CN100575103C - Image forming apparatus with a plurality of image forming units - Google Patents

Abstract

An image forming apparatus is disclosed which can detect the width and leading edge of a recording medium with a simple structure, thereby preventing erroneous printing. The carriage has a recording head to form an image by scanning the recording medium. A detector is provided on the carriage so as to detect a leading edge of the recording medium.

Description

imaging device

technical field

The present invention relates generally to an image forming apparatus, and more particularly, to an image forming apparatus that forms an image using inkjet technology such as an inkjet recording apparatus.

Background technique

As an image forming apparatus (which may be called an image recording apparatus) such as a printer, a facsimile or a copying machine is a known inkjet recording apparatus. The inkjet recording apparatus performs a recording job (image formation) by ejecting ink droplets onto a recording medium from an inkjet recording head, and the ink droplets adhere to a recording medium such as recording paper or overhead projector (OHP) film. The inkjet recording apparatus has advantages in that fine image recording can be performed at high speed, the running cost is low, there is less noise, and color images can be easily recorded by using multi-color inks.

In an inkjet recording device, generally, a recording head is a device for forming an image, and the recording head is mounted on a carriage so as to form an image by moving the carriage while feeding a recording medium. In such an inkjet recording apparatus, it is important to acquire information related to the position and size of the recording medium. By accurately acquiring the position information of the recording medium, recording (imaging) can be started at an accurate position, which improves image quality.

Especially in an inkjet recording apparatus that uses a conveyor belt to convey a recording medium, if ink droplets are ejected from the recording head at a position other than the recording medium, the ink droplets may be dropped on the conveyor belt, which will cause There is a problem that the back side of the recording medium is contaminated.

Japanese Laid-Open Patent Application No. 2000-94782 discloses an inkjet recording apparatus having a sensor for measuring the length of a recording medium so that the length of the recording paper can be detected in the conveying direction of the recording paper.

Moreover, conventionally, the detection of the recording medium reaching the imaging portion (recording portion), also known as leading edge detection, is performed by judging the conveyance amount of the recording medium or by detecting the leading edge by a sensor located at a fixed position. and achieved.

However, when the leading edge detection is performed according to the transport amount of the recording medium, it is difficult to precisely control the position of the recording medium because of the influence of physical errors such as fluctuations of the recording medium or recording during transport performed by the transport mechanism. The position of the medium has drifted. Furthermore, when the recording medium is detected by a sensor mounted at a fixed position, the position of positioning the sensor needs to be reserved with respect to the size of the recording medium, which may have undesired effects on the mechanical layout of the device.

In addition, detection of the recording medium width has the same problem. That is, when the recording operation is performed according to the printing instruction from the personal computer, if the end of the recording medium is cut off or folded, there will be a problem that the recording operation will only be performed according to the printing instruction from the personal computer. Execution, the recording operation will be performed at a location where no recording medium exists. Furthermore, similar problems may arise if the recording medium is conveyed in an oblique position or if the end portion of the recording medium is cut off. Therefore, it is preferable to dynamically detect the width of the recording medium.

Meanwhile, as an energy generating device for ejecting ink droplets, there are known various types of inkjet recording devices, such as a piezoelectric actuator type using a piezoelectric element, a thin film using a liquid generated by an electrothermal conversion element, etc. Thermal actuator types that change phases caused by boiling, shape memory alloy actuator types that use phase changes in metals caused by temperature changes, etc. Generally, an inkjet recording apparatus which forms an image by scanning a carriage on which a recording head as a recording means is mounted is provided with sensors for detecting the position and velocity of a carriage to obtain higher accuracy.

For example, Japanese Laid-Open Patent Application No. 2000-198244 discloses a recording device having an encoder scale and an encoder sensor for detecting the position and moving speed of a carriage. In addition, Japanese Laid-Open Patent No. 2001-239704 discloses a device having a light emitting device for emitting infrared light and a light receiving device for receiving the emitted infrared light provided so that the The detection is performed to control the driving timing of the recording head. In addition, in an apparatus that forms an image by scanning a carriage on which a recording head is mounted, the external environment is detected by a sensor mounted on a housing portion that is not scanned during image formation.

However, when the sensor is installed on the housing part to detect the external environment or the internal environment of the device, the detection result of the sensor may be different from the environment around the recording head, which may cause the detection result to inherently include errors. question. Therefore, the driving waveform of the recording head may be changed or the driving current supplied to the carriage driving device may be changed due to changes in the environment. However, there is a problem that such changes cannot always be controlled with sufficient precision.

Furthermore, in an image forming apparatus that conveys a recording medium by a conveyor belt so as to keep the recording medium flat, especially when a rubber material, which has thermal deformation greater than that of a metal material, is used to drive a driving roller of the conveyor belt, the travel of the conveyor belt The amount fluctuates due to fluctuations in the diameter of the driving roller, which is caused by changes in temperature, even though the rotational speed of the driving roller is constant. Therefore, the accuracy of the ink droplet decreases, which causes a problem of image quality degradation or fluctuation.

In addition, when the recording medium is conveyed using a conveyor belt, if ink droplets stick to the conveyor belt, the back side of the recording medium may become dirty or leakage of charges on the conveyor belt is likely to occur. If leakage occurs, the attractive force against the recording medium decreases, which causes a problem that normal conveyance cannot be performed.

Meanwhile, Japanese Laid-Open Patent Application No. 7-179248 discloses a recording apparatus that performs correct paper width detection based on the kind of recording paper detected by a paper width sensor provided in a tray. In addition, Japanese Laid-Open Patent Application No. 8-332738 discloses a recording apparatus having an ink amount detection sensor for detecting the amount of ink stored in a waste ink storage portion commonly used to detect recording Paper width sensor for media width. In addition, Japanese Laid-Open Patent Application No. 2002-301845 discloses a recording apparatus that detects an initial position of a recording head by an optical sensor mounted on a carriage. In addition, Japanese Laid-Open Patent Application No. 2001-10151 discloses a recording apparatus provided with a sensor for detecting the leading edge of a recording sheet located on the upstream side of a feed roller for feeding the recording sheet to a recording head, The apparatus is also provided with a sensor for detecting the trailing edge of the recording paper mounted on the carriage on which the recording head is mounted. In addition, Japanese Laid-Open Patent Application No. 5-131729 and No. 6-30933 disclose a recording apparatus provided with a sensor in a tray for detecting the presence of recording paper so that The sensor detects the same position as the recording head so that the sensor detects the width and trailing edge of the recording paper. Also, Japanese Laid-Open Patent Application No. 2002-265118 discloses an image forming apparatus provided with a paper sensor that detects the leading edge and/or trailing edge of recording paper near the entrance of a conveying roller that conveys the the recording paper described above.

As described above, in an apparatus for forming an image on a recording medium by scanning the recording medium in the main scanning direction and the sub-scanning direction perpendicular to the main scanning direction, there are many known devices that can An optical sensor is provided on the shelf or an initial position (initial position) of the carriage is set to detect the width and position of the recording medium. However, each conventional imaging device only detects the position of the recording medium or the initial position of the tray through an optical sensor provided on the tray. Therefore, it is difficult to obtain detailed information on where the recording medium is on the conveyance path, or to distinguish the kind of recording medium (plain paper, glossy paper, or OHP film). Therefore, it is difficult to optimize various controls due to differences in recording media.

In addition, when the recording medium is conveyed using a conveyor belt, if ink droplets adhere to the conveyor belt, the back side of the recording medium may become dirty or the charge on the conveyor belt may leak. If a leak occurs, the attractive force against the recording medium is reduced, which prevents proper conveyance. However, conventional imaging devices cannot deal with this problem. In addition, since the conventional device only detects the presence or absence of the recording medium through an optical sensor, it is difficult to obtain sufficient information from the outside of the recording medium.

As described above, in an image forming apparatus that records an image by ejecting ink droplets, it is important to acquire accurate information on the recording medium on which the ink droplets land. Particularly, in an apparatus in which a recording medium is conveyed by a conveyor belt so that the flatness of the recording medium is improved during conveyance, if ink droplets are ejected from a position of the recording head toward the outside of the recording medium, the ink droplets may drip onto the conveyor belt. Therefore, there is a problem that the back side of the recording medium may be soiled or the electrostatic attractive force against the recording medium conveyed by the conveyor belt may decrease.

Contents of the invention

It is an object of the present invention to provide an image forming apparatus in which the above-mentioned problems are eliminated.

A more specific object of the present invention is to provide an image forming apparatus which can detect the leading edge and width of a recording medium with a simple structure, thereby avoiding recording errors.

Another object of the present invention is to provide an image forming apparatus capable of performing precise control of conveyance of a recording medium by detecting the state of an inner or peripheral portion of a carriage having a recording head.

Another object of the present invention is to provide an image forming apparatus capable of performing precise control of conveyance of a recording medium by dynamically detecting the state of an inner or peripheral portion of a carriage having a recording head.

Another object of the present invention is to provide an image forming apparatus capable of controlling ejection of ink droplets so as to prevent the ink droplets from adhering to a position outside a recording medium.

In order to achieve the above object, according to one aspect of the present invention, there is provided an imaging device for forming an image on a recording medium, the device comprising: a carriage having a recording head to form an image by scanning the recording medium; Detector for the leading edge of the media.

According to the above invention, since the detector for detecting the leading edge or width of the recording medium is provided on the carriage, the detection of the leading edge or width of the recording medium can be realized with a simple structure, and recording errors can be prevented.

The imaging device according to the invention may also comprise an analog processing circuit which transmits the output signal of said detector. Optionally, the imaging device according to the invention may also comprise a digital processing circuit which transmits the output signal of said detector.

In addition, in the image forming apparatus according to the present invention, the detector may be located at a position where the recording medium can be detected upstream of the imaging start position by the recording head in the recording medium transport direction. , when the carriage is in the initial position, the detector can also be located at one side of the imaging area.

According to another aspect of the present invention, there is provided an image forming apparatus for forming an image on a recording medium, the apparatus comprising: a carriage having a recording head so as to form an image by scanning the recording medium; A detector that detects the width of the recording medium in the direction.

The imaging device according to the above invention may further include an analog processing circuit that transmits the output signal of the detector. Optionally, the imaging device according to the invention may also comprise a digital processing circuit which transmits the output signal of said detector.

In the image forming apparatus according to the above invention, the detector detects the width of the recording medium only when scanning is performed for the first time. In addition, in the image forming apparatus according to the above-mentioned invention, the detector may be located at a position where the recording medium can be detected upstream of the imaging start position by the recording head in the direction in which the recording medium is transported. , when the carriage is in the initial position, the detector can also be located at one side of the imaging area.

Furthermore, according to another aspect of the present invention, there is provided an image forming apparatus for forming an image on a recording medium, the apparatus comprising: a carriage having a recording head that forms an image by scanning the recording medium; A state detector for detecting the state of the part is mounted on the bracket.

According to the present invention described above, the state detector is provided on the carriage, the detector detecting the state inside the carriage or the state of the area around the carriage. Therefore, control based on the detection result of the state inside the carriage or the state of the region around the carriage can be performed with high precision.

In the imaging device described above, the state detector includes an optical sensor having a light-emitting element that emits light and a light-receiving element that receives light emitted from the light-emitting element. The light emitting element and the light receiving element may be integrated with each other.

The image forming apparatus according to the above-mentioned invention further includes a conveyor belt that conveys the recording medium. The image forming apparatus according to the above invention further includes a control section that determines whether or not the conveyor belt is dirty based on the detection result of the state detector. The status detector may include an infrared light sensor. Optionally, the status sensor may include a temperature sensor that detects the temperature of the area surrounding the carriage.

The image forming apparatus described above may further include: a conveying belt conveying the recording medium; a driving roller driving the conveying belt; and a control part correcting a rotation amount of the driving roller according to a detection result of the state detector.

The imaging apparatus described above may further include: a control section that changes a driving waveform applied to the recording head according to a detection result of the state detector.

The image forming apparatus described above may further include: a driving section that drives the carriage; and a control section that changes a driving waveform applied to the recording head according to a detection result of the state detector.

Furthermore, according to another aspect of the present invention, there is provided an image forming apparatus for forming an image on a recording medium, the apparatus including: a carriage having a recording head to form an image by scanning the recording medium; The optical sensor is a status detector that detects the status of the surrounding parts of the bracket.

According to the present invention described above, since the state sensor includes the optical sensor provided on the carriage to detect the state around the carriage, optimal control can be performed based on the detection result of the optical sensor.

In the imaging device according to the above invention, the state detector may determine the kind of the recording medium based on the detection result of the optical sensor. In addition, the type of recording medium can be determined based on the analog output level of the optical sensor.

The image forming apparatus according to the above invention may further include a conveying member that conveys the recording medium by attaching the recording medium to a predetermined surface area of the conveying member; wherein the state detector may detect the surface state of the conveying member. The conveying element can be an endless conveyor belt. In addition, the state detector can detect stains on the conveyor belt based on the detection result of the optical sensor. Also, the state detector can detect breakage of the conveyor belt based on the detection result of the optical sensor.

In the image forming apparatus according to the above-mentioned invention, the constituent parts other than the conveying part, which appear in the detectable area of the state detector, may have a color density level different from that of the recording medium conveyed by the conveying belt. to transport the recording medium. Furthermore, the color density level of constituent parts other than the conveying part may be different from the color density grade of the conveying part.

In addition, according to another aspect of the present invention, there is provided an imaging device for forming an image on a recording medium, the device comprising: a carriage having a recording head to form an image by scanning the recording medium; an optical sensor mounted on the carriage ; Constituent parts different from the conveying part, which appear in the detectable area of the optical sensor to convey the recording medium, the constituent parts having a color density level different from that of the recording medium conveyed by the conveying part. The color density grade of the constituent parts other than the conveying part is different from the color density grade of the conveying part.

Furthermore, according to another aspect of the present invention, there is provided an image forming apparatus including: a carriage having a recording head ejecting ink droplets on a recording medium to form an image on the recording medium; and a state detector, The detector detects the presence or absence of a recording medium along the moving path of the carriage, wherein when the carriage is moved in the main scanning direction to perform a printing operation, part of the printing operation after the state detector detects the absence of the recording medium got canceled.

In the image forming apparatus according to the above invention, the state detector may be provided upstream of the carriage in the main scanning direction so that the recording medium is detected by the state detector in the initial scan of the carriage for printing. After a position that does not exist, part of the print operation is canceled in the main scanning direction. In addition, the state detector may be provided upstream of the carriage in the main scanning direction, for each main scanning of the carriage for printing, when a position where the recording medium does not exist is detected, at Cancels part of the print operation in the main scanning direction.

In the image forming apparatus according to the above invention, a plurality of heads may be provided in the recording head so as to eject ink droplets in a plurality of colors by being arranged in the main scanning direction, and the main scanning of the carriage is performed at different positions of the recording medium. Continuing after the presence is detected by the status detector, the printing operation of each of the heads is phased out as the carriage is moved in the main scanning direction. In addition, according to the adjustment value related to each interval between the heads, after the absence of the recording paper is detected, the amount of movement of the carriage in the main scanning direction and the gradual cancellation of the printing operation of the heads are controlled. control.

In the image forming apparatus according to the present invention described above, a plurality of nozzle devices may be provided in the recording head so that ink droplets are ejected in a plurality of colors by being arranged in the main scanning direction, and the main scanning of the carriage is performed on the recording medium. Continues after the absence of is detected by the status detector, whereby the printing operation of each nozzle arrangement is phased out when the carriage is moved in the main scanning direction.

In the image forming apparatus according to the above invention, the carriage is bidirectionally movable so as to perform bidirectional printing, and when a part of the printing operation in one direction is canceled, corresponding to the printing operation in the one direction Part of the printing operation in a certain area that is canceled is also canceled in the printing operation in the other direction.

In the image forming apparatus according to the above invention, the carriage is bidirectionally movable so as to perform bidirectional printing, and the state detector is provided on each side of the carriage in the main scanning direction.

In the image forming apparatus according to the above invention, the state detector may be provided upstream of the carriage in the feeding direction of the recording medium, and detect when the state detector scans the carriage in the main scanning direction. After reaching the edge of the recording medium, the printing operation starts, and the state detector detects the edge of the recording medium for each main scan of the carriage to determine the edge position of the recording medium for use in subsequent line printing operations.

In the image forming apparatus according to the above invention, a plurality of heads may be provided in the recording head so as to eject ink droplets in a plurality of colors by being arranged in the main scanning direction, and beyond the edge of the recording medium detected by the state detector, The main scan of the carriage can continue, phasing out the print operation of the head.

In the image forming apparatus according to the above invention, according to the adjustment values related to the respective intervals between the heads, after each head has passed the edge of the recording medium, the amount of movement of the carriage in the main scanning direction and the amount of movement of the heads Cancellation of print operations is gradually controlled.

In the image forming apparatus according to the above-mentioned invention, a plurality of nozzle rows may be provided in the recording head so as to eject ink droplets in a plurality of colors by being arranged in the main scanning direction, and exceeding the recording medium detected by the state detector. edge, the main scan of the carriage can continue, thereby phasing out the print operation of the head.

In the image forming apparatus according to the above invention, the state detector may be provided at a position corresponding to a nozzle row closest to an edge of the recording head in the main scanning direction.

In addition, the image forming apparatus according to the above invention may further include a conveyor belt that conveys the recording medium by electrostatically attracting the recording medium to the surface of the conveyor belt.

Other objects, features and advantages of the present invention will become more apparent with reference to the accompanying drawings and the following detailed description.

Description of drawings

1 is a structural diagram of an inkjet recording apparatus, which is an example of an image forming apparatus according to a first embodiment of the present invention;

Fig. 2 is a plan view of a part of the ink jet recording apparatus shown in Fig. 1;

Fig. 3 is a perspective view of a part of the ink jet recording apparatus shown in Fig. 2;

Fig. 4 is a block diagram of the entire control section of the inkjet recording apparatus shown in Fig. 1;

Fig. 5 is the flowchart of a process that is carried out by control part;

Fig. 6 is a plan view of a certain part provided with an optical sensor;

FIG. 7 is a plan view of the part provided with the photosensor;

Fig. 8 is a plan view of said part provided with said light sensor in different positions;

Fig. 9 is a circuit diagram of a certain circuit when a reflective light sensor is used;

Figure 10 is a graph of output signals from the reflective light sensor shown in Figure 9;

FIG. 11 is a diagram showing variations occurring in the output signal due to differences in reflection factors of recording media;

12 is a circuit diagram of another example of the circuit using the reflective light sensor;

13A is a plan view of a part provided with an optical sensor for explaining recording paper width detection;

Figure 13B is a graph showing changes in sensor output signals with respect to time;

14 is a structural diagram of an inkjet recording apparatus, which is an example of an image forming apparatus according to a second embodiment of the present invention;

Fig. 15 is a block diagram of the entire control portion of the inkjet recording apparatus shown in Fig. 14;

Fig. 16 is a flowchart of a dirt detection process executed by the control section;

Fig. 17 is a flow chart of the temperature correction control process executed by the control section;

FIG. 18 is a graph showing a driving waveform pattern used in temperature correction control;

Fig. 19 is a flow chart showing the temperature correction control process of the feed amount executed by the control section;

Fig. 20 is a partial cross-sectional view of a housing housing a bracket and a guide;

Fig. 21 is a part of an inkjet recording apparatus according to a third embodiment of the present invention;

22 is a block diagram of a control portion of an inkjet recording apparatus according to a third embodiment of the present invention;

23 is a flowchart of a printing process performed by an inkjet recording apparatus according to a third embodiment of the present invention;

Fig. 24 is a flow chart of a certain process of detecting stains and/or damage on the surface of the conveyor belt according to the detection results of the state detection sensor;

Figure 25 is a bottom view of a recording head having a plurality of heads;

Figure 26 is a bottom view of a recording head having a plurality of nozzle devices;

27 is a flowchart of a first example of print control performed by the inkjet recording apparatus according to the fourth embodiment of the present invention;

Fig. 28 is a diagram showing a printing example;

Fig. 29 is a diagram showing a printing example;

Fig. 30 is a diagram showing a printing example when the paper is inclined;

Fig. 31 is a diagram showing a printing example;

32 is a flowchart of a second example of print control performed by the inkjet recording apparatus according to the fourth embodiment of the present invention;

Fig. 33 is a diagram showing a printing example;

Fig. 34 is a diagram showing a printing example;

Figure 35 is a bottom view of a recording head having a plurality of heads;

Fig. 36 is a diagram showing a printing example;

37 is a flowchart of a third example of print control performed by the inkjet recording apparatus according to the fourth embodiment of the present invention;

Fig. 38 is a diagram showing a printing example;

Fig. 39 is a diagram showing a printing example;

Figure 40 is a bottom view of a carriage with two status detection sensors;

Fig. 41 is a bottom view of the carriage with the status detection sensor upstream in the sheet feeding direction;

42 is a flowchart of print control performed by the inkjet recording apparatus having a state detection sensor upstream of the carriage in the sheet feeding direction;

Fig. 43 is a diagram showing a printing example;

Fig. 44 is a bottom view of the carriage with the state detection sensor upstream of the carriage in the main scanning direction and the sheet feeding direction.

Detailed ways

Various embodiments of the present invention will be described below with reference to the accompanying drawings.

(first embodiment)

FIG. 1 is a structural diagram of an inkjet recording apparatus, which is an example of an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is a plan view of a part of the ink jet recording apparatus shown in FIG. 1. FIG. FIG. 3 is a perspective view of a part of the ink jet recording apparatus shown in FIG. 2. FIG.

The inkjet recording apparatus shown in FIG. 1 includes guide rods 1 and guide rails 2 which together slidably support a carriage 3 which is driven by a main scanning motor 4 via a timing belt 5 to move as shown in FIG. Move in the direction of the arrow (main scanning direction) shown. The guide rod 1 and the guide rail 2 are guide elements that bridge between left and right plates (not shown in the drawings) of the inkjet recording apparatus.

The carriage 3 is provided with a recording head 7 having four inkjet heads which eject ink droplets of yellow (Y), cyan (C), magenta (M) and black (BK), thereby using the recording head 7 The plurality of ink outlets are arranged in a direction perpendicular to the main scanning direction, and the ink droplets are ejected in a downward direction.

The inkjet head constituting the recording head 7 may be of a piezoelectric actuator type using a piezoelectric element, may be of a thermal actuator type using phase shift caused by film boiling of a liquid by an electrothermal conversion element, may be Of the shape memory alloy actuator type using a metal phase change caused by temperature change, may be of the electrostatic actuator type using electrostatic force, and the like.

A sub cartridge 8 for each color is mounted on the carriage 3 so that the ink of each color is supplied to the recording head 7 . Ink is supplied from the main tank (ink carriage) to each sub-tank 8 through an ink supply tube (not shown in the drawings).

A paper feeding part that feeds recording paper 12 placed on a paper setting part 11 of a paper supply cassette 10 includes a woodruff roller 13 (feeding roller) and a separation pad 14 that is pushed toward the feeding roller 13. . The feed roller 13 separates and feeds the recording paper 12 from the paper placement member 11 on a single recording paper basis. The separation pad 14 is made of a material having a high coefficient of friction. In addition, as conveying means for conveying the paper fed from the paper feeding portion under the recording head 7 , a conveying belt 21 , a reverse roller 22 , a conveying guide 23 and an end pressure roller 25 are provided. The conveying belt 21 conveys the recording paper 12 by attracting the recording paper thereon by electrostatic force. The reverse roller 22 pinches each recording sheet 12 together with the conveyance belt 21 to convey each recording sheet 12 , which is fed from the sheet feeding portion through the guide 15 . The guide 23 causes each recording sheet 12 fed upward to rotate about 90 degrees so that each recording sheet 12 closely follows the conveying belt 21 . The end pressing rollers 25 are pushed towards the conveyor belt 21 by the pressing piece 24 . In addition, there is provided a charging roller 26 which is charging means for charging the surface of the conveyor belt so as to generate an electrostatic attraction force.

The conveyor belt 21 is an endless belt that cooperates with the conveyor roller 27 and the tension roller 28 so that the conveyor roller 21 rotated by the sub-scanning motor 31 via the timing belt 32 and the timing roller 33 moves in the direction shown in FIG. 2 (belt (paper) conveyance direction). ) to rotate.

The conveyor belt 21 has a front layer and a rear layer. The front layer is formed of a pure resin material that is not drag controlled and has a thickness of about 40 microns, such as ETFE pure resin. The front layer acts as a paper attracting surface. The rear layer is formed of the same material as the front layer, but resistance control is performed by adding carbon. The rear layer can serve as an intermediate resistive layer or a ground plane.

The conveying roller 27 and the counter roller 22 together form the conveying nip portion 18 . A paper detection sensor 16 is located at a predetermined position upstream of the transport nip portion 18 in the paper transport direction so as to detect each recording paper 12 . The paper detection sensor 16 detects each recording paper 12 through a detection lever 17 deflected by each recording paper 12 . The position indicated by the dotted line in FIG. 1 shows the ON position of the detection lever 17 . It should be noted that a paper detection sensor 16 is provided for detecting each recording paper 12 that is fed.

The charging roller comes into contact with the conveyor belt 21 to rotate due to the movement of the conveyor belt 21 . At each axial end of the charging roller 26, the charging roller 26 was applied with a pressure of 2.5N. The conveying roller 27 also serves as a ground roller, which is in contact with the middle resistive layer (rear layer) of the conveying belt 21 .

The guide 36 is located on the back side of the conveyor belt 21 relative to the printing area of the recording head 4 . The upper surface of the guide 36 thus protrudes toward the recording head tangent to the two rollers (the conveyance roller 27 and the tension roller 28 ) supporting the conveyance belt 21 . Therefore, the conveyor belt 21 is lifted and guided by the upper surface of the guide 36 in the printing area.

In order to detect the end of the recording paper 12 conveyed by the conveying belt 21, a paper sensor 41 comprising a reflective light sensor, which is a detector or detection means, is provided on the carriage 3 shown in FIG. When the carriage 3 is in the initial position shown by the solid line in FIG. 3, the paper sensor 41 is located at a certain position on the side of the recording area or the image forming area (on the side of the conveyor belt 21).

A code scale 42 having a cutout formed therein is provided on the front side of the bracket 3 , and a code sensor 43 including an emission type light sensor is provided on the front side of the bracket 3 so as to detect the cutout of the code scale 42 . The encoder scale 42 and the encoder sensor 43 constitute an encoder 44 that detects the position of the carriage (position relative to the initial position) in the main scanning direction.

In addition, as a paper discharge member for discharging the recording paper recorded by the recording head 7, there is provided a separating member for separating each recording paper 12 from the conveyance belt 21, and paper discharge rollers 52 and 53 and A paper discharge tray for accommodating the discharged recording paper 12 .

In addition, a double-sided sheet feeding unit 61 is detachably attached to the back of the inkjet recording apparatus. The double-sided paper feeding unit 61 returns each sheet of recording paper 12 by the reverse rotation of the conveying belt 21, and turns over the returned recording paper 12, and feeds the recording paper 12 to the reverse roller 22 and the conveying belt 21. a position in between.

In the inkjet recording apparatus having the above structure, each recording sheet 12 is separated from the sheet supply part and fed, each recording sheet 12 fed upward in the vertical direction is guided by the guide 15, each recording sheet 12 is fed while being sandwiched between the conveying belt 21 and the reverse roller 22, and then, the end of each recording sheet 12 is guided by the conveying guide 23 and pressed against the conveying belt 21 by the end pressing roller 25, The direction of delivery is thus changed by approximately 90 degrees.

At this time, an alternating voltage is applied to the charging roller 26 from a high voltage power source through a control circuit (not shown), so that positive output and negative output are repeatedly applied to the charging roller 26 . Accordingly, the conveying roller 21 is charged with an alternating charging voltage so that positive and negative charges are arranged in an alternating pattern in the sub-scanning direction, which is the direction of rotation of the conveying belt 21 . When the recording paper 12 is fed onto the conveyor belt 21 , which is charged in an alternating positive and negative pattern, polarized charges are generated in the recording paper 12 to form charges opposite to the charge pattern of the conveyor belt 21 . Therefore, the recording paper 12 is conveyed by the conveyance belt 21 rotating in the sub-scanning direction.

Therefore, when the recording paper is stopped, by driving the recording head 7 according to the image signal while moving the carriage 3, recording of one line is performed by ejecting ink droplets on the recording paper 12, and then, while the recording paper is conveyed at a predetermined distance After that, the recording of the next line is executed. Upon receipt of a recording end signal or a signal indicating that the trailing edge of the recording paper 12 has reached the recording area, the recording operation is stopped and the recording paper 12 is discharged on the paper discharge tray 44 .

In the case of double-sided printing, the conveyance belt 21 is reversed after printing on the front side (the side printed for the first time) is completed, thereby feeding the recording paper 12 to the double-sided paper feeding unit 61 . Thereafter, the recording paper 12 is reversed (setting the rear side as the surface to be printed on) and fed to a position between the reverse roller 22 and the conveyor belt 21 . Then, recording on the back side is performed by conveying the recording paper 12 to the conveyance belt 21 while timing control is performed, and thereafter, the recording paper 12 is discharged onto the paper discharge tray 44 .

Referring to Fig. 4, description will be made on the control section of the inkjet recording apparatus. FIG. 4 is a block diagram of the entire control portion of the ink jet recording apparatus shown in FIG. 1. Referring to FIG.

The control section includes: a printer controller 70; a motor driver 81 for driving the main scanning motor 4 and the sub-scanning motor 31; a driver 82 for transmitting the driving force of the sub-scanning motor 31 to the feed roller 13; The recording head driver 84, such as a driving circuit and a driving IC, is used to drive the recording head 7 (ink jet head).

The printer controller 70 includes: an interface for receiving print data and command signals from an information processing device such as a personal computer, an image reading device such as an image scanner, and an image acquisition device such as a digital camera through a cable or a network (hereinafter referred to as I/F); Main control part 73 comprises central processing unit (CPU); Random access memory (RAM) 74 is used to store various data; Read-only memory (ROM) 75 is used to store the program that is used to process various data a driving signal generation circuit 77 that generates a driving waveform for the recording head 7; an interface 78 for transferring the driving waveform and printing data converted into dot matrix data (bitmap data) to the recording head driver 84; Motor drive data is transmitted to a motor driver 81 and an interface (I/F) 79 for transmitting a clutch ON signal to a driver 82 .

The RAM 74 serves as a cache for various data and also as a work memory. The ROM 75 stores various control programs executed by the main control section 73, font data, graphic functions, and various programs.

The main control portion 73 performs paper feeding control based on a detection signal from the paper detection sensor 16 . Also, the main control section 73 detects the position of the carriage 3 in the main scanning direction based on the output signal of the encoder 44, thereby performing control of the stop position of the carriage 3, and also detects the position of the leading edge of the recording paper 12. , and detecting the presence or absence of the recording paper 12 on the conveying belt 21 .

The main control section 73 reads and analyzes the print data stored in the receiver buffer in the I/F 72 , and stores the analysis result in a predetermined area of the RAM 74 . Then, the main control section 73 will generate dot matrix data to be output by using the font data stored in the ROM 75 according to the stored analysis results, and store the dot matrix in a different area of the RAM 74 . It should be noted that when the image data is transferred to the recording device after the image data is converted into bitmap data by the print driver on the host side, the received bitmap image data is only stored in the RAM 74 .

After acquiring the dot pattern corresponding to one line of the recording head, the main control section 73 transmits the dot pattern as serial data corresponding to one line to the recorder through the I/F 78 synchronized with the clock signal CLK from the oscillation circuit 76. head driver 84, and transmits a lock signal (latch signal) to the recording head driver 84 at a predetermined timing.

The drive signal generation circuit 77 includes a ROM storing a drive waveform (drive signal), an amplifier, and a waveform generation circuit including a D/A converter that converts drive waveform data read from the ROM. The ROM can be constituted by ROM75.

Described head driver 84 comprises: shift register, its input clock signal and serial data, and this serial data is sent from main control part 73; A lock circuit, this circuit is controlled by the lock signal from main control part 73 a registered value of a latch shift register; a level conversion circuit (level register) that performs level change of an output value of said latch circuit; and an analog switch array (switching device) that is turned on by the level register and off. The head driver 84 selectively applies a desired driving waveform included in the driving waveform to the recording head 7 by controlling ON/OFF of the analog switch array.

It should be noted that the printer controller can exchange instruction information and display information with an operation/display section 86 through the I/F 72.

Printing control performed by the main control portion 73 will be described with reference to FIGS. 5 to 7. FIG.

First, at step S1, prior to paper feeding, the main control section 73 drives the main scanning motor 4, thereby moving the carriage 3 at the non-recording position as shown in FIG. direction to the middle portion of the conveyor belt 21 (or the center of the recording paper to be fed). Then, in step S2 , the main control portion 73 turns on the paper supply clutch, thereby transmitting the driving force of the sub-scanning motor 31 to the feed roller 13 . Accordingly, the feed roller 13 makes one revolution in the clockwise direction, the recording paper 12 is separated by the friction pad 14 and fed from the paper supply tray 10 .

Then, in step S3, by detecting the detection signal of the paper sensor 41, the main control portion 73 determines whether or not the leading edge of the recording paper 12 is detected. After the leading edge of the recording paper 12 is detected, the recording paper 12 is conveyed to the printing start position and stopped there in step S4. It should be noted that in this case, as shown in FIG. 8, if the paper sensor 41 is at a position where the leading edge of the recording paper 12 can be detected upstream of the printing area (image forming area) in the conveyance direction, Even if a detection position error occurs in the detection of the leading edge of the recording paper 12, the recording paper 12 can be surely moved to the printing start position. Therefore, even when printing is started from the leading edge of the recording paper 12, it does not happen that erroneous printing is performed on the conveying belt.

Thereafter, in step S5 , the carriage 3 is temporarily returned to the initial position, and movement of the carriage 3 toward the recording area is started according to the output of the encoder 44 . At this time, the main control portion 73 determines whether or not the recording paper 12 is present by detecting the detection signal of the paper sensor 41 in step S7. If there is the recording paper 12, desired printing (recording operation) is performed in step S8. If no paper 12 is detected, the recording operation will not be performed.

Then, in step S9, the stop of the printing operation is determined. If the printing operation is not stopped, go back to step S7 to resume the printing operation. Otherwise, the procedure proceeds to step S10 so that the recording paper 12 is ejected, and the printing operation is stopped.

Therefore, printing (ejecting ink droplets) is not performed at a position where there is no recording paper 12, that is, ink droplets are prevented from being ejected onto the conveying belt 21, which prevents the conveying belt 21 and the recording paper 12 from becoming dirty.

A description will be given of the procedure when using the reflective photosensor as the sheet sensor 41 . The reflective light sensor is an element that converts the amount of light into an output voltage. The reflective photosensor is installed facing the recording paper so that the presence or absence of recording paper can be detected by using a difference in reflected light amount due to a difference in reflectance between the conveyance belt 21 and the recording paper 12 .

FIG. 9 shows a circuit diagram of a certain circuit when a reflective light sensor is used. In the circuit shown in FIG. 9, the recording paper 12 on the conveyor belt 21 is driven by a reflective photosensor 41A having a light-emitting element 41Aa and a light-receiving element 41Ab, and from the reflective photosensor 41A through a voltage follower circuit (voltage follower circuit). ) 101 is determined by an electrical signal (output signal) output to the recording control IC 103 constituting the printer controller 70 that controls the recording operation.

That is, since the electric signal output from the sensor 41A is very small, the voltage tracking circuit 101 includes an operational amplifier having a high input impedance, thereby stabilizing the output level of the sensor 41A. In addition, the sensor and the recording control IC 103 are remote from each other in many cases, and, therefore, the voltage follower circuit can serve as a noise reduction means. In this case, the input of the recording control IC 103 is made to process analog signals, and an A/D converter is installed inside it to perform A/D conversion.

A description will be given of the advantages of relaying sensor output signals by analog signals. FIG. 10 is a view of the output signal from the reflective photosensor 41A. As shown in FIG. 10, it takes a certain time from the moment when the recording paper 12 reaches a certain position corresponding to the sensor 41 until the output signal reaches the threshold voltage Vref at which the recording control IC 103 determines that the recording paper is detected. Therefore, the accuracy of position detection varies depending on what voltage is set as the threshold voltage Vref.

Also, since the reflectance varies according to the size of the recording paper, the magnitude of the voltage output from the photosensor 41A varies according to the reflectance as shown in FIG. 11 . Therefore, by transmitting and processing the output signal of the sensor according to the analog method and setting the threshold voltage to a lower value, the accuracy of detection can be improved, and an optimal threshold can be set according to the kind of recording paper.

FIG. 12 is a circuit diagram of another example of a circuit using the reflective photosensor 41A. In the circuit configuration shown in FIG. 12, the recording paper on the conveying belt 21 is detected by the reflective photosensor 41A, and the electric signal (output signal) output from the photosensor 41A is input through the Schmitt trigger. The cache element 104 is output to the recording control IC 103.

That is, the circuit configuration shown in FIG. 12 is a digital processing circuit that transmits and processes the output signal of the photosensor according to a digital method. Although the output of the sensor 41A can be directly input to the recording control IC 103, the buffer element 104 is located close to the sensor 41A so that the output level of the sensor can be stabilized and noise can be reduced. The buffer element 104 uses a C-MOS type with high input impedance, and also uses a Schmitt trigger input type with hysteresis characteristics because the input is an analog signal.

By transmitting and processing the output signal according to a digital method, since the signal is transmitted by digital signals of "0" and "1", the circuit can be manufactured at low cost and prevented from being affected by noise. Therefore, as mentioned above, it is preferred to have a buffer element close to the sensor, for example on a bracket.

With reference to Figs. 13A and 13B, a description will be given of the detection of the recording paper width. Here, as described above, after the leading edge of the recording paper 12 is detected, the recording paper 12 is conveyed to a position where the sensor 41 can scan on the recording paper 12 . Then, as shown in FIG. 13A , the carriage 3 is moved in the X-axis direction (main scanning direction), thereby detecting an area where the recording paper 12 appears by the sensor 41 . Since the output from the sensor 41 varies according to the output signal conversion characteristic shown in FIG. 13B, and therefore, the width of the recording paper 12 can be detected by processing the output signal.

In this case, when a reflective photosensor is used as the sensor 41, the circuit configuration is the same as that shown in FIG. 9 or FIG. 12 . Also, the workload of the recording paper width detection process can be reduced by performing detection only once after the recording paper is conveyed.

It should be noted that although the description has been made for the above-mentioned embodiment in which the present invention is applied to a reciprocating inkjet recording apparatus using a carriage, the present invention is not limited to the described inkjet recording device. That is, for example, the present invention is applicable to a copier, a facsimile, a multifunctional machine combining a copying device, a printer, and a facsimile.

(second embodiment)

A description will be given of an imaging device according to a second embodiment of the present invention. Fig. 14 is a structural diagram of an inkjet recording apparatus, which is an example of an image forming apparatus according to a second embodiment of the present invention. In FIG. 14, the same components as those shown in FIG. 1 are given the same reference numerals and their descriptions are omitted.

The inkjet recording apparatus according to the second embodiment of the present invention basically has the same mechanical structure as the inkjet recording apparatus according to the above-described first embodiment shown in FIG. 1 except for the state sensor 41B. This sensor is used as a state detecting means for detecting the surrounding environment of the recording head 7 and the surface state of the conveyor belt 21, which is mounted on the carriage 3, and the description of components other than the state sensor 41B is omitted.

Fig. 15 is a block diagram of a printer controller 70A according to a second embodiment of the present invention. In FIG. 15 , the same components as those shown in FIG. 4 are given the same reference numerals, and descriptions thereof are omitted. The printer controller 70A has the same structure as the printer controller 70 shown in FIG. 4 except that a driver 88 for applying a high voltage to the charge roller 26 is provided.

A description will be given of the state sensor 41B, which is a detector or detection means for detecting the state of the environment around the recording head or the surface state of the conveyor belt 21 .

First, a description will be given of an example in which stains on the conveyor belt 21 are detected by using an optical sensor as the state detection sensor 41B. A reflective photosensor having a light emitting element and a light receiving element integrated with each other is suitable for an optical sensor because such a sensor has a simple structure. Also, if the conveyor belt is made of opaque material, the reflective light sensor is effective.

In this embodiment, as shown in FIG. 16, in step S21, the carriage 3 is moved to scan the surface of the conveying belt 21, thereby acquiring the image in the state where the recording paper 12 is not conveyed by the conveying belt 21 in step S22. The output of the state detection sensor 41B. Then, it is determined whether there is dirt on the conveyor belt 21 in step S23. Thereafter, it is determined in step S24 whether or not the entire surface of the conveyor belt 21 has been inspected. If the entire surface of the conveyor belt 21 has not been inspected, the procedure returns to step S21. On the other hand, if it is determined that the entire surface of the conveyor belt 21 has been inspected, the procedure proceeds to step S25. Then, in step S25, it is determined whether or not the conveyor belt 21 has become dirty. If it is determined that the conveyor belt 21 has become dirty, the program proceeds to step S26. In this step, the contamination of the conveyor belt 21 will be displayed on the operation/display part 86, thereby notifying the user to clean or replace the conveyor belt 21.

That is, if the surface of the conveying belt 21 becomes dirty due to the attachment of ink droplets, current leaks when the conveying belt 21 is charged, which results in insufficient electrostatic attraction, causing a conveyance error of the recording paper 12 . Alternatively, ink droplets on the conveyor belt 21 may be conveyed to the back of the recording paper 12, which causes the back of the recording paper 21 to become dirty. If duplex printing is performed on recording paper, dirt on the back side of the recording paper will cause image quality to deteriorate.

Therefore, in order to reduce the above-mentioned problems, if the conveyor belt 21 becomes dirty, a warning of the dirt is transmitted to the user, thereby preventing misfeeding or soiling of the recording paper.

Next, an explanation will be given of an example in which the environment is detected by using the temperature sensor as the state detection sensor 41B. When the ambient temperature changes, the viscosity of the ink changes accordingly, which results in a change in the ejection velocity of ink droplets or possibly a change in the volume of each ink droplet. In addition, the diameter or length of the structural elements of the drive system such as the timing belt and the wheels for driving the carriage 3 may change, resulting in fluctuations in the actual injection position even when the injection timing according to the drive waveform is the same. The transfer of the ink drop landing position.

Therefore, the processing shown in Fig. 17 is executed. First, in step S31, it is determined whether or not the recording paper 12 is fed. If the recording paper 12 is fed, the procedure proceeds to step S32, at which the ambient temperature is detected by using the state detection sensor 41 of the temperature sensor. Then, in step S33, it is determined whether the detected temperature is greater than a predetermined temperature Ta. If it is detected that the temperature is greater than the predetermined temperature Ta, the program proceeds to step S34. At this step, the drive waveform pattern A shown in FIG. 18 is selected and the pressure generating means of the recording head 7 is driven according to the selected drive waveform pattern A. . On the other hand, if the detected temperature is equal to or less than the predetermined temperature Ta, the program proceeds to step S35, at this step, the driving waveform pattern B shown in FIG. 18 is selected and the pressure generating means of the recording head 7 Driven according to the selected drive waveform pattern B.

Here, FIG. 18 shows an example of a driving waveform pattern. In particular, FIG. 18 shows the driving waveform pattern A applied when the detected temperature exceeds a predetermined temperature Ta (set temperature), and shows the driving waveform pattern A applied when the detected temperature does not exceed the predetermined temperature Ta. Drive waveform pattern B. It should be noted that a plurality of predetermined temperatures can be set, and the driving waveform pattern can also be set in a similar manner, and the driving waveform pattern data can be stored in a memory.

In addition, the piezoelectric element is an electrical-to-mechanical force conversion element, and when it is used as a pressure generating device of the recording head 7, temperature compensation can be performed by making the voltage value of the drive waveform pattern different. That is, the temperature compensation can be easily performed by switching between different waveform patterns according to the detected temperature. It should be noted that a thermal recording head or an electrostatic recording head can be used as the recording head 7, but these heads cannot be controlled with simple parameters of the drive waveform, such as voltage value or pulse width. On the other hand, a recording head using a piezoelectric element can be provided with a relatively large temperature compensation step width, and temperature compensation can be easily performed. Therefore, the storage capacity for the driving waveform data can be reduced, which reduces the capacity of the memory for storing the driving waveform pattern data.

In addition, although driving waveform pattern data for temperature compensation is initially stored in a storage device such as a ROM of a recording device, the driving waveform pattern data may be transferred from a printer driver of a host computer to the recording device.

In this case, since the temperature of a certain area near the recording head 7 is detected by the state detection sensor 41, more accurate temperature compensation can be performed with respect to the viscosity of the ink.

In addition, with respect to the carriage 3, it is possible to set a driving current corresponding to a temperature so that the driving current applied to the main scanning motor 4 is changed according to the detected temperature. Also in this case, since the temperature of a certain area near the carriage 3 is detected by the state detection sensor 41B, more accurate temperature compensation can be performed with respect to a change in scanning speed.

In addition, if a rubber roller or the line is used to drive the driving roller 27 (transporting roller) of the conveying belt 21 and when the ambient temperature changes, even when the rotation of the driving roller 27 is constant, the conveying The conveyance amount of the belt 21, that is, the movement amount of the recording paper 12 also changes.

Next, with reference to FIG. 19 , an explanation will be given on the process of controlling the conveying amount of the conveying rollers based on the detected temperature.

First, it is determined in step S41 whether or not the recording paper 12 is fed. If the recording paper 12 is fed, the procedure goes to step S42 where the main control portion 73 detects the ambient temperature based on the detection signal of the state detection sensor 41B, which is a temperature sensor. Then, the main control portion 73 performs a process of predicting the temperature of the conveying roller 27 based on the detected ambient temperature.

Subsequently, in step S43, the main control portion 73 calculates an error amount in the delivery amount (hereinafter referred to as "temperature feed error") from the predicted temperature. Here, the calculation of the temperature feed error is performed by calculating the temperature correction coefficient K _TC using the following formulas (1) and (2).

K _TC =d/[d+k(t-23)](1)

d＝32.34*[(25.4+c*10 ^-6 +u*10 ^-6 )/25.4](2)

It should be noted that in the above formula, "k" represents the temperature coefficient (=0.007[mm/°C]), "t" represents the detected temperature (predicted temperature), "d" represents the diameter of the conveying roller (23°C), "c" represents a process correction value, and "u" represents a user correction value.

Then, in step S45, the main control portion 73 corrects the rotation amount of the conveyance roller 27 by multiplying the feed amount of the recording paper 12 by the obtained temperature correction coefficient, thereby controlling the rotation of the conveyance roller 27 according to the corrected rotation amount.

As described above, by detecting the temperature related to the temperature of the conveying roller 27 for each page and correcting the rotation amount of the conveying roller 27 based on the detected temperature, even when the conveying roller 27 is made of a material such as rubber that is easily affected by temperature changes, Made of material, since fluctuations in the feeding amount of recording paper caused by temperature changes can be suppressed, thus obtaining stable image quality.

Hereinafter, with reference to FIG. 20 , the relationship between the device main body including the bracket 3 and the sensor serving as the state detection sensor 41B will be described. In a normal imaging device, as shown in FIG. 20, in order to prevent the user from contacting the moving elements when the carriage 3 moves, the carriage 3 and the guide member 1 are covered by a member or housing 90 to shield them from the outside world. It should be noted that the bracket 3 and the guide element 1 are not completely shielded, but the shielding element may have openings, windows or covers.

If the carriage 3 is housed in a shielding member such as the case described above, high detection accuracy can be obtained by using an optical sensor as the state detection sensor 41B. Also, if the light toward the carriage 3 is not completely cut off, more stable detection can be performed by using an infrared light sensor as the state detection sensor 41B.

(third embodiment)

An inkjet recording apparatus will be described, which is an example of an image forming apparatus according to a third embodiment of the present invention.

The ink jet recording apparatus according to the third embodiment of the present invention basically has the same structure as that according to the ink jet recording apparatus shown in FIG. 1, and the description of its entire structure is omitted.

In addition to the structure of the inkjet recording apparatus shown in FIG. 1, the inkjet recording apparatus according to this embodiment has a maintenance and restoration mechanism 94 as shown in FIG. 21 to maintain the state of the nozzles of the recording head 7, And restore the state of the nozzle when it degrades. Along the moving direction of the carriage 3, the maintenance and recovery mechanism 94 is located in the non-recording area outside the recording area, as shown in FIG. 21 . The maintenance and recovery mechanism 94 includes a cover member that covers the ink ejection surface of the recording head 7 and a wiper blade that wipes the nozzle surface.

Referring to Fig. 21, the control section of the ink jet recording apparatus according to the present invention will be described. Fig. 21 is a block diagram of the control section 100 of the inkjet recording apparatus according to the present invention.

Described control part 100 comprises: control the control processing unit 101 of whole device; Store the program that is carried out by CPU 101 and read-only memory (ROM) 102 of various fixed data; Temporarily store image information and other data random access memory (RAM) 103; non-volatile memory (NVRAM) 104, which retains data when the power of the device is turned off; application-specific integrated circuit (ASIC) 105, which performs image processing on image data, and the processing is used to control the entire Device input and output signals; an I/F 106, the signal is exchanged with the host side through the I/F 106; the recording head driver 108 and the recording head drive control part 107 for controlling the recording head 7; drive the main scanning motor 4 and a sub-scanning motor driving section 110 that drives the sub-scanning motor 31.

The control section 100 is connected to an operation panel 101 through which information required by the device is input and displayed. In addition, the control section 100 is supplied with a detection signal from the above-mentioned state detection sensor provided in the carriage 3 . The control section 100 receives print data and the like from an information processing device such as a personal computer, an image forming device such as an image scanner, an image capture device such as a digital still camera, etc. through the I/F 106.

The CPU 101 reads and analyzes the print data in the receive buffer provided in the I/F 86, and transfers the print data to the recording head drive control after applying required image processing and data rearrangement performed by the ASIC 105 Section 107. It should be noted that dot pattern data for outputting images can be performed by storing font data in the ROM 102. In addition, the image data becomes bitmap data by a printer driver on the host side, and thus prepared image data can be transferred to the inkjet recording apparatus.

Upon receiving the image data (dot matrix data) corresponding to one line of the recording head 7, the recording head drive control section 107 transmits the dot pattern data corresponding to one line to the recording head driver 108 in synchronization with a clock signal, and also The lock signal is transmitted to the recording head driver 108 at a predetermined timing.

The recording head driving control section 87 includes: a ROM (generally using the ROM 102) that stops (stores) the driving waveform pattern data (driving signal); and a driving waveform generating circuit including an amplifier and a waveform generating circuit, the waveform generating circuit A D/A converter is included which converts the drive waveform data read from the ROM into analog data.

Described recording head driver 108 comprises: shift register, and its input comes from the clock signal of recording head driving control part 107 and serial data, and this serial data is image data; the lock signal of the control section 107 locks the registered value of the shift register; the level conversion circuit (level register) that performs level change of the output value of the lock circuit; and the analog switch array (switching device), It is turned on and off by the level register. The recording head driver 108 selectively applies a desired driving waveform to the recording head 7 and drives the recording head 7 by controlling the on/off of the analog switch array.

Referring to FIG. 23, the detection process of the recording paper type by the control section 100 using the state detection sensor 41 will be described. 23 is a flowchart of a printing process including a recording paper type detection process that detects a recording paper type. In FIG. 23 , the same steps as those shown in FIG. 5 are given the same step numbers, and descriptions thereof will be omitted.

The process shown in FIG. 23 is basically the same as that in FIG. 5 except for step S50 between steps S4 and S5. When the printing process starts, the process of steps S1 to S4 shown in FIG. 5 is performed. Then, after the processing of step S4 is performed, the procedure proceeds to step S50.

In step S50 , based on the detection signal of the state detection sensor 41 , the type of the recording paper 12 is determined (detected). As the recording medium used in the inkjet recording apparatus, there are mainly plain paper, glossy paper, and overhead projector (OHP) film. Plain paper is widely used recording paper, which is inexpensive but may bleed or become dirty. Although glossy paper is more expensive than plain paper, it bleeds less or smudges less easily, and may yield higher print quality with this paper. The OHP film is used to prepare documents for presentation using a projector, and it is used less frequently than other recording papers, but does not bleed or smear or absorb ink.

As described above, since the characteristics of the ink attached to the recording medium depend on the type of the recording medium, generally, the printing characteristics are changed for each recording medium setting. In this case, the setting of the recording medium is generally performed by the user using the host computer, and therefore, if the user makes a mistake in the setting, the corresponding image quality cannot be obtained. However, if the kind of recording medium is automatically recognized, a corresponding image can always be formed. In this case, the analog output level of the state detection sensor 41 is used to discriminate the kind of recording paper. That is, when an optical sensor is used, based on the assumption that the relationship between recording media is, for example, plain paper < glossy paper < OHP film, analog output levels from the same optical sensor are in a similar relationship. Therefore, by detecting the difference between the analog output levels, discrimination of recording media can be performed with high precision.

An example in which the distinction is made will be described. The relationship between the analog output levels of the state detection sensor 41 and the type or kind of recording paper can be indicated by Table 1 below.

Table 1

Sensor output level Recording medium 0-1V No 1-2V plain paper 2-3V wax paper 4-5V OHP film

Therefore, the type or kind of recording paper 12 conveyed by the conveyance belt 21 can be detected by comparing the output of the state detection sensor 41 with a reference level set according to the type or kind of recording paper.

After the type or category of the recording paper is detected in step S50, the procedure proceeds to steps S5 to S10 to execute printing processing on the recording paper 12 as explained with reference to FIG. 5 .

As described above, optimal print control suitable for recording paper being conveyed can be performed by detecting the type or kind of recording paper by providing a state detection sensor (state sensor), particularly Reflective optical sensors are used to detect the state of the area around the carriage 3 . In this case, by performing detection of the type of recording medium based on the analog output level of the reflective optical sensor, it is possible to accurately distinguish the difference in the type of recording medium.

Referring to FIG. 24 , a process of detecting dirt and/or damage on the surface of the conveyor belt 21 based on the detection result of the state detection sensor 41 will be described.

As shown in FIG. 24, in step S61, the carriage 3 is moved to scan the surface of the conveyor belt 21 to obtain the output of the detection sensor 41 in the case where the recording paper 21 is not conveyed by the conveyor belt 21 in step S62. Then, in step S63, a determination is made as to whether or not the conveyor belt 21 is soiled or damaged. Thereafter, in step S64, it is determined whether the entire surface of the conveyor belt 21 is inspected. If the entire surface of the conveyor belt 21 has not been inspected, the procedure returns to step S61. On the other hand, if it is determined that the entire surface of the conveyor belt 21 has been inspected, the procedure goes to step S65. Then, in step S25, it is determined whether the conveyor belt 21 is soiled or damaged. If it is determined that the conveyor belt 21 is contaminated or damaged, the program proceeds to step S66, in which the fact that the conveyor belt 21 is contaminated or damaged is displayed on the operation panel 111, thereby notifying the user that the conveyor belt needs to be cleaned or replaced. twenty one.

That is, if the surface of the conveying belt 21 becomes dirty due to the attachment of ink droplets or is damaged for other reasons, current may leak when the conveying belt 21 is charged, which results in insufficient electrostatic attraction, which may cause recording paper to be damaged. 12 delivery errors. Or, the ink droplets on the conveying belt 21 may be conveyed to the back of the recording paper 12, which may cause the back of the recording paper 12 to be soiled. If duplex printing is performed on recording paper, dirt on the back side of the recording paper will cause image quality to deteriorate.

Therefore, in order to eliminate the above-mentioned problem, if the conveyor belt 21 becomes dirty or damaged, an indication of the damage or soiling is sent to the user, thereby preventing the recording paper from being erroneously conveyed or soiled.

If the optical sensor is used as the state detection sensor 41 as described above and if the constituent parts provide the same amount of light as the recording medium within the movable range of the state detection sensor, then since the optical sensor output corresponds to that provided by the constituent parts erroneous detection of the recording medium may occur.

Therefore, within the moving range of the state detection sensor 41, components other than the conveyor belt 21, such as components constituting the maintenance and restoration mechanism 94, are different in color density levels from the recording medium 12. Therefore, the detection accuracy of the recording medium is improved.

In addition, if other than the constituent parts of the conveyor belt 21, such as the parts constituting the maintenance and recovery mechanism 94, and the conveyor belt 21 are different in color density level, the detection target (recording medium) can be more accurately distinguished, which is Especially when the conveying means includes the conveyer belt 21, and the optical sensor detects that the conveyer belt 21 is dirty or broken, the detection accuracy is improved. It should be noted that the color of the constituent parts may be made to have a different color from the constituent parts of the recording medium and the conveying device in order to distinguish the color density levels.

(fourth embodiment)

A description will now be given of an inkjet recording apparatus which is an example of an image forming apparatus according to a fourth embodiment of the present invention.

An inkjet recording apparatus according to a fourth embodiment of the present invention has substantially the same structure as the inkjet recording apparatus shown in FIG. 1, and a description of its entire structure will be omitted.

In addition to the structure of the inkjet recording apparatus shown in FIG. 1, the inkjet recording apparatus according to this embodiment has a maintenance and restoration mechanism 94 as shown in FIG. Restores the state of the nozzle when it deteriorates. The maintenance and recovery mechanism 94 is located in a non-recording area outside the recording area in the moving direction of the carriage 3, as shown in FIG. 21 . The maintenance and recovery mechanism 94 includes a cover member that covers the nozzle surface of the recording head 7, and a wiper blade that scrapes the nozzle surface.

In addition, as shown in FIG. 25, the recording head 7 includes four heads 7kh, 7ch, 7mh and 7yh mounted on the carriage 3. As shown in FIG. Each head has a nozzle row 7a including a plurality of nozzles N. As shown in FIG. The number of the heads of the recording heads 7 is not limited to four. The number of nozzle rows 7a in each head is not limited to one, and two or more nozzle rows may be provided in each head. Alternatively, as shown in FIG. 26, the recording head 7 may have a plurality of nozzle rows 7kn, 7cn, 7mn and 7yn each having a plurality of nozzles N. As shown in FIG. The number of nozzle rows is not limited to four as shown in FIG. 26 , but any number of nozzle rows may be provided in the recording head 7 .

The control section of the inkjet recording apparatus according to the present embodiment has the same structure as the control section 100 of the inkjet recording apparatus according to the third embodiment shown in FIG. 22 , and description thereof is omitted.

Printing control performed in the inkjet recording apparatus according to this embodiment will be described with reference to FIG. 27. FIG.

First, in step S71, the main scanning motor 4 is driven prior to paper feeding, thereby moving the carriage 3 at the non-recording position to the middle area of the conveyance belt 21 (or the fed recording paper) in the direction indicated by the outlined arrow. center of). Then, in step S72 , the paper supply clutch is turned on, thereby transmitting the driving force of the sub-scanning motor 31 to the feed roller 13 . Accordingly, the feed roller 13 makes one rotation in the clockwise direction, and the recording paper 12 is separated by the friction pad 14 and fed from the paper supply tray 10 .

Then, in step S73, it is determined by detecting the detection signal of the paper sensor 41 whether or not the leading edge of the recording paper 12 is detected. After the leading edge of the recording paper is detected, in step S74, the recording paper 12 is conveyed to the printing start position and stopped there. Thereafter, in step S75 , the carriage 3 temporarily returns to the initial position, and starts moving the carriage 3 toward the recording area according to the output of the encoder 44 .

Then, in step S76, the carriage 3 is moved toward the recording area, and the printing operation of the first line (area printed by one scan of the carriage 3) is started in step S77. Then, it is determined in step S78 whether the printing operation is completed each time the carriage 3 moves by a predetermined amount (distance). If the printing operation is not completed, the procedure proceeds to step S79, in which it is determined whether or not the recording paper 12 is present by detecting the detection signal of the state detection sensor 41.

Here, if there is a recording sheet 12 to be printed, the scanning of the carriage 3 continues to continue printing of the line. On the other hand, if there is no paper 12 (when the status detector 41 detects that there is no recording paper), the process proceeds to step S80, in which the printing operation on the line is canceled. Therefore, in this case, the print data of the row is cleared. Therefore, the printing operation is not performed in an area where there is no recording paper 12, which prevents ink droplets from adhering to the conveyance belt 21, and thus, prevents the conveyance belt 21 and the recording paper 12 from becoming dirty.

After the printing operation is canceled in step S80, the remaining lines are printed in step S81 with the same width (width in the main scanning direction) as the first line. Then, it is determined in step S82 whether printing of all lines has been completed. If printing of all lines has been completed, the procedure proceeds to step S83, whereby the recording paper 12 is ejected, and the process ends. It should be noted that in step S83 , the recording paper 12 is not ejected if it is duplex printing, but the process performs some operation to convey the recording paper 12 to the duplex unit 61 .

That is, similar to the image forming apparatus according to the present embodiment, according to the operating method of a general inkjet recording apparatus, the head H draws an image while moving in a direction perpendicular to the feeding direction of the recording paper P, as shown in FIG. 28 . Drawing corresponding to one line (predetermined width) is performed immediately, and then, after the recording paper P is moved, drawing of the next line (same width) is performed. This operation is repeated until the entire recording sheet is pulled out.

When drawing a line, the position where the carriage with the head H is moved is determined based on print setting information from the host. However, if there is no detection function for detecting the size of recording paper in the paper feeding section of the recording device, as shown in FIG. 29, since there is no means for detecting whether the size of the recording paper actually fed is the same as the size set by the host , it is possible that the recording paper P1 has a smaller width than the recording paper set by the host.

Also, if the recording paper P is fed in an oblique state (recording paper P') as shown in Fig. 30, it is possible that the recording paper is not fed to a predetermined position or the recording paper is torn. Alternatively, fully twisted sheets can be fed at the user's request.

In this case, the printing operation is performed on the assumption that the recording paper P of the size set according to the print setting information is correctly fed even when the recording paper P does not appear at the predetermined position. Therefore, printing (ejection of ink droplets) is performed with the recording paper P1 not present at the position shown in FIG. 29 .

If printing is performed at a position where the recording paper is not present, ink droplets are attached to the conveying belt 21, which causes the conveying belt to be contaminated with ink, or ink may adhere to parts in contact with the conveying belt 21, as a result, The service life of the device will be shortened. Also, since printing is performed at unnecessary positions, ink droplets are used unnecessarily, which causes waste of ink.

Therefore, in this embodiment, the state sensor (state detector) is mounted on the carriage 3 so that the state detection sensor detects the presence of recording paper along the moving line of the carriage 3, so that when the fed record Printing is performed when the paper has a width equal to or greater than the recording paper set in the print settings. Then, if the presence of recording paper is detected in the middle of printing, when the size of the recording paper actually supplied matches the size of the recording paper set in the print settings, the printing operation is continued.

On the other hand, if the paper P1 is not detected in the middle of the carriage movement, the printing operation of the subsequent relevant line is canceled at that time, and the printing operation of the next line is advanced. In this case, it is assumed that the recording paper is supplied correctly so that the printing operation of the remaining line in the main scanning direction is performed within the width of the first line. Therefore, it is impossible to handle the case where the recording paper is fed in an oblique state or the recording paper is deformed, but without detecting the detection signal of the state detection sensor for each line (each scanning line), the printing process can be simplified.

By referring to FIG. 32, a second example of print control will be described. Here, the process when no recording paper is detected in the middle of a printing operation of one line until the printing operation is canceled will be described. In this example, as shown in FIG. 25 , it is assumed that four heads 7kh, 7h, 7mh, and 7mh are arranged at an interval "x" and that the head 7yh is located at a distance "a" from a paper-free position detected by the state detection sensor 41. at the location. It is also assumed that, in the main scanning direction of the carriage (printing direction), the head 7yh is the first head, the head 7mh is the second head, the head 7ch is the third head, and the head 7kh is the fourth head. It should be noted that the head 7yh is at the most downstream position and the head 7kh is at the most upstream position when viewed in the main scanning direction.

As shown in FIG. 12, it is determined in step S91 whether or not there is a recording sheet 12 in the middle of the printing operation for one line. If it is determined in step S91 that there is no recording paper, the main scanning of the carriage 3 continues for a distance "a" in step S92 while printing is performed using the four heads 7yh, 7mh, 7ch, 7kh.

Then, after the carriage 3 is moved by a distance "a", the printing operation of the first head 7yh is canceled, and in step S93, by using the second to fourth heads 7mh, 7ch while moving the carriage 3 by a distance "x" , 7kh, continue printing operation.

In addition, after moving the carriage by the distance "x", the printing operations of the first and second heads 7yh and 7mh are canceled, and in step S94, by using the third and fourth heads while moving the carriage 3 by the distance "x" Head 7ch and 7kh, continue printing operation.

Also, similarly, after moving the carriage by the distance "x", the printing operation of the first to third heads 7yh, 7mh, 7ch is canceled, and in step S95, while moving the carriage 3 by the distance "x" The printing operation is continued by using the fourth head 7kh. After that, the printing operation of the fourth head 7kh was canceled. Thereafter, in step S96, the remaining printing operations for the line are canceled.

That is, as shown in FIG. 33, if the printing operation is canceled when the status detection sensor 41 detects that there is no paper, it is possible that since four heads 7yh, 7mh, 7ch, 7kh are provided in the main scanning direction, The difference in the ejection timing of ink droplets from the four heads forms dots lacking ink droplets of the desired color.

Then, printing is continued by using the head facing the recording paper with respect to the distance between the state detection sensor 41 and the first head 7yh and the distances between the four heads 7yh, 7mh, 7ch, 7kh. That is, by gradually canceling the printing operations of the plurality of heads while continuing the main scanning, desired ink droplets can be attached to all dots and ink droplets can also be attached to a certain position very close to the edge of the recording paper. Therefore, the image can be formed at a position very close to the edge of the recording paper P, as shown in FIG. 34 . It should be noted that a margin can be set on the edge of the recording paper by canceling the printing operation of the first head when the status detection sensor detects the absence of paper, and thereafter gradually canceling the printing operation of the other heads while continuing the main scanning. .

In addition, if the recording head has a structure including a plurality of nozzle columns that can eject inks of different colors as shown in FIG. 26, a process similar to that of FIG. ” and the distance “xa” between each nozzle row.

Although on the basis of assuming that the four heads 7yh, 7mh, 7ch, and 7kh are arranged in the main scanning direction with an equal head spacing distance x, the head spacing distance is actually not fixed or varies with the device or varies with the device. changes with the passage of time. For example, FIG. 35 shows an example in which the distances between the four heads 7yh, 7mh, 7ch, 7kh are different from each other, such as "x", "y", "z", respectively.

Therefore, the head separation distance adjustment value (changed with respect to the reference value) for adjusting the distance between the heads or the head separation distance itself is stored as information in a memory such as the above-mentioned NVRAM or ROM, thereby using the adjustment value or the distance, when the state detection sensor 41 detects that there is no paper, the amount of movement of the carriage 3 is controlled in the main scanning direction, and the step-by-step cancellation of the printing operation makes it possible to accurately place the ink droplets by using a plurality of heads. Attaches at the same point for precise printing.

In addition, by using the adjustment value of the head separation distance used to determine the position where the printing operation is canceled due to narrow width recording paper, printing in all colors can be applied to a position very close to the edge of the recording paper.

A third example of print control for performing bidirectional printing will be described below with reference to FIG. 36 . Since the carriage 3 moves in two directions along the main scanning line to realize printing in the outward direction and the homeward direction in bidirectional printing, the printing operation should be canceled so that during the homeward movement, there is no recording Printing is not performed on the area of the paper.

For example, after printing in the outward direction by moving the carriage 3 (recording head 7) to the position shown by the dotted line in FIG. , 7kh one of them starts, the head has moved to the position where the recording paper P is present. At this time, by canceling the print data corresponding to the area where the printing operation was canceled in the outward direction due to being outside the recording paper P1, printing is not performed in the area outside the recording paper during printing in the homeward direction, which This allows proper printing in bidirectional printing operations.

As described above, in the area where the printing operation performed in the outward direction is canceled, by canceling the printing operation during the printing operation in the homeward direction, the bidirectional printing can be properly performed within the range of recording paper.

A fourth example of printing control will be described with reference to FIG. 37 .

First, in step S101, prior to paper feeding, the main scanning motor 4 is driven to move the carriage 3 at the non-recording position to the middle portion of the conveyor belt 21 in the direction indicated by the outlined arrow (or to be fed). the center of the recording paper). Then, at step S102 , the paper supply clutch is turned on, thereby transmitting the driving force of the sub-scanning motor 31 to the feed roller 13 . Accordingly, the feed roller 13 makes one rotation in the clockwise direction, and the recording paper 12 is separated by the friction pad 14 and fed from the paper supply tray 10 .

Then, in step S103 , it is determined whether the leading edge of the recording paper 12 is detected by the detection signal of the detection paper sensor 41 . After the leading edge of the recording paper 12 is detected, in step S104, the recording paper 12 is conveyed to the printing start position and stopped there. Thereafter, in step S105 , the carriage 3 temporarily returns to the initial position, and starts moving the carriage 3 toward the recording area according to the output of the encoder 44 .

Then, in step S106, the carriage 3 is moved toward the recording area, and in step S107, a printing operation of one line is performed. Then, in step S108, it is determined whether the printing operation is completed. If the printing operation is not completed, the procedure goes to step S109, where it is determined whether or not the recording paper 12 is present by detecting the detection signal of the state detection sensor 41.

Here, if the recording paper 12 to be printed is detected, the scanning of the carriage 3 continues, thereby continuing the printing of the line. On the other hand, if there is no paper 12 (when the state detecting sensor 41 detects no recording paper), the procedure goes to step S110, where the printing operation of the line is canceled. Therefore, in this case, the print data of the row is eliminated. Therefore, no printing operation is performed in an area where there is no recording paper 12, which prevents ink droplets from adhering to the conveyance belt 21, and thus prevents the conveyance belt 21 and the recording paper 12 from being contaminated.

In step S110, after the printing operation corresponding to the line is canceled, the program proceeds to step S111, where it is determined whether the printing operation for all the lines has been completed. If not, the program goes to step S106. Otherwise, the program proceeds to step S112 to discharge the printed recording paper 12 and end the printing process.

If the width of the recording paper is determined when it is fed, it can be determined whether the supplied recording paper has the same size as the recording paper set in the print settings. However, there is a possibility that the recording paper is deformed or the recording paper is inclined with respect to the feeding direction. In this case, the edge position of the recording paper may be changed, which results in printing on the outer area of the recording paper.

Therefore, in this printing control, when the state detection sensor is positioned at the front of the carriage 3 in the moving direction, the edge of the recording paper is always monitored (detected) while printing is performed, so that each line The printing operation always ends at the edge of the recording paper, and the printing operation corresponding to the remaining print data is canceled, thus preventing printing outside the recording paper.

It should be noted that when bidirectional printing is performed, by providing state detection sensors 41 on both sides of the carriage in the main scanning direction as shown in FIG. detected during a print operation on .

An inkjet recording apparatus which is a modification of the image forming apparatus according to the present invention will be described. As shown in FIG. 41 , the modified inkjet recording apparatus has the same configuration as that of The inkjet recording apparatuses according to the above-described embodiments have the same structure. It should be noted that the recording head 7 may have a structure of a plurality of nozzle rows as shown in 26 .

Referring to FIG. 42, the printing control performed by the ink jet recording apparatus will be described.

First, in step S121, the recording paper 12 is fed. Then, in step S122, the edge of the recording paper 12 is detected and the recording paper is fed by a predetermined distance. Thereafter, in step S123, the width of the recording paper 12 is detected by moving the carriage 3 in the main scanning direction. Then, in step S124, the printing operation is started to print in the main scanning direction within the width of the recording paper 12 by the recording head 7 while moving the carriage 3 in the main scanning direction, that is, canceled when no paper is detected. print operation. At this time, in step S125, the width of the recording paper 12 is determined according to the detection result of the state detection sensor 41 of the line next to the line to be printed, that is, in the next scan of the carriage 3. The line that prints.

Then, in step S126, it is determined whether the printing operation of the current line has been completed. If the printing operation of the current line has been completed, the program proceeds to step S127, in which it is determined whether the printing operation of all lines has been completed, that is, whether the printing operation of one page has been completed. If the printing operation for all lines has been completed, the printing process ends. Otherwise, the program goes to step S124. Therefore, even if a status detection sensor is provided, printing can be performed in bidirectional printing while canceling the printing operation after detection of absence of paper for each main scanning of the carriage.

That is, although the state detection sensor that can detect the edge of the recording paper before the recording head reaches the edge of the recording paper is a state detection sensor that is provided in the main scanning direction as described above, and when the state detection sensor is in the When the printing is performed by moving the carriage in the normal direction in front of the carriage 3, it is impossible to cancel the printing operation based on the detection result of the status detection sensor during the printing operation in the return direction, since The state detection sensor moves behind the recording head when the printing operation is performed in the return direction.

Therefore, the width of the recording paper corresponding to the next line of the printed line is monitored by disposing the state detection sensor on the carriage upstream in the paper feeding direction, so that the printing of the next line depends on the printing of the preceding line. The operation is performed while obtaining the width of the recording paper. Therefore, by monitoring the width of the line next to the line to be printed, bidirectional printing can be performed while monitoring the width of the recording paper for all lines as shown in FIG. 43 .

It should be noted that, also in this embodiment, if a plurality of beam heads or a plurality of nozzle columns are arranged in the main scanning direction as described above, the printing operation of the recording heads or nozzle columns can move the carriage along the main scanning direction. The carriages are phased out simultaneously until printing of the same dot by all recording heads or nozzle columns is completed.

In addition, as shown in FIG. 44, if the state detection sensor 41 is located at a position corresponding to the recording head (or nozzle row) that is located on the upstream side of the carriage 3 in the sheet feeding direction and located on the carriage 3 in the main scanning direction, the edge of the recording paper can be detected when the printing operation of the first line is performed. Therefore, there is no need to perform pre-scanning to detect the width of the recording paper before starting the printing operation.

It should be noted that although the embodiment has been described in which the present invention is applied to a shuttle-type inkjet recording apparatus using a carriage, the present invention is not limited to the inkjet recording apparatus described. That is, for example, the present invention is applicable to a copying machine, a facsimile machine, a multifunctional machine combining a copying device, a printer, and a facsimile device.

The invention is not limited to the particular disclosed embodiments, but variations and modifications may be made without departing from the scope of the invention.

Claims (14)

1. An imaging device for forming an image on a recording medium, comprising: a carriage having a plurality of recording heads for forming an image on a recording medium, the recording heads ejecting liquid droplets on the recording medium; and a state detector for detecting the presence of a recording medium along a moving line of the carriage; Wherein when the carriage is moved in the main scanning direction to perform a printing operation, the printing operation of each of the recording heads is gradually canceled after the state detector detects the absence of recording paper. 2. The image forming apparatus according to claim 1, wherein said state detector is provided on an upstream side of said carriage in a main scanning direction so that in an initial scan by said carriage for printing The state detector detects a position where the recording medium does not exist, and gradually cancels the printing operation of each of the print heads in the main scanning direction. 3. The image forming apparatus according to claim 1, wherein the state detector is disposed on an upstream side of the carriage in the main scanning direction so as to detect After reaching the position where the recording medium does not exist, the printing operation of each of the print heads is gradually canceled in the main scanning direction. 4. The image forming apparatus according to claim 1, wherein the plurality of recording heads eject ink droplets in a plurality of colors by being arranged in a main scanning direction, and the main scanning of the carriage is performed at different positions of the recording medium. Presence is detected by the status detector and continues, thereby phasing out printing operations for each head while moving the carriage in the main scanning direction. 5. The image forming apparatus according to claim 4, wherein after the absence of recording paper is detected, based on the information related to the adjustment value of the interval between the heads, the amount of movement of the carriage in the main scanning direction and Printing operations that phase out the heads are controlled. 6. The image forming apparatus according to claim 1, wherein a plurality of nozzle columns are provided in the recording head so as to eject ink droplets in a plurality of colors by being arranged in a main scanning direction, and the main scanning of the carriage is in the The absence of the recording medium is detected by the status detector to continue, thereby gradually canceling the printing operation of each nozzle column while moving the carriage in the main scanning direction. 7. The image forming apparatus according to claim 1, wherein said carriage is bidirectionally movable so as to perform bidirectional printing, and when a part of a printing operation in one direction is canceled, corresponding to Partial print operations in the area where the print operation was canceled are also canceled in the print operation in the other direction. 8. The image forming apparatus according to claim 1, wherein the carriage is bidirectionally movable so that bidirectional printing can be performed, and the state detector is provided on each side of the carriage in the main scanning direction . 9. The image forming apparatus according to claim 1, wherein said state detector is provided on an upstream side of said carriage in a feeding direction of said recording medium, while scanning said carriage in a main scanning direction, The printing operation starts after the edge of the recording medium is detected by the state detector, which detects the edge of the recording medium for each main scan of the carriage, thereby determining the The position of the edge of the recording medium used. 10. The image forming apparatus according to claim 9, wherein ink droplets are ejected in a plurality of colors by being disposed in a main scanning direction, and the main scanning of the carriage exceeds the recording medium detected by the state detector. The edge continues, gradually canceling the print operation of the head. 11. The image forming apparatus according to claim 10, wherein, after each of said heads passes the edge of said recording medium, said carriage moves in a main scanning direction based on information related to an adjustment value of an interval between said heads The amount of movement as well as the gradual cancellation of the print operation of the head is controlled. 12. The image forming apparatus according to claim 9, wherein a plurality of nozzle rows are provided in the recording head so as to eject ink droplets in a plurality of colors by being arranged in a main scanning direction, and the main scanning of the carriage exceeds the The edge of the recording medium detected by the state detector continues, thereby gradually canceling the printing operation of the nozzle row. 13. The image forming apparatus according to claim 9, wherein the state detector is disposed at a position corresponding to the nozzle row closest to the edge of the recording head in the main scanning direction. 14. The image forming apparatus according to claim 1, further comprising a transport belt that transports the recording paper by electrostatically attracting the recording paper to a surface of the transport belt.

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