JPH08192535A - Image recording device - Google Patents

Abstract

(57) Abstract: When an image formed on a plurality of photosensitive drums 20, 30 is multi-recorded on one sheet, misalignment of each image on the sheet is prevented. A reference clock signal common to the plurality of photosensitive drums is generated, and a driving unit of each photosensitive drum is controlled so that the rotations of the plurality of photosensitive drums are synchronized with the common reference clock signal. Further, when a plurality of photosensitive drums are independently scanned using the plurality of deflectors 22 and 32, a reference clock signal common to the plurality of deflectors is generated, and rotation of the plurality of deflectors is common. The driving means of each deflector is controlled so as to be synchronized with the reference clock signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording apparatus having a plurality of image forming units (photosensitive drums, etc.).

[0002]

2. Description of the Related Art Hitherto, various kinds of materials have been put into practical use for recording images on paper. For example, a copier that projects an image of a document directly onto a photoconductor to visualize it and records it on paper, or image information that has been converted into an electrical signal by an impact type (printing type, wire dot type, etc.) or non-impact type (heat-sensitive type). Type, ink-jet type, etc.) and a printer that reproduces an image on paper.

In recent years, these image recording apparatuses have been required to have higher functions due to requests for rationalization of office work, and in particular, it is strongly desired to improve the output speed (the number of sheets processed per hour). The speeding up of devices has been promoted.

However, although there are differences depending on the respective methods, there is a speed commensurate with it, and if it is attempted to increase the speed beyond that, many problems will occur,
In order to overcome it, great effort such as new technology development is required,
The device itself may become complicated and huge, making it uneconomical. Taking a copying machine as an example, a document image is directly guided to a photoconductor to form an image, a latent image is formed, and the latent image is visualized and transferred onto a sheet. I only get a copy of.

Therefore, in order to increase the speed, it is necessary to increase the machine speed, which causes problems such as insufficient sensitivity of the photoconductor, vibration of the machine, noise and durability. On the other hand, if measures such as increasing the light intensity of the original illumination lamp are taken, many problems occur, such as the temperature of the machine rising due to the heat generated by the lamp, and it is difficult to completely solve it. is there. Moreover, since this increases exponentially as the speed increases, the upper limit of the speed is naturally limited due to the balance of the merits of increasing the speed.

On the other hand, from the viewpoint of saving resources and filing space, what has been conventionally recorded on one side of a sheet is recorded on both sides of the sheet in the same manner as general printing, and the sheet of the sheet is recorded. There is a demand to reduce the number of sheets used. Also for this, a method has been proposed in which the sheets recorded on the first side are stacked once, and after the recording on the first side is completed, the accumulated sheets are fed again to record on the second side, and they are put into practical use. However, this is efficient when making many records of the same content, but it is very inefficient when making many different double-sided records.

That is, when creating pages 1, 2, 3, ..., first, 1, 3, 5, ... on the first surface of each sheet.
And then record an odd number of pages, re-feed it after it is finished, and record 2, 4, 6, ... pages on the back side. If, during this re-feeding, a double feed or a paper jam occurs, the combination of the front and back sides will differ from the predetermined one, so it will have to be restarted from the beginning. In order to avoid this, it is sufficient to record one sheet at a time, such as front, back, front and back, but it takes time to re-feed the sheet and the efficiency is extremely lowered.

In order to improve the function, there is also a demand for recording two pieces of information on one side of a sheet in an overlapping manner. In particular, as in recent years, colorization has progressed in various fields, and there is also a demand for making documents easier to see, for example, by mixing red records (for example, titles in red) instead of black as in the past. On the other hand, in the conventional apparatus, a method using an ink ribbon or the like was possible, but in a copying machine or a laser beam printer using the electrophotographic method, the apparatus would be extremely large-scaled. However, it has not been put to practical use for general office work.

As a simple method, there is a method of recording once in black, then changing the developing device in the apparatus from a black one to a red one, and recording again on the same surface, but this is very troublesome. It was a thing.

In order to solve the above-mentioned problems, a plurality of image forming units are provided in the apparatus, and they are connected by each selectable sheet conveying path to speed up image recording, double-sided recording, multiple recording, etc. An image recording apparatus that enables the above has been proposed.

1 to 5 are explanatory views of an embodiment of the image recording apparatus described above, and FIG. 1 is a schematic view showing the basic structure of this embodiment centering on a paper path. Reference numeral 1 denotes a main body, and inside thereof is a first image recording unit 2, a second image recording unit 3, a paper handling unit 4, a first paper feeding unit 5, a second paper feeding unit 6, a first stacker unit 7, and a first stacker unit. It is composed of two stacker units 8.

The first and second image recording units 2 and 3 are
The laser beam printer has almost the same configuration. First
Explaining the image recording unit 2, reference numeral 20 denotes a photosensitive member that is rotationally driven, and a known electrophotographic process unit is arranged around the photosensitive member (not shown). Laser light modulated according to an image signal is scanned and exposed on the photoconductor 20 by a laser scanner 22 via a mirror 21 and is visualized by a predetermined electrophotographic process.

On the other hand, the paper P ₁ stacked in the first paper feed section 5
Is a first sheet by sheet feeding means 50 such as a known roller.
The paper is fed into the paper supply passage 23 of the image recording unit 2. The fed sheet reaches the transfer section 24 in synchronization with the visible image on the photoconductor 20, and the image is transferred by a known transfer unit.
Then, the sheet reaches the fixing section 25, the image on the sheet is fixed by a known means such as heating or pressing, and the sheet is discharged to the outside of the first image recording section 2 through the discharge passage 26. In addition, conveyance means such as rollers and belts are appropriately provided in the paper passage path (not shown).

The second image recording section 3 is different from the first image receiving section 3 in which paper is received from the paper handling section 4 in addition to the paper supply passage 33 for receiving the paper P ₂ accumulated in the second paper feeding section 6. That is, the second sheet supply passage 37 is provided. Each sheet received from both sheet supply passages 23 and 33 is
Both are guided to the transfer unit 34.

Next, the paper handling section 4 will be described. The paper handling unit 4 reverses or does not reverse the paper received from the carry-in passage 40 connected to the discharge passage 26, from the paper carry-out passage 41 to the paper supply passage 37, or via the paper reversing unit 42. It is designed to be delivered from the second sheet unloading passage 43 to the first stacker unit 7.

FIG. 2 is a diagram showing the detailed internal structure of the paper handling section 4, in which the rollers 400 and 401 of the paper carry-in passage 40 are
Each rotates in the direction of the arrow, and the passage switching claw 402
Is provided. This passage switching claw 402 is provided with a shaft 403.
Is rotatable about the rotation center, and is always biased counterclockwise in the drawing by a spring 404 to direct the paper path to the paper reversing unit 42.

When the solenoid 405 is operated, the passage switching claw 402 rotates clockwise against the spring 404 and switches the passage to the unloading passage 41 side. Paper reversing unit 42
A claw 406 that hangs down by its own weight is provided at the entrance of the claw 406.
The sheet that can be pushed away from the lower surface of the sheet 6 and passed back, and returned from the sheet reversing unit 42 in the right direction in the drawing is guided by the upper surface of the claw 406 and directed to the carry-out passage 41. Nail 4
A sheet detector including a lamp 407 and a light receiving element 408 is arranged adjacent to 06.

Reference numerals 409 and 410 denote a reversing roller and a driven roller, respectively. The reversing roller 409 is attached to the tip of an arm 411 swingable around a shaft 409a and is constantly rotating counterclockwise in the drawing. The arm 411 is suspended by the spring 412, and the reversing aura 409 is normally spaced from the driven roller 410. However, when the solenoid 413 is operated, the arm 411 swings clockwise and the reversing roller 409 is driven. It is pressed against the roller 410. The driven roller 410 is rotatably supported and has a reversing roller 409.
When is pressed, it rotates clockwise accordingly.
Further, an endless belt 414 that rotates in the direction of the arrow is provided next to the endless belt 414, and a fan 215 located below the endless belt 414 sucks and conveys the sheet to the belt 414, and guides the sheet to the discharge passage 43.

Next, the operation of the paper handling section 4 will be described.
First, when guiding from the carry-in passage 40 to the carry-out passage 41 as it is, when the solenoid 405 is operated, the passage switching claw 402 is switched, and a passage from the carry-in passage 40 to the carry-out passage 41 is formed. Further, when the sheet is inverted and then guided to the carry-out passage 41, the sheet is guided to the sheet inverting unit 42 without operating the solenoid 405. The leading edge of the sheet passes between the reversing roller 409 and the driven roller 410, and the belt 4
When the sheet is placed on the sheet 14, the sheet is sent to the left by the suction force of the fan 415.

When the passage of the trailing edge of the sheet is detected by the lamp 407 and the light receiving element 408, the solenoid 413 is actuated, the reversing roller 409 is pressed against the driven roller 410, and the sheet is pinched. At this time, the reversing roller 4
Since 09 is rotating in the counterclockwise direction, the paper overcomes the frictional force of the fan 415 with the belt 414 and is sent to the right in the drawing. That is, what has been the trailing edge of the sheet until now becomes the leading edge and advances.

When the tip of the new paper reaches the claw 406, the claw 406 serves as a guide and the paper is guided to the carry-out passage 41, as described above. At this time, the sheet is replaced with the front side and the back side as compared with the case where the sheet is directly guided to the carry-out passage 41.

On the other hand, when the sheet is guided to the carry-out passage 43, the solenoid 405 is deactivated, the sheet is guided to the sheet reversing section 42, and then the solenoid 413 is kept inoperative. Is sent to the left by the cooperation of the fan 415 and is guided to the carry-out passage 43 as it is.

The first and second stacker units 7 and 8 shown in FIG.
Is the carry-out passage 43 and the second of the paper handling section 4, respectively.
The sheets discharged from the discharge passage 36 of the image recording unit 3 are stacked one after another.

The following will describe how the above-described device can be used for the above-described high-speed recording, double-sided recording and multiplex recording.

(1) High-speed recording FIG. 3 shows a block diagram for high-speed recording.

The signal S ₁ given to this apparatus is distributed to the first and second recording sections 2 and 3 and both image recording sections are operated in parallel. That is, the first image recording unit 2 receives the supply of the paper P ₁ from the first paper supply unit 5, and the signal S ₁ is supplied on one side thereof.
The image is recorded and transferred to the paper handling unit 4. In the paper handling unit 4, the solenoid 405 and the solenoid 4
13 is deactivated, and the received paper P ₁ is discharged from the carry-out passage 43 to the first stacker unit 7. On the other hand, the second image recording unit 3 receives the supply of the paper P ₂ from the second paper supply unit 6 and records the image by the same signal S ₁ as the paper P _{1 on} one side thereof, and then the second paper is supplied from the discharge passage 36 to the second position. The sheet is discharged to the stacker section 8.

In this way, if the processing capacity of each of the first and second image recording units 2 and 3 is N sheets, the processing capacity of the entire apparatus will be 2 per unit time.
The number of sheets becomes N and double speed recording is realized.

(2) Double-sided recording FIG. 4 shows a block diagram when performing double-sided recording.

The recording by the first surface image signal S ₂ given to the first side of the sheet by the first image recording section 2 and the second side given to the second side of the sheet by the second image recording section 3 are performed. The apparatus is operated so as to perform recording by the two-sided image signal S ₃ .

That is, first, in the first image recording section 2, the sheet P ₁ is supplied from the first sheet feeding section 5, and an image by the signal S ₂ for the first side is formed on the first side (upper surface in the drawing). It is recorded and delivered to the paper handling unit 4. The paper handling unit 4 performs the above-described paper reversing operation.

That is, the solenoid 405 is deactivated and the paper P ₁ is sent to the paper reversing unit 42, and then the paper detectors 407 and 408 detect the trailing edge of the paper to activate the solenoid 413, and the paper P ₁ is now removed. The rear end up to the leading end is guided to the carry-out passage 41 and transferred to the second image recording unit 3. The delivered paper P ₁ is transferred to the transfer unit 34 to the second position.
The image by the signal S ₃ for the surface is transferred, but the surface to be transferred (the upper surface in the drawing) is subjected to the reversing action, so
It is a second surface on the back side of the first surface transferred by the image recording unit 2. The sheet P ₁ on which the image is recorded on the second surface is discharged from the carry-out passage 36 to the second stacker unit 8 to complete the double-sided recording. During the above period, the second sheet feeding section 6 is kept inactive.

(3) Multiplex recording FIG. 5 is a block diagram for performing multiplex recording.

Recording by the first image signal S ₄ given by the first image recording section 2 is carried out by the second image signal S ₅ given by the second image recording section 3 on the same side of the paper. Make a record.

That is, first, the first image recording section 2 receives the sheet P ₁ supplied from the first sheet feeding section 5 and records the first image by the signal S ₄ on one side (the upper side in the figure) of the sheet P _1. Hand it over to the handling section 4. In the paper handling unit 4, the solenoid 4
05 is operated, and the received paper P ₁ is transferred from the carry-out passage 41 to the second image recording unit 3 as it is. The transferred paper P ₁ is transferred by the transfer unit 34 to the signals S _{5 of} different colors and the like.
The second image is transferred, but the surface (upper surface in the drawing) that receives the transfer is the same surface as the surface transferred by the first image recording unit 2. The sheet P ₁ on which the second image is recorded is discharged from the carry-out passage 36 to the second stacker unit 8 to complete the multiplex recording.

In such a recording apparatus, multiple recording can be continuously performed, and various high-performance image recording apparatuses can be obtained, such as various color recordings can be recorded at high speed.

[0036]

However, in the case of multiple recording, since a single sheet passes through a plurality of image forming sections, the rotation state of the photosensitive drums of the plurality of image forming sections is
It must be precisely aligned or synchronized with the paper transport. In the case of an image recording apparatus having only a single image recording section, as a method of obtaining the alignment of the rotation of the photosensitive drum and the conveyance of the sheet, the drive sources of the photosensitive drum and the sheet conveying section are made common.

However, in the case of the image recording apparatus having a plurality of image forming portions as in the present invention, when the drive source is shared, many mechanical transmission means such as gears, chains, belts are used. This means that speed fluctuations due to their mechanical accuracy are likely to occur on each photosensitive drum and the transport section. Therefore, it is difficult to match the rotation speed of each photosensitive drum and the paper conveyance speed within a desired accuracy range.

Further, when the common drive is performed, for example, the impact or load fluctuation when the paper passes through the fixing device is transmitted to the photosensitive drum as it is, and the image is disturbed. It is easy to cause a phenomenon that is transmitted to. In particular, when images are continuously recorded on a plurality of sheets, when a certain sheet passes through the fixing device, the next image is visualized on the photosensitive drum, and this phenomenon easily occurs.

When each image forming unit is equipped with a laser scanner that rotates at a high speed, the laser beam is applied to the generatrix of the photosensitive drum. The laser image formed by the laser light must be formed without distortion on the photosensitive drum and at the correct time according to the paper conveyance time.

Usually, the drive source of the laser scanner is provided with a DC motor having a device for generating a signal for each rotation, for example, and feedback is performed so that the generated signal matches the reference signal.

In the case where a plurality of laser scanners are provided inside one device like this device, by using the control method up to now, the feedback is applied so as to match the reference signal generated for each laser scanner. Therefore, the rotation speed of each laser scanner is stable, but a speed difference occurs between the laser scanners.

Since this difference in speed appears as a difference in deflection speed, there arises a problem that the position of each image transferred onto the sheet is displaced.

The main cause of the speed difference is that the frequency changes due to variations in characteristics of each element of the clock generating means such as each crystal oscillation for generating the reference signal and characteristic changes due to temperature changes.

If there is a difference in the deflection speed between the laser scanners, even if the images at the leading end in the paper feeding direction are superposed so as not to be displaced, the images at the trailing end will be displaced.

The object of the present invention is to solve the above technical problems and to multiplex images formed on a plurality of photosensitive drums onto one recording medium and record the multiplexed images on a recording medium. It is an object of the present invention to provide an image recording device capable of preventing a positional deviation of an image that is generated.

[0046]

In order to achieve the above object, the present invention forms a plurality of photosensitive drums on each photosensitive drum by independently scanning with a laser beam using a plurality of deflectors. In an image recording apparatus capable of multiplexing and recording an image on one recording medium, a plurality of driving means for respectively driving the plurality of deflectors, and a reference clock signal common to the plurality of deflectors are generated. And a control means for controlling the plurality of driving means so that the rotations of the plurality of deflectors are synchronized with the common reference clock signal.

Further, according to the present invention, in an image recording apparatus capable of multiplexing and recording images formed on a plurality of photosensitive drums on one recording medium, a plurality of photosensitive drums for driving the plurality of photosensitive drums are provided. A reference clock signal common to the drive means and the plurality of photosensitive drums is generated, and the plurality of drive means are controlled so that the rotations of the plurality of photosensitive drums are synchronized with the common reference clock signal. And a control means.

[0048]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS This embodiment will be described below with reference to the drawings.

[0049]

FIG. 6 is a schematic diagram showing a drive control method when the present invention is applied to the apparatus shown in FIG. Reference numeral 101 denotes a sheet conveying section of the first image recording section 2 and the second image recording section 3 in FIG. 1, a sheet handling section 4, a first sheet feeding section 5, and a second sheet feeding section 6.
And the like, 201 is a drive source for driving the photosensitive drum 20 of the first image recording unit 2, 221 is a drive source for driving the laser scanner 22 of the first image recording unit 2,
Reference numeral 301 is a drive source for driving the photosensitive drum 30 of the second image recording unit 3, and 321 is a drive source for driving the laser scanner 32 of the second image recording unit 3.

Each of the above driving sources is a DC motor. The reason why the DC motor is used is that the control can be performed with relatively high accuracy by changing the input when performing the rotation synchronization control. Reference numeral 9 is a reference signal generator, which has a crystal oscillator (not shown) as a reference signal generator. The reason for using a crystal oscillator is that it is relatively inexpensive (the operating power supply is easily available) and highly accurate (oscillation error is several pp
It is possible to obtain a reference signal within m).

Further, the reference signal generator 9 drives the drive sources 201 and 3 so that the rotations of the laser scanners 22 and 23 and the photosensitive drums 20 and 30 are synchronized with the generated reference signals.
01, 221, 321 are controlled. The reference signal generator 9 is in communication with the main body controller 91.

Next, the operation of the drive control according to this embodiment will be described. Normally, when the power is turned on, only the reference signal generator 9 is operating and the reference signal (hereinafter referred to as pulse) is generated. Further, although the laser scanner motors 221 and 321 are also rotating, they are not controlled by the reference signal generator 9 to rotate. When a signal to start image recording is input, the photosensitive drum drive motors 201 and 301 and the conveyance unit drive motor 101 in the image recording apparatus start rotating, and the rotation control is performed from the reference signal generator 9 together with the laser scanner motors 221 and 321. receive.

The main body control unit 91 counts several pulses from the time when the image recording start signal is input, and the main body control unit 91 controls each paper feed unit, laser modulation and paper handling unit based on the counted pulses. The image is recorded by operating each pulse. Since the main body control unit 91 operates each image forming unit and the paper handling unit, not only the recording start signal is input, but also information such as what kind of recording is to be input. The number of pulses counted from the image recording start signal input depends on how long each motor receives rotation control and synchronizes (rise time) or the charging characteristic adjustment time of the photoconductor (previously). It is determined in advance by setting the photosensitive characteristics).

FIG. 7 is a diagram showing signals of the respective parts showing the above-mentioned control state. S ₁ is an image recording start signal, P ₁
Is a reference pulse at the start of operation of the main body. N ₁ pulses of S ₁ are counted to become P ₁ , and each motor is synchronized during that period. In the figure, + and-indicate deviations from the synchronization state O. Counting n ₂ minutes from the P ₁ pulse, the paper feed roller 50 of the first paper feeding unit contacts the paper and sends it to the first image recording unit 2, counting n ₃ minutes from the P ₁ pulse and laser modulation 29. Then, a laser image is formed on the photoconductor. It is needless to say that how many counts are made to operate each operating portion differs depending on the operating state of the device (speeding up, multiplexing, double-sided, etc.).

Although FIG. 7 shows an example in which the laser scanner unit is constantly rotated, it may be normally stopped and started when S _{1 is} input.

(Other Embodiments) FIG. 8 is a schematic view of another embodiment of the drive control method of the present invention. The difference from FIG. 6 is that among the plurality of drive sources, the first image recording section 2 is exposed to light. A reference signal generator 9 is provided in a part of the driving source of the drum 20. The other drive sources are controlled so as to be synchronized with the drive source 201 based on the pulse generated by the reference signal generator 9. As the reference signal generating means, a device for generating a pulse for each rotation of the rotary shaft is provided at one end of the rotary output shaft. The reason for using such means is that the reference signal generator 9 requires a power source only while the apparatus is operating. The reference signal generator 9 communicates with the main body controller 91 and uses the generated pulse for main body control.

FIG. 9 is a diagram showing the signals of the respective parts showing the state of this drive control, which is almost the same as in FIG. 6, except that the pulse rotates the photosensitive drum 20 of the first image recording part 2. It will happen for the first time. Image recording start signal S ₁
It is necessary to drive the photosensitive drum 20 and count the number of pulses simultaneously with the input. Subsequent main body control is the same as in FIG. 7.

[0058]

As described above, according to the present invention,
In an image recording apparatus capable of multiplexing and recording images formed on a plurality of photosensitive drums on one recording medium, it is possible to prevent positional deviation of images multiplexed on the recording medium.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of an example of an image recording apparatus capable of implementing the present invention.

FIG. 2 is an internal configuration diagram of a paper handling unit 4 shown in FIG.

FIG. 3 is a block diagram when high-speed recording is performed using the image recording apparatus shown in FIG.

FIG. 4 is a block diagram when double-sided recording is performed using the image recording apparatus shown in FIG.

5 is a block diagram in the case of performing multiplex recording using the image recording apparatus shown in FIG.

FIG. 6 is a block diagram showing a configuration when the present invention is applied to the image recording apparatus shown in FIG.

7 is a waveform diagram for explaining a control operation in the configuration shown in FIG.

FIG. 8 is a block diagram showing the configuration of another embodiment of the present invention.

9 is a waveform diagram for explaining a control operation in the configuration shown in FIG.

[Explanation of symbols]

1 Image Recording Apparatus Main Body 2 First Image Recording Section 3 Second Image Recording Section 4 Paper Handling Section 9 Reference Signal Generation Section 91 Main Body Control Section 101, 201, 221, 301, 321 Drive Source (Motor) P ₁ Main Body Operation Start Reference pulse at time S ₁ Image recording start signal

Front page continuation (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location G03G 21/14 H04N 1/00 108 Q 1/29 F

Claims (2)

[Claims] 1. An image recording in which a plurality of photosensitive drums are independently scanned by a laser beam using a plurality of deflectors, and the images formed on the respective photosensitive drums can be multiplexed and recorded on one recording medium. In the apparatus, a plurality of driving means for respectively driving the plurality of deflectors and a reference clock signal common to the plurality of deflectors are generated, and each rotation of the plurality of deflectors is the common reference. An image recording apparatus comprising: a control unit that controls the plurality of drive units so as to be synchronized with a clock signal. 2. An image recording apparatus capable of multiplexing and recording images formed on a plurality of photosensitive drums on one recording medium, and a plurality of driving means for respectively driving the plurality of photosensitive drums, A control unit that generates a reference clock signal common to the plurality of photosensitive drums and controls the plurality of driving units so that the rotations of the plurality of photosensitive drums are synchronized with the common reference clock signal. An image recording apparatus characterized by having.