JPH07210059A - Image forming device - Google Patents

Abstract

(57) [Abstract] [Purpose] For example, in an image forming apparatus such as an electrophotographic printer, a thick sheet such as an envelope is used as a recording sheet, and a manual sheet feeding in which a sheet size smaller than the minimum sheet size is unrecognizable. Provided is a means for preventing a paper jam in the duplex unit or an inability to process an optimum amount when the paper is fed from the mouth and double-sided printing is designated. Therefore, when the recording paper 608 is fed from the paper feed port, the paper trailing edge sensor 118 and the paper thickness sensor 70 for detecting information such as the paper size and the paper thickness.
1 and the like are provided, and the switching of the single-sided / double-sided printing mode and the control of the double-sided sheet feeding timing are performed based on this information.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus such as an electrophotographic printer having a paper feed port whose recording paper size cannot be recognized and a recording paper conveying mechanism for double-sided recording. It is a thing.

[0002]

2. Description of the Related Art A conventional electrophotographic printer of this type has a mechanical section as shown in the schematic block diagram of FIG. That is, in FIG. 10, 101 is a photosensitive drum that is an electrostatic latent image carrier, and 102 is a semiconductor laser that is a light source. 103 is the photoconductor drum 10.
A charging roller 104 for uniformly charging the surface 1 and a developing device 104 for developing the electrostatic latent image formed on the photosensitive drum 101 with toner. Reference numeral 105 denotes a transfer roller for transferring the developed toner image onto a predetermined recording sheet,
Reference numeral 106 denotes a fixing roller for fusing the toner transferred onto the recording sheet, and reference numeral 107 denotes a manual sheet feeding roller that has a function of identifying the sheet size of the recording sheet and that feeds the sheet to a conveyance path from a manual sheet feeding port. is there.

Reference numeral 108 corrects the skew by hitting the optical end of the fed recording paper and corrects the photosensitive drum 101.
A registration roller for synchronizing image writing (recording / printing) to and from paper conveyance. Reference numeral 109 is a registration sensor for detecting the trailing edge of the recording paper and measuring the length of the fed paper in the transport direction, and 110 is a discharge roller for discharging the fixed paper. Reference numeral 111 is a paper discharge sensor for detecting the presence or absence of paper after fixing.

Reference numeral 112 denotes a double-sided reversal flapper for switching the discharge destination depending on whether the printing on the recording paper is one-sided or double-sided, and 113 is a reversing roller for reversing the recording paper by reversing the recording paper during double-sided printing. , 114 are reversing sensors for detecting that the paper has been conveyed into the duplex unit.

Denoted at 115 is a transport roller for transporting the reversed recording sheet, and denoted at 116 is a re-feed sensor for detecting that the inverted sheet has been transported to a position where it can be re-fed. , A re-feeding roller for feeding the re-fed recording sheet to a conveyance path for printing again. 11
Reference numeral 8 denotes a trailing edge sensor for detecting the trailing edge of the paper for measuring the length of the recording paper in the sub-scanning direction when the recording paper is fed from a paper feed port whose paper size cannot be recognized.

A circuit configuration block diagram of a control system for controlling the above-mentioned mechanism section is shown in FIG. 2 (which is also used in the description of the embodiments described later). In FIG. 2, reference numeral 201 is for expanding image code data from an external device such as a host computer (not shown) into bit data necessary for printing by the printer, and reading information inside the printer by communication or the like to display it. It is a printer controller.

Reference numeral 202 denotes a printer engine control unit for controlling the operation of each unit of the printer engine in accordance with an instruction from the printer controller 201 and notifying the printer controller 201 of printer internal information. 20
Reference numeral 3 denotes a paper conveyance control unit for driving and stopping a motor, rollers, etc. for conveying recording paper in accordance with an instruction from the printer engine control unit 202. Reference numeral 204 denotes a high voltage control unit for performing output control of each high voltage in each process such as charging, development, transfer, etc. according to an instruction from the printer engine control unit 202. Reference numeral 205 denotes an optical system control unit for driving / stopping the scanner motor and turning on / off the laser beam according to an instruction from the engine control unit 202.

Reference numeral 206 denotes a sensor input unit for transmitting information of the registration sensor and the paper discharge sensor to the engine control unit 202, and 207 adjusts the temperature of the fixing device to the temperature designated by the printer engine control unit 202. Is a temperature control unit. Reference numeral 208 denotes the printer engine control unit 20.
According to the instruction of 2, the reversing roller 113 and the conveying roller 11
5. A double-sided unit control unit for driving / stopping the re-feeding roller 117 and the like, and controlling the information of the reversing sensor 114 and the re-feeding sensor 116.

In the conventional printer of this type, when a print request is issued from the printer controller 201, the printer engine control unit 202 drives a recording paper conveying system including the photosensitive drum 101, and at the same time, charges, develops, and transfers. Each high voltage is started in each process such as, and the scanner motor is started up to the specified rotation speed.

When these processes are completed, the sheet feeding operation is started from the designated sheet feeding port, and after a predetermined time, the registration sensor 10
9 is in the "paper present" state. After the registration sensor is in the "paper present" state, the paper feeding operation is temporarily stopped and restarted when the printer controller 201 is vertically synchronized, and toner is applied to the recording paper on the photosensitive drum 101 and the fixing roller. In the case of single-sided printing, which is fused at 106, the sheet is discharged as it is from the apparatus.

Further, in the case of continuous printing, when the recording paper is fed from the manual feed port whose paper size cannot be recognized, when the trailing edge sensor detects the trailing edge of the preceding sheet, the next sheet is fed. By feeding the paper, it is possible to keep the paper at a predetermined interval and obtain the maximum throughput.

[0012]

However, the above-mentioned conventional examples are accompanied by the following problems. That is, (1) When a double-sided unit such as an envelope that cannot convey thick paper is attached and the thick paper such as an envelope is conveyed from the manual paper feed port whose paper size cannot be recognized and double-sided printing is designated, There is a drawback that paper jams (jams) occur inside.

(2) Further, when a recording paper of a size smaller than the maximum size that can be fed from the paper feed port whose paper size cannot be recognized is fed, the optimum processing amount (throughput) is achieved in the paper conveyance during double-sided printing. There was a problem that could not be obtained.

The present invention has been made in consideration of the problems of the conventional example as described above. Even when the paper is fed from the paper feed port whose paper size cannot be recognized as described above, the paper jam or the processing capability is caused. The purpose is to provide a means for preventing the unreasonable decrease of the.

[0015]

Therefore, in the present invention, an image forming apparatus of this type is provided with a recording sheet conveyance path for double-sided recording, a sheet feed port for which the sheet size of the recording sheet cannot be recognized, and
When the paper is fed from this paper feed port, it has a detecting means for detecting the information such as the paper size and the paper thickness of the recording paper, and based on the detected output information, recording on one side or both sides of the recording paper It is intended to achieve the above-described object by controlling the mode switching and the re-feed timing for double-sided printing.

[0016]

With the above-described structure of the present invention, when the recording paper is conveyed from the paper feed port where the paper size cannot be recognized, the means for recognizing the paper size is provided, so that the paper jam in the duplex unit can be prevented. In addition to the above, it is possible to always obtain a processing capacity suitable for the paper size.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on a plurality of embodiments: (Embodiment 1) A schematic structural view of a mechanical portion of a first embodiment of an electrophotographic printer according to the present invention (the above-mentioned conventional example FIG. 10). (Corresponding figure) is shown in FIG. The same (corresponding) components as in FIG. 10 are represented by the same reference numerals. In FIG. 1, 101 to 117 are the same as in FIG.
Since it is the same as that in 0, duplicate description of each is omitted here. Reference numeral 118 in FIG. 1 denotes a paper rear edge detection sensor for measuring the length of the recording paper in the sub-scanning direction when the recording paper is fed from a paper feed port whose paper size cannot be recognized. The trailing edge sensor 118 of the paper is a photo interrupter including a phototransistor and an LED, and its circuit diagram is shown in FIG. The presence or absence of paper is detected by the signal A in FIG.

The circuit configuration diagram of the control system of this electrophotographic printer is shown in FIG. Since the description of this figure has already been made when the above-mentioned conventional example FIG. 10 is described, duplicate description will be omitted.

FIG. 4 shows a flow chart of a recording paper size recognition control sequence in continuous printing on both sides of the recording paper from the manual paper feed port in which the paper size cannot be recognized in this embodiment.

In FIG. 4, when a print request is made, the paper size from the manual paper feed port is set to the maximum printable paper size (step S401). Rear end sensor 1
When 18 detects the leading edge of the sheet (step S402), the sheet size detection timer is started (step S40).
3). After that, when the paper trailing edge sensor 118 detects the trailing edge of the paper (step S404), the paper size detection timer is stopped (step S405). The time T ₁ defined by the paper size detection timer is compared with the time T _P for each paper size stored in the memory in advance to detect the size of the conveyed paper (step S406).

By storing the paper size of the fed / conveyed paper detected by the trailing edge sensor 118, the paper feed timing of the second surface during double-sided printing is controlled.

(Embodiment 2) It is assumed that the structure of the mechanical portion of the second embodiment of the electrophotographic printer according to the present invention is the same as that of the first embodiment shown in FIG. However, since the paper transport path for double-sided printing is not suitable for transporting raw paper such as envelopes, the setting position of the trailing edge sensor 118 is set as follows. That is, the double-sided flapper 112 and the rear-end sensor 118 are located at a distance longer than the maximum size of an envelope that can be printed on one side.
Set the distance to.

FIG. 5 shows a control sequence flowchart of the envelope detection. Steps S501 to S510 are step S4 in the flowchart of FIG. 4 of the first embodiment.
Since it is the same as 01 to S410, duplicate description will be omitted.

If the time T ₁ detected by the paper size detection timer is shorter than the transport time T _P2 of the maximum size envelope stored in the memory in advance, it is determined that the envelope is an envelope (step S5).
11), it is determined that the sheet is not suitable for double-sided printing, and the sheet is ejected out of the machine (step S512), and the printing is finished.

(Embodiment 3) FIG. 6 is a schematic configuration diagram of a mechanical portion of an image forming apparatus according to a third embodiment of the present invention. Figure 7
FIG. 4 is a circuit configuration block diagram of the recording medium thickness detecting means (paper thickness sensor unit).

In FIGS. 6 and 7, reference numeral 701 is the recording medium 6.
08 thickness detection means (paper thickness sensor section), and the recording medium thickness detection information detected by this detection means 701 also serves as paper thickness determination means (in this embodiment, the CPU 702 of the image forming apparatus main body 700 shown in FIG. 7 also serves. ) Determines whether or not it is suitable for double-sided printing.

Recording medium thickness detecting means 701 of this embodiment
Is disposed in a transport path portion downstream of the transport roller 606 upstream of the registration roller pair 607 in the transport direction of the recording medium, and includes a reflection type LED 701c as a light source and a phototransistor 701a as a light receiving element. It is a paper thickness sensor. In FIG. 6, 601 is a photosensitive drum, 602 is a charging roller, 603 is a developing device, 604 is a transfer roller, 611 is a fixing roller, and 612 is a double-sided reverse flapper.

The light emitted from the LED 701c is reflected on the surface of the recording medium 608. Light reflected on the surface of the recording medium 608 is supplied to the base of the phototransistor 701a, and a current according to the intensity of light, that is, a current according to the thickness of the recording medium 608 flows to the phototransistor 701a, and the point in FIG. Determine the voltage of part A. The CPU 702 of the image forming apparatus main body 700 receives the voltage at the point A and determines whether the recording medium is suitable for double-sided printing. In FIG. 7, 710 is a double-sided option unit, 711 is its CPU, and 712 is a double-sided inversion flapper drive control circuit.

FIG. 8 is a sequence flowchart showing a paper conveyance control procedure at the time of double-sided printing in the image forming apparatus of the third embodiment. This control procedure will be described with reference to FIG. 8; the system starts a printing operation in response to a print command from an external device or the like, and transfers a transfer material,
One recording medium 608 such as a recording material is fed (step S801). The fed recording medium 608 is set on the registration roller pair 607 via the conveyance roller pair 606 (step S802). When the recording medium 608 is set in the resist, the sheet thickness sensor unit 701 detects the sheet thickness (detection of the thickness of the recording medium 608) (step S80).
3).

Image forming apparatus main body C which has received the paper thickness detection result
The PU 702 indicates that the electric potential VA of the point A is VX (VX represents the electric potential of the point A when the maximum paper thickness capable of double-sided printing is set,
In this embodiment, it is determined whether or not the value is equal to or less than that (provided in the CPU 702 of the image forming apparatus main body 700) (step S804), and if no, it is determined that double-sided printing is possible and conventional double-sided printing is performed (step S808). ), Yes, it is determined that double-sided printing is impossible (step S805), and double-sided printing stop information is sent to the CPU 71 of the double-sided option unit 710.
1 (step S806).

The CPU 711 of the double-sided option unit 710, which has received the double-sided print cancel information, outputs it to the double-sided inversion flapper drive control circuit 712. Then, the double-sided inversion flapper 612 in FIG. 6 is turned off to prevent the recording medium 608 from being conveyed into the double-sided option unit 710 (step S807).

As described above, in this embodiment, the recording medium 60
By providing the detection unit 701 for detecting the paper thickness of No. 8, it is possible to prevent the recording medium 608, which is not suitable for double-sided printing, from being conveyed into the double-sided option unit 710. It is possible to prevent damage to the option unit 710 in advance.

The thickness detecting means 70 for the recording medium 608
Reference numeral 1 is a pair of conveyance rollers 606 and a pair of registration rollers 607.
It is also possible to adopt a configuration in which the thickness of the recording medium 608 is detected by detecting the axial displacement between when the recording medium 608 is not passed and when the recording medium 608 is passed. It is also possible to input from a host computer or the like.

(Embodiment 4) In Embodiment 3, the paper thickness control means 701 detects the presence / absence of paper in the paper thickness control means 701, although the paper conveyance control into the double-sided option unit 710 is performed based on the paper thickness detection result. The present invention can be applied even to a configuration that also serves as means.

FIG. 9 shows a control sequence flowchart for detecting the presence / absence of a sheet according to the fourth embodiment; the system enters a printing operation in response to a print command from an external device or the like, and a sheet size not shown cannot be recognized. A recording medium 608 such as a transfer material or a recording material is fed from the paper mechanism via the pair of conveying rollers 606 in FIG. 6 (step S
901). Then, the sheet presence / absence detection unit (also the sheet thickness detection unit 701 in this embodiment) performs sheet presence / absence detection to confirm that the recording medium 608 is conveyed (step S902).

When the CPU 702 of the image forming apparatus main body 700 receives the detection result of the presence / absence of paper, the potential VA at the point A is V
It is determined whether or not it is 0 (V0 represents the potential at the point A when there is no paper, which is provided in the CPU 702 of the image forming apparatus main body in this embodiment) (step S903), and yes. If so, it is determined that there is no paper and step S9 is performed.
Returning to 02, if no, it is determined that there is paper.

Next, it is judged whether or not the recording medium 608 is set with a resist (step S904), and if it is set, a series of recording operations represented by development, transfer, fixing and the like are performed (step S905).

The presence / absence of paper is detected again (step S
906), it is determined whether or not the potential VA at the point A is V0 or more (step S907), and if no, step S9.
Returning to 05, if yes, it is determined that there is no paper.

When the absence of paper is detected, the paper feed timing timer is started (step S908). Next, if there is no print request, this paper presence / absence detection sequence is ended, and if there is a print request, the process proceeds to the next step.

Paper feed timing timer T1 (here, T1
Starts the next sheet feeding operation at the time when the sheet feeding timing that satisfies the maximum processing amount of the image forming apparatus is reached.

As described above, in this embodiment, the recording medium 608 can be fed without lowering the processing capability even when the paper is fed from the paper feed port whose paper size cannot be recognized.

[0042]

As described above, according to the present invention,
When performing double-sided printing from the paper feed port where the paper size cannot be detected, by detecting the paper type such as paper size and paper thickness, it is possible to record at the re-feed timing according to the paper size. The maximum processing amount (throughput) that can be realized by the forming apparatus can be obtained. In addition, it is possible to prevent jams and other obstacles by forcibly ejecting paper that is judged to be incapable of double-sided recording from the length and thickness of recording paper to the outside of the machine with only single-sided recording. .

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a mechanical unit according to a first embodiment.

FIG. 2 is a circuit configuration block diagram of the control system shown in FIGS. 1 and 6.

FIG. 3 is a circuit diagram of a paper trailing edge sensor.

FIG. 4 is a control sequence flowchart during continuous printing.

FIG. 5 is an envelope detection control sequence flowchart of the second embodiment.

FIG. 6 is a schematic configuration diagram of a mechanical unit according to a third embodiment.

FIG. 7 is a circuit configuration block diagram of a paper thickness sensor unit.

FIG. 8 is a sequence flowchart of a paper conveyance control procedure during double-sided printing according to the third embodiment.

FIG. 9 is a sequence flowchart of a paper presence / absence detection control procedure according to the fourth embodiment.

FIG. 10 is a schematic configuration diagram of a mechanical section of an example of a conventional electrophotographic printer.

[Explanation of symbols]

 101,601 Photosensitive drum 102 Semiconductor laser 107 Manual paper feeding roller 109 Registration sensor 112,612 Double-sided reversal flapper 118 Paper trailing edge sensor 201 Printer controller 202 Printer engine control unit 203 Paper transport control unit 608 Recording medium 700 Image forming apparatus main body 701 Paper thickness sensor 710 Double-sided optional unit

Claims (1)

[Claims] 1. A recording paper conveyance path for double-sided recording, a paper feed port in which the paper size of the recording paper cannot be recognized, and a paper size and a paper thickness of the recording paper when fed from this paper feed port. A detection means for detecting information, and based on the detection output information, it is configured to control the recording mode switching of one side or both sides of the recording sheet and refeed timing at the time of double-sided printing. A characteristic image forming apparatus.