JP2003241480A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten a period of image forming time when resuming an image forming operation. <P>SOLUTION: When the jamming is detected before a recording material reaches a secondary transfer part (Yes in S1, Yes in S2), a transfer belt is separated and released from an intermediate transfer body (S3), thereby preventing a toner image transferred to the intermediate transfer body 205 from being transferred to the transfer belt, and the process of primarily transferring the toner image from a photoreceptor drum to the intermediate transfer body 205 is not interrupted but continued to the trailing end of the toner image and then finished (S4). Thereafter a display indicating the occurrence of a jam is provided on an operation part in order to urge a user to remove the jam (S5). After the removal of the jam is detected, a recording material is fed in correspondence with the position of the toner image on the intermediate transfer body, and the toner image on the intermediate transfer body is secondarily transferred with the transfer belt (S6). <P>COPYRIGHT: (C)2003,JPO

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 having an intermediate transfer member.

[0002]

2. Description of the Related Art A four-color full-color image forming apparatus having an intermediate transfer member (for example, an intermediate transfer belt or an intermediate transfer drum) is known.

This product sequentially forms yellow (Y), magenta (M), cyan (C), and black (K) toner images on a photosensitive drum, and sequentially performs primary transfer on an intermediate transfer member. Then, the four color toner images are once superposed on the intermediate transfer member, and then the four color toner images are secondarily transferred onto the recording material at once to form a four color full color image on the recording material. To do.

In such an image forming apparatus, in general, when forming a full-color toner image of four colors, the intermediate transfer member rotates four times, but when forming a black and white image, the intermediate transfer member is rotated. It only makes one revolution.

[0005]

In the above-described image forming apparatus, the recording material jams or images are continuously formed before the toner image on the intermediate transfer member is secondarily transferred to the recording material. If no recording material is detected in the middle of the process, the toner image on the intermediate transfer member is once cleaned at the time of recovery after jam processing or replenishment of recording material, and then image formation is restarted from the beginning. . Therefore, there is a problem that it takes time to obtain the image output after the recovery. Further, since all the toner images formed on the intermediate transfer body are once cleaned, there is a problem that the toner is wastefully consumed. Furthermore, since the drive is stopped when a jam occurs, cleaning is performed when a long size image is formed in which the primary transfer of all images has not been completed when a jam occurs.
The image formation had to be redone from the beginning.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an image forming apparatus and a recovery method for performing image output at the time of recovery in a short time and suppressing waste of toner. It is what

[0007]

The invention according to claim 1 is
Primary transfer of transferring the toner image formed on the image bearing member onto the intermediate transfer member at the primary transfer portion is repeated for the toner images of a plurality of colors, and the toner images of a plurality of colors are superimposed on the intermediate transfer member, and thereafter, In an image forming apparatus that collectively transfers toner images of a plurality of colors on an intermediate transfer member to a recording material at a secondary transfer portion, the leading end of the recording material supplied to the secondary transfer portion reaches the secondary transfer portion. If the detection means detects a recording material conveyance failure or no recording material before
The secondary transfer process is not performed on the recording material, the primary transfer process is performed on the intermediate transfer member to the end, and the toner image after the primary transfer is retained on the intermediate transfer member.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the tip of the recording material supplied to the secondary transfer portion is the secondary transfer portion when an image of a single color toner image is formed. Even if the detection unit detects a conveyance failure of the recording material or the absence of the recording material before the arrival at the time, the toner image after the primary transfer is not held on the intermediate transfer body,
It is characterized by

According to a third aspect of the present invention, in the image forming apparatus according to the first aspect, the front end of the recording material supplied to the secondary transfer portion is the secondary transfer portion when an image of a single color toner image is formed. Even if the detection unit detects a defective conveyance of the recording material or the absence of the recording material before the arrival of the toner image, if the single color is black, the toner image of which the primary transfer is completed should be held on the intermediate transfer member. When the single color is a color other than black, the toner image after the primary transfer is held on the intermediate transfer body.

According to a fourth aspect of the present invention, in the image forming apparatus according to the first or third aspect, the toner image held on the intermediate transfer member is discharged after the processing of the defective recording material is completed or the recording material is replenished. When the image forming operation is restarted, the secondary transfer is performed on the recording material supplied to the secondary transfer section.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. The same reference numerals in the drawings denote the same configurations or operations, and duplicated description thereof will be appropriately omitted.

<First Embodiment> FIG. 1 shows an example of an image forming apparatus according to the present invention. The image forming apparatus shown in FIG.
This is an electrophotographic four-color full-color printer, and the drawing is a vertical cross-sectional view showing the schematic configuration thereof.

The printer shown in FIG. 1 (hereinafter referred to as "image forming apparatus") is provided with a color reader unit 1 at the upper part and a color printer unit 2 at the lower part.

First, the structure of the color reader unit 1 will be described. The color reader unit 1 is provided with a document table glass (platen) 101 and an automatic document feeder (ADF) 102. Instead of the automatic document feeder 102, a pressing plate (mirror surface pressure plate or white pressure plate: not shown) for pressing the document against the platen 101 from above may be mounted. Further, the color reader unit 1 is provided with light sources 103 and 104 for irradiating a document. Light source 103,1
As 04, a halogen lamp, a fluorescent lamp, a xenon tube lamp, or the like can be used. Reference numeral 10 in FIG.
Reference numerals 5 and 106 denote reflectors that collect the light from the light sources 103 and 104 on the original. Reference numerals 107, 108, and 109 denote mirrors, and 110 denotes a CCD for reflecting or projecting light from a document.
A lens for condensing light on a (charge-coupled device) image sensor (hereinafter referred to as “CCD”) 111 is shown. Further code 1
12 is a substrate on which the CCD 111 is mounted, reference numeral 100
Is a control unit that controls the entire image forming apparatus, and 113 is a digital image processing unit (reader scanner control unit). Code 1
14 is a light source 103, 104 and a reflector 105, 106.
And a carriage that houses the mirror 107. Code 1
Reference numeral 15 denotes a carriage that houses the mirrors 108 and 109. The carriage 114 has a speed V and the carriage 115 has a speed V / 2, and the sub-scanning direction Y is orthogonal to the electrical scanning direction (main scanning direction X) of the CCD 111.
By mechanically moving to the right (in FIG. 1), the entire surface of the document is scanned. Reference numeral 116 indicates an external I / F (interface) with another device.

FIG. 2 is a block diagram showing the configuration of the control unit 100. The CPU 301, based on the program stored in the memory 302, the digital image processing unit 113, the printer control I / F (interface) 218, the external I
/ F116, exchanges information with the operation unit 303, and controls. The operation unit 303 is configured by a liquid crystal with a touch panel for inputting process execution contents by the operator and for notifying the operator of information regarding processing and warnings.

Next, the digital image processing section 113 will be described. FIG. 3 is a block diagram showing a detailed configuration of the digital image processing unit 113.

The original on the original table glass 101 (see FIG. 1) reflects light from the light sources 103 and 104, and the reflected light is guided to the CCD 111 and converted into an electric signal. In addition,
In the case where the CCD 111 is a color sensor, even if the RGB color filters are inline on the 1-line CCD in the order of RGB, the 3-line CCD is used, and the R filter, the G filter, and the B filter are respectively attached to the CCs.
The filters may be arranged for each D, or the filters may be on-chip or the filters may have a configuration different from that of the CCD. Then, the electric signal (analog image signal) is input to the digital image processing unit 113, sampled and held (S / H) by the clamp & Amp & S / H & A / D unit 502, and the dark level of the analog image signal is clamped to the reference potential. , Amplified to a predetermined amount (the above processing order is not limited to the notation order), A / D converted, and converted into, for example, R
It is converted into a digital signal of 8 bits for each GB.

The converted RGB signals are subjected to shading correction and black correction in a shading section 503, and then in a connection & MTF correction & document detection section 504, a CCD.
When the 111 is a 3-line CCD, since the reading position between the lines in the connecting process is different, the delay amount for each line is adjusted according to the reading speed, and the signal timing is corrected so that the reading positions of the 3 lines are the same. , MTF correction changes the MTF of reading depending on the reading speed and the scaling factor. Therefore, the change is corrected, and the document detection recognizes the document size by scanning the document on the platen glass 101. The digital signal whose reading position timing is corrected is input to the input masking unit 505.
According to the spectral characteristics of the CCD 111 and the light sources 103, 1
04 and the reflectors 105 and 106 correct the spectral characteristics.

The output of the input masking section 505 is an external I /
It is inputted to the selector 506 which can be switched with the F signal. The signal output from the selector 506 is color space compressed &
It is input to the background removal & LOG conversion unit 507 and the background removal unit 514. The signal input to the background removal unit 514 is subjected to background removal, and then input to the black character determination unit 515 that determines whether the original is a black character in the original, and generates a black character signal from the original. Further, the color space compression & background removal & LOG conversion unit 507 to which the output of another selector 506 is input
Then, in color space compression, it is judged whether the read image signal is within the range that can be reproduced by the printer, and if it is included, it is corrected as it is. . Then, the background removal processing is performed, and the LOG conversion unit converts the RGB signals into YM.
Convert to C signal. Then, in order to correct the signal and timing generated by the black character determination unit 515, the color space compression &
The output signal of the background removal & LOG conversion unit 507 is delayed 508.
The timing is adjusted with.

These two types of signals are applied to the moire removing section 509.
Moire is removed in step S4, and the scaling processing unit 510 performs scaling processing in the main scanning direction. Reference numeral 511 denotes a UCR & masking & black character reflection section. The signal processed by the scaling processing section 510 is a signal which is output from the YMC signal by the UCR processing and is output to the printer by the masking processing section. And the determination signal generated by the black character determination unit 515 is fed back to the YMCK signal. The signal processed by the UCR & masking & black character reflection unit 511 is density adjusted by the γ correction unit 512, and then smoothed or edge-processed by the filter unit 513.

The signal processed as described above is converted from an 8-bit multi-valued signal to a binary signal by a binary conversion unit. The conversion method may be any of the dither method, the error diffusion method, and the improved error diffusion method.

Next, the structure of the color printer section 2 will be described.

Reference numeral 218 in FIG. 1 denotes a printer control I / F.
Shows the CPU 301 of the color reader unit 1.
It becomes the receiving point of the control signal from. The color printer unit 2 performs the operation described below based on the control signal from the printer control I / F 218.

Reference numeral 201 indicates a laser scanner. The laser scanner 201 scans a laser beam corresponding to an image data signal in the main scanning direction with a polygon mirror and irradiates the surface of the photosensitive drum 202 after uniform charging to form an electrostatic latent image. The electrostatic latent image formed on the photosensitive drum 202 reaches the sleeve positions of the color developing device 203 and the black developing device 204 by the counterclockwise rotation of the photosensitive drum 202 in FIG.
From the color developing device 203 and the black developing device 204, toner in an amount corresponding to the charge on the photosensitive drum 202 is supplied, and the electrostatic latent image on the photosensitive drum 202 is developed. It should be noted that only the black developing device 204 is used when developing a black monochrome image,
Both the color developing device 203 and the black developing device 204 are used when developing a full-color image.

The toner image formed on the photosensitive drum 202 is transferred (primary transfer) to the intermediate transfer member 205 that rotates clockwise by the counterclockwise rotation of the photosensitive drum 202 at the primary transfer portion T1. The toner image is transferred to the intermediate transfer member 205 by one rotation of the intermediate transfer member 205 when the toner image is a black monochrome image, and four rotations of the intermediate transfer member 205 when the toner image is a full color image. Complete with.

On the other hand, the recording material is picked up by the pickup roller 211 or the pickup roller 212 from the upper cassette 208 or the lower cassette 209, and the recording material such as paper conveyed by the paper feed roller 213 or the paper feed roller 214 is conveyed by the conveyance roller. It is conveyed to the registration roller 219 by 215. Then, this recording material is conveyed between the intermediate transfer body 205 and the transfer belt 206 at the timing when the transfer onto the intermediate transfer body 205 is completed. After that, the recording material is conveyed by the transfer belt 206 and pressed onto the intermediate transfer body 205, and the intermediate transfer body 205 is pressed.
The upper toner image is transferred (secondary transfer) to the surface of the recording material.
The transfer belt 206 can be brought into contact with and separated from the intermediate transfer member 205, and only when the secondary transfer is performed, the intermediate transfer member 2 is transferred.
The secondary transfer portion T2 is formed by being pressed to 05. The toner image transferred to the recording material is heated and pressed by a fixing device 207 having a fixing roller and a pressure roller to be fixed on the surface of the recording material. The recording material on which the toner image is fixed is ejected from the face-up paper ejection port 217. Note that reference numeral 216 in FIG. 1 denotes a manual feed roller for manually feeding the recording material.

On the other hand, the residual toner remaining on the intermediate transfer member 205 without being transferred to the recording material is cleaned by the post-processing control in the latter half of the image forming sequence. In the post-processing control, the residual toner on the intermediate transfer body 205 is charged as a waste toner by the cleaning roller 220 of FIG. 1 to the opposite polarity of the toner polarity at the time of development, and the residual toner of the opposite polarity is transferred to the photosensitive drum 202. It is transcribed again. The cleaning roller 220 can be brought into contact with and separated from the intermediate transfer body 205, and is pressed against the intermediate transfer body 205 only during cleaning. In the photosensitive drum unit, residual toner of opposite polarity is scraped off from the drum surface by a blade (not shown),
It is conveyed to the waste toner box 221 integrated in the photosensitive drum unit. Thus, the intermediate transfer member 20
The residual toner on 5 is completely cleaned, and the post-processing control ends.

In the above-mentioned image forming apparatus, various sensors are provided to detect jams and the presence / absence of recording materials. That is, the upper second sheet-free sensor a, the lower second sheet-free sensor b, the upper sheet-free sensor c, the lower sheet-free sensor d, the refeed sensor e, the manual feed rear edge detection sensor f, and the middle plate position sensor h. A pre-registration sensor i, a separation jam sensor j, a fixing paper discharge sensor k, a reversal sensor l, and a double-sided sensor m are provided. In the present invention, the position of the recording material is detected based on the outputs of these sensors. That is, when a jam occurs, it is determined whether or not the leading edge of the recording material has reached the secondary transfer portion.

Specifically, the judgment is made as follows.

As shown in FIG. 1, the pickup roller 2
The recording material fed from 11 or the pickup roller 212 sequentially passes through the sheet re-feeding sensor e, the pre-registration sensor i, the separation jam sensor j, and the fixing ejection sensor k, which are arranged in the conveyance path, and is ejected from the ejection port 217. The paper is ejected. CPU301
(See FIG. 2) sequentially checks whether or not the recording material is detected within a predetermined time by these sensors as the recording material is conveyed. If the sensor cannot detect the passage of the recording material within a predetermined time, a jam occurs. The predetermined time is a value obtained by adding a margin to the time from when the leading edge of the recording material is detected by the sensor upstream of the transport path until it reaches the next sensor downstream.

Next, the determination of whether the leading edge of the recording material has reached the secondary transfer portion when a jam occurs will be described.

If the leading edge of the recording material is not detected within a predetermined time by the re-feed sensor e after the pickup roller 211 or the pickup roller 212 is driven to feed the recording material, or the re-feed sensor e is set to the recording material. If the front edge of the recording material is not detected by the pre-registration sensor i within a predetermined time after the front edge of the sheet has passed, it is determined as a pre-secondary transfer jam, and the process branches to “yes” in S2 of FIG.

The jam generated after the front edge of the recording material is detected by the pre-registration sensor i is "no" in S2 of FIG.
Branch to.

The same applies to the manual feeding. If the recording material fed by the driving of the manual feeding roller 216 is not detected by the middle plate position sensor h and the pre-registration sensor i within a predetermined time, it is judged as a pre-secondary transfer jam. Then, the process branches to “yes” in S2 of FIG.

FIG. 4 is a flow chart showing the processing when a jam occurs. The flow of processing when a jam occurs will be described with reference to this figure.

If a jam is detected before the recording material reaches the secondary transfer portion (Yes in S1 and Yes in S2), the intermediate transfer body 205 (see FIG. 1) is transferred to the transfer belt 20.
6 are separated from each other, and the pressure contact of the transfer belt 206 to the intermediate transfer body 205 is released (S3).
The toner image transferred to the transfer belt 206 is prevented from being transferred to the transfer belt 206, and the primary transfer processing of the toner image from the photosensitive drum 202 to the intermediate transfer member 205 is performed without interruption to the rear end of the toner image. , Then stop (S
4). Then, a message indicating a jam is displayed on the operation unit 303 (see FIG. 4) to prompt the user to perform a jam process (S5).
If it is detected that the jam has been processed, the intermediate transfer member 20
The recording material is fed at the position of the toner image on the recording medium 5, and the toner image on the intermediate transfer body 205 is secondarily transferred onto the recording material by the transfer belt 206 (S6), and the toner image is secondarily transferred. After the toner image is fixed on the surface of the recording material by the fixing device 207, the recording material is discharged from the face-up discharge port 217. As a result, when a jam occurs, image formation is performed in a shorter time at the time of restarting the image forming operation after jam processing (at the time of recovery), as compared with the case where the toner image on the intermediate transfer body 205 is once removed and recreated. It is possible to prevent waste of toner.

On the other hand, if a jam is detected after the recording material reaches the secondary transfer portion (No in S2), the image forming process is immediately stopped and the operation portion 303 is informed of the jam. And prompt the user to clear the jam (S
7). If it is detected that the jam has been processed, the cleaning process is first performed to clean the intermediate transfer body 205 (S8), and then the image forming process is restarted from the beginning (S9).

In the above description, in all image formation, in the case of a jam before the secondary transfer portion, the intermediate transfer member 20 is used.
Although the toner image on 5 is held, in the case of a black and white image, even if a new toner image is recreated, the intermediate transfer member 2
You only need to make one rotation of 05, so you may make a new one. Generally, in a four-color full-color image forming apparatus, a four-color toner of yellow, magenta, cyan, and black is used to form a color image. Therefore, when the image formation is performed by using only one of the above-mentioned four colors, not limited to the above-mentioned black-and-white image, the toner image is rotated by one rotation of the intermediate transfer member 205 as in the case of the black-and-white field image. Can be created, so make a new toner image and
When images are formed using toners of colors or more, the toner image on the intermediate transfer body 205 may be held at the time of jamming before the secondary transfer portion. Note that, in the image forming apparatus shown in FIG. 1, even when an image is formed by using only a single color toner, in the case of a single color other than black, it is used for development in the color developing device 203. It is necessary to move the developing device to a position facing the photosensitive drum 202. Therefore, it takes longer time to form a toner image of a toner image than in the case of a black single color (black and white image) which does not require such movement. Therefore, even in the case of single-color image formation, when the color is other than black, the toner image on the intermediate transfer body 205 may be held at the time of jamming before the secondary transfer portion as described above. .

Further, in this embodiment, the intermediate transfer member 20 is used.
A hard cylindrical intermediate transfer drum was used as 5, but the invention is not limited to this. For example, as long as intermediate transfer such as a belt-shaped intermediate transfer belt can be realized,
Any shape of the intermediate transfer member may be used.

The present invention can also be applied to a so-called long size toner image in which the length of the toner image along the recording material conveyance direction is longer than the peripheral length of the photosensitive drum 202. .

[0041]

As described above, according to the present invention,
If the detection unit detects a jam of the recording material or the absence of the recording material before the leading edge of the recording material supplied to the secondary transfer unit reaches the secondary transfer unit, the secondary transfer processing is performed on the recording material. Instead, the primary transfer process for the intermediate transfer member is performed to the end, and the toner image after the primary transfer is held on the intermediate transfer member, so that, for example, when the image forming operation is restarted, the toner image is held on the intermediate transfer member. Since it is possible to immediately secondarily transfer the existing toner image onto the recording material, it is possible to shorten the image forming time when the image forming operation is restarted, and prevent waste of toner.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a schematic configuration of an electrophotographic four-color full-color printer, which is an example of an image forming apparatus according to the present invention.

FIG. 2 is a block diagram showing a configuration of a control unit of the image forming apparatus.

FIG. 3 is a block diagram showing a configuration of a digital image processing unit.

FIG. 4 is a flowchart showing a flow of operations when a jam occurs.

[Explanation of symbols]

202 image carrier (photosensitive drum) 205 Intermediate transfer body T1 primary transfer part T2 secondary transfer part

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 21/00 500 G03G 21/00 500 F term (reference) 2H027 DA38 DC14 DC18 ED24 EE07 EF10 EK04 EK09 GB06 2H030 AD16 BB24 BB42 BB56 BB63 2H072 AA02 AA05 AA07 AA16 AA22 AB19 2H200 GA10 GA23 GA34 GA47 GB12 GB25 JA08 JA29 JB06 JC02 JC12 JC19 LB03 LB15 LB18 PA10 PA27 PA28 PB11 BAB06 BB00 CC03 BA03

Claims (4)

[Claims] 1. A primary transfer in which a toner image formed on an image bearing member is transferred onto an intermediate transfer member at a primary transfer portion is repeated for a plurality of color toner images to form a plurality of color toner images on the intermediate transfer member. In an image forming apparatus in which toner images of a plurality of colors on an intermediate transfer member are collectively transferred to a recording material at a secondary transfer portion in a secondary transfer portion, the leading end of the recording material supplied to the secondary transfer portion is the secondary transfer portion. If the detection unit detects a conveyance failure of the recording material or the absence of the recording material before reaching the next transfer portion, the secondary transfer processing for the recording material is not performed, and the primary transfer processing for the intermediate transfer member is performed. An image forming apparatus, characterized in that the toner image after the completion of the primary transfer is held on the intermediate transfer member. 2. When an image of a single color toner image is formed, the detection unit detects that the recording material is not conveyed well or the recording material is fed before the front end of the recording material supplied to the secondary transfer portion reaches the secondary transfer portion. The image forming apparatus according to claim 1, wherein the toner image after the primary transfer is not held on the intermediate transfer body even when the absence is detected. 3. When an image of a single color toner image is formed, before the leading edge of the recording material supplied to the secondary transfer section reaches the secondary transfer section, the detection means detects defective conveyance of the recording material or the recording material. Even when the absence is detected, when the single color is black, the toner image of which the primary transfer is completed is not held on the intermediate transfer body, and when the single color is a color other than black, the primary transfer is completed. The image forming apparatus according to claim 1, wherein the toner image is held on the intermediate transfer member. 4. The toner image held on the intermediate transfer member is transferred onto the recording material supplied to the secondary transfer portion when the image forming operation is restarted after the processing of the defective recording material is completed or the recording material is replenished. The image forming apparatus according to claim 1 or 3, wherein the image is transferred next.