JP2003122086A - Process control mechanism for image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently perform a process control with a simple and easy constitution by utilizing the shifting action of a transfer/carrying belt. SOLUTION: As a process control mechanism of a digital color copying machine provided with 1st to 4th image forming stations S1 to S4 separately provided with a photoreceptor drum 5 and the transfer/carrying belt 44c for carrying a recording medium P, and for performing the process control by detecting the density or the line width of a developer pattern on a calibration plate and the transfer/carrying belt, the transfer/carrying belt is constituted so that the belt can be shifted to a monochromatic image forming position at the time of forming a monochromatic image by using only the 1st image forming station, and also, the belt can be shifted to the multicolor image forming position at the time of forming the multicolor image by using all the image forming stations. At the time of shifting the belt to the monochromatic image forming position, the calibration is performed, on the other hand, at the time of shifting to the multicolor image forming position, the density of the developer pattern or the line width of the pattern on the transfer/carrying belt is detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image in which monochromatic image formation is performed by converting the transfer material conveying belt so as to retreat to the remaining image forming stations other than the most upstream image forming station. The present invention relates to improvement of a process control control mechanism that enables simple and efficient process control control for correcting the density or line width of a developer pattern in a forming apparatus.

[0002]

2. Description of the Related Art In recent years, in order to make a color type image forming apparatus compact and to improve image processing speed, a plurality of photoconductors corresponding to the number of hues are used, and a sheet conveying process is performed once. Nevertheless, an image forming apparatus using a tandem system that enables color image formation and monochrome image formation has been widely developed.

By the way, in such a tandem type image forming apparatus, process control control is performed by a process control control mechanism. In particular,
The sensor detects the density or line width of the reference developer pattern formed on the calibration plate, and the sensor detects the density or line width of the developer pattern formed on the transfer material transport belt. Then, based on the density or line width of the developer pattern detected by performing the above calibration, the image forming conditions such as the main charge amount, the developer density, the transfer output, or the exposure light amount are changed to transfer the transfer material. The density or line width of the developer pattern detected on the transport belt is corrected. As a sensor for detecting the density or line width of the developer pattern, a sensor having a light receiving / light emitting portion is applied.

In that case, as an example of the process control control mechanism, as shown in FIGS. 9 and 10, a sensor c which is moved forward and backward by a solenoid b is provided so as to be able to come into contact with and separate from the surface of the transfer material conveying belt a. A calibration plate e that moves in and out by a solenoid d is provided on the transfer material conveying belt a so that the sensor c can move in and out on the moving path of the sensor c (between the sensor c and the surface of the transfer material conveying belt a). When the density or line width of the developer pattern is detected, the sensor c is brought closer to the facing position (the position shown in FIG. 9) facing the surface of the transfer material transport belt a by the solenoid b, while the calibration is executed. At this time, the sensor c is separated from the solenoid b and the calibration plate e is moved forward and backward by the solenoid d. By projecting to the facing position (the position shown in FIG. 10) facing each other, the sensor c is equidistant from the developer pattern (the surface of the transfer material transport belt a and the calibration plate e) at each facing position. I try to face each other.

[0005]

However, in the process control control mechanism described above, when performing the process control control, the sensor c and the calibration plate e are moved to their facing positions by the respective solenoids b and d. Since it is necessary, the process control control mechanism itself becomes very complicated, and
The number of parts will increase and the process control will also become very complicated.

On the other hand, in the image forming apparatus using the tandem system, when an image is formed in a single color, it is located at the most upstream side of the image forming stations arranged from the upstream side to the downstream side in the conveying direction of the transfer material. There is also a configuration in which only the image forming station that is used is used, and conversion is performed so that the transfer material transport belt is retracted with respect to the remaining image forming stations, so that the most upstream image forming station performs single-color image formation. .

The present invention has been made in view of the above points, and an object of the present invention is to efficiently perform process control control by a simple mechanism by utilizing the conversion operation of the transfer material conveying belt described above. An object of the present invention is to provide a process control control mechanism of an image forming apparatus.

[0008]

In order to achieve the above object, according to the present invention, a plurality of image forming stations each provided with a charger, a writing optical system, a developing device and a cleaning device around a photoconductor, and an image forming device. And a transfer material transport belt for transporting the transfer material, which is located at the most upstream side of the image forming stations arranged from the upstream side to the downstream side in the transfer material transport direction when forming an image in a single color. In the image forming apparatus configured to perform single-color image formation by the most upstream image forming station by using only the image forming station and retracting the transfer material transport belt from the other remaining image forming stations, Calibration is performed to detect the density or line width of the developer pattern that is formed on the transfer material transport belt. The density or line width of the developer pattern detected on the transfer material conveying belt is detected based on the density or line width of the developer pattern detected by executing the calibration. It is premised on a process control control mechanism for performing process control control for correcting the width. Further, while the transfer material conveying belt is retracted to a monochromatic image forming position when a monochromatic image is formed using only the most upstream image forming station, a multicolor image is formed when a multicolor image is formed using all the image forming stations. It is configured to be convertible so as to return to the image forming position. Then, while the transfer material transport belt is retracted to the single-color image forming position, the calibration is executed, and when the transfer material transport belt is returned to the multi-color image forming position, the calibration is performed on the transfer material transport belt. The density or line width of the developer pattern is detected.

According to this specific matter, the conversion operation of the transfer material transport belt is used to perform the calibration when the transfer material transport belt is retracted to the single-color image forming position, while the transfer material transport belt is often used. When returning to the color image forming position, the density or line width of the developer pattern on the transfer material conveyance belt is detected,
When performing the process control control by the process control control mechanism, it is not necessary to move the sensor and the calibration plate using respective solenoids. Therefore, the process control control mechanism itself becomes very simple, the number of parts is reduced, and the process control control can be efficiently executed with a simple configuration.

In particular, when the process control control is executed when the apparatus main body is powered on, when the standby time has passed a predetermined time, and when the number of image-formed transfer materials exceeds the predetermined number. On the basis of the density or line width of the developer pattern detected by executing the calibration, it becomes possible to accurately correct the density or line width of the developer pattern on the transfer material transport belt at a desired timing. It is possible to always perform stable image formation.

In particular, the following constitutions are given as concrete examples of the process control control mechanism.

That is, the calibration plate provided at the calibration execution position and having the density or line width of the reference developer pattern formed thereon, and the developer pattern on the calibration plate and the transfer material conveying belt Equipped with a sensor that detects density or line width,
The distance between the sensor and the calibration plate when performing calibration, and the distance between the sensor and the surface of the transfer material transport belt when detecting the density or line width of the developer pattern on the transfer material transport belt. The distance is made equal to each other.

According to this particular matter, the density or line width of the developer pattern on the calibration plate and the density or line width of the developer pattern on the transfer material conveying belt are transferred by the single fixed sensor to the transfer material. It is detected at equal distances according to the conversion operation of the conveyor belt, and the process control control by the process control control mechanism can be performed more accurately.

Here, in the case where the transfer material transport belt is held in the transport belt holding unit which is converted together with the transfer material transport belt in the apparatus main body, and the sensor is attached to the above-mentioned transport belt holding unit, The sensor moves the transfer material transport belt to a calibration execution position (a position facing the calibration plate) when the transfer material transport belt is retracted to the single-color image forming position in accordance with the conversion operation of the transfer material transport belt. Is returned to the monochromatic image forming position, it moves to the detection execution position of the developer pattern on the transfer material conveying belt (the position facing the surface of the transfer material conveying belt). This eliminates the need for an actuator such as a solenoid that moves the sensor, which simplifies the process control control mechanism, reduces the number of parts, and enables efficient process control control with a simpler configuration. Becomes

Further, when the transfer material conveying belt is converted into the monochromatic image forming position in the conveying belt holding unit, the sensor mounting portion side is brought into contact with the transfer material conveying belt at the multicolor image forming position by contact with the apparatus main body. In the case where at least one center-folded portion is provided to be folded substantially parallel to each other,
The sensor will face the transfer material transport belt surface and the calibration plate under the same conditions regardless of whether the transfer material transport belt is converted to a single-color image forming position or a multicolor image forming position. It is possible to improve accuracy.

When a cleaning member for cleaning the surface of the sensor is arranged on the conversion locus of the monochromatic image forming position and the multicolor image forming position of the transfer material conveying belt, the transfer material conveying belt is monochromatic. The surface of the sensor is cleaned by the cleaning member every time the image forming position is changed to the multicolor image forming position, and erroneous detection due to adhesion of dust or the like to the sensor surface is prevented, thereby effectively improving the sensor reliability. It becomes possible.

Further, a conversion mechanism for converting the transfer material transport belt into a single color image forming position and a multicolor image forming position, a cam provided below the transport belt holding unit for holding the transfer material transport belt, and The width of the transfer area of the photoconductor at the upstreammost image forming station on the upstream side of the image forming station relative to the transfer material conveying belt is set at the upstream side of the image forming station during multicolor image formation and single color development. When the rotation fulcrum that rotates by the cam is provided so as to be substantially coincident with each other, even if the transfer material conveying belt (conveying belt holding unit) is converted to the single-color image forming position or the multi-color image forming position by the conversion mechanism. , The width of the transfer area of the photoconductor at the most upstream image forming station with respect to the transfer material conveying belt is almost the same during multi-color image formation and during single-color image formation Close to or in contact with so that, it becomes possible to maintain the transfer performance of the photoreceptor in the image forming station at the most upstream side in any of the multicolor image forming and during monochrome image formation. Moreover, since the conversion mechanism is composed of the cam and the rotation fulcrum, the conversion mechanism can have a very simple structure.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

In this embodiment, an electrophotographic digital color copying machine as an image forming apparatus equipped with the process control control mechanism according to the present invention will be described.

-Description of Overall Configuration of Digital Color Copying Machine 1- FIG. 1 is a vertical sectional front view showing the outline of the internal configuration of the digital color copying machine 1 according to the present embodiment from the front. This Figure 1
As described above, the digital color copying machine 1 includes the double-sided automatic document feeder 2, the image reading unit 3 for reading an image, and the image forming unit 4 for forming an image on the recording medium P as a transfer material. There is. Hereinafter, each part will be described.

<Description of Double-sided Automatic Document Feeding Unit 2> The double-sided automatic document feeding unit 2 is supported on the document table 21 made of transparent glass or the like so as to be openable and closable with respect to the document table 21.
1 is mounted in a predetermined positional relationship. The double-sided automatic document feeder 2 scans the original on one side (for example, the front side) of the document at a predetermined position on the document table 21.
After the image on one side is read, the original is temporarily retracted and inverted, and the other side (for example, the back side) of the original is placed at a predetermined position on the original table 21 at the image reading unit. The sheet is conveyed toward the document table 21 so as to face the sheet 3. When the double-sided automatic document feeder 2 finishes reading the images on both sides of one document, it discharges this document and then performs the two-sided conveyance operation for the next document. The above-described document feeding and reversing operations are controlled by a control unit (not shown) in relation to the overall operation of the digital color copying machine 1.

<Description of Image Reading Unit 3> The image reading unit 3 includes
A portion for reading image of a document placed on the document table 21 and images of a document fed one by one by the double-sided automatic document feeder 2 to create image data, and is an upper part of the digital color copying machine 1. That is, it is provided below the document table 21. The image reading unit 3 includes an exposure light source 31, first to third
The reflecting mirrors 32, 33, 34, the imaging lens 35, and the photoelectric conversion element 36 are provided. In this case, the exposure light source 31 and the first
The reflecting mirror 32 constitutes a first scanning unit 37, while the second and third reflecting mirrors 33, 34 constitute a second scanning unit 38.

The exposure light source 31 irradiates light onto an image surface of a document placed on the document table 21 of the double-sided automatic document feeder 2 or a document conveyed through the double-sided automatic document feeder 2. is there. Each of the reflecting mirrors 32, 33, and 34 temporarily deflects (reflects) the reflected light image from the original document in a predetermined direction (leftward in FIG. 1) and then downwardly deflects it, as shown by the broken line in FIG. After that, the light is deflected rightward in the drawing toward the imaging lens 35.

The first scanning unit 37 (exposure light source 31 and first reflecting mirror 32) reciprocates in parallel with the lower surface of the document table 21 at a predetermined scanning speed while maintaining a constant speed (see FIG. 1).
Then it moves left and right). Second scanning unit 38
The (second and third reflecting mirrors 33, 34) reciprocate (left and right in FIG. 1) in parallel to the lower surface of the document table 21 while maintaining a constant speed relationship with the first scanning unit 37. .

The imaging lens 35 is used in the second scanning unit 3
The reflected light image from the document deflected by the third reflecting mirror 34 of No. 8 is reduced, and the reduced light image is formed at a predetermined position on the photoelectric conversion element 36.

The photoelectric conversion element 36 sequentially photoelectrically converts the formed optical image and outputs it as an electric signal. The photoelectric conversion element 36 is a three-line color CCD capable of reading a black-and-white image or a color image and outputting line data that is color-separated into R (red), G (green), and B (blue) color components. . The document image information converted into an electric signal by the photoelectric conversion element 36 (CCD) is transferred to an image processing unit (not shown) and subjected to predetermined image data processing.

<Description of Image Forming Section 4>
An image forming system 41 and a transfer paper transport system 42 are provided.

The image forming system 41 is provided on the upper portion of the main body 10 of the digital color copying machine 1, and the paper feeding mechanism 4 is provided on the lower side thereof.
Equipped with 3. The paper feed mechanism 43 separates the recording media P stacked and stored in the paper feed cassette 12 as a storage unit attached to the lower end of the main body 10 one by one to separate the image forming system 4.
It is designed to supply one. This image forming system 41
The recording medium P supplied to is a cut sheet-shaped ordinary paper, and is a pair of upper and lower registration rollers 40 as rollers provided in front of the image forming system 41 (right side in FIG. 1).
40, the supply timing to the image forming system 41 is controlled by the controller. In addition, the recording medium P having an image formed on one surface is also used for the registration roller 4
0 and 40 supply (convey) again to the image forming system 41 at the same timing as the image forming in the image forming system 41.

Below the image forming system 41, there is provided a transfer / transport belt mechanism 44 as a transport belt holding unit. The transfer / conveying belt mechanism 44 is provided at a substantially central portion of the main body 10 of the digital color copying machine 1. The transfer / transport belt mechanism 44 includes a drive roller 4 rotatably supported on one side (left side in FIG. 1) of the main body case 44K.
4a, a driven roller 44b that is rotatably supported on the other side (the right side in FIG. 1), and a transfer material conveyance that is stretched between both rollers 44a and 44b and is driven in the arrow Z direction shown in FIG. An endless transfer / transport belt 44c as a belt is provided, and the recording medium P is electrostatically adsorbed on the surface of the transfer / transport belt 44c.
The recording medium P supplied from 0 is transported from the other side (upstream side) to one side (downstream side). A fixing device 45 is provided on the downstream side (left side in FIG. 1) of the transfer paper carrying belt mechanism 44 in the recording medium P conveyance direction, and the toner image transferred and formed on the recording medium P by the fixing device 45 is provided on the recording medium P. It is fixed in. The fixing device 45 is
A thermal heat roller 45a as a fixing member and a pressure roller 45b are provided above and below, and the recording medium P transported on the transfer paper transport belt mechanism 44 (transfer transport belt 44c) is heated by the thermal heat roller 45a and the pressure roller 45b. It is made to pass through the nip between and. A switching gate 46 is provided on one side of the fixing device 45. This switching gate 4
The reference numeral 6 designates a pair of upper and lower discharge rollers 11a, which discharge the recording medium P after fixing, which has passed through the nip between the thermal heat roller 45a and the pressure roller 45b, with respect to a discharge tray 11 mounted on one outer wall of the main body 10. The discharge path for discharging by 11a and the re-supply path for re-supplying the image forming system 41 through the lower part of the transfer / transport belt mechanism 44 are selectively switched. This re-supply path is provided with a switchback transport mechanism 47, and the front and back surfaces of the recording medium P transported to the re-supply path side by the switching gate 46 are turned upside down by the switchback transport mechanism 47 before the image forming system 4 is formed.
It is designed to be supplied again toward 1.

Above the transfer / transport belt mechanism 44, the first image forming station S1, the second image forming station S2, the third image forming station S3 and the fourth image forming station S4 are respectively transferred and transported. They are arranged in parallel in order from the upstream side (right side in FIG. 1) of the recording medium conveyance path in the vicinity of the belt 44c at predetermined intervals.
In this case, the recording medium P on the transfer / transport belt 44c is the first image forming station S1, the second image forming station S2, the third image forming station S3, and the fourth image forming station S2.
Will be sequentially conveyed to the image forming station S4.

Each of the image forming stations S1 to S4 has substantially the same structure and is provided with a photoconductor drum 5 as a photoconductor that rotates in the direction of arrow F shown in FIG. Around the periphery of each photoconductor drum 5, a charger 51 that charges each photoconductor drum 5 and forms an electrostatic latent image on the outer peripheral surface of each photoconductor drum 5, and on the outer peripheral surface of the photoconductor drum 5. A developing device 52 for developing the electrostatic latent image formed on the surface of the photosensitive drum 5 into a visible image with toner as powder, and a toner image (visible image) developed on the outer peripheral surface of the photoconductor drum 5 on the recording medium P. A transfer discharger 53 for transferring and a cleaning device 54 for removing the toner remaining on the outer peripheral surface of the photosensitive drum 5 are sequentially provided along the rotation direction of the photosensitive drum 5 (direction of arrow F).

A laser beam scanner unit 55 as a writing optical system is provided above each photosensitive drum 5.
(Hereinafter, referred to as LSU). Each LSU 55 includes a semiconductor laser element (not shown) that emits dot light modulated according to image data, and a polygon mirror 55a (deflecting device) for deflecting the laser beam from the semiconductor laser element in the main scanning direction. ), An fθ lens 55b and mirrors 55c and 55d for forming an image of the laser beam deflected by the polygon mirror 55a on the outer peripheral surface of the photosensitive drum 5.

LSU of the first image forming station S1
A pixel signal corresponding to the black component image of the color original image is input to 55, and the LS of the second image forming station S2 is input.
A pixel signal corresponding to the yellow color component image of the color original image is input to U55, and the third image forming station S
The pixel signal corresponding to the magenta color component image of the color original image is input to the third LSU 55, and the pixel signal corresponding to the cyan color component image of the color original image is input to the LSU 55 of the fourth image forming station S4. It is designed to be done. As a result, an electrostatic latent image corresponding to the color-converted original image information is formed on the outer peripheral surface of each photosensitive drum 5.

The developing device 52 of the first image forming station S1 stores black toner, the developing device 52 of the second image forming station S2 stores yellow toner, and the third image forming station S1. The developing device 52 of S3 contains magenta toner, and the developing device 52 of the fourth image forming station S4 contains cyan toner. The electrostatic latent image on the outer peripheral surface of each photoconductor drum 5 is developed into a visible image by the toner of each color, whereby the original image information color-converted in the image forming system 41 is a toner image by the toner of each color. It is supposed to be reproduced as.

A recording medium adsorption charger 56 is provided between the first image forming station S1 and the sheet feeding mechanism 43. The recording medium suction charger 56 charges the surface of the transfer / transport belt 44c, and the sheet feeding mechanism 4
The recording medium P supplied from the No. 3 transfer belt 44c
By surely adsorbing the recording medium P on the upper side, the recording medium P is conveyed between the first image forming station S1 and the fourth image forming station S4 without being displaced.

On the other hand, between the fourth image forming station S4 and the fixing device 45, a discharger 57 for static elimination is provided almost directly above the drive roller 41a. An AC current for separating the recording medium P electrostatically attracted to the transfer / transport belt 44c from the transfer / transport belt 44c is applied to the discharger 57.

When the recording medium P used in the present digital color copying machine 1 is sent out from the paper feeding cassette 12 and supplied into the guide of the recording medium conveying path of the paper feeding mechanism 43, the recording medium P is formed. The leading end of the sheet is detected by a sensor (not shown), and is temporarily stopped by the pair of registration rollers 40, 40 based on the detection signal output from this sensor. Then, the recording medium P is transferred onto the transfer / conveying belt 44c rotating in the direction of arrow Z in FIG. 1 at a timing with each of the image forming stations S1 to S4. At this time, since the transfer / conveying belt 44c has been charged by the recording medium suction charger 56 to a predetermined level, the recording medium P is recorded on each of the image forming stations S1 to S4.
Is stably fed while passing through.

In each of the image forming stations S1 to S4, a recording medium P on which a toner image of each color is formed and which is electrostatically adsorbed and conveyed by the transfer conveyance belt 44c.
The toner images of the image forming stations S1 to S4 are superposed on the supporting surface of (1) to transfer the images. And the fourth
When the transfer of the image by the image forming station S4 is completed, the recording medium P is sequentially peeled from the transfer conveying belt 44c by the negative discharger 57 from the leading end portion thereof, and is guided to the fixing device 45. The recording medium P on which the toner image is fixed by the fixing device 45 is the discharge roller 11a.
Is discharged onto the discharge tray 11 via a discharge port (not shown).

As a characterizing feature of the present invention, the digital color copying machine 1 transfers all the photosensitive drums 5, ... Of the first to fourth image forming stations S1 to S4 to the transfer / transport belt 44c as described above. Multicolor image formation in which an image is transferred by sequentially contacting the upper recording medium P, and the photosensitive drum 5 of only the first image forming station S1 is brought into contact with the recording medium P on the transfer conveyance belt 44c. Single-color image formation for transferring an image can be selectively performed. Specifically, when a start switch (not shown) of the digital color copying machine 1 is turned on, a monochrome image formation (monochrome image formation) is requested.
As shown by the solid line, only the photosensitive drum 5 of the first image forming station S1 on the most upstream side is used, and the remaining second to second
By retracting the transfer / conveyance belt 44c from each of the photosensitive drums 5 of the fourth image forming station, it is possible to perform single-color image formation only by the photosensitive drums 5 of the first image forming station S1. On the other hand, when multicolor image formation (full color image formation) is required when the start switch of the digital color copying machine 1 is turned on, as shown by the solid line in FIG. All the photoconductor drums 5 of the stations S1 to S4 are used, and the image forming stations S1 to S
By bringing the transfer / transport belt 44c into contact with each of the four photosensitive drums 5, the multi-color image formation can be performed by each of the photosensitive drums 5 of the first to fourth image forming stations S1 to S4.

The transfer / conveyance belt 44c is a monochromatic image forming position (a position shown by a solid line in FIG. 3) at the time of forming a monochromatic image by the conversion mechanism 7 provided in the main body case 44K of the transfer / conveying belt mechanism 44 holding the transfer / conveying belt 44c. In addition, at the time of forming a multicolor image, the single color image forming position is converted to the multicolor image forming position (position indicated by a solid line in FIG. 2). The conversion mechanism 7 is rotatably supported by the main body 10 of the digital color copying machine 1 and has a centering cam 71 that is in sliding contact with the lower surface of the other side (right side in the figure) of the main body case 44K.
And a rotation mechanism (not shown) such as an actuator for rotating the eccentric cam 71, and a transfer conveyance belt 44c freely rotatable on the other side (right side in the figure) of the main body case 44K of the transfer conveyance belt mechanism 44. Driven roller 44b supported on
As shown in (a) and (b) of FIG. 4, the rotation shaft (rotation fulcrum) 72 of the main body case 44K of the transfer / conveying belt mechanism 44 is provided on one side (on the left side in the figure) of the transfer case. When the transport belt 44c is converted to the single-color image forming position, one side end (sensor mounting portion side) of the main body case 44K is brought into contact with the frame 10a of the main body 10 to transfer the transfer belt at the multicolor image forming position. A middle bent portion 73 that is bent in the middle so as to be substantially parallel to 44c, and the middle bent portion 73
It is linked to one side and the other side of the body case 44K by sandwiching the
An urging spring 74 that urges one end of the one end flush with the other side. In this case, as shown in FIG. 4B, the biasing spring 74 causes the one side end of the main body case 44K to be bent in the middle against the biasing force by contact with the frame 10a of the main body 10. ing.

Further, the digital color copying machine 1 has
A process control control mechanism 8 is provided. The process control control mechanism 8 executes the calibration for detecting the density or line width of the reference toner pattern, and also detects the density or line width of the toner pattern formed on the transfer / transport belt 44c. Process control control is performed to correct the density or line width of the toner pattern detected on the transfer / transport belt 44c based on the density or line width of the toner pattern detected by executing the calibration. . Then, the calibration is performed by the conversion mechanism 7 by the conversion mechanism 7 so that the transfer / conveyance belt 44c is set to a single-color image forming position at the time of forming a single-color image using only the photoconductor drum 5 of the first image forming station S1. While being evacuated, the density or line width of the toner pattern on the transfer / transport belt 44c is detected to obtain a multicolor image using the photoconductor drums 5 of all the image forming stations S1 to S4. It is designed to be executed while returning to the multicolor image forming position (position indicated by the solid line in FIG. 2) during formation. Further, the process control control (including execution of calibration) is performed when the main body 10 of the digital color copying machine 1 is turned on, when a standby time has elapsed for a predetermined time, and when the number of recording media P on which an image is formed is predetermined. It is supposed to be done when the number of sheets is exceeded. In this case, the transfer / conveying belt 44c is set to the home position at the multicolor image forming position where the photosensitive drums 5 of all the image forming stations S1 to S4 are used.

The process control control mechanism 8 is
A calibration plate 81 which is provided on the frame 10a of the main body 10 so as to project at a calibration execution position, and on which the density or line width of a reference toner pattern is formed;
A pattern detection sensor 82 (sensor) that is attached to one end of the main body case 44K and detects the density or line width of the toner pattern on the calibration plate 81 and the transfer / transport belt 44c is provided. The pattern detection sensor 82 includes a light emitting unit and a light receiving unit (not shown), and the light receiving unit receives the reflected light of the light emitted from the light emitting unit toward the toner pattern on the calibration plate 81 and the transfer / transport belt 44c. Then, the density or line width of the toner pattern is detected. In this case, the distance L1 (shown in FIG. 3) between the pattern detection sensor 82 and the calibration plate 81, which is converted together with the main body case 44K to the monochromatic image forming position when performing the calibration, and the transfer conveyance belt A distance L2 (shown in FIG. 2) between the pattern detection sensor 82 converted together with the main body case 44K and the surface of the transfer / transport belt 44c at the multicolor image forming position when detecting the density or line width of the toner pattern in FIG. And are set to be equal to each other.

A cleaning brush 83 as a cleaning member for cleaning the surface of the pattern detection sensor 82 is provided on the upper end of the calibration plate 81. The cleaning brush 83 is located on a conversion locus (shown by a chain line in FIG. 3) between the single-color image forming position and the multi-color image forming position of the transfer / transport belt 44c converted by the converting mechanism 7, The surface of the pattern detection sensor 82 is rubbed and cleaned every time the transport belt 44c is converted into a single-color image forming position and a multi-color image forming position.

Next, the process control control by the process control control mechanism 8 will be described with reference to the flow charts of FIGS.

First, step S in the flowchart of FIG.
When the main body 10 of the digital color copying machine 1 is powered on at T1, the transfer / transport belt 44c is converted to the multicolor image forming position, that is, the home position (the position shown by the solid line in FIG. 2) at step ST2. Is determined. This determination is performed by a position sensor (not shown) that detects the rotational position of the centering cam 71.

If the transfer / transport belt 44c is not converted to the home position, the transfer center belt 71 is rotated in the reverse direction (counterclockwise in the figure) to rotate the transfer / transport belt in step ST3. 44c is returned from the single-color image forming position (the position shown by the solid line in FIG. 3) to the home position (multicolor image forming position).

On the other hand, if the transfer / conveyance belt 44c has been converted to the home position, the process control control is performed in step ST4.

The process control control will be described with reference to the flowchart of FIG.

First, step S in the flowchart of FIG.
At T40, the centering cam 71 is rotated in the forward direction (clockwise in the figure) to convert the transfer / transport belt 44c from the home position (multicolor image forming position) to the single color image forming position. At this time, in step ST41, the surface of the pattern detection sensor 82 is rubbed and cleaned by the cleaning brush 83 on the conversion locus of the transfer conveyance belt 44c that is converted from the home position to the single-color image forming position.

Then, in step ST42, the process waits until the transfer / conveyance belt 44c is converted into the single-color image forming position, and then in step ST43, calibration is executed. Specifically, the light receiving portion receives the reflected light of the light emitted from the light emitting portion of the pattern detection sensor 82 toward the toner pattern on the calibration plate 81, and the density or line width of the toner pattern on the calibration plate 81 is received. (A) is detected.

Then, in step ST44, the centering cam 71 is reversely rotated (counterclockwise in the figure) to convert the transfer / transport belt 44c from the single-color image forming position to the home position. At this time, step ST45
In step 3, the surface of the pattern detection sensor 82 is rubbed and cleaned by the cleaning brush 83 on the conversion locus of the transfer / transport belt 44c that is converted from the single-color image forming position to the home position.

Thereafter, in step ST46, the process waits until the transfer / transport belt 44c is converted to the home position, and in step ST47, the density or line width (B) of the toner pattern on the transfer / transport belt 44c is detected. To do. Specifically, the light receiving portion receives the reflected light of the light emitted from the light emitting portion of the pattern detection sensor 82 toward the toner pattern on the transfer / transport belt 44c, and the density of the toner pattern on the transfer / transport belt 44c or The line width (B) is detected.

Thereafter, in step ST48, the density or line width (A) of the toner pattern on the calibration plate 81 by calibration and the density or line width (B) of the toner pattern on the transfer / transport belt 44c are (A) ) .Apprxeq. (B) is determined. in this case,
The allowable range of the density or line width (A) of the toner pattern on the calibration plate 81 by calibration and the density or line width (B) of the toner pattern on the transfer / transport belt 44c is 2-3%. And

The determination in step ST48 is (A) ≈
In the case of NO that is outside the allowable value range that does not satisfy (B), the calibration plate 8 for calibration is used.
Process control for correcting the density or line width of the toner pattern detected on the transfer / conveyance belt 4c based on the density or line width of the toner pattern on No. 1, that is, the density of the toner pattern on the calibration plate 81 or A process for correcting the density or line width of the toner pattern detected on the transfer / transport belt 44c by changing the image forming conditions such as the main charge amount, toner density, transfer output, or exposure light amount based on the line width. Control control. On the other hand, step ST4
8 is within the allowable value range of (A) ≈ (B)
In the case of ES, the process control control for correcting the density or line width of the toner pattern detected on the transfer / transport belt 4c is not performed, and the process proceeds to step ST5 in the flowchart of FIG.

Then, in this step ST5,
After performing the warm-up processing (initialization processing) of the digital color copying machine 1, in step ST6, after waiting until the process control control and the warm-up processing are completed, the digital color copying machine 1 is shifted to the standby state.

Then, as shown in the flow charts of FIGS. 7 and 8, the process control control is performed even after the digital color copying machine 1 shifts to the standby state.

First, step S in the flowchart of FIG.
At T21, after the digital color copying machine 1 shifts to the standby state, it is determined whether the time during which image formation is not performed, that is, the leaving time has reached a set time (for example, 30 minutes),
If the leaving time has reached the set time, YES, in step ST22, the process control control is performed in the same manner as in step ST4, and then the process returns to the standby state.

Further, step S in the flowchart of FIG.
At T31, after the digital color copying machine 1 shifts to the standby state, it is determined whether or not the number of images formed on the recording medium P by the immediately previous image formation has reached a predetermined number (for example, 50 sheets), and Y when the number of image formation reaches the specified number
In the case of ES, in step ST32, process control control is performed in the same manner as in step ST4,
After that, returning to the standby state is repeated.

Therefore, in this embodiment, the process control control mechanism 8 is attached to the calibration plate 81 projecting from the frame 10a of the main body 10 at the calibration execution position and the one side end of the main body case 44K. And a pattern detection sensor 82
The pattern detection sensor 82 is a calibration execution position (a facing position facing the calibration plate 81) when the transfer carrying belt 44c is retracted to the single-color image forming position along with the conversion operation of the transfer carrying belt 44c.
In addition, when the transfer / transport belt 44c is returned to the single-color image forming position, the transfer / transport belt 44c moves to a toner pattern detection execution position on the transfer / transport belt 44c (a position facing the surface of the transfer / transport belt 44c). . For this reason,
An actuator such as a solenoid for moving the pattern detection sensor 82 is not required, the process control control mechanism 8 is very simple, the number of parts is reduced, and the process control control is efficiently executed with a simpler configuration. You will be able to

Further, the main body 10 of the digital color copying machine 1
When the power is turned on, the standby time is a predetermined time (for example, 30 minutes)
Since the process control control is executed when the time elapses and when the number of image-formed recording media P exceeds a predetermined number (for example, 50), the density or line width of the toner pattern detected by the execution of the calibration. Based on the above, the density or line width of the toner pattern on the transfer / transport belt 44c can be accurately corrected at a desired timing, and stable image formation can be always performed.

Moreover, the pattern detection sensor 82 and the calibration plate 81 when performing the calibration
And a distance L2 between the pattern detection sensor 82 and the surface of the transfer / transport belt 44c for detecting the density or line width of the toner pattern on the transfer / transport belt 44c are equal to each other. Therefore, the density or line width of the toner pattern on the calibration plate 41 and the density or line width of the toner pattern on the transfer / transport belt 44c are transferred and transferred by the fixed single pattern detection sensor 82. According to the conversion operation of the belt 44c, they are detected equidistantly, and the process control control by the process control control mechanism 8 can be performed more accurately.

Then, when the transfer / transport belt 44c is converted to the monochromatic image forming position, the frame 10 of the main body 10 is
The one end of the main body case 44K (on the side of the sensor mounting portion) is brought into contact with the transfer conveyance belt 44 at the multicolor image forming position.
Since the center folding part 73 for center folding is provided so as to be substantially parallel to c, the pattern detecting sensor 82 is configured such that the transfer / conveying belt 44c is converted to either the single color image forming position or the multicolor image forming position. However, the surface of the transfer / transport belt 44c and the calibration plate 81 are opposed to each other under the same condition, and the detection accuracy of the pattern detection sensor 82 can be improved. Further, since the cleaning brush 83 for cleaning the surface of the pattern detection sensor 82 is provided on the conversion locus of the monochromatic image forming position and the multicolor image forming position of the transfer / transport belt 44c, the transfer / transport belt 44c is monochromatic. The surface of the pattern detection sensor 82 is cleaned by the cleaning brush 83 every time the image forming position and the multicolor image forming position are converted, and erroneous detection due to adhesion of dust or the like to the surface of the pattern detecting sensor 82 is prevented to detect the pattern. The reliability of the sensor 82 can be effectively increased.

(Other Embodiments) The present invention is not limited to the above-described embodiments, but includes various other embodiments. For example, in the above embodiment, the rotation fulcrum of the transfer / transport belt 44c is located on the other side of the main body case 44K of the transfer / transport belt mechanism 44 and the transfer / transport belt 44c.
The rotary shaft 72 of the driven roller 44b that rotatably supports is provided on the other side of the main body case corresponding to the lower position of the vicinity of the first image forming station, and the photosensitive member at the first image forming station is provided. At the rotation fulcrum that rotates the main body case by the centering cam so that the contact width of the transfer area of the drum on the transfer / transport belt (width in the transport direction of the recording medium) is almost the same during multicolor image formation and during single color development. It may be.

Further, in the above embodiment, the main body case 44
A single end of the main body case 44K is folded at one end of the main body 10 by contact with the frame 10a of the main body 10 so as to be substantially parallel to the transfer conveyance belt 44c at the multicolor image forming position. Although the middle folding portion 73 is provided, there is a plurality of middle folding portions that cause one side end of the main body case to be center-folded so as to be substantially parallel to the transfer conveyance belt at the multicolor image forming position by contact with the frame of the main body. It may be provided at a location.

[0065]

As described above, according to the present invention, the following effects are exhibited. First, while the calibration is executed at the time of conversion of the transfer material conveying belt to the single color image forming position, the density or line width of the developer pattern on the transfer material conveying belt at the time of conversion of the transfer material conveying belt to the multicolor image forming position. By performing the detection of the transfer material, the process control control can be performed by using the conversion operation of the transfer material conveying belt, the process control control mechanism itself is very simple, the number of parts is reduced, and the process control control is simple. It can be executed efficiently with various configurations.

In particular, the process control control is executed when the apparatus main body is turned on, when the standby time has passed a predetermined time, and when the number of image-formed transfer materials exceeds a predetermined number, the transfer material is transferred. The density or line width of the developer pattern on the conveyor belt can be accurately corrected at a desired timing, and stable image formation can be always performed.

Further, by making the distances between the surface of the calibration plate and the surface of the transfer material conveying belt and the sensor equal to each other, the developer pattern on the calibration plate and the transfer material conveying belt by a single fixed sensor is provided. The density or line width can be detected at equal distances according to the conversion operation of the transfer material transport belt, and the process control control by the process control control mechanism can be performed more accurately.

By providing the transfer material transport belt and the sensor in the transport belt holding unit which performs the conversion operation together with the transfer material transport belt, the sensor is moved in accordance with the conversion operation of the transfer material transport belt, and the process control control mechanism is further improved. In addition to being simple, the number of parts is also reduced,
Process control control can be efficiently executed with a simpler configuration.

Further, at the time of conversion of the transfer material conveying belt to the single color image forming position, the sensor mounting portion side is bent at least one portion so as to be substantially parallel to the transfer material conveying belt at the multicolor image forming position. By arranging the portion on the transfer belt holding unit, the sensor can be made to face the transfer material transfer belt surface and the calibration plate under the same conditions at any conversion position of the transfer material transfer belt, and the detection accuracy of the sensor can be improved. .

In addition, by disposing the cleaning member on the conversion locus of the transfer material conveying belt, the surface of the sensor can be cleaned by the cleaning member every time the transfer material conveying belt is converted, and dust or the like adheres to the sensor surface. It is possible to prevent erroneous detection due to, and effectively improve the reliability of the sensor.

Further, the transfer material is provided by a cam below the transfer belt holding unit for holding the transfer material transfer belt and a rotation fulcrum of the transfer belt holding unit which is rotated by the cam as a fulcrum near the image forming station on the most upstream side. By configuring the conversion mechanism of the conveyor belt, the conversion mechanism can have a very simple structure. In addition, the conveyance belt holding unit is rotated by the cam so that the width of the transfer area of the photoconductor on the transfer material conveyance belt at the most upstream side image forming station is almost the same during multicolor image formation and during single color image formation. By rotating it around, it is possible to maintain the transfer performance of the photoconductor at the most upstream image forming station in both multicolor image formation and single color image formation.

[Brief description of drawings]

FIG. 1 is a sectional view of a color laser copying machine according to an embodiment of the present invention seen from the front.

FIG. 2 is a schematic diagram of a transfer / conveyance belt showing a state in which the belt is converted to a multicolor image forming position.

FIG. 3 is a schematic view of a transfer / conveyance belt showing a state of being converted into a single-color image forming position.

FIG. 4A is an explanatory diagram of a center-folded portion on one end side of the main body case at a multicolor image forming position of the transfer / transport belt.
FIG. 6B is an explanatory diagram of a center-folded portion on one end side of the main body case at the monochromatic image forming position of the transfer / transport belt.

FIG. 5 is a flowchart showing the overall flow of process control control by the process control control mechanism.

FIG. 6 is a flowchart showing a flow of process control control.

FIG. 7 is a flowchart showing a transition timing to process control control according to a leaving time.

FIG. 8 is a flowchart showing a transition timing to process control control according to the number of image formations.

FIG. 9 is a schematic view of the vicinity of one side of a transfer / conveyance belt showing a state in which a sensor is opposed to the surface of a transfer material conveyance belt according to a conventional example.

FIG. 10 is a schematic diagram of the vicinity of one side of the transfer / conveyance belt, showing a state where the sensor is opposed to the calibration plate.

[Explanation of symbols]

44K Main body case (conveying belt unit) 44c Transfer conveying belt (transfer material conveying belt) 5 Photosensitive drum (photosensitive member) 51 Charging device 52 Developing device 54 Cleaning device 55 Laser beam scanner unit (writing optical system) 7 Conversion mechanism 71 Centering cam (cam) 72 Rotation fulcrum 8 Process control control mechanism 81 Calibration plate 82 Pattern detection sensor (sensor) 83 Middle folding part S1 to S4 First to fourth image forming stations P Recording medium (transfer material)

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Fumio Shimazu             22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka             Inside the company (72) Inventor, Hiroshi Tachiki             22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka             Inside the company (72) Inventor Yoshikazu Harada             22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka             Inside the company (72) Inventor Mitsuyoshi Terada             22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka             Inside the company F term (reference) 2H027 DA38 DA46 DA50 EB04 EC03                       EC06 EC20 ED16 ED24 EE02                       EE07 EF06 FA28                 2H030 AB02 AD05 AD07 AD16 BB44                       BB53 BB56                 2H200 FA16 GA12 JB07 JB49 PA10                       PA12 PA20 PA22 PB18 PB32                       PB35

Claims (7)

[Claims] 1. A plurality of image forming stations each having a charging device, a writing optical system, a developing device, and a cleaning device around a photoconductor, and a transfer material conveying belt for conveying a transfer material on which an image is formed. When forming an image with a single color, of the image forming stations arranged from the upstream side to the downstream side in the transfer material conveyance direction, only the image forming station located on the most upstream side is used, and the other image forming stations remain. On the other hand, in the image forming apparatus in which the transfer material transport belt is retracted to perform the monochromatic image formation by the image forming station on the most upstream side, the calibration for detecting the density or the line width of the reference developer pattern is performed. While executing, the density or line width of the developer pattern formed on the transfer material transport belt is detected, and the above-mentioned key is detected. Process for performing process control control for correcting the density or line width of the developer pattern detected on the transfer material conveyance belt based on the density or line width of the developer pattern detected by executing the riblation A control control mechanism, wherein the transfer material transport belt retracts to a single-color image forming position when forming a single-color image using only the image forming station located on the most upstream side, while the multi-color image forming station uses all image forming stations. It is configured to be convertible so as to return to the multicolor image forming position during image formation, and the calibration is performed while the transfer material transport belt is retracted to the single color image forming position.
The detection of the density or line width of the developer pattern on the transfer material transport belt is performed when the transfer material transport belt is returned to the multicolor image forming position. Process control control mechanism of image forming apparatus. 2. The process control control mechanism of the image forming apparatus according to claim 1, wherein the process control control is performed when power is turned on to the apparatus main body, when a standby time has elapsed for a predetermined time, and when the image-formed transfer is performed. A process control control mechanism of an image forming apparatus, which is adapted to be performed when the number of materials exceeds a predetermined number. 3. The process control control mechanism of the image forming apparatus according to claim 1 or 2, wherein a density or a line width of a reference developer pattern provided at a calibration execution position is formed. A calibration plate and a sensor that detects the density or line width of the developer pattern on the calibration plate and on the transfer material transport belt are provided, and the distance between the sensor and the calibration plate when performing calibration And the distance between the sensor for detecting the density or line width of the developer pattern on the transfer material transport belt and the surface of the transfer material transport belt are equal to each other, the process control control of the image forming apparatus. mechanism. 4. The process control control mechanism of the image forming apparatus according to claim 3, wherein the transfer material transport belt is held by a transport belt holding unit that is converted together with the transfer material transport belt in the apparatus main body. The process control control mechanism of the image forming apparatus, wherein the sensor is attached to the conveyor belt holding unit. 5. The process control control mechanism of the image forming apparatus according to claim 4, wherein the conveyor belt holding unit contacts the apparatus body when the transfer material conveyor belt is converted to a single-color image forming position. The process control control mechanism of the image forming apparatus, characterized in that it has at least one center folding part for center folding the sensor mounting part side so as to be substantially parallel to the transfer material conveying belt at the multicolor image forming position. . 6. The process control control mechanism of the image forming apparatus according to claim 3, wherein a conversion locus between a monochromatic image forming position and a multicolor image forming position of the transfer material conveying belt. A process control control mechanism of the image forming apparatus, wherein a cleaning member for cleaning the surface of the sensor is arranged on the top. 7. The process control control mechanism of the image forming apparatus according to claim 1, wherein the transfer material conveying belt is converted into a single color image forming position and a multicolor image forming position. The conversion mechanism is provided in a cam provided below the transport belt holding unit that holds the transfer material transport belt, and in the transport belt holding unit near the image forming station on the most upstream side, and the most upstream image formation. An image characterized by having a rotation fulcrum rotated by the cam so that the width of the transfer area of the photoconductor at the station with respect to the transfer material conveying belt is substantially the same during multicolor image formation and during single color development. Process control control mechanism of forming equipment.