JP3369322B2 - Color image forming equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image of a full-color copying machine or the like in which an image formed on a photoconductor is transferred one by one onto an intermediate transfer belt in an overlapping manner to obtain a color image, and the color image is collectively transferred onto a recording paper. More specifically, the present invention relates to a color image forming apparatus that controls the cleaning process of the intermediate transfer belt from the start of printing to the start of transfer of the first color to shorten the printing time.

[0002]

2. Description of the Related Art Conventionally, as reference technical documents related to a color image forming apparatus using an intermediate transfer belt, for example, Japanese Patent Application Laid-Open Nos. 1-166069 and 1-293380.
Japanese Patent Laid-Open No. 1-273078 and Japanese Patent Laid-Open No. 2-1
It is disclosed in Japanese Patent No. 8591. These are executed after the toner image on the intermediate transfer belt is transferred to the recording paper as the timing for cleaning the intermediate transfer belt.

There is also known a technique of omitting the cleaning process at the start of copying by providing a cleaning process of at least one round of the intermediate transfer belt at the end of copying in order to improve the copy processing speed.

[0004]

However, in the conventional color image forming apparatus as shown above,
If a new cleaning process time is provided, the copy processing speed will be delayed accordingly. Further, if a cleaning process is provided after the copying is completed, the transfer surface may be contaminated due to toner scattering during standby. As described above, conventionally, there have been problems in that the copying speed is slow and the image quality is poor.

If the intermediate transfer of the first color is performed while cleaning, a color position shift occurs due to a change in the load torque applied to the transfer motor of the first color during the intermediate transfer process after the transfer of the second color. there's a possibility that. Furthermore, if the cleaning blade is separated and cleaning is not performed but the belt transfer of the first color is executed while the belt is still rotating, the motor operation after the transfer of the second color is different, and thus the color position may shift. is there. As described above, there is a problem in that a color position shift is caused at the time of intermediate transfer due to a change in load torque of the drive motor and a difference in rotation operation.

The present invention has been made in view of the above, and is a color image forming apparatus using an intermediate transfer belt for sequentially transferring a toner image formed on a photoconductor for each color,
The objective is to improve the copy processing speed, eliminate image misalignment, and obtain good image quality.

[0007]

In order to achieve the above-mentioned object, in the present invention , an intermediate transfer means for sequentially superposing and transferring the toner images formed on the photoconductor for each color, And a cleaning unit capable of contact and separation operation for removing the residual toner of the intermediate transfer unit after the transfer onto the recording paper.
In the color image forming apparatus, the photosensitive member
Wherein by separating the intermediate transfer means, the cleaning means, and executes a control to abut at least a maximum copy size of the intermediate transfer means, the first color in said
The intermediate transfer means before the start of the transfer process to the intermediary transfer means.
Of the intermediate transfer means after the cleaning step of
It is provided with a control means for temporarily stopping the driving and waiting .

[0008]

[0009]

[Action] color image forming equipment of the present invention, the control means, until the first color transcription initiation of the print start or al during the transfer means, to separate the photoreceptor and the intermediate transfer means, the intermediate transfer By performing control of the cleaning unit for cleaning the unit so that at least the maximum copy size is brought into contact with the intermediate transfer unit, the cleaning process can be performed without providing a new cleaning step time.
In addition, before the start of the transfer process to the intermediate transfer means for the first color,
The cleaning process of the interim transfer means is completed, and the intermediate transfer means
By temporarily stopping the drive of the
It is necessary to make the transfer drive state of the copying means the same for each color.
it can.

[0010]

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an explanatory diagram showing the configuration of a digital full-color copying machine suitable for applying the present invention. Further, FIG. 2 is an explanatory diagram showing a detailed configuration of an image forming unit and an intermediate transfer belt portion. This digital full-color copying machine is roughly composed of a color image reading device 100 (hereinafter referred to as a color scanner) and a color image recording device 110 (hereinafter referred to as a color printer). A paper feeding device 170 for adding is installed.

The color scanner 100 includes an illumination lamp 101 for illuminating the original P, a first mirror 102, a second mirror 103, and a third mirror 104 for guiding the reflected light of the original P.
And an image forming lens 105 and a color sensor 106 for converting the light imaged by the image forming lens 105 into an image signal. Further, the color sensor 106 is configured by a photoelectric conversion element such as a CCD (charge coupled device) as a color separation unit for blue (B), green (G), and red (R), and has a configuration capable of simultaneously reading three colors. To do.

The color printer 110 is roughly composed of an optical writing unit 111, an image forming unit 112, and a paper feeding unit 113.
And a fixing / paper discharging unit 114 and the like. The optical writing unit 111 includes a laser 115 that uses a semiconductor laser.
, Its laser drive control plate 311 (see FIG. 3), the polygon mirror 116, its polygon motor 117, f
This is a box-shaped unit composed of a / θ lens 118, a reflection mirror 119, and the like.

The image forming unit 112 is provided with the following functions centering on the photosensitive drum 120 which forms an electrostatic latent image. 121 is a charger for uniformly charging the photosensitive drum 120, 122 is a potential sensor for detecting the surface potential of the photosensitive drum 120, 123 is a Bk developing device for black toner, and 124 is C for cyan toner. Developing unit, 1
Reference numeral 25 is an M developing device for magenta toner, 126 is a Y developing device for yellow toner, 127 is a photoconductor cleaning unit for removing and collecting residual toner on the photoconductor drum 120, and a pre-cleaning static eliminator is provided. There is. Further, 128 is a discharge lamp for erasing the residual potential of the photoconductor drum 120, and 129 is a developing density pattern detector.

Reference numeral 130 is an intermediate transfer belt unit, which includes a driving roller 131 and a belt transfer bias roller 1.
32, and a driven roller 133.
The belt drive motor 134 can be driven. The intermediate transfer belt unit 130 is provided with a belt cleaning unit 135. The belt cleaning unit 135 includes the brush roller 136, the rubber blade 137, and the intermediate transfer belt unit 13.
It is composed of a contact / separation mechanism 138 and the like from 0.

Further, as shown in FIG. 2, each of the developing devices 123 to 126 is rotated by bringing a brush of developer for developing an electrostatic latent image on the photosensitive drum 120 into contact with the surface of the photosensitive drum 120. Bk developing sleeve 139, C developing sleeve 140, M developing sleeve 141, Y developing sleeve 142
And developing paddles 143 to 146 for stirring and stirring the developer, and toner concentration detection sensors 147 to 150 of the developer.

The paper feed unit 113 is equipped with a paper feed cassette 151, a paper feed cassette 152, and a manual paper feed tray 153 for feeding special paper such as OHP film one by one. Further, 154 is a paper feed cassette 151
The paper feeding roller 155 for feeding the recording paper, and 155 is a registration roller for feeding the recording paper in synchronism with the image on the intermediate transfer belt unit 130. Also, 15
6 is a paper transfer unit, and this paper transfer unit 156
Is composed of a paper transfer bias roller 157, a roller cleaning blade 158, a belt contact / separation mechanism 159, and the like. Further, 160 is a conveyor belt for conveying the recording paper after the transfer.

The fixing / paper discharging unit 114 includes a fixing unit 163 including a fixing roller 161 having a fixing heater built therein and a pressure roller 162 facing the fixing roller 161 and biased with a predetermined pressure. The sheet discharge roller 164, the sheet discharge tray 165 and the like are included. In addition, the paper feeding device 170
Includes paper feed cassettes 171 and 172.

Next, the operation of the above configuration will be described. The color scanner 100 receives a scanner start signal in timing with the operation of the color printer 110, scans the document in the direction of the left arrow, and obtains image data of one color for each scan. The image of the original P is illuminated by the illumination lamp 101, and the reflected light is emitted from the first mirror 102 and the second mirror 10.
An image is formed on the color sensor 106 by the imaging lens 105 via the third mirror 104. This operation is repeated a total of four times to obtain sequential four-color image data. Then, the color image information of the document P is read for each color separation of blue, green, and red, for example, and converted into an electrical image signal. Next, color conversion processing is performed by the image processing unit (see FIG. 3), and black (hereinafter referred to as Bk), C
yan (hereinafter referred to as C), Magenta (hereinafter referred to as M)
,), And yellow (hereinafter referred to as Y) color image data.

This color image data is Bk, C, M, Y by the color printer 110 for each color.
Is visualized as a final color copy. The details will be described below. The optical writing unit 111 converts the color image data from the color scanner 100 into an optical signal and performs optical writing corresponding to the original image, and the photoconductor drum 12
An electrostatic latent image is formed on 0.

Now, in the standby state, the four developing devices 123
Although all of Nos. To 126 are in the state of cutting off the developing sleeves 139 to 142 (development inoperative), the order of the developing operation (color image forming order) is as follows in the example of Bk, C, M and Y. explain. The developing order is not limited to this.

When the copying operation is started, the intermediate transfer belt unit 130 starts to rotate by the belt drive motor 134, and when the belt speed reaches a constant value, the rubber blade 137 is brought into contact with the belt to start cleaning.
Then, after cleaning a certain area, the rubber blade 137 is separated from the belt, and the belt drive motor 13
Stop 4 The color scanner 100 starts reading Bk image data at a predetermined timing, and optical writing by a laser beam and latent image formation are started based on the image data. Hereinafter, the electrostatic latent image based on this Bk image data is referred to as a Bk latent image. Note that C, M, and Y are treated in the same manner. For example, the above operation is performed by referring to FIG.
And the timing chart in Fig. 5,
From the lint start signal to the start of Bk transfer
(In FIG. 4, during time T), the belt cleaning
For the contact and separation (to the belt surface), the intermediate transfer belt drive speed is
At the time when it reaches the fixed value (when the velocity diagram shifts horizontally),
Cleaning by contacting the rubber blade 137 with the belt
Start, and after cleaning a certain area,
The cleaning is completed by separating the cord 137 from the belt.
After that, the belt drive motor 134 is stopped. Sanawa
Then, before the intermediate transfer belt drive speed becomes 0, the rubber shake
The cleaning is completed by separating the card 137 from the belt.
I am letting you. Timing of this belt cleaning contact and separation
Is just an example, as will be described later.
Contact / separation timing according to the belt length required for cleaning
The difference between the
Belt cleaning from start to Bk transfer start
Illustration of the contact and separation timing of the
Does not mean continued).

Before the development position of the Bk developing device 123 is reached, the Bk latent image is developed from the front end portion of the Bk latent image so that development is possible.
The developing sleeve 139 is rotated to make the developer stand, and the Bk latent image is developed with Bk toner. And after that,
The developing operation of the Bk latent image area is continued, but the rear end of the latent image is Bk
When the toner has passed through the developing position, the developer of the Bk developing sleeve 139 is quickly cut off to put it in a non-developing state.
This is completed at least before the leading edge of the C latent image by the next C image data arrives. It should be noted that this cutting is performed by switching the rotation direction of the Bk developing sleeve 139 to the opposite direction to that during the developing operation.

The Bk toner image formed on the photosensitive drum 120 is transferred onto the surface of the intermediate transfer belt unit 130 which is driven at the same speed as the photosensitive drum 120. Hereinafter, this is performed by applying a predetermined bias voltage to the transfer bias roller 132 while the intermediate transfer belt unit 130 is in contact with the photosensitive drum 120. In the intermediate transfer belt unit 130, the Bk, C, M, and Y toner images sequentially formed on the photoconductor drum 120 are sequentially aligned on the same surface to form a belt transfer image of four-color superimposition, and thereafter. , Perform batch transfer to recording paper. The operation of the intermediate transfer belt unit 130 will be described later.

By the way, on the photosensitive drum 120 side, B
After the k step, the C step is started, but the C image data reading by the color scanner 100 is started at a predetermined timing, and the C latent image formation is executed by the laser light writing by the image data. The C developing device 124 starts the rotation of the C developing sleeve 140 after the trailing end of the Bk latent image to the developing position has passed and before the leading end of the C latent image reaches the developing position. The ears are raised and the C latent image is developed with C toner. After that, the development of the C latent image area is continued, and when the trailing edge of the latent image passes, the brush cutting on the C developing sleeve 140 is performed like the Bk developing device 123. This is also completed before the leading edge of the next M latent image arrives. Also, M and Y
With regard to the step (1), the operations of reading, latent image formation, and development of the respective image data are performed in the same manner as the steps of BK and C, and therefore the description of this operation is omitted.

The intermediate transfer belt unit 130 is rotationally driven by a belt drive motor 134. Further, the bias roller 157 of the paper transfer unit 156 is usually separated from the surface of the intermediate transfer belt unit 130, but the four-color superposed images transferred and formed on the surface of the intermediate transfer belt unit 130 are collectively transferred onto the recording paper. At this time, the contact / separation mechanism 159 presses at a timing, and a predetermined bias voltage is applied to the bias roller 157 to perform the transfer process on the recording paper. Further, this recording paper is, for example, a paper feed cassette 151.
From the paper feed roller 154, and the registration roller 155 feeds the front end portion of the four-color superimposed image on the surface of the intermediate transfer belt unit 130 at the timing of reaching the paper transfer position.

Next, the operation of the intermediate transfer belt unit 130 will be described in detail. Intermediate transfer belt unit 130
There are the following three operation methods after the belt transfer of the Bk toner image of the first color is completed up to the rear end. One of them, or speedup of the copy process depending on the copy size, etc. In order to achieve this, selection / operation is performed by an efficient combination. Hereinafter, each method will be described.

(1) Constant-speed forward movement method Even after the Bk toner image is transferred on the belt, the forward movement is continued at a constant speed. When the front end position of the Bk image on the surface of the intermediate transfer belt unit 130 reaches the belt transfer position of the contact portion with the photosensitive drum 120 again, the photosensitive drum 12
On the 0 side, an image is formed with a timing so that the front end portion of the next C toner image exactly coincides with the position. As a result, the C image is accurately aligned with the Bk image and is transferred onto the intermediate transfer belt unit 130 in a superposed manner. Thereafter, the same operation is performed to proceed to the M and Y image process, and a belt transfer image of four colors is obtained. Subsequent to the Y toner image belt transfer process for the fourth color, the four color superimposed toner images on the belt surface are collectively transferred onto the recording paper while moving forward.

(2) Skip Forwarding Method After the belt transfer of the Bk toner image is completed, the intermediate transfer belt unit 130 is separated from the surface of the photosensitive drum 120, and the intermediate transfer belt unit 130 is skipped at a high speed in the forward direction, and a predetermined amount is moved. Then return to the original forward speed. After that, the intermediate transfer belt unit 130 is again attached to the photosensitive drum 120.
To contact. The intermediate transfer belt unit 130
When the front end position of the Bk image on the surface reaches the belt transfer position again, the image is formed on the photosensitive drum 120 side at a timing so that the front end part of the next C toner image exactly coincides with the position. As a result, the C image is accurately aligned with the Bk image, and the four colors are overlapped and transferred on the belt. Thereafter, the same operation is performed to proceed to the M and Y image process, and a belt transfer image of four colors is obtained. Subsequent to the Y toner image belt transfer process for the fourth color, the four color superimposed toner images on the belt surface are collectively transferred onto the recording paper while moving forward.

(3) Reciprocating (quick return) system When the belt transfer of the Bk toner image is completed, the intermediate transfer belt unit 130 is separated from the surface of the photosensitive drum 120. Then, the forward movement is stopped and at the same time, a high speed return is made in the opposite direction. Return is the intermediate transfer belt unit 1
The front end position of the Bk image on the 30th surface passes the position corresponding to the belt transfer in the opposite direction, and after moving a preset distance, it is stopped and put in a standby state. Next, when the front end portion of the C toner image on the photosensitive drum 120 side reaches a predetermined position before the belt transfer position, the intermediate transfer belt unit 130 is restarted in the forward direction. Further, the intermediate transfer belt unit 130 is brought into contact with the surface of the photosensitive drum 120 again. Also in this case, the C image is transferred under the condition that the C image is accurately overlapped with the Bk image on the surface of the intermediate transfer belt unit 130. Thereafter, the same operation is performed to proceed to the M and Y image process, and a belt transfer image of four colors is obtained. Subsequent to the transfer process of the Y-color toner image belt for the fourth color, the four-color overlaid toner image on the surface of the intermediate transfer belt unit 130 is collectively transferred onto the recording paper by moving forward at the same speed without returning.

[0031] Now, a recording paper which is collectively transferred toner image superimposed four colors from the intermediate transfer belt unit 130 side by the above method is carried into the fixing unit 1 63 by the conveyor belt 160. In fixing unit 1 63, the toner image on the recording paper is fused and fixed by the pressure roller 162 which is biased by the predetermined pressure and the fixing roller 161 is controlled to a predetermined temperature.
After that, the recording paper is ejected to the paper ejection tray 165 by the paper ejection roller 164, whereby a final full-color copy is obtained.

On the other hand, the photosensitive drum 120 after the belt transfer
The surface is cleaned by the photoconductor cleaning unit 127, and the residual charge is erased by the static elimination lamp 128 to prepare for the next copying process. In addition, the intermediate transfer belt unit 130 after the toner image is transferred onto the recording paper, the belt cleaning unit 135 is pressed again by the contact / separation mechanism 138, and the surface thereof is cleaned.

At the time of repeat copying, the color scanner 10
0 operation and image formation on the photosensitive drum 120 are 1
Subsequent to the Y (fourth color) image process of the first sheet, the process proceeds to the Bk (first color) image process of the second sheet at a predetermined timing. Also,
In the intermediate transfer belt unit 130, the second Bk toner image is belt-transferred to the area where the surface is cleaned by the belt cleaning unit 135, following the batch transfer process of the first four-color superimposed image onto the recording paper. To do so. After that, the same operation as the first sheet is executed.

In the above description, the copy mode for obtaining four full colors has been described as an example.
In the two-color copy mode, the same operation as described above is performed for the designated color and the number of times. In the case of the single-color copy mode, only the developing device for the target color is set to the developing operation (developer spike) state until the predetermined number of sheets is completed. Further, the intermediate transfer belt unit 130 is driven at a constant speed in the forward direction while being in contact with the surface of the photosensitive drum 120. Then, the belt cleaning unit 135
Also performs the single-color copy operation while keeping contact with the intermediate transfer belt unit 130.

FIG. 3 is a block diagram showing the configuration of the control system of the color image forming apparatus shown in FIG. In the figure, reference numeral 301 is a system control board equipped with a microcomputer system for controlling the entire apparatus. The system control board 301 is connected with the following functional units, load parts, sensors and the like. Reference numeral 302 denotes an operation unit that displays input setting keys and the state of the apparatus, 303 denotes an editor for performing input operations such as image editing, 304 denotes various peripheral devices such as an automatic document feeder (ADF) and a sorter, and 3
Reference numeral 05 denotes a document size detector for detecting the size of the document set on the document reading portion of the scanner 100, and 306.
Is a recording paper size detector for detecting the recording paper size of the paper feed cassettes 151, 152, 171, 172, and 307 is various detectors such as a conveyance sensor for detecting the conveyance timing of the recording paper and a density sensor for detecting the image density. Is.

Further, 308 is a scanner control plate for controlling the scanner motor 309 and the color sensor 106, 310 is an image processing unit, 311 is a laser drive control plate for controlling the laser 115, 312 is a polygon synchronization detector, 313.
Is an intermediate transfer belt drive motor control plate for controlling the belt drive motor 134, and 314 is an AC load 31 such as a fixing heater.
5, an AC load control plate for controlling 5, a belt contact / separation solenoid 316, a paper transfer roller contact / separation solenoid 317,
318 is a belt cleaner contact / separation solenoid, 319 is Bk
Developing sleeve motor, 320 is a C developing sleeve motor,
321 is an M developing sleeve motor, 322 is a Y developing sleeve motor, 323 is various process loads, and 324 is various driving loads.

Next, the cleaning control of the intermediate transfer belt unit 130 according to the present invention will be described with reference to the timing charts shown in FIGS. The present invention executes the cleaning process without providing time for the intermediate transfer belt cleaning process. The time from the start of printing to the start of belt transfer for the first color is the time for writing an image on the photosensitive drum 120 and developing. It suffices if the maximum copy size + distance to the belt cleaning unit 135 and the belt transfer area + preliminary can be cleaned during this indispensable time T.

The time T is the time from when the print switch is turned on (print start signal is turned on) to when the intermediate transfer belt unit 130 starts driving for Bk transfer. Moreover, the time T is determined by the time to perform data communication processing between the data processing and system control board 301 and the unit control of each unit controlled by the system control board 301 for copying the start of the color printer 110. In this embodiment, T = 2.8 sec.

Further, the belt length which needs to be cleaned within the time T is the maximum original size (A3 length) 420 mm + the distance between the rubber blade 137 and the belt transfer area 120 mm.
+ The margin is 40 mm, which means that it is sufficient if this length can be cleaned. That is, in this case, assuming that the linear velocity of the intermediate transfer belt unit 130 is 180 mm / sec, T = 580 (mm) / 180 (m / sec) ≈
It will be 3.2 seconds.

Therefore, the length of T time is 3.2 sec.
In the above case, the cleaning process can be executed without adding time for the cleaning process, and the final copy process time can be shortened. If the T time is 3.2 sec or less, the linear velocity of the intermediate transfer belt unit 130 during the cleaning process is 180 mm / s.
ec is set to 360 mm / sec for 1.6 s
The cleaning process can be ended with ec, and it is not necessary to add new time for the cleaning process.

After the cleaning, the rubber blade 137 is separated from the intermediate transfer belt unit 130 and the belt is driven as it is (linear speed 180 mm / sec) or 360 mm / sec → 180 mm / sec to perform the Bk belt transfer process. If you control to execute
Since the belt driving state is different from that at the start of C, M, and Y transfer, there is a possibility that misalignment may occur. Therefore, in the present invention, as indicated by the driving speed of the intermediate transfer belt unit 130 in the timing chart of FIG. 4, the intermediate transfer belt unit 130 is once stopped and then controlled to start driving by the transfer reference signal.

Although the maximum original size of the cleaning area has been set to A3, if the original size can be detected by the original size detector 305, the cleaning processing time is reduced by setting the recording paper size area as the cleaning target length. It is further shortened.

[0043]

As described above, according to the present invention, a color image forming equipment of the present invention, the control means, between the print start up first color transcription initiation to the intermediate transfer section, the photosensitive member
The intermediate transfer means is separated from the intermediate transfer means, and the cleaning means for cleaning the intermediate transfer means is controlled to bring at least the maximum copy size into contact with the intermediate transfer means. The transfer means can be cleaned, the copy processing speed can be improved, image stains can be eliminated, and good image quality can be obtained .
Cleaning process of the intermediate transfer means before the transfer process starts
Is completed, the drive of the intermediate transfer unit is temporarily stopped, and
Since the transfer driving state of each color is the same, the image position
The occurrence of deviation can be eliminated .

[0044]

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of a digital full-color copying machine suitable for applying the present invention.

FIG. 2 is an explanatory diagram showing a detailed configuration of an image forming unit and an intermediate transfer belt portion in FIG.

3 is a block diagram showing a configuration of a control system of the color image forming apparatus shown in FIG.

FIG. 4 is a timing chart of the color image forming apparatus according to the present invention.

FIG. 5 is a timing chart of the color image forming apparatus according to the present invention.

FIG. 6 is a timing chart of the color image forming apparatus according to the present invention.

[Explanation of symbols]

110 Color Printer 120 Photosensitive Drum 130 Intermediate Transfer Belt Unit 135 Belt Cleaning Unit 138 Contact / Separation Mechanism 301 System Control Plate

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Claims (2)

(57) [Claims] 1. An intermediate transfer device for sequentially superposing and transferring toner images formed on a photoconductor for each color, and a contact / separation operation for removing residual toner of the intermediate transfer device after transfer to a recording paper. In the image forming apparatus having various cleaning means, the photosensitive member and the intermediate transfer means are connected between the start of printing and the start of transfer of the first color to the intermediate transfer means.
And the cleaning unit is controlled so that at least the maximum copy size is brought into contact with the intermediate transfer unit, and the first color is transferred to the intermediate transfer unit.
Cleaning process of the intermediate transfer means before the start of the process
Then, the drive of the intermediate transfer means is temporarily stopped.
A color image forming apparatus, comprising: a control unit for holding the device in a standby state . 2. The control means ends the cleaning step of the intermediate transfer means before starting the transfer step of the first color to the intermediate transfer means, and temporarily stops the drive of the intermediate transfer means and waits. The color image forming apparatus according to claim 1, wherein