JP5228771B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus that forms an image on a recording material while performing image quality control.

  In an image forming apparatus, in particular, an electrophotographic image forming apparatus, the following image quality control is generally performed.

  A reference pattern called a patch image having one or a plurality of density levels is formed on the photosensitive member or the intermediate transfer member, and the density of the formed patch image is detected by a density detecting unit, and based on the detected density. And image forming means such as exposure means and developing means are controlled.

  Such image quality control is feedback control in which the density of the formed image is fed back to the image forming conditions, and an image having a constant image quality is always formed by correcting environmental changes and changes over time of the image forming apparatus. Is.

  As the patch image, a patch image having a plurality of levels of density is formed as in Patent Document 1. When a color image is formed, a plurality of levels of patch images are formed for each single color image constituting the color image, so that the number of patch images to be formed increases.

  It is not desirable to reduce the efficiency of output image formation for image quality control for forming patch images.

  Therefore, in Patent Document 1 and the like, a patch image is formed outside the area of the output image to avoid a decrease in image formation efficiency.

On the other hand, when the operation of the image forming apparatus is interrupted, the image quality control may be interrupted in the middle, and when the image forming apparatus restarts the operation, the image forming throughput decreases when the image quality control is restarted. It will be. For the purpose of avoiding this, in Patent Document 2, when the image quality control is interrupted due to the interruption of the operation of the apparatus, when the operation of the apparatus is resumed, not the image quality control is completely resumed but the incomplete image quality control is performed. Has been proposed.
JP 2000-318276 A JP 2007-316195 A

  When the image forming apparatus is interrupted, as in Japanese Patent Application Laid-Open No. 2004-26883, when image quality control that has not been completed is performed when the operation of the apparatus is resumed, the image quality control is divided into the front and the rear with the interruption of the apparatus operation. become.

  Therefore, there is a problem that the appropriate image forming conditions may be changed before and after the interruption due to an environment change or the like, and the reliability of image quality control is lowered.

  In addition, the technique described in the column “Problems to be Solved by the Invention” in Patent Document 2 also has a problem.

  That is, in the technique of “if the image quality control is incomplete due to the interruption of the operation of the apparatus, the image quality control is completely re-executed when the apparatus is restarted”, an extra reference pattern is formed and the toner consumption amount is increased. Increase in the number of photoconductors, early deterioration of the photosensitive member, and deterioration of the cleaning means.

  The present invention solves such a problem in the prior art, and provides an image forming apparatus that stably forms a high-quality image over a long period of time and does not reduce the productivity of image formation. With the goal.

  The object is achieved by the following invention.

1. An image carrier for carrying a toner image;
Image forming means for forming a toner image on the image carrier;
Reference pattern forming means for controlling the image forming means to form a reference pattern on the image carrier;
Density detecting means for detecting the concentration of the reference pattern on the image bearing member,
Image quality control means for controlling the image forming means based on the density detected by the density detection means ;
Toner remaining amount detecting means for detecting the remaining amount of toner,
Paper remaining amount detection means for detecting the remaining amount of paper,
In an image forming apparatus having
Forming the reference pattern, the density detecting means detects the density of the reference pattern, and the image quality control means has a control means for controlling the image quality at a predetermined interval based on the detected density,
Wherein, upon receipt of a paper no signal from the empty signal or remaining paper detection means from the toner remaining amount detecting means indicating that interrupting the step of forming an image on a sheet after a predetermined time, said Lee An image forming apparatus characterized by shortening the interval.

2 . It said control means from when the receiving one of the signals, the number of images that interruption of forming an image on a recording material is formed before being executed to predict, according to the prediction number, 2. The image forming apparatus according to 1 , wherein the image quality control interval is changed.

  In the present invention, when an interruption signal that causes the interruption of the apparatus is generated, the number of images from the interruption signal until the interruption is predicted is predicted, and the image quality control interval is changed based on the prediction.

  As a result, the image quality control is prevented from being divided in the middle due to the interruption of the operation of the apparatus, and the accuracy of the image quality control is prevented from being lowered. Further, formation of an extra reference pattern can be avoided.

  Hereinafter, the present invention will be described by way of embodiments of the present invention, but the present invention is not limited to the embodiments.

  FIG. 1 is a diagram showing an overall configuration of a color image forming apparatus as an example of an embodiment of the present invention.

  This color image forming apparatus is called a tandem type color image forming apparatus, and includes a plurality of image forming units 10Y, 10M, 10C, and 10K, an intermediate transfer body forming unit 7, and a sheet feeding conveyance for conveying a recording material P. Means 21 and fixing device 24 are provided. A document image reading device SC is disposed on the upper part of the main body A of the color image forming apparatus.

  As one of the different color toner images formed on each photoconductor, an image forming unit 10Y that forms a yellow image includes a drum-shaped photoconductor 1Y, a charging unit 2Y, an exposure unit 3Y, a developing unit 4Y, a primary unit. It has a transfer means 5Y and a cleaning device 6Y. The image forming unit 10M that forms a magenta image as another different color toner image includes a drum-shaped photoreceptor 1M, a charging unit 2M, an exposure unit 3M, a developing unit 4M, and a primary transfer unit 5M. And a cleaning device 6M. Further, an image forming unit 10C for forming a cyan image as another different color toner image includes a drum-shaped photoreceptor 1C, a charging unit 2C, an exposure unit 3C, a developing unit 4C, and a primary transfer unit. 5C and a cleaning device 6C. Further, as one of other different color toner images, the image forming unit 10K that forms a black image includes a drum-shaped photoreceptor 1K, a charging unit 2K, an exposure unit 3K, a developing unit 4K, a primary transfer unit 5K, It has a cleaning device 6K.

  The charging unit 2Y, the exposing unit 3Y, and the developing unit 4Y constitute an image forming unit that forms a toner image on the photoreceptor 1Y.

  Similarly, the charging unit 2M, the exposure unit 3M, the development unit 4M, the charging unit 2C, the exposure unit 3C, the development unit 4C, and the charging unit 2K, the exposure unit 3K, and the development unit 4K also constitute an image forming unit.

  The intermediate transfer body unit 7 has an intermediate transfer body 70. The intermediate transfer member 70 includes a semiconductive endless belt stretched around a plurality of rollers 71 to 74.

The color toner images formed by the image forming units 10Y, 10M, 10C, and 10K are sequentially transferred onto the rotating intermediate transfer body 70 by the primary transfer units 5Y, 5M, 5C, and 5K, and are combined. An image is formed. The recording material P accommodated in the paper feeding cassette 20 is fed by the paper feeding / conveying means 21 and is conveyed to the secondary transfer means 5A via a plurality of intermediate rollers 22A, 22B, 22C, 22D and registration rollers 23. Then, the color image is collectively transferred onto the recording material P. The recording material P onto which the color image has been transferred is fixed by the fixing device 24, is sandwiched between the paper discharge rollers 25, and is discharged onto a paper discharge tray 26 outside the apparatus.
On the other hand, after the color image is transferred to the recording material P by the secondary transfer means 5A, the intermediate transfer body 70 obtained by separating the curvature of the recording material P is cleaned by the cleaning device 6A.

  During the image forming process, the primary transfer unit 5K is always in pressure contact with the photoreceptor 1K. The other primary transfer units 5Y, 5M, and 5C are in pressure contact with the corresponding photoreceptors 1Y, 1M, and 1C, respectively, only during color image formation.

  The secondary transfer unit 5A is in pressure contact with the intermediate transfer member 70 only when the recording material P passes through the secondary transfer unit 5A.

  The image forming units 10Y, 10M, 10C, and 10K are arranged in tandem in the vertical direction. An intermediate transfer body unit 7 is arranged on the left side of the photoreceptors 1Y, 1M, 1C, and 1K in the figure. The intermediate transfer body unit 7 includes an endless belt-like intermediate transfer body 70 that can be rotated by winding rollers 71, 72, 73, 74, and 76, primary transfer means 5Y, 5M, 5C, and 5K, and a cleaning device 6A. Become.

  In this manner, toner images are formed on the photoreceptors 1Y, 1M, 1C, and 1K by charging, exposure, and development, and the toner images of the respective colors are superimposed on the endless belt-shaped intermediate transfer body 70, and the recording material P is collectively collected. Then, the image is fixed by the fixing device 24 by pressing and heating. The photoreceptors 1Y, 1M, 1C, and 1K after the toner image is transferred to the recording material P are cleaned by the cleaning device 6A after the toner remaining on the photoreceptor is transferred, and then the charging, exposure, and development cycle described above. The next image formation is performed.

  The present invention is also applicable to an image forming apparatus that does not use an intermediate transfer member.

  In an image forming apparatus that does not use an intermediate transfer member, a toner image formed on a photosensitive member by an image forming unit is transferred and fixed to a recording material as a transfer member by a transfer unit.

  The photoreceptor after the toner image is transferred to the recording material is cleaned by a cleaning unit.

  The image forming apparatus shown in the figure performs image quality control by setting image forming conditions at predetermined intervals in an image forming process.

  In the image quality control, as is well known, gradation control for controlling the exposure conditions of the exposure means 3Y, 3M, 3C, and 3K, development bias control for the development means 4Y, 4M, 4C, and 4K, and the rotation speed of the developer carrier. Control of development conditions such as control is performed.

  As is well known, image quality control is performed by forming a patch image as a reference pattern on the intermediate transfer body 70, detecting the density of the patch image by the density sensor 302, and based on the detected density, the exposure condition and the development. This is control for setting image forming conditions such as conditions.

  FIG. 2 shows the image quality control sequence.

  The patch images 1P and 2P are formed at intervals between the recorded images, such as between the recorded images 1G and 2G and between 2G and 3G. Further, a patch image may be formed outside the image area in the width direction X perpendicular to the moving direction Y of the intermediate transfer body 70.

  As described above, by forming the patch image outside the recorded image, image quality control is performed without reducing the productivity of image formation.

  As shown in FIG. 2, the image quality control is performed at a predetermined number of intervals, for example, 50 recorded images.

  In each interpal, a patch image is formed at an image interval of one to several recorded images.

  That is, a plurality of patch images are formed at each interval.

  In color image formation, a plurality of patch images are formed for each single color image.

  FIG. 3 is a block diagram of a control system of the color image forming apparatus.

  Image data obtained by image reading or image data transmitted from the outside is processed by the image processing unit 201 and transmitted to the printer unit 300.

  The printer engine 301 includes charging units 2Y, 2M, 2C, and 2K, exposure units 3Y, 3M, 3C3K, and developing units 4Y, 4M, 4C, and 4K in FIG. 1, and is based on image data transmitted from the printer control unit 200. Thus, an image is formed on the recording material.

  In image formation, the exposure control unit 202 and the development control unit 203 of the printer control unit 200 set optimum exposure conditions and development conditions, whereby a high-quality image is formed.

  In image quality control, image data for patch image formation is created in an image processing unit 201 serving as a reference pattern forming unit, and a patch image is formed.

  The system control unit 100 as an interval control means controls the image formation timing and image quality control interval of the recorded images 1G, 2G,... And the patch images 1P, 2P,.

  A printer control unit 204 provided in the printer control unit 200 as an image quality control unit controls the exposure control unit 202 and the development control unit 203 based on the detected density of the density sensor 302. The exposure control unit 202 sets exposure conditions for exposure means in the printer engine 301. The development control unit 203 sets development conditions for the developing means in the printer engine 301.

  In the image quality control, as shown in FIG. 2, patch images are formed at image intervals over a plurality of recorded images. At that time, when the final patch image in each image quality control is formed and the density sensor 302 detects the density, the printer control unit 204 sets an image forming condition based on the detected density.

  When the image forming conditions are set, a recorded image is formed under the set image forming conditions until density detection in the next image quality control.

  When the toner runs out (toner empty), the print job is interrupted by a signal from the remaining toner sensor 303, and when the paper runs out (out of paper), the print job is interrupted by a signal from the paper sensor 304. The prior art and the present invention will be described with reference to FIG. 4 as to how image quality control is performed when a print job is interrupted when the job is resumed.

  In FIG. 4, the print job is interrupted at time t2, and the print job is resumed at time t3. The image quality control interval is defined by a predetermined number of images such as t3-t4 and t4-t5. As shown in FIG. 2, image quality control for forming patch images at several leading image intervals (between the recorded images 1G, 2G,...) Is executed in this interval.

  Conventionally, as in Patent Document 1, when a print job is interrupted at time t2, the image quality control is also interrupted by the interruption, and as shown in ha, the image quality control processing ends when the image quality control ends. After the restart, the remaining image quality control hc is performed.

  In this control, since the image quality control is completed with ha + hc, the image forming conditions are set based on the image quality control with hb = ha + hc.

  In such image quality control, there may be a difference between the conditions and environment of the image forming apparatus before the interruption and the image forming conditions and environment at the time of resumption. There's a problem.

  The reference example is an example in which the complete image quality control hb is redone when the print job is interrupted before the image quality control is completed.

  In the reference example, there is no problem that the control accuracy is lowered as in the conventional example, but there is a problem that extra image quality control is performed.

  That is, in the reference example, extra image quality control indicated by ha is performed. As a result, problems such as increased toner consumption and faster fatigue of the photoreceptor occur.

  In the present invention, the interruption of the print job is predicted before the interruption is executed, and the image quality control timing is changed based on the prediction.

  The cause of the interruption of the print job occurs and is detected before the interruption execution time t2, as indicated by time t1.

  For example, an empty signal from the toner remaining amount sensor 303 is input to the system control unit 100 at time t1 before time t2. The same is true for a paper out signal from the paper sensor 304.

  The system control unit 100 as an interval control unit changes the image quality control interval based on signals from the remaining toner sensor 303 and the paper sensor 304.

  In the first embodiment, the image quality control interval is shortened, and the image quality control is executed and completed before execution of interruption.

  That is, the image quality control hb2 is executed by changing from the last hb1 of the actual control executed in the steady interval Porg before the interruption to the image quality control interval Pint shorter than the steady interval Porg. As a result, the image quality control hb2 is completed before the interruption and is completely executed.

  In the resumed job, a recorded image is formed under the image forming condition set by the image quality control hb2 until the image forming condition is set by the next image quality control hb3.

  In the second embodiment, image quality control is skipped by detecting interruption.

  That is, the system control unit 100 receives a signal that causes the print job to be interrupted, and interrupts the print job without performing image quality control after the last image quality control hb1 executed before the interrupt. In the following, a signal that causes an interruption is referred to as an interruption signal.

  The system control unit 100 executes image quality control hb2 after the regular interval Porg elapses after the print job is resumed.

  After the restart, the recorded image formed before the image forming condition is set by the image quality control hb2 is formed by the image forming condition set by the image quality control hb1 before the interruption.

  5 and 6 are flowcharts of image quality control performed in the first embodiment shown in FIG.

  Before describing FIGS. 5 and 6, the symbols used in FIGS. 5 to 7 will be described with reference to FIG.

  Porg is a regular interval for image quality control. For example, 50 sheets are set as the regular interval. The user can set the steady interval Porg to a desired value.

  Pint is an image quality control interval, and is uniquely set at each stage of control. When there is no interruption in image formation, Porg = Pint. However, as will be described later, when there is an interruption in image formation, the image quality control interval Pint may be different from the steady interval Porg.

  Pment is the number of images formed from the interruption signal until the apparatus is interrupted.

  Pnow is the number of images formed after the end of the last image quality control cycle.

  rev is the number of image intervals necessary for image quality control, and rev = 4 in the image quality control for forming 1P to 4P patch images shown in FIG.

  In step ST1, image formation is performed, and in step ST2, Pnow is incremented by one.

  In step ST3, it is determined whether or not Pnow has reached the set number, and when it reaches, the job is ended (Yes in ST3). If not reached (No in ST3), if there is an interruption signal (Yes in ST4), the process proceeds to the subroutine of FIG.

  When there is no interruption signal (No in ST4), Pnow = Pint? Is determined (ST5). If Pnow = Pint, a patch image is formed between the recorded images, and image quality control for setting image forming conditions is executed (ST6). In image quality control, image forming conditions are set when all of a plurality of patch images are formed and their densities are detected.

  If Pnow ≠ Pint, the process returns to the start (No in ST5).

  After the image quality control, the image quality control interval Pint is adjusted to the regular interval Porg and the process returns.

  FIG. 6 is a flowchart of a subroutine executed in the first embodiment when there is an interruption signal.

In step ST10, the number Pment of images formed from the interruption signal generation to the interruption execution time is calculated, and in step ST11,
Formula: Porg + rev ≦ Pment
It is determined whether or not

  If Porg + rev ≦ Pment is Yes, the process returns to the start of FIG.

  The meaning of this judgment is as follows.

  If there is a number of revs required for image quality control in the regular interval Porg from the interruption signal to the interruption execution, the image quality control can be performed at the regular interval after receiving the interruption signal, and further the image quality control at the next interval can be performed. . Therefore, the process returns to the start of FIG.

  In this case, after restarting, the image quality control is executed at the regular interval Porg.

If the determination in step ST11 is No, in step ST12,
Formula: Porg <Pment
It is determined whether or not

  The determination in step ST12 is for determining whether or not the image quality control is divided by the interruption when the image quality control is performed at the regular interval Porg after the interruption signal is received and then the image quality control is executed. is there.

  If the determination in step ST12 is Yes, the image quality control is divided.

  Therefore, in this case, in step ST14, the image quality control interval Pint is shortened by Porg-rev. As a result, as in the first embodiment shown in FIG. 4, the image quality control is performed before the interruption, and the division is avoided.

If the determination in step ST12 is No, in step ST13,
The expression: rev <Pment is determined.

  The determination in step ST13 is to determine whether or not image quality control executed after reception of the interruption signal is divided. If step ST13 is Yes, the image quality control is not divided, so image quality control is performed after the interruption is received until the interruption is executed. At that time, the image quality control interval is set to 0 (ST15).

  As a result, the image quality control is first executed after the restart.

  If the determination in step ST13 is No, that is, if the number of sheets until the interruption is executed after receiving the interruption signal is smaller than the image quality control number, the process returns to the start.

  In this case, after restarting, image quality control is executed after the regular interval Porg.

  FIG. 7 is a flowchart of a subroutine that is executed when there is an interruption signal in the second embodiment.

  7 is the same as FIG. 6 except that step ST14A is different from FIG.

  In step ST14A, the image quality control interval Pint is extended and set to Porg + rev.

  In step ST4 of FIG. 5, when there is an interruption signal, the image quality control interval Pint is extended to Por + rev in step ST14A of FIG. Therefore, image quality control is not performed between the interruption signal reception and the interruption execution. In the image forming process restarted after the interruption, the image quality control is executed after the image quality control interval Pint = Porg + rev has elapsed since the restart.

  That is, the image quality control is skipped once as in the second embodiment in FIG.

  Note that from the interruption signal reception (t1) in FIG. 4 to the start of image quality control after resumption (t4), image formation is performed according to the image forming conditions set in the image quality control immediately before the interruption signal reception.

1 is a diagram illustrating an overall configuration of a color image forming apparatus that is an example of an embodiment of the present invention. It is a figure which shows an image quality control sequence. 2 is a block diagram of a control system of the color image forming apparatus. FIG. It is a figure which shows control of an image quality control interval. 3 is a flowchart of image quality control performed in Embodiment 1 of the present invention. 3 is a flowchart of image quality control performed in Embodiment 1 of the present invention. It is a flowchart of the image quality control performed in Embodiment 2 of this invention. It is a figure for demonstrating the code | symbol used in FIGS.

Explanation of symbols

1Y, 1M, 1C, 1K photoconductor 2Y, 2M, 2C, 2K charging unit 3Y, 3M, 3C, 3K exposure unit 4Y, 4M, 4C, 4K developing unit 70 intermediate transfer unit 100 system control unit 200 printer control unit 300 printer Part 302 Density sensor Pint Image quality control interval Porg Steady interval

Claims (2)

An image carrier for carrying a toner image;
Image forming means for forming a toner image on the image carrier;
Reference pattern forming means for controlling the image forming means to form a reference pattern on the image carrier;
Density detecting means for detecting the concentration of the reference pattern on the image bearing member,
Image quality control means for controlling the image forming means based on the density detected by the density detection means ;
Toner remaining amount detecting means for detecting the remaining amount of toner,
Paper remaining amount detection means for detecting the remaining amount of paper,
In an image forming apparatus having
Forming the reference pattern, the density detecting means detects the density of the reference pattern, and the image quality control means has a control means for controlling the image quality at a predetermined interval based on the detected density,
Wherein, upon receipt of a paper no signal from the empty signal or remaining paper detection means from the toner remaining amount detecting means indicating that interrupting the step of forming an image on a sheet after a predetermined time, said Lee An image forming apparatus characterized by shortening the interval. The control means predicts the number of images to be formed from when one of the signals is received until the interruption of the process of forming an image on the recording material, and according to the predicted number, The image forming apparatus according to claim 1, wherein the image quality control interval is changed .

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