JP2009258376A - Image forming apparatus and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a toner band in appropriate timing. <P>SOLUTION: An image forming apparatus 1 includes an image forming engine 7 generating an electrostatic latent image by irradiating a photoreceptor drum 20 with light while driving and rotating the photoreceptor drum 20, forming an image by developing the electrostatic latent image with developer, transferring the formed image to a recording medium, and then removing the developer remaining on the surface of the photoreceptor drum 20 by a pressing member 241 pressed on the surface thereof. A calculation means 201 calculates a value in accordance with an amount of the developer used for development. A drive amount accumulation means 203 accumulates a rotational drive amount of the photoreceptor drum 20 when the value calculated by the calculation means 201 is lower than a first threshold. An accumulated value changing means 204 decreases the accumulated value by the drive amount accumulation means 203 or changes it to 0 in accordance with the value calculated by the calculation means 201. An instruction means 205 forms a prescribed image on the photoreceptor drum 20 when the accumulated value attains a second threshold. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus and a program.

  An electrophotographic image forming apparatus is provided with a cleaner blade which is a member for removing toner remaining on the photosensitive drum after transfer of the toner image. The cleaner blade removes toner by pressing the tip of the cleaner blade against the surface of the photosensitive drum and rubbing it.

  If the photosensitive drum continues to be rotated for a long time in a state where no toner image is formed or a low-density toner image is formed, excessive friction is generated between the photosensitive drum and the photosensitive drum. This may cause wear, damage, abnormal vibration, etc. of the drum or cleaner blade. As a means for avoiding such a problem, a technique for creating a toner band in an inter-image area between a toner image formed on a photosensitive drum and a toner image formed subsequently is known. Yes. When the toner band is created, friction between the photosensitive drum and the cleaner blade is reduced, and the above-described problems can be suppressed.

As a technique relating to a toner band, for example, the invention described in Patent Document 1 obtains the image density of a toner image on an image carrier and creates a toner band when the image density is lower than a threshold value. The invention described in Patent Document 2 integrates the rotation amount of the photosensitive member whose developing device is stopped, and forms a toner band when the integrated value N reaches the threshold value N1.
JP 2000-112298 A JP 2000-214644 A

  An object of the present invention is to provide a technique capable of creating a toner band at an appropriate timing.

  According to the first aspect of the present invention, while rotating an image holding body that holds an image, the image holding body is irradiated with light to generate an electrostatic latent image, and the electrostatic latent image is developed with a developer. Forming an image, transferring the formed image to a recording medium, and then removing the developer remaining on the surface with a pressing member pressed against the surface of the image carrier, A calculation unit that calculates a value according to the amount of developer used for development when the image is formed, and a value calculated by the calculation unit when the image is formed falls below a first threshold, A driving amount accumulating unit that accumulates the rotational driving amount of the image carrier when the image is formed, and a cumulative value by the driving amount accumulating unit are reduced or reduced to 0 according to a value calculated by the calculating unit. The accumulated value changing means to be changed and the accumulated value by the drive amount accumulating means are set to the second threshold value. When, to provide an image forming apparatus characterized by having an instruction unit that instructs to form a predetermined image on the image forming means.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the cumulative value changing unit has a value calculated by the calculating unit after the driving amount accumulating unit starts accumulating the rotational driving amount. The cumulative value is reduced or changed to 0 when a third threshold value greater than the first threshold value is exceeded.

  According to a third aspect of the present invention, in the image forming apparatus according to the first aspect, the first average value that is an average value of the values during a period in which the image carrier is rotationally driven by the first rotational driving amount; Average value calculating means for calculating a second average value that is an average value of the values during a period in which the image carrier is rotationally driven by a second rotational driving amount larger than the first rotational driving amount. The driving amount accumulating unit starts accumulating the rotational driving amount when the first average value falls below the first threshold, and the driving value accumulating unit The cumulative value is reduced or changed to 0 when the second average value exceeds a third threshold value that is greater than the first threshold value after starting to accumulate the rotational drive amount. And

  According to a fourth aspect of the present invention, in the image forming apparatus according to the first aspect, the first average value that is an average value of the values during a period in which the image carrier is rotationally driven by the first rotational driving amount; Average value calculation means for calculating a second average value that is an average value of the values during a period in which the image carrier is rotationally driven by a second rotational drive amount smaller than the first rotational drive amount. The driving amount accumulating unit starts accumulating the rotational driving amount when the first average value falls below the first threshold, and the driving value accumulating unit The cumulative value is reduced or changed to 0 when the second average value exceeds a third threshold value that is greater than the first threshold value after starting to accumulate the rotational drive amount. And

  In the invention according to claim 5, while rotating the image holding body that holds the image, the image holding body is irradiated with light to generate an electrostatic latent image, and the electrostatic latent image is developed with a developer. Forming an image, transferring the formed image to a recording medium, and then removing the developer remaining on the surface with a pressing member pressed against the surface of the image carrier, A calculation unit that calculates a value according to the amount of developer used for development when the image is formed, and a value calculated by the calculation unit when the image is formed falls below a first threshold, A driving amount accumulating unit for accumulating the rotational driving amount of the image carrier when the image is formed; and when the accumulated value by the driving amount accumulating unit reaches a second threshold, the image forming unit Instruction for instructing to form a predetermined image with an image density corresponding to the value calculated by the calculation means To provide an image forming apparatus characterized by comprising a stage.

  According to the sixth aspect of the invention, while rotating the image holding body that holds the image, the image holding body is irradiated with light to generate an electrostatic latent image, and the electrostatic latent image is developed with a developer. A computer that controls the image forming means that forms an image, transfers the formed image to a recording medium, and then removes the developer remaining on the surface with a pressing member pressed against the surface of the image carrier. Calculating means for calculating a value corresponding to the amount of developer used for development when each of the images is formed; and a value calculated by the calculating means when the image is formed is less than a first threshold value. The driving amount accumulating unit for accumulating the rotational driving amount of the image carrier when the image is formed, and the accumulated value by the driving amount accumulating unit according to the value calculated by the calculating unit, The cumulative value changing means for reducing or changing to 0 and the drive amount accumulating means If the accumulated value reaches a second threshold value, provides a program for causing to function as an instruction means for instructing to form a predetermined image on the image forming means.

  According to the seventh aspect of the invention, while rotating the image holding body that holds the image, the image holding body is irradiated with light to generate an electrostatic latent image, and the electrostatic latent image is developed with a developer. A computer that controls the image forming means that forms an image, transfers the formed image to a recording medium, and then removes the developer remaining on the surface with a pressing member pressed against the surface of the image carrier. Calculating means for calculating a value corresponding to the amount of developer used for development when each of the images is formed; and a value calculated by the calculating means when the image is formed is less than a first threshold value. A driving amount accumulating unit that accumulates the rotational driving amount of the image carrier when the image is formed, and the accumulated value by the driving amount accumulating unit reaches a second threshold value. The forming unit forms a predetermined image with an image density corresponding to the value calculated by the calculating unit. Function as an instruction means for instructing to provide a program characterized.

According to the first and sixth aspects of the invention, after the cumulative value of the rotational driving amount of the photosensitive drum is reduced or changed to 0 according to the image density, the cumulative rotational driving amount is continued to create a toner band. Whether or not to do so is determined based on the accumulated value. Therefore, a toner band is created at an appropriate timing.
According to the second aspect of the present invention, when the value exceeds the third threshold value that is larger than the first threshold value, the cumulative value is reduced or changed to 0. prevent.
According to the third aspect of the invention, since the second drive amount is set to a value larger than the first drive amount, the creation of the toner band is prevented from being suppressed too much.
According to the fourth aspect of the present invention, since the second driving amount is set to a value smaller than the first driving amount, the creation of the toner band is prevented from being promoted too much.
According to the fifth and seventh aspects of the invention, since the image density of the predetermined image data is determined according to the image density, the image density of the toner band is set appropriately.

Now, embodiments of the present invention will be described.
FIG. 1 is a diagram illustrating a hardware configuration of the image forming apparatus 1.
The control unit 4 includes a central processing unit (CPU) 44, a read only memory (ROM) 45, and a random access memory (RAM) 46. The storage unit 5 is, for example, a hard disk drive, and stores an OS (Operating System), application programs, and the like. The ROM 45 stores an IPL (Initial Program Loader), and when the image forming apparatus 1 is powered on, the CPU 44 executes the IPL, thereby reading the OS onto the RAM 46. Then, the CPU 44 controls the image forming apparatus 1 by executing the OS.

  The instruction receiving unit 41 includes a display unit 39 and a key input unit 40. The display unit 39 is a liquid crystal display screen, for example, and displays an image representing an operation menu. Further, the display unit 39 includes a sensor for recognizing an area touched by the operator on the screen, and specifies an item of the menu touched by the operator using this sensor. The key input unit 40 includes start, stop, and reset keys and a numeric keypad. By using the instruction receiving unit 41, the operator can specify the size and orientation of the recording medium (paper) 10, the number of copies, the contents of image quality adjustment, and the like. The instruction received by the instruction receiving unit 41 is sent to the CPU 44, and the CPU 44 controls the image forming apparatus 1 according to the sent instruction.

  A communication I / F (Interface) 48 is connected to a communication network (not shown) such as a LAN (Local Area Network) and the image forming apparatus according to a communication protocol such as TCP / IP (Transmission Control Protocol / Internet Protocol). Mediates communication between 1 and other devices.

  A cover 51 covering the platen glass 2 is provided with a document feeder 52. The document feeder 52 includes a document table 53 on which a document is placed, a roller 54 that feeds the documents placed on the document table 53 one by one, and a roller 55 that guides the sent document onto the platen glass 2. A plurality of documents placed on the document table 53 are conveyed one by one onto the platen glass 2.

  The image input unit 12 optically reads a document and generates an image signal. Specifically, the light source 13 irradiates light on the document placed on the platen glass 2, and the reflected light is received by the light receiving unit 17 through the optical system 3 including the mirrors 14, 15 and 16. . The light receiving unit 17 includes an image sensor such as a CCD (Charge Coupled Device), and converts the reflected light into three image data representing an image of R (Red) color, G (Green) color, and B (Blue) color. To do.

  The image processing unit 18 performs image processing such as color conversion, enlargement / reduction, background removal, and binarization on the input image data. In color conversion, the image processing unit 18 decomposes an image composed of R, G, and B colors into an image composed of Y (Yellow), M (Magenta), C (Cyan), and K (Black) colors. Then, image data representing each image obtained by the decomposition is generated. The image data subjected to the image processing is read at a predetermined timing and supplied to the image output unit 6.

  The image output unit 6 includes image forming engines 7Y, 7M, 7C, and 7K, a transfer belt 8, a fixing device 11, and the like. The image forming engines 7Y, 7M, 7C, and 7K are respectively based on the image data supplied from the image processing unit 18 by an electrophotographic method, Y (Yellow) color, M (Magenta) color, C (Cyan) color, A K (Black) toner image is formed on the surface of the transfer belt 8 so as to overlap. Since the configuration of each image forming engine is common, only the image forming engine 7Y will be described here.

  The image forming engine 7Y includes a charging device 21Y, an exposure device 19Y, a developing device 22Y, a transfer device 25Y, and the like around the photosensitive drum 20Y. The image forming engine 7Y generates an electrostatic latent image by irradiating the photosensitive drum 20Y with light while rotating the photosensitive drum 20Y that holds the image, and develops the electrostatic latent image with a developer. After an image is formed and the formed image is transferred to a recording medium, the developer remaining on the surface is removed by the pressing member 241Y pressed against the surface of the photosensitive drum 20Y. The photoconductor drum 20Y is a cylindrical rotary member that is driven to rotate in the direction of arrow A. An encoder (not shown) is provided on the rotating shaft of the photosensitive drum 20Y, and an index signal is output from the encoder every time the photosensitive drum 20Y rotates once. The charging device 21Y charges the surface of the photosensitive drum 20Y to a predetermined potential.

  The exposure device 19Y is a scanning optical system that irradiates the surface of the photosensitive drum 20Y with an exposure beam LB. Specifically, the exposure device 19Y includes a semiconductor laser and a rotating polygon mirror (not shown). The exposure device 19Y receives supply of image data from the image processing unit 18, and generates an exposure beam LB representing a Y-color image by a semiconductor laser based on the image data. The rotary polygon mirror is driven to rotate at a predetermined angular velocity. The exposure device 19Y deflects and scans the surface of the photosensitive drum 20Y at a predetermined speed in the main scanning direction by reflecting the generated exposure beam LB with a rotating polygon mirror and further reflecting with the reflecting mirror 191Y. Here, the main scanning direction coincides with the direction of the rotation axis of the photosensitive drum 20Y, and the exposure device 19Y causes the pixel value represented by the image data, that is, the latent image corresponding to the image area ratio of each pixel in the main scanning direction. Write. The arrangement of pixels in the main scanning direction is called a scanning line. The sub-scanning direction is a direction orthogonal to the main scanning direction, that is, a circumferential direction, and writing of the latent image in units of scanning lines is repeated in the sub-scanning direction by rotating the photosensitive drum 20Y. On the surface of the photosensitive drum 20Y, the potential of the portion irradiated with the exposure beam LB is lowered to a predetermined level. In this way, an electrostatic latent image based on the image data is formed on the surface of the photosensitive drum 20Y.

  The developing device 22Y develops the electrostatic latent image formed on the surface of the photoreceptor drum 20Y. The toner cartridge 23Y contains a developer composed of Y-color toner and a carrier, and a predetermined amount of developer is supplied to the developing device 22Y. The developing device 22Y charges the developer to a predetermined potential. Then, the toner adheres to the electrostatic latent image due to the potential difference between the electrostatic latent image on the photosensitive drum 20Y and the developer, and a toner image is formed. The transfer belt 8 is stretched around rollers 26, 27, 28, and 29, and is driven to circulate in the direction of arrow B. Below the photosensitive drum 20Y, a transfer device 25Y is provided so as to sandwich the transfer belt 8, and a predetermined voltage is applied. The toner image formed on the surface of the photoreceptor drum 20Y is transferred to the surface of the transfer belt 8 by the action of an electric field generated by a voltage applied to the transfer device 25Y (primary transfer). The cleaner 24Y has a pressing member 241Y that is a plate-like member, and the tip of the pressing member 241Y is pressed against the surface of the photosensitive drum 20Y, and the surface of the photosensitive drum 20Y is touched by the tip of the pressing member 241Y. By rubbing, the toner remaining on the surface of the photoreceptor drum 20Y is removed.

  The above is the configuration of the image forming engine 7Y. In the image forming engines 7M, 7C, and 7K, toner images corresponding to the respective colors are formed and transferred onto the transfer belt 8 in an overlapping manner. Hereinafter, when it is not necessary to distinguish between the image forming engines 7Y, 7M, 7C, and 7K, they are simply referred to as the image forming engine 7. Similarly, for other components, the Y, M, C, and K notations are omitted when it is not necessary to distinguish between Y, M, C, and K.

  A plurality of medium supply units 9 are provided and contain recording media 10 of different sizes. The recording medium 10 is paper, for example. When the toner image is formed on the surface of the transfer belt 8, the CPU 44 determines whether the operator designates one of the medium supply units 9 according to the size designated by the instruction receiving unit 41 or the size determined based on the image data. The corresponding roller 33 is rotated to feed the recording medium 10 one by one. The sent recording medium 10 is conveyed along the conveyance path 36 by roller pairs 34, 35, and 37.

  A predetermined voltage is applied to the transfer roller 30. The transfer belt 8 is circulated and driven in the direction of arrow B, and in synchronization with the toner image formed on the surface thereof approaching the transfer roller 30, the transfer roller 30 passes through the transfer belt 8 with a predetermined load. To form a contact area. Then, the recording medium 10 enters this contact area. The toner image on the transfer belt 8 is transferred onto the surface of the recording medium 10 (secondary transfer) by the action of the electric field applied to the transfer roller 30 and the pressurization in the contact area. The recording medium 10 on which the toner image is transferred is guided to the fixing device 11 by the roller pair 31. The fixing device 11 fixes the toner image on the surface of the recording medium 10 by heating and pressing the recording medium 10.

  A guide member 35 for determining the conveyance path of the recording medium 10 is provided on the downstream side of the fixing device 11, and a plate large enough to load the maximum size recording medium 10 is further provided on the downstream side thereof. A plurality of medium discharge portions 32 having a shape member are provided. The upper medium discharge unit 32 only discharges the recording medium 10. The lower medium discharge unit 32 has a post-processing function such as stapling, and the recording medium 10 is discharged to the lower medium discharge unit 32 only when the operator designates post-processing using the instruction receiving unit 41. Thus, the direction of the guide member 35 is changed.

  FIG. 2 is a block diagram showing functions realized by the CPU 44 executing the program P.

The calculation unit 201 calculates the image density of each toner image. Specifically, it is as follows.
The image data supplied from the image processing unit 18 to the exposure device 19 is data in which the pixel value of each pixel is recorded, and the pixel value is either “0” or “1”. Only when the pixel value is “1”, the electrostatic latent image is written in the area corresponding to the pixel on the photosensitive drum 20. Therefore, the amount of toner used for developing the electrostatic latent image is proportional to the number of pixels having a pixel value “1”. The CPU 44 obtains the image density D of the latent image every time the exposure device 19 writes one page of latent image on the photosensitive drum 20. The image density D is obtained by dividing the number of pixels having a pixel value “1” on the page by the total number of pixels on the page.

  Note that the amount of toner used for development may be calculated instead of the image density. For example, the difference in toner amount in the developing device 22 at the beginning and end of the period during which an image for one page is developed may be obtained. In short, the calculation unit 201 calculates a value corresponding to the amount of developer used for development when each toner image is formed.

  The average value calculation unit 202 includes a first average value D1 that is an average value of the image density D of the toner images for five pages formed immediately before, and an image density D of the toner image for 64 pages formed immediately before. And a second average value D2 that is an average value of. Specifically, the CPU 44 holds the calculated image density D for the previous 64 pages. The CPU 44 obtains an average value D1 (first average value) of the image densities D for the immediately preceding five pages and an average value D2 (second average value) of the image densities D for the 64 pages.

  The number of pages described above is an example, and any number of pages may be used as long as the number of pages for obtaining the second average value D2 is larger than the number of pages for obtaining the first average value D1. The number of pages is an example of an amount representing a period for obtaining the first and second average values. The number of rotations of the photosensitive drum 20, the time when the photosensitive drum 20 is driven to rotate, the photosensitive drum 20 Alternatively, the period may be determined by the time when charging by the charging device 21 is performed. In short, the average value calculation means includes the first average value that is the average value of the image density during the period in which the photosensitive drum 20 is rotationally driven by the first rotational driving amount, and the photosensitive drum 20 is the first rotationally driven. A second average value that is an average value of the image density in a period in which the rotation drive is performed by a second rotation drive amount larger than the amount is calculated.

  The driving amount accumulating unit 203 starts accumulating the rotational driving amount when the first average value falls below the first threshold value. Specifically, the CPU 44 determines whether or not the calculated first average value D1 is below a first threshold value. In the present embodiment, the first threshold is 1%. When the first average value D1 falls below 1%, the CPU 44 starts accumulating the number of pages of toner images formed on the photosensitive drum 20. Let R be the cumulative value thus obtained. The first threshold value 1% is an example, and any value may be used.

The accumulated value changing means 204 changes to the accumulated value R0 when the second average value D2 exceeds the third threshold value after the drive amount accumulating means 203 starts accumulating the rotational drive amount. Specifically, it is as follows.
The CPU 44 determines whether or not the second average value D2 exceeds the third threshold value after starting to accumulate the rotational drive amount of the photosensitive drum 20. In the present embodiment, the third threshold value is 3%. If the second average value D2 exceeds 3%, the CPU 44 changes the accumulated value R to 0, and continues accumulating the rotational drive amount with 0 being the initial value.

  Instead of changing the cumulative value R to 0, the cumulative value may be reduced. For example, the cumulative value R may be reduced to a predetermined value, or the cumulative value R may be reduced by multiplying the cumulative value R by a predetermined coefficient. Further, the third threshold value 3% is an example, and the third threshold value may be any value as long as the value is larger than the first threshold value. In short, the accumulated value changing unit 204 is configured such that, after the driving amount accumulating unit 203 starts accumulating the rotational driving amount, the second average value D2 exceeds a third threshold value that is larger than the first threshold value. The accumulated value R is reduced or changed to zero.

The instructing unit 205 instructs the image forming engine 7 to form a predetermined image when the accumulated value R by the driving amount accumulating unit 203 reaches the second threshold value. Specifically, it is as follows.
The CPU 44 determines whether or not the cumulative value R has reached the second threshold value. In the present embodiment, the second threshold value is a rotational drive amount corresponding to image formation for 10 pages. When the accumulated value R reaches 10 pages, the CPU 44 gives an instruction to the exposure device 19 to write the electrostatic latent image of the toner band on the photosensitive drum 20. The toner band is a toner image having a uniform image density (for example, 100%). Here, the exposure device 19 provides a blank of a predetermined length following the rear end of the electrostatic latent image for one page written immediately before on the photosensitive drum 20, and following this blank, It is set to start writing the electrostatic latent image on the page. This blank section is called an inter image area. The CPU 44 instructs the exposure device 19 to write the electrostatic latent image of the toner band in the inter image area.

  The transfer device 25 does not transfer the toner image to the transfer belt 8 during a period in which the inter-image area passes the transfer position. Therefore, the toner band reaches the position of the cleaner 24 without being transferred to the transfer belt 8, and is removed from the photosensitive drum 20 by the pressing member 241.

  FIG. 3 is a diagram illustrating a flow of operations that the CPU 44 causes the image forming apparatus 1 to perform according to the program P. Here, the image forming apparatus 1 is powered on, and the CPU 44 starts executing the program P.

  First, in step A01, the CPU 44 determines whether or not the number of pages of the image that has been developed on the photosensitive drum 20 has reached 5 pages, and if it has reached 5 pages (step A01: YES), Proceed to step A02. In step A02, the CPU 44 obtains the first average value D1, and compares the first average value D1 with the first threshold value (= 1%). If the first average value D1 is not less than 1% (step A02: NO), the process in step A02 is repeated each time development for one page is completed until the determination result in step A02 becomes YES. If the first average value D1 is less than 1% (step A02: YES), the process proceeds to step A03.

  In step A03, the CPU 44 starts accumulating the rotational drive amount. Next, in step A04, the CPU 44 determines whether or not the number of developed pages has reached 64 pages, and if it has reached 64 pages (step A04: YES), the process proceeds to step A05. If it has not reached 64 pages (step A04: NO), the process proceeds to step A07.

  In step A05, the CPU 44 obtains the second average value D2, and compares the second average value D2 with the third threshold value (= 3%). If the second average value D2 exceeds 3% (step A05: YES), the process proceeds to step A06, and the cumulative value R is changed to zero. Then, the process of step A05 is repeated each time image formation for one page is completed until the determination result of step A05 is NO. If the second average value D2 does not exceed 3% (step A05: NO), the process proceeds to step A07.

  In step A07, the CPU 44 compares the accumulated value R with a second threshold value (= 10 pages). If the accumulated value R has not reached 10 pages (step A07: NO), the process returns to step A05, and each time development of one page is completed until the determination result in step A07 is YES, steps A05 to A07 are performed. Repeat the process. If the accumulated value R reaches 10 pages (step A07; YES), the process proceeds to step A08.

  In step A08, the CPU 44 instructs the exposure device 19 to write the electrostatic latent image of the toner band in the inter image area. When the electrostatic latent image is developed by the developing device 22, a toner band is formed on the photosensitive drum 20. This toner band is removed from the photosensitive drum 20 by the cleaner 24 without being transferred to the transfer belt 8. When the process of step A08 is completed, the process returns to step A02.

The present invention is not limited to the form described above, and can be implemented in various forms. For example, the embodiment described above can be modified as follows.
<Modification 1>
In the above embodiment, the case where the second rotational drive amount is larger than the first rotational drive amount has been described. However, even if the second rotational drive amount is set to a value smaller than the first rotational drive amount. Good. For example, the first rotational drive amount may be set to 5 pages of images, and the second rotational drive amount may be set to 1 page of images as in the above embodiment. That is, in the image forming apparatus according to this modification, the first average value that is the average value of the image density during the period in which the photosensitive drum 20 is rotationally driven by the first rotational driving amount, and the photosensitive drum 20 is the first. An average value calculation unit 202 that calculates a second average value that is an average value of the image density during a period in which the rotation drive amount is smaller than the second rotation drive amount. Starts accumulating the rotational drive amount when the first average value falls below the first threshold, and the accumulated value changing unit 204 starts the accumulation of the rotational drive amount after the drive amount accumulating unit 203 starts accumulating the rotational drive amount. When the average value of 2 exceeds a third threshold value that is greater than the first threshold value, the cumulative value R is reduced or changed to zero. In this case, since the number of pages has already reached five when step A04 in FIG. 3 is reached, the processing in step A04 may be omitted.

<Modification 2>
Instead of the first average value and the second average value, the image density of the image for one page formed immediately before may be used. In this case, in the flow of FIG. 3, “page 64” in step A01 may be changed to “1 page”, and the process in step A04 may be omitted. That is, the driving amount accumulating unit 203 accumulates the rotational driving amount of the photosensitive drum 20 when the value calculated by the calculating unit 201 falls below the first threshold value. Further, the cumulative value changing unit 204 starts when the driving amount accumulating unit 203 starts accumulating the rotational driving amount and then the value calculated by the calculating unit 201 exceeds a third threshold value that is larger than the first threshold value. The accumulated value R is reduced or changed to zero.

  Therefore, the superordinate concept of the configuration shown in the embodiment, the first modification, and the second modification is that an electrostatic latent image is generated by irradiating the image holding body with light while rotating the image holding body holding the image. The electrostatic latent image is developed with a developer to form an image, the formed image is transferred to a recording medium, and then pressed against the surface of the image holding member on the surface. Image forming means for removing remaining developer, calculation means for calculating a value corresponding to the amount of developer used for development when each of the images is formed, and calculation means when an image is formed When the calculated value is less than the first threshold value, a driving amount accumulating unit that accumulates the rotational driving amount of the image carrier when the image is formed, and a cumulative value by the driving amount accumulating unit, In accordance with the value calculated by the calculating means, the cumulative value is changed or reduced to zero. And an instruction means for instructing the image forming means to form a predetermined image when the accumulated value by the drive amount accumulating means reaches a second threshold value. .

<Modification 3>
Moreover, you may comprise as follows.
FIG. 4 is a block diagram showing functions realized by the CPU 44 executing the program P in this modification. The calculation means 201, average value calculation means 202, and drive amount accumulation means 203 are the same as those in the above embodiment.
Next, FIG. 5 is a diagram illustrating a flow of operations that the CPU 44 causes the image forming apparatus 1 to perform according to the program P. In the figure, the processes in steps A01 to A03 and A07 are the same as those in the above embodiment.

  The instruction unit 305 forms a predetermined image with an image density corresponding to the value calculated by the calculating unit 201 in the image forming engine 7 when the accumulated value R by the driving amount accumulating unit 203 reaches the second threshold value. Instruct. Specifically, in step B08, when the accumulated value R reaches 10 pages, the CPU 44 determines the image density of the toner band according to the second average value calculated by the average value calculation unit 202. The control unit 4 is provided with a table that defines the correspondence between the image density of the developed image and the image density of the toner band to be created accordingly, and determines the image density of the toner band according to this table. Then, the exposure apparatus 19 is instructed to write an electrostatic latent image of a toner band having the determined image density. As a result, a toner band having an image density corresponding to the second average value is formed on the photosensitive drum 20 and is removed by the cleaner 24. Note that the image density of the image for one page formed immediately before may be used instead of the first average value.

  That is, the invention according to this modification generates an electrostatic latent image by irradiating light to the image holding body while rotating the image holding body that holds the image, and the electrostatic latent image is developed with a developer. An image forming means for forming an image by developing, transferring the formed image to a recording medium, and then removing the developer remaining on the surface with a pressing member pressed against the surface of the image carrier; A calculation unit that calculates a value corresponding to the amount of developer used for development when the image is formed, and a value calculated by the calculation unit when the image is formed is less than a first threshold value And a driving amount accumulating unit that accumulates the rotational driving amount of the image carrier when the image is formed, and the image forming unit when the accumulated value by the driving amount accumulating unit reaches a second threshold value. In order to form a predetermined image with an image density corresponding to the value calculated by the calculating means To provide an image forming apparatus characterized by having an instruction unit for. According to this modification, a toner band is created with an image density corresponding to a value corresponding to the amount of developer used for development when each image is formed.

<Modification 4>
In the above embodiment, the example in which the program P is stored in the storage unit 5 in advance has been described. However, the program P can be read by a computer such as a magnetic recording medium, an optical recording medium, a magneto-optical recording medium, or a semiconductor memory. It may be provided in a recorded state. Further, the program P may be downloaded through a communication line.
In the above-described embodiment, the example in which the function of FIG. 3 is realized by the CPU 44 executing the program P is shown, but an electronic circuit that realizes the same function may be mounted in the image forming apparatus 1.

2 is a diagram illustrating a hardware configuration of the image forming apparatus 1. FIG. It is a block diagram showing the function implement | achieved when CPU44 runs the program P. FIG. FIG. 4 is a diagram illustrating a flow of operations that the CPU 44 causes the image forming apparatus 1 to perform according to a program P. It is a block diagram showing the function implement | achieved when CPU44 runs the program P. FIG. FIG. 4 is a diagram illustrating a flow of operations that the CPU 44 causes the image forming apparatus 1 to perform according to a program P.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 4 ... Control part, 44 ... CPU, 45 ... ROM, 46 ... RAM, 5 ... Memory | storage part, 41 ... Instruction reception part, 48 ... Communication I / F, 12 ... Image input part, 18 ... Image Processing unit, 6: Image output unit, 7Y, 7M, 7C, 7K ... Image forming engine, 8 ... Transfer belt, 11 ... Fixing device, 21Y ... Charging device, 19Y ... Exposure device, 22Y ... Exposure device, 25Y ... Transfer device 24Y ... cleaner, 241Y ... pressing member, 9 ... medium supply unit, 30 ... transfer roller, 32 ... medium discharge unit, 201 ... calculation unit, 202 ... average value calculation unit, 203 ... driving amount accumulation unit, 204 ... accumulation Value changing means, 205 ... instruction means

Claims (7)

While rotating the image holding body that holds the image, the image holding body is irradiated with light to generate an electrostatic latent image, and the electrostatic latent image is developed with a developer to form an image. Image forming means for removing the developer remaining on the surface with a pressing member pressed against the surface of the image carrier after the image is transferred to the recording medium;
Calculating means for calculating a value corresponding to the amount of developer used for development when each of the images is formed;
Drive amount accumulating means for accumulating the rotational drive amount of the image carrier when the image is formed when the value calculated by the calculating means when the image is formed is below a first threshold;
Cumulative value changing means for reducing or changing the accumulated value by the driving amount accumulating means to 0 according to the value calculated by the calculating means;
An image forming apparatus comprising: an instruction unit that instructs the image forming unit to form a predetermined image when a cumulative value by the driving amount accumulating unit reaches a second threshold value. The accumulated value changing means, when the value calculated by the calculating means exceeds a third threshold value larger than the first threshold value after the drive amount accumulating means starts accumulating the rotational drive amount, The image forming apparatus according to claim 1, wherein the cumulative value is reduced or changed to zero. A first average value that is an average value of the values during a period in which the image carrier is rotationally driven by a first rotational drive amount, and a second value that is greater than the first rotational drive amount. An average value calculating means for calculating a second average value that is an average value of the values during a period in which the rotation drive amount is rotated;
The driving amount accumulating unit starts accumulating the rotational driving amount when the first average value falls below the first threshold value,
The cumulative value changing unit is configured such that, after the driving amount accumulating unit starts accumulating the rotational driving amount, the second average value exceeds a third threshold value that is larger than the first threshold value. The image forming apparatus according to claim 1, wherein the cumulative value is reduced or changed to zero. A first average value that is an average value of the values during a period in which the image carrier is rotationally driven by the first rotational drive amount, and a second value that is smaller than the first rotational drive amount. An average value calculating means for calculating a second average value that is an average value of the values during a period in which the rotation drive amount is rotated;
The driving amount accumulating unit starts accumulating the rotational driving amount when the first average value falls below the first threshold value,
The cumulative value changing unit is configured such that, after the driving amount accumulating unit starts accumulating the rotational driving amount, the second average value exceeds a third threshold value that is larger than the first threshold value. The image forming apparatus according to claim 1, wherein the cumulative value is reduced or changed to zero. While rotating the image holding body that holds the image, the image holding body is irradiated with light to generate an electrostatic latent image, and the electrostatic latent image is developed with a developer to form an image. Image forming means for removing the developer remaining on the surface with a pressing member pressed against the surface of the image carrier after the image is transferred to the recording medium;
Calculating means for calculating a value corresponding to the amount of developer used for development when each of the images is formed;
Drive amount accumulating means for accumulating the rotational drive amount of the image carrier when the image is formed when the value calculated by the calculating means when the image is formed is below a first threshold;
An instruction means for instructing the image forming means to form a predetermined image with an image density corresponding to the value calculated by the calculating means when the accumulated value by the driving amount accumulating means reaches a second threshold value; An image forming apparatus comprising: While rotating the image holding body that holds the image, the image holding body is irradiated with light to generate an electrostatic latent image, and the electrostatic latent image is developed with a developer to form an image. A computer for controlling the image forming means for removing the developer remaining on the surface with a pressing member pressed against the surface of the image carrier after the image is transferred to the recording medium;
Calculating means for calculating a value corresponding to the amount of developer used for development when each of the images is formed;
Drive amount accumulating means for accumulating the rotational drive amount of the image carrier when the image is formed when the value calculated by the calculating means when the image is formed is below a first threshold;
Cumulative value changing means for reducing or changing the accumulated value by the driving amount accumulating means to 0 according to the value calculated by the calculating means;
A program that causes the image forming unit to function as an instruction unit for instructing a predetermined image to be formed when a cumulative value by the driving amount accumulating unit reaches a second threshold value. While rotating the image holding body that holds the image, the image holding body is irradiated with light to generate an electrostatic latent image, and the electrostatic latent image is developed with a developer to form an image. A computer for controlling the image forming means for removing the developer remaining on the surface with a pressing member pressed against the surface of the image carrier after the image is transferred to the recording medium;
Calculating means for calculating a value corresponding to the amount of developer used for development when each of the images is formed;
Drive amount accumulating means for accumulating the rotational drive amount of the image carrier when the image is formed when the value calculated by the calculation means when the image is formed is below a first threshold;
When the accumulated value by the driving amount accumulating means reaches a second threshold value, it functions as an instruction means for instructing the image forming means to form a predetermined image with an image density corresponding to the value calculated by the calculating means. A program characterized by letting

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