JP2015059975A - Image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively use toner of a color cartridge and suppress consumption of toner of a black cartridge.SOLUTION: An image formation device includes: a plurality of cartridges 631 for housing toner of different colors; and a CPU 600 which can switch between a first mode for forming a black image by using only the cartridge 631 that houses black color among the plurality of cartridges 631 and a second mode for forming a black image by using the plurality of cartridges 631. The CPU 600, in a case where a black image is formed on a recording material, switches between the first mode and second mode, based on lives of the plurality of cartridges 631 except for the cartridge 631 that houses the toner.

Description

  The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a laser beam printer, and a facsimile.

  Conventionally, a plurality of rotatable image carriers provided in accordance with toner colors, a developing unit provided for each image carrier, and a rotatable belt member in contact with the surface of each image carrier. An image forming apparatus is known. According to this configuration, the toner is supplied from the developing unit to form a toner image on the surface of the image carrier, and the toner image is transferred to the recording material carried on the belt member, thereby forming an image on the recording material. be able to. It is also known that the toner image is primarily transferred from the surface of the image carrier onto the belt member, and the toner image is secondarily transferred from the belt member onto the recording material.

  Normally, when performing monochrome printing (printing in black), printing using only toner from a black (black) cartridge (single-color monochrome printing) is performed. However, if the frequency of monochrome printing is high, only the toner consumption of the black cartridge increases and a lot of toner remains in the color cartridge, but there is a case where the toner in the black cartridge runs out. Therefore, for example, in Patent Document 1, when the toner in the black cartridge is low, toner is generated in a pseudo manner using toners of a plurality of color cartridges excluding black, and monochrome printing (multicolor monochrome printing) is performed. The technology to do is released. Thus, the toner of the color cartridge can be used effectively, while the consumption of the toner of the black cartridge can be suppressed.

JP-A-7-178931

  In Patent Document 1 described above, whether or not to perform multicolor monochrome printing is determined based on whether or not the toner amount of the black cartridge falls below a predetermined amount. Therefore, multi-color monochrome printing with a color cartridge is not performed unless the toner amount of the black cartridge falls below a predetermined amount. On the other hand, when there is a lot of color printing with a low printing rate, the toner in the color cartridge is still sufficient, but the developer or photosensitive drum may reach the end of its life and the cartridge may need to be replaced. There is a problem that it cannot be used effectively. In this case, when performing monochrome printing, even if the toner amount of the black cartridge is not less than the predetermined amount, the toner of the color cartridge can be used more effectively by performing the monochrome printing of the multi-color, and the toner of the black cartridge Consumption can be suppressed.

  The present invention has been made under such circumstances, and an object thereof is to effectively use toner of a color cartridge and suppress consumption of toner of a black cartridge.

  In order to solve the above-described problems, the present invention is configured as follows.

  (1) A plurality of cartridges that store toners of different colors, a first mode that forms a black image using only a cartridge that stores black toner among the plurality of cartridges, and the plurality of cartridges. And a control unit capable of switching a second mode for forming a black image by using the plurality of control units except the cartridge containing the black toner when the black image is formed on the recording material. An image forming apparatus that switches between the first mode and the second mode based on the life of each cartridge.

  According to the present invention, the toner of the color cartridge can be effectively used and the consumption of the toner of the black cartridge can be suppressed.

Schematic configuration diagram showing the configuration of the image forming apparatus of Examples 1 to 3 Functional block diagram showing the system configuration of the image forming apparatus of Examples 1 to 3, and a functional block diagram for measuring the number of print pixels 7 is a flowchart illustrating a monochrome printing control sequence according to the first embodiment. 10 is a flowchart illustrating a monochrome printing control sequence according to the second embodiment. Flowchart showing a monochrome printing control sequence according to the third embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  In the first embodiment, when monochrome printing is performed, it is determined whether single-color monochrome printing or multi-color monochrome printing is performed depending on the life factor of a color cartridge (hereinafter also referred to as a cartridge). explain. In the following, “monochrome monochrome printing” refers to monochrome printing (printing in black) using only toner from a black (black) cartridge. “Multicolor monochrome printing” refers to monochrome printing (printing in black) in which a pseudo black color is created using toner from a plurality of color cartridges excluding black. In multicolor monochrome printing, monochrome printing may be performed using a black cartridge in addition to a color cartridge.

[Configuration of Image Forming Apparatus]
FIG. 1 is a schematic configuration diagram illustrating a configuration of an electrophotographic image forming apparatus according to the present exemplary embodiment. This image forming apparatus is a color image forming apparatus employing an intermediate transfer belt as an intermediate transfer member. As shown in FIG. 1, the image forming apparatus includes four process cartridges (hereinafter also referred to as cartridges). Each process cartridge includes photosensitive drums 2a, 2b, 2c, and 2d for yellow (Y), magenta (M), cyan (C), and black (K), which are side-by-side image carriers. Around the photosensitive drums 2a, 2b, 2c, and 2d of each process cartridge, the chargers 7a, 7b, 7c, and 7d, and developing devices 3a, 3b, 3c, and 3d, which are developing units, are sequentially arranged from the upstream side in the rotation direction. Cleaning devices 5a, 5b, 5c and 5d are arranged. In the following description, symbols a, b, and y corresponding to the colors of yellow (Y), magenta (M), cyan (C), and black (K) toners accommodated in the process cartridge, unless particularly required. Description of c and d is omitted.

  The charger 7 uniformly charges the surface of the photosensitive drum 2. The surface of the photosensitive drum 2 uniformly charged by the charger 7 is irradiated with a laser beam from the exposure devices 1a, 1b, 1c, and 1d based on the image information to form an electrostatic latent image. The developing device 3 uses a developing roller 6a, 6b, 6c, 6d, which is a toner carrying member that carries and conveys toner (developer), on the surface of the photosensitive drum 2 on which the electrostatic latent image is formed. (Agent) is supplied and adhered, and visualized as a toner image. In the present embodiment, the developing rollers 6a, 6b, 6c, and 6d can be in contact with or separated from the photosensitive drums 2a, 2b, 2c, and 2d, respectively. The developing rollers 6a, 6b, 6c, and 6d are in contact with the photosensitive drums 2a, 2b, 2c, and 2d, and can visualize the electrostatic latent images formed on the drums as toner images. When performing monochrome monochrome printing, the black developing roller 6d is in contact with the photosensitive drum 2d, and the developing rollers 6a, 6b, 6c of colors other than black are separated from the photosensitive drums 2a, 2b, 2c. When performing multi-color monochrome printing, the developing rollers 6a, 6b, 6c of colors other than black are in contact with the photosensitive drums 2a, 2b, 2c, and the black developing roller 6d is separated from the photosensitive drum 2d. The cleaning device 5 removes the toner remaining on the surface of the photosensitive drum 2 after the transfer, and collects it in the remaining toner container.

  An intermediate transfer belt 10, which is an intermediate transfer body to which a toner image formed on the surface of the photosensitive drum 2 is transferred, is stretched by a driving roller 11, a tension roller 12 and a driven roller 13, and faces the photosensitive drum 2. . In this embodiment, the photosensitive drum 2 is in contact with the intermediate transfer belt 10 and cannot be separated. Therefore, when performing multi-color monochrome printing, the drum provided in each cartridge is consumed regardless of when performing monochrome monochrome printing. Further, a secondary transfer roller 22 is disposed at a position facing the driving roller 11 with the intermediate transfer belt 10 interposed therebetween, and constitutes a secondary transfer portion.

  The toner image formed on each photosensitive drum 2 is transferred to the intermediate transfer belt 10 by primary transfer rollers 4a, 4b, 4c, and 4d that are primary transfer portions. On the other hand, the recording material fed from the feeding cassette 30 by the pickup roller 31 is separated and fed one by one by a separating means (not shown). Then, the recording material is conveyed to the registration roller pair 33, and further conveyed by the registration roller pair 33 between the intermediate transfer belt 10 and the secondary transfer roller 22 at a predetermined timing. Then, the toner image on the intermediate transfer belt 10 is transferred to the recording material by the secondary transfer roller 22. After the toner image is fixed by the fixing device 34, the recording material onto which the toner image has been transferred is conveyed by a discharge roller pair 35 and discharged to a discharge tray 36 provided in the upper part of the image forming apparatus main body.

  A residual toner charging roller 14 that is a residual toner charging unit is disposed on the intermediate transfer belt 10 in order to charge the residual toner that has not been transferred to the recording material and has adhered to the intermediate transfer belt 10. The residual toner charging roller 14 charges the transfer residual toner remaining on the intermediate transfer belt 10 after transfer to the recording material. Then, the charged transfer residual toner moves to the primary transfer portion while being on the intermediate transfer belt 10, is reversely transferred to the photosensitive drum 2 by the primary transfer roller 4, and is collected by the cleaning device 5.

[System configuration of image forming apparatus]
Next, the system configuration of the image forming apparatus of this embodiment will be described. FIG. 2A is a functional block diagram for explaining the system configuration of the image forming apparatus. In FIG. 2A, the controller 650 sends a command for image formation to the image formation engine 620 via the video interface 640. The image forming engine 620 includes a CPU 600, a ROM 601, a RAM 602, a non-volatile memory 603, and an image forming unit 630. Further, the image forming unit 630 includes a process cartridge 631, a secondary transfer roller 22, a residual toner charging roller 14, a fixing device 34, and the like. Further, as described above, the process cartridge 631 includes the charger 7, the exposure device 1, the developing device 3, the cleaning device 5, and the primary transfer roller 4.

  The CPU 600 executes an image forming operation while controlling the image forming unit 630 using the RAM 602 as a work area based on various control programs stored in the ROM 601. The non-volatile memory 603 is a memory that can retain stored contents even when the power is turned off, and is used to store life information described later. Note that part or all of the processing performed by the CPU 600 may be performed by an ASIC (application-specific integrated circuit) that is an integrated circuit.

  Further, the CPU 600 detects the lifetime of the toner, detects the lifetime of the toner based on the remaining amount of toner, detects the lifetime of the photosensitive drum 2, detects the lifetime of the photosensitive drum 2, and detects the lifetime of the developing device 3. I do. In this embodiment, “toner life” is the remaining life until the toner runs out based on the remaining amount of toner, “drum life” and “development life” are the service life of the photosensitive drum 2 and the development in the developing unit 3 respectively. It refers to the remaining life until the useful life of the roller 6 is reached. In addition, the lifetime is assumed to be 100% when it is in a new state, and the remaining lifetime is expressed as%.

  In the toner life detection according to the present exemplary embodiment, an image dot detection method is used in which the toner consumption is calculated by counting the number of image dots formed on the surface of the photosensitive drum 2. FIG. 2B is a diagram showing a functional block for measuring the number of print pixels necessary for the image dot detection method for detecting the toner life. In FIG. 2B, image data is transmitted to the controller 650 from a host computer (not shown). The controller 650 converts the image data into a laser lighting amount and lighting timing control signal. Then, via the video interface 640, the controller 650 transmits this control signal to the image forming engine 620 as a video signal S1 that is an image signal. The image forming engine 620 includes a laser lighting count circuit 800 that counts pixels that are turned on by the laser, and the CPU 600 includes a printing pixel number counting unit 500 that counts the number of printing pixels based on the output of the laser lighting counting circuit 800. . The laser lighting count circuit 800 detects the laser lighting in the video signal S1 for one page of the recording material transmitted from the controller 650, and counts printing pixels which are pixels to which toner is attached. The printing pixel number counting unit 500 acquires the number of printing pixels counted by the laser lighting count circuit 800, and uses the acquired number of printing pixels as an integrated value (cumulative value) of the number of printing pixels stored in the nonvolatile memory 603. Perform the addition process.

  The laser lighting count circuit 800 is constituted by a synchronous digital circuit, but the system clock is not shown in FIG. The video signal S1 input from the controller 650 is input to a flip-flop (F / F) 801 and latched by a system clock (not shown). The sample timing generator 804 receives a horizontal enable signal S2 indicating an image area in the scanning direction of the laser beam and a vertical enable signal S3 indicating a vertical image printing area that is orthogonal to the scanning direction of the laser beam. The The horizontal enable signal S2 can be generated by a control logic circuit (not shown) inside the image forming engine 620 based on a horizontal synchronization signal (not shown). Further, the vertical enable signal S3 can be generated by a control logic circuit (not shown) inside the image forming engine 620 according to the recording material conveyance timing.

  The gate circuit 802 outputs a high level when the latched video signal S1 is in an on state in which the laser is turned on at the timing determined by the sample timing generation unit 804. The counter 803 counts the number of times that the gate circuit 802 is at a high level within a predetermined image area, that is, the number of times that the video signal S1 is in the ON state. The count value of the counter 803 is output to the print pixel number counting unit 500 of the CPU 600 when the image forming engine 620 receives all the video signals S1 for the corresponding page to be printed from the controller 650. The accumulated value of the print pixel count calculated by the print pixel count counting unit 500 is updated as needed and stored in the nonvolatile memory 603. By dividing the calculated print pixel count cumulative value by the total number of print pixel counts corresponding to the life of the toner, that is, the number of pixels that can be printed from the state where the toner is 100% until the toner runs out, the toner usage amount Can be calculated. The toner life that is the remaining life of the toner can be calculated from the ratio of the obtained toner usage.

  In addition to the image dot detection method, in order to detect the amount of toner in the developing device 3, the operation path of the stirring member that stirs the toner in the developing device 3 is irradiated with laser light, and the amount of light passing therethrough is measured By doing so, an optical part detector for detecting the toner amount may be used. Furthermore, an antenna type detection unit that detects the amount of toner by measuring the capacitance with a metal antenna provided in the container of the developing device 3 may be used.

  Further, the image forming engine 620 acquires the rotational speeds of the photosensitive drum 2 and the developing roller 6 of the developing device 3 when the recording material is image-formed, and the nonvolatile memory 603 stores the accumulated values of the respective rotational speeds. The The drum life and the development life correspond to the service life of the photosensitive drum 2 and the service life of the developing roller 6, and the photosensitive drum 2 and the developing roller 6 have a total rotation speed from the start of use of the cartridge to the end of the life. It can be obtained by calculating the ratio of the rotational speed cumulative value. Further, even if the developing roller 6 rotates while the developing roller 6 is separated from the photosensitive drum 2, the number of rotations of the developing roller 6 is not counted. It should be noted that the total number of revolutions corresponding to the useful life of the photosensitive drum 2, the total number of revolutions equivalent to the useful life of the developing roller 6, and the total number of print pixel counts corresponding to the above-described toner life are counted. Is stored in the ROM 601 in advance, for example. If the process cartridge 631 has a non-volatile memory, and the total number of rotations of the photosensitive drum 2, the total number of rotations of the developing roller 6, and the total number of print pixel counts are stored in the non-volatile memory, the CPU 600 May be read and set in the RAM 602.

[Control sequence for monochrome printing]
FIG. 3A is a flowchart illustrating a control sequence during printing of the image forming apparatus according to the present exemplary embodiment. A monochrome printing control sequence will be described with reference to the flowchart of FIG. In this embodiment, a monochrome printing mode is set for each page of the recording material. In step 101 (hereinafter referred to as S101), when receiving an image formation start command from the controller 650 via the video interface 640, the CPU 600 performs pre-rotation processing necessary for image formation. When the pre-rotation process is completed, in S102, the CPU 600 performs monochrome print setting based on the life factor (details will be described later). In S <b> 103, the CPU 600 controls the above-described image forming operation and performs printing (image formation) on the recording material conveyed from the feeding cassette 30. In S104, the CPU 600 determines whether or not the print job has ended. If it is determined that the print job has not ended, the process returns to S102, and if it is determined that the print job has ended, the process proceeds to S105. In step S105, the CPU 600 performs post-rotation processing as post-processing of the image forming apparatus. When the post-rotation processing ends, the series of processing ends.

  Next, the “monochrome print setting based on life factor” process in S102 will be described in detail. FIG. 3B is a flowchart showing a control sequence of the monochrome print setting process based on the life factor. In “Monochrome print setting based on life factor” shown in FIG. 3B, based on the life of the color cartridge, either single color monochrome printing with a yellow, magenta, or cyan color cartridge is performed, or monochrome monochrome printing with a black cartridge. Decide what to do with.

  In this embodiment, the life of the process cartridge is managed by three pieces of life information of toner life, drum life, and development life, and the shortest life is the life of the process cartridge. Whether or not to perform multi-color monochrome printing is determined based on the life information of each color cartridge of yellow, magenta, and cyan. For example, a cartridge that has a little remaining drum life and development life, but has a sufficient toner life, may have a sufficient amount of toner remaining when the cartridge reaches the end of its life due to the drum life or development life. Is expensive. Therefore, in this embodiment, in order to effectively use the toner of the color cartridge, when the toner life of the color cartridge remains sufficiently with respect to the drum life, when monochrome printing is performed, the monochrome printing is not performed. Multi-color monochrome printing is performed.

First, as a condition for performing multi-color monochrome printing, the first condition is that the toner life is longer than the drum life by a predetermined value, and in this embodiment, the predetermined value is 40%, which is shown in Expression (1).
Toner life-drum life ≥ 40% (1)

Also, by performing multi-color monochrome printing, the developing roller 6 of yellow, magenta, and cyan color cartridges is driven as compared with single-color monochrome printing using only the black cartridge, so the development life of these color cartridges is consumed. To do. Accordingly, in the case of a cartridge with a short development life, even if the remaining amount of toner is sufficient, the development life is further reduced by driving the development roller 6 when multicolor monochrome printing is performed, and the life of the color cartridge is reduced. Will be shrunk. Therefore, the following condition (2) is satisfied as a second condition for performing multicolor monochrome printing.
Development life> Drum life (2)

  Based on the above two conditions, the flowchart of FIG. 3B will be described. In S <b> 201, the CPU 600 acquires cartridge life information stored in the nonvolatile memory 603, that is, the print pixel number count accumulated value and the rotation number accumulated value of the developing roller 6 of the photosensitive drum 2 and the developing device 3. Furthermore, the CPU 600 calculates the total number of rotations corresponding to the service life of each of the photosensitive drum 2 and the developing roller 6 and the number of printable pixels corresponding to the life of the toner from the ROM 601 for calculating the life of the cartridge. Read and obtain the total number of print pixel counts.

  Subsequently, in S202 to S208, the CPU 600 calculates the toner life, drum life, and development life of each of the yellow, magenta, and cyan color cartridges by the above-described method, and determines whether or not multicolor monochrome printing is possible for each cartridge. To do. In S202, the CPU 600 calculates the life of the corresponding cartridge, that is, the toner life, the drum life, and the development life using the cartridge life information acquired in S201. In S203, the CPU 600 compares the calculated development life and the drum life, and determines whether the development life is longer than the drum life. When the CPU 600 determines that the developing life is longer than the drum life, the CPU 600 proceeds to S204, and when determining that the developing life is equal to or less than the drum life, the CPU 600 proceeds to S207. In S204, the CPU 600 determines whether or not the obtained ratio (%) is equal to or greater than a predetermined value (40% in this embodiment) as a result of subtracting the drum life from the toner life. If the CPU 600 determines that the value is equal to or greater than the predetermined value, the process proceeds to S205. If the CPU 600 determines that the value is less than the predetermined value, the process proceeds to S207. In S205, the CPU 600 determines that multi-color monochrome printing using the corresponding cartridge is possible, and performs a setting to permit multi-color monochrome printing of the corresponding cartridge. In step S207, the CPU 600 determines that multicolor monochrome printing using the corresponding cartridge cannot be performed, and performs a setting for prohibiting the multicolor monochrome printing of the corresponding cartridge. In S208, the CPU 600 determines whether or not the processing from S202 to S207 has been completed for each of the yellow, magenta, and cyan color cartridges. If it is determined that the processing has not been completed, the CPU 600 returns to S202 and determines that the processing has been completed. If so, the process proceeds to S209.

  In step S209, the CPU 600 determines whether there is a cartridge set to prohibit multicolor monochrome printing in each of the yellow, magenta, and cyan color cartridges. If the CPU 600 determines that there is a cartridge that is set to prohibit multicolor monochrome printing, the process proceeds to S210. If the CPU 600 determines that there is no cartridge set to prohibit multicolor monochrome printing, the process proceeds to S211. In S210, the CPU 600 notifies the controller 650 through the video interface 640 to perform monochrome monochrome printing. In S211, the CPU 600 notifies the controller 650 via the video interface 640 so as to perform multi-color monochrome printing, and finishes the monochrome printing setting process based on the life factor.

  As described above, according to the present embodiment, the toner of the color cartridge can be effectively used and the consumption of the toner of the black cartridge can be suppressed. That is, when performing monochrome printing, it is determined according to the life of the color cartridge whether single-color monochrome printing or multi-color monochrome printing is performed. This makes it possible to effectively use the toner of the color cartridge excluding black and suppress the consumption of the toner of the black cartridge. As a result, it is possible to realize an optimal replacement frequency of the color cartridge.

In this embodiment, the monochrome printing mode is set for each page of the recording material under the same conditions. However, the mode may be set for different conditions for the second and subsequent prints. That is, when the first print is performed, the CPU 600 sets the monochrome print mode according to the flowchart of FIG. When the second and subsequent sheets are printed, the monochrome print mode once set is switched according to the following conditions. That is, when the above-described equations (1) and (2) are satisfied in the state where the multi-color monochrome printing mode is set, the CPU 600 switches to the monochrome monochrome printing mode. If the above-described equation (2) is not satisfied or the following equation (3) is satisfied in a state where the monochrome monochrome printing mode is set, the CPU 600 sets the monochrome monochrome printing mode. Switch to.
Toner life ≤ drum life (3)

  Here, the reason for setting the mode switching condition as described above is to prevent frequent switching of the mode because the toner is consumed faster than the drum. When the mode is frequently switched, the contact and separation of the developing roller provided in the color cartridge are repeated, and noise and throughput are reduced.

  In this embodiment, the monochrome printing mode is set for each page of the recording material. However, the mode may be set for each print job. That is, when a print job is started, a monochrome printing mode is set according to the flowchart of FIG. 3, and printing is continued in the set mode during printing of the same job.

  In the first embodiment, when performing monochrome printing, a description will be given of an embodiment in which it is determined whether single-color monochrome printing or multi-color monochrome printing is to be performed based on lifetime factors of yellow, magenta, and cyan color cartridges. did. However, when monochrome printing is performed with multicolor monochrome printing, if the printing rate is low, the effect of effectively using the toner of the color cartridge is reduced, while the photosensitive drum and developing roller of the color cartridge are driven. Is consumed. Therefore, in the second embodiment, when performing monochrome printing, in addition to the life factor of the color cartridge performed in the first embodiment, in addition to determining whether to perform single-color monochrome printing or multi-color monochrome printing, A description will be given of an embodiment in which determination is made in consideration of the printing rate. In this embodiment, the same image forming apparatus as in the first embodiment is used, and the description of the image forming apparatus is omitted because it overlaps with the first embodiment.

[Control sequence for monochrome printing]
FIG. 4A is a flowchart illustrating a control sequence during printing of the image forming apparatus according to the present exemplary embodiment. A monochrome printing control sequence will be described with reference to the flowchart of FIG.

  In S301, upon receiving an image formation start command from the controller 650 via the video interface 640, the CPU 600 performs pre-rotation processing necessary for image formation. When the pre-rotation process ends, in S302, the CPU 600 performs monochrome print setting based on the life factor. The monochrome print setting based on the life factor is the process shown in the flowchart of FIG. 3B of the first embodiment, and the description thereof is omitted here. Subsequently, in S303, the CPU 600 determines whether or not multicolor monochrome printing is permitted in the processing of S302. If the CPU 600 determines that multi-color monochrome printing is permitted, the process proceeds to S304. If the CPU 600 determines that multi-color monochrome printing is not permitted, the process proceeds to S305. In S304, the CPU 600 performs monochrome print setting based on the number of print pixels (details will be described later). In step S <b> 305, the CPU 600 controls the above-described image forming operation, and performs printing (image formation) on the recording material conveyed from the feeding cassette 30. In S306, the CPU 600 determines whether or not the print job has ended. If it is determined that the print job has not ended, the process returns to S302. If it is determined that the print job has ended, the process proceeds to S307. In step S307, the CPU 600 performs post-rotation processing as post-processing of the image forming apparatus. When the post-rotation processing ends, the series of processing ends.

  Next, the “monochrome print setting based on the number of print pixels” process in S304 will be described in detail. FIG. 4B is a flowchart showing a control sequence of monochrome print setting processing based on the number of print pixels. In the “monochrome print setting based on the number of print pixels” process shown in FIG. 4B, either the multicolor monochrome printing is performed with the yellow, magenta, and cyan color cartridges based on the printing rate of the recording material, or the black cartridge is used. Decide whether to perform monochrome monochrome printing.

  When monochrome printing is performed, if the printing rate is low, the toner of the color cartridge is not consumed much even if multicolor monochrome printing is used. However, since the photosensitive drum 2 and the developing roller 6 of the color cartridge are consumed, the cartridge cannot be used efficiently. Therefore, in this embodiment, in order to use the color cartridge effectively, in addition to the expressions (1) and (2) which are the conditions of the life factor of the color cartridge described in the first embodiment, a condition corresponding to the printing rate is set. Shall be added. The condition corresponding to the printing rate is the consumption rate of the color toner life per recording material determined from the printing rate at the time of monochrome printing, and the life of the photosensitive drum 2 and the developing roller 6 consumed at that time. If it is greater than the rate, then it is assumed that multicolor monochrome printing is performed.

  Here, the “printing rate” will be described. As described above, the CPU 600 uses the print pixel number counting unit 500 to acquire the print pixel number for each page of the recording material and for each toner color of the color cartridge. For example, in the print pixel number counting unit 500 of this embodiment, the number of print pixels when the toner is attached to the entire surface of the LETTER size recording material is counted as 56,045. That is, the resolution per inch is 600 dpi (dot per inch (= 25.4 mm)). Since the size of the recording material of LETTER size is 216 (mm) × 279 (mm), the number of print pixels is (600 dpi × 216 mm × 279 mm) / (25.4 mm × 25.4 mm) ≈56,045.

  For example, when printing on a recording material of LETTER size, the print rate when the number of print pixels acquired by the print pixel number counting unit 500 is 28,022 is as follows. That is, the printing rate is approximately 50% because the printing rate = the number of printing pixels / the total number of pixels of the entire recording material × 100 = 28,022 (pixels) / 56,045 (pixels) × 100≈50 (%).

  The toner consumption amount of the color cartridge at the time of multi-color monochrome printing is calculated from the printing rate obtained in this way, and the calculated toner consumption amount is converted into the life, whereby the toner life consumption rate in that case is obtained. Similarly, the lifetime of the developing roller 6 and the lifetime of the drum can be calculated from the number of rotations at the time of printing, respectively.

  By the way, in the present embodiment, as in the first embodiment, an image dot detection method that calculates the toner consumption based on the number of print pixels is employed. Therefore, the toner consumption cannot be calculated directly from the printing rate. Therefore, as will be described later, in this embodiment, the number of print pixels is acquired from the controller 650, and the consumption rate of the toner life is calculated. Although details will not be described in this embodiment, for example, the number of print pixels is calculated by obtaining information about the print rate, the size of the recording material, the resolution, and the like from the controller 650, and the consumption rate of the toner life is calculated. It is also possible.

In this embodiment, as a condition for permitting multi-color monochrome printing, in addition to the expressions (1) and (2), which are the conditional expressions for the life factors of the color cartridge described in the first embodiment, the wear rate of the life for each life factor. Satisfies the following expressions (4) and (5) as a third condition.
Consumption rate of toner life ≧ consumption rate of drum life (4)
Consumption rate of toner life ≧ Consumption rate of development life (5)

  The CPU 600 performs multi-color monochrome printing when the equations (4) and (5) are satisfied in all the color cartridges of yellow, magenta, and cyan in addition to the aforementioned equations (1) and (2). Judge that you can. If the CPU 600 determines that multi-color monochrome printing can be performed, the CPU 600 notifies the controller 650 to perform multi-color monochrome printing via the video interface 640. Further, even if the expressions (1) and (2) are satisfied, the CPU 600 determines that multi-color monochrome printing cannot be performed if either of the expressions (4) or (5) is not satisfied. Then, the controller 650 is notified to perform monochrome printing for monochrome printing. When the expressions (4) and (5) are satisfied, the consumption amount of the toner life becomes larger than the life of the developing roller 6 and the photosensitive drum 2, so that the difference in the life of each color cartridge is leveled. It will be.

  Next, a control sequence of “monochrome print setting based on the number of print pixels” will be described based on the flowchart of FIG. In S401, the CPU 600 acquires the number of print pixels. That is, the CPU 600 requests the controller 650 via the video interface 640 for information on the number of black print pixels on the recording material to be printed next. Based on the request from the CPU 600, the controller 650 calculates the number of black print pixels in the print data to be printed next, and notifies the CPU 600 via the video interface 640. The CPU 600 prints the print pixels on the recording material. Get the number.

  Next, in S402 to S408, the CPU 600 calculates the toner life, drum life, and development life wear rate of each of the yellow, magenta, and cyan color cartridges, and determines whether or not multicolor monochrome printing is possible for each cartridge. . In S <b> 402, the CPU 600 calculates the consumption rate of the toner life that is the ratio of the toner usage amount of the corresponding cartridge by dividing the number of print pixels acquired in S <b> 401 by the total number of print pixel counts. In S403, the CPU 600 divides the number of rotations of the photosensitive drum 2 and the developing roller 6 driven per recording material to be printed by the total number of rotations of the photosensitive drum 2 and the developing roller 6 to thereby obtain the drum life of the corresponding cartridge. And the developing life consumption rate is calculated.

  In S404, the CPU 600 compares the calculated toner life consumption rate with the drum life consumption rate, and determines whether the toner life consumption rate is equal to or higher than the drum life consumption rate. If the CPU 600 determines that the toner life consumption rate is greater than or equal to the drum life consumption rate, the CPU 600 proceeds to S405. If the CPU 600 determines that the toner life consumption rate is less than the drum life consumption rate, the CPU 600 proceeds to S407. In step S405, the CPU 600 compares the calculated toner life consumption rate with the development life consumption rate, and determines whether the toner life consumption rate is equal to or higher than the development life consumption rate. If the CPU 600 determines that the consumption rate of the toner life is greater than or equal to the consumption rate of the development life, the CPU 600 proceeds to S406. If the CPU 600 determines that the consumption rate of the toner life is less than the consumption rate of the development life, the processing proceeds to S407.

  In S <b> 406, the CPU 600 determines that multi-color monochrome printing using the corresponding cartridge is possible, and performs setting for permitting multi-color monochrome printing of the corresponding cartridge. In step S407, the CPU 600 determines that multicolor monochrome printing using the corresponding cartridge cannot be performed, and performs a setting for prohibiting the multicolor monochrome printing of the corresponding cartridge. In S408, the CPU 600 determines whether or not the processing from S402 to S407 has been completed for each of the yellow, magenta, and cyan color cartridges. If it is determined that the processing has not been completed, the CPU 600 returns to S402 and determines that the processing has been completed. If so, the process proceeds to S409.

  In step S409, the CPU 600 determines whether there is a cartridge set to prohibit multicolor monochrome printing in each of the yellow, magenta, and cyan color cartridges. The CPU 600 proceeds to S410 when there is a cartridge set to prohibit multicolor monochrome printing, and proceeds to S411 when there is no cartridge set to prohibit multicolor monochrome printing. In S410, the CPU 600 notifies the controller 650 via the video interface 640 to perform monochrome monochrome printing. In step S411, the CPU 600 notifies the controller 650 via the video interface 640 so as to perform multicolor monochrome printing, and finishes the monochrome printing setting process based on the printing rate.

  As described above, according to the present embodiment, the toner of the color cartridge can be effectively used and the consumption of the toner of the black cartridge can be suppressed. In particular, in this embodiment, it is possible to determine whether to perform monochrome monochrome printing or to perform monochrome monochrome printing before executing image formation. This makes it possible to print in black and white according to the printing rate of the image that is actually printed, effectively use the toner of the color cartridge except black, and further reduce the toner consumption of the black cartridge. become.

  In the first and second embodiments, the embodiment in which the CPU 600 of the image forming engine 620 determines whether to perform single-color monochrome printing or multicolor monochrome printing when performing monochrome printing has been described. In the third embodiment, a description will be given of an embodiment in which the controller 650 determines whether to perform single-color monochrome printing or multi-color monochrome printing when performing monochrome printing. In this embodiment, the same image forming apparatus as in the first embodiment is used, and the description of the image forming apparatus is omitted because it overlaps with the first embodiment.

[Control sequence for monochrome printing]
FIG. 5A is a flowchart illustrating a control sequence during printing of the image forming apparatus according to the present exemplary embodiment. A monochrome printing control sequence will be described with reference to the flowchart of FIG. In S501, when the CPU 600 receives an image formation start command from the controller 650 via the video interface 640, the CPU 600 performs pre-rotation processing necessary for image formation. When the pre-rotation process is completed, in S502, the CPU 600 performs monochrome print setting based on the life factor. The monochrome print setting based on the life factor is the process shown in the flowchart of FIG. 3B of the first embodiment, and the description thereof is omitted here. Subsequently, in S503, the CPU 600 determines whether or not multicolor monochrome printing is permitted in the processing of S502. If the CPU 600 determines that multi-color monochrome printing is permitted, the process proceeds to S504. If the CPU 600 determines that multi-color monochrome printing is not permitted, the process proceeds to S506.

  In step S <b> 504, the CPU 600 transmits life information for the controller 650 to perform monochrome print setting processing based on the number of print pixels to the controller 650 via the video interface 640. The life information transmitted from the CPU 600 to the controller 650 is the following information. That is, one is the cumulative number of printed pixel counts stored in the non-volatile memory 603, the cumulative rotational number of the developing roller 6 of the photosensitive drum 2 and the developing device 3, and the photosensitive drum driven per recording material. 2 and the number of rotations of the developing roller 6. The other is a printable pixel corresponding to the total number of revolutions corresponding to the useful life of the photosensitive drum 2 stored in the ROM 601, the total number of revolutions corresponding to the useful life of the developing roller 6, and the life of the toner. This is the total number of print pixel counts that is a number. In S505, the controller 650 performs monochrome print setting based on the number of print pixels (details will be described later).

  In step S <b> 506, the CPU 600 controls the above-described image forming operation and performs printing (image formation) on the recording material conveyed from the feeding cassette 30. In step S507, the CPU 600 determines whether the print job has ended. If it is determined that the print job has not ended, the process returns to step S502. If it is determined that the print job has ended, the process advances to step S508. In step S508, the CPU 600 performs post-rotation processing as post-processing of the image forming apparatus. When the post-rotation processing ends, the series of processing ends.

  Next, the “monochrome print setting of controller” process in S505 will be described in detail. FIG. 5B is a flowchart showing a control sequence of monochrome print setting processing based on the number of print pixels, which is executed by the controller 650. In the process shown in FIG. 5B, the controller 650 determines whether to perform multi-color monochrome printing or single-color monochrome printing based on the number of black (black) print pixels on the recording material. A video signal corresponding to the determined monochrome printing is generated. Note that the monochrome printing determination method based on the number of print pixels in FIG. 5B is the same as the determination method described in the second embodiment, and thus description of the determination method is omitted.

  First, in S601, the controller 650 calculates the number of black print pixels from print data transmitted from a host computer (not shown) or the like. Next, in S602 to S608, the controller 650 calculates the consumption rate of the toner life, the drum life, and the development life of the yellow, magenta, and cyan color cartridges based on the life information acquired from the CPU 600, and performs multicolor monochrome printing. Judge whether it is possible. In S <b> 602, the controller 650 divides the number of print pixels calculated in S <b> 601 by the total number of print pixel counts acquired from the CPU 600, thereby calculating a toner life consumption rate that is a ratio of toner usage of the corresponding cartridge. In step S <b> 603, the controller 650 divides the rotational speeds of the photosensitive drum 2 and the developing roller 6 that are driven per recording material acquired from the CPU 600 by the total rotational speed of the photosensitive drum 2 and the developing roller 6. Accordingly, the controller 650 calculates the consumption rate of the drum life and the development life of the corresponding cartridge.

  In step S604, the controller 650 compares the calculated toner life consumption rate with the drum life consumption rate, and determines whether the toner life consumption rate is equal to or higher than the drum life consumption rate. If the controller 650 determines that the toner life consumption rate is greater than or equal to the drum life consumption rate, the controller 650 proceeds to S605. If the controller 650 determines that the toner life consumption rate is less than the drum life consumption rate, the controller 650 proceeds to S607. In step S605, the controller 650 compares the calculated toner life consumption rate with the development life consumption rate, and determines whether the toner life consumption rate is equal to or higher than the development life consumption rate. If the controller 650 determines that the toner life consumption rate is greater than or equal to the development life consumption rate, the controller 650 proceeds to S606. If the controller 650 determines that the toner life consumption rate is less than the development life consumption rate, the controller 650 proceeds to S607.

  In step S606, the controller 650 determines that multi-color monochrome printing using the corresponding cartridge is possible, and performs setting to permit multi-color monochrome printing of the corresponding cartridge. In step S <b> 607, the controller 650 determines that double color monochrome printing using the corresponding cartridge is not possible, and performs setting to prohibit double color monochrome printing of the corresponding cartridge. In S608, the controller 650 determines whether or not the processing from S602 to S607 has been completed for each of the yellow, magenta, and cyan color cartridges. The controller 650 returns to S602 when determining that the processing from S602 to S607 has not been completed for each color cartridge, and proceeds to S609 when determining that the processing has been completed.

  In step S <b> 609, the controller 650 determines whether there is a cartridge set to prohibit multicolor monochrome printing in each of the yellow, magenta, and cyan color cartridges. The controller 650 proceeds to S610 if there is a cartridge set to prohibit multicolor monochrome printing, and proceeds to S612 if there is no cartridge set to prohibit multicolor monochrome printing. In step S610, the controller 650 notifies the CPU 600 that monochrome printing is to be performed via the video interface 640. In step S611, the controller 650 generates a video signal for monochrome monochrome printing and outputs the video signal to the CPU 600. In step S612, the controller 650 notifies the CPU 600 that multi-color monochrome printing is to be performed via the video interface 640. In step S613, the controller 650 generates a video signal for multicolor monochrome printing, outputs the video signal to the CPU 600, and ends the monochrome printing setting process based on the printing rate. In the flowchart of FIG. 5B showing the processing content of S505 in FIG. 5A, the controller 650 performs both single-color monochrome printing (S610) and multi-color monochrome printing (S612). Also, the CPU 600 is notified. Since the process of S505 is executed only when multi-color monochrome printing is possible, the process of S612 in FIG. 5B may be omitted. Thereby, the frequency | count of communication between the controller 650 and CPU600 can be reduced.

  As described above, according to the present embodiment, the toner of the color cartridge can be effectively used and the consumption of the toner of the black cartridge can be suppressed. In particular, according to the present embodiment, the controller can determine whether to perform monochrome monochrome printing or to perform monochrome monochrome printing while converting an image. Therefore, it is possible to select an efficient monochrome printing unit, and it is possible to effectively use the toner of the color cartridge and suppress the consumption of the toner of the black cartridge. Furthermore, in the present embodiment, the number of communications between the CPU and the controller can be reduced compared to the second embodiment.

  The first to third embodiments described above can be applied to a configuration in which the photosensitive drum of the color cartridge and the developing device can be separated from each other, a configuration in which the photosensitive drum and the intermediate transfer belt can be separated, and a configuration in which the photosensitive drum and the intermediate transfer belt can be separated from each other. it can. In particular, in a color cartridge configured such that the photosensitive drum and the intermediate transfer belt cannot be separated from each other, the life of the drum is consumed even during monochrome monochrome printing in which toner is not consumed. Therefore, by applying the first to third embodiments, it is possible to effectively use the toner of the color cartridge and suppress the consumption of the toner of the black cartridge. The above-described first to third embodiments can be applied to a color cartridge that can be replenished when the toner runs out. When the toner runs out and is replenished, the toner amount is the same as that of a new product. Therefore, by setting the print pixel count accumulated value stored in the nonvolatile memory to 100 (%), the toner life of the corresponding color cartridge can be set to a new state.

600 CPU
631 cartridge (process cartridge)

Claims (14)

A plurality of cartridges for storing different color toners;
Control capable of switching between a first mode for forming a black image using only a cartridge containing black toner and a second mode for forming a black image using the plurality of cartridges. With means,
In the case where a black image is formed on the recording material, the control unit is configured to select one of the first mode and the second mode based on the lifetime of each of the plurality of cartridges excluding the cartridge containing the black toner. An image forming apparatus characterized by switching to The cartridge is a process cartridge having a toner carrier for carrying and transporting the toner and an image carrier on which a toner image is formed by the toner conveyed by the toner carrier, and the life of the process cartridge is , Determined by any one of the lifetime of the toner, the lifetime of the image carrier, and the lifetime of the toner carrier,
2. The image according to claim 1, wherein the life of the toner, the life of the image carrier, and the life of the toner carrier are represented by a ratio that makes the start of use of the process cartridge 100%. Forming equipment.   The image forming apparatus according to claim 2, wherein the life of the toner is determined based on the number of print pixels from the start of use of the process cartridge. The image carrier is a photosensitive drum;
The image forming apparatus according to claim 2, wherein the life of the photosensitive drum is determined based on a rotational speed from the start of use of the process cartridge. The toner carrier is a developing roller;
The image forming apparatus according to claim 2, wherein the life of the developing roller is determined based on a rotational speed from the start of use of the process cartridge.   In all the process cartridges except the process cartridge containing the black toner, the control means has a life of the toner carrier larger than that of the image carrier, and from the life of the toner, the image carrier 3. The image forming apparatus according to claim 2, wherein when the result of reducing the life of the body is a predetermined value or more, the mode is switched to the second mode.   In at least one of the process cartridges excluding the process cartridge containing the black toner, the control unit is configured such that the life of the toner carrier is equal to or less than the life of the image carrier, or the life of the toner carrier. 2 is longer than the life of the image carrier, but when the result of subtracting the life of the image carrier from the life of the toner is less than a predetermined value, the mode is switched to the first mode. 6. The image forming apparatus according to 6. Receiving means for receiving image data;
The control means, based on the number of black print pixels in the image data notified from the receiving means in all the process cartridges except the process cartridge containing the black toner, And the lifetime of the image carrier consumed by image formation per recording material and the consumption rate of the toner carrier are calculated, and the consumption rate of the toner lifetime is the lifetime of the image carrier. The mode is switched to the second mode when the consumption rate of the toner is equal to or greater than the consumption rate of the toner and the consumption rate of the toner life is equal to or greater than the consumption rate of the toner carrier. Image forming apparatus.   In at least one of the process cartridges excluding the process cartridge containing the black toner, the control means is configured such that when the consumption rate of the toner life is less than the wear rate of the image carrier, The image forming apparatus according to claim 8, wherein when the lifetime consumption rate is less than the lifetime consumption rate of the toner carrier, the mode is switched to the first mode. Receiving means for receiving image data and generating an image signal based on the image data;
The receiving means includes, in all the process cartridges except for the process cartridge containing the black toner, the number of black print pixels calculated from the received image data, the toner included in the control means, the image carrier, And the lifetime information of the toner carrier, the consumption rate of the toner lifetime, the lifetime of the image carrier consumed by the image formation per recording material, and the lifetime of the toner carrier. The toner life consumption rate is equal to or higher than the image carrier life rate, and the toner life consumption rate is equal to or higher than the toner life rate. The image forming apparatus according to claim 6, wherein an image signal for image formation in the second mode is generated.   In the at least one of the process cartridges excluding the process cartridge containing the black toner, the receiving unit is configured such that when the consumption rate of the toner life is less than the wear rate of the image carrier, 11. The image formation according to claim 10, wherein an image signal for image formation in the first mode is generated when a life wear rate is less than a life wear rate of the toner carrier. apparatus.   12. The second mode according to claim 2, wherein the second mode forms a black image using the plurality of process cartridges excluding the process cartridge containing the black toner. The image forming apparatus described.   The image carrier is a photosensitive drum, the toner carrier is a developing roller, and the developing roller can be brought into contact with or separated from the photosensitive drum. The developing roller contacts the photosensitive drum in a process cartridge containing toner, and the developing roller is separated from the photosensitive drum in the plurality of process cartridges except the process cartridge containing black toner, In the second mode, in the process cartridge containing the black toner, the developing roller is separated from the photosensitive drum, and in the plurality of process cartridges excluding the process cartridge containing the black toner, the developing roller is 13. The photosensitive drum according to claim 12, wherein the photosensitive drum comes into contact with the photosensitive drum. The image forming apparatus. The image carrier is a photosensitive drum;
An intermediate transfer member to which a toner image formed on the photosensitive drum is transferred;
The image forming apparatus according to claim 12, wherein the photosensitive drums of all the process cartridges are in contact with the intermediate transfer member.

Images