JP2016122102A - Image forming apparatus, speed control method, and speed control program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that can suppress a reduction in image quality.SOLUTION: A control part 100, when performing monochrome printing, performs deceleration control of rotating a developing roller 7K at a high speed and rotating developing rollers 7Y, 7M, and 7C at a low speed. The control part 100 performs acceleration control of rotating the developing roller 7K and the developing rollers 7Y, 7M, and 7C at a high speed on the basis of at least the number of rotations of the developing rollers 7Y, 7M, and 7C in the deceleration control and a time during which the deceleration control has been performed.SELECTED DRAWING: Figure 7

Description

  The present invention relates to an image forming apparatus, a speed control method, and a speed control program.

  As an example of an image forming apparatus using an electrophotographic method, a photosensitive drum corresponding to cyan, yellow, magenta, and black toners, a toner storage unit that stores toner of each color, and a toner in the toner storage unit A developing roller that supplies a corresponding electrostatic latent image on a photosensitive drum is known.

  For example, the image forming apparatus described in Patent Literature 1 detects yellow, magenta, cyan, and black coverage in an image based on image data. When the detected coverage of each color is lower than the predetermined coverage, the rotation speed of the developing roller corresponding to the color with the low coverage is reduced.

JP 2010-2666 A

  In the above-described image forming apparatus, for example, when continuously printing images in which the coverage of each color is lower than the predetermined coverage, the developing roller corresponding to the color with the low coverage continues to rotate while being decelerated.

  However, the experiment of the applicant of the present application shows that if the developing roller continues to rotate while being decelerated, the circulation of the toner in the toner accommodating portion is worse than when the developing roller continues to rotate without being decelerated. It has been revealed by.

  Specifically, if the developing roller continues to rotate while being decelerated, the toner around the developing roller does not circulate throughout the toner storage unit. As a result, compared to the case where the toner around the developing roller is circulated throughout the entire toner container, the toner around the developing roller is more likely to be deteriorated because it is frequently subjected to friction by the rotating developing roller.

  For this reason, the image forming apparatus described in Patent Document 1 has a problem in that the developing roller continues to rotate in a decelerated state, thereby causing fogging and the like due to the above-described toner deterioration, thereby reducing the image quality.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus capable of suppressing deterioration in image quality.

  In order to achieve the above object, an image forming apparatus according to the present invention includes a first photosensitive member corresponding to a first color toner and a second color corresponding to a second color toner different from the first color. First development for developing the electrostatic latent image on the first photosensitive member by supplying the first photosensitive member and the first color toner stored in the first storage unit storing the first color toner to the first photosensitive member. And a second developing roller for developing the electrostatic latent image on the second photoconductor by supplying the second color toner contained in the roller and the second containing portion containing the second color toner to the second photoconductor And a control unit. The control unit rotates the second developing roller when the first developing roller and the second developing roller develop the electrostatic latent images on the first photosensitive member and the second photosensitive member. Rotation control, the first developing roller develops the electrostatic latent image on the first photosensitive member, and the second developing roller develops the electrostatic latent image on the second photosensitive member. Deceleration based on at least one of the deceleration control for rotating the second developing roller at a speed slower than the speed in the rotation control and the rotation speed of the second developing roller and the time for executing the deceleration control in the deceleration control when not developing. And a speed increase control for rotating the second developing roller at a speed faster than the speed in the control.

  In the image forming apparatus, the control unit counts the number of rotations of the second developing roller in the deceleration control, and executes speed increase control when the counted number of rotations of the second developing roller is equal to or higher than the first predetermined number of rotations. It may be a configuration.

  In the image forming apparatus, the control unit increases the speed increase control when the speed increase control is continuously executed for the first predetermined time or when the rotation speed of the second developing roller in the speed increase control is equal to or higher than the second predetermined speed. The structure which stops speed control may be sufficient.

  The image forming apparatus includes a toner amount detection unit that detects the amount of the second color toner stored in the second storage unit, and the control unit detects the amount of the second color toner detected by the toner amount detection unit. When the amount is equal to or smaller than the predetermined amount, the first predetermined rotational speed may be reduced.

  In the image forming apparatus, the control unit may measure the time for executing the deceleration control, and may execute the speed increase control when the measured execution time is equal to or longer than the second predetermined time.

  In the image forming apparatus, the control unit increases the speed increase control when the speed increase control is continuously executed for a third predetermined time or when the rotation speed of the second developing roller in the speed increase control is equal to or higher than the third predetermined speed. The structure which stops speed control may be sufficient.

  The image forming apparatus includes a toner amount detection unit that detects the amount of the second color toner stored in the second storage unit, and the control unit detects the amount of the second color toner detected by the toner amount detection unit. When the amount is equal to or less than the predetermined amount, the second predetermined time may be reduced.

  In the image forming apparatus, the control unit may execute speed increase control when the first photosensitive member and the second photosensitive member are positioned between two recording sheets that are continuously conveyed. Good.

  The invention disclosed in this specification includes various devices such as a control device, a control method, a printing device, a printing method, a computer program for realizing the functions of these methods or devices, and a recording medium on which the computer program is recorded. It is realizable with the aspect of.

  According to the present invention, the control unit rotates the second developing roller at a speed higher than the speed in the deceleration control based on at least one of the rotation speed of the second developing roller in the deceleration control and the time when the deceleration control is executed. Acceleration control is executed. Thereby, compared with the case where the control unit does not execute the speed increase control, the circulation of the toner around the second developing roller accommodated in the second accommodating unit can be improved, so that the deterioration of the image quality is suppressed. be able to.

1 is a schematic cross-sectional view illustrating a configuration of an image forming apparatus according to an embodiment. It is a block diagram which shows the electric constitution of the control part which concerns on this embodiment. It is a flowchart which shows the procedure of a printing process. This is a rotation processing subroutine. This is a subroutine for deceleration processing. It is a flowchart which shows the procedure of a low speed rotation monitoring process. This is a subroutine for acceleration processing. It is a flowchart which shows the procedure of a reset process.

  Embodiments will be described with reference to the drawings. After describing the overall configuration of the image forming apparatus 1, features of the present invention will be described in detail.

  As shown in FIG. 1, the image forming apparatus 1 includes an image forming unit 30, a paper feeding unit 9, and a control unit 100 in the apparatus main body 2.

  The image forming unit 30 includes a process unit 3 and an exposure device 4. The process unit 3 is provided corresponding to each color of black, which is an example of the first color, yellow, which is an example of the second color, magenta, and cyan, and yellow, magenta in the paper conveyance direction as an example of the recording sheet. , Cyan and black. The exposure device 4 is disposed above the process unit 3 and emits a laser beam corresponding to each color.

  Each process unit 3 includes a photoreceptor 5, a charger 6, a cleaning roller 8, a transfer roller 13 as an example of a transfer unit, and a cartridge 50. The cartridge 50 is formed in a substantially box shape extending in the left-right direction, and is detachable from the apparatus main body 2. The cartridge 50 is configured to store the toner in the storage unit 20, supply the toner in the storage unit 20 to the photoconductor 5, develop the electrostatic latent image on the photoconductor 5, and supply the toner to the development roller 7 A supply roller 60 to be supplied is provided. In the present embodiment, cartridges 50Y, 50M, 50C, and 50K are arranged in the order of yellow, magenta, cyan, and black in the paper transport direction.

  The cartridge 50K is provided with a first storage portion 20K that stores black toner. The cartridges 50Y, 50M, and 50C are provided with second storage portions 20Y, 20M, and 20C that store yellow, magenta, and cyan toners.

  The apparatus main body 2 is provided with a toner sensor 150 as an example of a toner amount detection unit. The toner sensor 150 is a known sensor that is provided corresponding to each cartridge 50 and detects the amount of toner stored in the storage units 20K, 20Y, 20M, and 20C.

  The toner sensor 150 is housed in each housing portion 20 by transmitting light to the housing portion 20 through one transmission window provided in each cartridge 50 and receiving light emitted from the other transmission window. The amount of toner is detected, and the detection result is output to the control unit 100.

  In each process unit 3, the surface of the photoconductor 5 is uniformly positively charged by the charger 6 along with the rotation of the photoconductor 5, and then selectively exposed by the laser beam from the exposure device 4. As a result, charges are selectively removed from the surface of the photoreceptor 5, and an electrostatic latent image is formed on the surface of the photoreceptor 5.

  Next, the developing roller 7 supplies toner to the electrostatic latent image formed on the surface of the photoreceptor 5 and develops the electrostatic latent image on the photoreceptor. In the present specification and drawings, when specifying the process unit 3, the photoreceptor 5, the developing roller 7, and the storage unit 20 corresponding to each color, K, corresponding to each of black, yellow, magenta, and cyan, , Y, M, C symbols.

  A paper feeding unit 9 that accommodates paper is disposed below the apparatus main body 2. The paper stored in the paper supply unit 9 is transported onto the transport belt 10 by various rollers.

  The conveyor belt 10 is stretched between a pair of driving rollers 11 and a driven roller 12, and includes a photoconductor 5K as an example of a first photoconductor, and photoconductors 5Y and 5M as an example of a second photoconductor. The four photoconductors 5 made of 5C are arranged to face each other from below. A transfer roller 13 is disposed at each position facing each photoconductor 5 across the upper portion of the conveyance belt 10.

  Further, a developing roller 7K as an example of a first developing roller that develops the electrostatic latent image on the photoconductor 5K and the photoconductors 5Y, 5M, and 5C are provided corresponding to the photoconductors 5Y, 5M, and 5C. Developing rollers 7Y, 7M, and 7C as an example of a second developing roller that develops the electrostatic latent image are disposed.

  The sheet transported on the transport belt 10 sequentially passes between the transport belt 10 and each photosensitive drum 5 as the transport belt 10 travels. Then, the toner image of each color carried by each photoconductor 5 is transferred to the paper by the transfer bias applied to each transfer roller 13, and a toner image is formed on the paper. Note that the image forming unit 30 performs monochrome printing that forms a black toner image on a sheet and color printing that forms a toner image of each color on a sheet.

  The transferred toner image is heat-fixed on the sheet by the fixing unit 14 disposed on the downstream side in the sheet conveying direction with respect to the conveying belt 10. The sheet on which the toner image is fixed is discharged to a discharge tray 15 disposed on the upper surface of the apparatus main body 2 by various rollers.

  A belt cleaner 16 is disposed between the paper supply unit 9 and the conveyor belt 10, and the belt cleaner 16 removes toner and paper dust attached to the surface of the conveyor belt 10. A cleaning roller 8 is disposed corresponding to each photoconductor 5, and the toner remaining on the surface of each photoconductor 5 after the transfer of the toner image is removed from the surface of the photoconductor 5 by the cleaning roller 8. .

  Next, the electrical configuration of the control unit 100 will be described. As shown in FIG. 2, the control unit 100 includes a CPU 101, a ROM 102, a RAM 103, and an NVRAM 104, and is electrically connected mainly to the developing roller drive motor 70 and the toner sensor 150.

  The ROM 102 stores various control programs and image processing programs for controlling the image forming apparatus 1, various settings, initial values, and the like.

  The RAM 103 is used as a work area from which various control programs are read, or as a storage area for temporarily storing print data such as image data sent via various interfaces.

  The NVRAM 104 is a non-volatile storage unit, and is used as a storage area for storing various settings, print data, and the like.

  The CPU 101 executes arithmetic operations for realizing various functions such as a printing function in the image forming apparatus 1 and is the center of control. The CPU 101 controls each component of the image forming apparatus 1 while storing the processing result in the RAM 103 or the NVRAM 104 according to the control program read from the ROM 102.

  The amount of toner in each container 20 detected by each toner sensor 150 described above is stored in the NVRAM 34.

  The developing roller driving motor 70 is a driving source for driving the developing roller 7 corresponding to each color. The developing roller driving motor 70 includes a monochrome driving motor 71 that drives a developing roller 7K as an example of a first developing roller, and a color driving motor 72 that drives developing rollers 7Y, 7M, and 7C as examples of a second developing roller. Consists of The monochrome drive motor 71 and the color drive motor 72 rotate each developing roller 7 under the control of the control unit 100.

  In the present embodiment, the monochrome driving motor 71 and the color driving motor 72 rotate each developing roller. However, the present invention is not limited to this, and a configuration in which one driving source rotates each developing roller 7, The drive source corresponding to the developing roller 7 may be configured to rotate each developing roller 7 individually.

  Next, the control performed by the control unit 100 will be described in detail with reference to FIGS. As shown in FIG. 3, the control unit 100 executes a printing process for forming an image on a sheet. The control unit 100 determines whether or not print data has been received (S50). If the control unit 100 determines that print data has been received (S50: YES), the control unit 100 determines whether or not to perform color printing based on the print data. (S55). In this specification, color printing refers to color based on print data on a sheet by developing the electrostatic latent image on the photoreceptor 5 corresponding to the developing roller 7K and the developing rollers 7Y, 7M, and 7C, respectively. To form an image.

  In S55, when the control unit 100 determines that color printing should be executed (S55: YES), the control unit 100 executes a rotation process described later (S60). The rotation process is a process executed by the control unit 100 to form a color image on a sheet.

  As shown in FIG. 4, when performing color printing, in the rotation process, the control unit 100 executes rotation control for rotating the developing roller 7K and the developing rollers 7Y, 7M, and 7C at a predetermined rotation speed (S125). ). Hereinafter, the rotation speeds of the developing rollers 7K, 7Y, 7M, and 7C in the rotation control are simply referred to as high speed. In the present embodiment, the control unit 100 rotates the developing rollers 7K, 7Y, 7M, and 7C at the same rotational speed in the rotation control, but is not limited to this, and the developing rollers 7K, 7Y, 7M, and 7C are not limited thereto. May be rotated at different rotational speeds.

  Here, the control unit 100 counts the number of rotations of the developing rollers 7Y, 7M, and 7C that rotate at high speed in accordance with the rotation of the developing rollers 7Y, 7M, and 7C, and accumulates the count values. The cumulative number of rotations of the developing rollers 7Y, 7M and 7C is counted. In the present specification, hereinafter, the cumulative rotational speed of the developing rollers 7Y, 7M and 7C rotating at high speed is referred to as high-speed cumulative rotational speed.

  Next, the control unit 100 causes the image forming unit 30 to form a color image based on the print data on the sheet (S130), and determines whether there is next print data that is different from the print data. (S135).

  In S135, when the control unit 100 determines that there is the next print data (S135: YES), the control unit 100 determines whether to perform color printing based on the next print data (S140).

  In S140, when the control unit 100 determines that color printing should be executed (S140: YES), the control unit 100 proceeds to S130 again, and causes the image forming unit 30 to form a color image based on the next print data on the sheet.

  In S140, when the control unit 100 determines that color printing should not be executed, that is, monochrome printing should be executed (S140: NO), a deceleration process described later is executed (S145), and then a rotation process is performed. Exit.

  In the present specification, monochrome printing refers to the development of the electrostatic latent image on the photosensitive member 5 to which the developing roller 7K of the developing rollers 7 corresponds, and the developing rollers 7Y, 7M, and 7C respectively correspond to the developing roller 7K. This means that a monochrome image based on print data is formed on a sheet under the condition that the electrostatic latent image on the photoreceptor 5 is not developed.

  In S135, when the control unit 100 determines that there is no next print data (S135: NO), it stops the rotation control, in other words, stops the rotation of the developing roller 7K and the developing rollers 7Y, 7M, and 7C. (S150), the rotation process ends.

  In S145, the control unit 100 executes a deceleration process, which will be described later, in order to reduce the cumulative number of rotations of the developing rollers 7Y, 7M, and 7C. Specifically, when performing monochrome printing, the developing rollers 7Y, 7M, and 7C do not perform a developing operation, so that the developing rollers 7Y, 7M, and 7C are rotated at a high speed as in the case of performing color printing. There is no need to let them.

  In the case of executing monochrome printing, a configuration in which the developing rollers 7Y, 7M, and 7C are separated from the corresponding photoreceptors 5 and rotation of the developing roller 7 is stopped is conventionally known. In this configuration, monochrome printing is performed. Since the separation operation of the developing roller 7 is accompanied when switching between color printing and color printing, the throughput of the image forming apparatus 1 may be reduced.

  Therefore, in the present embodiment, the control unit 100 reduces the rotational speed of the developing rollers 7Y, 7M, and 7C in the deceleration process as compared with the case where color printing is performed, so that the cumulative rotational speed of the developing roller 7 is increased. Thus, toner deterioration due to an increase in the cumulative number of rotations of the developing roller 7 is suppressed. The deceleration process will be described in detail below.

  As shown in FIG. 5, in the case of executing monochrome printing, in the deceleration process, the control unit 100 rotates the developing roller 7K at a high speed and rotates the developing rollers 7Y, 7M, and 7C to a quarter of the high speed. The deceleration control to rotate is executed (S100).

  In the present embodiment, the control unit 100 rotates the developing rollers 7Y, 7M, and 7C at a rotational speed that is 1/4 of the rotational speed of the developing roller 7K in the deceleration control. However, the present invention is not limited to this. The developing rollers 7Y, 7M, and 7C may be rotated at an arbitrary rotational speed that is slower than the rotational speed of the developing roller 7K. In the following, the rotation speed that is 1/4 of the high speed is simply referred to as low speed.

  Here, in S100, the control unit 100 counts the number of rotations of the developing rollers 7Y, 7M, and 7C that rotate at a low speed in response to the rotation of the developing rollers 7Y, 7M, and 7C. The number of rotations of the developing rollers 7Y, 7M and 7C in the control is counted. Then, the cumulative number of rotations of the developing rollers 7Y, 7M, and 7C is counted by integrating the count values. In the present specification, hereinafter, the cumulative rotational speed of the developing rollers 7Y, 7M, and 7C in the deceleration control is referred to as a low-speed cumulative rotational speed.

  Next, the control unit 100 causes the image forming unit 30 to form a monochrome image based on the print data on the paper (S105), and determines whether there is next print data that is different from the print data. (S110). When the control unit 100 determines that there is the next print data (S110: YES), the control unit 100 determines whether or not monochrome printing should be executed based on the next print data (S115).

  When the control unit 100 determines that monochrome printing should be executed (S115: YES), the control unit 100 proceeds to S105 again, and causes the image forming unit 30 to form a monochrome image based on the next print data on a sheet.

  In S115, when the control unit 100 determines that monochrome printing should not be performed, that is, color printing should be performed (S115: NO), rotation processing is performed (S120), and then deceleration processing is performed. Exit. In S110, when the control unit 100 determines that there is no next print data (S110: NO), it stops the deceleration control, in other words, stops the rotation of the developing roller 7K and the developing rollers 7Y, 7M, and 7C. (S121), the deceleration process is terminated.

  Here, in the present embodiment, the control unit 100 executes a deceleration process in order to reduce the cumulative number of rotations of the developing roller 7 when performing monochrome printing. Therefore, for example, when monochrome printing is continuously performed, the state where the control unit 100 performs the deceleration control continues, so that the developing rollers 7Y, 7M, and 7C continue to rotate at a low speed.

  As described above, when the developing rollers 7Y, 7M, and 7C rotate at a low speed, the developing rollers 7Y, 7M, and 20M in the second housing portions 20Y, 20M, and 20C are compared with a case where the developing rollers 7Y, 7M, and 7C rotate at a high speed. And the vortex flow of toner generated around 7C is weakened. As described above, when the spiral flow of the toner becomes weak, the toner stays around the developing roller 7 in the second storage portions 20Y, 20M, and 20C, and the toner circulates in the second storage portions 20Y, 20M, and 20C. It becomes difficult to be done.

  Therefore, when the developing rollers 7Y, 7M, and 7C continue to rotate at a low speed, the periphery of the developing rollers 7Y, 7M, and 7C in the second storage portions 20Y, 20M, and 20C is compared to a case where the developing roller 7 continues to rotate at a high speed. The toner circulation becomes worse. As a result, compared to the case where the toner continues to rotate at a high speed, the toner around each developing roller 7 is frequently subjected to friction by the rotating developing roller 7 and the toner is likely to deteriorate. Due to the deterioration of the toner, the image quality of the image formed on the paper may be lowered.

  Therefore, in the present embodiment, in consideration of the above-described problem, the control unit 100 executes a speed increasing process to be described later in order to suppress deterioration in image quality. The control unit 100 executes the low speed rotation monitoring process in order to determine whether or not the speed increasing process should be executed. The control unit 100 executes the low speed rotation monitoring process at a predetermined time interval.

  As shown in FIG. 6, in the low-speed rotation monitoring process, the control unit 100 determines whether or not the low-speed cumulative rotation speed is equal to or higher than the first predetermined rotation speed (S350). If it is determined that the rotation speed is equal to or greater than the predetermined number of revolutions (S350: YES), a speed increasing process is executed (S355). An arbitrary value may be applied to the first predetermined rotation speed.

  In S350, if control unit 100 determines that the low-speed cumulative rotational speed is not equal to or higher than the first predetermined rotational speed (S350: NO), the low-speed rotational monitoring process is terminated. Here, the speed increasing process executed by the control unit 100 in S355 will be described in detail below.

  As shown in FIG. 7, in the speed increasing process, the control unit 100 determines whether it is time to change the rotation speed of the developing rollers 7Y, 7M, and 7C (S200), and determines that it is time to change. Then (S200: YES), speed increase control for rotating the developing roller 7K and the developing rollers 7Y, 7M and 7C at high speed is executed (S205).

  The timing that can be changed in this specification refers to, for example, when monochrome printing is performed, when each photoconductor 5 is positioned between two sheets of paper that are continuously conveyed, or when monochrome printing is performed. This is when each photoconductor 5 does not come into contact with the paper, such as when not being.

  As described above, the control unit 100 executes the speed increase control when the low-speed cumulative rotational speed is equal to or higher than the first predetermined rotational speed. As described above, when the low-speed cumulative rotational speed is equal to or higher than the first predetermined rotational speed, in other words, when the circulation property of the toner around the developing rollers 7Y, 7M, and 7C in the second storage portions 20Y, 20M, and 20C is deteriorated. In addition, since the developing rollers 7Y, 7M, and 7C rotate at a high speed, the circulation characteristics of the toner around the developing rollers 7Y, 7M, and 7C in the second storage portions 20Y, 20M, and 20C can be compared to when the speed increase control is not performed. Will be better. Thereby, it is possible to suppress a decrease in image quality due to toner deterioration.

  As described above, the control unit 100 rotates the developing rollers 7Y, 7M, and 7C at a high speed in the rotation control shown in S125 of FIG. This is to simplify the control executed by the control unit 100 by making the rotation speed of each developing roller 7 in the speed increase control common to the rotation speed of each developing roller 7 in the rotation control. Therefore, by executing the rotation control, an effect equivalent to the speed increase control can be obtained with respect to the circulation of the toner around the developing rollers 7Y, 7M, and 7C in the second storage units 20Y, 20M, and 20C.

  Here, based on the detection result output from the toner sensor 150, the control unit 100 determines the first predetermined rotation speed when the amount of yellow, magenta, and cyan toner stored in the storage unit 20 is equal to or less than a predetermined amount. Make it smaller. This is because a phenomenon in which the circulation property of the toner changes according to the amount of toner stored in the storage unit 20 is taken into consideration.

  Specifically, as the amount of toner in the storage unit 20 decreases, the toner around the developing rollers 7Y, 7M, and 7C in the second storage units 20Y, 20M, and 20C hardly circulates in the storage unit 20. For this reason, the smaller the amount of toner in the storage unit 20, the easier it is for image quality degradation to occur due to toner degradation.

  As described above, the control unit 100 executes the speed increase control when the low-speed cumulative rotation speed is equal to or higher than the first predetermined rotation speed. Therefore, when the first predetermined rotation speed decreases, the speed increase control execution frequency increases. Become. Therefore, in this embodiment, when the amount of yellow, magenta, and cyan toners is equal to or less than a predetermined amount, the control unit 100 reduces the amount of toner in the storage unit 20 by reducing the first predetermined rotation speed. In other words, when the image quality is likely to be deteriorated due to the deterioration of the toner, the execution speed of the acceleration control is increased.

  Thereby, as compared with the case where the control unit 100 does not reduce the first predetermined rotation number as described above, it is possible to further suppress a decrease in image quality due to toner deterioration.

  Here, the control unit 100 executes speed increase control when the low-speed cumulative rotation speed is equal to or higher than the first predetermined rotation speed. In the speed increase control, the developing rollers 7Y, 7M, and 7C rotate at a high speed. Considering the cumulative number of rotations of the developing roller 7, it is desirable that the control unit 100 does not execute speed increase control more than necessary. Therefore, in the present embodiment, in consideration of the above-described circumstances, the control unit 100 executes a reset process, which will be described later, in order to reduce the cumulative number of rotations of the developing roller 7.

  As shown in FIG. 8, in the reset process, the control unit 100 determines whether or not the high-speed cumulative rotational speed is equal to or higher than the second predetermined rotational speed (S300), and the high-speed cumulative rotational speed is the second predetermined rotational speed. If it is determined that this is the case (S300: YES), after resetting the low-speed cumulative rotational speed (S305), the reset process is terminated. An arbitrary value may be applied to the second predetermined rotational speed, and resetting the low-speed cumulative rotational speed is to set the count value integrated by the control unit 100 to zero.

  In S300, when the control unit 100 determines that the high-speed accumulated rotational speed is not equal to or higher than the second predetermined rotational speed (S300: NO), the reset process is terminated. The control unit 100 executes the reset process at predetermined time intervals.

  As illustrated in FIG. 7, when the control unit 100 determines in S200 that it is not the timing at which the rotation speeds of the developing rollers 7Y, 7M, and 7C can be changed (S200: NO), the control unit 100 proceeds to S200 again.

  After S205, the control unit 100 determines whether or not the low-speed cumulative rotational speed has been reset (S210), and determines that the low-speed cumulative rotational speed has not been reset (S210: NO), the process proceeds to S210 again.

  In S210, when the control unit 100 determines that the low-speed cumulative rotational speed has been reset (S210: YES), the control unit 100 determines whether it is time to change the rotational speed of the developing rollers 7Y, 7M, and 7C (S220). If it is determined that the timing can be changed (S220: YES), the acceleration control is stopped, in other words, the developing roller 7K is rotated at a high speed, and the developing rollers 7Y, 7M, and 7C are rotated at a low speed (S225). The speed increasing process is terminated.

  As described above, the control unit 100 executes the speed increase control until it is determined that the low-speed cumulative rotational speed has been reset. In the reset process shown in FIG. If it is determined that the speed is equal to or higher than the rotation speed, the low-speed cumulative rotation speed is reset. Therefore, when the low-speed cumulative rotational speed is reset, in other words, when the high-speed cumulative rotational speed is equal to or higher than the second predetermined rotational speed, the control unit 100 determines that the high-speed cumulative rotational speed is the second predetermined rotational speed. If this is the case, it can be said that the acceleration control is stopped.

  As shown in FIG. 7, when the control unit 100 determines in S220 that it is not the timing at which the rotation speeds of the developing rollers 7Y, 7M, and 7C can be changed (S220: NO), the control unit 100 proceeds to S220 again.

  In the present embodiment, the control unit 100 stops the speed increase control when the high-speed cumulative rotation number is equal to or higher than the second predetermined rotation speed, but is not limited to this, and the control unit 100 performs the speed increase control. A configuration may be adopted in which the time measurement is measured and the speed increase control is stopped when it is determined that the speed increase control is continuously executed for the first predetermined time or more based on the measured time. In addition, you may apply arbitrary time to the said 1st predetermined time.

  As illustrated in FIG. 3, the control unit 100 ends the printing process after executing the rotation process in S <b> 60. In S55, when the control unit 100 determines that color printing should not be performed, that is, monochrome printing should be performed (S55: NO), the deceleration process is performed (S65), and then the printing process is performed. finish. If the control unit 100 determines that the print data has not been received (S50: NO), the printing process is terminated.

  In the present embodiment, the control unit 100 is configured to execute the speed increase control when the low-speed cumulative rotation number is equal to or higher than the first predetermined rotation speed. However, the control unit 100 is not limited to this, and the control unit 100 performs the deceleration control. The configuration may be such that the execution time is measured, and when the measured execution time is equal to or longer than the second predetermined time, the speed increase control is executed.

  Further, in addition to the configuration, the control unit 100 determines that the first, yellow, magenta, and cyan toners stored in the storage unit 20 are less than or equal to a predetermined amount based on the detection result output from the toner sensor 150. 2 When the predetermined time is shortened and the speed increasing control is executed, and the speed increasing control is continuously executed for the third predetermined time or more based on the measured time, or the high-speed cumulative rotational speed is the third predetermined speed. When it becomes more than the rotation speed, the speed increase control may be stopped.

  As described above, when the time for executing the deceleration control, in other words, the time for which the developing rollers 7Y, 7M, and 7C rotate at a low speed is equal to or longer than the second predetermined time, the control unit 100 controls the developing rollers 7Y, 7M, and 7C. Since the rotation is performed at a high speed, the circulation of toner around the developing rollers 7Y, 7M, and 7C in the second storage units 20Y, 20M, and 20C is improved as compared with the case where the speed increase control is not executed. Thereby, it is possible to suppress a decrease in image quality due to toner deterioration.

  Further, the control unit 100, when the amount of yellow, magenta, and cyan toner stored in the storage unit 20 is equal to or less than a predetermined amount, in other words, when the image quality is likely to deteriorate due to toner deterioration. By reducing the second predetermined time, the execution frequency of the speed increase control is increased. Thereby, compared with the case where the control part 100 does not make the said 2nd predetermined time small, the fall of the image quality resulting from toner deterioration can be suppressed more.

  In the above-described embodiment, an example in which the control unit 100 executes each step has been described. However, the present invention is not limited to this. At least a part of the steps is executed by another CPU, or one or a plurality of ASICs execute. It may be a configuration.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Apparatus main body 3 Process part 4 Exposure apparatus 5 Photoconductor 7 Developing roller 20 Storage part 30 Image forming part 100 Control part 150 Toner sensor

Claims (10)

A first photoreceptor corresponding to the first color toner;
A second photoreceptor corresponding to a second color toner that is a different color from the first color;
First development for supplying the first color toner accommodated in a first accommodating portion for accommodating the first color toner to the first photoreceptor and developing an electrostatic latent image on the first photoreceptor. Laura,
Second development for developing the electrostatic latent image on the second photoconductor by supplying the second color toner stored in the second storage unit for storing the second color toner to the second photoconductor. Laura,
A control unit,
The controller is
Rotation control for rotating the second developing roller when the first developing roller and the second developing roller develop the electrostatic latent images on the first photosensitive member and the second photosensitive member;
The speed in the rotation control when the first developing roller develops the electrostatic latent image on the first photosensitive member and the second developing roller does not develop the electrostatic latent image on the second photosensitive member. A deceleration control for rotating the second developing roller at a slower speed,
Acceleration control for rotating the second developing roller at a speed faster than the speed in the deceleration control based on at least one of the rotation speed of the second developing roller in the deceleration control and the time during which the deceleration control is executed; An image forming apparatus that executes The image forming apparatus according to claim 1,
The controller is
An image forming apparatus that counts the number of rotations of the second developing roller in the deceleration control, and executes the speed increase control when the counted number of rotations of the second developing roller is equal to or greater than a first predetermined number of rotations. The image forming apparatus according to claim 2,
The controller is
Stopping the speed increasing control when the speed increasing control is continuously executed for a first predetermined time or when the rotation speed of the second developing roller in the speed increasing control is equal to or higher than a second predetermined speed; Image forming apparatus. The image forming apparatus according to claim 2, wherein:
A toner amount detection unit for detecting the amount of the second color toner stored in the second storage unit;
The controller is
An image forming apparatus configured to reduce the first predetermined rotation number when the amount of the second color toner detected by the toner amount detection unit is equal to or less than a predetermined amount. The image forming apparatus according to claim 1,
The controller is
An image forming apparatus that measures the time during which the deceleration control is executed, and executes the acceleration control when the measured execution time is equal to or longer than a second predetermined time. The image forming apparatus according to claim 5, wherein
The controller is
Stopping the speed increasing control when the speed increasing control is continuously executed for a third predetermined time or when the rotation speed of the second developing roller in the speed increasing control is equal to or higher than a third predetermined speed; Image forming apparatus. The image forming apparatus according to claim 5, wherein:
A toner amount detection unit for detecting the amount of the second color toner stored in the second storage unit;
The controller is
An image forming apparatus configured to reduce the second predetermined time when the amount of the second color toner detected by the toner amount detection unit is equal to or less than a predetermined amount. An image forming apparatus according to any one of claims 1 to 7,
The controller is
An image forming apparatus that executes the acceleration control when the first photosensitive member and the second photosensitive member are positioned between two recording sheets that are continuously conveyed. A first photosensitive member corresponding to the first color toner, a second photosensitive member corresponding to a second color toner different from the first color, and a first toner containing the first color toner. A first developing roller that supplies the first color toner stored in the storage unit to the first photoconductor and develops an electrostatic latent image on the first photoconductor, and stores the second color toner. An image forming unit including: a second developing roller configured to supply the second color toner stored in the second storage unit to the second photosensitive member and develop an electrostatic latent image on the second photosensitive member; A rotating step of rotating the second developing roller when the first developing roller and the second developing roller develop an electrostatic latent image on the first photosensitive member and the second photosensitive member,
The speed in the rotation step when the first developing roller develops the electrostatic latent image on the first photosensitive member and the second developing roller does not develop the electrostatic latent image on the second photosensitive member. A decelerating step of rotating the second developing roller at a slower speed,
A speed increasing step for rotating the second developing roller at a speed faster than a speed in the speed reducing step based on at least one of a rotation speed of the second developing roller in the speed reducing step and a time required for the speed reducing step; Including speed control method. A first photosensitive member corresponding to the first color toner, a second photosensitive member corresponding to a second color toner different from the first color, and a first toner containing the first color toner. A first developing roller that supplies the first color toner stored in the storage unit to the first photoconductor and develops an electrostatic latent image on the first photoconductor, and stores the second color toner. An image forming unit including: a second developing roller configured to supply the second color toner stored in the second storage unit to the second photosensitive member and develop an electrostatic latent image on the second photosensitive member; In addition,
Rotation control for rotating the second developing roller when the first developing roller and the second developing roller develop the electrostatic latent images on the first photosensitive member and the second photosensitive member;
The speed in the rotation control when the first developing roller develops the electrostatic latent image on the first photosensitive member and the second developing roller does not develop the electrostatic latent image on the second photosensitive member. And a deceleration control for rotating the second developing roller at a slower speed,
Based on at least one of the number of rotations of the second developing roller in the deceleration control and the time during which the deceleration control is executed, speed increase control for rotating the second developing roller at a speed faster than the speed in the speed reduction control is executed. Speed control program to let you.

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