JP2015187667A - image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that can reduce unnecessary idle rotation to suppress a reduction of the life of developing sleeves and a reduction in toner yield irrespective of the value of the target number of rotation of a developing motor.SOLUTION: An image forming apparatus 100 includes exposure parts 3a to 3d that each form an electrostatic latent image on a photoconductor drum; developing parts 4a to 4d that each supply a developer to the electrostatic latent image to develop the electrostatic latent image; a detection part 122 that measures the time required for developing motors 40a to 40d rotating developing sleeves from the start of rotation to reach the target rotation speed; and a main body control CPU 111 that causes the exposure parts 3a to 3d to expose the photoreceptor drums while the developing motors 40a to 40d rotating the developing sleeves at the target rotation speed. The main body control CPU 111 causes the exposure parts 3a to 3d to start the exposure of the photoreceptor drums based on image data after the lapse of the time required for the developing motors 40a to 40d from the start of rotation to reach the target rotation speed measured by the detection part 122.

Description

  The present invention relates to an image forming apparatus using a photoconductor, and in particular, development timing of writing by an exposure unit such as a laser scanner that forms an electrostatic latent image on the photoconductor, and development by supplying a developer to the latent image. The present invention relates to a motor start timing control technology.

  In an image forming apparatus using an electrophotographic process, in order to maintain an appropriate image density, a developing motor that applies driving force to a developing unit that uses a developer to start driving is started, and then a laser scanner electrostatically applies to the photosensitive member. A latent image is formed. For example, a tandem type color image forming apparatus starts a developing motor of each color developing unit, and starts writing an image by a laser scanner of each color after a certain time has elapsed since the start of the developing motor was detected.

  Here, when the developing motor is a DC motor, the motor rotation speed changes as shown in FIG. 5 as time elapses after the motor is started. FIG. 5 is a diagram showing the relationship between the elapsed time after the start-up of the developing motor and the motor rotation speed, with the horizontal axis representing time [s] and the vertical axis representing motor rotation speed [rpm]. In the case of a DC motor, the number of rotations gradually increases with a certain inclination after the start of rotation. Then, after once overshooting, the developing motor is controlled to rotate stably at the target rotational speed (target rotational speed). At this time, an ON signal is output from the motor when the developing motor starts rotating, and a LOCK signal is output from the motor when the developing motor is stabilized at the target rotational speed.

  Image writing (image formation) by the laser scanner is started after a predetermined time has elapsed since the developing motor started to rotate (ON signal was output). However, the required time (rotation time) from when the developing motor starts rotating (ON signal is output) until it stabilizes at the target rotational speed (LOCK signal is output) varies. For example, when the rotation time of the developing motor is long, the image writing is started in a state where the rotation of the developing motor is not stable and the image density cannot be maintained properly. Therefore, there is a problem that the quality of the formed image is deteriorated.

Further, a main factor that the required time from the start of rotation of the developing motor to the stabilization at the target rotational speed varies is that the target rotational speed of the developing motor is changed on the image forming apparatus. One of the reasons for changing the target rotational speed is to prevent deterioration of the developer in the developing unit. By repeating the image formation, the deterioration of the developer proceeds, the amount of the developer supplied to the developing sleeve carrying the developer is reduced, and the image density is lowered. In order to prevent this, the number of rotations of the developing motor is increased, and the number of rotations of the developing motor is increased in order to keep the developer conveying force supplied to the developing sleeve constant.
As another reason, when the image forming apparatus has a plurality of productivity, for example, different types of printing functions, the target rotational speed may be changed to correspond to the process speed corresponding to each processing. .

  When the target rotational speed of the developing motor is changed, especially when the target rotational speed is high, as shown in FIG. 5, the time until overshoot is excessive as compared with other target rotational speeds. Further, as a result of increasing the amount of overshoot, the rotation time from when the ON signal is output to when the LOCK signal is output becomes longer.

  FIG. 6 shows the result of actually measuring the rotation time from the output of the ON signal to the output of the LOCK signal in a DC motor that is generally distributed. In FIG. 6, the average value taking into account the variation for each motor individual is represented as the ability value [s], and the maximum time in the variation is represented as the maximum value [s]. As shown in FIG. 6, when the DC motor is rotated at 2900 to 3000 [rpm] and when it is rotated at 1500 to 1600 [rpm], the actual value is 430 [ms], and the maximum value is 630 [ It can be seen that there is a difference in [ms]. As described above, when the rotation time varies, image formation is started in a state where the image density cannot be maintained properly, and as a result, the image quality is deteriorated.

To solve such a problem, in the conventional tandem type color image forming apparatus as in the developing apparatus disclosed in Patent Document 1, the writing time of all the laser scanners is the largest rotation time at the rotation speed of the developing motor. It is configured according to the uniform.
FIG. 7A is a timing chart showing operations of the developing motor and the laser scanner from the start to the end of printing when the target rotation speed of the developing motor is small (1500 to 1600 [rpm]). FIG. 7B is a timing chart showing the operations of the developing motor and the laser scanner from the start to the end of printing when the target rotational speed of the developing motor is large (2900 to 3000 [rpm]). As shown in FIGS. 7A and 7B, the writing start timing of the laser scanner is a timing that is uniformly set to the maximum value of the rotation time at the rotation speed of the developing motor of each color, regardless of the target rotation speed of the developing motor. It has become.

JP-A-8-146768

  However, in the configuration in which the image writing timing of the laser scanner is uniform, for example, when the target rotational speed of the motor is small (FIG. 7A), the time from the detection of the developing motor ON to the start of image writing of the laser scanner is large. It becomes relatively longer than For this reason, when the target rotational speed of the motor is small, the idle rotation time of the developing sleeve increases. Further, in order to prevent the developer carried on the developing sleeve from being deteriorated, it is necessary to discharge from the developing sleeve. For this reason, the toner yield (toner yield) decreases and the life of the developing sleeve is shortened as the discharged toner increases.

  Further, in order to reduce the idling time of the developing sleeve, it is assumed that the writing timing of all the laser scanners is uniformly set to the highest actual value (800 [ms] in FIG. 6) in use at the developing motor rotational speed. In this case, when the developing motor whose rotation time reaches the maximum value (1200 [ms] in FIG. 6) is started, the rotation of the developing motor is not stable and the image density cannot be maintained properly. Formation will begin. For this reason, the problem that the image quality is lowered remains.

  In view of the above problems, the present invention reduces the number of idle rotations and suppresses the shortening of the developing sleeve life and the decrease in toner yield, regardless of the value of the target rotation speed of the developing motor. It is a main object to provide an image forming apparatus that can be obtained.

  The image forming apparatus of the present invention is arranged to face a photosensitive member, an exposure unit that forms an electrostatic latent image on the photosensitive member by exposing the photosensitive member, and the electrostatic member. A developer carrier for developing a developer by supplying a developer to the latent image, a motor for rotating the developer carrier, and a measurement for measuring the time required from the start of rotation of the motor to the target rotational speed Control means for controlling the exposure means and the motor, wherein the exposure means exposes the photosensitive member in a state in which the motor rotates the developer carrier at a target rotational speed; And the control means exposes the photosensitive member based on image data to the exposure means after a lapse of time required from the start of rotation of the motor to the target rotational speed measured by the measurement means. Start And characterized in that.

  According to the present invention, the time from when the motor starts to rotate until the target rotational speed is reached is measured, and the exposure start timing of the image by the exposure unit is controlled based on the result. As a result, even if the elapsed time (rotation time) from the start of rotation of the motor to the target rotation speed varies due to the influence of individual motor differences, motor usage, etc., the rotation speed of the developer carrying member varies. After reaching the target rotational speed, the formation of the electrostatic latent image can be started.

1 is a schematic longitudinal sectional view of an image forming apparatus according to an embodiment. FIG. 3 is a diagram for explaining an example of a control system of the image forming apparatus according to the present embodiment. FIG. 6 is a procedure explanatory diagram illustrating an example of a procedure of image forming processing after activation or after returning from a hibernation state in the image forming apparatus according to the embodiment of the present invention. 6 is a timing chart showing operations of a developing motor and an exposure unit (laser scanner) from the start to the end of printing in the image forming apparatus according to the embodiment of the present invention. The figure which showed the relationship between the time passage after starting of a DC motor, and motor rotation speed. The figure which showed the measurement result of time from ON signal output for every rotational speed of DC motor to LOCK signal output. 9 is a timing chart showing operations of a developing motor and a laser scanner from the start to the end of printing in a conventional image forming apparatus example.

  Hereinafter, as an example of an image forming apparatus to which the present invention is applied, an electrophotographic image forming apparatus will be described with reference to the drawings. The present invention can also be applied to a printer, a copying machine, or a multifunction machine that integrates these functions.

[Embodiment]
FIG. 1 is a schematic cross-sectional view of the image forming apparatus according to the present embodiment.
The image forming apparatus 100 according to the present embodiment includes a housing 101, an operation panel 130 provided on the housing 101, and a scanner 140 that reads a document. The housing 101 is provided with each mechanism that constitutes an engine unit that performs image formation. In addition, a control system device including a main body engine unit 110 and a device controller unit 120 that perform control related to each printing process process (for example, a paper feed process) by each mechanism is provided. Details of the main body engine unit 110 and the device controller unit 120 will be described later. Hereinafter, each mechanism constituting the engine unit will be described.

The image forming apparatus 100 includes image forming stations Pa, Pb, Pc, and Pd corresponding to a plurality of colors (yellow, magenta, cyan, and black), respectively. Each of the image forming stations Pa to Pd is provided with a photosensitive drum 1 (1a, 1b, 1c, 1d) that is rotationally driven as a dedicated photosensitive member. As described above, in the image forming apparatus 100, as shown in FIG. 1, a plurality of photoconductors are arranged in parallel along the rotation direction of an intermediate transfer member described later. In the following, “a” is added to the device deployed at the yellow image forming station Pa, and similarly, “b” is indicated for magenta, “c” is indicated for cyan, and “k” is indicated for black.
Around each photosensitive drum 1 (1a to 1d), along the rotation direction, a dedicated charging unit 2 (2a, 2b, 2c, 2d), an exposure unit 3 (3a, 3b, 3c, 3d), Developing units 4 (4a, 4b, 4c, 4d) are provided. Further, a primary transfer unit 5 (5a, 5b, 5c, 5d) and a cleaning unit 6 (6a, 6b, 6c, 6d) are arranged.
Each exposure unit 3 (3a to 3d) is a laser scanner, and includes a laser light source (not shown) whose light emission is controlled in accordance with an image signal, and a plurality of mirror units (not shown) that guide laser light onto the drum. By the exposure units 3 (3a to 3d), electrostatic latent images based on image data are formed on the photoreceptor, that is, on the surfaces of the photosensitive drums 1 (1a to 1d). In addition, each exposure unit 3 (3a to 3d) can adjust the image writing timing based on the image data by adjusting the light emission timing of the laser light source and the mirror. Thus, each of the exposure units functions as an exposure unit.

On the other hand, an intermediate transfer belt 7, which is an endless belt-like (endless) intermediate transfer body, is provided below each photosensitive drum 1 (1 a to 1 d) in a manner of horizontally passing through the image forming stations Pa to Pd. Is done. The intermediate transfer belt 7 is wound around a plurality of rollers, and when a driving force is input to one of the driving rollers 8, the intermediate transfer belt 7 rotates.
Around the intermediate transfer belt 7 is a secondary transfer portion 9 that transfers a toner image onto the sheet material P on the intermediate transfer body, that is, from the surface of the intermediate transfer belt 7, and the surface of the intermediate transfer belt without being transferred by the secondary transfer portion 9. An intermediate transfer cleaning unit 10 that collects the remaining toner is disposed. In this way, the secondary transfer unit 9 functions as a transfer unit. The sheet material P is an example of a recording medium to which a toner image is transferred, and the toner image is transferred onto the recording medium.

The sheet material P is fed from a sheet feeding unit provided in the storage case 11, adjusted in posture by the registration adjusting unit 12, and then conveyed to the secondary transfer unit 9.
The sheet material P to which the toner image has been transferred is conveyed on the conveying belt 13. The conveyance belt 13 is driven by a drive motor (not shown), conveyed to a fixing unit 14 disposed downstream of the conveyance belt 13, heated and pressurized and fixed, and an image is obtained on the sheet material P. Thereafter, the sheet material P is conveyed to a paper discharge unit and discharged onto a paper discharge tray 15 outside the apparatus.

  As described above, the image forming apparatus 100 superimposes the toner images of different colors formed on the respective photosensitive drums 1 (1a to 1d) on the intermediate transfer belt 7 that is rotationally driven, thereby forming a color image. Configured to form.

Further, the operation panel 130 receives an instruction to change the development conditions, for example. This instruction is transmitted to a main body engine unit 110 and a device controller unit 120 described later. Thereby, the rotation speed (rotation speed) of the motor (development motor) 40 (40a-40d) which is each drive source of the image development part 4 (4a-4d) is controlled. The developing motor 40 (40a to 40d) can be a DC motor, for example.
The developing unit 4 (4a to 4d) includes, in addition to the developing motor 40 (40a to 40d), a developing sleeve (developer carrying member) (not shown) arranged to face the photosensitive drum 1 (1a to 1d). Each has a developing container (not shown) containing a developer. The developing sleeve is rotationally driven by the developing motor 40 (40a to 40d), carries the developer in the developing container, and supplies the developer to the corresponding photosensitive drums 1 (1a to 1d).

FIG. 2 is a diagram for explaining an example of a control system of the image forming apparatus 100 according to the present embodiment. As shown in FIG. 2, the image forming apparatus 100 includes a main body engine unit 110 and a device controller unit 120.
The main body engine unit 110 transfers motor rotation state data in the developing motor 40 (40a to 40d) in the developing unit 4 (4a to 4d) to the device controller unit 120 via the main body control CPU 111.

The device controller unit 120 includes an engine I / F 121, a detection unit 122, a storage unit 123, a control unit 124, and a motor control unit 125.
The engine I / F 121 exchanges information between the main body engine unit 110 and the device controller unit 120. The device controller unit 120 receives data (motor rotation state data) indicating the motor rotation state of the developing motor 40 (40a to 40d) via the engine I / F 121. Further, the engine I / F 121 transmits each control data processed in the device controller unit 120 to the main body engine unit 110 side.
Based on the motor rotation state data of the developing motor 40 (40a to 40d) received via the engine I / F 121, the detection unit 122 detects the state where each motor has started rotating from the stopped state (ON state) and the target rotational speed ( A stable state (LOCK state) is detected at the target rotational speed. The detection unit 122 also changes from a motor stop state to an ON state, and measures a required time (rotation time) from detection of the ON state to detection of the LOCK state for each motor. As described above, the detection unit 122 functions as a measurement unit.
The storage unit 123 records the maximum rotation time among the measurement results obtained by the detection unit 122 as time data.

The control unit 124 outputs information for controlling the image writing timing of the exposure unit 3 (3a to 3d) based on the time data stored in the storage unit 123.
The motor control unit 125 outputs information for changing the target rotational speed of the developing motor 40 (40a to 40d) based on the developing condition instructed from the operation panel 130. Information output from the control unit 124 and the motor control unit 125 is transmitted to the main body control CPU 111 via the engine I / F 121. The main body control CPU 111 that has received the information controls each operation of the exposure unit 3 (3a to 3d) and the developing motor 40 (40a to 40d) based on the information.

[Image formation processing procedure after startup or recovery from hibernation]
Next, an image forming procedure after activation of the image forming apparatus 100 or after returning from the hibernation state will be described with reference to FIG. FIG. 3 is a procedure explanatory diagram illustrating an example of the procedure of the image forming process after activation or return from the hibernation state in the image forming apparatus 100 according to the present embodiment. It should be noted that the image forming apparatus 100 has already been subjected to predetermined initial settings in advance, and will be described as starting various processes upon activation (power ON) or return from a hibernation state.

The image forming apparatus 100 acquires time data stored in the storage unit 123 in the device controller unit 120 when the image forming apparatus 100 returns from the startup or hibernation state (S001).
The time data stored in the storage unit 123 is the maximum time of the required time (rotation time) from when the ON state of the developing motor 40 (40a to 40d) is detected to when the LOCK state is detected. .

And it is discriminate | determined whether the target rotation speed of the developing motor 40 (40a-40d) instruct | indicated to the motor control part 125 is higher or lower than the predetermined setting value (for example, 2200-2300 [rpm]) in a factory shipment state. (S002).
When it is determined that the target rotational speed is higher than a predetermined set value in the factory shipment state (S002: Yes), the developing motor 40 (40a to 40d) is rotated at the target rotational speed instructed to the motor control unit 125. Control. Thereafter, the motor rotation state data is transmitted to the detection unit 122 via the engine I / F 121, and the ON state and the LOCK state are detected for each developing motor (S003).
The image forming apparatus 100 calculates the maximum rotation time in the developing motor 40 (40a to 40d) and transmits it to the control unit 124 as time data (S004). The calculated time data is stored in the storage unit 123 (S005). Note that the latest time data is overwritten and stored.

  On the other hand, when it is determined in the process of step S002 that the target rotational speed is lower than the predetermined set value in the factory shipment state (S002: No), the time data acquired in the process of step S001 is transmitted to the control unit 124.

  In response to the start of the print job (S006), the image forming apparatus 100 starts the yellow (Y) developing motor 40a (S007). Then, after the development motor 40a is started, the system waits for a time corresponding to the time data transmitted from the storage unit 123 to the control unit 124 (S008). Thereafter, the start of image writing of the exposure unit 3a is instructed after elapse of the standby time (S009). Note that the passage of the standby time is measured by a timer (not shown), and the standby time described below is also measured in the same manner.

  The image forming apparatus 100 activates the developing motor 40b for magenta (M) when the standby time obtained by dividing the distance between the photosensitive drums 1a and 1b by the process speed (S010). (S011). In this way, by starting (starting rotation) with a predetermined time delay from the developing motor 40a that is the upstream process, it is possible to reduce unnecessary idling of the developing motor 40b that is the adjacent downstream process. The same applies to the following downstream processes. Then, after the magenta developing motor 40b is started, the system waits for a time corresponding to the time data transmitted from the storage unit 123 to the control unit 124 (S012). After the standby time elapses, the exposure unit 3b is instructed to start image writing (S013).

  The image forming apparatus 100 activates the developing motor 40c for cyan (C) when the standby time obtained by dividing the distance between the photosensitive drums 1b and 1c by the process speed (S014). (S015). Then, after the cyan developing motor 40c is activated, the process waits for a time corresponding to the time data transmitted from the storage unit 123 to the control unit 124 (S016). After the standby time elapses, the apparatus is instructed to start image writing of the exposure unit 3c (S015 to S018).

The image forming apparatus 100 starts the development motor 40d for black (K) when the standby time obtained by dividing the distance between the photosensitive drums 1c and 1d by the process speed (S018). (S019). Then, after the black developing motor 40d is activated, it waits for a time corresponding to the time data transmitted from the storage unit 123 to the control unit 124 (S020). After the standby time elapses, the exposure unit 3d is instructed to start image writing (S021).
When the black image is written, the print job ends, and the image forming apparatus 100 ends the series of processes.

[Timing chart showing job start control operation]
The operations of the developing motor 40 (40a to 40d) and the exposure unit 3 (3a to 3d) from the start to the end of printing will be described with reference to FIG. FIG. 4 is a timing chart showing operations of the developing motor 40 (40a to 40d) and the exposure unit 3 (3a to 3d (laser scanner)) from the start to the end of printing in the image forming apparatus 100 according to the present embodiment. is there.
FIG. 4A is a timing chart showing the operations of the developing motor and the laser scanner from the start to the end of printing when the target rotation speed of the developing motor is small (1500 to 1600 [rpm]). FIG. 4B is a timing chart showing operations of the developing motor and the laser scanner from the start to the end of printing when the target rotation speed of the developing motor is large (2900 to 3000 [rpm]).

  In the timing chart shown in FIG. 4, when the target rotational speed of the developing motor 40 (40a to 40d) is small (FIG. 4A) and when the target rotational speed is large (FIG. 4B), the ON signal is changed. The image writing timing of the exposure unit 3 (3a to 3d) differs from the detection. That is, it can be seen that the idling time of the developing unit 4 (4a to 4d) is reduced. As a result, it is possible to optimize the idling time of the developing unit 4 (4a to 4d) according to the target rotation speed.

  As described above, in the image forming apparatus 100 of the present embodiment, even if the rotation time from when the developing motor starts to rotate until the speed is stabilized varies, regardless of the value of the target rotational speed of the developing motor. Optimization can be achieved by reducing unnecessary idle rotation of the developing section. Thereby, a good image can be obtained without reducing the image density.

In the above-described embodiment, the image forming apparatus is configured as a tandem type color image forming apparatus. However, it is of course possible to apply the technique according to the present invention to a single color image forming apparatus. Even when the technique according to the present invention is applied to a monochrome image forming apparatus, it is possible to reduce unnecessary idling. Thereby, it is possible to obtain a high-quality image while suppressing the shortening of the life of the developing sleeve and the decrease in the toner yield.
In the above-described embodiment, an example has been described in which the process includes determining whether the target rotational speed of the developing motor 40 (40a to 40d) is higher than a predetermined set value in the factory shipment state. In addition to this, it is of course possible to omit the determination step.
In the above-described embodiment, after the image forming apparatus 100 is activated or returned from the resting state, the developing motors 40a to 40d are actually rotated to measure the rotation time from the detection of the ON state to the detection of the LOCK state. The example in the case of having constituted so was demonstrated. In addition, the opportunity to measure the rotation time can be set arbitrarily.

  The embodiment described above is for explaining the present invention more specifically, and the scope of the present invention is not limited to these examples.

  Pa, Pb, Pc, Pd ... image forming station, 1 (1a, 1b, 1c, 1d) ... photosensitive drum, 2 (2a, 2b, 2c, 2d) ... charging unit, 3 (3a, 3b, 3c, 3d) ... exposure unit, 4 (4a, 4b, 4c, 4d) ... development unit, 40 (40a, 40b, 40c, 40d) ... development motor, 5 (5a, 5b, 5c, 5d) ... primary transfer part, 6 (6a, 6b, 6c, 6d) ... cleaning part, 7 ... intermediate transfer belt, 8 ... drive roller, 9 ... secondary transfer part DESCRIPTION OF SYMBOLS 10 ... Intermediate transfer cleaning part, 11 ... Storage, 12 ... Registration adjustment part, 13 ... Conveyor belt, 14 ... Fixing part, 15 ... Discharge tray, P ... Sheet material, 100: image forming apparatus, 101: casing, 110: main body engine unit 111 ... Main body control CPU, 120 ... Device controller, 121 ... Engine I / F, 122 ... Detection part, 123 ... Storage part, 124 ... Control part, 125 ... Motor control unit, 130 ... operation panel.

The image forming apparatus of the present invention is arranged to face a photosensitive member, an exposure unit that forms an electrostatic latent image on the photosensitive member by exposing the photosensitive member, and the electrostatic member. measurements a developer carrying member for developing by supplying a developer, and a DC motor for rotating the developer carrying member, the DC motor is until that reaches from the start of rotation to the target rotational speed time to the latent image Measuring means for controlling, and control means for controlling the exposure means and the DC motor, wherein the exposure means exposes the photosensitive member with the DC motor rotating the developer carrier at a target rotational speed. and a control unit, wherein the control means, the photosensitive member based on the image data to the exposure unit from the start of rotation of said DC motor after the lapse of time until the reach to the target rotational speed measured by said measuring means Dew of Characterized in that to start.

Claims (7)

A photoreceptor,
Exposure means for forming an electrostatic latent image on the photoreceptor by exposing the photoreceptor;
A developer carrying member that is disposed to face the photosensitive member and supplies the developer to the electrostatic latent image for development;
A motor for rotating the developer carrier;
Measuring means for measuring the time required from the start of rotation of the motor to the target rotational speed;
Control means for controlling the exposure means and the motor, the control means for exposing the photosensitive member to the exposure means in a state where the motor rotates the developer carrier at a target rotational speed,
The control means causes the exposure means to start exposure of the photoconductor based on image data after elapse of time required from the start of rotation of the motor to the target rotation speed measured by the measurement means. It is characterized by
Image forming apparatus. A storage unit for storing data relating to the time required from the start of rotation of the motor to the target rotation speed measured by the measuring means;
The controller is configured to expose the photoconductor based on image data at a timing based on data relating to a time required from the storage unit to reach the target rotational speed before the motor starts rotating after the motor starts rotating. Characterized by starting
The image forming apparatus according to claim 1. The control unit rotates the motor from a stopped state of the motor after the image forming apparatus is started or returned from a halt state, and the motor reaches the target rotational speed after the motor starts rotating. Storing the measurement result of the measurement means that measures the time until the storage unit,
The image forming apparatus according to claim 2. The control means determines whether the target rotational speed of the motor is higher than a predetermined rotational speed after the image forming apparatus is activated or returned from the hibernation state, and the target rotational speed is greater than the predetermined rotational speed. When the rotation speed is higher than the rotation speed of the motor, the measurement unit measures the time from when the motor starts to rotate until the motor reaches the target rotation speed. It is stored in the storage unit,
The image forming apparatus according to claim 1. The photoreceptor, the exposure means, the developer carrier, and the motor are provided for each of a plurality of colors,
The measuring means measures the time required from the start of rotation of each of the plurality of motors to the target rotational speed measured by the measuring means;
The control means causes the storage unit to store data relating to the longest time required to reach the plurality of target rotation speeds measured by the measurement means.
The image forming apparatus according to claim 2. An endless intermediate transfer body onto which the developed toner images are transferred onto the plurality of photoconductors;
Drive means for rotating the intermediate transfer member;
Transfer means for transferring a plurality of color toner images transferred onto the intermediate transfer body onto a recording medium at a transfer portion;
A plurality of photoconductors are juxtaposed along the rotational direction of the intermediate transfer member,
The control unit rotates the motor corresponding to a downstream photoconductor adjacent to a photoconductor provided upstream in the rotation direction of the intermediate transfer body when viewed from the transfer unit. The start timing is controlled so as to be delayed by a time obtained by dividing the distance between the adjacent photosensitive members by the rotation speed of the intermediate transfer member,
The image forming apparatus according to claim 5.   The image forming apparatus according to claim 1, wherein the motor is a DC motor.

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