JP2012220577A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress downtime generated by the execution of a developer residual amount detection and a reduction in lifetime of a cartridge.SOLUTION: With respect to a condition satisfaction unit which satisfies preliminarily set conditions among a plurality of image forming units, a CPU 205 is provided for executing a toner residual amount detection. In a case where the toner residual amount detection is executed on the condition satisfaction unit, when a condition unsatisfaction unit among condition unsatisfaction units which do not satisfy the preliminarily set conditions among the plurality of image forming units, is present whose estimated print number to the necessity of the toner residual amount detection afterward is equal to or less than an estimated print number of the condition satisfaction unit to the next necessity of the toner residual amount detection, the CPU 205 executes the toner residual amount detection on the condition unsatisfaction unit together with that on the condition satisfaction unit.

Description

  The present invention relates to an image forming apparatus such as a copying machine or a printer having a function of forming an image on a recording material such as a sheet.

2. Description of the Related Art Conventionally, in an image forming apparatus using an electrophotographic image process, a process cartridge system in which a photosensitive drum and process means acting on the photosensitive drum are integrally formed into a cartridge and the cartridge can be attached to and detached from the image forming apparatus main body. Is adopted. According to this process cartridge system, the maintenance of the apparatus can be performed by the user himself / herself without depending on the service person, so that the operability can be remarkably improved. In order to improve the maintainability of the cartridge type image forming apparatus, it is desirable to appropriately notify the user of the cartridge replacement time. Therefore, it is necessary to accurately detect the life of the cartridge.
One of the cartridge life detection methods is detection of the remaining amount of developer. A pixel count method, an antenna method, a light detection method, or a combination thereof (for example, Patent Document 1) has been proposed and implemented. ing.
Among them, the light detection method is a method in which the light detection means having an optical path in the developer accommodating portion obtains the remaining amount of developer by the time when the light is detected while the developer is stirred in the accommodating portion by the developer agitating means. is there. This light detection method can determine the remaining amount of developer with higher accuracy than the pixel count method for estimating the consumption amount of the developer or the antenna method that is affected by the environmental humidity.

JP 2009-37225 A

However, the above-described conventional image forming apparatus has the following problems.
In measurement of the remaining amount of developer by the light detection method (hereinafter, detection of remaining light amount), it is necessary to drive the developer agitating means at an appropriate speed for accurately measuring the remaining amount of developer. That is, when the rotation speed of the developing drive means during the printing operation is different from the rotation speed of the developer stirring means suitable for detecting the remaining amount of light, it is necessary to change the drive speed. For this reason, when detecting the remaining amount of light, the printing operation is temporarily stopped, and downtime occurs.
In an image forming apparatus having a plurality of cartridges such as a color laser beam printer, it is necessary to detect the remaining amount of light for each cartridge. Since the amount of developer consumption varies from cartridge to cartridge, the timing at which it is necessary to detect the remaining amount of light between the cartridges varies. For this reason, the number of times that the image forming apparatus performs the toner remaining amount detection increases by the number of cartridges, and there is a concern that the downtime due to the toner remaining amount detection execution further increases.

As a method for solving this problem, in an image forming apparatus having a plurality of cartridges, there is a method in which when the remaining amount of light is detected by one cartridge, the remaining amount of light is also detected by other cartridges. In this method, the execution timing of the remaining light detection of all the cartridges is aligned with the timing of the cartridge having the shortest execution interval of the remaining light detection. As a result, the number of times that the image forming apparatus stops the printing operation in order to execute the remaining light amount detection can be reduced to the number of executions of the remaining light amount detection for one cartridge, and the occurrence of downtime can be minimized. Can do.

However, in this method, the cartridge that does not need to detect the remaining amount of light always executes the remaining amount of light, and the developer agitation means is driven unnecessarily. As a result, since the developing device is driven in accordance with the driving of the developer stirring means, the driving time of the developing device becomes long. There is a concern that when the driving time of the developing device becomes long, the developer deteriorates earlier than usual, and a new problem of shortening the durable life of the cartridge occurs. Further, in the case of detecting the remaining amount of light while the photosensitive drum and the developing device are in contact with each other, there is a concern that the photosensitive drum may be scraped by the developing device and the cartridge may be shortened in the same manner. .
As described above, the execution of the developer remaining amount detection has two problems, that is, the occurrence of downtime and the shortening of the life of the cartridge.
The present invention has been made in view of the above-described circumstances, and an object thereof is to suppress downtime caused by execution of developer remaining amount detection and to suppress shortening of the cartridge life.

In order to achieve the above object, the present invention provides:
Developing means for developing the electrostatic latent image formed on the image carrier with a developer;
A developer accommodating portion for accommodating a developer used in the developing means;
A remaining amount detecting means for detecting the remaining amount of the developer in the developer accommodating portion;
In the image forming apparatus including a plurality of image forming units provided so as to be replaceable with respect to the image forming apparatus main body,
An execution unit for performing a developer remaining amount detection by the remaining amount detection unit for a condition satisfaction unit that satisfies a preset condition among the plurality of image forming units;
The execution means includes
Among the plurality of image forming units, a condition unsatisfied unit that does not satisfy a preset condition, when the remaining amount of developer is detected by the remaining amount detecting unit with respect to the condition satisfying unit. Then, there is a condition dissatisfied unit whose timing that is predicted to satisfy a preset condition is the same as or earlier than the timing that the condition satisfying unit is predicted to satisfy the preset condition next. If you want to
The developer remaining amount detection for the condition unsatisfactory unit is executed in parallel with the condition satisfaction unit.

  According to the present invention, it is possible to suppress the downtime caused by the execution of the developer remaining amount detection and to suppress the shortening of the cartridge life.

FIG. 6 is a diagram for explaining toner remaining amount detection parallel determination processing according to the first exemplary embodiment. Sectional drawing shown about schematic structure of the image forming apparatus of Example 1. FIG. FIG. 6 is a diagram for explaining a toner remaining amount detection method using a light transmission method according to the first exemplary embodiment. 1 is a diagram illustrating a system configuration of a control unit of an image forming apparatus according to a first embodiment. FIG. 10 is a diagram illustrating toner remaining amount detection execution determination processing according to the first exemplary embodiment. FIG. 10 is a diagram illustrating a relationship between the remaining toner amount A and the remaining toner amount detection execution threshold Wth according to the first exemplary embodiment. FIG. 6 is a diagram for explaining a process in which toner remaining amount detection according to the first exemplary embodiment is executed. A diagram for explaining a change in toner remaining amount and how toner remaining amount detection is performed. Block diagram of an engine control unit of an image forming apparatus in Embodiment 2. FIG. 10 is a diagram for explaining toner remaining amount detection parallel determination processing in Embodiment 2.

  DETAILED DESCRIPTION Exemplary embodiments for carrying out the present invention will be described in detail below with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in this embodiment should be appropriately changed according to the configuration of the apparatus to which the invention is applied and various conditions. It is not intended to limit the scope to the following embodiments.

(Outline of image forming apparatus)
Embodiment 1 of the present invention will be described below with reference to FIGS.
FIG. 2 is a cross-sectional view illustrating a schematic configuration of a laser printer as an image forming apparatus according to the present exemplary embodiment.
In the image forming apparatus according to the present exemplary embodiment, first, an electrostatic latent image is formed by image light formed based on the pixel signal transmitted from the controller unit, and the electrostatic latent image is developed to make a visible image. Is formed. This visible image is superimposed and transferred to form a color visible image, and this color visible image is transferred to the sheet (recording material) 2 to fix the color visible image on the sheet 2.

The image forming unit of the image forming apparatus includes a photosensitive drum (5Y, 5M, 5C, 5K) for each station arranged side by side for development color, a charger (7Y, 7M, 7C, 7K) as a primary charging unit, and development. And the intermediate transfer body 12. The container (8Y, 8M, 8C, 8K) The photosensitive drum (5Y, 5M, 5C, 5K), the injection charging means (7Y, 7M, 7C, 7K) as the primary charging means, and the developing device (8Y, 8M, 8C, 8K) are attached to and detached from the main body of the image forming apparatus. It is mounted on cartridges (22Y, 22M, 22C, 22K) that can be exchanged.
Here, the configuration and operation of each cartridge are substantially the same except that the color of the toner (developer) used is different. Accordingly, in the following description, if no distinction is required, the subscripts Y, M, C, and K given to the reference numerals in FIG. 2 are omitted to indicate that the elements are provided for any color. The overall explanation is as follows. The cartridge 22 corresponds to an image forming unit.

The photosensitive drum 5 serving as an image carrier is configured by coating an outer periphery of an aluminum cylinder with an organic optical transmission layer, and is rotated by a driving force of a driving motor (not shown). The driving motor is a photosensitive drum 5. Is rotated in the clockwise direction according to the image forming operation. The exposure light to the photosensitive drum 5 is sent from the scanner unit 10, and the surface of the photosensitive drum 5 is selectively exposed to form an electrostatic latent image.
As the primary charging means, each station is provided with four chargers 7 for charging the photosensitive drums of yellow (Y), magenta (M), cyan (C), and black (K) at each station. Are provided with primary charging rollers 7YR, 7MR, 7CR, and 7KR, respectively.

  In order to develop and visualize the electrostatic latent image with toner as developing means, development is performed using yellow (Y), magenta (M), cyan (C), and black (K) toner at each station. Four developing devices 8 are provided. Each developing device 8 is provided with developing rollers 8YR, 8MR, 8CR, and 8KR. Each developing device 8 is provided with a toner D described later, a toner containing portion containing the toner D, and a configuration for detecting the remaining amount of toner.

The intermediate transfer member 12 is in contact with the photosensitive drum 5 and is configured to rotate counterclockwise in FIG. 2 as the photosensitive drum 5 rotates during color image formation. The intermediate transfer body 12 receives a visible image from the photosensitive drum 5 at a nip (primary transfer nip) between the photosensitive drum 5 and the primary transfer roller 4 by a primary transfer bias applied to the primary transfer roller 4. . Thereafter, a nip formed between the intermediate transfer member 12 and the secondary transfer roller 9 (
By nipping and conveying the sheet 2 at the secondary transfer nip), a color visible image is simultaneously superimposed and transferred onto the sheet 2.

The fixing unit 13 fixes the transferred color visible image on the sheet 2 while conveying the sheet 2. The fixing roller 14 that heats the sheet 2 and the pressure for pressing the sheet 2 against the fixing roller 14. And a roller 15. The fixing roller 14 and the pressure roller 15 are formed in a hollow shape, and a heater is built in the fixing roller 14.
That is, the sheet 2 holding the color visible image is conveyed by a fixing nip formed by the fixing roller 14 and the pressure roller 15, and the toner is fixed on the sheet surface by applying heat and pressure. The sheet 2 after fixing the visible image is discharged to the discharge unit 27, and the image forming operation is completed.

(Toner remaining amount detection unit)
Next, the remaining light amount detection (developer remaining amount detection) by the light transmission type of this embodiment will be described with reference to FIG. FIG. 3 is a cross-sectional view illustrating a schematic configuration of the cartridge 22, for explaining a method for detecting the remaining amount of toner using a light transmission method.
As shown in FIG. 3, the developing device 8 of the cartridge 22 includes a toner D, a toner container (developer container) 301 that stores the toner D, and a toner agitator for agitating the toner D in the toner container 301. A member 305 is provided. In addition, the toner storage unit 301 includes a light transmission window 303 and a light transmission window 304 for transmitting light.

  The image forming apparatus includes a light emitting unit 300 that emits light for detecting the remaining amount of toner in the toner storage unit 301 (in the developer storage unit), and a toner storage unit 301 as shown in FIG. A light receiving unit 302 that receives the light that has passed therethrough is provided. In this embodiment, the light emitting unit 300 uses an LED, and the light receiving unit 302 uses a phototransistor (PTR). The light transmission type toner remaining amount detection method is a method of detecting the remaining amount of toner in the toner storage unit 301 by allowing light to pass through the toner storage unit 301.

  When there is no toner D in the toner storage unit 301 (when the remaining amount of toner is below a certain value), light from the light emitting unit 300 enters the light transmission window 303 and passes through the toner storage unit 301 to transmit light. The light exits from the window 304 and is guided to the light receiving unit 302. When there is sufficient toner D in the toner storage unit 301, light is blocked by the toner D on the optical path between the light transmission window 303 and the light transmission window 304 and does not reach the light receiving unit 302.

  In the configuration of the present exemplary embodiment, a CPU (central processing unit) 205 described later drives a developing drive motor 211 described later at the time of detecting the remaining amount of toner, thereby rotating the toner stirring member 305 at a predetermined cycle. Since the toner agitating member 305 is rotating during the toner remaining amount detection, the transmitted light is shielded even when the toner container 301 does not have the toner D. Therefore, the light receiving unit 302 detects the light receiving period and the light shielding period alternately. Here, the CPU 205 constitutes execution means, setting means, and remaining amount estimation means.

When the toner D remains in the toner storage unit 301 to some extent, since there is the toner D conveyed by the toner stirring member 305, the light shielding period becomes longer than when there is no toner D. The light shielding period corresponds to the amount of toner D in the toner storage unit 301.
Therefore, by measuring the ratio of the light shielding period of the period in which the toner agitating member 305 rotates once (hereinafter referred to as agitation period), the amount of toner D inside the toner storage unit 301 can be detected. It is also possible to detect the remaining amount by comparing the ratios of the light receiving periods instead of comparing the ratios of the light shielding periods.

FIG. 4B shows a developer amount detection device (remaining amount detection means, remaining light amount detection device) in this embodiment.
2 is a block diagram of a system configuration of a remaining toner amount detection unit 207. FIG.
As shown in FIG. 4B, the toner remaining amount detection unit 207 includes a light reception detection unit 212, a light reception time counter 213, and a toner remaining amount conversion unit 214 in addition to the light emitting unit 300 and the light receiving unit 302.

The output of the light receiving unit 302 is input to the light receiving detection unit 212. The light reception detection unit 212 sends an output signal (hereinafter referred to as a light reception signal) to the light reception time counter 213 only when light of a predetermined level or higher is received. The light reception time counter 213 measures the time when the light reception signal is received, and sends the measured value to the toner remaining amount conversion unit 214.
The toner remaining amount conversion unit 214 derives the remaining amount of toner in the toner storage unit 301 from the measurement value of the light reception time counter 213 and the stirring cycle, and sends the remaining amount of toner A (%) as detection data to the CPU 205.
Here, the toner remaining amount detection method for one cartridge has been described. However, in this embodiment, the above-described toner remaining amount detection unit 207 is provided in each station, and the toner remaining amount in the toner storage unit 301 is determined independently. Can be calculated and sent to the CPU 205.

In this embodiment, the rotation speed for rotating the toner stirring member 305 at a predetermined cycle is set to one third of the rotation speed of the developing drive motor 211 during the printing (printing, image forming) operation. . This is because the rotation speed of the toner stirring member 305 affects the accuracy of toner remaining amount detection.
Specifically, the mixing state of the toner D and the air in the toner storage unit 301 to be stirred changes depending on the rotation speed of the toner stirring member 305, and as a result, the fluidity of the toner D in the toner storage unit 301 changes. is there. In general, when the toner stirring member 305 is rotated at a high speed, the toner D and air are well mixed and the fluidity of the toner D is increased, and when the toner stirring member 305 is rotated at a low speed, the fluidity of the toner D is decreased. Become.

  When the fluidity of the toner D is high, the toner D again covers the light transmission window 303 even if the toner stirring member 305 wipes off the toner D covering the surface of the light transmission window 303. For this reason, the difference in the length of time during which the light receiving unit 302 detects light when the remaining amount of toner is large and when the amount of toner is small is reduced, and the remaining amount of toner cannot be accurately detected.

  For the above reasons, the printing operation is once stopped (interrupted) when the remaining toner amount is detected, and the rotation speed of the developing drive motor 211 for driving the toner stirring member 305 is reduced to one third of that during the printing operation. Downtime occurs because it is necessary.

(Configuration of control unit of image forming apparatus)
Next, the system configuration of the entire control unit of the image forming apparatus will be described with reference to the block diagram of FIG.
In FIG. 4A, 200 is a host computer, 201 is a controller unit, and 203 is an engine control unit. The engine control unit 203 includes a video interface unit 204, a CPU 205, a cartridge NVRAM control unit 206, a toner remaining amount detection unit 207, and a toner consumption amount estimation unit 208.

  The controller unit 201 receives image information and a print command from the host computer 200. The controller unit 201 analyzes the received image information and converts it into bit data, and sends a print reservation command, a print start command, and a video signal to the engine control unit 203 via the video interface unit 204 for each sheet.

The CPU 205 of the engine control unit 203 completes the image forming operation by outputting to the various actuators 210 based on the information acquired from the various sensors 209. The CPU 205 includes a ROM 219 that stores program codes and data, and a RAM 220 that is used for temporary data storage. Among the actuators, the photosensitive drum 5, the developing roller 8R, and the toner stirring member 305 of each station are connected to the developing drive motor 211 of each station of YMCK. The CPU 205 outputs a signal and rotates the developing drive motor 211, whereby driving force is supplied to the photosensitive drum 5, the developing roller 8 </ b> R, and the toner stirring member 305.

  The toner consumption amount estimation unit 208 receives the pixel signal transmitted from the controller unit 201 and estimates the toner consumption amount for each image forming station. The toner remaining amount detection unit 207 measures the remaining amount of toner in the toner storage unit 301 of each cartridge by operating the light emitting unit 300 and the light receiving unit 302 shown in FIG. The cartridge NVRAM control unit 206 is connected to the NVRAM read / write unit 306 provided in the cartridge shown in FIG. 3, and can read / write data from / to the cartridge NVRAM 307 via the nonvolatile memory read unit 306.

(Toner consumption estimation part)
A toner consumption estimation unit (calculation device) 208 that estimates toner consumption (developer consumption) at the time of image forming operation as needed will be described below.
In general, the amount of toner consumed increases as the image information of an image formed on a sheet by an image forming operation in proportion to the pixel information (number of pixel signals (pixel count number)) of the output image. The toner consumption W is estimated by applying the formula.
W = PC × Wdot (1)

  Here, the toner consumption amount W represents the toner consumption amount when the remaining amount of toner in the new cartridge is 100%, and its unit is%. PC is a pixel count value obtained by counting the number of times the pixel signal is turned on in order to expose the surface of the photosensitive drum, and the unit is pixel. Wdot is the amount of toner consumed per pixel, and its unit is% / pixel. Wdot is a value determined by the toner capacity of the cartridge.

FIG. 4C is a block diagram of a system configuration of the toner consumption amount estimation unit 208 in this embodiment.
As shown in FIG. 4C, the toner consumption amount estimation unit 208 includes a pixel signal input unit 215, a pixel signal counter 216, an estimated consumption amount conversion unit 217, and a consumption amount data output unit 218.
Image data sent from the host computer 200 is developed by the controller unit 201 and converted into a pixel signal of an output image. The converted pixel signal is input to the pixel signal input unit 215 via the video interface unit 204 of the engine control unit 203 and is 1/0 from the analog signal of voltage Low / High so that the pixel signal counter 216 can easily count the pixel signal. It is formed into a digital signal.

The pixel signal counter 216 counts the pixel signal for each printing operation of one page formed by the pixel signal input unit 215, and outputs the PC value for each printing operation of one page. The outputted PC value is sent to the estimated consumption amount conversion unit 217, and the toner consumption amount W is calculated by the above equation (1). The calculated toner consumption amount W is output to the CPU 205 via the consumption amount data output unit 218.
The CPU 205 sequentially obtains the estimated toner remaining amount by subtracting the toner consumption amount W from the toner remaining amount A obtained by the toner remaining amount detecting unit 207 described above.

In addition, the CPU 205 adds the toner consumption amount W received from the consumption amount data output unit 218 to the cumulative toner consumption amount Wint stored in the RAM 220 in the CPU 205, so that the total toner consumption amount of the current cartridge (current cumulative amount). The toner consumption amount Wint) is obtained.
The CPU 205 requests the cartridge NVRAM control unit 206 to write the accumulated toner consumption amount Wint, and the cartridge NVRAM control unit 206 stores the accumulated toner consumption amount Wint in the cartridge NVRAM 307 provided in the cartridge.

This is because the cartridge can be attached to and detached from the image forming apparatus. When the CPU 205 detects that the cartridge has been replaced, the CPU 205 performs the following operation. That is, the cumulative toner consumption amount Wint in the RAM 220 in the CPU 205 is overwritten with the cumulative toner consumption amount Wint stored in the cartridge NVRAM 307 provided in the cartridge via the cartridge NVRAM control unit 206.
As a result, even when the combination of the cartridge and the printer is changed, it is possible to normally obtain the accumulated toner consumption amount Wint.

The CPU 205 can also obtain the estimated toner remaining amount at a certain time as follows.
For this purpose, a reference toner consumption amount which is a value storing the toner remaining amount A finally obtained by the toner remaining amount detecting unit 207 and the accumulated toner consumption amount Wint at the time of obtaining the toner remaining amount A for a certain time point. Three are used: Wb and the accumulated toner consumption amount Wint at a certain time. Then, using these, the estimated remaining toner amount at a certain time is expressed by the following equation:
(Estimated toner remaining amount) = A− (Wint−Wb)
Can be obtained sequentially.

(Toner remaining amount detection execution determination process)
Next, the remaining toner amount detection execution interval calculation process and the remaining toner amount detection execution determination process performed using the remaining toner amount detection execution interval calculation result in the image forming apparatus according to the present exemplary embodiment will be described with reference to FIG.
FIG. 5 is a diagram illustrating toner remaining amount detection execution determination processing executed by the CPU 205. Here, for simplicity of explanation, only the toner remaining amount detection execution determination process for one cartridge is described. The toner remaining amount detection execution determination process when a plurality of cartridges are provided as in the configuration of the present embodiment will be described in the toner remaining amount detection concurrent determination process described later.

The CPU 205 performs a printing operation and executes a toner remaining amount detection execution determination process shown in FIG. 5 every time the accumulated toner consumption amount Wint is updated.
The CPU 205 performs a toner remaining amount detection execution threshold Wth obtained when the previous toner remaining amount detection is executed, a reference toner consumption amount Wb that is a cumulative toner consumption amount at the time when the previous toner remaining amount detection is executed, and the current accumulated toner consumption. Compare the difference in quantity Wint. When the difference between the reference toner consumption amount Wb and the cumulative toner consumption amount Wint is equal to or greater than the toner remaining amount detection execution threshold value Wth (corresponding to a case where a preset condition is satisfied), it is necessary to detect the remaining amount of toner. Judgment is made and execution of toner remaining amount detection is started (S501). If the value (detection result) is less than the remaining toner amount detection execution threshold Wth, the remaining toner amount detection execution determination process is terminated without executing the remaining toner amount detection (S501).

  If the CPU 205 determines that the toner remaining amount detection is necessary, the CPU 205 interrupts the printing operation to execute the toner remaining amount detection, and drives the development drive motor 211 at a speed for executing the toner remaining amount detection (S502). When the CPU 205 rotates the toner stirring member 305 by driving the development drive motor 211, the CPU 205 requests the remaining toner amount detection unit 207 to execute the remaining toner amount detection. The toner remaining amount detection unit 207 calculates the toner remaining amount A by the above-described toner remaining amount detection process, and sends the toner remaining amount A to the CPU 205 (S503).

When the CPU 205 receives the remaining toner amount A from the remaining toner amount detection unit 207, the CPU 205 obtains (sets) the remaining toner amount detection execution threshold value Wth using Expression (2) (S504). The CPU 205 updates the reference toner consumption amount Wb with the current cumulative toner consumption amount Wint (S505). When the toner remaining amount detection process is completed, the CPU 205 returns the driving speed of the development drive motor 211 changed in S502 to the normal printing operation speed, restarts the printing operation, and completes the remaining toner detection execution determination process. (S506).

Here, the remaining toner amount detection execution threshold value Wth corresponds to a preset condition, and in this embodiment, is obtained by a remaining toner amount detection execution interval calculation process. In this embodiment, the toner remaining amount detection execution threshold Wth is set to a value determined by the threshold function Fth shown in Expression (2) based on the toner remaining amount A measured by the toner remaining amount detecting unit 207.
Wth = Fth (A) = Max (3%, 0.25 × A) (2)
Here, the function Max (p1, p2,..., Pn) is a function for obtaining the maximum value among the parameters pi (i = 1 to n).

FIG. 6 shows the relationship between the toner remaining amount A and the toner remaining amount detection execution threshold value Wth.
As shown in FIG. 6, the toner remaining amount detection execution threshold value Wth is set so that when the remaining amount of toner is large, the execution interval of the remaining amount of toner becomes longer, and when the remaining amount of toner is small, the execution interval becomes shorter. Has been. This is because there is no need to accurately detect the remaining amount of toner when the remaining amount of toner is high, and when the remaining amount of toner is low, the user knows when the toner is empty and notifies the user accurately. This is because it is necessary to detect the remaining amount of toner.
Further, the reason why the toner remaining amount detection execution threshold Wth is pasted at the lower limit of 3% is to prevent downtime from increasing due to frequent occurrence of toner remaining amount detection at the end of the life of the cartridge. .

  Next, a process in which toner remaining amount detection is executed by one cartridge by the above-described toner remaining amount detection execution determination process will be described with reference to FIG. In FIG. 7, the broken line represents the estimated value of the remaining amount of toner obtained by the toner consumption amount estimating unit 208, and the solid line represents the actual remaining amount of toner in the toner storage unit 301.

It is assumed that the cartridge is in a new state where the remaining amount of toner is 100% at time 0 in the initial state. At this time, the remaining toner amount A is 100%, the remaining toner amount detection execution threshold Wth is 0.25 × 100 = 25%, the reference toner consumption amount Wb is 0%, and the cumulative toner consumption amount Wint is 0%.
The CPU 205 repeats the image forming operation with time, and each time the CPU 205 receives the toner consumption amount W output from the toner consumption amount estimation unit 208. The CPU 205 obtains an estimated toner remaining amount (broken line) by subtracting the toner consumption amount W sequentially (as needed) from the current toner remaining amount A. Since the toner consumption amount W is an estimated value, there is a slight difference between the estimated toner remaining amount (broken line) and the actual toner remaining amount (solid line).

  In the toner remaining amount detection execution determination process executed at time point 1, the CPU 205 determines that the difference between the reference toner consumption amount Wb (= 0%) and the cumulative toner consumption amount Wint (= 25%) is the remaining toner amount detection execution threshold value Wth ( = 25%) or more. The CPU 205 executes the remaining toner amount detection by the remaining toner amount detection execution determination process, and acquires the actual remaining toner amount A = 60% from the remaining toner amount detection unit 207.

  The CPU 205 obtains the remaining toner amount detection execution threshold Wth as Fth (60%) = 15% by the remaining toner amount detection execution determination process, and sets the reference toner consumption amount Wb to the current cumulative toner consumption amount Wint (= 25%). ) To update. Thereafter, the CPU 205 repeats this process, and when the estimated toner remaining amount (A- (Wint-Wb)) reaches 45% (cumulative toner consumption amount Wint is 40%) at time point 2, the CPU 205 detects the remaining toner amount. The actual toner remaining amount A = 50% is acquired.

  As described above, by using the remaining toner amount detection execution interval calculation process and the remaining toner amount detection execution determination process in this embodiment, the remaining toner amount detection is performed before the estimated value of the remaining toner amount greatly deviates from the actually measured value. It is possible to obtain a more accurate toner remaining amount.

(Toner remaining amount detection parallel determination process)
Next, the remaining toner amount detection concurrent determination processing as the remaining developer amount detection concurrent determination means when there are a plurality of cartridges, which is a feature of the present embodiment, will be described with reference to FIG.
Here, an outline of the toner remaining amount detection parallel determination process will be described. First, the interval (timing) for each cartridge is estimated from the estimation result of the remaining amount of toner for each cartridge until the next detection of the remaining amount of toner is necessary. The result is used to determine whether or not the remaining toner amount detection should be performed in parallel with the other cartridges when the remaining toner amount detection of a certain cartridge is performed. The toner remaining amount detection is executed only for the cartridge that is determined to be necessary. Hereinafter, the toner remaining amount detection concurrent determination process will be described in detail.

The CPU 205 executes the remaining toner amount detection parallel determination process shown in FIG. 1 each time the print operation is performed and the accumulated toner consumption amount Wint is updated. In the following description, the cartridges 22Y, 22M, 22C, and 22K are represented as cartridges C1, C2, C3, and C4, respectively, and when any one of the cartridges is represented, it is represented as Ci.
The CPU 205 includes execution request information R <b> 1 to R <b> 4 in the RAM 220 that indicates whether or not to perform toner remaining amount detection for each of the cartridges C <b> 1 to C <b> 4. In the execution request information R1 to R4, 1 is stored when the toner remaining amount detection is executed, and 0 is stored when it is not executed. In the execution request information R1 to R4, when any execution request information is represented, it is expressed as Ri.

  The CPU 205 makes a toner remaining amount detection execution determination for all the cartridges Ci (S101). If the CPU 205 determines that the toner remaining amount detection needs to be executed for the cartridge Ci in S101 (a preset condition is satisfied), the CPU 205 sets the execution request information Ri to 1 (S103) and determines that it is not necessary. In this case, the execution request information Ri is set to 0 (S102).

If there is no 1 in the execution request information R1 to R4, the CPU 205 determines that there is no cartridge that needs to be detected for the remaining amount of toner this time, and ends the toner remaining amount detection concurrent determination process (S104). ).
If the CPU 205 determines that it is necessary to detect the remaining amount of toner, the CPU 205 calculates the toner consumption amount inclination α as the developer remaining amount change estimation means for all cartridges using the following equation (3) (S105). ).
α = Wint ÷ Np (3)

Here, Wint is the current accumulated toner consumption amount Wint obtained by the toner consumption amount estimation unit 208. Np is the total number of printed sheets from the start of counting the cumulative toner consumption amount Wint of the cartridge 22 to the present. It is assumed that the total number Np of prints is incremented by one every time the image forming apparatus performs an image forming operation and is stored in the cartridge NVRAM 307 provided in the cartridge. Since the toner consumption amount inclination α is obtained for each cartridge, the toner consumption amount inclination α of a certain cartridge _Ci is expressed as α _Ci .
Note that the total number Np of prints may be changed according to the size of the recording material to be subjected to the image forming operation, or instead of being stored in the cartridge NVRAM 307 provided in the cartridge, It may be stored in other storage means.

Next, the CPU 205 is an interval from the execution of the toner remaining amount detection for the cartridge Ci whose execution request information Ri is 1 to the next time the toner remaining amount detection of the cartridge Ci needs to be executed again. The next toner remaining amount detection execution interval Ix _Ci is obtained (S106). The following equation (4) is used to obtain the next toner remaining amount detection execution interval Ix _Ci .
Ix _Ci = Fth (A _Ci − (Wint _Ci −Wb _Ci )) / α _Ci (4)

Here, the next toner remaining amount detection execution interval Ix _Ci is obtained by assuming that the current estimated toner remaining amount for a certain cartridge (condition satisfying unit) Ci is the actual toner remaining amount. This is the expected number of prints until detection needs to be executed. The timing (time point) at which the estimated number of prints is printed corresponds to the timing at which it is predicted that the preset condition is satisfied next. The CPU 205 predicts (predicts) that it is next necessary to detect the remaining amount of toner at the timing when the estimated number of prints is printed. A _Ci , Wint _Ci , and Wb _Ci are the remaining toner amount A, the accumulated toner consumption amount Wint, and the reference toner consumption amount Wb of the cartridge Ci, respectively.
In the equation (4), the threshold shown in the equation (2) is obtained by using the estimated toner remaining amount of the cartridge Ci obtained by (toner remaining amount A _Ci −cumulative toner consumption amount Win _Ci + reference toner consumption amount Wb _Ci ). The estimated threshold value for the next remaining toner amount detection is obtained by the function Fth.

The CPU 205 sets the smallest value of the next toner remaining amount detection execution interval Ix _Ci obtained in S106 as the next toner remaining amount detection execution minimum interval Im (S107). Here, the next toner remaining amount detection minimum execution interval Im corresponds to the expected number of prints between the time when the remaining toner amount detection is performed and the next remaining toner amount detection is performed as the entire image forming apparatus.

Next, for the cartridge (condition unsatisfactory unit) Ci whose execution request information Ri is 0, the CPU 205 performs a toner remaining amount detection execution interval Iy _Ci that is an interval from the current time until it becomes necessary to detect the remaining amount of toner in the cartridge _Ci. Is obtained by the following equation (5) (S108).
Iy _Ci = (Wth _Ci − (Wint _Ci −Wb _Ci )) / α _Ci (5)

Here, the toner remaining amount detection execution interval Iy _Ci is a toner remaining amount detection when a cartridge Ci that does not need to perform toner remaining amount detection at this time consumes toner at a toner consumption amount inclination α _Ci in the future. This is the expected number of prints until the execution of is required. Wth _Ci is a toner remaining amount detection execution threshold value Wth obtained when the toner remaining amount detection of the cartridge _Ci was previously performed.

Whether the CPU 205 executes (simultaneously) at the same time the remaining toner amount detection using the following conditional expression (6) for a cartridge Ci whose execution request information Ri is 0 and does not need to be executed. It is determined whether or not (S109). It is assumed that the cartridge Ci satisfying the conditional expression (6) needs to detect the remaining amount of toner by changing the execution request information Ri to 1 (S110).
Iy _Ci ≦ Im × Z (6)
Even if the CPU 205 executes the remaining toner detection at the subsequent toner remaining amount detection execution timing for the cartridge Ci whose execution request information Ri is 0 according to the conditional expression (6), the CPU 205 uses the threshold function Fth of the expression (2). It is determined whether or not the obtained toner remaining amount detection execution interval is satisfied.

  The coefficient Z in the conditional expression (6) is an error correction coefficient for preventing an increase in the number of executions of the remaining toner amount due to an estimated remaining toner amount error obtained from the output of the toner consumption amount estimation unit 208. And a value of 1 or more. This is because the estimated toner remaining amount is used to calculate the next toner remaining amount detection minimum execution interval Im.

  When the estimated toner remaining amount is estimated to be less than the actual toner remaining amount, the next toner remaining amount detection minimum execution interval Im is calculated to be shorter than the actual toner remaining amount detection execution interval. For this reason, when the concurrent determination is performed at the shorter next toner remaining amount detection minimum execution interval Im, the toner remaining amount detection of the cartridge Ci that should have been executed in parallel with the current toner remaining amount detection is performed. It may not be executed.

  When such a cartridge Ci exists, it is necessary for the cartridge that performs the remaining toner detection this time to perform the remaining toner detection at a timing earlier than the timing at which the remaining toner detection needs to be performed next. . As a result, in addition to the execution timing of the cartridge having the shortest interval for detecting the remaining amount of toner, the execution timing of the remaining amount of toner is detected, and the printing operation is performed in order for the image forming apparatus to detect the remaining amount of toner. The number of times of stopping will increase.

  For this reason, the error correction coefficient Z is set to a value of 1 or more, and the next toner remaining amount detection minimum execution interval Im is corrected to be longer in preparation for the case where the estimated toner remaining amount is estimated to be smaller. This prevents an increase in downtime. In this embodiment, it is assumed that the estimation accuracy of the toner consumption estimation unit 208 is sufficiently good, and Z = 1.

When the determination of the cartridge to be subjected to the toner remaining amount detection is completed by the above processing, the CPU 205 performs the toner remaining amount detection for all the cartridges Ci whose execution request information Ri is 1 in order to simultaneously execute the toner remaining amount detection. The detection simultaneous execution process is started (S111).
The CPU 205 interrupts the printing operation to execute the remaining toner amount detection (S151). Then, the development drive motor 211 that rotates the toner stirring member 305 of the cartridge Ci whose execution request information Ri is 1 is driven at a speed for executing the remaining toner detection, and the other development drive motors 211 are stopped (S152, S153). , S154).

When the CPU 205 rotates the toner stirring member 305, the CPU 205 requests the remaining toner amount detection unit 207 to execute the remaining toner amount detection for the cartridge Ci whose execution request information Ri is 1 (S155). The remaining toner amount detection unit 207 calculates the remaining toner amount A by the above-described toner remaining amount detection process, and sends the remaining toner amount A _Ci to the CPU 205 for the cartridge Ci whose execution request information Ri is 1 (S155).

When the CPU 205 receives the remaining toner amount A _Ci from the remaining toner amount detection unit 207, the CPU 205 obtains the remaining toner amount detection execution threshold value Wth _Ci for the cartridge Ci whose execution request information Ri is 1 using Equation (2) (S156). , S157). Then, the reference toner consumption amount Wb _Ci is updated with the current cumulative toner consumption amount Win _Ci (S158).
Nothing is performed for the cartridge Ci whose execution request information Ri is 0 (S156).

  When the toner remaining amount detection process is completed, the CPU 205 sets the drive speed of the development drive motor 211 changed or stopped in S152, S153, and S154 to a speed for a normal print operation (S159). Finally, the CPU 205 restarts the printing operation (S160), and completes the toner remaining amount detection simultaneous execution process and the toner remaining amount detection concurrent determination process.

(Operation example of toner remaining amount detection parallel determination processing)
Next, how the toner remaining amount detection concurrent determination process solves the increase in downtime and the shortening of the cartridge life due to the toner remaining amount detection execution will be described with reference to FIG. FIG. 8 is a diagram for explaining how the remaining amount of toner is detected by the change in the remaining amount of toner in each cartridge and the concurrent determination processing of the remaining amount of toner. In order to simplify the following description, FIG. 8 illustrates the toner remaining amount only for the two cartridges C1 and C2, and the estimated toner remaining amount obtained using the output of the toner consumption amount estimation unit 208. And the actual remaining toner amount are assumed to be equal with no error.

In FIG. 8, at time 0, the cartridge C1 is in a new state where (estimated toner remaining amount) = (actual toner remaining amount) = 100%, A _C1 = 100%, Wth _C1 = 25%, Np _C1 = It is assumed that 0 sheets, Wint _C1 = 0%, and Wb _C1 = 0%. Further, in the cartridge C2, (estimated toner remaining amount) = (actual toner remaining amount) = 30%, A _C2 = 30%, Wth _C2 = 7.5%, Np _C2 = 0 sheets, Wint _C2 = 0 % And Wb _C2 = 0%.

When the CPU 205 repeats the printing operation, Wint and Np increase in the cartridges C1 and C2. At time 1 shown in FIG. 8A, since the cartridge C2 satisfies the condition of the toner remaining amount detection parallel determination processing S101, the CPU 205 sets execution request information R2 = 1. At this time, since the cartridge C1 does not satisfy the condition of S101, the execution request information R1 = 0 is set. The CPU 205 obtains the toner consumption amount change α _Ci (corresponding to the slope of the graph in FIG. 8) for each of the cartridges C1 and C2. It is assumed that the toner consumption amount variation α of the cartridges C1 and C2 shown in FIG. 8 is obtained as α _C1 = 5 and α _C2 = 3, respectively, in order to simplify the subsequent calculation.

The CPU 205 obtains the next toner remaining amount detection minimum execution interval Im for the cartridge C2. Since the cartridge C2 at the time 1 is Wint _C2 = Wth _C2 = 7.5%, Im = Ix _C2 = 0.25 × (30% − (7.5% −0%)) / 3 = 1.87 Is required.
Next, the CPU 205 obtains the remaining toner amount detection execution interval Iy _C1 for the cartridge C1. Since the wint of the cartridge C1 at the time 1 is 12.5% which is 5/3 times the toner consumption of the cartridge C2, Iy _C1 = (25% − (12.5% −0%)) / 5 = 2.5 is required.

The CPU 205 compares the obtained Im and Iy _C1 with the conditional expression (6), determines that Iy _C1 (= 2.5) ≦ Im (= 1.87) is not satisfied, and detects the remaining amount of toner for the cartridge C1. It is determined (determined) that no parallel processing is performed (R1 = 0 remains). The CPU 205 requests the remaining toner amount detection unit 207 to detect the remaining amount of toner in the cartridge C2 while only the developing drive motor 221M of the cartridge C2 is driven at a low speed.
As a result of the toner remaining amount detection, the CPU 205 acquires the actual toner remaining amount 22.5% of the cartridge C2. The CPU 205 updates values to A _C2 = 22.5%, Wth _C2 = 5.6%, and Wb _C2 = 7.5%, respectively.

Thereafter, the printing operation is resumed, and after a while, at time 2 shown in FIG. 8B, the cartridge C2 satisfies the condition of the toner remaining amount detection parallel determination processing S101, and the CPU 205 sets the execution request information as R1 = 0, R2 = 1. Set to each. The CPU 205 performs the same processing as that at the time point 1 so that Im = (0.25 × (22.5% −5.6%)) / 3 = 1.4, Iy _C1 = (25% − (21.8) % -0%)) / 5 = 0.64.
The CPU 205 compares Im and Iy _C1 with the conditional expression (6), determines that the condition is satisfied from Iy _C1 (= 0.64) ≦ Im (= 1.4), and executes the execution request information R1 of the cartridge C1. Is changed to 1.

The CPU 205 requests the remaining toner amount detection unit 207 to detect the remaining amount of toner in the cartridges C1 and C2 while driving the development drive motors 221Y and 221M of the cartridges C1 and C2 at a low speed.
As a result of the toner remaining amount detection, the CPU 205 acquires the actual toner remaining amount as 78.2% for the cartridge C1 and 16.9% for the cartridge C2. The CPU 205 determines that the cartridge C1 has A _C1 = 78.2%, Wth _C1 = 19.6%, and Wb _C1 = 21.8.
%, The value of the cartridge C2 is updated to A _C2 = 16.9%, Wth _C2 = 4.2%, and Wb _C2 = 13.1%, respectively.

Similarly, when the cartridge C2 satisfies the condition of the toner remaining amount detection concurrent determination process S101 at time 3 in FIG. 8C, the CPU 205 sets the execution request information to R1 = 0 and R2 = 1. The CPU 205 has Im = 0.25 × (16.9% −4.2%) / 3 = 1.1, Iy _C1 = (19.6% − (28.8% −21.8%)) / 5 = 2.5 respectively.
Then, according to conditional expression (6), the CPU 205 does not satisfy the condition of Iy _C1 (= 2.5) ≦ Im (= 1.1), and does not perform the remaining toner detection (R1 = 0 remains). ), And at time point 3, only the remaining amount of toner is detected for the cartridge C2.

Here, the description will be made by paying attention to the estimated timing of the toner remaining amount detection execution of the cartridge C1 indicated by a star in FIG.
At time 2 shown in FIG. 8B, Im and Iy _C1 are compared by the conditional expression (6) by the toner remaining amount detection concurrent determination processing S109, and it is determined that the condition is satisfied from Iy _C1 ≦ Im. As a result, the toner remaining amount detection execution timing of the cartridge C1 is the closest toner remaining amount detection timing among the remaining toner detection execution timings of other cartridges before the estimated timing indicated by an asterisk. Carried forward.

  As described above, in the toner remaining amount detection concurrent determination process, control is performed so that the remaining toner amount detection is executed simultaneously with the remaining toner amount detection execution timing of another cartridge whose toner remaining amount detection execution timing is close. Accordingly, it is possible to reduce the number of executions of the toner remaining amount detection as the entire image forming apparatus and execute the toner remaining amount detection only at a timing when the toner remaining amount detection is originally required. As a result, it is possible to detect the remaining amount of toner at intervals that satisfy sufficient accuracy.

As described above, according to the present exemplary embodiment, it is determined whether or not the toner remaining amount detection for a plurality of cartridges is simultaneously performed by the toner remaining amount detection concurrent determination process. The remaining amount detection is controlled. In other words, at the timing of executing the remaining toner detection in any one of the cartridges, whether to detect the remaining toner in other cartridges at the same time is predicted, and the timing until the next remaining toner detection is predicted. Judging.
This minimizes the number of toner remaining detections, reduces the number of toner remaining detections (unnecessary toner remaining detection) for each cartridge, reduces downtime due to toner remaining detection, and shortens cartridge life. Both can be suppressed.

In this embodiment, in the toner remaining amount detection concurrent determination processing, the toner remaining amount detection execution determination is performed based on the toner remaining amount. However, the present invention is not limited to this. What is necessary is just to be performed based on what can be predicted. For example, the toner remaining amount detection execution determination may be performed based on the number of prints. In this case, when the number of prints reaches a preset number (corresponding to Yes in S101 in FIG. 1), it is determined that the remaining toner amount needs to be detected, and the execution request information Ri is set to 1. (Corresponding to S103 in FIG. 1).
The preset number of sheets can be obtained from, for example, the toner consumption amount inclination α obtained from the equation (3) and the remaining amount of toner. Then, the expected number of prints until the execution of the remaining toner amount detection for the cartridge whose execution request information Ri is 0 at the present time, and the remaining toner amount detection for the cartridge whose execution request information Ri is 1 are executed next. Compare the expected number of prints to be needed. If the former expected number of prints is less than or equal to the latter number of prints, the execution request information Ri of the former cartridge is set to 1.
As described above, the timing (time point) at which the former cartridge is predicted to satisfy a preset condition thereafter is set to 1 in the former cartridge execution request information. That is, when the timing is the same as or earlier than the timing when the latter cartridge is predicted to satisfy the preset condition next, the execution request information Ri of the former cartridge is set to 1. In this way, the remaining toner amount detection determination process may be performed.

  Further, the detection method of the toner remaining amount detection means is not limited to the above-described optical detection method. In other words, the present invention can be suitably applied if the image forming apparatus is provided with toner remaining amount detecting means that affects the downtime and the life of the cartridge by executing the toner remaining amount detection. . Further, the toner remaining amount estimating means is not limited to the above-described pixel count method. That is, any means capable of estimating the remaining amount of toner, such as a method based on the number and area of printed recording materials, may be used.

Example 2 will be described below.
(Configuration of image forming apparatus)
In the above-described first embodiment, the method of the toner remaining amount detection concurrent determination process in the configuration in which the toner remaining amount detection can be independently performed for each cartridge has been described. However, an image forming apparatus having a combination of cartridges that cannot independently detect the remaining amount of toner due to restrictions on the configuration of the apparatus is conceivable. In this embodiment, a case where the remaining toner amount detection determination process is applied to such an apparatus will be described.

FIG. 9 is a block diagram of an engine control unit of the image forming apparatus according to the present exemplary embodiment.
In the image forming apparatus of the present embodiment in order to realize the demand for cost reduction of the apparatus, the photosensitive drum 5 of the cartridge 22 storing Y toner, M toner, and C toner, the developing roller 8R, and the toner stirring member The development drive motor 211 that drives the motor 305 is shared. Here, the toner stirring member 305 corresponds to a driven member that is driven at least when the remaining amount of developer is detected. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

In this embodiment, when the toner agitating member 305Y is rotated in order to detect the remaining toner amount in the cartridge 22Y, the toner agitating members 305M and 305C of the cartridge 22M and the cartridge 22C simultaneously start to rotate simultaneously. For this reason, even when the toner remaining amount detection is executed by the cartridge 22Y and the toner remaining amount detection of the cartridges 22M and 22C is not executed, the toner agitating member 305 of the cartridges 22M and 22C rotates, so the stored toner Deterioration will progress.
Similarly, when the toner agitating member 305Y of the cartridge 22Y is rotated, the developing rollers 8MR and 8CR of the cartridges 22M and 22C are also rotated, so that the developing roller 8R and the photosensitive drum 5 are driven in contact with each other, thereby the photosensitive member. The surface of the drums 5M and 5C is consumed.

Therefore, when the remaining toner amount detection is executed for any of the cartridges 22Y, 22M, and 22C, the durable life of the cartridge is shortened regardless of whether the remaining toner amount detection is executed for the other cartridges. For this reason, it can be said that a method of detecting the remaining amount of toner in the cartridges 22Y, 22M, and 22C should be performed in parallel.
Since the cartridges 22Y, 22M, and 22C always detect the remaining amount of toner at the same time, in this embodiment, these three cartridges are referred to as non-independent cartridges (non-independent cartridges). Here, the non-independent cartridge corresponds to several image forming units among the plurality of image forming units.

(Judgment on detection of remaining amount of toner in this embodiment)
Next, the remaining toner amount detection determination process in this embodiment will be described with reference to FIG. The difference from the toner remaining amount detection parallel determination process in the first embodiment is that the non-independent cartridge execution request correction process (S1001, S1002) is executed after the execution request information Ri is obtained. Since other processes are the same as those in the first embodiment, description thereof is omitted.

The CPU 205 executes non-independent cartridge execution request correction processing (S1001) when there is even one cartridge whose execution request information Ri obtained by the processing of S101, S102, and S103 is 1. As a result, the execution request information Rj of the cartridge Cj that is not independent of the cartridge Ci whose execution request information Ri is 1 is also changed to 1 (S1003, S1004, S1005).
Further, when the execution request information Ri of the cartridge Ci is changed from 0 to 1 in S110, the CPU 205 similarly executes the non-independent cartridge execution request correction process. As a result, the execution request information Rj of the cartridge Cj that is not independent of the cartridge Ci whose execution request information Ri has been changed from 0 to 1 is also changed to 1 (S1002).

The CPU 205 can always make the execution request information Ri of all non-independent cartridges equal to the same value by the above processing, and always execute the toner remaining amount detection of non-independent cartridges simultaneously in the toner remaining amount detection simultaneous execution processing of S111. It becomes possible to make it.
Thereby, the non-independent cartridge can execute the toner remaining amount detection in accordance with the toner remaining amount detection execution timing of the cartridge having the shortest toner remaining amount detection execution interval.

As described above, according to the present embodiment, even when there is a combination of cartridges (non-independent cartridges) that cannot independently detect the remaining amount of toner due to the common development drive motor, the same as in the first embodiment. The effect of can be obtained.
In this embodiment, it is possible to perform the toner remaining amount detection parallel determination process in alignment with the cartridge having the earliest toner remaining amount detection execution timing (toner remaining amount detection execution interval) among the non-independent cartridges. As a result, it is possible to suppress both the occurrence of downtime due to the execution of the remaining toner detection and the shortening of the cartridge life.

  DESCRIPTION OF SYMBOLS 5 ... Photosensitive drum, 8 ... Developing device, 22 ... Cartridge, 205 ... CPU, 207 ... Toner remaining amount detection part, 301 ... Toner accommodating part

Claims (3)

Developing means for developing the electrostatic latent image formed on the image carrier with a developer;
A developer accommodating portion for accommodating a developer used in the developing means;
A remaining amount detecting means for detecting the remaining amount of the developer in the developer accommodating portion;
In the image forming apparatus including a plurality of image forming units provided so as to be replaceable with respect to the image forming apparatus main body,
An execution unit for performing a developer remaining amount detection by the remaining amount detection unit for a condition satisfaction unit that satisfies a preset condition among the plurality of image forming units;
The execution means includes
Among the plurality of image forming units, a condition unsatisfied unit that does not satisfy a preset condition, when the remaining amount of developer is detected by the remaining amount detecting unit with respect to the condition satisfying unit. Then, there is a condition dissatisfied unit whose timing that is predicted to satisfy a preset condition is the same as or earlier than the timing that the condition satisfying unit is predicted to satisfy the preset condition next. If you want to
An image forming apparatus, wherein the remaining amount of developer for the condition unsatisfactory unit is detected in parallel with the condition satisfaction unit. The preset condition is a threshold of the developer remaining amount set from the detection result of the developer remaining amount detection by the remaining amount detecting means,
From the detection result of the developer remaining amount detection by the remaining amount detecting means, setting means for setting a threshold of the remaining amount of developer;
A remaining amount estimating means for estimating the remaining amount of developer in the developer accommodating portion as needed;
With
2. The image formation according to claim 1, wherein when a remaining amount estimated by the remaining amount estimating unit reaches a threshold set by the setting unit, a preset condition is satisfied. apparatus. A driven member that is provided for each of the plurality of image forming units and constitutes the developing unit, and is provided with a driven member that is driven at least when the remaining amount of developer is detected,
The driven members of some image forming units among the plurality of image forming units are configured to be interlocked,
When the execution means intends to execute the remaining developer amount detection for one of the several image forming units, the developer for all of the several image forming units. The image forming apparatus according to claim 1, wherein the remaining amount is detected.

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