JP7537331B2 - Image forming apparatus and method for controlling the image forming apparatus - Google Patents

Description

The present invention relates to an image forming apparatus and a method for controlling an image forming apparatus.

There is known an electrophotographic image forming apparatus that adheres toner to an electrostatic latent image formed on a photoreceptor and transfers the adhered toner to a recording medium such as paper. This type of image forming apparatus detects the remaining amount of toner by accumulating detection values corresponding to the electrostatic capacitance generated by a toner detection member in a toner container and averaging the accumulated detection values (see, for example, Patent Document 1).

In addition, in an image forming device in which a processor such as a CPU (Central Processing Unit) is installed for each of multiple functional units, if one of the CPUs goes out of control, one of the other CPUs acquires the progress of the processing by the out-of-control CPU, transmits it to the other CPU, and restarts the out-of-control CPU (see, for example, Patent Document 2).

For example, if a detection CPU that detects the remaining amount of toner by averaging the toner amount detected a predetermined number of times goes out of control and is restarted by another CPU, the detection CPU acquires the detection value a predetermined number of times again and detects the remaining amount of toner. For example, a CPU that performs image formation processing when there is remaining toner cannot start image formation processing until the restarted detection CPU redetects the remaining amount of toner. Therefore, the longer it takes to redetect the remaining amount of toner, the longer it will be from restarting the detection CPU to starting image formation processing.

The disclosed technology was developed in consideration of the above-mentioned problems, and aims to shorten the time between restarting the controller that detects the remaining toner amount and starting the image formation process.

In order to solve the above technical problems, an image forming apparatus according to one embodiment of the present invention includes a toner container that stores toner, an image forming unit that forms an image using the toner in the toner container, a first controller that controls the image forming unit, a sensor that detects the amount of toner in the toner container and outputs the amount of toner at a predetermined frequency as toner amount information, and a second controller that calculates the remaining amount of toner using a predetermined number of the toner amount information and outputs toner end information to the first controller when the calculated remaining amount of toner is equal to or less than a predetermined amount, and when the first controller detects an abnormality in the second controller, it restarts the second controller and masks the acceptance of the toner end information until the restarted second controller is able to output the toner end information, and the restarted second controller calculates the remaining amount of toner using the toner amount information received from the sensor before the restart and the toner amount information received from the sensor after the restart.

This reduces the time between restarting the controller that detects the remaining toner amount and starting the image formation process.

1 is a block diagram showing an example of an image forming apparatus according to a first embodiment of the present invention. 2 is a waveform diagram showing an example of a toner amount signal output from a toner end sensor in FIG. 1 . FIG. 2 is a block diagram showing an example of the functions of a sub-CPU in FIG. 1 . FIG. 4 is an explanatory diagram showing an overview of the operation of the sub-CPU of FIG. 3; 2 is a timing chart showing an example of an operation of the image forming apparatus shown in FIG. 1 . 1. FIG. 4 is a timing chart showing another example of the operation of the image forming apparatus of FIG. FIG. 11 is a timing chart showing an example of the operation of another image forming apparatus.

The following describes the embodiments with reference to the drawings. In the following, the same reference numerals as the signal names are used for signal lines that transmit information such as signals. Note that in each drawing, the same components are given the same reference numerals, and duplicate explanations may be omitted.

First Embodiment
Fig. 1 is a block diagram showing an example of an image forming apparatus according to a first embodiment of the present invention. The image forming apparatus 100 shown in Fig. 1 includes an image forming unit 10, a plurality of toner containers 20 (20C, 20M, 20Y, 20K), a plurality of toner end sensors 30 (30C, 30M, 30Y, 30K), a sub-CPU 40, and a main CPU 50. Note that the image forming apparatus 100 may include a CPU other than the sub-CPU 40 and the main CPU 50. For example, the image forming unit 10 includes a CPU.

For example, the image forming device 100 is a multifunction device such as an MFP (Multi-Function Peripheral) having a copy function, a printer function, a scanner function, a fax function, etc. The image forming device 100 employs an electrophotographic method in which toner is applied to an electrostatic latent image formed on a photoconductor, and the applied toner is transferred to a recording medium such as paper. Note that it is sufficient for the image forming device 100 to have at least a printer function.

The image forming unit 10 has, for example, a writing unit, a photosensitive drum, a developing device, a conveyor belt, and a fixing device, all of which are not shown. The writing unit converts image information processed by an image processing unit, also not shown, into optical information. The photosensitive drum is uniformly charged by a charger, also not shown, and then exposed to laser light containing the optical information converted by the writing unit. An electrostatic latent image is formed on the photosensitive drum by the exposure.

The developing device develops the electrostatic latent image on the photosensitive drum to form a toner image on the photosensitive drum. The toner image on the photosensitive drum is transferred onto a recording medium, such as paper, transported by a transport belt. The fixing device fixes the toner image onto the recording medium. The recording medium onto which the image has been transferred is then discharged from the image forming device 100. Note that in this embodiment, a full-color image is transferred onto the recording medium using four colors of toner. For this reason, the image forming unit 10 has a writing unit, photosensitive drum, and developing device for each of the colors cyan, magenta, yellow, and black.

Toner container 20C contains cyan toner, and toner container 20M contains magenta toner. Toner container 20Y contains yellow toner, and toner container 20K contains black toner. Hereinafter, cyan will also be referred to as C color, and magenta will also be referred to as M color. Yellow will also be referred to as Y color, and black will also be referred to as K color.

The toner end sensor 30C is disposed in the toner container 20C. The toner end sensor 30M is disposed in the toner container 20M. The toner end sensor 30Y is disposed in the toner container 20Y. The toner end sensor 30K is disposed in the toner container 20K.

The toner end sensor 30C detects the amount of C color toner in the toner container 20C and outputs a toner amount signal INFC indicating the detected amount of toner to the sub-CPU 40. The toner end sensor 30M detects the amount of M color toner in the toner container 20M and outputs a toner amount signal INFM indicating the detected amount of toner to the sub-CPU 40.

The toner end sensor 30Y detects the amount of Y color toner in the toner container 20Y and outputs a toner amount signal INFY indicating the detected amount of toner to the sub-CPU 40. The toner end sensor 30K detects the amount of K color toner in the toner container 20K and outputs a toner amount signal INFK indicating the detected amount of toner to the sub-CPU 40.

Each toner end sensor 30 detects the amount of each toner at a predetermined frequency and outputs a toner amount signal INF (INFC, INFM, INFY, INFK) to the sub-CPU 40 at a predetermined frequency. The toner amount signal INF is an example of toner amount information that indicates the amount of toner in each toner container.

The sub-CPU 40 calculates the remaining amount of toner in each toner container 20 based on receiving a predetermined number of toner amount signals INF from each toner end sensor 30. When the sub-CPU 40 detects that the remaining amount of toner in each toner container 20 is equal to or less than a predetermined amount, it determines that the toner is depleted and outputs a toner end signal TEND (TENDC, TENDM, TENDY, TENDK) to the main CPU 50.

The toner end signal TENDC is output when it is determined that the C toner has run out. The toner end signal TENDM is output when it is determined that the M toner has run out. The toner end signal TENDY is output when it is determined that the Y toner has run out. The toner end signal TENDK is output when it is determined that the K toner has run out. The sub-CPU 40 is an example of a second controller that detects when toner has run out in each toner container 20. The toner end signal TEND is an example of toner end information.

When the image forming device 100 is a monochrome printer, the image forming device 100 does not have toner containers 20C, 20M, and 20Y, but has a K toner container 20K. The sub-CPU 40 then detects the remaining amount of K toner. The toners used in the image forming device 100 are not limited to C, M, Y, and K, and the colors are not limited to four.

The main CPU 50 controls the overall operation of the image forming apparatus 100, and also controls the image forming unit 10 to cause the image forming unit 10 to form an image. For example, when the main CPU 50 receives at least one of the toner end signals TENDC, TENDM, TENDY, and TENDK from the sub-CPU 40, it causes the image forming unit 10 to stop forming an image. Then, the main CPU 50 causes the display screen of the operation unit (not shown) to display that the toner has run out for each toner color.

The main CPU 50's serial port (not shown) and the sub-CPU 40's serial port (not shown) are connected to each other, for example, via a serial bus SBUS. The main CPU 50 can monitor the operating state of the sub-CPU 40 by communicating with the sub-CPU 40 via the serial bus SBUS.

When the main CPU 50 detects an abnormality in the sub-CPU 40, it restarts the sub-CPU 40. Here, an abnormality in the sub-CPU 40 is a malfunction of the sub-CPU 40 due to noise, or a runaway of a program executed by the sub-CPU 40, etc. The main CPU 50 masks the acceptance of the toner end signal TEND until the restarted sub-CPU 40 is able to output the toner end signal TEND. The main CPU 50 is an example of a first controller.

Figure 2 is a waveform diagram showing an example of the toner amount signal INF output from the toner end sensor 30 in Figure 1. Each toner end sensor 30 outputs a toner amount signal INF with a higher frequency to the sub-CPU 40 as the remaining amount of toner increases, and outputs a toner amount signal INF with a lower frequency to the sub-CPU 40 as the remaining amount of toner decreases. This allows the sub-CPU 40 that receives the toner amount signal INF to detect the frequency of the signal and thus detect the remaining amount of toner in each toner container 20. The method of detecting the frequency is described in Figure 3 and subsequent figures.

Figure 3 is a block diagram showing an example of the functions of the sub-CPU 40 in Figure 1. The sub-CPU 40 has four pulse counting units 42 (42C, 42M, 42Y, 42K) corresponding to the colors C, M, Y, and K, respectively, a RAM (Random Access Memory) 44, an average value calculation unit 46, and a toner end determination unit 48. The RAM 44 is an example of a memory accessible by the sub-CPU 40. The RAM 44 may be provided outside the sub-CPU 40. The average value calculation unit 46 and the toner end determination unit 48 may be realized by a control program executed by the sub-CPU 40, or may be realized by hardware.

Pulse counting unit 42C counts the number of pulses per predetermined time of toner amount signal INFC corresponding to color C. Pulse counting unit 42M counts the number of pulses per predetermined time of toner amount signal INFM corresponding to color M. Pulse counting unit 42Y counts the number of pulses per predetermined time of toner amount signal INFY corresponding to color Y. Pulse counting unit 42K counts the number of pulses per predetermined time of toner amount signal INFK corresponding to color K. For example, the predetermined time is 5 ms.

Each pulse counting unit 42 sequentially stores the count values counted at each predetermined time in the RAM 44. For example, each pulse counting unit 42 repeats the operation of sequentially storing 60 count values CT (CT1 to CT60) in the RAM 44. It takes 300 ms (5 ms x 60 times) for the 60 count values CT to be stored in the RAM 44 from each pulse counting unit 42.

The frequency of the toner amount signal INF is higher as the amount of remaining toner increases and is lower as the amount of remaining toner decreases. Therefore, the count value CT counted by each pulse counting unit 42 is larger as the amount of remaining toner increases and is smaller as the amount of remaining toner decreases. The count value CT is an example of toner amount information that indicates the amount of toner in each toner container 20.

The average value calculation unit 46 calculates the average value of the 60 count values CT stored in the RAM 44 for each toner color. The average value calculation unit 46 outputs the calculated average value for each toner color to the toner end determination unit 48. Note that the average value calculation unit 46 may take the value obtained by dividing the integrated value of the 60 count values CT by 60 as the average value CTAV, or may take the integrated value of the 60 count values CT itself as the average value CTAV.

When the average value for each toner color is equal to or less than a predetermined threshold value, the toner end determination unit 48 determines that the toner in the corresponding toner container 20 is depleted, and outputs a toner end signal TEND (TENDC, TENDM, TENDY, or TENDK) to the main CPU 50.

Figure 4 is an explanatory diagram showing an overview of the operation of the sub-CPU 40 in Figure 3. Detailed explanations of operations similar to those explained in Figure 3 will be omitted. For ease of understanding, Figure 4 explains the operation of calculating the remaining amount of C color toner. The operation of calculating the remaining amount of M, Y, and K color toner is also similar to that in Figure 4, and is performed in parallel with the operation of calculating the remaining amount of C color toner.

The pulse counting unit 42C repeatedly counts the number of pulses of the toner amount signal INFC for 5 ms, and sequentially stores the 60 count values CT1 to CT60 counted over 300 ms in the RAM 44. The average value calculation unit 46 calculates the average value CTAV of the 60 count values CT over the 300 ms stored in the RAM 44, and outputs the calculated average value CTAV to the toner end determination unit 48.

When the average value CTAV is greater than a preset threshold value CVT, the toner end determination unit 48 determines that there is toner in the toner container 20C and outputs a high level H toner end signal TENDC to the main CPU 50. When the average value CTAV is equal to or less than the threshold value CVT, the toner end determination unit 48 determines that there is no toner in the toner container 20C and outputs a low level L toner end signal TENDC to the main CPU 50.

Figure 5 is a timing diagram showing an example of the operation of the image forming apparatus 100 of Figure 1. Figure 5 shows an example of a control method for the image forming apparatus 100. In Figure 5, for ease of explanation, an example of the operation of calculating the remaining amount of C color toner is also shown. The operation of calculating the remaining amount of M color, Y color, and K color toner is the same as that shown in Figure 5, and is performed in parallel with the operation of calculating the remaining amount of C color toner.

In FIG. 5, the sub-CPU 40 repeats the operation of counting the number of pulses of the toner amount signal INFC for 5 ms every 300 ms 60 times. During the operation period shown in FIG. 5, the sub-CPU 40 operates normally without going out of control. The average value calculation unit 46 performs a calculation to calculate the average value CTAV of the count value CT every 300 ms.

The toner end determination unit 48 compares the average value CTAV obtained by calculation with the threshold value CVT every 300 ms, and outputs a toner end signal TENDC with a logical value according to the comparison result. In other words, the frequency of outputting the toner end signal TENDC according to the comparison result between the average value CTAV and the threshold value CVT (the period for determining the remaining amount of toner) is 300 ms. In the operation shown in FIG. 5, the average value CTAV obtained in the first and second calculations is greater than the threshold value CVT, so the toner end determination unit 48 outputs a high-level toner end signal TENDC.

The main CPU 50 sets the sub-CPU 40 to an acceptance permission state in which acceptance of the toner end signal TENDC is permitted while the sub-CPU 40 is operating normally. In FIG. 5, the internal permission signal used by the main CPU 50 is set to high level H. Then, the main CPU 50 controls the image forming unit 10 to perform an image forming operation every 300 ms.

For example, in the image forming apparatus 100, the image forming operation period required for the image forming unit 10 to create one image is 300 ms. In other words, the determination period for the remaining amount of toner is determined in accordance with the image forming operation period. Note that the determination period may be set to a period shorter than the image forming operation period. However, the greater the number of count values CT used to calculate the average value CTAV, the more accurate and precise the average value CTAV will be.

For this reason, it is preferable that the judgment cycle, which is the frequency at which the toner end signal TENDC is output, is set to the same period as the image-forming operation period. If the judgment cycle is set longer than the image-forming operation period, the image forming unit 10 must wait for the remaining toner amount to be determined after an image-forming operation before starting the next image-forming operation, which reduces operational efficiency. For this reason, the judgment cycle must be set to be shorter than the image-forming operation period.

In the example shown in FIG. 5, for ease of explanation, a 300 ms judgment period during which the pulse count unit 42C and the average calculation unit 46 operate is shown to coincide with a 300 ms image formation period during which the image forming unit 10 performs an image formation operation. However, the 300 ms judgment period and the 300 ms image formation period may not coincide but may be shifted from each other. In this case, it is preferable that a judgment period is set before the image formation period, and whether or not image formation is possible is judged based on the result of judging the remaining amount of toner.

In the example shown in FIG. 5, the average value CTAV obtained in the third calculation is equal to or less than the threshold value CVT, so the toner end determination unit 48 outputs a low-level toner end signal TENDC. In this case, the main CPU 50 sets the sub-CPU 40 to an allowed state in which the toner end signal TENDC is accepted, because the sub-CPU 40 is operating normally. The main CPU 50 then accepts the low-level toner end signal TENDC, detects that the C-color toner has run out, and causes the image forming unit 10 to stop image formation.

Figure 6 is a timing diagram showing another example of the operation of the image forming apparatus of Figure 1. Figure 6 shows an example of a control method for the image forming apparatus 100. Detailed explanations of operations that are the same as those in Figure 5 will be omitted. To make the explanation easier to understand, Figure 6 also shows an example of an operation for calculating the remaining amount of C color toner.

The operation during the first 300 ms in FIG. 6 is the same as that in FIG. 5. At the timing of performing the second calculation, for example, the main CPU 50 detects a runaway of the sub-CPU 40. Then, the main CPU 50 restarts the sub-CPU 40.

Because the logical value of the toner end signal TENDC is indefinite during the 300 ms, including the restart time, the main CPU 50 sets the reception mask state to prohibit reception of the toner end signal TENDC. For example, the reception mask state is set by changing the permission signal used inside the main CPU 50 to a low level. Because the logical value of the toner end signal TENDC is indefinite and the remaining amount of toner is unknown, the main CPU 50 causes the image forming unit 10 to stop image formation.

The restarted sub-CPU 40 receives the toner amount signal INFC that can be received from the toner end sensor 30C during the 300 ms judgment period required to determine the remaining amount of toner, excluding the restart time, and generates a count value CT using the received toner amount signal INFC. In other words, the sub-CPU 40 receives the toner amount signal INFC that can be received from the toner end sensor 30C during the period that is the difference between the image formation operation period and the restart time. In other words, the sum of the restart time of the sub-CPU 40 and the reception period of the toner amount signal INFC received from the toner end sensor 30 after the restart of the sub-CPU 40 is less than the image formation operation period during which one image is formed by the image forming unit 10.

The sub-CPU 40 also reads out the count values CT stored in the RAM 44 300 ms before the restart for the remaining number of times for which the toner amount signal INFC could not be received from the toner end sensor 30C and the count values CT could not be generated. The average value calculation unit 46 then calculates the average value CTAV of the count values CT counted before the restart and the count values CT counted after the restart (a total of 60).

That is, the restarted sub-CPU 40 calculates the remaining amount of C-color toner using the toner amount signal INFC received from the toner end sensor 30C before the restart and the toner amount signal INFC received by the toner end sensor 30C after the restart. In the example shown in FIG. 6, the toner end determination unit 48 determines that there is toner in the toner container 20C and outputs a high-level toner end signal TENDC to the main CPU 50.

As a result, even when the sub-CPU 40 is restarted, the stop period of the image formation operation can be shortened to 300 ms, which is the determination period required to obtain 60 count values CT and calculate the average value CTAV. As a result, the period during which the image forming unit 10 cannot form images due to runaway of the sub-CPU 40 or the occurrence of noise can be minimized, and the deterioration of the performance of the image forming device 100 can be minimized.

300 ms after the start of the restart of the sub-CPU 40, the main CPU 50 sets the toner end signal TENDC to an allowed state that allows it to receive the toner end signal TENDC. Then, the main CPU 50 receives a high-level toner end signal TENDC, which indicates that there is toner remaining, and causes the image forming unit 10 to resume image formation.

That is, the sub-CPU 40 generates the toner end signal TENDC using 60 counter values CT obtained by counting the toner amount signal INFC received from the toner end sensor 30C. This improves the accuracy of the calculation of the remaining amount of toner compared to using the counter values CT stored in the RAM 44 prior to the 300 ms determination period for generating the toner end signal TENDC.

When the main CPU 50 detects an abnormality in the sub-CPU 40, it acquires the operation history of the sub-CPU 40 via the serial bus SBUS, for example, and determines the cause of the abnormality. Then, when there is a possibility that the RAM 44 has been rewritten due to the occurrence of an abnormality in the sub-CPU 40, the main CPU 50 notifies the sub-CPU 40 after reboot of prohibition information not to use the count value CT held in the RAM 44.

The sub-CPU 40 that receives the prohibition information does not use the count value CT stored in the RAM 44 before restart, but calculates the remaining amount of toner using only the count value CT obtained by counting the number of pulses of the toner amount signal INF received from the toner end sensor 30 after restart. This makes it possible to prevent an erroneous average value CTAV from being calculated using an erroneous count value CT stored in the RAM 44, and to prevent a determination of an amount of remaining toner that differs from the actual amount. An example of the operation of the image forming apparatus 100, including the operation of the sub-CPU 40 that receives the prohibition information, is the same as the operation shown in FIG. 7, which will be described later.

Figure 7 is a timing diagram showing an example of the operation of another image forming device. Detailed explanations of the same operations as those in Figures 5 and 6 will be omitted. To make the explanation easier to understand, Figure 7 also shows an example of the operation of calculating the remaining amount of C color toner.

In FIG. 7, as in FIG. 6, the main CPU 50 detects the runaway of the sub-CPU 40 and restarts the sub-CPU 40. The restarted sub-CPU 40 does not use the count value CT stored in the RAM 44 before the restart, but calculates the remaining amount of toner using only the count value CT obtained by counting the number of pulses of the toner amount signal INF received from the toner end sensor 30 after the restart. In this case, the determination period including the restart time is the sum of the restart time and 300 ms. Therefore, the resumption of image formation by the image forming unit 10 is delayed by the restart time.

As described above, in the first embodiment, when the sub-CPU 40 is restarted, the count value CT stored in the RAM 44 before the restart is used for the number of times for which the count value CT cannot be generated corresponding to the restart time. This makes it possible to calculate the average value CTAV of the count value CT within the 300 ms judgment period (i.e., the 300 ms image formation operation period) even if the restart time is included in the 300 ms judgment period.

Therefore, even if the sub-CPU 40 is restarted, the toner end signal TEND can be generated within the 300 ms judgment period. As a result, the period during which the image forming unit 10 cannot form an image due to the sub-CPU 40 going out of control or the occurrence of noise can be minimized, and the degradation of the performance of the image forming device 100 can be minimized. In other words, the time from when the sub-CPU 40, which detects the remaining amount of toner, is restarted to when the image formation process starts can be shortened.

An area for storing 60 count values CT for each color of toner is allocated in the RAM 44 accessible by the sub-CPU 40. Therefore, the count values CT counted by the pulse count unit 42 can be stored sequentially in the RAM 44, and the count values CT counted before restart can be read out from the RAM 44 and used after restart.

If there is a possibility that the RAM 44 has been rewritten due to an abnormality occurring in the sub-CPU 40, after the sub-CPU 40 is restarted, the remaining amount of toner is calculated without using the count value CT stored in the RAM 44 before the restart. This makes it possible to prevent an incorrect average value CTAV from being calculated using an incorrect count value CT stored in the RAM 44, and to prevent a remaining amount of toner from being determined differently from the actual amount.

In the judgment period after the judgment period including the restart time, the sub-CPU 40 generates the toner end signal TEND using 60 counter values CT generated by counting the toner amount signal INF received from the toner end sensor 30. This improves the accuracy of the calculation of the remaining amount of toner compared to using the counter values CT stored in the RAM 44 before the 300 ms judgment period in which the toner end signal TEND is generated.

The present invention has been described above based on each embodiment, but the present invention is not limited to the requirements shown in the above embodiments. These points can be changed without departing from the spirit of the present invention, and can be appropriately determined according to the application form.

10 Image forming unit 20 (20C, 20M, 20Y, 20K) Toner container 30 (30C, 30M, 30Y, 30K) Toner end sensor 40 Sub-CPU
50 Main CPU
42 (42C, 42M, 42Y, 42K) Pulse count unit 44 RAM
46 Average value calculation section 48 Toner end determination section 100 Image forming apparatus CT (CT1 to CT60) Count value CTAV Average value CVT Threshold value INF (INFC, INFM, INFY, INFK) Toner amount signal SBUS Serial bus TEND (TENDC, TENDM, TENDY, TENDK) Toner end signal

JP 2004-086173 A JP 2013-054314 A

Claims (6)

a toner container for storing toner;
an image forming unit that forms an image using the toner in the toner container;
A first controller that controls the image forming unit;
a sensor that detects the amount of toner in the toner container and outputs the detected amount as toner amount information at a predetermined frequency;
a second controller that calculates a remaining amount of toner using a predetermined number of pieces of the toner amount information, and outputs toner end information to the first controller when the calculated remaining amount of toner is equal to or less than a predetermined amount;
having
when the first controller detects an abnormality in the second controller, the first controller restarts the second controller and masks receipt of the toner end information until the restarted second controller is able to output the toner end information;
the restarted second controller calculates the remaining amount of toner by using the toner amount information received from the sensor before the restart and the toner amount information received from the sensor after the restart. a period during which the second controller determines whether the toner is remaining corresponds to an image forming operation period during which one image is formed by the image forming unit;
The image forming apparatus according to claim 1 , characterized in that the sum of the restart time of the second controller and the reception period of the toner amount information received from the sensor after the restart is less than or equal to the image forming operation period for forming one image by the image forming unit. a memory accessible by the second controller;
the second controller stores the toner amount information received from the sensor in the memory;
The restarted second controller
receiving, from the sensor, the toner amount information that can be received during a period of time that is a difference between the image forming operation period and the restart time;
reading the remaining toner amount information necessary for calculating the toner amount information from the memory;
3. The image forming apparatus according to claim 2, wherein the remaining amount of toner is calculated using the toner amount information received from the sensor and the toner amount information read from the memory. When the first controller detects an abnormality in the second controller, the first controller determines a cause of the abnormality, and when there is a possibility that the memory has been rewritten due to the occurrence of the abnormality, notifies the second controller after reboot of use prohibition information for prohibiting the use of the toner amount information held in the memory;
4. The image forming apparatus according to claim 3, wherein the second controller, having received the use prohibition information, calculates the remaining amount of the toner using only the toner amount information received from the sensor after rebooting. 5. The image forming apparatus according to claim 1, wherein the second controller, having calculated the remaining amount of toner after restarting, thereafter calculates the remaining amount of toner using a predetermined number of pieces of toner amount information received from the sensor. 1. A control method for an image forming apparatus having a toner container for storing toner, an image forming unit for forming an image using the toner in the toner container, a first controller for controlling the image forming unit, a sensor for detecting an amount of toner in the toner container and outputting the amount of toner at a predetermined frequency as toner amount information, and a second controller for calculating a remaining amount of toner using a predetermined number of pieces of the toner amount information, and outputting toner end information to the first controller when the calculated remaining amount of toner is equal to or less than a predetermined amount,
when the first controller detects an abnormality in the second controller, the first controller restarts the second controller and masks receipt of the toner end information until the restarted second controller is able to output the toner end information;
the restarted second controller calculates the remaining amount of toner by using the toner amount information received from the sensor before the restart and the toner amount information received from the sensor after the restart.

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