Image formation device, abnormality determination method of sensor in the device, and program

Abstract

To provide an image formation device capable of accurately determining whether or not a plurality of sensors are normal by simple processing, an abnormality detection method of sensors in the image formation device, and a program.SOLUTION: An image formation device 1 includes: a plurality of sensors 21 to 23 that detect a state in the inside of the image formation device 1; a power source 101 that supplies power to the plurality of sensors; a current detection part 102 that detects a current value supplied from the power source to the plurality of sensors; an acquisition part 103 that acquires, as a reference value, a current value supplied from the power source to the plurality of sensors in a state where the plurality of sensors are normal; and a determination part 102 that determines whether or not the plurality of sensors are normal by comparing the current value detected by the current detection part 102 and the reference value.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus such as a copying machine, a printer, or a multifunction peripheral, and a method and program for determining abnormality in a sensor in the apparatus. [Background technology]

[0002] The image forming apparatus described above uses a plurality of sensors, such as a paper passing sensor that detects the passage of a transported sheet, and a detection sensor that detects the characteristics of the sheet.

[0003] An abnormality may occur in a sensor due to a sensor breakdown, a poor connection with a connector, etc. To check whether such a sensor is normal or abnormal, the following can be considered: That is, as shown in Fig. 5, if the sensor is, for example, sensor 20 having a light-emitting element 20a and a light-receiving element 20b, control unit 30 including a CPU can turn on / off light-emitting element 20a made of an LED to check whether there is a change in the output of light-receiving element 20b.

[0004] However, as shown in Fig. 6, there are cases where the light-emitting element 20a and the light-receiving element 20b are blocked by a light-blocking object 200. Also, if the sensor is a reflective sensor, there may be no reflective object present. In such cases, turning the light-emitting element 20a on and off does not change the output of the light-receiving element 20b, making it impossible to confirm whether or not there is an abnormality.

[0005] Also, by measuring the current flowing through one sensor, it is possible to detect a poor connection with the connector or a malfunction in the light-emitting section.However, since multiple sensors are used, providing a current detection circuit for each sensor would require a huge number of ports and circuits.

[0006] 6, if one current detection circuit detects the current values ​​of multiple sensors 20 and attempts to detect sensor abnormalities based solely on changes in the detected current values, the following problem occurs: Since the minimum current varies depending on variations in circuit constants and individual differences between sensors, it is difficult to detect whether a single sensor is abnormal.

[0007] Specifically, assume that in a power supply system with 10 sensors each with a representative current value of 12 mA, a total current value of 120 mA is detected and the system is determined to be normal, and when the total current value is 108 mA, one sensor is determined to be in an abnormal state.

[0008] However, due to variations in circuit constants and individual differences between sensors, there is a possibility that the minimum current value may be 9.2 mA, compared to the representative current value of 12 mA. In this case, even if 10 minimum current values ​​of 9.2 mA are normal, the total current value will be 92 mA (9.2 x 10), and it will be impossible to determine whether any one of them is abnormal.

[0009] Patent document 1 discloses an image forming device that detects the amount of current flowing through multiple controlled objects in response to changes in the output of control signals to the controlled objects, and determines whether the control signal output means is normal or abnormal based on the detected amount of current.

[0010] Patent Document 2 discloses an image forming apparatus in which a current detection resistor is provided in a power supply line of a sheet detection sensor, and a fault in the sheet detection sensor is identified based on the detected current by detecting the current flowing through the current detection resistor. In the image forming apparatus disclosed in Patent Document 2, a FET, which is a switching element, switches the timing at which a current flows through the sheet detection sensor and the timing at which a current flows through the current detection resistor. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Patent Application Publication No. 05-026937 [Patent Document 2] Japanese Patent Application Publication No. 2020-078876 Summary of the Invention [Problem to be solved by the invention]

[0012] However, in the image forming apparatus described in Patent Document 1, the amount of current flowing through the controlled objects is detected in response to switching of the output of control signals to the controlled objects, which means that an abnormality determination is performed for each of the controlled objects, making the abnormality determination process complicated.

[0013] Furthermore, in the image forming apparatus described in Patent Document 2, a current detection resistor is required for each sheet detection sensor, which makes the circuitry enormous. Moreover, because the timing at which current flows to the sheet detection sensor and the timing at which current flows to the current detection resistor are switched, there is also the problem that the abnormality determination process is complicated.

[0014] An object of the present invention is to provide an image forming apparatus that can accurately determine whether a plurality of sensors are normal through simple processing, and a method and program for determining abnormality of sensors in the apparatus. [Means for solving the problem]

[0015] The above object can be achieved by the following means: (1) a plurality of sensors for detecting conditions within the image forming apparatus; a power source for supplying power to the plurality of sensors; a current detection unit that detects a current value supplied from the power source to the plurality of sensors; an acquisition unit that acquires, as a reference value, a current value supplied from the power source to the plurality of sensors when the plurality of sensors are in a normal state; a determination unit that determines whether the plurality of sensors are normal by comparing the current value detected by the current detection unit with the reference value; An image forming apparatus comprising: (2) The image forming apparatus according to the above item (1), wherein the sensor is a sensor having a light emitting element and a light receiving element. (3) The image forming apparatus according to (1) or (2) above, wherein the acquisition unit acquires the reference value at the time when the manufacturing of the image forming apparatus is completed. (4) The image forming apparatus according to the preceding paragraph 1 or 2, wherein the acquisition unit acquires the reference value based on an instruction from a user of the image forming apparatus. (5) The image forming apparatus according to the preceding paragraph 1 or 2, wherein the acquisition unit acquires the reference value when a predetermined number of image formations has been performed in the image forming apparatus. (6) The image forming apparatus according to (1) or (2) above, wherein the acquisition unit acquires the reference value when the sensor is replaced. (7) A control board for controlling the plurality of sensors is provided, 3. The image forming apparatus according to claim 1, wherein the acquisition unit acquires the reference value when the control board is replaced. (8) The image forming apparatus according to (1) or (2), wherein the acquisition unit acquires the reference value when it is determined that the plurality of sensors are in a normal state. (9) The image forming apparatus according to the above item 1 or 2, wherein the determining unit determines whether the plurality of sensors are normal or not during a stabilization operation of image formation in the image forming apparatus. (10) The image forming apparatus according to the above item 1 or 2, further comprising a prediction unit that predicts a failure of the sensor based on a change over time in the current value detected by the current detection unit. (11) A plurality of sensors for detecting conditions within the image forming apparatus; a power source for supplying power to the plurality of sensors; a current detection unit that detects a current value supplied from the power source to the plurality of sensors; An image forming apparatus comprising: an acquisition step of acquiring, as a reference value, a current value supplied from the power source to the plurality of sensors when the plurality of sensors are in a normal state; a determining step of determining whether the plurality of sensors are normal by comparing the current value detected by the current detecting unit with the reference value; A method for determining an abnormality in a sensor in an image forming apparatus, comprising: (12) A plurality of sensors for detecting conditions inside the image forming apparatus; a power source for supplying power to the plurality of sensors; a current detection unit that detects a current value supplied from the power source to the plurality of sensors; A computer of an image forming apparatus including: an acquisition step of acquiring, as a reference value, a current value supplied from the power source to the plurality of sensors when the plurality of sensors are in a normal state; a determining step of determining whether the plurality of sensors are normal by comparing the current value detected by the current detecting unit with the reference value; A program to execute. [Effects of the Invention]

[0016] In the image forming apparatus and sensor abnormality determination method according to the present invention, the current values ​​supplied from a power supply to the plurality of sensors are detected. Furthermore, the current values ​​supplied from the power supply to the plurality of sensors when the plurality of sensors are in a normal state are acquired as reference values. Then, the detected current values ​​are compared with the acquired reference values ​​to determine whether the plurality of sensors are normal.

[0017] If the comparison shows that the detected current values ​​of the multiple sensors are the same as or close to the reference value when the multiple sensors are in a normal state, it can be determined that the multiple sensors are normal. On the other hand, if the detected current values ​​of the multiple sensors are lower than the reference value, it can be determined that at least one of the sensors is abnormal. Therefore, it is possible to accurately determine whether the multiple sensors are normal using simple processing.

[0018] Furthermore, even if there are variations in circuit constants or individual differences between sensors, these are reflected equally in both the detected current value and the reference value, so it is possible to determine whether one sensor is abnormal.

[0019] The program according to the present invention can cause a computer of an image forming apparatus to execute a step of acquiring, as a reference value, a current value supplied from a power supply to a plurality of sensors when the plurality of sensors are in a normal state, and further cause the computer of the image forming apparatus to execute a step of determining whether the plurality of sensors are normal by comparing the current value detected by the current detection unit with the reference value. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a configuration diagram of an image forming apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram of a control unit of the image forming apparatus. [Figure 3] 10 is a flowchart illustrating an example of a process for determining whether or not a sensor has an abnormality, which is executed in the image forming apparatus. [Figure 4] 10 is a flowchart illustrating another example of the process for determining whether or not a sensor has an abnormality, which is executed in the image forming apparatus. [Figure 5] FIG. 1 is a diagram for explaining a problem in the related art. [Figure 6] FIG. 10 is a diagram for explaining the problems of the related art. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0022] 1 is a configuration diagram of an image forming apparatus 1 according to an embodiment of the present invention. In this embodiment, the image forming apparatus 1 is an MFP (Multi-functional Peripheral) that combines the functions of a copier, printer, facsimile machine, image reader, and the like.

[0023] The image forming apparatus 1 includes an automatic document feeder (ADF) 1A, a flatbed scanner 1B, a printer section 1C, a paper feed section 1D, and an operation panel section 1E.

[0024] Automatic document feeder 1A transports documents (sheets) set on a document tray to the reading position of scanner 1B. Scanner 1B reads images from sheet-like documents transported from automatic document feeder 1A or from various documents set on the platen glass, and generates image data.

[0025] In print jobs such as copying, network printing (PC printing), facsimile reception, and box printing, the printer unit 1C forms a color or monochrome image on one or both sides of paper (recording sheet) P. For example, in a copy job, the printer unit 1C forms an image based on image data generated by the scanner 1B.

[0026] The printer unit 1C is equipped with a tandem electrophotographic printer engine, which includes four imaging units 3y, 3m, 3c, and 3k, a print head 6, an intermediate transfer belt 10, and the like.

[0027] Each of the imaging units 3y to 3k includes devices such as a cylindrical photoconductor 4, a charging roller 5, a developing device 7, a cleaner 8, and a cleaning roller 9, as well as a memory (not shown) that stores individual information about the photoconductor 4. The imaging units 3y to 3k have the same basic configuration.

[0028] The print head 6 emits a laser beam LB as light for performing pattern exposure on each of the imaging units 3y to 3k. The laser beam LB is a so-called Gaussian beam whose radiation intensity exhibits an approximately Gaussian distribution.

[0029] The intermediate transfer belt 10 is a member to which a toner image is transferred during the primary transfer. The intermediate transfer belt 10 is wound around a pair of rollers and rotates. Primary transfer rollers 11 are disposed inside the intermediate transfer belt 10 for each of the imaging units 3y, 3m, 3c, and 3k.

[0030] The paper feed section 1D has a plurality of paper feed cassettes 12a, 12b, and 12c, and takes out paper P from any selected paper feed cassette and supplies it to the printer section 1C above.

[0031] In color printing mode, imaging units 3y to 3k concurrently form toner images of four colors: Y (yellow), M (magenta), C (cyan), and K (black). The four color toner images are sequentially transferred (primary transfer) onto a rotating intermediate transfer belt 10. The Y toner image is transferred first, followed by the M toner image, C toner image, and K toner image, superimposed on it. When the primary transferred toner image faces secondary transfer roller 16, it is secondarily transferred onto paper P, which has been conveyed from paper feed unit 1D via timing roller 15. Paper P is then neutralized by separation member 18, passes through fuser 17, and is sent to paper output tray 19. As it passes through fuser 17, the toner image is fixed to paper P by heat and pressure.

[0032] The image forming apparatus 1 has a control unit 100 that controls the entire apparatus, a power supply 200 that supplies power to each part, a polygon motor that scans the laser beam LB on the print head 6, drive motors that drive each part, and solenoids that operate each part.

[0033] The paper feed cassettes 12a, 12b, and 12c of the paper feed section 1D have paper feed rollers 13a, 13b, and 13c, respectively, that supply paper P to the printer section 1C above.

[0034] FIG. 2 is a block diagram showing the configuration of the control unit 100.

[0035] The control unit 100 includes a power supply unit 101, a current detection unit 102, a CPU 103 which is an example of a hardware processor, a RAM 104, a ROM 105, a storage device 106, and the like.

[0036] The control unit 100 is supplied with power (for example, 5 V) from a power supply 200. The power supply unit 101 receives the power supply voltage from the power supply 200 and supplies it as power to each of the multiple sensors 21 to 23, which are loads, either as 5 V or by stepping it down to 3.3 V or the like as necessary. In this embodiment, three sensors are used as the multiple sensors 21 to 23.

[0037] In FIG. 2, thick lines indicate current supply lines, and thin lines indicate signal lines.

[0038] The uses of the multiple sensors 21-23 are not limited, but one example is a paper passage sensor that detects the passage of paper P transported and supplied from each paper feed cassette 12a, 12b, 12c to printer unit 1C. Alternatively, the sensors may be sensors that detect the characteristics of paper P to determine the paper type. Furthermore, sensors 21-23 may be sensors that detect the opening and closing of an opening / closing part of image forming apparatus 1, and in short, they may be sensors that are used to detect the state inside image forming apparatus 1.

[0039] The detection mechanisms of the sensors 21 to 23 are not limited either. As shown in Figures 5 and 6, they may be optical sensors that have a light-emitting element 20a and a light-receiving element 20b and detect the detection target by receiving light emitted from the light-emitting element 20a with the light-receiving element 20b. The optical sensors may be of either a reflective or transmissive type. Furthermore, the sensors 21 to 23 may not be optical sensors, but may be magnetic sensors or the like.

[0040] The current detection unit 102 is provided between the power supply unit 101 and the plurality of sensors 21 to 23. The current detection unit 102 is capable of detecting a total current value, which is the sum of the currents flowing from the power supply unit 101 to the plurality of sensors 21 to 23.

[0041] The CPU 103 performs overall control of the image forming apparatus 1. For example, in response to user instructions, the CPU 103 executes functions such as copying, printing, and scanning, and in this embodiment, it also determines whether or not the sensors 21-23 are malfunctioning. Specifically, at a predetermined timing, the CPU 103 acquires the total current value supplied from the power supply unit 101 to the sensors 21-23 when the sensors 21-23 are in a normal state as a reference value, and stores the reference value in the storage device 106. Also, at a predetermined timing, the CPU 103 compares the total current value of the sensors 21-23 detected by the current detection unit 102 with the reference value stored in the storage device 106. The CPU 103 then determines whether or not any of the sensors 21-23 is malfunctioning due to a poor connection with a connector, a malfunction, or the like. The process of determining whether or not a sensor is malfunctioning will be described later.

[0042] The RAM 104 is a memory that provides a working area when the CPU 103 operates according to an operating program.

[0043] The ROM 105 is a memory for storing the operating program of the CPU 103 and other data.

[0044] The storage device 106 is composed of a hard disk drive (HDD) or a solid state drive (SSD), and stores the above-mentioned reference values, various applications, and other data.

[0045] Next, an example of a process for determining whether or not there is an abnormality in a sensor executed by the image forming apparatus 1 will be described with reference to the flowchart in Fig. 3. This determination process is executed by the CPU 103 operating in accordance with an operating program stored in the ROM 105 or the like.

[0046] When the power supply of the image forming apparatus 1 is turned on, the CPU 103 performs a startup process in step S01. In this startup process, in this embodiment, the current supply unit 101 energizes the plurality of sensors 21 to 23 and maintains the energized state.

[0047] Next, the CPU 103 determines whether it is time to obtain a reference value, which will be described later.

[0048] As described above, the reference value is the total current value supplied from the power supply unit 101 to the plurality of sensors 21-23 when the plurality of sensors 21-23 are in a normal state. In this embodiment, the reference value is stored in advance in the storage device 106 at the time of factory shipment, with it being confirmed that all of the sensors 21-23 are operating normally. After the image forming apparatus 1 starts to be used, the reference value is acquired and updated at a predetermined timing.

[0049] Note that the factory default reference values ​​do not have to exist. In this case, the storage area for the reference values ​​in the storage device 106 may be blank, or a standard value may be stored. However, storing the factory default reference values ​​is preferable because it allows the first abnormality determination process after starting use to be performed more quickly.

[0050] If it is time to obtain the reference value (YES in step S02), in step S03, CPU 103 obtains the total current value of the plurality of sensors 21-23 detected by current detection unit 102 from current detection unit 102. Then, in step S04, CPU 103 stores the obtained total current value of the plurality of sensors 21-23 in storage device 106 as a reference value, and then goes into standby state in step S05. Therefore, the reference value is updated to a new reference value every time the reference value is obtained.

[0051] If it is not time to obtain the reference value in step S02 (NO in step S02), the CPU 103 proceeds to step S05 and enters a standby state.

[0052] Next, in step S06, CPU 103 determines whether a job has been accepted. If a job has not been accepted (NO in step S06), the standby state is maintained in step S05. If a job has been accepted (YES in step S06), the CPU executes the job in step S07, and then determines whether the job has been completed successfully in step S08. If the job has been completed successfully (YES in step S08), the process returns to step S02. If the job has not been completed successfully (NO in step S08), the process proceeds to step S09.

[0053] In step S09, CPU 103 obtains the total current value of the plurality of sensors 21 to 23 from current detection unit 102, and then in step S10 reads out a reference value from storage device 106, and then in step S11 compares the total current value with the reference value.

[0054] As a result of the comparison, CPU 103 determines in step S12 whether or not there is an abnormality in sensors 21 to 23. If it is determined that there is no abnormality (NO in step S23), the process ends. If it is determined that there is an abnormality (YES in step S23), CPU 103 displays a warning on an operation panel or the like in step S13 that there is an abnormality in at least one of sensors 21 to 23, and urges the user to inspect or replace sensors 21 to 23. The warning may be displayed by email to the user. Alternatively, the abnormality determination may be saved in storage device 106 without displaying a warning.

[0055] Here, a specific example of the process for determining whether or not there is an abnormality in the sensors 21 to 23 will be described.

[0056] For example, suppose the reference value stored in storage device 106 is 120 mA, and the threshold value for the difference between the reference value and the total current value for determining an abnormality is set to 12 mA. If the total current value of multiple sensors 21-23 detected by current detection unit 102 is 120 mA, it is determined that there is no abnormality. On the other hand, if the detected value is 108 mA, it is assumed that there is some kind of abnormality in one sensor, and processing such as displaying a warning or storing the information in storage device 106 is performed.

[0057] Next, the timing of acquiring the reference value in step S02 will be described.

[0058] An example of the timing for acquiring the reference value is when a user (including a serviceman) who has confirmed that the image forming apparatus 1 is operating normally issues an instruction via an operation panel or the like to acquire the reference value. Confirming normal operation allows an accurate reference value to be obtained. In this case, the reference value may be detected by the current detection unit 102. Alternatively, the user may use a separate current detection device to detect the current and input the detected value via an operation panel or the like, and the input value may be stored as the reference value.

[0059] Another example of the timing for obtaining the reference value is when the number of times images are formed by the copy function or print function reaches a predetermined number. Since the reference value is updated every predetermined number of times, even if the current value changes due to aging of the sensors 21-23, an appropriate reference value corresponding to this change is obtained, and the presence or absence of an abnormality can be determined with high accuracy. Examples of the predetermined number of times of image formation include 1,000 sheets (1k), 6,000 sheets (6k), 10,000 sheets (10k), and 20,000 sheets (20k).

[0060] Another example of the timing for acquiring the reference value is when at least one of the sensors 21-23 is replaced due to replacement of a paper feed unit or the like in which the sensors 21-23 are mounted. Even if the current value differs between the sensor before and after replacement, an appropriate reference value corresponding to the current value of the replaced sensor is acquired and updated. Note that whether a sensor has been replaced may be determined automatically by the image forming apparatus 1 or based on user input.

[0061] Another example of the timing for acquiring the reference value is when some or all of the boards of the control unit that controls the sensors 21 to 23 are replaced. When some or all of the boards of the control unit that controls the sensors 21 to 23 are replaced, the detected total current value may differ depending on the board. For this reason, an appropriate reference value corresponding to the new board after replacement is acquired and updated.

[0062] Another example of the timing for acquiring the reference value is the timing when it is determined that multiple sensors are in a normal state. In other words, when the image forming apparatus 1 is in normal use, if the mode in which the sensors 21-23, whose presence or absence of an abnormality is to be checked, are operating ends normally, it is determined that there is no abnormality in those sensors 21-23. Then, the reference value is acquired and updated in this state.

[0063] For example, if the image forming apparatus 1 has three paper feed cassettes 12a to 12c as shown in Figure 1, paper is fed from the lowest paper feed cassette 12c. When the paper P passes through the duplex transport path and printing is completed normally, it is determined that all of the sensors 21 to 23 that operate according to that print mode are normal, and the reference values ​​are acquired and updated.

[0064] If it is not possible to confirm that all of the sensors 21 to 23 to be checked are normal in a single print mode, the reference values ​​are updated by activating all of the sensors 21 to 23 through a combination of several print modes. As an example, the reference values ​​are acquired and updated when all of the jobs executed before the image forming apparatus 1 was turned off, including "single-stage paper feed," "two-stage paper feed," "three-stage paper feed," and "double-sided printing," have been completed without any abnormalities.

[0065] In a configuration in which the detection state of sensors 21-23 can be changed by operating a motor or the like rather than by normal operation, the operation of the motor or the like confirms that the sensors are normal, and then the reference values ​​are acquired and updated. As an example, there is an image forming apparatus in which a paper feed cassette mechanism that stores paper has a motor that lifts the paper, and above that has a sensor that detects when the paper reaches its upper limit. In this case, by raising or lowering the paper, it is confirmed that the output of the sensor that detects the upper limit of the paper is operating normally.

[0066] Furthermore, when it is confirmed by combining these that all of the sensors 21 to 23 to be judged are normal, the reference value is acquired and updated. As an example, in the jobs executed before the power was turned off, all of the "single-stage paper feed," "two-stage paper feed," and "double-sided printing" were completed without any abnormalities, but it may not be possible to confirm that the sensor configured for "three-stage paper feed" is normal. In this case, control is performed to operate the paper lift-up motor for the three-stage paper feed, and when it is confirmed that the sensor is normal, the reference value is acquired and updated.

[0067] In this embodiment, the value of the current supplied from the power supply unit 101 to the plurality of sensors 21-23 is detected. Furthermore, the value of the current supplied from the power supply unit 101 to the plurality of sensors 21-23 when the plurality of sensors 21-23 are in a normal state is acquired as a reference value. Then, by comparing the detected current value with the acquired reference value, it is determined whether the plurality of sensors 21-23 are normal or not.

[0068] If the comparison shows that the detected current values ​​of the multiple sensors 21-23 are the same as or close to the reference value when the multiple sensors 21-23 are in a normal state, it can be determined that the multiple sensors 21-23 are normal. On the other hand, if the detected current values ​​of the multiple sensors are lower than the reference value, it can be determined that at least one of the sensors is abnormal. Therefore, it is possible to accurately determine whether the multiple sensors 21-23 are normal using simple processing.

[0069] Furthermore, even if there are variations in circuit constants or individual differences between sensors, these are reflected equally in both the detected current value and the reference value, so it is possible to determine whether one sensor is abnormal.

[0070] Next, another example of the process for determining whether or not there is an abnormality in a sensor, which is executed by the image forming apparatus, will be described with reference to the flowchart in Fig. 4. The determination process shown in this flowchart is also executed by the CPU 103 operating in accordance with an operating program stored in the ROM 105 or the like.

[0071] In this determination process, CPU 103 stores date information together with the reference values ​​in storage device 106, and accumulates the most recent reference values ​​and date information from the past to the present. CPU 103 also functions as a prediction unit that predicts failures of sensors 21 to 23 based on changes over time in the reference values ​​determined from the accumulated multiple reference values ​​and date information.

[0072] 4 in step S04 in storage device 106, CPU 103 stores the reference value acquired in step S03 in the flowchart of FIG. 4 in association with the date information on which the reference value was acquired. When storing, CPU 103 stores the previously stored reference value and date information without erasing them, leaving them as they are.

[0073] Next, in step S21, CPU 103 obtains a change in the reference value over time from the stored multiple reference values ​​and date information, and determines whether the obtained change over time can estimate (predict) sensor deterioration (failure). If CPU 103 cannot estimate deterioration of sensors 21-23 (NO in step S21), it proceeds directly to step S05 and enters a standby state. If CPU 103 can estimate deterioration of sensors 21-23 (YES in step S21), it displays a warning in step S22 to prompt the user to replace sensors 21-23.

[0074] The date information may be the date or time when the reference value was acquired, or may be information such as one month, six months, one year, or two years after the date of the first reference value (initial value).

[0075] In the flowchart of Fig. 4, the processes other than step S04, step S21, and step S22 are the same as the processes shown in the flowchart of Fig. 3, and therefore description thereof will be omitted. Note that the reference value read by CPU 103 from storage device 106 in step S10 is the latest reference value among the accumulated reference values.

[0076] The sensor abnormality determination process shown in the flowchart of Fig. 4 has the following effect in addition to the effect of the abnormality determination process shown in the flowchart of Fig. 3. That is, the presence or absence of an abnormality in the sensors 21-23 is determined based on the change over time in the total current value of the multiple sensors 21-23 acquired as a reference value. This increases the opportunities to determine the presence or absence of an abnormality in the sensors 21-23, making it possible to stably detect an abnormal sensor.

[0077] The timing for determining whether or not the sensors 21 to 23 are abnormal based on the change over time in the total current value of the plurality of sensors 21 to 23 is not limited to the timing shown in the flowchart of Fig. 4. For example, the determination may be made after the job is completed.

[0078] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. For example, the abnormality determination process by comparing the reference value with the total current value of the sensors 21 to 23 is performed when a job does not end normally, but it may be performed at other times. Another example of such a timing is when the image forming apparatus 1 performs an image formation stabilization operation (image stabilization operation). The abnormality determination process may be performed before or after the image stabilization operation begins, but it is preferable to perform it during the image stabilization operation so as not to reduce productivity.

[0079] Furthermore, instead of determining whether or not a sensor is abnormal based on the total current value of all the sensors 21-23, the following configuration may also be adopted. That is, all the sensors 21-23 may be divided into a plurality of groups, and the plurality of sensors belonging to each group may be subjected to abnormality determination processing by comparing the total current value with a reference value. In this case, when a sensor abnormality is determined by comparing the total current value of all the sensors 21-23 with the reference value, abnormality determination processing is performed for each group, making it easy to identify the sensor having an abnormality.

[0080] Furthermore, the CPU 103 compares the total current value flowing through the plurality of sensors 21 to 23 with the reference value and determines whether or not there is an abnormality according to the operating program, but the comparison circuit and determination circuit may be configured by hardware. [Explanation of symbols]

[0081] 1. Image forming device 1A Automatic Document Feeder 1B scanner 1C Printer section 1D paper feed section 1E Operation panel 4 Photoreceptor 5 Charging roller 6 print head 7 Developer 8 Cleaner 9 Cleaning roller 10 Intermediate transfer belt 20~23 Sensor 20a Light-emitting element 20b Light receiving element 100 control section 101 Power supply section 102 Current detection unit 103 CPU 104 RAM 105 ROM 106 Storage device 200 power supply

Claims

1. a plurality of sensors for detecting conditions within the image forming apparatus; a power source for supplying power to the plurality of sensors; a current detection unit that detects a current value supplied from the power source to the plurality of sensors; an acquisition unit that acquires, as a reference value, a current value supplied from the power source to the plurality of sensors when the plurality of sensors are in a normal state; a determination unit that determines whether the plurality of sensors are normal by comparing the current value detected by the current detection unit with the reference value; An image forming apparatus comprising:

2. 2. The image forming apparatus according to claim 1, wherein the sensor is a sensor having a light emitting element and a light receiving element.

3. 3. The image forming apparatus according to claim 1, wherein the acquisition unit acquires the reference value at a time when manufacturing of the image forming apparatus is completed.

4. 3. The image forming apparatus according to claim 1, wherein the acquisition unit acquires the reference value based on an instruction from a user of the image forming apparatus.

5. 3. The image forming apparatus according to claim 1, wherein the acquisition unit acquires the reference value when a predetermined number of image formations has been performed in the image forming apparatus.

6. 3. The image forming apparatus according to claim 1, wherein the acquisition unit acquires the reference value when the sensor is replaced.

7. a control board for controlling the plurality of sensors; 3. The image forming apparatus according to claim 1, wherein the acquisition unit acquires the reference value when the control board is replaced.

8. 3. The image forming apparatus according to claim 1, wherein the acquisition unit acquires the reference value when it is determined that the plurality of sensors are in a normal state.

9. 3. The image forming apparatus according to claim 1, wherein the determining unit determines whether the plurality of sensors are normal or not during a stabilization operation of image formation in the image forming apparatus.

10. 3. The image forming apparatus according to claim 1, further comprising a prediction unit that predicts a failure of the sensor based on a change over time in the current value detected by the current detection unit.

11. a plurality of sensors for detecting conditions within the image forming apparatus; a power source for supplying power to the plurality of sensors; a current detection unit that detects a current value supplied from the power source to the plurality of sensors; An image forming apparatus comprising: an acquisition step of acquiring, as a reference value, a current value supplied from the power source to the plurality of sensors when the plurality of sensors are in a normal state; a determining step of determining whether the plurality of sensors are normal by comparing the current value detected by the current detecting unit with the reference value; A method for determining an abnormality in a sensor in an image forming apparatus, comprising:

12. a plurality of sensors for detecting conditions within the image forming apparatus; a power source for supplying power to the plurality of sensors; a current detection unit that detects a current value supplied from the power source to the plurality of sensors; A computer of an image forming apparatus including: an acquisition step of acquiring, as a reference value, a current value supplied from the power source to the plurality of sensors when the plurality of sensors are in a normal state; a determining step of determining whether the plurality of sensors are normal by comparing the current value detected by the current detecting unit with the reference value; A program to execute.

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