Processing execution device, image forming apparatus, defect detection method, and defect detection program

Abstract

To reduce manufacturing costs while identifying potentially faulty sensors from among multiple sensors. [Solution] The processing execution device comprises a processing execution unit 51 that executes multiple processes, multiple sensors provided corresponding to each of the multiple processes, a batch detection unit 53 that detects a malfunction in any of the multiple sensors, a normal determination unit 55 that determines that each of the multiple processes has been completed successfully based on the output value of the sensor corresponding to the process, and a malfunction determination unit 57 that, after a malfunction in any of the multiple sensors is detected, determines that at least one of the one or more sensors corresponding to the one or more remaining processes, excluding one or more normal processes that have been determined to have been completed successfully, is malfunctioning.

Description

[Technical Field]

[0001] The present invention relates to a processing execution device, an image forming device, a defect determination method, and a defect determination program. In particular, the present invention relates to a processing execution device that executes processing using a plurality of sensors, an image forming device including the processing execution device, a defect determination method executed by the processing execution device, and a defect determination program that causes a computer to execute the defect determination method. [Background Art]

[0002] Image forming devices such as copiers, printers, and facsimile machines execute a process of conveying a recording medium such as paper on which an image is formed, and form an image on the recording medium while the recording medium is being conveyed. While the process of conveying the recording medium is being executed, a plurality of sensors for detecting the presence or absence of the recording medium in the middle of conveyance are provided because an error such as the recording medium being jammed may occur. On the other hand, in a state where the sensor malfunctions and cannot operate normally, since the presence or absence of the recording medium cannot be detected, an error is detected even though the recording medium is not jammed. Therefore, it is required to detect the state of the sensor.

[0003] Japanese Patent Application Laid-Open No. 5-26937 discloses an image recording apparatus including control signal output means for supplying a control signal to a plurality of controlled objects, current amount detection means for detecting the amount of current flowing through the controlled objects in response to a change in the output of the control signal, determination means for determining whether the control signal output means is normal or abnormal based on the detected current amount, and power supply control means for shutting off the power supply to the apparatus according to the determination result of the determination means.

[0004] However, while faults can be detected in sensors whose output changes by switching on and off with a control signal, such as through-beam sensors, faults cannot be detected in sensors whose output does not change even when the control signal is switched, such as reflective sensors. Furthermore, faults can also be detected by detecting the value of the current flowing through the sensor, but this requires detecting the current for each sensor, which increases manufacturing costs. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 5-26937 [Overview of the project] [Problems that the invention aims to solve]

[0006] One of the objectives of this invention is to provide a processing device that can identify potentially faulty sensors while reducing manufacturing costs.

[0007] Another objective of this invention is to provide an image processing device that can identify potentially faulty sensors while reducing manufacturing costs.

[0008] Another object of this invention is to provide a fault detection method that can identify potentially faulty sensors while reducing manufacturing costs.

[0009] Another object of this invention is to provide a malfunction detection program that can identify potentially faulty sensors while reducing manufacturing costs. [Means for solving the problem]

[0010] According to one aspect of this invention, the processing execution device comprises: a processing execution unit that performs a plurality of processes; a plurality of sensors provided corresponding to each of the plurality of processes; a batch detection unit that detects a malfunction in any of the plurality of sensors; a normal determination unit that determines, for each of the plurality of processes, that the process has been completed normally based on the output value of the sensor corresponding to the process; and a malfunction determination unit that, after a malfunction in any of the plurality of sensors is detected, determines that at least one of the one or more sensors corresponding to the one or more remaining processes, excluding one or more normal processes that have been determined to have been completed normally, is malfunctioning.

[0011] According to another aspect of this invention, the image forming apparatus comprises the processing execution apparatus described above.

[0012] According to yet another aspect of this invention, the malfunction determination method is a malfunction determination method performed by a processing execution device that performs a plurality of processes, wherein the processing execution device is equipped with a plurality of sensors corresponding to each of the plurality of processes, and includes a batch detection step for detecting a malfunction in any of the plurality of sensors, a normal determination step for each of the plurality of processes for determining that the process has been completed normally based on the output value of the sensor corresponding to the process, and a malfunction determination step for determining that at least one of the one or more sensors corresponding to each of the one or more remaining processes, excluding one or more normal processes that have been determined to have been completed normally, is malfunctioning after a malfunction in any of the plurality of sensors has been detected.

[0013] According to yet another aspect of this invention, the defect detection program causes a computer to execute the above-described defect detection method. [Brief explanation of the drawing]

[0014] [Figure 1] This is a perspective view showing the external appearance of a printer according to one embodiment of the present invention. [Figure 2] This is a schematic cross-sectional view showing an example of the internal configuration of a printer. [Figure 3] This is a circuit diagram showing an example of the electrical connection relationships of various sensors. [Figure 4] This is a block diagram illustrating the hardware configuration of the printer in this embodiment. [Figure 5] This block diagram shows an example of the functions of the CPU that a printer has. [Figure 6] This figure shows an example of the sensor's current consumption value. [Figure 7] This figure shows an example of a reference value for the sum of the current consumption of the four sensors. [Figure 8] This figure shows an example of a threshold. [Figure 9] This figure shows an example of a defect detection process. [Modes for carrying out the invention]

[0015] Embodiments of the present invention will be described below with reference to the drawings. In the following description, identical parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed descriptions of them will not be repeated.

[0016] Figure 1 is a perspective view showing the external appearance of a printer according to one embodiment of the present invention. Figure 2 is a schematic cross-sectional view showing an example of the internal configuration of the printer. Hereinafter, for the purpose of explanation, the left and right directions in Figure 2 will be referred to as the left-right direction, and the front and back directions will be referred to as the depth direction. In the left-right direction, the direction from left to right will be referred to as the right side direction, and the direction from right to left will be referred to as the left side direction. In the depth direction, the direction from front to back will be referred to as the front direction, and the direction from back to front will be referred to as the back direction.

[0017] Referring to Figures 1 and 2, the printer 100 is an example of an image forming apparatus and includes an image forming unit 140 for forming an image on a recording medium based on image data, a paper feeding unit 150 for supplying the recording medium to the image forming unit 140, and an operation panel 160. The printer 100 and the paper feeding unit 150 are examples of processing execution devices. The recording medium includes paper and other paper, and OHP (Over Head Projector) sheets. Here, we will explain using paper as an example of a recording medium.

[0018] The image forming unit 140 includes image forming units 20Y, 20M, 20C, and 20K for yellow, magenta, cyan, and black respectively. Here, "Y", "M", "C", and "K" represent yellow, magenta, cyan, and black respectively. Printing data for yellow, magenta, cyan, and black are input into the image forming units 20Y, 20M, 20C, and 20K respectively. Since only the colors of the toners handled by the image forming units 20Y, 20M, 20C, and 20K are different, the image forming unit 20Y for forming a yellow image will be described here.

[0019] The image forming unit 20Y includes an exposure device 21Y, a photosensitive drum 23Y, a charging roller 22Y, a developing device 24Y, a primary transfer roller 25Y, a toner bottle 41Y, and a toner hopper 42Y. The exposure device 21Y receives yellow printing data. The photosensitive drum 23Y is an image carrier. The charging roller 22Y uniformly charges the surface of the photosensitive drum 23Y. The developing device 24Y forms a toner image on the photosensitive drum 23Y. The primary transfer roller 25Y transfers the toner image formed on the photosensitive drum 23Y onto the intermediate transfer belt 30, which is an image carrier, by the action of an electric field force. The drum cleaning blade 27Y removes the toner remaining on the photosensitive drum 23Y.

[0020] The toner bottle 41Y stores yellow toner. The toner bottle 41Y rotates with a toner bottle motor as a drive source and discharges the toner to the outside. The toner discharged from the toner bottle 41Y is supplied to the toner hopper 42Y. The toner hopper 42Y supplies toner to the developing device 24Y when the remaining amount of the toner stored in the developing device 24Y becomes less than or equal to a predetermined lower limit value.

[0021] Around the photosensitive drum 23Y, the charging roller 22Y, the exposure device 21Y, the developing device 24Y, the primary transfer roller 25Y, and the drum cleaning blade 27Y are arranged in order along the rotation direction of the photosensitive drum 23Y.

[0022] The photoreceptor drum 23Y is charged by the charging roller 22Y, and then irradiated with laser light emitted by the exposure device 21Y. The exposure device 21Y exposes the image-corresponding area on the surface of the photoreceptor drum 23Y to form an electrostatic latent image. The developer 24Y develops the electrostatic latent image formed on the photoreceptor drum 23Y with charged toner. Specifically, toner is placed on the electrostatic latent image formed on the photoreceptor drum 23Y by the action of an electric field force, thereby forming a toner image on the photoreceptor drum 23Y. The toner image formed on the photoreceptor drum 23Y is transferred onto the intermediate transfer belt 30, which is an image carrier, by the action of an electric field force using the primary transfer roller 25Y. Toner that remains on the photoreceptor drum 23Y without being transferred is removed from the photoreceptor drum 23Y by the drum cleaning blade 27Y.

[0023] Meanwhile, the intermediate transfer belt 30 is suspended by the drive roller 33 and the driven roller 34 to prevent slack. When the drive roller 33 rotates counterclockwise in Figure 2, the intermediate transfer belt 30 rotates counterclockwise in the figure at a predetermined speed. As the intermediate transfer belt 30 rotates, the driven roller 34 rotates counterclockwise.

[0024] As a result, the image forming units 20Y, 20M, 20C, and 20K sequentially transfer toner images onto the intermediate transfer belt 30. The timing at which each of the image forming units 20Y, 20M, 20C, and 20K transfers toner images onto the intermediate transfer belt 30 is adjusted by detecting reference marks attached to the intermediate transfer belt 30. In this way, yellow, magenta, cyan, and black toner images are superimposed on the intermediate transfer belt 30.

[0025] The toner image formed on the intermediate transfer belt 30 is transferred to the paper by the action of an electric field force by the secondary transfer roller 26, which is a transfer member. The paper, which is transported by the timing roller 31, is transported to the nip section N where the intermediate transfer belt 30 and the secondary transfer roller 26 come into contact. The paper on which the toner image has been transferred is transported to the fixing device 50, where it is heated and pressurized. This melts the toner and fixes it to the paper. After that, the paper is discharged into the output tray 39.

[0026] A belt cleaning blade 28 is provided upstream of the image forming unit 20Y of the intermediate transfer belt 30. The belt cleaning blade 28 removes toner that remains on the intermediate transfer belt 30 without being transferred to the paper.

[0027] When forming a full-color image, the image forming unit 140 drives all of the image forming units 20Y, 20M, 20C, and 20K, but when forming a monochrome image, it drives only one of the image forming units 20Y, 20M, 20C, and 20K. It is also possible to form an image by combining two or more of the image forming units 20Y, 20M, 20C, and 20K. The printer 100 will be described in an example that employs a tandem system equipped with image forming units 20Y, 20M, 20C, and 20K that form four different colors of toner on the paper. Note that the printer 100 may also employ a four-cycle system in which a single photosensitive drum transfers the four colors of toner sequentially onto the paper.

[0028] The paper feeding unit 150 includes a paper feeding cassette 35, an ejection roller 36, a transport roller 32, a timing roller 31, a fuser 50, a paper discharge roller 37, a reversing roller 45, a first reversing transport roller 46, and a second reversing transport roller 47. A transport path 15 is formed connecting the ejection roller 36 to the paper discharge roller 37. The ejection roller 36, transport roller 32, timing roller 31, fuser 50, and paper discharge roller 37 are arranged in this order from bottom to top within the transport path 15. A secondary transfer roller 26 is located between the timing roller 31 and the fuser 50.

[0029] The transport path 15 has a first branching point C1 and a second branching point C2. The first branching point C1 is located between the transport roller 32 and the timing roller 31. The second branching point C2 is located between the fixing device 50 and the paper discharge roller 37. The transport path 15 is connected to the reversal path 16 at the first branching point C1. The reversal path 16 is the path connecting the reversal roller 45 and the first branching point C1. The first reversal transport roller 46 and the second reversal transport roller 47 are arranged in the reversal path 16. The first reversal transport roller 46 is positioned closer to the reversal roller 45 than the second reversal transport roller 47. The reversal path 16 has a third branching point C3 between the reversal roller 45 and the first reversal transport roller 46. A connecting path 17 is formed connecting the transport path 15 and the reversal path 16. The connecting path 17 is the path connecting the second branching point C2 and the third branching point C3. The connection path 17 connects to the transport path 15 at the second branching point C2 and to the reversal path 16 at the third branching point C3.

[0030] The transport path 15 includes a first path P1 between the transport roller 32 and the first branching point C1, a second path P2 between the first branching point C1 and the timing roller 31, and a third path P3 between the fixing device 50 and the paper discharge roller 37.

[0031] Multiple sheets of paper are loaded into the paper feed cassette 35. The paper stored in the paper feed cassette 35 is supplied one sheet at a time to the transport path 15 by the ejection roller 36 attached to the paper feed cassette 35. The paper supplied to the transport path 15 by the ejection roller 36 is transported by the transport roller 32 through the first path P1 and the second path P2 to the timing roller 31.

[0032] The timing roller 31 transports the paper toward the secondary transfer roller 26. As the paper transported by the timing roller 31 passes through the nip section N formed between the secondary transfer roller 26 and the drive roller 33, the toner image formed on the intermediate transfer belt 30 is transferred by the secondary transfer roller 26. The paper passing through the nip section N is then transported to the fuser 50 by the intermediate transfer belt 30 and the secondary transfer roller 26.

[0033] The fuser 50 includes a pressure roller and a heating section. As the paper passes between the pressure roller and the heating section, the toner image formed on the paper is heated and pressurized, thereby fixing the toner image to the paper. The paper transported by the fuser 50 is transported towards either the paper discharge roller 37 or the reversing roller 45. A switching claw provided at the second branching point C2 of the transport path 15 switches whether the paper is transported towards the paper discharge roller 37 or the reversing roller 45. The paper transported from the fuser 50 towards the paper discharge roller 37 is transported to the paper discharge roller 37 via the third path P3. The paper discharge roller 37 discharges the paper transported by the fuser 50 into the paper discharge tray 39.

[0034] The paper transported from the fuser 50 toward the reversing roller 45 is transported to the reversing roller 45 through the portion of the third path P3 from the fuser 50 to the second branching point C2, the connecting path 17, and the portion of the fourth path P4 between the third branching point C3 and the reversing roller 45. The reversing roller 45 transports the paper transported by the fuser 50 toward the output tray 39 until the downstream end of the paper passes the third branching point C3. Then, in response to the downstream end of the paper passing the third branching point C3, the reversing roller 45 reverses its direction of rotation and transports the paper toward the first reversing transport roller 46. The paper transported by the reversing reversing roller 45 is transported toward the first reversing transport roller 46 through the fourth path P4. The first reversing transport roller 46 transports the paper toward the second reversing transport roller 47. The second reversing transport roller 47 transports the paper toward the timing roller 31. The paper transported by the second reversing transport roller 47 is transported to the timing roller 31 through the section of the fourth path P4 from the second reversing transport roller 47 to the first branching point C1 and through the second path P2.

[0035] A paper feed sensor 11 is located in the first path P1. The paper feed sensor 11 detects the paper being transported along the first path P1. A registration sensor 12 is located in the second path P2. The registration sensor 12 detects the paper being transported along the second path P2. A paper discharge sensor 13 is located in the third path P3. The paper discharge sensor 13 detects the paper being transported along the third path P3. The reversal path 16 has a fourth path P4 between the first reversal transport roller 46 and the second reversal transport roller 47. A duplex sensor 14 is located in the fourth path P4. The duplex sensor 14 detects the paper being transported along the fourth path P4.

[0036] The paper feed sensor 11, the resist sensor 12, the paper discharge sensor 13, and the duplex sensor 14 are all optical sensors. An optical sensor has a light-emitting part and a light-receiving part, and the light emitted from the light-emitting part is received by the light-receiving part. The amount of light received by the light-receiving part changes depending on whether or not paper is present in the detection area provided between the light-emitting part and the light-receiving part. Paper is detected by detecting this change in the amount of light. The optical sensor may be transmissive or reflective. A transmissive optical sensor detects the phenomenon that light emitted from the light-emitting part is blocked by the paper. A reflective optical sensor detects the phenomenon that light emitted from the light-emitting part is reflected by the paper. In this embodiment, the case in which the paper feed sensor 11, the resist sensor 12, the paper discharge sensor 13, and the duplex sensor 14 are all transmissive optical sensors will be described as an example.

[0037] Figure 3 is a circuit diagram showing an example of the electrical connection relationships of various sensors. Referring to Figure 3, the electrical circuit has the ammeter 19 connected in series with the power supply 18, and the paper feed sensor 11, resist sensor 12, paper discharge sensor 13, and duplex sensor 14 connected in parallel.

[0038] Figure 4 is a block diagram illustrating the hardware configuration of the printer in this embodiment. Referring to Figure 4, the printer 100 includes a main circuit 110, an image forming unit 140, a paper feeding unit 150, and an operation panel 160. The operation panel 160 is the user interface.

[0039] The main circuit 110 includes a CPU 111, a communication interface (I / F) unit 112, a ROM 113, a RAM 114, an HDD 115, and an external storage device 117. The HDD 115 is a high-capacity storage device. A solid-state drive (SSD) may be used instead of the HDD 115. The CPU 111 is connected to the image forming unit 140, the paper feeding unit 150, and the operation panel 160, and controls the entire printer 100.

[0040] The communication interface unit 112 is an interface for connecting the printer 100 to the network. The communication interface unit 112 communicates with computers connected to the network using communication protocols such as TCP (Transmission Control Protocol) or FTP (File Transfer Protocol).

[0041] ROM113 stores the program that the CPU111 executes, or the data necessary to execute that program. RAM114 is used as a workspace when the CPU111 executes the program.

[0042] The control panel 160 includes a display unit 161 and an operation unit 163. The display unit 161 is, for example, a liquid crystal display (LCD) and displays instruction menus for the user, information about acquired image data, etc. Alternatively, any device that displays images, such as an organic EL display, may be used instead of the LCD.

[0043] The operating unit 163 includes a touch panel 165 and a hard key unit 167. The touch panel 165 is capacitive. However, the touch panel 165 is not limited to the capacitive type; other types such as resistive, surface acoustic wave, infrared, and electromagnetic induction can be used. The hard key unit 167 includes a plurality of hard keys. The hard keys are, for example, contact switches.

[0044] The external storage device 117 is controlled by the CPU 111 and has a CD-ROM 118 installed in it. In this embodiment, an example is described in which the CPU 111 executes a program stored in ROM 113. Alternatively, the CPU 111 may control the external storage device 117 to read a program for execution from the CD-ROM 118, store the read program in RAM 114, and then execute it.

[0045] Furthermore, the recording medium for storing the program to be executed by the CPU 111 is not limited to the CD-ROM 118, but may also be a flexible disk, cassette tape, optical disk, semiconductor memory, etc. Optical disks include MO (Magnetic Optical Disc), MD (MiniDisc), and DVD (Digital Versatile Disc). Semiconductor memory includes IC cards, optical cards, mask ROM, and EPROM (Erasable Programmable ROM).

[0046] Furthermore, the CPU 111 may load programs stored in the HDD 115 into the RAM 114 and execute them. Programs stored in the HDD 115 include programs downloaded by the CPU 111 from computers connected to a network such as the Internet, or programs written to the HDD 115 by computers connected to the network. The term "program" here includes not only programs that can be directly executed by the CPU 111, but also source programs, compressed programs, encrypted programs, and so on.

[0047] Figure 5 is a block diagram showing an example of the functions of the CPU in the printer. The functions shown in Figure 5 are realized by the CPU 111 of the printer 100, which executes a malfunction detection program stored in the ROM 113, HDD 115, or CD-ROM 118. Referring to Figure 5, the CPU 111 includes a processing execution unit 51, a batch detection unit 53, a normal determination unit 55, a malfunction determination unit 57, and a notification unit 59.

[0048] The processing execution unit 51 executes predetermined processes. The processing execution unit 51 controls the paper feeding unit 150 to execute multiple processes for transporting paper. The multiple processes for transporting paper include the first to fourth processes. The first process is the process of controlling the paper feeding unit 150 to transport the paper along the first path P1. The second process is the process of controlling the paper feeding unit 150 to transport the paper along the second path P2. The third process is the process of controlling the paper feeding unit 150 to transport the paper along the third path P3. The fourth process is the process of controlling the paper feeding unit 150 to transport the paper along the fourth path P4.

[0049] The normal judgment unit 55 determines that each of the multiple processes has been executed successfully by the processing execution unit 51. The normal judgment unit 55 determines that each of the multiple processes has been executed successfully based on the output values ​​of the paper feed sensor 11, the registration sensor 12, the paper discharge sensor 13, and the duplex sensor 14. The normal judgment unit 55 outputs the determination result to the malfunction determination unit 57.

[0050] Specifically, when the processing execution unit 51 executes the first process, it drives the transport roller 32 and transports the paper taken out of the paper feed cassette 35 by the ejection roller 36. The normal judgment unit 55 determines that the first process has been executed normally if the paper is detected by the paper feed sensor 11 from the time Ts1 elapsed since the transport roller 32 was driven until the detection period Te1 has elapsed. The normal judgment unit 55 determines that the first process has not been executed normally and is in a first abnormal state if the paper is not detected by the paper feed sensor 11 even after the time Ts1 has elapsed since the transport roller 32 was driven. The first abnormal state is a state in which a malfunction has occurred in the paper feed sensor 11. Furthermore, the normal judgment unit 55 determines that the first process has not been executed normally and is in a second abnormal state if the period during which the paper is detected by the paper feed sensor 11 exceeds the detection period Te1. The second abnormal state is a state in which the paper jams without being transported during the execution of the first process. The detection period Te1 is determined by the paper size and the speed at which the transport roller 32 transports the paper.

[0051] The processing execution unit 51 executes the second process after executing the first process or after executing the fourth process. When the processing execution unit 51 executes the second process after executing the first process, it drives the timing roller 31 to transport the paper passing through the first path P1 through the second path P2. The normal judgment unit 55 determines that the second process has been executed normally if the paper is detected by the registration sensor 12 from the time Ts2 elapsed after the paper is detected by the paper feed sensor 11 until the detection period Te2 has elapsed. The normal judgment unit 55 determines that the second process has not been executed normally and is in a first abnormal state if the paper is not detected by the registration sensor 12 even after the time Ts2 has elapsed since the paper was detected by the paper feed sensor 11. The normal judgment unit 55 also determines that the second process has not been executed normally and is in a second abnormal state if the period during which the paper is detected by the registration sensor 12 exceeds the detection period Te2. The detection period Te2 is determined by the time the timing roller 31 starts transporting the paper, the size of the paper, and the speed at which the timing roller 31 transports the paper.

[0052] When the processing execution unit 51 executes the second process after executing the fourth process, it drives the timing roller 31 to transport the paper passing through the fourth path P4 through the second path P2. The normal judgment unit 55 determines that the second process has been executed normally if the paper is detected by the resist sensor 12 from the time Ts5 elapsed after the paper is detected by the duplex sensor 14 until the detection period Te2 has elapsed. The normal judgment unit 55 determines that the second process has not been executed normally and is in a first abnormal state if the paper is not detected by the resist sensor 12 even after the time Ts5 has elapsed since the paper was detected by the duplex sensor 14. Furthermore, the normal judgment unit 55 determines that the second process has not been executed normally and is in a second abnormal state if the period during which the paper is detected by the resist sensor 12 exceeds the detection period Te2.

[0053] When the processing execution unit 51 executes the third process, it drives the paper discharge roller 37 to transport the paper supplied from the fuser unit 50. The normal judgment unit 55 determines that the third process has been executed normally if the paper is detected by the paper discharge sensor 13 from the time Ts3 elapsed after the timing roller 31 starts transporting the paper until the detection period Te3 has elapsed. The normal judgment unit 55 determines that the third process has not been executed normally and is in a first abnormal state if the paper is not detected by the paper feed sensor 11 even after the time Ts3 has elapsed since the timing roller 31 started transporting the paper. The normal judgment unit 55 also determines that the third process has not been executed normally and is in a second abnormal state if the period during which the paper is detected by the paper discharge sensor 13 exceeds the detection period Te3. The detection period Te3 is determined by the size of the paper and the speed at which the paper discharge roller 37 transports the paper.

[0054] When the processing execution unit 51 executes the fourth process, it drives the reversing roller 45, the first reversing transport roller 46, and the second reversing transport roller 47 to transport the paper through the fourth path P4. The normal determination unit 55 determines that the fourth process has been executed successfully if the paper is detected by the duplex sensor 14 from the time Ts4 elapsed after the reversing roller 45 reverses its rotational direction until the detection period Te4 has elapsed. The normal determination unit 55 determines that the fourth process has not been executed successfully and is in a first abnormal state if the paper is not detected by the duplex sensor 14 even after the time Ts4 has elapsed since the reversing roller 45 reverses its rotational direction. The normal determination unit 55 also determines that the fourth process has not been executed successfully and is in a second abnormal state if the period during which the paper is detected by the duplex sensor 14 exceeds the detection period Te4. The detection period Te4 is determined by the size of the paper and the speed at which the reversing roller 45, the first reversing transport roller 46, and the second reversing transport roller 47 transport the paper.

[0055] The normal determination unit 55 determines whether the first to fourth processes performed by the processing execution unit 51 were executed successfully. The normal determination unit 55 outputs processing result information indicating either normal or abnormal for each of the first to fourth processes to the malfunction determination unit 57. The processing result information indicating an abnormality includes information indicating whether it is a first abnormal state or a second abnormal state.

[0056] The normal determination unit 55 determines whether the first to fourth processes have been executed successfully based on the outputs of the paper feed sensor 11, the registration sensor 12, the paper discharge sensor 13, and the duplex sensor 14. The normal determination unit 55 uses the output of the paper feed sensor 11 to determine whether the first process has been executed successfully. The normal determination unit 55 uses the output of the registration sensor 12 to determine whether the second process has been executed successfully. The normal determination unit 55 uses the output of the paper discharge sensor 13 to determine whether the third process has been executed successfully. The normal determination unit 55 uses the output of the duplex sensor 14 to determine whether the fourth process has been executed successfully. The normal determination unit 55 keeps track of the position of the transported paper in the transport path 15 and the inversion path 16 in real time. The normal determination unit 55 determines that the first to fourth processes have been executed successfully when the paper position it keeps track of matches the paper position detected by the paper feed sensor 11, the registration sensor 12, the paper discharge sensor 13, and the duplex sensor 14, respectively. The normal judgment unit 55 determines that the first process has not been executed correctly if the paper position it has grasped differs from the paper position detected by the paper feed sensor 11. The normal judgment unit 55 determines that the second process has not been executed correctly if the paper position it has grasped differs from the paper position detected by the registration sensor 12. The normal judgment unit 55 determines that the third process has not been executed correctly if the paper position it has grasped differs from the paper position detected by the paper discharge sensor 13. The normal judgment unit 55 determines that the fourth process has not been executed correctly if the paper position it has grasped differs from the paper position detected by the duplex sensor 14.

[0057] In this embodiment, the processing execution unit 51 executes the first process, the second process, the fourth process, the second process, and the third process in that order. If the normal judgment unit 55 determines that the first process is abnormal, it determines that all of the first to fourth processes are abnormal. If the normal judgment unit 55 determines that the first process is normal and the second process is abnormal, it determines that all of the second to fourth processes are abnormal. If the normal judgment unit 55 determines that the first and second processes are normal and the fourth process is abnormal, it determines that the fourth and third processes are abnormal. If the normal judgment unit 55 determines that the first, second, and fourth processes are normal and the second execution of the second process is abnormal, it determines that the second and third processes are abnormal. If the normal judgment unit 55 determines that the first, second, fourth, and second execution of the second process are normal and the third process is abnormal, it determines that the third process is abnormal.

[0058] The batch detection unit 53 detects a malfunction in any of the paper feed sensor 11, resist sensor 12, paper discharge sensor 13, and duplex sensor 14. As shown in Figure 3, the paper feed sensor 11, resist sensor 12, paper discharge sensor 13, and duplex sensor 14 are connected in parallel. The voltage applied to the paper feed sensor 11, resist sensor 12, paper discharge sensor 13, and duplex sensor 14 is the same. Therefore, the value of the current flowing through the paper feed sensor 11, resist sensor 12, paper discharge sensor 13, and duplex sensor 14 is fixed. If there is a malfunction in any of the paper feed sensor 11, resist sensor 12, paper discharge sensor 13, or duplex sensor 14, current will not flow to the malfunctioning sensor. Therefore, the current value detected by the ammeter 19 changes. A malfunction is when the sensor does not operate normally, and includes cases where the sensor is faulty or when the power supply is not connected to the sensor.

[0059] The batch detection unit 53 detects a malfunction in one of the multiple sensors based on the current value measured by the ammeter 19. Here, we will describe the case where the paper feed sensor 11, the registration sensor 12, the paper discharge sensor 13, and the duplex sensor 14 are of the same model. Hereafter, the paper feed sensor 11, the registration sensor 12, the paper discharge sensor 13, and the duplex sensor 14 will be collectively referred to as sensors.

[0060] Figure 6 shows an example of the sensor's current consumption. Referring to Figure 6, the average current consumption of the sensor is 12.0 mA, and the minimum current consumption of the sensor is 9.5 mA.

[0061] Figure 7 shows an example of a reference value for the total current consumption of four sensors. The total current consumption reference value is 48mA. The total current consumption reference value is determined based on the sum of the current consumption values ​​of each of the four sensors. Here, the total current reference value is the sum of the average current consumption values ​​of each of the four sensors.

[0062] Figure 8 shows an example of a threshold value. The threshold value is determined from the reference value and the minimum current consumption of each of the four sensors. The threshold value for a malfunction in one of the four sensors is 38.5 mA. The threshold value for a malfunction in two of the four sensors is 29.0 mA. The threshold value for a malfunction in three of the four sensors is 19.5 mA. The threshold value for a malfunction in all four sensors is 10.0 mA.

[0063] Returning to Figure 5, the batch detection unit 53 compares the current value measured by the ammeter 19 with four judgment thresholds. Based on the comparison result, the batch detection unit 53 determines the number of faulty sensors among the four sensors as the first number. If the batch detection unit 53 determines that none of the four sensors are faulty, it sets the first number to 0. The batch detection unit 53 outputs the first number to the fault determination unit 57.

[0064] The malfunction determination unit 57 receives a first number from the batch detection unit 53 and processing result information from the normal determination unit 55. If a malfunction is detected in any of the four sensors, the malfunction determination unit 57 determines that the first number of sensors is malfunctioning among the one or more sensors corresponding to the one or more remaining processes, excluding one or more normal processes that have been determined to have completed successfully among the first to fourth processes.

[0065] The malfunction determination unit 57 determines whether each of the first to fourth processes has completed successfully based on the processing result information. It determines that the process is normal if the processing result information does not indicate an abnormality. The processing result information includes either the first abnormality information or the second abnormality information. The second abnormality information indicates a paper jam, so after the paper jam is cleared, the processing result information will no longer include the second abnormality information. Therefore, a normal process is one in which the processing result information does not include the first abnormality information. Consequently, a normal process includes a process in which the processing result information indicates normal and a process in which the processing result information indicates the second abnormality information.

[0066] Furthermore, the malfunction determination unit 57 may identify a normal process based on the first abnormal information indicating an abnormality among the processing result information. In this case, a normal process is a process in which the processing result information does not include the first abnormal information. Therefore, a normal process includes a process in which the processing result information indicates normality and a process in which the processing result information indicates the second abnormal information.

[0067] The malfunction determination unit 57 determines whether the detection by the batch detection unit 53 is correct if the first number is 1 or greater, in other words, if the batch detection unit 53 detects that one or more sensors are malfunctioning. The malfunction determination unit 57 determines the second number to be the number of one or more sensors corresponding to the processes among the first to fourth processes that the normality determination unit 55 has determined to be abnormal. Based on the second number and the first number, the malfunction determination unit 57 determines whether the detection by the batch detection unit 53 is correct. The malfunction determination unit 57 determines that the detection by the batch detection unit 53 is correct if the second number is greater than or equal to the first number, and determines that the detection by the batch detection unit 53 is incorrect if the second number is less than the first number.

[0068] The malfunction determination unit 57 identifies the malfunctioning sensor if it determines that the detection by the batch detection unit 53 is correct. The malfunction determination unit 57 identifies the sensor corresponding to the process among the first to fourth processes in which the processing result information indicates an abnormality as the malfunctioning sensor. The malfunction determination unit 57 outputs sensor identification information to the notification unit 59 to identify the malfunctioning sensor. The malfunction determination unit 57 determines that the sensor corresponding to the process among the first to fourth processes that was determined to be abnormal is malfunctioning. If the first number is 1, the malfunction determination unit 57 determines that the sensor corresponding to the first process among the first to fourth processes that was determined to be abnormal is malfunctioning, and also determines that the sensors corresponding to the number of processes obtained by subtracting 1 from the first number are malfunctioning.

[0069] <When the first quantity is 1> If the malfunction detection unit 57 determines that the first process is abnormal, it identifies the paper feed sensor 11 as the faulty sensor. If the malfunction detection unit 57 determines that the second process is abnormal, it identifies the resist sensor 12 as the faulty sensor. If the malfunction detection unit 57 determines that the fourth process is abnormal, it identifies the duplex sensor 14 as the faulty sensor. If the malfunction detection unit 57 determines that the third process is abnormal, it identifies the paper discharge sensor 13 as the faulty sensor.

[0070] <When the first quantity is 2> If the malfunction detection unit 57 determines that the first process is abnormal, it identifies the paper feed sensor 11 as the faulty sensor. The malfunction detection unit 57 also identifies one of the register sensor 12, paper discharge sensor 13, and duplex sensor 14 as the faulty sensor. If the malfunction detection unit 57 determines that the second process is abnormal, it identifies the register sensor 12 as the faulty sensor, and one of the paper discharge sensor 13 or duplex sensor 14 as the faulty sensor. If the malfunction detection unit 57 determines that the fourth process is abnormal, it identifies both duplex sensors 14 and duplex sensors 14 as faulty sensors.

[0071] <When the first quantity is 3> If the malfunction detection unit 57 determines that the first process is abnormal, it identifies the paper feed sensor 11 as a faulty sensor. Furthermore, the malfunction detection unit 57 identifies any two of the registration sensor 12, paper discharge sensor 13, and duplex sensor 14 as faulty sensors. If the malfunction detection unit 57 determines that the second process is abnormal, it identifies the registration sensor 12, paper discharge sensor 13, and duplex sensor 14 as faulty sensors.

[0072] <When the first quantity is 4> If the malfunction detection unit 57 determines that the first process is abnormal, it identifies all of the following sensors as malfunctioning: the paper feed sensor 11, the registration sensor 12, the paper discharge sensor 13, and the duplex sensor 14.

[0073] The malfunction detection unit 57 includes a correction unit 63. The correction unit 63 changes the threshold if it determines that the detection by the batch detection unit 53 is incorrect. If the current value differs due to individual differences in sensors, the voltage applied to the circuit including the sensors may fluctuate. The batch detection unit 53 determines the first number using the threshold after it has been corrected by the correction unit 63.

[0074] The notification unit 59 notifies the user of a faulty sensor in response to sensor identification information input from the fault detection unit 57. The notification unit 59 displays the fault information on the display unit 161. The fault information includes sensor identification information. The fault information may also include a diagram showing the location of the sensor identified by the sensor identification information. The notification unit 59 may also output the fault information by voice. The notification unit 59 may also send the fault information to the user who manages the printer 100 via email or other means.

[0075] Figure 9 shows an example of the malfunction detection process. The malfunction detection process is performed by the CPU 111 of the printer 100 when the CPU 111 executes a malfunction detection program stored in the ROM 113, HDD 115, or CD-ROM 118. Referring to Figure 9, in step S01, the current value is acquired, and the process proceeds to step S02. The CPU 111 controls the ammeter 19 and acquires the current value detected by the ammeter 19.

[0076] In step S02, it is determined whether the current value is less than or equal to the threshold Th. The threshold Th is a predetermined value. Here, the threshold Th is defined as the sum of the average current values ​​flowing through the paper feed sensor 11, the resist sensor 12, the paper discharge sensor 13, and the duplex sensor 14 when they are operating normally. In this embodiment, the threshold Th is a reference value of 48mA. If the current value is less than or equal to the threshold Th, the process proceeds to step S03; otherwise, the process ends.

[0077] In step S03, all sensor flags are set to NG, and the process proceeds to step S04. Each of the four sensor flags corresponds to a different sensor and indicates its status. The flags are set to either OK, which indicates that the sensor is functioning normally, or NG, which indicates that the sensor is not functioning correctly.

[0078] In step S04, the first number is determined based on the current value, and the process proceeds to step S05. In step S04, the CPU 111 determines the first number by comparing the current value with a judgment threshold corresponding to the number of faulty sensors. The first number is the number of faulty sensors among the paper feed sensor 11, the resist sensor 12, the paper output sensor 13, and the duplex sensor 14.

[0079] In step S05, a process is selected, and the process proceeds to step S06. The process to be executed is selected from among the first to fourth processes. In step S06, the process selected in step S05 is executed, and the process proceeds to step S07. In step S07, it is determined whether the process executed in step S06 has completed successfully. If the process has completed successfully, the process proceeds to step S08; otherwise, step S08 is skipped, and the process proceeds to step S09. It is determined whether the process has completed successfully based on the output value of the sensor corresponding to the process.

[0080] In step S08, the sensor flag is set to OK, and the process proceeds to step S09. In step S05, the sensor flag corresponding to the optical sensor corresponding to the process selected as the processing target is set to OK. The first process is associated with the paper feed sensor 11, the second process with the registration sensor 12, the third process with the paper ejection sensor 13, and the fourth process with the duplex sensor 14. Whether the process has completed successfully includes cases where the process is completed after a paper jam has been resolved. In other words, if the first abnormal state is detected, it is determined that the process has not completed successfully, and if the first abnormal state is not detected, it is determined that the process has completed successfully.

[0081] In step S09, it is determined whether or not there is a process that should be processed next. If there is a process that was not selected as a target in step S05, the process returns to step S05; otherwise, the process proceeds to step S10.

[0082] In step S10, the second number is determined, and the process proceeds to step S11. The second number is the number of sensors whose sensor flag is set to NG. In step S11, it is determined whether the second number is greater than or equal to the first number. If the second number is greater than or equal to the first number, the process proceeds to step S12; otherwise, the process proceeds to step S13. In step S12, a malfunction is notified, and the process ends. If the first number is 1, the CPU 111 notifies the user that a malfunction has occurred in the sensor corresponding to the first process among the first to fourth processes that was judged to be abnormal. If the first number is 2 or greater, the CPU 111 notifies the user that a malfunction has occurred in the sensor corresponding to the first process among the first to fourth processes that was judged to be abnormal, and in a predetermined number of sensors corresponding to one or more subsequent processes. The predetermined number is the first number minus 1.

[0083] In step S13, the threshold Th is corrected, and the process returns to step S01. The threshold Th is changed from the reference value.

[0084] <Variation> (1) In this embodiment, the printer 100 has been described as executing the first to fourth processes in sequence. However, the present invention is not limited thereto. The printer 100 may execute each of the processes independently. In this case, each time any of the processes is executed, it is determined whether the executed process has completed successfully, and the result of this determination does not affect the other processes.

[0085] (2) In this embodiment, the case in which the printer 100 performs the first to fourth processes has been described as an example. However, the present invention is not limited thereto. The number of processes that the printer 100 performs may be multiple. Furthermore, one or more sensors may be provided corresponding to each of the multiple processes.

[0086] (3) Multiple processes only need to be associated with at least one sensor. Multiple sensors may be associated with a single process. If a process completes successfully, it is detected that there are no malfunctions in the multiple sensors. Multiple processes in this embodiment do not include processes to which no sensor is associated.

[0087] (4) In this embodiment, a printer 100 was given as an example of a processing execution device. The processing execution device is not limited to a printer, and may be any device capable of executing multiple processes and equipped with one or more sensors corresponding to each of the multiple processes. For example, the processing execution device includes a transport device for transporting paper, an image forming device for forming an image on the paper, and a post-processing device for performing post-processing on the paper. Post-processing includes a process for rearranging multiple sheets of paper, a punching process for punching holes in the paper, a stapling process for driving staples into the paper, a folding process for folding the paper, and a cutting process for cutting the paper.

[0088] (5) In this embodiment, a printer 100 was described as an example of an image forming apparatus, but the image forming apparatus may also be a copier, a laser beam printer, a facsimile machine, or a multifunction device (Multi Function Peripheral) that combines these.

[0089] (6) In this embodiment, a tandem-type color image forming printer 100 was described as an example of an image forming apparatus. The present invention is not limited to this, and may also be an image forming apparatus that forms monochrome images. The configuration and arrangement of the image forming units 20Y, 20M, 20C, 20K, the secondary transfer roller 26, and the fixing device 50 are not limited to this embodiment, and may be other configurations or arrangements.

[0090] <Summary of Embodiments> (Item 1) A processing execution unit that performs multiple processes, Multiple sensors provided in accordance with each of the multiple processes, A batch detection unit that detects a malfunction in any of the multiple sensors, For each of the multiple processes, a normal determination unit determines whether the process has been completed successfully based on the output value of the sensor corresponding to the process, A processing execution device comprising: a malfunction determination unit that, after a malfunction is detected in any of the multiple sensors, determines that at least one of the one or more sensors corresponding to one or more remaining processes, excluding one or more normal processes that have been determined to have completed successfully, is malfunctioning.

[0091] In this scenario, after a malfunction is detected in one of several sensors, for each of the multiple processes, it is determined whether the process has completed successfully based on the output value of the sensor corresponding to the process. Of the multiple processes, excluding one or more processes that have been determined to have completed successfully, at least one of the sensors corresponding to each of the one or more remaining processes is determined to be faulty. Since a malfunction in one of the multiple sensors is detected, there is no need to provide a device to detect malfunctions for each of the multiple sensors. Therefore, manufacturing costs can be reduced. In addition, it is determined that each of the multiple processes corresponding to each of the multiple sensors has completed successfully based on the output value of the sensor corresponding to the process. If a sensor is faulty, it is not possible to detect that the process has completed successfully, so if it is confirmed that the process has completed successfully, it means that the sensor is not faulty. Conversely, sensors corresponding to processes for which it is not detected that the process has completed successfully are likely to be faulty. It is likely that at least one sensor, excluding the normal sensors from the multiple sensors, is faulty. Therefore, it is possible to provide a processing execution device that can identify potentially faulty sensors while reducing manufacturing costs.

[0092] (Item 2) The processing execution device according to Item 1, further comprising a notification unit that notifies that at least one of the one or more sensors corresponding to each of the one or more remaining processes is malfunctioning.

[0093] Following this procedure, users can identify faulty sensors, making repairs easier.

[0094] (Item 3) The processing execution device according to Item 1, wherein the batch detection unit detects a malfunction in any of the multiple sensors and does not detect a malfunction in any of the multiple sensors until all of the multiple processes have been completed.

[0095] Following this procedure allows for the effective use of the judgment results from the normal detection unit.

[0096] (Item 4) The processing execution device according to Item 1, wherein the batch detection unit corrects the detection criteria for detecting a malfunction when the number of sensors in which a malfunction is detected among the plurality of sensors is greater than the number of remaining processes of 1 or more.

[0097] Following this approach, the accuracy of detecting a malfunction in any of the multiple sensors can be increased to the point where it can detect malfunctions in response to external factors.

[0098] (Item 5) A power supply circuit that supplies power to multiple sensors via a shared connection line shared by multiple sensors, The system includes an ammeter for detecting the current value of the current flowing through the shared connection line, The processing execution device according to item 1, wherein the batch detection unit detects a malfunction in any of the multiple sensors based on the current value detected by the ammeter.

[0099] In this scenario, malfunctions are detected based on the current value flowing through a shared connection line shared by multiple sensors. Therefore, a single ammeter can detect a malfunction in any of the multiple sensors.

[0100] (Item 6) An image forming apparatus equipped with a processing execution device as described in any of Items 1 to 5.

[0101] Following this approach, it becomes possible to provide an image forming apparatus that can identify potentially faulty sensors while reducing manufacturing costs.

[0102] (Item 7) A method for determining defects that is performed by a processing execution device that performs multiple processes, The processing execution device includes a plurality of sensors, each of which is provided in accordance with the plurality of processes. A batch detection step for detecting a malfunction in any of the multiple sensors, For each of the multiple processes, a normal determination step is performed to determine whether the process has been completed successfully based on the output value of the sensor corresponding to the process. A malfunction determination method comprising: a malfunction determination step of determining that, after a malfunction is detected in any of the multiple sensors, at least one of the one or more sensors corresponding to one or more remaining processes, excluding one or more normal processes that have been determined to have completed successfully, is malfunctioning.

[0103] Following this approach, it is possible to provide a fault detection method that can identify potentially faulty sensors while reducing manufacturing costs.

[0104] (Item 8) A fault detection program executed on a computer that controls a processing execution device that performs multiple processes, The processing execution device includes a plurality of sensors, each of which is provided in accordance with the plurality of processes. A batch detection step for detecting a malfunction in any of the multiple sensors, For each of the multiple processes, a normal determination step is performed to determine whether the process has been completed successfully based on the output value of the sensor corresponding to the process. A malfunction determination program that causes the computer to perform a malfunction determination step of determining that, after a malfunction is detected in any of the multiple sensors, at least one of the one or more sensors corresponding to one or more remaining processes, excluding one or more normal processes that have been determined to have completed successfully, is malfunctioning.

[0105] Following this approach, it becomes possible to provide a fault detection program that can identify potentially faulty sensors while reducing manufacturing costs.

[0106] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0107] 100 Printer, 110 Main circuit, 111 CPU, 112 Communication I / F unit, 113 ROM, 114 RAM, 115 HDD, 117 External storage device, 118 CD-ROM, 140 Image forming unit, 150 Paper feeding unit, 160 Operation panel, 161 Display unit, 163 Operation unit, 165 Touch panel, 167 Hard key unit, 11 Paper feed sensor, 12 Resist sensor, 13 Paper ejection sensor, 14 Duplex sensor, 15 Transport path, 16 Reversal path, 17 Connection path, 18 Power supply, 19 Ammeter, 20Y, 20M, 20C, 20K Image forming unit, 26 Secondary transfer roller, 30 Intermediate transfer belt, 31 Timing roller, 32 Transport roller, 33 Drive roller, 34 Driven roller, 35 Paper feed cassette, 36 Ejection roller, 37 39 Paper output roller, 45 Paper output tray, 46 Reversing roller, 47 First reversing transport roller, 50 Fixing device, 51 Processing execution unit, 53 Batch detection unit, 55 Normal judgment unit, 57 Malfunction judgment unit, 59 Notification unit, 63 Correction unit, C1 First branching point, C2 Second branching point, C3 Third branching point, N Nip section, P1 First path, P2 Second path, P3 Third path, P4 Fourth path.

Claims

1. A processing execution unit that performs multiple processes, Multiple sensors provided in accordance with each of the multiple processes, A batch detection unit that detects a malfunction in any of the multiple sensors, For each of the multiple processes, a normal determination unit determines whether the process has been completed successfully based on the output value of the sensor corresponding to the process, A processing execution device comprising: a malfunction determination unit that, after a malfunction is detected in any of the multiple sensors, determines that at least one of the one or more sensors corresponding to one or more remaining processes, excluding one or more normal processes that have been determined to have completed successfully, is malfunctioning.

2. The processing execution device according to claim 1, further comprising a notification unit that notifies that at least one of the one or more sensors corresponding to each of the one or more remaining processes is malfunctioning.

3. The processing execution device according to claim 1, wherein the batch detection unit, after detecting a malfunction in any of the multiple sensors, refrains from detecting any malfunction in any of the multiple sensors until all of the multiple processes are completed.

4. The processing execution device according to claim 1, wherein the batch detection unit corrects the detection criteria for detecting a malfunction if the number of sensors in which a malfunction is detected among the plurality of sensors is greater than the number of remaining processes of 1 or more.

5. A power supply circuit that supplies power to multiple sensors via a shared connection line shared by multiple sensors, The system includes an ammeter for detecting the current value of the current flowing through the shared connection line, The processing execution device according to claim 1, wherein the batch detection unit detects a malfunction in any of the plurality of sensors based on the current value detected by the ammeter.

6. An image forming apparatus comprising a processing execution device according to any one of claims 1 to 5.

7. A method for determining defects that is executed by a processing execution device that performs multiple processes, The processing execution device includes a plurality of sensors, each of which is provided in accordance with the plurality of processes. A batch detection step for detecting a malfunction in any of the multiple sensors, For each of the multiple processes, a normal determination step is performed to determine whether the process has been completed successfully based on the output value of the sensor corresponding to the process. A malfunction determination method comprising: a malfunction determination step of determining that, after a malfunction is detected in any of the multiple sensors, at least one of the one or more sensors corresponding to one or more remaining processes, excluding one or more normal processes that have been determined to have completed successfully, is malfunctioning.

8. A fault detection program executed by a computer that controls a processing execution device that performs multiple processes, The processing execution device includes a plurality of sensors, each of which is provided in accordance with the plurality of processes. A batch detection step for detecting a malfunction in any of the multiple sensors, For each of the multiple processes, a normal determination step is performed to determine whether the process has been completed successfully based on the output value of the sensor corresponding to the process. A malfunction determination program that causes the computer to perform a malfunction determination step of determining that at least one of the sensors corresponding to one or more remaining processes, excluding one or more normal processes that have been determined to have completed successfully, is malfunctioning after a malfunction has been detected in any of the multiple sensors.

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