Image forming device

Abstract

To provide an image forming device that can discriminate whether or not a change of state of the image forming device is wrongly detected by being influenced by electrostatic noise.SOLUTION: When a change of state of an image forming device is detected, a current time T1 is obtained, and a time difference ▵T between the current time T1 at which the change of state is detected and a noise occurrence time Ts is determined (S702) referring to a timing Ts at which electrostatic noise is lastly detected (S701). When the time difference ▵T is smaller than a threshold Th2 (S703:YES), it is determined that the change of state is wrongly detected by being influenced by the electrostatic noise (S704), and when the time difference ▵T is smaller than the threshold Th2 (S703:NO), it is determined that the change of state (for instance, paper jamming) is normally detected (S705).SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present disclosure relates to an image forming apparatus, and more particularly to a technique for determining whether or not a false detection of the apparatus state is caused by electrostatic noise. [Background technology]

[0002] When an electrostatic discharge (ESD) occurs in electronic devices due to the proximity or contact of a charged object, high-voltage pulse electrostatic noise can enter the device, causing malfunction or destruction of integrated circuits (ICs). For example, in an image communication device, when reading an image from a document, if the pressure roller that conveys the document while pressing it against the image sensor becomes charged due to friction with the recording sheet, the charge accumulated on the pressure roller can be discharged electrostatically, destroying the image sensor.

[0003] To address this problem, a technology has been proposed in which a discharge member having a leaf spring shape is used to surround the pressure roller on all four sides, and the discharge member is pressed into contact with the conductive shaft of the pressure roller, so that the charge discharged from the outer circumferential surface of the pressure roller is temporarily received by the discharge member, and then discharged from the discharge member to ground via the conductive shaft (see, for example, Patent Document 1). This technology makes it possible to prevent the image sensor from being destroyed by static electricity discharge from the pressure roller.

[0004] However, since the contact force of the discharge member against the conductive shaft cannot be made too large in order to prevent the conductive shaft and the discharge member from being worn down by rubbing, the discharge member and the conductive shaft may become separated from each other if the pressing roller vibrates while rotating. Also, the surface material of the discharge member may deteriorate, resulting in a decrease in conductivity.

[0005] In these cases, the charge discharged from the outer peripheral surface of the pressure roller to the discharge member cannot escape from the discharge member to the conductive shaft, so that charge accumulates in the discharge member, increasing the charge on the discharge member. When the charge on the discharge member is discharged to the conductive shaft as a result of the increase in the charge on the discharge member, electrostatic noise is generated. Electrostatic noise can also be generated when the charge on the outer peripheral surface of the pressure roller is electrostatically discharged to the discharge member. This can cause the integrated circuit to malfunction or break down due to the intrusion of electrostatic noise.

[0006] When electrostatic noise causes an integrated circuit to malfunction, it is difficult to determine whether the integrated circuit itself has failed or whether the malfunction has occurred due to disturbances such as electrostatic noise. If electrostatic noise is the cause of the malfunction, the malfunction will continue to occur even if the integrated circuit is replaced unless the generation of electrostatic noise can be suppressed. Furthermore, even if it is presumed that electrostatic noise is the cause of the malfunction, if the source of the electrostatic noise cannot be identified, measures cannot be taken immediately to prevent the generation of electrostatic noise, and there is a problem that it takes a long time to resolve the malfunction of the integrated circuit.

[0007] To address this problem, a technology has been proposed in which a loop antenna is installed inside the image forming device to detect the noise frequency and noise level of electrostatic noise, and then it is determined whether the received electrostatic noise is at a fault level that will definitely cause failures in the various elements that make up the image forming device, a predictive level that may cause failures, or a normal level that is unlikely to cause failures, and then a warning is displayed (see Patent Document 2).

[0008] According to this conventional technique, if the electrostatic noise is at a normal level, it can be determined that the element itself is at fault. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2003-295347 A [Patent Document 2] Japanese Patent Application Publication No. 6-102724 Summary of the Invention [Problem to be solved by the invention]

[0010] However, with the above-mentioned conventional technology, when electrostatic noise is at a predictive or failure level, it is not possible to distinguish between a failure of an element and a malfunction caused by electrostatic noise, and therefore it is not possible to take appropriate measures according to the cause.

[0011] Such problems are not limited to malfunctions; when a change in the state of an image forming device is detected by a circuit that may malfunction due to the effects of electrostatic noise, it is not possible to determine whether this change is due to electrostatic noise or not, and appropriate measures cannot be taken in response to the change in the state of the device.

[0012] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide an image forming device that is capable of determining whether a change in the state of the image forming device has been erroneously detected due to the influence of electrostatic noise. [Means for solving the problem]

[0013] In order to achieve the above object, an image forming apparatus according to one embodiment of the present disclosure includes a status monitoring means for monitoring a status of an output signal of a sensor or a control board that fluctuates due to electrostatic noise, an electrostatic noise detection means for detecting electrostatic noise, an erroneous detection determination means for determining whether or not the status monitoring means has erroneously detected a change in the output signal due to electrostatic noise based on a detection result of the change in the output signal by the status monitoring means and a detection result of the electrostatic noise detection means, and an electrostatic noise source estimation means for estimating a plurality of electrostatic noise sources that may generate electrostatic noise and the electrostatic noise source that generated the electrostatic noise, wherein the electrostatic noise detection means: Corresponding to the plurality of electrostatic noise sources, Inside the device In the vicinity of each of the plurality of electrostatic noise sources, The electrostatic noise detection units have different detection sensitivities from each other. Each can recognize the strength of the electrostatic noise. The electrostatic noise source estimation means is characterized in that it identifies the electrostatic noise source depending on the detection sensitivity of the electrostatic noise detection section that detected the electrostatic noise.

[0014] In this case, the erroneous detection determination means may make the determination based on a result of a comparison between the timing at which the state monitoring means detected a change in the state of the device and the timing at which the electrostatic noise detection means detected electrostatic noise.

[0015] Also, An image forming apparatus according to another aspect of the present disclosure includes a status monitoring means for monitoring a status of an output signal of a sensor or a control board that fluctuates due to electrostatic noise, an electrostatic noise detection means for detecting electrostatic noise, and an erroneous detection determination means for determining whether or not the status monitoring means has erroneously detected a change in the output signal due to electrostatic noise, based on a detection result of the change in the output signal by the status monitoring means and a detection result of the electrostatic noise detection means. Electrostatic noise is generated Get multiple Electrostatic noise sources And, The state monitoring means monitors the states of the plurality of types of output signals, moreover, an electrostatic noise source estimation means for estimating an electrostatic noise source that has generated the electrostatic noise, depending on which of the plurality of types of output signals the state monitoring means has determined to have erroneously detected a change in when the electrostatic noise detection means detects electrostatic noise; and a storage means for storing electrostatic noise sources in order of the likelihood of generating electrostatic noise that will cause erroneous detection of a change in the output signal. An image forming apparatus according to yet another aspect of the present disclosure includes a status monitoring means for monitoring a status of an output signal of a sensor or a control board that fluctuates due to electrostatic noise, an electrostatic noise detection means for detecting electrostatic noise, an erroneous detection determination means for determining whether the status monitoring means has erroneously detected a change in the output signal due to electrostatic noise based on a detection result of the change in the output signal by the status monitoring means and a detection result of the electrostatic noise detection means, and a plurality of electrostatic noise sources that can generate electrostatic noise, wherein the status monitoring means monitors the status of the plurality of types of output signals, and further, when the electrostatic noise detection means detects electrostatic noise, the status monitoring means detects the status of the plurality of types of output signals. and storage means for storing, for each combination of the output signal and the electrostatic noise source, whether or not there is a possibility that the change in the output signal has been erroneously detected by generating electrostatic noise. When the state monitoring means detects a change in the output signal, the erroneous detection determination means determines that the change in the output signal has been normally detected if, from the contents stored in the storage means, there is no possibility that the electrostatic noise source estimated by the electrostatic noise source estimation means has caused the change in the output signal to be erroneously detected.

[0016] In addition, the apparatus may include a plurality of electrostatic noise sources that generate electrostatic noise, the electrostatic noise detection means detects electrostatic noise at a plurality of detection positions, and an electrostatic noise source estimation means estimates the electrostatic noise source that generated the electrostatic noise depending on which of the plurality of detection positions the electrostatic noise is detected at.

[0017] In addition, the electrostatic noise detection means may be provided with a plurality of electrostatic noise sources that generate electrostatic noise, and the electrostatic noise detection means may be provided with electrostatic noise source estimation means that detects the intensity of the electrostatic noise and estimates the electrostatic noise source that generated the electrostatic noise according to the intensity of the electrostatic noise.

[0021] The electrostatic noise detection means may further include a history recording means for recording the history of the timing at which the electrostatic noise detection means detected the electrostatic noise.

[0024] The result of the determination by the erroneous detection determination means may be displayed on the operation panel.

[0025] In addition, the result of the determination by the erroneous detection determination means may be notified to the data center.

[0026] In addition, the device status monitored by the status monitoring means may be notified via wiring on which electrostatic noise may be superimposed, and the wiring includes at least one of a wiring for transmitting a detection signal of a sensor and a communication wiring.

[0027] The electrostatic noise source includes at least one of an electrical contact that may generate electrostatic noise due to poor contact and a motor that may generate electrostatic noise due to a foreign object. Furthermore, the state monitoring means monitors the state of the output signal of the sensor, and the sensor is a plurality of sensors, which are arranged in the vicinity of each of the plurality of electrostatic noise detection units in correspondence therewith. Effect of the Invention

[0028] In this way, it is possible to determine whether a change in the device status of the image forming device has actually occurred or whether it has been erroneously detected due to electrostatic noise, thereby preventing the user from being erroneously notified that a change in the device status has occurred when in fact no change in the device status has occurred. [Brief description of the drawings]

[0029] [Figure 1] 1 is an external perspective view illustrating a main configuration of an image forming apparatus according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a diagram illustrating a configuration of a sheet conveying system included in the image forming apparatus 1. [Diagram 3] FIG. 2A is an external perspective view showing a configuration in which a transport roller is grounded using a leaf spring, and FIG. 2B is an external perspective view showing a configuration in which a transport roller is grounded using a coil spring. [Figure 4] 2 is a block diagram showing the main configuration of a control unit 111. FIG. [Diagram 5]4A is a block diagram showing the main configuration of the electrostatic noise detection circuit 411, and FIG. 4B is a diagram illustrating a noise waveform output by an analog receiving circuit 502 of the electrostatic noise detection circuit 411 and a noise detection signal output by a digital processing unit 503. [Figure 6] 4 is a flowchart illustrating a main routine of processing executed by control unit 111. [Figure 7] 13 is a flowchart illustrating an error cause identification process (S614) executed by the control unit 111. [Figure 8] 11 is a timing chart illustrating output signals of a first-stage paper feed sensor 241a, a timing sensor 243, a pre-paper discharge sensor 244, and an electrostatic noise detection circuit 411. [Figure 9] 11 is a table that records, for each sensor that is determined to have made an erroneous detection, candidates for the electrostatic noise source that caused the erroneous detection. [Figure 10] (a) is a diagram explaining the positional relationship between the image forming apparatus 1 main body and the cover unit, and (b) is an enlarged view of the dashed line portion 1000 in (a), showing the main configuration of the door opening / closing leaf spring that constitutes the grounding circuit extending between the image forming apparatus 1 main body and the cover unit when the cover unit is closed. [Figure 11] FIG. 11A is a block diagram showing the main configuration of a multi-level detection circuit having noise detection circuits 1101 and 1111 that detect two levels of electrostatic noise, strong and weak, and FIG. 11B is a block diagram showing a control unit 111 equipped with a CPU 401 having an A / D conversion circuit that converts the output signal of the noise detection circuit 1121 into a multi-level digital signal. [Figure 12] 11 is a diagram illustrating changes over time in electrostatic noise, exemplifying noise levels when the number of image formations is 10,000, 100,000, and 1,000,000. FIG. [Figure 13] FIG. 13 is a block diagram illustrating a configuration of a control unit 111 according to a modified example of the present disclosure. [Figure 14] 13 is a flowchart illustrating an error cause identification process according to a modified example of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] Hereinafter, an embodiment of an image forming apparatus according to the present disclosure will be described with reference to the drawings. [1] Configuration of image forming device First, the configuration of the image forming apparatus according to the present embodiment will be described.

[0031] As shown in FIG. 1, image forming apparatus 1 is a so-called tandem type color multi-function peripheral (MFP: Multi-Function Peripheral), and includes an image reading section 100, an image forming section 110, a paper feeding section 120, and an operation panel .

[0032] The image reading unit 100 includes an automatic document feeder 101 and a scanner unit 102. When reading a document using the sheet-through method, the automatic document feeder 101 feeds the document one sheet at a time from a stack of documents to the scanner unit 102. The scanner unit 102 generates image data by reading the document being fed by the automatic document feeder 101, or by reading the document placed on a platen glass (not shown) when reading a document using the platen set method.

[0033] The image forming unit 110 forms an image using image data generated by the image reading unit 100, image data received via a communication network (not shown), etc. The paper feed unit 120 supplies recording sheets used by the image forming unit 110 to form an image. The recording sheets on which the images have been formed are discharged outside the apparatus. The image forming unit 110 includes a control unit 111.

[0034] Control unit 111 controls the operation of each part of image forming apparatus 1. In particular, control unit 111 detects the operating state of image forming apparatus 1 (hereinafter referred to as "apparatus state") by, for example, monitoring output signals from sensors provided in each part of image forming apparatus 1. These sensors include electrostatic noise detection circuit 411, which will be described later, and detects electrostatic noise to prevent erroneous detection of the apparatus state and to detect the state of the electrostatic noise source.

[0035] Operation panel 130 includes, for example, a touch panel and hard keys, and presents information to a user of image forming apparatus 1 using a liquid crystal display (LCD) constituting the touch panel, and accepts instructions input by the user using the touch panel or hard keys. This allows image forming apparatus 1 to accept image reading jobs and image formation jobs. Image forming apparatus 1 may accept jobs via a communication network (not shown), such as a local area network (LAN) or the Internet. [2] Sheet transport system configuration When performing image formation processing, the image forming apparatus 1 conveys a recording sheet to be used for image formation. Next, the configuration of a sheet conveying system that conveys the recording sheet will be described. Note that, here, an example will be described in which the paper feed unit 120 has two paper feed trays, but the number of paper feed trays may be one, or three or more.

[0036] For example, when feeding recording sheets from the first-stage paper feed tray, as shown in FIG. 2, first-stage pickup roller 201a is used to feed the topmost recording sheet of the stack of recording sheets stored in the first-stage paper feed tray, and first-stage separation roller 203a is used to prevent double feeding of lower recording sheets, while first-stage paper feed roller 202a is used to transport the topmost recording sheet toward timing roller 206.

[0037] Both the first-stage paper feed sensor 241a and the timing sensor 243 detect the leading edge of the recording sheet. This allows the control unit 111 to determine the timing at which the leading edge of the recording sheet reaches the detection positions of the first-stage paper feed sensor 241a and the timing sensor 243. Note that the first-stage pickup roller 201a, the first-stage paper feed roller 202a, and the first-stage separation roller 203a are rotated by the first-stage paper feed motor 221a.

[0038] Similarly, when feeding recording sheets from the second-stage paper feed tray, second-stage pickup roller 201b is used to send out the recording sheets from the second-stage paper feed tray, and second-stage separation roller 203b is used to prevent double feeding of lower recording sheets, while second-stage paper feed roller 202b is used to transport the uppermost recording sheet toward second-stage vertical transport roller 204. Second-stage vertical transport roller 204 transports the recording sheet toward timing roller 206.

[0039] Both the second-stage paper feed sensor 241b and the second-stage vertical transport sensor 242 detect the leading edge of the recording sheet. This allows the control unit 111 to determine the timing at which the leading edge of the recording sheet reaches the detection positions of the second-stage paper feed sensor 241b and the second-stage vertical transport sensor 242. The second-stage pickup roller 201b, the second-stage paper feed roller 202b, and the second-stage separation roller 203b are rotated by the second-stage paper feed motor 221b. The second-stage vertical transport roller 204 is rotated by the second-stage vertical transport motor 222.

[0040] When feeding a recording sheet from the multi manual feed tray, a multi manual feed motor 223 rotates and drives a multi manual feed roller 205 to transport the recording sheet toward a timing roller 206 .

[0041] The photosensitive drums 211Y, 211M, 211C and 211K have yellow (Y), magenta (M), cyan (C) and black (K) toner images formed on their outer peripheral surfaces, and these toner images are electrostatically transferred from the photosensitive drums 211Y, 211M, 211C and 211K to the intermediate transfer belt 210 so that they overlap each other on the outer peripheral surface of the intermediate transfer belt 210 to become a color toner image (primary transfer).

[0042] The intermediate transfer belt 210 is wound around a drive roller 208 and a driven roller 209. When a main motor 225 drives and rotates the drive roller 208, the intermediate transfer belt 210 rotates and runs in the direction of arrow A. A secondary transfer roller 207 is pressed against the drive roller 208 with the intermediate transfer belt 210 sandwiched therebetween, thereby forming a secondary transfer nip. A color toner image is carried on the intermediate transfer belt 210 and transported to the secondary transfer nip.

[0043] With the timing roller 206 at a stop, the leading edge of the recording sheet abuts against the transport nip of the timing roller 206. The recording sheet is further transported with the leading edge abutting against the transport nip of the timing roller 206, and forms a loop. The formation of this loop corrects the skew of the recording sheet. Thereafter, the timing roller 206 is rotated by the timing motor 224, and transports the recording sheet to the secondary transfer nip.

[0044] A secondary transfer bias is applied to secondary transfer roller 207, and a toner image is electrostatically transferred from intermediate transfer belt 210 to a recording sheet at the secondary transfer nip. After the toner image is thermally fixed onto the recording sheet by fixing roller 212, the recording sheet is further transported by pre-discharge roller 213. Fixing roller 212 and pre-discharge roller 213 are rotated by fixing motor 226.

[0045] The pre-discharge sensor 244 detects the recording sheet downstream of the pre-discharge rollers 213 in the conveying direction of the recording sheet. This makes it possible to detect a paper jam at the fixing rollers 212 or the pre-discharge rollers 213.

[0046] The switching claw 214 is driven to swing by a solenoid actuator 231 to switch the conveying direction of the recording sheet. This causes the recording sheet to be guided to a paper discharge path 251 when it is discharged outside the image forming apparatus 1, and to a reversing roller 216 when an image is formed on the back side. The paper discharge roller 215 is driven to rotate by a paper discharge motor 227 to discharge the recording sheet from the paper discharge path 251 to the outside of the image forming apparatus 1.

[0047] The reversing roller 216 first receives the recording sheet by being rotated in the direction of arrow B by the reversing motor 228. Next, the reversing roller 216 reverses the conveying direction of the recording sheet by being rotated in the direction of arrow C by the reversing motor 228, and conveys the recording sheet to the paper reversing path 252.

[0048] In the paper inversion path 252, ADU (Automatic Duplex Unit) transport rollers 217, 218 are rotated and driven by an ADU transport motor 229 to transport the recording sheet. An ADU transport sensor 245 detects the leading edge of the recording sheet between the ADU transport rollers 217, 218 on the paper inversion path 252. If the ADU transport sensor 245 does not detect the leading edge of the recording sheet at the appropriate time, it is determined that a paper jam has occurred.

[0049] ADU transport rollers 219, 220 are rotated by an ADU transport motor 230 and transport the recording sheet towards timing roller 206. ADU transport sensor 246 detects the leading edge of the recording sheet between ADU transport rollers 219, 220 on paper reversal path 252. This allows a paper jam to be detected. In this way, an image is formed on the back side of the recording sheet, making double-sided printing possible.

[0050] Antennas 261a, 261b, 262 and 263 are disposed near the first stage paper feed sensor 241a, the second stage paper feed sensor 241b, the timing sensor 243 and the pre-discharge sensor 244, respectively, to receive electrostatic noise. Antennas other than the antennas 261a, 261b, 262 and 263 are not shown in the figure.

[0051] Needless to say, an antenna does not have to be provided for each sensor, but may be provided for each electrostatic noise source, and the number of antennas may be greater or less than the number of sensors and electrostatic noise sources. Also, as long as the receiving sensitivity is high enough to detect all electrostatic noise that may cause erroneous detection by the sensor, only one antenna may be used. [3] Electrical grounding structure of the transport roller As described above, image forming apparatus 1 is equipped with transport rollers such as first stage pickup roller 201a, first stage paper feed roller 202a, first stage handling roller 203a, second stage pickup roller 201b, second stage paper feed roller 202b, second stage handling roller 203b, second stage vertical transport roller 204, multi manual paper feed roller 205, timing roller 206, secondary transfer roller 207, drive roller 208, driven roller 209, fixing roller 212, pre-discharge roller 213, paper discharge roller 215, reversal roller 216 and ADU transport rollers 217, 218, 219, 220.

[0052] When conveying a recording sheet, these conveying rollers become charged due to friction with the recording sheet, or charges are transferred from the charged recording sheet to the conveying roller. As described above, in order to remove the charge on the surface of the conveying roller, an electrical contact is brought into contact with the conveying roller and the contact is grounded. When a conductive elastic member such as a leaf spring or a coil spring is used as the electrical contact, the elastic restoring force of the elastic member itself can be used to press the elastic member against the outer circumferential surface of the conveying roller.

[0053] When the surface of the transport roller is grounded using a leaf spring, as shown in Fig. 3(a), the transport roller 302 is made up of a roller portion 303 and a shaft portion 304. The conductive leaf spring 301 is fixed to a metal frame 305 so that the leaf spring 301 abuts against the outer circumferential surface of the roller portion 303 by the elastic restoring force of the leaf spring 301 itself. The frame 305 is grounded, and the electrostatic charge on the transport roller 302 can be removed via the leaf spring 301.

[0054] Furthermore, as illustrated in FIG. 3(b), when the surface of the transport roller is grounded using a coil spring, for a transport roller 302 in which both the roller portion 303 and the shaft portion 304 are conductive, a coil spring 310 consisting of an arm portion 311 and a coil portion 312 is used, and with the coil portion 312 wound around the shaft portion 304, the arm portion 311 is abutted against the frame 305.

[0055] When the transport roller 302 is driven to rotate in the direction of the arrow C and the shaft portion 304 and the coil portion 312 rub against each other, the coil spring 310 is also biased to rotate in the direction of the arrow C. As a result, when the arm portion 311 is pressed against the frame 305, the rotation of the coil spring 310 in the direction of the arrow C is restricted.

[0056] Then, as the coil portion 312 rubs against the shaft portion 304 rotating in the direction of arrow C, the coil portion 312 contracts in diameter and comes into close contact with the shaft portion 304, ensuring electrical conductivity between the shaft portion 304 and the coil spring 310, and the charged electric charge on the outer peripheral surface of the roller portion 303 is eliminated via the shaft portion 304, the coil spring 310, and the frame 305.

[0057] Alternatively, a discharge member for discharging electric charge from the transport roller 302 to ground may be biased toward the transport roller 302 by using a coil spring, and brought into sliding contact with the transport roller 302 .

[0058] If the leaf spring 301 or the coil spring 310 becomes dirty or the like and loses conductivity between it and the transport roller 302 or between it and the frame 305, it becomes impossible to remove the electrified charge on the transport roller 302. As a result, if charge continues to accumulate on the transport roller 302, electrostatic discharge occurs between the leaf spring 301 or the coil spring 310 and the transport roller 302 or between it and the frame 305, generating electrostatic noise. [4] Configuration of control unit 111 Next, the configuration of the control unit 111 will be described.

[0059] 4, the control unit 111 has a configuration in which a CPU (Central Processing Unit) 401, a ROM (Read Only Memory) 402, a RAM (Random Access Memory) 403, etc. are connected via an internal bus 410. When the image forming apparatus 1 is reset, for example when power is turned on, the CPU 401 reads a boot program from the ROM 402 and starts up. The CPU 401 uses the RAM 403 as a working storage area and reads an OS (Operating System) and a control program from a HDD (Hard Disk Drive) 404 and executes them.

[0060] A network interface card (NIC) 405 executes processing for communicating with other devices via a communication network such as a local area network (LAN) or the Internet, etc. This enables the image forming device 1 to accept image forming jobs from other devices and to send notifications to a data center.

[0061] Network support provides maintenance of image forming apparatus 1 and other services to users who have signed a service contract for network support among users who use image forming apparatus 1. To provide this service, the data center accepts various information provided by image forming apparatus 1. The data center may include a server device that receives information from image forming apparatus 1, or may use a cloud system. Timer 406 is used to obtain the current time and measure elapsed time.

[0062] The electrostatic noise detection circuit 411 is a circuit that detects electrostatic noise inside the image forming apparatus 1. As shown in Fig. 5(a), the electrostatic noise detection circuit 411 includes an analog receiving circuit 502 and a digital processing unit 503. In this embodiment, an antenna 501 is connected to the analog receiving circuit 502, but an antenna may be mounted on the analog receiving circuit 502, or another type of antenna may be used as long as it is capable of receiving electrostatic noise.

[0063] Analog receiving circuit 502 has a built-in amplifier circuit, and amplifies the electrostatic noise signal received using antenna 501, and inputs the amplified signal to digital processing unit 503. In this embodiment, after removing the DC component of the electrostatic noise signal by AC coupling, only the AC component of the electrostatic noise signal is amplified using a transistor or the like. In this way, even if the electrostatic noise signal is weak compared to the DC component, it can be detected with high accuracy.

[0064] 5(b) shows an example of the waveform of an electrostatic noise signal input from the analog receiving circuit 502 to the digital processing unit 503. When a high voltage is applied with the electrical contacts separated and electrostatic noise is generated by electrostatic discharge, the duration of the electrostatic noise signal becomes extremely short. Specifically, electrostatic noise often occurs in a short period of time of several tens of nanoseconds.

[0065] The digital processing unit 503 includes an A / D (Analogue to Digital) conversion circuit, which converts the analog signal input from the analog receiving circuit 502 into a digital signal and maintains the ON state for a predetermined time (for example, one clock). Specifically, when the amplitude of the input signal from the analog receiving circuit 502 exceeds a threshold, it determines that electrostatic noise has occurred, latches the digitized electrostatic noise signal, and maintains the ON state for a predetermined time. After the latch, it clears the signal and returns to the OFF state after the predetermined time has elapsed.

[0066] As mentioned above, the duration of the electrostatic noise signal may be extremely short, so a high-speed A / D conversion circuit must be used. Of course, as shown in FIG. 5(b), the digital signal generated by the digital processing unit 503 is maintained in the ON state for a period longer than the duration of the electrostatic noise signal.

[0067] The digital processing unit 503 inputs such a digital signal to the control unit 111. Note that the digital processing unit 503 may be provided in the control unit 111 instead of in the electrostatic noise detection circuit 411. If the CPU 401 has a built-in A / D conversion circuit, instead of providing the digital processing unit 503, the electrostatic noise signal may be digitized using the A / D conversion circuit built into the CPU 401.

[0068] In these cases, there is a risk that the waveform of the electrostatic noise signal may be distorted on the wiring from the analog receiving circuit 502 to the digital processing unit 503 or the CPU 401. Therefore, in order to prevent distortion of the signal waveform, it is effective to take measures to increase the amplification factor of the electrostatic noise signal in the analog receiving circuit 502. In addition, it is desirable that the A / D conversion circuit built into the CPU 401 is also high-speed.

[0069] The control unit 111 determines the transport state of the recording sheet as the device status of the image forming apparatus 1 by referring to the sensor signals output by the first stage paper feed sensor 241a, the second stage paper feed sensor 241b, the second stage vertical transport sensor 242, the timing sensor 243, the pre-discharge sensor 244 and the ADU transport sensors 245, 246.

[0070] These sensors may include a light-emitting unit and a light-receiving unit, and may detect the conveyance state of the recording sheet by detecting with the light-receiving unit that the light emitted from the light-emitting unit is blocked by the recording sheet. Alternatively, the sensors may further include an arm unit that is pushed down by the leading edge of the recording sheet and a light-shielding unit that swings together with the arm unit, and may detect the conveyance state of the recording sheet by detecting with the light-receiving unit whether the light-shielding unit is blocking the light emitted from the light-emitting unit. Furthermore, other types of sensors may be applied.

[0071] When electrostatic noise occurs, an induced current flows in the light-emitting section, causing the light-emitting section to fluctuate in its illumination state, which may result in erroneous detection of the recording sheet. Also, when electrostatic noise causes an induced current to flow in the light-receiving section, the output of the light-receiving section fluctuates, which may result in erroneous detection.

[0072] In addition, the control unit 111 outputs control signals to a first stage feed motor 221a, a second stage feed motor 221b, a second stage vertical transport motor 222, a multi manual feed motor 223, a timing motor 224, a main motor 225, a fixing motor 226, a discharge motor 227, a reversing motor 228, an ADU transport motors 229, 230, and a solenoid actuator 231, thereby controlling the operation of these motors and solenoid actuators.

[0073] These motors wear out over time and produce conductive metal powder. If this metal powder accumulates inside the motor and shorts out the current-carrying parts inside the motor, it can generate electrostatic noise. [5] Operation of control unit 111 As described above, when electrostatic noise occurs and the output signal of the sensor fluctuates, there is a risk that control unit 111 may erroneously detect the state of image forming apparatus 1. For this reason, in the present embodiment, electrostatic noise is detected to determine whether control unit 111 has erroneously detected the apparatus state.

[0074] In the following, the operation of the control unit 111 will be described taking as an example a case where the output signal of the first-stage paper feed sensor 241a that detects a recording sheet on the recording sheet transport path fluctuates due to electrostatic noise. It goes without saying that the control unit 111 can determine whether or not the device state has been erroneously detected in the same manner when a recording sheet is detected using another sensor or when another device state is detected. (5-1) Main routine 6, when the control unit 111 feeds recording sheets from the first-stage paper feed tray (S601: YES), it starts driving the first-stage paper feed motor 221a (S602). This causes the first-stage pickup roller 201a, the first-stage paper feed roller 202a, and the first-stage separation roller 203a to rotate, and the feeding of recording sheets starts.

[0075] Next, the control unit 111 refers to the timer 406 to obtain the current time as the paper feed start time T0 (S603), and calculates the sheet detection scheduled time Te by adding the required time Tr from when the recording sheet starts to be fed until it reaches the sheet detection position of the first-stage paper feed sensor 241a to the paper feed start time T0 (S604). Note that the required time Tr may be stored in the HDD 404 in advance, or may be calculated by dividing the conveying distance of the recording sheet from the first-stage paper feed tray to the sheet detection position of the first-stage paper feed sensor 241a by the conveying speed of the recording sheet (system speed).

[0076] Next, the control unit 111 refers to the timer 406 to obtain the current time T1 (S605), and also refers to the output of the electrostatic noise detection circuit 411. If the result of this reference indicates that the electrostatic noise detection circuit 411 has detected electrostatic noise (S606: YES), the control unit 111 records the current time T1 as the noise occurrence time Ts (S607).

[0077] If the electrostatic noise detection circuit 411 does not detect electrostatic noise (S606: NO) and after completing the process of step S607, the control unit 111 refers to the output of the first-stage paper feed sensor 241a, and if the leading edge of the recording sheet has been detected (S608: YES), calculates the time difference (absolute value of the time difference) between the current time T1 and the scheduled sheet detection time Te. If the time difference (|T1-Te|) is greater than the threshold value Th1 (S613: YES), it means that the leading edge of the recording sheet was detected at a timing significantly different from the scheduled sheet detection time Te at which the first-stage paper feed sensor 241a was supposed to detect the leading edge of the recording sheet.

[0078] Therefore, since it is possible that either a paper jam has occurred or that a paper jam has been erroneously detected, an error cause identification process is executed to identify which of these has occurred (S614). The detection of a recording sheet by the first-stage paper feed sensor 241a can be said to be detection of a change in the device state of the image forming apparatus 1. The control unit 111 monitors the device state of the image forming apparatus 1 using not only the first-stage paper feed sensor 241a but also various other sensors and other means, and detects the change in the device state. This change in the device state may be erroneously detected due to electrostatic noise.

[0079] In addition, threshold value Th1 represents the range of fluctuation of the expected sheet detection time Te when first-stage paper feed sensor 241a normally detects a recording sheet, taking into account that the time at which first-stage paper feed sensor 241a detects a recording sheet may vary due to delays caused by slippage between first-stage pickup roller 201a, first-stage paper feed roller 202a, and first-stage handling roller 203a and the recording sheet.

[0080] On the other hand, if the time difference (|T1-Te|) is smaller than the threshold value Th1 (S613: NO), the first-stage paper feed sensor 241a detects the leading edge of the recording sheet at a timing close to the scheduled sheet detection time Te. Therefore, the recording sheet is normally transported without any problems such as a paper jam, and the process ends.

[0081] If the first-stage paper feed sensor 241a has not detected a recording sheet (S608: NO), the excess time (T1-Te) is calculated by subtracting the scheduled sheet detection time Te from the current time T1. If the excess time (T1-Te) is greater than the threshold value Th1 (S609: YES), the recording sheet has not reached the recording sheet detection position of the first-stage paper feed sensor 241a even if the time elapsed from the scheduled sheet detection time Te at which the first-stage paper feed sensor 241a is supposed to detect the leading edge of the recording sheet is long.

[0082] Therefore, it is determined that a paper jam has occurred (S610), and an error code indicating that a paper jam has occurred is displayed on the operation panel 130 (S611). Furthermore, the occurrence of a paper jam is notified to the data center (S612), and the process ends. If the excess time (T1-Te) is equal to or less than the threshold value Th1 (S609: NO), the process proceeds to step S605, and the above process is repeated.

[0083] In addition, in order to provide maintenance services for image forming device 1 to users who have signed a maintenance contract for image forming device 1, the data center receives data regarding the device status from image forming device 1 via the communication network and determines whether or not maintenance services are necessary and the content of such services. (5-2) Error cause identification process (S614) 7, in the error cause identification process (S614), first, the noise occurrence time Ts recorded in step S607 of the main routine is referenced (S701), and the time difference (absolute value of the time difference) ΔT between the noise occurrence time Ts and the current time T1 is calculated (S702). If the time difference ΔT is smaller than the threshold value Th2 (S703: YES), the timing when the first-stage paper feed sensor 241a detected the recording sheet is close to the timing when the electrostatic noise occurred, so it is determined that the first-stage paper feed sensor 241a erroneously detected the recording sheet due to the influence of the electrostatic noise (S704).

[0084] On the other hand, if the time difference ΔT is equal to or greater than the threshold value Th2 (S703: NO), the timing when the first-stage paper feed sensor 241a detected the recording sheet is far from the timing when the electrostatic noise occurred, so it is unlikely that the first-stage paper feed sensor 241a erroneously detected the recording sheet due to the influence of the electrostatic noise. Therefore, it is determined that the first-stage paper feed sensor 241a detected the recording sheet because a paper jam occurred due to disturbance in the behavior of the recording sheet or the like (S705).

[0085] Thereafter, an error code according to the determination result is displayed on the operation panel 130 (S706). If it is determined that the first stage paper feed sensor 241a has erroneously detected the recording sheet due to the influence of electrostatic noise, an error code to that effect is displayed on the operation panel 130, and if it is determined that a paper jam has occurred, an error code to that effect is displayed on the operation panel 130. Furthermore, after notifying the data center of the determination result (S707), the process returns to the main routine.

[0086] Even if it is determined that the first stage paper feed sensor 241a has erroneously detected a recording sheet due to the effects of electrostatic noise, since no paper jam has occurred, the user of the image forming apparatus 1 has no task to perform. Therefore, if it is considered that there is no particular benefit to the user even if an error code is displayed on the operation panel 130, it is also effective to not display the error code on the operation panel 130.

[0087] In this way, whether the first stage paper feed sensor 241a has erroneously detected the recording sheet is determined depending on the proximity between the timing of detection of the recording sheet by the first stage paper feed sensor 241a and the timing of the occurrence of electrostatic noise, so it is possible to determine whether a paper jam has actually occurred or whether the erroneous detection is due to electrostatic noise. [6] How to identify the source of electrostatic noise In the above-described embodiment, even if electrostatic noise occurs, depending on the strength and frequency of the electrostatic noise, it may not affect the operation of the first-stage paper feed sensor 241a and may not cause erroneous detection. However, when electrostatic noise occurs, there is a possibility that a problem has occurred in the source of the electrostatic noise (hereinafter, referred to as the "electrostatic noise source") itself. Therefore, by monitoring the electrostatic noise, the control unit 111 can grasp the signs of trouble in the electrostatic noise source. (6-1) Relationship between the erroneous detection sensor and the source of electrostatic noise For example, if a double feed of recording sheets occurs when feeding recording sheets from the first-stage paper feed tray, the double-fed sheets will be fed the next time the recording sheets are fed, but the leading edge of the double-fed sheets will be outside the paper feed tray, and the first-stage paper feed sensor 241a will detect the leading edge of the double-fed sheets earlier than the scheduled sheet detection time Te by the threshold value Th1 or more. On the other hand, as shown in Fig. 8, when electrostatic noise occurs, the first-stage paper feed sensor 241a may erroneously detect the recording sheets at the same timing.

[0088] In such a case, if the time difference ΔT between the timing when the first stage paper feed sensor 241a detects the recording sheet and the timing when the electrostatic noise detection circuit 411 detects the electrostatic noise is less than threshold value Th2, it can be determined that the first stage paper feed sensor 241a has erroneously detected the recording sheet due to electrostatic noise.

[0089] 8, no effect of electrostatic noise is observed on timing sensor 243 or pre-discharge sensor 244 at the same timing. Therefore, it is considered that the electrostatic noise source that generated the electrostatic noise is located close to first-stage paper feed sensor 241a. In other words, when electrostatic noise is detected by electrostatic noise detection circuit 411, it is possible to estimate which electrostatic noise source generated the electrostatic noise based on which sensor erroneously detected the recording sheet.

[0090] Fig. 9 is a table that records, for each sensor that has been determined to have detected an incorrect signal, possible sources of electrostatic noise that caused the incorrect signal. Using such a table is effective in identifying the source of electrostatic noise. In particular, when electrostatic noise is thought to have been generated repeatedly from the same electrostatic noise source, unlike when electrostatic noise is generated from the electrostatic noise source in a single burst, there is a high possibility that there is some problem with the electrostatic noise source. For this reason, it is considered necessary to take measures such as replacing the electrostatic noise source.

[0091] 9, for first-stage paper feed roller 202a, timing roller 206, and pre-discharge roller 213, when these rollers become charged due to friction with a recording sheet, etc., a leaf spring, coil spring, etc. are used as a biasing member for bringing a discharging member into contact with these rollers to discharge the electric charge to ground. When the biasing force of the biasing member decreases due to deterioration over time, etc., the discharging member separates from the roller.

[0092] When the charge on the roller increases while the discharge member is separated, electrostatic noise is generated due to electrostatic discharge. First-stage paper feed roller 202a, timing roller 206, and pre-discharge roller 213 are disposed near first-stage paper feed sensor 241a, timing sensor 243, and pre-discharge sensor 244, respectively, and are therefore the first candidates for the source of electrostatic noise.

[0093] The sheet transport guide, which guides the recording sheet during transport, can also become charged due to friction with the recording sheet, etc. The sheet transport guide is grounded by being fixed to the main body of the image forming apparatus 1 with a screw, but if there is poor contact between the screw and the sheet transport guide, or between the screw and the main body of the image forming apparatus 1, the sheet transport guide becomes a so-called floating metal plate, and it becomes impossible to neutralize the static electricity from the sheet transport guide.

[0094] In this state, if the charge on the sheet transport guide continues to increase, the potential difference between the sheet transport guide and members other than the sheet transport guide, such as the main body of the image forming apparatus 1, will increase, eventually causing electrostatic discharge and generating electrostatic noise. If the sheet transport guide is fastened with a screw near the first-stage paper feed sensor 241a, the sheet transport guide joining screw may be the second candidate.

[0095] First-stage feed motor 221a, timing motor 224, and fixing motor 226 wear out as they are rotated, generating metal powder. Paper powder generated from recording sheets can also be conductive under high humidity conditions. If such foreign matter is present inside the motors, it can cause a short circuit and generate noise.

[0096] The secondary transfer high voltage contact is a contact for applying a secondary transfer bias voltage to the secondary transfer roller 207, and is, for example, a leaf spring that rubs against the shaft of the secondary transfer roller 207. Since the secondary transfer bias voltage is high, if the leaf spring deteriorates over time or is subjected to vibration, and the contact becomes separated, noise may occur due to discharge.

[0097] A contact for applying a primary transfer bias is provided on the primary transfer rollers (not shown) that electrostatically transfer the toner images from the photoconductor drums 211Y, 211M, 211C, and 211K to the intermediate transfer belt 210. This primary transfer high voltage contact is also a high voltage, and therefore can become a noise source that generates noise due to discharge when the leaf spring deteriorates over time or vibration is applied and the contact separates. Therefore, depending on the distance between these contacts and the sensor, the secondary transfer high voltage contact and the primary transfer high voltage contact can also be candidates for electrostatic noise sources.

[0098] 10(a) and 10(b), the door opening / closing leaf spring constitutes a contact point that is interposed in a circuit from the secondary transfer high voltage contact point to ground. The door opening / closing leaf spring is composed of a leaf spring 1001 fixed to a main body side frame 1002 and a leaf spring 1011 fixed to a cover unit side frame 1012, and the leaf springs 1001 and 1011 abut against each other to form a ground circuit.

[0099] If the leaf springs 1001 and 1011 become separated due to deterioration over time or vibration, noise may be generated due to discharge. If the door opening / closing leaf spring is disposed near the timing sensor 243, it may become a candidate for a source of electrostatic noise in the event of an erroneous detection by the timing sensor 243. The cover unit may also function as a duplex transport unit when performing duplex printing.

[0100] The discharge outlet static neutralizing cloth is disposed at the discharge outlet for discharging the recording sheet on which an image has been formed outside the apparatus, and neutralizes the recording sheet that has become charged during image formation. Therefore, the discharge outlet static neutralizing cloth itself is easily charged, and when the amount of charge increases, static electricity discharge generates static noise. In particular, if it is located near the pre-discharge sensor 244, it may be a candidate for the source of static noise that caused the pre-discharge sensor 244 to detect the image erroneously.

[0101] When the control unit 111 determines that the sensor has made a false detection due to electrostatic noise, it may display candidates for the electrostatic noise source on the operation panel 130 or may notify the data center. In this way, when electrostatic noise is being generated due to a problem with the electrostatic noise source, the problem with the electrostatic noise source can be quickly resolved. (6-2) Electrostatic noise detection circuit 411 and electrostatic noise source The electrostatic noise detection circuit 411 may detect electrostatic noise by providing antennas 401 at multiple locations. For the purpose of determining the cause of erroneous detection by the sensor, it is preferable to provide multiple antennas 401 inside the image forming apparatus 1.

[0102] By disposing antennas 401 at locations that may be electrostatic noise sources, it is possible to identify the electrostatic noise source at the location corresponding to antenna 401 that detects the strongest electrostatic noise as the electrostatic noise source that caused the erroneous detection. Even if the number of antennas 401 is smaller than the number of electrostatic noise sources, it is possible to estimate the electrostatic noise source from the combination of electrostatic noise intensities detected for each antenna 401.

[0103] For example, four antennas are disposed inside the image forming apparatus 1. In this case, the four antennas are disposed so as not to be located on the same plane. Since the power of radio waves attenuates in proportion to the inverse of the square of the distance, the distance from an antenna to the electrostatic noise source is proportional to the inverse of the square root of the power of the electrostatic noise received by that antenna. Therefore, for two antennas, the electrostatic noise source exists on a plane where the distance from each antenna is in the ratio of the inverse of the square root of the power of the electrostatic noise received by that antenna.

[0104] When there are three antennas, the electrostatic noise source exists on a line where the distance from each antenna is in the ratio of the reciprocal of the square root of the received power. Similarly, when there are four antennas, the position of the electrostatic noise source can be identified from the ratio of the reciprocal of the square root of the received power of the electrostatic noise.

[0105] Furthermore, since the manner in which electrostatic noise propagates inside the image forming device 1 differs from that in free space, the position of the electrostatic noise source can be estimated with even greater accuracy by adjusting the ratio of the distance from the antenna to the electrostatic noise source according to the specific device configuration.

[0106] 11(a), a plurality of noise detection circuits 1101, 1111 are connected to one antenna 1100 to provide a difference in sensitivity to electrostatic noise between the noise detection circuits 1101, 1111. The weak noise detection circuit 1101 includes an analog receiving circuit 1102 and a digital processing unit 1103, and when the output of the analog receiving circuit 1102 is 10 mV or more, the digital processing unit 1103 detects electrostatic noise.

[0107] On the other hand, the strong noise detection circuit 1111 includes an analog receiving circuit 1112 and a digital processing unit 1113, and when the output of the analog receiving circuit 1112 is 50 mV or more, the digital processing unit 1113 detects electrostatic noise.

[0108] Needless to say, the number of noise detection circuits does not need to be two, strong and weak, and may be three or more stages for multi-stage. Also, instead of making the outputs of the analog receiving circuits 1102, 1112 that the digital processing units 1103, 1113 use to detect electrostatic noise different from each other, the outputs of the digital processing units 1103, 1113 that detect electrostatic noise may be made the same, and the amplification factors in the analog receiving circuits 1102, 1112 may be made different.

[0109] 11(b), the noise detection circuit 1121 may include only a noise amplification circuit 1122 that amplifies a noise signal acquired from an antenna 1120, and the noise signal may be converted into a multi-bit digital signal using an A / D conversion circuit 1123 provided in a CPU 401 included in the control unit 111. Alternatively, an A / D conversion circuit may be provided in the control unit 111 separately from the CPU 401 to convert the analog output signal of the noise detection circuit 1121 into a multi-bit digital signal, and then input to the CPU 401.

[0110] Such an A / D conversion circuit may be an A / D conversion circuit that can recognize the strength of noise by directly inputting the level of the analog signal output by the noise detection circuit 1121. Since electrostatic noise lasts for an extremely short period of time, on the order of tens of nanoseconds, it is preferable to use a high-speed A / D conversion circuit.

[0111] The electrostatic noise detection circuit and control unit 111 as described above may be used to detect the intensity of electrostatic noise.

[0112] In this way, by disposing antennas respectively in the vicinity of first-stage paper feed roller 202a, timing roller 206, and pre-discharge roller 213, and detecting the intensity of electrostatic noise on a five-level scale, for example, when electrostatic noise level is detected as 1 in the vicinity of first-stage paper feed roller 202a, level 4 in the vicinity of timing roller 206, and level 3 in the vicinity of pre-discharge roller 213, it can be determined that the distance to the electrostatic noise source is the farthest for timing roller 206, the intermediate for pre-discharge roller 213, and the closest for first-stage paper feed roller 202a. Furthermore, taking the arrangement of the antennas into consideration, the secondary transfer high voltage contact becomes the first candidate for the electrostatic noise source. [7] Electrostatic noise occurrence history In the above, we have described the case where only the time when electrostatic noise was most recently detected is recorded and the source of electrostatic noise is determined from the intensity of the electrostatic noise. However, the intensity of electrostatic noise may change as the electrostatic noise source deteriorates over time. In such cases, it is effective to record the detection history of the electrostatic noise intensity, since it is possible to obtain information about the electrostatic noise source, such as deterioration over time.

[0113] For this reason, the control unit 111 refers to the output signal of the electrostatic noise detection circuit 411 regardless of the operating state of the image forming apparatus 1, and repeats the process of detecting the date and time when the electrostatic noise occurred and its intensity, thereby recording the detection history of the electrostatic noise.

[0114] As a result, for example, it is assumed that a detection history such as that shown in Fig. 12 has been obtained. The intensity of the electrostatic noise shown in Fig. 12 increases as the number of images formed by the image forming apparatus 1 increases to 10,000 sheets (10 kp) and then to 100,000 sheets (100 kp), and when the number of images formed reaches 1,000,000 sheets (1,000 kp), it is determined that the number exceeds a given threshold and maintenance is required, and a maintenance requirement notice is sent from the image forming apparatus 1 to the data center.

[0115] In this way, by monitoring the strength of electrostatic noise, it is possible to detect signs of problems that could lead to more serious problems than just electrostatic noise at the source of the electrostatic noise, and take measures such as replacing parts before the problem occurs, thereby preventing the occurrence of such problems.

[0116] In addition, multiple thresholds for the strength of electrostatic noise may be set, and each time the electrostatic noise exceeds a threshold, the warning level may be raised and a warning message may be displayed on the operation panel or a warning may be sent to the data center. [8] Variations While the present disclosure has been described above based on the embodiments, it goes without saying that the present disclosure is not limited to the above-described embodiments, and the following modified examples can be implemented. (8-1) In the above embodiment, a leaf spring is used as a discharging member to mainly neutralize the charge on the conveying roller. However, it goes without saying that the present disclosure is not limited to this, and the following may be used instead of or in addition to this.

[0117] As described above, various motors are mounted on the image forming apparatus 1. For example, as shown in Fig. 13, a control signal is input to the motors 1332 and 1334, and the motors rotate in response to this control signal. In addition, the motors 1332 and 1334 are provided with sensors that monitor the rotation state, and feedback control of the motors 1332 and 1334 is performed by acquiring the rotation state of the motor from the sensor output. If the timing at which this feedback signal changes is close to the timing at which electrostatic noise is detected, it can be assumed that the electrostatic noise has been generated from an electrostatic noise source located near the motor 1332 or 1334.

[0118] Furthermore, the control unit 111 may be composed of a plurality of circuit boards. When a drive control board 1311 equipped with an ASIC (Application Specific Integrated Circuit) 1312 is used in addition to the control board 1301 equipped with the CPU 401, control signals and the like are exchanged between the two circuit boards 1301, 1311 via communication wiring 1321 since the CPU 401 needs to control the operation of the ASIC 1312. Electrostatic noise may affect communication signals between such boards 1301, 1311.

[0119] Therefore, if the timing when a communication error occurs between boards 1301 and 1311 is close to the timing when electrostatic noise is detected, it can be assumed that the electrostatic noise occurred from an electrostatic noise source located near the communication wiring 1321 between the boards.

[0120] Even in the above manner, the electrostatic noise source that generated the electrostatic noise can be estimated, which is effective in discovering abnormalities such as deterioration over time of the electrostatic noise source. As a result, by replacing or repairing an electrostatic noise source that is determined to be unable to continue normal operation, the electrostatic noise source can continue to operate normally and the generation of electrostatic noise can be prevented, thereby maintaining normal operation of the image forming apparatus 1. (8-2) In the above embodiment, an example was described in which a case was described in which a change in the device state was determined to have been erroneously detected when the timing at which electrostatic noise was detected and the timing at which a change in the device state of image forming device 1 was detected were close in time. However, it goes without saying that the present disclosure is not limited to this, and the following may also be adopted in addition to this.

[0121] For example, if there are multiple sources of electrostatic noise and it is possible to estimate which electrostatic noise source generated the electrostatic noise as described above, if the estimated electrostatic noise source is not included in the candidates that may cause a false detection in the sensor that detected the change in the device state, as illustrated in Figure 9, it may be determined that the change in the device state was detected normally even if the timing at which the electrostatic noise was detected and the timing at which the change in the device state was detected are close in time.

[0122] 14, if the time difference ΔT between the current time T1 at which the change in the device state was detected and the noise occurrence time Ts at which the electrostatic noise was detected is smaller than the threshold value Th2 (S1403: YES), the electrostatic noise source is estimated as described above (S1404). Then, if the estimated electrostatic noise source is included in the candidates for electrostatic noise sources that may cause the change in the device state to be erroneously detected (S1405: YES), it is determined that the change in the device state has been erroneously detected due to the electrostatic noise (S1406).

[0123] In the above, the table illustrated in FIG. 9 is used as a table that stores, for each combination of device state and electrostatic noise source, the possibility of falsely detecting a change in the device state. However, as illustrated in FIG. 9, the table may be a list of electrostatic noise sources that have the possibility of falsely detecting a change in the device state without storing the candidate ranking, or conversely, a table that lists electrostatic noise sources that have no possibility of falsely detecting a change in the device state.

[0124] On the other hand, if the estimated electrostatic noise source is not included in the candidates for electrostatic noise sources that may erroneously detect the change in the device state (S1405: NO), it is determined that the device state has changed (S1407). In this way, even if electrostatic noise and a change in the device state are detected at close timings, but are independent events with no causal relationship, it can be correctly determined that the device state has changed.

[0125] As long as it is possible to check whether or not an electrostatic noise source has the potential to cause a false detection of a change in the device state, it is not necessary to store the order of likelihood as in the table exemplified in Fig. 9. In other words, it is possible to store only whether or not, for each device state, the device state has the potential to cause a false detection of a change in the device state. (8-3) In the above embodiment, an example was described in which the presence or absence of a change in the device state of image forming apparatus 1 was detected. However, it goes without saying that the present disclosure is not limited to this, and it is also possible to detect the magnitude of the change in the device state.

[0126] In particular, if a history of the timing at which electrostatic noise was detected and its intensity is recorded, the possibility (level of concern) that the change in the device status will be erroneously detected can be determined based on only the intensity of the electrostatic noise, or a combination of the intensity of the electrostatic noise and the magnitude of the change in the device status, and this can be displayed on the operation panel 130 or a notification can be sent to the data center.

[0127] In this way, the possibility of false detection occurring before a change in the device state is falsely detected can be known, so that the source of the limited noise can be identified and measures taken to prevent electrostatic noise from occurring before a false detection actually occurs. Therefore, false detection of a change in the device state can be prevented, and normal operation of the image forming device 1 can be more reliably guaranteed. (8-4) In the above embodiment, the electrostatic noise detection circuit 411 is described as having one analog receiving circuit 502 and one digital processing unit 503, but it goes without saying that the present disclosure is not limited to this, and instead, the following may be used. For example, the electrostatic noise detection circuit 411 may have a plurality of analog receiving circuits 502, each of which is connected to a different antenna, and the digital processing unit 503 outputs digital data having a number of bits equal to or greater than the number of analog receiving circuits 502 to the control unit 111.

[0128] The digital processing unit 503 detects electrostatic noise and sets a bit corresponding to the analog receiving circuit 502 whose output is above the threshold, and clears the bit corresponding to the analog receiving circuit 502 whose output is below the threshold, and outputs digital data to the control unit 111, allowing the control unit 111 to confirm which antenna detected the electrostatic noise.

[0129] Furthermore, the output value of the analog receiving circuit 502 may be A / D converted to multi-bit digital data representing the magnitude of the output value, rather than one bit representing whether or not the threshold has been exceeded, and output to the control unit 111. In this way, the control unit 111 can obtain the strength of the electrostatic noise detected for each antenna. (8-5) When there are multiple electrostatic noise sources that generate electrostatic noise that can be detected by the electrostatic noise detection circuit 411, the electrostatic noise detection circuit 411 cannot identify which electrostatic noise source generated the electrostatic noise simply by detecting the electrostatic noise.

[0130] However, in the case of a change in the device state of image forming device 1 that has only one electrostatic noise source that generates electrostatic noise that causes the change to be falsely detected, once it is known that the change has been falsely detected, it is possible to identify which electrostatic noise source generated the electrostatic noise.

[0131] In addition, if there is only one electrostatic noise source that generates electrostatic noise that causes multiple types of changes to be erroneously detected simultaneously, once it is known that these multiple types of changes have been erroneously detected simultaneously, it is possible to identify which electrostatic noise source caused the electrostatic noise.

[0132] Therefore, if the control unit 111 stores in advance a combination of a pattern of which of a plurality of types of changes in the device state have been erroneously detected, and an electrostatic noise source that generates the electrostatic noise that causes the erroneous detection of the change, the electrostatic noise source can be identified from the pattern of erroneous detection. As described above, if the electrostatic noise generation status of each electrostatic noise source can be grasped, the deterioration over time and lifespan of each electrostatic noise source can be diagnosed and appropriate maintenance can be performed. Therefore, the availability and reliability of the image forming apparatus 1 can be improved. (8-6) In the above embodiment, a case has been described where a change in the device state of image forming device 1 is erroneously detected due to electrostatic noise. However, it goes without saying that the present disclosure is not limited to this. Even in the case where a change in the device state is erroneously detected due to a cause other than electrostatic noise, if the occurrence of the cause of the erroneous detection is also detected when the change in the device state is detected, it may be determined that the change in the device state has been erroneously detected.

[0133] Furthermore, when there are multiple causes of erroneous detection, it is possible to infer from which source the cause of the erroneous detection occurred based on which change in the device state was erroneously detected. This makes it possible to grasp the occurrence status of the erroneous detection causes for each source and diagnose the deterioration status of the sources, etc.

[0134] For example, in cases where vibrations caused by wear or deformation of mechanical parts result in erroneous detection of the device status by a mechanical sensor, the present disclosure can be applied in the same way as with electrostatic noise. (8-7) In the above embodiment, the image forming apparatus 1 is described as a tandem color multifunction machine, but the present disclosure is not limited to this, and may be a color multifunction machine of a type other than the tandem type, or may be a monochrome multifunction machine. The same effect can be obtained by applying the present disclosure to a single-function machine such as a printer, a copy machine equipped with a scanner, or a facsimile machine equipped with a facsimile communication function. [Industrial Applicability]

[0135] The image forming apparatus according to the present disclosure is useful as an apparatus capable of determining whether or not a false detection of the apparatus state is caused by electrostatic noise. [Explanation of symbols]

[0136] 1. Image forming apparatus 111...................................................Control unit 130………………………Operation panel 201a…………………………First stage pick-up roller 202a…………………………First stage feed roller 203a…………………………First stage separating roller 206……………………………Timing roller 213...................................................Pre-eject roller 221a…………………………First stage feed motor 224……………………………Timing motor 226...Fuser motor 241a…………………………First stage paper feed sensor 243……………………………Timing sensor 244...Pre-eject sensor 261a, 261b, 262...Antennas 263, 501, 1100...antenna 1120…………………………Antenna 301, 1001, 1011...Leaf springs 310……………………………Coil spring 411...........Electrostatic noise detection circuit 502, 1102, 1112...Analog receiving circuit 503, 1103, 1113...Digital processing unit 1122…………………………Noise amplifier circuit 1123…………………………A / D conversion circuit

Claims

1. Monitoring the state of the output signal of a sensor or control board that fluctuates due to electrostatic noise A monitoring means; An electrostatic noise detection means for detecting electrostatic noise; an erroneous detection determination means for determining whether or not the state monitoring means has erroneously detected a change in the output signal due to electrostatic noise, based on a detection result of the change in the output signal by the state monitoring means and a detection result of the electrostatic noise detection means; A plurality of electrostatic noise sources capable of generating electrostatic noise; An electrostatic noise source estimation means for estimating an electrostatic noise source that has generated the electrostatic noise, the electrostatic noise detection means includes a plurality of electrostatic noise detection units disposed in the vicinity of each of the plurality of electrostatic noise sources within the device in correspondence with the plurality of electrostatic noise sources, The multiple electrostatic noise detection units have different detection sensitivities and can each recognize the strength of electrostatic noise. The electrostatic noise source estimation means identifies the electrostatic noise source based on the detection sensitivity of the electrostatic noise detection unit that detected the electrostatic noise.

1. An image forming apparatus comprising:

2. A status monitoring means for monitoring the status of an output signal of a sensor or a control board that fluctuates due to electrostatic noise; An electrostatic noise detection means for detecting electrostatic noise; an erroneous detection determination means for determining whether or not the state monitoring means has erroneously detected a change in the output signal due to electrostatic noise, based on a detection result of the change in the output signal by the state monitoring means and a detection result of the electrostatic noise detection means; A plurality of electrostatic noise sources capable of generating electrostatic noise; The state monitoring means monitors the states of the plurality of types of output signals, moreover, an electrostatic noise source estimating means for estimating an electrostatic noise source that has generated the electrostatic noise, depending on which of the plurality of types of output signals the state monitoring means has determined to have erroneously detected a change in when the electrostatic noise detecting means detects electrostatic noise; and a storage means for storing the electrostatic noise sources in order of the likelihood of generating electrostatic noise and thus causing erroneous detection of a change in the output signal.

1. An image forming apparatus comprising:

3. A status monitoring means for monitoring the status of an output signal of a sensor or a control board that fluctuates due to electrostatic noise; An electrostatic noise detection means for detecting electrostatic noise; an erroneous detection determination means for determining whether or not the state monitoring means has erroneously detected a change in the output signal due to electrostatic noise, based on a detection result of the change in the output signal by the state monitoring means and a detection result of the electrostatic noise detection means; A plurality of electrostatic noise sources capable of generating electrostatic noise; The state monitoring means monitors the states of the plurality of types of output signals, moreover, an electrostatic noise source estimating means for estimating an electrostatic noise source that has generated the electrostatic noise, depending on which of the plurality of types of output signals the state monitoring means has determined to have erroneously detected a change in when the electrostatic noise detecting means detects electrostatic noise; a storage means for storing, for each combination of the output signal and an electrostatic noise generating source, whether or not there is a possibility that a change in the output signal may be erroneously detected due to the generation of electrostatic noise; The erroneous detection determination means determines that the change in the output signal has been normally detected when the state monitoring means detects a change in the output signal and, based on the stored contents of the storage means, the electrostatic noise source estimated by the electrostatic noise source estimation means is unlikely to cause the erroneous detection of the change in the output signal.

1. An image forming apparatus comprising:

4. The electrostatic noise detection means has a history recording means for recording the history of the timing at which the electrostatic noise was detected.

4. The image forming apparatus according to claim 1, wherein the image forming apparatus is a multi-color image forming apparatus.

5. The erroneous detection determination means performs the determination based on a result of a comparison between the timing at which the state monitoring means detects a change in the output signal and the timing at which the electrostatic noise detection means detects electrostatic noise.

5. The image forming apparatus according to claim 1, wherein the image forming apparatus is a laser printer.

6. The result of the determination by the erroneous detection determination means is displayed on the operation panel.

6. The image forming apparatus according to claim 1,

7. The result of the false positive determination means is notified to the data center.

6. The image forming apparatus according to claim 1,

8. The output signal monitored by the state monitoring means is notified via a wiring on which electrostatic noise may be superimposed.

8. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

9. The wiring includes at least one of a wiring for transmitting a detection signal of a sensor and a communication wiring.

9. The image forming apparatus according to claim 8,

10. The electrostatic noise source includes at least one of an electrical contact that may generate electrostatic noise due to poor contact and a motor that may generate electrostatic noise due to a foreign object.

10. The image forming apparatus according to claim 1,

11. The state monitoring means monitors the state of the output signal of the sensor, The sensors are provided in a plurality of locations and are disposed in the vicinity of each of the electrostatic noise detection units.

2. The image forming apparatus according to claim 1,

Images