JP5230405B2 - Surface potential measuring apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a surface potential measuring device that detects a surface potential of a measurement target, and an image forming apparatus equipped with the surface potential measuring device.

  FIG. 12 is a simplified block diagram of a surface potential measuring apparatus according to a conventional example.

  In FIG. 12, the surface potential measuring device includes a potential sensor 101 and a controller 103 that controls the potential sensor 101. The surface potential measuring device measures the surface potential of the measurement object 102.

  The potential sensor 101 includes a probe 110 and a control unit 120 that controls the probe 110 and communicates with the controller 103.

  FIG. 13 is a detailed block diagram of the surface potential measuring apparatus of FIG.

  The operation of the surface potential measuring device will be described with reference to FIG.

  In FIG. 13, when the remote signal input from the controller 103 is turned on, the operation of the potential sensor 101 and the control unit 120 is started.

  First, a drive signal is input to the potential sensor 101 by a drive circuit (not shown). Then, the tuning fork (tuning fork type vibrator) 111a starts to vibrate, and the tip thereof vibrates in the arrow direction 111b on the left and right respectively.

  On the other hand, as the tuning fork 111a vibrates, the capacitance between the electrode (measurement electrode) 112 and the measurement object 102 periodically changes C (t). As a result, the charge amount of the electrode 112 is changed, and the change in the charge amount is converted into a voltage by the detection resistor 113 in the detection circuit 115, thereby obtaining an AC voltage signal proportional to the potential difference between the measurement object 102 and the electrode 112. ing. Then, it is amplified by the amplifier 114 and output to the control unit 120.

  Each part of the potential sensor 101 operates with an output (point H in FIG. 13) of a high-voltage power supply 124 described later as a reference potential.

  The control unit 120 controls the output of the high-voltage power supply 124 so that the amplitude of the AC detection signal is zero based on the AC detection signal output from the detection circuit 115. Here, when the amplitude of the AC detection signal is zero, the tuning fork 111 (a pair of tuning forks 111a) vibrates and the capacitance between the electrode 112 and the measurement object 102 periodically changes. In this state, the charge amount of the electrode 112 does not change.

  This state means that the surface potential of the measurement target 102 and the potential of the electrode 112, that is, the surface potential of the measurement target 102 and the output of the high-voltage power supply 124 are the same potential. Thereby, the surface potential of the measuring object 102 can be obtained (zero method).

  The control unit 120 converts the output of the high-voltage power supply 124 at this time in the output circuit 125 according to the relationship shown in FIG.

  FIG. 14 is a diagram showing the relationship between the output signal, which is the output of the control unit 120 in FIG. 13, and the measured potential.

  In the case of FIG. 14, the measurement result and the detected value are such that the output of the output circuit 125 is 0 V when the measurement result at the control unit 120 is −50 V, and the output of the output circuit 125 is 3.3 V when it is +900 V. Is a linear relationship. Therefore, the controller 103 can obtain the surface potential information of the measurement object 102 by converting the signal input from the control unit 120 based on the relationship of FIG.

  Next, failure detection of the potential sensor 101 will be described using the waveform of FIG.

  FIG. 15 is a diagram showing an output signal when the potential sensor 101 in FIG. 13 is abnormal.

  In FIG. 15, (a) is a waveform of potential fluctuation applied to the measurement object 102. (B) is a signal waveform of the potential measurement result output from the output circuit 125 of the control unit 120.

  Here, failure determination of the potential sensor 101 is performed based on the response characteristic of the waveform (b) when the waveform (a) falls. That is, when the value of the waveform (b) after the lapse of the predetermined time t13 from the fall of the waveform (a) applied to the measurement object 102 is measured and the value is less than the predetermined voltage V13, it is normal and when it is V13 or more. Then, it is determined that the response characteristic has deteriorated due to the failure of the potential sensor 101.

The above technique is disclosed in Patent Document 1.
JP-A-63-94252

  However, in the conventional failure determination method of the potential sensor 101, even if the failure of the potential sensor 101 is determined, it is not possible to determine which of the probe 110 and the control unit 120 constituting the potential sensor 101 has failed.

  Therefore, when repairing the surface potential measurement device, the probe 110 and the control unit 120 need to be replaced together with the configuration of the potential sensor 101.

  Actually, it is very unlikely that the probe 110 and the control unit 120 will fail at the same time. In general, only one of them fails. There was a waste of money.

  SUMMARY OF THE INVENTION An object of the present invention is to determine whether a probe or a control unit constituting a potential sensor has failed, and to replace only a failed part, thereby reducing the cost and a surface potential measuring device and an image forming apparatus. Is to provide.

  In order to achieve the above object, the surface potential measuring apparatus according to claim 1 is a surface potential measuring means comprising a probe that outputs a signal corresponding to a surface potential of a measurement object and a control unit that controls the probe. And failure detection means for detecting which of the probe and the control unit failed based on the output signal of the probe when the surface potential measurement means fails.

  The image forming apparatus according to claim 5, an image carrier on which an electrostatic latent image is formed on a surface, a probe that outputs a signal corresponding to a surface potential of the image carrier, and a control unit that controls the probe; And a failure detection means for detecting which of the probe and the control unit failed based on the output signal of the probe when the surface potential measurement means fails. It is characterized by that.

  According to the surface potential measuring device of the present invention, it is possible to reduce costs by determining which one of the probe and the control unit constituting the potential sensor has failed and replacing only the failed part.

  Hereinafter, the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. Absent.

  FIG. 1 is a detailed block diagram of a surface potential measuring apparatus according to an embodiment of the present invention. The same parts as those in the conventional surface potential measuring apparatus shown in FIG.

  In FIG. 1, the surface potential measuring device includes a potential sensor 101, a controller 103 that controls the potential sensor 101, and a high-voltage power supply 104. The surface potential measuring device measures the surface potential of the measurement object 102.

  The potential sensor 101 includes a probe 110 and a control unit 120 that controls the probe 110 and communicates with the controller 103. The high voltage power source 104 applies a voltage to the measurement object 102.

  The probe 110 of the potential sensor 101 includes a tuning fork 111, an electrode 112, a detection resistor 113, an amplifier 114, and the like.

  The control unit 120 of the potential sensor 101 includes a drive circuit 121 of the tuning fork 111, an amplifier circuit 122 that amplifies a signal from the amplifier 114, and a control circuit 123 that controls the high-voltage power supply 124 based on the signal from the amplifier circuit 122.

  Further, the control unit 120 converts the output of the high-voltage power supply 124 into a predetermined specification and outputs the output circuit 125, and the open loop switching for switching the reference sensor potential to the ground and switching the operation of the potential sensor 101 to the open loop. Part 126 is provided. Furthermore, the control unit 120 includes a protective resistor 127 that protects the output of the high-voltage power supply 124 during an open loop operation.

  The controller 103 is connected to the control unit 120 and has a function of communicating an output signal Vs, a remote signal, and a mode switching signal (control mode: feedback loop mode and open loop mode). The controller 103 is connected to the probe 110 and has a function of monitoring the output of the amplifier 114 in the probe 110 and a function of controlling the output of the high-voltage power supply 104.

  FIG. 2 is a diagram showing a state in which an operation display unit is connected to the surface potential measuring apparatus of FIG.

  As shown in FIG. 2, the operation display unit 201 is connected to the potential sensor 101, the controller 103, and the high voltage power supply 104.

  The basic potential measurement method is the same as that of the conventional example shown in FIG.

  Here, in order to measure the potential of the measurement object 102 with higher accuracy using the potential sensor 101, it is important to adjust the offset and confirm the operation of the potential sensor before measuring the potential.

  The offset voltage is a difference between the true potential of the measurement object 102 and the output signal Vs of the potential sensor 101. This is because of variations in assembly of the probe 110, variations in the constant of the control unit 120, variations in the fixation of the probe 110 (distance to the measurement object 102, etc.), changes in the usage environment (temperature, humidity, etc.) of the potential sensor 101, It is affected by changes over time and dirt.

  Therefore, an offset adjustment method is known in which an offset potential is actually measured before actual potential measurement and subsequent measurement data is corrected.

  When adjusting the offset, the measuring object 102 is fixed to the GND potential by a switch means or the like (not shown), the state is measured by the potential sensor 101, and the output signal Vs at that time is stored in the controller 103 as the offset voltage Voffset. Then, the result of subtracting Voffset from the subsequent measurement value (output signal Vs) is defined as measurement value = measurement target potential.

  The offset voltage as the potential sensor 101 is generally about several volts in absolute value. The offset voltage measured during the offset adjustment reaches several tens of volts in absolute value, or the measured value is stabilized. If not, the potential sensor 101 may be out of order.

  In addition to the offset voltage, what is important as the performance of the potential sensor 101 is the measurement accuracy (linearity characteristics). This is a characteristic of how accurately the potential can be measured after the offset adjustment. For example, when the potential of the measuring object 102 is set to 500 V after the offset adjustment, the potential sensor 101 measures how close to 500 V. It is a characteristic to output the result.

  Regarding this characteristic as well as the offset voltage, the constant variation of the control unit 120, the fixing of the probe 110 (distance to the measurement object 102, etc.), the change in the usage environment (temperature, humidity, etc.) of the potential sensor 101, the probe 110 It is affected by changes over time and dirt.

  In order to measure the potential of the measurement object 102 with higher accuracy, a method of confirming measurement accuracy after offset adjustment is known.

  The measurement accuracy is confirmed by setting the measurement object 102 to a predetermined voltage (for example, 500 V) with the high-voltage power supply 104, measuring the potential with the potential sensor 101, and allowing the measurement accuracy of the potential sensor 101 whose measurement result Vs is predetermined. Check if it is less than the value. For example, when the allowable accuracy is 3%, it is normal if the measurement result is 485 V to 515 V, and when it is outside this, the potential sensor 101 may be broken.

  In addition to the above offset correction and measurement accuracy confirmation, it is possible to maintain a more reliable measurement system by periodically checking the performance of the potential sensor 101.

  Next, a method for periodically checking the performance of the potential sensor 101 will be described. Note that this check method is also a method of specifying the failure location of the potential sensor 101 when there is an abnormality in the result when the offset adjustment or the measurement accuracy is confirmed and the potential sensor 101 is considered to be defective.

  FIG. 3 is a flowchart showing a procedure of a failure check process of the potential sensor 101 executed by the surface potential measuring apparatus of FIG.

  This process is executed under the control of the controller in FIG. Each processing step is denoted by a symbol S.

  This potential sensor failure check process is performed, for example, every time when the surface potential measuring device is operating, when the environmental temperature in the surface potential measuring device fluctuates by a predetermined value, or whenever potential measurement is performed. It is executed before the measurement as a trigger. Furthermore, when the offset voltage exceeds a predetermined value by offset adjustment, when the measurement accuracy is lower than the predetermined value by checking the measurement accuracy, or when the user of the surface potential measurement device executes the check mode at any time, etc. Is executed as a trigger.

  When the failure check mode (check process) is started by the above trigger, first, the controller 103 sets the measurement object 102 to a predetermined potential Vh1 (eg, 500 V) by the high-voltage power supply 104, and the potential sensor 101 at that time is set. The output signal Vs is measured (S301).

  The controller 103 checks whether or not the measured Vs is in a predetermined range Vh2 (example 485V) ≦ Vs ≦ Vh3 (example 515V) (S302). If within the predetermined range, it is determined that the potential sensor 101 is normal (S309). Then, the check mode ends.

  On the other hand, if it is not within the predetermined range, the controller 103 determines that there is some abnormality in the potential sensor 101, and in order to identify the abnormal part, first, the controller 120 is changed from the feedback mode to the open loop mode. Switch. At the time of switching, a switching signal is output from the controller 103, and the open loop switching unit 126 fixes the reference potential of the probe 110 to the ground potential (S303).

  Then, a predetermined potential Vh1 (eg, 500 V) is applied to the measurement object 102, and the controller 103 checks the output of the amplifier 114 in the probe 110 in an open loop state (S304).

  First, the controller 103 confirms the frequency and confirms whether the frequency is within a predetermined range, fb1 (eg, 460 Hz) ≦ fa ≦ fb2 (eg, 540 Hz) (S305).

  The output signal frequency of the amplifier 114 is a sine wave signal having the vibration frequency of the tuning fork 111. If the tuning fork 111 vibrates normally, the tuning fork 111 vibrates at a resonance frequency determined by the shape of the tuning fork 111, and falls within a reference value of ± several tens of Hz even if variations in parts are taken into consideration.

  FIG. 4 is a diagram showing an example of an output signal of the probe 110 in FIG. 1 (1).

  In FIG. 4, reference numeral 4-1 is an output signal at the minimum frequency (fb1), reference numeral 4-3 is an output signal at the maximum frequency (fb2), and reference numeral 4-2 is an output signal of the measurement result fa. is there.

  Whether fa is fb1 or less or fb2 or more is determined to be abnormal. Therefore, if not in the predetermined range in S305, it is determined that the probe 110 of the potential sensor 101 is abnormal (S310).

  Then, as shown in FIG. 2, when the surface potential measuring apparatus has the operation display unit 201, the controller 103 indicates that the probe 110 of the potential sensor 101 is abnormal, which is a check result of the check mode. The information is displayed on the operation display unit 201 (S308). Then, the check mode ends.

  If the amplitude is within the predetermined range in S305, the controller 103 next checks whether or not the amplitude Va is within the predetermined amplitude range, Vb1 (example 10 mV) ≦ Va ≦ Vb2 (example 30 mV) (S306).

  That is, in the present embodiment, both the frequency and amplitude of the output of the probe 110 are determined, but either one may be determined.

  The amplitude of the output signal of the amplifier 114 is related to the magnitude of the vibration of the tuning fork 111, the detection resistor 113, the amplification factor of the amplifier 114, and the magnitude of the voltage applied to the measurement object 102. The predetermined voltage Vh1 is applied. Under the circumstances, most of the fluctuation factors are within the probe 110. The detection signal amplitude Va at the predetermined voltage Vh1 greatly affects the response time as the potential sensor 101, and the decrease in the amplitude Va means that the response time is delayed and sufficient performance cannot be obtained. ing.

  FIG. 5 is a diagram illustrating an example of an output signal of the probe 110 in FIG. 1 (2).

  In FIG. 5, reference numeral 5-1 is an output signal at the minimum amplitude (Vb1) necessary for complying with the response time regulation as the potential sensor 101, and reference numeral 5-3 is the maximum amplitude (Vb2) assumed in normal operation. ), And reference numeral 5-2 is an output signal of the measurement result Va.

  Va is determined to be abnormal regardless of whether it is Vb1 or less or Vb2 or more. Therefore, if it is not within the predetermined range in S306, it is determined that the probe 110 is abnormal (S310). Similarly to the above, the controller 103 displays “the probe 110 of the potential sensor 101 is abnormal” on the operation display unit 201 (S308). Then, the check mode ends.

  If it is within the predetermined range in S306, the controller 103 determines that there is an abnormality on the control unit 120 side (S307). Then, the controller 103 displays “the control unit 120 is abnormal” on the operation display unit 201 (S308). Then, the check mode ends.

  With this check mode, it can be confirmed whether or not there is an abnormality in the potential sensor 101. If there is an abnormality, the failure location is specified, and if the operation display unit 201 is provided, the failure location is identified. Can be displayed.

  As described above, by periodically executing the check mode, it is possible to confirm that the performance of the potential sensor 101 is always satisfied, so that the measurement quality of the surface potential measurement of the measurement object 102 is maintained. The

  At the same time, if there is an abnormality in the result of offset adjustment or confirmation of measurement accuracy and the potential sensor 101 is considered to be faulty, it becomes possible to identify the faulty part and replace only the faulty part. Can restore the function.

  6 is a block diagram showing a configuration of an image forming system of the image forming apparatus according to the embodiment of the present invention, and FIG. 7 is a block diagram showing a connection state of the image forming apparatus of FIG.

  In FIG. 6, a charging device 604, an exposure device 605, a potential sensor 101, a developing device 606, and a rotation detection sensor 608 are arranged around a photoconductor 602 as an image carrier. The photoconductor 602 is driven by a photoconductor drive motor 607.

  As shown in FIG. 7, the controller 603 includes a charging device 604, an exposure device 605, a photoconductor drive motor 607, a potential sensor 101, a rotation detection sensor 608, an operation display unit 609, and a network connection unit 610. Communicate with various devices, sensors, etc. And it is the structure which can control them.

  The configuration of the potential sensor 101 is the same as the configuration described in FIG. 1, and the relationship between the controller 603 and the potential sensor 101 is also the same as the configuration of the controller 103 and the potential sensor 101 described in FIG.

  In the image forming apparatus of FIG. 6, during image formation, the photosensitive member 602 starts rotating by the photosensitive member driving motor 607, and after the photosensitive member 602 is uniformly charged by the charging device 604, the image forming device responds to the image signal. Exposure is performed by the exposure device 605. As a result, an electrostatic latent image is formed on the photoreceptor 602. The potential sensor 101 is provided between exposure and development in order to measure the potential of the electrostatic latent image.

  The electrostatic latent image is developed into a toner image by the developing device 606, the toner image on the photoreceptor 602 is transferred to a recording material (paper) (not shown), and the toner image on the paper is fixed by a fixing unit (not shown). To get the output.

  The image forming apparatus shown in FIG. 6 has an image forming parameter adjustment mode in order to stabilize the image quality. In order to always maintain stable image quality even when there are changes in environmental conditions (temperature, humidity), changes in film thickness of the photoconductor 602, and deterioration over time, an adjustment mode is regularly implemented. .

  For example, the output voltage of the charging device 604 for charging the photosensitive member 602 and the high voltage applied to the developing device 606 are determined as follows. That is, a predetermined potential pattern is formed on the photoconductor 602 by the charging device 604, the surface potential of the photoconductor 602 is measured by the potential sensor 101, and the charging device is set to a desired (predetermined) charging potential. The output value of 604 is corrected. Further, the high voltage applied to the developing device 606 is determined based on the correction result.

  This adjustment mode is executed in various cases such as when the power is turned on the first day in the morning, every predetermined number of image formations, every elapse of a predetermined time, or when the temperature in the apparatus changes by a predetermined value or more. Is done.

  Note that when the surface potential of the photoconductor 602 is measured by the potential sensor 101 as in the above adjustment mode, it is possible to predict in advance how much the measurement result will be. In this adjustment mode, the measurement result has a certain value. There is a reference value indicating that some abnormality has occurred.

  For example, when an output that charges the photosensitive member 602 to −500 V is applied by the charging device 604, and the device operates normally, the measurement result of the potential sensor 101 should be within the range of −350 V to −650 V. It is. If it deviates from this value, some abnormality has occurred.

  For this reason, in offset adjustment, charged portion potential measurement, and exposure portion potential measurement performed using the potential sensor 101, an error is processed as a potential measurement error if it does not fall within a predetermined measurement range. It has become.

  The offset adjustment refers to adjusting the offset of the potential measurement system in a state where the photoconductor 602 is neutralized. The charged portion potential measurement refers to measuring a potential obtained by charging the photosensitive member 602 with the charging device 604. Further, the measurement of the potential of the exposed portion refers to the measurement of the potential after the charged photoconductor 602 is exposed by the exposure device 605.

  However, since there are a plurality of causes that the potential measurement result does not fall within the predetermined range, when this potential measurement error occurs, a failure location check mode for identifying the cause is executed.

  FIG. 8 is a flowchart showing a procedure of failure location check processing executed by the image forming apparatus of FIG.

  This process is executed under the control of the controller 603 as failure detection means in FIG. Each processing step is denoted by a symbol S.

  As described above, when the result of the potential measurement by the potential sensor 101 in the various adjustment modes does not fall within the predetermined measurement range, the failure location check mode (check process) is executed as a potential measurement error.

  First, the controller 603 checks whether the output of the charging device 604 is normal (S801). The controller 603 outputs a control signal so as to output a predetermined voltage Vh2 to the charging device 604. Then, the charging device 604 outputs a signal value corresponding to the output high voltage to the controller 603, whereby the controller 603 confirms whether a desired output is being made.

  If the desired output has not been made, the controller 603 determines that the charging device 604 is abnormal (S811).

  Then, “the charging device 604 is abnormal”, which is the check result of the check mode, is displayed on the operation display unit 609. Further, when the image forming apparatus is connected to the network, the controller 603 can notify the PC or the like of the abnormal location via the network (S810). Then, the check mode ends.

  If the desired output is made to the charging device 604, the controller 603 confirms whether the output of the exposure device 605 is normal (S802). The exposure device 605 scans the photoconductor 602 in a direction perpendicular to the rotation direction. Therefore, an optical sensor is provided in the middle of the optical path and at a position where the image formation on the photoconductor 602 is not affected, and it is confirmed whether or not the light is normally emitted.

  If the exposure apparatus 605 is not emitting light, the controller 603 determines that the exposure apparatus 605 is abnormal (S812).

  Similarly to the above, the controller 603 displays “the exposure apparatus 605 is abnormal” on the operation display unit 609. Further, when the image forming apparatus is connected to the network, the controller 603 can notify the PC or the like of the abnormal location via the network (S810). Then, the check mode ends.

  If the exposure device 605 is emitting light normally, then the controller 603 checks whether the rotation operation of the photoconductor 602 is normal (S803). The photoconductor 602 is rotated by a photoconductor drive motor 607.

  However, the photoconductor 602 does not rotate normally even when the photoconductor drive motor 607 itself fails or when there is an abnormality in the shaft, belt, gear, etc. that transmits the driving force. In this case, the charged portion of the photoconductor 602 does not come to the opposite portion of the potential sensor 101, and the measured value of the potential measurement deviates from a predetermined value. Therefore, the photosensitive member 602 is rotated, and the rotation of the photosensitive member 602 is actually detected by the rotation detection sensor 608 for confirmation.

  Various configurations are conceivable for the rotation detection sensor 608. A pattern formed on the surface of the photoconductor 602 may be detected by a photosensor, or a rotation signal may be formed by a protrusion formed on the end of the photoconductor 602 passing between the photosensors.

  If the photoconductor 602 does not rotate normally, the controller 603 determines that there is an abnormality in the drive system of the photoconductor 602 (S813).

  Similarly to the above, the controller 603 displays “the drive system of the photoconductor 602 is abnormal” on the operation display unit 609. Further, when the image forming apparatus is connected to the network, the controller 603 can notify the PC or the like of the abnormal location via the network (S810). Then, the check mode ends.

  If the rotating operation of the photoconductor 602 is normally performed, the controller 603 confirms whether the potential sensor 101 is operating normally.

  First, the controller 603 switches the control unit 120 to the open loop mode. In the same way as described with reference to FIG. 3, a switching signal is output from the controller 603 to fix the reference potential of the probe 110 to the ground potential (S804).

  Next, the controller 603 applies a predetermined potential Vh1 (eg, 500V) to the photoconductor 602 (sets it to the predetermined potential Vh1) (S805), and checks the output of the amplifier 114 in the probe 110 in an open loop state. (S806).

  First, the controller 603 confirms the frequency, and confirms whether the frequency is within a predetermined range, fb1 (eg, 460 Hz) ≦ fa ≦ fb2 (eg, 540 Hz) (S807).

  The output signal frequency of the amplifier 114 is a sine wave signal having the vibration frequency of the tuning fork 111. If the tuning fork 111 vibrates normally, the tuning fork 111 vibrates at a resonance frequency determined by the shape of the tuning fork 111, and falls within a reference value of ± several tens of Hz even if variations in parts are taken into consideration. Therefore, if not within the predetermined range in S807, the controller 603 determines that the probe 110 of the potential sensor 101 is abnormal (S814).

  Similarly to the above, the controller 603 displays “the probe 110 of the potential sensor 101 is abnormal” on the operation display unit 609. Further, when the image forming apparatus is connected to the network, the controller 603 can notify the PC or the like of the abnormal location via the network (S810). Then, the check mode ends.

  If it is within the predetermined range in S807, the controller 603 next checks whether the amplitude Va is a predetermined amplitude range, Vb1 (example 10 mV) ≦ Va ≦ Vb2 (example 30 mV) (S808).

  The amplitude of the output signal of the amplifier 114 is related to the magnitude of the vibration of the tuning fork 111, the detection resistor 113, the amplification factor of the amplifier 114, and the magnitude of the voltage applied to the measurement object 102. The predetermined voltage Vh1 is applied. Under the circumstances, most of the fluctuation factors are within the probe 110. The detection signal amplitude Va at the predetermined voltage Vh1 greatly affects the response time as the potential sensor 101, and the decrease in the amplitude Va means that the response time is delayed and sufficient performance cannot be obtained. ing.

  Therefore, if not within the predetermined range in S808, the controller 603 determines that the probe 110 of the potential sensor 101 is abnormal (S814).

  Similarly to the above, the controller 603 displays “the probe 110 of the potential sensor 101 is abnormal” on the operation display unit 609. Further, when the image forming apparatus is connected to the network, the controller 603 can notify the PC or the like of the abnormal location via the network (S810). Then, the check mode ends.

  If it is within the predetermined range in S808, the controller 603 determines that there is an abnormality on the control unit 120 side (S809).

  Then, the controller 603 displays “the control unit 120 is abnormal” on the operation display unit 609. Further, when the image forming apparatus is connected to the network, the controller 603 can notify the PC or the like of the abnormal location via the network (S810). Then, the failure location check mode ends.

  In this fault location check mode, when the offset adjustment, the charged portion potential measurement, and the exposed portion potential measurement performed using the potential sensor 101 are not within the predetermined measurement range, the potential measurement result is within a predetermined range. It is possible to identify a cause that does not fit in

  As a result, it is possible to restore the function of the device by appropriately dealing only with the failure location.

  9 is a diagram showing an example of error display contents of the operation display unit 609 in FIG. 6, FIG. 10 is a correspondence table between error display contents and error codes of the operation display unit 609 in FIG. 9, and FIG. 11 is a diagram of FIG. 1 is a network configuration diagram of an image forming apparatus.

  The content of the error code “error 003” in FIG. 10 is “photoconductor drive abnormality”, and this content is displayed on the operation display unit 609 in FIG.

  Further, when the image forming apparatus A 1101 is connected to a network as shown in FIG. 11, the specified abnormal location can be notified to the management PC 1102 or the like via the network.

  For example, if the management PC 1102 is a departmental PC that performs maintenance of the image forming apparatus A1101, the failure of the apparatus is notified by notifying the specified failure location and placing an order for replacement parts based on the notification. Can be dealt with more quickly.

1 is a detailed block diagram of a surface potential measuring device according to an embodiment of the present invention. It is a figure which shows the state by which the operation display part was connected to the surface potential measuring apparatus of FIG. It is a flowchart which shows the procedure of the failure check process of the electric potential sensor 101 performed by the surface electric potential measuring apparatus of FIG. It is a figure which shows the example of the output signal of the probe 110 in FIG. 1 (1). It is a figure which shows the example of the output signal of the probe 110 in FIG. 1 (2). 1 is a block diagram illustrating a configuration of an image forming system of an image forming apparatus according to an embodiment of the present invention. FIG. 7 is a block diagram illustrating a connection state of the image forming apparatus in FIG. 6. FIG. 7 is a flowchart illustrating a procedure of a fault location check process executed by the image forming apparatus in FIG. 6. FIG. It is a figure which shows an example of the error display content of the operation display part 609 in FIG. 10 is a correspondence chart between error display contents and error codes in the operation display unit 609 in FIG. 9. FIG. 7 is a network configuration diagram of the image forming apparatus in FIG. 6. It is a simplified block diagram of a surface potential measuring apparatus according to a conventional example. FIG. 13 is a detailed block diagram of the surface potential measuring device of FIG. 12. It is a figure which shows the relationship between the output signal which is an output of the control part 120 in FIG. 13, and measured potential. It is a figure which shows the output signal at the time of abnormality of the electric potential sensor 101 in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Potential sensor 102 Measurement object 103 Controller 104 High voltage power supply 110 Probe 120 Control part 201 Operation display part 602 Photoconductor 603 Controller 604 Charging device 605 Exposure device 606 Developer

Claims (9)

A surface potential measuring means comprising a probe that outputs a signal corresponding to the surface potential of the measurement object, and a control unit that controls the probe;
When the surface potential measuring means fails, based on the output signal of the probe, failure detecting means for detecting which of the probe and the control unit has failed,
A surface potential measuring device comprising: A high-voltage power supply for applying a voltage to the measurement object;
When the surface potential measurement unit measures the surface potential of the measurement target to which a predetermined voltage is applied by the high-voltage power source, the measurement result does not fall within a predetermined range. 2. The surface potential measuring apparatus according to claim 1, wherein the surface potential measuring means is determined to be a failure.   3. The failure detection unit detects which of the probe and the control unit has failed based on either or both of an amplitude and a frequency of a signal output from the probe. The surface potential measuring device described.   The surface potential measuring apparatus according to claim 1, further comprising a display unit that displays a failure location detected by the failure detection unit. An image carrier on which an electrostatic latent image is formed on the surface;
A surface potential measuring means comprising a probe that outputs a signal corresponding to the surface potential of the image carrier, and a control unit that controls the probe;
When the surface potential measuring means fails, based on the output signal of the probe, failure detecting means for detecting which of the probe and the control unit has failed,
An image forming apparatus comprising: Having charging means for charging the image carrier,
The failure detection means, when measuring the surface potential of the image carrier charged to a predetermined potential by the charging means with the surface potential measurement means, if the measurement result is not within a predetermined range, 6. The image forming apparatus according to claim 5, wherein it is determined that the surface potential measuring unit is faulty, and based on an output signal of the probe, it is detected which of the probe and the control unit is faulty.   The failure detection means detects which of the probe and the control unit has failed based on either or both of an amplitude and a frequency of a signal output from the probe. The image forming apparatus described.   The surface potential measuring device according to claim 5, further comprising a display unit that displays a failure location detected by the failure detection unit.   9. The image forming apparatus according to claim 5, further comprising network connection means for notifying a failure location detected by the failure detection means via a network.

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