JP2006162676A - Process cartridge, image forming apparatus and control method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of accurately detecting the surface potential of a photoreceptor and reducing the number of components in the whole image forming apparatus. <P>SOLUTION: The image forming apparatus is mounted with detachable process cartridges (39), and each process cartridge (39) constituted of a photoreceptor (30) for forming a latent image from a laser output, a charging roller, a developing part (31) for sticking toner to a latent image part formed on the surface of the photoreceptor (30), a drum cleaning part (34) for cleaning toner left on the photoreceptor (30), and a substrate (32) constituted of integrating a surface potential detection circuit part for detecting the surface potential of the photoreceptor (30) and a high voltage generation part for boosting a charging bias AC+DC and a developing bias DC. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, and a multifunction machine, and more particularly to a process cartridge that can be attached to and detached from the main body of an image forming apparatus, an image forming apparatus equipped with the process cartridge, and a control method in the image forming apparatus. Is.

  An electrophotographic image forming apparatus charges the surface of a photoreceptor with a charging charger or other charging means, projects image light onto the surface of the charged photoreceptor, forms an electrostatic latent image, and The formed electrostatic latent image is visualized with a toner.

  As described above, charging on the photoconductor is the starting point of the image forming process, and if the charge potential on the surface of the photoconductor fluctuates, a good image cannot be obtained. For this reason, the surface potential detecting means is provided, and the charging means is controlled so that the detection potential of the surface potential detecting means becomes a set value, and / or the exposure intensity or the developing bias is controlled in accordance with the surface potential. It has been performed conventionally.

  Conventionally, when detecting the surface potential of the photosensitive member with an inexpensive surface potential detection circuit (hereinafter referred to as a potential sensor), the grounding of the photosensitive member is set to the float state in order to eliminate an output error due to the distance dependency of the potential sensor. The DC developing bias applied to the developing sleeve is adjusted to several predetermined potentials, applied to the photosensitive member, a linear approximation expression is obtained from the potential sensor output at that time, and the potential sensor is calibrated using the constants. It was. However, when a DC bias power supply (development bias power supply) applied to a conventional developing sleeve is used, the output voltage level of the DC bias power supply is adjusted by adjusting the PWM duty of a PWM signal of 1 kHz to 2 kHz. It will be. However, in the case of the above configuration, the relationship between the PWM duty of the PWM signal and the DC bias power supply output voltage level is not necessarily linear. In addition, since the output voltage range of the developing bias power supply is narrow, it is not possible to apply several levels of voltage for obtaining a linear approximation equation over a wide area to the photoreceptor, and the accuracy of the obtained linear approximation equation is reduced. It will be. Further, due to variations in individual DC bias power supplies, a similar output level cannot be obtained even if the PWM duty of the PWM signal is the same. There is also a PWM control system using a microcomputer. However, feedback signals for output voltage detection and output current detection must be given to the microcomputer for each output (in the case of an AC + DC power supply). In the case of color copiers (printers) with a large number of DC and AC bias power supplies, there is a problem in performance or cost, such as complicated control and the provision of a microcomputer dedicated to bias power supplies. There is.

For this reason, as a technical document filed prior to the present invention, the photoreceptor (9), the charging means (12) for charging the photoreceptor, and the surface potential detection for detecting the potential of the charged surface of the photoreceptor (9). Means (13), exposure means (1) for applying an image exposure to the charged surface of the photosensitive member (9) to form an electrostatic latent image, and developing means for developing the electrostatic latent image on the photosensitive member (9) (14-17), a first DC power supply circuit (74) for applying a developing bias voltage to the developing means (14-17), a transfer medium (19) to which a visible image on the photoreceptor (9) is transferred, A second DC power supply circuit (75) for applying a visible image transfer bias voltage between the transfer medium (19) and the photosensitive member (9), and a transfer for transferring the visible image of the transfer medium (19) to a transfer sheet. Means for calibrating the surface potential detecting means (13) in the image forming apparatus comprising the means (23) 1 is provided with switching means (76-2, 77-2, 78-2) for switching and supplying the voltage generated by the 1 DC power supply circuit (74) and the second DC power supply circuit (75) to the photoreceptor (9). 9) improves the calibration accuracy of the potential sensor for detecting the surface potential. The surface potential detection means (13) includes a potential probe and a potential detection circuit board. In this configuration, the surface potential of the photoconductor is detected by the potential probe, and the detected potential is detected. Is reduced to a voltage level controllable by the potential detection circuit board, and processing such as storage and calculation is performed by the control unit, and process control when forming an image is performed (see, for example, Patent Document 1).
JP-A-8-305096

  However, in the AC + DC charging method as described in Patent Document 1, the charging bias has an AC component, and the harness from the surface potential detection probe of the photoconductor to the surface potential detection circuit board of the photoconductor near the photoconductor. Since the wiring and the harness become longer, when the AC frequency component of the charging bias applied to the photosensitive member is an integral multiple of the tuning sensor fork driving frequency of the potential sensor, a ripple is added to the surface potential detection voltage of the photosensitive member, and the photosensitive member The surface potential may not be detected accurately.

  A photosensitive member that forms a latent image from the laser output; a charging method using the photosensitive member and a charging roller; a developing unit that attaches toner to the latent image portion of the photosensitive member; and a drum cleaning unit that cleans residual toner on the photosensitive member; Since the surface potential detection circuit board of the photoconductor and the high voltage generation unit that boosts the charging bias AC + DC and the developing bias DC are used exclusively outside the process cartridge apparatus including The number of parts in the entire forming apparatus increases, the layout becomes complicated, and the high-voltage leakage current increases.

  In addition, since the surface potential of the photoconductor is detected only during a predetermined image forming process control time in the image forming apparatus, it is necessary to constantly supply power to the surface potential detection circuit board of the photoconductor. Increase.

  Also, a color image forming apparatus that performs tandem image formation of four colors of black (K), magenta (M), cyan (C), and yellow (Y) is generally a predetermined process control in the image forming apparatus. If any error is detected in the surface potential detector of the photoconductor even at one color per hour, the entire system of the image forming apparatus is shut off. For this reason, even when an error other than black is detected, the black mode cannot be used.

  In addition, the tandem color image forming apparatus requires four colors for the charging bias AC + DC and the developing bias DC high voltage generation unit and the surface potential detection unit of the photoconductor. This increases the load on the controller.

  The present invention has been made in view of the above circumstances, and a process cartridge capable of accurately detecting the surface potential of the image carrier and reducing the number of parts as the entire image forming apparatus, and the process cartridge are mounted. An object of the present invention is to provide an image forming apparatus and a control method in the image forming apparatus.

  In order to achieve this object, the present invention has the following features.

  The process cartridge according to the present invention includes an image carrier, a charging unit that forms a charged region on the image carrier, a developing unit that forms a toner image on the image carrier, and a cleaning that removes the toner image on the image carrier. A process cartridge having a high voltage generating unit for boosting the charging bias AC + DC and the developing bias DC and a surface potential detecting unit for detecting the surface potential of the image carrier. It is characterized by having a substrate.

  An image forming apparatus according to the present invention is a tandem type image forming apparatus equipped with the process cartridge described above, wherein the process cartridge is detachable from the image forming apparatus, and the process cartridge forms an image. It is provided for each of a plurality of image forming means.

  The image forming apparatus according to the present invention further includes a control unit that controls a high voltage generation unit that boosts the charging bias AC + DC and the development bias DC, and a surface potential detection unit that detects the surface potential of the image carrier. The control board is arranged in the vicinity of the process cartridge.

  In the image forming apparatus according to the present invention, the control unit controls the power supply voltage of the surface potential detection unit to be supplied only at the time of image formation control performed at a predetermined timing.

  In the image forming apparatus according to the present invention, when the control unit determines that a surface potential detection error is detected in an image carrier that forms a color image other than the image carrier that forms a black image, Control is performed so as to enable printing only with an image.

  Further, the control method in the image forming apparatus according to the present invention includes an image carrier, a charging unit that forms a charged region on the image carrier, a developing unit that forms a toner image on the image carrier, and an image carrier. A control method in an image forming apparatus configured to be detachable from a process cartridge having a cleaning unit that removes a toner image, wherein the process cartridge includes a high voltage generation unit that boosts a charging bias AC + DC and a developing bias DC, An image forming apparatus includes a substrate integrated with a surface potential detection unit that detects a surface potential of an image carrier, and includes a high voltage generation unit that boosts a charging bias AC + DC and a development bias DC, and an image carrier. A control substrate having a surface potential detection unit for detecting the surface potential of the body and a control unit for controlling the surface potential is disposed in the vicinity of the process cartridge. The power supply voltage of the potential detecting unit, and is characterized in that the control so that only supplied at the time of image formation control performed at a predetermined timing.

  In the control method according to the present invention, when the control unit determines that a surface potential detection error is detected in an image carrier that forms a color image other than the image carrier that forms a black image, It is characterized in that control is performed so that printing can be performed only with this.

  According to the present invention, the process cartridge has a substrate in which a high voltage generating unit that boosts the charging bias AC + DC and the developing bias DC and a surface potential detecting unit that detects the surface potential of the image carrier are integrated. As a result, the surface potential of the image carrier can be accurately detected, and the number of parts of the entire image forming apparatus can be reduced.

  First, the image forming apparatus according to the present embodiment will be described with reference to FIG.

  The image forming apparatus according to the present embodiment includes a process cartridge that is detachable from the image forming apparatus. The process cartridge includes a photoconductor (3) that forms a latent image from a laser output, a charging roller (19), A developing unit (5) for attaching toner to a latent image portion on the surface of the photoconductor (3), a drum cleaning unit (14) for cleaning residual toner on the photoconductor (3), and a surface potential detection of the photoconductor (3). The image forming apparatus includes a circuit portion (17) and a substrate (18) integrated with a charging bias AC + DC and a high-voltage generating portion (15, 16) for boosting the developing bias DC. A dedicated control unit for controlling the unit (17) and the high-voltage generation unit (15, 16) for boosting the charging bias AC + DC and the developing bias DC, and detecting the surface potential of the photoconductor (3) accurately. Forming apparatus reduces the overall number of parts, layout optimization, reduction of the high pressure leakage flow, reduction of power consumption, the load reduction of the control unit of the image forming apparatus, and possible to use efficiency UP user. Hereinafter, an image forming apparatus according to this embodiment will be described with reference to the accompanying drawings.

  First, an image forming apparatus according to the present embodiment will be described with reference to FIG. FIG. 1 shows the overall configuration of a tandem image forming apparatus as an example of the image forming apparatus of the present embodiment.

  As shown in FIG. 1, the image forming apparatus according to the present embodiment is a tandem type image forming apparatus that forms four-color images of Y (yellow), C (cyan), M (magenta), and K (black). is there.

  The image forming apparatus according to the present embodiment photoelectrically converts reflected light from an exposed document, and performs signal processing on the scanner unit (1) and projects laser light emitted by the laser onto the photosensitive member (3). And a photoconductor (3) that forms a latent image by PM and PWM modulation of the laser output of the writing unit (2).

  Further, a charging unit (4) for uniformly charging the surface of the photosensitive member (3), a developing unit (5) for attaching toner to the photosensitive member (3) on which the latent image is formed, and the photosensitive member (3). And a transfer portion (intermediate transfer belt) (6) for transferring the toner image adhered thereon onto the transfer paper.

  Further, a paper feed tray is provided in the main body (7) (single-sided machine) and a paper feed bank (8), and a manual paper feed tray (9) is provided in the main body (7).

  In addition, a belt fixing unit (11), a fixing roller (12), and a pressure roller (13) that apply temperature and pressure to the sheet sent from the transport unit (10) to fuse the toner onto the sheet. And having.

  Next, a process cartridge mounted on the image forming apparatus of the present embodiment will be described with reference to FIG.

  As shown in FIG. 2, the process cartridge according to this embodiment includes a photoconductor (3) that creates a latent image from laser output, a developing unit (5) that attaches toner to a latent image portion on the surface of the photoconductor (3), and And a drum cleaning section (14) for cleaning the toner remaining on the surface of the photoreceptor (3).

  The process cartridge according to the present embodiment includes a charging AC + DC bias high voltage generation unit (15) that boosts the charging bias AC + DC, a development DC bias high voltage generation unit (16) that boosts the development bias DC, and a photoconductor (3). A substrate (18) in which a photoconductor surface potential detection unit (17) for detecting the surface potential is integrated is mounted.

  The charging AC + DC bias high voltage generator (15) is connected to the charging roller (19) via a high voltage harness (22), and the developing DC bias high voltage generator (16) is connected to the developing roller (5) of the developing unit (5). 20) and the high-voltage harness (22), and the photoconductor surface potential detector (17) connects the photoconductor surface potential probe (21) in the vicinity of the photoconductor (3) and the high-voltage harness (22). Are connected via the shortest high-voltage harness (22).

  In the conventional image forming apparatus, as a method for detecting the surface potential of the photoconductor (3), the photoconductor surface potential probe (21) is installed in the vicinity of the photoconductor (3), and the photoconductor is exposed via the surface potential detection circuit board. The surface potential of the body (3) is detected.

  The surface potential detection circuit board includes a photosensitive member (3) that forms a latent image from a laser output, a developing unit (5) that attaches toner to a latent image portion on the surface of the photosensitive member (3), and a photosensitive member (3). The drum cleaning unit (14) for cleaning the toner remaining on the surface is laid out outside the process cartridge device, and therefore, the space between the photoreceptor surface potential probe (21) and the surface potential detection circuit board is between It consists of a high-voltage harness that is longer than necessary. On the other hand, the charging bias has an AC frequency component, and the surface potential detection circuit board has a tuning fork drive frequency. For this reason, if the photosensitive member surface potential probe (21) and the surface potential detection circuit board are configured with a high voltage harness that is longer than necessary, the AC frequency component of the charging bias is reduced in the surface potential detection circuit board. When used at an integral multiple of the tuning fork drive frequency, a low-frequency ripple rides through the high-voltage harness, making it impossible to accurately detect the surface potential of the photoreceptor (3). Further, a photosensitive member (3) for forming a latent image from a laser output, a developing unit (5) for attaching toner to a latent image portion on the surface of the photosensitive member (3), and a drum for cleaning residual toner on the photosensitive member (3). A high voltage generation unit “charging AC + DC bias high voltage generation unit (15), development DC bias high voltage generation unit” boosting the charging bias AC + DC and the development bias DC outside the process cartridge including the cleaning unit (14). (16) "is laid out, each high-voltage harness becomes longer than necessary, and the leakage current of each high-voltage output increases. In addition, since the charging AC + DC bias high voltage generation unit (15), the development DC bias high voltage generation unit (16), and the photoreceptor surface potential detection unit (17) are configured, the entire image forming apparatus is configured. The number of parts is very large.

  However, the process cartridge according to this embodiment includes a substrate (18) in which a charging AC + DC bias high voltage generation unit (15), a development DC bias high voltage generation unit (16), and a photoreceptor surface potential detection unit (17) are integrated. ) In the vicinity of the charging roller (19), the developing roller (19) of the developing unit (5), and the photoreceptor surface potential probe (21), the wires of each high-voltage harness (22) can be minimized. It becomes possible to reduce the leakage current of each high-voltage output and the ripple of the surface potential of the photoreceptor (3).

  For this reason, a charging roller (15) for the high-voltage output voltage on the charging AC + DC bias high voltage generator (15) that boosts the charging bias AC + DC and the developing DC bias high voltage generator (16) that boosts the developing bias DC. 19) In addition, each high voltage output voltage drop on the developing roller (19) of the developing section (5) is reduced. In addition, the surface potential of the photoreceptor (3) can be accurately detected.

  Further, since the charging AC + DC bias high voltage generation unit (15), the development DC bias high voltage generation unit (16), and the photoreceptor surface potential detection unit (17) can be configured by a single substrate (18), an image can be obtained. It is possible to reduce the number of parts of the entire forming apparatus.

  As described above, the process cartridge mounted on the image forming apparatus according to the present embodiment includes a high voltage generation unit that boosts the charging bias AC + DC and the development bias DC, a surface potential detection unit that detects the surface potential of the image carrier, By having the integrated substrate, it is possible to accurately detect the surface potential of the photoconductor, and to reduce the number of parts of the entire image forming apparatus. In addition, the high-voltage leakage current can be reduced.

  Next, the image forming unit of the image forming apparatus shown in FIG. 1 will be described with reference to FIG. FIG. 3 shows a color image forming apparatus that performs image formation in four colors of black (K), magenta (M), cyan (C), and yellow (Y) in tandem.

  As shown in FIG. 3, the image forming apparatus according to the present embodiment includes a photoconductor (30), a developing unit (31) that develops toner on the photoconductor (30), and an unremained image on the photoconductor (30). A photosensitive member cleaning unit (34) for cleaning the transfer toner, and a toner image formed on the photosensitive member (30) by the developing unit (31) is transferred onto the intermediate transfer belt (35) as a primary transfer roller. This is a tandem method in which a color image is formed by sequentially performing primary transfer according to (33). The transfer belt (35) has a secondary transfer roller (36) and a secondary transfer counter roller (37), and the toner image formed on the intermediate transfer belt (35) is printed on paper. This is a secondary transfer mechanism for transferring. Further, an intermediate transfer belt cleaning unit (38) for cleaning untransferred toner remaining on the intermediate transfer belt (35) is provided.

  In the primary transfer process, the toner image formed on the photosensitive member (30) is intermediately applied to the primary transfer roller (33) by applying a positive polarity bias that is opposite to the negative polarity toner image to the primary transfer roller (33). In this method, the toner is drawn from the inside of the transfer belt (35) and transferred onto the intermediate belt (35).

  The process method of the secondary transfer mechanism is an extrusion bias method using a secondary transfer roller (36), a secondary transfer counter roller (37), and an intermediate transfer belt (35). A system in which a negative polarity toner image transferred onto an intermediate transfer belt has the same polarity as the toner, and a negative polarity bias is applied to the secondary transfer roller to push the toner from the inside of the intermediate transfer belt and transfer the paper. It is.

  As shown in FIG. 3, the color image forming apparatus according to the present embodiment includes a charging AC + DC bias high voltage generation unit (15), a development DC bias high voltage generation unit (16), a photoreceptor surface potential detection unit (17), A single board (32) is laid out for each image forming unit of black (K), magenta (M), cyan (C), and yellow (Y).

  In the present embodiment, the process cartridge (39) includes a photoconductor (30), a developing unit (31), a photoconductor cleaning unit (34), a charging AC + DC bias high voltage generator (15), and a developing DC bias high voltage. This is a process cartridge in which a generation unit (16) and a substrate (32) in which a photoreceptor surface potential detection unit (17) is integrated into one sheet are integrated for each color.

  In the tandem type color image forming apparatus according to the present embodiment, by mounting the process cartridge described above, the process cartridge for each color can be used in common, and the assemblability of the process cartridge can be improved. At the same time, the cost can be reduced.

  Next, referring to FIG. 4, in order to control the high voltage generating unit that boosts the charging bias AC + DC and the developing bias DC and the photoconductor surface potential detecting unit that detects the surface potential of the photoconductor. The configuration of the control unit will be described. FIG. 4 shows a control unit for controlling the high voltage generation unit that boosts the charging bias AC + DC and the development bias DC and the photoconductor surface potential detection unit that detects the surface potential of the photoconductor. 1 is a diagram illustrating a configuration of an image forming apparatus in which a control board having a layout is arranged.

  The control board shown in FIG. 4 includes a charging AC + DC bias high voltage generation unit (15), a development DC bias high voltage generation unit (16), and a photoreceptor surface potential detection unit (17) laid out in each process cartridge (39). It has an interface between the substrate (32) gathered on the sheet and the control unit on the image forming apparatus side. A detailed view thereof is shown in FIG. FIG. 5 shows a control unit (51) on the image forming apparatus main body side, a charging AC + DC bias high voltage generation unit (15), a development DC bias high voltage generation unit (16), and a photoreceptor surface potential detection unit (17). A control unit for controlling the substrate (32) gathered into one sheet, a high voltage generating unit that boosts the charging bias AC + DC and the developing bias DC, and a photoconductor surface potential detecting unit that detects the surface potential of the photoconductor. (52).

  A control unit (51) on the image forming apparatus main body side, a high voltage generation unit that boosts the charging bias AC + DC and the development bias DC, and a photoconductor surface potential detection unit that detects the surface potential of the photoconductor are controlled. As shown in FIG. 5, the control unit (52) is a ROM that stores programs and data, a CPU that executes arithmetic functions in accordance with the programs and data stored in the ROM, and a work area for the CPU. A control unit configured to include at least a RAM to be used.

  Further, the substrate (32) in which the charging AC + DC bias high voltage generation unit (15), the development DC bias high voltage generation unit (16), and the photoreceptor surface potential detection unit (17) are integrated into one sheet is black (K ), Magenta (M), cyan (C), and yellow (Y).

  The photoreceptor surface potential detection unit (17) includes a DC-DC converter, an insulation transformer, a voltage dividing buffer, a high voltage generation circuit, a dropper control circuit, a synchronous detection circuit, an integration circuit, an AC amplification circuit, It is comprised.

  The charging AC + DC bias high voltage generator (15) includes a charging AC drive circuit, a charging DC drive circuit, a charging AC driving transformer, a charging DC driving transformer, a charging DC output voltage detection, a charging Pk-Pk detection, AC output current detection.

  The development DC high voltage generator (16) includes a development DC drive circuit, a development DC drive transformer, and a development DC output voltage detection.

  As shown in FIG. 5, the charging AC + DC bias high voltage generator (15) has an interface connected to the charging roller, and the development DC bias high voltage generator (16) has an interface connected to the developing roller. The body surface potential detector (17) is configured to have an interface connected to the photoreceptor surface potential probe.

  The surface potential of the photosensitive member is fed back to the control unit (52) as an analog voltage of 0 to 5 V via the photosensitive member surface potential probe and the photosensitive member surface potential detecting unit (17).

  FIG. 6 shows the relationship between the surface potential of the photoconductor and the voltage obtained by converting the surface potential of the photoconductor into an analog voltage of 0 to 5 V via the photoconductor surface potential detector (17). As shown in FIG. 6, the analog voltage is linear in proportion to the absolute amount of the surface potential of the photoreceptor.

  The charging AC + DC bias high voltage generation unit (15) and the development DC bias high voltage generation unit (16) directly drive the PWM signal from the control unit (52) to generate a high voltage output.

  The relationship between the DUTY of the PWM signal and the high voltage output is shown in FIG. As shown in FIG. 7, the high voltage output has a linearity proportional to the DUTY of the PWM signal.

  The charging AC, the charging DC, and the development DC receive PWM signals independently, respectively, and the output voltage for the charging DC, the Pk-Pk voltage and output current for the charging AC, and the output voltage for the development DC are converted to 0 to 5V. The analog voltage is fed back to the control unit (52).

  FIG. 8 shows the relationship between the output voltage and current and the feedback voltage 0 to 5V. As shown in FIG. 8, the feedback voltage 0 to 5 V is linear in proportion to the high-voltage output voltage and current.

  The output voltage of the charging DC, the Pk-Pk voltage of the charging AC, and the output voltage of the developing DC are a high voltage generating unit that boosts the charging bias AC + DC and the developing bias DC, and a photoconductor that detects the surface potential of the photoconductor. While detecting the analog voltage fed back by the control unit (52) for controlling the surface potential detection unit, the PWM DUTY is varied so as to be the target output voltage.

  By constructing the configuration as shown in FIG. 5, the control unit (52) controls the charging bias AC + DC, the developing bias DC, and the PWM required for the control of the surface potential detection of the photosensitive member in total 12 and the AD 20 in total. ) Can be controlled.

  On the other hand, the control unit (52) and the control unit (51) on the image forming apparatus main body side are configured to be serially connected via the UART.

  By constructing the configuration as shown in FIG. 5, the control unit (51) on the image forming apparatus main body side and the control unit (52) on the process cartridge side can be configured as an interface only for serial communication. Thus, it is possible to reduce the harness and drawer connector with the control unit (51) of the image forming apparatus main body, and the load on the control unit on the image forming apparatus main body side.

  Next, the configuration of the control unit (52) will be described with reference to FIG. In FIG. 9, the controller (52) is provided with an OFF / ON port at the time of process control performed at a predetermined timing, and the photoreceptor surface potential is detected based on the level of the signal from the provided OFF / ON port. The structure which supplies the power supply Vcc with respect to a part is shown. As shown in FIG. 9, a signal from the OFF / ON port at the time of process control is a Pr signal.

  The control unit (52) shown in FIG. 9 sets the Pr signal to the low level when the process control is ON, and sets the Pr signal to the high level when the process control is OFF. When the Pr signal is at the Low level, the power source Vcc is supplied to the photoconductor surface potential detection unit, and when the Pr signal is at the High level, the power source Vcc is not supplied. As a result, the power source Vcc is supplied to the photoconductor surface potential detection unit (17) only when the process control is ON.

  Conventionally, the surface potential detection timing of the photoconductor is only during process control performed at a predetermined timing of the image forming apparatus. However, the power supply Vcc is always supplied to the photosensitive member surface potential detection unit, which increases the power consumption of the entire image forming apparatus. With the configuration shown in FIG. 9, the power supply Vcc is supplied to the photosensitive member surface potential detection unit only during process control, and the power consumption of the entire image forming apparatus can be reduced.

  Next, with reference to FIG. 10, a description will be given of a processing operation that enables copier only in the black mode when an error is detected in the surface potential detection unit of a photoconductor other than black.

  First, the control unit (52) starts process control (step S1), and after T2S (seconds) from the start of process control, whether or not the surface potential V of the photoreceptor satisfies V1 ≦ V ≦ V2. Is determined (step S2). V1 and V2 are potentials for determining whether the surface potential of the photoreceptor is within the specification range, and can be arbitrarily set.

  When it is determined that the surface potential V of the photoconductor satisfies V1 ≦ V ≦ V2 (step S2 / Yes), the control unit (52) performs the determination in step S2 again. When it is determined that the surface potential V of the photoconductor does not satisfy V1 ≦ V ≦ V2 (No in step S2 /), the control unit (52) determines that the surface potential is detected, and the surface potential detection error is detected. It is determined whether the photoconductor determined to be a black (K) photoconductor (step S3).

  When the control unit (52) determines that the photoreceptor determined to be the surface potential detection error is black (K) (step S3 / Yes), the control of the image forming apparatus is stopped (step S4). If it is determined that the photoconductor determined as the surface potential detection error is not black (K) (No in step S3), the process control is terminated (step S5).

  As described above, a color image forming apparatus that performs image formation in four colors of black (K), magenta (M), cyan (C), and yellow (Y) in tandem is performed at the time of process control performed at a predetermined timing. The control unit (52) detects whether the surface potential of the photoconductor is within the specification range via the surface potential probe and the photoconductor surface potential detection unit.

  As a result of the above determination, if the controller (52) detects that the sensor is out of the specification range, the surface potential of any of the four color photoreceptors of black (K), magenta (M), cyan (C), and yellow (Y). Will be detected if it is out of specification range.

  If the color detected outside the specification range is black (K), the operation of the entire image forming apparatus is stopped. If the color is not black (K), the process control is terminated and only the black mode can be copied. Will be controlled. However, which color photoreceptor surface potential is out of the specification range is displayed on the operation unit mounted on the image forming apparatus.

  As a result, even when an error is detected other than black (K) in the surface potential detection of the photosensitive member, the user can perform copying in the black mode.

  The above-described embodiment is a preferred embodiment of the present invention, and the scope of the present invention is not limited to the above-described embodiment alone, and various modifications are made without departing from the gist of the present invention. Implementation is possible.

  The process cartridge and the image forming apparatus equipped with the process cartridge according to the present invention can be applied to an image forming apparatus such as a copying machine, a printer, a facsimile machine, and a multifunction machine.

1 is a diagram illustrating a configuration of an image forming apparatus according to an exemplary embodiment. It is a figure which shows the structure of the process cartridge in this embodiment. 2 is a diagram illustrating an image forming unit of the image forming apparatus according to the present exemplary embodiment. FIG. FIG. 4 is a second diagram illustrating an image forming unit of the image forming apparatus according to the present exemplary embodiment, a high voltage generating unit that boosts the charging bias AC + DC and the developing bias DC, and a photoconductor that detects the surface potential of the photoconductor. It is the figure which mounted the control board which has a control part for controlling a surface potential detection part. A control unit (51) on the image forming apparatus main body side, a charging AC + DC bias high voltage generation unit (15), a development DC bias high voltage generation unit (16), and a photoreceptor surface potential detection unit (17) are integrated into a single substrate ( 32), and a control unit (52) for controlling the high voltage generating unit that boosts the charging bias AC + DC and the developing bias DC and the photosensitive member surface potential detecting unit that detects the surface potential of the photosensitive member. It is a figure which shows a relationship. It is a figure which shows the relationship between the surface potential of a photoconductor, and the voltage which converted the surface potential of the photoconductor into the analog voltage of 0-5V via the photoconductor surface potential detection part (17). It is a figure which shows the relationship between DUTY of a PWM signal, and a high voltage | pressure output. It is a figure which shows the relationship between an output voltage and an electric current, and the feedback voltage 0-5V. It is a figure which shows the structure of the control part (52) for controlling the high voltage production | generation part which pressure | voltage-rises charging bias AC + DC and developing bias DC, and the photoreceptor surface potential detection part which detects the surface potential of a photoreceptor. . FIG. 10 is a flowchart showing a processing operation in which only a black mode can be copied when an error is detected in a surface potential detection unit of a photoconductor other than black.

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 Photoconductor 5 Developing part 14 Drum cleaning part 15 Charge AC + DC bias high voltage generation part 16 Development DC bias high voltage generation part 17 Photoconductor surface potential detection part 18 Charge AC + DC bias high voltage generation part, Development DC bias high voltage generation part, and photoreceptor surface potential Substrate integrated with detection unit 19 Charging roller 20 Development roller 21 Photoconductor surface potential probe 22 High voltage harness 30 Photoconductor 31 Development unit 32 Substrate 33 Primary transfer roller 34 Photoconductor cleaning unit 35 Intermediate transfer belt 36 Secondary transfer roller 37 Secondary transfer counter roller 38 Intermediate transfer belt cleaning unit 39 Process cartridge

Claims (7)

An image carrier, a charging unit that forms a charged region on the image carrier, a developing unit that forms a toner image on the image carrier, and a cleaning unit that removes the toner image on the image carrier. A process cartridge,
The process cartridge includes a substrate in which a high voltage generating unit that boosts the charging bias AC + DC and the developing bias DC and a surface potential detecting unit that detects the surface potential of the image carrier are integrated. Feature process cartridge. A tandem type image forming apparatus equipped with the process cartridge according to claim 1,
The image forming apparatus, wherein the process cartridge is detachable from the image forming apparatus, and the process cartridge is provided for each of a plurality of image forming units for forming an image.   A control board having a control unit for controlling a high voltage generating unit that boosts the charging bias AC + DC and the developing bias DC and a surface potential detecting unit that detects the surface potential of the image carrier is provided on the process cartridge. The image forming apparatus according to claim 2, wherein the image forming apparatus is arranged in the vicinity. The controller is
4. The image forming apparatus according to claim 3, wherein the power supply voltage of the surface potential detection unit is controlled to be supplied only at the time of image formation control performed at a predetermined timing.   When the control unit determines that a surface potential detection error has been detected in an image carrier that forms a color image other than the image carrier that forms a black image, the control unit enables printing using only the black image. 5. The image forming apparatus according to claim 3, wherein the image forming apparatus is controlled as follows. An image carrier, a charging unit that forms a charged region on the image carrier, a developing unit that forms a toner image on the image carrier, and a cleaning unit that removes the toner image on the image carrier. A control method in an image forming apparatus configured to be detachable from a process cartridge,
The process cartridge includes a substrate in which a high voltage generation unit that boosts the charging bias AC + DC and the development bias DC and a surface potential detection unit that detects the surface potential of the image carrier are integrated.
The image forming apparatus includes:
A control board having a control unit for controlling a high voltage generating unit that boosts the charging bias AC + DC and the developing bias DC and a surface potential detecting unit that detects the surface potential of the image carrier is provided on the process cartridge. In the vicinity,
The controller is
A control method comprising controlling the power supply voltage of the surface potential detection unit to be supplied only during image formation control performed at a predetermined timing.   When the control unit determines that a surface potential detection error has been detected in an image carrier that forms a color image other than the image carrier that forms a black image, the control unit enables printing using only the black image. The control method according to claim 6, wherein control is performed as follows.

Images