JP2006243542A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus improved in safety in terms of high-voltage load by detecting leak even in the case of small leak amount, thereby realizing the output stop and the output restriction of a high voltage output generating device. <P>SOLUTION: In the image forming apparatus having a scorotron electrifier 70 for electrifying a body to be electrified, the scorotron electrifier has a plurality of electrifying wires 73 and 74 for electrifying the body to be electrified. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus having a high-voltage load and a processing device using the high-voltage load as a load.

  FIG. 1 is a diagram illustrating an overall configuration of a general image forming apparatus. The image forming apparatus 1 takes in image data from the digital camera 2, the personal computer 3, the FAX 4, the scanner device 5, and the like, and performs image copying, printing, and the like based on the image data. The image forming unit plays an important role in executing such copying and printing of images.

  FIG. 2 is a configuration diagram illustrating an example of the image forming unit. The image forming unit in FIG. 2 includes a photoconductor 11, a charging device 12, an exposure device 13, a developing device 14, a transfer device 15, a static elimination needle 16, a fixing device 17, a cleaning device 18, and a static elimination device 19. A series of operations such as charging, exposure, development, transfer, and fixing are performed. Among these operations, in the charging device 12, the developing device 13, the transfer device 15, and the like, the photosensitive member 11 needs to be charged or charged, but this charging exposes the photosensitive member to a high voltage space. Is going on. As a result, since the photosensitive member is charged to a high voltage, the photosensitive member 11 has a high voltage load, and devices such as the charging device 12, the exposure device 13, and the transfer device 15 are processing devices that process the high voltage load. It can be said that there is. The image forming unit is provided with a device for processing such a high-voltage load.

  FIG. 3 is an example of a processing apparatus for processing a high-voltage load. The scorotron charger 201 includes a charging wire 202, a casing 203, a grid 204, a charge terminal 205, and a grid terminal 206. The transfer roller 211 includes a roller 212, a shaft 213, and a terminal 214. The transfer belt 221 includes an application roller 222, a belt 223, a belt conveyance roller 224, a terminal 225, and a belt driving roller 226. The static elimination needle 231 has a static elimination needle main body 232 and a terminal 233. The developing unit 241 includes a developing unit main body 242 and a terminal 243. A predetermined voltage is applied to the terminals of these processing apparatuses.

  FIG. 4 is a configuration diagram of a high-voltage output generation device that supplies a high voltage to the charging device, for example. 4A includes a step-up transformer T41, a transistor Q41, a diode D41, a capacitor C41, a capacitor C42, a resistor R41, a resistor R42, a resistor R43, a resistor R4, and a resistor R45, and a terminal 401. To the load Z41. The transistor Q41 is a switching transistor provided on the input side of the step-up transformer T41, and D41 is a rectifier circuit provided on the output side of the step-up transformer T41. The switching transistor Q41 turns on / off the power supply voltage V402 at the terminal 402 in accordance with the PWM pulse signal. As a result, a high voltage pulse is generated on the secondary side of the transistor Q41, and the high voltage pulse is rectified to supply a high voltage to the load. Further, the voltage supplied to the load Z41 can be controlled by controlling the PWM pulse width. The resistor R42 and the resistor R44 detect the voltage Vfbi corresponding to the load current and the voltage Vfbv corresponding to the load voltage, and control the pulse width of the PWM supplied to the switching transistor Q41 based on these detection results. And getting a stable output. Examples of the control of the switching transistor Q41 include constant voltage control using the comparator of FIG. 4B and constant current control using the microcomputer of FIG. 4C. An example of constant voltage control using the comparator of FIG. 4B includes a comparator CP41 and a transistor Q41. In the circuit operation of FIG. 4B, a pulse PWM is generated by a comparator having the voltage Vfbv and a triangular wave as inputs, and switching control of Q41 is performed by this pulse PMW. 4C includes a microcomputer M41, an A / D converter AD41, a timer TM41, and a transistor Q41. In the circuit operation of FIG. 4C, the voltage Vfbi is converted from an analog signal to a digital signal by the A / D converter AD41, PMW is generated according to the digital output, and switching control of Q41 is performed by the pulse PMW. Do. Note that the voltage Vfbv in FIG. 4B may be the voltage Vfbi, or the voltage Vfbi in FIG. 4C may be the voltage Vfbv.

  FIG. 5 is another configuration diagram of the high-pressure generator. A step-up transformer T51, a transistor Q51, a diode D51, a diode D52, a Zener diode D53, a capacitor C51, a capacitor C52, and a resistor R51 are formed by a voltage doubler circuit and a Zener diode D53 that is a constant voltage element.

By the way, in such a high voltage output generation device (see Patent Document 1), a countermeasure against leakage is usually taken in which leakage current is detected and voltage is controlled based on the detected information. This is because the high-voltage generator generates a high voltage, and thus a leak such as corona discharge may occur due to the high voltage. If this leak is excessive, there is a risk of ignition or the like. For example, the high voltage generation unit 40 of FIG. 4 takes measures against leakage by feeding back a Vfbi signal as leakage information.
Japanese Patent Laid-Open No. 03-002358

  FIG. 6 is a diagram showing the voltage, current, and impedance of the high-voltage load when a leak occurs during high-voltage output. Here, the leakage phenomenon is exemplified by arc discharge of the charging charger. The horizontal axis represents time, and the vertical axis represents the voltage 64, current 65, and impedance 66 of the high-voltage load. It shows how the voltage 64, current 65, and load 66 at the time of leakage change in three states with different amounts of leakage (leakage a61 <leakage b62 <leakage c63). As shown in the figure, as the amount of leakage decreases, the changes in the voltage 64, current 65, and impedance 66 of the high-voltage load become smaller, and there is little change in the state of the leakage c63.

  By the way, the high-voltage output generator is usually provided with a countermeasure against leakage that detects leakage current and controls voltage based on the detected information. However, even if a leak current is generated, the voltage, current, and impedance that change with the leak are not significantly changed as in the state of the leak c63 in FIG. There is a problem that it is difficult to detect leaks and the leak countermeasure circuit does not operate.

  Recently, paper using conductive pigment-based ink is often used, and a technology for ensuring safety against ignition caused by leakage has become a very important issue.

  The present invention has been made in view of the above points, and by detecting a leak even with a small amount of leak, it becomes possible to stop the output of the high-voltage output generation device or to limit the output, and safety in a high-voltage load. An object of the present invention is to provide an image forming apparatus with improved image quality.

  In order to achieve the above object, according to the present invention, in an image forming apparatus having a high-voltage load and a processing device having the high-voltage load as a load, a plurality of the processing devices are provided, and the plurality of processing devices simultaneously Can be configured to process in parallel.

  In order to achieve the above object, the processing apparatus can be configured to be a scorotron charger, a transfer roller, a transfer belt, a static elimination needle, or a developing unit.

  In order to achieve the above object, in an image forming apparatus having a scorotron charger for charging a member to be charged, the scorotron charger has a plurality of charging wires for charging the member to be charged. Can be configured.

  In order to achieve the above object, in an image forming apparatus having a scorotron charger for charging a member to be charged, the member to be charged is used by using a plurality of scorotron chargers having a single charging wire. It can be configured to be charged.

  In order to achieve the above object, the charging device includes a charging unit that charges the charging wire of the scorotron charger, and a charging control unit that controls a charging amount of the charging unit. When the discharge current in the wire exceeds a predetermined amount, the charging control unit can control the charging unit to limit or stop the output of the charging unit.

  In order to achieve the above object, a grid portion for regulating discharge in the charging wire, grid voltage supply means for supplying a voltage to the grid portion, and grid control means for controlling a discharge current amount in the charging wire; The grid portion is configured such that when the discharge current in the charging wire exceeds a predetermined amount, the grid control means controls the grid voltage supply means to limit or stop the discharge current. can do.

  According to the present invention, it is possible to stop the output of the high-voltage output generation device or limit the output by detecting the leak even with a small leak amount, and to improve the safety in the high-voltage load. Can be provided.

  Next, the best mode for carrying out the present invention will be described based on the following embodiments with reference to the drawings. The basic principle is that by increasing the impedance of the high-voltage load, the amount of impedance change associated with the leakage current is greater than when the impedance is small, and the amount of change in voltage and current is also corresponding to this large amount of impedance change. Increasing the size facilitates detection of leakage current.

  By doing so, it is possible to detect the leakage current even in a state where the leakage amount is small, which has been difficult in the prior art, and the leakage current countermeasure circuit operates.

  FIG. 7 is a block diagram of the first embodiment. The scorotron band 70 includes a charge terminal 71, a charge terminal 72, a wire 73, a wire 74, a grid terminal 75, and a casing 76. The wires 73 and 74 charge the photoconductor 11. The casing 76 is an object surrounding a wire. The grid controls corona discharge to the surface of the photoreceptor 11 by the wires 73 and 74. The charger terminal 71 and the charge terminal 72 are terminals for applying a voltage to the wire 73 and the wire 74. The grid terminal 75 applies a voltage to the grid. The scorotron charger 70 of this embodiment has a configuration in which two wires 73 and 74 are provided inside one casing 76. The wire 73 and the wire 74 are connected to the charger terminal 71 and the charger terminal 72, respectively.

  FIG. 8 is an example of a circuit of the high voltage generator 80 that applies a voltage to the charger terminal. The circuit of FIG. 8 includes a step-up transformer T81, a transistor Q81, a diode D81, a capacitor C81, a resistor R81, a resistor R82, a resistor R83, and a resistor R84. Two high voltage generators 80 are provided, and their outputs are connected to the charger terminal 71 and the charger terminal 72 of FIG. The transistor Q81 is a switching transistor provided on the input side of the step-up transformer T81, and the diode D81 is a rectifier circuit provided on the output side of the step-up transformer T81. The switching transistor Q81 is turned on / off according to the PWM pulse signal. As a result, the current flowing to the primary side of the step-up transformer T81 is turned on / off by the power supply voltage V81, so that a high voltage is applied to the secondary side of the switching transistor Q81. A pulse is generated, and the high-voltage pulse is rectified by the diode D81 to supply a high voltage to the load. Also, the voltage supplied to the charger terminal can be controlled by controlling the PWM pulse width.

  FIG. 9 is an example of a grid voltage circuit for applying a stable voltage to the grid terminals. The circuit in FIG. 9 includes a transistor Q91, a Zener diode D91, a comparator CP91, a capacitor C91, a resistor R91, a resistor R92, and a resistor R93. A signal obtained by comparing the voltage Vfb corresponding to the grid supply voltage with the reference voltage Vref by the comparator CP91 is generated, and the switching transistor Q91 is controlled based on this signal, thereby supplying a stable voltage to the grid voltage.

  10A and 10B are configuration diagrams of an output limiting circuit based on leak detection. FIG. 10A includes a comparator CP101. In the circuit operation, the reference voltage Vref and the voltage Vfbi are compared by the comparator CP101, a PWM having a predetermined pulse width or a PWM having a pulse width = 0 is output from the comparison result, and this output is supplied to the base of the switching transistor Q81. . FIG. 10B includes a microcomputer M101. The circuit operation outputs a PWM with a predetermined pulse width or a PWM with a pulse width = 0 from the microcomputer M101 that receives the voltage Vfbi, and supplies this output to the base of the switching transistor Q81.

  FIG. 11 is an example of a configuration diagram of the output stop circuit 110 based on leak detection. The circuit in FIG. 11 includes a transistor Q111, a transistor Q112, a capacitor C111, a resistor R111, a resistor R112, a resistor R113, and a resistor R114. The switching state of the transistors Q111 and Q112 is changed by the voltage Vfbi, and a stop signal is generated. This stop signal is supplied to the base of the switching transistor Q81. Instead of supplying to the base of the switching transistor Q81, it may be controlled to cut off the supply of the power source V81.

  Next, the high voltage output operation will be described. FIG. 12 shows an operation example of output voltage limitation controlled by a microcomputer. First, the operation when there is no leakage current will be described. Step S121 indicates that it is operating. Next, in step S122, the microcomputer updates the FB value. Next, in step S123, the microcomputer multiplies the difference between the target value and the FB value by a gain to perform a PWM value calculation process. Next, in step S124, the presence / absence of leakage is determined based on the voltage Vfbi. In this case, since it is determined that there is no leakage, the output voltage is turned off in step S126. If the output voltage is off, the output is turned off in step S128. On the other hand, if the output voltage is not turned off, the PWM value is updated in step S127. In a state where there is no leak, step S122, step S123, step S124, step S126, and step S127 are repeated. If the leakage current exceeds a predetermined value, it is determined in step S124 that there is a leak based on the voltage Vfbi. In step S125, PWM = 0 or PWM = predetermined value is processed. This operation is not limited to microcomputer control, and can be realized by the output limiting circuit 100 based on leak detection in FIG.

  FIG. 13 shows an operation example of output voltage stop by microcomputer control. First, the operation when there is no leakage current will be described. Step S131 indicates that it is operating. Next, at step S132, the FB value is updated. Next, in step S133, a PWM value calculation process is performed by multiplying the difference between the target value and the FB value by a gain. Next, in step S134, it is determined whether there is a leak based on the voltage Vfbi. In this case, since it is determined that there is no leak, the PWM value update process is performed in step S136. In a state where there is no leak, step S132, step S133, step S134 and step S136 are repeated. If the leakage current exceeds a predetermined value, if it is determined in step S134 that there is a leak, the output is turned off in step S137. This operation is not limited to microcomputer control, and can be realized by the output stop circuit 110 based on leak detection in FIG.

  FIG. 14 is a diagram showing the voltage, current, and impedance of a high-voltage load when a leak occurs during high-voltage output in the present invention. Here, the leakage phenomenon is exemplified by arc discharge of the charging charger. The horizontal axis represents time, and the vertical axis represents the voltage 154, current 155, and impedance 156 of the high-voltage load. It shows how the voltage 154, current 155, and load 156 at the time of leakage change in three states with different amounts of leakage (leakage a151 <leakage b152 <leakage c153). Similar to the prior art of FIG. 3 in which the high-voltage load impedance is smaller than that of the present invention, as the amount of leakage decreases, the changes in the voltage 154, current 155, and impedance 156 of the high-voltage load become smaller. However, compared with the prior art of FIG. 3, the amount of change in the current of the present invention is large. In the present invention, since the impedance of the high-voltage load is made larger than that of the prior art, the amount of change in impedance due to the leakage current is larger than that of the prior art, and the amount of change in current is also corresponding to this large amount of impedance change. Because it grows. By increasing the amount of change in current, the change in current waveform can be increased.

  A feature of the present invention is to increase the impedance of the high voltage load by having a plurality of wires inside the casing of the scorotron charger. By doing so, the amount of change in current increases in accordance with this large amount of change in impedance, so that the change in current waveform can be increased. And since the waveform change at the time of the leak becomes large, the leak detection is improved, and the output can be stopped and the output power can be limited even in the leak state.

  FIG. 15 is a block diagram of the second embodiment. In this example, two scorotron chargers are provided. A charger terminal 141, a grid terminal 142, a casing 143, a charger terminal 144, a grid terminal 145, and a casing 146 are included. The circuit for applying to the charger terminal and the grid terminal is the same as in the first embodiment.

  The feature of this embodiment is that the impedance of the high voltage load is increased by providing a plurality of scorotron chargers. By increasing the impedance, the amount of impedance change is also larger than in the conventional technology, and the amount of change in current increases with this large amount of impedance change, improving the detection of leaks and stopping output even in leak conditions And limiting the output power.

  In addition, the transfer roller 211, the transfer belt 221, the static elimination needle 231 and the developing unit 241 are each provided in two, and at the same time, it is possible to increase the impedance of the high voltage load by acting on the load in parallel. Since the impedance change amount is larger than that of the conventional technology and the current change amount is also increased according to this large impedance change amount, the detection of leak is improved, and the output is stopped or stopped even in the leak state. The limitation of output power can be realized, and the same effect as a scorotron device can be obtained.

  The present invention is not limited to the specifically disclosed embodiments, and various modifications and changes can be made without departing from the scope of the claims.

1 is a diagram illustrating an overall configuration of a general image forming apparatus. It is a block diagram which shows the example of an image formation part. It is a figure of the example of the processing apparatus which processes a high voltage | pressure load. It is a block diagram of the high voltage | pressure output production | generation apparatus which supplies a high voltage to a charging device. It is another block diagram of a high voltage | pressure production | generation part. It is a figure which shows the voltage, electric current, and impedance of a high voltage | pressure load when a leak generate | occur | produces during a high voltage | pressure output. It is a block diagram of a 1st Example. It is a circuit diagram of the high voltage production | generation part 80 which applies a voltage to a charger terminal. It is a figure of the grid voltage circuit for applying the stable voltage to a grid terminal. It is a block diagram of the output limiting circuit by leak detection It is a block diagram of the output stop circuit 110 by leak detection. It is a figure explaining the operation | movement of the output voltage restriction | limiting controlled by a microcomputer. It is a figure explaining the operation | movement of the output voltage stop by microcomputer control. In this invention, it is a figure which shows the voltage, electric current, and impedance of a high voltage | pressure load when a leak generate | occur | produces during a high voltage | pressure output. It is a block diagram of a 2nd Example.

Explanation of symbols

1 Image forming device 2 Digital camera 3 Personal computer 4 FAX
DESCRIPTION OF SYMBOLS 5 Scanner apparatus 11 Photoconductor 12 Charging apparatus 13 Exposure apparatus 14 Developing apparatus 15 Transfer apparatus 16, 231 Electric discharge needle 17 Fixing apparatus 18 Cleaning apparatus 19 Electric discharge apparatus 40 High voltage generation part 70, 201 Scorotron type charger 71, 72, 141, 144 , 205 Charge terminal 73, 74, 202 Charging wire 75, 142, 145, 206 Grid terminal 76, 143, 146, 203 Casing 80 High voltage generator 110 Output stop circuit 204 Grid 211, 222 Transfer roller 212 Roller 213 Shaft 214, 225 233, 243 Terminal 221 Transfer belt 223 Belt 224 Belt transport roller 226 Belt drive roller 232 Static elimination needle body 241 Development unit 242 Development unit body

Claims (6)

In an image forming apparatus having a high-voltage load and a processing device having the high-voltage load as a load,
An image forming apparatus comprising: a plurality of the processing devices, wherein the plurality of processing devices simultaneously process the high-voltage load in parallel. The processor is
Scorotron charger,
Transfer roller,
Transfer belt,
The image forming apparatus according to claim 1, wherein the image forming apparatus is a static elimination needle or a developing unit. In an image forming apparatus having a scorotron charger for charging an object to be charged,
2. The image forming apparatus according to claim 1, wherein the scorotron charger has a plurality of charging wires for charging the member to be charged. In an image forming apparatus having a scorotron charger for charging an object to be charged,
An image forming apparatus, wherein the object to be charged is charged using a plurality of scorotron chargers having a single charging wire. Charging means for charging the charging wire of the scorotron charger;
Charge control means for controlling the charge amount of the charging means,
2. The charging unit according to claim 1, wherein when the discharge current in the charging wire exceeds a predetermined amount, the charging control unit controls the charging unit to limit or stop the output of the charging unit. The image forming apparatus according to 3 or 4. A grid portion for controlling discharge in the charging wire;
Grid voltage supply means for supplying a grid voltage to the grid portion;
Grid voltage control means for controlling the grid voltage,
6. The image forming apparatus according to claim 5, wherein when the discharge current in the charging wire exceeds a predetermined amount, the grid voltage control unit controls the grid voltage supply unit to limit or stop the discharge current. .

Images