JP2006115606A - High voltage power supply - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve a high-voltage power supply used in an image forming apparatus using an electrophotographic process, and having a plurality of output terminals and no effect on the other output terminals if an output voltage is fluctuated due to a rapid fluctuation of a load connected to any output. <P>SOLUTION: The high-voltage power supply is provided with a voltage transforming means, and a full-wave rectifying means. The full-wave rectifying means is divided into a first rectifying means for outputting an AC voltage without smoothing an output from the voltage transforming means, and second rectifying means for smoothing an output from the first rectifying means and outputting a DC voltage. A plurality of the second rectifying means are connected to the first rectifying means. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a high-voltage power supply device for an image forming apparatus using an electrophotographic process.

  As an example of a conventional high-voltage power supply device, a configuration of an image forming apparatus, a configuration of a high-voltage power supply device used therein, and a circuit configuration of the high-voltage power supply device will be described in order.

  FIG. 6 is a block diagram of a four-drum color laser printer which is an image forming apparatus showing a conventional example. Here, first, the recording medium 110 fed out by the pickup roller 111 is detected by the registration sensor 112 and conveyed by the conveyance roller pairs 113 and 114 and the conveyance belt 105. Further, according to the detection timing of the registration sensor 112, the scanner units 100a to 100d sequentially irradiate the photosensitive drums 101a to 101d with laser light. At this time, the photosensitive drums 101a to 101d are charged by the charging rollers 104a to 104d, and electrostatic latent images are formed by the irradiation of the laser light, and toner images are further formed by the developing units 102a to 102d and the developing sleeves 103a to 103d. Form. Then, the toner image is transferred to the recording medium 110 conveyed on the conveying belt 105 by the transfer rollers 106a to 106d. Thereafter, the recording medium 110 is conveyed to the fixing device 107, and an image is formed and then output. Here, the alphabetic character a of each symbol indicates a configuration / unit of black, b is cyan, c is magenta, and d is yellow.

  Next, the configuration of the high-voltage power supply device in the image forming apparatus of FIG. 6 will be described with reference to FIG. The high-voltage power supply device includes four types of charging bias HVPri30, developing bias HVDev 31a to 31d, transfer bias HVTr32a to 32d, and transfer reverse bias HVTrn33. The charging bias HVPri30 is applied to the charging rollers 104a to 104d to form a background potential on the surface of the photosensitive drums 101a to 101d, and an electrostatic latent image can be formed by irradiation with laser light. The development biases HVDev 31a to 31d are applied to the development sleeve 103b, thereby placing toner on the electrostatic latent image and forming a toner image. The transfer biases HVTr 32 a to 32 d are applied to the transfer rollers 106 a to 106 d to transfer the toner image to the recording medium 100. Further, the reverse transfer bias HVTrn33 is applied to the transfer rollers 106a to 106d to return the waste toner on the conveyance belt 105 to the photosensitive drums 101a to 101d, and performs the cleaning operation of the conveyance belt 105. At this time, the waste toner returned to the photosensitive drums 101a to 101d is scraped off by the cleaning blades 115a to 115d and stored in the waste toner containers 116a to 116d. Here, the charging bias HVPri30 and the transfer reverse bias HVTrn33 are connected to a plurality of output terminals from one high-voltage power supply device without providing a high-voltage power supply device for each color for space saving and cost reduction.

  Next, the circuit configuration of the high-voltage power supply device of FIG. 7 will be described with reference to FIGS. FIG. 8 is a circuit configuration example of the charging bias HVPri30. FIG. 9 shows voltage waveforms of the circuit of FIG. 8, and waveforms 300 to 302 of FIG. 9 show voltage waveforms of the nodes 400 to 402 of FIG. Here, the AC voltage generated by the voltage source 200 is boosted to a voltage 300 having an amplitude of several tens of times by the transformer 201, and then converted to a DC voltage having a double voltage by the full-wave rectifier circuit 206. Smoothed. Here, if the full-wave rectifier circuit 206 is divided into a first rectifier circuit 207 and a second rectifier circuit 208 as shown in FIG. 8, the first rectifier circuit 207 is derived from the output waveform 300 of the transformer 201. Then, an AC waveform 301 in which the DC voltage level is shifted by its own peak voltage is output. The second rectifier circuit 208 outputs an output waveform 302 smoothed with a peak voltage from the output waveform 301 of the first rectifier circuit 207. The DC voltage output 302 of the full-wave rectifier circuit 206 is connected to a plurality of output terminals 211a to 211d, and the output terminals 211a to 211d are respectively connected to the charging rollers 104a to 104d shown in FIG. The detection unit 209 detects the output voltage of the full-wave rectifier circuit 206 and controls the output voltage of the voltage source 200 through the control unit 210 based on the detection result.

  Here, as a problem of the circuit configuration of FIG. 8, since the plurality of output terminals 211 a to 211 d are directly connected to the same node 402, the current flowing through the load at one of the output terminals increases rapidly, When the output voltage of the wave rectifier circuit 206 is temporarily lowered, there is a problem that the voltages at all other output terminals are similarly lowered. As a conventional technique for solving this problem, there is a configuration in which a rectifying element and a storage element are inserted between a constant voltage circuit and a load (see, for example, Patent Document 1).

Hereinafter, this configuration will be described with reference to FIG. FIG. 10 differs from FIG. 8 in that a full-wave rectifier circuit 206 as a constant voltage circuit and output terminals 211a to 211d to which loads are connected, diodes 213a to 213d as rectifier elements, and capacitors as storage elements. That is, the hold circuits 212a to 212d constituted by 214a to 214d are connected. Thereby, for example, when the current flowing through the load of the output terminal 211d suddenly increases and the output voltage of the full-wave rectifier circuit 206 is temporarily reduced, the other output terminals 211a to 211c are caused by the diodes 213a to 213c. Is electrically disconnected from the full-wave rectifier circuit 206 to prevent the current from flowing in reverse, and the capacitors 214a to 214c have the effect of stabilizing the output voltages of the other output terminals 211a to 211c.
Japanese Patent Laid-Open No. 7-210262

  However, in the above conventional example, since a smoothing circuit is added to stabilize the output voltage, the number of high withstand voltage elements increases, which causes problems such as an increase in substrate size and an increase in cost.

  Accordingly, an object of the first invention according to the present application is to realize a high voltage power supply apparatus in which the number of high voltage elements is minimized while stabilizing output voltages at a plurality of output terminals.

  In addition, an object of the second invention according to the present application is to realize a high-voltage power supply apparatus that controls the voltage at any one output terminal with high accuracy in the first invention.

  Furthermore, an object of the third invention according to the present application is to realize a high-voltage power supply apparatus in the first invention, in which the withstand voltage required for the output voltage detection circuit is kept low.

  A fourth object of the present invention is to stabilize a transfer reverse bias output of an image forming apparatus according to the first invention.

  A fifth object of the present invention is to stabilize the charging bias output of the image forming apparatus according to the first invention.

  In order to achieve the above object, a first invention according to the present application includes a transforming unit and a full-wave rectifying unit including a plurality of rectifying elements, and the full-wave rectifying unit does not perform smoothing and does not perform smoothing. The second rectifying means for smoothing the outputs of the plurality of first rectifying means and outputting the DC voltage is connected to the output of the first rectifying means for outputting the voltage.

  In order to achieve the above object, according to a second aspect of the present invention, there is provided a voltage detection means for detecting a voltage in the first invention, and an input voltage of the transformation means based on a detection result of the voltage detection means. Control means for controlling, and the voltage detecting means detects any one output voltage of the second rectifying means.

  In order to achieve the above object, according to a third aspect of the present invention, there is provided a voltage detecting means for detecting a voltage in the first invention, and an input voltage of the transformer means based on a detection result of the voltage detecting means. Control means for controlling, and the voltage detecting means detects the voltage of the first rectifying means.

  In order to achieve the above object, according to a fourth invention of the present application, in the color image forming apparatus, the high-voltage power supply device according to any one of the first to third inventions is used for each color. It was used as a reverse bias for transfer.

  In order to achieve the above object, according to a fifth aspect of the present invention, in the color image forming apparatus, the high-voltage power supply device according to any one of the first to third aspects is used for each color. It is used as a charging bias of

  As described above, according to the first invention of the present application, it is possible to minimize the increase in the high withstand voltage elements while stabilizing the output as compared with the conventional configuration. As a result, costs can be reduced.

  According to the second invention of the present application, in the first invention, the voltage at any one of the output terminals can be controlled with higher accuracy.

  According to the third invention of the present application, in the first invention, the withstand voltage of the output voltage detecting means can be kept low, and the cost can be reduced.

  According to the fourth aspect of the present application, the transfer reverse bias output of the image forming apparatus can be stabilized by the first aspect.

  According to the fifth aspect of the present application, the charging bias output of the image forming apparatus can be stabilized by the first aspect.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to examples.

  FIG. 1 is a configuration diagram showing a high-voltage power supply device according to the first embodiment of the present invention, which is an example in which the present invention is applied to a charging bias HVPri30. Elements common to those in FIG. 8 or FIG. 10 that are conventional configurations are denoted by the same reference numerals, and description thereof is omitted. The difference from the conventional configuration of FIG. 10 is that the full-wave rectifier circuit 206 in the conventional configuration is divided into a first rectifier circuit 207 and a second rectifier circuit 208, and the second rectifier circuit is independently provided for each of the output terminals 211a to 211d. The second rectifier circuits 208a to 208d have the effects of the second rectifier circuit 208 and the hold circuits 212a to 212d in the conventional configuration shown in FIG. Here, in this configuration, a full-wave rectifier circuit as a constant voltage circuit is configured by a combination of the first rectifier circuit 207 and the second rectifier circuits 208a to 208d.

  The circuit configuration of FIG. 1 will be described below using the waveforms of FIG. Waveforms 310 to 312 in FIG. 2 indicate voltage waveforms at nodes 410 to 412 in FIG. The first rectifier circuit 207 outputs an AC voltage 311 that is DC-shifted from the AC output voltage 310 of the transformer 201 by an amount corresponding to its peak voltage. The second rectifier circuits 208a to 208d output a DC voltage 312 obtained by smoothing the AC output voltage 311 of the first rectifier circuit 207. Further, the voltage detection circuit 209 detects the output voltage of the second rectifier circuit 208a, and the control circuit 210 controls the output voltage of the voltage source 200 based on the detection result of the voltage detection circuit 209. Here, the second rectifier circuits 208a to 208d have the same effects as the hold circuits 212a to 212d in the conventional configuration of FIG. Thereby, for example, when the current flowing through the load of the output terminal 211d suddenly increases as in the conventional example, the output voltage of the first rectifier circuit 207 temporarily decreases, but the second rectifier circuits 208a to 208d are configured. The diodes 204a to 204d are effective in preventing current from flowing in reverse from the other output terminals 211a to 211c and stabilizing the output voltage by the capacitors 205a to 205d.

  According to this embodiment, one set of diodes and capacitors can be reduced compared to the conventional configuration of FIG. 10 while suppressing mutual interference of output voltages due to load fluctuations. These elements are high withstand voltage elements that are large in size and high in cost, and can be reduced in size and cost. In this embodiment, the output voltage of the output terminal 212a to which the voltage detection circuit 209 is connected can be controlled with particularly high accuracy.

  FIG. 3 is a configuration diagram showing a second embodiment of the high-voltage power supply device according to the present invention, and is a circuit example in which the present invention is applied to a transfer reverse bias HVTrn33. Elements common to those in FIG. 8 or FIG. 10 as the conventional configuration and FIG. 1 as the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. The difference from FIG. 1 which is the first embodiment is that the polarity of the output voltage is reversed and that it is constituted by a quadruple rectifier circuit, and transfer biases HVTr32a to 32d having different polarities are connected to each output terminal. Therefore, it is configured to be able to output both positive and negative biases. When configured by a quadruple rectifier circuit, the three sets of diodes 230 to 232 and capacitors 240 to 242 arranged on the transformer 201 side are regarded as the first rectifier circuit 220 and arranged most on the output ends 222a to 222d side. The diodes 233a to 233d and the capacitors 243a to 243d are regarded as the second rectifier circuits 221a to 221d. By connecting a plurality of second rectifier circuits 221a to 221d to the first rectifier circuit 220, the second rectifier circuits 221a to 221d are the effects of the second rectifier circuit 208 and the hold circuits 212a to 212d in the conventional configuration of FIG. It is the same as that of Example 1 to have both.

  Further, transfer biases HVTr32a to 32d having different polarities are connected to the output terminals 222a to 222d of the transfer reverse bias HVTrn33 together with bleeder resistors 251a to 251d and 252a to 252d, so that the output terminals 250a to 250d are both positive and negative. A bias can be output.

  Hereinafter, the circuit configuration of FIG. 3 will be described with reference to the waveforms of FIG. Waveforms 320 and 322 to 324 in FIG. 4 show voltage waveforms at the nodes 420 and 422 to 424 in FIG. The first rectifier circuit 220 outputs, from the AC output voltage 310 of the transformer 201, an AC voltage 323 having a polarity opposite to that of the first embodiment and DC-shifted by three times its peak voltage. In addition, the operations and effects of the second rectifier circuits 221a to 221d are the same as those in the first embodiment except that the polarities are reversed.

  According to this embodiment, even in a high-voltage power supply device configured by a quadruple rectifier circuit having a reverse polarity, as in the first embodiment, the size of the device can be reduced as compared with the prior art while suppressing mutual interference of output voltages due to load fluctuation. In addition, the cost can be reduced.

  FIG. 5 is a configuration diagram showing a third embodiment of the high-voltage power supply device according to the present invention, and is a circuit example in which the present invention is applied to the transfer reverse bias HVTrn 33 as in the second embodiment. Moreover, the voltage waveform is the same as that of Example 2 shown in FIG. Elements common to those in FIG. 3 as the second embodiment are denoted by the same reference numerals, and description thereof is omitted. The difference from FIG. 3 which is the second embodiment is that the voltage detection circuit 209 is configured to detect the voltage of the node 422 in the first rectifier circuit 220 instead of the output terminal 424 of the second rectifier circuit 221a. . According to this configuration, a DC voltage having a voltage half that of the node 424 that is the output terminal of the quadruple rectifier circuit is applied to the node 422. Therefore, the detection result of the voltage detection unit 209 is converted to double, The output voltage of the voltage source 200 is controlled through the control means 210.

  According to the present embodiment, since the output voltage is detected from the first rectifier, the withstand voltage required for the voltage detection circuit 209 can be kept low compared with the configuration in which the output voltage is detected from the output terminal, and the cost is low. Can be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram which shows 1st Embodiment of the high voltage power supply device which concerns on this invention. It is a figure which shows the operating voltage waveform of the high voltage power supply device shown in FIG. It is a block diagram which shows 2nd Embodiment of the high voltage power supply device which concerns on this invention. It is a figure which shows the operating voltage waveform of the high voltage power supply device shown in FIG. It is a block diagram which shows 3rd Embodiment of the high voltage power supply device which concerns on this invention. It is a block diagram of the image forming apparatus which shows a prior art example. FIG. 7 is a configuration diagram of a high voltage power supply device in the image forming apparatus of FIG. 6. FIG. 8 is a circuit configuration diagram of a charging bias in the high voltage power supply device of FIG. 7. It is a voltage waveform in the high voltage power supply device of FIG. It is a circuit block diagram of the charging bias which shows a prior art example.

Explanation of symbols

30 Charging bias 33 Transfer reverse bias 32a to d Transfer bias 200 Voltage source 201 Transformer 209 Voltage detection means 210 Control means 207 First rectification means 208a to d Second rectification means 220 First rectification means 221a to d Second rectification means

Claims (5)

  An image forming apparatus using an electrophotographic process, comprising: a transformer means; and a full-wave rectifier means including a plurality of rectifier elements, wherein the full-wave rectifier means does not smooth the output of the transformer means In a high-voltage power supply apparatus configured by a first rectifier that outputs an AC voltage to a second rectifier and a second rectifier that outputs a DC voltage by smoothing the output of the first rectifier, the output of the first rectifier A high-voltage power supply device comprising a plurality of the second rectifying means connected.   Voltage detecting means for detecting a voltage, and control means for controlling an input voltage of the transformer means based on a detection result of the voltage detecting means, wherein the voltage detecting means is one of the second rectifying means. The high-voltage power supply device according to claim 1, wherein the high-voltage power supply device is configured to detect an output voltage.   Voltage detecting means for detecting a voltage, and control means for controlling an input voltage of the transformer means based on a detection result of the voltage detecting means, wherein the voltage detecting means detects a voltage of the first rectifying means. The high voltage power supply device according to claim 1, wherein the high voltage power supply device is configured as described above.   4. The high-voltage power supply according to claim 1, wherein outputs of the plurality of second rectifiers are used as transfer reverse biases for the respective colors in a color image forming apparatus. 5. apparatus.   4. The high-voltage power supply apparatus according to claim 1, wherein outputs of the plurality of second rectifying units are used as charging biases for the respective colors in a color image forming apparatus. 5. .

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