JP2006154077A - High voltage power supply - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a voltage detecting circuit used only by a bias power supply of one polarity in a high voltage power supply apparatus configured to superimpose and output two bias power supplies having different polarities in an image forming apparatus using an electrophotographic process. A high-voltage power supply device that efficiently transfers the output voltage of the bias power supply to the output terminal by electrically disconnecting the bias power supply with the polarity of.
Rectification means is provided in the voltage detection means, and when one bias power supply is operating, the output voltage is detected by the voltage detection means, and when the other bias power supply is operating, the voltage detection circuit is electrically disconnected by the rectification means. A high-voltage power supply device that is configured as described above.
[Selection] Figure 1

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. 4 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. The scanner units 100a to 100d sequentially irradiate the photosensitive drums 101a to 101d with laser light in accordance with the detection timing of the registration sensor 112 in the previous period. 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. 4 will be described with reference to FIG. The high-voltage power supply device includes four types of charging biases HVPri 30a to 30d, developing biases HVDev 31a to 31d, transfer biases HVTr32a to 32d, and transfer reverse biases HVTrn33a to 33d. The charging biases HVPri 30a to 30d are applied to the charging rollers 104a to 104d to form a background potential on the surfaces of the photoconductive drums 101a to 101d, and the electrostatic latent images 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 transfer reverse bias HVTrns 33a to 33d is applied to the transfer rollers 106a to 106d to return the waste toner on the transport belt 105 to the photosensitive drums 101a to 101d, and performs the cleaning operation of the transport 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. Therefore, in this configuration, it is necessary to apply transfer biases HVTr32a to 32d and transfer reverse biases HVTrn33a to 33d having different polarities to the transfer rollers 106a to 106d, respectively.

A conventional circuit configuration capable of outputting both positive and negative biases having different polarities includes a configuration in which a negative bias power source and a positive bias power source are connected in series to superimpose an output voltage (see, for example, Patent Document 1). The conventional circuit configuration will be described below with reference to FIG. The positive bias power source 42 amplifies the AC signal output by the control circuit 210 several tens of times by the transformer 200, and then smoothes the AC signal to a positive DC signal by a rectifier circuit including the diode 202 and the capacitor 204. The Similarly, the negative bias power supply 43 amplifies the AC signal output by the control circuit 211 several tens of times by the transformer 201, and then smoothes the AC signal to a negative DC signal by a rectifier circuit including the diode 203 and the capacitor 205. It becomes. Furthermore, by connecting the positive bias power source 42 and the negative bias power source 43 in series, the output voltage is superimposed and output to the output terminal 92. At this time, the positive bias power source 42 and the negative bias power source 43 are controlled by the control circuits 210 and 211 so as not to operate simultaneously. The resistors 52 and 53 are bleeder resistors for the positive bias circuit 42 and the negative bias circuit 43, respectively. Further, the voltage detection circuit 62 divides the voltage at the output terminal 92 by the resistors 60 and 61 and converts the voltage into a voltage that can be detected by the control circuit 210 of the positive bias power supply 42. The control circuit 210 adjusts the output voltage of the positive bias power supply 42 based on the detection result. Further, in this circuit example, the negative bias power supply 43 is for cleaning and does not require high voltage accuracy, so the output voltage is not detected.
JP 2000-3103 A

  However, in the above conventional example, the voltage appearing at the output terminal when the negative bias power supply 43 is operated is divided by the bleeder resistor 52 and the voltage detection resistors 60 and 61. For this reason, the negative bias power supply 43 needs to output a negative voltage larger than the negative voltage required for the output terminal 92. For this reason, it is necessary to design the maximum output voltage of the negative bias power supply 43 to be large, and there are problems such as an increase in the size and cost of the device.

  Accordingly, an object of the first invention according to the present application is to realize a configuration in which the voltage detection circuit used only by the bias circuit of one polarity is electrically disconnected when the bias circuit of the other polarity is in operation.

  In addition, an object of the second invention according to the present application is to realize the object of the first invention by inserting a rectifier circuit between the output terminal and the voltage detection circuit in the first invention.

  In addition, an object of the third invention according to the present application is to realize the object of the first invention by inserting a rectifier circuit between two resistors constituting the voltage detection circuit in the first invention. is there.

  In order to achieve the above object, a first invention according to the present application includes two bias power supplies having different polarities and voltage detecting means for detecting a voltage, and the voltage detecting means outputs outputs of the two bias power supplies. In the high voltage power supply apparatus configured to detect the voltage at the output terminal on which the voltage is superimposed, the voltage detecting means is provided with a rectifying means, so that when one of the bias power supplies is operating, the output voltage is detected by the voltage detecting means, and the other When the bias power supply is in operation, the voltage detecting circuit is electrically disconnected by the rectifying means.

  In order to achieve the above object, according to a second invention of the present application, in the high-voltage power supply apparatus configured by two resistors in which the voltage detection unit is connected in series, the rectification unit is connected to the output terminal. And the voltage detecting means.

  In order to achieve the above object, according to a third aspect of the present invention, there is provided a high voltage power supply apparatus including two resistors in which the voltage detection unit is connected in series, wherein the rectification unit includes the two rectification units. It is provided between the resistors.

  According to the first invention of the present application, since the maximum output voltage of the bias power supply can be set low, the device can be reduced in size and the cost can be reduced.

  According to the second invention of the present application, in the first invention, the configuration can be realized by a simple circuit in which the rectifying means is provided between the output terminal and the voltage detecting means.

  Further, according to the third invention of the present application, in the first invention, the configuration can be realized by a simple circuit in which the rectifying means is provided between the two resistors constituting the voltage detecting means.

  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. Elements common to those in FIG. 6 having the conventional configuration are denoted by the same reference numerals, and description thereof is omitted. The difference from FIG. 6 is that a diode 70 as a rectifier is disposed between the output terminal 92 and the output detection circuit 62. In this configuration, since a reverse voltage is applied to the diode 70 during operation of the negative bias power supply 43, the output detection circuit 62 is electrically disconnected from the output terminal 92. In addition, since the forward voltage is applied to the diode 70 during the operation of the positive bias power supply 42, the voltage at the output terminal 92 can be detected by the voltage detection circuit 62. At this time, since a voltage obtained by subtracting the forward voltage of the diode 70 from the voltage at the output terminal 92 is detected, the positive bias power source 42 is controlled after correction by the control circuit 210. Therefore, according to the present embodiment, the output voltage of the negative bias power supply 43 can be efficiently transmitted to the output terminal 92, so that the maximum output voltage of the negative bias power supply 43 can be set lower than in the conventional configuration.

  FIG. 2 is a block diagram showing a high-voltage power supply device according to the second embodiment of the present invention. Elements common to those in FIG. 1 as the first embodiment are denoted by the same reference numerals, and description thereof is omitted. The difference from FIG. 1 is that a transformer unit 40 in which diodes 208 and 209, a capacitor 204, a bleeder resistor 52, a voltage detection resistor 60, and the like, which are high-voltage circuits on the secondary side of the transformer 200, are sealed together with the transformer 200 is used. And a capacitor 70 as a smoothing means is provided between the voltage detection resistors 60 and 61. Here, the detection result of the output voltage is taken out between the capacitor 70 and the resistor 61. The configuration using the transformer unit 40 is often used in a high-voltage power supply device that outputs a particularly high voltage. In this configuration, as in the first embodiment, since the reverse voltage is applied to the diode 70 when the negative bias power supply 43 is in operation, the resistor 61 and the control circuit 210 can be electrically disconnected from the output terminal. Thereby, it is possible to prevent the voltage detection circuit constituted by the resistors 60 and 61 from dividing the output voltage of the negative bias power supply 43. Therefore, according to the present embodiment, a circuit having the same effect as that of the first embodiment can be configured even when a high-voltage power supply device having a configuration in which the secondary high-voltage circuit of the transformer is sealed with resin is used.

  FIG. 3 is a block diagram showing a high-voltage power supply device according to the third embodiment of the present invention. Elements common to those in FIG. 1 as the first embodiment are denoted by the same reference numerals, and description thereof is omitted. The difference from FIG. 1 is that the positive bias power supplies 42a and 42b are provided for the two output terminals 92a and 92b, respectively, and the negative bias power supply 43 is shared, and the positive bias power supplies 42a and 42b are connected to the diode 220a. ˜223a, capacitors 230a to 233a, diodes 220b to 223b, and capacitors 230b to 233b. Since the positive bias power sources 42 a and 42 b are configured by a quadruple rectifier circuit, the anode ends of the diodes 230 a and 230 b that are the ground side output ends of the positive bias power sources 42 a and 42 b are both connected to the output end of the negative bias power source 43. By connecting, the output voltage of the negative bias power supply 43 is transmitted to the output ends 92a and 92b. According to this configuration, the diodes 70a and 70b, which are rectifiers, are provided in the voltage detection circuits 62a and 62b of the positive bias power supplies 42a and 42b, respectively, so that when the positive bias power supplies 42a and 42b are in operation, The voltage detection circuits 62a and 62b detect the voltages at the output terminals 92a and 92b, respectively. When the negative bias power supply 43 is in operation, the voltage detection circuits 62a and 62b are both electrically disconnected from the output terminals 92a to 92d. Therefore, according to the present embodiment, a circuit having the same effect as that of the first embodiment is configured even in a circuit configuration including a plurality of rectification stages or a configuration in which a plurality of positive bias power sources are connected to one negative bias power source. I can do it.

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 block diagram which shows 2nd Embodiment of the high voltage power supply device which concerns on this invention. 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. 5 is a configuration diagram of a high voltage power supply device in the image forming apparatus of FIG. 4. It is a circuit block diagram in the high voltage power supply device of FIG.

Explanation of symbols

40 Flyback transformer 42 Positive bias power supply 43 Negative bias power supply 51-53 Breeder resistance 62 Voltage detection circuit 70 Rectifier means 210, 211 Control means

Claims (3)

  A high-voltage power supply device used in an image forming apparatus using an electrophotographic process, comprising: two bias power supplies having different polarities; and a voltage detecting means for detecting a voltage, the voltage detecting means comprising: In the high voltage power supply device configured to detect the voltage at the output terminal on which the output voltage is superimposed, by providing a rectifying means in the voltage detecting means, the output voltage is detected by the voltage detecting means when one of the bias power supplies is operating, A high-voltage power supply apparatus configured to electrically disconnect the voltage detection circuit by the rectifying means when the other bias power supply is in operation.   2. The high voltage power supply apparatus constituted by two resistors in which the voltage detection means is connected in series, wherein the rectification means is provided between the output terminal and the voltage detection means. The high-voltage power supply device described in 1.   2. The high voltage power supply apparatus according to claim 1, wherein the voltage detecting means is a high voltage power supply device configured by two resistors connected in series, and the rectifying means is provided between the two resistors. Power supply.

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