JP4774344B2 - High voltage power supply device and image forming apparatus - Google Patents

Description

The present invention, high-voltage power supply apparatus for processing residual potential accumulated in the load relates to an image forming equipment having the high-voltage power supply apparatus.

  FIG. 8 is a diagram showing a schematic configuration of a conventional image forming apparatus. As shown in the figure, an image forming apparatus such as a copying machine or a laser printer includes a photoconductor 1 as an image carrier, a charging device 2 for forming an electrostatic latent image on the photoconductor 1, and the photoconductor 1. An endless belt-like intermediate transfer that is stretched between a developing device 3 for visualizing the electrostatic latent image of the image and two rollers 4 for transferring the image on the developed photoreceptor 1. A recording medium in which an image on the photosensitive member 1 transferred to the intermediate transfer member 5 is fed from a pair of paper feed rollers 7; a primary transfer device 6 for transferring an image on the photosensitive member 1 to the intermediate transfer member 5; And a secondary transfer device 8 for transferring to transfer paper (not shown). Reference numeral 9 denotes a cleaning device for the photosensitive member 1.

  The indirect transfer type image forming apparatus schematically configured as described above includes a CPU 11, a memory 12, an input unit 13, an IO control unit 14, a writing control, as shown in a block diagram showing an electrical schematic configuration in FIG. 9. Part 15 is provided. The CPU 11 performs overall control of the image forming apparatus. The memory 12 is a ROM containing a control program, a RAM providing a work area necessary for control, an NV-RAM holding various information necessary for control, and the like. The input unit 13 inputs image data from a document reading unit such as a print controller or a scanner. The IO control unit 14 controls various electrical components such as a motor and a solenoid. The writing control unit 15 performs control for writing an image on the photosensitive member 1 of FIG.

  When these devices are operated, a high voltage output from a high voltage power supply device is used. The high-voltage power supply device is provided with a high-voltage power supply circuit 17 on the high-voltage power supply board 16 as can be seen from the diagram showing the connection relationship between the high-voltage power supply and the main components of the image forming apparatus in FIG. A negative output is supplied to the charging device 2, a positive and negative output is supplied to the developing device 3 including the photosensitive member 1, a positive output is supplied to the primary transfer device 6, and a positive and negative output is supplied to the secondary transfer device 8. is doing.

  Such a high-voltage power supply device has a rise failure at the time of positive high-voltage output due to the accumulation of negative charges in the load of the secondary transfer device 8. This is because the load of the secondary transfer device 8 accumulates negative charges due to some cause, and this causes a problem that the rising is delayed or not rising when a positive high voltage is output.

  As a cause of such a failure, a residual potential is generated with respect to the load due to a change in charging performance with time due to deterioration of the photoreceptor 1, and the residual potential is transferred from the charging device 2 and the developing device 3 to the primary transfer device 6, and further. It is considered that the residual potential is finally accumulated in the load of the secondary transfer device 8 through the path of the secondary transfer device 8.

  Therefore, conventionally, as a countermeasure against these residual potentials, a Zener diode 18 is added to the output side of the secondary transfer device 8 as shown in FIG. This is because the output of the secondary transfer device 8 needs to output both positive and negative polarities, and only a method using the Zener diode 18 can be dealt with.

As another means, for example, Patent Document 1 proposes a method of preventing the occurrence of a residual potential itself by controlling the transfer device in accordance with a change in charging property due to deterioration of the photoreceptor. In this method, in order to prevent the generation of a residual potential, the value of the leakage current to the photosensitive member is measured and the value is fed back to the transfer device.
JP 11-38702 A

  However, the method described in Patent Document 1 has a large-scale configuration including a current detection unit and a CPU that moves the transfer device according to the current.

  The present invention has been made in view of such a state of the prior art, and a problem to be solved is to make it possible to reliably remove the residual potential with a simple configuration.

In order to achieve the above object, the first means is a high voltage power supply device that applies a high voltage power supply to each of a plurality of loads, and a high voltage output capable of outputting only a single polarity and a load connected to the high voltage output. An element having a rectifying action is connected in such a direction that the reverse charge applied to the load flows to the ground.
A second means is characterized in that, in the first means, the element is a diode.
The third means is a high voltage power supply apparatus that applies a high voltage power supply to each of a plurality of loads, and a residual load in which a residual charge generated in one load is applied to the other load between the plurality of loads. When there is a plurality of loads to which only a single polarity is applied from the high-voltage power supply among the plurality of loads existing in the residual load path, a load positioned upstream of the residual load path An element having a rectifying action is connected in a direction in which a reverse charge applied to a load flows to the ground.
The fourth means is characterized in that the image forming apparatus includes a high-voltage power supply device according to any one of the first to third means.
A fifth means is the fourth means, wherein the high-voltage power supply device develops the latent image on the photosensitive member, a photosensitive member carrying the latent image, a charging unit for charging the photosensitive member. A voltage is applied to at least one of developing means, primary transfer means for transferring the developed image on the photosensitive member to an intermediate transfer member, and secondary transfer means for transferring the image on the intermediate transfer member to a recording material. It is characterized by supplying.
The sixth means is characterized in that, in the fifth means, the image forming apparatus is a color image forming apparatus, and the high-voltage power supply device is connected to the primary transfer means.

  According to the present invention, the residual potential can be surely removed by a very simple configuration in which a counter measure against reverse charges is provided in a load having a unipolar output.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same reference numerals are assigned to the same components as those in the above-described conventional example, and duplicate descriptions are omitted.

  FIG. 1 is a schematic configuration diagram of a high-voltage power supply device according to Embodiment 1 of the present invention. In the first embodiment, the high-voltage power supply 17 includes a load 21 that may generate an unintended negative charge, a first path portion 22 to which positive and negative outputs are applied, and a positive output. The second path part 23 to be applied is connected to the third path part 24 to which both positive and negative outputs are applied. In the load 21, it is assumed that negative charges flow from the first path portion 22 to the second path portion 23. Therefore, a diode 25 as a flow means for flowing negative charge, which is reverse charge, to the ground is connected to the connection line between the high voltage power supply 17 and the second path portion 23.

  In this way, by connecting the diode 25 between the output of the second path section 23 and the ground, the reverse charge is further upstream from the load 21 to the path of the residual potential such as the first path section 22 and the second path section 23. Measures will be taken. Therefore, it becomes a countermeasure for the residual potential not only for the first path portion 22 but also for the second path portion 23.

  FIG. 2 is a schematic configuration diagram of a high-voltage power supply device according to Embodiment 2 of the present invention. In the second embodiment, a case where a negative output is applied to the second path portion 23 is shown. In this case, the diode 25 is connected in the reverse direction to that of the first embodiment so that a positive charge, which is a reverse charge, flows through the connection line between the high-voltage power supply 17 and the second path portion 23 to the ground.

  FIG. 3 is a flowchart showing the control procedure of the first and second embodiments. In FIG. 3, when reverse charge is generated (step S101), reverse charge flows through the first path portion 22 (step S102). Therefore, the polarity of the charge with the first path portion 22 is checked, and if the first path portion 22 has a unipolar output and the charge has a reverse characteristic (step S103—YES), the reverse charge is reduced by the rectifying action of the diode 25. Flow to ground (step S108).

  On the other hand, if the condition that the first path portion 22 is a unipolar output and the charge has a reverse characteristic does not hold (step S103-NO), the reverse charge flows to the second path portion 23 (step S104). Therefore, the polarity of the charge with the second path portion 23 is checked. If the second path portion 23 is a unipolar output and the charge has a reverse characteristic (step S105—YES), the reverse charge is reduced by the rectifying action of the diode 25. Flow to ground (step S108).

  On the other hand, if the condition that the second path portion 23 is a unipolar output and the charge has a reverse characteristic does not hold (step S105-NO), the reverse charge flows to the third path portion 24 (step S106). Therefore, the polarity of the charge with the third path section 24 is checked. If the third path section 24 has a unipolar output and the charge has a reverse characteristic (YES in step S107), the reverse charge is caused to flow to the ground by a rectifying action. (Step S108).

  These operations are repeated for each path portion, and if the path state and the polarity state are established as in steps S103, 105, and 107, a reverse charge is caused to flow to the ground by the rectifying action of the diode 25. These operations may be controlled by the CPU 11 of the image forming apparatus shown in FIG.

  FIG. 4 is a block diagram illustrating a configuration of a third embodiment in which the high-voltage power supply device described in the first and second embodiments is applied to an image forming apparatus. That is, as in FIG. 10, a negative output is output from the high-voltage power supply circuit 17 on the high-voltage power supply substrate 16 to the charging device 2, a positive and negative output is output to the developing device 3 including the photoreceptor 1, and the primary transfer device 7. Is supplied with positive output, and the secondary transfer device 9 is supplied with positive and negative outputs. In addition, a diode 25 is connected to the connection line between the high-voltage power supply 17 and the primary second path section 23 to allow negative charge as reverse charge to flow to the ground.

  As described above, in this embodiment, the rectifying diode 25 is connected between the connecting line of the primary transfer device 6 and the ground from the high-voltage power supply 17 that outputs only a single polarity so that a negative charge as a reverse charge flows to the ground. ing. With such a configuration, the residual potential is generated in the charging device 2 and the developing device 3 that are a portion surrounded by a dotted line due to deterioration of the photosensitive member 1 or the like. The residual potential then flows from the developing device 3 to the secondary transfer device 8 from the primary transfer device 6. Here, since the output of the primary transfer device 6 has only positive polarity, if a diode 25 is added to the output section of the primary transfer device 6, the residual potential can be released to the ground. Thus, by adding the diode 25 and taking measures near the generation source, it is possible to prevent the residual potential from flowing into the secondary transfer device 8 downstream.

  FIGS. 5A and 5B are circuit diagrams for explaining the principle in the embodiment in which the means for flowing the reverse charge to the ground is constituted by a switch. FIG. 5A shows a high voltage output, and FIG. 5B shows a charge discharge. FIG. 6 is a flowchart for explaining the operation. In this embodiment, a reverse charge discharge switch that can be switched between high voltage output and non-high voltage output is provided in place of the diode 25 in the first to third embodiments. The switch 32 is provided between the high-voltage output terminal of the high-voltage power supply 17 and the load 31 that accumulates electric charges, and flows reverse charges to the ground when turned on.

  This operation procedure will be described with reference to the flowchart of FIG. 6. When reverse charge is generated (step S201), the reverse charge flows to a place where a countermeasure against reverse charge needs to be taken (step S202). Therefore, it is checked whether or not the reverse charge flows at the time of high voltage output (step S203). If it is at the time of high voltage output, the switch 32 is turned off, that is, opened as shown in FIG. 5A (step S204). A high voltage is output to 31 (step S205), and the process ends.

  On the other hand, if it is not during high-voltage output in step S203, the switch 32 is turned on, that is, short-circuited (step S206) as shown in FIG. 5B, and the reverse potential of the load 31 is discharged to the ground (step S2075). To do. These operation controls may be controlled by the CPU 11 of the image forming apparatus shown in FIG.

  In this way, by controlling the switching of the switch during high-voltage output and non-output, it is possible to flow a reverse potential with respect to the load to the ground. Further, by taking a countermeasure so that the reverse charge flows to the ground upstream of the residual potential path, it becomes a countermeasure against the residual potential not only in the portion provided with the switch 32 but also downstream thereof.

  Note that the image forming apparatus described so far takes a monochrome image as an example, but can also be applied to a color image forming apparatus.

  FIG. 7 is a diagram showing a schematic configuration of Embodiment 5 in which a high voltage power supply device is applied to a tandem type color image forming apparatus. Although not shown, the tandem type color image forming apparatus has four photoconductors for forming a latent image juxtaposed, and black (K), cyan (C), magenta (M) and magenta (M) corresponding to each photoconductor individually. A yellow (Y) developing device is provided, and a single color toner image is formed on each photoconductor, and the single color toner images are sequentially transferred to form a composite color image on a recording material. Therefore, the photosensitive member 1, the charging device 2, the developing device 3 and the cleaning device 9 shown in FIG. 8 constitute one set, and these are arranged side by side on the four sets of intermediate transfer members 5.

  FIG. 7 is a block diagram showing a main configuration when a high voltage power supply device is applied to a tandem type color image forming apparatus. The high-voltage power source 17 includes black, cyan, magenta, and yellow charging devices 2K, 2C, 2M, and 2Y, and black, cyan, magenta, and yellow developing devices 3K, 3C, 3M, and 3Y, and a primary transfer device 6. And a secondary transfer device 8 is connected. In this way, the charging output of the high-voltage power supply is 4 types of black, cyan, magenta and yellow, the development output is also 4 types of black, cyan, magenta and yellow, and the output to the primary transfer device 6 is 1 type, secondary transfer. There is one type of output to the device 8. For example, in FIG. 7, if means for flowing reverse charges to the ground is to be installed in the developing unit, it is necessary to install them at four locations. However, if the diode 25 is installed in a portion where the number of outputs is one as in the primary transfer device, the number of installation locations can be reduced.

  Further, in a model using two-component toner as a developer, the output required for development is unipolar. Therefore, when the counter charge countermeasure is to be installed in the development portion, since the number of outputs is four, the counter charge countermeasure means must also be mounted at four locations. However, in the present invention, counter charge countermeasures are taken in a device with a small number of output types, and the number of mounting locations is reduced, resulting in an effect in cost.

1 is a schematic configuration diagram of a high-voltage power supply device according to Embodiment 1 of the present invention. It is a schematic block diagram of the high voltage power supply device which concerns on Example 2 of this invention. 3 is a flowchart illustrating a control procedure of the first and second embodiments. It is a schematic block diagram of the high voltage power supply device which concerns on Example 3 of this invention which applied the high voltage power supply device to the image forming apparatus. It is a circuit diagram for demonstrating the principle of Example 4 which comprised the means to flow reverse charge with a switch. It is a flowchart which shows the operation | movement procedure of FIG. FIG. 10 is a block diagram illustrating a main configuration of Example 5 in which a high-voltage power supply device is applied to a tandem type color image forming apparatus. 1 is a diagram illustrating a schematic configuration of an image forming apparatus that has been conventionally performed. It is a block diagram which shows the electrical schematic structure of the image forming apparatus conventionally implemented. It is a figure for demonstrating the connection relation of the conventional high voltage power supply and the main structures of an image forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Charging apparatus 3 Developing apparatus 5 Intermediate transfer body 6 Primary transfer apparatus 8 Secondary transfer apparatus 17 High voltage power supply 21 Load 22 First path part 23 Second path part 24 Third path part 25 Diode 32 Switch

Claims (6)

In the high-voltage power supply device that applies a high-voltage power supply to multiple loads,
An element having a rectifying action is connected between a high-voltage output capable of outputting only a single polarity and a load connected to the high-voltage output in a direction in which a reverse charge applied to the load flows to the ground. High voltage power supply device. The device is a high-voltage power supply device according to claim 1 Symbol mounting, characterized in that a diode. In the high-voltage power supply device that applies a high-voltage power supply to multiple loads,
A residual load path is formed between the plurality of loads, in which residual charge generated in one load is applied to another load, and the high voltage among the plurality of loads existing in the residual load path is formed. When there are multiple loads to which only a single polarity is applied from the power source, an element having a rectifying action is connected to the load located upstream of the residual load path in such a direction that the reverse charge applied to the load flows to the ground. Tei Rukoto high-voltage power apparatus it said. The image forming apparatus you characterized by comprising a high-voltage power supply device according to any one of claims 1 to 3. The high-voltage power supply device includes: a photosensitive member that carries a latent image; a charging unit that charges the photosensitive member; a developing unit that develops the latent image on the photosensitive member; and a developer on the developed photosensitive member. a primary transfer means for transferring an image to an intermediate transfer member of claim 4, wherein the supplying the voltage to at least one of said intermediate transfer member a secondary transfer means for transferring a recording material an image of Image forming apparatus. The image forming apparatus is a color image forming apparatus, the high-voltage power supply apparatus is an image forming apparatus according to claim 5, characterized in that it is connected to the primary transfer unit.

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