JP2006078934A - Discharger and image forming apparatus equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a discharge current from leaking from a high-voltage terminal to a metallic side plate at its vicinity. <P>SOLUTION: The discharger 30 is equipped with a high-voltage terminal base 31 which is fitted to the metallic side plate 25 and has a coil spring 46 and a main charger 32 which is attachable to and detachable from the high-voltage terminal base 31 and has a charge terminal 41 and while the main charger 32 is mounted on the high-voltage terminal base 31 to bring the coil spring 46 and charge terminal 41 into contact with each other, a high voltage is applied from the coil spring 46 to the side of the charge terminal 41. Then a leak preventing part 50 which prevents a current generated by discharge between the coil spring 46 and side plate 52 from leaking is provided to the high-voltage terminal 31 on the side of the main charger 32. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge device and an image forming apparatus provided with the discharge device, and more specifically, a discharge device that uniformly applies a charge to a photosensitive drum, and electrophotographic image formation such as a copying machine and a facsimile equipped with the discharge device. Relates to the device.

  2. Description of the Related Art Conventionally, in an image forming apparatus, a discharge device (charging device) that uniformly applies a negative (or positive) charge to a photosensitive drum is provided around the photosensitive drum. In principle, when a high voltage is applied to the discharge wire, the air near the discharge wire is ionized and the ions move toward the photosensitive drum (this is called corona discharge). This discharge causes ions (charges) to adhere to the photosensitive drum.

  As such a discharge device, for example, as shown in FIG. 12, a resin-made high-voltage terminal block 31 having a coil spring (high-voltage terminal) 46, and the high-voltage terminal block 31 can be attached to and detached from the charge terminal 41 (and not shown). The high-voltage terminal block 31 is attached to a metal side plate 25 of the image forming apparatus main body. Then, by attaching (connecting) the main charger 32 to the high voltage terminal block 31 and bringing the charge terminal 41 into contact with the coil spring 46, a high voltage current flows from the high voltage power source (not shown) to the charge terminal 41 side via the coil spring 46. It is like that.

  In addition, as another discharge device, a main charger provided with a discharge wire stretched in a casing extending in the width direction of the recording paper, and a conveyance guide fitted into the opening end surface of the casing, the discharge wire from the power supply terminal When a high voltage is applied and this discharge device is used as a paper separation mechanism of an image forming apparatus, discharge paper flows and a discharge wire burns out when a paper having a low resistance value passes over the conveyance guide. For this reason, it is known that the edge of the opening end face of the casing is covered with a covering piece to prevent discharge from the edge (see Patent Document 1).

JP 2001-196150 A (page 4, FIG. 2)

  However, in the discharge device shown in FIG. 12, the spatial distance L (see the broken line in FIG. 13) between the coil spring 46 and the side plate 25 of the image forming apparatus main body is not sufficient due to structural problems or poor setting of the main charger 32. As shown in FIG. 13, when the main charger 32 is detached from the high-voltage terminal block 31 during maintenance or the like, a discharge current flows from the tip of the coil spring 46 to the side plate 25, and the high-voltage terminal block 31 in the middle There was a possibility that the front end side 42A of the resin housing 42 would burn out.

  Further, in the discharge device of Patent Document 1, the power supply terminal for applying a high voltage and the main charger are not detachable. For example, when maintaining the discharge device used in the image forming apparatus, the maintenance worker is required to maintain the main charger. However, there is a problem that workability is poor because the work must be performed with the high-voltage power source connected to the power source.

  In order to solve such a problem, an object of the present invention is to provide a discharge device in which a discharge current does not leak from a high voltage terminal to a metal mounting plate in the vicinity thereof, and an image forming apparatus including the discharge device. .

  The discharge device of the invention of claim 1 includes a high voltage terminal block having a high voltage terminal attached to a metal mounting plate, and a main charger having a charge terminal that is detachably attached to the high voltage terminal block, A high voltage is applied from the high-voltage terminal to the charge terminal in a state where the main charger is mounted and the high-voltage terminal and the charge terminal are in contact with each other. This discharge device is characterized in that a leak prevention portion for preventing current leakage due to discharge between the high voltage terminal and the mounting plate is provided on the main charger side of the high voltage terminal block.

  According to a second aspect of the present invention, in the discharge device according to the first aspect, the leak preventing portion is a rib portion of the high-voltage terminal block that houses the high-voltage terminal, and a tip portion of the rib portion on the main charger side is arranged. The high-voltage terminal is protruded from the front end portion on the main charger side.

  According to a third aspect of the present invention, in the discharge device according to the first or second aspect, the leak prevention portion is a tip portion on the main charger side of the high-voltage terminal, and the tip portion is bent toward the base end side. It is characterized by.

  According to a fourth aspect of the present invention, in the discharge device according to any one of the first to third aspects, the high-voltage terminal is a coil spring, and the distal end of the coil spring on the main charger side is bent toward the base end. And

  According to a fifth aspect of the present invention, in the discharge device according to any one of the first to third aspects, the high-voltage terminal is a leaf spring, and a tip portion of the leaf spring on the main charger side is hemming bent. And

  A sixth aspect of the invention is characterized by comprising the discharge device according to any one of the first to fifth aspects and an image forming unit that uniformly charges the surface of the photosensitive drum by the discharge device.

  According to the first aspect of the present invention, in a discharge device comprising a high voltage terminal block attached to a metal mounting plate and a main charger detachable from the high voltage terminal block, leakage prevention is provided on the main charger side of the high voltage terminal block. Since the portion is provided, current leakage due to discharge between the high-voltage terminal and the mounting plate can be prevented, and burning of the resin member or the like existing in the middle can be prevented.

  In the invention of claim 2, since the leading end portion of the rib portion protrudes to the main charger side from the leading end portion of the high-voltage terminal, the creepage distance and the spatial distance between the high-voltage terminal and the mounting plate are increased, and the high-voltage terminal and the mounting portion are attached. Current leakage due to discharge between the plates can be prevented.

  In the third aspect of the invention, since the distal end portion of the high voltage terminal is bent to the proximal end side, the spatial distance between the distal end portion of the high voltage terminal and the mounting plate is increased, and current leakage due to discharge between the high voltage terminal and the mounting plate is prevented. Can be prevented.

  In the invention of claim 4, since the distal end portion of the coil spring as the high-voltage terminal is bent toward the proximal end side, the spatial distance between the distal end portion of the coil spring and the mounting plate is increased, and the discharge between the distal end portion of the coil spring and the mounting plate is performed. The leakage of current due to can be prevented.

  In the invention of claim 5, since the tip of the leaf spring as the high-voltage terminal is hemming bent, the spatial distance between the tip of the leaf spring and the mounting plate becomes long, and between the tip of the leaf spring and the mounting plate. Current leakage due to discharge can be prevented.

  The invention according to claim 6 is provided with a discharge device and an image forming unit that uniformly charges the surface of the photosensitive drum by the discharge device, so that the current in the discharge device can be reduced during maintenance of the device body. Leakage can be prevented and workability can be improved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Schematic configuration of image forming apparatus]
FIG. 1 is a schematic configuration diagram of an image forming apparatus to which the present invention is applied as viewed from the front side (user).

  As shown in FIG. 1, an image forming apparatus 1 according to the present embodiment includes a box-shaped image forming apparatus main body 2 and, in the image forming apparatus main body 2, a sheet feeding and conveying operation in an approximately sequential order from below. A unit 3, an image forming unit 4, a fixing unit 5, and a paper discharge unit 6 are provided.

  In the paper feeding / conveying unit 3, a manual paper feeding device 7, a paper feeding cassette 8 for automatic paper feeding, a paper feeding roller 10, a conveying roller 11, and a registration roller 12 are disposed. In the paper feeding / conveying section 3, the recording material (sheet-like copy paper, plastic film, etc.) fed from the paper feeding device 7 or the recording material S fed from the paper feeding cassette 8 by the paper feeding roller 10. Is conveyed upward by the conveying roller 11, and skew is corrected by the registration roller 12, and at a predetermined timing (timing synchronized with a toner image formed on a photosensitive drum described later) will be described next. It is supplied to the image forming unit 4.

  The image forming unit 4 includes a photosensitive drum 13 that is rotationally driven in the direction of an arrow (clockwise in FIG. 1), a discharge device (charging device) 30 and an exposure device 15 that are arranged substantially in the order along the rotational direction. A developing device 16, a transfer roller 17, and a cleaning device 18 are disposed. The image forming unit 4 forms a toner image on the recording material S supplied from the paper feeding / conveying unit 3 described above.

  That is, the photosensitive drum 13 uniformly charged by the discharge device 30 is exposed according to the image information by the exposure device 15 to form an electrostatic latent image. The electrostatic latent image is developed as a toner image with toner attached thereto by the developing device 16. The toner image formed on the photosensitive drum 13 is transferred by the transfer roller 17 to the recording material S supplied from the paper feeding / conveying unit 3 described above.

  The toner remaining on the photosensitive drum 13 after the toner image transfer (transfer residual toner) is removed by the cleaning device 18. The recording material S having the toner image fixed on the surface thereof is conveyed to a fixing unit 5 described below.

  The fixing unit 5 includes a fixing roller 21 including a heater 20 and a pressure roller 22 pressed against the fixing roller 21. In the fixing unit 5, the recording material S conveyed from the image forming unit 4, that is, the recording material S carrying an unfixed toner image on the surface is nipped and conveyed by the nip portion between both rollers. At this time, the recording material S is heated and pressurized at the nip portion, and the toner image is fixed on the surface.

The paper discharge unit 6 is provided with a paper discharge roller 23 and a paper discharge tray 24. The recording material S after the toner image is fixed is discharged onto a paper discharge tray 24 by a paper discharge roller 23.
[Configuration of discharge device]
As shown in FIGS. 2 and 3, the discharge device 30 includes a high voltage terminal block 31 having a coil spring (compression) 46 as a high voltage terminal, and a main charger having a charge terminal 41 that can be attached to and detached from the high voltage terminal block 31. 32. The coil spring 46 and the charge terminal 41 are arranged on the same straight line. When the main charger 32 is attached to the high voltage terminal block 31 (see FIG. 2), the coil spring 46 and the charge terminal 41 are in contact with each other. .

  The high-voltage terminal block 31 has an insulating housing portion 42 made of synthetic resin and a mounting portion 43 for fixing the housing portion 42. The high-voltage terminal block 31 is connected to the image forming apparatus main body 2 via the mounting portion 43. The metal side plate (attachment plate) 25 is attached. The high-voltage terminal block 31 has a leak prevention unit 50 on the main charger 32 side for preventing current leakage due to discharge between the coil spring 46 and the side plate 25.

  The high-voltage terminal block 31 has concentric inner rib portions 42A and outer rib portions 42B on the main charger 32 side, and the coil spring 46 is provided in the center. The coil spring 46 is accommodated in an inner rib portion 42A serving as a leak prevention portion 50. The inner rib portion 42A projects the tip end portion on the main charger 32 side from the tip end portion on the main charger 32 side of the coil spring 46. I am letting.

  Further, the distal end portion of the coil spring 46 as the leak preventing portion 50 is bent toward the base end side (the conductive portion 47 side). The base end side of the coil spring 46 is connected to the conductive portion 47 in the housing portion 42. When the main charger 32 is mounted (connected) to the high-voltage terminal block 31, the coil spring 46 is elastically deformed so that the coil spring 46 and the charge terminal 41 are reliably in contact with each other.

  As described above, the inner rib portion 42A of the high-voltage terminal block 31 protrudes toward the main charger 32 from the distal end portion of the coil spring 46, and the distal end portion of the coil spring 46 is bent toward the proximal end side. It is possible to increase the creepage distance and the spatial distance between the front end portion and the side plate 25. As a result, when the main charger 32 is detached from the high-voltage terminal block 31 during maintenance or the like, the discharge between the distal end portion of the coil spring 46 and the side plate 25 is prevented, and the inner rib portion 42A is prevented from burning. Can be prevented.

  In addition, the creepage distance mentioned above means the sum total of the distance from the front-end | tip part (A part of FIG. 7) of the coil spring 46 to the side plate 25 through the front end side surface of the inner side rib part 42A in FIG. In addition, the spatial distance refers to a distance connecting the space from the tip end portion (B portion in FIG. 7) of the coil spring 46 to the side plate 25.

  As shown in FIGS. 5 and 6, the main charger 32 has a shield case 33 having a U-shaped cross section elongated in a direction (width direction) perpendicular to the feeding direction of the recording material S, and both end portions in the longitudinal direction. It has end blocks 35 and 36 made of insulating synthetic resin or the like (see FIG. 5), and the shield case 33 is made of a conductive metal plate or the like, so that the discharge from the discharge wire 34 is not concentrated in part. I am doing so. The main charger 32 is attached to a frame (not shown) of the image forming apparatus main body 2 via attachment portions 48 and 50 (see FIG. 5).

  Further, attachment plates 37 and 38 to which both end sides of the discharge wire 34 are connected are attached to the end blocks 35 and 36. The mounting plates 37, 38 have hook portions 37 A, 38 A, and a discharge wire 34 is connected to one hook portion 37 A in the longitudinal direction of the shield case 33 via a spring 40.

Furthermore, a charge terminal 41 is integrally connected to one mounting plate 37 so as to protrude from the shield case 33 in the longitudinal direction (see FIG. 6). A high voltage (4 to 8 KV) is applied to the discharge wire 34 from the high voltage power supply via the charge terminal 41. The charge terminal 41 is covered with a cover portion 45 made of an insulating synthetic resin or the like, and a housing of the high-voltage terminal block 31 is provided at an end portion of the cover portion 45 opposite to the mounting plate 37 via a step portion 45A. A fitting portion 45 </ b> B for connecting to the portion 42 is provided.
[Shape of the tip of the high-voltage terminal]
Next, for reasons such as structure, a creepage distance and a spatial distance between the coil spring 46 and the side plate 25 may not be sufficiently secured. In this case, it is possible to prevent leakage of current due to discharge by changing the tip shape of the coil spring 46 without changing the free length of the coil spring 46.

  7 to 11 show the tip shapes of a coil spring 46, a bar spring 52, and a leaf spring 51 as high-voltage terminals.

  When the shape of the tip of the coil spring 46 is cut at an acute angle like a needle, it is easy to discharge from the tip to the side plate 25, and the tip of the normal spring is cut so that the end is cut off. It becomes an acute angle. For this reason, the creeping distance and the spatial distance between the distal end portion of the coil spring 46 and the side plate 25 to be leaked are maintained to a certain extent, and the distal end portion of the coil spring 46 is bent by bending the distal end portion of the coil spring 46 to the proximal end side. As hemming bending, leakage of the discharge current can be prevented.

  7A and 7B, the distal end portion 46A of the coil spring 46 is bent horizontally toward the coil center side, and further bent at a right angle from the coil center portion toward the proximal end side. According to the inventor's experiment, it was confirmed that the amount of bending of the distal end portion 46A toward the proximal end side does not leak as the length increases. This is presumably because the spatial distance from the spring tip to the side plate 25 becomes longer.

  8A and 8B, the distal end portion 46A of the coil spring 46 is bent at an acute angle toward the proximal end side. As with the case of FIG. 7, it was confirmed that the amount of bending of the distal end portion 46A toward the proximal end side did not leak as the length increased.

  FIG. 9 shows the appearance of a bar spring 52 used in place of the coil spring 46. The bar spring 52 is handled as a kind of the leaf spring 51. This bar spring 52 shows an embodiment (hemming bending) in which the distal end portion 52A is bent toward the proximal end side. According to this embodiment, since the spatial distance from the distal end portion 52A to the side plate 25 becomes longer, it is possible to prevent discharge current leakage.

  FIG. 10 shows the appearance of a leaf spring 51 used in place of the coil spring 46. The leaf spring 51 is used with its fixed piece 51A connected to the conductive portion 47 of FIG. 2 and the free piece 51B in contact with the charge terminal 41. Also in this case, when the main charger 32 is connected to the high-voltage terminal block 31, the free piece 51B is elastically deformed, and the leaf spring 51 and the charge terminal 41 are reliably in contact with each other.

  FIG. 11 shows an embodiment (hemming bending) in which the end 51C of the free piece 51B of the leaf spring 51 is bent inward. By doing so, the spatial distance from the end 51C to the side plate 25 is increased.

  As described above, discharge current leakage can be prevented by projecting the inner rib portion 42A of the high-voltage terminal block 31 toward the main charger 32 and bending the distal end portion of the coil spring 46 toward the proximal end side. . However, the present invention is not limited to this, and for example, even if only the inner rib portion 42A protrudes toward the main charger 32 or only the distal end portion such as the coil spring 46 is bent toward the proximal end side, discharge current leakage can be prevented. .

  The present invention can be used in the field of image forming apparatuses such as copying machines, facsimile machines, printers, or multifunction machines having both functions.

1 is a schematic configuration diagram of an image forming apparatus viewed from the front side. It is a sectional front view of a discharge device, and is a figure which shows the state which mounted | wore the high voltage | pressure terminal block with the main charger. It is a disassembled perspective view of the discharge device which consists of a high voltage terminal block and a main charger. It is a sectional front view of a discharge device, and is a figure showing the state where a main charger was detached from a high voltage terminal block. It is an external view of a main charger. It is a section front view of a main charger. (A) is a front view of a coil spring, (b) is the top view. (A) is a front view of a coil spring, (b) is the top view. It is a figure which shows the external appearance of a needle-shaped terminal. It is a figure which shows the external appearance of a leaf | plate spring. It is a figure which shows the external appearance of a leaf | plate spring. It is a sectional front view of a discharge device, and is a figure which shows the prior art example of the state which attached the main charger to the high voltage | pressure terminal block. It is a sectional front view of a discharge device, and is a figure which shows the prior art example of the state which removed the main charger from the high voltage | pressure terminal block.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2 ... Image forming apparatus main body, 4 ... Image forming part, 13 ... Photosensitive drum, 25 ... Side plate (mounting plate), 30 ... Discharge device, 31 ... High voltage terminal block , 32 ... main charger, 34 ... discharge wire, 42 ... housing part, 42A ... inner rib part, 42B ... outer rib part, 46 ... coil spring (high voltage terminal), 50 ... leak prevention part, 51 …… Plate spring (high voltage terminal), 52 …… Bar spring (high voltage terminal)

Claims (6)

A high-voltage terminal block attached to a metal mounting plate and having a high-voltage terminal; and a main charger having a charge terminal that is detachably attached to the high-voltage terminal block, and the high-voltage terminal block is attached to the main charger. In a discharge device that applies a high voltage from the high voltage terminal to the charge terminal in a state where the charge terminal is in contact with the charge terminal,
Provided on the main charger side of the high-voltage terminal block is a leak prevention unit that prevents current leakage due to discharge between the high-voltage terminal and the mounting plate.
A discharge device characterized by that. The leak prevention part is a rib part of the high-voltage terminal block that houses the high-voltage terminal,
The leading end of the rib portion on the main charger side is protruded from the leading end portion of the high-voltage terminal on the main charger side,
The discharge device according to claim 1. The leak prevention portion is a tip portion on the main charger side of the high-voltage terminal, and the tip portion is bent toward the base end side.
The discharge device according to claim 1 or 2, characterized in that. The high-voltage terminal is a coil spring, and the distal end portion on the main charger side of the coil spring is bent to the proximal end side,
The discharge device according to claim 1, wherein the discharge device is provided. The high-voltage terminal is a leaf spring, and the tip of the leaf spring on the main charger side is hemming bent.
The discharge device according to claim 1, wherein the discharge device is provided. The discharge device according to claim 1, and an image forming unit that uniformly charges the surface of the photosensitive drum by the discharge device.
An image forming apparatus.

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