JP2005309278A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus where the operation stability of a circuit is made compatible with the prevention of adverse influence of noise by efficiently arranging the high voltage base board unit of an intermediate transfer belt unit or a transfer belt unit. <P>SOLUTION: The image forming apparatus comprising a plurality of image forming parts and a plurality of transfer parts has a transfer unit where an endless belt body is stretched and provided between a plurality of rollers and a plurality of high voltage base board units generating high voltage applied to the plurality of transfer parts respectively. The plurality of high voltage base board units are arranged inside the transfer units and also arranged in a direction where they are reversed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus employing an electrostatic recording system, an electrophotographic recording system, or the like, and more particularly to an image forming apparatus having a belt body that carries an image or a recording material.

  Conventionally, various types of color image forming apparatuses have been proposed. One of them is provided with an image forming unit for each color developer, and the image forming unit is well known for a photosensitive drum as an image carrier. In this image forming process, a visible image for each color is formed, and these visible images are sequentially transferred onto a so-called intermediate transfer belt, which is endlessly circulated, and further transferred to a sheet supplied from the outside and then fixed. Thus, there is an electrophotographic color image forming apparatus that obtains a color image.

  In such an intermediate transfer type image forming apparatus, the toner image on the drum is transferred onto the intermediate transfer belt by applying a high pressure to the transfer portion, and therefore a high pressure substrate unit for generating a high pressure is provided. Yes. One high-voltage board unit is provided for each color, and four high-voltage board units are provided when four color images are superimposed.

  On the other hand, in order to superimpose four color images without causing color misregistration, it is necessary to drive the intermediate transfer belt with high accuracy. Therefore, an encoder for detecting the phase of the driving roller for conveying and driving the intermediate transfer belt is provided on the driving roller, and the rotation of the driving roller is controlled with high accuracy based on the signal of this encoder.

  Further, during the operation of the intermediate transfer type image forming apparatus, these intermediate transfer belts are moved from a predetermined position due to roller misalignment caused by distortion of the apparatus main body, a difference in peripheral length of the intermediate transfer belt itself, or the like. There is a problem that a so-called belt deviation occurs due to meandering. As a means for correcting the belt deviation, for example, a method of detecting the amount of belt deviation by detecting the position of the belt end and correcting the alignment of one of the rollers based on this information is adopted. . According to this method, the mechanical stress is less and the life of the belt can be reduced compared to the means for regulating the rib-shaped rubber part affixed to the belt edge or regulating the belt edge by directly abutting against the flange or the like. It can be greatly improved.

Japanese Patent Laid-Open No. 05-019553

  However, in such a high-voltage substrate unit of the intermediate transfer system, it is necessary to dispose it as close to the transfer unit as possible in order to reduce the influence of noise generated by high pressure. Therefore, the high-voltage substrate unit is disposed inside the intermediate transfer unit so that the high-voltage lead wire leading to the transfer portion can be shortened. For example, conventionally, as shown in FIG. 5, the high-voltage board units 171a to 171d are arranged beside the primary transfer rollers 35a to 35d, respectively.

  On the other hand, high-voltage high-power output and high-speed operation are required in response to image quality improvement and high productivity, and various high-pressure controls are required. For this reason, the size of the high voltage substrate is also increased, and the risk to noise is also increasing. Furthermore, in the rectangular shape as shown in the high voltage board units 171a to 171d, the width of the short side is narrow, and it is difficult to arrange the circuit pattern efficiently.

  Furthermore, very weak analog signals are emitted from the encoder 97 that detects the phase of the driving roller and the edge sensor 91 that detects the position of the belt end, and noise has an adverse effect on these signals. It is necessary to be careful not to. For this reason, it is desirable to arrange a control board for processing these signals inside the intermediate transfer unit to shorten the signal line. However, in the conventional example shown in FIG. 5, it is difficult to secure a space for this purpose. is there.

  In addition, these problems are not limited to the intermediate transfer type image forming apparatus, but may be applied to a so-called direct transfer type image forming apparatus that adsorbs and conveys paper onto a transfer belt and sequentially transfers an image. It is the same.

  The present invention has been made in view of the above problems, and the object of the present invention is to efficiently arrange the intermediate transfer belt unit or the high-voltage substrate unit of the transfer belt unit, and to prevent the adverse effects of noise due to circuit operation stability. An object is to provide a compatible image forming apparatus.

  In order to achieve the above object, an invention according to claim 1 is an image forming apparatus including a plurality of image forming units and a plurality of transfer units, and a transfer unit that stretches an endless belt body between a plurality of rollers; A plurality of high-voltage substrate units that generate a high voltage to be applied to each of the plurality of transfer portions, and the plurality of high-voltage substrate units are disposed inside the transfer unit and each high-voltage substrate unit is in an inverted direction. It is arranged.

  According to a second aspect of the present invention, in the first aspect of the present invention, the high-voltage substrate has a substantially square shape, and the primary system and the secondary system are arranged on opposite sides.

  According to a third aspect of the present invention, in the first aspect of the present invention, the transfer unit has four transfer portions, and two high-voltage substrate units are provided between the first and second transfer portions. The four high-voltage substrate units are arranged in an inverted direction between the four transfer portions.

  According to a fourth aspect of the present invention, in the third aspect of the present invention, the transfer unit includes: a detection unit that detects a phase of a driving roller that conveys and drives the belt body; and a detection unit that detects an edge position of the belt body. A control board having at least one of them and processing a detection signal by the detection means is provided between the second and third transfer portions.

  According to a fifth aspect of the present invention, in the fourth aspect of the present invention, a cross member forming a casing of the transfer unit is provided in the vicinity of the second and third transfer portions.

  According to the first aspect of the present invention, the plurality of high-voltage board units can be shortened by arranging the plurality of high-voltage board units inside the transfer unit, noise generation can be reduced, and the plurality of high-voltage board units can be reduced. By arranging in the direction in which is reversed, even if the high-voltage board unit is enlarged, it can be arranged efficiently, and the primary line and the secondary line do not overlap and malfunction due to noise can be prevented.

  According to the second aspect of the present invention, the circuit pattern can be efficiently arranged by making the high-voltage substrate substantially square, and the primary system and the secondary system are arranged on opposite sides. By inverting the arrangement inside the unit, high pressure can be efficiently supplied to the transfer section.

  According to the third aspect of the present invention, the high-voltage lead wire can be arranged in the shortest path with respect to the four transfer portions, and the overlap with the primary line can be prevented, so that stable operation can be ensured and the transfer can be performed. The space in the unit can be used efficiently.

  According to the fourth aspect of the present invention, an analog signal line through which only a weak current flows can be efficiently introduced into a control board provided inside the transfer unit, and a stable control operation can be guaranteed.

  According to invention of Claim 5, the shielding effect from a high voltage | pressure system can be provided with respect to a control board.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  First, an embodiment of an image forming apparatus according to the present invention will be described in detail with reference to FIGS.

  FIG. 1 is a cross-sectional view of a main part of a conventional image forming apparatus. The illustrated image forming apparatus is a color image forming apparatus in which a plurality of image forming units are arranged in parallel.

  The illustrated color image forming apparatus is provided with an image output unit 1P. The image output unit 1P is roughly divided into an image forming unit 10 (four stations a, b, c, and d arranged in parallel. The configuration is the same), and includes a paper feeding unit 20, an intermediate transfer unit 30, a fixing unit 40, and a control unit (not shown).

  Here, each unit will be described in detail.

  In the image forming unit 10, photosensitive drums 11a, 11b, 11c, and 11d as image carriers that are rotationally driven in the direction of the arrow shown in the drawing are pivotally supported at the center and face the outer peripheral surfaces of the photosensitive drums 11a to 11d. The primary chargers 12a, 12b, 12c and 12d, the optical systems 13a, 13b, 13c and 13d, and the developing devices 14a, 14b, 14c and 14d are arranged in the rotation direction.

  Thus, the primary chargers 12a to 12d give a uniform charge amount to the surfaces of the photosensitive drums 11a to 11d, and then the light beams such as laser beams modulated according to the recording image signal by the optical systems 13a to 13d. The photosensitive drums 11a to 11d are exposed to form electrostatic latent images on the photosensitive drums 11a to 11d. Then, each electrostatic latent image is visualized as a toner image by the developing devices 14a to 14d respectively containing developers (toners) of four colors of yellow, cyan, magenta, and black. Note that, on the downstream side of the image primary transfer areas Ta, Tb, Tc, and Td where the visualized toner image is transferred to the intermediate transfer belt 31, the toner image is not transferred to the recording material P and remains on the photosensitive drums 11a to 11d. The toner is scraped off by the cleaning devices 15a, 15b, 15c, and 15d, and the surfaces of the photosensitive drums 11a to 11d are cleaned.

  Through the above-described process, image formation with each toner is sequentially performed.

  On the other hand, the paper feed unit 20 includes cassettes 21a and 21b and a manual feed tray 27 for storing the recording material P, and pickup rollers 22a and 22b for feeding the recording material P one by one in the cassettes 21a and 21b or from the manual feed tray 27. , 26, a pair of paper feed rollers 23 and a paper feed guide 24 for conveying the recording material P fed from the pickup rollers 22a, 22b, 26 to the registration rollers 25a, 25b, and the timing of image formation in the image forming unit 10. In addition, it is composed of registration rollers 25a and 25b for sending the recording material P to the secondary transfer region Te.

The intermediate transfer unit 30 has an intermediate transfer belt 31 as an intermediate transfer member. The intermediate transfer belt 31 faces a driving roller 32 and a registration mark detection sensor 60 for transmitting a driving force thereto. A backup roller 62, a tension roller 33 that applies an appropriate tension to the intermediate transfer belt 31 by a biasing force of a spring (not shown), and a secondary transfer that faces the secondary transfer region Te across the intermediate transfer belt 31. It is wound around the inner roller 34. For example, PI [polyimide] or PVdF [polyvinylidene fluoride] is selected as the material of the intermediate transfer belt 31.

  A primary transfer plane A is formed between the drive roller 32 and the backup roller 62. The drive roller 32 is coated with rubber (urethane or chloroprene) having a thickness of several millimeters on the surface of the metal roller. Slip is prevented. The drive roller 32 is rotationally driven by a pulse motor (not shown).

  The alignment of the tension roller 33 urged by a pressure mechanism (not shown) can be adjusted, and the meandering of the intermediate transfer belt 31 can be corrected.

  Primary transfer devices 35 a to 35 d are arranged behind the intermediate transfer belt 31 in primary transfer regions Ta to Td where the photosensitive drums 11 a to 11 d and the intermediate transfer belt 31 face each other. A secondary transfer device 36 is arranged to face the secondary transfer inner roller 34 to form a secondary transfer region Te.

  A cleaning device 50 for cleaning the image forming surface of the intermediate transfer belt 31 is disposed downstream of the secondary transfer region Te on the intermediate transfer belt 31, and the cleaning device 50 removes the cleaner blade 51 and waste toner. The waste toner box 52 is housed. As the material of the cleaner blade 51, polyurethane rubber or the like is used.

  The fixing unit 40 includes a fixing roller 41a having a heat source such as a halogen heater therein, a pressure roller 41b that is pressed against the fixing roller 41a (the pressure roller 41b may also be provided with a heat source), and fixing. A guide 43 for guiding the recording material P to the nip portion between the roller 41a and the pressure roller 41b, and an inner discharge roller 44 for further guiding the recording material P discharged from the fixing roller 41a and the pressure roller 41b to the outside of the apparatus. The outer paper discharge roller 45 and the like.

  The control unit includes a control board 70 for controlling the operation of the mechanism in each unit, a motor drive board (not shown), and the like.

  Next, the operation of the color image forming apparatus will be described.

  When the image forming operation start signal is issued, first, the recording material P is sent out one by one from the cassette 21a by the pickup roller 22a. The recording material P is guided between the paper feed guides 24 by the paper feed roller pair 23 and conveyed to the registration rollers 25a and 25b. At this time, the registration rollers 25a and 25b are stopped, and the leading edge of the recording material P comes into contact with the nip portion. Thereafter, the registration rollers 25a and 25b start rotating in accordance with the timing at which the image forming unit 10 starts image formation. The rotation timing of the registration rollers 25a and 25b is set so that the recording material P and the toner image primary-transferred onto the intermediate transfer belt 31 from the image forming unit 10 exactly coincide with each other in the secondary transfer region Te. ing.

  On the other hand, when the image forming operation start signal is issued, the image forming unit 10 causes the toner image formed on the photosensitive drum 11d, which is the most upstream in the rotation direction of the intermediate transfer belt 31 through the above-described process, to have a high voltage. Is primarily transferred to the intermediate transfer belt 31 in the primary transfer region Td by the primary transfer roller 35d to which is applied. Then, the toner image primarily transferred onto the intermediate transfer belt 31 is transported to the next primary transfer region Tc, where image formation is performed between the image forming units 10 with a delay of the time during which the toner image is transported. Therefore, the next toner image is transferred by aligning the resist on the previous image. Thereafter, the same process is repeated, and eventually the four color toner images are primarily transferred onto the intermediate transfer belt 31.

  Thereafter, when the recording material P enters the secondary transfer region Te and contacts the intermediate transfer belt 31, a high voltage is applied to the secondary transfer device 36 in accordance with the passing timing of the recording material P. Then, the four color toner images formed on the intermediate transfer belt 31 by the above-described process are transferred to the surface of the recording material P, and the recording material P to which the toner images have been transferred is fixed by the conveyance guide 43 to the fixing roller of the fixing unit 40. It is accurately guided to the nip portion between 41a and the pressure roller 41b. Then, the toner image is fixed on the surface of the recording material P by the heat of the roller pair 41a and 41b of the fixing unit 40 and the pressure of the nip, and the recording material P on which the toner image is fixed is the inner discharge roller 44 and the outer discharge roller. It is conveyed by 45 and discharged out of the machine.

  Next, a characteristic configuration of the embodiment will be described.

  2 is a cross-sectional view of the intermediate transfer unit, FIG. 3 is a top view, and FIG. 4 is a top view showing details of the high-voltage substrate unit.

  The housing of the intermediate transfer unit 30 includes a front side plate 68, a rear side plate 69, and a cross member 65 passed between them. Primary transfer rollers 35a to 35d are arranged on the cross member 65, and are supported by bearing holders 81a to 81d and 82a to 82d. The bearing holders 82a to 82a are made of a conductive resin, and a transfer current flows through the primary transfer rollers 35a to 35d by applying a transfer high voltage thereto.

  In the space between the primary transfer rollers 35d and 35c, high-voltage board units 71d and 71c having the same shape are arranged, and each is in an inverted direction. Further, high-pressure board units 71b and 71a are similarly arranged in the space between the primary transfer rollers 35b and 35a, and each is in an inverted direction. The high voltage substrate 71 has a substantially square shape, and a primary signal line input unit 103 and a secondary high voltage output unit 101 are provided on the opposite side.

  A primary signal line 104 is connected to the primary signal line input unit 103, and a high voltage lead wire 102 is output from the secondary high voltage output unit 101. These primary lines and secondary lines are arranged without overlapping, and malfunction due to noise is prevented. The secondary lines are connected to the bearing holders 82d to 82a through the shortest paths. Further, a control board 72 is disposed in the space between the primary transfer rollers 35c and 35b.

  On the other hand, an edge sensor 91 is provided at the edge portion of the intermediate transfer belt 31 to detect the position of the edge portion. An output signal from the edge sensor 91 is sent to the control board 72 through the lead wire 111. When the intermediate transfer belt 31 meanders and the edge position changes, the steering motor 92 is driven to change the alignment of the tension roller 33 to correct the edge position. Further, a code wheel 96 is provided on the shaft of the driving roller 32, and this phase can be detected by the encoder 97. An output signal from the encoder 97 is sent to the control board 72 through the lead wire 114. When the code wheel 96 has a rotational fluctuation, the speed of the drive motor 98 is adjusted to control the drive roller 32 to rotate at a predetermined speed.

  A weak electrical signal flows through these lead wires 111 and 114, and the control board 72 is disposed in the vicinity of the edge sensor 91 and the encoder 97, that is, in the intermediate transfer unit, thereby deteriorating these signals. Can be prevented and the stability of the control is guaranteed.

  Further, cross members 66 and 67 are arranged in the vicinity of the primary transfer rollers 35 c and 35 b to provide a shielding effect for the control board 72. Thereby, the stability of control is more reliably ensured.

  In the embodiment described above, the intermediate transfer unit has been described as an example, but it goes without saying that the same configuration can be applied to a direct transfer type transfer unit.

1 is a cross-sectional view illustrating an image forming apparatus according to an embodiment of the present invention. It is sectional drawing explaining the transfer unit in embodiment of this invention. It is a top view explaining the transfer unit in the embodiment of the present invention. It is a top view explaining the high voltage | pressure board | substrate unit in embodiment of this invention. It is a top view explaining the transfer unit of a prior art example.

Explanation of symbols

31 Intermediate transfer belt 72 Control board 82 High pressure board unit

Claims (5)

In an image forming apparatus comprising a plurality of image forming units and a plurality of transfer units,
A transfer unit that stretches an endless belt between a plurality of rollers; and a plurality of high-pressure substrate units that generate a high pressure to be applied to each of the plurality of transfer units, wherein the plurality of high-pressure substrate units An image forming apparatus, wherein each high-voltage board unit is arranged in an inverted direction while being arranged inside the unit.   The image forming apparatus according to claim 1, wherein the high-voltage substrate has a substantially square shape, and a primary system and a secondary system are arranged on opposite sides.   The transfer unit has four transfer units, two high-voltage substrate units are inverted between the first and second transfer units, and two high-voltage substrate units are inverted between the third and fourth transfer units. The image forming apparatus according to claim 1, wherein the image forming apparatus is disposed in an orientation.   The transfer unit has at least one of a detection unit that detects a phase of a driving roller that conveys and drives the belt body and a detection unit that detects an edge position of the belt body, and processes a detection signal by the detection unit. 4. The image forming apparatus according to claim 3, wherein a control substrate to be provided is provided between the second and third transfer portions.   The image forming apparatus according to claim 4, wherein a cross member forming a casing of the transfer unit is provided in the vicinity of the second and third transfer portions.

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