JP4525648B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus that forms an image on a recording sheet, and an electronic apparatus including a power supply circuit board that supplies power to each portion.

  Conventionally, in laser beam printers, the tip of the wire extended from each part of the transfer roller, charger, developer, etc. is connected to the power circuit board by screwing or soldering to supply power to the transfer roller, etc. is doing. In such a configuration, it takes time and labor for screwing and soldering, which increases the cost of the printer. Accordingly, various configurations have been studied in which power can be supplied to the transfer roller or the like without screwing or soldering.

  For example, as shown in FIG. 4, there is a printer configured to supply electric power to each portion by an elastic conductive member disposed from a transfer roller 107 or the like to a power circuit board. In such a configuration, the jumper wire (axial jumper) 140 disposed on the component mounting surface 112b of the power circuit board 112 and the tip 131 of the elastic conductive member 130 are brought into contact with each other so as to ensure conduction between the two. I have to.

  Both ends of the jumper wire 140 are bent at a substantially right angle, and the tip is penetrated from the component mounting surface 112b side of the power supply circuit board 112 to the circuit pattern forming surface 112a side through a through hole, and then the circuit pattern forming surface. It is soldered to the land part formed in 112a. Therefore, the central portion of the jumper wire 140 that is in contact with the tip 131 is located on the component mounting surface 112 b side of the power circuit board 112. Since it is necessary to output a high voltage from the power circuit board 112 to the transfer roller 107 or the like, the contact pressure between the jumper wire 140 and the tip 131 must be high enough to obtain reliable conduction, while the above-mentioned If the contact pressure is too high, problems such as deformation of the power circuit board 112 occur. Therefore, in consideration of these circumstances, the elastic coefficient of the elastic conducting member 130 is determined, and in order to realize this, the material, alignment, dimensions such as the number of turns, etc. of the elastic conducting member 130 are set. Accordingly, the distance d between the power circuit board 112 and the frame 113 is set according to the dimension of the elastic conductive member 130.

  Frames 113 for supporting the transfer roller 107 are provided upright at both ends of the transfer roller 107. However, the distance d between the power circuit board 112 and the frame 113 is set according to the dimensions of the elastic conductive member 130, and the jumper wire 140 is positioned on the component mounting surface 112 b side of the power circuit board 112. For this reason, the electronic component mounted on the power supply circuit board 112 is restricted by its height dimension. Therefore, as indicated by a broken line in FIG. 4, an electronic component such as a transformer 143 having a height exceeding the distance d between the power circuit board 112 and the frame 113 cannot be used, and a transformer 144 having a small height is used. The degree of freedom in selecting parts, such as having to use them, decreases. In addition, an electronic component such as the transistor 142 having a large height must be mounted in a state where the lead 142a is bent and inclined, which places a burden on the bent portion and may cause a failure. It was. Furthermore, in an electronic component such as the transistor 141 having a large calorific value, it is necessary to use a large heat radiating plate 145. In order to avoid such interference between the heat radiating plate 145 and the frame 113, the heat radiating plate 145 is used. Must be placed in parallel with the power supply circuit board 112 in a state where it is laid down. Accordingly, not only is the load applied to the bent portion of the lead portion 141a, but the area occupied by the heat sink 145 on the substrate is increased, and the power circuit board 112 cannot be reduced in size.

Note that Patent Documents 1 and 2 show printed circuit boards on which jumper wires are mounted from the component mounting surface side of the circuit board, as described above.
JP-A-9-36517 JP 2006-1000071 A

  The present invention has been made in order to solve the above-described problems, and is an image forming apparatus capable of mounting an electronic component having a large height in an upright state without being restricted by a distance between a power circuit board and a frame. The purpose is to provide.

In order to achieve the above object, the invention of claim 1
A photoreceptor drum having a photoreceptor coated on the surface;
Charging means for uniformly charging the surface of the photosensitive drum;
Exposure means for forming a latent image by irradiating the surface of the photoconductor while scanning with a laser beam;
Developing means for forming a toner image by attaching toner to a portion of the surface of the photoreceptor where a latent image is formed;
At a predetermined transfer position downstream of the developing means in the rotational direction of the photosensitive drum, the photosensitive drum is provided to face the surface of the photosensitive drum, and the surface of the recording sheet is charged to Transfer means for transferring the toner image formed on the surface onto the recording paper;
Fixing means for applying a predetermined heat and pressure to the recording paper on which the toner image has been transferred to fix the toner image on the recording paper;
Conveying means for conveying the recording paper to the transfer position;
A frame erected so as to be orthogonal to the rotation axis of the photosensitive drum in order to support the photosensitive drum, charging means, exposure means, developing means, transfer means, fixing means, and conveying means;
An image forming apparatus comprising a power supply circuit board for supplying electric power to the photosensitive drum, charging means, exposure means, developing means, transfer means, fixing means, and conveying means.
In order to electrically connect at least one of the photosensitive drum, charging means, exposure means, developing means, transfer means, fixing means, and conveying means to the power supply circuit board, each means faces the power supply circuit board. An elastic conducting member having elasticity provided over a position ;
A support member coupled to a part of the frame to support the elastic conducting member ;
The elastic conducting member is rotatable by the support member and an abutting portion that abuts at least one of the photosensitive drum, charging unit, exposure unit, developing unit, transfer unit, fixing unit, and conveying unit. A torsion coil spring portion supported by the coil spring portion and a coil spring portion abutting against the power circuit board,
The power supply circuit board is disposed in an upright posture in parallel with the frame so that a circuit pattern forming surface thereof faces the elastic conducting member, and faces the tip of the elastic conducting member on the circuit pattern forming surface. In the position to be mounted, a pair of jumper wires that are in contact with the tip of the coil spring portion are mounted, and
Electronic components constituting a power supply circuit are mounted on the back side of the circuit pattern forming surface,
Some of the electronic components are mounted on the power circuit board together with a heat dissipation member,
Regardless of the distance between the frame and the power circuit board, an electronic component having a large height and a heat dissipating member can be mounted on the power circuit board in an upright position.

  According to the first aspect of the present invention, since the electronic component constituting the power supply circuit is mounted on the back side of the circuit pattern forming surface, the electronic component having a large height is erected while using the existing elastic conductive member. Thus, it can be mounted on the power circuit board. As a result, there is no restriction on the height dimension of the electronic component, the degree of freedom in selecting the component can be increased, and the electronic component can be mounted on the power circuit board in an upright position without bending the lead portion. There is no risk of overloading. Similarly, some of the electronic components with the heat dissipation member can be mounted on the power supply circuit board in an upright posture without any restriction on the height. Thereby, there is no possibility that an excessive burden is applied to the lead portion. Further, since the area occupied by the heat dissipating member on the substrate can be reduced, the degree of freedom in designing the power circuit board can be increased and the size can be easily reduced. In addition, since a pair of jumper wires that are brought into contact with the tip of the elastic conductive member are mounted on the circuit pattern forming surface, the tip of the elastic conductive member and the jumper wire are in contact at a plurality of locations. As the contact area increases, the contact pressure becomes uniform. Thereby, the contact resistance between both can be reduced. Furthermore, since the power circuit board is disposed in a standing posture in parallel with the frame, the apparatus can be reduced in size.

  An image forming apparatus according to an embodiment of the invention will be described with reference to the drawings. FIG. 1 shows a laser beam printer 1 which is a configuration example of an image forming apparatus. A laser beam printer 1 includes a photosensitive drum 2, a cleaner 3, a charger 3, a charger (charging means) 4, a laser scanning unit (exposure means) 5, a developing brush (developing means) 6, and a transfer roller. (Transfer means) 7, a fixing roller (fixing means) 8 disposed downstream of the transfer roller 7 in the conveying direction of the recording paper P, and a paper feed tray (recording paper holding means) loaded with the recording paper P 9, a paper discharge unit 10 on which the printed recording paper P is deposited, a recording paper transport mechanism (transport means) 11 for transporting the recording paper P loaded in the paper feed tray 9 to the position of the photosensitive drum 2, and each part of the apparatus The power supply circuit board 12 (see FIG. 2) and the like for supplying power to the power supply. Each of the above components is mounted and supported on a metal frame 13 disposed on the bottom of the laser beam printer 1 or the like. The frame 13 is provided with a cover 14 that covers each of the above components and forms the exterior of the laser beam printer 1, and on the rear side thereof, the recording paper P jammed in the recording paper transport mechanism 11 is removed or A door member 15 for exchanging a toner cartridge 17 described later is provided so as to be freely opened and closed.

  The cleaner 3 removes toner and paper dust before one stroke (one rotation) adhering to the surface of the photosensitive drum 2 and cleans the drum surface. The charger 4 uniformly charges the surface of the photosensitive drum 2 cleaned by the cleaner 3. The laser scan unit 5 forms a latent image by irradiating the surface of the photosensitive drum 2 charged by the charger 4 while scanning the laser beam L. The developing brush 6 is attached to a toner cartridge 17 filled with toner, and forms a toner image by attaching toner to a portion of the surface of the photosensitive drum 2 where a latent image is formed. The transfer roller 7 is provided so as to oppose the surface of the photosensitive drum 2, and charges the surface of the recording paper P while pressing the recording paper P against the surface of the photosensitive drum 2. The formed toner image is transferred onto the recording paper P. Electric power necessary for the transfer is supplied from the power supply circuit board 12. The recording paper P on which the image is formed on the surface by the transfer roller 7 is conveyed to the fixing roller 8. The fixing roller 8 fixes the toner by applying heat and pressure while sandwiching the recording paper P together with the pressing roller 16 disposed opposite to the fixing roller 8. Heat for fixing the toner is supplied from a heater (for example, a halogen lamp) built in the fixing roller 8. A fixing voltage generated by the power supply circuit board 12 is applied to the heater. The recording paper transport mechanism 11 has a pick roller 21 that sends out the recording paper P loaded in the paper feed tray 9. The pick roller 21 is rotatably supported by the frame member 23 via the rotation shaft 22.

  FIG. 2 shows the configuration of the transfer roller 7, the power supply circuit board 12, and the vicinity thereof. A feeding terminal 7 a for supplying power for transfer is attached to the edge of the transfer roller 7. Further, an elastic conducting member 30 formed by processing a metal bar is mounted between the power supply terminal 7a and the power supply circuit board 12.

  FIG. 3 shows the configuration of the power supply circuit board 12 and the elastic conducting member 30 and their surroundings. The power supply circuit board 12 is arranged in a standing posture in parallel with the frame 13 so that the circuit pattern forming surface 12 a faces the frame 13 and the elastic conductive member 30. As a result, the component mounting surface 12b on which electronic components such as the transistors 41 and 42 and the transformer 43 are mounted is positioned on the back surface of the circuit pattern forming surface 12a, that is, on the side opposite to the frame 13. Further, in the circuit pattern forming surface 12 a of the power circuit board 12, a pair of contact conductively connected with the distal end portion 31 of the elastic conducting member 30 is located at a position facing the distal end portion 31 of the elastic conducting member 30 (see FIG. 2) A jumper line 40 is mounted. In the laser beam printer 1 at the time of the printing operation, it is necessary to apply a high voltage of about −2000 V to the transfer roller 7 in particular. Therefore, in order to obtain good energization characteristics, generally the elastic conductive member 30 and the jumper wire It is necessary to increase the contact area with 40 to reduce the contact resistance. Therefore, in the present embodiment, by making the jumper wires 40 a pair, the contact area is increased, and each jumper wire 40 is arranged symmetrically with respect to the axis of the coil spring portion 30c of the elastic conducting member 30. The contact pressure is made uniform and the contact resistance is reduced. Similar to the transistors 41 and 42 and the transformer 43, the jumper line 40 is attached to a through hole formed in the power circuit board 12, and is soldered to a land portion of the circuit pattern formation surface 12a in the dipping process. Thus, it is possible to reliably conduct.

  Various electronic components such as the transistors 41 and 42 and the transformer 43 are mounted on the component mounting surface 12b. Among the electronic components, components such as the component transistor 41 that generates a particularly large amount of heat are mounted on the power supply circuit board 12 together with a heat sink (heat dissipating member) 45. As described above, in order to make the elastic coefficient of the elastic conducting member 30 appropriate, the frame 13 and the power supply circuit board 12 need to be arranged at a predetermined interval d. Since the transistors 41 and 42, the transformer 43, and the like are mounted on the component mounting surface 12b on the opposite side of the frame 13, the height of these electronic components depends on the distance d between the frame 13 and the power supply circuit board 12. There are no dimensional constraints.

  The elastic conducting member 30 is a torsion coil spring portion that is rotatably supported by a terminal contact portion 30a that is in contact with the power supply terminal 7a and a support member 50 that is coupled to a part of the frame 13 of the laser beam printer 1. 30 b and a coil spring portion (tip portion) 30 c that comes into contact with the power supply circuit board 12. By the torsion coil spring portion 30b and the coil spring portion 30c, elasticity required for contact conduction between the power supply terminal 7a and the terminal contact portion 30a and contact between the jumper wire 40 mounted on the power supply circuit board 12 and the coil spring portion 30c. Is applied to the elastic conducting member 30. That is, in FIG. 2, when the transfer roller 7 is mounted in the arrow X direction, the power supply terminal 7a contacts the terminal contact portion 30a, and the terminal contact portion 30a is pressed in the arrow Y direction in FIG. Thereby, the elastic conducting member 30 is rotated around the support member 50, and the coil spring portion 30c is urged in the direction of the jumper wire 40 (arrow Z direction), and the contact between both is ensured. In FIG. 3, only the connection between the transfer roller 7 and the power supply circuit board 12 is shown, but the charger 4, the laser scan unit 5, the developing brush 6, the fixing roller 8, and the recording paper transport mechanism 11 are also equivalent. The power supply circuit board 12 is connected in the configuration.

  As described above, according to the laser beam printer 1 of the present embodiment, the electronic components (transistors 41 and 42, the transformer 43, etc.) constituting the power supply circuit are mounted on the back side of the circuit pattern forming surface 12a. The electronic component having a large height can be mounted on the power circuit board 12 in a standing posture while using the existing elastic conductive member 30. Thereby, there is no restriction on the height dimension of the transistor 42 and the like, and the degree of freedom of component selection can be increased, and the electronic component can be mounted on the power supply circuit board in an upright posture without bending the lead portion 42a. There is no possibility that an excessive load is applied to the lead portion 42a. Similarly, components such as the transistor 41 having a large calorific value with the heat sink 45 among the electronic components can be mounted on the power supply circuit board 12 in an upright posture without restriction on the height of the heat sink 45. Thereby, there is no possibility that an excessive burden is applied to the lead portion 41a. In addition, since the area occupied by the heat sink 45 on the substrate can be reduced, the degree of freedom in designing the power supply circuit board 12 can be increased and the size can be easily reduced. In addition, since a pair of jumper wires 40 that are in contact with the tip end portion 31 of the coil spring portion 30c of the elastic conducting member 30 are mounted on the circuit pattern forming surface 12b, a plurality of tip end portions 31 and jumper wires 40 are provided. Since contact is made at a location, the contact area is increased and the contact pressure is made uniform. Thereby, the contact resistance between both can be reduced. Furthermore, since the power circuit board 12 is arranged in a standing posture parallel to the frame 13, the laser beam printer 1 can be reduced in size.

  The present invention is not limited to the configuration of the above embodiment, and at least the circuit pattern forming surface 12b is mounted with the jumper wire 40, and the electronic component such as the transistor 41 is disposed on the surface opposite to the frame 13 and the elastic conductive member 30. Should be implemented. Further, the number and arrangement of the jumper wires 40 are not limited to the example shown in FIG. The present invention can be modified in various ways. For example, the image forming apparatus is not limited to the laser beam printer 1, and other image forming apparatuses such as a laser beam type copying machine and an ink jet printer are used. Widely applicable to electronic devices.

The figure which shows the structure of the laser beam printer by one Embodiment of this invention. FIG. 3 is a perspective view illustrating a configuration of a transfer roller, a power supply circuit board, and the vicinity thereof in the printer. The top view which shows the structure of the elastic conduction member which makes the transfer roller and a power supply circuit board conduct | electrically_connect, and its periphery. The top view which shows the structure of the elastic conduction member and its periphery which conduct | electrically_connect a transfer roller and a power supply circuit board in the conventional laser beam printer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser beam printer 2 Photosensitive drum 4 Charger (charging means)
5 Laser scan unit (exposure means)
6 Developing brush (Developing means)
7 Transfer roller (transfer means)
8 Fixing roller (fixing means)
9 Paper feed tray 11 Recording paper transport mechanism (transport means)
12 Power Circuit Board 30 Elastic Conductive Member 40 Jumper Wire 41 Transistor (Electronic Component)
42 Transistor (electronic component)
43 Transformer (electronic parts)
45 Heat dissipation plate (heat dissipation member)

Claims (1)

A photoreceptor drum having a photoreceptor coated on the surface;
Charging means for uniformly charging the surface of the photosensitive drum;
Exposure means for forming a latent image by irradiating the surface of the photoconductor while scanning with a laser beam;
Developing means for forming a toner image by attaching toner to a portion of the surface of the photoreceptor where a latent image is formed;
At a predetermined transfer position downstream of the developing means in the rotational direction of the photosensitive drum, the photosensitive drum is provided to face the surface of the photosensitive drum, and the surface of the recording sheet is charged to Transfer means for transferring the toner image formed on the surface onto the recording paper;
Fixing means for applying a predetermined heat and pressure to the recording paper on which the toner image has been transferred to fix the toner image on the recording paper;
Conveying means for conveying the recording paper to the transfer position;
A frame erected so as to be orthogonal to the rotation axis of the photosensitive drum in order to support the photosensitive drum, charging means, exposure means, developing means, transfer means, fixing means, and conveying means;
An image forming apparatus comprising a power supply circuit board for supplying electric power to the photosensitive drum, charging means, exposure means, developing means, transfer means, fixing means, and conveying means.
In order to electrically connect at least one of the photosensitive drum, charging means, exposure means, developing means, transfer means, fixing means, and conveying means to the power supply circuit board, each means faces the power supply circuit board. An elastic conducting member having elasticity provided over a position ;
A support member coupled to a part of the frame to support the elastic conducting member ;
The elastic conducting member is rotatable by the support member and an abutting portion that abuts at least one of the photosensitive drum, charging unit, exposure unit, developing unit, transfer unit, fixing unit, and conveying unit. A torsion coil spring portion supported by the coil spring portion and a coil spring portion abutting against the power circuit board,
The power supply circuit board is disposed in an upright posture in parallel with the frame so that a circuit pattern forming surface thereof faces the elastic conducting member, and faces the tip of the elastic conducting member on the circuit pattern forming surface. In the position to be mounted, a pair of jumper wires that are in contact with the tip of the coil spring portion are mounted, and
Electronic components constituting a power supply circuit are mounted on the back side of the circuit pattern forming surface,
Some of the electronic components are mounted on the power circuit board together with a heat dissipation member,
An image forming apparatus, wherein an electronic component having a large height and a heat radiation member can be mounted on the power circuit board in an upright position regardless of the distance between the frame and the power circuit board.

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