JP2010076895A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus suppressing jump of static electricity to a circuit board, in structure in which the circuit board of a sensor is supported by engagement with a hook part formed to a resin support frame. <P>SOLUTION: The image forming apparatus includes: a sheet metal guide 70 guiding a recording sheet delivered from a paper feed tray and electrically grounded; a sensor 100 detecting the recording sheet inserted in a manual paper feed port; and the resin support frame (chute cover 61) supporting the sensor 100. A lower wall part 61A of the support frame has: the oscillatable hook part 66C engaged with the circuit board 90 of the sensor 100; and an opening part 66D formed around the hook part 66C to allow the oscillation of the hook part 66C. An extension part 73B extended to cover a part of the opening part 66D is formed to the sheet metal guide 70. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus including a sensor that detects a recording sheet inserted into a manual sheet feeding port.

  2. Description of the Related Art Conventionally, as an image forming apparatus, a paper feed tray that is detachable from an outlet of an apparatus main body, a manual paper feed port that is located above the drawer, and a sensor that detects a recording sheet inserted into the manual paper feed port A resin support frame that supports the sensor is known (see Patent Document 1).

JP 2006-315797 A

  By the way, in order to reduce the number of parts, in order to fix the sensor circuit board to the support frame without using screws or the like, a part of the resin support frame is formed as a hook part, and this hook part is connected to the circuit board. A structure in which the circuit board is fixed to the support frame can be considered. In the case of this structure, it is necessary to form an opening around the hook portion in order to swing the hook portion.

  However, if the opening for the hook portion opens into the installation space for the paper feed tray in the apparatus main body, the circuit board of the sensor faces the installation space for the paper feed tray through this opening. In this case, when the user pulls out the paper feed tray from the drawer outlet and sets paper in the paper feed tray, if static electricity is accumulated in the user's hand, the static electricity from the user passes through the opening to the circuit board. There was a risk of flying and adversely affecting the circuit board.

  Accordingly, the present invention provides an image forming apparatus capable of suppressing static electricity from flying on a circuit board in a structure in which the circuit board of the sensor is supported by being engaged with a hook portion formed on a resin support frame. The purpose is to do.

  The present invention that solves the above-described problems is a paper feed tray that is detachable from the outlet of the apparatus main body, a manual paper feed port that is formed above the outlet of the apparatus main body, and a paper tray that is discharged from the paper tray. An image provided with a sheet metal guide that guides the recording sheet and is electrically grounded, a sensor that detects the recording sheet inserted into the manual sheet feeding port, and a resin support frame that supports the sensor A forming device, wherein a swingable hook portion that engages with a circuit board of the sensor is provided on a lower wall portion of the support frame, and the hook portion is configured to allow swinging of the hook portion. An opening formed on the sheet metal guide, and an extension that extends to cover at least a part of the opening is formed adjacent to the opening. To do.

  According to the present invention, the sheet metal guide is formed with the extending portion extending to cover at least a part of the opening or adjacent to the opening formed in the lower wall portion of the support frame. At this time, even if the user's hand that has accumulated static electricity approaches the opening, the static electricity does not pass through the opening but jumps to the extension near the opening. Thereafter, static electricity flows to ground through the sheet metal guide.

  According to the present invention, the sheet metal guide is formed with the extending portion extending to cover at least a part of the opening or adjacent to the opening formed in the lower wall portion of the support frame. In this case, it is possible to prevent static electricity from flying from the user's hand through the opening to the circuit board.

  Next, embodiments of the present invention will be described with reference to the drawings. In the drawings to be referred to, FIG. 1 is a cross-sectional view showing an overall configuration of a color printer, and FIG. 2 is a cross-sectional view showing a state in which a paper feed tray is pulled out. In the following description, the direction will be described with reference to the user when using the color printer. That is, in FIG. 1, the left side toward the paper surface is “front side (front side)”, the right side toward the paper surface is “rear side (back side)”, the back side toward the paper surface is “left side”, and it faces the paper surface. Let the near side be the “right side”. In addition, the vertical direction toward the page is defined as the “vertical direction”.

<Overall configuration of image forming apparatus>
As shown in FIG. 1, a color printer 1 as an example of an image forming apparatus is a direct transfer tandem printer, and includes a substantially box-shaped casing 2 as an example of an apparatus main body. A front cover 3 is provided on the front surface of the housing 2. Further, on the upper surface of the housing 2, a paper discharge tray 5A on which paper 4 as an example of a recording sheet is stacked after image formation is formed.

  A paper feed tray 7 for storing the paper 4 before image formation is disposed at the lower part of the housing 2, and this paper feed tray 7 is formed at the lower part of the front cover 3 as shown in FIG. It is detachable from the outlet 3B. As shown in FIG. 1, a paper feed roller 11 for transporting the paper 4 is provided at a position above the front end of the paper feed tray 7 in the mounted state. A separation roller 12 and a separation pad 13 for separating the paper 4 conveyed by the paper roller 11 one by one are provided.

  The uppermost sheet 4 in the sheet feed tray 7 is separated one by one by a sheet feed roller 11, a separation roller 12, and the like, and is then sandwiched between a paper dust removing roller 14 and a counter roller 15 and conveyed. The sheet is guided by a sheet metal guide 70 which will be described later, and is fed between a pair of registration rollers 16 and 17. The registration rollers 16 and 17 send the paper 4 onto the rear belt unit 20 at a predetermined timing.

  A part of the front cover 3 is configured to be openable as a manual feed tray 18. The manual feed tray 18 is a tray for opening and closing the manual feed port 3C formed above the outlet 3B of the front cover 3 and for placing the paper 4 thereon. Then, the paper 4 inserted into the manual paper feed port 3 </ b> C passes between the manual chute surface 62 of the front chute 60 described later and is inserted between the registration rollers 16 and 17. The paper 4 thus inserted into the manual paper feed port 3 </ b> C is similarly sent out onto the belt unit 20 by the registration rollers 16 and 17.

  Note that the contact portion 81 of the actuator 80 (see FIG. 3) protrudes from the manual feed side chute surface 62 so as to penetrate upward through the hole 62A. The registration rollers 16 and 17 are driven and controlled to convey the paper 4 when the contact portion 81 is tilted by the paper 4 inserted into the manual paper feed port 3C. The configuration of the front chute 60 including the contact portion 81 will be described in detail later.

  The belt unit 20 includes a conveyor belt 23 that is stretched between a belt driving roller 21 and a tension roller 22 that are spaced apart from each other in the front-rear direction. The conveyance belt 23 is an endless belt made of a resin material such as polycarbonate, and conveys the paper 4 placed on the upper surface thereof backward when the belt drive roller 21 on the rear side is rotationally driven.

  Inside the conveyance belt 23, four transfer rollers 24 arranged to face four photosensitive drums 31 described later are arranged at regular intervals in the front-rear direction, whereby transfer corresponding to each photosensitive drum 31 is provided. The conveyance belt 23 is sandwiched between the rollers 24. A transfer bias is applied to the transfer roller 24 by constant current control during transfer.

  Four process cartridges 30 are provided corresponding to each color of black, cyan, magenta, and yellow in pairs with the LED unit 40. Each process cartridge 30 and each LED unit 40 are provided in series along the paper transport direction.

  Each process cartridge 30 includes a photosensitive drum 31, a scorotron charger 32, a developing cartridge 34, and the like. The photosensitive drum 31 includes a grounded metal drum main body, and is configured by covering the surface layer with a positively chargeable photosensitive layer. The scorotron charger 32 is disposed opposite the photosensitive drum 31 with a predetermined interval so as not to contact the photosensitive drum 31. The scorotron charger 32 uniformly charges the surface of the photosensitive drum 31 to positive polarity by generating corona discharge.

  The developing cartridge 34 includes a toner storage chamber 35, a supply roller 36, a developing roller 37, and a layer thickness regulating blade 38. In the toner storage chamber 35 of each developing cartridge 34, black, cyan, magenta, or yellow positively chargeable non-magnetic one-component toner is stored as a developer.

  The toner in the toner storage chamber 35 is supplied to the developing roller 37 by the rotation of the supply roller 36 and is positively frictionally charged between the supply roller 36 and the developing roller 37. The toner supplied onto the developing roller 37 enters between the layer thickness regulating blade 38 and the developing roller 37 as the developing roller 37 rotates, and is further sufficiently frictionally charged to form a thin layer having a constant thickness. Is carried on the developing roller 37.

  The surface of the photosensitive drum 31 is uniformly positively charged by the scorotron charger 32 and then exposed to LEDs (not shown) arranged in a line in the paper width direction (left-right direction) at the lower end of the LED unit 40. Thus, an electrostatic latent image corresponding to the image to be formed on the paper 4 is formed.

  Next, the electrostatic latent toner formed on the surface of the photosensitive drum 31 when the positively charged toner carried on the developing roller 37 contacts the photosensitive drum 31 by the rotation of the developing roller 37. Supplied to the image. As a result, the electrostatic latent image on the photosensitive drum 31 is visualized, and the surface of the photosensitive drum 31 carries a toner image with toner attached only to the exposed portion.

  Thereafter, the toner image carried on the surface of each photosensitive drum 31 is transferred to the transfer roller to which a transfer bias is applied when the paper 4 conveyed by the conveyance belt 23 passes between the photosensitive drum 31 and the transfer roller 24. Attracted to 24 and sequentially transferred onto the paper 4. The paper 4 on which the toner images of the respective colors are transferred in this manner is conveyed to the fixing device 50.

  The fixing device 50 is disposed behind the conveyance belt 23 in the housing 2. The fixing device 50 includes a heating roller 51 that is rotationally driven with a heat source such as a halogen lamp, and a pressure roller 52 that is disposed below the heating roller 51 so as to press the heating roller 51. Yes. In the fixing device 50, the toner image is fixed to the paper 4 by heating the paper 4 on which the toner images of the respective colors are transferred while being nipped and conveyed by the heating roller 51 and the pressure roller 52. The sheet 4 on which the toner image is fixed is conveyed by a conveyance roller 53 disposed obliquely above and behind the fixing device 50, and is discharged onto the sheet discharge tray 5A by a sheet discharge roller 54 provided at the upper part of the housing 2. Discharged.

<Configuration of front chute>
Next, the configuration of the front chute 60 will be described in detail. In the drawings to be referred to, FIG. 3 is an exploded perspective view showing the front chute exploded, and FIG. 4 is an enlarged view (a) showing the inside of the chute cover before the sensor is attached, and the sensor attached. It is an enlarged view (b) which expands and shows the inside of the chute | shoot cover after a long time. 5 is a cross-sectional view showing the structure around the circuit board, FIG. 6 is an exploded perspective view showing the extension part of the sheet metal guide and the opening part of the chute cover, and FIG. 7 is a part of the opening part of the chute cover. It is an expansion perspective view which shows the state covered with the extension part of the sheet metal guide.

  As shown in FIG. 3, the front chute 60 has a sheet metal guide 70 made of a metal plate smoothly curved along the conveyance path of the paper 4 at the rear part of a resin chute cover 61 as an example of a support frame. It is configured to be fixed at S. Further, a manual feed side chute surface 62 formed on the upper surface of the chute cover 61 is provided with a hole 62A (see FIG. 2) in the center of the paper width direction (left and right direction). The contact part 81 protrudes so that it can swing back and forth.

  The chute cover 61 is configured in a box shape opened rearward, and a sensor 100 that detects the paper 4 inserted into the manual paper feed port 3C (see FIG. 1) is provided on the inside thereof. The sensor 100 includes an actuator 80 and a circuit board 90. The actuator 80 has a structure in which the abutting portion 81 described above, an arm 82 having a light shielding plate 82A formed at the tip thereof, and an actuator positioning arm 83 are integrally formed around one shaft 84. Further, the circuit board 90 is configured by using a known printed wiring board, and a photo interrupter 91 capable of detecting light emitted from the light emitting part by the light receiving part is attached to the lower part of the circuit board 90.

  Corresponding to these configurations, the inner surface of the chute cover 61 has a long hole 63 for supporting one end 84A of the shaft 84, a positioning arm receiving portion 64 for receiving the actuator positioning arm 83, and the other end 84B of the shaft 84. And a board mounting portion 66 on which the circuit board 90 is mounted.

  As shown in FIGS. 4A and 4B, the long hole 63 is configured to be elongated in the front-rear direction in order to facilitate the insertion of the one end 84A of the shaft 84. The shaft 84 is supported by the notch portion 64A of the positioning arm receiving portion 64, whereby the one end 84A is rotatably supported by the rear end of the long hole 63.

  The positioning arm receiving portion 64 is formed in a U-shape with the rear view opened upward so as to receive the rectangular plate-like actuator positioning arm 83 protruding from the shaft 84, and a cylindrical surface is formed on a portion overlapping the shaft 84. A notch 64A is formed. When the actuator positioning arm 83 is fitted to the positioning arm receiving portion 64, the position of the actuator 80 in the left-right direction is determined.

  The bearing portion 65 rotatably supports the other end 84B of the shaft 84. The other end 84 </ b> B is configured such that a portion inserted into the bearing portion 65 has a smaller diameter than other portions of the shaft 84. In the state where the shaft 84 is supported by the bearing portion 65, the notch portion 64A, and the long hole 63, the light shielding plate 82A is interposed between the light emitting portion 91A and the light receiving portion 91B of the photo interrupter 91 mounted on the circuit board 90. Be placed. Further, a torsion coil spring 85 is fitted on the shaft 84. The torsion coil spring 85 has one end 85 </ b> A engaged with the contact portion 81 and the other end 85 </ b> B engaged with a spring receiving portion 67 provided on the chute cover 61, thereby biasing the contact portion 81 forward. ing.

  As a result, the contact portion 81 normally contacts the front end of the hole 62A by the biasing force of the torsion coil spring 85, and at this time, the light shielding plate 82A blocks the optical path from the light emitting portion 91A to the light receiving portion 91B. Then, when the sheet 4 is inserted through the manual feed tray 18 and the abutting portion 81 swings backward, the light from the light emitting portion 91A is detected by the light receiving portion 91B. Based on the detection result of the light receiving portion 91B, known drive control for the registration rollers 16, 17 and the like is executed by a control system (not shown).

  As shown in FIG. 4A, the board mounting portion 66 includes a pair of holding ribs 66A for holding the upper end portion of the circuit board 90, a support rib 66B and a hook portion 66C for holding the lower end portion of the circuit board 90, An opening 66D formed around the hook portion 66C is provided to allow the hook portion 66C to swing.

  The hook portion 66C is integrally formed with the lower wall portion 61A of the chute cover 61 together with the opening portion 66D. The hook portion 66C has a hook-like tip, and is bent and deformed to the left and right to press and fix the lower end portion of the circuit board 90 against the support rib 66B. And this hook part 66C is formed so that it may protrude below lower wall part 61A of chute cover 61 (refer to Drawing 6), and, thereby, extension part 73B (refer to Drawing 6) of sheet metal guide 70 mentioned below Can be engaged.

  As shown in FIG. 5, the lower part of the circuit board 90 is sandwiched between the hook-shaped tip part C1 of the hook part 66C and the front end edge of the opening part 66D, and the upper part is the front wall part 61B of the chute cover 61. Is in contact with a positioning projection 61C formed on the substrate. Thereby, the movement of the circuit board 90 in the front-rear direction is restricted.

  Further, the circuit board 90 is sandwiched between the upper wall portion 66E connecting the upper ends of the pair of sandwiching ribs 66A, the tip end portion C1 of the hook portion 66C, and the lower wall portion 61A in the vertical direction. As a result, the movement of the circuit board 90 in the vertical direction is restricted.

  As described above, the circuit board 90 supported by the hook portion 66C or the like is in the space near the outlet 3B (the space in which the paper feed tray 7 is accommodated) via the opening 66D, as shown in FIG. To be exposed.

  As shown in FIG. 3, the sheet metal guide 70 includes a curved plate-shaped guide portion 71 that guides the paper 4, a pair of mounting flanges 72 that protrude forward from the left and right ends of the guide portion 71, and a shape shown in FIG. 6. And a lower flange 73 projecting forward from the lower end of the guide portion 71. The lower flange 73 is formed by being bent from the lower end of the guide portion 71 so as to cover the lower surface of the lower wall portion 61A of the chute cover 61, and escapes from the hook portion 66C at a position corresponding to the hook portion 66C. The formed escape portion 73A is formed.

  Further, on the right side of the escape portion 73A, an extension portion 73B that extends forward and covers a part of the opening 66D is formed. Specifically, as shown in FIG. 7, the extending portion 73 </ b> B has a right surface (a surface opposite to the surface contacting the circuit board 90) of the hook portion 66 </ b> C when the sheet metal guide 70 is attached to the chute cover 61. ). Accordingly, the hook portion 66C is prevented from swinging (opening) in the right direction, and the circuit board 90 is prevented from falling off the hook portion 66C.

  The sheet metal guide 70 configured as described above is electrically grounded. As a result, when the sheet 4 is brought into sliding contact with the sheet metal guide 70, static electricity accumulated on the sheet 4 is caused to flow to the ground via the sheet metal guide 70.

Next, the operation of the sheet metal guide 70 will be described.
As shown in FIG. 2, when the user pulls out the paper feed tray 7 and puts the paper 4 into the paper feed tray 7, even if the user's hand with static electricity approaches the opening 66D, The accumulated static electricity does not fly to the circuit board 90 above (back) the opening 66D, but to the extension 73B of the sheet metal guide 70 below (front) the opening 66D. Then, the static electricity captured by the extending portion 73 </ b> B flows to the ground via the sheet metal guide 70.

According to the above, the following effects can be obtained in the present embodiment.
The sheet metal guide 70 is formed with an extending portion 73B that extends so as to cover a part of the opening 66D formed in the lower wall portion 61A of the chute cover 61. The static electricity can be prevented from flying to the circuit board 90 through the opening 66D. Further, since the opening 66D is covered using the sheet metal guide 70 for removing the static electricity charged in the paper 4 being conveyed, that is, the sheet metal guide 70 that is originally grounded, the opening 66D is covered with a new sheet metal. Thus, the number of parts can be reduced compared to the structure in which the sheet metal is grounded.

  Since the extension part 73B of the sheet metal guide 70 is engaged with the hook part 66C, even if the user accidentally pushes the hook part 66C in the opening direction, the hook part 66C is opened by the extension part 73B. Therefore, the circuit board 90 can be prevented from falling off.

In addition, this invention is not limited to the said embodiment, It can utilize with various forms so that it may illustrate below.
In the embodiment, a part of the opening 66D is covered with the extending part 73B. However, the present invention is not limited to this, and as shown in FIGS. 8A and 8B, all of the opening 66D is covered. You may make it cover with the wide extension part 73C. According to this, since static electricity accumulated in the user's hand does not pass through the opening 66D, it is possible to reliably prevent static electricity from flying to the circuit board 90. In this case, it is desirable to form the hook portion 66C flush with the lower wall portion 61A of the chute cover 61 without projecting, and to make the extending portion 73C closely contact the vicinity of the opening 66D of the lower wall portion 61A. . According to this, it is possible to suppress static electricity from leaking from the gap between the lower wall portion 61 </ b> A and the extending portion 73 </ b> C and reaching the circuit board 90.

  Further, as shown in FIG. 9, a part 73C of the wide extension part shown in FIG. 8 is cut upward by press working or the like to form a regulation part 73D that regulates the swing of the hook part 66C. May be. Specifically, as shown in FIGS. 10A, 10B, and 11, the restricting portion 73D enters into the escape portion 66F formed at the rear end of the opening 66D, so that the hook portion 66C Engage with the right side. According to this, a small hole opens in a part of the wide extension part 73C due to the formation of the regulation part 73D, but since substantially the entire opening part 66D is covered with the extension part 73C, static electricity passes through the opening part 66D. Thus, it is possible to satisfactorily prevent the circuit board 90 from flying. Moreover, since the swinging of the hook portion 66C is restricted by the restricting portion 73D, the circuit board 90 can be prevented from falling off.

  In addition, as shown in FIG. 9, a part of the extending part 73C is not cut and raised, but a protrusion that engages with the hook part 66C without making a hole in a part of the extending part 73C by drawing or welding. You may form in the extension part 73C. According to this, since a hole is not opened in the extension part 73C, it is possible to satisfactorily suppress static electricity from reliably flying to the circuit board 90.

  In the above-described embodiment, at least a part of the opening is covered with the extending part, but the present invention is not limited to this, and the extending part may be adjacent to the opening. Also in this case, since static electricity can be captured by the extending portion adjacent (close to) the opening, it is possible to suppress static electricity from flying to the circuit board.

In the above embodiment, the present invention is applied to the color printer 1. However, the present invention is not limited to this, and the present invention may be applied to other image forming apparatuses such as a copying machine and a multifunction machine.
In the embodiment, the paper 4 such as a thick paper, a postcard, and a thin paper is used as an example of the recording sheet. However, the present invention is not limited to this, and may be an OHP sheet, for example.

1 is a cross-sectional view illustrating an overall configuration of a color printer. FIG. 6 is a cross-sectional view illustrating a state where a paper feed tray is pulled out. It is a disassembled perspective view which decomposes | disassembles and shows a front chute. They are an enlarged view (a) which expands and shows the inside of a chute cover before a sensor is attached, and an enlarged view (b) which expands and shows the inside of a chute cover after a sensor is attached. It is sectional drawing which shows the structure around a circuit board. It is a disassembled perspective view which shows the extension part of a sheet metal guide, and the opening part of a chute | shoot cover. It is an expansion perspective view which shows the state which covered a part of opening part of the chute | shoot cover with the extension part of the sheet metal guide. It is the expansion perspective view (a) which shows the structure around the hook part of the chute cover in the form which covers all the opening parts with an extension part, and the expansion perspective view (b) which shows the state which covered the opening part with the extension part. . It is an expansion perspective view which shows the form which formed the control part which controls a hook part in the extension part of FIG. It is the expansion perspective view (a) which shows the structure around the opening part covered with the extension part of FIG. 9, and the expansion perspective view (b) which shows the state which covered the opening part with the extension part. It is sectional drawing which shows the structure around the hook part controlled by the control part of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Color printer 2 Housing | casing 3 Front cover 3B Drawer 3C Manual feed port 4 Paper 7 Paper feed tray 18 Manual feed tray 60 Front chute 61 Chute cover 61A Lower wall part 66A Holding rib 66B Support rib 66C Hook part 66D Opening part 70 Sheet metal Guide 73B Extension part 90 Circuit board 91 Photo interrupter 100 Sensor

Claims (3)

A paper feed tray that is detachable from the outlet of the apparatus body;
A manual feed port formed above the pull-out port in the apparatus body;
A sheet metal guide that guides the recording sheet discharged from the paper feed tray and is electrically grounded,
A sensor for detecting a recording sheet inserted into the manual paper feed port;
A resin support frame for supporting the sensor, and an image forming apparatus comprising:
In the lower wall portion of the support frame,
A swingable hook that engages the circuit board of the sensor;
An opening formed around the hook portion so as to allow swinging of the hook portion; and
The image forming apparatus, wherein the sheet metal guide is formed with an extending portion that extends adjacent to the opening or covers at least a part of the opening.   The image forming apparatus according to claim 1, wherein the extension portion is engaged with the hook portion. The image forming apparatus according to claim 1, wherein the extending portion is formed so as to cover all of the opening.

Images