JP5018796B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus including a heating member that heats a recording sheet.

  2. Description of the Related Art Conventionally, there has been known an image forming apparatus that includes a rear cover that opens and closes an opening formed on the back side of the apparatus main body, and a heating roller that is disposed to face the opening and heats a recording sheet (patent). Reference 1). In this image forming apparatus, when the rear cover is opened, the heating roller faces the opening.

JP-A-8-185076

  However, in the prior art, when foreign matter such as dust enters the apparatus main body from the opening when the rear cover is opened, there is a possibility that the foreign matter adheres to the heating roller and the image quality deteriorates.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus capable of suppressing deterioration in image quality by suppressing adhesion of foreign matter to a heating roller (heating member).

The present invention that solves the above-described problems is disposed between a heating member that heats a recording sheet, a cover that opens and closes an opening formed in the apparatus main body, and the heating member and the cover, and conveys the recording sheet. An image forming apparatus including a conveyance roller and a shaft portion that supports the conveyance roller, wherein the heating member is disposed so as to face the opening through a gap between the shaft portion and a member facing the shaft portion. The apparatus is provided with an interlocking mechanism for moving the shaft portion in the direction of narrowing the gap in conjunction with the opening operation of the cover, and transports the recording sheet while being sandwiched between the transporting rollers. A pinch roller is further provided, and the pinch roller is movable with the transport roller .

  According to the present invention, when the cover is opened, the gap between the shaft portion supporting the conveyance roller and the member facing the shaft portion is narrowed by the moving shaft portion, so that the inside of the apparatus enters from the opening. This makes it difficult for the foreign matter to pass through the gap, thereby preventing the foreign matter from adhering to the heating member.

  According to the present invention, the gap between the shaft portion that supports the transport roller and the member facing the shaft portion is narrowed by the shaft portion that moves in conjunction with the opening operation of the cover. Adhesion can be suppressed, and deterioration in image quality can be suppressed.

It is sectional drawing which shows the structure of the laser printer which concerns on one Embodiment of this invention. It is explanatory drawing which shows the relationship between a rear cover, a conveyance roller, etc., and is explanatory drawing (a) which shows the state which closed the rear cover, and explanatory drawing (b) which shows the state which opened the rear cover. FIG. 4 is a rear view of the fixing device as viewed from the rear, and is a rear view (a) showing a state when the rear cover is closed, and a rear view (b) showing a state when the rear cover is opened. It is XX sectional drawing (a) of Fig.3 (a), and YY sectional drawing (b) of FIG.3 (b). It is explanatory drawing which shows the gear structure which moves a heating roller and a conveyance roller with a pitch circle, explanatory drawing (a) which shows a state when a rear cover is closed, and explanatory drawing (b) which shows a state when a rear cover is open | released ).

  Next, an embodiment of the present invention will be described in detail with reference to the drawings as appropriate. In the following description, first, the overall configuration of a laser printer as an example of an image forming apparatus will be briefly described, and then details of the characteristic portions of the present invention will be described.

  Further, in the following explanation, explanation will be made in the direction based on the user when using the laser printer. That is, in FIG. 1, the right side is referred to as “front side (front side)”, the left side is referred to as “rear side (back side)”, and the back side in the paper vertical direction is referred to as “right side”. The near side is referred to as the “left side”. In addition, the vertical direction toward the page is defined as the “vertical direction”.

<Overall configuration of laser printer>
As shown in FIG. 1, the laser printer 1 includes a feeder unit 4 for feeding a sheet 3 as an example of a recording sheet in an apparatus main body 2 and an image for forming an image on the fed sheet 3. The formation part 5 etc. are provided.

  An opening 2A is formed on the rear wall of the apparatus body 2, and a rear cover 100 that opens and closes the opening 2A is rotatably provided. The structure of the rear cover 100 will be described in detail later.

  The feeder unit 4 includes a paper feed tray 6 that is detachably attached to the bottom of the apparatus main body 2 and a paper pressing plate 7 provided in the paper feed tray 6. The feeder unit 4 includes a sheet feeding roller 8 and a sheet feeding pad 9 provided above one end of the sheet feeding tray 6, and a sheet provided downstream of the sheet feeding roller 8 in the conveying direction of the sheet 3. Powder removing rollers 10 and 11 are provided. Further, the feeder unit 4 includes a registration roller 12 provided on the downstream side with respect to the paper dust removing rollers 10 and 11.

  In the feeder section 4 configured as described above, the paper 3 in the paper feed tray 6 is brought close to the paper feed roller 8 side by the paper pressing plate 7 and sent out by the paper feed roller 8 and the paper feed pad 9. After passing through the various rollers 10 to 12, the sheets are conveyed one by one to the image forming unit 5.

  The image forming unit 5 includes a scanner unit 16, a process cartridge 17, a fixing device 18, and the like.

  The scanner unit 16 is provided in the upper part of the apparatus main body 2 and includes a laser light emitting unit (not shown), a polygon mirror 19 that is rotationally driven, lenses 20, 21 and reflecting mirrors 22, 23, 24, and the like. . In the scanner unit 16, the laser beam is irradiated on the surface of the photosensitive drum 27 of the process cartridge 17 by high-speed scanning through a path indicated by a chain line in the drawing.

  The process cartridge 17 is disposed below the scanner unit 16 and is configured to be detachably attached to the apparatus main body 2. The process cartridge 17 is mainly composed of a developing cartridge 28 and a drum unit 51.

  The developing cartridge 28 includes a developing roller 31, a layer thickness regulating blade 32, a supply roller 33, and a toner hopper 34. The toner in the toner hopper 34 is stirred by an agitator (not shown) and then supplied to the developing roller 31 by the supply roller 33. At this time, the toner is positively frictionally charged between the supply roller 33 and the developing roller 31. The The toner supplied onto the developing roller 31 enters between the layer thickness regulating blade 32 and the developing roller 31 as the developing roller 31 rotates, and is carried on the developing roller 31 as a thin layer having a constant thickness. The

  The drum unit 51 mainly includes a photosensitive drum 27, a scorotron charger 29, and a transfer roller 30. In the drum unit 51, the surface of the photosensitive drum 27 is uniformly positively charged by the scorotron charger 29 and then exposed by high-speed scanning of the laser beam from the scanner unit 16. Thereby, the potential of the exposed part is lowered, and an electrostatic latent image based on the image data is formed. Next, the rotation of the developing roller 31 causes the toner carried on the developing roller 31 to be supplied to an electrostatic latent image formed on the surface of the photosensitive drum 27 when it contacts and faces the photosensitive drum 27. The The toner is visualized by being selectively carried on the surface of the photosensitive drum 27, whereby a toner image is formed by reversal development.

  Thereafter, the photosensitive drum 27 and the transfer roller 30 are rotationally driven so as to sandwich and convey the sheet 3 between them, and the sheet 3 is conveyed between the photosensitive drum 27 and the transfer roller 30, so that the photosensitive drum 27 and the transfer roller 30 are photosensitive. The toner image carried on the surface of the drum 27 is transferred onto the paper 3.

  The fixing device 18 mainly includes a halogen heater HH, a heating roller 41 as an example of a heating member, a pressure roller 42, a conveyance roller 200, and a pinch roller 300.

  The halogen heater HH is disposed in the cylindrical heating roller 41 and heats the heating roller 41 from the inside.

  The heating roller 41 is a metal member formed in a substantially cylindrical shape, and is rotatably supported by the frame of the fixing device 18. As the heating roller 41, for example, a surface of a cylindrical aluminum member coated with Teflon (PTFE: registered trademark) can be used.

  The pressure roller 42 is pressed against the heating roller 41 by a spring (not shown), and comes into contact with the rotating heating roller 41 to rotate. As the pressure roller 42, for example, a urethane rubber provided around a core bar and the surface of the urethane rubber covered with a Teflon (PTFE: registered trademark) tube can be used.

  The conveyance roller 200 and the pinch roller 300 are disposed so as to be opposed to each other between the heating roller 41 and the rear cover 100 and are rotatably supported by the frame of the fixing device 18. The transport roller 200 and the pinch roller 300 sandwich the paper 3 between them and transport it backward. The structures of the transport roller 200 and the pinch roller 300 will be described in detail later.

  In the fixing device 18 configured as described above, the heating roller 41 is heated by the halogen heater HH, so that the sheet 3 is placed on the sheet 3 while passing between the heating roller 41 and the pressure roller 42. The transferred toner image is heat-fixed. Thereafter, the sheet 3 is conveyed to the paper discharge path 44 by the conveying roller 200 and the pinch roller 300. The paper 3 sent to the paper discharge path 44 is discharged onto a paper discharge tray 46 by a paper discharge roller 45.

<Rear cover structure>
Next, the structure of the rear cover 100 will be described in detail.
The rear cover 100 includes a main body part 110, an extension part 120, and a cam part 130 as an example of a pressing member.

  The main body portion 110 is formed in a plate shape, and the rotation shaft portion 111 provided at one end portion (lower end portion) of the main body portion 110 is rotatably supported by the apparatus main body 2, thereby swinging with respect to the apparatus main body 2. It moves and opens and closes the opening 2A.

  The extension part 120 is formed so as to extend from the main body part 110 into the apparatus main body 2. Specifically, as shown in FIG. 2A, the extending portion 120 is formed so as to extend outward from a circle in contact with the shaft portion 210 of the conveyance roller 200 described later with the center of the rotation shaft portion 111 as the center. Has been.

  The cam portion 130 is formed so as to protrude from the upper surface (surface on the conveying roller 200 side) of the distal end portion of the extending portion 120, and the pressing surface 131 for pressing the shaft portion 210 of the conveying roller 200 is viewed from the side. It is formed in an arc shape. In addition, it is desirable to provide the extension part 120 and the cam part 130 described above one by one at positions corresponding to both ends of the shaft part 210 in order to stably push the shaft part 210.

  As shown in FIGS. 2A and 2B, the rear cover 100 configured as described above is regulated by a regulating member (not shown) so as to rotate by a predetermined angle. 2B, when the rear cover 100 is opened, the shaft portion 210 of the conveying roller 200 is pressed upward together with the pinch roller 300 by the pressing surface 131 of the cam portion 130. ing.

<Conveyor roller and pinch roller structure>
Next, the structures of the transport roller 200 and the pinch roller 300 will be described in detail.

  As shown in FIG. 3A, the transport rollers 200 are arranged at a plurality of intervals in the left-right direction (the width direction of the paper 3). The plurality of conveyance rollers 200 are formed in a cylindrical shape, and a shaft portion 210 that supports each conveyance roller 200 is provided coaxially with each conveyance roller 200 so as to penetrate through each conveyance roller 200.

  The shaft portion 210 is formed to have a length that penetrates the left and right side wall portions 181 of the frame 180 of the fixing device 18. The shaft portion 210 is disposed so as to face the upper wall portion 182 of the frame 180 in the vertical direction, as shown in FIGS. Thus, a gap G having a vertical length L1 is formed between the shaft portion 210 and the upper wall portion 182 of the frame 180 (a member facing the shaft portion 210).

  Here, as shown in FIG. 4A, the frame 180 is formed in a substantially cylindrical shape having left and right side walls 181, an upper wall 182, and a lower wall 183. Openings 180A and 180B for allowing the paper 3 to pass therethrough are formed on the front side and the rear side. The opening 2A (see FIG. 1) of the apparatus main body 2, the opening 180B on the rear side of the frame 180, the gap G described above, and the heating roller 41 are arranged in a straight line. Accordingly, the heating roller 41 faces the opening 2A through the gap G and the opening 180B.

  In addition, the left and right side wall portions 181 of the frame 180 are formed with groove portions 181A that support the shaft portion 210 so as to be pivotable and move up and down. As a result, as shown in FIGS. 4B and 3B, when the shaft portion 210 protruding outward from the frame 180 is pushed upward by the pressing surface 131 of the cam portion 130 described above, the shaft portion 210 is It moves in the direction (upward) to narrow the gap G described above.

  That is, in the present embodiment, the shaft portion 210 is narrowed in the direction of narrowing the gap G in conjunction with the opening operation of the rear cover 100 by the groove portion 181A described above and the cam portion 130 provided in the extending portion 120 of the rear cover 100. An interlocking mechanism to be moved is configured.

  The lower portion of the opening 180B on the rear side of the frame 180 is covered with a shielding plate 184. The shielding plate 184 is formed in such a size as to cover a gap formed between the shaft portion 210 and the lower wall portion 183 of the frame 180 even when the shaft portion 210 is located at the upper end of the groove portion 181A. Yes.

  As shown in FIG. 3A, a plurality of pinch rollers 300 are provided corresponding to the plurality of transport rollers 200, and are arranged above the respective transport rollers 200. Each pinch roller 300 includes a pair of disk-shaped roller main body portions 301 arranged at a distance from each other, and a rotation shaft formed integrally with the roller main body portion 301 so as to penetrate the center of the roller main body portion 301. Unit 302.

  Each pinch roller 300 includes a plurality of notches 182A formed so as to be recessed forward from the rear surface of the upper wall 182 of the frame 180, as shown in FIGS. 3 (a) and 4 (a). Is arranged. The cutout portion 182A is formed so as to penetrate in the vertical direction, and support grooves 182B that open to the inside and penetrate upward are formed on the respective inner surfaces of the left and right sides.

  Then, both end portions of the rotating shaft portion 302 of the pinch roller 300 are supported by a pair of support grooves 182B so as to be rotatable and vertically movable. A linear spring 310 (elastic member) that urges the rotating shaft 302 of the pinch roller 300 to the pair of support grooves 182B is provided on the upper surface of the upper wall portion 182 of the frame 180.

  As described above, the pinch roller 300 is supported by the upper wall portion 182 of the frame 180, so that the pinch roller 300 can be moved up and down together with the conveying roller 200.

  Further, a heating gear 41G and a conveying gear 200G as shown in FIG. 5A are integrally fixed to one end portion of the heating roller 41 and one end portion of the shaft portion 210 of the conveying roller 200. . The heating gear 41G is provided coaxially with the heating roller 41 and rotates integrally with the heating roller 41.

  The transport gear 200G is provided coaxially with the transport roller 200 and rotates integrally with the transport roller 200. Between the heating gear 41G and the conveying gear 200G, a first idle gear G1 meshing with the heating gear 41G and a second idle gear G2 meshing with the first idle gear G1 and the conveying gear 200G are arranged. It is installed. Therefore, when a driving force from a driving source such as a motor (not shown) is transmitted to one gear (a gear that does not move in the direction orthogonal to the rotation axis: for example, the heating gear 41G), all the gears rotate. It has become.

  The first idle gear G1 is rotatably supported by the frame 180 of the fixing device 18. The second idle gear G2 is rotatably supported by the plate-shaped support member SP together with the transport gear 200G.

  The support member SP can rotate the first bearing portion SP1 that rotatably supports the shaft portion 210 of the transport gear 200G (the shaft portion 210 of the transport roller 200) and the rotation shaft portion G21 of the second idle gear G2. A second bearing portion SP2 to be supported is formed.

  As an example of an urging member that presses the second idle gear G2 against the first idle gear G1 via the support member SP between the second bearing portion SP2 of the support member SP and the frame 180 of the fixing device 18. A coil spring 400 is provided.

  By configuring the gears as described above, even when the transport gear 200G moves upward as the transport roller 200 moves upward as shown in FIG. The working gear 200G and the second idle gear G2 are maintained in mesh with each other by being connected by the support member SP. At this time, the second idle gear G2 rolls around the first idle gear G1 while meshing with the first idle gear G1 by being urged by the coil spring 400 to the first idle gear G1. Therefore, even if the transport roller 200 moves up and down, it is possible to reliably maintain the gears in mesh.

Next, the operation of the transport roller 200 and the like according to the opening and closing of the rear cover 100 will be described.
2A and 2B, when the rear cover 100 is opened, the shaft portion 210 of the transport roller 200 is pressed upward by the cam portion 130 of the rear cover 100, and the transport roller 200 and the pinch roller 300 are integrated. Move upwards. As a result, as shown in FIGS. 3A and 3B, the vertical length of the gap G between the shaft portion 210 and the upper wall portion 182 of the frame 180 is narrowed from L1 to L2. Thereby, foreign matter such as dust entering from the opening 2 </ b> A of the apparatus main body 2 can be prevented from entering around the heating roller 41.

  In addition, when the rear cover 100 is closed, the pinch roller 300 and the transport roller 200 can be integrally moved downward by the urging force of the wire spring 310 to automatically return to the initial position.

According to the above, the following effects can be obtained in the present embodiment.
Since the gap G between the shaft portion 210 of the transport roller 200 and the upper wall portion 182 of the frame 180 is narrowed by the shaft portion 210 that moves in conjunction with the opening operation of the rear cover 100, the entry of foreign matter from the gap G is prevented. Therefore, it is possible to suppress the adhesion of foreign matter to the heating roller 41, and it is possible to suppress a decrease in image quality.

  Since the second idle gear G2 rolls around the first idle gear G1 as the transport roller 200 moves, the heating roller 41 and the transport roller 200 can be rotated by one drive source. In addition, it is possible to prevent the gears from coming off as the rear cover 100 is opened and closed.

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 above embodiment, the interlocking mechanism is configured by the groove portion 181A formed in the frame 180 and the cam portion 130 provided in the extending portion 120 of the rear cover 100, but the present invention is not limited to this. . For example, instead of the groove portion 181A in the above-described embodiment, a swingable swing arm may be employed, and the shaft portion of the transport roller may be rotatably supported by the tip end portion of the swing arm. In this case, the cam arm 130 may be configured to press the swing arm.

  Further, instead of the extension part 120 and the cam part 130, a detection unit such as an optical sensor that detects opening and closing of the rear cover, a cylinder that presses the shaft part, and a control device that controls the cylinder based on a signal from the detection unit And may be adopted.

  In the above-described embodiment, the pinch roller 300 is moved together with the transport roller 200. However, the present invention is not limited to this. For example, the transport roller may be configured to roll around a pinch roller that does not move. Good.

In the above embodiment, the member facing the shaft portion is the upper wall portion 182 of the frame 180, but the present invention is not limited to this, and may be other components other than the lower wall portion of the frame and the fixing device. .
In the embodiment, the rear cover 100 is used as the cover. However, the present invention is not limited to this, and for example, a front cover may be used depending on the position of the fixing device.

In the above-described embodiment, the heating roller 41 is employed as the heating member. However, the present invention is not limited to this. For example, a cylindrical fixing film that is slidably supported by a guide may be used.
In the above-described embodiment, the coil spring 400 is employed as the biasing member. However, the present invention is not limited to this, and for example, a torsion spring or a leaf spring may be employed.

In the above embodiment, the present invention is applied to the laser 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 3 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.

DESCRIPTION OF SYMBOLS 1 Laser printer 2 Apparatus main body 2A Opening part 3 Paper 41 Heating roller 100 Rear cover 110 Main body part 120 Extension part 130 Cam part 180 Frame 181A Groove part 182 Upper wall part 200 Conveyance roller 210 Shaft part 300 Pinch roller 310 Wire spring G Gap

Claims (4)

A heating member for heating the recording sheet;
A cover for opening and closing an opening formed in the apparatus body;
A conveying roller disposed between the heating member and the cover, for conveying the recording sheet, and a shaft portion for supporting the conveying roller;
The image forming apparatus in which the heating member is arranged to face the opening through a gap between the shaft and a member facing the shaft.
In conjunction with the opening operation of the cover, an interlocking mechanism for moving the shaft portion in the direction of narrowing the gap is provided ,
It further comprises a pinch roller that sandwiches and conveys the recording sheet with the conveying roller,
The image forming apparatus , wherein the pinch roller is movable together with the conveying roller . A heating member for heating the recording sheet;
A cover for opening and closing an opening formed in the apparatus body;
A conveying roller disposed between the heating member and the cover, for conveying the recording sheet, and a shaft portion for supporting the conveying roller;
The image forming apparatus in which the heating member is arranged to face the opening through a gap between the shaft and a member facing the shaft.
In conjunction with the opening operation of the cover, an interlocking mechanism for moving the shaft portion in the direction of narrowing the gap is provided ,
The heating member is a rotatable heating roller,
A heating gear provided coaxially with the heating roller and rotating integrally with the heating roller;
A conveyance gear provided coaxially with the conveyance roller and rotating integrally with the conveyance roller;
A first idle gear meshing with the heating gear;
A second idle gear meshing with the first idle gear and the transport gear;
A support member that rotatably supports the transport gear and the second idle gear;
An urging member that presses the second idle gear against the first idle gear,
The image forming apparatus , wherein the second idle gear rolls around the first idle gear as the conveying roller moves . A pinch roller that sandwiches and conveys the recording sheet with the conveying roller;
The image forming apparatus according to claim 2, wherein the pinch roller is movable together with the conveying roller. The cover includes a main body part that is swingably supported by the apparatus main body and capable of opening and closing the opening, and an extending part that extends from the main body part into the apparatus main body.
The interlocking mechanism is
4. The image formation according to claim 1 , further comprising: a pressing member that is provided in an extending portion of the cover and presses the shaft portion in a direction in which the gap is narrowed. 5. apparatus.

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