JP2013067508A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain a major hitch from occurring in the oscillation of a pressing plate assembled to a resin frame to be oscillatory.SOLUTION: A large-diameter part 34A is provided in a part which is displaced to a tip side with respect to a base side of a rocking shaft 34. Thereby, a relatively large gap 33B is formed between an outer peripheral surface of the rocking shaft 34 and an inner peripheral surface 33A of a shaft hole 33 on the base side with respect to the large-diameter part 34A of the rocking shaft 34. Thus, even if a position of one frame of a pair of frames 20 is largely displaced with respect to the other frame, the "displacement" can be absorbed by the relatively large gap 33B. This can restrain the major hitch from occurring in the oscillation of the pressing plate 32 assembled to the frames 20 formed of resin to be oscillatory while reducing the manufacturing cost of an image forming apparatus 1.

Description

  The present invention relates to an image forming apparatus such as a printer.

  For example, the image forming apparatus described in Patent Document 1 includes a pair of frames made of resin disposed on both sides in the horizontal direction with an image forming unit interposed therebetween.

JP 2010-44363 A

  By the way, in the image forming apparatus, there are provided a pickup roller for imparting a conveyance force to the sheet conveyed to the image forming unit, and a pressing plate for pressing the sheet against the pickup roller. The pressing plate is usually attached to a metal frame or a paper feed cassette so as to be swingable.

  In contrast, the inventor has newly invented an image forming apparatus in which a pressing plate is slidably assembled to a resin frame as one means for reducing the manufacturing cost of the image forming apparatus. However, in the image forming apparatus according to the novel invention, there is a possibility that a problem described below may newly occur.

  That is, it is difficult for the resin frame to obtain high rigidity compared to the metal frame. For this reason, when the level of the part where the image forming apparatus is installed is low, there is a high possibility that the position of one frame of the pair of frames is largely shifted from the other frame.

  The pressing plate of the image forming apparatus according to the above-described novel invention is configured to be swingably supported by the pair of frames while being disposed between the pair of frames. For this reason, if the position of one frame deviates greatly with respect to the other frame, there is a possibility that the pressing plate may be disturbed.

  In view of the above points, an object of the present invention is to suppress the occurrence of a large hindrance to the swing of a pressing plate that is swingably assembled to a resin frame.

  In order to achieve the above object, the present invention provides an image forming section (2) for forming an image on a sheet, and a pair of frames (resin) disposed on both sides in the horizontal direction across the image forming section (2) ( 20) and a pickup roller (11) that is provided in a space (20C) for placing a sheet set between the pair of frames (20) and applies a conveying force to the sheet, and a pair of frames (20) And a pressing plate (32) that presses the sheet against the pickup roller (11) by swinging, and is attached to either the pair of frames (20) or the pressing plate (32). The shaft hole (33) is provided, and on the other side, a swing shaft (34) protruding toward the shaft hole (33) and fitted in the shaft hole (33) is provided. 34) part shifted from the root side to the tip side It is characterized in that the large-diameter portion having a larger outer diameter than the root side of the outer diameter (34A) is provided.

  As a result, in the present invention, on the base side of the large-diameter portion (34A) of the swing shaft (34), it is between the outer peripheral surface of the swing shaft (34) and the inner peripheral surface of the shaft hole (33). A relatively large gap is formed.

  For this reason, even if the position of one frame (20) deviates greatly with respect to the other frame (20), the “displacement” can be absorbed by the gap. Therefore, it is possible to reduce the manufacturing cost of the image forming apparatus and suppress the occurrence of a major hindrance to the swing of the pressing plate (32) that is swingably assembled to the resin frame (20). .

  Incidentally, the reference numerals in parentheses for each of the above means are examples showing the correspondence with the specific means described in the embodiments described later, and the present invention is indicated by the reference numerals in the parentheses of the above respective means. It is not limited to specific means.

1 is a central sectional view of an image forming apparatus according to an embodiment of the present invention. 2 is a top perspective view showing the arrangement of a pair of frames 20 and their beam members in the image forming apparatus according to the embodiment of the present invention. FIG. FIG. 2 is a bottom perspective view showing the arrangement of a pair of frames 20 and their beam members in the image forming apparatus according to the embodiment of the present invention. 1 is a perspective view of an image forming apparatus according to an embodiment of the present invention. 3 is an exploded perspective view showing a relationship between a pair of frames 20 and a pressing plate 32 in the image forming apparatus according to the embodiment of the present invention. FIG. (A) And (b) is a figure which shows the rocking | fluctuation shaft 34 and the shaft hole 33 in 1st Embodiment of this invention. FIG. 3 is a perspective view showing a pressing plate 32 in the image forming apparatus according to the embodiment of the present invention. FIG. 3 is a side view showing a pressing plate 32 in the image forming apparatus according to the embodiment of the present invention. (A) is a figure which shows the state which the flame | frame 20 shifted | deviated, (b) is a figure which shows the relationship between the rocking | fluctuation shaft 34 and the shaft hole 33 in Fig.9 (a). It is a figure which shows the shaft hole 33 in the image forming apparatus which concerns on 2nd Embodiment of this invention.

  The “embodiment of the invention” described below shows an example of the embodiment. In other words, the invention specific items described in the claims are not limited to the specific means and structures shown in the following embodiments.

In this embodiment, the image forming apparatus according to the present invention is applied to a monochrome laser printer. Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
1. Structure of Image Forming Apparatus As shown in FIG. 1, the image forming apparatus 1 houses an image forming unit 2, a paper feeding device 10, and the like. As shown in FIG. 2, the image forming unit 2, the paper feeding device 10, and the like are directly or indirectly supported by a pair of frames 20 disposed on both sides in the horizontal direction with the image forming unit 2 interposed therebetween. ing. In FIG. 2, the image forming unit 2 is omitted, and the paper feeding device 10 is not illustrated.

  The pair of frames 20 are resin members including a frame main body 20A formed in a substantially rectangular plate shape, wall-shaped reinforcing ribs 20B integrally formed on the outer peripheral portion of the frame main body 20A, and the like. Incidentally, the frame 20 according to the present embodiment is formed of a resin having excellent mechanical strength such as ABS resin.

  The image forming unit 2 is an electrophotographic image forming unit that forms an image on a sheet. That is, as shown in FIG. 1, the image forming unit 2 includes a developing unit including a process cartridge 3, an exposure unit 4, a transfer roller 8, and the like, and a fixing unit 5.

  The process cartridge 3 houses a photosensitive drum 3A on which a developer image is carried, a charger 3B for charging the photosensitive drum 3A, and the like. The transfer roller 8 transfers the developer image carried on the photosensitive drum 3A onto a sheet such as paper.

  The fixing device 5 includes a heating roller 5A that heats the sheet and a pressure roller 5B that presses the sheet against the heating roller 5A. The sheet discharged from the fixing device 5 is discharged from a pair of paper discharge rollers 9 to a paper discharge tray 1A set on the upper surface of the image forming apparatus 1.

  The sheet feeding device 10 is a sheet feeding unit that sends at least one sheet out of one or more sheets placed on the sheet feeding tray 30 to the image forming unit 2. The paper feeder 10 includes a pickup roller 11 and a separation mechanism 12.

  The pickup roller 11 contacts at least one sheet placed on the sheet feeding tray 30 with the sheet positioned at the upper end in the stacking direction, and sends out at least one sheet to the image forming unit 2 side. The separation mechanism 12 includes a separation pad 12A, a separation roller 12B, and the like.

  In this connection, the separation mechanism 12 provides a separation resistance 12B that comes into contact with the lower surface of one or more sheets sent out by the pickup roller 11 and provides separation resistance 12B that comes into contact with the upper surface of the one or more sheets. By applying a conveying force at, one or more sent sheets are separated one by one and sent out to the image forming unit 2.

  Note that one sheet conveyed toward the image forming unit 2 by the sheet feeding device 10 is conveyed to the pair of registration rollers 6. The pair of registration rollers 6 corrects the posture of the one sheet, and then transfers the one sheet at a predetermined timing set in advance on the transfer position of the photosensitive drum 3A, that is, the photosensitive drum 3A. It rushes into a part facing the roller 8.

2. Structure of Frames etc. As shown in FIG. 2, the pair of frames 20 has a first to a fourth so that a space 20 </ b> C for accommodating the paper feed tray 30 and the image forming unit 2 is formed between the pair of frames 20. They are connected by beam members 21-24. The third beam material 23 and the fourth beam material 24 are shown in FIG.

  The first to fourth beam members 21 to 24 are beam portions extending in the horizontal direction intersecting the frame main body 20 </ b> A so as to pass between the pair of frames 20. Then, both ends of the beam members 21 to 24 in the horizontal direction are fixed to the frames 20 by mechanical fastening means such as screws.

  Further, as shown in FIG. 1, the first beam material 21 supports one side of the pickup roller 11, the separation roller 12 </ b> B, and the pair of registration rollers 6. The second beam material 22 supports the exposure device 4. As shown in FIG. 3, the third beam member 23 is fixed to the pair of frames 20 at a portion below the paper feed tray 30.

  The fourth beam member 24 is a wall-shaped beam portion fixed to the pair of frames 20 so as to close the fixing device 5 side in the space 20C. The fourth beam member 24 is integrally formed with a reinforcing wall 24A that increases its rigidity in a lattice shape.

  Further, as shown in FIG. 4, the pair of frames 20 and the space 20 </ b> C are covered with a housing cover 25 that constitutes an external design surface of the image forming apparatus 1. A replenishing port 25 </ b> A for a user to replenish sheets in the paper feed tray 30 is provided on the front side of the image forming apparatus 1 in the housing cover 25. Incidentally, in the present embodiment, the side facing the fourth beam member 24 in the horizontal direction is the front side of the image forming apparatus 1.

3. Structure of Paper Feed Tray The paper feed tray 30 includes a tray body 31 and a pressing plate 32 as shown in FIG. That is, the tray body 31 and the pressing plate 32 are arranged in series along the sheet conveyance path. The one or more sheets placed on the paper feed tray 30 are placed so as to straddle the tray main body 31 and the pressing plate 32.

  Incidentally, in this embodiment, after the sheet placed on the sheet feeding tray 30 is conveyed from the replenishing port 25A side to the fourth beam material 24 side, the conveyance direction is turned about 90 degrees upward. Thereafter, the sheet on which image formation has been completed is discharged toward the replenishing port 25A, that is, toward the front side of the image forming apparatus 1.

  Further, the tray main body 31 can swing between a position where the refill port 25A is closed and a position where the refill port 25A is opened. The tray body 31 is swingably assembled to either the pair of frames 20 or the housing cover 25. Incidentally, in this embodiment, the tray main body 31 is assembled to the pair of frames 20.

  Further, the pressing plate 32 swings upward to cause the pickup roller 11 to press the pressing plate 32, that is, one or more sheets placed on the paper feed tray 30. The pressing plate 32 is swingably supported on the replenishing port 25 </ b> A side of the lower ends of the pair of frames 20.

  That is, as shown in FIG. 5, the shaft hole 33 is provided in the pair of frames 20, and the swing shaft 34 that protrudes toward the shaft hole 33 is provided in the pressing plate 32. The swing shaft 34 is fitted into the shaft hole 33 so as to be rotatable.

  Further, as shown in FIG. 6 (a) or 6 (b), an outer diameter dimension D2 larger than the outer diameter dimension D1 on the root side is provided in a portion of the swing shaft 34 that is shifted from the root side to the tip side. And a large-diameter portion 34A having a perfect circular cross section. The swing shaft 34 and the large diameter portion 34A are integrally formed with a resin such as polystyrene or ABS resin together with the pressing plate 32.

  6A is an example in which the large diameter portion 34A is formed in a columnar shape or a cylindrical shape, and FIG. 6B is an example in which the large diameter portion 34A is spherical. Incidentally, in the large-diameter portion 34A shown in FIG. 6A, the corner portion is rounded 34B so that the portion that is in sliding contact with the inner peripheral surface 33A of the shaft hole 33 is a curved surface.

  On the other hand, the shaft hole 33 is configured by a through hole having a perfect circular cross section through the frame 20. The protruding dimension of the swing shaft 34 is set so that at least the entire large-diameter portion 34 </ b> A of the swing shaft 34 is positioned in the shaft hole 33.

  Further, as shown in FIG. 7 and FIG. 8, a coil spring-like elastic member is provided on the pressing plate 32 on the fourth beam 24 side from the swing shaft 34 and between the third beam member 23 and the pressing plate 32. A member 35 is disposed. The elastic member 35 causes the pressing plate 32 to exert a force for pressing one or more sheets placed on the sheet feeding tray 30 against the pickup roller 11.

4). Features of Image Forming Apparatus According to this Embodiment This embodiment is characterized in that a large-diameter portion 34A is provided in a portion of the swing shaft 34 that is shifted from the root side to the tip side. For this reason, as shown in FIG. 6A or FIG. 6B, the outer peripheral surface of the swing shaft 34 and the inner peripheral surface of the shaft hole 33 on the root side of the large-diameter portion 34A of the swing shaft 34. A relatively large gap 33B is formed between 33A and 33A.

  For this reason, as shown in FIG. 9 (a), even if the position of one frame of the pair of frames 20 is greatly displaced with respect to the other frame, the “deviation” is shown in FIG. 9 (b). As shown, it can be absorbed by the gap 33B. Therefore, it is possible to reduce the manufacturing cost of the image forming apparatus 1, and to suppress the occurrence of a large hindrance to the swinging of the pressing plate 32 that is swingably assembled to the resin frame 20.

  Further, the present embodiment is characterized in that the entire large-diameter portion 34A is positioned in the shaft hole 33 as shown in FIG. As a result, the outer peripheral surface 34B of the large diameter portion 34A and the inner peripheral surface 33A of the shaft hole 33 are in sliding contact with each other, whereby the pressing plate 32 is supported so as to be swingable.

  On the other hand, for example, when the shaft hole 33 is configured as a through hole and the entire large diameter portion 34A is located outside the shaft hole 33, the large diameter portion 34A is provided only at the end of the shaft hole 33. Is configured to be in sliding contact. For this reason, since the contact surface pressure in the sliding contact portion becomes very large, the end portions of the large-diameter portion 34A and the shaft hole 33 may be prematurely worn.

  On the other hand, in the present embodiment, as described above, since the outer peripheral surface 34B of the large diameter portion 34A and the inner peripheral surface 33A of the shaft hole 33 are in sliding contact with each other, it is possible to suppress the contact surface pressure from becoming very large. Therefore, it is possible to prevent the large diameter portion 34A and the shaft hole 33 from being unevenly worn at an early stage.

  In this embodiment, the swing shaft 34 and the pressing plate 32 are integrally formed of resin. As a result, the manufacturing cost of the image forming apparatus 1 can be further reduced.

  By the way, in this embodiment, as shown in FIG. 3, the first to fourth beam members 21 to 24 are portions below the pressing plate 32 in the pair of frames 20 and below the swing shaft 34. It connects with a pair of flame | frame 20 in the site | part except the site | part of the side.

  In other words, in the present embodiment, a beam-like beam material is provided in a portion below the pressing plate 32 and where the pressing plate 32 is assembled, that is, in the vicinity of the swing shaft 34 and the shaft hole 33. The configuration is not made.

  For this reason, since the rigidity in the vicinity of the swing shaft 34 and the shaft hole 33 is lower than the rigidity of other parts, the swing of the pressing plate 32 is shifted when the position of one frame is shifted with respect to the other frame. There is a high possibility that it will cause a major obstacle to movement.

  However, in the image forming apparatus 1 according to the present embodiment, as described above, even if the position of one frame of the pair of frames 20 is largely deviated from the other frame, the “displacement” is absorbed. be able to.

  Accordingly, as in the present embodiment, it is particularly effective to apply the present invention to the image forming apparatus 1 in which no beam-like beam material is provided in the vicinity of the portion where the pressing plate 32 is assembled.

  In the present embodiment, as shown in FIG. 2, since the second beam material 22 is provided above the portion where the pressing plate 32 is assembled, one frame of the pair of frames 20 is provided. It is possible to prevent the shaft hole 33 provided in the other frame from being greatly displaced from the shaft hole 33 provided in the frame.

  By the way, in the present embodiment, the clearance 33B is provided between the shaft hole 33 and the swinging shaft 34 by providing the swinging shaft 34 with the large diameter portion 34A. 33B can be provided.

  That is, for example, without providing the large-diameter portion 34A on the swing shaft 34, the clearance 33B is provided by making the diameter diameter constant from the base side to the tip side and reducing the inner diameter dimension of the shaft hole 33 only partially. It is a configuration. However, in this configuration, it is difficult to form the shaft hole 33 as compared with the shaft hole 33 having a constant inner diameter, so that the manufacturing cost of the image forming apparatus 1 may be increased.

  On the other hand, in this embodiment, since the large-diameter portion 34A is provided on the swing shaft 34, the large-diameter portion 34A is easily formed as compared with the case where the inner diameter dimension of the shaft hole 33 is partially reduced. be able to. Therefore, when both the frame 20 and the pressing plate 32 are resin-molded, it is desirable that the shaft hole 33 has a constant inner diameter and the swing shaft 34 has a large-diameter portion 34A as in this embodiment.

(Second Embodiment)
In the first embodiment, the oscillating shaft 34 and the shaft hole 33 are both formed in a perfect circle. However, in the present embodiment and the like, as shown in FIG. The gap dimension in the vertical direction is larger than the dimension in the horizontal direction.

  Specifically, with the cross-sectional shape of the oscillating shaft 34 being a perfect circle, the cross-sectional shape of the shaft hole 33 is an oval shape whose vertical direction coincides with the major axis direction. It is larger than the dimension in the direction.

  Thereby, in the present embodiment, even when the position of one frame of the pair of frames 20 is largely displaced in the vertical direction with respect to the other frame, the “displacement” can be reliably absorbed. .

  Therefore, it is possible to reduce the manufacturing cost of the image forming apparatus 1, and to suppress the occurrence of a large hindrance to the swinging of the pressing plate 32 that is swingably assembled to the resin frame 20.

  Incidentally, it is rare in reality that the installation location of the image forming apparatus 1 is a complete horizontal plane. Rather, in many cases, the installation location is inclined. For this reason, this embodiment is particularly effective because the position of one frame of the pair of frames 20 is likely to be greatly displaced in the vertical direction with respect to the other frame.

(Other embodiments)
In the above-described embodiment, the present invention is applied to the monochrome laser printer. However, the present invention is not limited to this, and can be applied to, for example, a direct tandem laser printer, an inkjet printer, and the like.

  In the above-described embodiment, the entire large-diameter portion 34A is located in the shaft hole 33. However, the present invention is not limited to this. For example, the entire large-diameter portion 34A is outside the shaft hole 33. A positioned configuration may be used.

In the above-described embodiment, the shaft hole 33 is a through hole. However, the present invention is not limited to this, and the shaft hole 33 may be a blind hole closed on one side.
In the above-described embodiment, the pressing plate 32 is provided with the swing shaft 34, and the pair of frames 20 is provided with the shaft hole 33. However, the present invention is not limited to this, and the pair of frames 20 is rocked. A moving shaft 34 may be provided, and a shaft hole 33 may be provided in the pressing plate 32.

  In addition, the separation mechanism 12 according to the above-described embodiment includes the separation pad 12A, the separation roller 12B, and the like. However, the present invention is not limited to this, and instead of the separation pad 12A, for example, a retard roller May be adopted.

  Further, the present invention is not limited to the above-described embodiment as long as it matches the gist of the invention described in the claims.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 1A ... Paper discharge tray 2 ... Image forming part 3 ... Process cartridge 3A ... Photosensitive drum 4 ... Exposure device 5 ... Fixing device 5A ... Heating roller 5B ... Pressure roller 6 ... Registration roller 8 ... Transfer roller 9 ... Paper discharge roller 10 ... Paper feeding device 11 ... Pickup roller 12A ... Separation pad 12B ... Separation roller 12 ... Separation mechanism 20 ... Frame 20A ... Frame body 20C ... Space 21 ... First beam material 22 ... Second beam material 23 ... Third Beam material 24 ... Fourth beam material 24A ... Reinforcement wall 25 ... Housing cover 25A ... Replenishment port 30 ... Feed tray 31 ... Tray body 32 ... Press plate 33 ... Shaft hole 33A ... Inner peripheral surface 33B ... Gap 34 ... Swing Shaft 34A ... Large diameter part 34B ... Outer peripheral surface 35 ... Elastic member

Claims (6)

An image forming unit for forming an image on a sheet;
A pair of frames disposed on both sides in the horizontal direction across the image forming unit and made of resin;
A pickup roller that is provided in a space for placing a sheet set between the pair of frames and that imparts a conveying force to the sheet;
A pressing plate that is supported by the pair of frames in a swingable manner and presses the sheet against the pickup roller by swinging;
One of the pair of frames and the pressing plate is provided with a shaft hole, and the other is provided with a swing shaft that protrudes toward the shaft hole and is fitted into the shaft hole.
Further, an image forming apparatus characterized in that a large-diameter portion having an outer diameter dimension larger than the outer diameter dimension of the root side is provided in a portion of the swing shaft that is shifted from the root side to the tip side. .   The image forming apparatus according to claim 1, wherein the entire large-diameter portion is located in the shaft hole.   The image forming apparatus according to claim 1, wherein the shaft hole is provided in the pair of frames, and the swing shaft is provided in the pressing plate.   The image forming apparatus according to claim 1, wherein the swing shaft and the pressing plate are integrally formed of resin. A beam portion extending to pass between the pair of frames and connecting the pair of frames is provided,
Further, the beam portion is connected to the pair of frames at a portion of the pair of frames below the pressing plate and excluding a portion below the swing shaft. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.   6. The image forming apparatus according to claim 1, wherein a cross-sectional shape of the shaft hole is formed in an oval shape in which a vertical direction coincides with a major axis direction.

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