JP7238563B2 - HOLDER UNIT AND IMAGE FORMING APPARATUS INCLUDING THE SAME - Google Patents

Description

The present invention relates to a holder unit that holds rollers and an image forming apparatus that includes the holder unit.

2. Description of the Related Art In an image forming apparatus such as a printer, a conveying system that conveys a sheet such as paper by rollers employs a configuration in which a roller or a frame is pressed against an object (for example, an opposing roller) by a compression spring (for example, Patent Document 1). , 2). Although Patent Literatures 1 and 2 do not disclose the details of the method of holding the compression spring, for example, a method of press-fitting the compression spring into a boss provided on the frame and fixing it is common.

JP-A-5-178485 JP-A-2002-145472

However, if the compression spring is only press-fitted into the boss, for example, when the unit holding the rollers by the frame body is attached to or detached from the apparatus main body (unit replacement work), the compression spring can be easily caught by other members. I'm off. In this case, it is necessary to press-fit the compression spring again, but this operation takes time, and there is a concern that the replacement time of the unit will be lengthened, resulting in a decrease in workability. Therefore, it is desired to realize a configuration in which the compression spring is difficult to come off from the frame while facilitating attachment of the compression spring to the frame.

Further, if the posture of the compression spring held by the frame is unstable, the compression spring may collide with another member and be buckled and deformed when the unit is replaced, resulting in an assembly failure. For this reason, it is also desired to realize a configuration in which the posture of the compression spring is stabilized by the frame.

SUMMARY OF THE INVENTION In view of the above problems, the present invention facilitates attachment of a compression spring to a frame while making it difficult for the compression spring to come off the frame, and stabilizes the posture of the compression spring to reduce assembly defects. It is an object of the present invention to provide a holder unit and an image forming apparatus provided with the holder unit.

In order to achieve the above object, the holder unit of the present invention includes a roller, a frame holding the roller on one end side and supported swingably at the one end side, and attaching the one end side of the frame body. a compression spring biased to urge the roller against the object. The frame includes a pair of side plates that support the rotation shaft of the roller, a pair of first and second connection plates that are parallel to the rotation shaft and connect the side plates, and the second side plate on the one end side. and a mounting portion provided on one connecting plate for mounting the compression spring. The mounting portion has a support surface that supports the compression spring, a boss projecting from the support surface and through which the compression spring is inserted, and a locking portion that locks an end portion of the compression spring. . The compression spring includes a helical portion that extends helically and is inserted through the boss, and a helical portion that extends radially outward from an end portion of the helical portion and is fitted into the locking portion so that the compression spring is mounted on the support surface. It has a bent portion positioned at a mounting position, and a hook portion provided at the tip of the bent portion and locked by the locking portion. The inside diameter of the spiral portion is larger than the outside diameter of the boss. At the mounting position of the compression spring, the helical portion inserted through the boss moves in the radial direction, and the inner peripheral surface of the helical portion comes into contact with the boss.

Since the end portion of the compression spring is locked by the locking portion of the mounting portion, the compression spring is less likely to come off from the mounting portion. Moreover, since the inner diameter of the helical portion of the compression spring is larger than the outer diameter of the boss, the compression spring can be easily inserted into the boss compared to press-fitting. In other words, it is possible to make it difficult to remove the compression spring from the frame while facilitating the attachment of the compression spring to the frame. Further, at the mounting position of the compression spring, the helical portion inserted through the boss moves in the radial direction and the inner peripheral surface of the helical portion comes into contact with the boss, so that the posture of the compression spring can be stabilized by the frame. . As a result, it is possible to reduce the situation in which the compression spring undergoes buckling deformation at the time of replacement of the holder unit, thereby reducing the occurrence of assembly failure (installation failure).

1 is a cross-sectional view showing a schematic configuration of an image forming apparatus according to an embodiment of the present invention; FIG. 2 is an enlarged cross-sectional view showing a configuration around a pickup roller in FIG. 1; FIG. 10 is a perspective view of a paper feed holder of Reference Example 1. FIG. FIG. 4 is a perspective view showing an enlarged main portion of FIG. 3; 10 is a perspective view of a paper feed holder of Reference Example 2. FIG. FIG. 6 is a perspective view showing an enlarged main portion of FIG. 5; 4 is a plan view of a paper feed holder that is attached to and detached from the image forming apparatus; FIG. FIG. 8 is a plan view showing an enlarged main portion of FIG. 7; 4 is a perspective view showing an appearance of a compression spring attached to the paper feed holder; FIG. FIG. 4 is a rear view of the boss of the paper feed holder as viewed from the side of the feed roller; FIG. 11 is a perspective view of the boss in FIG. 10 as seen obliquely from above; It is the perspective view which looked at the said compression spring from the diagonally downward direction in the state which attachment to the support plate was completed. It is a side view of the said compression spring. 4 is a cross-sectional view of the paper feed holder in a state where the compression spring has been completely attached to the support plate; FIG. Figure 15 is a side view of the compression spring of Figure 14 with the frame removed;

[1. Configuration of Image Forming Apparatus]
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a schematic configuration of an image forming apparatus 100 according to an embodiment of the invention. The image forming apparatus 100 is a tandem color copier. In an apparatus main body 100a of the image forming apparatus 100, four image forming units Pa, Pb, Pc and Pd are arranged in order from the left side in FIG. The image forming units Pa to Pd are provided corresponding to images of four different colors (yellow, magenta, cyan and black). Black images are sequentially formed.

Photoreceptor drums 1a, 1b, 1c, and 1d carrying visible images (toner images) of respective colors are arranged in these image forming units Pa to Pd, and rotate counterclockwise in FIG. An intermediate transfer belt 8 is provided adjacent to each of the image forming portions Pa to Pd. The toner images formed on these photoreceptor drums 1a to 1d are sequentially transferred and superimposed on an intermediate transfer belt 8 that moves while being in contact with each of the photoreceptor drums 1a to 1d. is transferred onto a sheet 26 such as paper by the action of , and further fixed onto the sheet 26 by the fixing device 7 . After that, the sheet 26 is ejected from the apparatus main body 100a. An image forming process is performed on each of the photosensitive drums 1a to 1d while rotating the photosensitive drums 1a to 1d clockwise in FIG. The image forming apparatus 100 will be described in more detail below.

A mounting portion 101 is provided in the lower portion of the apparatus main body 100a, and a paper feed cassette 10 containing sheets 26 is detachably mounted in the mounting portion 101. As shown in FIG. The paper feed cassette 10 is configured to be detachable from the front of the apparatus main body 100a (the front side with respect to the plane of FIG. 1).

Sheets 26 are stacked on a sheet stacking plate 28 of the paper feed cassette 10 . Feeding of the sheet 26 is started by rotating the pickup roller 29 while the upper surface of the sheet 26 is pressed against the pickup roller 29 with a predetermined pressure. Only the uppermost sheet of the plurality of sheets 26 is separated by the feeding roller pair 30 and conveyed toward the sheet conveying path 11 . After passing through the sheet conveying path 11, the sheet 26 reaches the pair of registration rollers 14 and is conveyed to the nip portion between the secondary transfer roller 9 and the driving roller 13 of the intermediate transfer belt 8 in time with the image forming timing. .

A dielectric resin sheet is used for the intermediate transfer belt 8, and a seamless belt is mainly used. A cleaning blade 17 for removing toner remaining on the surface of the intermediate transfer belt 8 is arranged downstream of the secondary transfer roller 9 in the moving direction of the intermediate transfer belt 8 .

The image reading section 20 is arranged in the upper portion of the apparatus main body 100a, and reads an original image at the time of copying and converts it into image data.

Next, the image forming units Pa to Pd will be described. Charging devices 2a, 2b, 2c and 2d, an exposure device 4, developing devices 3a, 3b, 3c and 3d, and cleaning devices 5a, 5b, 5c and 5d are provided around and below the photosensitive drums 1a to 1d. is provided.

When image data is input from the image reading unit 20, first, the surfaces of the photosensitive drums 1a to 1d are uniformly charged by the charging devices 2a to 2d, and then the exposure device 4 irradiates a light beam to each photosensitive drum. Electrostatic latent images corresponding to image data are formed on the drums 1a to 1d. The developing devices 3a to 3d are provided with developing rollers (developer bearing members) arranged to face the photosensitive drums 1a to 1d. Each of the developing devices 3a to 3d is filled with a predetermined amount of two-component developer containing yellow, magenta, cyan and black toners. The toner is supplied onto the photosensitive drums 1a to 1d by developing rollers, thereby forming a toner image corresponding to the electrostatic latent image.

The toner images on the photosensitive drums 1a to 1d are primarily transferred onto the intermediate transfer belt 8. As shown in FIG. After that, toner remaining on the surfaces of the photosensitive drums 1a to 1d is removed by cleaning devices 5a to 5d.

The intermediate transfer belt 8 is stretched over a driven roller 12 and a driving roller 13 . When the intermediate transfer belt 8 starts rotating in the counterclockwise direction with the rotation of the drive roller 13, the sheet 26 is moved from the registration roller pair 14 at a predetermined timing to the nip portion between the secondary transfer roller 9 and the intermediate transfer belt 8. The full-color image is secondarily transferred onto the sheet 26 at the nip portion.

The sheet 26 is conveyed to the fixing device 7 and heated and pressurized when passing through the nip portion (fixing nip portion) of the fixing roller pair 15 . As a result, the toner image is fixed on the surface of the sheet 26 to form a desired full-color image. After that, the sheet 26 passes through the pair of conveying rollers 16 and is distributed in the conveying direction by the conveying guide member 21 arranged at the branch portion of the sheet conveying path 19, and is sent to the double-sided conveying path 23 to be double-sided copied. later), it is discharged to the output tray 18 via the output roller pair 24 .

The sheet conveying path 19 is configured to communicate with the discharge tray 18 or the double-sided conveying path 23 on the downstream side of the conveying roller pair 16 .

Next, the configuration around the pickup roller 29 will be described. FIG. 2 is a cross-sectional view showing an enlarged configuration around the pickup roller 29 in FIG.

A pickup roller 29 sends out the sheet 26 accommodated in the paper feed cassette 10 . The feeding roller pair 30 is arranged to face the feed roller 31 that conveys the sheet 26 sent out by the pickup roller 29 and the feed roller 31, and is a nip portion for conveying the sheet 26 by pressing the feed roller 31. and a retard roller 32 forming a . A driving force transmission gear 33 is arranged between the feed roller 31 and the pickup roller 29 to transmit the rotational driving force of the feed roller 31 to the pickup roller 29 . The pickup roller 29, the feed roller 31, and the driving force transmission gear 33 are held by the paper feed holder 200, and the details of the paper feed holder 200 will be described later.

The feed roller 31 is attached to a rotating shaft that is connected to a drive motor (driving source) (not shown), and is configured to rotate by driving force from the drive motor. The retard roller 32 is configured to be rotated by being pressed against the feed roller 31 . In addition, the retard roller 32 is supported by a rotating shaft via a torque limiter (not shown), stops until a predetermined torque is applied, and when a torque exceeding the predetermined torque is applied, the feed roller 31 It is configured to be driven to rotate. As a result, feeding of the sheet 26 is started by rotating the pickup roller 29 in a state of being pressed against the sheet 26, and when a plurality of sheets 26 are fed simultaneously by the pickup roller 29, the action of the torque limiter causes the sheet 26 to be fed. The sheet 26 is separated by the feed roller 31 and the retard roller 32 while the retard roller 32 is stopped, and only the uppermost sheet 26 is sent out toward the sheet conveying path 11 .

[2. About the paper feed holder]
Next, the paper feed holder 200 will be described. The paper feed holder 200 is a holder unit that holds the pickup roller 29 and the feed roller 31, and is detachably arranged at a predetermined position on the paper discharge side of the paper feed cassette 10 in the apparatus main body 100a.

For example, when at least one of the pickup roller 29 and the feed roller 31 wears out due to use and needs to be replaced, the operator opens the cover on the right side of the apparatus main body 100a shown in FIGS. After pulling out the holding unit (retard holder) of the roller 32, the used paper feed holder 200 is pulled out and a new paper feed holder 200 is inserted from the pickup roller 29 side, whereby the replacement work can be performed.

Here, before describing the details of the paper feed holder 200 of the present embodiment, a configuration that is a premise of the paper feed holder 200 of the present embodiment will be described as a reference example. FIG. 3 is a perspective view of the paper feed holder 200a of Reference Example 1, and FIG. 4 is an enlarged perspective view of the main part of FIG. The paper feed holder 200a has a pickup roller 29, a feed roller 31, a frame 201, and a compression spring 202a.

The feed roller 31 is connected to a drive motor via a drive gear 31 a , and the drive gear 31 a is connected to the gear 29 a of the pickup roller 29 via a driving force transmission gear 33 . As a result, when the feed roller 31 rotates, its rotational driving force is transmitted to the pickup roller 29 via the driving force transmission gear 33, and the pickup roller 29 rotates.

Frame 201 holds pickup roller 29 , feed roller 31 , and driving force transmission gear 33 . This frame 201 has a boss 211 and a support plate 212 . The boss 211 positions the compression spring 202a by press-fitting the compression spring 202a. The support plate 212 is a flat plate that supports the boss 211 .

The compression spring 202a is composed of, for example, a coil spring. One end of the compression spring 202 a is press-fitted into a boss 211 of the frame 201 and held by the frame 201 . The other end side of the compression spring 202a abuts on the frame or transport guide inside the apparatus main body 100a when the paper feed holder 200a is attached to the apparatus main body 100a. As a result, the compression spring 202a can bias the paper feed holder 200a with the frame or the like as a fulcrum, whereby the pickup roller 29 can be pressed against the paper.

In the configuration in which the compression spring 202a is press-fitted into the boss 211 as in Reference Example 1, not only is it difficult to attach the compression spring 202a to the boss 211, but it is also difficult to compress the paper feed holder 200a when replacing the paper feed holder 200a with respect to the apparatus main body 100a. As described above, when the spring 202a is caught on another member, it is easily disengaged, resulting in a decrease in workability.

5 is a perspective view of a paper feed holder 200b of Reference Example 2, and FIG. 6 is an enlarged perspective view showing the main part of FIG. In the paper feed holder 200b of Reference Example 2, instead of the compression spring 202a of Reference Example 1, a compression spring 202b with a bent end is used. A wall portion 213 for accommodating the compression spring 202b is formed on the support plate 212, and a part of the wall portion 213 is cut away to sandwich the support plate 212 between the bent ends 202b ₁ of the compression spring 202b. ing. Note that in the paper feed holder 200 b of Reference Example 2, the pickup roller 29 and the feed roller 31 are covered with the frame 201 .

In the configuration of Reference Example 2, since the end portion 202b ₁ of the compression spring 202b is hooked on the support plate 212, the compression spring 202b is less likely to come off _. Since it is only surrounded by 213 and is not supported at all, the posture of the compression spring 202b is not stable. As a result, when the paper feed holder 200b is replaced with respect to the apparatus main body 100a, the compression spring 202b is likely to collide with other members and be buckling-deformed, resulting in assembly failure.

Therefore, in the paper feed holder 200 of the present embodiment, by adopting the following configuration, the problems of the reference examples 1 and 2 are improved. The paper feed holder 200 of this embodiment will be specifically described below.

FIG. 7 is a plan view of the paper feed holder 200 (holder unit) of this embodiment, and FIG. 8 is an enlarged plan view showing the main part of FIG. In addition, in FIG. 7, in order to clearly distinguish between the roller portion (including the gear) and the frame, the roller portion is hatched for convenience. 8, for the sake of convenience, the illustration of the compression spring 202 shown in FIG. 7 is omitted.

The paper feed holder 200 of this embodiment includes a pickup roller 29 , a feed roller 31 , a frame 201 and compression springs 202 . The frame 201 holds the pickup roller 29 on one end and the feed roller 31 on the other end. Further, the frame body 201 is supported by the apparatus main body 100a via bosses 201M so that the one end side can swing. The compression spring 202 is a coil spring that presses the pickup roller 29 on the one end side against an object (for example, the sheet 26) by urging the one end side of the frame 201. As shown in FIG.

The frame body 201 has a pair of side plates 201 a and 201 b, a pair of first and second connection plates 201 c and 201 d, and a mounting portion 210 . The pair of side plates 201a and 201b are arranged to face each other and support the rotation shaft of the pickup roller 29, respectively. The first connecting plate 201c and the second connecting plate 201d extend parallel to the rotational axis of the pickup roller 29 (extend in the horizontal direction in FIG. 7) and connect the pair of side plates 201a and 201b. Specifically, the first connecting plate 201c connects the ends of the pair of side plates 201a and 201b on the pickup roller 29 side, and the second connecting plate 201d connects the ends of the pair of side plates 201a and 201b on the feed roller 31 side. connecting the parts.

The attachment portion 210 is a portion to which the compression spring 202 is attached. The mounting portion 210 includes a support surface 212b that supports the compression spring 202, a boss 211 projecting from the support surface 212b and through which the compression spring 202 is inserted, and an end portion of the compression spring 202 (flexion portion 222 described later). It has a locking portion 214 to be locked and a rib 231 to be described later. The support surface 212 b is the upper surface of the support plate 212 . The locking portion 214 includes the support plate 212 described above.

FIG. 9 is a perspective view showing the appearance of the compression spring 202. FIG. In this embodiment, the compression spring 202 has a helical portion 221 and a bent portion 222 . The spiral portion 221 is a portion that extends spirally and is inserted through the boss 211 . In this embodiment, the inner diameter Ds (mm) of the spiral portion 221 is larger than the outer diameter Db (mm) of the boss 211 . Due to this dimensional relationship, even if the spiral portion 221 is inserted through the boss 211, it does not take a form of being press-fitted, so that the insertion through the boss 211 is facilitated.

The bent portion 222 extends radially outward from the end of the helical portion 221 and is fitted into the locking portion 214 to position the compression spring 202 at the mounting position on the support surface 212b. The bent portion 222 has a first extension portion 222b, a second extension portion 222a, a third extension portion 222c, and a hook portion 222c ₁ to be locked by the locking portion 214. and has elasticity as a whole.

The first extending portion 222b extends radially outward from one end of the spiral portion 221 . The second extending portion 222 a extends in the direction along the central axis AX of the spiral portion 221 from the end portion of the first extending portion 222 b opposite to the connection side with the spiral portion 221 . The third extending portion 222c extends radially inward from the end portion of the second extending portion 222a opposite to the connecting side with the first extending portion 222b. The hook portion 222 c ₁ is connected to the end (tip) of the third extension 222 c on the side opposite to the connection side with the second extension 222 a and is positioned at the tip of the bent portion 222 .

10 is a rear view of the boss 211 of the paper feed holder 200 viewed from the side of the feed roller 31, and FIG. 11 is a perspective view of the boss 211 of FIG. 10 viewed obliquely from above. A rib 231 of the mounting portion 210 is formed integrally with the support plate 212 at a position on the opposite side (rear surface) of the boss 211 with respect to the support plate 212 . The rib 231 is provided so as to incline from the side surface 201c ₁ of the first connecting plate 201c toward the inner side. In this configuration, when the compression spring 202 is attached to the attachment portion 210 (particularly the support plate 212), a portion (hook portion 222c ₁ ) of the bent portion 222 of the compression spring 202 is brought into contact with the rib 231, and the compression spring 202 is While rotating, the hook portion 222c ₁ of the bent portion 222 is slid along the inclined surface of the rib 231, thereby moving the bent portion 222 (hook portion 222c ₁ ) to the predetermined mounting position (locking position) P of the support plate 212. can lead to From this, it can be said that the shape of the rib 231 is such that the curved portion 222 (hook portion 222c ₁ ) tapers in the sliding direction toward the mounting position P as the compression spring 202 rotates. Although the mounting position P is the same position as the tip portion 231a of the rib 231 here, it may be a position away from the tip portion 231a in the rotation axis direction of the pickup roller 29. FIG.

Further, the support plate 212 is formed with a recessed portion 232 into which the hook portion 222c ₁ enters when the hook portion 222c ₁ passes over the tip portion 231a of the rib 231 in the sliding direction. When the hook portion 222c ₁ enters the recessed portion 232, the hook portion 222c ₁ is locked by the recessed portion 232. Therefore, unless the locking is intentionally released, the hook portion 222c ₁ slides in the direction opposite to the sliding direction. won't go back. In addition, although the recessed portion 232 is formed, for example, in the shape of being recessed in the depth direction of the paper surface of FIG.

Next, a method for attaching the compression spring 202 to the paper feed holder 200 will be described.

First, the helical portion 221 of the compression spring 202 is inserted through the boss 211 and a portion of the bent portion 222 (hook portion 222 c ₁ ) is brought into contact with the rib 231 . Then, in this state, the compression spring 202 is rotated around the central axis AX. As a result, the hook portion 222c ₁ slides toward the mounting position P while contacting the rib 231 . At the same time, the second extending portion 222a of the bent portion 222 approaches the side surface 212a of the support plate 212 .

Further, when the compression _spring 202 is rotated and the hook portion 222c ₁ passes over the tip portion 231a of the rib 231 in the sliding direction, as shown in FIG. As a result, the compression spring 202 is locked to the support plate 212 (locking portion 214) at the mounting position P (see FIG. 10). In addition, when the hook portion 222c ₁ enters the recessed portion 232, the second extending portion 222a of the bent portion 222 contacts the side surface 212a of the support plate 212, and at the same time, the first extending portion 222b and the third extending portion 222 c sandwich the support plate 212 . This completes the attachment of the compression spring 202 to the support plate 212 (attachment portion 210).

Here, in this embodiment, the following dimensional relationships are satisfied. That is, as shown in FIG. 10, the rotation axis of the pickup roller 29 when the mounting portion 210 of the frame 201 is viewed from the other end side (the feed roller 31 side) opposite to the one end side (the pickup roller 29 side). A (mm) is the distance from the tip end portion 231a of the rib 231 to the side end portion 211a ₁ of the boss 211 in the direction parallel to (horizontal direction in FIG. 10). Here, the side end portion 211a ₁ of the boss 211 refers to the end portion of the boss 211 on the opposite side of the central axis N from the rib 231 . On the other hand, as shown in FIG. 13, in a plane parallel to the central axis AX of the helical portion 221 of the compression spring 202, a bent portion that abuts the side surface 212a of the mounting portion 210 (support plate 212) when mounted on the mounting portion 210. The distance from the second extending portion 222a of 222 to the position on the inner peripheral surface of the spiral portion 222 opposite to the second extending portion 222a with respect to the central axis AX is defined as B (mm). At this time, A>B is satisfied in this embodiment.

When A>B, when the bent portion 222 (hook portion 222c ₁ ) reaches the mounting position P by moving in the sliding direction, the bent portion 222 pulls the spiral portion 222 in the radial direction. As a result, the helical portion 221 inserted through the boss 211 moves in the radial direction of the compression spring 202 , and the inner peripheral surface of the helical portion 221 comes into contact with the boss 211 .

As described above, in this embodiment, the end portion of the compression spring 202 is locked by the locking portion 214 (mounting portion 210) _. 232 and is locked, the compression spring 202 is less likely to come off from the mounting portion 210 . Moreover, since the inner diameter Ds of the helical portion 222 of the compression spring 202 is larger than the outer diameter Db of the boss 211, the compression spring 202 can be easily inserted through the boss 211 as compared with press fitting. In other words, according to the configuration of the present embodiment, it is possible to make it difficult to remove the compression spring 202 from the frame 201 while facilitating the attachment of the compression spring 202 to the frame 201 .

At the mounting position P of the compression spring 202 , the helical portion 222 inserted through the boss 211 moves in the radial direction and the inner peripheral surface of the helical portion 222 comes into contact with the boss 211 . can stabilize the posture of As a result, it is possible to reduce the situation where the compression spring 202 comes into contact with other members and undergoes buckling deformation when the paper feed holder 200 is replaced, and it is possible to reduce the occurrence of assembly failures (installation failures). .

In addition, since the compression spring 202 is less likely to come off from the frame 201, it is possible to reduce the possibility of the compression spring 202 coming off or not being attached when the paper feed holder 200 is replaced. It is also possible to reduce the situation where the image forming apparatus 100 is operated without noticing. Furthermore, since there is no increase in the number of parts (because the effects of the present embodiment can be obtained without adding new members) in obtaining the effects of the present embodiment described above, there is no cost disadvantage at all.

In addition, by providing the rib 231 integrally with the support plate 212, a part of the bent portion 222 (hook portion 222c ₁ ) is brought into contact with the rib 231 by a simple action of rotating the compression spring 202, thereby bending the portion. The portion 222 can be guided to a predetermined mounting position P. Therefore, it is possible to easily attach the bent portion 222 to the support plate 212 .

Further, when the compression spring 202 is attached, part of the bent portion 222 (hook portion 222c ₁ ) enters the recessed portion 232, so that part of the bent portion 222 naturally (unless external force is applied intentionally). It becomes difficult to remove. This makes it difficult for the bent portion 222 to be released from the support plate 212, and can reliably prevent the compression spring 202 from accidentally falling off the support plate 212 (frame body 201).

Further, as described above, by satisfying A>B, when the compression spring 202 is attached, when a portion of the bent portion 222 slides and passes over the tip portion 231a of the rib 231, the bent portion 222 is helically formed. The portion 221 is pulled radially. As a result, the inner peripheral surface of the spiral portion 221 reliably contacts the boss 211, and the posture of the compression spring 202 can be reliably stabilized.

By the way, FIG. 14 is a sectional view of the paper feed holder 200 with the compression spring 202 completely attached to the support plate 212, and FIG. 15 shows the compression spring 202 of FIG. It is a side view shown in a state. When the compression spring 202 is attached to the support plate 212, the first extension 222b before the bent portions 222 (especially the first extension 222b and the third extension 222a) sandwich the support plate 212 from opposite sides. and the third extending portion 222c is C (mm), and the thickness of the support plate 212 is D (mm).

Since the bent portion 222 has elasticity, if C<D, when the bent portion 222 sandwiches the support plate 212, the distance between the first extension portion 222b and the third extension portion 222c is the same as that of the support plate. The bent portion 222 is elastically deformed by being widened by the thickness of 212 . At this time, since a restoring force acts on the bent portion 222, the supporting plate 212 can be strongly sandwiched between the first extending portion 222b and the third extending portion 222c. This makes it difficult for the compression spring 202 to rotate in the opposite direction (the direction in which the attachment to the support plate 212 is released), and it is possible to reliably prevent the compression spring 202 from coming off the support plate 212 .

As described above, in the present embodiment, in the paper feed holder 200 including the pickup roller 29, the configuration for facilitating the attachment of the compression spring 202, reducing the dropout thereof, and stabilizing the posture has been described. Any unit other than the paper feed holder 200 can be applied as long as it is a unit that presses an object with a compression spring. For example, it is possible to apply the configuration of this embodiment to a unit that holds the retard roller 32 or a paper feed unit of an automatic document feeder. can be done.

INDUSTRIAL APPLICABILITY The present invention can be used for holder units having compression springs, such as paper feed holders.

REFERENCE SIGNS LIST 10 sheet feed cassette 26 sheet 31 feed roller 100 image forming apparatus 100a apparatus main body 200 sheet feed holder (holder unit)
201 Frame 201a, 201b Side plate 201c First connection plate 201c ₁ Side 201d Second connection plate 202 Compression spring 210 Mounting portion 211 Boss 211a Side end 212 Support plate mounting portion 212a Side 212b Support surface 214 Locking portion 221 Spiral portion 222 bent portion 222a second extension portion 222b first extension portion 222c third extension portion 222c ₁ hook portion 231 rib 231a tip portion 232 hollow portion

Claims (7)

a roller, a frame body 201 that holds the roller on one end side and is supported so that the one end side can swing, and a compression spring that presses the roller against an object by urging the one end side of the frame body. 202, a holder unit 200 comprising:
The frame includes a pair of side plates 201a and 201b that support the rotation shaft of the roller, a pair of first and second connection plates 201c and 201d that are parallel to the rotation shaft and connect the side plates, a mounting portion 210 provided on the first connecting plate on one end side for mounting the compression spring;
The attachment portion includes a support surface 212b for supporting the compression spring, a boss 211 projecting from the support surface and through which the compression spring is inserted, and a locking portion 214 for locking the end of the compression spring. and
The compression spring has a helical portion 221 that extends helically and is inserted through the boss, and a helical portion 221 that extends radially outward from an end portion of the helical portion and is fitted in the locking portion so that the compression spring is positioned on the support surface. and a hook portion _222c1 provided at the tip of the bent portion and locked to the locking portion,
the inner diameter of the spiral portion is larger than the outer diameter of the boss;
A holder unit according to claim 1, wherein at said mounting position of said compression spring, said helical portion inserted through said boss moves in a radial direction, and an inner peripheral surface of said helical portion comes into contact with said boss. The mounting portion has a rib 231 inclined from the side surface 201c ₁ of the first connecting plate toward the back side,
When the compression spring inserted through the boss is rotated about the central axis of the helical portion, the rib contacts the hook portion and slides the bent portion, thereby moving the bent portion. 2. The holder unit according to claim 1, wherein the holder unit is guided to the mounting position. The rib has a shape in which the bent portion tapers in a sliding direction toward the mounting position,
3. The mounting portion has a recess portion 232 for locking the hook portion when the hook portion exceeds the tip portion 231a of the rib in the sliding direction. holder unit. The bent portion includes a first extension portion 222b extending radially outward from one end of the spiral portion, and a second extension portion 222a extending from the first extension portion in a direction along the central axis of the spiral portion. , a third extension portion 222c extending radially inward from the second extension portion, and the hook portion _222c1 connected to the tip of the third extension portion,
When the mounting portion of the frame is viewed from the other end side opposite to the one end side, in a direction parallel to the rotation axis of the roller, from the tip portion of the rib to the central axis N of the boss. On the other hand, the distance to the side end 211a on the opposite side of the rib is A (mm),
In a plane parallel to the central axis AX of the helical portion of the compression spring, from the second extending portion 222a of the bent portion that contacts the side surface 212a of the mounting portion when mounted to the mounting portion, the helical portion When the distance to the position on the opposite side of the central axis AX from the second extending portion on the inner peripheral surface of is B (mm),
4. The holder unit according to claim 3, wherein A>B. The bent portion of the compression spring has elasticity,
The first extension portion 222b and the third extension portion 222c sandwich the support plate 212 having the support surface from opposite sides,
When the distance between the first extension portion and the third extension portion before sandwiching the support plate is C (mm), and the thickness of the support plate is D (mm),
5. The holder unit according to claim 4, wherein C<D. The holder unit according to any one of claims 1 to 5, wherein the rollers include a pickup roller (29) that feeds the sheet from the paper feed cassette (10). a holder unit according to any one of claims 1 to 6;
An image forming apparatus comprising an apparatus main body 100a to which the holder unit is attached and detached.

Images