JP3073832B2 - Sheet transport device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a laser printer, LE
The present invention relates to a sheet conveying device applied to an image forming apparatus such as a D printer.

[0002]

[Prior art]

(1) Conventionally, a sheet conveying apparatus applied to an image forming apparatus such as a laser printer, an LED printer, or the like, as shown in FIG. 9, is a sheet conveying apparatus in which a conveyed sheet 51 is jammed (paper jam). In order to remove or replace the cartridge 52 with which the image forming means is integrated, the apparatus main body 53 can be divided into the fixed side A and the opening / closing section 54 can be divided into the opening / closing side B.

A structure of a positioning portion of the opening / closing portion 54 with respect to the apparatus main body 53 will be described with reference to FIG. In FIG. 10, the dashed line indicates the open / close side B in the open state, and the solid line indicates the position when the open / close side B is fixed to the fixed side A at the final position. When the opening / closing side B is fixed to the fixed side A from the open state, the opening / closing side B is rotated counterclockwise about the fulcrum M, and the hook 55 provided on the opening / closing side B is fixed to the stopper portion 56 of the fixed side A. Hit. The hook 55 is urged clockwise around the fulcrum N by a spring 57, and the hook 55 is
When it comes into contact with, it rotates over the stopper portion 56 while rotating counterclockwise against the urging force of the spring 57 and rotates to the state shown by the two-dot chain line. Thereafter, the opening / closing side B is pivoted clockwise around the fulcrum M by a spring 58 provided on the fixed side A, and the hook 55 and the stopper 56 are rotated.
Is locked and fixed at the position shown by the solid line in the figure.

FIG. 11 shows a sheet discharging section in a state where the opening / closing section 54 is fixed to the apparatus main body 53. The transport path 59 formed on the fixed side A of the apparatus is composed of a main body frame 60 and an upper cover 61, and the upper cover 61 is fixed to the main body frame 60 by a rigid connection with screws 62.

In the above-described image forming apparatus, the sheet after the image transfer is fixed by the fixing device 62, and then conveyed by the conveying roller 63. The conveying path 64 on the opening / closing side B and the fixing side A Rollers 65 through the conveyance path 59
Is discharged to a discharge tray 66 outside the apparatus.

[0006]

[Problems to be solved by the invention]

(1) However, in the prior art, as shown in FIG. 10, when the opening / closing side B is fixed, the hook 55 is rotated to the position shown by the two-dot chain line in order to lock the hook 55 with the stopper 56. Therefore, a gap d is always formed between the connecting portions between the opening / closing side B and the fixed side A. This has caused the following problems.

As shown in FIG. 11, a gap d is formed at the connecting portion between the opening / closing side B and the conveying paths 64 and 59 on the fixed side A, which may hinder the smooth conveyance of the sheet. Also, as shown in FIG. 11, the upper cover 61 located above the fixed side A often also serves as a transport path, and when a gap d is formed between the fixed side A and the opening / closing side B, play is generated. Therefore, it is difficult to keep the distance between the transport guides constant.

(2) The sheet on which the transferred image has been fixed by the fixing device 62 is heated by a heater or the like, so that if there is an obstacle in the course of conveyance or if the sheet is not smoothly introduced into the discharge roller 65, it will undulate. It is desirable that the distance between the transport guides (the body frame 60 and the upper cover 61) be narrowed so that the paper can be smoothly introduced into the discharge rollers 64 because of the possibility that the paper jams or jams may occur. Further, it is necessary to keep the interval between the conveyance guides uniform so that the transfer image surface of the sheet is not rubbed by the conveyance guide.

Particularly, in the sheet discharge section, the conveyance guide is easily deformed by the heat of the fixing device 62, and it is difficult to keep the interval uniform. If the interval between the conveyance guides is too large, the sheet may not be guided to the nip portion of the discharge roller pair 65, but the leading end may be caught, thereby causing a jam. Further, if the distance between the conveyance guides is too small, there is a possibility that a jam occurs or the image quality is deteriorated by rubbing the transfer image surface with the conveyance guide.

(1) An object of the present invention is to solve the above-mentioned problem (1) in the prior art, to prevent a gap from being formed in a sheet conveyance path, and to smoothly convey a sheet.

(2) An object of the present invention is to solve the problem (2) in the prior art and to stably convey a sheet while keeping a constant interval between guide members.

[0012]

Means for Solving the Problems (1) A typical means according to the present invention for solving the problem (1) shown in the prior art is a conveying means for conveying a sheet and a conveying means for conveying the sheet. A first and a second transport path that can be divided for guiding a sheet to be transported, provided on at least one of the first and the second transport paths, and provided on the first transport path.
It is characterized by having a connecting member for pressing the beam connecting portion and the connecting portion provided on the second transport path .

(2) A typical means according to the present invention for solving the problem (2) shown in the prior art is a transport rotating body for transporting a sheet, and both ends of a rotating shaft of the transport rotating body. A shaft supporting member for supporting the sheet, a guide member provided above and below for guiding a sheet conveyed by the conveying rotating body, and a deformation of the guide member formed on at least one of the guide members. And an abutting member.

[0014]

According to the above-mentioned means (1), a gap is formed in the connecting portion of the transport path by providing the connecting member for pressing the connecting portion of at least one of the first and second transport paths. Is prevented, and the sheet can be smoothly conveyed.

According to the above means (2), by forming the abutting member on at least one of the transport guides, even if the transport guide is deformed due to heat or the like, the deformation of the transport guide is corrected by the abutting member. Thus, the interval between the conveyance guides can be kept constant, and the sheet can be stably conveyed.

[0016]

Next, an embodiment of a sheet conveying apparatus to which the above-mentioned means is applied will be described with reference to the drawings. In this embodiment, a laser beam printer will be used to explain a sheet discharge unit of the printer. FIG. 1 is a cross-sectional explanatory view showing a schematic configuration of a laser beam printer, FIG. 2 is an enlarged explanatory view of a sheet discharging section, FIG. 3 is an enlarged explanatory view showing another example of the sheet discharging section, and FIG. FIG. 5, FIG. 5 is an explanatory view showing a modification of the transport guide of FIG. 4, FIG. 6 is an explanatory view showing another example of FIG. 4, FIG.
FIG. 8 is an explanatory diagram showing another example of FIG.

First, a schematic configuration of a laser beam printer will be described with reference to FIG. The printer according to the present embodiment is configured by combining an apparatus main body A with an opening / closing section B that can be opened and closed around a fulcrum M. Reference numeral 1 denotes a cassette capable of stacking a plurality of sheets P such as cut sheets. The sheets P stored in the cassette 1 are separated and fed one by one from the uppermost one at a predetermined timing by a feeding roller 2 and a separating claw 3, and a sheet guide 4 provided in the cassette 1 and an apparatus main body The registration roller pair 7 is guided by sheet guides 5 and 6 provided on the A side.
Is led to. Immediately before the registration roller pair 7, a sheet detection sensor S is provided. Control of rotation of the registration roller pair 7, emission timing of laser light from the laser oscillation unit 8, and the like are performed by a detection signal of the sensor S. Done.

The sheet P sent at a predetermined timing by the pair of registration rollers 7 transfers an image when passing between a photosensitive drum 9 as an image carrier and a transfer roller 10 provided opposite thereto. Is applied to the sheet P to transfer an image. A plurality of process units for image formation including the photosensitive drum 9 include:
The process cartridge C is housed in a process cartridge C. The process cartridge C is detachably mounted by opening and closing an opening / closing section B fixed to the apparatus main body A.

The image-transferred sheet P is guided by a fixing frame 11a and guided to a fixing device 11 arranged on the downstream side, where the transferred image is fixed. The fixing device 11 includes an aluminum fixing roller 12 heated to a predetermined temperature (about 200 ° C.) by a heater 12a and a temperature sensor (not shown).
And a pressure roller 13 made of rubber disposed opposite to the pressure roller 13. The pressure roller 13 is pressed against the fixing roller 12 with a constant pressure by a spring or the like (not shown) so as to be driven to rotate. It is configured.

Further, the sheet P after image fixing is fixed to a fixing roller.
A fixing roller is provided by a separation claw 12b provided on the downstream side of the fixing roller 12.
12, is transported downstream by a transport roller pair 14 that is a transport rotating body, and passes through a second transport path 15 of the opening / closing section B and a first transport path 16 of the apparatus main body A so that the image surface faces down. And is discharged by a discharge roller 17 to a discharge tray 18 arranged outside the apparatus.

Next, the configuration of the sheet discharge section will be described with reference to FIGS. The first transport path 16 on the apparatus main body A side includes a lower guide 19 integrally fixed to the apparatus main body frame and an upper guide 20 also serving as an exterior part.

The upper guide 20 is held by the fitting portion 20b of the apparatus body frame so as to be movable in the horizontal direction (the direction of arrow X). Also, the upper guide 20 is
And a connecting member 21 made of an elastic material. The connecting member 21 is formed in an L-shaped cross section, and is fixed to the lower guide 19 with a screw 21a. The material is a metal material such as a stainless steel plate for a spring, a phosphor bronze plate, or a polyacetal resin. Is used.

Therefore, the upper guide 20 is mounted movably in the direction of the arrow X within the range of the elastic limit of the connecting member 21. In FIG. 2, reference numeral 22 denotes a hook provided on the opening / closing portion B, which is attached so as to be rotatable about a fulcrum N. Reference numeral 23 denotes a stopper provided on the apparatus main body A side, and locks the hook 22 when the opening / closing portion B is fixed to the apparatus main body A.

When the hook 22 of the opening / closing section B is locked and fixed to the stopper 23 of the apparatus body A, the upper side of the opening 22 is larger than the gap d between the apparatus body A side and the opening / closing section B shown in the conventional example. When the moving range of the guide 20 is equal or more,
As shown in FIG. 2, the opening / closing portion B can be fixed at a predetermined position while the connecting portion D is always kept in close contact with the apparatus main body A by the elastic force of the connecting member 21, and the gap d is completely eliminated. It is possible to do.

As a result, the connection between the first transport path 16 and the second transport path 15 can be brought into close contact, and the sheet P can be transported smoothly.

When the connecting member 21 is made of a plastic resin as shown in FIG. 3, it can be formed integrally with a part of the upper guide 20. In this case, it is possible to reduce the number of parts and to manufacture at lower cost.

Next, the structure near the discharge roller 17 will be described with reference to FIGS. As shown in FIG.
The discharge roller 17 is attached at a plurality of positions in the axial direction of the rotating shaft 24, and the rotating shaft 24 is attached to the frame 25 of the apparatus main body A.
Is rotatably supported via a bearing 26.

The upper guide 20 is provided with a discharge roller 17.
In order to improve the positional accuracy with respect to the position, the frame 25 is fixed near the bearing 26 so as to support the projecting portion 20a. If the upper guide 20 is configured so that the projecting portion 20a directly abuts against the bearing 26, the positional accuracy is further improved.

The lower guide 19 is integrally fixed to the frame 25. At a position facing the discharge roller 17, a discharge roller 27 is supported by springs 29 fixed at both ends of a rotating shaft 28 on a frame 25 and is in pressure contact with the discharge roller 17.

At the center of the upper guide 20, an abutment member arranged close to the rotation shaft 24 of the discharge roller 17 is provided.
30 are protruding. The abutting member 30 is arranged so that the upper guide 20 is not warped, and the rotating shaft 24 of the discharge roller 17 and the rotating shaft 24 are located at 0.
They are arranged with a gap of about 2 mm.

For example, when the upper guide 20 is deformed so as to protrude downward as shown in FIG. 5 due to the heat of the sheet P after image fixing or the heat of the fixing device 11, the upper and lower guides 20, 19
The interval between them and the position of the upper guide 20 with respect to the discharge roller 17 cannot be maintained. Therefore, the sheet P can be smoothly guided to the discharge roller 17 by maintaining the distance and position between the upper and lower guides by correcting the warpage of the upper guide 20 by the abutting member 30.

As the abutment member 30, it is preferable to use a bearing material such as a resin having good slidability without generating abnormal noise or the like. For example, the same effect can be obtained by attaching a freely rotatable roller 31 to the tip of the abutting member 30 as shown in FIG. Furthermore, when the upper guide 30 is warped when a plurality of the abutting members 30 are provided at a plurality of locations in the axial direction, instead of only one abutting member 30, the abutting force can be dispersed. Is more preferred.

According to the above-described structure, by projecting the abutting member 30 on the upper guide 20, even if the upper guide is deformed by heat or the like, the deformation of the upper guide 20 is corrected by the abutting member 30. Accordingly, the interval between the upper and lower guides can be kept constant, and the sheet P can be stably conveyed.

Next, another embodiment of the abutment member 30 will be described with reference to FIGS. In the above-described embodiment, the correction method in the case where the upper guide 20 warps downward (toward the discharge roller 17) is described. However, as shown in FIG. In the case where the convex warpage occurs in ()), there is no effect. Therefore,
As shown in FIG. 8, a hook 32 that rotatably engages with the rotation shaft 24 of the discharge roller 17 can be formed at the tip of the butting member 30. In this case, even if the upper guide 20 warps in any of the upper and lower directions, it can be corrected, and the reliability of the device can be further improved.

Although the present embodiment has been described using a laser beam printer as an image forming apparatus, the present invention can be applied to other image forming apparatuses such as a copying machine and an LED printer.

[0036]

According to the present invention, as described above, at least one of the first and second transport paths is provided with a connecting member for pressing the connecting portions of the two, so that a gap is formed in the connecting section of the transport paths. It is possible to prevent the sheet from being generated and to smoothly carry the sheet.

By forming the abutting member on at least one of the transport guides, even if the transport guide is deformed by heat or the like, the deformation of the transport guide is corrected by the abutting member, so that the distance between the transport guides is increased. Can be kept constant, and the sheet can be stably conveyed.

[Brief description of the drawings]

FIG. 1 is an explanatory sectional view showing a schematic configuration of a laser beam printer.

FIG. 2 is an enlarged explanatory view of a sheet discharge unit.

FIG. 3 is an enlarged explanatory view showing another example of the sheet discharging unit.

FIG. 4 is an explanatory sectional view of a sheet discharging unit.

FIG. 5 is an explanatory view showing a modification of the transport guide of FIG. 4;

FIG. 6 is an explanatory diagram showing another example of FIG. 4;

FIG. 7 is an explanatory view showing a modification of a transport guide of another example.

FIG. 8 is an explanatory diagram showing another example of FIG. 4;

FIG. 9 is an explanatory diagram of a conventional image forming apparatus.

FIG. 10 is an explanatory view showing a conventional fixing structure of an opening / closing unit.

FIG. 11 is an enlarged explanatory view of a conventional sheet discharge unit.

[Explanation of symbols]

 A: apparatus body B: opening / closing section C: process cartridge M, N: fulcrum P: sheet S: sheet detection sensor 1: cassette 2: feeding roller 3: separation claw 4, 5, 6: sheet guide 7: registration roller pair 8 Laser Oscillation Unit 9 Photosensitive Drum 10 Transfer Roller 11 Fixing Unit 11a Fixing Frame 12 Fixing Roller 12a Heater 13 Pressure Roller 14 Transfer Roller Pair 15 Second Transport Path 16 First Transport Path 17 ... discharge roller 18 ... discharge tray 19 ... lower guide 20 ... upper guide 20a ... protruding part 20b ... fitting part 21 ... connecting member 22 ... hook 23 ... stopper 24, 28 ... rotating shaft 25 ... frame 26 ... bearing 27 … Discharge roller 29… Spring 30… Abutment member 31… Roller 32… Hook

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁷ identification code FI G03G 21/16 G03G 15/00 554 (58) Investigation field (Int.Cl. ⁷ , DB name) B41J 13/00 B41J 13 / 10 B41J 29/13 B65H 5/36 G03G 15/00 510-550 G03G 21/16-21/18

Claims (5)

(57) [Claims] A transport unit configured to transport the sheet; a first and a second transport path that can be divided to guide the sheet transported by the transport unit; Provided on at least one of the paths,
A connecting portion provided on the first transport path and a connecting section provided on the second transport path
A sheet conveying device having a connecting member for pressing the connecting portion into pressure. 2. The sheet conveying apparatus according to claim 1, wherein the connecting member presses the connecting portions of the first and second conveying paths by using an elastic member. 3. A conveying rotator for conveying a sheet, a shaft supporting member for supporting both ends of a rotating shaft of the conveying rotator, and a vertical member for guiding a sheet conveyed by the conveying rotator. a guide member provided on said guide the guide portion is formed on at least one member
And a butting member for correcting deformation of the material . 4. The sheet conveying device according to claim 3, wherein the abutting member is made of a resin . 5. The sheet conveying device according to claim 3, wherein the abutting member uses a rotating roller.