JPH09124170A - Sheet feeding device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simultaneously perform the retreating operation of a feeding rotational body and the separating operation of a separating rotational body from a contact rotational, body by means of a single releasing means with the attaching and detaching operation of a sheet cassette, by retreating the feeding rotational body by a releasing means and separating the separating rotational body from the contact rotational body. SOLUTION: When a cassette 1 is pulled out from a device main body, a releasing member 52 is turned clockwise by elastic force of a spring 53, a retard roller holder 30 is pressed down by a holder contact part 52a, and the contact of a feed roller 4 with the retard roller 5 is released. A pickup roller shaft 3a is pressed up by a pickup roller press-up part 52b, and the pickup roller 3 is separated and retreated from a sheet S in the cassette 1. The contacting and separating operation of the feed roller 4 and the retard roller 5 and the forcible raising operation of the pickup roller 3 are performed by a single member of a releasing member 52, and therefore, the number of part items is decrease, the cost is reduced, and the installation space can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding device for an image forming apparatus.

[0002]

2. Description of the Related Art In a conventional sheet feeding apparatus in which a sheet cassette is attachable to and detachable from an apparatus main body, particularly in a sheet feeding apparatus in which a sheet conveying direction and a sheet cassette attaching / detaching direction are orthogonal to each other. A pickup means for retracting the pickup roller from the sheet so that the sheet stored in the sheet cassette does not interfere with a pickup roller or the like for feeding the sheet provided on the apparatus main body side when the sheet cassette is attached or detached, Release means for releasing the pressure contact between the feed roller and the retard roller, which separate the sheets fed out by the roller one by one, are separately provided.

[0003]

However, in the above-mentioned prior art, the retracting means for retracting the pickup roller from the sheet and the releasing means for releasing the pressure contact between the feed roller and the retard roller are separately configured separately. Since it was provided, the number of parts increased and the cost increased,
There is a problem that the device becomes large.

Further, since there are a large number of parts constituting the retracting means and the releasing means, the tolerances of the respective parts are accumulated, and the retracting operation of the pickup roller and the releasing operation of the feed roller and the retard roller are defective. There was also a risk of becoming.

The present invention solves the above-mentioned problems.
The purpose of this is a sheet feeding apparatus capable of simultaneously performing the retracting operation of the feeding rotating body and the separating operation of the separating rotating body and the pressure contact rotating body by one releasing means in conjunction with the attaching / detaching operation of the sheet cassette. And an image forming apparatus provided with the same.

[0006]

A typical structure according to the present invention for achieving the above object is a sheet cassette that is detachably attached to a main body of an apparatus, and stores a sheet.
A feeding rotating body that feeds out the sheets accommodated in the sheet cassette, a separating rotating body that is provided downstream of the feeding rotating body in the sheet conveying direction, and a pressure contact rotation that is provided so as to face the separating rotating body. A sheet body and a releasing means for retracting the feeding rotating body with respect to the sheets accommodated in the sheet cassette and for separating the separating rotating body and the pressure contact rotating body from each other. The releasing means retracts the feeding rotating body with respect to the sheets accommodated in the sheet cassette in association with the attaching / detaching operation of attaching / detaching to / from the apparatus main body, and at the same time, the separating rotating body and the pressure contact rotating body are separated from each other. A sheet feeding device characterized by being configured to be separated from each other.

Since the present invention is configured as described above, the retracting operation of the feeding rotating member and the separating operation of the separating rotating member and the pressure contact rotating member are performed by one releasing means in conjunction with the attaching / detaching operation of the sheet cassette. Can be done at the same time.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be specifically described with reference to the drawings. 1 is an explanatory view of the overall configuration of the image forming apparatus, FIG. 2 is an explanatory view of a guide for inserting the sheet cassette into the apparatus main body, FIGS. 3 and 4 are explanatory views of the positioning of the sheet cassette, and FIG. 5 is a separation of the retard roller. FIG. 6 is a diagram for explaining the separation of the pickup roller, FIGS. 7 to 12 are diagrams for explaining the operation configuration of the pickup roller and the lifter, FIG. 13 is a diagram for explaining the drive transmission of the feed roller and the retard roller, and FIG. 14 is a ground for the retard roller. FIG.

[Overall Configuration of Image Forming Apparatus] First, the overall configuration of the image forming apparatus main body will be described with reference to FIG. FIG.
In the above, the image forming apparatus main body A has a scanner unit B serving as an image reading unit that reads image information of an image surface of a book document at an upper portion thereof, and an image forming unit C serving as an image forming unit at a lower portion thereof, Further, a seat deck D is attached to the lower part thereof.

The scanner unit B includes a scanning system light source 201, a platen glass 202, an original pressure plate 203 that can be opened and closed with respect to the apparatus main body A, a mirror 204, a lens 205, a light receiving element (photoelectric conversion element) 206, and an image processing section. And so on. Then, on the platen glass 202, books or cardboard,
Place a book document such as curled paper or a sheet document with the document side facing down, press the back side of the document pressure plate 203 to set it in a stationary state, and press the reading start key to turn on the scanning system light source 201. The lower part of the platen glass 202 is scanned in the direction of arrow a in FIG. 1 to read the image information on the document surface. Scanning light source
The image information of the document read by 201 is processed by the image processing unit, converted into an electric signal and transmitted to the laser scanner 111.

Here, the image forming apparatus main body A functions as a copying machine when the processing signal of the image processing section is input to the laser scanner 111, and functions as a printer when the output signal of the personal computer is input. If a transmission signal from a facsimile device of another device is input or a processing signal of the image processing unit is transmitted to a facsimile device of another device, the device functions as a facsimile device.

On the other hand, a sheet cassette 1 is attached to the lower portion of the image forming section C, and the sheet cassette 1 is composed of two lower cassettes 1a and upper cassettes 1b as one feeding unit. In this embodiment, three feeding units U1, U2, and U3 are mounted, and six cassettes are mounted. Further, one feeding unit U1 located above is detachably attached to the apparatus main body A, and two feeding units U2 and U3 below are detachably attached to the seat deck D.

The sheets accommodated in the cassettes 1a and 1b are fed out by a pickup roller 3 serving as a feeding rotating body, as described later, and a feed roller 4 serving as a separating rotating body, and a retard roller serving as a pressure contact rotating body. After the sheets are separated and fed one by one by the cooperative action with 5, the conveyance rollers
It is conveyed by 104 and 105, guided to the registration roller 106, and fed to the image forming section C by the roller 106 in synchronism with the image forming operation.

The image forming section C includes an electrophotographic photosensitive drum 11
2. An image writing optical system 113, a developing device 114, a transfer charging device 115, and the like. Then, the laser beam corresponding to the image information emitted from the laser scanner 111 is scanned by the image writing optical system 113 on the surface of the photosensitive drum 112 uniformly charged by the charger to form a latent image. A toner image is formed on the image by the developing device 114, and the toner image is transferred to the first surface of the sheet by the transfer charging device 115 on the sheet conveyed by the registration roller 106 in synchronization with the rotation of the photosensitive drum 112.

Reference numeral 117 is a conveyance belt that conveys a sheet on which a toner image is formed, 118 is a fixing device, and 119 is a discharge roller. The sheet on which the toner image is formed is the conveyance belt 11
The toner image is conveyed to a fixing device 118 by means of 7 and is heated and pressed to fix the toner image on the surface of the sheet, and then discharged and stacked by a discharge roller 119 to a sorter 120 arranged outside the machine.

When recording images on both sides of the sheet, the sheet discharged from the fixing device 118 is the discharge roller.
When the trailing edge of the sheet is nipped by 119 and the trailing edge of the sheet passes the branch point 207, the discharge roller 119 reverses and the sheet is fed to the duplex tray.
After the sheet is once placed on the sheet 121, it is conveyed by the conveying rollers 104 and 105, reaches the registration roller 106, and the reversed sheet has an image formed on the second surface in the same manner as described above, and then the sorter 120. It is configured to be discharged and loaded onto

[Configuration of Cassette Mounting Guide] Next, the configuration of the cassette mounting guide in the image forming apparatus will be described. The cassette according to this embodiment is shown in FIGS.
As shown in FIG. 3, a pair of two feeding units U composed of a lower cassette 1a and an upper cassette 1b are arranged in upper and lower parts.
By stacking them, 6 cassettes are mounted one above the other. This cassette is mounted by sliding it from the front side to the back side (from the front surface side to the back surface side in FIG. 1) of the apparatus main body.

FIG. 2 is an explanatory view showing a mounting guide of the feeding unit. A plurality of rails and guides serving as guide members of the cassette and slides of the cassette are provided at predetermined positions of the image forming apparatus main body frame and the sheet feeding apparatus frame. It is provided parallel to the direction.

In the upper cassette 1b, a convex portion 1b1 formed at the left end of the upper cassette 1b is fitted to a rail 81 having a U-shaped cross section attached to a frame 88 of the main body of the image forming apparatus, and the upper cassette is extended along the rail 81. Insert 1b. As a result, the height of the left end side of the upper cassette 1b is set to the rail.
81, and the left side when the upper cassette is attached or detached,
The upper left side regulation is also performed by the rail 81.

On the other hand, the right end side, which is the sheet feeding side of the upper cassette 1b, has a lower end and a right side surface at the frame 7 of the feeding device.
By inserting it along a rail 86 having an L-shaped cross section attached to the upper cassette 1b (see FIG. 7), the height of the right end of the upper cassette 1b and the position of the right side when the cassette is attached and detached are defined. The upper right side of the upper cassette 1b is pressed by the stay 83 attached to the frame 7 of the feeding device, so that the upper right side when the upper cassette is attached and detached is regulated.

The sheets in the upper cassette 1b are picked up by the pickup roller 3 on the upper cassette side and fed by the feed rollers 4 and the like, and the side picking up the sheets stored in the cassette 1b is attached to the feeding device. The height is regulated by a rail 86, and the rail 86 is attached to the feeding frame 7 which is the same member as the member to which the pickup roller 3, the feed roller 4 and the retard roller 5 constituting the upper cassette side feeding means are attached. For being a feeding means and rail 86
The height of the upper cassette 1b is restricted, and as a result, the positional accuracy between the feeding means and the sheet surface fed from the cassette 1b can be easily obtained, and reliable and stable feeding can be performed. I can.

Next, the bottom end of the lower cassette 1a is guided by the bottom plate 87 of the main body of the image forming apparatus, whereby the height of the left end is defined. Further, the left side surface and the upper left side when the lower cassette is attached and detached are guided by a guide 82 having an L-shaped cross section attached to the image forming apparatus main body, whereby the left side surface and the upper left side are regulated.

On the other hand, the right side, which is the sheet feeding side of the lower cassette 1a, is guided by a rail 85 having an L-shaped cross section attached to the frame 7 of the feeding device, and the height of the right side is defined by the rail 85. It has become so. still,
The rail 85 also regulates the right side surface when the lower cassette is attached or detached.

Further, a pressing member 84 having a T-shaped cross section is attached to a rail 86 which guides the right side of the upper cassette 1b, and the pressing member 84 regulates the upper right side of the lower cassette 1a. doing.

The sheets in the lower cassette 1a are also picked up by the pickup roller 3 on the lower cassette side and fed by the feed rollers 4 and the like, but like the upper cassette 1b, the sheets stored in the lower cassette 1a are fed. The pick-up side has a height defined by a rail 85 attached to the frame 7 of the feeding device, and the rail 85 is attached with the pickup roller 3, the feed roller 4, and the retard roller 5 which constitute the lower cassette side feeding means. Since it is attached to the feeding frame 7 which is the same member as the member, the lower cassette 1a, whose height is regulated by the feeding means and the rail 85, is eventually fed from the feeding means and the lower cassette 1a. Positional accuracy with respect to the seat surface can be easily obtained, and reliable and stable feeding can be performed.

Further, as shown in FIG. 2, rails 85 and 86 for guiding the sheet feeding side of the upper and lower cassettes 1a and 1b, when the sheets accommodated in the cassette are fed out by the pickup roller 3, Sheet guide portions 85c and 86c for guiding to the nip portion between the feed roller 4 and the retard roller 5 are integrally formed by bending. The sheet guide portions 85c and 86c are provided for the respective cassettes 1
The member that defines the heights of a and 1b, that is, the cassette 1
Since the rails 85 and 86, which are members for supporting the bottom surfaces of a and 1b, are integrally formed, the respective cassettes 1a and
The sheet can be accurately positioned at the height position corresponding to the sheet feeding port of 1b, and thus the sheet can be stably fed from the cassette.

Further, since the pressing member 84 is arranged so as to be located above the leading end of the sheet when the lower cassette 1a is set at the feeding position, curling of the sheet in the lower cassette 1a is suppressed. Further, the lower surface of the pressing member 84 serves as a guide portion for guiding the sheet when the sheet is fed from the lower cassette 1a.

By attaching the pressing member 84 to the rail 86 that guides the upper cassette 1b as in the present embodiment, various functions are achieved in a narrow space. Even if the bottom surface of the upper rail 86 is used as it is without providing the pressing member 84, the same effect can be obtained. In this case, the number of parts and the cost can be reduced. .

Further, as shown in FIG. 2, the rails 85,
In the back side of the apparatus 86, partially bent and raised portions 85a and 86a are provided, and after the cassette is inserted into the main body, it is finally fitted into the recesses 1c and 1d and the back side of the cassette and the feeding apparatus. The position of can be specified. Bending and raising part 85
Since a and 86a are provided only on the rear side of the apparatus, the cassette and the rail are not caught when the cassette is attached and detached, and the sliding load is reduced, so that the operability is improved.

[Cassette Positioning Structure When Mounting Cassette] Next, the positioning structure when the cassette is mounted will be described. FIG. 3 shows a cassette 1 for the apparatus main body A.
FIG. 6 is a diagram showing a cassette holding member 60 that constitutes a sheet cassette positioning device that holds and positions a sheet. The cassette holding member 60 includes a stay 62 fixed to the main body frame 61 of the apparatus main body A, and an adjusting plate 65 that serves as an adjusting unit that can adjust the position of the stay 1 in the attaching / detaching direction of the cassette 1.
A positioning plate 63, which serves as a positioning means, is movably provided in the attachment / detachment direction of the cassette 1 with respect to the adjusting plate 65; It is configured to have a lever 64 or the like that serves as holding means.

The positioning plate 63 is provided with an elongated hole 63e, and a guide shaft 66 and a fixing screw 67 which are fitted and engaged with the elongated hole 63e are fixed to the stay 62.
63e is guided by the engagement of the guide shaft 66 and the fixing screw 67, and is movable with respect to the stay 62 in the attachment / detachment direction of the cassette 1.

The positioning plate 63 includes a guide shaft 66 and a fixing screw.
Although it is movable along the cylindrical portion of 67, it is restricted by the guide shaft 66 and the flange portions 66a and 67a of the fixing screw 67 so as not to move in the vertical direction.

A pair of guide portions 63b, 63c are provided on the side of the positioning plate 63 facing the cassette 1, and the guide portion 63 is provided.
b is longer than the guide part 63c, and both guide parts 63c
A cylindrical portion 11 serving as an engaging portion of the cassette 1 is provided between b and 63c.
A groove portion 63d is formed so that 0 can be fitted and engaged.

A lever 64 is provided on the upper surface of the positioning plate 63 so as to be rotatable around a shaft 63a.
A spring 68 is engaged between one end of 63 and one end of the lever 64. Further, on the upper surface of the positioning plate 63, a stopper 63i is provided, which is in contact with the end portion of the lever 64 and regulates the rotation angle of the lever 64 by the pulling force of the spring 68. Then, the pulling force of the spring 68 causes the lever 64 to rotate in the clockwise direction in FIG. 3 so that the end of the lever 64 is stopped by the stopper 63i.
The claw portion 64a of the lever 64 is located at a position opposed to the groove portion 63d of the positioning plate 63 by being brought into contact with and locked.

The adjusting plate 65 arranged between the positioning plate 63 and the stay 62 is also provided with an elongated hole (not shown), and the elongated hole is engaged with the guide shaft 66 by engaging with the adjusting plate. 65 is stay
It is possible to move on the 62 along the guide shaft 66 in the attachment / detachment direction of the cassette 1, but with the fixing screw 67, it is possible to stay at any position.
It can be fixed to 62.

At the end of the adjusting plate 65 on the side of the cassette 1, a projection 65 is provided as a butt portion that protrudes in correspondence with a groove 63f provided at the lower portion of a positioning plate 63 arranged at the upper portion of the adjusting plate 65.
The protrusion 65a of the adjusting plate 65 abuts on the wall surface 63g, which is a bent and erected, and which is the abutting portion of the groove 63f of the positioning plate 63 that moves on the adjusting plate 65, thereby regulating the position of the positioning plate 63. It is like this.

Further, a biasing means (not shown) composed of a coil spring, a leaf spring, etc. is provided on the main body frame 61 or the cassette 1 side, and when the cassette 1 is mounted on the apparatus main body A, the cassette 1 To urge the cassette 1 away from the apparatus main body A (pull-out direction).

Next, the operation of the cassette holding member 60 when the cassette 1 is mounted on the apparatus main body A is shown in FIG.
This will be described using (a) to (c). As shown in FIG.
The cassette 1 has two cylindrical portions 109 and 110 which are coaxially formed on the front right side in FIG.

As shown in FIGS. 4A to 4C, when the cassette 1 is mounted on the apparatus main body A, the cassette 1 is attached to the apparatus main body A by the arrow b in FIG. 4A. The cylindrical portions 109, 11 provided in the cassette 1 are pushed in the direction
0 abuts on the claw portion 64a of the lever 64 and the guide portion 63b of the positioning plate 63 provided on the apparatus main body A, and the positioning plate 63 and the lever 64 are integrally pushed into the main body frame 61 side.

A positioning plate pushed by the cassette 1
63 moves on the stay 62 and the adjusting plate 65 in the direction of the arrow b in FIG. 4B, and as shown in FIG.
63h of the end hits the body frame 61, and the cassette 1
Is pushed further toward the body frame 61 side, the lever 64
Rotating in the counterclockwise direction in FIG. 3 against the pulling force of 68, the cylindrical portion 110 provided in the cassette 1 is aligned with the positioning plate 63.
It fits in the groove 63d provided in the.

When the cylindrical portion 110 is completely fitted in the groove portion 63d, the lever 64 is rotated clockwise by the pulling force of the spring 68, and the claw portion 64a of the lever 64 is rotated to the cylindrical portion of the cassette 1. Holds 109 and cassette 1 is positioning plate 63
And is positioned with respect to the positioning plate 63.

At this time, the cassette 1 is, as described above,
4C, the positioning plate 63 moves integrally with the cassette 1 in the direction of arrow c in FIG. 4C.

Then, the wall surface 63 of the groove portion 63f of the positioning plate 63
The protrusion 65a of the adjusting plate 65 hits g, and the cassette 1 and the positioning plate 63 are held at this position and positioned with respect to the apparatus main body A. The position of the cassette 1 with respect to the apparatus main body A is determined by the series of operations described above.

When changing the position of the cassette 1 with respect to the apparatus main body A, after loosening the fixing screw 67, the adjusting plate 65 is slid with respect to the stay 62 and set to a predetermined position, and then fixed. Fasten the screw 67 and stay the adjustment plate 65.
It may be fixed in place with respect to 62.

When the cassette 1 is pulled out from the main assembly A of the apparatus, when the cassette 1 is pulled out from the main assembly A of the apparatus against the pulling force of the spring 68, the lever 64 rotates counterclockwise in FIG. And the cylindrical part 109 of the cassette 1 is the lever 64.
The cylindrical part 110 is removed from the claw part 64a of the
The cassette 1 can be pulled out from the main assembly A of the apparatus by coming out of the groove 63c of 63.

With the above structure, the cassette 1 can be positioned and held in a narrow space. Further, since the adjusting plate 65 does not directly receive the shock when the cassette is inserted, it can withstand even a slight fastening force of the fixing screw 106, and the shock of the adjusting plate 65 when the cassette 1 is mounted causes the adjusting plate 65 to move. The position does not shift.

When the cassette 1 is attached to the main assembly A of the apparatus, first, when the cassette 1 is fitted into the bent and raised portions 85a and 86a of the rails 85 and 86, the cassette 1 is preceded by the left side of FIG. The cassette 1 has a backlash so that the whole of the cassette 1 tilts.
Of the 63c, the guide portion 63b located on the left side has a longer length, and the cylindrical portion 110 of the cassette 1 comes first.
Since the cassette 1 is restrained from inclining by contacting b, the cassette 1 is regulated so that the cylindrical portion 110 faces the center of the groove portion 63d, and a small force for rotating the lever 64 is required. The feeling is lighter and preferable.

[Up and Down of Pickup Roller and Contact and Separation of Retard Roller] Next, FIGS. 5A, 5B and 6
The contacting / separating operation of the feed roller 4 and the retard roller 5 and the retracting operation of the pickup roller 3 when the cassette 1 is attached / detached to / from the apparatus main body A will be described with reference to FIGS. 5 (a) and 6 (a) show a state in which the cassette 1 is removed, and FIGS. 5 (b) and 6 (b) show a state in which the cassette 1 is inserted.

In FIGS. 5 and 6, a releasing member 52 made of a wire serving as a releasing means is held by a bearing portion 7b provided inside the feeding frame 7. The spring 53 urges it clockwise in FIGS. 5 and 6.

The releasing member 52 has a holder contact portion 52a which can contact the retard roller holder 30 which holds the retard roller shaft 5a of the retard roller 5, and the pickup roller 3.
It has a pickup roller push-up portion 52b capable of contacting the pickup roller shaft 3a and a cassette contact portion 52c capable of contacting the cassette 1.

As shown in FIGS. 5 (a) and 6 (a), when the cassette 1 is pulled out from the apparatus main body A, the release member 52 is moved to the release member 52 by the elastic force of the spring 53. ), The holder contact portion 52a pushes down the retard roller holder 30 to release the pressure contact between the feed roller 4 and the retard roller 5, and at the same time the pickup roller push-up portion
52b pushes up the pickup roller shaft 3a, and retracts the pickup roller 3 away from the sheet S in the cassette 1.

Further, as shown in FIGS. 5 (b) and 6 (b), when the cassette 1 is pushed into the apparatus main body A,
The side end surface of the cassette 1 is the cassette contact portion 52c of the release member 52.
The release member 52 against the elastic force of the spring 53.
6B, the feed roller 4 and the retard roller 5 can be pressed against each other by rotating counterclockwise in FIG. 6B to release the holder contact portion 52a of the release member 52 from the retard roller holder 30. At the same time, the pickup roller push-up portion 52b of the release member 52 is released from the pickup roller shaft 3a to lower the pickup roller 3 so that the pickup roller 3 can contact the sheet S in the cassette 1.

Therefore, due to the action of the releasing member 52, even if the pickup roller shaft 3a remains down for some reason (such as when the power of the main body is suddenly turned off), the cassette 1
By pulling out, the pickup roller push-up portion 52b of the release member 52 pushes up the pickup roller shaft 3a and does not interfere with the attaching / detaching operation of the cassette 1 to / from the apparatus main body A.

As described above, one member of the releasing member 52 performs the contact / separation operation between the feed roller 4 and the retard roller 5 and the compulsory raising operation of the pickup roller 3, thereby reducing the number of parts and reducing the cost. At the same time, the space for installing parts can be reduced, the device can be downsized, and the effect of suppressing the height of the entire feeding unit is great.

[Arrangement of Cassettes] Next, the arrangement of the upper and lower cassettes 1a and 1b mounted as described above will be described.

As described above, the feeding unit according to the present embodiment is constituted by the upper and lower cassettes 1a and 1b as one unit, and the pickup roller 3, the feed roller 4, and the retard roller are provided for the respective cassettes 1a and 1b. A feeding unit composed of 5 and a pair of conveying rollers and a lifter are provided, and a driving mechanism for driving these is arranged in the feeding frame 7 as shown in FIG.

In the one feeding unit U, as shown in FIGS. 1 and 2, the lower cassette 1a is arranged so as to be displaced downstream of the upper cassette 1b in the sheet feeding direction. Further, the pickup roller 3, the feed roller 4 and the like in one feeding unit U are also arranged so as to be offset from each other between the upper cassette 1b and the lower cassette. That is, the pickup roller 3, the feed roller 4, and the retard roller 5 on the lower cassette 1a side are connected to the upper cassette 1b.
The downstream side (right side in FIG. 2) of the upper cassette 1
By arranging them in the upper and lower areas of b (the area up to the upper part of the upper cassette 1b), the wasted space is eliminated and the feeding unit U is eliminated.
The overall height is kept low.

Further, by making the pickup roller diameter and the feed roller diameter small (20 mm or less in this embodiment), the height of the entire feeding unit can be further suppressed.

In this embodiment, three feeding units U (U
By using 1 to U3), it becomes possible to realize large-capacity sheet feeding as it is and to load sheets of various sizes in the cassette. At this time, the configuration of the sheet guide may be changed from the overall sheet path configuration, but as described above, the upper and lower cassettes 1a and 1b are displaced, and the feeding means on the lower cassette side is provided in an empty space. By suppressing the height of the feeding unit U, the height of the main body of the image forming apparatus (the height L of the document table, the height L of the operation key for performing copy operations, etc.) even when the three feeding units are vertically stacked. ′) Is a certain height or less (for example, 950 is defined as a height that is not inconvenient when a general adult stands upright and performs a copy operation).
It can be suppressed to about 990 mm).

[Upper and Lower of Pickup Roller, Operational Structure of Lifter] Next, the structure for swinging the pickup roller 3 will be described. In FIG. 7, 1 is a sheet cassette as a sheet storage container, and a sheet S
Is loaded and stored. The sheets S are stacked on a sheet stacking plate 2 rotatably attached to the bottom of the cassette 1,
The cassette 1 is configured to be attachable to the apparatus main body A in the direction of arrow d in FIG.

Reference numeral 3 denotes a pickup roller as a feeding rotary member, which sends out the sheets S stacked in the cassette 1 from the uppermost side. 4 is a feed roller, 5 is a retard roller,
The sheets S that have been respectively driven to rotate in the opposite direction and sent out are separated and fed one by one.

The pickup roller shaft 3a of the pickup roller 3 and the feed roller shaft 4a of the feed roller 4 are connected and supported by a roller holder 6, and the pickup roller 3 is swingably supported around the feed roller 4. There is.

One end of the pickup roller shaft 3a is inserted into an elongated hole 7a formed in the feeding frame 7 and extends to a lifter mechanism (right side in FIG. 7). A lift-up lever 9 is rotatably attached to a shaft 8 formed integrally with the feeding frame 7, and is urged in a clockwise direction (direction of arrow e in FIG. 7) by a spring 9a.

Therefore, one end of the lift-up lever 9 is in contact with the pickup roller shaft 3a. The other end of the lift-up lever 9 extends near the pickup cam 10, and the lift-up lever 9 swings when the pickup cam 10 rotates.

The pickup cam 10 is coaxially and integrally formed on the side surface of the pickup gear (partial tooth gear) 11 on the side facing the gear 12 with only a part of teeth. The pickup gear 11 is biased in the counterclockwise direction (the direction of arrow f in FIG. 7) by a biasing means (not shown). In this embodiment, a pickup cam is resisted by the flapper type solenoid 13 against the biasing means. 10 rotations are restricted.

Reference numeral 14 is a main motor of the image forming apparatus main body A, and a drive input from the motor 14 is transmitted to a gear 12 via a gear 15 so that the gear 12 is constantly moved in the direction of arrow g in FIG. It is rotating.

Reference numeral 16 is a lifter which raises and lowers the sheet stacking plate 2 of the cassette 1. A ratchet gear 17 is integrally formed at one end of the lifter 16. A lift-up gear (partial tooth gear) 18 arranged facing the gear 12 and having only a part of teeth has a lift-up cam 19 coaxially with the lift-up gear 19. 20 is swung around the shaft 21, and the lifter 16 is raised by progressively feeding the ratchet gear 17 one tooth at a time by the reverse rotation preventing function of the lock pawl 22 (see FIG. 8B). Thereby, the sheet S in the cassette 1 is lifted up.

In FIG. 7, 23 is a lifter trigger lever, which is swingably supported by a shaft 8 formed integrally with the feeding frame 7 and is rotated by a spring 24 in a clockwise direction ( It is biased in the direction of arrow h in FIG.

One end of the lifter trigger lever 23 is
It has a function as a rotation restricting member for the lift-up gear 18 integrated with the lift-up cam 19, and the other end of the lever 23 comes into contact with the pick-up roller shaft 3a when the pick-up roller 3 is lowered to a predetermined height. It is arranged.

That is, when the pickup roller shaft 3a is lowered to a predetermined height, the restriction portion at the other end of the lifter trigger lever 23 releases the rotation restriction of the lift-up cam 19,
The lift-up cam 19 rotates, and the feed claw 20 is swung by a mechanism described later to raise the lifter 16.

When the uppermost sheet surface of the sheet S is lifted by the lifter 16 being lifted, the pickup roller 3 which is in contact with the seat surface is also lifted, and the lifter trigger lever is moved.
23 returns to the clockwise direction (direction of arrow h in FIG. 7) to return to the position where the rotation of the lift-up cam 19 is restricted again. By repeating this operation, the sheet S in the cassette 1
Of the uppermost sheet surface becomes substantially constant.

As a result, this apparatus enters a standby state in which sheets S can be fed. After that, the pickup cam 10 is rotated by exciting the flapper solenoid 13 in synchronization with the feeding start signal, the lift-up lever 9 swings, the pickup roller shaft 3a descends, and the pickup roller 3 moves to the sheet S. The sheet S can be fed out by contacting with.

The pickup roller 3 contacts the sheet surface of the sheet S for a time determined by the shape and angular velocity of the pickup cam 10, and then separates from the sheet surface and rises. During this time, by starting the driving of the three feeding rollers by the driving source described above, the sheets S stacked in the cassette 1 are separated and fed one by one.

When the sheet surface height of the sheet S eventually decreases, one end of the lifter trigger lever 23 is pushed up by the pickup roller shaft 3a, the rotation restricting member of the lift-up cam 19 is disengaged, and the lifter 16 is moved by one latch.
Rises and the seat surface height returns.

By repeating this operation, the seat surface height is kept substantially constant. By a series of these operations,
The pickup roller 3 is in contact with the sheet surface only when the sheet S is fed from the cassette 1, and is separated from the sheet surface at other times, so that the pair of the feed roller 4 and the retard roller 5 prevents the sheet S from being fed double. It can be maximized, and double feeding can be reliably prevented.

Details of the lift-up operation will be described with reference to FIGS. 8 (a) and 8 (b). FIG.
By rotating the pickup cam 10 once in the state of (a), as shown in FIG.
The claw portion 25a of 25 is locked to one end of the lift-up lever 9.

As a result, one end of the lifter trigger lever 23 releases the rotation restriction of the lift-up cam 19. The lift-up cam 19 rotates integrally with the lift-up gear 18 when the lift-up gear 18 meshes with the gear 12.
Then, as the lift-up cam 19 rotates, the lift-up mechanism starts the lifter raising operation described below.

The lift-up cam 19 is coaxially provided with a first
A cam 19a and a second cam 19b are arranged. The first cam 19a is an eccentric cam, and is formed so as to be able to contact the first cam contact portion 20a formed on the feed claw 20.

The feed pawl 20 is mounted so as to be rotatable around a shaft 21, but its mounting hole is an elongated hole, and the diameter of the first cam 19a causes the arrow i in FIG. And it is attached so as to be movable in the direction of arrow j in FIG. The rotation of the lift-up cam 19 causes the first cam 19a to rotate, whereby the ratchet gear 17 and the gear meshing portion 20b of the feed pawl 20 can be brought into and out of contact with each other.

When the normal lift-up operation is not necessary, as shown in FIG. 8A, the ratchet gear 17 and the gear meshing portion 20b of the feed pawl 20 are not in mesh with each other. Then, as shown in FIG. 8B, as the lift-up gear 18 rotates, the ratchet gear 18 interlocks with the first cam 19a.
17 and the gear meshing portion 20b of the feed pawl 20 are in mesh with each other.

Then, the second cam shown by the broken line in FIG.
19b and the second cam contact portion 20c of the feed pawl 20 are brought into contact with each other to feed the pawl.
20 swings in the direction of arrow k in FIG. 8 (b) and lifts ratchet gear 17 in the direction of arrow l in FIG. 8 (b). Then, the lock claw 22 is momentarily disengaged when the ratchet gear 17 moves in the direction of the arrow l, is pulled by the spring 26 and meshes with the ratchet one tooth below, thereby suppressing the rotation of the ratchet gear 17.

Finally, as shown in FIG. 8A, when the engagement between the claw portion 25a of the pickup lock lever 25 and one end of the lift-up lever 9 is released, the lifter trigger lever 23 is lifted by one end again. The rotation of the up cam 19 is regulated, the contact between the first cam 19a and the first cam contact portion 20a is released, and the gear meshing portion 20b of the feed pawl 20 and the ratchet gear 17 are disengaged. By repeating the above operation, the lifter 16 is raised to the normal position.

When the series of movements of the lift-up operation are arranged, the lift-up gear 18 rotates and the feed claw 20 rotates.
And ratchet gear 17 mesh with each other (see arrow i in FIG. 8 (b)), ratchet gear 17 is lifted (see arrows k and l in FIG. 8 (b)), lock pawl 22 bites one ratchet below, and feeds The claw 20 and the ratchet gear 17 are disengaged (see arrow j in FIG. 8A).

Next, regarding the lifter cancellation, as shown in FIG.
This will be described with reference to FIG. As described above, normally, only the lock claw 22 is locked to the ratchet gear 17, and when the cassette 1 is pulled out, the projection of the cassette 1 (not shown) pushes the projection of the lock claw 22 to engage the cassette lock spring 27. It is fixed in the broken line state of (a) and (b). As a result, the ratchet gear 17 has no claw to be locked, and the lifter 16 falls due to its own weight.

FIGS. 10 and 11 are views showing the positional relationship among the rails 85, 86, the lifter 16, each pickup roller 3, the feed roller 4, and the retard roller 5. As shown in FIG. 10, the rails 85 and 86 are formed with escape portions 85b and 86b which are bent downward so as to pass under the lifter 16, and the escape portions 85b and 86b cause the rails 85 and 86 to be lifted. The strength of the rails 85 and 86 can be maintained without interfering with the lifting operation of the rail 16.

As described above, the ratchet gear 17 is fixed to the lifter 16, and the ratchet gear 17
The bottom of the device is in contact with a protrusion 7c provided on the feeding frame 7 of the apparatus main body A, so that the rotation angle is regulated.

With the above structure, the ratchet gear is released even if the lifter 16 is released and the lifter 16 is lowered to the lowest position.
The bottom portion of the rail 17 abuts on the protrusion 7a and is regulated.
Since the escape portions 85b and 86b of 86 are provided at positions where they do not collide with the lifter 16, when the lifter 16 descends, the rail
No impact noise is generated by colliding with 85 and 86.

Although the pickup roller 3 can be moved up and down by the above-described structure, in the present embodiment, the pickup roller 3 on the upper cassette side and the pickup roller 3 on the lower cassette side can be moved up and down by the cam. That is, as shown in FIG. 12, the lift-up lever 9 for moving the pickup roller 3 on the lower cassette side up and down contacts the pickup cam 10 as described above, and the cam 10 'which rotates integrally with the pickup cam 10 is brought into contact with the pickup cam 10. A lift-up lever 9 for moving the pickup roller 3 on the upper cassette side up and down abuts.
As a result, as described above, the pickup cams 10, 1
When 0'is rotated, each lift-up lever 9
Oscillates about the shaft, and simultaneously moves up and down both the pickup roller 3 on the lower cassette side and the pickup roller 3 on the upper cassette side.

Thus, the upper and lower cassettes 1a, 1
By rotating the cams 10 and 10 'by rotating each of the pickup rollers 3 of b by one solenoid 13, the number of parts can be reduced and the cost can be reduced. In addition, it is possible to reduce the component installation space.

[Sheet Feeding Structure] Next, the structure of the driving means for driving the feeding means for the sheets stored in the cassette will be described. In the present embodiment, as shown in FIG. 13, the upper cassette side feeding means and the lower cassette side feeding means in one unit are switched and driven by one driving motor 40. .

To explain this concretely, a swing gear is used as the motor gear 40a of the feeding motor 40 which is the driving motor.
41 is meshed, and this swing gear 41 is the drive gear on the upper cassette side.
42 or the lower cassette side drive gear 44 can be meshed. The upper cassette side drive gear 42 meshes with an upper stage feed roller gear 43 attached to one end of the upper stage feed roller shaft 4a through a gear train (not shown).
43 is the upper retard roller shaft 5 through the torque limiter
Upper-stage retard roller gear 46 attached to one end of a
Transmits the driving force to. Similarly, lower cassette side drive gear 44
Meshes with a lower feed roller gear 43 attached to one end of the lower feed roller shaft 4a, and this gear 43 is connected via a torque limiter to the lower retard roller gear 46 attached to one end of the lower retard roller shaft 5a. Transmits the driving force to.

Further, the driving gear 42 transmits a driving force to the upper cassette side pickup roller 3 by a transmission system not shown, and the driving gear 44 transmits a driving force to the lower cassette side pickup roller 3 by a transmission system not shown. It has become.

The shaft 41a of the swing gear 41 can swing within the range of the long hole 90, and as shown in FIG. 13 (a), the feed motor 40 swings in the forward direction in the direction of the arrow in the figure. Dynamic gear shaft 41a
Moves to the upper end side of the long hole 90, the swing gear 41 meshes with the upper drive gear 42, and the driving force is transmitted to the feed roller 4 and the retard roller 5 on the upper cassette side. On the other hand, FIG.
As shown in (b), when the feeding motor 40 is reversely driven in the direction of the arrow in the figure, the swing gear shaft 41a moves to the lower end side of the slot 90, and the swing gear 41 meshes with the lower drive gear 44. , The driving force is transmitted to the feed roller 4 and the retard roller 5 on the lower cassette side.

A stepping motor is used as the feeding motor 40 and the roller driving time is controlled to achieve the required sheet feeding amount. At this time, the feeding motor 40 rotates in the forward and reverse directions, and the swinging gear 41 is swung by utilizing the meshing force of the respective gears to select and feed the sheets to the upper and lower cassettes 1a and 1b. It can be done.

As described above, by switching between the two-stage drive using the forward / reverse rotation of the feeding motor 40, one feeding unit U is sufficient for the feeding unit U. As a result, cost and space advantages are great, and the unit height can be suppressed.

Here, when the retard roller 5 is driven, the retard roller 5 is always driven in the opposite direction to the feeding direction. However, in order to reduce the influence of the gear engagement force on the separation pressure,
As shown in FIG. 14, the retard roller shaft 5a and the retard roller drive shaft 5b are separated, and a joint 50 connects them. Therefore, the retard roller shaft 5a is in a so-called electrically floating state, which may cause electrical noise. Therefore, in the present embodiment, as shown in FIG. 14, a conductive compression spring 51 is press-fitted into the end portion of the retard roller shaft 5a to establish electrical continuity between the retard roller shaft 5a and the retard roller drive shaft 5b. By taking this kind of continuity,
It does not hinder the rotational force of both. By connecting the retard roller drive shaft 5b to another member grounded by a leaf spring or the like (not shown), all the roller shafts can be grounded.

In the above-described embodiment, the case where the electrophotographic image forming means is applied as the image forming means has been described. However, as another image forming means, an image forming means having an ink jet head, a thermal head or the like may be used. The present invention can also be applied to an image forming apparatus equipped.

[0098]

Since the present invention has the above-described structure and operation, the releasing means interlocks with the attachment / detachment operation of the sheet cassette to / from the main body of the apparatus, with respect to the sheet in which the feeding rotary member is accommodated in the sheet cassette. Since the separating rotary body and the pressure contact rotating body are separated from each other while retracting, the retracting means of the feeding rotating body and the separating means between the separating rotary body and the pressure contact rotating body are separately configured as in the conventional case. It is not necessary to reduce the number of parts to reduce the cost and downsize the device.

Further, it is possible to prevent malfunction of the retracting operation of the feeding rotary member and the separating operation of the separating rotary member and the pressure contact rotary member due to the accumulation of the component tolerances.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the overall configuration of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a guide for inserting the sheet cassette into the apparatus main body.

FIG. 3 is a structural explanatory view of a sheet cassette positioning device.

FIG. 4 is an operation explanatory view of the sheet cassette positioning device.

FIG. 5 is an explanatory view of contact and separation of a feed roller and a retard roller.

FIG. 6 is an explanatory view of retracting a pickup roller.

FIG. 7 is a perspective explanatory view of a sheet feeding device.

FIG. 8 is an explanatory diagram of an operation configuration of a pickup roller and a lifter.

FIG. 9 is an explanatory diagram of a lifter release configuration.

FIG. 10 is an explanatory diagram of a relationship between a lifter and a guide rail.

FIG. 11 is an explanatory diagram of a relationship between a lifter and a guide rail.

FIG. 12 is an explanatory view of the upper and lower configurations of pickup rollers of the upper and lower cassettes.

FIG. 13 is an explanatory diagram of a drive switching configuration of upper and lower cassettes to a feeding unit.

FIG. 14 is a diagram illustrating the ground configuration of the retard roller.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Sheet cassette 1a ... Lower cassette 1b ... Upper cassette 1b1 ... Convex part 1c, 1d ... Recessed part 2 ... Sheet stacking plate 3 ... Pickup roller 3a ... Pickup roller shaft 4 ... Feed roller 4a ... Feed roller shaft 5 ... Retard roller 5a ... Retard roller shaft 5b ... Retard roller drive shaft 6 ... Roller holder 7 ... Feed frame 7a ... Slot 7b ... Bearing 7c ... Projection 8 ... Shaft 9 ... Lift up lever 9a ... Spring 10, 10 '... Pickup cam 11 ... Pickup gear 12 ... Gear 13 ... Solenoid 14 ... Motor 15 ... Gear 16 ... Lifter 17 ... Ratchet gear 18 ... Lift-up gear 19 ... Lift-up cam 19a ... First cam 19b ... Second cam 20 ... Feed claw 20a ... First cam Contact part 20b ... Gear meshing part 20c ... Second cam contact part 21 ... Shaft 22 ... Lock claw 23 ... Lifter trigger lever 25 ... Lock-up lock lever 25a ... claw portion 26 ... spring 30 ... retard roller holder 40 ... feeding motor 40a ... motor gear 41 ... swing gear 41a ... shaft 42 ... upper cassette side drive gear 43 ... feed roller gear 44 ... lower cassette side drive Gear 46 ... Retard roller gear 50 ... Joint 51 ... Compression spring 52 ... Release member 52a ... Holder contact part 52b ... Pickup roller push-up part 52c ... Cassette contact part 53 ... Spring 60 ... Cassette holding member 61 ... Body frame 62 ... Stay 63 ... Positioning plate 63a ... Shafts 63b, 63c ... Guide portion 63d ... Groove portion 63e ... Slot 63f ... End portion 63g ... Wall surface 63h ... End portion 63i ... Stopper 64 ... Lever 64a ... Claw portion 65 ... Adjusting plate 65a ... Protrusion 66 ... Guide shaft 67 ... Fixing screws 66a, 67a ... Collar portion 68 ... Spring 81, 85, 86 ... Rail 82 ... Guide member 83 ... Stay 84 ... Holding member 85a, 86a ... Bending and raising portion 85b, 86b ... Relief portion 85c, 86c Sheet guide part 87 ... Bottom plate 88 ... Frame 90 ... Long holes 104, 105 ... Conveying rollers 106 ... Registration rollers 109, 110 ... Cylindrical part 111 ... Laser scanner 112 ... Photosensitive drum 113 ... Optical system 114 ... Developing device 115 ... Transfer charging Device 117… Conveyor belt 118… Fixing device 119… Ejection roller 120… Sorter 121… Double-sided tray 201… Scanning light source 202… Platen glass 203… Original pressure plate 204… Mirror 205… Lens 206… Photoelectric conversion element 207… Branch point A… Device main unit B ... Scanner unit C ... Image forming unit D ... Sheet deck S ... Sheets U1 to U3 ... Feeding unit

Claims (3)

[Claims] 1. A structure that is attachable to and detachable from a device body,
A sheet cassette that stores a sheet, a feeding rotating body that feeds out the sheets that are stored in the sheet cassette, a separating rotating body that is provided on the downstream side in the sheet conveying direction with respect to the feeding rotating body, and the separating rotating body. Pressure contact rotators provided to face each other, and a release means for retracting the feeding rotator with respect to the sheets accommodated in the sheet cassette, and for separating the separating rotator and the pressure rotator. The releasing means retracts the feeding rotating member with respect to the sheets accommodated in the sheet cassette, and the separating rotation is performed in association with an attaching / detaching operation of attaching / detaching the sheet cassette to / from the apparatus main body. A sheet feeding device, characterized in that the body and the pressure contact rotating body are configured to be separated from each other. 2. The sheet feeding device according to claim 1, wherein the releasing means is formed of a wire rod. 3. An image forming apparatus comprising: the sheet feeding device; and an image forming means for recording an image on a sheet fed by the sheet feeding device according to image information.