JPH0639297B2 - Reverse paper feeder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a reversing sheet feeding device, and more specifically,
The present invention relates to a reversing paper feeding device in which the feeding direction of paper from a paper feeding cassette by a paper feeding roller and the paper feeding direction by a registration roller which operates in synchronization with an optical system are set to be opposite.

<Prior Art> Conventionally, in an OA device such as a copying machine, a paper feed cassette containing a large number of sheets of a predetermined size is used, and when it becomes necessary to use sheets of different sizes, a sheet feeding cassette is used. It is generally used that the paper size can be easily changed only by replacing the paper cassette. In recent years, the size of the manuscript that can be copied tends to increase. Therefore, as the paper feed cassette, a large-sized one capable of accommodating a large-sized paper corresponding to the size of the manuscript that can be copied is used. It has become to.

Therefore, when the paper feed cassette is attached to the main body of the copying machine, an installation area much larger than the size of the main body of the copying machine is required, which causes a problem that utilization efficiency of a limited space such as an office is deteriorated. Occur.

In order to solve such a problem, conventionally, the feeding direction of the paper from the paper feeding cassette by the paper feeding roller and the conveying direction of the paper by the registration roller operating in synchronization with the optical system are set to be opposite. In addition, even when the sheet feeding cassette is installed, the sheet feeding cassette is
For example, it is possible to achieve compactness of the entire copying machine by preventing the optical system, which requires the widest planar shape, from protruding from the vertical projection position.

As such a reverse sheet feeding device, a sheet feeding roller for feeding the sheets one by one from the sheet feeding cassette, a feed roller for feeding the sheet fed by the sheet feeding roller toward the registration roller, and a feeding roller It is composed of a guide member that reverses the conveying direction of the conveyed sheet, and controls the drive of the above-mentioned paper feed roller and registration roller in accordance with a predetermined sheet conveying timing, and also the drive roller is driven by a clutch or the like. Is used to control the timing in accordance with the above-mentioned sheet conveyance timing.

Therefore, by rotationally driving the paper feed roller and the feed roller, it is possible to perform primary paper feeding until the leading edge of the paper comes into contact with the registration roller, and then by rotationally driving the feed roller and the registration roller, It is possible to carry out the secondary paper feeding for performing the copying operation.

<Problems to be Solved by the Invention> With the reversing paper feeding device having the above-described configuration, it is possible to reduce the installation area of the copying machine and to reliably carry the paper. Drive the paper feed roller,
Since the control must be performed according to the driving state of the registration rollers, the electric control device becomes complicated, and the mechanical rotational force transmission control device becomes complicated. There are some inconveniences in that there is not much freedom in the mounting position, the design is difficult, or an extra addition is required.

This invention has been made in view of the above problems,
An object of the present invention is to provide a reversing paper feeding device that does not need to control the drive of the feed roller and can surely perform the primary paper feeding and the secondary paper feeding of the paper.

<Means for Solving Problems> In order to achieve the above object, a reversing sheet feeding device of the present invention is configured to feed a sheet from a sheet bundle in a predetermined direction one by one, and The image forming apparatus includes a registration roller that temporarily stops the existing paper and re-conveys it in synchronism with the optical system, and guides the guide roller to the registration roller by reversing the conveyance direction of the paper by the paper feed roller. Of the feed roller, which is in close proximity to the end on the paper feed roller side of the sheet feeding section, and which is constantly driven to rotate, and which conveys the paper to the registration roller side between the feed roller and the feed roller. In a reversing paper feeding device for feeding and driving a sheet over the entire length in the sheet feeding direction, the sheet feeding roller supports the outer guide plate and the inner guide member constituting the guide portion, and the driven member. It is provided in the main body of the image forming apparatus to hold the driven member, and normally the driven member is pressed against the feed roller, and due to the bending of the paper, a repulsive force larger than the repulsive force due to the allowable bending from the paper is applied to the driven member. Switching means for allowing the paper to slip between the driven member and the feed roller when the paper feeds, and the outer guide plate and the inner guide member form the paper between the feed roller and the registration roller. In the state in which a curlable space is formed, a conveyance path from the paper feed roller to the registration roller is partitioned, and the conveyance path is set to be shorter than the length of the paper to be conveyed in the conveyance direction. It is characterized by that.

However, it is preferable that the space between the paper feed roller and the feed roller is a space portion capable of forming a bend in the paper when the conveyance of the paper to the registration roller is completed. Formed in a convex curved surface, the distance between the outer guide plate and the inner guide member is such that the paper comes into contact with the outer guide plate when the paper is conveyed to the registration rollers, and the paper is on the outer surface of the inner guide member when the paper is conveyed by the registration rollers. The feed roller is preferably formed at a contacting interval, the feed roller is preferably attached to a sheet conveyance direction reversal portion, and the driven member is a driven roller that is in rolling contact with the feed roller. A roller may be used, and the switching means may be a spring that elastically biases the driven member toward the feed roller.
Further, the paper feed roller may be one that prevents double feeding of paper by being pressed against a friction pad.

<Operation> In the case of the reversing sheet feeding device having the above configuration, the sheets accommodated in the sheet feeding cassette are fed one by one by the sheet feeding roller. Here, since the paper feed roller drives the paper to be conveyed over the entire length in the paper conveyance direction, the paper feed roller further cooperates with a feed roller to further convey the paper and configure an outer guide plate and an inner guide that form a guide unit. It is guided between the member and the primary paper feed.

The guide portion of the present invention is composed of an outer guide plate and an inner guide member. The outer guide plate and the inner guide member define a conveyance path from the paper feed roller to the registration roller in a state where a space capable of bending the paper is formed between the feed roller and the registration roller. . Then, the transport path is set shorter than the length of the sheet to be transported in the transport direction. At the same time, the paper feed roller drives the paper to be conveyed over the entire length in the paper conveyance direction. Therefore, by bringing the paper that has passed through the guide portion into contact with the registration roller, the paper is separated between the feed roller and the registration roller. Bend between.

When the repulsive force, which is larger than the repulsive force due to the curvedness that should be allowed, acts on the driven member from the sheet due to the bending of the sheet, the switching unit separates the driven member from the feeding roller, so that the rotation of the feeding roller is prevented. , Does not act as a conveying force on the sheet, and the sheet slips while being curved by a predetermined amount.

Next, when the registration roller is rotationally driven and the secondary sheet feeding is started, the sheet is pulled by the registration roller, and the repulsive force of the sheet due to the above-described bending to the driven member does not act, so the switching means Presses the driven member against the feed roller again, and causes the paper to be pinched between the driven member and the feed roller. For this reason, the rotation of the feed roller acts on the paper as a conveyance force, and the feed roller cooperates with the registration roller to reliably convey the paper.

<Example> Hereinafter, detailed description will be given with reference to the accompanying drawings illustrating an example.

FIG. 3 is a schematic view showing the internal mechanism of a copying machine as an image forming apparatus equipped with the reversing paper feeding device of the present invention. The copying machine main body (1) comprises a light source, a reflecting mirror, and a lens. Only the portion containing the constructed optical system (2) is wide, and the portion containing the remaining copy processing section (3) and copy paper transporting section (4) is formed narrow.

More specifically, a contact glass (11) for supporting an original to be copied is provided at a predetermined position on the upper surface of the copying machine main body (1), and the optical system (2) allows the original to be copied. A light source (21) for scanning exposure, reflecting mirrors (22), (23) and (24) that guide reflected light from a document to a lens (25), and guide light that has passed through the lens (25) to a copy processing unit (3). It is composed of a reflecting mirror (26). The copy processing section (3) includes a photosensitive drum (31) that rotates in one direction for each copying operation, a charger (32) sequentially arranged around the photosensitive drum (31), and a developing device (33). ),
Transfer charger (34), separation belt (35), and cleaner
It consists of (36). The copy paper transport section (4) is a paper feed cassette mounted below the copy processing section (3).
A reversing paper feeding device (5) for feeding the paper one by one from the (12), and a registration roller (4) driven in synchronization with the optical system (2).
1), a conveyance roller (42) that conveys the sheet separated from the photoconductor drum (31) by the separation belt (35), and a fixing device (4
3) and a discharge roller (44) for discharging the paper onto the carry-out tray (15), and at the predetermined position of the stack bypass (45) attached at the predetermined position of the copying machine main body (1), the paper Attach the pre-feed roller (46) and the paper feed roller (47) to convey the paper to the registration roller (41),
Paper feed from (12) and paper feed from the stack bypass (45) are selectable.

FIG. 1 is a diagram showing in detail the configuration of the reversing paper feeding device (5). The paper feeding roller (51), the feed roller (52), the driven roller (53) as a driven member, and the guide portion (55). ) Is the main part.

The paper feed roller (51) is mounted on the paper which is rotated upward by a push-up lever (14) mounted at a predetermined position inside the copying machine main body (1) with the paper feed cassette (12) attached. The paper (P) is fed one by one by rotating while being pressed against the upper surface of the paper (P) supported by the plate (13), and the fed paper (P) is fed. Coro (5
It is guided between 1) and the friction pad (58) so that double feeding can be reliably prevented. And the paper feed roller
(51) and the friction pad (58), the space where the leading edge of the paper (P) can be corrected by allowing the paper (P) to bend.
Forming (59).

The space (59) is continuously connected to the feed roller (52) which is constantly driven to rotate, and the leaf spring (5) as a switching unit.
The driven roller (5) pressed against the feed roller (52) by the (4)
3) is attached, and the feed roller (5
2) and a guide member (55) including an outer guide plate (56) and an inner guide member 57 is attached between the driven roller (53) and the registration roller (41).

More specifically, the inner guide member (57) is entirely made of synthetic resin or the like, and a plurality of ribs having a convex curved side surface are formed on the outer surface of the inner guide member (57). An outer guide plate (56) made of iron or the like is attached so that the space between the two is approximately 1 mm, and a space for sheet conveyance is provided between the two. Then, of the inner guide member (57),
The feed roller (52) is rotatably supported at a position slightly separated from the space, and a switch (60) for detecting the paper (P) is supported immediately before the registration roller (41). Further, the driven roller (53) is a leaf spring (54).
Is attached to the opening / closing member (61) supported by the main body (1) of the copying machine so as to be openable and closable. With the opening / closing member (61) open, the driven roller (53) feeds the roller (52). The driven roller (53) can be pressed against the feed roller (52) with the open / close member (61) closed. However, the urging force of the leaf spring (54) is
Normally, the driven roller (53) is pressed against the feed roller (52), and due to the curving of the paper (P), a repulsive force larger than the repulsive force due to the permissible curving is applied to the paper.
(P) acts on the driven roller (53), the driven roller (5
In order to allow the paper (P) to slip between the feeding roller (52) and the feeding roller (52), the force is set to be smaller than the waist strength of the paper (P). Incidentally, (62) is a magnet.

Further, reference numeral (48) is a lever which, when a sheet is set on the stack bypass (45), is rotated upward due to contact of the sheet and moves the forward feed roller (46) upward.

With the above configuration, by rotating the sheet feeding roller (51) to feed the sheets (P) one by one from the inside of the sheet feeding cassette (12), the feeding roller ( 52) is guided between the driven roller (53) and the rotation of the feed roller (52) is added as a conveying force for the sheet (P), so that a sufficient conveying force acts and the sheet (P) It is conveyed until it contacts the registration roller (41) after passing through the guide portion (55). And
Since the paper (P) is conveyed by the paper feed roller (51) for a predetermined time even after the leading end of the paper (P) contacts the registration roller (41), as shown by the solid line in FIG. (P) is placed along the entire surface of the outer guide plate (56), and the driven roller (53) is moved by the waist of the paper (P) against the biasing force of the spring (54). ) Is rotated, no conveyance force can be applied to the sheet (P), and the sheet (P) is unnecessarily loaded with the registration roller (41).
It is possible to reliably prevent the inconvenience of causing a jam by transporting the paper toward the side. However, when the paper (P) is not so stiff, the driven roller (53) hardly moves, but the pressure contact force with respect to the feed roller (52) is weakened.
The feed roller (52) and the paper (P) slip, and the conveyance of the paper (P) can be stopped. Further, the above-mentioned primary paper feeding is stopped inside the space (59) with the paper (P) being deflected by about 5 to 10 mm from the regular carrying surface, and the front end of the paper (P) is corrected. be able to.

After that, when secondary feeding is performed, the feeding roller (51) is in a stopped state, and the frictional force between the friction pad (58) and the sheet (P) acts as a resistance force. When the conveyance of the paper (P) by the registration rollers (41) is started, the second
As indicated by the broken line in the figure, the paper (P) is immediately pulled and comes into a state along the outer surface of the inner guide member (57), so that the waist of the paper (P) is no longer the feed roller (53). 52) can no longer be separated. Therefore, the driven roller (53) is pressed against the feed roller (52) with a strong pressure, and the rotation of the feed roller (52) is not slipped and the paper (P) is not slipped.
It acts as a transport force for the registration roller.
Secondary paper feed for feeding the paper (P) toward the copy processing section (3) by the conveyance force applied to the paper (P) by the (41) and the feed roller (52) overcoming the resistance force. Can be accomplished.

When a jam occurs between the paper feed roller (51) and the feed roller (52), the jammed paper (P) can be easily removed by opening the opening / closing member (61). it can.

As is clear from the above description, the feed roller (52) is constantly rotating, but the driven roller (53) is in pressure contact with the sheet (P) so as to give a conveying force. Since it is only during the period, the paper (P) is conveyed by rotating the paper feed roller (51) with the registration roller (41) stopped, and the paper (P) abuts the registration roller (41). In addition, by rotating the registration roller (41) until the state along the inner surface of the outer guide plate (56) and with the paper feed roller (51) stopped, the paper (P) is guided inside. It is only during the period along the outer surface of the member (57), and during the period other than the above period, the paper (P) is applied with no or almost no carrying force, which is inconvenient for carrying the paper (P). It does not occur.

Further, as a mounting position of the feed roller (52), as shown in the drawing, it is most preferable to install it at a position where the conveying direction of the paper (P) changes abruptly. The selective control between the state in which the force can be reliably transmitted and the state in which the transport force cannot be transmitted due to slipping can be reliably performed regardless of the frictional resistance of the feed roller (52).

As is clear from the above description, as long as the pressure contact force of the feed roller (52) can be changed depending on the conveyance state of the sheet (P), the conveyance force transmission state and the slip state can be selectively controlled. Therefore, the driven roller (53) is not always necessary and can be omitted.

Incidentally, the present invention is not limited to the above-mentioned embodiment, and for example, it is possible to use a pressing body having a friction coefficient not so high, which is composed of a leaf spring or the like instead of the driven roller (53). , Omitting the space (59) for causing the paper (P) to bend (however, in this case, the conveying force by the registration roller (41), the conveying force by the feed roller (52), and the friction pad ( Strictly setting and adjusting the relationship of the frictional force according to 58) is required), and various design changes can be made within the range not changing the gist of the present invention.

<Effects of the Invention> As described above, according to the present invention, it is possible to selectively control the pressure contact state and the non-pressure contact state with respect to the feed roller depending on the waist of the sheet, so that the feed roller can be constantly rotated. An electrical and mechanical control device for controlling the rotation of the feed roller can be eliminated altogether, and there is a unique effect that the overall structure can be simplified.

Further, in the present invention, in order to bend the paper between the feed roller and the registration roller, a conveyance path shorter than the length of the paper to be conveyed in the conveyance direction is provided between the paper feed roller and the registration roller. Since the sheet conveying path is shortened, the guide portion can be downsized and the image forming apparatus, which is the original purpose of the reversing sheet feeding apparatus, can be downsized.

Moreover, in the present invention, since the paper is curved between the feed roller and the registration roller, and the paper transport path is set short for that, the paper transport force of the paper feed roller of the image forming apparatus is reduced. As a result of being able to perform the primary sheet feeding by using the, it is not necessary to provide a conveying means for the primary sheet feeding between the sheet feeding roller and the feeding roller, and accordingly,
This not only contributes to further miniaturization, but also has the advantage that the increase in the number of parts and the cost of the product can be suppressed.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an essential part of a reversing paper feeding device according to the present invention, FIG. 2 is a longitudinal sectional view showing an essential part for explaining an operation state, and FIG. 3 is a copying machine incorporating the reversing paper feeding device. Schematic diagram showing the main parts, (12) …… paper feed cassette, (41) …… registration roller, (51) …… paper feed roller, (52) …… feed roller, (53) …… as a driven member Driven roller, (54) …… spring as biasing means, (55) …… guide part, (56) …… outer guide plate, (57) …… inner guide member, (58) …… friction pad, ( 59) …… Space

Claims (7)

[Claims] 1. An image forming apparatus comprising: a sheet feeding roller that conveys sheets one by one in a predetermined direction from a sheet bundle; and a registration roller that pauses the conveyed sheets and re-conveys them in synchronization with an optical system. A guide part provided in the apparatus, which reverses the sheet conveying direction by the paper feed roller and guides it to the registration roller, a feed roller which is in close proximity to the end of the guide part on the paper feed roller side, and which is constantly driven to rotate, and a feed roller. A follower member that is provided so as to be able to come into contact with and separate from the feed roller and that conveys the sheet to the registration roller side between the feed roller, and the sheet feeding roller conveys and drives the sheet over the entire length in the sheet conveying direction. In a reversing paper feeding device, the outer guide plate and the inner guide member that form the guide portion and the driven member are provided in the main body of the image forming apparatus to support the driven member, and normally the driven member is pressed against the feed roller. In addition, due to the curving of the sheet, when a repulsive force larger than the repulsive force due to the curving that is allowed is applied to the driven member from the sheet, the sheet is prevented from slipping between the driven member and the feed roller. The outer guide plate and the inner guide member form a space in which the sheet can be curved between the feed roller and the registration roller, from the paper feed roller to the registration roller. A reversing sheet feeding device, which divides a conveying path to reach, and the conveying path is set to be shorter than a length of a sheet to be conveyed in a conveying direction. 2. The space between the paper feed roller and the feed roller is a space where a bend can be formed in the paper when the paper is completely conveyed to the registration rollers. Reverse paper feeder. 3. A guide portion is formed in a convex curved surface shape as a whole, and a distance between the outer guide plate and the inner guide member is such that the paper comes into contact with the outer guide plate when the paper is conveyed to the registration rollers, and the paper is formed by the registration rollers. The reversal sheet feeding device according to claim 1, wherein the sheet is formed at an interval so as to contact the outer surface of the inner guide member during conveyance. 4. The reversing paper feeding device according to claim 1, wherein the feed roller is attached to a reversing portion of the paper conveyance direction. 5. The reversing paper feeding device according to claim 1, wherein the driven member is a driven roller which is in rolling contact with the feed roller. 6. The reversing sheet feeding device according to claim 1, wherein the switching means is a spring that elastically biases the driven member against the feed roller. 7. The reversing sheet feeding device according to claim 1, wherein the sheet feeding roller is pressed against the friction pad to prevent double feeding of the sheet.