JP2000128371A - Paper feeding unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive and small paper feeding unit. SOLUTION: A first partially toothless gear 60 and a second partially toothless gear 62 are fixed adjacent to each other on an end part of a first rotary shaft 56. Of these gears, a part of the teeth formed in a circular shape is lacking. Additionally, out of a second rotary shaft 58, a gear 64 is fixed on an end part on the same side of the end part of the first rotary shaft 56. This gear 64 is interlocked with the second partially toothless gear 62 through a transmission gear 68. A double feeding preventive roller 54 is devised to rotate with the second rotary shaft 58 by fixing the double feeding preventive roller 54 to prevent double feeding of a recording medium delivered from a paper feeding roller 52 on the second rotary shaft 58.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feeding unit for feeding recording media one by one in a predetermined direction (paper feeding direction) from a cassette tray on which a plurality of recording media are stacked.

[0002]

2. Description of the Related Art As an output device of a computer or a work station, an ink jet type image forming apparatus for forming an image on a recording medium by discharging ink, or an electrophotographic type forming apparatus for forming an image on a recording medium using a developer or the like. Image forming apparatuses are known. These image forming apparatuses are usually provided with a cassette tray in which a plurality of recording media are stored in a stacked state. The cassette tray is incorporated so as to be freely inserted into and removed from the main body of the image forming apparatus. A paper feed unit that feeds the recording media stacked on the cassette tray one by one in a predetermined paper feed direction at a predetermined timing is arranged near the cassette tray.

The paper feed unit is provided with a paper feed roller that comes into contact with a recording medium stacked on a cassette tray and feeds the recording medium in the paper feeding direction, and is disposed slightly downstream of the paper feeding roller in the paper feeding direction. And a double feeding prevention roller for preventing double feeding of the recording medium. The feed roller normally feeds the recording medium one sheet at a time, but a plurality of recording media may be fed simultaneously for some reason. In order to prevent such double feeding, a double feeding preventing roller is disposed slightly downstream of the sheet feeding roller in the sheet feeding direction. The paper feed roller rotates at a predetermined timing to feed the recording medium in the paper feed direction, and the double feed prevention roller rotates according to the rotation of the paper feed roller to prevent double feed.

The paper feed roller is fixed to a rotary shaft for the paper feed roller, and a gear for rotating the rotary shaft for the paper feed roller is fixed to an end of the rotary shaft for the paper feed roller. This gear is meshed with a drive gear, and the rotation of the drive gear causes the rotation shaft of the paper feed roller to rotate, so that the paper feed roller also rotates. On the other hand, in order to rotate the double feed prevention roller in accordance with the rotation of the paper feed roller, a drive source different from the above-described drive gear, an electromagnetic clutch, and the like are used.

[0005]

As described above, the double feed prevention roller provided in the conventional paper feeding unit is rotated by a driving source different from the driving source of the paper feeding roller.
An electromagnetic clutch or the like is used to rotate the double feed prevention roller according to the rotation of the paper feed roller. For this reason,
The conventional paper feeding unit requires a drive source, an electromagnetic clutch, and the like, and requires a space for arranging them, and thus there is a problem that the cost is high and the paper feeding unit becomes large.

The present invention has been made in view of the above circumstances, and has as its object to provide a low-cost, small-sized paper feeding unit.

[0007]

According to a first aspect of the present invention, there is provided a sheet feeding unit for feeding a recording medium one by one in a predetermined direction from a cassette tray on which a plurality of recording media are stacked. (1) a first rotation shaft extending in a predetermined direction, disposed above a portion of the cassette tray on the downstream side in the sheet feeding direction; and (2) a recording medium rotated with the first rotation shaft. In the predetermined direction,
A half-moon-shaped paper feed roller fixed to the first rotating shaft;
(3) a first partially toothed gear which is fixed to an end of the first rotating shaft and meshes with a predetermined drive gear, wherein a predetermined portion of the circumferentially formed teeth lacks teeth; A second rotating shaft disposed downstream of the first rotating shaft in the sheet feeding direction and extending in parallel with the first rotating shaft; and (5) fixed to the second rotating shaft and rotating together with the second rotating shaft. A double feed prevention roller for preventing double feeding of the recording medium sent out by the paper feed roller, and (6) fixed to an end of the second rotating shaft and interlocked with rotation of the first toothless gear. And a gear that rotates to rotate the second rotation shaft.

[0008] Here, the paper feed unit is (7) the first
A predetermined portion of the circumferentially formed teeth fixed to the first rotary shaft adjacent to the toothless gear and transmitting the driving force of the predetermined drive source to the gear at a predetermined timing; A second missing gear may be provided.

[0009] The sheet feeding unit may further include (8) a transmission gear disposed between the second missing gear and the gear, for transmitting a rotational force of the second missing gear to the gear. Is also good.

[0010] Further, the first missing tooth gear is configured such that (9) a base of a plurality of teeth that meshes with the predetermined drive gear first among a plurality of teeth adjacent to the portion where the teeth are missing is freely bent. May be done.

Furthermore, the bases of the plurality of teeth that mesh first with the predetermined drive gear are wider (10) from the base of the teeth that first mesh with the predetermined drive gear toward the base of the teeth that mesh later. It may be something.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a paper feeding unit according to the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram showing the internal structure of a copying machine in which one embodiment of the paper feeding unit of the present invention is incorporated.

An original cover 12 that can be opened and closed is disposed on the top surface of the copying machine 10. A document table glass 14 on which a document 15 is placed is arranged below the document pressure plate 12. An operation panel (not shown) for inputting the number of copies and the like is arranged on the front side of the top surface. The copying machine 10 is provided with a universal cassette 16 for accommodating a plurality of cut sheets so that the universal cassette 16 can be taken in and out of the main body of the copying machine 10. The right side wall of the copying machine 10 is provided with a rectangular manual tray 18 capable of feeding small-sized recording paper such as postcards. The manual feed tray 18 rotates in the direction of arrow C about the lower side 18a and opens to a position where a recording medium can be placed (a position indicated by a two-dot chain line). The left side wall of the copying machine 10 is provided with a paper discharge tray 20 on which recording paper on which an image is formed is stacked.

A procedure for forming an image in the copying machine 10 will be described.

The original 15 is placed on the upper surface of the original platen glass 14 so that the image side faces down.
Hold 5 and fix. The image recorded on the manuscript 15 is
A known optical system 28 including a light source lamp (not shown) and the like.
And light (broken line A) carrying the information of the image recorded on the original is obtained. This light is applied to the photosensitive drum 32 uniformly charged by the charger 30 to form an electrostatic latent image. The electrostatic latent image is developed with the toner (developer) supplied from the developing device 34 to form a developed image.

On the other hand, a recording medium such as recording paper is fed from the universal cassette 16 in the direction of arrow B (paper feeding direction) by a paper feeding unit 50 having a paper feeding roller 52 and a double feeding prevention roller 54 to be described later. Then, the transfer unit 36 transfers the developed image to a recording medium. The recording medium to which the developed image has been transferred is transported to the fixing device 40 by the transport device 38. The fixing device 40 is provided with a heat roller 42 and a press roller 44, and these two rollers 42, 44
The recording medium is conveyed while being sandwiched therebetween, and the developed image is fixed on the recording medium. The recording medium on which the developed image has been fixed in this manner is discharged and stacked on the discharge tray 20. The toner remaining on the photosensitive drum 32 after the transfer is scraped off by the cleaning device 46. Also, the recording medium can be fed from the manual feed tray 18, and the procedure for forming an image on the recording medium fed from the manual feed tray 18 is the same as described above.

The structure of the sheet feeding unit will be described with reference to FIGS.

FIG. 2 is a perspective view showing the entire sheet feeding unit, and FIG. 3 is an enlarged perspective view showing an end of the sheet feeding unit.

The paper feeding unit 50 has a half-moon-shaped paper feeding roller 52 for feeding out the recording medium loaded on the universal cassette 16 (see FIG. 1) in the direction of arrow B (paper feeding direction). The paper feed roller 52 is fixed to a first rotation shaft 56 extending in a direction perpendicular to the direction of arrow B (an example of a predetermined direction in the present invention), and rotates together with the first rotation shaft 56. The first rotating shaft 56 is disposed above a portion of the universal cassette 16 on the downstream side in the sheet feeding direction. A second rotation shaft 58 extends downstream of the first rotation shaft 56 in the sheet feeding direction in parallel with the first rotation shaft 56.

Two gears are fixed adjacent to each other at the end of the first rotating shaft 56. These gears are the first missing gear 6
0 and the second missing tooth gear 62, both of which are partially missing teeth among the circumferentially formed teeth. However, the first
The part of the toothless gear 60 where the teeth are missing and the part of the second gear 62 where the teeth are missing are displaced from each other and do not overlap.

A gear 64 is fixed to an end of the second rotating shaft 58 on the same side as the end of the first rotating shaft 56.
The gear 64 is interlocked with the second missing tooth gear 62 via a transmission gear 68 rotatably fixed to a frame 66 of the sheet feeding unit 50. The two gears 64 and 68 are not toothless gears but have teeth formed in a circumferential shape. Second rotating shaft 5
A double feed prevention roller 54 for preventing double feeding of the recording medium sent out by the paper feed roller 52 is fixed to 8, and the double feed prevention roller 54 rotates together with the second rotation shaft 58.

One end of a connecting arm 70 is rotatably fixed to an end of the first rotating shaft 56 to which the first toothless gear 60 is fixed. One end of a tension coil spring 72 is hung on the other end of the connecting arm 70. The other end of the tension coil spring 72 is hung on a portion of the frame 66 near the second rotation shaft 58. Further, a step 56a is formed at the above-mentioned end of the first rotary shaft 56, and a claw 76 of a solenoid 74 (see FIG. 4) is engaged with the step 56a. The claw 76 is disengaged from the step 56a when the solenoid 74 is turned on, and the tension coil spring 72
Causes the first rotating shaft 56 to rotate slightly in the direction of arrow D.

The rotation of the first rotation shaft 56 and the second rotation shaft 58 will be described with reference to FIGS.

FIG. 4 is a side view of the sheet feeding unit of FIG. 2 as viewed from the front side of the figure, and FIG. 5 is a side view of the sheet feeding unit of FIG. 4 viewed from the opposite side. FIG. 6 is a side view showing the sheet feeding unit in which the first missing gear meshes with the driving gear. In these figures, the same components as those shown in FIGS. 2 and 3 are denoted by the same reference numerals.

When an ON signal is transmitted from a control device (not shown) of the main body of the copying machine 10 (see FIG. 1) to the solenoid 74, as described above, the pawl 76 is lowered to come off the step 56a, and the tension coil spring The first rotating shaft 56 is slightly rotated in the direction of arrow D by the urging force of 72. As a result, FIG.
As shown in (1), the drive gear 80 and the first missing gear 60 mesh with each other, and the rotation of the drive gear 80 causes the first missing gear 60 to also rotate. The first rotary shaft 56 also rotates with the rotation of the first toothless gear 60, and the second toothless gear 62 and the paper feed roller 52 also rotate. Transmission gear 6 meshing with second missing gear 62
8 rotates and the gear 64 also rotates. As the gear 64 rotates, the second rotating shaft 58 also rotates, and the double feed prevention roller 54
Also rotate.

As described above, the rotation of the drive gear 80 causes the paper feed roller 52 to rotate, and in conjunction with this rotation, the double feed prevention roller 54 also rotates. As a result, the double feeding of the recording medium sent to the sheet feeding roller 52 is prevented by the double feeding preventing roller 54. Further, since the paper feed roller 52 and the double feed prevention roller 54 are rotated by the rotation of one drive gear 80, only one drive source is required to drive these two rollers 52 and 54. Thus, a small-sized paper supply unit can be obtained at a lower price than in the case of using.

When the paper feed roller 52 starts to rotate and makes one rotation, the solenoid 74 is turned off and the toothed portion of the first toothless gear 60 is moved to the drive gear 80 as shown in FIG.
And the first toothless gear 60 and the drive gear 80 are disengaged. As a result, the pawl 76 rises and is caught by the step 56a to stop the rotation of the first rotary shaft 56, so that the paper feed roller 52 and the double feed prevention roller 54 are stopped.
Also stop rotating. The recording medium sent to the paper feed roller 52 is further transported downstream in the paper feed direction by a transport roller (not shown) disposed downstream in the paper feed direction.

Here, the shape of the first toothless gear 60 will be described.

In the first toothless gear 60, a plurality of teeth are arranged adjacent to the part where the teeth are missing. The base 6 of the plurality of teeth that meshes with the drive gear 80 first among the plurality of teeth
1 is configured to bend freely without anything under it. Further, the base 61 is provided with the drive gear 8 of the base 61.
0, it becomes thicker from the base 61a of the first meshing tooth toward the base 61b of the second meshing tooth.

As described above, since the base portion 61 is configured to flex freely, it is possible to reduce the impact at the time of meshing with the drive gear 80, and to provide the first toothless gear 6 having excellent durability.
0 is obtained. Further, since the diameter increases from the base 61a toward the base 61b, the base 61a of the tooth that meshes with the drive gear 80 is thinner and more easily bent, and the first toothless gear 60 having more excellent durability. Becomes

[0032]

As described above, according to the sheet feeding unit of the present invention, the double feeding of the recording medium sent to the sheet feeding roller is prevented by the double feeding preventing roller. The gear for rotating the second rotating shaft to which the double feed prevention roller is fixed rotates in conjunction with the rotation of the first toothless gear. Therefore,
Since the second rotating shaft is also rotated by the driving force of the driving gear for rotating the first toothless gear, a separate device for rotating the second rotating shaft is not required. As a result, 1
Since both the paper feed roller and the double feed prevention roller can be rotated by one driving source, a small-sized paper feed unit at low cost can be obtained.

Here, the paper feed unit is fixed to the first rotating shaft adjacent to the first toothless gear and transmits a driving force of a predetermined drive source to the gear at a predetermined timing. In the case where a second missing gear in which predetermined portions of the formed teeth are missing is provided, the driving force is transmitted to the gear at a predetermined timing by the second missing gear, so that the double feed prevention roller is moved to a predetermined position. Can be rotated at the timing

In the case where the sheet feeding unit has a transmission gear disposed between the second toothless gear and the gear, the transmission gear transmitting the rotational force of the second toothless gear to the gear, the transmission gear is provided via the transmission gear. Since the rotational force of the second toothless gear is transmitted to the gear, the rotational force can be reliably transmitted with a simple configuration.

Further, the first toothless gear is configured such that the bases of a plurality of teeth that mesh with a predetermined drive gear among a plurality of teeth adjacent to the portion where the teeth are missing flex freely. In this case, since the bases of the plurality of teeth that mesh first with the drive gear are configured to flex freely, the impact when meshing with the drive gear can be reduced, and a first toothless gear with excellent durability can be obtained. Can be

Still further, in the case where the bases of the plurality of teeth that mesh first with the predetermined drive gear are thicker from the base of the teeth that first mesh with the predetermined drive gear toward the base of the teeth that mesh later. Since the base of the tooth that meshes first with the drive gear is thinner and more easily bent, a first toothless gear with higher durability can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an internal structure of a copier in which an embodiment of a sheet feeding unit according to the present invention is incorporated.

FIG. 2 is a perspective view showing the entire sheet feeding unit of the present invention.

FIG. 3 is an enlarged perspective view showing an end portion of the sheet feeding unit of FIG. 2;

FIG. 4 is a side view of the sheet feeding unit of FIG. 2 as viewed from the near side of the figure.

FIG. 5 is a side view of the sheet feeding unit of FIG. 4 as viewed from the opposite side.

FIG. 6 is a side view showing a sheet feeding unit in which a first toothless gear meshes with a driving gear.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Copier 50 Paper feed unit 52 Paper feed roller 54 Double feed prevention roller 56 First rotary shaft 58 Second rotary shaft 60 First missing gear 61 Base 62 Second missing gear 64 Gear 68 Transmission gear

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nasaku Kamiya 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 3F343 FA02 FB04 JA03 JA18 JD09 JD33 LC23 LD24

Claims (5)

[Claims] 1. A sheet feeding unit for feeding recording media one by one in a predetermined direction from a cassette tray on which a plurality of recording media are stacked, wherein a portion of the cassette tray on a downstream side in the sheet feeding direction is provided. A first rotating shaft disposed in a predetermined direction, the first rotating shaft being arranged and rotating along with the first rotating shaft to feed a recording medium in the predetermined direction; a semi-lunar-shaped paper feed roller fixed to the first rotating shaft; A first toothless gear, which is fixed to an end of the first rotation shaft and meshes with a predetermined drive gear, has a predetermined part of teeth formed in a circumferential shape and lacks teeth of the first rotation shaft; A second rotating shaft disposed downstream of the sheet feeding direction and extending in parallel with the first rotating shaft; and a second rotating shaft fixed to the second rotating shaft and rotated together with the second rotating shaft. A double feed prevention roller for preventing double feeding of a recording medium; A gear fixed to the end of the second rotating shaft and rotating in synchronization with the rotation of the first toothless gear to rotate the second rotating shaft. 2. A circumferentially-shaped member fixed to the first rotating shaft adjacent to the first toothless gear and transmitting the driving force of the predetermined driving source to the gear at a predetermined timing. The sheet feeding unit according to claim 1, further comprising a second missing gear in which a predetermined portion of the teeth is missing. 3. A transmission gear disposed between the second missing gear and the gear, for transmitting a rotational force of the second missing gear to the gear. Paper feed unit according to. 4. The first toothless gear, wherein a base of a plurality of teeth that meshes with the predetermined drive gear first among a plurality of teeth adjacent to a part where the teeth are missing is configured to flex freely. The sheet feeding unit according to claim 1, 2, or 3, wherein 5. The base of the plurality of teeth that meshes first with the predetermined drive gear is thicker from the base of the tooth that first meshes with the predetermined drive gear toward the base of the tooth that meshes later. The sheet feeding unit according to claim 4, wherein: