JP2002255366A - Paper feeder - Google Patents

Abstract

(57) [Summary] [PROBLEMS] When the detection switch 9 does not operate and the rotation of the push-up lever 4 for pushing up the paper placing table 3 is not stopped, the drive of the motor 5 is pushed up at a predetermined upper limit position. It is not transmitted to the lever 4 to prevent damage to the members of the sheet feeding device. SOLUTION: When a paper placing table 3 moves to a preset upper limit position between a motor 5 and a push-up member 4 in a sheet feeding device, the drive transmission from the motor 5 to the push-up member 4 is released. The transmission gear on the push-up member 4 side is a toothless gear 81 to prevent the push-up member 4 from rotating beyond the rotation allowable angle α.

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 used in an image forming apparatus such as a printer, a facsimile, a copying machine, and the like.

[0002]

2. Description of the Related Art Conventionally, paper feeders used in printers, facsimile machines, copiers and the like include FIGS.
As shown in FIG. 3, a paper loading table 3 holding a paper cassette 1 containing paper P and swingably supported about a shaft 2 as a fulcrum.
And a push-up lever 4 for urging the paper table 3 upward.
A drive gear 6 connected to a paper feed motor 5 for operating the push-up lever 4, and a transmission gear 8 meshed with the drive gear 6 and axially mounted on a shaft 7 of the push-up lever 4. Something was done.

[0005] A detection switch 9 for detecting that the paper P in the paper cassette 1 loaded on the paper mounting table 3 is pushed up to a predetermined position (paper feeding position) is provided above the paper mounting table 3. A paper feed roller 10 that rotates at a constant peripheral speed for feeding the pushed-up paper P one by one is provided. The leading edge of the pushed-up paper P (uppermost paper) is pressed against the paper feed roller 10 and
The paper is fed by rotating.

[0004] Incidentally, ordinary printers, facsimile machines,
In a copying machine or the like, the paper P fed by the paper feed roller 10 is sent to a nip portion between the paper feed roller 10 and a separating member 11 for preventing double feeding of the paper P,
Next, the sheet is guided by a pinch roller 12 and a guide roller 13 that rotate in contact with the paper feed roller 10,
It is sent to the printing unit 20.

In this example, the printing unit 20 is provided with a platen 21 for supporting the paper P and a print head 22 which can reciprocate in the longitudinal direction of the platen 21. The reciprocation of the print 22 causes printing on the surface of the paper P sent onto the platen 21. The printed sheet is discharged to a discharge tray 24 by a discharge roller 23.

The operation of the push-up lever 4 will be described with reference to FIG. As shown in FIG. 5A, when the paper feed motor 5 is driven based on a paper feed signal, the driving force is transmitted to a drive transmission mechanism including a drive gear 6, a transmission gear 8, a lever shaft 7, and the like. Via the push-up lever 4
Is rotated in the counterclockwise direction a, whereby the paper mounting table 3 is pushed up.

As shown in FIG. 5 (b), when the paper P loaded on the paper mounting table 3 to be pushed up comes to a paper feed position where it comes into contact with the paper feed roller 10, the detection switch 9 is turned on. The uppermost paper Pa loaded on the mounting table 3 is detected, the drive of the paper feeding motor 5 is stopped, the paper mounting table 3 is held at the paper feeding position, and the paper is fed by the paper feeding roller 10. . When the paper feed by the paper feed roller 10 is completed, the paper feed motor 5 rotates in the reverse direction, and the push-up lever 4 is rotated clockwise through the drive gear 6, the transmission gear 8 and the lever shaft 7, and Return the mounting table 1 to the initial position.

[0008]

However, when the detection switch 9 is normally operated, the sheet mounting table 3 is raised, and the uppermost sheet Pa comes to the sheet feeding position where it comes into contact with the sheet feeding roller 10. At this time, the uppermost paper Pa loaded on the paper mounting table 3 activates the detection switch 9 to stop the driving of the paper feeding motor 10 and hold the paper mounting table 3 at the paper feeding position. If the sheet 9 does not operate due to a failure or the like, as shown in FIG. 5C, even if the sheet (top sheet Pa) loaded on the sheet mounting table 3 comes to the sheet feeding position, the sheet feeding motor 5 continues to drive, thereby trying to rotate the push-up lever 4 further counterclockwise.

As a result, the paper P stacked on the paper mounting table 3 is pushed up to a position above the upper limit position L above the paper feeding position, breaking the detection switch 9 or overloading the push-up lever 4. There is a possibility that a problem such as breakage may occur. SUMMARY OF THE INVENTION The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to prevent damage to members attached to a sheet feeding device such as a detection switch 9 and a push-up lever 4 with a simple configuration. To provide a paper feeder.

[0010]

According to a first aspect of the present invention, there is provided a sheet feeding apparatus for holding a sheet to be stacked and swingably supported, and having the sheet mounting table disposed upward. A push-up member that urges the push-up member, a drive mechanism for operating the push-up member, a detecting unit that detects the paper pushed up by the push-up member and controls the drive of the drive mechanism, and is pushed up by the push-up member. In a sheet feeding device including a sheet feeding member for feeding sheets stacked on a sheet loading table one by one, the sheet loading table is moved to a preset upper limit position between the driving mechanism and the lifting member. A drive transmission mechanism is provided which releases the drive transmission from the drive mechanism to the push-up member when moved.

In the paper feeder according to the present invention, the push-up operation of the push-up member is stopped at a predetermined position because, for example, the detecting means which operates by the uppermost sheet of the paper pushed up by the push-up member does not operate properly. Even when the paper mounting table is to be further raised beyond the predetermined paper feeding position, the drive transmission mechanism operates at the time when the paper mounting table moves to the preset upper limit position, and The drive transmission to the push-up member is released. As a result, the upward movement of the sheet mounting table is stopped, and it is possible to prevent members such as the detection unit and the push-up member from being carelessly damaged.

The form of the push-up member and the manner in which the push-up member pushes up the sheet mounting table may be arbitrary, and there is no particular limitation as long as the sheet mounting table can be moved to a predetermined position by the pushing-up operation of the push-up member. However, the configuration in which the sheet mounting table is pushed up by the rotating lever as shown in FIGS. 3 to 5 is preferable from the viewpoint of the reliability of operation and the easiness of the mechanism.

[0013] The drive transmission mechanism may be any drive transmission mechanism that can be activated when the paper mounting table moves to a preset upper limit position, and release the drive transmission from the drive mechanism to the push-up member. Optionally, if the push-up member is in the form of a pivoting lever as described above, the drive gear coupled to the drive mechanism and the drive gear, such as a toothless gear or a sector gear, It is preferable that the push-up member is rotated within a predetermined angle range by meshing with the rotary member.

In the above aspect, by providing the rotating member for rotating the push-up member within a predetermined angle, the drive transmission from the drive mechanism to the push-up member is released when the push-up member rotates by the predetermined angle. Therefore, it is possible to prevent damage to members such as the detection means and the push-up member without using a complicated control mechanism.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the paper feeder according to the present invention will be described below with reference to the drawings. The paper feeding apparatus according to the present invention can be used as appropriate with any conventionally known image forming apparatus such as a printer, a facsimile, and a copying machine. The other configuration is the same as that shown in FIGS. 3 and 4 except that the drive transmission mechanism releases the drive transmission from the drive mechanism to the push-up member under certain conditions. May be. Accordingly, in the following description, the “drive transmission mechanism” will be mainly described, and members having the same functions as those of the other components will be denoted by the same reference numerals, and detailed description thereof will be omitted.

The sheet feeding device shown in FIGS.
4 and a push-up lever 4 as a push-up member for urging the sheet mounting table 1 supported swingably about a shaft 2 (not shown in FIGS. 1 and 2). A feed motor 5 as a drive mechanism for operating the push-up lever 4; a drive transmission mechanism for operating the push-up lever 4 by driving the feed motor 5; A detection switch (FIGS. 1 and 2) serving as a detection unit that detects the uppermost sheet Pa of the sheets P placed on the sheet table 3 pushed up by the sensor and controls the driving of the driving mechanism (sheet feeding motor 5). (Not shown) is provided. During the normal operation, the sheet feeding operation is the same as that shown in FIGS.

The drive of the paper feed motor 5 is transmitted to the drive transmission mechanism of the present invention via the drive transmission mechanism, the push-up lever 4 is operated, and the paper table 3
Is pushed up, and the uppermost sheet Pa of the sheets placed on the sheet placing table 3 is pushed up to the sheet feeding position in contact with the sheet feeding roller 10, but the detection switch 9 is operated due to some problem. Instead, the push-up lever 4 is operated more than necessary, and a mechanism is provided that does not damage members such as the detection switch 9 and the push-up lever 4 of the sheet feeding device.

That is, as shown in FIG. 1 and FIG. 2, the drive transmission mechanism includes a drive gear 6 mounted on the shaft of the paper feed motor 5, meshed with the drive gear 6, and a predetermined gear. The rotation allowable angle α is set, and the push-up lever 4 is
And a rotating member 81 (in the illustrated example, a missing tooth gear) that is mounted on the shaft 7.

The toothless gear 81 in which the rotation allowable angle α is set has teeth 82 corresponding to a predetermined rotation allowable angle α formed on the outer periphery thereof. When the drive gear 6 rotates, the toothless gear 81 meshes with the teeth of the drive gear 6,
When the toothless portion 83 of the toothless gear 81 comes to a position corresponding to the drive gear 6, the rotation of the drive gear 6 is stopped by the rotation of the pushup lever 4 because the toothless gear 81 does not rotate. It is no longer transmitted to the shaft 7.

The rotation allowable angle α is determined by detecting the sheet P stored in the sheet table 3 to which the sheet table 3 is pushed up from the initial position, and normally, the detection switch 9 is pushed up. Is set within a range up to a position (upper limit position L) above which the member constituting the sheet feeding device is broken up from the position where the operation of is canceled (see FIG. 1C).

Accordingly, as shown in FIG. 1A, when the driving gear 6 is rotated by the driving of the paper feed motor 5 by the paper feed signal from the state where the paper mounting table 3 is placed at the initial position. The meshing of the drive gear 6 with the teeth 82 of the toothless gear 81 causes the toothless gear 81 to rotate, thereby rotating the lever shaft 7 and rotating the push-up lever 4 in the counterclockwise direction a. As a result, the leading end portion 4a of the push-up lever pushes up the paper table 3.

When the paper table 3 is pushed up, the loaded paper P is fed to a paper feed roller 10 (FIG. 3).
1), and if the detection switch 9 is normal, the missing gear 81 shown in FIG.
The uppermost sheet Pa loaded on the sheet placing table 3 is pushed up to a predetermined position (sheet feeding position) within the rotation allowable angle α corresponding to the tooth portion of, and the detection switch 9 is operated. Stop the paper feed motor 5,
By catching the actuator of the switch,
When the detection switch 9 is not operated, FIG.
As shown in FIG. 7, when the toothless portion 83 of the toothless gear 81 comes to a position where the toothless gear 83 meshes with the drive gear 6, the drive of the drive gear 6 can be transmitted by the toothless portion 83 of the toothless gear 81. Therefore, the paper table 3 is not pushed up any more, and stops in the state shown in FIG. 1C. Therefore, it is possible to prevent breakage of members constituting the sheet feeding device.

In order to release the stopped state of the paper placing table 3, the motor 5 is rotated in the reverse direction, so that the toothless gear 81 rotates clockwise by its own weight, meshes with the driving gear 6, and rotates. By rotating the lever shaft 7 in the reverse direction, it is possible to return the push-up lever 4, the sheet mounting table 3 and the like to the initial state. Although not shown, as the rotating member for rotating the permissible angle, not only the toothless gear but also a sector gear, a rack, or the like can be used.

[0024]

As described above, according to the present invention, the detection switch 9 is operated even when the paper mounting table 3 is pushed up and the paper P stacked on the paper mounting table 3 reaches a predetermined paper feeding position. Even if the drive mechanism for pushing up the paper table 3 is not stopped without stopping, a predetermined position (upper limit position) determined in advance.
, The drive of the drive mechanism is not transmitted to the push-up lever 4, so that damage to the members of the sheet feeding device can be prevented.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining an operation of a drive transmission mechanism of a sheet feeding device according to the present invention.

FIG. 2 is a plan view illustrating a drive transmission mechanism of the sheet feeding device according to the present invention.

FIG. 3 is a diagram illustrating an example of a conventional sheet feeding device.

FIG. 4 is a plan view illustrating an example of a conventional sheet feeding device.

FIG. 5 is a view for explaining the operation of a drive transmission mechanism of a conventional sheet feeding device.

[Explanation of symbols]

P: paper, 1: paper cassette, 3: paper mounting table, 4: push-up lever, 5: paper feed motor as drive mechanism,
6: drive gear, 7: shaft of the push-up lever 4, 81: toothless gear, 82: tooth part, 83: toothless part, α: rotation allowable angle corresponding to tooth part of the toothless gear

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hideki Goto 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka F-term (reference) 3F343 FA02 FB02 FB03 FB04 FC27 GA03 GB01 GC01 GD02 HA12 HA33 HA34 HD07 HD10 HD18 KB03 KB20 LA15 LC12 LC22 LC25 MA03 MA09 MA24 MA32 MA58 MB04 MB13 MC17 MC19 MC27

Claims (4)

[Claims] A sheet mounting table that holds the sheets to be stacked and is swingably supported, a push-up member for urging the sheet mounting table upward, a drive mechanism for operating the push-up member, Detecting means for detecting the paper pushed up by the push-up member and controlling the drive of the drive mechanism; and a paper feed member for feeding the sheets stacked on the paper mounting table pushed up by the push-up member one by one In the sheet feeding device, the drive transmission from the drive mechanism to the push-up member is released when the sheet mounting table moves to a preset upper limit position between the drive mechanism and the push-up member. A sheet feeding device provided with a drive transmission mechanism. 2. The push-up member is a rotating lever,
The sheet mounting table is pushed up by the rotation of the lever, and when the lever rotates a predetermined angle, the transmission of the drive from the drive mechanism to the push-up member is released. The paper feeding device according to claim 1. 3. The drive transmission mechanism includes: a drive gear connected to the drive mechanism; and a rotation member that meshes with the drive gear and rotates the push-up member within a predetermined angle. The sheet feeding device according to claim 2, wherein 4. The sheet feeding device according to claim 3, wherein the rotating member is formed of a toothless gear or a sector gear.