JPH0743070Y2 - Paper feeder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a sheet feeding device of an image recording apparatus using an electrophotographic process.

(Prior Art) In an image recording apparatus such as an electrophotographic copying machine or a printer that records an image using an electrophotographic process, an electrostatic latent image formed on a rotating photosensitive drum is developed and then transferred to a recording sheet. At this time, the recording paper pulled out from the cassette is temporarily stopped and put in standby so that the leading edge of the recording paper matches the leading edge of the visible image formed on the photosensitive drum, and the recording paper is synchronized with the rotation of the photosensitive drum. Then, the sheet is re-fed toward the transfer position at a predetermined timing.

In a conventional image recording apparatus, a pair of rollers called a registration roller and a shutter are used to temporarily hold the recording paper before the transfer position in this way.
The registration roller is normally stopped, and the leading edge of the recording paper is abutted against this roller to make it stand by, and is rotated by a re-feed command to send the recording paper forward. On the other hand, the shutter moves in and out of the recording paper conveyance path, and when the shutter is in the conveyance path, the leading edge of the recording paper abuts against the shutter and is stopped.When the shutter retracts, the recording paper moves forward by the paper feed roller. Sent out. A solenoid is used to move the shutter in and out.

On the other hand, as shown in FIG. 1, the recording sheets are fed one by one from the cassette 11 that stores a large number of sheets in synchronization with the recording operation. A roller 5 having a semi-lunar outer shape is used so that only the paper is fed, once pulled out of the cassette 1 and fed to a certain extent, and then separated from the recording paper to be free. The drive mechanism for the half-moon shaped roller 5 is shown in FIG.

There is a power transmission gear 3 that constantly rotates, and a tooth-missing gear 4 that can be meshed with the power-transmitting gear 3. A cam 9 and a half-moon roller 5 are integrally coupled to the tooth-missing gear 4 coaxially. The cam 9 is urged by the spring 6 to rotate in one direction (clockwise direction). An L-shaped actuator 7a of a solenoid 7 is biased by a spring 8 and coupled to the step portion 5a of the cam 5.

The solenoid 7 is energized by the paper feed signal and its actuator
When the tip of 7a comes off the stepped portion 5a of the cam 5, the cam 5 is rotated in the direction of the arrow by the action of the spring 6. As a result, the missing tooth gear 4
Part of the teeth of the gear meshes with the power transmission gear 3, and the partly tooth-missing gear 4 continues to rotate in the same direction. Since the half-moon roller 5 is fixed coaxially with the tooth-missing gear 4, the half-moon roller 5 also rotates, and when the tooth-missing portion 4a of the tooth-missing gear 4 eventually comes to a position facing the power transmission gear 3, both gears are rotated. , The tooth-missing gear 4 stops, and the half-moon roller 5 also stops. At this time, the solenoid 7 is de-energized, so that the actuator 7a has the spring 8
Then, the cam 5 is rotated clockwise, and its tip projects into the passage of the step 5a of the cam 5, so that the step 5a and the tip of the actuator 7a are engaged with each other to stop the rotation of the cam 5.

By the way, in the conventional image recording apparatus, since the solenoid for opening and closing the shutter and the solenoid for driving the half-moon roller for feeding are separate, each requires a mounting space, which is troublesome for mounting. However, there is a problem that the cost is high.

(Object and Structure of the Invention) The present invention has been made in view of the above points. By using the shutter driving solenoid and the half-moon roller driving solenoid in common, the installation space is reduced and the cost is reduced. In order to achieve this purpose, a toothless gear that is always urged to rotate in one direction is provided at a position where it can mesh with the power transmission gear, and the half moon for feeding is coaxial with the toothless gear. A roller that fixes the roller-shaped roller and is rotated by an electromagnetically driven drive source to take two positions, and a shutter that opens and closes the passage of the recording paper by an elevating member provided in a part of this lever. When the lever is in the first position, the one-sided rotation bias of the toothless gear is blocked, the toothless gear and the power transmission gear are not meshed, and the shutter is opened, and the lever is in the second position. When The tooth-missing gear is urged to rotate in one direction, meshes with the power transmission gear, makes almost one rotation, and then prevents rotation, and the shutter is closed.

(Embodiment) The present invention will be described below with reference to the drawings.

FIG. 1 shows a main part of a sheet feeding device of an image recording apparatus according to the present invention. In the figure, 1 is a photosensitive drum which forms an electrostatic latent image, 2 is a transfer pole, and 10 is a separation pole. A strip electrode, a developing device, a cleaning device and the like which are necessary for a normal electrophotographic process are omitted.

Reference numeral 11 denotes a cassette that stores a large number of recording papers P. A half-moon roller 5 that sends out the uppermost recording paper is provided above the cassette 11, and a first paper feeding roller is provided along a paper feeding path of the recording paper. 12, a second paper feed roller 13, and a shutter 14 immediately downstream of the second paper feed roller 13 for stopping the recording paper and making it stand by. A paper feed sensor 15 is located immediately upstream of the second paper feed roller 13 and detects the presence or absence of recording paper.

When the half-moon roller 5 rotates in synchronism with the operation of the recording paper, the topmost recording paper P stored in the cassette 11 is sent out, and when the leading end of the recording paper P reaches the first paper feed roller 12, this time It is conveyed by the first paper feed roller 12. When the front end of the recording paper hits the second paper feed roller 13 and the front end hits the shutter 14, it stops and enters the standby state. After that, the shutter 14 is moved downward at a timing such that the front end of the recording paper coincides with the front end of the visible image formed on the photosensitive drum 1, the conveyance path is opened, and the recording paper is fed to the transfer section. .

The structure of the shutter and the half-moon roller will be described with reference to FIG.

In FIG. 2, reference numeral 5 denotes a pair of half-moon shaped rollers which are attached to the central portion of the shaft 16 with a space therebetween.
Is provided so as to come to the position shown in FIG. At one end of the shaft 16, a toothless gear 4 having a toothless toothless portion 4a formed on a part of its circumference and a disc 17 are attached, and a surface of the disc 17 that is not in contact with the toothless gear 4 Two protrusions 17a, 17b and one pin 17c are provided at a certain interval. A coil spring 18 is hung between the pin 17c and a part of the device. The power transmission gear 3 is used for the toothless gear 4.
It is arranged at a position where it can be meshed with.

On the other hand, a solenoid 19 is provided, and its actuator 19a
One end of a lever 21 which is rotatable around the shaft 20 as a fulcrum is loosely attached to the. The other end of the lever 21 is bent, and the bent portion 21a comes into contact with the protrusion 17a or 17b of the disc 17. An elevating round bar 22 extends horizontally from the center of the lever 21, and the round bar 22 is in light contact with the lower bent portion of the rising piece 14a of the shutter 14. In addition,
The shutter 14 is rotatably supported by a shaft 23 and is always urged upward by a spring 24.

Next, the movements of the shutter 20 and the half-moon roller 10 will be described with reference to FIG.

When the solenoid 19 is not energized, its actuator 19
Since a projects upward, the lever 21 is in a position rotated clockwise (indicated by an arrow A in FIG. 2) about the shaft 20 as a fulcrum. The round bar 22 for raising and lowering is in contact with the protrusion 17b and is in a position where it is pushed down. Therefore, the disk 17 cannot be rotated by the coil spring 18 even if a counterclockwise rotational force is applied thereto, and the shutter 14 is rotated clockwise (indicated by an arrow C in FIG. 2) about the shaft 23 as a fulcrum. In position. As a result, shutter 14
As shown in FIG. 3A, the rising piece 14a of FIG. 3 descends below the passage of the recording paper, and the passage is open. At this time,
Even if the power transmission gear 3 rotates, the tooth-missing gear 4 does not rotate because its meshing portion faces the tooth-missing portion 4a of the tooth-missing gear 4, and therefore the recording paper P is not fed from the cassette 11. .

When the solenoid 19 is energized, the actuator 19a retracts and the lever 21 rotates counterclockwise (indicated by arrow B in FIG. 2), as shown in FIG. The bent portion 21a at the tip is disengaged upward from the projection 17b of the disc 17 and the elevating round bar 22 is raised. As a result, the circular plate 17 is counterclockwise by the tensile force of the coil spring 18 (indicated by arrow E in FIG. 2).
When turned to, the power transmission gear 3 meshes with the tooth portion of the tooth-chipped gear 4, and the rotational force from the power transmission gear 3 is transmitted to the tooth-chipped gear 4. In this way, the half-moon roller 5 rotates in the direction of the arrow and the uppermost recording sheet in the cassette 11 is pulled out.

On the other hand, since the elevating round bar 24 is also moved upward, the shutter 14 is rotated clockwise (indicated by an arrow D in FIG. 2) by the spring 24 about the shaft 23 as a fulcrum, and the rising piece 14a thereof is a recording paper. It comes to the position to close the route.

In this state, the recording paper is conveyed by the first paper feed roller 12 (see FIG. 1) and the second paper feed roller 13 and its leading end projects into the rising piece 14a of the shutter 14 as shown in FIG. It hits and stops, and enters the standby state. Further, the partly tooth-missing gear 4 continues to be rotated by the power transmission gear 3, and stops when the protrusion 17a of the disk 17 comes into contact with the tip bending portion 21a of the lever 21. As a result, the half-moon roller 5 also stops and returns to the original state. However, the leading edge of the recording paper is detected by the paper feed sensor 15 prior to this, and a predetermined time (for example, 2 seconds) has elapsed after the detection.
When the passage of time elapses, the solenoid 19 is de-energized.
As described above with reference to FIG.
3 in that the bent portion 21a at the tip thereof comes into contact with the protrusion 17a of the disc 17 and the round bar 22 is lowered to rotate the shutter 14 in the arrow C direction. The rising piece 14a is pulled in from the passage of the recording paper as shown in FIG.
At this time, since the second paper feed roller 13 is rotating, the recording paper waiting up to that point is re-fed toward the transfer position. The above is one cycle of the sheet feeding operation until one recording sheet is supplied from the cassette 4 to the transfer position.

After that, the sheet feeding signal output in synchronization with the recording operation is waited for, and the same sheet feeding operation is repeated by the output of the sheet feeding signal.

(Effects of the Invention) As described above, in the present invention, the toothless gear that is constantly urged to rotate in one direction is provided at a position where it can mesh with the power transmission gear, and the paper is fed coaxially with the toothless gear. A half-moon roller for use is fixed, and a lever that is rotated by an electromagnetically biased drive source to take two positions is provided, and an elevating member provided at a part of this lever opens and closes the path of the recording paper. A shutter is provided to prevent unidirectional rotation of the tooth-chipped gear when the lever is in the first position and to prevent the tooth-chipped gear from meshing with the power transmission gear.
When the position is set to, the tooth-chipped gear is urged to rotate in one direction and meshes with the power transmission gear to rotate for about one rotation, and then the rotation is blocked, and the shutter is closed. Both the shutter and the half-moon roller can be driven in synchronism by a driving source, that is, a solenoid. Therefore, the installation space can be significantly reduced compared to the conventional case in which the shutter and the solenoid for driving the half-moon roller are separately provided, and the cost can be reduced in combination with the reduction in the number of parts.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a paper feeding unit of an image recording apparatus, and FIG. 2 is a perspective view of an embodiment of a shutter / half-moon roller driving mechanism of a paper feeding apparatus for an image recording apparatus according to the present invention. I),
(B), (c) and (d) are diagrams showing the operation of the drive mechanism shown in FIG. 2 in stages, and FIG. 4 is a schematic diagram showing a conventional half-moon roller drive mechanism. 1 ... Photosensitive drum, 3 ... Power transmission gear, 4 ... Missing gear, 5 ... Half moon roller, 11 ... Cassette, 12 ... First paper feed roller, 13 ... Second paper feed roller , 14 …… Shutter, 17 …… Disc, 19 …… Solenoid, 21 …… Lever

Claims (1)

[Scope of utility model registration request] Claim: What is claimed is: 1. A power transmission gear, a toothless gear which is provided at a position where it can mesh with the power transmission gear and is biased so as to always rotate in one direction, and is fixed coaxially with the toothless gear. Recording by a fed sheet-shaped half-moon roller, a drive source that is electromagnetically biased, a lever that is rotated by the drive source to assume two positions, and an elevating member provided in a part of the lever A shutter for opening and closing a paper path, and when the lever is in the first position, the one-way rotation bias of the tooth-chipped gear is blocked, and the tooth-chipped gear and the power transmission gear mesh with each other. If the shutter is opened and the lever is in the second position, the tooth-chipped gear is urged to rotate in one direction. Also, the shutter is configured to be closed. Sheet feeder that.