JPH0784267B2 - Paper feeder - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding device, and more particularly to a sheet feeding device configured to sequentially feed monosheets from a sheet feeding cassette to a platen from a sheet feeding roller.

[Prior Art] FIG. 4 shows a conventional sheet feeding device of this type. Here, 1 is a paper feed cassette in which the single sheets (cut sheets) 2 are held in an accumulated state, 3 is the sheet receiver thereof, and 4 is the cut sheet 2 accumulated on the sheet receiver 3 in a separating claw 5. It is a spring that is biased toward. 6 is a paper feed roller provided on the paper feed cassette 1, 7 is a platen for holding the cut sheet 2A fed from the paper feed cassette 1 in a wound state for recording, 8 is a paper guide, and 9 is a paper guide. Is a pinch roller which is provided at a position related to the paper guide 8 and holds the cut sheet 2A fed by being pressed against the platen 7 and cooperates with the sheet feeding.

In the sheet feeding device thus configured, when the sheet feeding roller 6 starts to rotate in the direction indicated by the arrow A in FIG. Only as shown in FIG. 5B, they are separated and delivered toward the platen 7 as shown in FIG.

By the way, when the cut sheet 2 is stored in the sheet feeding cassette 1, a gap or play between the cut sheet 2 and the sheet feeding cassette 1, or a separation claw 5 provided at the left and right front ends of the sheet feeding cassette 1 is used. The timing difference between the left and right when 2A is separated, and further, when there are a plurality of paper feed rollers 6 arranged side by side, there are variations in torque between the individual paper feed rollers, and so on. There arises a problem that the cut sheet 2A delivered at the time of paper operation is obliquely fed to the platen 7 or is not fed to a predetermined position.

Therefore, conventionally, in order to deal with the above problem, the platen 7 is stopped until the cut sheet 2A is nipped between the platen 7 and the pinch roller 9 by the paper feed roller 6, as shown in FIG. 5C. The cut sheet 2A is formed into a loop by keeping it in this state, and then the platen 7 is driven, or the platen 7 is specially rotated in the opposite direction to the sheet feeding direction to change the posture of the cut sheet 2A. I was fixing it.

[Problems to be Solved by the Invention] However, in the method of correcting the skewed posture of the cut sheet as described above, a drive system for driving the platen and a drive system for driving the paper feed roller are separately provided, or appropriate. Since it is necessary to provide a control means for driving each of them at various timings, the mechanism becomes complicated and the cost increases. Also, rotating the platen in the reverse direction
The platen knob will also rotate in the opposite direction, giving the user a strange feeling.

Furthermore, as shown in FIG. 5C, in order to form a loop until the trailing end of the cut sheet 2A sent out is kept in contact with the platen 7 and the rear end thereof is separated from the paper feed roller 6. , The loop becomes quite large, and not only wasted time is consumed until the loop is formed,
A loop forming space is required, which causes a wasteful space in the device, which hinders downsizing of the device.

Further, when the platen and the paper feed roller are operated by the same drive source and the rotation directions thereof are the same, the leading end is caught in the platen before the cut sheets delivered from the paper feed cassette are completely delivered. There is no room for skew correction because there is no gap between loops to be formed.
Therefore, in such a printer, a gate-like member is arranged in the feed path of the cut sheet from the paper feed cassette, the loop is formed by this gate, and the opening / closing operation of the gate is controlled by the electric control means. I was trying to do it.

However, if the gate-shaped member is opened and closed by such a control means, a switch means is required to turn on / off the drive means for that purpose, and the structure becomes complicated, leading to an increase in cost and for general customers. Not desirable.

In view of the above-mentioned conventional problems, an object of the present invention is to provide a sheet feeding device capable of preventing skew of a cut sheet with a simple mechanical mechanism.

[Means for Solving the Problems] A sheet feeding device of the present invention that can achieve the above object is a separation device that is provided in a sheet feeding cassette and presses both front end corners of a cut sheet stored in the sheet feeding cassette. A pawl, a paper feed roller for feeding one of the cut sheets in the paper feed cassette separated by the separation pawl between a platen and a pinch roller, and one end of the paper feed cassette is rotatable. A loop-forming member pivotally attached to the loop-forming member, a blocking portion formed at the other end of the loop-forming member and brought into contact with the two corners of the leading edge of the cut sheet fed from the paper feed cassette, The blocking portion is interlocked with a paper roller to close a paper feeding path of the cut sheet extending from the paper feeding cassette to the platen and the pinch roller, and a position retracted from the paper feeding path. Loop formation A loop forming member driving means for rotating the member is provided.

Here, the loop forming member driving means is provided coaxially with the paper feeding roller and a spring that biases the loop forming member so that the blocking portion blocks the paper feeding path, and the spring of the spring is provided. It is possible to employ one having a cam member that rotates the loop forming member at a position where the blocking unit retracts from the paper feeding path against the force.

[Operation] According to the present invention, the top cut sheet in the paper feed cassette forms a loop by the separating claws as the paper feed roller rotates, and only one sheet is ejected from the paper feed cassette. Both corners of the tip end contact the blocking portion of the loop forming member that blocks the path. In this state, the paper feed roller continues to rotate, so that the leading edge of the cut sheet starts to form a loop again,
When the paper feed roller reaches a predetermined rotation, the loop forming member drive means retracts the blocking portion from the paper feed path, whereby the leading edge of the cut sheet is accurately fed between the platen and the pinch roller.

Further, when the one having the spring and the cam member is adopted as the loop forming member driving means, the spring urges the loop forming member so that the blocking portion closes the paper feeding path, and the cam member acts as the paper feeding roller. When the predetermined rotation is reached, the loop forming member is rotated to the position where the blocking portion retracts from the sheet feeding path against the spring force of the spring.

Embodiments Embodiments of the present invention will be described in detail and specifically below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, in which 11 operates to block the front end portion of a temporary cut sheet in order to form a loop on a cut sheet (not shown) fed from the paper feed cassette 1. It is a loop forming member, and 11A is a blocking portion provided at its tip. The arm 11B of the member 11 is rotatably attached around a pin 12 provided on the side surface of the paper feed cassette 1, while the roller shaft 14 of the paper feed roller 13 is provided with a cam member 15. There is. 16 is a loop forming member 11
Is a spring that biases the arm portion 11B of the cam member 15 toward the cam member 15, and in the present embodiment, the cam member 15 and the spring 16 are
The loop forming member driving means of the present invention is constituted by the above.

In the case of this example, the paper feed roller 13 has a half-moon cam shape including a circumferential portion 13A and a cutout portion 13B.

Now, the sheet feeding operation in the sheet feeding device configured as described above will be described with reference to FIGS. 2A to 2D and FIG. 3 showing the timing.

It should be noted that in FIG. 3, the paper feed roller is shown for the sake of clarity.
The postures and the states of the loop forming member 13 and the loop 13 during operation are shown in two levels as shown in the drawing, and their changes are shown as rising and falling. In this example, only one cut sheet 2A is delivered from the paper feed cassette 1 during the period in which the circumference 13A of the paper feed roller 13 keeps contacting the cut sheet 2A while the paper feed roller 13 makes one rotation.

That is, in FIG. 3, the time as shown in (A) T ₁
Then, the paper feed roller 13 starts to rotate according to the paper feed command, and at time T ₂ , the circumferential portion 13A of the paper feed roller 13 comes into contact with the upper surface of the cut sheet 2 (see FIG. 2A). Only one cut sheet 2A positioned at the top of the accumulated cut sheets 2 is separated from the locking claws 5 and fed, but in this state, as shown in (C). The loop forming member 11 is kept in a state of closing the sheet feeding passage, and therefore the cut sheet 2A to be fed out is shown in FIG. 2B after its leading end abuts against the loop forming member blocking portion 11A. So that a loop is formed.

Therefore, at the time T ₃ when the loop is formed in this way, the loop forming member 11 is then pushed down by the cam member 15 to open the paper feed path and the tip of the cut sheet 2A curved in a loop shape. Is extended and guided between the platen 7 and the pinch roller 9 in the state shown in FIG. 2C. Thus, the tip end portion can be properly held between the platen 7 and the pinch roller 9 by the restoring force of the bent cut sheet 2A.

After this, after the subsequent paper feeding operation by the paper feeding roller 13,
At time T ₅ , the cutout portion 13B of the paper feed roller 13 rotates toward the paper feed cassette 11 to separate the paper feed roller 13 from the cut sheet surface. At that time, the platen 7 starts sheet feeding. As shown in FIG. 2D, the cut sheet 2A has no relation to the rotation of the paper feed roller 13 and the platen 7
Will be wound around. Thus, at time T ₆ , the paper feed roller 13 becomes 1
The paper feed roller 13 is stopped when it rotates.

In the above description, the loop forming member is operated by the cam member provided coaxially with the sheet feeding roller.
The means for operating the loop forming member may have any structure as long as it is a mechanical mechanism that works in conjunction with the paper feed roller. Further, in the above example, the loop forming member is operated in the vertical direction, but it is not limited to the vertical direction, and it is of course possible to operate the loop forming member in the horizontal direction to open and close the paper feed path. is there.

[Effects of the Invention] As described above, according to the present invention, the paper feed path from the paper feed cassette to the platen is opened and closed by the member interlocking with the paper feed roller, and the paper feed is performed. Since the tip of the cut sheet fed to the sheet feeding path by the roller is blocked by the roller interlocking member to form a loop, the loop is opened and guided between the platen and the pinch roller. By forming the loop with a simple mechanical structure, it is possible to prevent the cut sheet from skewing, and it is possible to provide a sheet feeding device suitable for a small printer.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of the configuration of the paper feeding device of the present invention, FIGS. 2A to 2D are explanatory views showing the steps of the paper feeding operation step by step, and FIG. FIG. 4 is a timing chart, FIG. 4 is a configuration diagram showing an example of a conventional sheet feeding device, and FIGS. 5A to 5C are explanatory diagrams showing stepwise the steps of the sheet feeding operation. 2,2A: Cut sheet, 5: Separation claw, 7: Platen, 9: Pinch roller, 11: Loop forming member (roller interlocking member), 11A: Blocking part, 11B: Arm part, 12 …… pin, 13 …… feed roller, 13A …… circumferential part, 13B …… notch part, 15 …… cam member.

Claims (2)

[Claims] 1. A separation claw that is provided in a paper feed cassette and presses both corners of the leading edge of a cut sheet stored in the paper feed cassette, and a separation claw that is separated by the separation claw A sheet feeding roller that feeds the cassette sheet between a platen and a pinch roller, a loop forming member whose one end is pivotally attached to the sheet feeding cassette, and the other end of the loop forming member. A blocking portion that is formed and sent out from the inside of the paper feeding cassette and abuts against both corners of the leading edge of the cut sheet; and the blocking portion is interlocked with the paper feeding roller and extends from the paper feeding cassette to the platen. A loop forming member driving means for rotating the loop forming member at a position for closing the paper feed path of the cut sheet reaching the pinch roller and a position for retracting from the paper feed path. Sheet feeder for the butterflies. 2. The loop forming member drive means is provided coaxially with the paper feed roller, and a spring for urging the member in a loop shape so that the blocking portion closes the paper feed path. The cam member for rotating the loop forming member at a position where the blocking portion is retracted from the paper feeding path against the spring force of a spring, The cam member according to claim 1, Paper feeder described in.