JPH10129895A - Paper feeder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make paper feeding operations including a paper skewing preventive motion so as to be done by one motor alone in a positive manner. SOLUTION: After a tip of paper has slightly passed through between two narrowly pressed parts of a conveyor-roller pair, a paper feed roller 10 is stopped once while these paired conveyor rollers are rotated in reverse, whereby the paper tip is made to go along the narrowly pressed parts of these paired conveyor rollers, preventing any paper skewing from occurring in this way. Subsequently a brake pad 30 is forcibly made contact with a drum 20 clamped tight to the end of a paper feed roller shaft 11. This drum is one to detect a position of the paper feed roller 10, therefore a hole 22 to be detected by a detector 60 is bored in the peripheral wall 21. In this connection the brake pad 30 is larger tan this hole 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feeder used for a printer, a facsimile, a copying machine, and the like. More specifically, the paper feed roller includes a paper feed roller that feeds the paper in contact with the paper, and a transport roller pair that nips and transports the paper fed by the paper feed roller. After a short passage, the paper feed roller is temporarily stopped and the transport roller pair is reversed, so that the leading edge of the paper follows the nip portion of the transport roller pair to prevent skew of the paper and feed the paper. It concerns the device.

[0002]

2. Description of the Related Art FIG. 3 shows the basic structure and operation of a conventional sheet feeding apparatus.

In FIG. 1, reference numeral 1 denotes a paper feed roller, which is fixed to a paper feed roller shaft 2.

[0004] Reference numerals 3 and 4 denote conveying roller pairs. One roller 3 is a driving roller, and the other roller 4 is a driven roller that is pressed against and driven by the driving roller 3.

[0005] The paper feeding operation is as follows.

(A) In the standby state, as shown in FIG. 1 (a), both the sheet feeding roller 1 and the conveying roller pairs 3 and 4 are stopped.

(B) When a paper feed command signal is output from a control unit (not shown), the paper feed roller 1 and the transport roller pairs 3 and 4 rotate in the paper feed direction (forward rotation) as shown in FIG. ).

At this time, the paper P is urged toward the paper feed roller 1 by a hopper (not shown). Therefore,
The sheet P comes into contact with the sheet feeding roller 1 and is fed toward the conveying roller pairs 3 and 4.

(C) As shown in FIG. 1C, when the leading end P1 of the sheet P slightly passes through the pressing portions (contact portions between the two rollers) of the conveying roller pairs 3 and 4, the sheet feeding roller 1 and the conveying roller pairs 3 and 4 temporarily stop.

(D) As shown in FIG. 1D, while the paper feed roller 1 is in a stopped state, the transport roller pair 3, 4
Is reversed. As a result, the leading end P1 of the sheet is pushed back to a position short of the pressing portion of the pair of transport rollers 3 and 4 (until the sheet passes through the pressing portion in reverse). At this time, since the paper feed roller 1 is still stopped, the paper is slackened P2, and the leading edge P1 of the paper is pressed against the pressing portion of the pair of transport rollers 3 and 4 by the restoring force, and the paper is sent obliquely. If so, this will be corrected. That is, the leading edge P1 of the sheet is along the pressing portion of the pair of conveying rollers 3 and 4, and the skew of the sheet is prevented.

(E) As shown in FIG. 1 (e), the sheet feeding roller 1 and the conveying roller pairs 3 and 4 rotate forward again to feed the sheet.

The paper feed roller 1 is stopped after being rotated just one rotation by the operation of a one-rotation clutch or the like (not shown), and the transport roller pairs 3 and 4 continue to rotate as necessary to transport the paper.

[0013]

In the above-described paper feeder, there is a demand that the above-described operation be performed by one motor in order to reduce the size and cost.

In order to meet such a demand, a power transmission path by a gear train or the like from one motor is connected to the feed roller 1.
2 of the path toward the transport rollers and the path toward the transport roller pairs 3 and 4
And a switching gear is provided at a branch point between these two paths.

In the above-mentioned operations (a) to (c) and (e), the switching gear is positioned so that power is transmitted to the two paths. Power is transmitted to the route toward 3,4,
By arranging the switching gear so that power is not transmitted to the path toward the paper feed roller 1, the above-mentioned (a)
It is considered that the operations (1) to (e) can be performed by one motor.

However, when the above operation (d) is performed by such a configuration, the power transmission path to the paper feeding roller 1 is cut off, that is, the power transmission path to the paper feeding roller 1 is In this case, the switching gears are not engaged with each other, so that the paper feed roller 1 is in a free state. For this reason, when the pair of conveyance rollers 3 and 4 rotate in the reverse direction and the paper is pushed back, the paper feed roller 1 rotates in the same direction (reverse rotation).
The slack P2 is not formed on the sheet, and as a result, a situation may occur in which the skew of the sheet is not corrected.

That is, with the above configuration alone, (a) to
It is difficult to perform the operation of (e), particularly the operation of (d) with one motor.

An object of the present invention is to solve the above-mentioned problems and to provide a sheet feeding device capable of reliably performing the operations (a) to (e) with one motor.

[0019]

According to a first aspect of the present invention, there is provided a sheet feeding apparatus which is fixed to a sheet feeding roller shaft, rotates together with the sheet feeding roller shaft, and feeds the sheet in contact with the sheet. A sheet feed roller that feeds the sheet, and a pair of sheet feed rollers that pinch and feed the sheet fed by the sheet feed roller. After the leading end of the sheet slightly passes through the pinching portion of the sheet feed roller pair, the sheet is fed. A paper feeder for temporarily stopping a paper roller and reversing a pair of transport rollers to prevent the skew of the paper by causing the leading edge of the paper to follow a squeezing portion of the pair of transport rollers, wherein It is characterized by comprising a drum fixed to an end and a brake pad pressed against the drum.

According to a second aspect of the present invention, in the sheet feeding apparatus of the first aspect, the drum is a drum for detecting a position of a sheet feeding roller.

According to a third aspect of the present invention, there is provided the paper feeding apparatus according to the second aspect, wherein a hole to be detected by a detector is formed in a peripheral wall of the drum, and the brake pad is located closer to the hole than the hole. Is large.

[0022]

According to a first aspect of the present invention, there is provided a sheet feeding device which is fixed to a sheet feeding roller shaft, rotates together with the sheet feeding roller shaft, and feeds the sheet in contact with the sheet. A pair of transport rollers for nipping and transporting the fed paper, and after the leading edge of the paper slightly passes through the nipping portion of the transport roller pair, temporarily stop the paper feed roller and reverse the transport roller pair A sheet feeding device that prevents the sheet from skewing by causing the leading end of the sheet to follow the pressing portion of the pair of conveying rollers, and a drum fixed to an end of the sheet feeding roller shaft;
And a brake pad that is pressed against the drum. Therefore, even when the power transmission path to the feed roller is cut off when the pair of transport rollers is rotated in reverse, the end of the feed roller shaft When the brake pad is pressed against the drum fixed to the section, a rotational load is applied to the paper feed roller.

Therefore, when the sheet is pushed back by the reverse rotation of the transport roller pair, the paper feed rollers do not rotate together, and as a result, the leading end of the sheet is moved along the pressing portion of the transport roller pair. Skew is prevented.

That is, according to the sheet feeding device of the first aspect, the operations (a) to (e) described above can be reliably performed by one motor.

According to a second aspect of the present invention, in the first aspect of the present invention, the drum is a drum for detecting the position of a sheet feeding roller, and therefore a separate brake pad is pressed against the drum. It is not necessary to provide such a drum, and as a result, the number of parts can be reduced and the size of the apparatus can be reduced.

More specifically, some sheet feeders have a detection drum provided at an end of a sheet feed roller shaft in order to detect the position of the sheet feed roller.

According to the paper feeder of the second aspect, since the brake pad is pressed against the detection drum, there is no need to separately provide a drum for pressing the brake pad. The number of points can be reduced and the size of the apparatus can be reduced.

Further, when the power transmission path to the paper feed roller is cut off, the paper feed roller is prevented from rotating unnecessarily for some reason (for example, vibration), and the position detection accuracy of the paper feed roller is degraded. Can be prevented.

According to the sheet feeding device of the third aspect, in the sheet feeding device of the second aspect, a hole to be detected by a detector is formed in a peripheral wall of the drum, and the hole is more than the hole. Since the brake pad is large, smooth rotation of the paper feed roller can be obtained.

More specifically, in some paper feeders, a hole is formed in the peripheral wall of the drum for detecting the position of the paper feed roller, and this hole is detected by an appropriate detector. In such a configuration, if the brake pad is smaller than the hole, the brake pad may be caught in the hole and smooth rotation of the drum, that is, smooth rotation of the paper feed roller may not be obtained. .

On the other hand, according to the paper feeding device of the third aspect, the brake pad is larger than the hole formed in the peripheral wall of the drum, so that the brake pad does not get caught in the hole. Smooth rotation of the paper roller can be obtained.

[0032]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a side view showing a main part of an embodiment of a sheet feeding apparatus according to the present invention, FIG. 2A is a partially exploded perspective view thereof, and FIG. 2B is a perspective view of a brake lever.

In these figures, reference numeral 10 denotes a paper feed roller, which is fixed to a paper feed roller shaft 11 having a cross-shaped cross section, rotates together with the paper feed roller shaft, and comes in contact with paper (not shown) to feed the paper. It has become.

Reference numeral 20 denotes a drum, which is fixed to one end of the feed roller shaft 11. A gear (not shown) is fixed to the other end of the feed roller shaft 11, and the feed roller shaft 1 is connected via the gear and a power transmission path (not shown).
1 is driven to rotate by a motor (not shown).

Reference numeral 30 denotes a brake pad (hereinafter also simply referred to as a pad), which is attached to a tip 31 a of a brake lever 31. The pad 30 is made of an appropriate friction member, for example, felt, urethane foam rubber, or the like.
It is affixed to the tip 31a of the brake lever 31. The pad 30 is formed larger than a hole 22 described later.

The brake lever 31 has a through hole 31b.
Is fitted to a shaft 42 projecting from the side wall 41 of the frame 40 to be rotatably attached to the side wall 41 of the frame 40.

The shaft 42 has a side wall 41 and a brake lever 3
1, a torsion spring 50 is interposed.
The one end 51 of the torsion spring 50 is locked by the hook 43 provided on the side wall 41, and the other end 52 is locked by the hook 31 c provided on the brake lever 31. In FIG. 1, the pad 30 is urged clockwise, that is, in a direction in which the pad 30 is pressed against the peripheral wall 21 of the drum 20.

A hole 22 is formed in the peripheral wall 21 of the drum 20. On the other hand, a detector 60 for detecting the position of the paper feed roller 10 by detecting the hole 22 is attached to the side wall 41. In this embodiment, a photo interrupter having a light projecting unit 61 and a light receiving unit 62 is used as the detector 60. Detector 60
Is for detecting the initial position (standby position) of the paper feed roller 10.

The apparatus as described above is incorporated in a main body (not shown) of, for example, a printer or the like, and a pair of conveying rollers provided in the main body (not shown, the main body includes a conveying roller shown in FIG. 3). (E.g., a pair of transport rollers equivalent to pairs 3 and 4 are provided) (see FIGS. 3A to 3E), that is, the sheet is fed, and the leading edge of the sheet is fed. Is slightly passed through the pressure portion of the transport roller pair,
0 is temporarily stopped and the conveying roller pair is rotated in the reverse direction so that the leading edge of the sheet follows the pressing portion of the conveying roller pair to prevent skew of the sheet and feed the sheet.

According to the above-described paper feeder, the following operational effects can be obtained.

(I) Since the drum 20 is fixed to the end of the feed roller shaft 11 and the brake pad 30 is pressed against the drum 20, the transport roller pair is rotated backward (FIG. 3). (D), the brake pad 30 is pressed against the drum 20 fixed to the end of the feed roller shaft 11 even if the power transmission path to the feed roller 10 is cut off. As a result, a rotational load is applied to the paper feed roller 10.

Accordingly, when the sheet is pushed back (reversely fed) due to reverse rotation of the conveying roller pair, the sheet feeding roller 10 does not rotate together, and as a result, the leading end of the sheet is As a result, the paper is prevented from skewing along the pinching portion.

That is, according to the sheet feeding device, the operations (a) to (e) described above can be reliably performed by one motor.

The rotational load (moment) due to the pressure contact between the drum 20 and the pad 30 is smaller than the driving force obtained by the motor and larger than the moment generated around the paper feed roller shaft 11 when the paper is fed backward. Is set. This rotation load is applied to the paper feed roller shaft 11 when the paper is fed backward.
It is desirable to set as small as possible within a range larger than the moment generated around. Paper feed roller 10
This is for minimizing the load at the time of the rotation operation.

(B) Since the drum 20 is a drum for detecting the position of the paper feed roller 10, there is no need to provide a separate drum for pressing the brake pad 30. As a result, the number of parts can be reduced and the apparatus can be reduced. Can be reduced in size.

Further, when the power transmission path to the paper feed roller 10 is cut off, the paper feed roller 10 is prevented from rotating unnecessarily for some reason (for example, vibration).
It is also possible to prevent the position detection accuracy of the paper feed roller 10 from deteriorating.

(C) The detector 6 is mounted on the peripheral wall 21 of the drum 20.
The hole 22 to be detected by 0 is drilled,
Since the brake pad 30 is larger than the hole 22, the smooth rotation of the paper feed roller 10 can be obtained.

If the brake pad 30 is smaller than the hole 22, the brake pad 30 is caught in the hole 22, and the smooth rotation of the drum 20, that is, the smooth rotation of the paper feed roller 10 cannot be obtained. There is a risk.

On the other hand, according to the paper feeder of this embodiment, since the brake pad 30 is larger than the hole 22, the brake pad 30 does not get caught in the hole 22. Ten smooth rotations are obtained.

As described above, one embodiment of the present invention has been described. However, the present invention is not limited to the above-described embodiment, and can be appropriately modified within the scope of the present invention.

[0052]

According to the present invention, the sheet feeding operation including the sheet skew preventing operation can be reliably performed by one motor.

[0053]

[Brief description of the drawings]

FIG. 1 is a side view showing a main part of an embodiment of a sheet feeding device according to the present invention.

2A is a partially exploded perspective view of the same, and FIG. 2B is a perspective view of a brake lever.

FIGS. 3A to 3E are explanatory diagrams of a conventional technique.

[Description of Signs] 3, 4 Conveyance Roller Pair 10 Feed Roller 11 Feed Roller Shaft 20 Drum 21 Peripheral Wall 22 Hole 30 Brake Pad 60 Detector

Claims (3)

[Claims] A paper feed roller fixed to a paper feed roller shaft, rotates together with the paper feed roller shaft, and feeds the paper in contact with the paper, and squeezes the paper fed by the paper feed roller. A pair of conveying rollers for conveying, and after the leading edge of the sheet slightly passes through the nip portion of the pair of conveying rollers, the paper feed roller is temporarily stopped and the pair of conveying rollers is rotated in reverse to nip the pair of conveying rollers. A sheet feeding device for preventing the sheet from skewing along the leading edge of the sheet, comprising: a drum fixed to an end of the sheet feeding roller shaft; and a brake pad pressed against the drum. A sheet feeding device. 2. The sheet feeding device according to claim 1, wherein the drum is a drum for detecting a position of a sheet feeding roller. 3. The sheet feeding device according to claim 2, wherein a hole to be detected by a detector is formed in a peripheral wall of the drum, and the brake pad is larger than the hole.