JPH0930664A - Sheet feeding device of printing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the load applied on a cam and quicken the cam motions by forming a driving means to rotate the rotary shaft of the cam so that contacting with a sheet supporting part is commenced with the side going farther from the fulcrum of the sheet supporting part than the rotary shaft of the cam. SOLUTION: When the uppermost sheet of paper P of the stack formed on a sheet supporting part 10 are to be separated from a payoff roller 20, a driving means 50 rotates a can 41 so that contacting with the sheet supporting part 10 is commenced with the side going farther from the fulcrum 15 of the part 10 than the rotary shaft 42 of the cam. This reduces the load applied on the cam 41, compared with a conventional arrangement. That is, the load applied on the cam 41 by the part 10 (reactive force) is smaller in case the cam contacting is started with the side farther from the fulcrum 15, than in case contacting is started with the nearer side, which should lead to quickening of cam motions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feeding device of a printing device.

[0002]

2. Description of the Related Art Conventionally, as a paper feeding device of a printing device,
It is known that a paper supported on the paper support is brought into contact with a paper feeding roller by rotating the paper support about a fulcrum, and the rotational force of the roller is used to feed the paper one by one. There is.

FIG. 4 shows a conventional structure of such a sheet feeding device (10P). In FIG. 4, 10 is a sheet supporting portion, 20 is a sheet feeding roller, 30 is a pressing spring as a pressing means, 4
0P is a cam device and 50P is a drive means.

The sheet supporting portion 10 is provided on a printer body frame (not shown) so as to be rotatable around a fulcrum (fulcrum 15) and is formed so as to be capable of supporting a plurality of sheets.

The sheet feeding roller 20 is provided on the sheet supporting portion 10.
The uppermost sheet (P) among the sheets supported by the sheet is configured to be fed out. Specifically, the paper feeding roller 20 is rotatably supported by the printer body frame via a roller shaft 21, and a driving unit 50 described in detail later.
It is rotationally driven by P in a predetermined direction (clockwise direction in FIG. 4).

The pressing spring 30 is a means for pressing the paper supporting portion 10 so that the uppermost paper (P) among the plurality of papers supported by the paper supporting portion 10 comes into contact with the paper feeding roller 20.

The cam device 40P is provided with the sheet support portion 10 so that the uppermost sheet (P) is separated from the sheet feeding roller 10.
Is means for rotating against the pressing force of the pressing spring 30.

Specifically, the cam device 40P includes an engaging portion 46 provided on the back side of the sheet supporting portion 10 and a rotary shaft 42.
The cam 41 is provided on the printer body frame so as to be rotatable about its axis, and is in contact with the engaging surface 47 of the engaging portion 46.

The cam 41 is rotated clockwise in FIG. 4 to come into contact with the engaging surface 47 of the engaging portion 46 and press the engaging portion 46 (hence the sheet supporting portion 10) to the spring 30.
Push down against the elastic force of. As a result, the uppermost sheet (P) on the sheet supporting unit 10 is separated from the sheet feeding roller 20.

The drive means 50 includes a drive motor 51, a clutch device 52, a power transmission gear mechanism 53, etc., and is configured to be able to switch and supply rotational power to the paper feeding roller 20 and the rotary shaft 42 of the cam 41. ing.

[0011]

In the paper feeding device, the cam 41 is used while being switched from the power of the paper feeding roller 20, so it is convenient that the driving time of the cam 41 is as short as possible.

Further, there are cases where other operations are performed in the cam sequence, and in the sequence of one round of the cam 41,
The shorter the operation of the cam 41, the better the sequence becomes.

In view of the above circumstances, an object of the present invention is to provide a paper feeding device of a printing device capable of reducing the load acting on the cam and accelerating the cam operation.

[0014]

SUMMARY OF THE INVENTION According to the present invention, a sheet supporting portion rotatable about a fulcrum, a sheet feeding roller capable of feeding the uppermost sheet supported by the sheet supporting portion and feeding the sheet, A pressing unit that presses the sheet supporting unit so that the upper sheet contacts the sheet feeding roller, and a cam that rotates the sheet supporting unit against the pressing force of the pressing unit to separate the uppermost sheet from the sheet feeding roller. In a paper feeding device of a printing apparatus, which comprises a device, a sheet feeding roller, and a drive unit capable of switching and supplying rotational power to a rotary shaft of a cam of a cam device, the drive unit is configured such that the cam has a rotation axis greater than the rotation axis. The present invention is characterized in that the rotation shaft of the cam is rotationally driven so as to start contact with the sheet support section from the side away from the fulcrum of the sheet support section.

In the present invention having the above structure, the driving means is
The cam is rotated so as to start contact with the sheet support section from the side farther from the fulcrum of the sheet support section than the rotation shaft.

As a result, when the sheet supporting portion is rotated against the pressing force of the pressing means, the load acting on the cam can be reduced and the cam operation can be speeded up.

The principle of the present invention will be described below with reference to the sheet feeding device shown in FIGS. 2 (A) and 2 (B).

The same components as those of the conventional example (FIG. 4) are designated by the same reference numerals, and the description thereof will be omitted. A is the distance between the fulcrum (15) of the paper support 10 and the rotation shaft 42 of the cam 41, and B is the distance between the fulcrum (15) and the point of application of the pressing force P of the pressing means (30). Is. Further, R is the tip of the cam 41 (maximum radius part) and the rotary shaft 42.
Is the distance between

As shown in FIG. 2, the cam 41 starts contacting with the engaging surface (for example, the upper surface) 43 of the paper supporting portion 10 from the side farther from the fulcrum (15) of the paper supporting portion 10 than the rotating shaft 42. When rotated counterclockwise in the figure by an arbitrary angle θ from the reference position shown in (A) [see (B) in the figure].
Further, when the force exerted by the cam 41 on the sheet supporting portion 10 is F1, F1 (Rcos θ + A) = PB Therefore, F1 = PB ÷ (A + Rcos θ) ... Strictly speaking, F1 is PB ÷ (A + Rcos
θ must be larger than θ), but they are the same for convenience of explanation. The same applies to Equation 2 below.

On the other hand, the cam 41 is replaced with the rotary shaft 4 as in the conventional case.
2 is rotated clockwise so as to start contact with the engagement surface 43 of the paper supporting portion 10 from the side closer to the fulcrum 15 of the paper supporting portion 10 than 2, the tip portion of the cam 41 is rotated. When the force exerted from the cam 41 to the sheet supporting portion 10 when the lens further rotates by the angle θ from the position where the contact with the engaging surface 43 is started is F2, F2 (A−Rcos θ) = PB Therefore, F2 = PB ÷ (A-Rcos θ) ... Equation 2 is obtained.

From Equation 1 and Equation 2, F1 / F2 = (A-Rcos θ) / (A + Rcos θ) ... Equation 3 is obtained.

Here, for example, when the ratio of A and R is 5: 1 and F1 changes from 0 to 90 °, F1
A diagram of / F2 is shown in FIG. For example, θ = 0 °, 45
The values of F1 / F2 in the case of ° and 60 ° are 0.6 respectively.
It becomes 7,0.75,0.82. That is, when the cam 41 starts contacting the paper supporting portion 10 from the side far from the fulcrum (15), the cam 4 starts contacting from the near side.
1, the load (reaction force) applied from the sheet supporting portion 10 is reduced, and the cam operation can be speeded up.

Therefore, it is possible to rotate the sheet supporting portion with a driving force (starting torque) smaller than that of the conventional example. On the contrary, if the same torque is applied, a cam shape with an acute angle is allowed accordingly.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. This paper feeder is shown in FIGS. 1 (A) and 1 (B).
As shown in FIG. 4, the basic structure is the same as that of the conventional example (FIG. 4), but the drive means 50 is provided, and the cam 41 of the cam device 40 is farther from the fulcrum (15) of the paper support 10 than the rotation shaft 42. Is configured to start contact with the sheet supporting unit 10.

The same components as those of the conventional example (FIG. 4) are designated by the same reference numerals, and the description thereof will be simplified or omitted.

The cam 41 of the cam device 40 is mounted on the rotary shaft 42 and has a fan shape.

The drive means 50 starts contact with the engagement surface (for example, the upper surface) of the paper support portion 10 from the side of the cam 41 farther from the fulcrum (support shaft 15) of the paper support portion 10 than the rotary shaft 42. It is a means for rotationally driving so as to perform.

Next, the operation of this embodiment will be described. When the uppermost sheet (P) on the sheet supporting portion 10 is separated from the sheet feeding roller 20, the driving means 50 causes the cam 41 to move the cam 41 more than the rotary shaft 42 to the fulcrum (1
5) It is rotated so as to start contact with the sheet supporting unit 10 from the side away from 5). Then, the above-mentioned principle [Fig. 2
Based on (A) and (B)], the load acting on the cam 41 can be reduced as compared with the conventional example.

In this embodiment, however, the driving means 5
0 is rotationally driven so that the cam 41 starts contact with the engagement surface 43 of the paper supporting portion 10 from the side farther from the fulcrum (15) of the paper supporting portion 10 than the rotating shaft 42, so that the configuration is simplified. It is possible to reduce the load on the cam 41 and speed up the cam operation.

[0030]

According to the present invention, the driving means is rotationally driven so as to start contact with the paper supporting portion from the side of the cam farther from the fulcrum of the paper supporting portion than the rotating shaft, so that the structure is simplified. It is possible to reduce the cam load and speed up the cam operation.

[Brief description of drawings]

FIG. 1 is a diagram for describing an embodiment of the present invention.

FIG. 2 is a diagram for explaining the principle of the present invention.

FIG. 3 is a diagram for explaining the relationship between the cam rotation angle and the driving force ratio.

FIG. 4 is a diagram for explaining a conventional configuration of a paper feeding device of a printing device.

[Explanation of symbols]

 10 Paper Supporting Part 15 Support Shaft (fulcrum) 20 Paper Feeding Roller 30 Pressing Spring (Pressing Means) 40 Cam Device 41 Cam 42 Cam Rotating Shaft 50 Driving Means

Claims (1)

[Claims] 1. A paper support portion rotatable about a fulcrum, a paper feed roller capable of feeding and feeding the uppermost paper supported by the paper support portion, and the uppermost paper contacting the paper feed roller. So as to press the sheet supporting portion, a cam device for rotating the sheet supporting portion against the pressing force of the pressing means to separate the uppermost sheet from the sheet feeding roller, the sheet feeding roller and the cam. In a paper feeding device of a printing device, which comprises a rotating shaft of a cam of the device and a driving means capable of switching and supplying rotational power, a side where the cam is farther from a fulcrum of the paper supporting unit than the rotating shaft is. The sheet feeding device of the printing device, wherein the rotation shaft of the cam is rotationally driven so as to start contact with the sheet supporting portion.