JPS6360833A - Paper feeding mechanism - Google Patents

Abstract

PURPOSE:To enable a recording paper to be fed on both surfaces by a simple construction and improve accuracy in paper feeding by providing both ends of a feeding roller and paper holding rollers to opposed to each other and project from the width of recording paper while pressing each other in sandwiching the recording paper. CONSTITUTION:A paper feeding roller 1 is constituted from a paper feeding portion 1-a and torque transmitting portions 1-b. Assuming the thickness of recording paper 3 is t, the respective radii ra, rb of said portions are set in the relationship, rb>ra+t. On the other hand, paper holding rollers 2 made of an elastic body sandwich the recording paper 3 between them and the paper feeding portion 1-a, while pressing the torque transmitting portions 1-b at portions other than these contacting the recording paper 3. Then, the respective pressing radii rd, re of sandwiching portions 2-a and pressing portions 2-b are set in the relationship, rd+rb=r3+t+ra, while being set to the relationship, rd<re. Thus, the radius of torque transmitting portions 1-a is made larger than the radius of the paper feeding portion 1-b by an amount exceeding the thickness of recording paper 3 to improve the torque transmission.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a paper feeding mechanism for a printer, and particularly to a high-precision paper feeding mechanism for the purpose of outputting images and the like.

[Conventional technology]

A schematic configuration of a conventional paper feeding mechanism 9 will be explained with reference to FIGS. 4 and 5. Fig. 4 shows a generally used diro paper feeding mechanism, in which the recording paper is narrowly pressed by the paper presser roller 5 and the paper feed roller 4, and is placed between the recording paper 3 and the paper feed roller 4. Using the generated frictional force, the paper feed roller 4 is fed when it rotates by receiving torque from a driving means (not shown). Assuming that the friction coefficient between the recording paper 6 and the paper feed roller 4 is μm, the pinching load is P, and the shaft loss and the wrapping of the recording paper 3 around the paper feed roller 4 are ignored, the paper feed force F is F-μm× P...The first equation is obtained. Fifth
The figure shows a system commonly used to increase the paper feeding force by transmitting torque to both the paper feeding roller 4 and the paper pressing roller 5 and utilizing the frictional force generated on both sides of the recording paper. In the paper feeding mechanism, the torque transmitted from the drive means (not shown) to the paper feeding roller 4 is further transmitted to the paper pressing roller 5 via gears 6 and 7, and the transmission ratio between the gears 6 and 7 is adjusted to the paper pressing roller 4. The circumferential speed of the roller 5 is set to be greater than the circumferential speed of the paper feed roller 5. During the paper feeding operation, a torque limiter (not shown) interposed in the transmission system between the paper feeding roller 4 and the paper presser roller 5 acts, and a constant feeding force is applied from the paper presser roller 5 to the recording paper 3. If the coefficient of friction between the paper press roller and the recording paper 5 is μ2, and the feeding force limited by the torque limiter is T, then the paper feeding force F is: F−μzP+T... Second formula % formula % T×μ2P and T<μIP...The fifth equation must be satisfied.

[Problem that the invention seeks to solve]

However, conventional single-sided feed (Fig. 4), double-sided feed (
The paper feeding mechanism according to FIG. 5) had the following problems.

In the case of a single-sided feeder type as shown in Figure 4, in order to obtain a large paper feeding force, as is clear from equation 1, the clamping load must be increased or the friction coefficient must be increased. However, if the clamping load is increased, shaft loss and other loads will increase, which will require an increase in the power of the drive means, which will not only be detrimental to lower power consumption, but also paper feed rollers are generally designed to have as large a friction coefficient as possible. Because materials such as rubber are used to obtain
This results in significant elastic deformation, resulting in a decrease in paper feeding accuracy, and in order to obtain a large friction coefficient, special treatment is required on the surface of the paper feeding shear roller, which has been a hindrance to cost reduction. In addition, when feeding recording paper with copy paper or transparent film for backing material, etc., the feeding force is transmitted only to one side, so there is A relative discrepancy will occur.

In addition, in the double-sided feeding method as shown in Fig. 5, the second type,
From equation 6, it is possible to obtain a large paper feeding force without changing the clamping load, but parts such as gears and torque limiters are required, which increases the cost of the paper feeding mechanism. In addition, since gears are involved when transmitting torque from the paper feed roller to the paper presser roller, the transmission torque and the peripheral speed of the paper presser roller fluctuate due to the meshing of the gears, which not only reduces the pitch accuracy of paper feed υ. When feeding recording paper in both forward and reverse directions, due to gear backlash and play in the torque limiter, paper feeding accuracy and paper feeding error cannot be ensured when reversing, etc.
Conventional paper feeding mechanisms have the above-mentioned problems in both single-sided and double-sided paper feeding.

[Means for solving problems]

The present invention solves this problem. Both ends or one end of the paper feed roller and the paper presser roller protrude beyond the width of the recording paper, and are opposed to each other and are in pressure contact with each other, and the radius of the paper feed roller in this area is [Function] According to the paper feeding mechanism of the present invention, the paper feeding roller and Torque is frictionally transmitted from the paper feed roller to the paper press roller at the portion where the paper press roller protrudes from the width of the recording paper and presses against it. The radius of the torque transmission part of the paper feed roller (the part in pressure contact with the paper press roller) is larger than the radius of the paper feed part (recording paper narrow pressure part) by an amount that exceeds the thickness of the recording paper, and the paper press roller is made of an elastic body. Therefore, the radius of the torque-transmitted part of the paper presser roller (the part in pressure contact with the paper feed roller) is deformed so that it becomes smaller than the radius of the paper narrow pressure part, and the torque transmission from the paper feed roller to the paper presser roller is Due to the increased speed transmission, the peripheral speed of the paper presser opening V is
If the circumferential speed of the paper feed rope is greater than that, the recording paper is fed on both sides.

〔Example〕

An embodiment according to the present invention will be explained with reference to FIGS. 1, 2, and 3.

Reference numeral 1 denotes a paper feed roller, which is a stepped roller consisting of a paper feed section 1-a and a torque transmission section j-b. -a is rubber with high hardness, torque transmission part is metal or plastic,
Alternatively, surface-treated metal is used for the paper feed section 1-a. The radius r of the torque transmission section 1-b and the radius r of the paper feeding section 1-a are r, where t is the thickness of the recording paper 3.
b> r a + j ......The fourth formula is satisfied. Reference numeral 2 denotes a paper pressing roller made of an elastic material such as rubber, and by applying a pressure load to pinch the recording paper 6, the recording paper 3 is moved to the paper feeding portion 1-a of the paper feeding loaf 1.
It is in pressure contact with the torque transmitting portion 1-b of the paper feed roller 1, which is removed from the recording paper 5. Since the paper pressing roller 2 is an elastic body, by applying a pinching load, the portion 2-a that pinches the recording paper 3 and the portion 2-a that is in pressure contact with the paper feed roller 1 are elastically deformed, and the second As shown in FIG. 3, it is in pressure contact with the paper feed roller 1 or the recording paper 5. If the pressure contact radius of the pressure contact portion 2-b with the paper feed roller 1 is rdl, and the pressure contact radius of the pressure contact portion 2-a that pinches the recording paper 3 is tlr, then the center distance between the paper feed roller 1 and the paper presser roller 2 is constant. ra + rb -re + t + ra -...
- Equation 5 is obtained, and from Equation 4, r, (r, ......The coefficient of friction between the paper feeding section 1-a of the 6th type paper feeding roller 1 and the recording paper 3 is μm,
Assuming that the pinching load between the paper presser roller 2 and the recording paper 5 is P1, the friction coefficient is μ2, and the pressure contact load between the paper presser roller 2 and the torque transmission section 1-b of the paper feed roller 1 is Q1, the friction coefficient is μ3, μtP, respectively. ＞-μ3Q and μ2P＞-μ3Q ・・・・・・
Equation 7 % Equation % The paper feeding υ operation by this paper feeding mechanism is performed by paper feeding roller 1
is rotated by torque transmission from a driving means (not shown), and at the same time, the paper presser loaf 2 is rotated by being given torque by friction transmission to the torque transmission section 1-b of the paper feed roller 1, and the recording paper 3 Paper feeding force is applied from both sides, and the paper is fed.

The paper feeding force F1 by the paper feeding roller 1 is due to the shaft loss and the recording paper 5.
Ignoring the winding, Fl-μIP . . . Formula 8 is obtained. If the circumferential speed of the paper feeding section 1-a of the paper feeding roller 1 is 1, and considering that the paper press roller 2 and the recording paper 3 slip, the circumferential speed V2 of the narrow pressure section 2-a of the paper press roller 2 is , Vl--x-xv, ..9th formula %formula%, and from the 4th and 6th formulas, Vl>Vl ..11th formula According to Equation 7, there is actually a slip between the torsion transmitting portion 1-b of the paper feed roller 1 and the paper presser roller 2, and the paper feed force F2 by the paper presser roller 2 is F x −r. @μ3Q
Medium μ3Q......Formula 12, recording paper 3
is given a paper feeding force of 9 μIP, 10 μ3Q, from both sides, and the paper is fed.

〔Effect of the invention〕

According to the paper feeding mechanism configured as described above, it is possible to realize double-sided production of recording paper with a simple structure, and it is possible to reduce costs, reduce power consumption, use a film with backing paper, etc., and high-definition variable paper feeding. Not only is this possible, but since torque is transmitted between the paper feed roller and paper presser roller without intervening gears, torque limiters, etc., high-precision paper can be easily fed even when paper is fed in both forward and reverse directions. can be realized.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of an embodiment of the present invention, and FIGS. 2 and 3 are according to the embodiment of the present invention. A cross-sectional view showing the state of pressure contact between the paper feed roller and the paper press roller,
FIGS. 4 and 5 are drawings showing the configuration of a conventional paper feeding mechanism. 1.4...Paper feed roller 2.5...Paper pusher roller 3......Recording paper and above Applicant Seiko Epson Corporation -10 - Figure 1 O'At /+l CTj
reactor! ) -4th part 1

Claims (1)

[Scope of Claims] 1) A paper feed mechanism for a printer that is composed of a paper feed roller and at least one paper press roller, and feeds the recording paper by narrowly pressing the recording paper between the paper feed roller and the paper press roller. A paper feeding mechanism characterized in that both ends or one end of the paper feeding roller and the paper pressing roller protrude from the width of the recording paper and face each other, and are pressed against the recording paper during narrow pressure. 2) The radius of the pressure contact portion of the paper feed roller with the paper presser roller is larger than the radius of the narrow pressure portion of the recording paper, and the difference exceeds the thickness of the recording paper, and the paper presser The paper feeding mechanism according to claim 1, wherein the roller is an elastic body.