JPH06320811A - Sheet feeding mechanism for printer - Google Patents

Abstract

PURPOSE:To effectively grip an end of a sheet by a main sheet feed roller and a first pressure roller, to reduce a pressing force of the pressure roller and to prevent a contamination of a copy sheet by indentation. CONSTITUTION:A sheet feeding mechanism has a main sheet feed roller 1 to be rotated by a rotary drive force of a motor, and first, second pressure rollers 4, 5 rotatably supported in parallel to the roller 1 and energized by the roller 1, and comprises gears 11, 12 fixed to the rollers 4, 5 and coupled by an idle gear 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feed mechanism of a printer, and more particularly, to a pair of pressure rollers rotatably supported in a paper feed direction with respect to a main paper feed roller so that the rotational force of the pressure roller is greatly increased. The present invention relates to a paper feed mechanism improved so as to be increased.

[0002]

2. Description of the Related Art A paper feeding mechanism of a conventional printer is shown in FIG.
As shown in FIG. 1, a main paper feed roller 1 and a pair of first and second pressure rollers 4, 5 rotatably attached to the roller support plate 6 and arranged parallel to the axial direction of the main paper feed roller 1. Is equipped with. The central portion of the roller support plate 6 is swingably attached to one end of an L-shaped pressure arm 8 rotatably supported by the support shaft 7, and the other end of the pressure arm 8 is a spring. It is pulled counterclockwise in FIG. As a result, the pair of pressure rollers 4 and 5 are pressed against the outer peripheral surface of the main paper feed roller 1 by the force of the spring 9. The other end of the pressure arm 8 has an arm 8
The release shafts 10 for rotating clockwise are provided opposite to each other.

In the sheet feeding mechanism constructed as above,
When the main paper feed roller 1 is rotationally driven by a motor (not shown) via a reduction gear mechanism, both the pressure rollers 4 and 5 biased against the roller 1 are driven to rotate. Therefore, the paper 3 fed along the paper guide 14 is sandwiched between the main paper feed roller 1 and the first pressure roller 4 and taken in, and further, by the main paper feed roller 1 and the second pressure roller 5. It is pinched and sent to the print position. Main paper feed roller 1
Also has a function as a platen, and the carriage 2a
Printing is performed on the paper 3 on the roller 1 by scanning in the printing direction by the print head 2 fixed to. After the printing of one line is completed, the main paper feed roller 1 is driven to feed the paper 3 by the predetermined amount required for line feed. The pressed state between the main paper feed roller 1 and the pressure rollers 4 and 5 is released when the release shaft 10 is rotated and the pressure arm 8 is rotated clockwise.

[0004]

In the above-described conventional paper feeding mechanism, the first pressure roller 4 and the second pressure roller 5 are independently driven by the main paper feeding roller 1 to rotate. When an envelope or thick paper is tried to be fed, the leading edge of the paper between the main paper feed roller 1 and the first pressure roller 4 may not be well caught, and the paper 3 may not be fed well. Therefore, the first pressure roller 4 is made of a rubber material having a high friction coefficient, and the biasing force (pulling force of the spring 9) for pressing the pressure roller 4 against the main paper feed roller 1 is used.
Can be strengthened. However, if the pressure roller 4 is made of such a material, there is a problem that the roller 4 becomes expensive. In addition, the main paper feed roller 1
When the urging force of the pressure rollers 4 and 5 is increased, there arises a problem that indentation stains occur on the copy surface of the copy sheet.

To solve this problem, Japanese Laid-Open Patent Publication No. 64-22452 proposes a sheet feeding mechanism in which, as shown in FIG. 5, other pressure rollers 20 and 21 which are driven to rotate between the pressure rollers 4 and 5 are interposed. There is. However, the pressure rollers 4, 20, 2 that perform such driven rotation
Even if a paper feed mechanism having a plurality of rows of 1 and 5 is configured, it is not possible to fundamentally improve the biting of the leading edge of the paper by the main paper feed roller 1 and the first pressure roller 4, so that thick paper, etc. When attempting to feed the paper, the paper cannot be satisfactorily fed like the above-mentioned conventional example.

The present invention has been proposed in order to solve the problems of the prior art as described above, and it is possible to reliably bite the leading edge of the paper between the main paper feed roller and the first pressure roller. In addition, it is an object of the present invention to provide a paper feed mechanism of a printer that can reduce the pressing force of the pressure roller and prevent indentation stains on the copy surface of the copy paper.

[0007]

To achieve this object, the present invention is directed to a main paper feed roller that is rotated by the rotational driving force of a motor, and is supported rotatably in parallel to the main paper feed roller. A paper feed mechanism having first and second pressure rollers biased by the main paper feed roller, wherein the first pressure roller and the second pressure roller are connected to each other by a rotation transmission means, Accordingly, the rotation transmitting means is a gear fixed to each of the first and second pressure rollers,
An idle gear interposed between these gears, and the rotation transmitting means includes pulleys fixed to the first and second pressure roller sides, and a toothed belt wound between these pulleys. Further, the rotation transmission means is composed of gears fixed to the first and second pressure roller sides, respectively, and a chain wound between these gears.

[0008]

According to the paper feeding mechanism of the printer having the above-described structure, if either one of the first and second pressure rollers is pressed against the main paper feeding roller, the first and second pressure transmitting means are rotated through the rotation transmitting means. Make sure that the pressure roller rotates (actual rotation). Therefore, when feeding thick paper or the like, even if the first pressure roller cannot obtain sufficient rotation force from the main paper feed roller, the rotation force of the second pressure roller is transmitted to the first pressure roller, The paper feeding force of the first pressure roller that bites the edge is increased.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a paper feeding mechanism of a printer according to the present invention will be described below in detail with reference to the drawings. Figure 1
An example of this paper feed mechanism is shown in FIG. In this figure, the first and second pressure rollers 4 and 5 pressed against the peripheral surface of the main paper feed roller 1 are rotatably attached to the roller support plate 6 by roller shafts 4a and 5a. ing. The first pressure roller 4 arranged on the paper feed side of the paper 3 has a larger diameter than the second pressure roller 5. These pressure rollers 4 and 5 are molded using a material such as POM (polyacetal), PA (nylon), PC (polycarbonate), or the like.

The roller support plate 6 is similar to that of the conventional example.
A pressure arm 8 which is rotatable by a support shaft 7 is swingably attached to one end of a pressure arm 8 via a fulcrum pin 6a. The other end of the pressure arm 8 is counterclockwise in a stop hole 8a. One end of the spring 9 that is pulled to is locked. As a result, the first and second pressure rollers 4 and 5 are urged against the main paper feed roller 1 by receiving the tensile force of the spring 9. When the pressure rollers 4 and 5 are pressed against the main sheet feed roller 1, the release shaft 10 facing the right side in the figure on the other end side of the pressure arm 8 is rotated clockwise against the tensile force of the spring 9. It is released by moving it. Main paper feed roller 1
Also has a function as a platen, and the carriage 2a
Printing is performed on the paper 3 on the roller 1 by scanning in the printing direction by the print head 2 fixed to. After the printing of one line is completed, the main paper feed roller 1 is driven to feed the paper 3 by the predetermined amount required for line feed.

Next, a structure for positively rotating the first and second pressure rollers 4 and 5 will be described. Figure 2
As shown in, the first spur gear 11 is fixed to the roller shaft 4a supporting the first pressure roller 4,
A second spur gear 12 is fixed to a roller shaft 5a that supports the second pressure roller 5. These spur gears 11 and 12 have the same ratio to the outer diameters of the first and second pressure rollers 4 and 5. That is, the outer diameters of the first and second pressure rollers 4 and 5 are Φ1 and Φ2, respectively, and the first and second spur gears 1 are
If the numbers of teeth of 1 and 12 are G1 and G2, then Φ1 / Φ2 = G1 / G2. An idle gear 13 for connecting the first and second spur gears 11 and 12 is rotatably attached to the lower center of the roller support plate 6 via a gear shaft 13a. Spur gears 11 and 12
Meshes with an idle gear 13 interposed in the intermediate portion, and the spur gears 11 and 12 and the idle gear 13 constitute a rotation transmitting means.

In the sheet feeding mechanism thus constructed, the rotational force of the motor (not shown) is transmitted to the roller shaft 1 via the reduction gear.
When the main sheet feed roller 1 is transmitted to the sheet a, the first and second pressure rollers 4 and 5 pressed by the sheet feed roller 1 are also rotated. At this time, the first and second pressure rollers 4, 5 are
Is connected by an idle gear 13, and when one of the pressure rollers rotates, the other pressure roller surely rotates (positive rotation). That is, since the rotational force of the second pressure roller 5 is transmitted to the first pressure roller 4 via the idle gear 13, the first pressure roller 4 is reliably rotated, and when the sheet 3 is taken in, The paper feeding force can be obtained by both the first pressure roller 4 and the main paper feeding roller 1 which is rotationally driven. Therefore, the leading edge 3a of the sheet 3 fed along the paper guide 14 is surely bitten by the main sheet feed roller 1 and the first pressure roller 4, so that the thick sheet 3 can be reliably fed.

In the above embodiment, one idle gear 13 is interposed between the first and second spur gears 11 and 12, but three idle gears are interposed between the first and second spur gears 11 and 12. It is also possible to adopt a configuration in which an odd number of idle gears, which is equal to or greater than the above, is interposed. As described above, when three or more odd-numbered idle gears are used, there are advantages that the degree of freedom in gear arrangement is increased and each idle gear can be downsized.

Next, a sheet feeding mechanism of another embodiment will be described with reference to FIG. In this embodiment, the pulleys 15 and 16 constituting the rotation transmitting means are fixed to the roller shafts 4a and 5a of the first and second pressure rollers 4 and 5, respectively.
A belt is wound between these pulleys 15 and 16. As the belt 17, a round belt, a flat belt, a toothed belt, or the like can be used. Particularly, when a toothed belt is used, slippage can be prevented and the first and second pressure rollers 4 and 5 can be positively rotated. Reference numeral 18 is a limiter for giving tension to the belt 17. Also, the pulley 15,
A gear and a chain may be used instead of 16 and the belt 17, and by doing so, the first and second pressure rollers 4 and 5 can be rotated more reliably.
With such a configuration, the size can be reduced as compared with the case where the idle gear is used.

[0015]

As described above, according to the present invention, the first and second pressure rollers are connected by the rotation transmission means so that they can be positively rotated with respect to the main paper feed roller. The first pressure roller can be reliably rotated, and the paper feeding force can be greatly increased.
As a result, the leading edge of the paper fed along the paper guide is surely bitten by the main paper feed roller and the first pressure roller before being fed, so even when feeding envelopes or thick paper, feeding errors may occur. The paper can be fed well without causing any trouble. In this way, it is possible to increase the biting of the leading edge of the paper, so that the first pressure roller does not need to be made of a rubber material having a large friction coefficient and can be molded using a plastic material, so that the paper feeding mechanism can be configured at low cost. it can. Further, since it is not necessary to increase the pressing force of the pressure roller with respect to the main paper feed roller, it is possible to prevent the impression of the copy paper which is generated when the pressing force is increased.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a paper feeding mechanism of a printer according to the present invention.

FIG. 2 is a plan view of the paper feed mechanism of FIG. 1 in which a main paper feed roller is omitted.

FIG. 3 is a sectional view showing a paper feeding mechanism of another embodiment.

FIG. 4 is a cross-sectional view showing a conventional paper feeding mechanism.

FIG. 5 is a sectional view showing another conventional paper feeding mechanism.

[Explanation of symbols]

 1 Main Paper Feed Roller 2 Print Head 3 Paper 4 First Pressure Roller 5 Second Pressure Roller 6 Roller Support Plate 8 Pressure Arm 9 Spring 10 Release Shaft 11 First Spur Gear 12 Second Spur Gear 13 Idle Gear 14 Paper Guide 15, 16 Pulley 17 Belt 18 Limiter

Claims (4)

[Claims] 1. A main paper feed roller which is rotated by receiving a rotational driving force of a motor, and first and second main paper feed rollers which are rotatably supported in parallel with and urged by the main paper feed roller. A paper feed mechanism having a pressure roller, wherein a first pressure roller and a second pressure roller are connected to each other by a rotation transmission means. 2. The rotation transmission means comprises gears fixed to the first and second pressure roller sides, respectively, and an idle gear interposed between these gears. The paper feed mechanism of the printer described in 1. 3. The rotation transmission means comprises a pulley fixed to each of the first and second pressure rollers, and a toothed belt wound between the pulleys. The paper feeding mechanism of the printer according to claim 1. 4. The rotation transmitting means comprises gears fixed to the first and second pressure roller sides, respectively, and a chain wound between these gears. The paper feed mechanism of the printer described in 1.