JPH0474664A - Sheet feeding mechanism - Google Patents

Abstract

PURPOSE:To ensure stable sheet feed by allowing pressure to be applied by a spring attached to a holding plate fixed across right and left side frames and holding paired rollers at the front and rear on which a belt is stretched, in a freely rotatable manner, on each of roller arms installed on a connecting rod provided along a platen. CONSTITUTION:The cam part of a release arm 8 unlocks the cam part of the arm 8 by manipulation of the release bar 9, and a roller arm 4 is pushed up to a platen 11 side by the elastic force of a spring 6. Subsequently, a printing sheet is inserted under pressure into a space between a belt 2 stretched across paired rollers 3 which are axially supported by the roller arm 4 and the platen 11. If the platen 11 rotates, a friction force generates between the platen 11 and the printing sheet 12 and the sheet is fed. In addition, a friction force generates between the printing sheet 12 and the belt 2, resulting in the rotation of the belt 2 following the sheet feed process.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a paper feed mechanism, and particularly to a paper feed mechanism for a serial printer that uses paper without a feeding hole.

[Conventional technology]

Conventionally, this type of paper feeding mechanism usually has a structure in which rollers arranged in the front and rear rows are pressed against the platen by springs, and the paper for printing is inserted between the platen and the rollers in the front and rear rows. The paper is then fed by the frictional force generated between the platen and the paper when it rotates.

[Invention or problem to be solved]

The conventional paper feeding mechanism described above has a structure in which a plurality of rollers in the former and rear rows are pressed against the platen by the force of a spring, so the contact form between the platen and the rollers is such that the cylinders are pressed parallel to each other. In this way, a plurality of line contacts are formed in each of the front row and the rear row.

Therefore, the generated frictional force tends to become unstable. Also, the paper that has passed through the rollers in the rear row does not advance along the platen surface.
It advances in the tangential direction of the platen in the rear row roller section. Therefore, due to the difference in the stiffness of the printing line, the timing at which the paper is bitten by the rollers in the front row changes,
There is a drawback that the edge of the printing paper tends to change the distance to the first printing position.

[Means to solve the problem]

The paper feed mechanism of the present invention is a paper feed mechanism for a serial printer that uses paper without feeding holes, and includes a plurality of roller arms that hold a pair of front and rear rollers and are attached to a connecting rod provided along a platen, and a plurality of roller arms that hold a pair of front and rear rollers and are attached to a connecting rod provided along a platen. a belt stretched across the rollers, at least one spring fixed at one end to the frame system and the other end fixed to one of the connecting rod and the roller arm to press the belt surface against the platen, and the connecting a switching shaft rotatably provided in the frame system parallel to the rod; a plurality of release arms having one rod fixed to the switching shaft and the other end rotatably holding the connecting rod; and a release lever having a cam that engages with the release arm and swings the connecting rod.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a perspective view of one embodiment of the present invention, in which the platen is abstracted. A pair of front and rear rollers 3 are rotatably held at both ends by a roller arm 4, and a belt 2 is stretched across the pair of front and rear rollers 3. A plurality of roller arms 4 each having a belt 2 stretched around a roller 3 are arranged along the longitudinal direction of a platen (not shown), and all the roller arms 4 are rotatably attached to a connecting rod 5. One end of the plurality of springs 6 is fixed to a retaining plate 7 passed between side frames (not shown).
The other ends are each fixed to a connecting rod 5, and are provided so that a force acts in a direction that presses the pair of front and rear rollers 3 and belt 2 against the platen via the roller arm 4. The switching shaft 13 is rotatably held at both ends by the side frame, and all the release arms 8 are arranged and fixed in the same phase. The swinging end of the release arm 8 is engaged with the connecting rod 5, and when the swinging end is lowered, the roller arm 4 having the belt 2 and the roller 3 is separated from the platen against the pressing force of the spring 6. . The release lever 9 has its center of rotation on the side frame, and has a cam portion at the contact portion with the release arm 8. When the release lever 9 is operated, the cam portion acts to cause the release arm 8 to swing. perform a moving action.

2 is a side view of FIG. 1, and FIG. 2(a) shows the state in which the belt 2 is separated from the platen 11, and FIG. 2(b) shows the state in which the belt 2 is connected to the platen 11 via the printing paper 12. Indicates a pressed state.

By operating the release lever 9 in the state shown in FIG. 2(a), the cam portion of the release lever 9 moves to the release arm 8.
2(b), the roller arm 4 is pushed up towards the platen 11 by the elastic force of the spring 6.

Therefore, the printing paper 12 is sandwiched under pressure between the belt 2 stretched across the pair of rollers 3 rotatably supported by the roller arm 4 and the platen 11. Platen 11
When the platen 11 rotates, a frictional force is generated between the platen 11 and the printing paper 12, and the paper is fed. Furthermore, printing paper 12
Frictional force is also generated between the belt 2 and the belt 2, and the belt 2 rotates as the paper is fed.

〔Effect of the invention〕

As explained above, the present invention has a structure in which pressure is applied by a spring attached to a holding plate fixed across the left and right side frames, and a plurality of roller arms attached to a connecting rod provided along a platen. By rotatably holding a pair of front and rear rollers with belts attached to each roller, the belts attached to these rollers and the platen come into close contact with each other, and the printing paper and the platen come into surface contact. Therefore, a stable frictional force is obtained between the platen, the paper, and the belt, which has the effect of stably feeding the paper. Furthermore, the distance from the printing paper terminal to the first printing position is
This has the effect of eliminating the problem of variations due to differences in stiffness of printing paper.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of one embodiment of the present invention, and FIG. 2 is a side view of FIG. 1. DESCRIPTION OF SYMBOLS 1... Print head, 2... Belt, 3... Roller, 4... Roller arm, 5... Connecting rod, 6... Spring, 7... Holding plate, 8... release arm,
9...Release lever, 10. ...paper guide,
11...platen,]2...printing paper, 13...
switching shaft.

Claims (1)

[Claims] In the paper feed mechanism of a serial printer that uses paper without a feeding hole, a plurality of roller arms holding a pair of front and rear rollers are attached to a connecting rod provided along a platen, and a roller arm stretched across the pair of rollers. a belt; at least one spring fixed at one end to the frame system and at the other end to one of the connecting rod and roller arm to press the belt surface against the platen; and a frame system parallel to the connecting rod; a switching shaft rotatably provided on the switching shaft; a plurality of release arms having one rod fixed to the switching shaft and the other end rotatably holding the connecting rod; and a release lever having a cam that swings the connecting rod.