JPS59198172A - Opening and closing mechanism for friction roller and pressure sheet in printer - Google Patents

Abstract

PURPOSE:To provide the titled mechanism for preventing a paper from sagging at a printing part by a simple construction, wherein a pressure sheet can be opened and closed by a change-over lever for opening and closing a friction roller. CONSTITUTION:At the time of fitting a paper, when the change-over lever 7 is turned to the solid-line position, a cam 5 is separated from a leaf spring 4, and the friction roller 2 is pressed against a platen 1. Simultaneously, a reinforcing plate 12 for the pressure sheet 10 is turned counterclockwise by the cam 5, and the sheet 10 is separated from the platen 1. In this condition, the platen 1 is driven to rotate, the paper is inserted between the platen 1 and the friction roller 2, and the paper is fed out to the side of a printing part. After feeding out the paper, perforations of the paper are engaged to pins, and the paper is fitted to the platen 1 so that it does not sag. After fitting the paper, the lever 7 is turned to the two-dotted line position, and the leaf spring 4 is pressed by the cam 5, whereby the roller 2 is separated from the platen 1. The reinforcing plate 12 is turned clockwise, and the paper is pressed against the platen 1 by the sheet 10, resulting in a printing condition.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention relates to an opening/closing mechanism for a friction roller and a thin pressure plate in a printing apparatus.

(Background of the Invention) In order to prevent paper from sagging in the printing area of the platen, a printing device is provided with a thin pressure plate in pressure contact with the lower part of the platen near the printing area. Paper is used. The cut sheet is fed by a friction roller disposed so as to be in pressure contact with a portion almost directly below the platen, in cooperation with the platen. The continuous paper is forcibly fed by a bin tractor that engages perforations provided at both ends of the continuous paper. When using a bin tractor, some are equipped with friction rollers and some are not, and some are equipped with friction rollers, while others are used and some are not.

When using a tension type bin tractor with a friction roller, if the friction roller is not released from the platen when printing continuous paper, slack in the paper or excessive paper tension will accumulate, leading to paper jams. . Therefore, printing devices equipped with a friction roller are generally equipped with an opening/closing mechanism for the friction roller.

On the other hand, the pressure thin plate has the disadvantage that paper cannot be loaded smoothly because most printing devices are fixed. In particular, it is very difficult to insert paper from below the platen. Some printing devices are capable of opening and closing the thin pressure plate, but this structure has a dedicated switching lever or is linked to a head gap adjustment lever, making the structure very complicated. It had the disadvantage of becoming

(Object of the Invention) An object of the present invention is to provide a friction roller and pressure thin plate opening/closing mechanism in a printing device that has a very simple structure and can open and close the pressure thin plate using a switching lever for opening and closing the friction roller. .

(Example of the invention) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

A friction roller 2 is disposed almost directly below the platen 1, which is driven by a drive motor (not shown). The friction roller 2 has one end connected to the fixed part 3 of the device.
It is rotatably supported by the other end of a leaf spring 4 fixed to the platen 1, and is pressed against the platen l by the biasing force of the leaf spring 4. A cam shaft 6 to which a cam 5 is fixed is rotatably supported by a side frame (not shown) of the device above the leaf spring 4.

A switching lever 7 is fixed to one end of the camshaft 6.

The switching lever 7 has an arc-shaped long groove 7 centered on the camshaft 6.
a is formed, and a stopper 8 fixed to the side frame of the device is inserted into this long groove 7a. Here, the long groove 7a
The position of the left end of the length a7a is set so that the cam 5 separates from the leaf spring 4 when the switching lever 7 is moved to the position shown by the solid line so that the left end abuts the stopper 8.

Furthermore, when the switching lever 7 is moved to the position shown by the two-dot chain line so that the right end of the long groove 7a contacts the stopper 8, a line connecting the apex of the cam 5 and the center of the cam shaft 6 comes into contact with the cam of the leaf spring 5. The right end position of the long groove 7a is set so that the cam 5 can move slightly beyond the position perpendicular to the plane.

In addition, a thin pressure plate 1 is provided between the printing part 1a of the platen 1 and the friction roller 2 in a portion closer to the printing part la.
The upper end portion of the pressure thin plate 10 is arranged, and the lower end of the pressure thin plate 10 is fixed to a pressure thin plate reinforcing plate 12. Bent portions 12a at both ends of the pressure thin reinforcing plate 12 are rotatably supported by the support shaft 11, and the ends extend onto the upper surface of the cam 5. Further, one end of a spring 13 is hung on the bent portion 12a of the pressure thin reinforcing plate 12 so that the pressure thin plate 10 comes into pressure contact with the bent portion 12a, and the other end of the spring 13 is hung on a spring hook 14 fixed to the fixing part 3. It is being

Next, the effect will be explained. When loading paper, the switching lever 7 is rotated to the position shown by the solid line. This causes cam 5
is separated from the leaf spring 4, and the friction roller 2 is separated from the leaf spring 4.
It is pressed against the platen 1 with the urging force of . At the same time, cam 5
1. As a result, the pressure thin plate reinforcing plate 12 is rotated counterclockwise in 5-1 directions about the support shaft 11, and the pressure thin plate 10 is rotated around the support shaft 11 in the counterclockwise direction.
move away from In this state, the switching lever 7 maintains the state shown by the solid line by setting the biasing force of the leaf spring 4 to be larger than the biasing force that causes the spring 13 to rotate the cam 5. In this state, when the platen 1 is driven to rotate and a sheet is inserted between the platen 1 and the friction roller 2, the sheet is sent to the printing section 11111 by the rotation of the platen 1. After feeding the paper a certain number of needles, the perforations formed at both ends of the paper are engaged with the bins of a bin tractor (not shown) disposed behind the platen 1, and then the paper is moved so that there is no slack in the paper. Attach the platen.

After loading the paper, when the switching lever 7 is rotated to the position shown by the two-dot chain line, the leaf spring 4 is pressed by the cam 5, and the friction roller 2 is separated from the platen 1. Also at the same time
Since the cam 5 separates from the pressure thin plate reinforcing plate 12, the pressure reinforcing plate 12 is pushed against the support shaft 11 by the biasing force of the spring 13.
The thin pressure plate O presses the paper against the platen 1. This brings the paper into a printing state, and the thin pressure plate 10 provides the paper with appropriate tension. In this state, as mentioned above, the line connecting the apex of the cam 5 and the center of the cam shaft 6 is slightly over the cam contact surface of the leaf spring 5 (the vertical position), so the cam 5 is moving. , the biasing force of the leaf spring 4 acts to rotate the cam 5 counterclockwise, the right end of the long groove 7a is pressed against the stopper 8, and the switching lever 7 maintains the state shown by the two-dot chain line.

In this way, the pressure thin plate lO is controlled by the switching lever 7.
Since it can be opened, it is very easy to load paper when inserting the paper from behind, below, or above the platen 1. In particular, when inserting paper from below or above the platen (front insertion), it is very difficult if the thin pressure plate 10 remains closed, so the effect of being able to open the thin pressure plate 10 is significant. Furthermore, when using a tension type bin tractor, when printing on continuous paper, the switching lever 7 can be operated to open the friction roller 2 and close the thin pressure plate 1o. It can also remove jams, etc.

In the above embodiment, in order to maintain the switching lever 7 in the printing state position, the switching lever 7 is provided with a long groove 7a, a stopper 8 is disposed in this long groove 7a, and the switching click is performed by the action of the leaf spring 4. Although a mechanism has been constructed, a known click spring mechanism may be separately attached to the switching lever 7.

Further, although the leaf spring 4 and the pressure thin reinforcing plate 2 are operated by one cam 5, they may be operated by separate cams.

(Effects of the Invention) As is clear from the above description, according to the present invention, the thin pressure plate can be opened and closed by operating the switching lever that opens and closes the friction roller, making it very easy to load paper. Furthermore, since it has a very simple structure in which one switching lever i opens and closes the friction roller and the thin pressure plate, the cost of the device does not increase.

[Brief explanation of the drawing]

The figure is a mechanical diagram of main parts showing one embodiment of the present invention. ]...Platen, 2...Friction roller, 4...Flat spring, 5...Cam, 7
...Switching lever, 10...Pressure thin plate, 12...Pressure thin plate reinforcing plate, 13...
Spring. 9-

Claims (1)

[Claims] In a printing device having a friction roller and a pressure thin plate disposed so as to be in pressure contact with a platen, a plate spring is provided to support the friction roller so as to be in pressure contact with the platen, and a leaf spring is provided to hold the pressure thin plate and to be freely rotatable. a pressure thin plate reinforcing plate; a spring biasing the pressure thin plate so as to come into pressure contact with the platen; and a plate spring and the pressure thin plate reinforcing plate so as to alternately press the friction roller and the pressure thin plate against the platen. An opening/closing mechanism for a friction roller and a thin pressure plate in a printing device, consisting of a cam that engages and disengages from the cam, and a switching lever that rotates the cam.