JP2674278B2 - Thermal printer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a thermal printer that prints on recording paper using a thermal head.

[Conventional technology]

FIG. 4 is a schematic side view showing a conventional thermal printer disclosed in, for example, Japanese Patent Laid-Open No. Sho 60-13574. In FIG. 4, (1) is a thermal head, which is movable to a position shown by a broken line (1A). is there. (2) is an ink sheet on which Y, M, and C colors are sequentially applied, and (3) is an ink sheet (2)
Supply roll, (4) also take-up roll, (5) recording paper, (6) platen roller for closely contacting the ink sheet (2) and recording paper (5) against the thermal head (1) Thus, it can be driven and rotated in the direction of arrow A, and the opposite direction can be separated from the drive source by a clutch or the like and driven and rotated by the movement of the recording paper (5). (7) is a pinch roller that presses the recording paper (5) against the platen roller (6), and (8) is a transport unit that can move to a position indicated by a broken line (8A). (9) is a guide that movably supports the transfer unit (8), (10) is a transfer wire that is connected to the transfer unit (8) and moves, and (11) is a transfer wire (10).
With a drive pulley for driving, the transport unit (8) is reciprocated by a pulse motor or the like. (12) and (13) are intermediate pulleys around which the transfer wire (10) is stretched, and (14) is a clamper mounted on the transfer unit (8), which is rotatable around a pin (15) for transfer. The tip of the recording paper (5) is held between the unit (8) and the unit (8) by a spring (16).

Next, the operation will be described. The leading edge of the recording paper (5) is clamped by the clamper (14) in the transport unit (8). Next, the ink sheet (2) and the recording paper (5) are pressed against the platen roller (6) by the thermal head (1), and in this state, the transfer unit (8) is moved by the transfer wire (10) from the position of the broken line (8A). While moving in the direction of arrow B, the thermal head (1) is heated to melt the ink of the ink sheet (2) and transfer it to the recording paper (5), and the printing of the first color (Y, yellow) is completed. Next, the thermal head (1) is moved to the position of the broken line (1A), the platen roller (6) is rotated in the direction of arrow A, and the transport unit (14) is moved in the direction of arrow C. 5) receives the conveying force of the platen roller (6) by the pinch roller (7) and is returned to a predetermined position. Then, the thermal head (1) is pressed against the platen roller (6) again, the transport unit (8) is moved in the direction of arrow B, and the second color (M
-Magenta) printing, and similarly, printing of the third color (C / cyan) is performed.

[Problems to be solved by the invention]

Since the conventional thermal printer is configured as described above, it is necessary to return the recording paper (5) to the initial position every time one color is printed. Therefore, the trailing end of the recording paper (5) has a pinch roller ( 7) is not allowed, and accordingly the length from the pressing position of the platen roller (6) to the thermal head (1) to the pressing position to the pinch roller (7) (with the length indicated by L in FIG. 4). (Actually about 20 mm to 30 mm)
Has a problem that it is in an unprintable range.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain a thermal printer that can reliably print to the trailing edge of a recording sheet.

[Means for solving the problem]

The thermal printer according to the present invention movably supports the position of the pinch roller pressed against the platen roller, and also provides recording paper guide means between the platen roller and the transport unit to guide the trailing end of the recording paper to a predetermined position. It is something that is done.

[Action]

According to the present invention, even if the trailing edge of the recording sheet is printed until it comes off the pinch roller, the trailing edge of the recording sheet is held at the predetermined position by the guiding means, and when the recording sheet is returned, the pinch roller is moved to the trailing edge of the recording sheet. By moving to a position where it can easily enter, it is guided again between the pinch roller and the platen roller, and a reliable return operation of the recording paper is performed, so printing can be performed up to the trailing edge of the recording paper.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3, (2) to
Since (5), (9) to (13), (15) and (16) are the same as the conventional ones, the same reference numerals are given and the description thereof will be omitted. (20) is a fan-shaped gear that is rotatably supported around the shaft (21a) of the platen roller (21), and is rotated by the drive gear (22) to rotatably hold the pinch roller (23). ing. The fan-shaped gear (20) has a pinch roller (23) at a first position (opposite the guide roller (28) with respect to a position where the thermal head (25) faces the outer peripheral surface of the platen roller (21) ( It functions as a pinch roller moving means for reciprocating between a position shown by a solid line in FIG. 1) and a second position near the facing position of the thermal head (25) (a position shown by an imaginary line in FIG. 1). (24) is a pinch roller (23)
Spring to press the platen roller (21), (2
5) is a thermal head, and the platen roller (2
1) and the platen roller (2
Far from 1). (26) is a transport unit which is supported by a guide (9) and reciprocates by a transfer wire (10). Reference numeral (27) is a clamper mounted by a transport unit (26), which is rotatable around a pin (15), and the front end of the recording paper (5) is springed (16) between the clamp unit and the transport unit (26). To pinch. (28) is the platen roller (21)
A guide roller arranged between the transport unit and the transport unit (26),
It always rotates in the same direction as the platen roller (21).
(29) is a pinch roller of the guide roller (28). The transport unit (26) and the clamper (27) are partially cut out so that the guide roller (28) and the pinch roller (29) do not interfere with each other. The solenoid (30) controls the position of the rod (31) by NO and OFF to open and close the clamper (27). (32) is a spring that biases the rod (31) in a protruding direction when the solenoid (30) is OFF. The platen roller (21) has a structure that can be rotationally driven in both directions via a torque limiter.

Next, the operation of three-color overprinting by this apparatus will be described. In FIG. 1, the recording paper (5) delivered from a paper supply unit (not shown) is guided between the platen roller (21) and the pinch roller (23) at the first position. Move the thermal head (25) away from you and move the platen roller (21) to the arrow A
If it is rotated in the direction, the recording paper (5) is conveyed. Further, rotate the gear (20) in the direction of arrow B to move the pinch roller (2
3) is moved to a second position indicated by an imaginary line in FIG. 1 and the leading end of the recording paper (5) is guided by the guide roller (28) and the clamper (2
7) Bring it around. At this time, turn off the solenoid (30)
When the rod (31) is projected by the spring (32) and the clamper (27) is opened, the recording paper (5) is conveyed by the platen roller (21) and the guide roller (28), and the leading end of the clamper (27) 27) Enter below. When the platen roller (21) stops rotating, the solenoid (30) is turned on and the rod (31) is attracted, the spring (16) causes the leading edge of the recording paper (5) to move to the transport unit (26) and clamper. It is securely sandwiched between (27). Next, 1 of ink sheet (2)
While performing the indexing operation for the color and Y (yellow), the gear (20) is rotated in the opposite direction to return the pinch roller (23) to the original first position, and the thermal head (25) is moved to the platen roller (21). ). Drive pulley (11) in this state
When the thermal head (25) is heated according to the image signal while driving the transport unit (26) in the direction of arrow C by driving the transfer wire (10), the ink of the ink sheet (2) melts and the recording paper It is transferred to (5). In this way, printing is performed for a predetermined length. At this time, there is no problem even if printing / conveying is performed until the trailing edge of the recording paper (5) comes off the platen roller (21) and pinch roller (23). Absent. Now, as shown in FIG. 2, when the printing of the first color is completed, the trailing edge of the recording paper (5) is held between the guide roller (28) and the pinch roller (29). There is. Here, after the thermal head (25) is moved away from the platen roller (21), the drive gear (22) rotates the gear (20) in the direction of arrow D to move the pinch roller (23) to the position shown in FIG. Move to position 2. Now, in FIG. 3, the platen roller (21) is rotated in the direction of arrow E and the drive pulley (11) is rotated in the reverse direction to move the transport unit (26) in the direction of arrow F. At this time, since the guide roller (28) is rotating in the same direction as the platen roller (21), the trailing edge of the recording paper (5) is reliably guided between the platen roller (21) and the pinch roller (23). Then, the recording paper (5) is quickly returned to a predetermined position. After the return operation is completed, the pinch roller (23) is returned to the original first position again, and the second color / M (magenta) indexing operation of the ink sheet (2) is performed, and the same operation as the first color is shown in FIG. The second color and M are printed from the state. Similarly, the third color / C (cyan) is printed, and a series of color printing steps are completed. Therefore, it is possible to reliably print to the trailing edge of the recording paper (5).

In the above embodiment, the guide roller (2
8) and a pinch roller (29) were used, but not limited to this. Further, although the transfer unit (26) is moved by the transfer wire (10), there is no problem if it is moved by a timing belt or the like.

〔The invention's effect〕

As described above, according to the present invention, since the pinch roller is provided so as to be movable on the outer periphery of the platen roller and the guide means is provided between the platen roller and the transport unit, the trailing edge of the recording paper is the platen roller and the pinch roller. Even if it is separated from, the trailing edge can be guided again between the platen roller and the pinch roller, and the recording paper can be surely returned, so that there is an effect that a thermal printer capable of printing up to the trailing edge of the recording paper can be obtained.

[Brief description of the drawings]

1 is a schematic side view showing a thermal printer according to an embodiment of the present invention, FIGS. 2 and 3 are schematic side views for explaining the operation of FIG. 1, and FIG. 4 is a schematic view showing a conventional thermal printer. It is a side view. In the figure, (5) is a recording paper, (20) is a gear, (21) is a platen roller, (23) is a pinch roller, (25) is a thermal head, (26) is a transport unit, (27) is a clamper, (28) is a guide roller, and (29) is a pinch roller. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

(57) [Claims] 1. A thermal head that generates heat in response to an image signal, a platen roller that faces the thermal head, recording paper that passes between the platen roller and the thermal head, and a leading edge of the recording paper. In a thermal printer having a conveying unit that reciprocates while holding a sheet, a guide unit that guides the recording sheet to a predetermined position between the platen roller and the conveying unit, and the recording sheet on the platen roller. A pinch roller that presses and guides the recording paper to the outer peripheral surface of the platen roller, and a pinch roller on the side opposite to the guide unit with respect to the position where the thermal head faces the outer peripheral surface of the platen roller. A pinch roller moving means for reciprocating between a first position and a second position near the facing position of the thermal head, Further, the second position is such that when the recording paper is conveyed in the same direction as the printing operation, the leading end of the recording paper is inserted between the platen roller and the pinch roller through the guide means into the conveying means. Further, the thermal printer is characterized in that, at the time of returning operation of the recording paper, the rear end portion of the recording paper is at a position where it is reinserted from the guide means between the platen roller and the pinch roller.