JPH02219661A - Thermal printer - Google Patents

Abstract

PURPOSE:To obtain a thermal printer having no printing slippage by a method wherein a clamper grasping an edge part of recording paper bridged between a pair of second pulleys tensing a timing belt by development and the timing belt is established. CONSTITUTION:A running velocity of a timing belt 3 is so constructed as to be equal to or slightly faster than a peripheral speed of a platen 1. When a recording paper 6 is sent from a paper feed mechanism 15 and its top is inserted between claws of a clamper 9, a clamper closing mechanism 16 is actuated to close the clamper 9. A top of the recording paper 6 is grasped, and the platen 1 starts rotation. Then, the clamper 9 reaches a paper detecting sensor 14 via a torque limiter 11, a first pulley 2, and the timing belt 3 and when the top of the recording paper 6 is detected, photographic printing is started. The clamper 9 is rotated around a second pulley 4 to reach a position of the clamper closing mechanism 16 again, a thermal head 8 sets up an ink sheet 7 to a following color. Consequently running irregularity of the recording paper to be generated when the clamped is rotated around the second pulley is absorbed, and a thermal printer having no slippage in photographic printing can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a recording paper feeding mechanism for a thermal printer.

[Conventional technology]

5 and 6 are a side view and a plan view of a main part of a paper feeding mechanism of a conventional thermal printer disclosed in, for example, Japanese Patent Application No. 62-147241. In the figure, (1) is a platen, (2) is a pair of first pulleys that are provided on both sides of the platen and rotates with the platen (υ), and (31 is a platen (around the circumference of υ) hung on the pulley (2) of the gil. A pair of timing belts running at the same speed as the speed, (4) (5+ is the timing belt (31)
This is the pulley. (6) is a sheet of recording paper, (7)
is an ink sheet, which supplies ink for thermal transfer, and after the ink is thermally transferred, is wound onto a take-up reel QG. +
81 is a thermal head that thermally transfers the ink on the ink sheet (7) to the recording paper (6) using an electric signal, and (9) is a timing belt (installed on a bridge (9a) installed between 31 and parallel to the platen (υ)). This is a clamper that grips the edge of the recording paper (6) and runs in synchronization with the timing belt (3).

A conventional thermal printer is constructed as described above, and its operation is such that recording paper (6) is first fed from a paper supply mechanism (not shown), and the leading edge of the recording paper (6) is fed to the platen (1). The clamper (9) passes between the
) to be grasped. Then, in response to an instruction to start printing, the thermal head (8) moves the recording paper (61 and ink sheet (7)
The platen (1) then starts rotating in the direction of the arrow (A1), and the ink sheet 1 is brought into contact with the ink sheet 1 by an electric signal sent to the thermal head (8).
7) is thermally transferred onto the recording paper (61).

At the same time, the timing belt (3) runs in the direction of the arrow, and conveys the leading edge of the recording paper (6) gripped by the clamper t9). When the clamper (9) passes through the second pulley (4) and the third pulley (5) and reaches the first pulley (2) again, the thermal head (8) does not separate from the platen (υ) and the clamper ( 91 passes between the platen (1) and the thermal head (8).At this time, the ink sheet (7) is set up for the next color.Then, the clamper (
9] reaches the printing start position again, the thermal head (8
) is brought into contact with the platen (υ) again and printing of the second color is carried out in the same order as above.

The above printing operation is repeated for the third or fourth color, and when a color print is completed, the recording paper (6) is separated from the clamper (9) and discharged.

[Problem to be solved by the invention]

In the conventional thermal printer as described above, the circumferential speed of the platen (L) and the running speed of the timing belt (31) are equal, but the recording paper (
The part that grips the second pulley (4) and the third pulley (51) is the pulley i41. ), which is gripped by the clamper (9), temporarily becomes faster than the peripheral speed of the platen (13) and pulls the recording paper '(6) in the running direction. This tensile force causes the recording paper (6) to travel faster. There were problems such as unevenness and misalignment of prints.

This invention was made to solve the above-mentioned problems, and an object of the present invention is to absorb the running unevenness of recording paper that occurs when a clamper rotates around a pulley, and to obtain a thermal printer that is free from printing misalignment.

[Means to solve the problem]

The thermal printer according to claim 1 of the present invention includes a platen that brings an ink sheet and a recording paper into close contact with each other and conveys the recording paper at a predetermined speed, and a pair of torque limiters that are provided on the shaft of the platen and that slip at a predetermined torque. , a pair of first pulleys connected to the shaft of the platen via a torque limiter, and a pair of pulleys that are hung on the first pulley and have a circumference longer than the recording paper that is constantly traveling at the same speed as or at the conveyance speed of the recording paper. The recording paper includes a timing belt, a pair of second pulleys that extend the timing belt, and a clamper that is installed between the timing belts and grips the edge of the recording paper.

The thermal printer according to claim 2 of the present invention includes a platen that brings an ink sheet and a recording paper into close contact with each other and conveys the recording paper at a predetermined speed, and a first pulley that is rotatably provided on both axes of the platen. A pair of timing belts having a circumference longer than the hung recording paper, a clamper installed between the timing belts to grip the edge of the recording paper, and a timing belt that is constantly moved at the same or faster speed as the recording paper conveyance speed. a pair of second pulleys that run and extend;
The second pulley is provided with a drive source that rotates the second pulley, and a torque limiter that is provided between the second pulley and slips at a predetermined torque.

[Effect]

In this invention, the torque limiter slips the difference between the running speed of the timing belt and the circumferential speed of the platen when it goes around the second pulley of the clamper that grips the recording paper.

〔Example〕

1 and 2 are a side view and a plan view of a main part of a thermal printer showing an embodiment according to claim 1 of the present invention. In the figure, (1] to (41, 161 to αG) are the same as those described in the conventional example.

(B) is a torque limiter disposed between the shaft of the platen (1) and the pulley (2) of the mt, and is a torque limiter (platen 11).
The rotational force of the first boot is transmitted to the platen (13).
If a torque difference of more than a predetermined value occurs between the pulley 12) and the first pulley 12), a slip occurs. (to) is a pinch roller, (2)
is a tension roller that holds the recording paper (61) after thermal transfer.
tension in the running direction of the timing belt 131. α
4 is a paper detection sensor (2) that detects the leading edge of the recording paper (61), which is a paper supply mechanism that separates and supplies the stacked recording paper (6) into - sheets, and α is supplied from the paper supply mechanism (g). αη is a clamper closing mechanism that causes the clamper (9) to grip the leading edge of the recorded recording paper +61, and αη is a clamper opening mechanism that releases the grip of the clamper (9) immediately before ejecting the recording paper (6) on which printing has been completed; , α9 is a paper guide that protects the recording paper (6) conveyed along the timing belt (31). In normal conditions, the running speed of the timing belt (3) is the same as or equal to the circumferential speed of the platen (1). Constructed a little faster.

The operation of the thermal printer configured as above will be explained. First, before starting the printing operation, use the clamper (9).
is located above the clamper closing mechanism (to), and when the recording paper (61) is fed from the paper supply mechanism (to) and its leading edge is inserted between the claws of the clamper (9), the clamper closing mechanism closes. The cAQ operates, closes the clamper (9), grips the leading edge of the recording paper (61), and the platen (1) starts rotating in the direction of the arrow.At this time, the thermal head (8) moves away from the platen (1). , the pinch roller 0 is separated from the tension roller (2), and the clamper (9), which grips the recording paper (6) through the gap, is rotated by the platen (υ) and the torque limiter υ% first pulley (2). ), the paper detecting sensor α runs through the timing belt (3).
Reach 4. Paper detection sensor α4 detects recording paper (61
When the tip of the thermal head (8) is detected, the thermal head (8) comes into contact with the platen (11) and printing starts.

Then, when the clamper (9) passes between the tension roller υ and the pinch roller (to), the pinch roller (to) pinches the recording paper (6) and comes into contact with the tension roller (2), which holds the recording paper (61) under tension. Ink sheet after thermal transfer (
7) Stabilizes the separation between the ink and the ink. The clamper (9) goes around the second pulley (4) and closes the clamper closing mechanism Q again.
When it reaches the position l, the thermal head (81 is the platen)
From step 1), the pinch roller 0 is separated from the tension roller (2), and the clamper (9) is passed between them, and at the same time, the ink sheet (7) is set up to the next color. After that, printing of the second color is started. Similarly, printing of the third color is performed to complete the color printing, and when the clamper (9) reaches the position of the clamper release mechanism αη, the clamper release mechanism Akebono releases the clamper (9) and the recording paper (6) Guide the tip of the paper toward the paper ejection direction. During this printing operation, when the clamper (9) grasping the leading edge of the recording paper (61) which is being thermally transferred revolves around the second pulley (4),
Since the trajectory of the clamper (9) passes outside the occlusal pitch circle of the second pulley (4) and the timing belt +31,
The running speed of clamper +91 increases temporarily, and tension is applied to the recording paper (6) between the platen (υ and clamper (9)).This tension is applied to the timing belt (clamper +9 of 31).
) is transmitted forward in the running direction and acts on the first pulley (2). Therefore, as the clamper +91 tries to become faster than the circumferential speed of the platen (1), a torque corresponding to the amount of torque applied to the torque limiter (b) is applied to the torque limiter (b), causing the timing belt (3) to slip. By loosening the clamper (91), the clamper (91) is maintained at the same peripheral speed as the platen (1), and uneven running of the recording paper (6) at the printing position is absorbed.

Also, the timing belt (3) is lower than the circumferential speed of the platen (13).
), the slip of the difference between the circumferential speed of the platen (1) and the running speed of the clamper (9) is always performed by the torque limiter 0, and the clamper (9)
When orbiting the second Boo January 41, the torque limiter (
By increasing the degree of slip (b), uneven running of the recording paper (6) is absorbed.

3 and 4 are a side view and a perspective view of a main part of a thermal printer showing an embodiment according to claim 2 of the present invention. In the figure, (13, 13), +41.

(6) to Q□ and (b) to α are the same as those explained in the embodiment of claim 1 above. (1) is the first pulley rotatably disposed on the shafts (1a) on both sides of the platen field, is the motor of the platen (fM which is the drive source of 17), and is the second pulley (41 The second motor is the driving source of It is configured to run at the same speed as or slightly faster than the circumferential speed of the platen (1).

The printing operation in the thermal printer having the above configuration is the same as that in the embodiment of claim 1, so the explanation thereof will be omitted.

During this printing operation, when the clamper (91) that grips the leading edge of the recording paper (6) that is being thermally transferred revolves around the second pulley (4), the running speed of the clamper (9) temporarily changes. Faster, platen tIJ and clamper [9]
Tension acts on the recording paper (6) between the two, but this tension causes the torque limiter to slip, slowing down the rotational speed of the second pulley (4), and keeping the clamper (91 at the same speed as the circumferential speed of the platen (υ). This absorbs uneven running of the recording paper (6) at the printing position.

Also, from the peripheral speed of the platen (13), the timing belt 13
] When the running speed of the platen (1) and the recording paper (61) is high, the clamper (
The running of the platen (9) is regulated to the circumferential speed of the platen (13).At this time, the difference from the original running speed of the timing belt (31) is absorbed by the slip of the torque limiter (■), and the clamper (9) is When going around Boo January 41, the degree of slip of the torque limiter O increases, so the recording paper (6
) running unevenness is absorbed.

〔Effect of the invention〕

As explained above, claim 1 of the present invention includes a timing belt that is hooked on a first pulley provided on both sides of the platen via a torque limiter and runs at a speed that is the same as or faster than the conveyance speed of the recording paper, and By providing a second pulley that stretches the belt and a clamper that is stretched between the timing belt and grips the edge of the recording paper, uneven running of the recording paper that occurs when the clamper rotates around the second pulley is eliminated. It is possible to obtain a thermal printer with no printing deviation.

As explained above, claim 2 of the present invention includes: a timing belt that is hooked on first pulleys rotatably provided on both sides of the platen and runs at a speed that is the same as or faster than the conveyance speed of the recording paper; and the timing belt. The second step is to expand
By comprising a torque limiter connected to the second pulley, a drive source that rotates the second pulley via the torque limiter, and a clamper that is installed between the timing belt and grips the edge of the recording paper, It is possible to obtain a thermal printer that absorbs the running unevenness of the recording paper that occurs when the clamper rotates around the second pulley and is free from printing misalignment.

[Brief explanation of the drawing]

1 and 2 are a side view and a plan view of a main part of a thermal printer showing an embodiment according to claim 1 of the present invention,
3 and 4 are a side view and a plan view of a main part of a thermal printer showing an embodiment according to claim 2 of the present invention,
FIG. 85 and FIG. 6 are a side view and a plan view of a main part of a paper feeding mechanism of a conventional thermal printer. In the figure, (13 is the platen, (2), the slope is the first pulley, (3) is the timing belt, (4) is the second pulley, (6) is the recording paper, (81 is the thermal head, (9 ) is clamper, gn,
1 is the torque limiter, and ρ is the second motor. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (2)

[Claims] (1) An ink sheet that supplies ink, a platen that brings the ink sheet and a sheet of recording paper into close contact and conveys the recording paper at a predetermined speed, and a pair of plates that are installed on the axis of the platen and that slip with a predetermined torque. a torque limiter, a pair of first pulleys connected to the platen through the torque limiter; a length longer than the length of the recording paper that is hung on the first pulley and always travels at the same or faster speed than the conveyance speed of the recording paper; A thermal printer comprising a pair of timing belts having a circumferential length, a pair of second pulleys that extend the timing belts, and a clamper that is installed between the timing belts and grips an end of the recording paper. . (2) An ink sheet that supplies ink, a platen that brings the ink sheet and sheet-shaped recording paper into close contact and conveys the recording paper at a predetermined speed, and a pair of ink sheets that are rotatably provided on the axis of the platen. a pair of timing belts that are hung on the first pulley and have a circumference longer than the length of the recording paper; a clamper that is installed between the timing belts and grips an end of the recording paper; and the timing belt. a pair of second pulleys that are always run and extended at the same or higher speed than the conveyance speed of the recording paper, a drive source that rotates this second pulley, and between this drive source and the second pulley. 1. A thermal printer comprising a torque limiter which is provided and slips at a predetermined torque.