WO2009101653A1

WO2009101653A1 - Thermal printer

Info

Publication number: WO2009101653A1
Application number: PCT/JP2008/000213
Authority: WO
Inventors: Takaaki Kase; Ichirou Furuki
Original assignee: Mitsubishi Electric Corporation
Priority date: 2008-02-13
Filing date: 2008-02-13
Publication date: 2009-08-20
Also published as: JPWO2009101653A1

Abstract

A thermal printer comprises a thermal head (2) which applies heat to an ink sheet 5 to print characters or image information on a recording paper (4), a platen roller (1) wherein a platen roller cored bar portion (1a) is rotationally supported and which supports the recording paper (4) and the ink sheet (5), guide portions (21d, 21e) of a head support member (21) which are arranged on both ends in the main scanning direction which is the printing direction of the thermal head (2), bearings (11, 12) arranged on both ends in the main scanning direction of the platen roller (1), a tension spring (22) for energizing the guide portions (21d, 21e) toward the bearings (11, 12) when the thermal head (2) and the platen roller (1) are pressurized into contact, a fixed flange (41) and a movable flange (43) which are rotatably supported on both ends of the platen roller (1) and are in contact with the external faces of the bearings (11, 12), and a compression spring (44) for energizing the movable flange (43) toward the center in the main scanning direction of the platen roller (1).

Description

Thermal printer

The present invention relates to a thermal printer that performs printing on photographic paper such as thermal paper using a thermal head.

The thermal printer places a roll of photographic printing paper and recording paper between the thermal head and the platen roller, and presses the thermal head against the platen roller to support the printing paper and the recording paper. Thereafter, the heating element formed on the thermal head is heated while moving the photographic paper and the recording paper with a conveying roller or the like, whereby the dye of the photographic paper is transferred to the recording paper and printing is performed.

In the case of color printing, the color of the photographic paper is sequentially changed, and the recording paper is reciprocated between the platen roller and the thermal head a plurality of times. A thermal printer that performs color printing generally performs printing using three color printing papers of Y (yellow), M (magenta), and C (cyan). First, the Y color image is transferred using the photographic paper coated with the Y color, and after the completion, the press contact between the thermal head and the platen roller is released, the recording paper is returned to the recording start position, and the photographic paper is moved to the M position. The sheet is fed to the position where the color is applied, and the platen roller and the thermal head are pressed again to transfer the M-color image onto the recording paper. Thereafter, the C color is similarly transferred, and a color image is formed on the recording paper. Note that the transfer order of the Y, M, and C colors is not limited to the above, and may be different.

In the above-described color printing, it is necessary to perform positioning so that the heating element formed on the thermal head is located in the nip range that is the contact range between the thermal head and the platen roller. That is, when the thermal head and the platen roller are in pressure contact, if the heating element formed on the thermal head deviates from the nip range, the heat energy from the heating element cannot be transmitted to the photographic paper, resulting in a transfer failure.

As a countermeasure, in Patent Document 1, a support plate and a leaf spring are arranged on both sides of the thermal head, and the platen roller is positioned by urging the platen roller shaft using the support plate and the leaf spring. The heating element row is configured to be correctly positioned in the nip range.

JP 11-268375 A

Since the conventional thermal printer is configured as described above, it is possible to position the heating element row on the thermal head within the nip range (sub-scanning direction), but the recording paper width direction (main scanning direction) ) Cannot be performed, and when three colors of Y, M, and C are transferred in a frame sequential manner, there is a problem that each color is color-shifted. That is, after the Y color is transferred, the recording paper is returned to the recording start position, and the photographic paper is sent to the position where the M color is applied, and the platen roller and the thermal head are pressed against each other again through the photographic paper and the recording paper. In such a case, when a deviation occurs in the main scanning direction of the thermal head, the position of the heating element in the main scanning direction with respect to the recording paper is displaced, resulting in a color shift.

The present invention has been made to solve the above-described problems. The thermal head is positioned in the main scanning direction and the sub-scanning direction with respect to the platen roller with a simple configuration, thereby improving the image quality and reducing the size and size of the thermal head. The purpose is to obtain a thermal printer that realizes the cost.

In the thermal printer according to the present invention, a thermal head that prints characters and image information on recording paper by applying heat to the photographic paper, and a shaft portion are rotatably supported to support the recording paper and the photographic paper. A platen roller, guide members provided at both ends in the main scanning direction which is the printing direction of the thermal head, positioning members provided at both ends in the main scanning direction of the platen roller, the thermal head, A first urging means for urging the guide member toward the positioning member when the platen roller is in pressure contact; and two urging members that are pivotally supported at both ends of the platen roller and abut against the outer surface of the guide member. A flange member and second biasing means for biasing one of the flange members toward the center position in the main scanning direction of the platen roller are provided.

According to this invention, when the thermal head and the platen rotor are in pressure contact, the guide members provided at both ends in the main scanning direction of the thermal head are positioned on the positioning member side provided at both ends in the main scanning direction of the platen roller. A first urging means that urges the platen roller, two flange members that are pivotally supported at both ends of the platen roller and abutting against the outer surface of the guide member, and one of the flange members is positioned at the center position in the main scanning direction of the platen roller. Since the second urging means that urges toward the platen is provided, the thermal head can be accurately positioned with respect to the platen roller, and an image free from transfer defects and color misregistration can be output.

It is a side view which shows the structure of the thermal printer which concerns on Embodiment 1 of this invention. It is a side view which shows the structure of the positioning mechanism of the thermal printer which concerns on Embodiment 1 of this invention. It is a side view which shows the structure of the positioning mechanism of the thermal printer which concerns on Embodiment 1 of this invention. It is a figure which shows the structure of the positioning mechanism of the thermal printer which concerns on Embodiment 1 of this invention. It is a figure which shows the structure of the positioning mechanism of the thermal printer which concerns on Embodiment 1 of this invention. FIG. 3 is a sectional view taken along line cc of FIG. FIG. 4 is a sectional view taken along the line dd in FIG. 3.

Hereinafter, in order to describe the present invention in more detail, the best mode for carrying out the present invention will be described with reference to the accompanying drawings.
Embodiment 1 FIG.
FIG. 1 is a side view showing a configuration of a thermal printer according to Embodiment 1 of the present invention.
The thermal printer includes a platen roller 1 that is rotationally driven by a drive motor (not shown) and the like, and a thermal head 2 that is disposed to face the platen roller 1. A plurality of heating elements 3 are arranged on the surface of the thermal head 2 on the side of the platen roller 1 and pressed against the outer periphery of the platen roller 1 with a predetermined pressure during printing. A recording paper 4 and an ink sheet (printing paper) 5 are sandwiched between the platen roller 1 and the thermal head 2, and the recording paper 4 is pulled out from the roll-shaped recording paper roll 4 a and is cut by a cutter 6 to a predetermined length. Disconnected.

The ink sheet 5 is a sheet on which Y (yellow), M (magenta), and C (cyan) inks are applied in the surface order, and is stored in a roll shape in the ink sheet supply roll 5a. The ink sheet is wound around the ink sheet winding roll 5b. With respect to the platen roller 1, on the upstream side and downstream side in the discharge direction of the recording paper 4,

upstream transport rollers

7a and 7b and

downstream transport rollers

8a and 8b for transporting the recording paper 4, and transport of the ink sheet 5, respectively. An upstream guide shaft 9 and a downstream guide shaft 10 are disposed. Hereinafter, the width direction of the recording paper 4 is referred to as a main scanning direction, and the discharge direction of the recording paper 4 is referred to as a sub-scanning direction.

2 and 3 are side views showing the configuration of the positioning mechanism of the thermal printer according to Embodiment 1 of the present invention. FIG. 2 shows a state in which the thermal head is pressed against the platen roller, and FIG. 3 shows the thermal head. Is shown in a state of being separated from the platen roller. 4 and 5 are diagrams showing the configuration of the positioning mechanism of the thermal printer according to the present invention. FIG. 4 is a view as seen from the direction of arrow a in FIG. 2, and FIG. 5 is from the direction of arrow b in FIG. FIG. 6 is a cross-sectional view taken along the line cc of FIG. 2, and FIG. 7 is a cross-sectional view taken along the line dd of FIG.

The platen roller 1 has a platen roller cored bar (shaft) 1a at the center, and both ends of the platen roller cored bar 1a are fitted into bearings (positioning members) 11 and 12 which are substantially cylindrical positioning members. Inserted. Furthermore, substantially

cylindrical bearings

13 and 14 are fitted to the side plate 51 of the thermal printer, respectively, and the platen roller 1 is inserted into the

bearings

13 and 14 by inserting both ends of the platen roller cored portion 1a. It is supported rotatably.

The thermal head 2 is held at both ends by a head support member 21. The head support member 21 includes

support surfaces

21a and 21b, cutout portions 21c, guide portions (guide members) 21d and 21e, and locking pieces 21f. The

support surfaces

21a and 21b hold the side portion of the thermal head 2 from both sides. The notch 21c is provided at the tip of the

support surfaces

21a and 21b extending in the sub-scanning direction. The notch 21c has a substantially U shape, and is supported by being fitted to

pins

52a and 52b protruding from the side plate 51 of the thermal printer. The

guide portions

21d and 21e extend in a direction substantially orthogonal to the sub-scanning direction, and abut on the outer rings of the

bearings

11 and 12 into which the platen roller core metal portion 1a is inserted.

The locking piece 21f has a locking portion 21g that protrudes in the vicinity of the notch portion 21c and that can lock one end of a tension spring (first biasing means) 22 that is a biasing means. The tension spring 22 locked to the locking portion 21g is stretched by being locked to the

pins

53a and 53b provided on the side plate 51 at the other end. The tension spring 22 urges the head support member 21 in the direction of arrow A shown in FIGS. 2 and 3, and the outer rings of the

bearings

11 and 12 into which the guide portions 21d and 21e and the platen roller core metal portion 1a are inserted and inserted. Abut. Thereby, the thermal head 2 can be positioned in the sub-scanning direction with respect to the platen roller 1.

On the upper surface of the head support member 21, a pressing means 31 and a pressing spring 32 for pressing the head support member 21 in the direction of arrow B shown in FIG. When the pressing means 31 is pressed in the direction of arrow B by an urging means (not shown), the thermal head 2 is moved to the platen roller by the urging force of the pressing spring 32 disposed between the head support member 21 and the pressing means 31. 1 is pressed.

As shown in FIG. 4 to FIG. 7, a fixed flange (flange member) 41 is rotatably disposed between the bearing 11 and the bearing 13 into which the platen roller core metal portion 1 a of the platen roller 1 is inserted. The fixed flange 41 has a flange portion 41 a that contacts the outer ring of the bearing 11. On the other hand, the opening 41 b of the fixed flange 41 is in contact with the outer ring of the bearing 13.

Further, a collar (sliding member) 42, a movable flange (flange member) 43, and a compression spring (second compression spring) 44 are disposed between the bearing 12 and the bearing 14 into which the platen roller core metal portion 1a is inserted. ing. The collar 42 that is inserted into the platen roller core 1a has a length shorter than the distance between the bearing 12 and the bearing 14, and can move between the bearing 12 and the bearing 14 along the axial direction of the platen roller 1. is there. Further, the collar 42 has a flange portion 42 a on the bearing 14 side. When the collar 42 moves to the bearing 14 side, the flange portion 42 a comes into contact with the outer ring of the bearing 14.

The movable flange 43 is rotatably inserted into the collar 42. The movable flange 43 has a flange portion 43 a on the bearing 12 side. When the movable flange 43 moves to the bearing 12 side, the flange portion 43 a comes into contact with the outer ring of the bearing 12. The compression spring 44 is fitted on the movable flange 43, one end abuts on the flange portion 42a of the collar 42, the other end abuts on the flange portion 43a of the movable flange 43, and the collar 42 and the movable flange 43 are separated from each other. Energize to.

Next, the operation of the thermal printer will be described. First, the thermal head 2 is in a state of being retracted away from the platen roller 1 as shown in FIGS. At the start of printing, the

upstream conveying rollers

7a and 7b and the downstream conveying

rollers

8a and 8b convey the recording paper 4 from the recording paper roll 4a, and the recording paper 4 is held between the platen roller 1 and the thermal head 2 at a position. Match the recording start position. At the same time, the take-up roll 5b is rotationally driven by a driving means (not shown), and the ink sheet 5 is moved so that the Y-color transfer start position of the ink sheet 5 is held between the platen roller 1 and the thermal head 2. Send it out.

Next, the pressing means 31 is moved in the direction of arrow B by an urging means (not shown), and the heating element 3 formed on the thermal head 2 by the urging force of the pressing spring 32 is passed through the ink sheet 5 and the recording paper 4. Press contact with the platen roller 1. At this time, the head support member 21 is urged in the direction of the arrow A by the urging force of the tension spring 22 provided on the locking portion 21g of the locking piece 21f, so that the

guide portions

21d and 21e are moved to the platen roller 1 of the platen roller 1. The thermal head 2 supported by the head support member 21 is positioned in the sub-scanning direction in contact with the

bearings

11 and 12 fitted in the roller metal core 1a. Thus, since the thermal head 2 is positioned in the sub-scanning direction, the heating element 3 can always be accurately positioned in the sub-scanning direction, so that the contact range (nip range) between the thermal head 2 and the platen roller 1 is reached. Therefore, the heat energy of the heat generating body 3 can be applied to the ink sheet 5 without loss, and good transfer can be performed.

The positioning of the head support member 21 in the main scanning direction will be described. The outer side surface of the guide portion 21d of the head support member 21 abuts on the flange portion 41a of the fixed flange 41 fitted into the platen roller core metal portion 1a, and the outer side surface of the guide portion 21e is a movable flange fitted into the collar 42. 43 abuts. Further, since the movable flange 43 is biased in the direction away from the collar 42 by the biasing force of the compression spring 44, the collar 42 is in the direction of arrow C described in FIGS. Biased in the direction.

When the collar 42 is urged in the direction of arrow C, the flange portion 42a abuts against the outer ring of the bearing 14 fitted in the side plate 51 to restrict movement in the direction of arrow C, and the urging force of the compression spring 44 is movable. The flange 43 is pressed in the direction of arrow D. Thus, the movable flange 43 moves in the direction of arrow D and acts to move the head support member 21 in the direction of arrow D. When the head support member 21 moves in the direction of arrow D, the fixing flange 41 is urged in the direction of arrow D through the guide portion 21d, and the outer peripheral surface of the opening portion 41b contacts the outer ring of the bearing 13 fitted in the side plate 51. Touch. Thereby, the movement of the head support member 21 in the arrow D direction is restricted.

By restricting the movement of the head support member 21 in the directions of arrows C and D, the thermal head 2 supported by the head support member 21 is positioned in the main scanning direction. As described above, since the thermal head 2 is positioned in the main scanning direction, the heating element 3 can always be accurately positioned in the main scanning direction. Can be prevented.

In the state where the platen roller 1 is separated from the thermal head 2 as shown in FIG. 7, the movable flange 43 moves in the direction of arrow D by the urging force of the compression spring 44, and from the fixed flange 41 to the movable flange 43. The distance is shorter than the outer width of the

guide portions

21d and 21e of the head support member 21. However, since the taper surfaces 41c and 43b are formed on the flange portion 41a of the fixed flange 41 and the flange portion 43a of the movable flange 43, respectively, the

guide portions

21d and 21e are moved when the thermal head 2 is lowered in the arrow B direction. Without riding on the flange portions of the fixed flange 41 and the movable flange 43, the movable flange 43 can be retracted in the direction of arrow C to generate a biasing force against the guide portion 21e.

The platen roller 1 is driven to rotate when the recording paper 4 is conveyed, but the fixed flange 41 and the movable flange 43 are not rotated due to contact resistance with the

guide portions

21d and 21e. Further, the collar 42 does not rotate due to the urging force of the compression spring 44. On the other hand, since the fixed flange 41 is in contact with the outer ring of the

bearings

11 and 13 and the collar 42 is in contact with the outer ring of the bearing 14, the driven rotation of the platen roller 1 is not hindered.

While the platen roller 1 and the thermal head 2 are in pressure contact, the recording paper 4 and the ink sheet 5 are moved in the direction of arrow E shown in FIG. 2 at the same speed, and the heat energy of the heating element 3 is applied to the ink sheet 5. Then, the Y color of the desired image is transferred onto the recording paper 4. The ink sheet 5 conveyed with the recording paper 4 is taken up by a take-up roll 5b. Due to the friction between the thermal head 2 and the ink sheet 5 when the recording paper 4 and the ink sheet 5 are conveyed in the direction of arrow E, a force in the direction of arrow A is applied to the thermal head 2. With this force, the

guide portions

21d and 21e are pressed against the

bearings

11 and 12, and the positioning of the thermal head 2 in the sub-scanning direction becomes more stable.

When the transfer of the Y color is completed, the pressing means 31 is moved in the direction of arrow F shown in FIG. 3 by the urging means (not shown), and the thermal head 2 is moved away from the platen roller 1. The recording paper 4 is pulled back in the direction of arrow G shown in FIG. 3 by the upstream conveying

rollers

7 a and 7 b and the downstream conveying

rollers

8 a and 8 b, and the recording paper 4 is held between the platen roller 1 and the thermal head 2. Match the recording start positions of At the same time, the take-up roll 5b is rotationally driven by a driving means (not shown), and the ink sheet 5 is moved so that the M-color transfer start position of the ink sheet 5 is positioned between the platen roller 1 and the thermal head 2. Send it out.

Thereafter, the heating element 3 is pressed against the platen roller 1 through the ink sheet 5 and the recording paper 4 in the same manner as in the Y color transfer described above. As the thermal head 2 is lowered in the direction of arrow B, it is similarly accurately positioned in the main scanning direction and the sub-scanning direction, so that a good transfer can be obtained without causing a transfer defect or misalignment. The same applies to the C color transfer performed after the M color transfer.

After the transfer of Y color, M color, and C color is completed, the thermal head 2 is retracted in the direction of arrow F, and the recording paper 4 is moved in the direction of arrow G by the upstream

side conveyance rollers

7a and 7b and the downstream

side conveyance rollers

8a and 8b. Then, the sheet is conveyed by a predetermined length and cut by the cutter 6 to complete the image recording.

As described above, according to the first embodiment, the

guide portions

21 d and 21 e of the head support member 21 are provided at both ends of the thermal head 2, and the

bearings

11 and 12 are provided at both ends of the platen roller 1. When the platen roller 1 is brought into pressure contact, a tension spring 22 that urges the

guide portions

21d and 21e toward the

bearings

11 and 12 is supported by both ends of the platen roller 1 and abuts against the outer surfaces of the

bearings

11 and 12. Since the fixed flange 41, the movable flange 43, and the compression spring 44 for urging the movable flange 43 toward the center position in the main scanning direction of the platen roller 1 are provided, a thermal head for the platen roller using a simple configuration. It is possible to perform positioning in the main scanning direction and the sub-scanning direction. As a result, it is possible to obtain a small-sized and low-cost thermal printer with good image quality.

As described above, the thermal printer according to the present invention enables accurate positioning of the thermal head with respect to the platen roller in the main scanning direction and the sub-scanning direction, and is suitable for use in printing of a plurality of colors.

Claims

A thermal head that applies heat to the photographic paper to print characters and image information on the recording paper;
A platen roller that is rotatably supported by a shaft portion and supports the recording paper and the photographic paper;
Guide members provided at both ends in the main scanning direction, which is the printing direction of the thermal head,
Positioning members provided at both ends in the main scanning direction of the platen roller;
First biasing means for biasing the guide member toward the positioning member when the thermal head and the platen roller are in pressure contact;
Two flange members pivotally supported at both ends of the platen roller and in contact with the outer surface of the guide member;
A thermal printer comprising: a second urging unit that urges one of the flange members toward a central position in the main scanning direction of the platen roller.
2. The thermal printer according to claim 1, wherein the second urging means is composed of a sliding member and a compression spring fitted into a shaft portion of the platen roller.