JP2000272151A - Thermal printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a thermal printer having a plurality of print sections in which a print medium can be fed and printed continuously without sacrificing print quality. SOLUTION: A thermal printer having print sections A, B located at at least two positions in the carrying direction of a print medium 1 while spaced apart from each other is provided with mechanisms 4, 5, 6 for regulating the contact pressure between a thermal head 3 and a platen roller 2. When these load regulation mechanisms lessen the contact pressure between the thermal head and the platen roller when the part of a print medium close to the end thereof arrives at the contact part between the thermal head and the platen roller.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal printer having at least two printing units.

[0002]

2. Description of the Related Art A conventional printing mechanism is disclosed in, for example,
As disclosed in JP-A-262786, a first printing unit that prints on the lower surface side of a sheet via a thermal transfer ink ribbon, and a second printing unit that prints on the upper surface side of the sheet via a thermal transfer ink ribbon. A two-sided printing thermal printer including a printing unit is known.

That is, in this thermal printer, a sheet cutter located between the two printing units separates the printing paper on which the lower surface has been printed from the continuous paper, detects the leading end of the continuous paper with a paper sensor, and performs first printing. The printing paper printed by the copy unit is sent to the second printing unit, and is simultaneously printed by multiplex processing.

[0004]

However, such a conventional technique has the following problems to be improved.

That is, in the conventional thermal printer,
While the first printing unit is printing on the second printing medium while the second printing unit is printing on the first printing medium, the second printing unit performs printing on the second printing unit. When printing is completed and the print medium is ejected, a collision between the thermal head and the platen roller occurs in the second printing section, and the impact force at that time is transmitted to the first printing section during printing, There is a problem in that the load on the print medium fluctuates, adversely affects printing, and lowers printing accuracy. .

Therefore, in order to continuously print two print media without causing a load variation, the first print medium is completely separated from the second print unit and then is replaced by two print media in the first print unit. The eyes were to be printed. However, even in such a measure, since the print medium is held in the standby state with respect to the first printing unit, there is a problem that the printing speed is reduced and the printing performance is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of such conventional problems, and in a thermal printer having a plurality of printing units, continuous supply and continuous supply of print media while preventing a decrease in print quality. The purpose is to enable printing.

[0008]

According to a first aspect of the present invention, there is provided a thermal printer, comprising: a thermal head; a platen roller disposed to face the thermal head; A printing section comprising a pressing mechanism for elastically pressing the thermal head against a platen roller, a thermal printer comprising at least two locations provided at intervals in the transport direction of the print medium, wherein the pressing mechanism includes: A load adjusting mechanism for adjusting the contact pressure between the thermal head and the platen roller is provided, and when these load adjusting mechanisms reach the contact portion between the thermal head and the platen roller near the end of the print medium, It is characterized in that the contact pressure between the thermal head and the platen roller is reduced. In the thermal printer according to a second aspect of the present invention, each of the load adjustment mechanisms according to the first aspect adjusts an urging member mounted on the thermal head and an elastic deformation amount of the urging member. And a cam member for adjusting a contact pressure between the thermal head and a platen roller.
In a thermal printer according to a third aspect of the present invention, the load adjustment mechanism according to the first or second aspect sets a contact pressure between the thermal head and the platen roller to a contact pressure suitable for printing. And a release mode in which the contact pressure is lower than the pressure in the print mode and is a contact pressure at which the print medium can be transported by the platen roller, and an open mode in which the contact pressure is released. It is characterized by being. In the thermal printer according to a fourth aspect of the present invention, the cam member according to the third aspect is provided so as to be capable of reciprocating rotation within a predetermined angle range, and has a profile whose bottom is close to the center of rotation. And a high-top portion connected to one side in the rotation direction of the cam member with respect to the bottom portion, and a high-top portion furthest away from the center of rotation, and a continuous connection with the bottom portion on the opposite side to the high-top portion. And a middle top portion closer to the center of rotation than the high top portion and farther from the center of rotation than the bottom portion. In a thermal printer according to a fifth aspect of the present invention, a guide member for guiding the upper and lower surfaces of the print medium is provided between the two printing units according to any one of the first to fourth aspects. It is characterized by being. According to a sixth aspect of the present invention, there is provided a thermal printer according to any one of the first to fifth aspects, wherein a thermal transfer ink is provided between the thermal head and a platen roller constituting each of the printing units. The ribbon is inserted. Further, in a thermal printer according to a seventh aspect of the present invention, the thermal head of the one printing unit according to any one of the first to sixth aspects is disposed on the front side of the print medium, and Wherein the thermal head of the printing section is provided on the back side of the print medium.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings. As shown in FIG. 1, the thermal printer according to the present embodiment is configured to continuously print a print medium 1 such as a cut thermal transfer sheet.
A first printing unit A and a second printing unit B are arranged adjacent to each other along the transport direction of FIG. The first printing unit A is configured to perform printing on the upper surface of the printing medium 1, and the second printing unit B is configured to perform printing on the lower surface of the printing medium 1.

The first printing section A and the second printing section B are brought into contact with the thermal heads 3 and 8, respectively, and the platen to which the printing medium 1 is supplied therebetween. Rollers 2 and 7 are provided.

A feed roller 14 for feeding the cut print medium 1 to the printing section is provided in the first printing section A.
Further, a feed roller 15 similar to the feed roller 14 is provided in the second printing section B.

Each of the thermal heads 3 and 8 provided in the printing section is provided with a pressing mechanism for bringing the thermal heads 3 and 8 into contact with the platen rollers 2.7. And platen rollers 2.7
There is provided a load adjustment mechanism for adjusting the contact pressure with the load.

The pressing mechanism includes a cam 6/11 arranged to face the thermal head 3.8, and a compression spring 4 as an urging member interposed between the cam 6/11 and the thermal head 3.8. 9 and this compression spring 4.9
Brackets 5 and 10 interposed between the cam and the cams 6 and 11
In the present embodiment, the cams 6.1
1 and the brackets 5 and 10 constitute a load adjusting mechanism.

Further, between the first printing section A and the second printing section B, a paper guide 13 which is a guide member for feeding the printing medium 1 is provided.

Further, in the present embodiment, each of the cams 6 and 11 is provided so as to be capable of reciprocating rotation within a range of a predetermined angle, and has a profile whose bottom portions 6a and 11a are close to the center of rotation. The high top portions 6b and 11b, which are connected to the bottom portions 6a and 11a on one side in the direction of rotation of the cams 6 and 11 and that are farthest from the center of rotation, and the bottom portions 6a and 11a. High top part 6b ・ 11
b, the high-top portions 6b and 11b
Closer to the center of rotation and the bottom portions 6a and 11
Middle top parts 6c and 11c farther from the center of rotation than a
And is constituted by.

By setting the high top portions 6b and 11b to face the brackets 5 and 10, the printing mode is set so that the contact pressure between the thermal heads 3.8 and the platen rollers 2.7 is a contact pressure suitable for printing. (See FIG. 2 (b).) Also, by making the middle top portions 6c and 11c face the brackets 5 and 10, the contact pressure is smaller than the pressure in the above-described print mode, and the platen rollers 2.7 The transfer mode (see FIG. 2 (c)) is set to a contact pressure at which the print medium 1 can be transferred according to (1), and the contact pressure is released by making the bottom portions 6a and 11a face the brackets 5 and 10. Mode (Fig. 2
(See (a)). The contact pressure is adjusted to three stages.

Next, the operation of the present embodiment configured as described above will be described. In the first printing section A, the cut print medium 1 is fed by the feed roller 14. At this time, the thermal head 3 of the first printing unit A is set to the print mode, and a printing load is applied to the thermal head 3, whereby one side of the print medium 1 is printed.

On the other hand, in the second printing section B, printing on the other side of the printing medium 12 is performed. When this printing is completed, the thermal head 8 is set to the transport mode, and
The print medium 12 is discharged from the second printing section B. At this time, since the second printing unit B is set to the transport mode as described above, the pressing force applied to the thermal head 8 is adjusted to be small.
Thermal head 8 when print medium 12 is ejected
The impact force at the time of contact with the platen roller 7 is reduced.
As a result, even when printing is being performed in the first printing unit A, unnecessary load acting on the first printing unit A is suppressed from acting, and a decrease in print quality is suppressed. . Therefore, the printing medium 12 from the second printing unit B
The printing medium 1 can be supplied to the first printing unit A without waiting for the discharge of the printing medium, thereby improving the printing speed.

It is assumed that the printing relationship between the first printing unit A and the second printing unit B is opposite to the above-described relationship. In this case, the printing from the first printing unit A is performed. By setting the thermal head 3 in the transport mode when the medium 1 is discharged, it is possible to suppress a decrease in print quality in the second printing unit B.

The various shapes, dimensions, and the like of the components shown in the above embodiment are merely examples, and can be variously changed based on design requirements and the like. For example, as shown in FIG. 3, it is also possible to interpose the ink ribbon 16 between the thermal head 3 and the platen roller 2 so that the ink ribbon 16 can be continuously transferred. With such a configuration, printing can be performed even when the printing medium is plain paper other than thermal transfer paper.

[0021]

The present invention is configured as described above and has the following effects. When performing continuous printing on a printing medium in one printing unit, the impact force at the time of discharging the printing medium in the other printing unit is reduced, and unnecessary external force is prevented from acting on the other printing unit. High-speed printing is possible while preventing deterioration in printing performance and printing accuracy.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing one embodiment of the present invention.

FIGS. 2 (a) to 2 (c) are explanatory views of each mode by rotation of a cam.

FIG. 3 is a conceptual diagram showing another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Print medium 2 Platen roller 3 Thermal head 4 Compression spring (pressing mechanism / load adjusting mechanism) 5 Bracket (pressing mechanism / load adjusting mechanism) 6 Cam (pressing mechanism / load adjusting mechanism) 6a Bottom part 6b High top part 6c Middle top Part 7 Platen roller 8 Thermal head 9 Compression spring (pressing mechanism / load adjusting mechanism) 10 Bracket (pressing mechanism / load adjusting mechanism) 11 Cam (pressing mechanism / load adjusting mechanism) 11a Bottom part 11b High top part 11c Middle top part 12 Print medium 13 Paper guide (guide member) 14 Feed roller 15 Feed roller 16 Ink ribbon A First print unit B Second print unit

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[Procedure amendment]

[Submission date] March 21, 2000 (200.3.2
1)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction contents]

[0008]

According to a first aspect of the present invention, there is provided a thermal printer, comprising: a thermal head; a platen roller disposed to face the thermal head; A printing section comprising a pressing mechanism for elastically pressing the thermal head against a platen roller, a thermal printer comprising at least two locations provided at intervals in the transport direction of the print medium, wherein the pressing mechanism includes: the thermal head and the load adjusting mechanism for adjusting the contact pressure between the platen roller is provided, one sign
While printing is being performed in the printing section, the other printing section
At the time when printing with
A thermal printer , wherein a load adjusting mechanism is configured to reduce a contact pressure between the thermal head and a platen roller. The thermal printer according to claim 2 of the present invention, each of the load adjustment device according to claim 1
The mechanism comprises an urging member mounted on the thermal head,
Adjust the amount of elastic deformation of the biasing member of
And a cam member for adjusting the contact pressure between the platen roller and the platen roller.
This cam member is provided within a range of a predetermined angle.
It is provided so as to be reciprocally rotatable within the enclosure, and its profile
The bottom part close to the center of rotation and the bottom part
The cam member is connected to one side in the rotation direction of the cam
The farthest high top part and the bottom part
It is installed on the opposite side of the high top part, and this high top part
Closer to the center of rotation and rotating more than the bottom part
And a middle top portion remote from the heart.
The top and the thermal head and the platen roller
Printing mode with a contact pressure suitable for printing
And the pressure in the printing mode by the middle top portion.
Smaller than the printing medium by the platen roller.
The transfer mode is set to a contact pressure at which the body can be transferred, and
An open mode in which the contact pressure is released by the bottom portion
It is characterized by having been made . According to a third aspect of the present invention, there is provided a thermal printer, wherein a guide member for guiding the upper and lower surfaces of the print medium is provided between the two printing units according to the first or second aspect. Features.

Claims (7)

[Claims] 1. A printing section comprising a thermal head, a platen roller disposed opposite to the thermal head, and a pressing mechanism for elastically pressing the thermal head against the platen roller, in a printing medium transport direction. A thermal printer provided in at least two places with an interval, wherein the pressing mechanism is provided with a load adjusting mechanism for adjusting a contact pressure between the thermal head and a platen roller, and these load adjusting mechanisms are provided. A thermal printer configured to reduce a contact pressure between the thermal head and the platen roller when a portion near an end of the print medium reaches a contact portion between the thermal head and the platen roller. Each of said load adjusting mechanisms adjusts an urging member mounted on said thermal head and an elastic deformation amount of said urging member to adjust a contact pressure between said thermal head and a platen roller. 2. The thermal printer according to claim 1, wherein the thermal printer comprises a cam member. 3. A printing mode in which the load adjusting mechanism sets the contact pressure between the thermal head and the platen roller to a contact pressure suitable for printing, and a pressure smaller than the printing mode.
2. The method according to claim 1, wherein the contact pressure is adjusted in three stages: a transport mode in which the contact pressure is such that the print medium can be transported by the platen roller; and an open mode in which the contact pressure is released. Item 3. The thermal printer according to Item 2. 4. The cam member is provided so as to be capable of reciprocating rotation within a predetermined angle range, and has a profile close to a center of rotation, and a rotation of the cam member with respect to the bottom portion. The high-top portion, which is continuously provided on one side in the direction, is furthest away from the center of rotation, and is continuously provided on the opposite side to the high-top portion with respect to the bottom portion, closer to the center of rotation than the high-top portion, The thermal printer according to claim 3, further comprising a middle top portion farther from the center of rotation than the bottom portion. 5. The thermal printer according to claim 1, wherein a guide member for guiding upper and lower surfaces of the print medium is provided between the two printing units. . 6. The printing apparatus according to claim 1, wherein an ink ribbon for thermal transfer is inserted between the thermal head and a platen roller constituting each of the printing units. Thermal printer. 7. The thermal head of the one printing section,
The thermal head according to any one of claims 1 to 6, wherein a thermal head of the other printing unit is provided on a front side of the print medium, and is provided on a back side of the print medium. Printer.