JPH0911565A - Line type color thermal printer - Google Patents

Abstract

PURPOSE: To provide a line type color thermal printer capable of avoiding the print deviation by suppressing the sheet feeding irregularity during printing. CONSTITUTION: This line type color thermal printer comprises a pick roller 2, a front roller 8, and a rear roller 10. In the case of printing, a press releasing means 14 for releasing the pressed state of the roller 8 is provided. The means 14 includes a release arm 36 for holding one of the pair of front rollers 8, a spring member 38 for setting the rollers 8 to a pressed state, a release arm 40 for pressing the arm 36 against the energizing force of the member 38, and a driving mechanism 42 for driving the cam 40.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line-type color thermal printer, and more particularly to a line-type color thermal printer that returns a sheet to an upstream side and repeats a printing operation.

[0002]

2. Description of the Related Art Conventionally, a line type color thermal printer of this type is arranged, as shown in FIG. 3, for example, a pick roller 54 for feeding a paper 50 from a paper hopper 52 and a downstream side of the pick roller 54. And a printing unit 56. The line-type color thermal printer includes a pair of front rollers 58 arranged on the upstream side of the printing unit 56, a pair of rear rollers 60 arranged on the downstream side of the printing unit 56, and a paper path switching member 62. I have it.

The printing section 56 comprises a thermal head 64, a platen roller 66, an ink ribbon 68A, and ribbon supporting rollers 68 and 70.

The line-type color thermal printer is also provided with a spring member 72 for urging one of the pair of front rollers 58 to keep it in a constantly pressed state.

The sheet 50 sent out by the pick roller 54 is partially printed by the printing unit 56 and then returned to the upstream side by the reverse rotation operation of the front roller 58 and the like. In this case, the trailing edge of the paper 50 is guided by the paper path switching member 62 in a direction different from the path to the pick roller 54. This printing operation is repeated to perform multicolor printing.

[0006]

However, in the above-described conventional line type color thermal printer, since the space between the front rollers 58 is constantly pressed, the rear end of the paper 50 is separated from the front roller 58 in the printing operation. At the moment when it comes off, the balance of the force on the paper 50 is lost. That is,
Since the tension state of the pressure support between the platen roller 66 and the rear roller 60 suddenly collapses, there is a problem in that pitch unevenness partially occurs and print misalignment occurs.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a line type color thermal printer capable of improving the disadvantages of the conventional example and suppressing the occurrence of paper feeding unevenness during the printing operation, thereby effectively preventing the printing deviation. That is the purpose.

[0008]

According to the first aspect of the present invention, a pick roller for feeding a sheet, a printing section arranged on the downstream side of the pick roller, and a sheet arranged on the upstream side of the printing section. A pair of front rollers for feeding and returning the sheet, and a pair of rear rollers disposed downstream of the printing section for feeding and returning the sheet. Further, a configuration is adopted in which a pressing releasing means for releasing the pressing state between the pair of front rollers described above is provided during the printing operation.

According to a second aspect of the present invention, in the structure of the first aspect, the pressing releasing means is rotatably provided with an intermediate portion supported by a shaft, and one of the pair of front rollers is provided at one end side. A release arm that is rotatably held, a spring member that constantly urges the other end of the release arm to press the pair of front rollers into a pressed state, and a release arm that resists the urging force of the spring member. Of the release cam and a drive mechanism that drives the release cam according to the printing operation.

According to a third aspect of the present invention, in the structure according to the second aspect, the release cam includes an eccentric cam body and a drive connecting portion formed at a position deviated from the center of the cam body. , Is adopted.

[0011]

First, the paper sent out by the pick rollers is sent to the printing section by the pair of front rollers in the pressed state,
Further, it is sent to a pair of rear rollers. After that, the pressure releasing means operates to release the pressure between the pair of front rollers. The paper is partially (yellow) printed by the printing unit while being fed by the pair of rear rollers with the support on the front roller side being opened. When a part of the printing is completed, the pressing releasing means operates to bring the pair of front rollers into a pressed state, and the pair of front rollers is returned to the upstream side in a tensioned state supported by the rear roller and the front roller. When performing the next printing, the pressing state between the pair of front rollers is released again by the pressing release means.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

In FIG. 1, reference numeral 2 indicates a pick roller for feeding the paper 4, and reference numeral 6 indicates a printing portion arranged on the downstream side of the pick roller 2. Further, reference numeral 8 indicates a front roller arranged on the upstream side of the printing section 6, and reference numeral 10 indicates a rear roller arranged on the downstream side of the printing section 6. Furthermore, reference numeral 12 indicates a paper path switching member for switching the path when the paper 4 is returned, and reference numeral 14 indicates a pressing release means for releasing the pressing of the front roller 8 during the printing operation.

The printing unit 6 includes a platen roller 16, a thermal head 18 pressed against the platen roller 16 during printing, an ink ribbon 20, and the ink ribbon 2.
Ribbon support rollers 22, 2 for feeding and winding 0
And 4.

The front roller 8 is composed of a front fixed roller 26 and a front pressure roller 28 pressed against the fixed front roller 26. On the other hand, the rear roller 10 includes a rear fixed roller 30,
The rear pressure roller 32 is pressed against the rear fixed roller 30.

The pressure releasing means 14 is a release arm 3 rotatably mounted on the printer body at an intermediate portion by a shaft 34.
6 and a spring member 38 disposed between the rear end of the release arm 36 and the printer body. The front pressure roller 28 is rotatably held at the tip of the release arm 36. There is. Also, the pressure release means 1
4 is a release arm 3 against the biasing force of the spring member 38.
A release cam 40 that presses the rear end portion 6 and a drive mechanism 42 that drives the release cam 40 in accordance with the printing operation.

The release cam 40 is an eccentric cam body 4
4 and a drive connecting portion 46 formed at a position deviated from the center of the cam body 44 and connected to the drive mechanism 42. Here, the pick roller 2 receives power from a pick motor (not shown) to pick a sheet, and the front roller 8, the platen roller 16, and the rear roller 10 are L-shaped.
Paper is conveyed by receiving power from an F motor (not shown).

Next, the printing operation of the line type color thermal printer in the above embodiment will be described.

The overall flow of the color printing operation is paper pick, paper suction, printing (yellow), paper reverse, printing (magenta), paper reverse, printing (cyan), paper ejection.

First, as shown in FIG. 2, the pick roller 2
The sheet 4 sent out from the hopper 48 by the above is sent to the platen roller 16 of the printing unit 6 by the front roller 8 which is pressed by the biasing force of the spring member 38. Here, the thermal head 18 is pressed against the platen roller 16. Thereafter, the sheet 4 is moved to the rear roller 10 by the platen roller 16.
Transported to After this, the drive mechanism 4 of the pressure releasing means 14
The release cam 40 is rotationally driven by 2. As a result, the rear end portion of the release arm 36 is pressed against the biasing force of the spring member 38, and the front pressure roller 28
Separates from the front fixing roller 26 (state of FIG. 1).

When the pressed state of the front roller 8 is released, that is, when the rear end of the sheet 4 is opened, the rear roller 10 feeds a part of the printing (yellow). When the printing of this part is completed, the front roller 8 is returned to the pressed state again by the operation of the pressure releasing means 14, and the sheet 4 is rear roller 10 and platen roller 16
Also, it is returned to the upstream side in a tensioned state supported by the front roller 8, that is, in a state without slack. FIG. 2 shows this state.

When the next printing (magenta) is performed on the paper 4 returned to the upstream side, as shown in FIG.
4, the pressed state of the front roller 8 is released again. The same operation is performed when printing (cyan). The front roller 8 is also in the pressed state when all the printing is completed and the paper 4 is discharged.

Here, in the above embodiment, the pressure releasing means 1
4 is shown with a specific configuration and a specific shape, the present invention is not limited to this, and the pressing state of the front roller 8 can be released only during the printing operation to prevent the paper feeding force from being unbalanced, and The configuration, shape, etc. may be changed as appropriate within the range that a function without slack can be obtained at the time of returning and discharging.

[0024]

As described above, according to the present invention, since the pressing state of the front roller is released during the printing operation, it is possible to avoid the pitch unevenness due to the imbalance of the paper feeding force. It is possible to effectively prevent the print misalignment that has occurred in the conventional example.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing one embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the operation of FIG.

FIG. 3 is an explanatory diagram showing a conventional example.

[Explanation of symbols]

 2 Pick roller 4 Paper 6 Printing section 8 Front roller 10 Rear roller 14 Press release means 34 Shaft 36 Release arm 38 Spring member 40 Release cam 42 Drive mechanism 44 Cam body 46 Drive connection section

Claims (3)

[Claims] 1. A pick roller for feeding a sheet, a printing section arranged on the downstream side of the pick roller, and a pair of front rollers arranged on the upstream side of the printing section for feeding and returning the sheet. A line provided with a pair of rear rollers arranged downstream of the printing unit for feeding and returning the paper, and repeating the operation of returning the paper to the upstream side after printing a part in the printing unit and printing again. A line type color thermal printer, characterized in that the pair of front rollers are equipped with a pressure releasing means for releasing the pressure applied to the paper during the printing operation by the printing unit. 2. A release arm in which the pressing release means is rotatably provided with an intermediate portion supported by a shaft and rotatably holds one of the pair of front rollers on one end side, and the release arm. A spring member for constantly urging the other end of the release roller to bring the pair of front rollers into a pressed state, a release cam for pressing the other end of the release arm against the urging force of the spring member, and the release cam. The line type color thermal printer according to claim 1, further comprising a drive mechanism that drives the printer according to a printing operation. 3. The line-type color thermal printer according to claim 2, wherein the release cam comprises an eccentric cam body and a drive connecting portion formed at a position deviated from the center of the cam body. Printer.