JPH0745332Y2 - Paper transport device for thermal printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a sheet conveying device used in a thermal printer of Japanese Patent Application No. 63-119123 filed by the present applicant.

[Background of the invention]

As shown in FIG. 6, the thermal printer is provided with two drums 3 provided on both sides of the platen 5 in the axial direction, at predetermined intervals along the circumferential direction of the drum 3, and rotatably supported. A plurality of pulleys 6 and an endless belt 4 which is guided by these pulleys 6 and whose inner side is in close contact with the outer circumference of the drum 3 leaving a part (opening) of the outer circumference of the drum 3, The drum 3 and the belt 4
The thermal head 10 performs printing with the sheet 9 being sandwiched between the sheets and wound around the drum 3, and there is an advantage that color printing can be performed without reciprocating the sheet 9.

Such a printer will be briefly described with reference to FIG. FIG. 6 shows the sheet feeding operation, and it is assumed that the lower side of the opening where the belt 4 is not in contact is located below the sheet feeding guide 1. The sheet-shaped paper 9 on the paper feed cassette 7 is taken out one by one by the pickup roller 8, further guided by the paper feed guide 1, and sent toward the drum 3. At the time of paper feeding, the drum 3 is rotated clockwise by a motor or the like (not shown), and the belt 4 is rotated as the drum 3 rotates.
Since the paper 9 is also rotated clockwise, the paper 9 is inserted between the drum 3 and the belt 4 and wound around the drum 3. As a result, both side edges of the paper 9 are nipped by the drum 3 and the belt 4. Like When the trailing edge of the paper 9 is wound around the drum 3, the paper feeding operation is completed and the next printing operation is started.

During the printing operation, the drum 3 and the belt 4 are integrally rotated in the counterclockwise direction. As a result, the side edges of the sheet 9 are clamped by the drum 3 and the belt 4 in the longitudinal direction and moved in the counterclockwise direction, that is, in the direction opposite to the sheet feeding direction. The ink on the thermal ribbon (not shown) is transferred and printed. Therefore, if the thermal ribbon has three or four colors, printing is completed by three or four rotations of the drum 3.

When the printing operation is completed, the paper discharging operation is started. At this time, it is assumed that the upper side of the opening of the drum 3 is located above the paper feeding guide 1. During the paper discharge operation, the drum 3 is rotated in the clockwise direction similarly to the paper feed, and the belt 4 is also driven to rotate, so that the paper 9 is discharged from the holding portions of the drum 3 and the belt 4, and the paper discharge guide (not shown) is used as a guide. Is discharged.

The paper feed guide 1 is provided close to the drum 3 so that the gap between the paper feed guide 1 and the drum 3 is as small as possible in order to smoothly convey the paper 9 to the holding section.
Therefore, there is a problem that when the paper 9 moves counterclockwise during printing, it interferes with the paper feed guide 1 and paper jam occurs.

[Purpose of device]

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, improve paper conveyance during printing, and improve the reliability of the thermal printer.

[Outline of device]

The present invention focuses on the fact that the above-mentioned problems of the prior art occur because the tip of the paper feed guide is bent in the paper feed direction, and the tip of the paper feed guide does not come into contact with the paper during printing. The relationship between the paper feed guide and the elastic guide is devised so that the elastic guide is provided below the paper feed guide. The present invention will be described below with reference to FIGS. 1 to 5 showing an embodiment.

[Example of device]

1 to 5 show a sheet feeding guide 1 and an elastic guide 2 which are essential parts of the present invention. For example, an elastic guide 2 formed by a leaf spring or the like has a lower end below the sheet feeding guide 1. Is mounted on the stationary fixing portion located at, and the tip extends, as shown in the enlarged view of FIG. 2, so as to be located above the tip bent in the sheet feeding direction of the sheet feeding guide 1 and on the drum 3 side. There is.

FIG. 3 shows the start of sheet feeding. Since the elastic guide 2 is bent downward by the sheet 9, that is, in the sheet feeding direction, there is no obstacle during sheet feeding.

FIG. 4 shows the end of sheet feeding, and the elastic guide 2 returns to the state before sheet feeding when the trailing edge of the sheet 9 leaves.

FIG. 5 shows a state at the time of printing, in which the tip of the elastic guide 2 is pushed slightly upward by the sheet 9. As described above, since the elastic guide 2 is located between the paper feed guide 1 and the paper 9 during printing to prevent the paper 9 from interfering with the paper feed guide 1, a paper jam phenomenon may not occur. Disappear.

[Effect of device]

According to the present invention, since a paper jam at the time of printing can be prevented with a simple structure in which an elastic guide is added, the reliability of the thermal printer can be improved.

[Brief description of drawings]

1 to 5 show one embodiment of the device of the present invention.
FIG. 1 is a side view showing a state before sheet feeding, FIG. 2 is an enlarged side view showing an essential part of FIG. 1, FIG. 3 is a side view showing a sheet feeding start time, and FIG. FIG. 5 is a side view showing a state during printing, and FIG. 6 is a side view showing an example of a conventional example. In the figure, 1 is a paper feed guide, 2 is an elastic guide, 3 is a drum, 4 is a belt, 5 is a platen, 6 is a roller, 7 is a paper feed cassette, 8 is a pickup roller, 9 is paper, and 10 is a thermal head. is there.

Claims (1)

[Scope of utility model registration request] 1. A platen facing a linear thermal head, two drums provided on both sides of the platen in the axial direction, and a plurality of belts provided at predetermined intervals along the circumferential direction of the drum. A supporting pulley and an endless belt which is guided by these pulleys and whose inner side is in close contact with the outer circumference of the drum are provided. When the paper is fed, the drum and the belt are rotated in one direction to insert a sheet between the belt and the drum, At the time of printing, the belt and drum are integrally rotated to move the paper in the direction opposite to the paper feeding direction, and when the paper is moved, the platen and the thermal head print on the paper. And the lower end is fixed below the paper feed guide and the front end is located above the front end of the paper feed guide. An elastic guide provided as described above is provided.