JPH0524305A - Head pressing device of printer - Google Patents

Abstract

PURPOSE:To carry out high quality printing, in a thermal transfer printer applying printing to paper through an ink ribbon by accurate pressing force using a thermal head, by making the pressing force of the thermal head accurate with respect to paper different in thickness or smoothness. CONSTITUTION:By differentiating the printing force of a thermal head 1 imparted when printing is applied to exclusive thermal transfer paper from that of the thermal head 1 imparted when printing is applied to paper 2 different from the thermal transfer paper in thickness or smoothness, the accurate pressing force of the thermal head 1 can be set by papers different in thickness or smoothness and good printing quality generating no blur, collapse and reverse transfer can be ensured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer printer in which a thermal head prints on paper with an appropriate pressing force via an ink ribbon, and a head pressing device for the printer capable of printing on two or more different kinds of paper. Regarding

[0002]

2. Description of the Related Art A conventional head pressing device for a printer will be described below.

As shown in FIGS. 4 and 5, the thermal head 1 presses the sheet 2 against the platen 9 via the ink ribbon 3. The thermal head 1 is mounted on a carriage 4, and is rotatably arranged around a carriage shaft 14 that slides the carriage 4 in an axial direction as a support shaft. It is configured to press and release the sheet 2 via the cam 6 that is transmitted and driven by the drive motor 5. The pressing force on the paper 2 is always a constant load because the thermal head 1 is pressed by the spring force of the spring 7 mounted on the carriage 4. The paper 2 is conveyed by a paper feed roller 8 a and a paper feed auxiliary roller 8 b which is rotated by being pressed by the paper feed roller 8 a and is sent to a gap between the platen 9 and the carriage 4. At this time, since the sheet 2 is conveyed in the tangential direction on the contact point between the sheet feed roller 8a and the sheet feed auxiliary roller 8b, it is not conveyed in parallel to the surface of the platen 9 and the sheet with the carriage 4 is conveyed. 2 will be passed while being bent. The paper 2 is printed in close contact between the thermal head 1 and the platen 9 due to the pressing force required for printing that is greater than the strength of the paper 2.

[0004]

However, in the above-mentioned conventional configuration, when the paper 2 is thicker than a dedicated thermal transfer paper such as a postcard manufactured by a public office and has a strong rigidity, printing is performed by the strength of the paper 2. When the thermal head 1 is sometimes pressed against the platen 9, the thermal head 1 is more likely to be conveyed in the tangential direction at the contact point between the feed roller 8a and the feed assist roller 8b. The pressing force against the strength is reduced, and the pressure distribution is different between the upper part and the lower part of the thermal head 1 which are in contact with the platen 9, and the printed characters and the like are blurred. Therefore, there is a problem that the printing quality is impaired. Further, if the head pressure is set to a high value in accordance with a large sheet thickness, problems such as character crushing and reverse transfer will occur in printing of a dedicated thermal transfer sheet, which is satisfactory for all different types of sheets 2. However, there is a problem that it is impossible to perform proper printing.

The present invention solves the above-mentioned problems of the prior art. A head pressing device for a printer, which can perform high-quality printing by ensuring an appropriate head pressing force even for papers having different paper thickness and smoothness. The purpose is to provide.

[0006]

In order to achieve this object, the head pressing device of the printer of the present invention has a pressing force of the thermal head when printing on a dedicated thermal transfer paper, and the thermal transfer paper has a paper thickness and smoothness. It is configured such that it can be varied depending on the pressing force of the thermal head when printing on paper of different degrees.

[0007]

With this structure, the pressing force of the thermal head can be set appropriately for each sheet having different thickness and smoothness.

[0008]

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

1 to 3 showing an embodiment of the present invention, the same parts as those of the conventional example are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 1, the carriage 4 is provided with a cam gear 12 for rotating a pressing lever 11 for pressing the thermal head 1 against the platen 9 via the paper 2 about a support shaft 11a. ing. Push lever 11
The circular hook portion 13 for pressing the thermal head 1
A head pressing spring 13 having a is integrally arranged.

A head pressing lever 11 is pressed by a cam gear 12 which is rotatably driven by a drive motor 5 through a reduction gear to rotate forward and backward, and a head pressing spring 13 integrally formed on the head pressing lever 11. Round hook part 13
a is in contact with the head holder 10 having the thermal head 1 and presses it against the platen 9 via the ink ribbon 3 and the paper 2. The shape of the cam 12a of the cam gear 12 is formed so that the radii of rotation from the cam fulcrum are continuously different.

The operation of the printer head pressing device configured as described above will be described below. Cam 12
The cam 2a stands still at a predetermined position by driving the drive motor 5 with a predetermined number of steps together with a sensor for detecting the position on the a.

When the cam 12a driven by the motor 5 on the carriage 4 is in the position shown in FIG. 2, the displacement amount l of the head pressing spring 13 is equal to the displacement of the drive motor 5 on the carriage 4.
Is larger than the displacement amount m of the head pressing spring 13 when the cam 12a is in the position shown in FIG. 3, the head pressing force in the case shown in FIG. The value is higher than the pressure. The paper 2 has a paper thickness of about 70 to 100 μm like a general thermal transfer paper to about 200 to 240 μm like a postcard manufactured by a public company. As shown in FIG. 2, the pressing force is set to be high, and the negative amount due to the strength of the paper 2 is taken into consideration to obtain good print quality without print blurring. As shown in, the pressing force is set to be slightly lower to obtain good print quality without character collapse and reverse transfer.

As described above, according to the present embodiment, by having two types of head pressing force, it is possible to press the thermal head 1 accurately even with respect to the paper 2 having different paper thickness and smoothness. High-quality printing can be performed by the pressure, and by further changing the pressing type depending on the shape of the cam 12a, good printing of two or more types of paper 2 can be performed. Although the pressing means is configured on the carriage 4 in the present embodiment, the same effect can be obtained by the pressing force switching means from the outside of the carriage 4.

[0015]

As is apparent from the above description of the embodiments, the present invention can be applied to a paper having different paper thickness and smoothness from the thermal head pressing force when printing on a dedicated heat transfer paper. Since it can be changed with the pressing force of the thermal head when printing, an excellent head pressing device for a printer that can perform high quality printing by adjusting the head pressing force even for paper with different paper thickness and smoothness It can be realized.

[Brief description of drawings]

FIG. 1 is a schematic plan view showing a concept of a main part of a head pressing device of a printer according to an embodiment of the present invention.

FIG. 2 is a schematic plan view of essential parts showing the concept of a state in which the head pressing force of the head pressing device of the printer is increased.

FIG. 3 is a schematic plan view of essential parts showing the concept of a state in which the head pressing force of the head pressing device of the printer is reduced.

FIG. 4 is a schematic plan view showing the concept of a main part of a conventional head pressing device of a printer.

FIG. 5 is a schematic side view of essential parts showing the concept of a head pressing device of the printer.

[Explanation of symbols]

 1 Thermal Head 2 Paper 3 Ink Ribbon 9 Platen 11 Pressing Lever 12 Cam Gear 13 Head Pressing Spring

Claims (1)

Claim: What is claimed is: 1. A printer for printing by pressing a thermal head against a platen via an ink ribbon and paper.
A head pressing device for a printer, which has means for varying the pressing force of the thermal head.