JPS6184272A - Ribbon-feeding mechanism - Google Patents

Abstract

PURPOSE:To prevent relative slippage from occurring between a printing paper and an ink ribbon and prevent a printed surface from being contaminated due to rubbing of carbon, by providing a ribbon-pressing means at a position different from a pressing position of a printing head. CONSTITUTION:In a thermal transfer type thermal printer wherein printing on a printing medium 3 such as a printing paper is conducted while pressing an ink ribbon 4 by a printing head 1, a pressing means is provided for pressing the ribbon 4 at a position different from the pressing position of the head 1. The pressing means comprises, for example, a rail 10 covered by a rubber plate 10a with a high coefficient of friction on the front side thereof overlapping with a part of the width of the ribbon 4 out of the printing position of the head 1 and disposed in parallel with a platen 2, and rollers R5, R6 provided on a carrier 5 so that the ribbon 4 is pressed against the rail 10 by the rollers R5, R6. Even when the pressing force of the head 1 is increased to increase printed density, the ribbon 4 is securely pressed against the rail 10 by the rollers R5, R6. Accordingly, slippage between the ribbon 4 and the printing paper 3 is prevented from occurring.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an ink ribbon feeding mechanism in a thermal transfer thermal printer, and in particular, to a mechanism for ensuring print quality by preventing print smudges due to ink ribbon displacement. This relates to a ribbon feeding mechanism that can be used.

Recently, with the development of office automation, various computer terminals and word processors have been developed.

A thermal transfer type thermal printer has been developed and put into practical use as a printing output device for facsimiles and the like.

The ink ribbon used in this printer is a film ribbon coated with heat-soluble carbon ink.

These ribbons are pressed against the print medium by a thermal head during printing, and a method is desired that does not cause staining of the print surface due to ribbon displacement.

[Conventional technology]

Figure 3 is a perspective view illustrating the main parts of a thermal transfer printer;
The figure is a side view of FIG. 3. The same reference numerals indicate the same objects throughout the figures.

As shown in FIG. 3, the thermal head 1 mounted on the carrier 5 comes into contact with the printing paper 3, which is placed on the platen 2, via the ink ribbon 4, and presses it with a constant pressure.

The carrier 5 is slidably fitted into a guide shaft 6 arranged parallel to the platen 1, and is also fixed to a feed belt 7 parallel to the platen 2, which is connected via a pulley (not shown). connected to the space motor,
The thermal head 1 can be moved back and forth in the directions of arrows A and B in the figure by forward and reverse rotation of the motor.

The thermal head 1 is equipped with a plurality of resistance heating elements (hereinafter referred to as heating elements) in order to form prints using dots.
A heat generating section is provided.

The ink ribbon 4 is housed in a ribbon cassette 8 and mounted on a carrier 5.

Also, as shown in the fourth episode, the printing paper 3 is fed by the feed roller R1.
~ R4 in the direction of arrow C.

The ink ribbon 4 is, for example, a volume film tape (or paper tape) coated with heat-soluble ink containing carbon on one side, and when the heating element [a] of the thermal head in contact with it is heated, the ink is heated. The image is thermally transferred onto the printing paper 3.

With such a configuration and function, when the carrier 5 is driven when the mark ':,' is commanded to start, and the heat generating element ]a of the thermal head 1 is selectively heated based on the print data, the platen is heated. Dot printing is performed on the printing paper 3 on the printing paper 2, and the thermal head 1 prints on the printing paper 3 while moving in the direction of the arrow along with the carrier 5. When one line of printing is completed, a line feed signal causes the thermal head to move along with the ink ribbon 4 to the printing paper 3 by an evacuation mechanism (not shown).
The printing paper 3 is retracted from the surface, moves in the direction of arrow B, and returns to the home position, and feed rollers R1 to R4 are driven to feed the printing paper 3 line feed in the direction of arrow C.

Here, the ink ribbon 4 is pressed against the print paper 3 by the thermal head 1 during printing, and as the thermal head 1 moves, it is sent out by the amount of movement from the delivery port of the ribbon cassette 8, and is taken up from the other winding port. It will be done.

[Problem that the invention seeks to solve]

According to the above conventional method, the ink ribbon 4 and the printing paper 3 do not move relative to each other, but at the same time an appropriately weak winding force is applied to the winding shaft 9 to prevent the ink ribbon 4 and the printing paper 3 from shifting, the thermal head 1 takes up the weak winding force. The ink ribbon 4 and printing paper 3 are pressed against the platen 2 by a force F0 that overcomes the force. Now, the coefficient of friction between the thermal head 1 and the ink ribbon 4 is μm (for example, 0
．． 1), the coefficient of friction between the ink ribbon 4 and the printing paper 3 is μ
2 (for example, 0.4), then μm <At μ2, the friction force between the ink ribbon 4 and the fixed printing paper 3 μt FG
is the frictional force μ+F between the thermal head 1 and the ink ribbon 4.

Since the ink ribbon 4 is larger than the printing paper 3, it is difficult for the ink ribbon 4 to cause relative "slippage" with the printing paper 3. However, the frictional force varies greatly and is unstable, and It is not possible to completely prevent such "misalignment".Therefore, there is a problem in that the printed surface becomes smeared due to carbon rubbing, impairing the printing quality.

Normally, when the transferred print is thin, the pressing force of the thermal head 1 is increased in order to make the print quality darker.
The pressing force is naturally limited because "slippage" occurs severely and print stains occur.

Means for Solving Problems c] The present invention is a ribbon feeding mechanism that includes a ribbon pressing means for pressing the ink ribbon at a position different from the pressing position of the print head, thereby solving the above problems. be able to.

[Effect]

According to the present invention, instead of the conventional method in which the ink ribbon is pressed against the printing paper only by the print head, i.e., the thermal head, in addition to the thermal head, a ribbon pressing means, i.e., the thermal head is used to control the printing position. A rail that overlaps a part of the width of the ink ribbon on the outside and is arranged parallel to the platen, and a roller are provided on the carrier, and by pressing the ink ribbon against the rail with the roller, the printing paper and the ink ribbon are separated. It is possible to prevent misalignment and improve the quality of printing.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 is a plan view showing an embodiment according to the present invention;
FIG. 2 is a side view of FIG. 1.

The same reference numerals indicate the same objects throughout the figures.

As shown in FIG. 1, a rail 10 is provided below and in parallel with the platen 2. Both ends of the rail 10 are fixed to a frame (not shown).

The rail 10 is made of, for example, a stainless steel thin plate, and a rubber plate 10a having a high coefficient of friction, for example, is attached to the front surface of the rail 10.

Rollers R3, l? are provided on the carrier 5a on the left and right sides of the thermal head 1. 4 is in position.

As shown in FIG. 2, the upper part of the ink ribbon 4 is pressed against the platen 2 through the print paper 3 by the thermal head 1, and the lower part of the ink ribbon 4 is pressed against the platen 2 through the rail 10 by rollers R5 and R6. has been done.

With such a configuration, when printing is performed, the thermal head 1 moves in the direction of the arrow in the above-mentioned pressing state, but at this time, the roller 115. l? 6 is the pressing force Fl, and the coefficient of friction between the rollers R5, R6 and the ink ribbon 4 is 7'31, the rubber plate 9a and the ink ribbon 4.
If the friction coefficient between is μ4, then METS+FO+μ3F, <
Since μ2Fo+μ4F+ and μx <</Ja, this relationship is unlikely to collapse.

Furthermore, even if the pressing force F0 is increased to make the print darker, the ink ribbon 4 is reliably pressed onto the rail 10 by the rollers R5, 176.

Therefore, it is possible to prevent misalignment between the ink ribbon 4 and the printing paper 3, and prevent staining of the printing surface, thereby preventing deterioration of printing quality.

In the above example, the rubber plate 10a is attached to the rail 0, but it goes without saying that other members may be used as long as they have a high coefficient of friction.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to prevent the ink ribbon from shifting on the printing paper surface during printing, so there is an effect that printing quality can be ensured without staining the printing surface.

[Brief explanation of drawings]

1 is a plan view showing an embodiment according to the present invention, FIG. 2 is a side view of FIG. 1, FIG. 3 is a plan view showing a conventional method, and FIG. 4 is a side view of FIG. 3. In the figure, 1 is a thermal head, 1a is a heating element, 2 is a platen, 3 is printing paper, 4 is an ink ribbon,
5 and 5a are carriers, 8 is a ribbon cassette, 10 is a rail, 10a is a rubber plate, and R5 and R6 are rollers. 1st officer

Claims (3)

[Claims] (1) A thermal transfer thermal printer device that prints on a print medium while pressing an ink ribbon with a print head, characterized by comprising a pressing means that presses the ink ribbon at a position different from the pressing position of the print head. Ribbon feeding mechanism. (2) The pressing means includes a rail that overlaps a part of the width of the ink ribbon outside the printing position of the print head and is arranged parallel to the platen member, and a roller that is provided on the carrier. 2. The ribbon feeding mechanism according to claim 1, wherein the ink ribbon is pressed against the rail by the roller. (3) The ribbon feeding mechanism according to claim 2, wherein the rail has a contact surface with the ink ribbon made of a member having a large friction coefficient.