JPS6072761A - Platen support mechanism for thermal printer - Google Patents

Abstract

PURPOSE:To bring a heat generating body of a thermal head into smooth contact with the printing surface of the platen under any circumstance by arranging the platen to always tilt the printing surface thereof upward while being held with a coil spring. CONSTITUTION:The platen 11 is fitted with a coil spring 13 at the bottom thereof opposite to the printing surface thereof to be held so as to turn slightly upward on the side of the printing surface thereof from the level. The platen 11 is tilted at an obtuse angle theta with the thermal head 14 due to reduction thereof 11 or others and abbuts on the thermal head. In this case, receiving a compression force of the coil spring 13, the platen 11 turns in the direction X centered on the platen shaft 12 and the thermal head 14 turns in the direction Y. Thus, the platen 11 gets tight on the bottom of a heat generating body 15 of the thermal head 14 at the bottom of the printing surface 11b thereof 11 and then, the printing surface 11b of the platen 11 comes in contact with the heat generating body 15 accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a support mechanism for a platen in a thermal printer.

[Technical background of the invention and its problems]

Figure 1 shows an example of a platen support mechanism in a conventional thermal printer (2). In the figure, (1) is a fixed platen, and the printing surface (1a
) rotates around the head shaft (2), and the print head (3) (two attached heat generating elements (4)) are sandwiched between multiple pairs of paper feed mechanisms (5A) and (5B) and fed. The paper (6) and the ink ribbon can come into surface contact via force. However, the upper platen (
If the platen (1) is not installed horizontally, or if the platen (2) is not held horizontally during use (2)
A gap was generated between the printing surface (1a) of 1) and the heating element (4), and complete surface contact could not be obtained, which caused an adverse effect on printing quality. Therefore, conventionally the platen (1
), it was necessary to make adjustments to install the unit horizontally, or the parts needed to be highly accurate.

Further, FIGS. 2 and 3 show other examples. In the figure, (1') is a platen that can rotate around the platen shaft (1b), and this platen (1')
When the platen (1') and the print head (3) are rotated clockwise as shown in Figure 2 (2), the platen (1') and print head (3) are separated, and when rotated clockwise as shown in Figure 3 (2), the platen (1') and print head (3) are separated. Even when the platen (1') and the print head (3) are rotated clockwise (two rotations), there is a possibility that the platen (1') and the print head (3) may become separated from each other.

[Purpose of the invention]

The present invention has been made based on the above circumstances, and although the construction is relatively simple, the platen and the print head can come into surface contact with each other in any case without mating, and the pressing force can be reduced. The purpose of the present invention is to provide a platen support mechanism for a thermal printer that is capable of improving print quality, and also allows for more reliable feeding of the ink ribbon in thermal transfer printers (-). .

[Summary of the Invention] The present invention provides a rotatable thermal head whose end is pivotally supported, and a rotatable thermal head that faces the heating element of the thermal head and is located slightly closer to the thermal head than the center of gravity. It is characterized by having a rotatable platen tilted upward and an elastic member elastically supporting the lower part of the non-printing side of the platen.

[Embodiments of the invention]

Hereinafter, the present invention will be explained based on an embodiment 1'' shown in FIGS. 4, 5, and 6.
υ is a rotatable platen that rotates twice around the platen shaft (■υ center of gravity (lla)
lb) side (two-sided. Therefore, the above-mentioned platen kick is centered on the platen shaft) CI,
Due to its own weight, it is always supported so that it is facing upwards.
An elastic member such as a coil spring (1) is attached to the second part to elastically push up the platen (11), and the platen (11) is held so that the printing surface side is slightly upward from the horizontal state. The bleeding occurs on the printing surface of the platen I (
llb) (: A thermal head having heating elements tI51 facing each other, this thermal head fi4) is configured so as to be able to rotate around a head shaft butterfly Q pivotally supported at the end.

(17A) and (17B) are the platen μm)
(1 frame is the printing surface (ll) of the thermal head (one heating element 051 and platen u1)
b) Two ink ribbons are placed between the paper (P) and the two sheets of paper (P).

Next, the operation of the present invention based on the above structure will be explained with reference to FIGS. 5 and 6.

Figure 5 shows a case where the platen (11) is tilted and comes into contact with the thermal head ([4) due to shrinkage etc. (secondary platen l11) and the thermal head ([4)] at an obtuse angle (θ). It is. In this case, platen I is coil spring 1
In order to receive the compressive force of t3), the platen shear 7) (
121 as the center, in the direction of arrow
The lower part of the printing surface (llb) of 11) and the lower part of the heating element of the thermal head I are in close contact with each other, and then the lower part of the printing surface (llb) of
- As shown, the printing surface (ii, b) of the platen I and the heating element ttS of the thermal head circle can be brought into contact with each other reliably.

Figure 6 is the opposite (= platen (11) is the cause of expansion etc.)
This figure shows a case where the second lug platen (Ll) and the thermal head (14) are inclined at an acute angle (θ') and come into contact with each other. In this case, the platen t (11) rotates twice in the force direction of the arrow X' around the platen shaft (1) due to its own weight, and this (the thermal head I without
rotates twice in the direction of arrow Y. Therefore, first
As shown in a), the printing surface (llb) of the platen (11)
The upper part and the heating element (1!9) of the thermal head ([4) come into close contact, and then, as shown in FIG.
L4)'s heating element (L4) can definitely be brought into contact with the seagull.

In this way (2. The above platen I is caused by its own weight on the printing surface ()
1b) is tilted upward, and the pushing force of the coil spring is acting, so the platen (1) is held slightly upward and tilted in any case. be.

〔Effect of the invention〕

As explained above (according to the present invention), the heating element of the thermal head can make smooth contact with the printing surface of the platen without reducing the pressing force, which improves printing quality. In addition, the ink ribbon can be fed in a refreshing manner in a thermal transfer printer (-).Furthermore, the present invention can be applied to a thermal printer as well.

[Brief explanation of drawings]

Figure 1 shows a conventional platen support 41 to which the platen is fixed.
1A structure, FIGS. 2 and 3 are front views showing a conventional platen support mechanism in which the platen is rotatable (supported on two axes), and FIG. 4 is a front view showing a platen support mechanism according to an embodiment of the present invention. (L+1 is an explanatory diagram showing the state of complete contact when the platen of the same mechanism is contracted. Figure 6 1al, (b) is also an illustration when the platen of the same mechanism is expanded. 11... Platen lla... Center of gravity 11b... Printing surface 12... Shaft for platen 13... Coil spring (elastic member) 14. ...Thermal head 15
... Heating element 16 ... Head shaft representative Patent attorney Mr. Inoue Figure 5 (d)

Claims (2)

[Claims] (1) Thermal printer (position 2, with a rotatable thermal head whose end is supported on a shaft, facing the heating element of this thermal head, and the center of gravity is slightly on the side of the thermal head (position 2) facing the heating element of this thermal head. supported, and its own weight (two points)
(= A platen support mechanism for a thermal printer, comprising a tilted and rotatable platen, and an elastic member that elastically supports the lower part of the non-printing surface of the platen. (2) The platen support mechanism for a thermal printer according to claim 1, wherein the elastic member is a coil spring.