JPS60176778A - Thermal printing head - Google Patents

Abstract

PURPOSE:To print with uniform density, by a construction wherein a major surface of a resistor substrate on which a plurality of heating resistors are provided is formed in a convexed curved line shape. CONSTITUTION:A thermal recording paper 31 is fed while pressing it by a platen roller 32 in a direction perpendicular to the longitudinal direction of a plurality of heating resistors provided on the resistor substrate 2. Both shaft rods 3201, 3202 for the roller 32 are pressed by springs or the like in the direction of an arrow 33, thereby pressing the paper 31 against the heating resistors. The surface of the substrate 2 on which the heating resistors are provided is formed in a convexed curved line shape with a substantially central part 35 of the substrate 2 as an apex, whereby the pressure exerted by the roller 32 is transmitted evenly to the paper 31.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a thermal printing head, and more particularly to a thermal printing head that improves contact between a heating resistor and thermal paper.

[Technical background of the invention and its problems]

In general, the thermal recording method is widely used in facsimile machines and office equipment, etc., and its configuration is to print one line with a thermal printing head in which a large number of minute heating resistors are arranged in the width direction of the paper, in pressure contact with each other, and a paper feed roller. Images are sequentially formed in the longitudinal direction of the paper by step feeding.

A bratin roller is usually used as a means for pressurizing the thermal printing head and the paper. Both ends of the platen roller are pressed against the paper by a spring or the like, and the paper and the thermal printing head are brought into pressure contact.

However, since the force that presses the platen roller against the paper is applied to both ends of the platen roller, the force that presses the platen roller against the paper is applied to both ends of the platen roller. The pressing force of the stain roller decreases. As a result, there is a risk that the print density on the paper will be different between the vicinity of the center and both ends of the platen roller in the longitudinal direction. Furthermore, there is a risk that the density of the print printed on the paper near the longitudinal center of the platen roller may become lighter or blur may occur.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned problems, and
It is an object of the present invention to provide a thermal printing head that can always maintain optimal print density despite having a simple structure.

[Summary of the invention]

In order to achieve the above-mentioned purpose, the shape of the whole surface of the resistor base on which a plurality of heating resistors are lined up is a convex curved shape, so that the pressure contact force between the paper pressed by the platen roller and the thermal printing head is reduced. Since it is approximately averaged, the print density is averaged.

[Embodiments of the invention]

Next, an embodiment of the thermal printing head of the present invention will be described with reference to FIGS. 1 to 4.

In Fig. 1, a resistive substrate (2) made of ceramic whose main surface (201) has a substantially convex curved shape in the elongated direction is bonded with silicone rubber on a heat dissipation substrate (1) made of iron. They are bonded together via a member (not shown).

On the main surface (201) of this resistance substrate (2), a plurality of heating resistors (20
2) is formed.

On the other hand, a plurality of driving integrated circuits (302) are arranged on the negative main surface (301) of the driving board (3).

The heating resistor (202) and the integrated circuit (302) are connected by a conductor wire (not shown).

In this way, the thermal printing head (4) of the present invention is constructed.

Next, the circuit configuration of the thermal printing head (4) will be explained with reference to FIG.

In FIG. 2, a plurality of heating resistors (1B) are arranged in rows at high density using thin film or thick film technology on a resistor substrate made of ceramic.

A driving integrated circuit α1 consisting of a shift register, a transistor, and a selector for driving this heating resistor α1) is formed on a driving substrate. One end of this heating resistor αD is connected to the output terminal (I9) of the driving integrated circuit (12+).
) are connected via conductive wires (2).

In addition, the other end αη of each heating resistor aυ is placed on the resistor board.
A common electrode (13) is formed in which the two are commonly connected.

On the drive board (= is a group of input signals (14) for selectively generating heat through each heating resistor I through the integrated circuit (one)
is formed. Furthermore, an output signal control terminal (151) of the driving integrated circuit (12+) and a power supply terminal α0 of the driving integrated circuit (121) are formed on the driving substrate.

Next, the actual printing operation of the thermal printing head shown in FIG. 1 will be explained using FIG. 3. Thermal paper 01) is fed while being pressed by a platen roller (c) along a direction perpendicular to the longitudinal direction of the plurality of heating resistors on the resistance board (2). Koru. This resistance board (2
) main surface (the surface on which multiple heating resistors are formed)
has the apex approximately at the center (35) of the resistor board (2),
Since it has a convex curved shape, the pressure applied from the platen roller (3rd floor) is transmitted evenly to the thermal paper Gυ.In other words, the pressure applied from the platen roller (3rd floor) is transmitted evenly to the thermal paper Since the same pressing force is applied to the thermal paper (31), the print density of the thermal paper (31) will not vary depending on the location.As a result, it is possible to prevent the print density of the thermal paper (31) from becoming thin or blurring. This convex curved shape is the height difference (34) between the top (in this case, the center part C35, but not necessarily the center part 051) and both ends of the resistance base (2). , A 4 Sa(su(210g)
m) is abbreviated as io.

A thickness of μm or less is sufficient, and a normal platen roller 02 can also be used.

Referring to FIG. 4, the operation of this thermal printing head will be described in detail. The thermal printing head (4) is attached to a copper rotating lever (41), The thermal printing head (4) is brought into pressure contact with the platen roller (43), which is rotated stepwise in the direction of arrow A by a stamping motor (not shown) to feed the paper and form an image.

Note that the resistance substrate and the drive substrate may be the same substrate. Further, the resistor substrate itself may have a convex curved shape, and the entire surface of the heat sink or the heat sink itself may have a convex curved shape so as to substantially match the convex curved shape.

Next, another embodiment of the present invention will be described with reference to FIGS. 5 to 7.

In Figure 5, the thermal printing head (4)
A drive board (3) is bonded onto a heat dissipation board (1) via a silicone rubber adhesive member (not shown).

On this drive board (3), there is a resistance board (2) made of ceramic whose entire surface is substantially convex in the longitudinal direction.
They are bonded together via a silicone rubber adhesive member (not shown). The thermal printing head (4) shown in Fig. 5 uses a laminated type for each substrate, so the size of the thermal printing head (4) can be made small, and the laminated type also reduces the strength of each substrate. By reducing the thickness of each substrate, the use of expensive ceramic substrates can be reduced.

In Figure 6, the thermal printing head (4)
In the example of ++h, the resistor board (2) in FIG.
It itself has a convex curved shape. Accordingly, the entire surface of the drive board on which the resistor board (2) is placed has a convex curve shape that substantially matches the convex curve shape of the resistor board itself.

In FIG. 7, in another embodiment of the thermal printing head (4), in addition to the one shown in FIG. 6, the drive board (3) itself has a convex curved shape,
The whole surface of the heat dissipation board on which the drive board (3) is placed has a convex curved shape so as to substantially match the convex curved shape of the drive board.

By the way, the resistance board (2) and the drive board (3) are 1f.
If the tensile coefficients are different, if it is operated for a relatively long time,
A phenomenon occurs in which the printed part is warped concavely, and the pressing force between the central part of the printed part and the platen roller is reduced, and as a result, the printed density of the thermal paper may become thinner or the paper may peel off. In order to prevent this phenomenon,
As shown in Japanese Patent No. 7596, a structure is known in which a backing correction plate made of the same material as the thermal printing head is attached, but this thermal printing head has a large external size and a large weight Kk.

However, with the structure shown in FIG. 7, there is no change in the convex curved shape of the resistor board itself, extremely stable printing is possible, and the thermal printing head can be made smaller.

In the thermal printing head shown in FIG. 8, the heat sink itself also has a convex curved shape. When using a thermal printing head of this type, even if the coefficients of thermal expansion of the resistor board (2), drive board (3), and heat dissipation board (1) are different, the force generated by thermal expansion will be as shown by the arrow (61). ), there is no change in the convex curved shape of the resistor board, and extremely stable printing is possible.
In addition, the thermal printing head becomes smaller and lighter. In addition, the warpage (62) of this heat dissipation board is approximately 100 μmlJ in the case of an A4 size thermal printing head.
Since it is below, there is no problem when implementing it in facsimile etc.

Note that when the thermal printing head having the structure shown in FIG. 8 is used, the thermal printing head can be formed by appropriately combining the substrates that are warped during the formation of the respective mounting plates. Furthermore, by appropriately combining warped boards, the reliability of the wiring connecting each board can be improved. Furthermore, since the adhesion between the resistive substrate, the driving substrate, and the heat dissipating substrate is the same as above, the heat conduction from the heat generating resistor is good, and the influence on the driving substrate is reduced, so that stable circuit operation can be guaranteed.

〔Effect of the invention〕

By adopting the above-mentioned configuration, the thermal printing head of the present invention has a convex curved shape of the whole surface of the resistor base on which the plurality of heating resistors are lined up, so that the thermal printing head can be easily connected to the paper pressed by the platen roller. Since the pressure contact force with the printing head is approximately averaged, the print density is averaged.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an embodiment of the thermal printing head of the present invention, Fig. 2 is a circuit diagram of the thermal printing shown in Fig. 1, and Figs. 3 and 4 are the thermal printing head shown in Fig. 1. A schematic diagram showing the operating state of the printing head, and FIGS. 5 to 8 are schematic sectional views showing other embodiments of the thermal printing head of the present invention. (1)...Heat dissipation board, (2)...Resistance board (3)...
...Driver board, (201), (11)...Heating resistor (302), (121...Driver integrated circuit Agent: Patent attorney Noriyuki Chika (and one other person) Fig. 2 Fig. 3 Fig. 4 Fig. 5\4 Fig. 6'X-η Fig. 7 Fig. 8

Claims (5)

[Claims] (1) A heat dissipation base, a resistance base formed on the heat dissipation base made of a high-resistance base material whose whole surface has a substantially convex curved shape, and a resistor base formed on the heat dissipation base which has a substantially convex curved shape on its whole life surface. A thermal printing head comprising a plurality of heat generating resistors arranged side by side, and a color driving base having drive wiring for driving the plurality of heat generating resistors formed on the heat dissipating base. . (2) The thermal printing head according to claim 1, wherein the resistor base itself has a substantially convex curved shape. (3) The resistance base and the drive base are the same base, and the surface of the heat dissipation base on which the resistance base and the drive base are placed substantially matches the convex curved shape of the resistance base itself. 3. The thermal printing head according to claim 1, wherein the thermal printing head has a convex curved shape or the heat dissipating base itself substantially matches the convex curved shape of the resistive base itself. (4) The multi-mullinting head according to claim 1, wherein the resistance base is placed on the drive base. (5) The surface of the drive base on which the resistance base is placed has a convex curve shape that substantially matches the convex curve shape of the resistor base itself, or the drive base itself has a convex curve shape that is similar to the convex curve shape of the resistor base itself. Thermal printing head (6) according to claims 2 and 4, characterized in that the thermal printing head (6) has a shape that substantially matches the shape of a curved line. or the heat dissipation base itself has a convex curve shape that substantially matches the convex curve shape of the resistor base itself, or the heat dissipation base itself has a convex curve shape that substantially matches the convex curve shape of the resistor base itself. Thermal printing head.