JPS613757A - Thermal head - Google Patents

Abstract

PURPOSE:To upgrade the print quality by fixing with a bond an auxiliary plate having a specific coefficient of linear expansion between an insulating board and a radiant plate. CONSTITUTION:In a thermal head composed of at least a group of the heating resistors 21 mounted over one of surfaces of an insulating board 22, an auxiliary plate 25 is inserted between the other surface of the insulating board 22 and a radiant plate 24 and fixed with a bonding material 231, 232 and while a group of heating resistors 21 is driven continuously, the relations T0>Ts>T1,alpha0<alphas<alpha1 and alpha0T0=alphasTs=alpha1T1 are satisfied where T0,Ts,P1 and alpha0,alphas,alpha1 are respectively the temperature and the coefficient of linear expansion of the insulating board 22, the auxiliary plate and the radiant plate 24. According to such constitution the print quality is excellent as a group of heating resistors 21 and a platen roller always have a tight contact uniformly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a thermal head, and particularly to an IT! ! To extremely minimize deformation during continuous driving of a heat generating resistor group of a thermal head having at least a heat generating resistor group adhered and formed on one surface of an edge substrate and a heat sink fixed to the other surface via an adhesive. This relates to a thermal head that is capable of

[Technical background of the invention and its problems]

The thermal head is widely used in facsimile IJ and other equipment, and at least the common electrode group, backflow prevention diode group, heating resistor group, and wiring group that connects these are made of ceramics. A group of heat-generating resistors is selectively heated by an external signal, and a thermal paper fed by a platen roller is placed in close contact with the group of heat-generating resistors. Text and images can be printed on normal lines through the printer.

For this reason, when the heat generating resistor group is continuously driven, the insulating substrate on which the heat generating resistor group is adhered accumulates heat due to the heat generating resistor group and active element driving, so a heat sink is usually fixed to the other surface with adhesive. has been done.

Next, the main parts of a conventional thermal head will be explained with reference to FIG. That is, the other side of the insulating substrate Out, on which the heating resistor group aυ is adhered and formed on the negative side, is heated to a certain thickness for about 0.2 ms+.
) is fixed to a heat dissipation plate I made of an Fe alloy spear alloy or the like via an adhesive 0.

However, when this thermal head is driven for printing, the temperature of the insulating substrate α2 rises due to the heating resistor group (11), and this heat is transferred to the heat sink (14) K via the adhesive 0. , insulating substrate (lzO linear expansion coefficient (
α. ) and the linear expansion coefficient (α, ) of the heat sink I. (Due to the relationship of As a countermeasure to this problem, a structure in which the heat sink I is curved in the opposite direction in advance or a structure shown in Publication of Utility Model Publication No. 56-25874 have been considered, but the former method depends on the manufacturing method and the degree to which it is curved. In addition, since the latter uses a clamp member, the thermal head becomes larger, and the linear expansion coefficients of the insulation board, clamp member, and heat sink are different, so the thermal head There is a problem that unexpected deformation occurs in the print itself, and the print quality drops by (11).

[Purpose of the invention]

The present invention has been made in view of the above-mentioned two problems, and it is an object of the present invention to provide a thermal head capable of improving print quality.

[Summary of the invention]

That is, in the thermal head according to the present invention, in which at least a group of heating resistors is formed on one surface of an insulating substrate, Il.
An auxiliary plate is inserted and fixed to the other surface of the substrate h, s and each heat sink through adhesive, and the temperature of the insulating substrate, the auxiliary plate, and the heat sink when the heating resistor group is continuously driven is T. +
TR+'r, l linear expansion coefficient α, respectively. , α3
．． When α, To>Ts>T+, α0<α6
〈α, and α. T(1=αs Ts−α1TI is set to 1 to satisfy the relationship,
＃＋The board is ceramic, the auxiliary board is SPC, and the heat sink
In the embodiment, □ is A3052P.

[Examples of the invention]

Next, an embodiment of the thermal head of the present invention will be described with reference to FIG.

That is, the other side of the insulating substrate 12, on which the heating resistor group 01) is adhered and formed on the - side, and the heat dissipation plate (incorporated) are assisted by using, for example, rubber thread adhesive (23□) (2at). The plate function has been inserted and identified.

With this structure, the bonding length L) is 280 mm, and the insulating substrate (
b) is the linear expansion coefficient α. = 7X10-' ceramics, auxiliary plate (A) and linear expansion coefficient α5 = 12X10-
JI8 standard spc of ', heat sink (241 as linear expansion coefficient α, = 23X 10-' JIS intellectual grade A305
Thermal conductivity Cal/cm − when using 2P respectively
The relationship between temperature and elongation (fin) during continuous operation at sac/°C is shown in the table below.

The difference in elongation is 0.0 between the auxiliary board and the insulating board C.
67 stiffness, 0.06 stiffness between heat sink (2) and auxiliary plate (a), and the difference in stiffness is, for example, rubber thread adhesive (23+), (
The thickness of the P and N substrates (23t) is set to a value that can absorb even 0.03m of t, and as a result, the P and N substrates (2 m) do not curve, and are adhered to the −・face of this 1m substrate. The close contact between the heating resistor group 01) and the platen roller becomes uniform, making it possible to improve the print quality.

[Effect of invention,]

As described above, according to the present invention, the heating resistor group (11) and the platen roller are always in uniform contact with each other even during printing, so the printing quality is good, and the printing process is easily stabilized and uniform. The product can be made small and inexpensive, and since the thickness of the adhesive can be made thinner, the heat dissipation effect is also high, and a thermal head that can easily perform high-speed printing can be provided.

[Brief explanation of the drawing]

2.1 Figure is a perspective view showing one embodiment of the thermal head of the present invention, Figures 2 and 3 are views showing conventional thermal heads, Figure 2 is a perspective view when not driven, Figure 3 is a perspective view showing an embodiment of the thermal head of the present invention. The figure is a perspective view during driving. 11.21 - Heat generating resistor group 12.22... Insulating substrate 13, 23+, 23t... Adhesive 14.24
・・・Radiation plate 25 Auxiliary plate agent Patent attorney Inoue - Male Figure 1 Figure 2

Claims (2)

[Claims] (1) In a thermal head in which at least a group of heating resistors is adhered and formed on one surface of an insulating substrate, an auxiliary plate is inserted and fixed between the other surface of the insulating substrate and the heat sink via an adhesive, and The temperatures of the insulating substrate, the auxiliary plate, and the heat sink during continuous operation of the heating resistor group are T.
_O, T_S, T_1, linear expansion coefficient α_O,
When α_S and α_1, T_O>T_S>T_1,
α_O<α_S<α_1 and α_OT_O=α_ST_
A thermal head characterized by satisfying the relationship S=α_1T_1. (2) The thermal head according to claim 1, wherein the insulating substrate is made of ceramic, the auxiliary plate is made of SPC, and the heat sink is made of A5052P.