JP2605825Y2 - Thermal head - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal head used for a printer or the like.

[0002]

2. Description of the Related Art A thermal head used in a printer or the like has a large number of heating resistors arranged on a ceramic substrate made of Al ₂ O ₃ or the like in a direction perpendicular to a feeding direction of a thermal recording paper. The resistive element selectively generates heat by applying a voltage to cause a coloring reaction on the thermosensitive recording paper to record information. Therefore, heat generation at the time of circuit connection and printing becomes a problem, and a heat dissipation structure is required. In general, this type of thermal head is mounted with a temperature measuring element such as a thermistor to detect the temperature of the head.

FIGS. 4 to 6 show a conventional example of a thermal head of the joining type provided with such a temperature measuring element. This is briefly described below. 1 is a ceramic substrate on which a heating resistor 2, lead electrodes, connection terminals 3 and the like are formed by printing,
Reference numeral 4 denotes a circuit board. The circuit board 4 includes a backing board 4A made of glass epoxy or the like and a flexible printed board 4A.
B. 6 is a heat sink made of aluminum alloy, 7 is a protective cover also made of aluminum alloy, 8 is a set screw for fixing the protective cover 7 and the circuit board 4 together to the heat sink 6, 9 is a driver IC, 10 is a thermistor, 1
1 is a thermal recording paper, 12 is a platen roller, and 13 is an elastic member such as silicon rubber. In this bonding type thermal head, a ceramic substrate 1 and a circuit substrate 4 are placed on a heat sink 6, a control circuit portion of a flexible printed circuit board 4B is superimposed on a connection terminal 3 portion of the ceramic substrate 1, and these are protected by a protective cover. 7 and is electrically connected via an elastic member 13. In addition, Sera
The mix substrate 1, the circuit board 4 and the heat sink 6 are shown in FIG.
The long side is long enough to the short side.
The heating resistor 2 has a length substantially equal to that of the ceramic substrate 1.
Have

The thermistor 10 for temperature measurement has its lead 15 connected to the circuit of the flexible printed circuit board 4B by solder 16 and arranged below the backing board 4A. Storage recess 17
And is sealed by an insulating material 18 having high viscosity and high thermal conductivity such as silicon grease. The temperature measurement by the thermistor 10 is arranged closer to the circuit board 4 because more uniform temperature control can be achieved by measuring the temperature regardless of the positions of the dots of the heating resistor 2. The reason for embedding in the heat radiating plate 6 is that simply arranging it on the flexible printed circuit board 4B has a low heat conductivity and cannot measure the temperature accurately. In addition, a through hole 19 for heat radiation is formed in the protective cover 7 corresponding to the storage recess 17.

[0005]

However, the conventional thermal head described above has a problem that the processing cost of the heat radiating plate 6 is increased because the accommodating recess 17 must be formed in the heat radiating plate 6. When assembling the thermal head, the thermistor 10 is inserted into the storage recess 17.
(The length of the lead wire 15 may not be too long or too short).
B (or the backing substrate 4A), and the thermistor 10 mounted on the circuit board 4 protrudes below the backing substrate 4A. Damaged,
Alternatively, there is a problem that the lead wire 15 may be bent, which causes a manufacturing failure.

Accordingly, the present invention has been made in view of the above-mentioned conventional problems, and has as its object to eliminate the necessity of forming a storage recess in a heat sink and to break a thermistor during assembly. An object of the present invention is to provide a thermal head which is excellent in assembling workability without fear of bending or bending a lead wire.

[0007]

In order to achieve the above object, a thermal head according to the present invention has a long side with respect to a short side.
It is formed long enough and is approximately equal to the long side
Rectangular ceramic substrate with a heating resistor
A predetermined for driving the heating resistor of the ceramic substrate
The wiring board with the wiring pattern of
A circuit board that is formed by stacking
A heat plate, and the ceramic substrate and
Most of the back of the circuit board adheres to the heat sink
So that the wiring board and the backing board overlap
A through hole is formed at a predetermined position on the combined circuit board.
Inserting a temperature measuring element in the through hole and thermally conductive insulation
Filling the material until it reaches the heat sink,
And the temperature measuring element measures the temperature of the heat sink.
It is made possible .

[0008]

Since the temperature measuring element is housed in the hole formed in the circuit board, there is no need to form a housing recess on the heat radiating plate. No bends.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings. FIG. 1 is a sectional view of a main part showing an embodiment of a thermal head according to the present invention, and FIG. 2 is a plan view of a main part before a thermal conductive insulating material is filled. The same components as those of the conventional head shown in FIGS. 4 to 6 are denoted by the same reference numerals, and detailed description thereof will be omitted. In these figures, in this embodiment, holes 21 and 22 larger than the thermistor 10 are formed in the backing substrate 4A and the flexible printed circuit board 4B forming the circuit board 4 so as to communicate with each other. And the lead 15 is connected to the flexible printed circuit board 4B.
And the protective cover 7 corresponding to these holes 21 and 22 is provided with a through hole 1 for heat radiation.
9, the holes 21 and 22 are filled with a heat conductive insulating material 18 such as silicon grease through the through holes 19, and the thermistor 10 is sealed. Therefore, no processing for attaching the thermistor is performed on the heat sink 6 itself.

When the thermistor 10 is mounted, the backing substrate 4A is positioned close to the surface of the radiator plate 6.
Is inserted and arranged in the hole 21. Further, the lead wire 15 of the thermistor 10 is substantially parallel to the plane direction of the backing substrate 4A,
The leading end is bent toward the flexible printed circuit board 4B, inserted into the lead wire insertion hole (not shown) provided in the flexible printed circuit board 4B from the backing circuit board 4A side, and has a protruding end projecting toward the protective cover 7 side. It is connected to the circuit of the flexible printed board 4B by the solder 16. The other configuration is the same as the above-described conventional structure.

In the thermal head having such a configuration, since the thermistor 10 is incorporated in the hole 21 of the backing substrate 4A, the thermistor 10 is provided in the heat radiation plate 6 itself.
No processing is required for the heat sink 6, and therefore, the manufacture of the heat sink 6 is simple and easy. In this case, even if the thermistor 10 is not incorporated in the heat sink 6, the heat of the heating resistor is transmitted to the thermistor 10 via the heat sink 6 and the heat conductive insulating material 18, so that the temperature is good as in the conventional case. Can be measured. Further, since the thermistor 10 is housed and arranged in the hole 21 of the backing substrate 4A and is protected by the backing substrate 4A itself, the circuit board 4 is poorly handled at the time of assembling work, or stored over when the circuit board 4 is stored. Even if the thermistor 10 is not broken or its lead wire 15 is bent, the assembling work of the thermal head can be performed satisfactorily.

[0012]

[0013]

As described above, in the thermal head according to the present invention, a hole is formed in a circuit board, a temperature measuring element is inserted in the hole, and sealed with a heat conductive insulating material. It is not necessary to form a hole for a temperature measuring element in itself, and the manufacture of a heat sink is easy. In addition, since the temperature measuring element is housed and arranged in the hole of the circuit board, the circuit board is easy to handle. Even if the circuit boards are overlapped, the temperature measuring element may be damaged or its lead wire may be bent. Therefore, the workability of assembling the thermal head can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part showing an embodiment of a thermal head according to the present invention.

FIG. 2 is a plan view of a main part before filling with a thermally conductive insulating material.

FIG. 3 is a sectional view of a main part showing another embodiment of the present invention.

FIG. 4 is an exploded perspective view of a conventional thermal head.

FIG. 5 is a sectional view of the head.

FIG. 6 is a cross-sectional view of a main part showing a mounting structure of a thermistor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ceramic board 2 Heating resistor 4 Circuit board 4A Backing board 4B Flexible printed board 6 Heat sink 7 Protective cover 12 Platen roller 15 Thermistor 18 Thermal conductive insulating material 21 Hole 22 Hole

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B41J 2/345

Claims (1)

(57) [Scope of request for utility model registration] 1. A long side is formed sufficiently long with respect to a short side.
And a heating resistor having a length substantially equal to the long side.
Rectangular ceramic substrate and the front of this ceramic substrate
The specified wiring pattern for driving the heating resistor
The formed wiring board and backing board are overlapped and formed
Circuit board, and a heat sink having a large surface area,
Place the ceramic substrate and the circuit board on the heatsink
Most of the surface is placed close to the heat sink so as to be in close contact with the heat sink,
A circuit board on which the wiring board and the backing board are overlapped
A through hole is formed at a predetermined position, and a temperature measuring element is
And insert the heat conductive insulating material to the heat sink.
Until the temperature measurement element is sealed,
A thermal head, wherein a measuring element can measure the temperature of the heat sink .