JPS59178269A - Thermal head - Google Patents

Abstract

PURPOSE:To eliminate unevenness in drop of voltage and permit printing undergoing no fluctuation in density by a thermal head wherein a connection conductor of a common electrode is provided separate from and substantially in the same plane as a circuit board for supplying a driving current to individual separate electrodes. CONSTITUTION:A thermal head comprises an insulating substrate 12 formed of a semi-cylindroidal electric insulator such as glass, which is provided at its top with a plurality of heating resistors 11 made of electric resistors, and a heat radiating plate 13 which is formed of a conductive metal such as aluminum and to which is mounted the substrate 12. A common electrode 15 is so constituted that it is commonly connected on the base end side thereof through a connection electrode 16 for each of the heating resistors 11 in the predetermined number. Separate electrodes 14 and the common electrode 15 are provided on the insulating substrate 12 facing each other with the respective heating resistors 11 therebetween. When a driving current is supplied to the side of the separate electrodes 14, the corresponding heating resistors 11 are heated to make print recording on a heat sensitive recording medium of heat sensitive paper.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal head used for performing thermal recording on a thermal recording medium such as thermal recording paper.

[Background technology and its problems]

Conventionally, individual electrodes of each heating resistor are taken out alternately on both sides of a plurality of heating resistors formed on an insulating substrate such as a glass substrate, and a common electrode facing the individual electrodes is placed between the heating resistors. A thermal head constructed as shown in FIGS. 1 and 2 has been proposed as a thermal head in which the heating resistor generates heat. The thermal head shown here has a cylindrical insulating substrate 1 made of an electrical insulator such as glass, and a plurality of heating resistors made of electrical resistance arranged in parallel in the longitudinal direction of the insulating substrate 1. Provide body 2,
Individual electrodes 3 of each heating resistor 2 are taken out alternately on both sides of the heating resistor 2, that is, alternately from one end and the other end of the heating resistor 2 arranged in parallel in the longitudinal direction on the insulating substrate 1. Individual electrodes 3 are provided to extend. moreover,
A common type &4 is provided to extend from the other end or one end of the heating resistor 2 provided so that the individual electrode 3 extends from one end or the other end, and the individual electrode 3 and the common electrode 4 are connected to the heating resistor 2. The base ends of each common electrode 4 are commonly connected to a predetermined number of heat generating resistors 2 through a connection electrode 5, and one end side of each heat generating resistor 2 and The common type $i4 provided for each common electrode 4 extending to the other end side serves as a common electrode for each heating resistor 2.

As mentioned above, the heating resistor 2, the individual electrodes 3 and the common electrode 4
The insulating substrate 1 provided with the above is fitted with a V-shaped groove 7 formed on one end surface of the drive circuit board 6, which has a drive circuit pattern connected to the individual electrodes 3 and the common electrode 4 on both sides thereof. I'm being kicked.

At this time, the heating resistor 2 is arranged so as to face the top of the insulating substrate 1, as shown in FIG. The drive circuit patterns formed on both sides of the drive circuit board 6 include an individual electrode pattern 8 corresponding to each individual electrode 3 connected to each individual electrode 3, and one drive circuit pattern formed on one side connected to the common electrode 4. A lead frame 10 is connected to each common electrode pattern 9 by soldering between each individual electrode 3 and each individual electrode pattern 8 and between each common electrode 4 and common electrode pattern 9 for electrical connection. has been done.

By the way, in the conventional thermal head configured as described above, there is one location between the common electrode 4 common to the plurality of heating resistors 2 and the common electrode pattern 9 on the drive circuit board 7 on both sides of the drive circuit board 7. Since each of the heating resistors 2 is connected in reverse by the lead frame 10, the voltage drop caused by the common electrode 4 of these heating resistors 2 when a drive current is supplied from the individual electrodes 3 to cause each heating resistor 2 to generate heat is reduced. In the above thermal head, the heat generation temperature of each heating resistor 2 is not constant, and the heating temperature of each heating resistor 2 varies. In order to connect the common electrode 4 on the insulating substrate 1 and the common electrode pattern 9 on the drive circuit board 7 to the lead frame 10,
It is necessary to align them with each other, making it difficult to improve production efficiency.

Furthermore, since the individual electrode patterns 8 to which the individual electrodes 3 are connected and the common electrode patterns 9 to which the common electrodes 4 are connected are mixedly formed on the same surface on the drive circuit board 7, complicated wiring is required. There are manufacturing difficulties.

[Purpose of the invention]

The present invention was proposed for the purpose of solving the drawbacks of the conventional thermal head as described above.
To provide a thermal head which eliminates inconsistency in voltage drop caused by a common electrode of a heating resistor, enables high-quality printing with little density unevenness, improves production efficiency, and is easy to manufacture. With the goal.

[Summary of the invention]

Therefore, in order to achieve the above-mentioned object, the present invention alternately takes out the individual electrodes of each heating resistor on both sides of a plurality of heating resistors formed on an insulating substrate, and the individual electrodes of the heating resistors are sandwiched between the heating resistors. In a thermal head in which heat is generated by the heat generating resistor through a common electrode opposite to the heat generating resistor, the heat generating resistor is separate from a circuit board that supplies a drive current to the individual electrodes and is substantially on the same plane as the surface of the circuit board. A connecting conductor for the common electrode is arranged.

〔Example〕

An example of the present invention will be described below with reference to the drawings.

As shown in FIG. 3, the zaruhesod according to the present invention is made of an electrically insulating material such as glass in the shape of a semi-elliptic cylinder and having a plurality of heating resistors 11 made of electrical resistors on the top. An insulating substrate 12 formed of
The heating resistors 11 are arranged in parallel in the longitudinal direction on the top of the insulating substrate 12, and the heating resistors 11 are arranged in parallel in the longitudinal direction on the top of the insulating substrate 12. On both sides of the resistor 11, a fourth
As shown in the figure, the individual electrodes 14 of each heating resistor 11 are taken out alternately, that is, the individual electrodes 14 of each heating resistor 11 are taken out alternately from one end and the other end of the heating resistors 11 arranged in parallel in the longitudinal direction on the insulating substrate 12. The common electrode 15 is provided so as to extend from the other end or one end of the heating resistor 11, which is provided so that the individual electrode 14 extends from one end or the other end. There is. These common electrodes 15 are configured such that their base ends are commonly connected to each predetermined number of heating resistors 11 by a connecting electrode 16. and,
The individual electrodes 14 and the common electrode 15 are provided on an insulating substrate 12 facing each other with each heating resistor 11 in between, and when a driving current is supplied from the individual electrode 14 side, the heating resistor 11 generates heat. The apparatus is configured to print and record on a predetermined heat-sensitive recording medium such as heat-sensitive recording paper.

As described above, a heat sink 13 is provided with several insulating substrates 12 provided with heating resistors 11, individual electrodes 14, and common electrodes 15.
Individual electrode patterns 1 are respectively connected to the individual electrodes 14 and supply a drive current from a predetermined drive circuit to the individual electrodes 14 to drive the heating resistor 11 to generate heat.
A drive circuit board 18 having 7 formed thereon is bonded and disposed. Further, a fitting protrusion 20 is provided on one end surface of the heat dissipation plate 13, into which a fitting groove 19 formed at the base end of the insulating substrate 12 is fitted, and into which the insulating substrate 12 is attached. Fitting protrusion 2
On both sides of the base end side of the heat dissipation plate 13, there are flanges 2 that serve as connection conductors to which the common electrode 15 is connected so as to protrude laterally of the heat sink 13.
1 is formed protrudingly over the entire width of the heat sink plate 13. The flange portion 21 is formed to protrude so as to be substantially flush with the pattern surface of the drive circuit board 18 disposed on both sides of the heat sink 13 . Furthermore, the width of the flange 21.21 is approximately the same width as the width of the proximal end of the insulating substrate 12.
It is attached to the heat dissipation plate 13 by fitting into the fitting protrusion 20 and placing it on the flange 21.21. When the insulating substrate 12 is placed on the heat sink 13 in this way, the heat sink 13
On each side surface side, the base end side of the individual electrodes 14 on the insulating substrate 12, the connection electrode 16 of the common electrode 15, the π111 plane of the flange 21, and the pattern plane of the drive circuit board 18 are located on approximately the same plane. I come to do it. Then, each individual electrode 14 on the insulating substrate 12 and each individual electrode pattern 17 on one drive circuit board 18 are connected by a method such as a wire punch ink using a thin wire 22 such as a silver wire. It's a trench.
Connection electrode 16 of common electrode 15 on insulating substrate 12 and collar part 2
1 is also connected at several points by a method such as wire bonding using a thin wire 23. In particular, in this example,
Since the flange 21 protruding from the heat sink 13, which serves as a connection conductor to which the common electrode 15 on the insulating substrate 12 is connected, can be made to face the entire width of the insulating substrate 12,
A desired number of thin wires 2 are connected between the common electrode 15 and the flange 21.
You can connect with 2. Therefore, when the drive current is supplied to the heat generating resistor 11 from the individual electrode 14 side, it is possible to connect only the portions that are sufficient to eliminate the uneven voltage drop on the common electrode 15 side. Note that a connection layer formed by plating silver on nickel plating is provided on the side surface of the flange portion 21 where the thin wire 22 is connected.

Furthermore, a terminal for leading out the common electrode is provided at one end of the heat sink 13.

〔Effect of the invention〕

As described above, the present invention provides a circuit board that is separate from a circuit board that supplies a drive current that causes a heat-generating resistor to generate heat to individual electrodes on an insulating board, and that the above-mentioned circuit board is provided on substantially the same plane as the circuit board surface. Since the connecting conductor of the common electrode is arranged on the insulating substrate, it is possible to increase the drawing density of the common electrode, and it is possible to prevent the uneven voltage drop caused by the common electrode as in the conventional case. It is possible to eliminate variations in the heat generation temperature of each heat generating object, and to perform high quality printing without uneven density, and furthermore, the connection between the common electrode and its connecting conductor is facilitated. In particular, it is no longer necessary to accurately align the common electrode and the connecting conductor, resulting in improved production efficiency.

Further, since it is not necessary to provide a common electrode pattern together with individual electrode patterns in the drive circuit board, the configuration of one drive circuit board becomes easy.

[Brief explanation of drawings]

FIG. 1 is a side sectional view showing a conventional thermal head.
FIG. 2 is a plan view showing this thermal head developed, FIG. 3 is a side sectional view showing the thermal head according to the present invention, and FIG. 4 is a plan view showing this thermal head developed. be. 11...0 Heating resistor 12...Insulating substrate 13...Radiation plate 14...Individual electrode 15-...Common electrode 1B-...Circuit board 21...Flame portion that becomes a single connection Patent applicant Sony Corporation Representative Patent Attorney Mi Koike

Claims (1)

[Claims] The individual electrodes of each heating resistor are taken out alternately on both sides of a plurality of heating resistors formed on an insulating substrate, and the heating resistor is heated by a common electrode facing the individual electrodes by sandwiching the heating resistor. In the thermal head, the thermal head is separate from the circuit board that supplies drive current to the individual electrodes, and the connecting conductor of the common electrode is disposed on substantially the same plane as the circuit board surface. head.