JPH06415B2 - Method of equalizing resistance of thermal head - Google Patents

Description

The present invention relates to a method for equalizing the resistance value of a thermal head, which adjusts the resistance value of a heating resistor by applying a voltage pulse.

[Prior Art] FIG. 3 is a circuit diagram showing an apparatus for carrying out a method of equalizing the resistance value of a thermal head disclosed in, for example, Japanese Patent Laid-Open No. 61-83053, in which 1 is a common thermal head. Electrodes 2, 2 are electrodes, 3 is a heating resistor formed between the common electrode 1 and the lead electrode 2, 4 is a pulse power source, 5 is a contact with the common electrode 1, which is connected to the pulse power source 4. A common probe connected to the negative output terminal, 6 is an individual probe individually contacting each of the lead electrodes 2, and 7 is arranged between the individual probe 6 and the pulse power source 4, and the individual probe is provided. It is a switching circuit that selects one of the needles 6 and connects the lead electrode 2 with which it is in contact to the positive output terminal of the pulse power supply 4.

Next, the operation will be described. First, the switching circuit 7
Therefore, one of the individual probes 6 is selected, and the individual probe 6 is selected.
The lead electrode 2 in contact with is connected to the pulse power source 4. Here, when the pulse power supply 4 generates a voltage pulse between its first output terminal and its second output terminal, this voltage pulse is applied to the heating resistor 3 between the lead electrode 2 and the common electrode 1, The resistance value of the heating resistor 3 decreases. Hereinafter, the application of the voltage pulse is repeated while sequentially increasing the voltage value until the resistance value of the heating resistor 3 decreases to a predetermined value. In addition, the voltage pulse is applied based on the initial resistance value of the heating resistor 3 to obtain an applied voltage of the voltage pulse required to reduce it to a predetermined resistance value, and the voltage pulse of the voltage is applied once. You may make it apply only.

In this way, when the resistance value of the heating resistor 3 corresponding to one lead electrode 2 is adjusted, the adjacent individual probe 6 is selected by the switching circuit 7, and the corresponding heating resistor is selected in the same manner as described above. After adjusting the resistance value of 3,
This is sequentially repeated to make the resistance value of the thermal head uniform.

[Problems to be solved by the invention]

Since the conventional method of equalizing the resistance value of the thermal head is performed as described above, the lead electrode adjacent to the lead electrode to which the voltage pulse is applied is in an electrically floating state, while the lead electrode is The gap l between them is extremely narrow due to demands for high-density mounting, high resolution, etc. Therefore, when a voltage pulse is applied to one lead electrode, if the voltage becomes high, electrostatic induction or Voltage is generated due to discharge, etc. and disturbs the resistance value of the resistance heating element that has already been adjusted, or even if it is not adjusted the high voltage is applied and the resistance value drops more than necessary However, there is a problem that it is difficult to make the resistance values uniform with high accuracy.

The present invention has been made in order to solve the above problems, and prevents a voltage from being applied to the force of an adjacent lead electrode due to electrostatic induction, discharge, or the like, so that the resistance value can be made uniform with high accuracy. It is an object of the present invention to obtain a method for equalizing the resistance value of a thermal head that can be performed.

[Means for solving problems]

The method of equalizing the resistance value of the thermal head according to the present invention is
The switching electrodes of the switching switch elements of the switching circuit are respectively connected to the individual probes, and the normally closed electrodes of the switching switches have the same pole (positive, positive,
Negative side), the normally open side electrode is connected to a pole (positive or negative) different from the common probe, and is connected to the first output terminal of the pulse power source by the individual probe selected by the switching circuit. The lead electrode adjacent to the lead electrode is connected to the second output terminal of the pulse power source together with the common probe by an unselected individual probe.

[Action]

In the method of equalizing the resistance value of the thermal head according to the present invention, the lead electrode in contact with the selected individual probe is connected to the first output terminal of the pulse power source, and the second output terminal of the pulse power source is connected. A predetermined voltage pulse is applied to the heating resistor between the common electrode and the common electrode connected thereto, and the lead electrode adjacent to the lead electrode is connected to the common probe by the unselected individual probe and the pulse power source By connecting to the second output terminal and holding the same potential as the common electrode, application of voltage to the lead electrode due to electrostatic induction, discharge, etc. is prevented and the resistance value of the heating resistor is made uniform. It can be done accurately.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. First
In the figure, 1 is a common electrode, 2 is a lead electrode, 3 is a heating resistor, 4 is a pulse power source, 5 is a common probe, and 6 is an individual probe, which are equivalent to those shown in FIG. Therefore, detailed description thereof will be omitted.

Next, 7 is a switching circuit corresponding to the switching circuit 7 in FIG. 3, the switching elements are arranged in a hierarchical structure, and the switching type switching elements 8 are provided corresponding to the individual probes 6 in the lowermost layer. There is. Each switching type switch element 8 is
The switching electrode 8a is connected to the associated individual probe 6. The normally closed electrode 8c is connected to the same pole (positive, negative) as the common probe 5, and the normally open contact 8b is connected to a different pole (positive, negative) from the common probe 5.

As a result, the individual probe 6 adjacent to the individual probe 6 connected to the first output terminal of the pulse power source 4 by the selection of the switching circuit 7 is always connected to the second electrode of the pulse power source 4 together with the common probe 5. Will be connected.

Next, the operation will be described. First, the switching circuit 7
Then, the switch element control for each layer is performed, and one of the individual probes 6 is selected and connected to the first output terminal of the pulse power supply 4. At this time, the two individual probes 6 adjacent to the individual probe 6 are connected to the second output terminal of the pulse power supply 4. Here, when a voltage pulse is generated from the pulse power source 4, this voltage pulse is applied to the heating resistor 3 between the lead electrode 2 and the common terminal 1 with which the selected individual probe 6 is in contact, and the heating resistance is generated. The resistance value of the body 3 decreases. At this time, the lead electrode 2 adjacent to the lead electrode 2
Are both connected to the second output terminal of the pulse power source 4 by the individual probe 6 in contact therewith, and are fixed at the same potential as the common electrode 1. Therefore, no voltage is applied to these lead electrodes 2 due to electrostatic induction, discharge, etc., and the distance between lead electrodes 2 farther from the lead electrode 2 becomes longer and the shield action of both lead electrodes 2 causes electrostatic induction and discharge. There is no concern that voltage will be applied due to the above.

Here, in the pulse power supply 4, the second output terminal, that is, the negative output terminal side is grounded, the common electrode 1 having a large area is connected to the second output terminal on the ground side, and the first terminal not on the ground side. The output electrode has a lead electrode 1 with an extremely small area.
Since they are connected one by one, even when the thermal head was placed on the grounded work stage and the resistance value was made uniform, the voltage was applied by the capacitance between the work stage and the electrodes. The waveform of the voltage pulse does not become large, and the resistance value can be adjusted with high accuracy.

While individually selecting the individual probe 6 by the switching circuit 7, the resistance value of the heating resistor 3 corresponding to the lead electrode 2 in contact with the individual probe 6 is adjusted to make the resistance value of the thermal head uniform. .

FIG. 2 is a circuit diagram showing an apparatus for carrying out the method of equalizing the resistance value of the thermal head according to the present invention. The switching circuit 7 is composed of only the switching type switch element 8 provided corresponding to the individual probe 6. This is different from the embodiment shown in FIG. That is, the switching electrode 8a of each switching type switch element 8 is connected to the associated individual probe 6, the normally closed side electrode 8c is connected to the same pole (positive, negative) as the common probe 5, and the normally open side. The electrode 8b is a pole different from the common probe 5 (positive,
Negative).

In this embodiment, the switching type switch elements 8 of the switching circuit 7 are driven one by one, and the corresponding individual probe 6
Only the first output terminal of the pulse power source 4 is connected, and the other individual probe 6 is connected to the second output terminal of the pulse power source 4 together with the common probe 5. As a result, the resistance value of the heating resistor 3 is adjusted as in the embodiment shown in FIG. 1, and the influence of the voltage pulse applied for adjusting the resistance value affects the adjacent heating resistor 3. Nor.

In addition, although the mechanical switch element such as a relay contact is shown as the switch element of the switching circuit 3 in the above-described embodiment, a static switch element such as a semiconductor switch may be used.

〔The invention's effect〕

As described above, according to the present invention, the switching electrode of the switching-type switching element is connected to the individual probe, and the normally closed side electrode is connected to the same pole (positive or negative) as the common probe so that it is normally opened. The side electrode is connected to a pole (positive or negative) different from the common probe, and the lead electrode adjacent to the lead electrode connected to the first output terminal of the pulse power supply by the selected individual probe is not selected. Since the individual probe is connected to the common probe together with the second output terminal of the pulse power supply, the lead electrode of the heating resistor adjacent to the heating resistor for adjusting the resistance value has the same potential as the common electrode. The lead electrodes other than the lead electrode of the heating resistor that is fixed to the electric potential and whose resistance value is adjusted can completely eliminate the influence of the voltage pulse for resistance adjustment due to electrostatic induction, discharge, etc. Accurately equalizes the resistance value of The effect of the resistance value uniform method for the thermal head is obtained which can be carried out.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an apparatus for carrying out a thermal head resistance equalizing method according to an embodiment of the present invention, and FIG. 2 is a thermal head resistance equalizing method according to another embodiment of the present invention. FIG. 3 is a circuit diagram showing an apparatus for carrying out the method for equalizing the resistance value of a conventional thermal head. 1 is a common electrode, 2 is a lead electrode, 3 is a heating resistor, 4 is a pulse power source, 5 is a common probe, 6 is an individual probe, 7 is a switching circuit, 8 is a switching type switch element, 8a is a switching electrode, 8b is a normally open side electrode, and 8c is a normally closed side electrode. In the drawings, the same reference numerals indicate the same or corresponding parts.

Continued Front Page (72) Inventor Hirozo Yamashita 8-1-1 Tsukaguchi Honcho, Amagasaki City, Hyogo Sanbishi Electric Co., Ltd. Communication Equipment Factory (72) Yahei Takase 8-1-1 Tsukaguchi Honcho, Amagasaki City, Hyogo Prefecture No. 1 Sanryo Electric Co., Ltd. Communication Equipment Factory

Claims (2)

[Claims] 1. A plurality of individual probes individually contacting the lead electrodes of a thermal head are selectively connected to a first output terminal of a pulse power source through a switching circuit and are in contact with a common electrode of the thermal head. The common probe is connected to the second output terminal of the pulse power supply, and the heating resistor between the common electrode and the lead electrode in contact with the individual probe selected by the switching circuit is connected to the heating source from the pulse power supply. In the method of equalizing the resistance value of the thermal head by adjusting the resistance value of the heating resistor by applying the voltage pulse of, the switching circuit has a switching type switch element corresponding to the individual probe, The switching element has its switching electrode connected to each of the individual probes, its normally closed side electrode is connected to the same pole (positive, negative) as the common probe, and the normally open side electrode is A lead electrode adjacent to the lead electrode connected to a pole (positive or negative) different from the common probe and connected to the first output terminal of the pulse power source by the individual probe selected by the switching circuit, A method for equalizing the resistance value of a thermal head, characterized in that the individual probes that are not selected are connected to a second output terminal of the pulse power source together with a common probe. 2. The method of equalizing the resistance value of a thermal head according to claim 1, wherein the second output terminal of the pulse power supply is an output terminal on the ground side.