JPS60172556A - Thermal recording apparatus - Google Patents

Abstract

PURPOSE:To obtain a thermal recording appratus having a low cost head requiring no multi-layered wiring, easy to prepare and having high reliability, by providing one common electrode and using an electrode driver, which supplies positive voltage, negative voltage or high impedance corresponding to a recording signal, in place of a switch element. CONSTITUTION:A driver circuit P1 issues an output signal (e) according to signals g1, g2 inputted from a control part corresponding to a signal to be recorded and selectively generates either one of positive voltage, negative voltage and a high impedance state belonging to neither one of said voltages to supply the same to an electrode E31. For example, if negative voltage is applied to the electrode E31, a current flows through a route of common electrode E21 diode D1 electrode E11 dot region R1 electrode E31 and the dot region R1 of a heat generating resistor I generates heat and, if positive voltage is applied to the electrode E31, a dot region R2 generates heat. If the output of the driver circuit P1 is brought to the high impedance state, only a slight current flows to the dot regions R1, R2 and said regions generate no heat together.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a thermal recording device used in facsimiles and the like, and particularly to a thermal recording device whose thermal recording head has a simplified configuration.

[Background of the invention]

Thermal recording devices used in facsimiles, printers, etc. usually have a heating resistor arranged linearly on an insulating substrate, and the pixels (dots) of the heating resistor are arranged in a straight line on an insulating substrate.
Thermal recording is performed on the recording medium that is in contact with the resistor by selecting an area corresponding to the resistor and generating heat. The figure is a sectional view taken along line xx' in FIG. 1. In these figures, E21. ' J22 is a common electrode, DI-D6 is a backflow prevention diode, ■ is a heating resistor, Elly b12
~Ex6 are electrodes, E31, E32~E35, respectively
are electrodes, 81 to S5 are switching elements, and R1=R10 are resistance regions corresponding to pixels (dots).

Explain circuit operation. Now, it is assumed that thermal recording is to be carried out in the dot region R (the region in the heat generating resistor 1 from the center of the electrode Elf to the center of the electrode E31 as shown in FIG. 1A). At this time, after the switching element S1 is closed by a drive circuit (not shown), a positive power source is connected to the common electrode E21.

Then, E21→D1→E 11→1(1→E3t→S
1 → Current flows through the earth circuit and the dot area R1
generates heat, and thermal recording is performed on a recording medium (not shown).

Also, consider the case where thermal recording is performed in the dot area R2. At this time, after closing the switching element S1, a positive power source is connected to the common electrode E22.

Then, E22 → D2 → E12 → R2 → E31 → S1 →
A current flows through the grounded circuit, heat is generated in the dot region R2, and thermal recording is performed on a recording medium (not shown).

As described above, in the conventional thermal recording apparatus, thermal recording is performed in a desired dot area by selecting one of a plurality of common electrodes in addition to selecting a switching element.

Although two common electrodes E21 and E22 are shown here, in reality, a large number (for example, four) are used.

This is because if there is only one common electrode, all dot areas will be connected to the same common electrode, and if all dot areas are to be thermally recorded at the same time, the required large current must be supplied from that common electrode. However, the entire dot area is divided into four groups, a separate common electrode is assigned to each group, and thermal recording is performed four times for each group. This is because the required power supply capacity is - compared to the case where there is only one common electrode.

Due to these circumstances, a plurality of common electrodes are used in conventional thermal recording devices, but in this case, as is clear from FIG. 1, for convenience of connection with other electrodes, the common electrode E2
1 and E22 must be placed one on top of the other with an insulating layer in between. If the number of common electrodes increases, an insulating layer must be interposed between each common electrode, which forces the overall wiring structure to be multilayered.

In conventional thermal recording devices, the head part has a multilayer wiring structure, which increases the number of manufacturing steps, the amount of materials required, and the cost.
Furthermore, due to the complex structure of multilayer wiring, product defects are likely to occur.

[Purpose of the invention]

The present invention is first in its longevity to eliminate the drawbacks of the prior art as described above, and therefore, an object of the present invention is to eliminate the need for a multilayer wiring structure in the head portion, thereby reducing manufacturing costs. It is an object of the present invention to provide a thermal recording device K that is easy, inexpensive, and highly reliable.

[Summary of the invention]

In order to achieve the above object, in the present invention, the number of common electrodes is one, and as an electrode driver used instead of a switch element, positive and negative voltages and high impedance of neither are selectively applied according to the signal to be recorded. By using a logic circuit that can be generated, it is possible to select and group dot regions.

[Embodiments of the invention]

Next, one embodiment of the present invention will be described with reference to the drawings.

FIG. 2 is an explanatory diagram showing one embodiment of the present invention.

In this figure, the same reference numerals as in FIG. 1 indicate the same things. In addition, P1 to P5 are driver circuits having the same circuit configuration.

In the non-embodiments, the driver circuit has the most important meaning. The explanation will be given by taking the driver circuit P1 as an example.

The driver circuit P1 outputs either a positive voltage, a negative voltage, or a high impedance state that is neither of the above, as the output voltage e, according to a signal g1yg2 input from a control unit (not shown) in response to a signal to be recorded. One of them is selectively generated and supplied to the electrode E31.

Next, recording Wb production will be explained. In FIG. 2, common electrode E21 is connected to the ground side, and positive or negative voltage is applied to electrodes E31-E35 via driver circuits P1-P5. For example, when a negative voltage is applied to the electrode E31 from the driver circuit P1, the current flows from the common electrode R21 to the diode D1.
It flows through the path of → electrode Eo → dot region tti → electrode E31, and dot region R1 generates heat. If a positive voltage is applied to the electrode E31 from the driver circuit P1, then the electrode E31→dot region R2→electrode E12→diode D2
→ Common electrode E21 → Current flows through the path of ground,
Dot region R2 is selected and generates heat. Other dot areas can be selected in a similar manner.

That is, by applying a positive voltage to each of the electrodes E31 to E35, the dot regions tt2. n3. n6゜R7
, Rlo respectively and apply a negative voltage, the dot region R1s IL4 y 1L5 y
I'S yR9 can each be exothermic.

The operation mode for selecting the dot areas R1 to R1 and generating heat has been described above, but if there is a dot area that is not recorded, it is sufficient to apply neither positive voltage nor negative voltage to the corresponding electrode. In order to achieve this, the output of the driver circuit may be brought into an impedance state. A tri-state output type driver circuit that can output any one of a positive voltage, a negative voltage, and a high impedance state will be described below.

FIG. 2A is a circuit diagram showing a specific example of such a tri-state output type driver circuit P1 in FIG. 2.

In the same figure, ■ is a positive power supply, e is a negative power supply, Ql and G2 are transistors, r1yr2 are resistors, and G
1 is N0Ft gate, G2 is inverter, G3 is NAN
In the D gate, g12g2 is an input signal, and e is an output signal.

The relationship between input and output signals for driver circuit P1 is shown in the following truth table.

Truth Table In the truth table, X indicates that it can be positive or negative, and Z indicates an impedance state.

As can be seen from this truth value, in order to generate heat in the dot regions R1 and R2 in FIG. 2, it is sufficient to make the human power signal g2 negative and to make the input signal g4 negative and positive. In addition, if you do not want to generate heat, make the input (i) and g2 positive.Then, transistors Q i and Q 2 (1': t, both turn off and exhibit a high impedance state, and the dot region [
t], rtz, only a small current that is negligible compared to the current required to generate heat flows, and no heat is generated.

In the head of this device, due to the circuit configuration shown in FIG. 2, care must be taken not to apply voltages of different polarities to the electrodes E31 to E35 at the same time.

For example, if positive and negative voltages are simultaneously applied to the electrodes E31 and E32, the dot area will be 11.2. This is because in addition to R and 4, R3, which is not desired, is also selected.

However, in spite of such a problem to be noted, in the present invention, only one common electrode E21 is required, and in particular, there is no need for wiring for blocking a large number of dot regions, and the blocking is done by the driver. Since it can be controlled from the side, the configuration of the head is extremely simple.

[Effect of J emitted]

As described above, according to the present invention, it is possible to provide a thermal recording device that does not require multilayer wiring, is easy to manufacture, and has a highly reliable, low-cost head.

[Brief explanation of drawings]

Figure 1 is a plan view showing the main parts of a conventional thermal recording device.
Figure A is a sectional view taken along the line xx' in Figure 1, Figure 2 is a diagram showing an embodiment of the present invention;
The figure is a circuit diagram showing a specific example of the driver circuit in FIG. 2. Code explanation R21, J22...Common electrode, Ell t
E12-E16... Electrode, l bow 31 p b
32-E35...electrode, D1-D6...
...Diode, ■...Heating resistor, 81-8
5... Switching elements, P1 to P5...
...Driver circuit, g□-R2...Input signal,
e-・・・Output signal Figure 1 Figure 1A

Claims (1)

[Claims] 1) a common electrode, a heating resistor, and a plurality of electrodes sequentially arranged in 5 patterns to divide the resistor along the resistor;
a plurality of unidirectional elements connecting each of the first group of electrodes consisting of every other electrode among the plurality of electrodes and the common electrode with changing polarity for each adjacent electrode; , and a plurality of driver circuits connected to each of the second group of electrodes consisting of every other remaining electrode among the plurality of electrodes, and each of the driver circuits has a positive or negative polarity depending on the recording signal. 1. A thermal recording device, characterized in that the voltage or high impedance is supplied to the connected electrodes.