JPH0441258A - thermal printer head - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a thermal printer head for facsimiles, word processors, etc.

[Prior art]

The thermal printer head consists of a heat-generating section that performs printing and a driver IC that drives it, and generates heat and prints by passing an electric current through it.

The driver IC is CMO5 or Bi-CMO.
5 chips, which are connected by wire bonding.

The thermal printer head described above is subject to mounting restrictions such as wire bonding as the resolution increases and the number of dots increases.
This makes it difficult to lower prices.

Therefore, the substrate is made of quartz, and the drive circuit is composed of polysilicon thin film transistors.

Many proposals have been made to integrate a driving circuit and a heating element on the same substrate without using an IC chip by forming polysilicon as a heating element in the manufacturing process.

For example, in JP-A No. 62-204964, a heating resistor is selectively energized to generate heat by driving a driver element, and this driver element is a MOSFET and other circuits are CMO5, and these sources - It is disclosed that the thickness of the polycrystalline silicon of the drain active layer is 800 Å or less.

However, the conventional example described above was still insufficient in the following points6: The current value when turning on one bit of the heating element ranges from several mA to several +
mA is required, and the driver transistor is required to have the current driving capability.

If a driver transistor is made from a MOS transistor, even one made from a wafer will require tens to hundreds of W/L, and polysilicon thin film transistors will certainly require hundreds or more, occupying a considerable area. Furthermore, if W increases to that extent, the leakage current during off-time also increases, causing a problem.

〔the purpose〕

The object of the present invention is to convert the driver thin film transistor into a MOS
To provide a thermal printer head which uses not a transistor but a bipolar transistor having a large current drive capability to reduce the area and suppress leakage current.

〔composition〕

One of the present inventions is to provide a heat generating resistor, a bipolar thin film transistor for driving the heat generating resistor, and an M
The present invention relates to a thermal printer head characterized in that it is constituted by a drive circuit made of OS type thin film transistors.

Another aspect of the present invention relates to a thermal printer head according to claim 1, wherein the semiconductor substrate of the bipolar thin film transistor is made of a single crystal.

As the insulating substrate in the present invention, quartz glass, Pyrex glass, glazed ceramic, etc. can be used.

The bipolar thin film transistor formed on the insulating substrate to drive the heating resistor and the 0MO5 thin film transistor of other circuits can be formed by known means.

Preferably, the semiconductor substrate (active layer) of the emitter, collector, and base portions of the bipolar thin film transistor is made of single crystal.

For the single crystallization, for example, when amorphous silicon or polysilicon is used as the semiconductor substrate, a well-known laser annealing process may be used after depositing the amorphous silicon or polysilicon.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an example of a circuit configuration of a thermal printer head of the present invention.

In this circuit configuration example, a one-picture signal is input as a data signal to a shift register circuit 2 from a signal terminal 1. When one line of data is input to the shift register circuit 2 according to the clock signal input from the signal terminal 3, all the data is transferred in parallel to the latch circuit 5 by the strobe signal input as a latch pulse from the signal terminal 4. Retained. The data held in the latch circuit 5 is inputted from the signal terminal 6 and drives the driver element 8 via the gate circuit 7 in accordance with the instruction of the enable signal that determines printing timing, etc., and selectively energizes the heating resistor 9. cause fever.

1 as the driver element that causes the heating resistor to generate heat;
In the present invention, a bipolar thin film transistor is used, and a CMO5MOS transistor is used as another circuit.

FIG. 2 is a sectional view of an example of the thermal printer head of the present invention. #! As the edge substrate 21, quartz glass, Pyrex glass, glazed ceramic, etc. can be used.

When the resistance of the heating resistor 22 is set to 3Ω, the same polycrystalline silicon as the active layer 24 of the MOS thin film transistor 23 constituting the drive circuit may be used for the heating resistor 22. Furthermore, when the heating resistor 22 is set to a lower resistance, for example, 1.3 Ω, the gate electrode 25 of the MO5 type thin film transistor 23 may be used. Further, polysilicon may be used for the gate electrode 25 as well as the active layer 24.

Next, when polysilicon is used as the semiconductor substrate 27 in the bipolar thin film transistor 26, MO3
Polysilicon may be deposited in a separate process from the polysilicon of the type transistor 23, and it is also possible to use the polysilicon of the gate electrode 25 depending on the selection of process and film thickness.

As the semiconductor substrate 27, amorphous silicon can be used in addition to the polysilicon.

The polysilicon or amorphous silicon deposited as the semiconductor substrate 27 is preferably recrystallized by laser annealing using an argon laser or the like.

The laser annealing process can be performed by a known method, and may be performed selectively on the semiconductor substrate 27.

The semiconductor substrate 27, which has been made into a single crystal by the above-mentioned treatment, undergoes an impurity implantation process to form an emitter 28, a collector 29, and a base 30.
is formed. Bipolar transistor 26 in FIG. 2 is of lateral structure.

Although FIG. 2 shows only one transistor for switching the driver transistor 26 as the M○S type transistor 23 constituting the drive circuit, in reality, a circuit such as a shift register is constituted by a CMOS transistor.

Further, in a CMOS transistor, a thermally oxidized polysilicon film of the active layer 24 is used as a gate insulating film 31, and polysilicon of the gate electrode 25 is formed thereon. pch
, nch can be created by boron and phosphorus ion implantation, respectively.

The electrode 32 is connected from the heating resistor 22 to the MOS transistor 2.
For example, A Q-5i may be used. 33 is an insulating film between the eyebrows, and 34 is a passivation film.

〔effect〕

In the thermal printer head of the present invention, the heating element, driver transistor, and drive circuit are formed on the same substrate, and the driver transistor is composed of a bipolar thin film transistor, so that sufficient driver characteristics can be exhibited in a small area. Further, in bipolar thin film transistors for drivers, those using a semiconductor substrate subjected to laser annealing recrystallization can exhibit good driver characteristics.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an example of the circuit configuration of a thermal printer head of the present invention, and FIG. 2 is a sectional view of an example of the thermal printer head of the present invention. 8...Driver element 9,22...Heating resistor 21...
... Insulating substrate 23 ... MO5 type thin film transistor 24 • Active layer 25 ... Gate electrode 26 ...
Bipolar thin film transistor 27...Semiconductor substrate
28... Emitter 29... Collector 30.
...Base 31...Gate insulating film 32...Electrode 33...Interlayer insulating film 34...Passivation film Fig. 1 Fig. 2

Claims (1)

[Scope of Claims] 1. A thermal printer head comprising a heating resistor, a bipolar thin film transistor for driving the heating resistor, and a drive circuit including a MOS thin film transistor on an insulating substrate. 2. The thermal printer head according to claim 1, wherein the semiconductor substrate of the bipolar thin film transistor is made of a single crystal.