JPS63104853A - Thermal head drive - Google Patents

Abstract

PURPOSE:To reduce the size of a drive without increasing the wiring density of drive electrodes, by forming common ground electrodes immediately below for every other drive ICs arranged side by side and sharing the common ground electrodes with adjoining drive ICs. CONSTITUTION:Common ground electrodes 13a, 13b,... are formed immediately below a plurality of drive ICs 15a, 15b, 15c,... juxtaposed on a part mounting substrate for every other ICs. Ground terminals 16a, 16b, 16c, 16d of the drive IC 15a and ground terminals 17a, 17b of the drive IC 15b are connected through lead wires to the common ground electrode 13a, while ground terminals 18a, 18b, 18c, 18d of the drive IC 15c and ground terminals 17c, 17d of the drive IC 15b are connected through lead wires to the common ground electrode 13b. Consequently, the number of common ground electrodes is reduced to enable reduction of the size of part mounting substrate without increasing the drive electrode density, resulting in reduction of the size of a thermal head drive.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a thermal head driving device that drives a thermal head by energizing a heating resistor within the thermal head.

(Prior Art) FIG. 2 is a circuit diagram of a driving integrated circuit applied to a thermal head driving device. A driving integrated circuit (hereinafter referred to as "driving ICJ") 1 includes a shift register 4 that shifts print data input to a print data input terminal 2 at the timing of a clock pulse input to a clock input terminal 3; A latch circuit 6 that holds the output data of the shift register 4 at the timing of a latch signal input to a latch input terminal 5, and a logic between the output of this latch circuit 6 and an enable signal input via an enable input terminal 7. The device includes a plurality of AND circuits 8 that calculate the product ()q, and a plurality of driver circuits 9 that heat and drive a heating resistor (referred to as a heating element) using the output of the AND circuit 8.

Enable signal input terminal 7. Latch signal input terminal 5. Print data input terminal 2. Clock input terminal 3 is a driving I
This is a terminal for taking in various input signals such as an enable signal into C1, that is, into the logic circuit. In this sense, each of the above terminals is collectively referred to as a logic circuit input terminal 10. Further, 11 is a drive terminal to which a heating element is connected, and 12 is a logic circuit output terminal.

Due to manufacturing problems with drive IC1, the drive ICI
is configured as a 32-bit output, and a plurality of driving ICs 1 shown in FIG. 2 are arranged in the thermal head. The arrangement of the driving ICs 1 on the component mounting board is determined by taking into consideration the positional relationship of each terminal provided on the driving ICs 1.

FIGS. 3 and 4 are explanatory diagrams showing a conventional thermal head driving device. In addition, the driving I shown in FIGS. 3 and 4
C1 also displays the power input terminal, ground terminal, etc.
The number of terminals is greater than that in Figure 2.

Figure 3 shows a common grounding electrode 13 on the component mounting board.
and a drive electrode 14 are formed, and the drive IC 1 is mounted on the drive electrode 14. In the case shown in FIG. 4, the drive ICI is mounted on the common ground electrode 13. It is something.

(Problem to be solved by the invention) However, in order to miniaturize the device with this configuration, the drive electrode must be made thinner and the wiring density must be increased, which increases power loss in the drive electrode. However, this poses a problem in that it adversely affects the heating drive characteristics. For this reason, it has been extremely difficult to downsize the device.

The present invention has been made in view of the above circumstances, and its purpose is to reduce the size of a thermal head drive device without increasing the wiring density of drive electrodes.

[Structure of the Invention] (Means for Solving the Problems) The present invention includes a component mounting board on which a common grounding electrode is formed, and a number of drive ICs for heating and driving a heating element arranged in parallel. In a thermal head drive device in which a ground terminal of the driving IC is connected to the common grounding electrode, a common grounding electrode is formed at a position immediately below the driving IC for every other driving IC arranged in parallel, This common ground electrode is connected to the drive IC.
and a driving IC adjacent to the driving IC.

(Function) As described above, as a result of forming a common grounding electrode directly under every driving IC installed in parallel, the number of common grounding electrodes is increased compared to the conventional method. will be reduced by 1/2. Therefore, by effectively utilizing the space created by the reduction in common grounding electrodes to form drive electrodes, it is possible to reduce the size of the component mounting board without increasing the density of drive electrodes, resulting in miniaturization of the device. It becomes possible.

(Example) Hereinafter, the present invention will be specifically explained with reference to Examples.

FIG. 1 shows an embodiment of the present invention.

As shown in the figure, the device of this embodiment includes a plurality of driving ICs 15a and 15b arranged in parallel on a component mounting board.

15C1...A common grounding electrode 13a, 13b, .
It is shared by the adjacent driving IC. That is, in FIG. 1, the driving IC 15a.

Common ground electrodes 13a and 13b are formed directly below the drive IC 15G, but no common ground electrode is formed directly below the drive IC 15b, and a drive electrode 14 is formed instead. . And drive IC1
5a ground terminals 16a, 16b, 16c.

16d and the ground terminals 17a and 17b of the driving IC 15b.
are connected to the common grounding electrode 13a via a conductive wire, and similarly ground terminals 18a, 18b of the driving IC 15c.

18c, 18d and ground terminal 17 of driving IC 15b
c.

17d is connected to the common grounding electrode 13b via a conductive wire.

According to the above configuration, the number of common grounding electrodes is reduced to 172 compared to the conventional one (Figs. 3 and 4), and this reduction creates a space (in Fig. 1, the number of common grounding electrodes is 172). Since the drive electrodes 14 are formed by effectively utilizing the position directly below the drive electrodes, the component mounting board can be made smaller without increasing the density of the drive electrodes, and the device can be made smaller.

It goes without saying that the present invention is not limited to the above-mentioned embodiments, and that various modifications can be made.

[Effects of the Invention] As described in detail above, according to the present invention, it is possible to downsize a thermal head drive device without increasing the wiring density of drive electrodes.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention, FIG. 2 is a circuit diagram of a driving IC applied to a thermal head driving device,
FIGS. 3 and 4 are explanatory diagrams of conventional examples. 13a, 13b... common grounding electrode, 15a, 15b
, 15G...Drive IC. 16a to 16d, 17a to 117d, 18a to fi
18d...Grounding terminal, ゛R...Heating element. Figure 3

Claims (1)

[Claims] A thermal thermal device in which a plurality of driving ICs for heating and driving a heating element are arranged in parallel on a component mounting board on which a common grounding electrode is formed, and the grounding terminal of the driving IC is connected to the common grounding electrode. In the head drive device, drive ICs 1 arranged in parallel
A common grounding electrode is formed directly below the driving IC, and this common grounding electrode is shared by the driving IC and a driving IC adjacent to the driving IC. Thermal head drive device.