Capacitive load driving circuit and liquid crystal display

Abstract

An overcurrent is prevented from flowing in an output circuit when a short circuit occurs between an output terminal and a power supply terminal or a ground terminal. For this purpose, provided is an output circuit comprising a power supply terminal, a ground terminal, and an output terminal connected to a capacitive load. Depending on the state of a load control input signal, the output circuit performs selectively a charging-current supplying operation of supplying a charging-current from the power supply terminal to the capacitive load and a discharging-current withdrawing operation of withdrawing a discharging-current from the capacitive load to the ground terminal. Further, an overcharging-current prevention switch is provided for detecting a short circuit between the output terminal and the ground terminal so as to stop or suppress the charging-current supplying operation. Furthermore, an overdischarging-current prevention switch is provided for detecting a short circuit between the output terminal and the power supply terminal so as to stop or suppress the discharging-current withdrawing operation.

Description

technical field [0001] The present invention relates to a capacitive load driving circuit for driving a capacitive load by charging and discharging current, such as a capacitive load driving circuit for driving a common electrode of a liquid crystal panel. In addition, the present invention also relates to a liquid crystal display device using a capacitive load drive circuit. Background technique [0002] Japanese Patent Application Laid-Open No. 2000-174601 and the like describe a capacitive load drive circuit for driving a capacitive load including, for example, a common electrode of a liquid crystal panel. [0003] image 3 is a schematic circuit diagram showing a capacitive load drive circuit proposed by the present inventors previously. like image 3 As shown, in this capacitive load driving circuit, the output circuit 21 has a power supply terminal 17 connected to a power supply line (Vcc line), a ground terminal 18 connected to a ground line, and a capacitor composed...

AI Technical Summary

Problems solved by technology

As a result, there is a problem that the output transistors Q1, Q2 constituting the output circuit 21 are overheated, and an integrated circuit, etc. integrating, for example, a capacitive load driving circuit including the output transistors Q1, Q2 is also overheated.

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