Drive circuit for inductive load

Abstract

An inductive load is disposed between a midpoint between a first and second transistors connected in series and a midpoint between a third and fourth transistors connected in series. A protective resistor is disposed between sources or emitters of the first and third transistors and a direct-current power supply, a sensing resistor is disposed between the low-potential sides of the second and fourth transistors and a ground, and the first and third transistors are driven by inputting drive signals each having a fixed potential to gates or bases thereof. When the voltage applied to the sensing resistor is continuously equal to or less than a threshold value for sensing a ground short circuit for a predetermined period of time or longer at the time of application of power to the inductive load, the drive signals from a drive means are turned off. The destruction of the first and third transistors caused by the ground short circuit is prevented by a simple circuit.

Description

technical field [0001] The present invention relates to a drive circuit for inductive loads such as solenoids, motors, and coils, and more particularly to detection of grounding around inductive loads. Background technique [0002] Patent Document 1: Japanese Patent Application Laid-Open No. 11-81105 discloses a pull-down device for knitted fabric on a knitting machine such as a flat knitting machine. On the flat knitting machine, the knitted fabric is pulled down to the lower side of the needle bed. In order to cope with the lateral movement of the needle bed, the movement of the knitted fabric on the needle bed, etc., Japanese Patent Application Laid-Open No. 11-81105 discloses a pull-down device capable of independently releasing the pull-down at each position in the knitted fabric. Using a solenoid for on / off of the pull-down, for example, several tens of solenoids are controlled in parallel, and the pull-down is performed or released corresponding to the position in th...

AI Technical Summary

Problems solved by technology

[0005] Figure 4 In the circuit, due to the deviation of the resistors R11~R14, the detection accuracy is reduced

Furthermore, a differential amplifier circuit composed of buffers 40, 41 and a differential amplifier 42 is required to drive dozens of coils 12 in parallel, thus generating a non-negligible cost.

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