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US 4,481,452 AGranted
Control circuit for electromagnetic devices
AssigneeDiesel Kiki Co., Ltd.
InventorsYuichi Kitano, Yoshiharu Tada
Life of this patent
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Abstract
In a control circuit, which has a current switching-over circuit including at least four switching transistors for controlling a current flowing through an electromagnetic device, the control circuit has driving circuits each of which drives the switching transistors in such a way that a short circuit does not occur during the switching-over operation thereof.
Claims5
A control circuit for an electromagnetic device, which controls the current supplied from a d.c. power source to the electromagnetic device in response to an input signal, comprising:
- a first switching transistor provided between one power input terminal of said electromagnetic device and the positive terminal of said d.c. power source;
- a second switching transistor provided between said one power input terminal and the negative terminal of said d.c. power source;
- a third switching transistor provided between the other power input terminal of said electromagnetic device and said positive terminal;
- a fourth switching transistor provide between said other power input terminal and said negative terminal;
- means responsive to said input signal for generating a first and second control signals;
- means including a first driving circuit responsive to said first control signal for controlling the conducting states of said first and said second switching transistors so as to cause said conducting states to be opposite to one another in such a way that one of said first and said second switching transistors is turned ON after the other is substantially turned OFF;
- wherein said first driving circuit has means including a first circuit substantially turning OFF said first switching transistor within the region where the level of said first control signal is less than a predetermined first level and a means including a second circuit for substantially turning OFF said second switching transistor within the region where the level of said first control signal is more than a predetermined second level which is less than said first level;
- and
- means including a second driving circuit responsive to said second control signal for controlling the conducting states of said third and said fourth switching transistors so as to cause said conducting states to be opposite to one another in such a way that one of said third and said fourth switching transistors is turned ON after the other is substantially turned OFF;
- wherein said second driving circuit has means including a third circuit for substantially turning OFF said third switching transistor within the region where the level of said second control signal is less than a predetermined third level and means including a fourth circuit for substantially turning OFF said forth switching transistor within the region where the level of said second control signal is more than a predetermined fourth level which is less than said third level.
7 more elements
A control circuit for an electromagnetic device, which controls the current supplied from a d.c. power source to an electric motor for driving a door of a vehicle air-conditioner in response to an input signal indicative of the position of said door, comprising:
- a first switching transistor provided between one power input terminal of said motor and the positive terminal of said d.c. power source;
- a second switching transistor provided between said one power input terminal and the negative terminal of said d.c. power source;
- a third switching transistor provided between the other power input terminal of said motor and said positive terminal;
- a fourth switching transistor provided between said other power input terminal and said negative terminal;
- a first voltage comparator for comparing the level of said input signal with a first reference level;
- a second voltage comparator for comparing the level of said input signal with a second reference level which is less than said first reference level;
- means including a first driving circuit responsive to a first control signal for controlling the conducting states of said first and said second switching transistors so as to cause said conducting states to be opposite to one another in such a way that one of said first and said second switching transistors is turned ON after the other is substantially turned OFF, said first control signal being indicative of the result of comparison in said first voltage comparator;
- and
- means including a second driving circuit responsive to a second control signal for controlling the conducting states of said third and said fourth switching transistors so as to cause said conducting states to be opposite to one another in such a way that one of said third and said fourth switching transistors is turned ON after the other is substantially turned OFF, said second control signal being indicative of the result of comparison in said second voltage comparator.
6 more elements
Dependencies are inferred from the claim text.