Driving circuit for controlling output voltage to be applied to a load in accordance with load resistance
First Claim
1. A driving circuit for driving a load having either of large and small resistance, comprising:
- driving means connectable to a load for driving the same, said driving means including a driving transistor, a switch controlled by an input signal and a transformer having a primary winding connected to said driving transistor through said switch and a secondary winding connected to said load;
first control means being operative in case of said load having a relatively large resistance for producing a first control signal effective to control said driving means to drive said load by a constant voltage;
second control means being operative in case of said load having a relatively small resistance for producing a second control signal effective to control said driving means to drive said load by a constant current; and
selecting means for selectively applying either of said first and second control signals to said driving means according to the value of load resistance connected to said driving circuit.
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Accused Products
Abstract
The disclosed driving circuit is composed of a driving transistor connectable to a load in accordance with an input signal, a first control device operating in case of driving the load having a relatively large resistance for producing a first control signal effective to control the driving transistor to drive the load by a constant-voltage type operation, a second control device operating in case of driving the load having a relatively small resistance for producing a second control signal effective to control the driving transistor to drive the load by a constant-current type operation, and a selecting device selectively applying either of the first and second control signals to the driving transistor according to the value of the load resistance connected to the driving transistor.
14 Citations
11 Claims
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1. A driving circuit for driving a load having either of large and small resistance, comprising:
- driving means connectable to a load for driving the same, said driving means including a driving transistor, a switch controlled by an input signal and a transformer having a primary winding connected to said driving transistor through said switch and a secondary winding connected to said load;
first control means being operative in case of said load having a relatively large resistance for producing a first control signal effective to control said driving means to drive said load by a constant voltage;
second control means being operative in case of said load having a relatively small resistance for producing a second control signal effective to control said driving means to drive said load by a constant current; and
selecting means for selectively applying either of said first and second control signals to said driving means according to the value of load resistance connected to said driving circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7)
- driving means connectable to a load for driving the same, said driving means including a driving transistor, a switch controlled by an input signal and a transformer having a primary winding connected to said driving transistor through said switch and a secondary winding connected to said load;
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8. A driving circuit comprising:
- a driving transistor for driving a load in response to an input signal, said load being connected in series to a first side of said driving transistor;
first means for producing a first reference voltage;
a first differential amplifier having a non-inverting input terminal receptive of said first reference voltage produced by said first means and an inverting input terminal receptive of an output voltage obtained from said driving transistor to be applied to said load;
current detecting means connected in series to a second side of said driving transistor opposite to said first side thereof, said current detecting means detecting a current flowing through said driving transistor;
second means for producing a second reference voltage;
a second differential amplifier having an inverting input terminal receptive to said second reference voltage produced by said second means and a non-inverting input terminal receptive of a detected voltage produced by said current detecting means; and
an adder for adding outputs from said first and second differential amplifiers to each other to output the added voltages as a control signal effective to control said driving transistor. - View Dependent Claims (9, 10, 11)
- a driving transistor for driving a load in response to an input signal, said load being connected in series to a first side of said driving transistor;
Specification