JPS6181240U - - Google Patents

Description

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention, FIG. 2 is a circuit diagram for explaining only the direct current relationship in FIG. 1, and FIG. 3 is a circuit diagram of the circuit shown in FIG. 2. Graphs for explaining the operation, FIG. 4 is a circuit diagram showing a second embodiment of the present invention, FIG. 5 is a circuit diagram showing an example of a typical conventional light emitting element drive circuit, and FIG. 6 is a circuit diagram showing a second embodiment of the present invention. Figure 5 is a graph showing the current relationship during operation of the circuit, Figure 7 is a circuit diagram showing an example of a conventional DC passing type drive circuit, and Figure 8 explains only the DC current relationship in Figure 7. FIG. 9 is a graph for explaining the operation of the circuit shown in FIG. 8. In the figure, 1, 2, 7, and 14 are transistors, 3, 4, 6, 8, 9 to 12, and 15 to 18 are resistors, 5 is a light emitting element, and 19 is a coaxial cable.

Claims (1)

[Scope of utility model registration request] a light emitting element, an output side connected to the light emitting element,
a DC passing impedance circuit for driving the light emitting element with an electric signal; and a DC passing impedance circuit connected in series to a parallel connection point between the output side of the DC passing impedance circuit and the light emitting element, and connected through a transistor for controlling a current value. and a DC current supply circuit for supplying a DC bias current to the light emitting element, wherein a voltage drop is caused by a series current flowing to the DC current supply circuit via the current value control transistor. A bypass circuit including a second transistor is connected in parallel with the circuit including the current value control transistor to a connection point closer to the light emitting element than the connected resistor, and a bypass circuit including a second transistor is connected in parallel to the circuit including the current value control transistor. adjusting the control input of the value control transistor to make the current value flowing through the resistor equal to the DC bias value flowing through the light emitting element;
A light emitting element equipped with a bias current monitor circuit, characterized in that the DC value flowing through the bypass is made equal to the DC value flowing through the DC passing impedance circuit by adjusting the control input of the second transistor. drive circuit.