Driving apparatus for stabilizing burst light output

Claim 3

The apparatus according to claim 1, characterized in that said bias controller means comprises comparator means (28), connected to said photodetector means (24), for receiving a reference signal (30) and the detection signal (26) and for generating a first comparison signal when the detection signal (26) has a lower level than that of the reference signal (30) and a second comparison signal when the detection signal (26) has a higher level than and an equal level to that of the reference signal (30), power source means (42), connected to said light-emitting element (10), for generating a variable bias current, and logic circuit means (40, 34), connected to said comparator means (28) and said power source means (42), for receiving a light emission instruction signal (16) for specifying a light emission timing of said light-emitting element (10) and selectively receiving the first and second comparison signals (32), so as to cause said power source means (42) to increase an output bias current in response to the first comparison signal and to inhibit an increase in the output bias current and hold a last bias current level in response to the second comparison signal.

Claim 4

The apparatus according to claim 2, characterized in that said power source means includes capacitor means (42) for receiving a constant current, storing the constant current, and increasing the bias current to be supplied to said light-emitting element (10).

Claim 5

The apparatus according to claim 3, characterized in that said bias controller means further comprises discharge-control device means (62), connected in parallel with said capacitor means (42), for forcibly discharging said capacitor means (42) at a first time constant which is larger than a second time constant for a natural decrease in optical output of said light-emitting element (10) and which is smaller than a third time constant for an ambient temperature decrease, so as to inhibit a natural increase in the optical output emitted from said light-emitting element (10) when a charging operation of said capacitor means (42) is stopped.

Claim 6

An optical signal transmitting apparatus comprising pulse generator means (14) for receiving a data signal (12) to be transmitted and for generating a corresponding pulse signal, and semiconductor light radiator means (10), connected to said pulse generator means (14), for radiating light in response to the pulse signal, characterized by further comprising photodetector means (24) for partially detecting the actual light radiated from said light radiator means (10) and for generating a corresponding electrical detection signal, and bias generator means (20, 60), electrically connected to said photodetector means (24) and said light radiator means (10), for receiving a sending request signal which defines a data transmission time of the data signal and controlling a radiation time of said light radiator means (10), and, responsive to the detection signal, for regulating a bias current supplied to said light radiator means (10) so as to compensate instability of the light radiation which is caused by a thermal influence, said bias generator means (20, 60) performing uni-directional automatic power control operation such that the bias current is only increased and supplied to said light radiator means (10) to generate light in compensation for a decrease therein due to the thermal influence within a data transmission time.

Claim 7

An optical signal transmitting apparatus comprising pulse generator means (14) for receiving a data signal (12) to be transmitted and for generating a corresponding pulse signal, and semiconductor light radiator means (10), connected to said pulse generator means (14), for radiating light in response to the pulse signal, characterized by further comprising photodetector means (24) for partially detecting the actual light radiated from said light radiator means (10) and for generating a corresponding electrical detection signal, and bias generator means (20, 60), electrically connected to said photodetector means (24) and said light radiator means (10), for receiving a sending request signal which defines a data transmission time of the data signal and controlling a radiation time of said light radiator means (10), and, responsive to the detection signal, for regulating a bias current supplied to said light radiator means (10) so as to compensate instability of the light radiation which is caused by a thermal influence, said bias generator means (20, 60) performing uni-directional automatic power control operation such that the bias current is only increased and supplied to said light radiator means (10) to generate light in compensation for a decrease therein due to the thermal influence within a data transmission time.

Claim 8

The apparatus according to claim 5, characterized by further comprising superposing means (22), electrically connected to said light radiator means (10), said pulse generator means (14) and said bias generator means (20, 60), for superposing the pulse signal from said pulse generator means (14) on the bias current from said bias generator means (20, 60), thereby supplying a superposed signal to said light radiator means (10).

Claim 9

The apparatus according to claim 6, characterized in that said bias generator means (20) receives the sending request signal for specifying a data transmission time which is short enough to permit the influence of an ambient temperature change on said light radiator means to be substantially neglected and to regard the light radiated from said light radiator means to be decreased pnly by heat radiation from itself; and wherein said bias generator means (20) comprises output light stabilizing control circuit means (28 ' , 34, 40, 42) for increasing a bias current supplied to said light radiator means (10) in response to the detection signal which is lowered below a predetermined reference level when the output light from said light radiator means has a lower intensity within the data transmission time, and for holding the bias current at a last current level when the detection signal has a higher level than the predetermined reference level.

Claim 10

The apparatus according to claim 7, characterized in that said output light stabilizing control circuit means (28, 34, 40, 42) comprises current source means (36) for producing a constant current, capacitor means (42) for receiving the constant current to be charged thereby, and current control circuit means (28, 34, 40) for receiving the sending request signal and the detection signal, and for controlling supply of the constant current to said capacitor means (42).

Claim 11

The apparatus according to claim 8, characterized in that said current control circuit means (28, 34, 40) includes a comparator (28), connected to said photodetector means (24), for comparing a level of the detection signal with the reference level and generating a comparison signal, a transistor circuit (34), connected between said capacitor means (42) and said current source means (36), for performing switching operation, and logic circuit means (40), connected to said comparator (28) and said transistor circuit (34), for controlling the switching operation of said transistor circuit (34) in response to the sending request signal and the comparison signal, whereby supply and cutoff operations of the constant current with respect to said capacitor means (42) are performed.

Claim 12

The apparatus according to claim 9, characterized in that the data transmission time is set to be a maximum of several miliseconds, thereby achieving burst optical data transmission.

Claim 13

The apparatus according to claim 6, characterized in that said bias generator means (60) receives the sending request signal for specifying a data transmission time which is long enough to regard the output light from said light radiator means (10) to be influenced by an ambient temperature change and heat radiation thereof; and wherein said bias generator means (60) comprises: first control circuit means (28, 34, 40, 42) for increasing a bias current supplied to said light radiator means (10) in response to the detection signal which is lowered below a predetermined reference level when the output light from said light radiator means has a lower intensity within the data transmission time, and for holding the bias current at a last current level when the detection signal has a higher level than the predetermined reference level; and second control circuit means (62), electrically connected to said first control circuit means (28, 34, 40, 42), for forcibly decreasing the bias current at a first time constant (T3) which is larger than a second time constant (Tl) for a natural decrease in optical output of said light-emitting element and which is smaller than a third time constant (T2) for an ambient temperature change when said first control circuit means (28, 34, 40, 42) holds the bias current at the predetermined reference level, thereby preventing the light output of said light radiator means (10) from being naturally increased due to an ambient temperature decrease.

Claim 14

The apparatus according to claim 11, characterized in that said output light stabilizing control circuit means (28, 34, 40, 42) comprises current source means (36) for producing a constant current, capacitor means (42) for receiving the constant current to be charged thereby, and current control circuit means (28, 34, 40) for receiving the sending request signal and the detection signal, and for controlling supply of the constant current to said capacitor means (42).

Claim 15

The apparatus according to claim 12, characterized in that said current control circuit means (28, 34, 40) includes a comparator (28), connected to said photodetector means (24), for comparing a level of the detection signal with the reference level and generating a comparison signal, a transistor circuit (34), connected between said capacitor means (42) and said current source means (36), for performing switching operation, and logic circuit means (40), connected to said comparator (28) and said transistor circuit (34), for controlling the switching operation of said transistor circuit (34) in response to the sending request signal and the comparison signal, whereby supply and cutoff operations of the constant current with respect to said capacitor means (42) are performed.

Claim 16

The apparatus according to claim 13, characterized in that said second control circuit means includes discharge-control device means (62), connected in parallel with said capacitor means (42), for partially discharging said capacitor means (42).