Abstract: Disclosed is a laser driving technique capable of reducing power consumption in a laser driving circuit to achieve reduced heat generation in an optical pickup of a recording/reading equipment for an optical disc. A base-voltage control circuit is connected to a base of a grounded-base cascode transistor connected between a driver circuit and a laser diode (LD), and a LD-anode-voltage control circuit is connected to an anode of the laser diode. The base-voltage control circuit and the LD-anode-voltage control circuit are connected to a controller, and operable to variously change an anode voltage of the laser diode and a base voltage of the cascode transistor depending on a driving current for the laser diode.

Abstract: The laser drive circuit of the present invention includes a first drive circuit 105 receiving an input of a current from a variable current source 103 and a first pulse control signal 101 and outputting a first drive current in synchronism with the first pulse control signal 101; a pulse output circuit 107 outputting a pulse signal in response to a falling edge of the first pulse control signal 101; and a second drive circuit 106 receiving an input of a current from a variable current source 104 and a second pulse control signal 102, generating a second drive current in synchronism with the second pulse control signal 102, and outputting a decreased current value of the second drive current at least in synchronism with the pulse signal. According to this configuration, the falling time of the pulse can be shortened regardless of the relationship between the voltage of a laser connecting terminal and the power source voltage of a drive circuit or a ground voltage.

Abstract: A laser driving device is provided that can support a higher speed and drives a semiconductor laser (3) to emit light in a pulse-like manner in accordance with a digital signal. The laser driving device includes a temperature sensor (5), a recording pulse generator (1), an auxiliary pulse generator (4), and an adder (8). The temperature sensor (5) produces a measured temperature that changes in accordance with a temperature of the semiconductor laser. The recording pulse generator (1), the auxiliary pulse generator (4), and the adder (8) produce a pulse-like signal having a shape corresponding to the measured temperature.

Abstract: Disclosed is a laser driving technique capable of reducing power consumption in a laser driving circuit to achieve reduced heat generation in an optical pickup of a recording/reading equipment for an optical disc. A base-voltage control circuit is connected to a base of a grounded-base cascode transistor connected between a driver circuit and a laser diode (LD), and a LD-anode-voltage control circuit is connected to an anode of the laser diode. The base-voltage control circuit and the LD-anode-voltage control circuit are connected to a controller, and operable to variously change an anode voltage of the laser diode and a base voltage of the cascode transistor depending on a driving current for the laser diode.

Abstract: The laser drive circuit of the present invention includes a first drive circuit 105 receiving an input of a current from a variable current source 103 and a first pulse control signal 101 and outputting a first drive current in synchronism with the first pulse control signal 101; a pulse output circuit 107 outputting a pulse signal in response to a falling edge of the first pulse control signal 101; and a second drive circuit 106 receiving an input of a current from a variable current source 104 and a second pulse control signal 102, generating a second drive current in synchronism with the second pulse control signal 102, and outputting a decreased current value of the second drive current at least in synchronism with the pulse signal. According to this configuration, the falling time of the pulse can be shortened regardless of the relationship between the voltage of a laser connecting terminal and the power source voltage of a drive circuit or a ground voltage.

Abstract: A laser diode driving device of the present invention can appropriately shorten the rising time and the falling time of a laser diode drive current in a range from a small current region to a large current region. In synchronization with the addition of an original input current from an input constant current source to the laser diode drive current amplifier, a differentiated current is added to the input current through a differentiation circuit and a pull-in type V-I conversion circuit, whereby the rising of a laser diode drive current is made abrupt. Furthermore, by increasing a gate potential of an input PchMOS transistor constituting the laser diode drive current amplifier by a differentiation circuit and a push-out type V-I conversion circuit in synchronization with the disconnection of an input current, the falling of a laser diode drive current is made abrupt.

Abstract: A laser driving device is provided that can support a higher speed and drives a semiconductor laser (3) to emit light in a pulse-like manner in accordance with a digital signal. The laser driving device includes a temperature sensor (5), a recording pulse generator (1), an auxiliary pulse generator (4), and an adder (8). The temperature sensor (5) produces a measured temperature that changes in accordance with a temperature of the semiconductor laser. The recording pulse generator (1), the auxiliary pulse generator (4), and the adder (8) produce a pulse-like signal having a shape corresponding to the measured temperature.

Abstract: A laser diode driving device of the present invention can appropriately shorten the rising time and the falling time of a laser diode drive current in a range from a small current region to a large current region. In synchronization with the addition of an original input current from an input constant current source to the laser diode drive current amplifier, a differentiated current is added to the input current through a differentiation circuit and a pull-in type V-I conversion circuit, whereby the rising of a laser diode drive current is made abrupt. Furthermore, by increasing a gate potential of an input PchMOS transistor constituting the laser diode drive current amplifier by a differentiation circuit and a push-out type V-I conversion circuit in synchronization with the disconnection of an input current, the falling of a laser diode drive current is made abrupt.