Semiconductor laser driving device, semiconductor laser driving method, and image forming apparatus using semiconductor laser driving device

A semiconductor laser driving device which performs a driving control of a semiconductor laser to control current supplied to the laser so that a desired amount of emission light is obtained, said semiconductor laser driving device comprising:

• a first current generating unit generating a first current that is below an oscillation threshold current of the laser, and outputting the first current to the laser invariably;
• a second current generating unit generating a second current that is needed for light emission of the laser responsive to an input signal, and outputting the second current to the laser;
• a third current generating unit generating a third current that controls the laser such that a detected amount of emission light from the laser accords with a given value, and outputting the third current to the laser;
• an auxiliary current generating unit outputting a predetermined auxiliary current to the laser in response to a control signal;
• and
• an initialization unit performing an initialization operation to detect luminescence characteristics of the laser, and outputting a signal, indicating a value of the second current derived from the detected luminescence characteristics, to the second current generating unit,
• wherein the third current generating unit controls the third current so that an amount of light outputted by the laser which receives a sum of the first current, the second current, the third current and the auxiliary current, accords with a predetermined amount.

A semiconductor laser driving method which performs a driving control of a semiconductor laser to control current supplied to the laser so that a desired amount of emission light is obtained, said method comprising the steps of:

• generating a first current that is below an oscillation threshold current of the laser;
• generating a second current that is needed for light emission of the laser responsive to an input signal;
• generating a third current that controls the laser such that a detected amount of emission light from the laser accords with a given value;
• performing an initialization operation to detect not only first luminescence characteristics of the laser at a normal temperature but also second luminescence characteristics of the laser at a predetermined high temperature when a same amount of light is outputted by the laser for the two temperatures;
• and
• generating an auxiliary current so that the generated auxiliary current is larger than a difference between a value of the second current derived from the first luminescence characteristics and a value of the second current derived from the second luminescence characteristics;
• wherein the third current is controlled so that an amount of light outputted by the laser which receives a sum of the first current, the second current, the third current and the auxiliary current, accords with a predetermined amount.

An image forming apparatus including a semiconductor laser driving device which performs a driving control of a semiconductor laser to control current supplied to the laser so that a desired amount of emission light is obtained, said semiconductor laser driving device comprising:

• a first current generating unit generating a first current that is below an oscillation threshold current of the laser, and outputting the first current to the laser invariably;
• a second current generating unit generating a second current that is needed for light emission of the laser responsive to an input signal;
• a third current generating unit generating a third current that controls the laser such that a detected amount of emission light from the laser accords with a given value, and outputting the third current to the laser;
• an auxiliary current control unit causing the second current generating unit to generate a predetermined auxiliary current, the second current generating unit outputting a sum of the second current and the auxiliary current to the laser;
• and
• an initialization unit performing an initialization operation to detect luminescence characteristics of the laser, and outputting a signal, indicating a value of the second current derived from the detected luminescence characteristics, to the second current generating unit,
• wherein the third current generating unit controls the third current so that an amount of light outputted by the laser which receives a sum of the first current, the second current, the third current and the auxiliary current, accords with a predetermined amount.

An image forming apparatus including a semiconductor laser driving device which performs a driving control of a semiconductor laser to control current supplied to the laser so that a desired amount of emission light is obtained, said semiconductor laser driving device comprising:

• a first current generating unit generating a first current that is below an oscillation threshold current of the laser, and outputting the first current to the laser invariably;
• a second current generating unit generating a second current that is needed for light emission of the laser responsive to an input signal, and outputting the second current to the laser;
• a third current generating unit generating a third current that controls the laser such that a detected amount of emission light from the laser accords with a given value, and outputting the third current to the laser;
• an auxiliary current generating unit outputting a predetermined auxiliary current to the laser in response to a control signal;
• and
• an initialization unit performing an initialization operation to detect luminescence characteristics of the laser, and outputting a signal, indicating a value of the second current derived from the detected luminescence characteristics, to the second current generating unit,
• wherein the third current generating unit controls the third current so that an amount of light outputted by the laser which receives a sum of the first current, the second current, the third current and the auxiliary current, accords with a predetermined amount.