Filament lamp light quantity control method and filament lamp light quantity control unit and filament lamp light source unit

A filament lamp light quantity control unit for controlling a light quantity of a filament lamp, comprising:

• a current detection sensor connected in series to the filament lamp having a characteristic in which a change in a light quantity of a lamp is substantially proportionate to the square of a power consumption;
• a multiplication circuit for generating a voltage Vw proportionate to a product of a terminal voltage V of the filament lamp and an output voltage Vi of said current detection sensor;
• a multiplication circuit for generating a voltage VWW proportionate to the square root of said voltage VW;
• an error amplifier circuit for controlling an error to the minimum by comparing the output voltage VWW of said multiplication circuit and the control voltage Vc;
• and
• a constant voltage source unit for supplying an electric power to the filament lamp, the unit being connected to an output terminal of the error amplifier circuit.

A filament lamp light source unit for controlling a light quantity of a filament lamp, comprising:

• a filament lamp having a characteristic in which a light quantity of the lamp is substantially proportionate to a square of a power consumption;
• a current detection sensor connected in series to the filament lamp;
• a multiplication circuit for generating a voltage Vw proportionate to the product of a terminal voltage V of the filament lamp and an output voltage Vi of said current detection sensor;
• a multiplication circuit for generating a voltage VWW proportionate to the square of said voltage VW;
• an error amplifier circuit for controlling an error to the minimum by comparing the output voltage VWW of said multiplication circuit and the control voltage Vc;
• and
• a constant voltage power source unit for supplying an electric power to the filament lamp, the unit being connected to an output terminal of the error amplifier circuit.

A microscopic halogen lamp light source unit for controlling a light quantity of a halogen lamp, comprising:

• a current detection sensor connected in series to a lamp having a characteristic in which a change in a light quantity of a lamp is substantially proportionate to a square of a power consumption;
• a multiplication circuit for generating a voltage Vw proportionate to a product of a voltage V of the lamp and an output voltage Vi of said current detection sensor;
• a multiplication circuit for generating a voltage VWW proportionate to the square root of said voltage VW;
• an error amplifier circuit for controlling an error to the minimum by comparing the output voltage VWW of said multiplication circuit and the control voltage Vc;
• and
• a constant voltage power source unit for supplying an electric power to the lamp, the unit being connected to an output terminal of the error amplifier circuit.