Discharge-lamp lighting apparatus and projector

Abstract

A discharge-lamp lighting apparatus includes a control circuit that determines electric power supplied to a high-pressure discharge lamp after the high-pressure discharge lamp is started by an igniter. The electric power is determined in accordance with a voltage corresponding to a lamp voltage detected by a voltage detection circuit and a drive current detected by a current detection circuit. When the determined electric power is less than predetermined electric power, the control circuit causes a down chopper to control the drive current such that an amount of increase in the electric power per unit time becomes equal to or less than a predetermined value.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating the structure of a discharge-lamp lighting apparatus according to a first embodiment of the preset invention.

FIG. 2 is a diagram illustrating light returning from a secondary mirror in a lamp having the secondary mirror.

FIG. 3 is a graph showing the lamp voltage and the lamp current of the lamp having the secondary mirror.

FIG. 4 is a graph showing the lamp power of the lamp having the secondary mirror.

FIG. 5 is a graph showing the lamp voltage and the lamp current according to the first embodiment of the present invention.

FIG. 6 is a graph showing the lamp power according to the first embodiment of the present invention.

FIG. 7 is an optical structure diagram of a projector according to a second embodiment of the present invention.

Claims

1. A discharge-lamp lighting apparatus comprising: a direct-current power supply circuit that receives a direct-current voltage and performs current control for supplying predetermined electric power to a high-pressure discharge lamp;an inverter that converts a current outputted from the direct-current power supply circuit into an alternating current with a predetermined frequency and supplies a drive current to the high-pressure discharge lamp;an igniter that is connected to an output terminal of the inverter and that generates a high voltage at the start of lighting to start the high-pressure discharge lamp;a voltage detection circuit that detects a voltage corresponding to a lamp voltage of the high-pressure discharge lamp;a current detection circuit that detects a current corresponding to the drive current of the high-pressure discharge lamp; anda control unit for controlling the direct-current power supply circuit, the inverter, and the igniter,wherein, after the start of the high-pressure discharge lamp by the igniter, the control unit determines electric power supplied to the high-pressure discharge lamp in accordance with the voltage corresponding to the lamp voltage detected by the voltage detection circuit and the drive current detected by the current detection circuit, andwherein, when the determined electric power is less than predetermined electric power, the control unit causes the direct-current power supply circuit to control the drive current such that a rate of increase in the electric power supplied to the high-pressure discharge lamp becomes equal to or less than a predetermined value.

2. The discharge-lamp lighting apparatus according to claim 1, wherein, when the electric power supplied to the high-pressure discharge lamp is less than the predetermined electric power, the control unit causes the direct-current power supply circuit to control the drive current such that the rate of increase in the electric power supplied to the high-pressure discharge lamp becomes equal to the predetermined value.

3. The discharge-lamp lighting apparatus according to claim 1, wherein, when the electric power supplied to the high-pressure discharge lamp is less than the predetermined electric power, the control unit causes the direct-current power supply circuit to reduce the drive current supplied by the direct-current power supply circuit with time.

4. The discharge-lamp lighting apparatus according to claim 1, wherein, when the electric power supplied to the high-pressure discharge lamp reaches the predetermined electric power, the control unit causes the direct-current power supply circuit to control the drive current such that the electric power supplied to the high-pressure discharge lamp is maintained at the predetermined electric power.

5. The discharge-lamp lighting apparatus according to claim 1, wherein the high-pressure discharge lamp to which the direct-current power supply circuit supplies the drive current is provided with a secondary mirror.

6. A projector comprising: a high-pressure discharge lamp that has or does not have a secondary mirror;the discharge-lamp lighting apparatus according to claim 1;at least one spatial light modulator;an optical system for guiding light from the high-pressure discharge lamp to the spatial light modulator; anda projecting unit for projecting an image formed by the spatial light modulator onto a screen.

7. A projector comprising: a high-pressure discharge lamp that has or does not have a secondary mirror;the discharge-lamp lighting apparatus according to claim 2;at least one spatial light modulator;an optical system for guiding light from the high-pressure discharge lamp to the spatial light modulator; anda projecting unit for projecting an image formed by the spatial light modulator onto a screen.

8. A projector comprising: a high-pressure discharge lamp that has or does not have a secondary mirror;the discharge-lamp lighting apparatus according to claim 3;at least one spatial light modulator;an optical system for guiding light from the high-pressure discharge lamp to the spatial light modulator; anda projecting unit for projecting an image formed by the spatial light modulator onto a screen.

9. A projector comprising: a high-pressure discharge lamp that has or does not have a secondary mirror;the discharge-lamp lighting apparatus according to claim 4;at least one spatial light modulator;an optical system for guiding light from the high-pressure discharge lamp to the spatial light modulator; anda projecting unit for projecting an image formed by the spatial light modulator onto a screen.

10. A projector comprising: a high-pressure discharge lamp that has or does not have a secondary mirror;the discharge-lamp lighting apparatus according to claim 5;at least one spatial light modulator;an optical system for guiding light from the high-pressure discharge lamp to the spatial light modulator; anda projecting unit for projecting an image formed by the spatial light modulator onto a screen.