Discharge lamp lighting apparatus and projector

• US 20070188113A1
• Filed: 02/12/2007
• Published: 08/16/2007
• Est. Priority Date: 02/10/2006
• Status: Active Grant

• Current Assignee: Ushio Denki Kabushiki Kaisha
• Original Assignee: Ushio Denki Kabushiki Kaisha
• Inventors: Okamoto, Masashi
• Granted Patent: US 7,567,041 B2
• Time in Patent Office: Days
• US Class Current: 315/291
• CPC Class Codes: H05B 41/2882 the control resulting from an action on the static converter

Abstract

In a lamp lighting apparatus for lighting a high intensity discharge lamp, which is used for a projector, it is possible to carry out high speed modulation of brightness of the discharge lamp, in synchronization with a conversion operation to sequential color light flux which is carried out by using a dynamic filter such as a rotation color wheel, and it is also possible to switch modulation patterns by electric control. A lamp current detection signal conversion circuit has two or more switching elements whose ON/OFF state is controlled corresponding to truth/false of respective bits of modulation signal, in which a gain can be changed by a combination of truth and false of the respective bits of the modulation signal. When a modulation switching timing signal is received, an original modulation signal is updated by selecting a bit set corresponding to a value counted by a modulation change count section.

Claims

1. A discharge lamp lighting apparatus for initiating and lighting a discharge lamp of a projector which displays an image by using sequential color light flux which is converted by a dynamic filter from light flux generated by the discharge lamp,

wherein the discharge lamp lighting apparatus includes a power supply circuit which supplies power to the discharge lamp, a lamp voltage detection circuit which generates a lamp voltage detection signal by detecting lamp voltage, a lamp current detection circuit which generates a lamp current detection circuit by detecting lamp current, a lamp current detection signal conversion circuit which converts the lamp current detection signal, a power supply capacity control circuit which controls the power supply circuit so that a difference between a lamp current correlation signal from the lamp current detection signal conversion circuit and a lamp current target signal showing a value of current flowing through the discharge lamp becomes small, a power supply circuit which updates the lamp current target signal so that a load power value supplied to the discharge lamp becomes a predetermined target power value, depending on the lamp voltage detection signal, and a modulation signal generation circuit which generates two or more binary modulation signals,

wherein the lamp current detection signal conversion circle includes two or more switching elements whose ON/OFF stage is controlled in response to a truth/false of respective bits of the modulation signals, in which the gain the lamp current detection signal conversion circle is changed based on a combination of truth and false of bits of the modulation signals,

wherein the modulation signal generation circuit includes modulation signal resisters which holds respective bits of the modulation signals, and an original modulation signal generation circuit which generates an original modulation signal which is set in the modulation signal resister,

wherein the original modulation signal generation circuit includes a modulation bit set memory unit in which an original modulation bit set for the original modulation signals is stored in relation to respective colors of the dynamic color filter,

wherein the modulation signal generation circuit sets the original modulation signal in the modulation signal resister in synchronization with a modulation switching timing signal which is generated based on an operation of the dynamic color filter in order to specify timing for switching a modulation state,

wherein the original modulation signal generation circuit has a modulation change count section which counts the received modulation switching timing signal, and

wherein when the modulation switching timing signal is received, and then a next modulation switching timing signal is inputted, a bit set corresponding to a counted value of the modulation change count section is selected from the original modulation bit set stored in the modulation bit set memory unit and the original modulation signal is updated, so as to be a value set in the modulation signal resistors and the counted value of the modulation change count section is updated.

2. The discharge lamp lighting apparatus according to claim 1, wherein the modulation switching timing signal is modulated based on the operation of the dynamic color filter in order to specify a phrase of a sequential color cycle, and the modulation signal generation circuit has an initialization information demodulation circuit which determines whether the modulation switching timing signal is modulated, and when the initialization information demodulation circuit determine that the modulation switching timing signal is modulated, an operation by which the counted value of the modulation change count section is initialized is set.

3. The discharge lamp lighting apparatus, according to claim 1, wherein the original modulation signal generation circuit generates a current target update permission signal during a period from the modulation switching timing signal in the sequential color cycle of the dynamic filter to the next modulation switching timing signal, and when the current target update permission signal is in an inactive state, the lamp current target signal is not updated.

4. The discharge lamp lighting apparatus, according to claim 2, wherein the original modulation signal generation circuit generates a current target update permission signal during a period from the modulation switching timing signal in the sequential color cycle of the dynamic filter to the next modulation switching timing signal, and when the current target update permission signal is in an inactive state, the lamp current target signal is not updated.

5. The discharge lamp lighting apparatus according to claim 1, further including an inverter which drives the discharge lamp in an alternating current manner, in which polarity of voltage applied to the discharge lamp is inverted, and an inverter controlling circuit which controls an operation of the inverter, wherein the inverter controlling circuit causes the inverter to invert the polarity when receiving the modulation switching timing signal under a specific sequential color condition of the dynamic filter.

6. The discharge lamp lighting apparatus according to claim 2, further including an inverter which drives the discharge lamp in an alternating current manner, in which polarity of voltage applied to the discharge lamp is inverted, and an inverter controlling circuit which controls an operation of the inverter, wherein the inverter controlling circuit causes the inverter to invert the polarity when receiving the modulation switching timing signal under a specific sequential color condition of the dynamic filter.

7. The discharge lamp lighting apparatus according to claim 3, further including an inverter which drives the discharge lamp in an alternating current manner, in which polarity of voltage applied to the discharge lamp is inverted, and an inverter controlling circuit which controls an operation of the inverter, wherein the inverter controlling circuit causes the inverter to invert the polarity when receiving the modulation switching timing signal under a specific sequential color condition of the dynamic filter.

8. The discharge lamp lighting apparatus according to claim 4, further including an inverter which drives the discharge lamp in an alternating current manner, in which polarity of voltage applied to the discharge lamp is inverted, and an inverter controlling circuit which controls an operation of the inverter, wherein the inverter controlling circuit causes the inverter to invert the polarity when receiving the modulation switching timing signal under a specific sequential color condition of the dynamic filter.

9. The discharge lamp lighting apparatus according to claim 5, wherein the inverter controlling circuit has an inverter polarity resister which holds an inverter polarity signal which is a bit signal corresponding to a polarity state of the inverter, and an original inverter polarity signal generation circuit which generates an original inverter polarity signal set in the inverter polarity resister, and the original inverter polarity signal is set in the inverter polarity resister in synchronization with the modulation switching timing signal, and wherein after the original inverter polarity signal generation circuit receives the modulation switching timing signal, the original inverter polarity signal generation circuit updates the original inverter polarity signal so as to be a value set in the inverter polarity resister when the next modulation switching timing signal is inputted.

10. The discharge lamp lighting apparatus according to claim 6, wherein the inverter controlling circuit has an inverter polarity resister which holds an inverter polarity signal which is a bit signal corresponding to a polarity state of the inverter, and an original inverter polarity signal generation circuit which generates an original inverter polarity signal set in the inverter polarity resister, and the original inverter polarity signal is set in the inverter polarity resister in synchronization with the modulation switching timing signal, and wherein after the original inverter polarity signal generation circuit receives the modulation switching timing signal, the original inverter polarity signal generation circuit updates the original inverter polarity signal so as to be a value set in the inverter polarity resister when the next modulation switching timing signal is inputted.

11. he discharge lamp lighting apparatus according to claim 7, wherein the inverter controlling circuit has an inverter polarity resister which holds an inverter polarity signal which is a bit signal corresponding to a polarity state of the inverter, and an original inverter polarity signal generation circuit which generates an original inverter polarity signal set in the inverter polarity resister, and the original inverter polarity signal is set in the inverter polarity resister in synchronization with the modulation switching timing signal, and wherein after the original inverter polarity signal generation circuit receives the modulation switching timing signal, the original inverter polarity signal generation circuit updates the original inverter polarity signal so as to be a value set in the inverter polarity resister when the next modulation switching timing signal is inputted.

12. he discharge lamp lighting apparatus according to claim 8, wherein the inverter controlling circuit has an inverter polarity resister which holds an inverter polarity signal which is a bit signal corresponding to a polarity state of the inverter, and an original inverter polarity signal generation circuit which generates an original inverter polarity signal set in the inverter polarity resister, and the original inverter polarity signal is set in the inverter polarity resister in synchronization with the modulation switching timing signal, and wherein after the original inverter polarity signal generation circuit receives the modulation switching timing signal, the original inverter polarity signal generation circuit updates the original inverter polarity signal so as to be a value set in the inverter polarity resister when the next modulation switching timing signal is inputted.

13. A projector in which light flux generated by a discharge lamp is converted by a dynamic filter into sequential color light flux so that an image is displayed by using the sequential color light flux, wherein the discharge lamp is initiated so as to be lighted, by the discharge lamp lighting apparatus according to claim 1.