Discharge lamp driving device, projector, and discharge lamp driving method

Patent metadata

Field	Value
Publication number	US-9867265-B2
Application number	US-201615168634-A
Country	US
Kind code	B2
Filing date	May 31, 2016
Priority date	Jun 4, 2015
Publication date	Jan 9, 2018
Grant date	Jan 9, 2018

Abstract

A discharge lamp driving device according to one aspect of the invention includes a discharge lamp driving section configured to supply a driving current to a discharge lamp including electrodes and a control section configured to control the discharge lamp driving section. The control section controls the discharge lamp driving section such that a mixed period is provided in which a first period in which an alternating current having a first frequency is supplied to the discharge lamp and a second period in which a direct current is supplied to the discharge lamp are alternately repeated. The first frequency includes a plurality of frequencies different from one another. The control section temporally changes the length of the first period.

First claim

What is claimed is:

1. A discharge lamp driving device comprising:
a discharge lamp driving section configured to supply a driving current to a discharge lamp including electrodes; and
a control section configured to control the discharge lamp driving section, wherein
the control section controls the discharge lamp driving section such that a mixed period is provided in which a first period in which an alternating current is supplied to the discharge lamp and a second period in which a direct current is supplied to the discharge lamp are alternately repeated,
the first period includes a plurality of AC periods including a first AC period and a second AC period,
a frequency of alternating current supplied in the first AC period and a frequency of alternating current supplied in the second AC period are different from one another, and
the control section changes a total length of time of the plurality of the AC periods included in the first period.

2. The discharge lamp driving device according to claim 1 , wherein the control section repeats the total length of time change in multiple instances of the first period.

3. A projector comprising:
a discharge lamp configured to emit light;
the discharge lamp driving device according to claim 2 ;
a light modulating device configured to modulate light emitted from the discharge lamp according to an image signal; and
a projection optical system configured to project the light modulated by the light modulating device.

4. The discharge lamp driving device according to claim 1 , wherein
the control section changes lengths of time of each of the plurality of AC periods included in the first period.

5. A projector comprising:
a discharge lamp configured to emit light;
the discharge lamp driving device according to claim 4 ;
a light modulating device configured to modulate light emitted from the discharge lamp according to an image signal; and
a projection optical system configured to project the light modulated by the light modulating device.

6. The discharge lamp driving device according to claim 1 , further comprising:
a voltage detecting section configured to detect an inter-electrode voltage of the discharge lamp, wherein
the control section sets the frequency of alternating current supplied in the first AC period based on the detected inter-electrode voltage, and
the frequency of alternating current supplied in the first AC period is set higher as the inter-electrode voltage is higher.

7. The discharge lamp driving device according to claim 1 , wherein
the control section sets the frequency of alternating current supplied in the first AC period based on driving power supplied to the discharge lamp, and
the frequency of alternating current supplied in the first AC period is set higher as the driving power is smaller.

8. The discharge lamp driving device according to claim 1 , wherein
the second AC period occurs after the first AC period, and
the frequency of alternating current supplied in the second AC period is lower than the frequency of alternating current supplied in the first AC period.

9. The discharge lamp driving device according to claim 1 , further comprising:
a voltage detecting section configured to detect an inter-electrode voltage of the discharge lamp, wherein
the control section cyclically changes the total length of time and changes a cycle of the change in the total length of time based on at least one of the detected inter-electrode voltage and driving power supplied to the discharge lamp.

10. The discharge lamp driving device according to claim 9 , wherein, when the detected inter-electrode voltage is higher than a first voltage, the control section sets the cycle shorter as the detected inter-electrode voltage is higher.

11. The discharge lamp driving device according to claim 10 , wherein, when the detected inter-electrode voltage is higher than a second voltage higher than the first voltage, the control section sets the cycle longer as the detected inter-electrode voltage is higher.

12. The discharge lamp driving device according to claim 10 , wherein, when the detected inter-electrode voltage is equal to or lower than the first voltage, the control section maintains the cycle fixed.

13. The discharge lamp driving device according to claim 9 , wherein, when the driving power is larger than a first driving power, the control section sets the cycle longer as the driving power is larger.

14. The discharge lamp driving device according to claim 13 , wherein, when the driving power is equal to or smaller than the first driving power, the control section maintains the cycle fixed.

15. The discharge lamp driving device according to claim 9 , wherein the control section cyclically repeats the total length of time change in multiple instances of the first period.

16. The discharge lamp driving device according to claim 9 , wherein
the control section cyclically changes lengths of time of each of the plurality of AC periods included in the first period.

17. A projector comprising:
a discharge lamp configured to emit light;
the discharge lamp driving device according to claim 9 ;
a light modulating device configured to modulate light emitted from the discharge lamp according to an image signal; and
a projection optical system configured to project the light modulated by the light modulating device.

18. A projector comprising:
a discharge lamp configured to emit light;
the discharge lamp driving device according to claim 1 ;
a light modulating device configured to modulate light emitted from the discharge lamp according to an image signal; and
a projection optical system configured to project the light modulated by the light modulating device.

19. The discharge lamp driving device of claim 1 , wherein the mixed period is provided while supplying a single lamp power.

20. The discharge lamp driving device of claim 1 , wherein the mixed period is started with the first period.

21. A discharge lamp driving method for supplying a driving current to a discharge lamp including electrodes and driving the discharge lamp, the method comprising:
supplying, to the discharge lamp, the driving current including a mixed period in which a first period in which an alternating current is supplied to the discharge lamp and a second period in which a direct current is supplied to the discharge lamp are alternately repeated, the first period including a plurality of AC periods including a first AC period and a second AC period, a frequency of alternating current supplied in the first AC period and a frequency of alternating current supplied in the second AC period being different from one another; and
changing a total length of time of the plurality of the AC periods included in the first period.

22. The discharge lamp driving method according to claim 21 , further comprising:
cyclically changing the total length of time; and
changing a cycle of the change in the total length of time.

Assignees

• Seiko Epson Corp

Inventors

• Sato Shun
• Suzuki Junichi
• Kito Satoshi

Classifications

• H01J61/025

  Associated optical elements · CPC title

• H05B41/2887 Primary

  characterised by a controllable bridge in the final stage · CPC title

• H01J61/073

  for high-pressure discharge lamps · CPC title

• H05B41/392

  using semiconductor devices, e.g. thyristor · CPC title

• G03B21/2026

  Gas discharge type light sources, e.g. arcs · CPC title