Projector using ballast controlled high-pressure discharge lamps

• US 8,042,953 B2
• Filed: 02/23/2009
• Issued: 10/25/2011
• Est. Priority Date: 02/25/2008
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Takezawa, Takeshi
• Primary Examiner(s): Epps; Georgia Y
• Assistant Examiner(s): NAPHAS, RENEE D
• Application Number:
  US12/390,787
• Publication Number:
  US 20090213336A1
• Time in Patent Office: 974 Days
• Field of Search: 313/113, 315/144, 315/225, 315/291, 315/307, 353/30, 353/38, 353/85, 353/86, 353/94
• US Class Current: 353/85
• CPC Class Codes: H04N 9/3155 for controlling the light source light source control per se H05B35/00 – H05B47/00; control of an illumination source for displays in general G09G3/3406
• CPC Class Codes: H04N 9/3161 using laser light sources using laser beams scanning the display screen H04N9/3129
• CPC Class Codes: H04N 9/3164 using multiple light sources
• CPC Class Codes: H05B 41/2887 characterised by a controllable bridge in the final stage
• CPC Class Codes: H05B 41/38 Controlling the intensity of light
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

A projector includes: plural high-pressure discharge lamps; a high-pressure discharge lamp lighting device for lighting the plural high-pressure discharge lamps; a light combining system that combines and outputs lights from the plural high-pressure discharge lamps; an electro-optical modulation device that modulates the light from the light combining system according to image information; and a projection system that projects the light modulated by the electro-optical modulation device, wherein the high-pressure discharge lamp lighting device supplies alternating lamp currents having alternating-current waveforms with the same waveform and period and phases shifted by a predetermined amount with respect to each of the high-pressure discharge lamps to the respective plural high-pressure discharge lamps.

Claims

1. A projector comprising:

plural high-pressure discharge lamps;

a high-pressure discharge lamp lighting device that lights the plural high-pressure discharge lamps;

a light combining system that combines and outputs lights from the plural high-pressure discharge lamps;

an electro-optical modulation device that modulates the light from the light combining system according to image information; and

a projection system that projects the light modulated by the electro-optical modulation device,

the high-pressure discharge lamp lighting device supplying alternating lamp currents having alternating-current waveforms with the same waveform and period and phases shifted by a predetermined amount with respect to each of the high-pressure discharge lamps to the respective plural high-pressure discharge lamps;

the high-pressure discharge lamp lighting device having;

plural ballasts respectively corresponding to the plural high-pressure discharge lamps; and

a control circuit that integrally controls the plural ballasts to supply alternating lamp currents having the alternating-current waveforms to the respective plural high-pressure discharge lamps;

the high-pressure discharge lamp lighting device being configured to detect rises of the alternating lamp currents and control the plural ballasts based on detection information on the rises of the alternating lamp currents.

2. The projector according to claim 1, given that the amount of phase shift is X (unit:

period) and the number of the high-pressure discharge lamps is n (unit;

number), is satisfied.

3. The projector according to claim 1, the high-pressure discharge lamp lighting device having:

plural control circuits respectively corresponding to the plural ballasts and respectively integrally controls the ballasts to supply the alternating lamp currents having the alternating-current waveforms to the respective plural high-pressure discharge lamps,

one control circuit of the plural control circuits being configured to output control information on the ballast controlled by the control circuit itself to the other control circuit, and

the other control circuit being configured to control the corresponding ballast based on the control information from the one control circuit.

4. The projector according to claim 1, the alternating-current waveform being a waveform in which an instantaneous value of current gradually increases with time in a half period.

5. The projector according to claim 1, the alternating-current waveform being a waveform in which a current pulse is superimposed on the alternating lamp current immediately before the reversal of polarity so that a current value immediately before reversal of polarity is higher than a current value of the alternating-current.

6. A projector comprising:

a plurality of high-pressure discharge lamps;

a high-pressure discharge lamp lighting device that lights the plurality of high-pressure discharge lamps;

a light combining system that combines and outputs lights from the plurality high-pressure discharge lamps;

an electro-optical modulation device that modulates the light from the light combining system according to image information; and

a projection system that projects the light modulated by the electro-optical modulation device,

the high-pressure discharge lamp lighting device supplying alternating lamp currents to the respective plural high-pressure discharge lamps, the alternating lamp currents being triangular waves;

the high-pressure discharge lamp lighting device having;

plural ballasts respectively corresponding to the plurality of high-pressure discharge lamps; and

a control circuit that integrally controls the plural ballasts to supply the alternating lamp currents having alternating-current waveforms to respective high-pressure discharge lamps;

the high-pressure discharge lamp lighting device being configured to detect rises of the alternating lamp currents and control the plural ballasts based on detection information on the rises of the alternating lamp currents.

7. The projector according to claim 6, the alternating lamp currents having alternating-current waveforms with an amount of phase shift periods being equal to half the number of high-pressure discharge lamps.