Light source device, projection display device, and light source control method

1. A light source device comprising:

a phosphor rotating body on which a phosphor formed on a surface and that is used in a state of rotation having an axis of rotation that is perpendicular to said surface;

a first excitation light source that irradiates first excitation light upon a first position that is separated by a predetermined distance from the center of rotation on said surface to cause emission of a first fluorescent light;

a detection light generation unit that irradiates detection light upon a second position that differs from said first position and that is separated by said predetermined distance from said center of rotation on said surface;

an optical detection unit that supplies a detection signal that corresponds to emission light that is emitted from said phosphor rotating body in response to said detection light; and

a control unit that receives said detection signal and that controls the intensity of said first excitation light on the basis of the detection signal.

2. The light source device as set forth in claim 1 , wherein:

said control unit controls the intensity of said first excitation light after the passage of a predetermined time interval from the reception of said detection signal; and

said predetermined time interval is determined by the positional relation on said surface of each of said first excitation light and said detection light on the surface of said phosphor rotating body and the rotation rate of said phosphor rotating body.

3. The light source device as set forth in claim 1 , wherein said emission light comprises second fluorescent light that is excited by said detection light or reflected light that is said detection light reflected by said phosphor rotating body.

4. The light source device as set forth in claim 1 , wherein:

said detection signal comprises a signal that indicates the intensity of said emission light; and

said control unit causes change of the intensity of said first excitation light such that change of the intensity of said first fluorescent light is reduced.

5. The light source device as set forth in claim 1 , wherein the intensity of said detection light is lower than the intensity of said first excitation light.

6. The light source device as set forth in claim 1 , wherein:

said first excitation light source comprises a laser diode or a light-emitting diode; and

said control unit controls the drive current of said first excitation light source.

7. The light source device as set forth in claim 1 , wherein:

said first excitation light source supplies said first excitation light that has an intensity that accords with the drive current; and

said control unit causes change of the intensity of said first excitation light by changing said drive current.

8. The light source device as set forth in claim 7 , wherein said control unit generates a correction signal that accords with change in intensity of said second fluorescent light on the basis of said detection signal and causes change of said drive current on the basis of said correction signal.

9. The light source device as set forth in claim 8 , wherein:

said first excitation light source supplies a first feedback signal that accords with the intensity of said first excitation light to said control unit; and

said control unit comprises:

a correction signal generation unit that generates a first correction signal realized by inversely amplifying said detection signal and then delaying the result by a predetermined time interval;

an amplifier that adjusts the level of said first correction signal that was generated by said correction signal generation unit to a predetermined level and then supplies a second correction signal that is the signal that follows adjustment;

a subtraction unit that supplies a second feedback signal realized by subtracting said second correction signal that was supplied by said amplifier from said first feedback signal;

a power source unit that supplies a first drive signal that accords with the magnitude of said second feedback signal that was supplied by said subtraction unit; and

an addition unit that superposes said first correction signal that was generated by said correction signal generation unit upon said first drive signal that was supplied by said power source unit and supplies the superposed signal as said drive signal.

10. The light source device as set forth in claim 8 , wherein:

said first excitation light source supplies a first feedback signal that accords with the intensity of said first excitation light to the control unit; and

said control unit comprises:

a correction signal generation unit that generates a first correction signal that is realized by amplifying said detection signal and then delaying the result by a predetermined time interval;

an addition unit that supplies a second feedback signal realized by superposing said first correction signal that was generated by said correction signal generation unit upon said first feedback signal; and

a power source unit that generates a first drive signal that accords with the magnitude of said second feedback signal that was supplied by said addition unit and that supplies the first drive signal as said drive signal.

11. The light source device as set forth in claim 1 , wherein:

the spot of said second excitation light on the surface of said phosphor rotating body is formed on the side opposite the spot of said first excitation light with said center of rotation interposed.

12. The light source device as set forth in claim 1 , wherein said phosphor includes two or more phosphor regions that supply fluorescent light of different wavelengths.

13. A projection-type display device comprising:

the light source device as set forth in claim 1 ;

a display element that modulates light that is supplied from said light source device to form an image; and

a projection optical system that projects the image that was formed by said display element.

14. A light source control method comprising:

causing a phosphor rotating body on which a phosphor is formed on a surface to rotate;

causing excitation light to irradiate a first position that is separated by a predetermined distance from the center of rotation on said surface to cause emission of fluorescent light;

irradiating detection light upon a second position that differs from said first position and that is separated by said predetermined distance from said center of rotation on said surface and detecting emission light that is emitted from said phosphor rotating body in response to said detection light; and

controlling the intensity of said excitation light on the basis of the detection result of said emission light.