Projector with foreign matter detecting means

1. A projector comprising:

an image generating device for generating an image;

a housing having said image generating device disposed therein and having an opening defined therein for emitting therethrough projection light representing the image from said image generating device;

a projection mirror mounted on said housing, the projection mirror being positioned to reflect said projection light onto a projection surface;

an optical element disposed in said opening so as to transmit said projection light to said projection mirror; and

a foreign matter detector arranged so as to detect a presence of foreign matter located in a light path of the projection light between said optical element and said projection mirror.

2. The projector of claim 1 , wherein, said foreign matter detector comprises:

a light emitter positioned so as to emit detection light across said light path of the projection light;

a plurality of detection mirrors positioned so as to reflect said detection light across said light path of the projection light;

a light-detecting element positioned so as to receive said detection light which has been reflected by said detection mirrors; and

an electric projector control circuit connected to receive an output signal generated by the light-detecting element, and

wherein said detection mirrors are mounted on opposing side walls of the opening and across said light path of the projection light.

3. A projector having an image generating device, comprising:

a housing having an opening; and

a foreign matter detector including:

a light-emitter to emit detection light;

at least one mirror to reflect said detection light;

a light detector to detect said detection light; and

a controller to control the projector based on a signal from said light detector,

wherein projection light representing an image on the image generating device goes through said opening, and

wherein at least part of said detection light travels transversely across the light path of said projection light.

4. The projector according to claim 3 ,

wherein a plurality of mirrors reflect said detection light, and

wherein said plurality of mirrors are disposed in a mutually confronting position across said projection light that goes through said opening.

5. The projector according to claim 4 ,

wherein at least one of said plurality of mirrors reflects said detection light twice or more.

6. The projector according to claim 3 ,

wherein exactly two mirrors reflect said detection light, and

wherein said detection light is reflected in multiple paths between said two mirrors.

7. The projector according to claim 3 ,

wherein said at least one mirror is a projection mirror mounted outside of said housing, and

wherein said detection light is reflected by said projection mirror after going through said opening.

8. The projector according to claim 7 ,

wherein said projection mirror is angularly movably mounted to selectively open or close said opening, and

wherein said projection mirror serves as part of a projection optical system when opening said opening and serves as a lid when closing said opening.

9. The projector according to claim 3 ,

wherein a peak wavelength of said detection light is in the infrared region.

10. The projector according to claim 3 ,

wherein said controller deenergizes a light source when said signal from said light detector indicates no-detection of said detection light for a predetermined period.

11. The projector according to claim 10 ,

wherein said controller energizes said light source when said signal from said light detector indicates detection of said detection light.

12. The projector according to claim 10 ,

wherein said predetermined period is arbitrary.

13. The projector according to claim 3 ,

wherein said controller cuts off said image when said signal from said light detector indicates no-detection of said detection light for a predetermined period.

14. The projector according to claim 13 ,

wherein said controller displays an OSD (On-Screen Display) when said controller cuts off said image.

15. The projector according to claim 14 ,

wherein at least part of said OSD is gray.

16. The projector according to claim 13 ,

wherein said predetermined period is arbitrary.

17. The projector according to claim 13 ,

wherein a peak wavelength of said detection light is different from the wavelength region of said projection light.

18. The projector according to claim 3 ,

wherein a plurality of detection mirrors reflect said detection light, and

wherein said detection mirrors are mounted on opposing side walls of the opening.

19. The projector according to claim 3 ,

wherein exactly two detection mirrors reflect said detection light,

wherein said one of said two detection mirrors is mounted on each of opposing side walls of the opening, and

wherein said detection light is reflected in multiple paths between said two detection mirrors.