1. A method to provide video conferencing, comprising:
a. generating at a client a high quality video stream and a low quality video stream;
b. receiving at a server a plurality of high quality and low quality video streams from a plurality of clients; and
c. sending from the server to each client one high quality video stream and a plurality of low quality video streams.
2. The method of claim 1, comprising sending the high quality video stream at a high frequency to enhance video quality.
3. The method of claim 1, comprising sending the low quality video stream at a low frequency to reduce bandwidth requirement.
4. The method of claim 1, comprising selecting at the client one participant’s high quality video stream.
5. The method of claim 4, comprising displaying at the client the low quality video for the remaining participant(s).
6. The method of claim 1, comprising rendering at the client one participant’s high quality video stream.
7. The method of claim 1, comprising displaying the video streams on multiple screen pages, each page contains video images of a sub-set of participants.
8. The method of claim 7, comprising streaming only video streams for the sub-set of participants.
9. The method of claim 7, comprising displaying a link to access videos of participants on another page.
10. The method of claim 1, comprising searching for a selected participant and displaying a page containing the video stream of the selected participant.
11. The method of claim 1, comprising detecting audio silence at the client and not transmitting the client’s audio stream to the server.
12. The method of claim 1, comprising detecting a video still at the client and not transmitting the client’s video stream to the server.
13. The method of claim 1, comprising streaming a document to the server for document sharing.
14. The method of claim 1, comprising periodically labelling each video stream or document sharing stream with a session identifier (ID) to synchronize the conference video streams.
15. The method of claim 14, wherein each client periodically reports the session ID being streamed to the client, and wherein the server compares a received session ID with a session ID uploaded by the client.
16. The method of claim 1, wherein the server sends a correct session ID to a client whose session ID exceeds a pre-determined synchronization tolerance.
17. The method of claim 1, comprising
a. allowing predetermined clients to send voice streams to the server;
b. mixing the voice streams at the server; and
c. distributing the voice streams to the clients.
18. A video conferencing system, comprising:
a. a plurality of clients, each generating a high quality video stream and a low quality video stream;
b. a server to receive a plurality of high quality and low quality video streams from the plurality of clients and to send to each client one high quality video stream and a plurality of low quality video streams.
19. The system of claim 18, wherein the server sends the high quality video stream at a high frequency to enhance video quality.
20. The system of claim 18, wherein the server sends the low quality video stream at a low frequency to reduce bandwidth requirement.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A projector for irradiating light onto a display device comprising:
a discharge lamp for emitting light;
a reflector provided with a concave reflecting surface that reflects the light emitted from said discharge lamp and outputs the emitted light in a direction of an optical axis;
a display device for modulating the light from said discharge lamp to a projected image light;
a projection lens for projecting the light from said display device; and
a fan for cooling said discharge lamp, wherein said reflector is formed of a heat resistant organic material mixed with high heat conductive substances having higher heat conductivity than that of said heat resistant organic material.
2. The projector according to claim 1, wherein the reflecting surface of said reflector has a paraboloidal or ellipsoidal shape.
3. The projector according to claim 1, wherein the reflecting surface of said reflector has a non-spherical shape.
4. The projector according to claim 1, wherein said discharge lamp is a short arc type discharge lamp which is lit with rated power of 250 W or less, constructed of a light emitting tube which seals at least xenon or mercury inside, includes a pair of electrodes at both ends with the distance between said electrodes being 1.8 mm or less.
5. The projector according to claim 1, wherein a front plate glass is provided on a light emitting side of said reflector.
6. The projector according to claim 1, wherein an average thickness of said reflector in the periphery of said discharge lamp is made greater than an average thickness of the light emitting section of said reflector.
7. The projector according to claim 4, wherein a material of said light emitting tube is quartz glass.
8. The projector according to claim 1, wherein a plurality of protrusions are provided on an external surface of said reflector.
9. The projector according to claim 8, wherein said cooling fan is arranged in a rear surface of said reflector, and said protrusions are a heat radiating fin and a direction in which said fin is attached is quasi-parallel to a direction of the optical axis of said reflector.
10. The projector light source according to claim 8, wherein said cooling fan is arranged in a side surface of said reflector, and said protrusions are a heat radiating fin and a direction in which said fin is attached is orthogonal to the direction of the optical axis of said reflector.