Claims
- 1. A projection type display system comprising:
- a) optical modulation means for modulating a light in accordance with video data;
- b) a projection lens system having a projection lens for projecting the modulated light on a screen;
- c) automatic adjustment means for focusing images onto the screen;
- d) a range finding unit for finding the distance between said projection lens and said screen with a beam of light, said range finding unit comprising
- (i) a light emitting element for irradiating said screen with said beam of light, and
- (ii) a light reception device for receiving light reflected from said screen to output an electrical signal corresponding to the light receiving position of said reflected light;
- e) a control means, coupled to said automatic adjustment means and to said range finding unit, for sending a control signal to said automatic adjustment means so that said reflected light may irradiate a desired light receiving position in said light receiving device on the basis of said electrical signal; and
- f) a pattern display unit, coupled to said optical modulation means, for displaying on said screen a first fixed pattern during a focal adjustment period, and a second fixed pattern when focal adjustment is completed.
- 2. The system of claim 1, wherein said pattern display unit comprises a plurality of character generators.
- 3. The system of claim 1, wherein said first and second fixed patterns are displayed as a pattern having an upper component and a lower component.
- 4. The system of claim 3, wherein said first fixed pattern comprises said upper and lower components laterally offset from each other.
- 5. The system of claim 4, wherein said second fixed pattern comprises said upper and lower components displayed without lateral offset.
- 6. The system of claim 1 wherein said light reception device has at least two light receiving areas, reflected light in one area causing the automatic adjustment means to operate in one mode, with light in the other light receiving area causing the automatic adjustment means to operate in an opposite mode.
- 7. The system of claim 1 wherein said pattern display unit superimposes the first or second pattern onto said video data.
- 8. The system of claim 1 wherein said beam of light is infrared radiation.
- 9. The system of claim 1 wherein said automatic adjustment means comprises means for changing the distance from said screen to said projection lens.
CROSS REFERENCE TO RELATED APPLICATION
This is a continuation of U.S. patent application Ser. No. 07/971,861, filed Mar. 29, 1993, now U.S. Pat. No. 5,341,176, issued Aug. 23, 1994.
US Referenced Citations (11)
Foreign Referenced Citations (23)
Number |
Date |
Country |
131794 |
Jan 1985 |
EPX |
0192023 |
Aug 1986 |
EPX |
0239024 |
Sep 1987 |
EPX |
454451 |
Oct 1991 |
EPX |
275615 |
Dec 1961 |
JPX |
22189 |
Jun 1974 |
JPX |
6046 |
Mar 1978 |
JPX |
39032 |
Mar 1982 |
JPX |
104918 |
Jun 1982 |
JPX |
97123 |
Jun 1984 |
JPX |
128314 |
Aug 1985 |
JPX |
247631 |
Dec 1985 |
JPX |
67012 |
Apr 1986 |
JPX |
61-154377 |
Jul 1986 |
JPX |
240108 |
Oct 1986 |
JPX |
261710 |
Nov 1986 |
JPX |
204010 |
Aug 1989 |
JPX |
214828 |
Aug 1989 |
JPX |
90135 |
Mar 1990 |
JPX |
3261284 |
Nov 1991 |
JPX |
4-10785 |
Jan 1992 |
JPX |
470076 |
Mar 1992 |
JPX |
4124980 |
Apr 1992 |
JPX |
Continuations (1)
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Number |
Date |
Country |
Parent |
971861 |
Mar 1993 |
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