Optical system of a reflection LCD projector

• US 5,706,063 A
• Filed: 10/13/1995
• Issued: 01/06/1998
• Est. Priority Date: 11/25/1994
• Status: Expired due to Term

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Hong, Chang-wan
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): Ngo, Julie
• Application Number:
  US08/543,008
• Time in Patent Office: 816 Days
• Field of Search: 359/40, 359/41, 359/73, 349/5, 349/9, 349/117
• US Class Current: 349/9
• CPC Class Codes: H04N 9/3105 for displaying all colours simultaneously, e.g. by using two or more electronic spatial light modulators simultaneous projection in colour photography G03B33/10; beam splitting or combining systems per se G02B27/10

Abstract

An optical system of an LCD projector includes a light beam splitter for passing only a specific wavelength of light emitted from a light source and reflecting another wavelength. Two reflection type LCDs for a black-and-white signal and a color signal, respectively, are placed in correspondence with the light of the respective wavelengths, split by the light beam splitter. The LCDs either transmit or scatter the light of the respective wavelengths according to whether the particular LCD is turned on or off, so that the resolution can be improved by projecting the LCD for the black-and-white signal together with the LCD for the color signal.

Claims

1. An optical system of an LCD projector, comprising:

a light source for emitting light;

a light beam splitter for passing only a specific wavelength of the light emitted from said light source and reflecting another wavelength of the light emitted from said light source;

first and second LCD panels, which are placed in correspondence with the light of the respective wavelengths split by said light beam splitter, for reflecting the light of the respective wavelengths;

a projecting lens which receives and projects the light reflected by said first and second LCD panels; and

a screen, located on a pathway of the light projected by said projecting lens, for receiving the light projected by said projecting lens,

wherein said first LCD panel, said light beam splitter, said projecting lens and said screen form a first optical axis by being located on a common optical axis, and wherein said light source, said light beam splitter, and said second LCD panel form a second optical axis at a predetermined angle with respect to said first optical axis, by being located on a common optical axis, and

further wherein one of said first and second LCD panels is for a color signal, while the other of said first and second LCD panels is for a black-and-white signal.

2. The optical system of an LCD projector as claimed in claim 1, wherein said first and second LCD panels comprise first and second focusing lenses positioned in front thereof, respectively, for focusing the light of the respective wavelengths split by said light beam splitter.

3. The optical system of an LCD projector as claimed in claim 1, wherein said first and second LCD panels comprise first and second focusing lenses positioned in front thereof, respectively, for focusing the light of the respective wavelengths split by said light beam splitter.

4. The optical system of an LCD projector as claimed in claim 1, further comprising first and second λ

/4 wavelength boards which are located between said first LCD panel and first focusing lens, and between said second LCD panel and second focusing lens, respectively.

5. The optical system of an LCD projector as claimed in claim 1, wherein said light beam splitter is a polarizing beam splitter disposed at a predetermined angle with respect to the axis of the light emitted from said light source.

6. The optical system of an LCD projector as claimed in claim 4, wherein said light beam splitter is slantingly positioned at 45°

with respect to the second optical axis along which the light emitted from said light source travels.

7. The optical system of an LCD projector as claimed in claim 1, wherein said first and second optical axes form an approximately 90°

angle by crossing each other centering around said light beam splitter.