Liquid-crystal projector with light beam reduction lens array for improved brightness of image outer portions

• US 4,722,593 A
• Filed: 07/01/1986
• Issued: 02/02/1988
• Est. Priority Date: 07/29/1985
• Status: Expired due to Term

• Current Assignee: Casio Computer Company Limited
• Original Assignee: Casio Computer Company Limited
• Inventors: Shimazaki, Tatsuo
• Primary Examiner(s): Miller, Stanley D.
• Assistant Examiner(s): Duong, Tai V.
• Application Number:
  US06/880,803
• Time in Patent Office: 581 Days
• Field of Search: 350/331 R, 350/336, 350/339 F, 350/432, 350/250, 353/122, 353/121, 353/38, 353/69, 353/30, 353/31
• US Class Current: 349/5
• CPC Class Codes: G02F 1/133526 Lenses, e.g. microlenses or Fresnel lenses
• CPC Class Codes: G03B 21/006 using LCD's
• CPC Class Codes: H04N 9/3108 by using a single electronic spatial light modulator
• CPC Class Codes: H04N 9/3152 for shaping the light beam beam shaping per se G02B27/09

Abstract

A liquid-crystal projector reduces outer portions of a light beam corresponding to a projection image from a liquid-crystal display panel illuminated with light from a light source by a light beam width reduction lens array in order to increase the luminance of the outer beam portions. The projection image passing through the light beam width reduction lens array is compensated for attenuation in luminance of the outer beam portions, and is then projected onto a screen surface through a projection lens system.

Claims

1. A liquid-crystal projector comprising:

light source means;

liquid-crystal display panel means which is illuminated with light emitted from said light source means and in which an image displayed thereon is enlarged and projected onto a screen surface;

light beam width reduction lens means which reduces the widths of outer portions of the light beam corresponding to the image displayed on said liquid-crystal display panel means in order to increase an optical density of the outer portions of the light beam; and

projection lens means, arranged along the optical axis of said liquid-crystal display panel means, said light beam width reduction lens means, and said screen, for enlarging the image passing through said light beam width reduction lens means and projecting it onto said screen surface.

2. A projector according to claim 1, wherein said liquid-crystal display panel means comprises a first substrate on which scanning electrodes for holding liquid crystals are aligned, and a second substrate on which signal electrodes are aligned;

widths of upper and lower scanning electrodes, each corresponding in number to substantially 1/n the total number of said scanning electrodes aligned in the row direction, are substantially m times those of central scanning electrodes corresponding in number to substantially (1-2/n) the total number of said scanning electrodes;

each of said signal electrodes consists of three elongated electrodes, i.e., a red display electrode on which a red filter is formed, a green display electrode on which a green filter is formed, and a blue display electrode on which a blue filter is formed; and

the total width of said three elongated electrodes is substantially equal to that of each of said central scanning electrodes.

3. A projector according to claim 2, wherein n of 1/n is 4, and m is 1.5.

4. A projector according to claim 1, wherein said liquid-crystal display panel means comprises a first substrate on which scanning electrodes for holding liquid crystals are aligned, and a second substrate on which signal electrodes are aligned;

widths of upper and lower scanning electrodes, each corresponding in number to substantially 1/n the total number of said scanning electrodes aligned in the row direction, are substantially m times those of central scanning electrodes corresponding in number to substantially (1-2/n) the total number of said scanning electrodes;

each of said signal electrodes consists of three elongated electrodes, i.e., a red display electrode on which a red filter is formed, a green display electrode on which a green filter is formed, and a blue display electrode on which a blue filter is formed;

widths of left and right signal electrodes, each corresponding in number to substantially 1/s the total number of said signal electrodes aligned in the column direction, are substantially p times those of central signal electrodes corresponding in number to substantially (1-2/s) the total number of said signal electrodes; and

the total width of said three elongated electrodes is substantially equal to a width of each of said central scanning electrodes.

5. A projector according to claim 4, wherein s of 1/s is 4, and p is 1.5.

6. A projector according to claim 1, wherein said light beam width reduction lens means comprises a first lens body having upper and lower convex lens portions and a second lens body having upper and lower concave lens portions, which are aligned along said optical axis.