Rear projection display device and projecting method used for the same

• US 6,805,447 B2
• Filed: 10/12/2001
• Issued: 10/19/2004
• Est. Priority Date: 10/13/2000
• Status: Expired due to Fees

• Current Assignee: NEC Display Solutions, Ltd. (NEC Corporation)
• Original Assignee: NEC Viewtechnology, Ltd.
• Inventors: Takeuchi, Tadashi
• Primary Examiner(s): Fuller, Rodney
• Assistant Examiner(s): KOVAL, MELISSA J
• Application Number:
  US09/974,966
• Publication Number:
  US 20020044263A1
• Time in Patent Office: 1,103 Days
• Field of Search: 348/744, 348/760, 348/836, 348/843, 353/74, 353/77, 353/71, 353/79, 353/119, 353/30, 353/31, 353/37, 353/78, 349/6, 359/443, 359/456, 359/460
• US Class Current: 353/71
• CPC Class Codes: G03B 21/10 Projectors with built-in or built-on screen
• CPC Class Codes: G03B 21/28 Reflectors in projection beam in illumination beam G03B21/2066
• CPC Class Codes: G03B 21/62 Translucent screens

Abstract

A flat mirror for folding an optical path in a casing of a rear projection television is arranged in the casing on not the side of a screen but a rear or upper side of the casing. In order to direct an optical path of an image projection to a flat mirror on a rear or upper side of the casing, a plurality of focusing mirrors, with which a light beam can be directed at a large angle with respect to a normal line of the screen and can focus an image through a shorter distance compared with a conventional lens system, are used. Since the light beam projected by the focusing mirrors is directed at high angle and reflected by the rear or upper side flat mirror in the casing, the light beam is focused on the screen provided on a front side of the casing.

Claims

1. A rear projection television comprising:

a casing having a projection screen, said projection screen constituting a front face of said casing;

a projector provided within said casing for emitting a light beam containing an image information; and

an end side final stage reflection mirror provided within said casing in the vicinity of an end portion of said projection screen,

wherein said end side final stage reflection mirror reflects said light beam emitted from said projector toward a whole rear surface of said screen, and

said end side final stage reflection mirror is arranged such that an optical axis of said light beam incident on said end side reflection minor is slanted toward said screen to gradually reduce a distance between said optical axis and said screen,

wherein a normal line of said end side reflection mirror is in parallel to a surface of said screen.

2. A rear projection television comprising:

a casing having a projection screen, said projection screen constituting a front face of said casing;

a projector provided within said casing for emitting a light beam containing an image information; and

an end side final stale reflection mirror provided within said casing in the vicinity of an end portion of said projection screen,

wherein said end side final stage reflection mirror reflects said light beam emitted from said projector toward a whole rear surface of said screen, and

said end side final stage reflection mirror is arranged such that an optical axis of said light beam incident on said end side reflection mirror is slanted toward said screen to gradually reduce a distance between said optical axis and said screen,

wherein an angle between a surface of said end side reflection mirror and said surface of said screen is in a range from 70 degrees to 120 degrees,

wherein said screen has a construction including a flail reflection type Fresnel lens and a lenticular lens laminated on said Fresnel lens.

3. A rear projection television as claimed in claim 2, wherein an optical axis of said Fresnel lens is separated from a center of said screen.

4. A rear projection television as claimed in claim 3, wherein said optical axis of said Fresnel lens is outside of said screen.

5. A rear projection television comprising:

a casing having a projection screen, said projection screen constituting a front face of said casing;

a projector provided within said casing for emitting a light beam containing an image information; and

an end side final stage reflection mirror provided within said casing in the vicinity of an end portion of said projection screen,

wherein said end side final stage reflection mirror reflects said light beam emitted from said projector toward a whole rear surface of said screen, and

said end side final stage reflection mirror is arranged such that an optical axis of said light beam incident on said end side reflection minor is slanted toward said screen to gradually reduce a distance between said optical axis and said screen,

wherein an angle between a surface of said end side reflection mirror and said surface of said screen is in a range from 70 degrees to 120 degrees,

further comprising a group of micro reflection mirrors for representing an image by reflecting an illumination light beam emitted from said light source to arbitrary directions.