Projection type image display apparatus with circuit for correcting luminance nonuniformity

• US 5,260,797 A
• Filed: 06/07/1990
• Issued: 11/09/1993
• Est. Priority Date: 06/08/1989
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Kotaka, Mitsuru, Muraji, Tsutomu
• Primary Examiner(s): Groody, James J.
• Assistant Examiner(s): Burgess, Glenton B.
• Application Number:
  US07/534,275
• Time in Patent Office: 1,251 Days
• Field of Search: 358/231, 358/60, 358/61, 358/63, 358/232, 358/233, 358/235, 358/236, 358/51, 358/64, 362/13
• US Class Current: 348/745
• CPC Class Codes: H04N 5/7441 the modulator being an array of liquid crystal cells
• CPC Class Codes: H04N 9/3179 Video signal processing therefor

Abstract

A projection type image display apparatus using a light modulation image display device as a light valve varies the voltage of a video signal so as to correct the nonuniformity of luminance of the optical device so that an image uniform in brightness and color even in peripheral parts can be displayed on a projection screen. A driving circuit contained with the apparatus generates three driving signals for driving three image display devices in accordance with red, green and blue color component signals of an input video signal. The driving circuit includes a correction circuit for correcting the red and blue color component signals independently of one another so that their luminance is commensurate with that of the green color component signal.

Claims

1. A projection type image display apparatus comprising:

a lamp;

a circuit for lighting said lamp;

three image display devices each for modulating a light in accordance with a driving signal;

a first optical device for respectively guiding light of red, green and blue components from said lamp to said three image display devices;

a second optical device comprising three projection lenses for projecting light modulated by said three image display devices on a screen to form a color image in which a luminance distribution on said screen by each of said three projection lenses is nonuniform; and

a driving circuit for generating three driving signals in accordance with red, green and blue color component signals of an input video signal, and for respectively feeding said three driving signals into said three image display devices, said driving circuit including a signal correction circuit for correcting said red and blue color component signals independently of one another so that a luminance distribution on said screen by each of said three projection lenses becomes a predetermined nonuniform luminance distribution.

2. A projection type image display apparatus comprising:

a lamp;

a circuit for lighting said lamp;

three image display devices each for modulating a light in accordance with a driving signal;

a first optical device for respectively guiding light of red, green and blue components from said lamp to said three image display devices;

a second optical device comprising three projection lenses for projecting lights modulated by said three image display devices on a screen to form a color image in which a luminance distribution on said screen by each of said three projection lenses is nonuniform; and

a driving circuit for generating three driving signals in accordance with red, green and blue color component signals of an input video signal, and for respectively feeding said three driving signals into said three image display devices, said driving circuit including a signal correction circuit for correcting said red and blue color component signals independently of one another so that nonuniform luminance distributions on said screen by said three projection lenses are substantially identical.

3. A projection type image display apparatus comprising:

a lamp;

a circuit for lighting said lamp;

three image display devices each for modulating a light in accordance with a driving signal;

a first optical device for respectively guiding light of red, green and blue components from said lamp to said three image display devices;

a second optical device comprising three projection lenses for projecting lights modulated by said three image display devices on a screen to form a color image in which a luminance distribution on said screen by each of said three projection lenses is nonuniform; and

a driving circuit for generating three driving signals in accordance with red, green and blue color component signals of an input video signal, and for respectively feeding said three driving signals into said three image display devices, said driving circuit including a signal correction circuit for correcting two specific color component signals out of said red, green and red color component signals independently of the other so that a nonuniform luminance distribution on said screen by each of two specific projection lenses out of said three projection lenses are equal to a nonuniform luminance distribution on said screen by the remaining projection lens.

4. An apparatus according to claim 3, wherein said signal correction circuit comprises two look-up table memories having stored therein predetermined correction data for correcting said two specific color component signals.