Projection display apparatus and method for projecting image onto a screen

A projection display apparatus for projecting an image onto a screen, comprising:

• a light source;
• a signal processing unit for processing an input image signal to output a first image signal representing first primary-color information R1, G1, and B1 representing values of red, green, and blue components of an image to be projected;
• a signal conversion unit for converting the first image signal into a second image signal representing a coefficient M which depends on luminance of the image to be projected defined by the first primary-color information R1, G1, and B1, and into a third image signal representing second primary-color information R2=R1/M, G2=G1/M, and B2=B1/M;
• a first light valve for modulating light received from the light source in accordance with the coefficient M;
• a color-separation unit for separating the light modulated by the first light valve into red, green and blue lights;
• three second light valves for further modulating the red, green and blue lights received from the color separation unit in accordance wit the second primary-color information R2, G2, and B2 respectively;
• and
• a projection unit for throwing mixture of the red, green, and blue lights modulated by the three second light valves onto the screen.

A projection display apparatus for projecting an image onto a screen, comprising:

• a light source;
• a signal processing unit for processing an input image signal to produce a first image signal representing first luminance information Y1 representing luminance of an image to be projected;
• a signal conversion unit for converting the first image signal into a second image signal representing a coefficient M=Y11/2+α, α being a parameter variable between −½ and +½, and into a third image signal representing second luminance information Y2=Y1/2+α
• a first light valve for modulating light received from the light source in accordance with the coefficient M represented by the second image signal;
• a second light valve for further modulating the light received from the first light valve in accordance with the second luminance information Y2 represented by the third image signal;
• and
• a projection unit for throwing the light received from the second light valve onto the screen.

A method of driving a projection display apparatus having a light source, a first light valve modulating light received from the light source in accordance with a first drive signal, the light changing in color among red, green and blue, a second light valve further modulating the light received from the first light valve in accordance with a second drive signal, and a projection unit throwing the light received from the second light valve onto a screen, comprising the steps of:

• producing, from an input image signal, first primary-color information R1, G1, and B1 representing values of red, green and blue components of an image to be projected;
• producing a coefficient M which depends on luminance of the image to be projected defined by the first primary-color information R1, G1, and B1;
• producing second primary-color information R2=R1/M, G2=G1/M, and B2=B1/M;
• supplying the first light valve with the coefficient M as the first drive signal;
• and
• supplying the second light valve with the second-primary color information R2, G2, and B2 as the second drive signal.

A method of driving a projection display apparatus having a light source, a first light valve modulating light received from the light source in accordance with a first drive signal, a light-separation unit separating the light modulated by the first light valve into red, green and blue lights, three second light valves further modulating the red, green and blue lights received from the color separation unit in accordance with second drive signals, and a projection unit throwing mixture of the red, green, and blue lights modulated by the three second light valves onto a screen;

• comprising the steps of:
• producing, from an input image signal, first primary-color information R1, G1, and B1 representing values of red, green, and blue components of an image to be projected;
• producing a coefficient M which depends on luminance of the image to be projected defined by the first primary-color information R1, G1, and B1;
• producing second primary-color information R2=R1/M, G2=G1/M, and B2=B1/M;
• supplying the first light valve with the coefficient M as the first drive signal;
• and
• supplying the three second light valves with the second-primary color information R2, G2, and B2 as the second drive signals.

A method of driving a projection display apparatus having a light source, a first light valve modulating light received from the light source in accordance with a first drive signal, a second light valve further modulating the light received from the first light valve in accordance with a second drive signal, and a projection unit for throwing the light received from the second light valve onto a screen, comprising the steps of:

• producing first luminance information Y1 representing luminance of an image to be projected from an input image signal;
• producing a coefficient M=Y11/2+α,α being a parameter variable between −½ and +½;
• producing second luminance information Y2=Y11/2−α,
• supplying the first light valve with the coefficient M as the first drive signal;
• and
• supplying the second light valve with the second luminance information Y2 as the second drive signal.

A device for driving a projection display apparatus having a light source, a first light valve modulating light received from the light source in accordance with a first drive signal, a second light valve further modulating the light received from the first light valve in accordance with a second drive signal, and a projection unit for throwing the light received from the second light valve onto a screen, said device comprising:

• a signal processing unit for producing, from an input image signal, first primary-color information R1, G1, and B1 representing values of red, green and blue components of an image to be projected;
• a signal conversion unit for producing a coefficient M which depends on luminance of the image to be projected defined by the first primary-color information R1, G1, and B1, and producing second primary-color information R2=R1/M, G2=G1/M, and B2=B1/M;
• a first light valve circuit for supplying the first light valve with the coefficient M as the first drive signal;
• and
• a second light valve circuit for supplying the second light valve with the second-primary color information R2, G2, and B2 as the second drive signal.

A device for driving a projection display apparatus having a light source, a first light valve modulating light received from the light source in accordance with a first drive signal, a second light valve further modulating the light received from the first light valve in accordance with a second drive signal, and a projection unit for throwing the light received from the second light valve onto a screen, said device comprising:

• a signal processing unit for calculating first luminance information Y1 representing luminance of an image to be projected from an input image signal;
• a signal conversion unit for producing a coefficient M=Y11/2+α, a being a parameter variable between −½ and +½, and second luminance information Y2=Y11/2+α
• a first light valve circuit for supplying the first light valve with the coefficient M as the first drive signal;
• and
• a second light valve circuit for supplying the second light valve with the second luminance information Y2 as the second drive signal.