US 4,789,221 A · Light valve projector apparatus having increased light efficiency

Abstract

A multiple light valve (MLV) projector apparatus for producing a color display includes two separate light valves of the Schlieren dark field type. One of the light valves produces a first primary color, for example green, and the other light valve produces two other primary colors, for example red and blue. In such an apparatus the output brightness is usually limited by the red light output. An improved input (and complementary output) mask is described which optimizes the transmission of the first, second and third diffraction orders through the slots in the portion of the input mask which transmits red light. Such an optimization provides a substantial increase in red light output compared to a conventional input mask. Red transmitting slots extending in a first direction are asymmetrically disposed with respect to corresponding lenticules that extend in the first direction, while slots extending in a second direction may be symmetrically disposed with respect to corresponding lenticules that extend in the second direction. The first and second direction may be orthogonal to each other.

Claims16

Dependent claims

In a light valve projector apparatus including a two color light valve of the Schlieren dark field type having an input mask and a complementary output mask wherein an optical pupil for the two color light valve comprises:

a plurality of lenticules arranged in a first and a second direction to form an array of lenslets;
said input mask having a plurality of first slots in one region extending in said first direction and a plurality of second slots in a second region extending in said second direction said slots in each of said regions being separated by opaque bars;
and
light filtering means for passing a first color through said first slots in said one region and a second color through said second slots in said second region, wherein the improvement comprises
said first slots in said first region of said input mask being asymmetrically disposed with respect to said lenticles arranged in said first direction, whereby the light output of said first color is increased substantially.

2 more elements

In a light valve projection apparatus wherein an image to be displayed in color is formed by the addition of light from two separate light valves of the Schlieren dark field type a first light valve producing red and blue light and a second light valve producing green light, said first light valve having an input mask and a complementary output mask wherein an optical pupil for said first light valve comprises:

a plurality of lenticules arranged in rows and columns to form an array of lenslets;
said input mask having a plurality of first slots in a horizontally extending central portion, said first slots extending in the direction of the rows of lenticules and a plurality of second slots in the portions above and below the central portion, said second slots extending in the direction of the columns of lenticules, said slots in the central portion and in the portions above and below the central portion being separated by opaque bars;
and
light filtering means for passing red light through the slots in the central portion and blue light through the slots in the portions above and below the central wherein the improvement comprises:
said first slots in the central portion being asymmetrically disposed with respect to the lenticules arranged in rows, each of said first slots in the central portion having a geometric width greater than that of said second slots in the portions above and below the central portion whereby the output of red light is increased substantially from the first light valve.

2 more elements

Dependencies are inferred from the claim text.

Light valve projector apparatus having increased light efficiency

Life of this patent

Light valve projector apparatus having increased light efficiency

Life of this patent

Abstract

Claims16