Compact projector and method of using same

• US 5,510,861 A
• Filed: 09/15/1994
• Issued: 04/23/1996
• Est. Priority Date: 05/11/1993
• Status: Expired due to Fees

• Current Assignee: Proxima Corporation (Ask ASA)
• Original Assignee: Proxima Corporation (Ask ASA)
• Inventors: Kappel, David W., Minich, Arthur P.
• Primary Examiner(s): Dowling, William C.
• Application Number:
  US08/306,366
• Time in Patent Office: 586 Days
• Field of Search: 353/119, 353/37, 353/38, 353/63, 353/64, 353/98, 353/99, 353/DIG. 3, 359/40, 359/48, 359/49, 362/297, 362/298, 362/343
• US Class Current: 353/119
• CPC Class Codes: G03B 21/132 Overhead projectors, i.e. capable of projecting hand-writing or drawing during action epidiascopic projectors G03B21/08
• CPC Class Codes: G03B 21/28 Reflectors in projection beam in illumination beam G03B21/2066
• CPC Class Codes: G09G 2340/04 Changes in size, position or resolution of an image
• CPC Class Codes: G09G 2340/0414 Vertical resolution change
• CPC Class Codes: G09G 2340/0421 Horizontal resolution change
• CPC Class Codes: G09G 2340/0471 Vertical positioning
• CPC Class Codes: G09G 2340/0478 Horizontal positioning
• CPC Class Codes: G09G 2340/0485 Centering horizontally or vertically
• CPC Class Codes: H04N 5/7441 the modulator being an array of liquid crystal cells
• CPC Class Codes: H04N 9/3141 Constructional details thereof details not peculiar to the presence of an electronic spatial light modulator G03B21/14

Abstract

A compact projection illumination system includes a display controller, a condenser lens assembly including a light source, and a pair of finely faceted mirrors angularly disposed relative to one another to spread projection light emitted from the high intensity projection light source in two directions, and direct the reflected light to an image forming display device where an image is formed for projection purposes. The light is spread to illuminate precisely the light impinging surface of the image forming display device. To reduce image distortion caused by the faceted mirrors forming beam segments, the condenser lens assembly and the light source are arranged and constructed to permit the reflected beam segments to converge sufficiently to fill in dark or shadow areas between the beam segments prior to the segments impinging on the image forming display device, so that the resulting image is formed uniformly and substantially distortion free in a narrowly defined, compact space.

Claims

1. A method of projecting an image onto a remote viewing surface, comprising:

positioning a projection lens system in an optical path extending from a source of high intensity projection light to the remote viewing surface;

positioning an image forming device generally horizontally in a low profile housing and substantially in said optical path to enable light from said source of high intensity light to be modulated;

positioning an optical system in said low profile housing substantially below said image forming device for directing light from said source of light through said device;

positioning a lamp assembly at a rear portion of said housing to provide said source of high intensity projection light; and

coupling a display control system electrically to said device for modulating the high intensity projection light as it passes through said device to form the image for projection purposes;

generating a generally collimated light for image projection purposes;

wherein said step of positioning said optical system includes positioning a first faceted mirror at a predetermined angle relative to the collimated light to produce beam segments reflecting therefrom for spreading them by a predetermined amount in a desired dimension; and

positioning a second faceted mirror at a predetermined angle relative to the first mirror to reflect said beam segments therefrom and to in turn produce beam segments reflecting therefrom for spreading them by a predetermined amount in another desired dimension.

2. A method according to claim 1, wherein the steps of positioning the mirrors is at a predetermined distance of a sufficient length to permit the beam segments reflecting from the first mirror to diverge and intersect to fill in dark areas therebetween before impinging on the second mirror.

3. A method of projection according to claim 1, wherein the step of positioning said image forming device includes:

positioning said image forming device at a predetermined angle relative to the second mirror and at a predetermined distance therefrom of a sufficient length to permit the beam segments reflecting from the second mirror to diverge and intersect to fill in dark areas before impinging on the image forming device;

whereby the light is uniformly dispersed over the light impinging surface of the image forming device to reduce distortion and efficiently and effectively form an image to be projected.

4. A method of projecting an image onto a remote viewing surface, comprising:

positioning a projection lens system in an optical path extending from a source of high intensity projection light to the remote viewing surface;

positioning an image forming device generally horizontally in a low profile housing and substantially in said optical path to enable light from said source of high intensity light to be modulated;

positioning an optical system in said low profile housing substantially below said image forming device for directing light from said source of light through said device;

positioning a lamp assembly at a rear portion of said housing to provide said source of high intensity projection light; and

coupling a display control system electrically to said device for modulating the high intensity projection light as it passes through said device to form the image for projection purposes;

generating a generally collimated light for image projection purposes;

wherein the generating of the generally collimated light includes positioning an optical device relative to said source of light for causing the generally collimated light to be directed therefrom where the light spreads at an angle of spreading equal to the arc tangent of the size of the light source divided by the effective focal length of the device to cause the generally collimated light to overlap within a predetermined distance.

5. A projection illumination arrangement for projecting an image onto a remote viewing surface, comprising:

a projection lens arrangement;

means for positioning said projection lens arrangement in an optical path extending from a source of high intensity projection light to the remote viewing surface;

an image forming device;

means for positioning said image forming device generally horizontally in a low profile housing and substantially in said optical path to enable light from said source of high intensity light to be modulated;

an optical system;

means for positioning said optical system in said low profile housing substantially below said device for directing light from said source of light through said device;

a lamp assembly;

means for positioning said lamp assembly at a rear portion of said housing to provide said source of high intensity projection light;

a display control system; and

means for coupling said display control system electrically to said image forming device to facilitate modulating the high intensity projection light as it passes through said device to form the image;

wherein said means for positioning a lamp assembly includes means for collimating the light from said source of light for image projection purposes; and

wherein said means for positioning an optical system includes;

a first faceted mirror;

means for positioning said first faceted mirror at a predetermined angle relative to the collimated light to produce beam segments reflecting therefrom for spreading them by a predetermined amount in a desired dimension;

a second faceted mirror;

means for positioning said second faceted mirror at a predetermined angle relative to the first mirror to reflect said beam segments therefrom and to in turn produce beam segments reflecting therefrom for spreading them by a predetermined amount in another desired dimension;

said mirrors being positioned at a predetermined distance of a sufficient length to permit the beam segments reflecting from the first mirror to diverge and intersect to fill in dark areas therebetween before impinging on the second mirror.

6. A projection illumination arrangement according to claim 5, wherein said means for positioning said image forming device includes:

means for positioning said image forming device at a predetermined angle relative to the second mirror and at a predetermined distance therefrom of a sufficient length to permit the beam segments reflecting from the second mirror to diverge and intersect to fill in dark areas before impinging on the image forming device;

whereby the light is uniformly dispersed over the light impinging surface of the image forming device to reduce distortion and efficiently and effectively form an image to be projected.

7. A projection illumination arrangement according to claim 5, wherein the image forming device is an image modulating device.

8. A projection illumination arrangement according to claim 5, wherein said image forming device is a transparency supporting stage.

9. A projection illumination arrangement according to claim 5, wherein said lamp assembly includes a parabolic reflector to collect and direct substantially all of the light emitted by said source of light toward said a first faceted mirror.

10. A projection illumination arrangement for projecting an image onto a remote viewing surface, comprising:

a low profile housing;

light collimating means disposed at a rear portion of said housing for producing high intensity collimated light;

first dimension faceted mirror means mounted within said housing at a predetermined angle relative to said light collimating means for spreading reflectively the collimated light by a predetermined amount in a desired dimension to form a plurality of high intensity light beams;

second dimension faceted mirror means mounted within said housing at a predetermined angle relative to the first mirror means for spreading reflectively said plurality of high intensity light beams by another predetermined amount in another desired dimension to cause a substantial portion of said plurality of high intensity light beams to be directed in a desired direction along an optical path;

image forming means mounted substantially horizontally within said housing in said optical path to enable the light directed in said desired direction to be modulated; and

means for coupling a display control system electrically to said image forming means for enabling it to modulate said plurality of high intensity light beams to form the image.