Split lens video display system

• US 5,742,421 A
• Filed: 03/01/1996
• Issued: 04/21/1998
• Est. Priority Date: 03/01/1996
• Status: Expired due to Term

• Current Assignee: Microvision, Inc.
• Original Assignee: Reflection Technology, Inc.
• Inventors: Johnson, Bruce, Wells, Benjamin A., Dilworth, Donald
• Primary Examiner(s): Phan, James
• Application Number:
  US08/609,729
• Time in Patent Office: 781 Days
• Field of Search: 359/197, 359/204, 359/209, 359/210, 359/212-215, 359/221, 359/225, 359/900, 250/578.1, 340/815.45, 345/7-8, 345/32, 345/82-83, 348/800-803, 348/739, 348/42, 348/51, 348/115
• US Class Current: 359/214.1
• CPC Class Codes: G02B 26/10 Scanning systems
• CPC Class Codes: H04N 5/74 Projection arrangements for image reproduction, e.g. using eidophor
• CPC Class Codes: Y10S 359/90 Methods

Abstract

A miniature visual display has an optical lens system with at least two separated lens elements positioned to admit a scanning mirror between them. The scanning mirror is driven with an oscillatory motion causing an image of a light source which is reflected in the mirror to appear to sweep across the field of view of an observer looking into the system. The light source is typically a linear array of light-emitting diodes, and the diodes are controlled to emit light flashes in synchronism with the scanning mirror oscillation frequency to generate a virtual raster image. The two lens elements are selected and arranged so that the magnification power of the system is split between the lenses. A viewer looking into the system sees a virtual image apparently positioned at a comfortable viewing distance which is in uniform focus over the entire viewing area.

Claims

1. An optical system for a display apparatus which has a size suitable for hand-held and headgear-mounted use and generates a raster image by reflecting light produced by an array of light emitting elements from an oscillating mirror to a user'"'"'s eye and selectively illuminating the light-emitting elements as the mirror moves to create a substantially planar, two-dimensional enlarged virtual image, the system comprising:

a first positive power lens located between the light emitting element array and the mirror for creating a first intermediate virtual image of the light-emitting elements;

the first lens having a first optical axis;

a second positive power lens located between the mirror and the user'"'"'s eye for magnifying the reflection of the first intermediate virtual image;

the second lens having a second optical axis; and

the light-emitting element array, the first lens, the mirror, and second lens each being positioned relative to one another and relative to the viewer'"'"'s eye so that the first lens and the second lens together generate a distant, magnified, virtual image at a comfortable viewing distance.

2. The optical system as defined in claim 1 further comprising a means for moving the second lens in a longitudinal direction along the second optical axis to vary the position and focus of the virtual image.

3. The optical system as defined in claim 1 wherein the first lens and the second lens are made from a plastic material.

4. The optical system as defined in claim 3 wherein the first lens has a concave surface that faces the plurality of light-emitting elements.

5. The optical system as defined in claim 1 wherein the total magnification in the optical system is split between the first lens and the second lens.

6. The optical system as defined in claim 1 wherein the virtual image is located at infinity and the first lens and the second lens together collimate the light emitted from the light emitting elements.

7. A miniature visual display system for displaying a magnified two-dimensional raster image that is viewable by a viewer'"'"'s eye comprising:

an array of light emitting elements;

a first lens for creating an enlarged virtual image of the light-emitting elements;

a mirror for reflecting the enlarged virtual image to produce a reflection of the enlarged virtual image;

a means for repetitively moving the mirror through a predetermined range of movement;

a second lens for magnifying the reflection of the enlarged virtual image;

a means for selectively illuminating the light-emitting elements as the mirror moves to create a substantially planar, two-dimensional virtual raster image; and

the light-emitting element array, the first lens, the mirror, and second lens each being positioned relative to one another and relative to the viewer'"'"'s eye so that the first lens and the second lens together generate a virtual image at an apparent viewing distance at or less than infinity and provide the virtual image directly to the user'"'"'s eye.

8. The display system as defined in claim 7 wherein the light emitting elements comprise light emitting diodes.

9. The display system as defined in claim 7 wherein the mirror comprises a planar mirror.

10. The display system as defined in claim 7 wherein the first lens and the second lens are positive power lenses.

11. The display system as defined in claim 7 further comprising a protective cover to shield the light emitting elements.

12. The display system as defined in claim 7 further comprising a means for adjusting the focus of the enlarged virtual image.

13. A miniature display system for displaying a substantially planar, magnified image comprised of a plurality of illuminated picture elements viewable by a viewer'"'"'s eye, the display system being of an overall size suitable for hand-held use and comprising:

a plurality of light-emitting elements, each of which are capable of being independently illuminated to generate an illuminated pixel dot, the light-emitting elements being linearly aligned in at least one row;

a first lens for creating an enlarged virtual image of at least one row of the light-emitting elements;

a planar mirror, having a maximum dimension, in which the reflection of the enlarged virtual image is capable of being observed;

a means for resonantly oscillating the mirror about a fixed axis through a predetermined range of movement;

a second lens for magnifying the reflection of the enlarged virtual image;

a means for selectively illuminating the light-emitting elements so that a plurality of images of the light-emitting elements of the one row are generated at physically displaced points and a substantially planar, two-dimensional, virtual raster image is created; and

the light-emitting element array, the first lens, the mirror, and second lens each being positioned relative to one another and relative to the viewer'"'"'s eye so that the first lens and the second lens together generate a virtual image at an apparent viewing distance at or less than infinity and provide the virtual image directly to the user'"'"'s eye.

14. A method for displaying an image in a display system that is directly viewable by a viewer'"'"'s eye, the method comprising the steps:

(a) illuminating a plurality of light emitting elements that are aligned in a predetermined fashion;

(b) projecting light emitted from the plurality of light-emitting elements through a first positive lens to create an enlarged virtual image of the light-emitting elements;

(c) reflecting the virtual image from a planar mirror to produce a reflected virtual image;

(d) repetitively moving the mirror through a predetermined range of movement to create a two-dimensional raster display;

(e) magnifying the reflected virtual image by projecting the reflected virtual image through a second positive lens; and

(f) positioning the light-emitting element array, the first lens, the mirror, and second lens relative to one another and relative to the viewer'"'"'s eye so that the first lens and the second lens together generate a virtual image at an apparent viewing distance at or less than infinity and provide the virtual image directly to the user'"'"'s eye.

15. The method as defined in claim 14 comprising the further step of:

(g) color filtering the reflected virtual image after it passes through the second positive lens.