Virtual image display system with reduced ambient reflection and low radiation

• US 5,585,946 A
• Filed: 08/19/1994
• Issued: 12/17/1996
• Est. Priority Date: 08/19/1994
• Status: Expired due to Fees

• Current Assignee: Delta Electronics Incorporated
• Original Assignee: Vivitek Corporation (Delta Electronics Incorporated)
• Inventors: Chern, Mao-Jin
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US08/293,641
• Time in Patent Office: 851 Days
• Field of Search: 359/630, 359/631, 359/633, 359/634, 359/486, 359/40, 359/65, 359/73, 359/53
• US Class Current: 349/5
• CPC Class Codes: H04N 9/30 using solid-state colour display devices

Abstract

A virtual image display system with reduced ambient reflection. The virtual image display system includes a black and white image source for projecting a black and white image. The black and white image is then projected to a magnifying virtual image optical arrangement including a concave reflecting mirror. The magnifying virtual image optical arrangement and a color shutter including a linear polarizer receive the black and white image to generate a magnified color virtual image. The virtual color image display system further includes a λ/4-plate for cooperating with the color shutter including the linear polarizer to reduce an ambient reflection from the concave reflecting mirror.

Claims

1. A virtual image display system with reduced ambient reflection comprising:

a black and white image source for projecting a black and white image therefrom;

a magnifying virtual image optical arrangement including a concave reflecting mirror for receiving and reflecting said black and white image projected from said image source assembly;

a λ

/4-plate for receiving said black and white image reflected from said concave reflecting mirror;

a color shutter including a linear polarizer facing said λ

/4-plate for receiving said black and white image for generating a magnified color virtual image displayed behind said concave reflecting mirror; and

said polarizer and said λ

/4-plate converting an external ambient beam into a circularly polarized beam of a first polarization, said external ambient beam when reflected from said concave reflecting mirror is converted to a reflecting ambient beam which is a circularly polarized beam of a second polarization whereby said reflecting ambient beam is blocked by said λ

/4-plate and said color shutter thus reducing an ambient reflection.

2. The virtual image display system of claim 1 further comprises:

a viewing window, disposed outside of said color shutter opposite said λ

/4 plate and said reflecting mirror, for an operator to view said magnified virtual color image behind said concave reflecting mirror.

3. The virtual image display system of claim 2 wherein:

said color shutter is a liquid crystal color shutter which further including liquid crystal cells and color polarizers disposed adjacent to each other for transmitting an optical beam therethrough wherein each of said liquid crystal cells is controlled to have an on or off state thus generating, in combination with said color polarizers, a color display beam from said optical beam transmitting therethrough.

4. The virtual image display system of claim 2 wherein:

said color shutter is a ferroelectric color shutter which further including ferroelectric cells and color polarizers disposed adjacent to each other for transmitting an optical beam therethrough wherein each of said ferroelectric cells is controlled to have an on or off state thus generating, in combination with said color polarizers, a color display beam from said optical beam transmitting therethrough.

5. The virtual image display system of claim 2 wherein:

said magnifying virtual image optical arrangement further includes a beam splitter for reflecting said black and white image from said image source to said concave reflecting mirror with a reflection axis which is an axis symmetrical to an incident and reflecting optical paths of said monochromatic image wherein said reflection axis deviates for an angle of ten degrees or less from an axis of said concave reflecting mirror.

6. A virtual image display system with reduced ambient reflection comprising:

a black and white image source for projecting a black and white image;

a color shutter for receiving said monochromatic image and converting said monochromatic image into a color image;

a first λ

/4 plate cooperating with said color shutter for circularly polarizing said color image;

a magnifying virtual image optical arrangement including a concave reflecting mirror for receiving said color image for generating a magnified color virtual image; and

a circular polarizer including a second λ

/4-plate for cooperating with said first λ

/4 plate and said color shutter to allow said color image to pass through while reducing an ambient reflection from said concave reflecting mirror.

7. The virtual image display system of claim 6 further comprises:

a viewing window for an operator to view said magnified virtual color image; and

said circular polarizer including said second λ

/4 plate are disposed on the back side of said view window.

8. The virtual image display system of claim 7 wherein:

said color shutter is a liquid crystal color shutter which further including liquid crystal cells and color polarizers disposed adjacent to each other for transmitting an optical beam therethrough wherein each of said liquid crystal cells is controlled to have an on or off state thus generating, in combination with said color polarizers, a color display beam from said optical beam transmitting therethrough.

9. The virtual image display system of claim 7 wherein:

said color shutter is a ferroelectric color shutter which further including ferroelectric cells and color polarizers disposed adjacent to each other for transmitting an optical beam therethrough wherein each of said ferroelectric cells is controlled to have an on or off state thus generating, in combination with said color polarizers, a color display beam from said optical beam transmitting therethrough.

10. The virtual image display system of claim 7 wherein:

said magnifying virtual image optical arrangement further includes a beam splitter for reflecting said color image from said color shutter and said first λ

/4 plate to said concave reflecting mirror with a reflection axis which is an axis symmetrical to an incident and reflecting optical paths of said color image wherein said reflection axis deviates for an angle of ten degrees or less from an axis of said concave reflecting mirror.