Image display device

• US 6,626,540 B2
• Filed: 03/19/2001
• Issued: 09/30/2003
• Est. Priority Date: 03/17/2000
• Status: Expired due to Term

• Current Assignee: Maxell, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Ouchi, Satoshi, Imahase, Taro, Miyoshi, Tomohiro, Abe, Fukuyasu
• Primary Examiner(s): DOWLING, WILLIAM C
• Application Number:
  US09/810,571
• Publication Number:
  US 20020140905A1
• Time in Patent Office: 925 Days
• Field of Search: 353/20, 353/31, 353/33, 353/34, 353/37, 353/81, 349/5.89
• US Class Current: 353/31
• CPC Class Codes: G02B 27/1026 for use with reflective spatial light modulators
• CPC Class Codes: G02B 27/1073 characterized by manufacturing or alignment methods
• CPC Class Codes: G02B 27/14 operating by reflection only
• CPC Class Codes: G02B 27/145 having sequential partially reflecting surfaces
• CPC Class Codes: G02B 27/283 used for beam splitting or combining
• CPC Class Codes: G03B 21/006 using LCD's
• CPC Class Codes: G03B 21/10 Projectors with built-in or built-on screen
• CPC Class Codes: G03B 21/14 Details
• CPC Class Codes: G03B 21/2066 Reflectors in illumination beam in projection beam G03B21/28
• CPC Class Codes: G03B 21/2073 Polarisers in the lamp house peculiar to electronic spatial light modulators H04N9/3197
• CPC Class Codes: G03B 33/12 using beam-splitting or beam-combining systems, e.g. dichroic mirrors
• CPC Class Codes: H04N 5/7441 the modulator being an array of liquid crystal cells
• CPC Class Codes: H04N 9/3105 for displaying all colours simultaneously, e.g. by using two or more electronic spatial light modulators simultaneous projection in colour photography G03B33/10; beam splitting or combining systems per se G02B27/10
• CPC Class Codes: H04N 9/3167 for polarizing the light beam polarizing optical systems per se G02B27/28

Abstract

A compact, lightweight, low cost image display device with high image quality and improved brightness are attained by a combination of a color separating means and color separating/combining means and color combinations means and two reflecting means and polarizing plate to change the polarization direction of the light and a polarized beam splitter on the optical axis of reflective liquid crystal display element.

Claims

1. An image display device having a plurality of reflective image display elements for forming an optical image according to a video signal from light output from a light source unit, and an optical system to beam the light onto the reflective image display elements and to combine and output the light reflected from the reflective image display elements, comprising:

a color separating unit for separating the light from the light source unit into a first and a second light;

a color separating/combining unit installed on an optical axis of the first light separated by the color separating unit;

a first reflecting unit;

a color combining unit for combining the optical image from the plurality of the reflective image display elements;

a second reflecting unit;

wherein the first light separated by the color separating unit is reflected by the first reflecting unit and input to the color separating/combining unit; and

wherein the second light separated by the color separating unit is permeated through the color combining unit and input to the second reflecting unit for reflection, and the reflected second light is input to one of the reflective image display elements, and an optical image obtained from the one of the reflective image display elements is again reflected by the second reflecting unit and inputted to the color combining unit.

2. An image display device comprising:

a color separating unit to separate light into a first light and a second light and a third light;

a color separating/combining unit to separate and combine the first light and the second light;

first and second liquid crystal display elements installed at approximate right angles in a vicinity of the color separating/combining unit;

a third liquid crystal display element to input the third light; and

a color combining unit to respectively combine the first, the second and the third light separated by the color separating unit;

wherein the first and second light separated by the color separating unit are respectively input to the first and second liquid crystal display elements, and the first light and the second light output from the first liquid crystal display element and the second liquid crystal display element, respectively, are combined in the color separating/combining unit, and the first light and second light combined in the color separating/combining unit are input to the color combining unit, and the third light separated by the color separating unit is input to the third liquid crystal display element through the color combining unit, and the light output from the third liquid crystal display element is input to the color combining unit, for combining with the first light and the second light.

3. An image display device according to claim 2, wherein a first reflecting unit is installed along the optical path from the color separating unit to the color separating/combining unit on the optical axis of the first and second light.

4. An image display device according to claim 3, wherein a second reflecting unit is installed along the optical path from the color separating unit to the third crystal display element on the optical axis of the third light.

5. An image display device according to claim 2, wherein a first designated wavelength converter element for converting the polarization direction of a first light is installed on the incident side of the color combining/separating unit, a second designated wavelength converter element for converting the polarization direction of a second light is installed at an output side of the color combining/separating unit, and a polarity converter element is installed on the optical path from the color separator unit to the third liquid crystal display element on the third optical axis.

6. An image display device according to claim 4, wherein the reflecting unit is comprised of any of aluminum, silver vapor deposition mirrors, full reflective prisms and mirror vapor deposition prisms, or is comprised of any of dichroic mirrors and dichroic prisms.

7. An image display device according to claim 2, wherein a first designated wavelength converter element for converting the polarization direction of a first light is installed on the incident side of the color combining/separating unit, a second designated wavelength converter element for converting the polarization direction of a second light is installed output side of the color combining/separating unit.

8. An image display device comprising:

a color separating unit for separating color in light, a first reflecting unit to change the optical axis of one light portion from the color separating unit at an approximate right angle;

a color separating/combining unit to separate a tight input by reflection from the first reflecting unit into a first light and a second light, to input the first light and the second light into a first and a second liquid crystal display element, respectively, installed in a vicinity of the color separating/combining unit, and to combine the first light and the second tight output from the first liquid crystal display element and second liquid crystal display element in the color separating/combining unit;

a color combining unit to be input with the first light and the second light from the color separating/combining unit; and

a second reflecting unit to reflect a third light separated by the color separating unit after permeation through the color combining unit, and input the third light to a third liquid crystal display element, wherein the light output from the third liquid crystal display element is inputted to the color combining unit to combine with the first light and second light.

9. An image display device according to claim 8, wherein a designated wavelength converter element is installed between the color separating unit and the color separating/combining unit.

10. An image display device according to claim 8, wherein a designated wavelength converter element is installed respectively between the color separating unit and the color separating/combining unit, and also between the color separating/combining unit and the color combining unit.

11. An image display device comprising:

a color separating unit for separating light having substantially a same polarization direction, a first reflecting unit to change an optical axis of a first light and a second light separated in the color separating unit at an approximate right angle;

a first designated wavelength converter element to convert the polarization direction of the first light which is reflected from the first reflecting unit and to permeate the second light therethrough without changing the polarization direction thereof;

a color separating/combining unit to separate the first light and the second light that permeated through the first designated wavelength converter element, to input the first and the second light to first and second liquid crystal display elements, respectively installed at approximate right angles to one another, to combine the first light and second light reflected from the first liquid crystal display element and second liquid crystal display element, respectively, and to emit a light output at an approximate right angle to the optical axis of the first and second light input thereto;

a second designated wavelength converter element to convert light from among the first and second light emitted from the color separating/combining unit to a first light polarization direction;

a color combining unit to be input with the first light and the second light from the second designated wavelength converter element;

a polarity converter element to convert the polarization direction of a third light separated by the color separating unit; and

a unit to input a third light from the polarity conversion element to permeate the color combining unit to a third liquid crystal display element wherein the third light reflected from the third liquid crystal display element is input to the color combining unit, and is combined with the first and second light and output.

12. An image display device according to claim 11, wherein a surface area of the section for the color separating/combining unit to output light is smaller than a surface area of the section for the color combining unit to be input with light.

13. An image display device comprising:

three reflective image display elements each provided for a red, a blue and a green color for forming optical images according to video signals from light output from a light source unit;

an optical system to beam light onto the reflective image display elements; and

a projection unit to project the light output from the reflective image display elements;

wherein a plurality of polarity separating/combining units for separating and/or combining the light based on the polarization of the light and a color separating/combining unit for separating and/or combining by reflecting or permeating light of a designated wavelength are combined on the optical axis of the reflective image display elements, and an optical axis output from the reflective image display for green color and an optical axis of the projection unit are made substantially in parallel, and the output light from the reflective image display is input to the projection unit permeating through two of polarity separating/combining units.