JP2009109618A - Projection display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projection display which is simple in structure, inexpensive and improved in brightness. <P>SOLUTION: The projection display includes: a first optical system which projects an image composed of a plurality of pixels onto a screen; and a second optical system which emits near-ultraviolet light having a spatial intensity distribution corresponding to brightness for each of the plurality of pixels on the image. In the surface of the screen 10, a phosphor film 10c which is excited by the near-ultraviolet light, to emit light is provided as a phosphor composition which is uniform in a screen surface, without being patterned. The phosphor film 10c is irradiated with the near-ultraviolet light high in intensity, in accordance with the pixel of a high brightness signal. On the other hand, the phosphor film 10c is irradiated with the near-ultraviolet light low in intensity, in accordance with the pixel of a low brightness signal. The screen 10 is used, so that the projection display which is simple in structure, inexpensive and improved in brightness can be provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a projection display, and more particularly, to a projection display that is simple and inexpensive in structure and has improved luminance.

  In a projection display, light from each light source is enlarged and projected on the screen by blocking light for each pixel corresponding to the video signal. For such light blocking for each pixel, for example, light blocking by a liquid crystal light valve is performed. The effect is used. What is observed as reflected light on the image projected on the screen is called front projection, and what is observed as transmitted light is called rear projection.

As technical problems of such a projection display, there are an improvement in luminance of an image projected on a screen and a simplification of a system structure. Patent Document 1 (Japanese Patent Application Laid-Open No. 11-31833) is patterned on a screen. A projection liquid crystal display in which R (red), G (green), and B (blue) phosphors are formed and the phosphor is excited and emitted by near ultraviolet rays to improve luminance and color purity. It is disclosed.
JP 11-311833 A

  However, in the projection liquid crystal display described in Patent Document 1, the phosphor film provided on the screen is formed by patterning phosphors of R (red), G (green), and B (blue). Is not always easy. For example, when the screen is made of an organic film, the pattern of the fluorescent film may be misaligned due to thermal expansion. In addition, the manufacturing cost is inevitably increased by the amount that requires a patterning process with high positional accuracy.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a projection display that has a simple structure, is inexpensive, and has improved luminance.

  In order to solve such a problem, a projection display according to the present invention includes a first optical system that projects an image composed of a plurality of pixels on a screen, and a spatial according to the luminance of each of the plurality of pixels. A second optical system that irradiates near-ultraviolet light having an intensity distribution on the image, and is a phosphor film that emits light when excited by the near-ultraviolet light on the surface of the screen. A phosphor film that is uniform in the plane is provided.

The phosphor film provided on the screen includes, for example, ZnS, ZnSe, CdS, ZnTe, CdSe, CdTe, europium and samarium activated lanthanum sulfide phosphors (La ₂ O ₂ S: Sm, Eu), europium and manganese. From the group of active barium magnesium aluminate phosphor (BaMgAl ₁₀ O ₁₇ : Eu, Mn), europium activated chlorostrontium phosphate phosphor ((Sr, Ca, Ba) ₁₀ (PO ₄ ) ₆ · Cl ₂ : Eu) At least one phosphor to be selected is included.

  Preferably, the phosphors are a plurality of types of phosphors that can obtain a white color by additive color mixing.

  Preferably, the phosphor is a fluorescent particle having an average particle size of 0.5 μm or less.

  In the present invention, the phosphor film may contain a light absorber.

  The light absorber is, for example, carbon black having an average particle size of 0.5 μm or less.

  In the present invention, a phosphor film that emits fluorescence when excited by near-ultraviolet light is provided on the observation surface side of the screen included in the projection display, and high-intensity near-ultraviolet light is irradiated corresponding to pixels having a high luminance signal. On the other hand, since low-intensity near-ultraviolet light is irradiated in response to pixels having a low luminance signal, it is possible to provide a projection display with a simple structure, low cost, and improved luminance. In addition, there is an advantage that it is not necessary to accurately align an image projection optical system with an optical system for improving luminance, and is easy to handle.

  The projection display of the present invention will be described below with reference to the drawings.

  FIG. 1A is a schematic cross-sectional view for explaining a configuration example of a screen 10 included in the projection display of the present invention. Reference numeral 10a denotes a high reflectance layer having a high reflectance with respect to projection light of an image, and reference numeral 10b denotes A light scattering layer for scattering projection light of an image, and a reference numeral 10c are phosphor films that are provided on the observation surface side of the screen 10 and emit fluorescence when excited by near-ultraviolet light. The phosphor film 10c emits light. The brightness of the image is improved by the light. Then, as shown in FIG. 1B, high-intensity signal pixels are irradiated with high-intensity near-ultraviolet light (near-ultraviolet light A), while low-intensity signal pixels are associated. By irradiating low-intensity near-ultraviolet light (near-ultraviolet light B), the luminance of each pixel of the image projected on the screen 10 is improved according to the amount of irradiation of these near-ultraviolet light. It is.

  As will be described in detail later with reference to the drawings, the projection display according to the present invention includes a first optical system that projects an image composed of a plurality of pixels on a screen, and a luminance for each of the plurality of pixels. And a second optical system for irradiating near ultraviolet light having a spatial intensity distribution superimposed on the image. As shown in FIG. A phosphor film 10c that emits light when excited by near-ultraviolet light is provided. The phosphor film 10c is not patterned as in the invention described in Patent Document 1, and has a uniform phosphor composition within the screen surface.

The phosphors contained in the phosphor film are, for example, ZnS, ZnSe, CdS, ZnTe, CdSe, CdTe, europium and samarium activated lanthanum sulfide phosphors (La ₂ O ₂ S: Sm, Eu), europium and manganese. From the group of active barium magnesium aluminate phosphor (BaMgAl ₁₀ O ₁₇ : Eu, Mn), europium activated chlorostrontium phosphate phosphor ((Sr, Ca, Ba) ₁₀ (PO ₄ ) ₆ · Cl ₂ : Eu) It is good also as combining several types of fluorescent substance which is the at least 1 sort (s) of fluorescent substance selected and can obtain white by additive color mixture.

  The average particle diameter of the phosphor is, for example, 0.5 μm or less, more preferably 0.2 μm or less, from the viewpoint of suppressing the effect of scattering the image projection light.

  The phosphor film 10c may contain a light absorber together with the above-described phosphor. This light absorber is for reducing the light intensity (background intensity) from the position on the screen corresponding to the pixel whose original luminance should be zero. Examples of such a light absorber include carbon black having an average particle size of 0.5 μm or less (more preferably 0.2 μm or less). When carbon black is used as the light absorber, the light reflectance from the screen surface (the surface of the phosphor film 10c) can be 50% or less.

  Hereinafter, a specific configuration of the projection display of the present invention will be described by way of examples.

  FIG. 2 is a diagram for explaining a first configuration example of the projection display of the present invention. The light source 1 is a light source of a first optical system that projects an image composed of a plurality of pixels on the screen 10. For example, red (R), green (G), and blue (B) light of visible light is used. High pressure mercury lamp or LED light source. The light from the light source 1 is divided into RGB light by two dichroic mirrors (3, 4) and three mirrors (5, 6, 7), and enters the liquid crystal light valve 8, and this RGB light Is converted into image light by the light blocking effect of the liquid crystal light valve 8 for each pixel corresponding to the image signal. The image light is enlarged by a lens group 9 provided between the liquid crystal light valve 8 and the screen 10, and the enlarged image is projected on the screen 10.

  The projection display of the present invention further includes a second optical system that irradiates the image with near-ultraviolet light having a spatial intensity distribution corresponding to the luminance of each of a plurality of pixels of the image projected by the first optical system. It has. The light source 2 is a light source of the second optical system, and a high-pressure mercury lamp or LED light source similar to the light source 1 can be used. As the light from the light source 2, light in the near ultraviolet band of, for example, 380 to 420 nm is selected by the bandpass filter 11, and this near ultraviolet light is incident on the liquid crystal light valve 12.

  The liquid crystal light valve 12 receives a luminance signal obtained by calculating the light intensity signal for each pixel of the image projected on the screen 10 by the first optical system, and a pixel corresponding to the luminance signal. Each light is blocked. Signal processing (control) is performed so that light corresponding to each pixel of the liquid crystal light valve 8 provided in the first optical system is transmitted from each pixel of the liquid crystal light valve 12. That is, in the image projected on the screen 10, the liquid crystal light valve 12 corresponding to the pixel with low light intensity has a low near-ultraviolet light transmittance, while the liquid crystal light corresponding to the pixel with high light intensity. In the pixel of the bulb 12, the transmittance of near ultraviolet light is high. The transmitted near-ultraviolet light is enlarged and projected by a lens group 13 and a mirror 14 provided between the liquid crystal light valve 12 and the screen 10, and is superimposed on the image projected on the screen 10.

  Near-ultraviolet light superimposed on the image projected on the screen 10 excites the phosphor film 10c provided on the observation surface side of the screen 10, and the luminance of the image is improved by this excitation fluorescence.

  In FIG. 2, the light source 1 and the light source 2 are separate light sources, but may be a single light source. In addition, an optical component such as a dichroic mirror of the first optical system can also be configured to serve as an optical component of the second optical system.

  FIG. 3 is a diagram for explaining a second configuration example of the projection display according to the present invention. In this configuration, the number of optical components such as a liquid crystal light valve is greatly reduced. Light from the light source 1 is incident on a color wheel 15 capable of time-dividing each RGB light, transmitted light from the color wheel 15 is incident on a liquid crystal light valve 16, and an image is enlarged by a lens group 17 to form an enlarged image. Projected onto the screen 10.

  The light from the light source 2 passes through a bandpass filter 18 that selects light in the near ultraviolet band of, for example, 380 to 420 nm, is reflected by a mirror 19 and enters the liquid crystal light valve 16 described above. Due to the light blocking effect of the liquid crystal light valve 16, near ultraviolet light having a spatial intensity distribution corresponding to the luminance for each of the plurality of pixels is enlarged and projected on the image on the screen 10.

  According to the present invention, there is provided a projection display having a simple structure, low cost, and improved luminance.

It is the cross-sectional schematic for demonstrating the structural example of the screen with which the projection display of this invention is provided. It is a figure for demonstrating the 1st structural example of the projection display of this invention. It is a figure for demonstrating the 2nd structural example of the projection display of this invention.

Explanation of symbols

1, 2 Light source 3, 4 Dichroic mirror 5, 6, 7, 14, 19 Mirror 8, 12, 16 Liquid crystal light valve 9, 13, 17 Lens group 10 Screen 10a High reflectivity layer 10b Light scattering layer 10c Phosphor film 15 Color wheel 11, 18 Band pass filter

Claims (6)

A first optical system that projects an image composed of a plurality of pixels on a screen;
A second optical system that irradiates near-ultraviolet light having a spatial intensity distribution in accordance with the luminance of each of the plurality of pixels so as to overlap the image;
A projection display, characterized in that a phosphor film that emits light when excited by the near-ultraviolet light and has a uniform phosphor composition within the screen surface is provided on the surface of the screen. The phosphor film provided on the screen includes ZnS, ZnSe, CdS, ZnTe, CdSe, CdTe, europium and samarium activated lanthanum sulfide phosphors (La ₂ O ₂ S: Sm, Eu), europium and manganese activated aluminum. Selected from the group consisting of barium magnesium oxide phosphor (BaMgAl ₁₀ O ₁₇ : Eu, Mn) and europium-activated chlorostrontium phosphate phosphor ((Sr, Ca, Ba) ₁₀ (PO ₄ ) ₆ · Cl ₂ : Eu) The projection display according to claim 1, wherein at least one kind of phosphor is contained.   The projection display according to claim 2, wherein the phosphors are a plurality of types of phosphors capable of obtaining white by additive color mixing.   The projection display according to claim 3, wherein the phosphor is a fluorescent particle having an average particle diameter of 0.5 μm or less.   The projection display according to claim 1, wherein the phosphor film contains a light absorber.   The projection display according to claim 5, wherein the light absorber is carbon black having an average particle size of 0.5 μm or less.