JPH09258026A - Display device utilizing holographic optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avert the coloration caused by UV rays included in light for irradiation and the thermal deformation caused by IR rays of a display device utilizing a HOE(holographic optical element) requiring a light source for irradiation. SOLUTION: This display device is constituted by not directly irradiating the HOE of the display device utilizing the HOE requiring the light source for irradiation with the UV rays and IR rays included in the light for irradiation. The method thereof includes the following (1) to (4): (1) The HOE is illuminated with the light source for illumination via an optical filter for shielding the UV rays and IR rays. (2) The filter is formed on the surface of the HOE by coating or laminating. (3) A material for absorbing the UV and IR rays is incorporated into the photosensitive material which constitutes the HOE. (4) The light source for irradiation which does not contain UV or IR rays is used.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a holographic optical element (hereinafter, HOE; Holographic Optical Element).
Referred to as a display device.

[0002]

2. Description of the Related Art The HOE uses holograms to replace existing optical elements (lenses, prisms, etc.) by utilizing the optical characteristics of holograms, and has the advantage of reducing the size and cost of applied equipment. Have.

In recent years, as a new HOE, an HOE (hereinafter, referred to as HCF: Holographic Color) as a color filter utilizing a spectral diffraction characteristic of a hologram or a diffraction grating is used instead of an existing color filter using a dye or a pigment.
A filter) is also known, and among display devices using HOE, a full-color liquid crystal image display device using HCF (see FIG. 1) is also known, and the following are exemplified.

Japanese Laid-Open Patent Publication No. 5-232319 This is a proposal by the applicant relating to the improvement of a liquid crystal video projector in a liquid crystal image display device, in which each color cell of the color filter itself is formed by a hologram, and red, green, and blue are formed. It has a hologram panel (HCF) consisting of holograms of minute dots corresponding to each color.
A slit provided with a light-transmitting part is arranged so that the diffracted light corresponding to each color from F is condensed, and the light passing through the slit is connected as red, green, and blue dots on the screen. It is a liquid crystal video projector that makes images.

Japanese Laid-Open Patent Publication No. 5-249318 discloses that a hologram element diffracts liquid crystal irradiation light in directions corresponding to the arrangement of three primary color image display pixels (liquid crystal cells).
Disperse into primary color light. A color image is displayed by irradiating each of the three primary color image display pixels with corresponding three primary color light.

Japanese Laid-Open Patent Publication No. 6-308332 discloses that incident light (white light) is diffracted and separated by a hologram so that light having different wavelengths is emitted to a desired position in a predetermined spatial period, and (existing) color Without using a filter, the use efficiency of the backlight for liquid crystal display etc. is greatly improved.

In the above-mentioned proposals, by using HCF, the absorption of liquid crystal irradiation light (white backlight) is less than that of existing color filters, the light utilization efficiency is improved, and bright and small power consumption is achieved. A full color liquid crystal image display device is provided.

However, when a volume phase hologram in which a diffraction grating (interference fringes) is recorded in a photosensitive material as a hologram in the form of refractive index modulation, the photosensitive material itself is used as a final product, a color filter (HCF). Therefore, the environment resistance is not good, and there is a problem in that, due to light, heat, or humidity in the usage environment of the liquid crystal image display device, performance degradation such as coloring, deterioration of diffraction efficiency, and white turbidity occurs. is there.

The above proposal describes that a volume phase hologram (transmission volume hologram element in which a photosensitive material such as photopolymer or dichromated gelatin is sandwiched) is used as the hologram element.

[0010]

Among the above-mentioned performance deterioration, coloring of HCF is caused by long-time irradiation of ultraviolet rays (wavelength: 185 nm to 380 nm) radiated from a liquid crystal irradiation light source, and a full-color display. This is a phenomenon unfavorable for use. In addition, the infrared region (wavelength: 780 nm to 14 nm) radiated from the liquid crystal irradiation light source is used.
(00 nm) gives heat to HCF,
The thermal deformation of CF deteriorates the alignment with the liquid crystal panel (cell), which is also a phenomenon not preferable for display applications. Both phenomena
Not only does it shorten the life of the display device, but it also degrades the major functions of the system, which require extremely high alignment accuracy.

The present invention is not limited to a full-color liquid crystal image display device using HCF, but is also applicable to all display devices using HOE that require an irradiation light source, such as coloring due to ultraviolet rays contained in the irradiation light or due to infrared rays. The purpose is to avoid thermal deformation.

[0012]

That is, the present invention is a display device having a structure in which the HOE is not directly irradiated with the ultraviolet rays and infrared rays contained in the irradiation light of the display device using the HOE which requires the irradiation light source.

In the apparatus of the present invention, the illumination light source illuminates the white light through the optical filter that blocks the ultraviolet rays (or infrared rays) contained in the white illumination light.

Alternatively, an optical filter that blocks ultraviolet rays (or infrared rays) contained in the white illumination light absorbs HOE provided on the surface by coating or laminating, or ultraviolet rays (or infrared rays) contained in the white illumination light. HOE formed by mixing the material to be mixed with the photosensitive material is used.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION A display device to which an optical filter for blocking ultraviolet rays is applied will be described below with reference to the drawings, but the description is similarly applicable to the case where infrared rays are used.

FIG. 2 is an explanatory view schematically showing an example of the display device of the present invention. An optical filter (represented as an ultraviolet film in the figure) that blocks ultraviolet rays and transmits light of other wavelengths is placed immediately before the white light source, and the ultraviolet rays are included in the illumination light that irradiates the HOE via the collimator. (Wavelength is 185 nm to 380 nm) is not included.

FIG. 3 is an explanatory view schematically showing another example of the display device of the present invention. Unlike FIG. 2, even when the illumination light that irradiates the HOE contains ultraviolet rays, a filter that blocks ultraviolet rays on the surface of the HOE itself and transmits light of other wavelengths (in the figure, , Represented by an ultraviolet ray film) by a method such as lamination so that the illumination light incident on the HOE itself does not include ultraviolet rays (wavelengths of 185 nm to 380 nm).

In any case, as another method of disposing the filter, a known ultraviolet absorbing material that absorbs ultraviolet rays and transmits light of other wavelengths may be formed by coating.

Alternatively, the HOE may be formed by mixing a known ultraviolet absorbing material into the photosensitive material.

Note that, unlike the above-mentioned embodiment, as an irradiation light source, ultraviolet rays (having a wavelength of 1
85nm ~ 380nm) and infrared (wavelength is 780nm
It is needless to say that the same effect can be obtained by using a material which does not include (1400 nm). (See Fig. 4)

[0021]

INDUSTRIAL APPLICABILITY Not only the full-color liquid crystal image display device using HCF but also the display device using HOE which requires an irradiation light source, in general, is colored (or is caused by ultraviolet rays (or infrared rays) contained in the irradiation light. , Thermal deformation) is avoided. Therefore, it is possible to prevent the life of the display device from being shortened and the main function of the system which requires extremely high alignment accuracy from being deteriorated.

[0022]

[Brief description of drawings]

FIG. 1 shows an example of H among display devices using HOE.
Explanatory drawing which concerns on the full-color liquid crystal image display device which used CF.

FIG. 2 is an explanatory view schematically showing an example of a display device of the present invention.

FIG. 3 is an explanatory view schematically showing another example of the display device of the present invention.

FIG. 4 is an explanatory view schematically showing another example of the display device of the present invention.

Claims (4)

[Claims] 1. A display device using a holographic optical element, characterized in that white light is illuminated from an illumination light source through an optical filter that blocks ultraviolet rays and / or infrared rays contained in white illumination light. . 2. A display device using a holographic optical element, characterized in that an optical filter for blocking ultraviolet rays and / or infrared rays contained in white illumination light is provided on the surface. 3. A display device using a holographic optical element, characterized in that a material that absorbs ultraviolet rays and / or infrared rays contained in white illumination light is mixed in a photosensitive material. 4. A display device using a holographic optical element, characterized by using a light source that emits white illumination light that does not contain ultraviolet rays and / or infrared rays.