JPH08254642A - Optical device and picture display device using it - Google Patents

Abstract

PURPOSE: To provide a picture display device where the occurrence of interference fringes is prevented and the irregularity of a picture is eliminated. CONSTITUTION: A spacer part 13 having a height equal to or above a coherence length order of wavelength of visible light beam) from an optical function surface 12 is projectingly provided to be uniformly high all over the periphery at the outer periphery area of the optical function surface 12, so that the optical device 11 is manufactured. The attaching surface of the spacer part 13 is stuck and attached on a polarizing plate 3 where a liquid crystal display panel 1 is stuck together and is housed at the inside of a housing part 2, so that the picture display device A is manufactured. Thus, space equal to or above the coherence length is provided between the optical function surface 12 and the polarizing plate 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical element and an image display device using the optical element. Specifically, the present invention relates to an optical element such as a diffraction grating and a microlens array used in an image display device such as a liquid crystal projector, a viewfinder, a liquid crystal display, and a head mounted display.

[0002]

2. Description of the Related Art FIG. 13 is a partially cutaway sectional view of an image display device B such as a liquid crystal projector using a liquid crystal display panel. 51 is a liquid crystal display panel, 52
Is a housing, and 53 is an optical element (optical low-pass filter) such as a diffraction grating. Polarizing plates 54 are arranged on both sides of the liquid crystal display panel 51, and light emitted from a backlight light source 55 arranged on one side of the liquid crystal display panel 51 is converted into linearly polarized light by the incident side polarizing plate 54. Then, the light passes through each pixel of the liquid crystal display panel 51 and again passes through the polarizing plate 54 on the emission side. At this time, the liquid crystal display panel 5
Only the light whose polarization direction is changed by the first liquid crystal layer (not shown) and coincides with the polarization direction of the polarizing plate 54 on the exit side is the polarizing plate 5
Since the light passing through the liquid crystal display panel 51 is displayed as a moving image by controlling the polarization characteristics of the liquid crystal layer corresponding to each pixel, the observer 59 passes the displayed moving image through the eyepiece lens 58. Can be observed.

In this image display device B, in order to reduce the roughness of the screen due to the so-called black matrix (wiring region of the liquid crystal display panel 51), the polarizing plate 5 is used.
The optical element 53 is arranged on the emission side of 4 so that it can be seen as if the light α is emitted from the direction of the wiring region 5. Reference numeral 56 is an adhesive for sticking the polarizing plate 54 to the liquid crystal display panel 51, and 57 is a cushioning material for bringing the optical element 53 into close contact with the polarizing plate 54.

[0004]

However, if the optical element 53 or the polarizing plate 54 has a slight warp or unevenness, or if foreign matter such as dust or dust enters between the optical element 53 and the polarizing plate 54. In some cases, a minute gap was generated at the bonding interface between the two. As a result, there is a problem that an interference fringe (Newton's ring) 60 as shown in FIG. 14 is generated, and the image observed through the eyepiece lens 58 is disturbed.

The present invention has been made in view of the above-mentioned drawbacks of conventional examples, and an object of the present invention is to provide an optical element which prevents the generation of interference fringes and does not disturb an image. It is in.

[0006]

DISCLOSURE OF THE INVENTION The first optical element of the present invention is an optical element in which an optical functional surface such as a lens array or a diffraction grating is formed on at least one surface of the base material. It is characterized in that a convex spacer portion is provided in a region where no is formed.

Therefore, by adhering the spacer portion to the optical element adhering surface of a liquid crystal display panel or the like, a sufficient space over the coherence distance can be provided between the optical elements. The occurrence of interference fringes can be suppressed.

An optical element according to a second aspect is characterized in that it also has a convex spacer portion in a region overlapping with the optically functional surface of the base material. Therefore, if the back side of the optical element is attached to the optical element attachment surface of a liquid crystal display panel or the like, the region where the optical functional surface is formed is supported by the spacer portion, and the surface opposite the optical functional surface and the optical element is supported. A space can be surely provided between and.

The second optical element of the present invention is an optical element in which an optical functional surface such as a lens array or a diffraction grating is formed on one surface of a base material, and at least the optical surface of the other surface of the base material. The anti-glare treatment is applied to the area facing the functional surface. Therefore, the light reflected by the optical element is not scattered and specularly reflected, and the incident light and the reflected light do not interfere with each other. Therefore, the generation of interference fringes can be suppressed. Moreover, the occurrence of interference fringes can be suppressed by a simple process such as etching or sandblasting.

The first image display device of the present invention is defined in claim 1.
And a liquid crystal display panel for generating an image, wherein the convex spacer portion is in contact with the liquid crystal display panel.

Therefore, a sufficient space is provided between the optical element and the surface facing the optical element by the spacer portion, and the occurrence of interference fringes is eliminated, so that an image display apparatus with good image quality can be obtained.

A second image display device of the present invention includes the optical element according to claim 3 and a liquid crystal display panel for generating an image, and the antiglare-treated surface is the liquid crystal display panel. It is characterized by having an interview with.

Therefore, the light incident on the optical element and the light reflected on the incident surface of the optical element do not interfere with each other, and interference fringes are not generated, so that an image display apparatus with high image quality can be obtained.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a partially broken sectional view showing an image display device A which is an embodiment of the present invention. The image display device A is a viewfinder of a video camera, and displays various images by allowing light emitted from the backlight light source 6 to pass through only a certain pattern area of the liquid crystal display panel 1. You can In the image display device A, a liquid crystal display panel 1 is housed in a housing 2, and polarizing plates 3 are arranged on the incident side and the emitting side thereof. The polarizing plate 3 on the emitting side is an optically transparent adhesive 4
The optical element (optical low-pass filter) 11 of the present invention is mounted on the exit side of the polarizing plate 3 on the exit side. The optical element 11 is attached to the polarizing plate 3 by the cushion material 5.

FIG. 2A is a sectional view showing the optical element 11, which is in the form of a sheet, and the surface of the optical element 11 has optical functions such as a diffraction grating and a microlens array. The surface 12 is formed, and a convex spacer portion 13 is provided so as to project on the outer peripheral region of the optically functional surface 12. The spacer portion 13 has an optical function surface 1 so that the light reflected by the optical element 11 and the light transmitted through the polarizing plate 3 do not interfere with each other.
It has a height (specifically, about 0.1 mm) from 2 to the coherence length (about the wavelength of visible light) and is manufactured to have a uniform height over the entire circumference. In addition, a convex spacer portion 13 is provided so as to project also on the outer edge portion of the back surface of the optical element 11. The sheet-shaped optical element 11 is a transparent sheet base material 18 such as triacetyl cellulose (TAC), polycarbonate (PC), polyethylene terephthalate (PET), or an ultraviolet curable resin applied on the sheet base material 18. Optical function surface 1 for the lens resin material
It is manufactured by pressing a die (stamper) having a reverse pattern of No. 2 formed thereon, and has a thickness of 0.1 mm to 0.5 m.
The optical pattern has a depth of about 0.5 μm and a pattern period of about 3 to 30 μm. As shown in FIG. 2B, in the optical element 11, the optical functional surface 12 is made to face the polarizing plate 3 and the bonding surface of the spacer portion 13 is attached to the polarizing plate 3, whereby the optical functional surface 12 is formed.
A space 14 is provided between and the polarizing plate 3.

The light emitted from the backlight light source 6 passes through the polarizing plate 3 and is incident on the liquid crystal display panel 1 to generate a moving image. The observer 8 can observe the moving image displayed on the liquid crystal display panel 1 through the eyepiece lens 7. In this image display device A, the optical functional surface 1
Since a space 14 having a coherence length or more is provided between the image pickup device 2 and the polarizing plate 3, no interference fringes are generated and the image is not disturbed. In this way, by preliminarily projecting the spacer portion 13 on the optical element 11, a sufficient space 14 is secured between the optical element 11 and the polarizing plate 3 to suppress the generation of interference fringes, and the optical element 11 and the polarizing plate 3 are warped, The optical element 11 can be attached to the polarizing plate 3 without considering the generation of a gap due to the entry of dust or dirt. Further, the back surface side of the optical element 11 can be attached to the polarizing plate 3. In this case, it is advisable to provide the spacer portion 13 on the rear surface side at a height equal to or greater than the coherence distance so that a sufficient space 14 is formed between the rear surface of the optical element 11 and the polarizing plate 3 to cause interference fringes. Can be prevented. Although the optical element 11 is exaggerated for convenience of illustration, the outer shape of the sheet-shaped optical element 11 is, for example, 1 mm or less in thickness and several cm to ten and several cm square in length and width. Yes (same below).

FIG. 3 is a view showing a state in which the optical element 11 according to another embodiment of the present invention is mounted on the image display apparatus A. On the back surface of the optical element 11, a spacer portion 13 is provided on the entire back surface of the optical function surface 12 together with the space portion 13 of the outer edge portion in the shape of a protrusion or a cross. Therefore, the distance between the optical element 11 and the polarizing plate 3 can be more reliably kept constant, and the optical characteristics of the optical element 11 can be uniformly ensured. Particularly, in the case of the sheet-shaped optical element 11, it can be attached to the polarizing plate 3 without bending.

4 (a) and 4 (b) are a side view and a back view of an optical element 11 according to still another embodiment of the present invention, in which four protruding spacer portions are provided on the back surface of the optical element 11. 13 are provided. In this optical element 11, as shown in FIG. 5, when the spacer portion 13 is placed in the housing 2 so as to overlap the polarizing plate 3, the optical element 11
Sufficient space 14 can be provided between and the polarizing plate 3. At this time, for example, if a positioning portion (not shown) slightly shallower than the spacer portion 13 is provided in the polarizing plate 3 so as to face the spacer portion 13, the optical element 11 can be easily positioned.

FIG. 6A is an explanatory view showing a method of manufacturing the optical element 11 which is still another embodiment of the present invention. In order to form the spacer portion 13 on the optical element 11, FIG. Do the following: First, as shown in FIG. 6 (a), a lower die 16 provided with a recess 17 for forming a spacer portion 13 is provided with a jig (not shown) on a sheet base material 18 having an optically functional surface 12 formed thereon. Lower mold 16 by
Supported in place. Then, rod-shaped molding rod 1
9 is pressed from above the sheet base material 18 to project the spacer portion 13 to the back surface side of the sheet base material 18 (FIG. 6B). At this time, if the sheet base material 18 is heated, the spacer portion 13 can be easily projected.

The optical element 11 has a case 22 in which a liquid crystal display panel 1 (a polarizing plate 3 is attached to the liquid crystal display panel 1 with an adhesive 4) is housed, for example, as shown in FIG. It is mounted on the top surface. A positioning portion 23, which is slightly shallower than the spacer portion 13, is provided on the upper surface of the case 22 in advance at a position located on the spacer portion 13. The spacer portion 13 is fitted into the positioning portion 23 so that a sheet-shaped optical member can be easily formed. The element 11 can be mounted at a predetermined position on the upper surface of the case 22.

In each of the above-mentioned embodiments, the case where the optical element 11 provided with the spacer portion 13 is used has been described. In the next FIG. 8, an optical element subjected to anti-glare processing (non-glare processing) for preventing interference. The case where 31 is used is shown. As shown in FIG. 8A, the back surface of the optical element 31 is subjected to anti-glare processing to form an anti-glare processing surface 32. The anti-glare treatment is a treatment for roughening the surface of a substrate or the like into a ground glass by etching or sandblasting, and the ambient light incident on the anti-glare treated surface 32 is scattered without being specularly reflected.
FIG. 9 shows a surface profiler (Dektak3030, VEECO INSTRU) of the anti-glare surface 32 of the optical element 31.
MENTS Inc.) surface scanning results.
The anti-glare treated surface 32 has a period of several tens of μm and several μm.
The unevenness with the amplitude of is observed. In the figure, the vertical axis represents the amplitude (1 μm per scale) and the horizontal axis represents the distance in the scanning direction (100 μm per scale). In the photograph shown in FIG. 10, light is incident on the optical element 31 from the antiglare surface 32 side,
The surface of the optical element 31 is observed from the exit side by an optical microscope (about 400 times), and the incident light is diffusely reflected on the anti-glare surface 32 as shown in white in the photograph. I understand. Therefore,
If the antiglare surface of the optical element 31 is attached to the polarizing plate 3 as shown in FIG. 8B, the light reflected by the optical element 31 is scattered without being specularly reflected, and the light from the polarizing plate 3 is reflected. No interference with the emitted light occurs. Therefore, the optical element 3
No interference fringes are generated even if a slight gap (gap less than the coherence length) is generated due to the warp of 1 or the polarizing plate 3 or the intrusion of dust or dust, and the deterioration of the image quality of the image display device A is prevented. You can According to this optical element 31, the spacer portion 1
It is not necessary to provide 3, and the optical element 31 can be easily manufactured by subjecting the back surface of the conventional optical element 53 to a simple process such as etching or sandblasting.

At this time, the light α incident on the anti-glare surface 32 is converted into a spread light β (having a directional half-value angle θ) like Lambertian light as shown in FIG. Therefore, it is desirable that the directional half-value angle θ of the light converted by the anti-glare processing surface 32 satisfies the condition of the following expression, and if the anti-glare processing that makes the directional half-value angle θ larger than this expression is performed, The light emitted from each pixel 32 of the liquid crystal display panel 1 is blurred and overlaps with the image of the adjacent pixel, which causes deterioration of the image. θ ≦ tan ⁻¹ {Λ / (2 × L)}) where Λ is the array period of each pixel 33 of the liquid crystal display panel 1, and L is the optical distance from each pixel 33 to the anti-glare processing surface 32. Shown (see FIG. 12).

In the above embodiment, the sheet-like optical element 11 (31) is used, but other than this, for example, the so-called 2P method (Photopolymerization-Method) is used.
It goes without saying that the present invention can also be applied to optical elements such as microlens arrays and diffraction gratings manufactured by injection molding or the like.

[0024]

According to the first optical element of the present invention, a sufficient space can be provided between the optical element and the surface on which the optical element such as a liquid crystal display panel is adhered by the spacer portion, and interference fringes are generated. Can be prevented. Further, by providing the spacer portion in a region corresponding to the optically functional surface on the surface where the optically functional surface is not formed, the space can be surely provided.
This is an effective method especially when an optical element having a large area is formed.

Therefore, in the first image display device provided with such an optical element, image distortion is reduced.

Further, according to the second optical element of the present invention, the light reflected by the anti-glare-treated surface of the optical element is scattered and no interference fringes are generated. Moreover, the occurrence of interference fringes can be prevented by a simple process.

Therefore, even in the second image display device of the present invention, interference fringes do not occur and the image disturbance is reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram in which an image display device of the present invention is partially broken.

FIG. 2A is a cross-sectional view of an optical element that is an embodiment of the present invention, and FIG. 2B is an explanatory diagram showing a state in which the optical element is mounted on an image display device.

FIG. 3 is an explanatory diagram showing a state in which an optical element according to another embodiment of the present invention is attached to an image display device.

4A and 4B are a side view and a rear view showing an optical element which is still another embodiment of the same.

FIG. 5 is an explanatory diagram showing a state in which the above optical element is mounted on an image display device.

FIG. 6A is an explanatory view showing a method for manufacturing an optical element which is another embodiment of the same, and FIG. 6B is a sectional view of the optical element.

7 (a) and 7 (b) are explanatory views showing a method for mounting the optical element of the above to an image display device.

FIG. 8A is a cross-sectional view showing an optical element whose back surface has been subjected to anti-glare treatment, and FIG. 8B is an explanatory view showing a state where the optical element is mounted on an image display device.

FIG. 9 is a diagram showing a surface scanning result of an antiglare-treated surface by a surface profiler.

FIG. 10 is an optical micrograph showing a light scattering phenomenon caused by an antiglare-treated optical element.

FIG. 11 is an explanatory diagram showing how incident light spreads and is incident on an optical element by an anti-glare surface.

FIG. 12 is an explanatory diagram showing a limiting condition in anti-glare processing.

FIG. 13 is a sectional configuration diagram in which a conventional image display device is partially broken.

FIG. 14 is a diagram showing interference fringes observed in the image display device of the above.

[Explanation of symbols]

 1 Liquid Crystal Display Panel 3 Polarizing Plate 11 Sheet-Shaped Optical Element 12 Optical Functional Surface 13 Spacer Section 31 Anti-Glare Optical Element

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number in the agency FI Technical indication location G02F 1/1335 G02B 1/10 Z (72) Inventor Yutaro Okuno Hanazono Takudo, Kyoto, Kyoto Prefecture 10th town OMRON Corporation

Claims (5)

[Claims] 1. An optical element in which an optically functional surface such as a lens array or a diffraction grating is formed on at least one surface of a substrate, wherein a convex shape is formed in a region of the substrate where the optically functional surface is not formed. An optical element having a spacer portion. 2. The optical element according to claim 1, wherein a convex spacer portion is also provided in a region overlapping with the optically functional surface of the base material. 3. An optical element in which an optically functional surface such as a lens array or a diffraction grating is formed on one surface of a base material, in at least a region of the other surface of the base material facing the optically functional surface. An optical element characterized by being subjected to anti-glare treatment. 4. An image display comprising the optical element according to claim 1 and a liquid crystal display panel for generating an image, wherein the convex spacer portion is brought into contact with the liquid crystal display panel. apparatus. 5. An image display, comprising: the optical element according to claim 3; and a liquid crystal display panel for generating an image, wherein the anti-glare surface is brought into contact with the liquid crystal display panel. apparatus.