JP2001147307A - Optical collimator sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical collimator sheet which efficiently gathers diffused rays of light and gives collimated rays of light having high directivity and high luminance. SOLUTION: This optical collimator sheet has a transparent substrate, with many light transmissive spherical bodies fixed on the substrate, while keeping partial contact with the substrate and a reflection layer which has a scattering length S [μm] in the range of 1<S<(R/80) (where R is the diameter [μm] of the spherical bodies) and diffuses light which was incident on the sheet except at the contact parts or further except at their vicinities.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of an optical collimator sheet that makes diffused light straight, and
The present invention relates to an optical collimator sheet which can obtain collimated light having high directivity and high brightness, and which is suitably used for a backlight of a liquid crystal display.

[0002]

2. Description of the Related Art In recent years, the frequency of use of liquid crystal displays (LCDs) as word processor and computer displays has been greatly increased. In addition, the use of the LCD as a monitor of a medical diagnostic apparatus such as an ultrasonic diagnostic apparatus, a CT diagnostic apparatus, and an MRI diagnostic apparatus, which has conventionally been mainly a CRT (Cathode Ray Tube), is being considered.

[0003] LCDs have numerous advantages, such as being easy to miniaturize, thin and lightweight. On the other hand, the viewing angle characteristics are poor (the viewing angle is narrow). That is, the contrast ratio of the image sharply decreases depending on the viewing direction and the angle, and the inversion of the gradation also occurs, so that the image looks different. Therefore, there is a problem that the image cannot be properly observed depending on the position of the observer or the like. In particular,
In medical applications such as those described above, diagnosis is performed based on the density of the image, so an image with a high contrast ratio is required.
Inappropriate recognition of an image causes erroneous diagnosis and discrepancy in diagnosis results. Therefore, especially over a wide viewing angle,
A display image with a high contrast ratio is required. further,
In a medical monitor, a display image is usually a monochrome image, and the image contrast greatly depends on the viewing angle, which is more problematic.

As a wide viewing angle LCD, IPS (In-Plan)
e Swiching) mode, MVA (Multidomaoin Vertical A)
lignement mode LCDs are also known. However, even with these, a sufficiently wide viewing angle has not been ensured for monochrome images, particularly for medical use.

On the other hand, as an LCD capable of obtaining an image with a good contrast ratio over a wide viewing angle, collimated light (straight light) is used as light (backlight) irradiated to the liquid crystal panel from the back (collimated backlight). Further, there is known an LCD in which light carrying an image passing through a liquid crystal panel is diffused by a diffusion plate. This L
In a CD, a wider viewing angle can be realized by using a backlight having higher directivity and higher luminance. Therefore, for medical applications requiring a wide viewing angle as described above, it is particularly preferable to use a backlight having strong directivity and high brightness. Therefore, an appearance of an optical collimator having strong directivity and capable of obtaining high-brightness collimated light is desired.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical collimator sheet which efficiently collects diffused light, has strong directivity, and can obtain high-brightness collimated light. . By using the optical collimator sheet of the present invention, in a rear projection display such as a liquid crystal display of a type in which the distance from the image forming surface to the screen (observation surface) is relatively short, a diffusion light source such as a fluorescent lamp, a liquid crystal panel Image display devices, such as
When used with a light diffusion screen (or a fluorescent screen), a high-quality image with a wide viewing angle can be displayed.

[0007]

SUMMARY OF THE INVENTION To achieve the above object, the present invention provides a transparent support, a plurality of light-transmitting spheres partially fixed to the support, Length S
[Μm] is 1 <S <(R / 80), and a reflection layer for diffusing light incident on a portion other than the contact portion between the support and the sphere or further near the contact portion. Provide a featured optical collimator sheet (where R is the diameter [μm] of the sphere).

It is preferable that the reflection layer has a binder for fixing a sphere to the support, and a light scattering substance dispersed in the binder.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an optical collimator sheet of the present invention will be described based on a preferred embodiment shown in the accompanying drawings.
This will be described in detail.

FIG. 1 conceptually shows an example of a display device using the optical collimator sheet of the present invention. A display device 10 shown in FIG. 1 includes a liquid crystal panel 12 as an image display means.
A so-called liquid crystal display (hereinafter referred to as LCD)
Then, the liquid crystal panel 12 and the optical collimator sheet 20 of the present invention, into which a backlight is incident, are provided.
And a light diffusing plate 16 for diffusing light carrying an image that has passed through the liquid crystal panel 12. The display device 10 using the optical collimator sheet 20 of the present invention has strong directivity and can use high-luminance collimated light (straight light) as a backlight. Therefore, a high contrast ratio can be realized over a wide viewing angle, and it can be suitably used as a monitor of a medical diagnostic apparatus.

The display device 10 includes a backlight unit 1
4 is a known LCD except that the optical collimator sheet of the present invention is used. That is, the collimated light (collimated backlight) emitted from the backlight unit 14
Is incident on the liquid crystal panel 12 driven according to the display image and passes therethrough, and becomes light carrying the image,
This is diffused by the light diffusion plate 16 and an image is displayed.
Therefore, a driver (not shown) for driving the liquid crystal panel 12 is connected to the liquid crystal panel 12, and the display device 10
Various members of a known LCD are arranged as needed.

In the display device 10 using the optical collimator sheet 20 of the present invention, the liquid crystal panel 12 is filled with a liquid crystal between transparent supports arranged with a predetermined gap, and a transparent electrode is provided. A known liquid crystal panel used for various LCDs, in which an analysis plate is disposed on one side of the sheet and a polarizing plate is disposed on the other side, may be used. Therefore, the liquid crystal panel 12
It may be color or monochrome, and the operation mode is T
N (Twisted Nematic) mode, STN (Super Twisted Nmatic)
ematic) mode, ECB (Electrically Controlled Bir
efringence) mode, IPS mode, MVA mode, and all other operation modes are available. Further, there is no limitation on the switching element or the matrix.

The light diffusing plate 16 is not particularly limited, and various known light diffusing plates (sheets) can be used. As an example, Japanese Patent Application Laid-Open No. 7-5306 discloses a light having a crosslinked layer of an ion conductive resin having a cationic quaternary ammonium base in a side chain between a transparent support and a light diffusion layer. Diffusion plate; disclosed in JP-A-7-174909, having a diffusion layer containing an organic polymer binder and organic polymer particles on one surface of a transparent support, wherein the refractive index difference between the binder and the particles is 0.05 or less; The weight average particle diameter of the particles is 10 μm to 2
1 μm, a light diffusion plate having a binder / particle weight ratio of 1.9 to 3.6, an application amount of both of them of 10 g / m ^{2 to} 17 g / m ² , and a standard deviation of particle size distribution within 3.5 μm. And the like are preferably exemplified.

The backlight unit 14 is a so-called collimated backlight emitting unit that emits collimated light (straight light) as a backlight for observing an image on the liquid crystal panel 12. In the illustrated example, the backlight unit 14 includes a housing 18, a light source (not shown) arranged in the housing 18, and the optical collimator sheet 20 of the present invention.

The light source of the backlight unit 14 is the display device 1
A light source used in known LCDs, such as a fluorescent lamp, is appropriately used as long as it can emit a sufficient amount of light (diffused light) in accordance with the application of No. 0. The housing 18 for housing the light source is a housing having an open portion on one surface and having a light-diffusing (reflective) inner surface such as white or a mirror surface.

The light collimator sheet 20 of the present invention comprises a transparent support sheet 22 and a plurality of light-transmitting spheres 24 (hereinafter referred to as beads 2) that are partially contacted and fixed to the support sheet 22.
4) and a reflective layer 26 that diffuses the incident light except at the contact portion (or near the contact portion) between the support sheet 22 and the beads 24. The optical collimator sheet 20 is arranged and held on the backlight unit 14 such that the open side of the housing 18 is closed with the beads 24 facing the liquid crystal panel 12.

In the optical collimator sheet 20 of the present invention, ideally, the reflection layer 26 is
Other than the contact portion between the beads 24 and
Is formed so as to cover the entire surface of the support sheet 22 in the area where the is fixed. However, since the beads 24 are fine,
Depending on the manufacturing method of the optical collimator sheet 20 and the composition of the reflective layer 26, it may be unavoidable that a region where the reflective layer 26 is not formed is formed near the contact portion between the support sheet 22 and the beads 24. The present invention also includes this.

The support sheet 22 is not particularly limited, and various materials can be used as long as they have a sufficient light transmittance and a sufficient mechanical strength according to the application. Specifically, various types of glass, polyester, polyolefin, polyamide, polyether, polystyrene,
Various resin materials such as polyesteramide, polycarbonate, polyphenylene sulfide, polyetherester, polyvinyl chloride, and polymethacrylic acid ester are preferably exemplified. In addition, the optical collimator sheet 20 of the present invention may be in the form of a rigid plate or in the form of a flexible sheet or film. The material and thickness of the support sheet 22 may be selected depending on the required mechanical strength and application.

The beads 24 are light-transmitting (substantially) spheres,
In the illustrated example, a part thereof is in contact with the support sheet 22 and is fixed to the support sheet 22 by the reflection layer 26 (the binder thereof). The material of the beads 24 is not particularly limited, and various materials can be used as long as they are transparent. For example, various examples of the material of the above-described sheet material 18 are provided.
Glass and (meth) acrylic resin are preferably used in terms of good optical characteristics.

The diameter R of the beads 24 is not particularly limited, and may be appropriately selected according to the use and size (area) of the optical collimator sheet 20. If the beads 24 are too small, the reflection layer 26 described later must be thinned.
Light and the like that pass through the reflection layer 26 increase, and as a result, the directivity and efficiency (that is, the luminance of the emitted light) of the optical collimator sheet 20 decrease. Therefore, the diameter R of the beads 24 is preferably set to 40 μm or more. Conversely, if the size of the bead 24 is too large, the shape of the bead 24 causes noise to the image.
The size of 4 is preferably 5 mm or less. Therefore,
The diameter R of the beads 24 is from 40 μm to 5 mm, especially 10 μm.
It is preferably from 0 μm to 2 mm.

As described above, the reflection layer 26 is formed of the beads 24.
It blocks light from passing through portions other than the contact portion between the sheet and the support sheet 22, and is basically formed so as to cover at least the entire surface of the support sheet 22 in a region where the beads 24 are fixed. In the optical collimator sheet of the present invention, when the diameter of the beads 24 is R [μm],
It has a scattering length S [μm] of “1 <S <(R / 80)”. The scattering length S (light scattering length) means an average distance that light travels straight before being scattered once, and the shorter the scattering length, the higher the light scattering property.

As schematically shown in FIG. 2, in the light collimating sheet 20 of the present invention, the diffused light emitted from the light source in the housing 18 enters from the support sheet 22 side and acts on the reflecting layer 26. Accordingly, the light enters the beads 24 from the contact portion between the beads 24 and the support sheet 22, is refracted by the spherical beads 24, is appropriately condensed, and becomes collimated light. On the other hand, the optical collimator sheet 20 of the invention
In the above, the reflection layer 26 is formed of “1 <S <(R / 80)”
Has a scattering length S of Therefore, the diffused light other than the contact portion, that is, the diffused light incident on the reflective layer 26 is preferably diffused on the surface or inside of the reflective layer 26, that is, reflected by the reflective layer 26, returned to the housing 18, and returned to the housing 18. The light is reflected by the inner surface and reenters the optical collimator sheet 20.

That is, the optical collimator sheet 2 of the present invention
In the case of 0, of the diffused light emitted from the light source, only light appropriately incident on the beads 24 is collected and emitted as collimated light. On the other hand, the light incident on the reflection layer 26 is well reflected, so that the light emitted from the light source can be used without waste. Therefore, the optical collimator sheet 20 of the present invention has a small amount of light (leakage light) passing through the reflective layer 26,
In addition, it is possible to emit collimated light with high directivity and high brightness with high light use efficiency. Therefore, by using the optical collimator sheet 20 of the present invention for a backlight, a display device 10 (LCD) having a wide viewing angle can be realized.

When the scattering length S is (R / 80) μm or more, the light diffusion characteristic (light shielding power) of the reflective layer 26 is low, and the above-mentioned effect cannot be exhibited well, so that unnecessary light leakage increases. As a result, collimated light having sufficient directivity cannot be obtained. On the other hand, the shorter the scattering length S is, the more advantageous in terms of the optical characteristics of the reflection layer 26.
m or less, for example, it is necessary to increase the amount of the light scattering substance in the reflective layer 26 and reduce the amount of the binder to which the beads 24 are adhered. Cannot be fixed to the surface, causing problems in mechanical strength and the like. The scattering length S is preferably “1 <S <(R / 160)”. Within this range, sufficient mechanical strength can be obtained and collimated light with higher directivity can be emitted, which is preferable.

The scattering length S is given by Kubelka
It can be calculated by a calculation method based on the theory of. Specifically, three or more film samples having the same composition as the reflective layer 26 and different thicknesses are prepared, and the thickness and transmittance of each film sample are measured. The transmittance may be measured with a spectrophotometer. The transmittance is measured by using the same collimated light (that is, the light source of the backlight unit 14 in the illustrated example). The thickness of the film sample is d [μm], and the scattering length S of the film sample is 1 / α [μ
m], the absorption length (average free distance until light is absorbed) of the film sample is 1 / β [μm], and the transmittance of the film sample is T [%]. Further, the light intensity distribution I at the depth Z
(Z) is replaced by the component i from the front to the back of the film sample.
(Z) and a component j (Z) going from the back to the front are considered separately. That is, “I (Z) = i (Z) + j (Z)”.

In such a system, the increase / decrease of the light intensity due to scattering / absorption in a film having a small thickness dz at an arbitrary depth Z of the film sample is determined by the following simultaneous differential equation (1) and the following differential equation according to Kubelka's theory. It can be calculated by solving (2). di / dz =-(β + α) i + αj (1) dj / dz = (β + α) j-αi (2)

In the above equation, “γ ² = β (β + 2
α) ”,“ ξ = (α + β−γ) / α ”,“ η = (α + β
+ Γ) / α ”and the integration constants are K and L, the general solution for the simultaneous equations i and j is as follows. i (Z) = Kexp (−γZ) + Lexp (γZ) j (Z) = Kξexp (−γZ) + Lηexp (γZ)

The transmittance T of a film sample having a thickness d is expressed as “T =
i (d) / i (0) ". At this time, when it is assumed that there is no returning light (i.e., j (d) = 0) when measuring the transmittance of the film sample alone, the transmittance T is expressed by the following equation as a function of the thickness d of the film sample. It can be shown in (3). T (d) = (η−ξ) / (ηexp (γZ) −ξexp (−γZ)) (3) Put the measured transmittance T and thickness d of each film sample into equation (3), By optimizing using the least square method or the like, the scattering length S = (1 / α) and the absorption length 1 / β can be obtained.

Here, the optical collimator sheet 20 of the present invention
In the state where the beads 24 are fixed, the scattering length S
May be difficult to measure. However, as is clear from the above calculation method, the scattering length S is a numerical value that does not depend on the thickness of the film (reflection layer 26). If the composition is the same, the scattering length S of the reflective layer 26 does not change whether the beads 24 are fixed or not. Therefore, in the optical collimator sheet 20 of the present invention, a film sample having the same composition as that of the reflecting layer 26 to be formed is prepared, and the scattering length S is calculated by the above-described method.
A scattering length S of 6 can be found.

As an example, when a manufacturing method described later is used, the same paint as that for forming the reflection layer 26 of the optical collimator sheet 20 is prepared, and this paint is applied to a substrate or the like in a sheet form. Then, a film sample is prepared by curing the same as the reflection layer 26 in the manufacture of the optical collimator sheet 20. By creating such a film sample, for example, by changing the coating thickness of the paint,
Film samples of three or more different thicknesses are prepared. By using this film sample and calculating the scattering length S by the above method, the reflection layer 2 of the optical collimator sheet 20 to be produced is obtained.
A scattering length S of 6 can be found.

As such a light reflecting layer 26, various materials can be used as long as the above conditions are satisfied. In a preferred embodiment, the beads 24 are
An example is a material in which fine particles of a light-scattering substance are dispersed in a binder (adhesive) fixed to the substrate.

The binder used for the light reflecting layer 26 is not particularly limited, and various binders can be used as long as the beads 24 can be fixed to the support sheet 22. For example, urethane resin, vinyl acetate resin, ethylene-vinyl acetate copolymer, vinyl chloride resin, vinyl chloride-vinylidene chloride copolymer, (meth) acrylate resin, butyral resin, silicone resin, polyester, vinylidene fluoride resin , Nitrocellulose resin, polystyrene,
Styrene-acrylic copolymers, polyethylene, polypropylene, polyethylene chloride, rosin derivatives, and mixtures thereof are preferably exemplified. In particular, urethane resin,
Acrylic resin and silicone resin are preferably used. In the present invention, it goes without saying that the binder may have various components contained in a normal binder such as a plasticizer, in addition to the adhesive component.

On the other hand, the light scattering substance used for the reflection layer 26 is not particularly limited, and various substances can be used as long as they do not absorb light emitted from the light source. Preferably, fine particles of a substance having a refractive index of 1.6 or more are preferred. Thus, efficient light diffusion (reflection) with little attenuation can be performed. Specifically, yttrium oxide (Y ₂ O
₃ ), zirconium oxide (ZrO ₂ ), gadolinium oxide (Gd
₂ O ₃ ), lanthanum oxide (La ₂ O ₃ ), hafnium oxide (Hf
One or more of fine particles such as O ₂ ), barium sulfate (BaSO ₄ ), alumina (Al ₂ O ₃ ), and titanium oxide (TiO ₂ ) are preferably exemplified. In particular, yttrium oxide, zirconium oxide, gadolinium oxide, lanthanum oxide, hafnium oxide, titanium oxide, and the like are preferable.

These fine particles are not spherical but have many irregularities on the surface. Therefore, a gap is formed between the contacting fine particles, and the binder does not flow into the gap, and there are many regions where air exists. for that reason,
A large difference in the refractive index between the air (refractive index 1) and the light scattering substance can be ensured, whereby the reflection layer 26
The attenuation of the light inside the housing 18 can be greatly reduced, and the light incident on the reflective layer 26 can be returned to the housing 18 or the like with high efficiency.

In the reflection layer 26, the scattering length S is
It can be adjusted by the type (particularly, refractive index) of the light scattering substance, the particle size of the light scattering substance, the content ratio between the binder and the light scattering substance, the porosity, and the like. Here, the particle size of the light scattering substance is not particularly limited. However, in order to suitably realize the scattering length S, for example, fine particles having a D50% particle diameter of 0.1 μm to 2 μm by a laser diffraction method are preferable. It is. Similarly, the amount ratio of the binder to the light scattering substance is not particularly limited, but considering the scattering length S and the adhesive force of the beads 24,
0.5: 1 to 2 by weight ratio of “light scattering material: binder”
It is preferably 0: 1. The binder also contains components such as a plasticizer.

The thickness (maximum thickness) of the reflection layer 26 is not particularly limited. However, in the optical collimator sheet 20 of the present invention, when the thickness of the reflective layer 26 is equal to or less than the scattering length S, a large amount of light (leakage light) passing through the reflective layer 26 is generated. Conversely, the beads 24 are more than half the reflective layer 26
When buried in the light, the light incident on the beads 24 is reflected by the reflection layer 26, and the efficiency is reduced. In consideration of the above, the thickness of the reflective layer 26 is set to a value equal to the scattering length S to half of the diameter R (S to 0.5R), particularly, 10 times the scattering length S to the diameter R.
(10S to 0.5R).

The method for manufacturing the optical collimator sheet 20 of the present invention is not particularly limited, but the following method is exemplified as a preferred embodiment. First, a predetermined amount of a binder is dissolved in an appropriate solvent, a predetermined amount of a light scattering substance is added to the solution, and the mixture is stirred to prepare a coating material in which the light scattering substance is dispersed. Then, after adjusting the viscosity as needed,
This paint is applied to the support sheet 22 at a predetermined thickness and dried to make the paint semi-cured. In this state, a sufficient amount of beads 2 is applied to the entire area of the support sheet 22 where the paint is applied.
Sprinkle 4 and press lightly to make it even. After the pressing, the beads 24 that have not adhered to the paint are removed by, for example, making the support sheet 22 slant. Thereafter, the remaining beads 24 (beads 24 attached to the paint) are pressed using a roller or the like, and are pressed into the paint until a part thereof comes into contact with the support sheet 22. Finally, the paint is dried (the binder is cured) to obtain the optical collimator sheet 20 of the present invention.

Although the optical collimator sheet of the present invention has been described in detail above, the present invention is not limited to the above-described embodiment, and various improvements and modifications may be made without departing from the gist of the present invention. Of course.

[0039]

Hereinafter, the present invention will be described in more detail with reference to specific examples of the present invention. [Example] Pandex T-5265HM (manufactured by Dainippon Ink and Chemicals), which is a urethane resin binder, was dissolved in a 1/1 solution of diacetone alcohol / methyl ethyl ketone.
A 13% by weight binder solution was prepared. To 200 g of the binder solution, 52 g of fine yttrium oxide powder (produced by Nippon Yttrium Co., Ltd.) was added, and the mixture was dispersed with a homogenizer to prepare a coating material for forming the reflective layer 26.
It should be noted that Dt of the yttrium oxide fine powder by a laser diffraction method was measured.
The 50% particle size is 1.4 μm, FSSS (Fisher sub-sieve).
The average particle size measured by a sizer (Fisher air permeation apparatus) is 0.4 μm.

After the viscosity of the paint was adjusted to 30 poise, the paint was filtered and defoamed, and applied to a 180 μm-thick polyethylene terephthalate support sheet 22 with a doctor blade (clearance 800 μm). After air drying for about 1 hour, the diameter R is about 800 μm (R / 80 = 10 μm).
m) glass beads 24 (Ohihara Hibee D
24, a refractive index of 1.595) was sprayed in a large amount over the entire area where the paint was applied, and was pressed so as to even out the entire area. After removing the beads 24 not adhering to the paint, the beads 24 were pressed from above by a rubber roller, and the beads 24 were pushed into the paint until they came into contact with the support sheet 22. Thereafter, the paint was completely dried (the binder was cured) to complete the optical collimator sheet (Inventive Example 1).

As a fine yttrium oxide powder (both manufactured by Nippon Yttrium Co., Ltd.),
0% particle size is 1.6 μm (average particle size by FSSS 0.4
μm), and an optical collimator sheet (Invention Example 2) having the same particle size as 2.5 μm (FS
An exactly similar optical collimator sheet (comparative example) was prepared except that an average particle size of 1.4 μm according to SS was used.

The scattering length S of each of the obtained optical collimator sheets
Was measured by the above-described method, and it was found that Inventive Example 1 was 4 μm,
Inventive Example 2 was 7 μm, and Comparative Example was 15 μm.

For each of the obtained optical collimator sheets,
The luminous intensity of the light emitted from the light source, incident from the support sheet 22 side, and passed through the optical collimator sheet was measured, and the angle (°) from the vertical direction at which the luminous intensity was の of the vertical direction was measured. The results are shown in Table 1 below.

[0044]

As shown in Table 1, when the scattering length S is "1 <
In the comparative example in which the optical collimator sheet exceeds “S <(R / 80)”, the angle from the vertical where the luminous intensity is １ ／ is 43 °.
It is. On the other hand, according to the optical collimator sheet of the present invention in which the scattering amount S satisfies the above condition, the angles are narrow as 17 ° and 33 °, and therefore, the light is favorably condensed and the reflection layer 26 is formed. It can be seen that the transmitted light is reduced to obtain a highly directional and high-brightness collimated light. From the above results, the effect of the present invention is clear.

[0046]

As described above in detail, according to the optical collimator sheet of the present invention, it is possible to appropriately collect the diffused light and obtain a collimated light having high directivity and high brightness. it can. Therefore, by using the optical collimator sheet of the present invention, in a LCD or the like in which the distance from the image forming surface to the screen is relatively short, when used together with a light diffusion screen or the like, a high-quality image with a wide viewing angle is displayed. can do.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view conceptually showing a display device using an optical collimator sheet of the present invention.

FIG. 2 is a conceptual diagram of an example of an optical collimator sheet of the present invention.

[Description of Reference Numerals] 10 display device 12 liquid crystal panel 14 backlight unit 18 housing 20 optical collimator sheet 22 support sheet 24 beads 26 reflection layer

Claims (2)

[Claims] 1. A transparent support, a number of light-transmitting spheres partially fixed to the support, and a scattering length S [μ
m] is such that 1 <S <(R / 80), and a reflecting layer that diffuses the incident light at a portion other than the contact portion between the support and the sphere or further near the contact portion. (In the above formula, R is the diameter [μm] of the sphere). 2. The light collimator sheet according to claim 1, wherein the reflection layer has a binder for fixing a sphere to the support, and a light scattering substance dispersed in the binder.