JPH06324330A - Light scattering and transmitting light source device - Google Patents

Abstract

PURPOSE:To provide the light scattering and transmitting device which is simple in construction and excellent in mass productivity and cost effectiveness and with which uniformly scattered light is obtainable. CONSTITUTION:This light scattering and transmitting light source device 1 has a light scattering and transmitting element 2, a reflection element 4 disposed on the rear surface side thereof and a light source 3. The element 2 is composed of light scattering and transmitting body block regions GAMMA1 and GAMMA2. The respective regions GAMMA1, GAMMA1 have effective scattering irradiation parameter values E1, E2 (E1>E2). The far and near effect from the light source is negated by the various intensities of scatterability if the light is made incident from the flank on the side where the ratio occupied by the region GAMMA2 having the weak scatterability is large. The scattered exit light having uniform intensity is thus obtd. The materials produced by a molding process including a kneading stage for different refractive index materials (polymer matrix + particulate material, different polymer blends, etc.) are used for the respective light scattering and transmitting body blocks. The angle characteristic of the scattered light intensity is changed if the front side or rear side of the light scattering and transmitting element is provided with a means for correcting the exit direction of the scattered light.

Description

Detailed Description of the Invention

[0001]

2. Description of the Related Art Conventionally, various types of optical elements or devices which emit light in a desired direction by utilizing a scattering phenomenon have been publicly known, and are used as a backlight light source for liquid crystal display devices. Is used for. One type of these known optical elements or devices is such that light is incident from the side of an extended plate-shaped transparent material, a reflecting element is arranged on one surface side, and a light diffusing property is provided near the other surface. A planar light source is provided to serve as a light emitting surface and is used as a backlight light source of a liquid crystal display device. For example, JP-A-62-
235905, JP-A-63-63083,
JP-A-2-13925 and JP-A-2-24578
This corresponds to that described in Japanese Patent Publication No. 7.

In the surface light source device using these light scattering guide devices, light scattering is not generated volumetrically inside the transparent body, and diffuse reflection or specular reflection near the surface of the transparent body or at a reflecting element occurs. Since it is only used to have a spread in the light emission direction, it was theoretically difficult to sufficiently increase the proportion of scattered light that can be extracted from the light scattering guide device.

Further, when it is attempted to obtain a planar light source device having a uniform illuminance by making light incident from the side, as will be easily understood from the examples shown in the above-mentioned respective publicly known documents, the reflecting element. It is necessary to have some kind of gradient in the reflectivity, etc., and the structure of the light-scattering light guide device portion becomes complicated and large, and the manufacturing cost must be increased.

Therefore, when this type of light-scattering light guide device is used for a backlight light source of a liquid crystal display device, there are demands for brightness, uniformity of illuminance as a planar light source, thin structure, economical efficiency and the like. I had to sacrifice some of them.

As a second type of known light-scattering light guide element or light source device, a light diffusing plate is constructed by dispersing a granular material having a refractive index different from that of the transparent material inside an extended transparent material in the form of a plate. There is something to do.

For example, JP-A-1-172801, JP-A-1-236257, and JP-A-1-269.
Those disclosed in Japanese Patent Application Laid-Open No. 901, Japanese Patent Application Laid-Open No. 2-221925 and Japanese Patent Application Laid-Open No. 4-145485 belong to this type.

Particularly, in the above-mentioned JP-A-2-221925 and JP-A-4-145485, light is incident from the side of the light guide plate, a reflecting element is arranged on one surface side, and the other surface is formed. It is disclosed that a light source such as a backlight of a liquid crystal display device is configured as a light emitting surface.

In these plate-shaped light guide elements, light scattering is volumetrically caused by the non-uniform refractive index generated by the granular material dispersed and mixed in the transparent body. In that sense, it can be said that the light diffusion efficiency can be improved as compared with the first type, but a light scattering guide of this type is incorporated as a light scattering guide. In the case of constructing, the following problems occur.

That is, as can be seen from the above-mentioned publicly known examples, the element itself has a light scattering ability and has a function of guiding light while scattering light, that is, a light scattering guide, and the light scattering guide. When a light-scattering light guide device is combined with a light source element that allows light to enter from the side of the body, the dispersion of particulate matter dispersed in the light-scattering light guide body with the intention of making the intensity of outgoing scattered light uniform. A density-gradient is provided, or a light scattering ink or the like is used on the back side of the light-scattering light guide to provide scattering reinforcing means in a mesh shape, a dot shape, or the like, and in some cases, the density of the mesh or dots. A gradient is being applied to.

That is, conventionally, the scattering ability is intentionally reduced in a portion near the light source, and the light scattering ability is maximized by including a mesh-like or dot-like reinforcing layer on the back side in a portion away from the light source. The idea and the idea of adding a reinforcing means such as a mesh-like or dot-like diffusion ink layer to the back surface area to maximize the light scattering ability have been adopted.

In the background to which such a technique has been widely used, in general, in a light scattering guide device of a normal size, the scattering reinforcing means in the back surface region of the light scattering guide is indispensable for securing the total scattered light amount. In addition to the background that it has been considered that the light scattering guide is constructed by dispersing modified refractive index particles in a matrix, the light scattering ability depending on the distance from the light source is somehow formed. It is a fact that there was a problem that illuminance reduction in the part far from the light source could not be avoided unless a gradient was given. In addition, as another form of this second type of technique, the shape of the light-scattering light guide body is formed into a wedge shape or a triangular shape without a gradient in the modified refractive index substance dispersion density itself in one light-scattering light guide body. It has been proposed to make a roof.

[0012] For example, in Japanese Patent Laid-Open No. 4-140783, a light scattering guide (milky white substrate) having a mountain-shaped cross section and a transparent substrate are combined in a complementary shape relationship (complementary relationship) to form one plate. A light-scattering light guide light source device having a structure in which members are formed and light sources are arranged on both sides is disclosed.

Also, the present inventors have already used two so-called cast-polymerization techniques to form two wedge-shaped light-scattering light guides, each having a different scattering power in which a substance having a different refractive index is uniformly dispersed in a polymer matrix. A light-scattering light-guiding light source device of a type in which light-scattering light-guiding elements are formed in a plate shape by combining bodies and light is incident from the side is proposed ("International Patent Application PCT
/ JP / 92/01230 (Priority date; September 27, 1991) "," Polymer Reprints, J
apan Vol. 41, No. 3; 1992 ",
Pp. 802 and "Polymer Reprints,
Japan Vol. 41, No. 7 1992
Years ", pp. 2945-2947).

[0014]

As described above, in the prior art, light is made incident from the side of the extended plate-shaped transparent material, the reflecting element is arranged on one surface side, and the vicinity of the other surface is arranged. It is difficult to increase the light utilization efficiency in a light scattering guide device of a type that is used as a backlight light source of a liquid crystal display device by configuring a planar light source that has a light diffusing property as a light emitting surface, Also, if you try to forcefully increase the illuminance on the light exit surface,
Various reinforcing means are required, which increases the thickness of the device and the manufacturing cost.

Further, in the type using this transparent plate, when a mesh-like or dot-like reinforcing layer is formed on the back surface side of the transparent plate for the purpose of reinforcing the scattering power and making the illuminance distribution uniform, the light emitting surface is When observing the light-scattering light guide device from the side, there arises an inconvenience that the mesh of the reinforcing layer and the pattern of dots can be seen through. In order to prevent this, a light-scattering film or the like is also arranged on the light emitting surface side.
The additional structure also causes light absorption, which is a factor of lowering the light utilization efficiency, and also becomes a cause of increasing the manufacturing cost due to the complicated device structure.

On the other hand, a light-scattering light-guiding light source device is formed by combining a light-scattering light-guiding body which itself has a light-scattering ability and a light source element which allows light to enter from the side of the light-scattering light-guiding body. A gradient is given to the dispersion concentration itself of the granular material dispersed in the light guide body, or a light-scattering reinforcing layer in a mesh shape, a dot shape or the like is formed by using a light-diffusing ink or the like on the back side of the light-scattering light guide body. Even when the measures such as providing the above are taken, the structure of the device becomes complicated and the manufacturing process becomes complicated due to the additional technical measures.
It was inevitable due to the disadvantages of sophistication.

That is, when a method of forming a mesh or dot-like reinforcing layer on the back surface of the light-scattering light guide and providing a gradient in the scattering power of the reinforcing layer is adopted as the scattering power gradient applying means, Alternatively, the distribution density of the dot pattern has to be given a predetermined gradient, which makes the manufacturing process more complicated than the case of forming a simple scattering reinforcing layer, which is obviously disadvantageous in terms of manufacturing cost.

Further, when the brightness of the light scattering and guiding light source device is made uniform by providing a gradient in the dispersion density of the modified refractive index substance dispersed in the polymer matrix, the dispersion density gradient as intended is obtained. It is not always industrially easy to manufacture a light-scattering light guide having the above-mentioned characteristics, and it cannot be said that the technology is suitable for mass production.

Further, in the one disclosed in Japanese Patent Laid-Open No. 4-140783, only the light-scattering light guide (milky white substrate) portion having a mountain-shaped cross section contributes to the scattering, and the remaining transparent substrate portion is volumetric. Scattering does not occur. Therefore, there is a basic problem that the scattering efficiency becomes low as a whole when the thickness of the plate-shaped element is constant, and the means for providing the scattering power gradient is limited to only the mountain-shaped section. When the average scattering power of the whole is determined, the size of the scattering power gradient is also determined unless the shape is changed, which is a constraint in manufacturing the light scattering guide device of various characteristics using a specific material. .

With respect to the technique proposed by the present inventors in the above-mentioned report, the entire element is provided by giving a selected scattering ability to each of the two elements constituting the plate-like element while providing the scattering ability to each of the two elements. It can be said that this is a technology that can provide a light-scattering light guide light source device having a characteristic that the scattering efficiency is good and the average scattering power and the scattering gradient can be set relatively freely because the scattering power gradient is generated.

However, at the time of the above proposal, as described in the above-mentioned reports and specifications, cast polymerization is used as a method for producing each wedge-shaped light-scattering light guide, and mass production is not possible. From the point of view, it must be said that there was the same problem as in the case of the conventional technique in which the gradient of the modified refractive index dispersion density in the light scattering guide is provided.

The present invention avoids problems such as complication, size increase and lack of suitability for mass production, which are obstacles to any of these conventional techniques, and emits uniform and bright scattered light with an extremely simple structure. It is intended to provide a light-scattering light guide light source device which has a surface and is also suitable for mass production.

[0023]

According to the present invention, first, a shape complementary to each other, which is given a light scattering ability by being molded through a kneading step of at least two materials having different refractive indexes from each other, is formed. A plate-like light-scattering light guide element including at least two light-scattering light-guide block areas Γi (i = 1,2, ...) and light is incident from the side of the plate-like light scatterer light guide element. And at least one light incidence means capable of controlling the scattering power of each light scattering guide block region Γi is represented by an effective scattering irradiation parameter value Ei (i = 1,2, ...). , Each effective scattered irradiation parameter value Ei (i = 1,2, ...
) Is not equal to any other effective scattering irradiation parameter value, and the average value Eav of the effective scattering irradiation parameter on the cross section in the thickness direction of the plate-like light scattering guide is A light-scattering light guide light source device, which is relatively small in a portion relatively close to the light incidence means and relatively large in a portion relatively far from the light incidence means, has a basic configuration for solving the above-mentioned problems. It is provided (configuration according to claim 1).

Further, in the present invention, the value of the effective scattering irradiation parameter Ei (i = 1,2, ...) Of each light scattering guide block region is 0.0001 on the basis of the above basic structure.
Correlation function γi (r) of a non-uniform refractive index structure in the range of [cm ^-1 ] ≤ Ei ≤ 1000 [cm ^-1 ] and causing the scattering ability in each light scattering guide block region Γi.
Is an approximate expression, γi (r) = exp [−r / ai], (where r is the distance between two points in the light scattering guide block region Γi).
The range of the correlation distance a i expressed by is 0.005 μm ≦
By imposing the condition of ai ≦ 50 μm, the effectiveness when applied to a backlight light source or the like is further ensured (configuration according to claim 2).

Further, the present invention includes a polymer matrix as a material constituting each light-scattering light guide block region, and a particulate material dispersed and contained in the polymer matrix through a molding process including a kneading step, By using a material in which the refractive index of the particulate material and the refractive index of the polymer matrix are different by at least 0.001 or more, the light scattering and guiding light source device having each of the above configurations is It is given a general proof (configuration according to claim 3).

In the present invention, at least one of the light-scattering light guide block regions Γi is made of a material formed by a molding process including a kneading step of at least two kinds of polymers, and the at least two kinds of polymers are Regarding the refractive index, by imposing a condition that the difference between the maximum refractive index and the minimum refractive index is at least 0.001 or more, the light scattering and guiding light source device having each of the above configurations is generally supported in a different form from the material side. Is given (Claim 5
Configuration described in).

In the light-scattering light-guide light source device having each of the above-described configurations, the present invention provides an injection molding process for the purpose of providing conditions for more surely ensuring mass-production suitability in the manufacturing process of each light-scattering light-guide block region. Alternatively, it imposes a requirement that it is formed by a process including an extrusion step (apparatus according to claim 5 or claim 6).

In the present invention, on the premise of each of these configurations, the light-scattering light-guiding means is provided with a light-exiting direction correcting means for correcting the light-exiting direction by facing the front surface area or the back surface area of the light-scattering light-guiding element. By providing the element integrally or separately, the angle characteristic of the intensity of the scattered light emitted can be corrected.

[0029]

The operation of each of the light-scattering light guide light source devices of the present invention outlined above will be described in more detail, focusing on the operation. First, in claim 1 and claim 2, regarding the scattering irradiation parameter E and the correlation distance a used to numerically limit the light scattering power of each light scattering light guide block region,
The Debye theory will be cited and explained.

When light of intensity I 0 is transmitted through the medium by y (cm) and the intensity is attenuated to I due to scattering during the period, the effective scattering irradiation parameter E is defined by the following equation (1) or (2).

[0031]

[Equation 1] The expressions (1) and (2) are expressions of so-called integral type and differential type, respectively, and their physical meanings are equivalent. In addition, this E
Is sometimes called turbidity.

On the other hand, the scattered light intensity when light scattering occurs due to the non-uniform structure distributed in the medium is such that in the normal case where most of the emitted light is vertically polarized light with respect to the vertically polarized incident light (VV
Scattering) is expressed by the following equation (3).

[0033]

[Equation 2] It is known that, when natural light is incident, the following equation obtained by multiplying the right side of equation (3) by (1 + cos θ ² ) may be considered in consideration of Hh scattering.

[0034]

[Equation 3] Where λ0 is the wavelength of the incident light, ν = (2πn) / λ0,
s = 2sin (θ / 2), n is the refractive index of the medium, θ is the scattering angle, <η ² > is the mean square of the dielectric constant fluctuation in the medium (hereinafter,
<Η ² > = τ, and τ is appropriately used. ), And γ
(R) is called a correlation function.

According to Debye, when the non-uniform refractive index structure of the medium has an interface and is divided into A phase and B phase and dispersed, the correlation function γ (r) with respect to the fluctuation of the dielectric constant,
The correlation distance a, the dielectric constant fluctuation root mean square τ, and the like are expressed by the following relational expressions.

[0036]

[Equation 4] Assuming that the non-uniform structure is composed of spherical interfaces of radius R, the correlation distance a is expressed by the following equation.

[0037]

[Equation 5] Using the equation (6) for the correlation function γ (r), the equation (5)
The effective scattering irradiation parameter E when the natural light is made incident on the medium is calculated based on the above, and the result is as follows.

[0038]

[Equation 6] From the relationship described above, it is possible to control the scattered light intensity, the angle dependence of the scattered light intensity, and the effective scattered irradiation parameter E by changing the correlation distance a and the dielectric constant fluctuation root mean square τ. I understand. Needless to say, the angle dependence of the scattered light intensity can be considered when the light scattering guide of the present invention is applied to an actual illumination device or the like.

[0039] Figure 1 is a correlation in the horizontal axis distance a, the curve of the vertical axis of the square mean τ permittivity fluctuations effective scattering illumination parameter E E = 50 ^[cm-1] and E = 100 [cm ^{over 1} ] is an example.

Generally, the larger E is, the larger the scattering power is,
If E is small, the scattering power is small, in other words, it becomes almost transparent. E = 0 corresponds to no scattering.

Therefore, in general, in order to realize a uniform illuminance surface light source having a relatively large area, the value of E is set to be small.
It would be good if light scattering is caused in a wide range.

To give a tentative guide, for example, E = 0.
If it is about 0001 [cm ^-1 ], the light-scattering light guide can be illuminated comparatively uniformly in the range up to several tens of meters. Also,
If it is about E = 100 [cm ^-1 ] shown in FIG.
It is suitable for intensive and uniform illumination of the range of m.

In the case of E = 50 [cm ^-1 ] in FIG. 1, intermediate sizes (for example, several cm to several tens of c) are used.
It is considered to be suitable for making the light-scattering light guide body of m) illuminate uniformly.

However, the values of these effective scattered irradiation parameters E are just a guideline, and the scattered light reinforcement or the scattered light reinforcement depending on the specific usage conditions of the application device, for example, the intensity of the primary light source and the optical elements arranged in the periphery. It is preferable to flexibly select in consideration of the attenuation factor and the like. If the angle characteristic of light scattering is special, a value of E = 1000 or more may be selected.

For the correlation distance a, 0.005 μ
Although it is considered that the thickness is practically about m to 50 μm, it is preferable to set it in consideration of required angle characteristics and the like in each case.

By handling the scattering phenomenon as described above, the scattering characteristics of the light scattering guide can be determined in such a manner as to specify the range of the scattering irradiation parameter E and the correlation distance a. The light-scattering light guide device described in claims 1 and 2 specifies the scattering characteristics of each light-scattering light guide block region incorporated therein based on such an idea.

Based on the above description regarding the effective scattering irradiation parameter E or the correlation distance a, the operation of the light scattering guide light source device according to claim 1 which defines the basic configuration of the present invention will be further described. FIG. 2 schematically shows, in the form of a sectional view, the simplest configuration of the light-scattering light guide light source device according to the present invention. To explain this, the light-scattering light guide light source device generally shown by the number 1 has a light-scattering light guide element 2 and a reflection provided on the back surface (surface opposite to the scattered light extraction surface) side thereof. It is composed of an element 4 and a light source element 3 which allows light to enter from the side of the light scattering guide element 2. Arranging the reflective element 4 on the back surface side of the light-scattering light-guiding element itself belongs to a known technique for preventing wasteful escape of light and is not essential to the technical idea of the present invention. When configuring the light scattering light guide light source device according to the invention,
It is preferable to arrange an ordinary mirror plate or a white diffuser plate as the reflecting element 4.

Further, this reflecting element 4 is a light scattering light guide element 2.
It is only necessary to form it separately from the above, and it is also one of the advantages of the present invention that there is no need to form the mesh-like or dot-like pattern in the above-described conventional technique separately or in the light-scattering light guide element body.

The light-scattering light guide element 2 is composed of two light-scattering light guide block areas Γ 1 and Γ 2 having complementary shapes, and effective scattering irradiation parameters E 1 and E 2 representing the scattering power of each block area. For the value of, E1> E2
The material is selected so that As shown in the graph in FIG. 2, the x-axis and the y-axis are set in the light incident direction and the thickness direction of the light-scattering light guide element 2, and the light incident end side surface is x =
Considering the average effective scattered irradiation parameter Eav (x) on the cross section in the thickness direction at each position x as the 0 plane,
The following expression (13) is established.

Eav (x) = E2 + [(E1−E2) / L] x (13) Here, L is the length measured along the light incident direction of the light scattering guide element 2 (hereinafter , Simply referred to as the “length” of the light-scattering light guide element.) E1> E2, so Eav
The value of increases gradually from the light-incident side of the light-scattering light-guiding element 2 toward the opposite side surface. On the other hand, x =
The light that entered from the side of 0 repeatedly scatters and x
As the light propagates in the axial direction, the scattered light emitted from the scattered light extraction surface (upper surface) and attenuated in the form of absorption loss inside the light-scattering light guide element main body or on the surface of the reflecting element 4 are included in the light-scattering light guide element. Energy density ρ at position x
(X) decreases with the x value. The intensity of scattered light emitted from the position x on the upper surface of the light scattering light guide element is the product of the two, Eav
Since it is almost proportional to (x) · ρ (x), an increasing function E of x
The av (x) and the decreasing function ρ (x) cancel each other out so that the brightness of the light scattering guide element 2 becomes uniform as a whole.

As can be seen from the above formula (13), the smaller the length L of the light-scattering light guide element 2 and the larger the difference ΔE = E1−E2 of the effective scattering irradiation parameters, Eav
The gradient of (x) becomes large. Therefore, if ΔE is appropriately selected, the same effective scattering irradiation parameter gradient Eav (x) can be realized for the light scattering guide elements 2 having various lengths L. It is also possible to change the magnitude of (E1 + E2) / 2, which is a measure of the average scattering power of the entire device, while keeping the condition of giving the same ΔE. Since the technique disclosed in the above-mentioned Japanese Patent Laid-Open No. 4-140783 does not show the technical idea of combining block regions having non-zero scattering power,
We cannot expect such freedom of choice.

By the way, as described in the section of the description of the prior art, although the present inventors have already reported such an idea, the problem of poor productivity remains unsolved. there were.

Therefore, in the present invention, the origin of the scattering ability of the material forming the light-scattering light guide block area is determined in the "kneading step". That is, generally, the light-scattering light guide block molded through a step including a kneading step of mixing and kneading a plurality of transparent materials having different refractive indexes,
Focusing on the fact that the block has a certain scattering ability regardless of the shape, the above-mentioned problem of productivity is solved, and a combination of complementary shapes of each block and the entire light-scattering light guide element are configured. The number of blocks to be played can be freely varied.

In contrast to FIG. 2 showing the most basic structure of the light scattering guide light source device according to the present invention, FIG.
(5) and FIGS. 4 (1) and 4 (2) simply illustrate how to take a combination of complementary shapes of the blocks.

First, FIGS. 3 (1) to 3 (5) show an example in which the effective scattering irradiation parameter average value Eav is changed only in one length direction of the light scattering guide element.
The incident direction of light is indicated by an arrow, and only the example of (1) belongs to the system in which light is incident from one side, and in (2) to (5), light is incident from both left and right directions on the paper surface. Is assumed. The number of block areas is (1),
There are two in (3) and (5), three in (2),
In (4), the number is 5. In (4), three kinds of values E1, E2, and E3 are used as the refractive index of each light-scattering light guide block area.
Has been adopted. Then, regarding these values, E3 <E
The materials are selected so that the relationship of 2 <E1 holds.

Further, in (5), the effective scattering irradiation parameter E is stepwise toward the center of the light scattering guide element.
An example of increasing the thickness of the block portion with 1 is shown. According to this configuration method, each light-scattering light guide block does not need a slope or a curved surface, which may be advantageous for simplifying the molding process.

Next, in FIGS. 4 (1) and 4 (2), the two-dimensional effective scattering irradiation parameter average value E in the light scattering guide element is shown.
An example is given which gives the distribution of av. In FIG. 4 (1), the entire light-scattering light guide element has a rectangular parallelepiped shape. A light-scattering light guide block area having an effective scattering irradiation parameter E1 is formed in a pyramid shape (quadrangular pyramid shape) having a point P0 as an apex from the central bottom surface P5 P6 P7 P8 upward. As a light scattering light guide block area having a complementary shape to this, an effective scattering irradiation parameter E2 (E2 <E1
) With four light-scattering light guide block areas P0 P1
P2 P5 P6 and the like (however, it is possible to combine them to produce one block area P1 P2 P3 P4 -P5 P6 P7 P8 -P0) are also prepared.

Light incidence in this case is carried out from four directions as shown by arrows. It is easy to see that the ratio of the highly effective scattered irradiation parameter block area is the maximum (= 1) at the point P0, corresponding to the fact that the vicinity of the center P0 of the light scattering light guide element is farthest from each light source. Will be understood.

FIG. 4 (2) shows an arrangement example when a circular uniform scattered light source device is required. In this example, as the block area having the high effective scattered irradiation parameter E1, a cone-shaped block area Q1 Q2 is formed instead of the pyramid-shaped block area in FIG. 4A, and the shape of the entire light-scattering light guide element is formed. Is a disk or a column. As a light incident light source used in combination with this arrangement, it is usually considered advantageous to select an arc-shaped light source from the viewpoints of ensuring the uniformity of illuminance and light utilization efficiency.

When the various block shapes and arrangements illustrated in FIGS. 3 and 4 are to be manufactured with high industrial productivity, various shapes of light scattering light guides in which the effective scattering irradiation parameter values are controlled are provided. The body block must be formed. In the present invention, in order to satisfy such a condition, one light-scattering light-guiding element is configured by combining the light-scattering light-guiding member block regions that have been molded and processed through the kneading step of the modified refractive index material. .

As a combination of materials to be kneaded, there are 2
One type is possible. That is, as described in claim 4, the first mold is one in which a particulate material having a modified refractive index is dispersed in a polymer matrix by kneading, and the second mold is one in which
As described in claim 5, the polymers having different refractive indices are kneaded together. Whichever type is adopted, if there is a non-zero refractive index difference between the kneading materials, it theoretically functions as a light-scattering light guide. As a practical value in consideration of the application of, the condition that the difference between the maximum refractive index and the minimum refractive index is 0.001 or more is set (see claims 3 and 4).

Typical examples of the polymer matrix material used in the first type are PMMA (polymethylmethacrylate), PSt (polystyrene) and P
Although there are C (polycarbonate) and the like, in principle, it is possible to use any of the polymer materials described in Tables 1 and 2 including these. These materials are usually used alone as a polymer matrix,
A plurality of types may be mixed and kneaded with the particulate matter. In that case, since the modified refractive index polymer is blended, the second type character is naturally imparted.

The particulate matter dispersed in the polymer matrix made of these polymer materials has a refractive index different from that of the polymer matrix and is stably present in the polymer matrix material (no elution or modification phenomenon occurs). What can be used may be appropriately used. For example, silicon-based resin powder (for example, manufactured by Toshiba Silicon, which is commercially available under the trade name Tospearl) and crosslinked particles using various organic materials as raw materials can be used. As can be seen from the form of the equation (9), the correlation distance a and the particle size R are in a proportional relationship under the condition that the volume fraction of the particle material in the matrix is constant. Therefore, it is preferable to select the particle size of the particulate material to be used in consideration of this relationship. The typical particle size used is 0.1 μm to 10 μm.
About μm is possible.

The second type of technique utilizes a process called a polymer blend in which two or more kinds of polymers are kneaded as described in claim 4, and the present inventor proposes a method disclosed in Japanese Patent Application No. The technology proposed in No. 341589 is applied.

That is, two or more kinds of polymer materials having different refractive indexes (arbitrary shapes may be used; industrially, for example, pellets are conceivable.) Are mixed and heated, and kneaded to obtain light scattering. The original material of the light guide can be obtained (kneading step). By selecting the combination of polymer materials to be blended and the blending ratio, it is possible to have various values of the effective scattering irradiation parameter E and the correlation distance a. These raw materials are molded into a light-scattering light guide block having a desired complementary shape through an appropriate process,
If integrated into one light-scattering light guide body by an appropriate means (for example, adhesion with a transparent adhesive, fixing using a reflection foil covering the non-light-incident surface of the light-scattering light guide element), the invention of the present application can be realized. A light-scattering light guide element for use in the light-scattering light guide light source device is obtained.

The materials that can be used for the polymer blend are extremely diverse, and representative ones are listed in Tables 1 and 2 below. Since a very wide range of combinations and mixing ratios of these polymer blends can be selected, the refractive index difference, the strength and properties of the refractive index non-uniform structure generated in the molding process (scattering irradiation parameter E, correlation distance a, dielectric constant) It is preferable to make a selection that matches the purpose by taking account of the fluctuation root mean square τ).

[0067]

[Table 1]

[0068]

[Table 2] Any molding technique may be used to mold the kneaded material of the first mold or the second mold into blocks.
Considering mass productivity and economical efficiency, it is considered most practical to use so-called injection molding technology as described in claim 5. That is, a mold having a desired complementary shape is prepared, and a raw material obtained by kneading a molding machine polymer and a granular substance or polymers is injected into the molding machine mold in a molten liquid state by high-pressure injection, and then cooled and solidified. After that, if the molded product is taken out of the mold, a light-scattering light guide block having a shape corresponding to the shape of the mold can be obtained. For example, in the case of manufacturing the light-scattering light-guiding element of the type shown in FIG. 3 (1), at least one wedge-shaped mold may be prepared, and in the case of FIG. 3 (2), a mountain-shaped mold is used. It is sufficient to prepare a right-angled triangle die.

Not only when the insoluble particulate matter is mixed with the polymer but also when the polymers are blended with each other, the different polymers are cooled and solidified through the injection molding process without being completely and uniformly fused. Therefore, it is immobilized while leaving non-uniformity (fluctuation) in the local concentration of each polymer. Therefore, if there is a substantial difference in refractive index between the polymers to be kneaded, a light scattering guide having a non-uniform refractive index structure will be manufactured.

Further, depending on the shape and size of the light-scattering light guide block, an extrusion molding technique, which is known as a molding method excellent in production efficiency along with injection molding, is applied, and the light scattering according to claim 6 is applied. In some cases, it may be advantageous to construct a light guide light source device. For example, in the case of manufacturing a light-scattering light guide element having a thin strip-like cross-sectional structure as shown in FIG. 3 (1), the kneaded molten material is placed in the cylinder of an extruder equipped with a right-angled triangular extrusion port. Of the light source device, and a long light-scattering light guide body is manufactured in a usual manner, and is cut into a length corresponding to the depth length of the light source device (dimension in the direction perpendicular to the paper surface in FIG. 3). A light-scattering light guide strip-shaped block can be obtained.

Next, the structure described in claim 7 is applied to Japanese Patent Application No. 4-341589 or Japanese Patent Application No.
This is equivalent to applying the scattered light emission direction correction means described in each specification of -355073 to each light scattering light guide light source device described in claims 1 to 6. Less than,
This will be briefly described.

For example, in a liquid crystal display device or the like, since the display surface is generally observed from a fan-shaped space area centered on the front direction, a light scattering light guide light source used for a backlight light source. The scattered light emitted from the device is desired to be strongly distributed in an appropriate angular range centered on the direction perpendicular to the light extraction surface. By using the scattered light emitting direction correcting means, it is possible to surely meet such a demand.

FIG. 5 shows an example in which a separate scattered light emitting direction correcting element is provided on the scattered emitting light extraction surface side of the light scattering guide element of the type shown in FIG. 3 (2). The light guide element 11 is composed of a mountain-shaped high scattering power region having an effective scattering irradiation parameter E1 and two low scattering power regions having an effective scattering irradiation parameter E2 that complements the region to form a plate. Light sources (fluorescent lamps) 12 are arranged on both sides of the light-scattering light guide element 11, and a scattered-light emission direction correction element 14 is provided on the scattered-light extraction surface 15 side. The back surface 16 of the light-scattering light guide 11 is an optically open surface, and the main body of the light-scattering light-guide element 11 is not subjected to light-scattering reinforcement processing such as a light-diffusing ink pattern or a concavo-convex diffusing surface. A reflector (white film plate) 13 that is a separate body from the light-scattering light guide element 11 is disposed so as to face the back surface 16.

As the scattered light emission direction correction element 14, here, a thin plate or sheet-like element in which a large number of rows of prism regions are formed as shown in the figure is used. The scattered light emission direction correction element 14 has a function of correcting the light emitted from the light scattering guide element 11 in an oblique direction to the upward direction by refraction. The specific shape of the scattered light emission direction correction element is not limited to that shown in the figure, and any type may be used. For example, a film in which protrusions having a triangular pyramid shape or a dome shape are distributed, a plate-shaped element having columnar convex portions having a semicylindrical cross section, and the like are conceivable.

The undulating surface that causes the refraction action is usually
The one on the upper side (the side farther from the light-scattering light guide 1) is used, but the light-scattering light-guide can be used if the light emitted from the light-scattering light-guide 1 in an oblique direction is corrected to a direction directly above. Element 11
You may use the type which has an undulating surface on the side facing. The direction in which the scattered light emission direction correction means enhances the scattered light emission light intensity is not necessarily the front direction of the light scattering light guide element, and the scattered emission light in the oblique direction is strengthened by selecting the prism angle. It is not necessary to explain what you can do.

FIG. 6 shows a light-scattering light-guide element 21 of the type shown in FIG.
The columnar prism surface regions 22 are provided as the scattered light emission direction correction element means integrated with the above. The shape of each area of the effective scattering irradiation parameters E1 and E2 is as shown in the figure. The function of the columnar prism surface region 22 is similar to the function of the scattered light emission direction correction element 14 in FIG. In FIG. 6, 24 is a reflector (white film plate) that is separate from the light-scattering light guide element 21, and 25 is a light source (fluorescent lamp) arranged on both sides of the light-scattering light guide element 11. is there.

Further, FIG. 7 shows two light sources (fluorescent lamps) 35.
A columnar prism surface area 33 is provided on the surface of the light-scattering light-guiding element 31 opposite to the surface from which the scattered-light emitting light is taken out as a scattered-light emitting-direction correcting element means integrated with the light-scattering light-guiding element 31. is there. Arranging the reflectors 34 to face each other is the same as in the case of FIG. 5 or FIG. The shape of each region of the effective scattering irradiation parameters E1 and E2 is the one shown in FIG. 3 (3) upside down. This row-shaped prism surface area 3
The action of 2 is a little more complicated than the scattered light emission direction correction means 14 and 22 shown in FIG. 5 or FIG. 6, so that the pitch of the prism, the apex angle, the depth of the unevenness, etc., which realizes the optimum scattered light direction correction, etc. It is practicable to determine about by adopting an experimental method. It should be noted that the prism unevenness void portion indicated by 33 may be an air layer.

Specific methods for forming the concavo-convex area on the front surface area or the back surface area of the light-scattering light-guiding element body include a method of forming a predetermined shape on a mold or an extrusion port used for injection molding or extrusion molding, press working. Method, a method by mechanical processing such as cutting, a method by a chemical processing process such as various etching, etc. are conceivable. What means is used to form the concavo-convex region is particularly within the technical scope of the present invention. Is not a matter that has a restrictive effect on.

Further, it is possible to employ various combinations of the types of the scattered light emitting direction correcting means and the type of the light scattering guide element as described above, sizes, etc., all of which are technical aspects of the present invention. It does not deviate from the range.

[0080]

EXAMPLES Some specific examples will be described below. <Example 1> 0.3 wt% of methacrylic resin pellets (Asahi Kasei, Delvet 80N) with 3 μm particle size silicon resin powder (Toshiba Silicon, Tospearl 130)
After adding and mixing and dispersing with a mixer, it was extruded into a strand shape with an extruder and pelletized with a pelletizer to prepare pellets in which the silicone resin powder was uniformly dispersed.

The pellets were molded using an injection molding machine under the conditions of a cylinder temperature of 230 ° C. to 260 ° C. and a mold temperature of 50 ° C., having a length of 80 mm and a width of 100 mm, and a thickness in the long side direction. A light-scattering light guide block having a wedge shape that linearly changes from 1 mm (the thinnest part) to 3 mm (the thickest part) was produced, and was designated as a light-scattering light guide block Γ 1.

A methacrylic resin pellet (Asahi Kasei Corp., Delvet 80N) to which 0.01 wt% of a silicon-based resin powder having a particle size of 3 μm (Toshiba Silicon, Tospar 130) was added was used, and a vertical process was performed by the same process.
mm, width 100 mm, thickness is 1 along the long side direction
A wedge-shaped light-scattering light guide block that linearly changes from mm (the thinnest part) to 3 mm (the thickest part) was obtained. This is referred to as a light scattering guide block Γ 2.

The inclined surfaces of the two wedge-shaped light-scattering light guide blocks Γ 1 and Γ 2 having these complementary shapes are closely fixed to each other to form one plate-like light-scattering light guide element, which is shown in FIG. The light-scattering light guide light source device is configured in this manner.

This wedge-shaped block area portion This light scattering guide element belongs to the type shown in FIG. 2, and the light source is arranged on one side of the light scattering guide element 41 (side with weak scattering ability).
The surface of the reflection plate 43 arranged on the back side of the light scattering guide 41 is a mirror surface. In the block area Γ 1,
Since the granular material that is the scattering center is dispersed at a higher density than the block region Γ2, both block regions Γ1 and Γ2
Effective scattering irradiation parameters E1 and E2 of E1>
E2 is established. Therefore, as described in the related description of FIG. 2, the light scattering guide element 41 as a whole has an average effective scattering irradiation in the thickness direction from the end portion closer to the light source 42 to the far end portion. A structure in which the parameter value Eav is gradually increased is realized, and the configuration of FIG. 8 in which light is incident from the side surface having the smaller Eav value achieves uniform illuminance in the light scattering guide light source device. It should be.

In order to confirm this, the intensity of scattered outgoing light was observed from the direction of arrow VD using a video camera and an intensity display device, and it was found that the entire light extraction surface of the light scattering guide element 41 was the brightest. The light intensity difference between the dark and darkest areas was only about 5%. That is, the contrast ratio is 9
It was confirmed that a light-scattering light guide light source device having an extremely high brightness uniformity of 5% was obtained.

Example 2 Polymethylmethacrylate (PMMA) with 0.4% by weight of polystyrene (PSt)
Add and mix for 10 minutes using a V tumbler, then 5 minutes using a Henschel mixer. This is diameter 30
The pellets were prepared by melting and mixing under the conditions of a cylinder temperature of 220 ° C. to 250 ° C., a screw rotation speed of 75 rpm, and a discharge rate of 6 kg / hr using a 2-mm extruder (manufactured by Nakatani Machinery Co., Ltd.).

Using an injection molding machine, the pellets were heated at a cylinder temperature of 220 ° C. to 250 ° C., a mold temperature of 65 ° C., an injection speed of medium speed, an injection pressure of a short shot pressure plus 10 k.
Molded under the conditions of g / cm ² , length and width 80 mm, width 100
mm, thickness is from 1 mm (thinnest part) to 3 along the long side direction
A wedge-shaped light-scattering light guide block that changes linearly up to mm (the thickest part) was produced and was designated as a light-scattering light guide block Γ1 ′.

Polymethyl methacrylate (PMMA) added with 0.01 wt% of polystyrene (PSt) was used, and the same process was used to obtain a length of 80 mm and a width of 10
A wedge-shaped light-scattering light guide block having a length of 0 mm and a thickness linearly varying from 1 mm (the thinnest portion) to 3 mm (the thickest portion) along the long side direction was obtained. This was designated as a light scattering guide block Γ2 ′.

The slant surfaces of the two wedge-shaped light-scattering light guide blocks Γ1 'and Γ2' having these complementary shapes are closely fixed to each other to form a single plate-like light-scattering light guide element. The light-scattering light guide light source device is configured in the same arrangement relationship as the example shown in FIG.

This wedge-shaped block area portion This light scattering guide element also belongs to the type shown in FIG. 2, and E1 '>E2' holds for the effective scattering irradiation parameters E1 ', E2' of the block area Γ1 '. To do. Therefore, also in this case, a structure in which the average effective scattering irradiation parameter value Eav in the thickness direction is gradually increased from the end portion closer to the light source to the end portion farther from the light source is realized as the entire light scattering guide element. Will be there. Therefore, similar to the case of the example <1>, the scattered emission light intensity should be made uniform over the entire scattered light extraction surface.

In order to confirm this, the same observation as in Example <1> was carried out from the direction of arrow VD using a video camera and an intensity display device. As a result, the entire light extraction surface of the light scattering guide element was observed. An extremely high brightness uniformity of 90% light / dark ratio was observed.

[0092]

According to the present invention, a light-scattering light guide which is simple and easy to manufacture and which has a very simple structure and which has a uniform and bright light-exiting surface, avoids the complication and size increase of the device, which is difficult to avoid by the prior art. A device is provided. Further, according to the present invention, by using the scattered light emission direction correction element, a light scattering guide device suitable for observation or the like from a specific direction is realized. In particular,
INDUSTRIAL APPLICABILITY The present invention uses a block-shaped light-scattering light guide whose scattering power is given by a kneading process that can be reasonably incorporated into a plastic material molding process such as injection molding or extrusion molding. A wide range of materials and shapes of body blocks can be selected, and a light-scattering light guide light source device excellent in mass productivity and economical efficiency can be realized.

Since the light-scattering light guide light source device of the present invention has such basic features, it is a backlight light source device for various displays such as a liquid crystal display device, a backlight light source for automobiles, etc. By applying to a planar light source of various sizes in various illumination systems using light or a normal illumination light source, it exhibits its usefulness in a wide range of optical fields.

[Brief description of drawings]

FIG. 1 shows a curve of effective scattered irradiation parameter E at E = 50 [cm ⁻¹ ] and E = 100 [, with a horizontal axis representing a correlation distance a and a vertical axis representing a mean square of dielectric constant τ = <η ² >. cm ^-1 ] The figure drawn for the case.

FIG. 2 is a sectional view schematically showing the simplest configuration of the light-scattering light guide light source device according to the present invention.

FIG. 3 is a diagram exemplifying how to take a combination of complementary shapes of the respective light scattering light guide block regions forming the light scattering light guide element used in the light scattering light guide light source device of the present invention.

FIG. 4 is a diagram showing another example of how to take a combination of complementary shapes of the respective light-scattering light guide block regions forming the light-scattering light guide element used in the light-scattering light guide light source device of the present invention. .

FIG. 5 is a diagram showing an example in which a separate scattered light emission direction correction element is provided on the scattered emission light extraction surface side of the light scattering guide element of the type shown in FIG. 3 (2).

FIG. 6 is a diagram showing a configuration of a light-scattering light-guide light source device in which, for the light-scattering light-guide element of the type shown in FIG. 3 (3), a column-shaped prism surface region is provided on the scattered emission light extraction surface.

FIG. 7 is a diagram showing a configuration of a light-scattering light-guiding light source device in which a column-shaped prism surface region is provided on a surface of the light-scattering light-guiding element opposite to a surface from which scattered light is emitted.

FIG. 8 is a view for explaining the arrangement of a light source device incorporating the light-scattering light guide element manufactured in Examples <1> and <2> of the present invention.

[Explanation of symbols]

1, 10 Light-scattering light guide light source device 2, 11, 21, 31 Light-scattering light guide element 3, 12, 25, 35 Light source (fluorescent lamp) 4, 13, 24, 34 Reflector plate 5 Scattered outgoing light extraction surface 6 Light Back surface of scattering light guide (optically open surface) 14 Scattered emission light direction correction element 15 Scattered light extraction surface 16 Light scattering light guide element back surface 22, 32 Row-shaped prism surface 33 Void portion Γ1 Effective scattering irradiation parameter E1 Light-scattering light guide block area having Γ2 Light-scattering light guide block area having effective scattering irradiation parameter E2

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[Procedure amendment]

[Submission date] March 4, 1994

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 7]

[Figure 1]

[Fig. 2]

[Figure 3]

[Figure 4]

[Figure 5]

[Figure 6]

[Figure 8]

Claims (7)

[Claims] 1. At least two light-scattering light guides having complementary shapes, which are given a light-scattering ability by being molded through a kneading step of at least two materials having mutually different refractive indexes. Block domain Γ i (i = 1,
2, ...) and a plate-like light-scattering light guide element, and at least one light-incident means capable of allowing light to enter from the side of the plate-like light-scattering light-guide element. When the scattering power of the scattering light guide block region Γi is represented by effective scattering irradiation parameter values Ei (i = 1,2, ...), each effective scattering irradiation parameter value Ei (i = 1,2 ,. .) Is not equal to any other effective diffuse irradiation parameter value,
Moreover, the average value Eav of the effective scattering irradiation parameters on the cross section in the thickness direction of the plate-like light-scattering light guide is relatively small in the portion relatively close to the light incident means, and relatively small to the light incident means. A light-scattering light guide light source device characterized in that it is relatively large in a portion far away from. 2. The values of the effective scattering irradiation parameters Ei (i = 1, 2 ...) Of the respective light scattering guide block regions are
Correlation function γi (of non-uniform refractive index structure) in the range of 0.0001 [cm ⁻¹ ] ≦ Ei ≦ 1000 [cm ⁻¹ ] and causing the scattering ability in each light scattering guide block region Γi ( r) is an approximate expression, γi (r) = exp [-r / ai
] (Where r is the distance between two points in the light-scattering light guide block area Γi), the range of the correlation distance ai is 0.
2. The light-scattering light guide light source device according to claim 1, wherein the range is 005 μm ≦ ai ≦ 50 μm. 3. At least one of the light-scattering light guide block regions Γ i includes a polymer matrix and a particulate material dispersed and contained in the polymer matrix through a molding process including a kneading step. The light scattering guide light source device according to claim 1 or 2, wherein the refractive index and the refractive index of the polymer matrix are different from each other by at least 0.001. 4. At least one of the light-scattering light guide block regions Γ i is made of a material formed by a molding process including a kneading step of at least two kinds of polymers, and the refractive index of the at least two kinds of polymers is The difference between the maximum and minimum refractive index is at least 0.00
It is 1 or more, Claim 1 or Claim 2 characterized by the above-mentioned.
The light-scattering light guide device described in. 5. The method according to claim 1, wherein at least one of the light scattering guide block regions Γi is formed by a process including an injection molding process. Light scattering light source device. 6. The method according to claim 1, wherein at least one of the light-scattering light guide block regions Γ i is formed by a process including an extrusion molding step. Light scattering light source device. 7. The scattered light emitting direction correcting means for correcting the scattered light emitting direction characteristic facing the scattered light taking-out surface area of the light scattering guide element or the surface area opposite to the scattered light taking-out surface area. The light-scattering light-guide light source device according to any one of claims 1 to 6, wherein the light-scattering light-guide element is provided integrally with or separately from the light-scattering light-guide element.