JP3215218B2 - Light scattering light guide light source device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

2. Description of the Related Art Hitherto, various types of optical elements or devices for emitting light in a desired direction by utilizing a scattering phenomenon have been known, and are used for backlight sources of liquid crystal display devices. Used in One type of these known optical elements or devices is that light is incident from the side of an extended plate-shaped transparent material, a reflective element is arranged on one surface side, and light diffusivity is provided near the other surface. The surface light source is provided as a light emitting surface and is used as a backlight light source of a liquid crystal display device. For example, Japanese Patent Laid-Open No. 62-
JP-A-235905, JP-A-63-63083,
JP-A-2-13925 and JP-A-2-24578
No. 7 describes this.

In such a planar light source device using the light scattering light guide device, light scattering is not generated volumetrically inside the transparent body, and irregular reflection or specular reflection near the surface of the transparent body or at a reflection element is caused. There is only a fundamental difficulty in sufficiently increasing the proportion of scattered light that can be extracted from the light-scattering light-guiding device, because the light-scattering light-guiding device only has a spread in the light emission direction.

[0003] Further, when an attempt is made to obtain a planar light source device having uniform illuminance by irradiating light from the side, as will be easily understood from the examples shown in the above-mentioned known documents, the reflection element is required. Of the light scattering / guiding device must be complicated and large, and the manufacturing cost must be high.

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

[0005] As a second type of the known light-scattering light-guiding element or light source device, a light diffusing plate is formed by dispersing a particulate material having a different refractive index from the transparent material inside an extended plate-shaped transparent material. There is something to do.

For example, JP-A-1-172801, JP-A-1-236257, JP-A-1-269
Japanese Patent Application Laid-Open Nos. 901-901, 2-221925 and 4-145485 belong to this type.

[0007] In particular, in 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 side, and the other side is exposed. It is disclosed that a backlight light source or the like of a liquid crystal display device is configured as a light emitting surface.

[0008] In these plate-shaped light guide elements, light scattering occurs volumetrically due to non-uniform refractive index caused by particulate matter 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 this type of light scatterer is incorporated as a light scatterer and light guide device. However, the following problem arises in the configuration.

That is, as can be seen from the above-mentioned known examples, an element having a light scattering ability by itself and having a function of guiding light while scattering light, that is, a light scattering light guide, and the light scattering light guide When a light scattering device is used in combination with a light source element that allows light to enter from the side of the body, the dispersion of the particulate matter dispersed in the light scattering device is intended to make the intensity of the emitted scattered light uniform. By giving a gradient to the concentration, or by using a light-diffusing ink or the like on the back side of the light-scattering light guide, a mesh-like or dot-like scattering reinforcing means is provided, and in some cases, the density of the mesh or the dot is increased. Gradients have been made.

That is, conventionally, the scattering power is consciously reduced in a portion close to the light source, and the light scattering capability is maximized in a portion remote from the light source, including a mesh-like or dot-like reinforcing layer on the back surface side. 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 region to maximize the light scattering ability have been adopted.

In the background where such a method has been widely used in the past, generally, in a light scattering light guide device of a normal size, the scattering reinforcing means on the back surface region of the light scattering light guide is indispensable for securing the total amount of scattered light. In addition to the fact that the light scattering guide is constructed by dispersing different refractive index particles in a matrix, the light scattering ability according to the distance from the light source in some form It is a fact that there is a problem that illuminance reduction in a portion far from the light source cannot be avoided unless a gradient is given. Further, as another form of the second type of technology, the shape of the light-scattering light guide may be wedge-shaped or triangular, without giving a gradient to the hetero-refractive-index material dispersion density itself in one light-scattering light guide. It has been proposed to have a roof shape.

For example, Japanese Patent Application Laid-Open No. 4-140783 discloses that a light-scattering light guide (milky white substrate) having a mountain cross section and a transparent substrate are combined in a shape relationship (complementary relationship) that complement each other. A light-scattering and light-guiding light source device having a structure in which members are formed and light sources are arranged on both sides is disclosed.

Further, the present inventors have already used a so-called cast polymerization technique to uniformly disperse a different refractive index substance in a polymer matrix to form two wedge-shaped light scattering guides having different scattering capabilities. A light-scattering light-guiding light source device of a system in which light is incident from the side by forming a light-scattering light-guiding element in a single plate by combining bodies (see International Patent Application PCT
/ JP / 92/01230 (priority date; September 27, 1991) "," Polymer Reprints, J
apan Vol. 41, no. 3; 1992 ",
802 and "Polymer Reprints,
Japan Vol. 41, no. 7; 1992
Years, pp. 2945-2947).

[0014]

As described above, in the prior art, light is incident from the side of an extended plate-shaped transparent material, a reflecting element is arranged on one surface side, and the vicinity of the other surface. In a light scattering light-guiding device of the type used as a backlight light source of a liquid crystal display device, which constitutes a planar light source having a light emitting surface by giving light diffusing property, it is difficult to increase the light use efficiency, Also, if you try to increase the illuminance of the light exit surface by force,
Various reinforcing means are required, which increases the thickness and the like of the apparatus, and also increases the manufacturing cost.

Further, in the type using this transparent plate, when a mesh or dot-shaped reinforcing layer is formed on the back side of the transparent plate for reinforcing the scattering ability and making the illuminance distribution uniform, the light exit surface Observation of the light scattering / guiding device from the side has a disadvantage that the mesh or dot pattern of the reinforcing layer 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 configuration also causes light absorption, which is a factor of lowering the light use efficiency, and also complicates the device structure and causes an increase in manufacturing cost.

On the other hand, a light-scattering light-guiding light source device is obtained by combining a light-scattering light-guiding body which itself has a light-scattering ability, and a light source element for allowing light to enter from the side of the light-scattering light-guiding body. A gradient is given to the dispersion concentration itself of the particulate matter dispersed in the light guide, or a light-scattering reinforcing layer having a mesh shape, a dot shape, or the like using a light-diffusing ink or the like on the back side of the light-scattering light guide. In the case of taking measures such as providing additional equipment, the complexity of the device structure and the manufacturing
It was unavoidable due to the disadvantages of sophistication.

That is, in the case where a mesh or dot-like reinforcing layer is formed on the back surface of the light-scattering light guide and the scattering ability of the reinforcing layer is graded as the scattering power gradient imparting means, the mesh Alternatively, a predetermined gradient must be imparted to the distribution density of the dot pattern, which makes the manufacturing process more complicated than when a simple scattering reinforcing layer is formed, and is clearly disadvantageous in terms of manufacturing cost.

When the brightness of the light-scattering / guiding light source device is made uniform by giving a gradient to the dispersion density of the different refractive index substance dispersed in the polymer matrix, the intended dispersion density gradient It is not always technically easy to manufacture a light-scattering light guide having the following characteristics quickly and reliably, and it cannot be said that this is a technique suitable for mass production.

Further, in the device disclosed in Japanese Patent Application Laid-Open No. 4-140783, only the light scattering light guide (milky white substrate) having a mountain-shaped cross section contributes to the scattering, and the volume of the remaining transparent substrate is reduced. No scattering occurs. Therefore, there is a fundamental problem that the scattering efficiency when the thickness of the plate-like element is constant is reduced as a whole, and the means for imparting the scattering power gradient is limited to only the section having a mountain-shaped cross section. If the average scattering power of the whole is determined, the magnitude of the scattering power gradient is also determined unless the shape is changed, which is a constraint in manufacturing light scattering light guide devices of various characteristics using specific materials. .

The technique proposed by the present inventors in the above-mentioned report is based on the fact that the scattering ability is given to both of the two parts constituting the plate-like element and the selected scattering ability is given to each of the parts. Therefore, it can be said that this is a technique that can provide a light-scattering and light-guiding 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.

However, at the time of the proposal, as described in the above-mentioned reports and the specification, cast polymerization is used as a technique for producing each wedge-shaped light scattering light guide, and mass production is required. From the viewpoint, it must be said that there was the same problem as in the case of the related art in which a gradient is provided to the different refractive index dispersion density in the light scattering light guide.

The present invention avoids problems such as the complicated, large-sized, and inadequate mass production of the apparatus, 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 and light-guiding light source device having a surface and excellent suitability for mass production.

[0023]

According to the present invention, first, mutually complementary shapes provided with a light scattering ability by being formed through a kneading process of at least two materials having mutually different refractive indices are provided. And a plate-like light-scattering and light-guiding element including at least two light-scattering and light-guiding block regions Γi (i = 1, 2,...), And light is made incident from the side of the plate-like light-scattering and light-guiding element. And at least one light incident means capable of operating the light scattering / guiding member block region Γi, wherein the scattering power of each of the light scattering / guiding member block regions Γi is represented by an effective scattering irradiation parameter value Ei (i = 1, 2,...) , Each effective scattering irradiation parameter value Ei (i = 1,2, ...)
) Is not equal to any of the other effective scattering irradiation parameter values, and the average value Eav of the effective scattering irradiation parameters on the cross section in the thickness direction of the plate-shaped light scattering light guide is The basic configuration for solving the above-mentioned problem is based on a light-scattering light-guiding light source device that 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. It is provided (the configuration according to claim 1).

Also, in the present invention, based on the above basic configuration, the values of the effective scattering irradiation parameters Ei (i = 1, 2,...) Of each light scattering light guide block area are all 0.0001.
The correlation function γi (r) of the non-uniform refractive index structure in the range of [cm ^-1 ] ≦ Ei ≦ 1000 [cm ⁻¹ ] and causing the scattering power in each of the light-scattering light guide block regions Γi.
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 represented by the following expression is 0.005 μm ≦
By imposing the condition that ai ≤ 50 µm, the effectiveness when applied to a backlight light source or the like is further ensured (the configuration according to claim 2).

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

According to 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. 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 / guiding light source device having each of the above-described configurations is generally supported in a different form from the material side. (Claim 5)
Configuration described in).

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

According to the present invention, on the premise of these configurations, the light scattering direction correcting means for correcting the light emitting direction facing the front surface region or the back surface region of the light scattering light guiding element is provided. The angle characteristics of the intensity of the scattered light emitted can be corrected by being provided integrally with or separately from the element.

[0029]

The light scattering light-guiding light source devices of the present invention, which have been schematically described above, will be described in more detail, focusing on their functions. First, in claim 1 and claim 2, regarding the scattering irradiation parameter E and the correlation distance a used for numerically limiting the light scattering ability of each light scattering light guide block region,
This will be described with reference to Debye's theory.

When the light having the intensity I0 passes through the medium in y (cm) and the intensity is attenuated to I by scattering during the period, the effective scattering irradiation parameter E is defined by the following equation (1) or (2).

[0031]

(Equation 1) Equations (1) and (2) are so-called integral and differential expressions, respectively, and their physical meanings are equivalent. Note that this E
Is sometimes called turbidity.

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

[0033]

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

[0034]

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

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

[0036]

(Equation 4) Assuming that the non-uniform structure is constituted by a spherical interface having a radius R, the correlation distance a is expressed by the following equation.

[0037]

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

[0038]

(Equation 6) From the relation 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. It goes without saying that the angle dependence of the scattered light intensity is a matter that can be considered when the light scattering guide of the present invention is applied to an actual lighting 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} ].

In general, the larger E is, the larger the scattering power is,
If E is small, the scattering power is small, in other words, it is almost transparent. E = 0 corresponds to no scattering at all.

Therefore, in general, in order to realize a relatively large area, uniform illuminance planar light source, the value of E should be small,
It is only necessary to cause light scattering in a wide range.

As a rough guide, for example, E = 0.
If it is about 0001 [cm ^-1 ], the light-scattering light guide can be made to emit light relatively uniformly within a range of up to several tens of meters. Also,
If E = 100 [cm ^-1 ] shown in FIG.
It is suitable for intensively and uniformly illuminating the range of m.

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

However, these values of the effective scattered irradiation parameter E are only for reference, and the scattered light reinforcement or the scattered light depending on the use conditions of the specific application apparatus, for example, the intensity of the primary light source, the optical element arranged in the periphery, etc. It is preferable to flexibly select in consideration of the attenuation factor and the like. When the angular characteristics of light scattering are special, a value of E = 1000 or more may be selected.

As for the correlation distance a, 0.005 μm
Although it is considered that m to 50 μm is practical, it is preferable that each case is determined in consideration of required angle characteristics and the like.

By treating the scattering phenomenon as described above, the scattering characteristics of the light-scattering light guide can be determined by specifying the range of the scattering irradiation parameter E and the correlation distance a. The light-scattering and light-guiding device according to claims 1 and 2 specifies the scattering characteristics of each light-scattering and light-guiding block region incorporated therein based on such a concept.

Based on the above description regarding the effective scattering irradiation parameter E or the correlation distance a, the operation of the light-scattering light-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 the simplest configuration of a light-scattering light-guiding light source device according to the present invention in the form of a cross-sectional view. Explaining this, the light-scattering and light-guiding light source device generally indicated by the numeral 1 includes a light-scattering and light-guiding element 2 and a reflection surface provided on the back surface (surface opposite to the scattered light extraction surface). It comprises an element 4 and a light source element 3 to which light is incident from the side of the light scattering and light guiding element 2. The arrangement of the reflective element 4 on the back surface side of the light scattering / guiding element itself belongs to a known technique for preventing useless 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 a normal mirror plate or a white diffusion plate as the reflection element 4.

The reflection element 4 is a light-scattering light-guiding element 2
Another advantage of the present invention is that it is not necessary to form the mesh-like or dot-like pattern in the above-described prior art separately or on the main body of the light-scattering light-guiding element.

The light-scattering light-guiding element 2 is composed of two light-scattering light-guiding block regions Γ1 and を 2 having complementary shapes, and effective scattering irradiation parameters E1 and E2 representing the scattering power of each block region. E1> E2
The material is selected so that As shown in FIG. 2 in the form of a graph, the x-axis and the y-axis are respectively set in the light incident direction and the thickness direction of the light-scattering light-guiding element 2, and the side of the light incident end is defined as x =
Considering the average effective scattering irradiation parameter Eav (x) on the section in the thickness direction at each position x as the plane of 0,
The following equation (13) holds.

Eav (x) = E 2 + [(E 1 −E 2) / L] x (13) where L is a length measured along the light incident direction of the light scattering / guiding element 2 (hereinafter referred to as “L”). , The length of the light-scattering light-guiding element is simply referred to as “length”.
Will gradually and greatly increase 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 incident from the side of 0 repeats scattering and x
As the light travels in the axial direction, the light is attenuated in the form of scattered light emitted from the scattered light extraction surface (upper surface) or absorption loss in the light scattering / guiding element main body or on the surface of the reflecting element 4. Energy density ρ at position x
(X) decreases with the x value. The intensity of the 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
(X) · ρ (x), so that the increasing function E of x
The av (x) and the decreasing function ρ (x) cancel each other, so that the brightness of the light-scattering light-guiding element 2 becomes uniform as a whole.

As can be seen from the expression (13), the smaller the length L of the light-scattering light-guiding element 2 and the larger the value of the difference ΔE = E1−E2 between the effective scattering irradiation parameters, Eav.
The gradient of (x) increases. Therefore, if ΔE is appropriately selected, the same effective scattering irradiation parameter gradient Eav (x) can be realized for the light scattering light-guiding 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 .DELTA.E. Since the technology described in Japanese Patent Application Laid-Open No. 4-140783 does not show any technical idea of combining block regions having non-zero scattering power,
Such freedom of choice cannot be expected.

Incidentally, as described in the description of the prior art, such a concept itself has already been reported by the present inventors, but the problem that productivity is difficult remains unsolved. there were.

Therefore, in the present invention, the origin of the scattering ability of the material constituting the light scattering light guide block region is determined in the "kneading step". That is, the light-scattering light-guiding block formed through a step including a kneading step of mixing and kneading a plurality of generally transparent materials having different refractive indices,
Focusing on the fact that the block has a certain scattering ability regardless of the shape, solve the above productivity problem, and configure the combination of complementary shapes of each block and the entire light scattering light guide element. This allows the number of blocks to be varied to be freely provided.

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

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

In (5), the effective scattering irradiation parameter E is set in a stepwise manner toward the center of the light-scattering light-guiding element.
An example is shown in which the thickness of the block portion having 1 is increased. According to this configuration, no slope or curved surface is required for each light-scattering light guide block, which may be advantageous for simplifying the molding process.

Next, FIGS. 4A and 4B show two-dimensional effective scattering irradiation parameter average values E in the light scattering light guide element.
An example giving the distribution of av is shown. In FIG. 4A, the entire light scattering / guiding element has a rectangular parallelepiped shape. A light-scattering light guide block region having an effective scattering irradiation parameter E1 is formed in a pyramid shape (quadrangular pyramid) having a point P0 as an apex upward from the central bottom surface P5 P6 P7 P8. On the other hand, the light scattering / guiding member block region having a complementary shape has an effective scattering irradiation parameter E2 (E2 <E1).
) Having four light-scattering light guide block regions P0 P1
P2, P5, P6, etc. (however, they can be manufactured as one block area P1 P2 P3 P4 -P5 P6 P7 P8 -P0 by merging).

In this case, light is incident from four directions as indicated by arrows. It is easy to see that the proportion occupied by the high effective scattering irradiation parameter block area is the maximum (= 1) at the point P0 in correspondence with 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 example of an arrangement in the case where a circular uniform scattered light source device is required. In this example, instead of the pyramid-shaped block region in FIG. 4A, a conical block region Q1 Q2 is formed as the block region having the high effective scattering irradiation parameter E1, and the shape of the entire light scattering light guide element is changed. In a disk or column shape. As the light source for light incidence used in combination with this arrangement, it is usually considered advantageous to select an arc-shaped light source from the viewpoints of ensuring uniformity of illuminance and light use efficiency.

When various block shapes and arrangements as exemplified in FIGS. 3 and 4 are to be manufactured with high industrial productivity, light scattering light guides of various shapes with effective scattering irradiation parameter values controlled. A body block must be formed. In the present invention, one light-scattering light-guiding element is formed by combining the light-scattering light-guiding block regions formed through the kneading step of the different refractive index material in order to satisfy such conditions. .

As the combination of the materials to be kneaded,
One type is conceivable. That is, as described in claim 4, the first type is to disperse a particulate material having a different refractive index in a polymer matrix by kneading, and the second type is
As described in claim 5, polymers having different refractive indices are kneaded. Regardless of which type is adopted, if there is a non-zero refractive index difference between the kneading materials, it will theoretically function as a light scattering light guide. Is set 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 (see claims 3 and 4).

Representative examples of the polymer matrix material used in the first type include PMMA (polymethyl methacrylate), PSt (polystyrene), and Pt (polystyrene).
C (polycarbonate) and the like, but in principle, any of the polymer materials described in Tables 1 and 2 including these can be used. These materials are usually used alone to form a polymer matrix,
A plurality of types may be mixed and kneaded with the particulate matter. In this case, since the different refractive index polymer is blended, it naturally has the second type.

The particulate matter dispersed in the polymer matrix composed of these polymer materials has a different refractive index from that of the polymer matrix and is stably present in the polymer matrix material (does not cause elution or denaturation). What can be used may be appropriately used. For example, a silicon-based resin powder (for example, manufactured by Toshiba Silicon, marketed under the trade name Tospearl) or crosslinked particles made of various organic materials as raw materials can be used. As can be seen from the expression (9), the correlation distance a and the particle diameter 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. Typical particle size used is 0.1 μm to 10 μm.
About μm is conceivable.

The second type of technology utilizes a process which can be called a polymer blend in which two or more polymers are kneaded as described in claim 4. No. 341589 is applied.

That is, light scattering is obtained by mixing and heating two or more polymer materials having different refractive indices mutually different in refractive index (arbitrary shape may be used, and industrially, for example, a pellet shape) and mixing them. The original material of the light guide can be obtained (kneading step). By selecting the combination of the polymer materials to be blended and the blend ratio, it is possible to provide various effective scattering irradiation parameters E and values of the correlation distance a. These raw materials are formed into a light-scattering light guide block of a desired complementary shape through an appropriate process,
If integrated into one light-scattering light guide by appropriate means (for example, adhesion using a transparent adhesive, fixing using a reflective foil or the like that covers the non-light incident surface of the light-scattering light-guiding element), The light scattering light guide element used for the light scattering light guiding light source device is obtained.

The materials which can be used for the polymer blend are extremely wide, but typical ones are listed in Tables 1 and 2 below. Since the combination and mixing ratio of these polymer blends can be selected from a very wide range, the difference in refractive index, the strength and properties of the non-uniform refractive index 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 in consideration of the fluctuation root mean square τ).

[0067]

[Table 1]

[0068]

[Table 2] Any molding technique may be used to mold and knead the kneaded material of the first mold or the second mold,
In consideration of mass productivity and economy, it is considered most practical to use a so-called injection molding technique as described in claim 5. That is, a mold having a desired complementary shape is prepared, and the raw material obtained by kneading the molding machine polymer and the granular material or the polymers together is injected into the molding machine mold in a high pressure state in a molten liquid state, and then cooled and solidified. If the molded product is taken out of the mold after the formation, a light-scattering light guide block having a shape corresponding to the shape of the mold can be obtained. For example, when manufacturing a light-scattering light-guiding element of the type shown in FIG. 3A, at least one wedge-shaped mold may be prepared, and in the case of FIG. It is sufficient to prepare a right-angled triangular mold.

[0069] In the case of kneading particulate matter insoluble in the polymer as well as the case of blending the polymers, the different polymers are cooled and solidified through the injection molding process without completely uniform fusion. Therefore, the polymer is immobilized while leaving the local concentration of each polymer non-uniform (fluctuation). Therefore, if there is a substantial difference in refractive index between the polymers to be kneaded, a light-scattering light guide having a non-uniform refractive index structure is manufactured.

In addition, depending on the shape and size of the light-scattering light guide block, an extrusion molding technique known as a molding method excellent in production efficiency along with injection molding is applied. It may be advantageous to configure the light guide light source device. For example, in the case of manufacturing a light-scattering light-guiding element having a cross-sectional structure as shown in FIG. 3A, a kneaded molten material is placed in a cylinder of an extruder provided with a right-angled triangular-shaped extrusion port. To produce a long light-scattering light guide in a usual manner, and cutting the light source device into a length corresponding to the depth length (dimension in a direction perpendicular to the paper surface in FIG. 3) of the light source device. A light-scattering light guide strip-shaped block can be obtained.

Next, the configuration described in claim 7 is based on the invention of Japanese Patent Application No. 4-341589 or Japanese Patent Application No.
The scattered light emitting direction correction means described in each specification of JP-A-355073 is applied to each light scattering light guide light source device described in claims 1 to 6. Less than,
This will be described briefly.

For example, in a liquid crystal display device or the like, the display surface is generally observed from a fan-shaped space region centered on the front direction. It is desired that the scattered emitted light of the device is strongly distributed in an appropriate angle range centered on a direction perpendicular to the light extraction surface. If the scattered light emitting direction correcting means is used, such a demand can be surely met.

FIG. 5 shows an example in which a separate scattered light emitting direction correction element is provided on the side of the scattered and emitted light extraction surface with respect to the light scattering and light guiding element of the type shown in FIG. The light guide element 11 is composed of a high scattering power region having a chevron-shaped effective scattering irradiation parameter E1 and a low scattering power region having two effective scattering irradiation parameters E2 forming a plate-like body by supplementing the high scattering power region. A light source (fluorescent lamp) 12 is arranged on both sides of the light scattering light guide element 11, and a scattered light emitting direction correcting element 14 is provided on the side of the scattered light extraction surface 15. The back surface 16 of the light-scattering light guide 11 is an optically open surface, and the light-scattering light-guiding element 11 is not subjected to a light scattering reinforcing process such as a light diffusion ink pattern or an uneven diffusion surface. A reflector (white film plate) 13 separate from the light-scattering light-guiding element 11 is arranged to face the back surface 16.

As the scattered light emitting direction correcting element 14, a thin plate or sheet-like element having a large number of rows of prism regions is used as shown in FIG. The scattered light emitting direction correcting element 14 has a function of correcting the direction of light emitted obliquely from the light scattering and light guiding element 11 to a direction right above by refraction. The specific shape of the scattered light emitting direction correcting element is not limited to the illustrated one, and any type may be used. For example, a film in which a group of triangular pyramidal or dome-shaped protrusions are distributed, a plate-like element having a row-like convex portion having a semi-cylindrical cross section, and the like can be considered.

The undulating surface causing the refraction action is usually
The light on the upper side (far side from the light-scattering light guide 1) is used, but if the light emitted obliquely from the light-scattering light guide 1 has a function of correcting the direction directly above, the light-scattering light is guided. Element 11
A type having an undulating surface on the side facing may be used. The direction in which the intensity of the scattered light is increased by the scattered light emission direction correcting means is not necessarily the front direction of the light scattering / guiding element. By selecting a prism angle, the intensity of the scattered light emitted in the oblique direction is increased. What you can do will not require any particular explanation.

FIG. 6 shows a light-scattering light-guiding element 21 of the type shown in FIG.
A row-shaped prism surface area 22 is provided as a 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 illustrated. The function of the row prism surface area 22 is the same as the function of the scattered light emitting direction correcting element 14 in FIG. In FIG. 6, reference numeral 24 denotes a reflector (white film plate) separate from the light-scattering light-guiding element 21, and 25 denotes light sources (fluorescent lamps) arranged on both sides of the light-scattering light-guiding element 11. is there.

FIG. 7 shows two light sources (fluorescent lamps) 35.
A row-shaped 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 extracted, as a means for correcting the direction of scattered light emission integrated with the light-scattering light-guiding element 31. is there. The arrangement of the reflectors 34 facing each other is the same as in the case of FIG. 5 or FIG. The shape of each area of the effective scattering irradiation parameters E1 and E2 is obtained by inverting the shape shown in FIG. This columnar prism surface area 3
2 is slightly more complicated than the scattered light emission direction correcting means 14 and 22 shown in FIG. 5 or FIG. 6, so that the prism pitch, apex angle, depth of unevenness, etc. for realizing the optimum scattered light direction correction. It is practical to determine by adopting an experimental method. The prism concave / convex void indicated by 33 may be an air layer.

As a specific method for forming the uneven area on the front surface area or the rear surface area of the light scattering / light guiding element body, a method used for injection molding or extrusion molding, or a method for forming a predetermined shape on an extrusion opening, press working, or the like. , A method based on mechanical processing such as cutting, and a method based on a chemical processing process such as various types of etching are conceivable. However, what means to form the concavo-convex region depends on the technical scope of the present invention. It is not a matter that has a restrictive effect on

Further, various combinations, sizes, etc., of the types of the scattered light emitting direction correcting means and the light scattering / guiding element as described above can be adopted. It does not depart from the scope.

[0080]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Some specific embodiments will be described below. <Example 1> 0.3 wt% of a silicon-based resin powder (Toshiba 130, manufactured by Toshiba Silicon) having a particle diameter of 3 µm was added to a methacrylic resin pellet (Delvet 80N, manufactured by Asahi Kasei Corporation).
The resulting mixture was mixed and dispersed by a mixer, extruded into a strand by an extruder, and pelletized by a pelletizer to prepare a pellet in which the silicon-based 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., and had a length of 80 mm and a width of 100 mm, and a thickness in the long side direction. A wedge-shaped light-scattering and light-guiding block linearly changing from 1 mm (the thinnest part) to 3 mm (the thickest part) was produced along with the light-scattering and light-guiding block # 1.

Using a methacrylic resin pellet (Delvet 80N, manufactured by Asahi Kasei Corporation) added with 0.01 wt% of a silicon-based resin powder (Tospearl 130, manufactured by Toshiba Silicon) having a particle size of 3 μm, and using a similar process, a vertical length of 80%.
mm, width 100 mm, and thickness 1 along the long side direction.
A wedge-shaped light-scattering and light-guiding block that linearly changes from mm (the thinnest part) to 3 mm (the thickest part) was obtained. This was designated as a light-scattering light guide block # 2.

The two wedge-shaped light-scattering light-guiding blocks # 1 and # 2 having complementary shapes are closely fixed to each other to form one plate-like light-scattering light-guiding element, which is shown in FIG. In this manner, the light-scattering light-guiding light source device was constructed.

The wedge-shaped block region portion This light-scattering light-guiding element belongs to the type shown in FIG. 2, and the light source is arranged on one side of the light-scattering light-guiding element 41 (the side with weak scattering ability).
Only, and the surface of the reflection plate 43 disposed on the back side of the light scattering light guide element 41 was a mirror surface. Within the block area Γ1,
Since the particulate matter serving as the scattering center is dispersed at a higher density than the block region Γ2, both the block regions Γ1 and Γ2
For the effective scattering irradiation parameters E1 and E2 of E1>
E2 holds. Therefore, as described in the related description of FIG. 2, the light scattering / guiding element 41 as a whole has an average effective scattering irradiation in the thickness direction from the end portion closer to the light source to the end portion farther from the light source. The structure in which the parameter value Eav is gradually increased is realized, and the uniformity of the illuminance in the light-scattering light-guiding light source device is achieved by the configuration of FIG. 8 in which light is incident from the side having the smaller Eav value. Should be.

To confirm this, the intensity of scattered light was observed using a video camera and an intensity display device in the direction of arrow VD. The light intensity difference between the part and the darkest part was only about 5%. That is, the contrast ratio 9
It was confirmed that a light-scattering light-guiding light source device having an extremely high brightness uniformity of 5% was obtained.

<Example 2> 0.4% by weight of polymethyl methacrylate (PMMA) containing polystyrene (PSt)
The mixture was added and mixed using a V-type tumbler for 10 minutes, and then using a Henschel mixer for 5 minutes. This is diameter 30
Using a 2-mm extruder [manufactured by Nakatani Machinery Co., Ltd.], pellets were prepared by melting and mixing at 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 an injection molding machine, the pellets were subjected to a cylinder temperature of 220 ° C. to 250 ° C., a mold temperature of 65 ° C., a medium injection speed, an injection pressure short shot pressure plus 10 k.
g / cm ² , 80 mm long and 100 mm wide
mm, thickness from 1 mm (the thinnest part) along the long side direction to 3
A wedge-shaped light-scattering light guide block that linearly changes up to mm (thickest part) was prepared, and was designated as a light-scattering light guide block # 1 '.

A polymethyl methacrylate (PMMA) to which 0.01 wt% of polystyrene (PSt) is added is used.
A wedge-shaped light-scattering light-guiding block having 0 mm and having a thickness linearly changing from 1 mm (thintest part) to 3 mm (thickest part) along the long side direction was obtained. This was designated as light scattering light guide block # 2 '.

The two wedge-shaped light-scattering light-guiding blocks # 1 'and # 2' having complementary shapes are closely fixed to each other to form one plate-like light-scattering light-guiding element. The light-scattering and light-guiding light source device was constructed in the same arrangement as in the example shown in FIG.

This light-scattering light-guiding element also belongs to the type shown in FIG. 2, and the effective scattering irradiation parameters E1 ′ and E2 ′ of the block area 、 1 ′ satisfy E1 ′> E2 ′. I do. Therefore, also in this case, a structure in which the average effective scattering irradiation parameter value Eav in the thickness direction gradually increases 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 light guide element. Will be. Therefore, as in the case of the embodiment <1>, the intensity of the scattered light should be uniform over the entire scattered light extraction surface.

To confirm this, the same observation as in Example <1> was performed from the direction of arrow VD using a video camera and an intensity display device. 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 to manufacture and has a uniform and bright light emitting surface with an extremely simple structure, avoiding the complexity and size increase of the device which was inevitable in the prior art. An apparatus is provided. Further, according to the present invention, a light scattering light guide device suitable for observation from a specific direction or the like is realized by using the scattered light emitting direction correcting element. In particular,
The present invention uses a light-scattering light guide in the form of a block, which is provided with a scattering ability by a kneading process that can be easily incorporated into a plastic material molding process such as injection molding or extrusion molding. A light-scattering and light-guiding light source device that has a wide range of choices in the material and shape of the body block, and that is excellent in mass productivity and economy can be realized.

Since the light-scattering light-guiding light source device of the present invention has such basic features, it can be used as a backlight light source device for various displays such as a liquid crystal display device, a backlight light source for an automobile or the like, and a sun light source as a primary light source. The present invention exerts its usefulness in a wide range of optical fields through application to various sizes of planar light sources in various illumination systems using light or ordinary illumination light sources.

[Brief description of the drawings]

FIG. 1 shows a curve of the effective scattering irradiation parameter E with the correlation distance a on the horizontal axis and the mean square τ = <η ² > of the dielectric constant fluctuation on the vertical axis, where E = 50 [cm ⁻¹ ] and E = 100 [ cm ^-1 ].

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

FIG. 3 is a diagram exemplifying a combination of complementary shapes of respective light scattering light guide block regions constituting a light scattering light guiding element used in the light scattering light guiding 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 each light scattering light guide block region constituting the light scattering light guiding element used in the light scattering light guiding light source device of the present invention. .

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

FIG. 6 is a diagram showing the configuration of a light-scattering and light-guiding light source device in which an array of prism surface areas is provided on a scattered and emitted light extraction surface for a light-scattering and light-guiding element of the type shown in FIG.

FIG. 7 is a diagram illustrating a configuration of a light-scattering and light-guiding light source device in which an array of prism surface regions is provided on a surface of the light-scattering and light-guiding element opposite to the surface from which the scattered emission light is extracted.

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

[Explanation of symbols]

1, 10 light-scattering light-guiding light source device 2, 11, 21, 31 light-scattering light-guiding element 3, 12, 25, 35 light source (fluorescent lamp) 4, 13, 24, 34 reflector 5 scattered emission light extraction surface 6 light Back surface of scattering light guide (optically open surface) 14 Scattering / emitting light direction correcting element 15 Scattering light extraction surface 16 Light scattering light guiding element back surface 22, 32 prismatic surface 33 Void portion Γ1 Effective scattering irradiation parameter E1 Light-scattering light guide block area with Γ2 Light scattering light guide block area with effective scattering irradiation parameter E2

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-53-36199 (JP, A) JP-A-63-29728 (JP, A) JP-A 7-43700 (JP, U) JP-A 5- 45601 (JP, U) Japanese Utility Model 3-12202 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) G02F 1/13357 G02B 6/00 G09F 9/00 332

Claims (7)

(57) [Claims] 1. At least two light-scattering light guides having shapes complementary to each other and given a light-scattering ability by being formed and processed through a kneading step of at least two materials having mutually different refractive indices. Block area Γi (i = 1,
2,..), And at least one light incident means capable of receiving light from a side of the plate-shaped light scattering light-guiding element, When the scattering power of the scattered light guide block region Γi is represented by an effective scattering irradiation parameter value Ei (i = 1, 2,...), Each effective scattering irradiation parameter value Ei (i = 1, 2,. .) Is not equal to any other effective scattered irradiation parameter value;
In addition, the average value Eav of the effective scattering irradiation parameters on the cross section in the thickness direction of the plate-shaped light scattering light guide is relatively small in a portion relatively close to the light incidence means, and is relatively small in the portion close to the light incidence means. A light scattering light-guiding light source device, which is relatively large in a portion far from 2. The value of the effective scattering irradiation parameter Ei (i = 1, 2,...) Of each of the light scattering light guide block regions is:
The correlation function γi of the non-uniform refractive index structure in the range of 0.0001 [cm ⁻¹ ] ≦ Ei ≦ 1000 [cm ⁻¹ ] and causing the scattering power in each of the light scattering / guiding block regions ブ ロ ッ ク i. 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) and the range of the correlation distance ai is 0.
2. The light-scattering light-guiding 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 Γi includes a polymer matrix and a particulate material dispersed and contained in the polymer matrix through a molding process including a kneading step. 3. The light-scattering light-guide light source device according to claim 1, wherein a refractive index of the polymer matrix is different from that of the polymer matrix by at least 0.001 or more. 4. 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 a 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
3. The method according to claim 1, wherein the number is at least one.
The light-scattering light-guiding device described in 1 above. 5. The method according to claim 1, wherein at least one of the light-scattering light guide block regions Γi is formed by a process including an injection molding step. Light scattering light guide light source device. 6. The method according to claim 1, wherein at least one of the light-scattering light guide block regions Γi is formed by a process including an extrusion molding step. Light scattering light guide light source device. 7. A scattered light emitting direction correcting means for correcting a scattered light emitting direction characteristic facing a scattered light extracting surface region of the light scattering light guide element or a surface region opposite to the scattered light extracting surface region. The light-scattering light-guiding light source device according to any one of claims 1 to 6, wherein the light-scattering light-guiding device is provided integrally with or separately from the scattering light-guiding element.