JP4684791B2 - LIGHTING DEVICE, LIGHT CONTROL MEMBER USED FOR THE SAME, AND IMAGE DISPLAY DEVICE USING THEM - Google Patents

Description

  The present invention relates to an illuminating device including a plurality of linear light sources and an image display device using the illuminating device, and is particularly suitable for an illumination signage device, a liquid crystal display device, and the like that are large and require high luminance and luminance uniformity. The present invention relates to an illumination device and an image display device used.

  Taking an illumination device for an image display device as an example, an edge light system that guides light of a light source arranged on the side edge of the light guide plate in the front direction with the light guide plate and makes it uniform with a diffusion sheet, and on the back side of the illumination surface There is a direct system in which a light source is arranged and light is made uniform by a light diffusion plate.

  In the direct method, since the light source is provided on the back surface of the apparatus, the edge light method, which is advantageous by providing the light source at the side edge, has been mainly used in fields where thinness is required such as a mobile phone and a mobile personal computer.

  On the other hand, in recent years, there has been an increasing demand for larger displays and higher brightness mainly in the market of televisions and personal computer monitors. With the increase in size, the edge light method reduces the ratio of the length of the peripheral portion to the display area where the light source can be arranged, so that sufficient luminance cannot be obtained. Therefore, a method of arranging a plurality of brightness enhancement films on a surface light source has also been proposed (see, for example, Patent Document 1). However, the brightness enhancement film is not necessarily advantageous from the viewpoint of productivity and thinning because it leads to cost increase and the number of films to be used increases.

  Furthermore, there is a problem that the weight of the light guide plate increases as the display becomes larger.

  As described above, it has become difficult for the edge light system to respond to market demands such as an increase in display size and brightness in recent years.

  Therefore, a direct method using a plurality of light sources is attracting attention. FIG. 15 shows an example of this type of lighting device. In this example, the illumination device has a rectangular emission surface composed of an X direction and a Y direction perpendicular to the X direction, and includes a plurality of linear light sources 1, a light diffusion plate 5, and a reflection plate 4. The linear light source 1 is arranged in one imaginary plane parallel to the X direction and the Y direction, and the linear light source 1 has a longitudinal direction arranged parallel to the Y direction, and the X direction. The light diffusing plates 5 are arranged on the emission surface side of the arranged linear light sources 1, and the main surface is the virtual plane on which the linear light sources 1 are arranged. The reflecting plate 4 is positioned on the opposite side of the light diffusing plate 5 with the arrayed linear light sources 1 sandwiched therebetween, and the main surface of the reflecting plate 4 is arranged with linear light sources. Parallel to the virtual plane. In addition, the light diffusing plate 5 usually has a light diffusing material uniformly dispersed therein and has a uniform optical performance within the main surface.

  A rectangular exit surface is most common in many applications of the present lighting device, such as image display devices and lighting signs.

  Also, the linear light source is the most common light source for these lighting devices because it is easier to eliminate luminance unevenness than the point light source and the wiring is short and easy. A cold cathode tube or the like is often used as the linear light source. In general, it is advantageous for production to use the same type of linear light source, and it is also advantageous for uniform brightness. In this case, however, the linear light source is oriented parallel to the long side of the output surface rectangle. It is desirable that the number of linear light sources can be reduced. In addition, by arranging linear light sources at equal intervals in the same plane, luminance unevenness, which is a problem, becomes periodic due to the arrangement of linear light sources, and it is a problem with light diffusing plates that have uniform optical performance within the main surface. Elimination of uneven brightness becomes easy. The reflector is not essential, but it works to reflect the light emitted from the linear light source and the light diffusing plate opposite to the exit direction to the exit side and use it again as the exit light. It is advantageous.

  In addition, the direct method requires the use efficiency of the light emitted from the light source, that is, the ratio of the light flux emitted from the light exit surface is high, and the number of light sources can be increased freely. High brightness can be easily obtained. Furthermore, since a light guide plate that directs light to the front is not necessary, the weight can be reduced.

  Further, as another lighting device, for example, an illumination signboard or the like has a simple structure, and a high brightness can be easily obtained without using a brightness enhancement film.

  However, the direct system has to solve unique problems such as elimination of lamp image, thinning, and energy saving. In particular, in an application for observing an illumination surface such as an image display device or an illumination signboard, not only the elimination of the lamp image but also the in-plane luminance uniformity is required. Furthermore, in applications where the illumination surface is observed mainly from the front, such as a television or a personal computer monitor, the uniformity of the front luminance within the surface is the most important. Since the lamp image appears as significantly more uneven brightness than in the edge light system, it is difficult to eliminate it by means such as a diffusion film in which a light diffusing material is applied to the surface of a film conventionally used in the edge light system. Therefore, a light diffusing plate in which a light diffusing material is dispersed in a base resin such as a methacrylic resin, a polycarbonate resin, a styrene resin, or a vinyl chloride resin is widely used. An example of a direct display device using a light diffusing plate is as already described with reference to FIG. In order to obtain good diffusibility and light utilization efficiency, various light diffusing materials such as inorganic fine particles and crosslinked organic fine particles have been studied (for example, see Patent Document 2). However, these methods using a light diffusing material are not preferable from the viewpoint of energy saving because they absorb light into the light diffusing material and diffuse light in unnecessary directions. Moreover, although a lamp image can be reduced by arranging a large number of light sources close to each other, there is a problem that power consumption increases.

  On the other hand, a method of erasing the lamp image by giving the reflector a unique shape has been proposed (see, for example, Patent Document 3). However, it is not preferable because it is necessary to align the shape of the reflector and the light source, and the shape of the reflector may hinder thinning.

  In addition, a method of installing a reflective member facing the light source (for example, see Patent Document 4), a method of arranging a light beam direction conversion element such as a Fresnel lens for each light source (for example, see Patent Document 5), etc. However, similarly, since the exact alignment of a member and a light source is required, the subject that productivity is inferior arises.

  Further, a light diffusing plate having irregularities on the surface has been proposed (see, for example, Patent Document 6). These diffusing plates can obtain the desired diffusibility while avoiding or reducing the use of the light diffusing material, so that the light utilization efficiency can be enhanced. However, since there is no detailed examination on the uneven shape, it is difficult to strictly adjust the luminance unevenness. Similarly, it is difficult to obtain the uniformity of the front luminance within the exit surface.

  In a large illuminating device, since the demand for thinning is not strict as compared with a mobile phone or a mobile personal computer, it can be dealt with by shortening the distance between the light source and the light diffusing plate or reducing the number of optical films. In order to realize energy saving, it is necessary to increase the light utilization efficiency. The direct method can increase the number of linear light sources and easily obtain high brightness as described above. However, from the viewpoint of energy saving, use of light by using a large amount of light diffusing material to eliminate the lamp image. Decreasing efficiency must be suppressed.

Japanese Patent Laid-Open No. 2-17 JP 54-155244 A Japanese Patent No. 2852424 JP 2000-338895 A JP 2002-352611 A JP-A-10-123307

  Therefore, in the present invention, high brightness, high light use efficiency, no change in the optical design of the light control member accompanying the increase in size, no decrease in luminance, and no increase in luminance unevenness, it is easy to cope with an increase in size, Luminance unevenness in the front direction is eliminated without strict alignment of other members, and an illumination device that is advantageous for productivity and thinning by bringing the light source close to other members and simplifying the film configuration, and the use thereof An object of the present invention is to provide an image display apparatus. Another object of the present invention is to provide an illumination device with high front luminance according to the purpose, a light control member provided in the illumination device, and an image display device using the illumination device.

  Therefore, the present inventors have found that the above-described problem can be solved by replacing the light diffusing plate of a general direct-type illumination device illustrated in FIG. 15 with the light control member proposed by us. In order to solve the above problems, in the present invention, by providing a convex portion having a suitable shape on the exit surface of the light control member, the use of the light diffusing material can be avoided or greatly reduced, and the light use efficiency can be improved. Thus, high brightness can be achieved. In addition, it is not only advantageous for size change but also alignment with the light source by giving a uniform property that similarly controls the outgoing direction of incident light at all points on the incident surface of the light control member. Is also unnecessary. Further, by making the light intensity distribution in the front direction constant, luminance unevenness in the front direction can be eliminated. Furthermore, the combined functions of the light control member, such as uneven brightness and improved brightness, can eliminate or reduce the use of other functional optical films, which is advantageous for productivity and thinning. Furthermore, it is also possible to increase the front strength by increasing the light emission ratio in the front direction of the light control member. In addition, an image display device can be obtained by disposing a transmissive display element on the emission side of these illumination devices. Here, the front direction means a small solid angle centered on the normal direction of the main surface of the light control member.

That is, the present invention for solving the above problems
It has a rectangular exit surface composed of an X direction and a Y direction perpendicular to the X direction,
A reflector, a plurality of linear light sources, and a plate-like light control member;
The reflector is arranged in parallel to the X direction and the Y direction,
The linear light source is disposed in one imaginary plane parallel to the X direction and the Y direction on the exit surface side of the reflector,
And, the linear light source has a longitudinal direction arranged parallel to the Y direction,
And it is arranged at equal intervals along the X direction,
The light control member is disposed on an emission surface side of the arranged linear light sources,
And the main surface is parallel to the virtual plane where the linear light sources are arranged,
The main surface of the light control member is composed of an incident surface that faces the linear light source and receives light from the linear light source, and an output surface that emits light received by the incident surface,
The emission surface has a plurality of ridge-shaped projections on the surface,
The convex portion is a lighting device in which a bowl-shaped ridge line corresponding to the top portion is formed in parallel to the Y direction, and arranged along the X direction,
The distance between the centers of the linear light sources is D, the distance between the center of the arbitrary linear light source and the light control member is H, and the X direction of the light incident on the light control member from one linear light source F (X) is a function representing the intensity of light emitted in the normal direction of the exit surface at the position coordinate X (where the light source position is X = 0),
g (X) = f (X−D) + f (X) + f (X + D) (1)
When
In the range of −D / 2 ≦ X ≦ D / 2,
The ratio g (X) _min / g (X) _{max of} g (X) _min that is the minimum value of g (X) and g (X) _max that is the maximum value is 0.6 or more,
The minimum value X _min of X is in the range of −3.0D ≦ X _min ≦ −0.5D, and the maximum value X _max is in the range of 0.5D ≦ X _max ≦ 3.0D (X _min and X _max are , F (X) is attenuated around a linear light source whose value is X = 0, and coordinates at both ends when it becomes substantially 0),
An illuminating device is characterized in that the cross-sectional shape in the X direction of an arbitrary convex portion is composed of (2N + 1) different regions −N to N expressed by the following formula.

δ = (X _max −X _min ) / (2N + 1) (2)
X _i = i × δ (3)
α _i = Tan- ¹ (X _i / H) (4)
β _i = Sin ⁻¹ ((1 / n) sin α _i ) (5)
γ _i = Sin ⁻¹ ((1 / n ₂ ) sin α _i ) (6)
_{a i αf (X i + T} · tanγ i) · cosΦ i · cosβ i / cos 2 α i / cos (Φ i -β i) (7)
Φ _i = Tan ⁻¹ ((n · sin β _i ) / (n · cos β _i −1)) (8)
N: Natural number
i: integer from -N to N
n: Refractive index of the convex portion of the light control member
n ₂ : Refractive index of the base material of the light control member
a _i : width of region i in X direction
Φ _i : Slope inclination with respect to the exit surface of region i
T: Thickness from the incident surface of the light control member to the bottom of the convex portion

  Moreover, this invention is said illuminating device, Comprising: The area | region -N-N showing the cross-sectional shape of the X direction of the said convex part is located in order of the coordinate of the X-axis, It is an illuminating device characterized by the above-mentioned. In addition, the cross-sectional shape in the X direction of the convex portion is a shape that approximates the shape inclination of at least one pair of two adjacent regions out of (2N + 1) different regions constituting the convex portion by a curve. In addition, in a cross section parallel to the normal direction of the main surface of the light control member in the X direction, the light is emitted within a range that forms an angle of 30 degrees or less with respect to the normal direction of the output surface. The illumination device is characterized in that the ratio of light to be emitted is 50% or more of the total light output.

Moreover, this invention is a light control member with which said illuminating device is provided.
Furthermore, the present invention is an image display device characterized in that a transmissive display element is provided on the exit surface side of the above-described illumination device.

  The means provided by the present invention will be described in detail below.

  An illuminating device provided in the present invention is an illuminating device having a rectangular emission surface composed of an X direction and a Y direction perpendicular to the X direction. The illuminating device includes a reflector, a plurality of linear light sources, a plate A light control member, and the reflector receives and reflects light from the linear light source and enters the light control member as diffused light, and receives and reflects the reflected light from the light control member and diffuses the light. It plays the role which makes it inject into a light control member again. The light control member is a member for eliminating luminance unevenness in the front direction. The plate shape is preferable because the apparatus can be thinned and an appropriate mechanical strength can be secured. If the distribution of the outgoing light intensity is substantially constant, the luminance unevenness is eliminated and the luminance uniformity is obtained. In the illuminating device in which the linear light sources are arranged as described above, the distribution of the light output intensity is the sum of the distribution of the light output intensity of each linear light source, and if the distribution becomes almost constant at an arbitrary position on the observation surface side, the luminance Unevenness is eliminated.

  The illuminating device of the present invention eliminates uneven brightness in the front direction by making the light intensity distribution in the front direction substantially constant.

  Invention of Claim 1 is the said illuminating device, Comprising: The said reflecting plate is arrange | positioned in parallel with the said X direction and a Y direction, The said linear light source is the said X direction of the output surface side of the said reflecting plate. Arranged in one virtual plane parallel to the Y direction, and the linear light sources are arranged such that the longitudinal direction thereof is parallel to the Y direction and arranged at equal intervals along the X direction. Yes. The light control member is arranged on the emission surface side of the arranged linear light sources, and the main surface is parallel to the virtual plane on which the linear light sources are arranged.

  Since the main surface and the virtual plane on which the linear light source is arranged are parallel, the distance from the linear light source to the light control member becomes uniform, so that each linear light source enters the light control member. The distribution of the light intensity is uniform, and the distribution of the entire incident light intensity is a periodic distribution according to the position of the linear light source along the X direction, which is the arrangement direction of the linear light sources. It is easy to eliminate.

The main surface of the light control member includes an incident surface that faces the linear light source and receives light from the linear light source, and an output surface that emits light received by the incident surface.
The emission surface has a plurality of hook-shaped protrusions on the surface, and the protrusions have hook-shaped ridgelines corresponding to the tops formed in parallel to the Y direction and arranged along the X direction. . The convex portion serves to control the light from the linear light source and to make the distribution of the emitted light intensity in the front direction of the emitted light constant. The ridge-shaped ridgeline corresponding to the top of the convex portion is arranged in parallel to the Y direction, that is, the convex portions are positioned in parallel, and the linear light source is formed between the entrance surface and the exit surface, which are the main surfaces of the light control member. Since it is arranged in parallel with the arranged virtual plane, it is possible to efficiently receive light from the linear light source on the main surface and to control the direction of the light in the X direction in which the luminance unevenness is remarkable. In the direct illumination system, the luminance unevenness is most noticeable in the X direction perpendicular to the longitudinal direction of the linear light source. On the other hand, the illumination apparatus of the present invention makes the convex shape of the light control member suitable. Therefore, it is characterized in that the distribution of the intensity of light emission in the front direction is made constant, and uneven brightness in the front direction is eliminated, and the ability is highest in the direction in which the width of the convex portion is the smallest. By providing the bowl-shaped ridge line corresponding to the top of the light source in parallel with the linear light source, that is, in parallel with the Y direction, the luminance unevenness can be efficiently eliminated.

  In addition, by arranging the convex parts of the same shape in parallel, the optical properties of the light control member become uniform, so alignment is not necessary, and it is also possible to change the display size, the number of linear light sources and the arrangement The lighting device can be manufactured immediately and can be manufactured with high productivity. Therefore, for example, since it is possible to cut out an arbitrary position of a large plate-shaped molded article having a desired convex portion created by a large extrusion molding machine to an arbitrary size to be a light control member, it is only advantageous in production. In addition, it can easily cope with the size change of the lighting device.

The light from the linear light source and the light from the linear light source reflected by the reflecting plate are incident on the incident surface of the light control member. Among these, with respect to light incident on the light control member from the linear light source, the distance between the centers of the linear light sources is D, and the distance between the center of the arbitrary linear light source and the light control member is H. When the position coordinate X in the X direction and the intensity of light emission in the normal direction of the exit surface, which is the front direction, are expressed as f (X) where the light source position is X = 0,
g (X) = f (X−D) + f (X) + f (X + D) (1)
When
In the range of −D / 2 ≦ X ≦ D / 2,
The ratio g (X) _min / g (X) _{max of} g (X) _min that is the minimum value of g (X) and g (X) _max that is the maximum value is 0.6 or more. .

  In the illumination device of the present invention, the same linear light source is used. Therefore, the function g (X) is the sum of f (X) for three adjacent linear light sources. The range of −D / 2 ≦ X ≦ D / 2 is a range up to an intermediate point between each of the central linear light source and the adjacent linear light source, and g (X) regarding any three adjacent linear light sources. When the above condition is satisfied, the luminance unevenness in the front direction can be eliminated over the entire surface.

Since light is received under the same conditions for each period of the linear light source, and the light control member controls the same light output direction for light incident on an arbitrary point on the incident surface, it is equivalent to one period -D / 2 By controlling the distribution of the light emission intensity in the range of ≦ X ≦ D / 2, the distribution of the whole light emission intensity can be controlled.
Further, as described above, the distribution of the light intensity is the sum of the distributions of the light intensity of the respective linear light sources. If the distribution becomes almost constant at any position on the observation surface side, the luminance unevenness is eliminated. The illuminating device of the present invention eliminates uneven brightness in the front direction by making the light intensity distribution in the front direction substantially constant.

Since the light intensity of the linear light source is inversely proportional to the distance, the influence of the light from the distant linear light source is small. For this reason, by setting the function g (X) considering only the light output intensities from the three adjacent linear light sources within an appropriate range, the distribution of the light output intensity in the front direction can be controlled, and the luminance unevenness in the front direction can be reduced. Can be resolved. By setting g (X) to a range in which the ratio g (X) _min / g (X) _{max of} g (X) _min that is the minimum value and g (X) _max that is the maximum value is 0.6 or more, Due to the effect of the reflector, the actual light intensity distribution is made more uniform, and the sum of the light intensity distributions in the front direction of each linear light source is almost constant at any position on the observation surface side. Can be resolved.

  FIG. 9 is a diagram showing f (X) and g (X) of the illumination device of the present invention in which linear light sources are arranged with D = 30 mm shown for f (X) in FIG. The position coordinate in the X direction of the linear light source located at the center is set to 0, and the distance (mm) in the X direction is set to the X coordinate.

Furthermore, the present inventors have found out the shape of the convex portion for making the distribution of the light emission intensity in the front direction substantially uniform. That is, in the present invention, the minimum value X _min of the minimum value X _min is X of X is in a range of -3.0D ≦ X _min ≦ -0.5D, the maximum value X _max is 0.5 D ≦ X _max ≦ 3 The cross-sectional shape in the X direction of any convex portion is a range of 0.0D, and is composed of (2N + 1) different regions −N to N expressed by the following formulas (2) to (8). Features. Of these, the region 0 has an inclination of 0, that is, parallel to the incident surface, and can efficiently emit light incident from directly below in the front direction.

δ = (X _max −X _min ) / (2N + 1) (2)
X _i = i × δ (3)
α _i = Tan- ¹ (X _i / H) (4)
β _i = Sin ⁻¹ ((1 / n) sin α _i ) (5)
γ _i = Sin ⁻¹ ((1 / n ₂ ) sin α _i ) (6)
_{a i αf (X i + T} · tanγ i) · cosΦ i · cosβ i / cosα i / cos (Φ i -β i) (7)
Φ _i = Tan ⁻¹ ((n · sin β _i ) / (n · cos β _i −1)) (8)
N: Natural number
i: integer from -N to N
n: Refractive index of the convex portion of the light control member
n ₂ : Refractive index of the base material of the light control member
a _i : width of region i in X direction
Φ _i : Slope inclination with respect to the exit surface of region i
T: Thickness from the incident surface of the light control member to the bottom of the convex part Here, the angles of α, β, γ, Φ, etc. are all absolute values of less than 90 °, and are angles formed clockwise with respect to the reference line. Positive and counterclockwise angles are negative.

First, equation (7) will be described with reference to FIG.
X _min and X _max are the coordinates of both ends when the value of f (X) attenuates around the vicinity of the linear light source where X = 0 and becomes substantially zero. When X _{min to} X _max are equally divided (2N + 1), the width δ of each divided element is expressed by Expression (2). At this time, the center coordinates X _i of an arbitrary element are expressed by Expression (3). Incident angle from the linear light source at the position of X = 0 to the incident surface of the light control member of coordinate X _i is the angle alpha _i represented by the formula (4) with respect to the normal direction.

Here, the light is refracted and travels inside the light control member at an angle γ _{i represented} by Expression (4) with respect to the normal direction. When the bottom of the convex portion is reached, the light is refracted again, travels inside the light control member at an angle β _{i represented} by Expression (5), and enters the convex portion 3. Here, the refractive index of the light control member and the substrate on which the convex portions are provided may be the same. In this case, the light is not refracted at the bottom of the convex portion, and β _i = γ _i .
Among them, only the light that has reached the slope of the inclination Φ _i with respect to the emission surface represented by the equation (8) is directed in the front direction.

Here, the length of the slope of the area i occupied by the slope of the angle Φ _i is b _i, and the length of the projection from the slope of the area i in the direction perpendicular to the light ray direction inside the convex portion of the light control member is e When _i, the angle of the inclined surface area i in the normal direction parallel to a cross-section of the main surface of the X-direction and the light control member, forms with the beam direction perpendicular angles within the convex portion of the light control member Since the angle ξ _i is (Φ _i −β _i ),
e _i = b _i · cos (Φ _i −β _i ) (9)
It becomes.

Here, if the length of the projection onto the plane parallel to the incident surface of the region i occupied by the slope of the angle Φ _i , that is, the width of the region i in the X direction is a _i ,
b _i = a _i / cosΦ _i (10)
It is.

From equation (9) and equation (10), e _i = a _i / cosΦ _i · cos (Φ _i −β _i ) (11)
It becomes.
Here, as shown in FIG. 17, when the width in the X direction of the convex portion, that is, the sum of a _i is P, the convex portion 3 enters the light control member 2 at an angle α _i and passes through the inside of the light control member. The proportion of the light 9 going to the region i out of the light 9 going to is e _i / (P · cos β _i ).

On the other hand, the intensity of light per unit area incident on the light control member at the angle α _i , that is, the illuminance, is proportional to cos ² α _i as described later.
Further, as shown in FIG. 18, the angle [Delta] [alpha] _i anticipating the diameter of the light source in the point of coordinates X _i is proportional to cos [alpha] _i. Accordingly, the intensity of light per unit area unit angle incident on the coordinate X _i is proportional to cos ² α _i / Δα _i , and from this, is proportional to cos ² α _i / cos α _i , that is, cos α _i . In other words, the light from the linear light source per unit angle of the light incident on the unit convex portion at the point of the coordinate X = X _i with respect to the intensity per unit angle of light incident on the unit convex portion at the point of X = 0. The intensity ratio is cosα _i . Thus, the light exiting the front is _{cosα i · e i / (P} · cosβ i), a i / cosΦ i · cos (Φ i -β i) from equation _{(11) · cosα i / (} P · cosβ _i ).

The light incident on the coordinate X _i is emitted at the coordinate (X _i + T · tan γ _i ) when the thickness of the light control member 2 is T. Therefore, the intensity of the emitted light in the front direction at that time is f (X _i + T Tan γ _i ).

Furthermore, since the light emission intensity in the front direction is proportional to the emission intensity of the linear light source and the emission ratio in the front direction,
_{f (X i + T · tanγ} i) αa i / cosΦ i · cos (Φ i -β i) · cosα i / (P · cosβ i) (12)
According to
_{a i αP · f (X i} + T · tanγ i) · cosΦ i · cosβ i / cosα i / cos (Φ i -β i) (13)
It becomes. Here, if the width of the convex portion 3 is P, the sum of a _i becomes the width P of the convex portion.

It becomes.
P is the convex width and is a constant.
_{a i αf (X i + T} · tanγ i) · cosΦ i · cosβ i / cosα i / cos (Φ i -β i) (7)
The convex portion has a shape composed of a region i having a width a _i that satisfies the relationship of (Expression 7). As is well known, since the proportional reduction optical system exhibits almost the same directivity characteristics, the pitch of the convex portions can be freely selected.

Here, the relationship between the incident angle to the light control member and the incident intensity will be described with reference to FIG.
Considering the minute angle Δθ centering on the incident angle θ from the linear light source to the light control member, the following equations (15), (16), and (17) are established when Δθ is sufficiently small.

U = H '· Δθ (15)
H ′ = H / cos θ (16)
V = U / cos θ (17)
Therefore, V = H · Δθ / cos ² θ (18)
That is, since V is inversely proportional to cos ² θ, when the intensity of the emitted light within Δθ from the linear light source is constant regardless of θ, the intensity of incident light per unit area to the light control member, that is, the illuminance Is proportional to cos ² θ.

Next, equation (8) will be described.
FIG. 6 shows the principle of directing light to the front in the lighting device of the present invention.
Incident light 7 that enters the light control member 2 having a refractive index n from the linear light source at an angle α is refracted by the incident surface 6 of the light control member, passes through the inside of the light diffusion plate, and this light 9 is The light is refracted by the convex portion 3 on the emission surface side and emitted to the observation surface side. At this time, the emitted light 8 is emitted in the front direction when the inclination of the convex portion 3 is a desirable angle Φ. In the present invention, the light emission intensity in the front direction can be adjusted by adjusting the ratio of the angle Φ so that the light emission intensity in the front direction is constant in consideration of the distribution of α based on the arrangement and the intensity of the incident light 7.

  The inclination Φ of the projection 3 on the exit surface for directing the incident light 7 is determined by the refractive index of the light control member 2 and the incident angle of light on the light control member 2. The incident angle of light on the incident surface 6 with respect to the normal of the incident surface 6 is α, and the light that is refracted at the incident surface 6 and passes through the convex portion 3 inside the light control member is relative to the normal of the incident surface 6. The angle formed by β, the angle formed by the light traveling inside the light control member with respect to the normal of the slope on the exit side, ε, the light being refracted on the slope on the exit side and the normal of the slope of the light emitted to the observation surface side And ω and the refractive index of the light control member is n. At this time, let Φ be the angle of the slope of the convex portion so that the light exiting the exit surface travels in the front direction, which is the normal direction of the entrance surface.

At this time, the following relationship is established.
β = Sin ⁻¹ (1 / n · sin α) (5) ′
Φ = β−ε (19)
−n · sinε = −sinω = sinΦ (ω = −Φ) (20)
From equation (19) and equation (20),
−n · sin (β−Φ) = sinΦ (21)
−n · {sinΦ · cosβ−cosΦ · sinβ} = sinΦ (21) ′
Dividing both sides of equation (21) 'by cosΦ (since sinΦ / cosΦ = tanΦ)
−n {tanΦ · cosβ−sinβ} = tanΦ (21) ”
From this, Φ can be expressed as follows.
Φ = Tan ^-1 (n · sinβ) / (n · cosβ-1)) (21) '''
From Equation (5) 'and Equation (21)''', Φ = Tan ^-1 (sin α / (n · cos (Sin ⁻¹ ((1 / n) sin α)) − 1)) (21) ″ ″

α, n, and Φ have such a relationship, and light having a desired incident angle α can be emitted in the front direction by the refractive index n of the light control member 2 and the inclination Φ of the convex portion 3. By the equation (21) ′ ″, the inclination Φ _i of each region of the convex portion satisfies the equation (8), so that the light incident on the incident surface at the angle α _i is emitted in the front direction from the region i of the convex portion. Can explain what can be done.

As described above, the slope Φ _i of the convex region _i and the width a _{i in the} X direction occupied by the convex region i, which are important factors that determine the shape of the convex portion, in the distribution f (X) of the desired intensity of light emission in the front direction are as follows. The linear light source is selected based on the arrangement of the linear light source and the refractive index of the light control member.

  Invention of Claim 2 is the illuminating device of Claim 1, Comprising: The area | region -N-N showing the cross-sectional shape of the X direction of the said convex part is located in order of the coordinate of X, It is characterized by the above-mentioned. It is an illuminating device. At this time, the cross-sectional shape of the unit convex portion has no inflection point, and the entire convex portion is substantially convex. When there are many inflection points, the light reaches the region on another convex part before reaching the region on the desired convex part, and the direction of the light beam is changed by reflection or refraction, and the light emission direction is controlled. May be difficult. In addition, since the shape having no inflection point is simpler than the shape having the inflection point, it is easy to shape and advantageous in production.

Invention of Claim 3 is an illuminating device in any one of Claim 1, 2, Comprising: The cross-sectional shape of the X direction of the said convex part differs in (2N + 1) inclination which comprises this convex part. The illumination device is characterized in that the shape of at least one pair of two adjacent regions in the region is a shape approximated by a curve. The convex portion described in claim 1 is composed of (2N + 1) inclined surfaces having an angle Φ _i , and shows a shape obtained by approximating the shape of at least one pair of two adjacent regions by a curve. This is desirable because the distribution of the light emission intensity in the front direction and the distribution of the light emission angles become smoother. Moreover, since it is easier to form, it is advantageous when producing a light control member. Furthermore, it is also desirable that the bonded portion of the region is not easily broken because it is not a sharp shape. The breakage of the joint is undesirable because it may cause a change in the light emission direction and unnecessary scattering.

Invention of Claim 4 is an illuminating device in any one of Claims 1-3, and is normal of an output surface in the cross section parallel to the normal direction of the X direction and the main surface of a light control member. The illumination device is characterized in that a ratio of light emitted in a range that forms an angle within 30 degrees with a direction is 50% or more of the total light output. Since the illumination device has a relatively high light emission ratio in the front direction, bright illumination light can be efficiently obtained in applications such as a television or a personal computer monitor that mainly observe the illumination surface from the front direction. In the cross section parallel to the X direction and the normal direction of the main surface of the light control member, the ratio of the light emitted in a range that forms an angle of 30 degrees or less with the normal direction of the output surface is the convexity of the light control member. It can be adjusted by adjusting the angle of the slope of the part. The angle of the slope of the convex portion can be adjusted by adjusting the width of X _{max to} X _min .

  Invention of Claim 5 is a light control member with which the illuminating device in any one of Claims 1-4 is provided. The light control member has a plate shape having an entrance surface and an exit surface as main surfaces, and part of the light incident on the entrance surface from the entrance surface side is reflected and part of the light is transmitted. By this function, the luminance unevenness of the emitted light is reduced. The light that passes through the incident surface is refracted at the incident surface, collected near the normal direction of the incident surface, and travels toward the exit surface. The light transmitted through the incident surface and directed to the convex portion of the output surface is refracted according to the inclination of each region of the convex portion. Light that is directed to an area of the appropriate angle is directed in the front direction. Further, by appropriately selecting the ratio of each region of the convex portions having different inclinations, it is possible to make the light emission intensity in the front direction at a point on an arbitrary light exit surface constant. Due to the functions of the entrance surface and the exit surface convex portion described above, it is possible to eliminate uneven brightness of the exit light in the front direction, which is the normal direction of the exit surface, with various configurations in which a linear light source is disposed on the entrance surface side.

  A sixth aspect of the present invention is an image display device characterized in that a transmissive display element is provided on the exit surface side of the illumination device according to any one of the first to fourth aspects. The lighting device is a lighting device in which the distribution of the light emission intensity in the front direction is constant and the distribution of the light emission intensity in the front direction is uniform, and the ratio of the light emission intensity in the front direction can be increased. By providing a transmissive display element, it can be used as a preferred image display device. Here, the image display device refers to a display module in which a lighting device and a display element are combined, and a device having at least an image display function such as a television or a personal computer monitor using the display module.

  The light intensity distribution in the front direction can be evaluated by measuring the front luminance distribution. The distribution of front luminance is measured while moving the luminance meter at equal intervals in the X direction with the distance between the luminance meter and the measurement point on the light exit side of the light control member kept constant. In the measurement of the light emission ratio in the front direction, first, the luminance of the measurement point is measured while changing the angle. At this time, the angle is changed along a cross section parallel to the normal direction of the main surface of the light control member and the X-axis direction. At this time, the distance between the luminance meter and the measurement point on the emission surface side of the light control member is kept constant. Next, the obtained luminance value for each angle is converted into an energy value, and the ratio of the energy emitted within 30 degrees to the front direction, which is the normal direction of the main surface of the light control member, is calculated. .

  The present invention provides an illumination device that has high light utilization efficiency and has a constant light intensity distribution in the front direction in the direct system, so that there is no luminance unevenness in the front direction such as a lamp image. Moreover, the light emission rate in the front direction is as high as 50% or more, and high front luminance can be obtained. Further, by approximating the cross-sectional shape of the convex portion with a curve, a smooth distribution of the light emission intensity in the front direction and a desirable distribution of the light emission angles can be obtained. Moreover, it can respond also to thickness reduction by making a linear light source and another member close, or simplifying a film structure. Furthermore, since the same optical control can be performed on the light incident on the incident surface at any place, alignment between the linear light source and the light control member is unnecessary, and the display size and linear shape are not required. Changes in the number and arrangement of light sources can be handled immediately, and a lighting device can be manufactured with high productivity. In addition, an image display apparatus using the same is provided.

  FIG. 1 shows an example of the best mode of a lighting device provided by the present invention. An illumination device having a rectangular emission surface composed of an X direction and a Y direction perpendicular to the X direction, wherein the linear light source 1 is arranged in a Y virtual direction in one virtual plane parallel to the X direction and the Y direction. The light control member 2 is arranged on the emission surface side of the arranged linear light sources, and the main surface is arranged in the virtual direction where the linear light sources 1 are arranged. It is parallel to the plane, and a plurality of protrusions 3 on the surface are formed on the surface on the exit surface side, and the protrusion 3 has a ridge-like ridgeline corresponding to the top formed in parallel to the Y direction, and X It is the illuminating device arranged along the direction. It is desirable that the reflectance of the reflector 4 arranged on the back surface in parallel with the X direction and the Y direction is 95% or more. By reflecting the light traveling from the linear light source 1 to the back surface and the light reflected by the light control member 2 and traveling toward the back surface further to the emission side, the light can be used effectively, so that the light utilization efficiency is increased. Examples of the material of the reflecting plate include metal stays such as aluminum, silver, and stainless steel, white coating, and foamed PET resin. A reflector having a high reflectance is desirable for improving the light utilization efficiency. From this viewpoint, silver, foamed PET resin, and the like are desirable. Further, it is desirable to diffuse and reflect light in order to improve the uniformity of the emitted light. From this viewpoint, foamed PET resin and the like are desirable.

Since the linear light source of the present invention is disposed so as to be sandwiched between the reflector and the light control member, about half of the light emitted from the linear light source is directed toward the light control member and the remaining half is about half. Heads toward the reflector. Among these, the light diffusely reflected by the reflecting plate toward the reflecting plate enters the light control member as diffused light. Further, part of the light incident on the light control member from the linear light source is totally reflected and travels toward the return reflector. The light emitted from the linear light source toward the reflection plate and the light totally reflected by the light control member and directed toward the return reflection plate are diffusely reflected by the reflection plate and enter the light control member again as diffused light. The incident light as the diffused light is emitted as light having the same front luminance and angular distribution at all points on the emission surface of the light control member. Therefore, the ratio G (X) _min / G (X) between the minimum value G (X) _min and the maximum value G (X) _max of the emitted light intensity in the front direction when the diffused light is included in the state where the reflector is disposed. ) _Max is greater than the ratio g (X) _min / g (X) _max when no reflected light is included. Further, by appropriately selecting the reflector, 50% or more of the light incident on the light control member becomes diffuse light.

The brightness unevenness eliminating effect by the reflector will be briefly estimated below. It is assumed that 50% of the light emitted from the linear light source is diffusely reflected by the reflector and then enters the light control member. If the reflectance of the reflector is 95%, 95% of the same amount of light emitted from the linear light source toward the light control member in the front direction is reflected by the reflector from the linear light source and then diffused light The light enters the light control member and exits in the front direction. Assuming that the light emitted from the linear light source toward the light control member in the front direction is the average of g (X) _max and g (X) _min , (g (X) _max + g (X) _min ) / 2 × 0.95 is reflected by the reflector from the linear light source, enters the light control member as diffused light, and exits in the front direction. This is added to g (X) _max and g (X) _min , respectively, and G (X) _min which is the minimum value of the light output intensity when the reflector is arranged, G (X) _max which is the maximum value and When the ratio ratio G (X) _min / G (X) _max is obtained, it is as follows.

G (X) _max = g (X) _max + (g (X) _max + g (X) _min ) /2*0.95 (22)
G (X) _min = g (X) _min + (g (X) _max + g (X) _min ) /2×0.95 (23)
G (X) _min / G (X) _max
= {G (X) _min + (g (X) _max + g (X) _min ) /2×0.95} /
{G (X) _max + (g (X) _max + g (X) _min ) /2×0.95} (24)

In order for the ratio G (X) _min / G (X) _{max to} be 0.8 or more,
g (X) _min / g (X) _max ≧ 0.65 (25)
It becomes.
As described above, since the diffused light component is actually 50% or more of the incident light to the light control member,
g (X) _min / g (X) _max > 0.6 (26)
You can see that.

  FIG. 16 is a diagram illustrating the relationship between the light output intensity in the front direction and the position of the linear light source when the linear light sources are arranged in parallel. As shown here, in an illuminating device in which a plurality of linear light sources 1 are arranged, the intensity of light emitted in the front direction (up in the drawing) is the portion directly above each linear light source 1 and the portion directly above it. And the portion directly above each of the adjacent linear light sources 1 (an oblique upper portion) is greatly different. This means that in the illumination device of the present invention, the incident intensity in the front direction of the light control member on the incident surface is greatly different between the portion directly above each linear light source 1 and the oblique upper portion.

  FIG. 2 is a diagram showing the relationship between the position of the linear light source and the intensity of light emitted in the front direction in the illumination device of FIG. As described above, since the distribution of the intensity of light emission in the front direction is substantially constant, the luminance unevenness in the front direction is eliminated.

  FIG. 3 is a diagram showing the positions of the linear light sources and the distribution of the light output intensity in the respective frontal directions when three adjacent linear light sources and reflectors are arranged. If these sums are almost constant, it can be said that the luminance unevenness in the front direction has been eliminated. As shown in FIG. 2, the light intensity distribution in the front direction becomes almost constant by the light control member 2 of the present invention, so that luminance unevenness in the front direction is eliminated.

FIG. 7 shows an example of the distribution in the X direction of the intensity of light emitted in the front direction by light from any one linear light source of the illumination device of the present invention in which linear light sources are arranged with D = 30 mm. Light emitted in the front direction by light from one linear light source is in the range of X _{min to} X _max . In the case of showing gentle attenuation as shown in FIG. 7, for example, the value of X when the value of f (X) is 1/100 of the maximum value can be substituted. The values of f (X) for determining X _min and X _max are preferably the same, and if it is 1/20 or less of the maximum value, there is no problem, and 1/100 or less is more desirable. In FIG. 7, X _min = −3D and X _max = 3D, and f (X _min ) = f (X _max ) is 1/100 or less of f (X). In such a shape, since the intensity of light emission in the front direction is not strictly determined by the sum of only three adjacent ones, g (X) is not constant but g (X) near the center where X = 0. It is desirable that is slightly higher than the surrounding area.

In FIG. 8, linear light sources are arranged with D = 30 mm as in FIG. 7, and in the front direction by light from any one linear light source in the illumination device of the present invention using another light control member. 2 shows an example of the distribution in the X direction of the intensity of emitted light. In this example, X _min = −D and X _max = D. Depending on the shape of the convex portion, light having a certain incident angle or more does not travel forward, and thus the light emission intensity is suddenly reduced at a portion away from the linear light source to some extent. In such a shape, since the intensity of light emission in the front direction is determined by the sum of only three adjacent ones, it is most desirable that g (X) is constant. At this time, light exits in the front direction in the range of X _{min to} X _max , and its distribution is f (X). When the case where X _min = −3D and X _max = 3D shown in FIG. 7 is compared with the case where X _min = −D and X _max = D shown in FIG. 8, the convex portion width is limited. The distribution of the intensity of light emission in the front direction is determined by the distribution of the inclination angle Φ of the slope. As shown in FIG. 8, the convex shape has a slope angle that directs light with low energy incident in an oblique direction from a far direction to the front direction, but an angle Φ that directs light from a far direction to the front as shown in FIG. Instead, the front luminance is improved in the convex shape formed by the angle Φ in which only the light incident in the range of −D <X <D is directed to the front. Thus, reducing the width of X _{max to} X _min has the effect of increasing the ratio of light emission in the front direction by efficiently directing stronger light to the front.

On the other hand, increasing the width of X _{max to} X _min has the effect of increasing the light emission ratio in the front direction by directing the light of a distant linear light source to the front. Therefore, in order to increase the front luminance, it is desirable that the width of X _{max to} X _min be in an appropriate range. Desirable widths of X _{max to} X _min vary depending on f (X). For example, a range of X in which the light emission intensity is ½ or more of the maximum value can be used as a guide. It is desirable to take the width of this range is large when the X _max to X _min relatively large, it is desirable to take small smaller. Width of the thus X _max to X _min can increase the front luminance in suitably determined that the.

FIG. 10 shows g (X) of the illumination device shown for f (X) in FIG. As already shown, if g (X) is constant within the range of −D / 2 ≦ X ≦ D / 2, which is one cycle of the linear light source, the luminance unevenness in the front direction is eliminated, and X _min , X _max is optimal, the light with high energy in the vicinity of the linear light source is directed to the front, and thus the brightness in the front direction is higher.

The arrangement order of the regions -N to N is not necessarily along the X axis. However, if this is not the case, there will be an inflection point in the convex part due to the arrangement of each region, and before reaching the slope of the convex part at angle Φ _i that directs the light incident at angle α _i to the front rays direction depends reach refracted or reflected in a different angle of slope, may not reach the slant angle [Phi _i, by or to reach the slope angle in undesirable angle [Phi _i, the emission direction of the light Control may be difficult and performance may be insufficient. When the -N to N regions are arranged in the order of the position coordinates of the X axis, the shape of the convex portion is usually a shape having no inflection point, and the entire convex portion is substantially convex. In the case of such a shape, the direction of the light beam usually does not change due to reflection or refraction by reaching the region on another convex part before the light reaches the region on the desired convex part. This is easy and advantageous.

The lighting the width a _i in the X direction of each region of protrusions is proportional to _{f (X i + T · tanβ} i) · cosΦ i · cosβ i / cosα i / cos (Φ i -β i) is of the present invention Although it is a feature of the apparatus, the preferred width may slightly deviate due to the influence of the height from the bottom of the convex part to the surface, but there is no significant influence.

  Here, FIG. 12 is a sectional view showing the arrangement of the light control member 2 and the linear light source 1. In the figure, a thickness T from the incident surface 6 to the bottom of the convex portion, a distance H from the center of the linear light source 1 to the incident surface 6 of the light control member 2, and a distance D between the centers of the linear light sources 1 are shown. The thickness T from the incident surface 6 to the bottom of the convex portion is preferably 1 mm to 3 mm. If T is small, the thickness of the light control member becomes thin and the thickness of the lighting device is also thin, which is desirable. However, if it is too thin, the strength will be weak, and control will not be possible due to the change in the light output direction. Will occur. In addition, the mechanical strength is weakened and there is a possibility of breakage. On the other hand, if the thickness is too large, the thickness of the lighting device is increased, which is not desirable because it is contrary to the demand for thickness reduction.

  N is preferably 2 or more. When N is large, the convex portion has a complicated shape composed of many inclinations. When the number of inclinations is large, the light emission in the front direction can be controlled efficiently and accurately, and the uniformity of the light emission intensity distribution in the front direction is high. In terms of accuracy, N should be large, but if it is too large, the shape becomes complicated and it becomes difficult to produce. From the viewpoint of ease of creation, N is preferably 100 or less, and more preferably 10 or less.

  You may approximate the shape of at least 1 set of adjacent area | regions among the area | regions which form a convex part with a curve. Further, the shape of two or more adjacent regions may be approximated by a curve. Further, the shape of three or more adjacent regions may be approximated by a curve, and the shape of the entire convex portion may be approximated by a curve. FIG. 11 is a diagram illustrating an example of a cross-sectional shape in the X direction of the light control member when the shape of the entire region of the convex portion is approximated by a curve. Approximating the shape of many areas with a curve approximates the shape of adjacent areas such as smoothing out the light intensity distribution and light angle distribution in the front direction, easy to shape, and difficult to break. This is more effective and desirable. The approximation method to the curve is not particularly limited, and a generally well-known least square method, spline interpolation method, Lagrange interpolation method, or the like can be used. As the points used for approximation, at least one point is selected from the approximated region. Usually more than the number of approximated areas. For example, it is possible to select both ends of a plurality of continuous regions and contact points of each region. In addition, the midpoint of each region can be used for approximation.

  In a cross section parallel to the normal direction of the X direction and the main surface of the light control member, the proportion of light emitted at an angle within 30 degrees with the front direction that is the normal direction of the exit surface is 50% or more Is a lighting device with high front luminance. In a display device such as a personal computer that requires high front luminance, 60% or more is more desirable, and 80% or more is more desirable. On the other hand, for a display device that requires a wide viewing angle, such as a lighting signboard, if the light emission ratio in the front direction is too high, the light is directed only in the front direction and the viewing angle becomes narrow. For this reason, 60 to 80% is desirable.

  As shown in FIG. 12, in the illuminating device of the present invention, the linear light source is arranged in the same plane at a distance D parallel to the Y direction, and the incident surface of the light control member is arranged at a position separated by H. Here, a smaller D is desirable because the distribution of the intensity of light emission in the front direction is constant. However, if D is too small, the number of linear light sources increases and energy consumption increases when the screen size is the same. A desirable range of D is 10 mm to 100 mm, and a more desirable range is 15 mm to 50 mm. Further, it is desirable that H is large because the distribution of the light emission intensity in the front direction is constant. However, if H is too large, the thickness is increased, which is not desirable because it is contrary to the thinning required for the lighting device. A desirable range of H is 5 mm to 50 mm, and a more desirable range is 10 mm to 30 mm. Further, the ratio D / H is preferably 0.5 to 3 and more preferably 1 to 2 in view of the balance between D and H.

  As for the height of the convex part formed on an output surface, 1 micrometer-500 micrometers are desirable. When the thickness is larger than 500 μm, the convex portion is easily confirmed when the emission surface is observed, and the quality is deteriorated. On the other hand, if the thickness is smaller than 1 μm, coloring occurs due to the diffraction phenomenon of light, and the quality deteriorates. Furthermore, in the image display device of the present invention in which the transmissive liquid crystal panel is provided as the transmissive display device element, the width P of the convex portion in the X direction is 1/100 to 1 / 1.5 of the pixel pitch of the liquid crystal. It is desirable. If it is larger than this, moire occurs with the liquid crystal panel, and the image quality is greatly reduced.

  Although there is no restriction | limiting in shaping | molding a convex part, Extrusion molding, injection molding, 2P shaping | molding using an ultraviolet curable resin, etc. are mention | raise | lifted. The molding method may be appropriately used in consideration of the size of the projection, the required shape, and mass productivity. When the main surface size is large, extrusion molding is suitable.

  In addition, the normal convex portions are continuously arranged, but a flat portion may be provided between the convex portions. Providing the flat portion is advantageous because the convex portion of the mold is difficult to deform. In addition, since the light directly above the linear light source is emitted in the front direction, it is effective when only the luminance immediately above the linear light source is increased. On the contrary, in the case of a shape having no flat part, all the light can be controlled by the inclination angle of the slope of the convex part, so that the light intensity distribution in the front direction becomes uniform.

  Moreover, it is desirable that the convex portions have the same shape. Since the optical properties of the light control member are uniform, alignment is not necessary, and it is possible to immediately respond to changes in the display size, the number of linear light sources and the arrangement, and the lighting device can be manufactured with high productivity. .

  The light control member can be desirably used as long as it is a material usually used as a base material of an optical material, and usually a light-transmitting thermoplastic resin is used. For example, methacrylic resin, polystyrene resin, polycarbonate resin, cycloolefin resin, methacryl-styrene copolymer resin, cycloolefin-alkene copolymer resin and the like can be mentioned.

Further, by providing the light diffusing means, it is possible to further improve the uniformity of luminance.
As the light diffusing means, a method of providing random irregularities such as embossing or embossing on the main surface of the plate member, a method of dispersing a small amount of light diffusing material inside the structure, a diffusion sheet on the incident side of the light control member and / or Or the method of providing in the output side, or the method of combining these is mentioned.

  The formation of random irregularities can be realized by applying a solution in which fine particles are dispersed to the main surface or transferring from a mold having irregularities. These are preferably provided on the exit surface side rather than the light source side, and can be provided on the light source side and / or the exit surface side of the light control member. As for the degree of unevenness, the arithmetic average roughness Ra is desirably 3 μm or less. If it becomes larger than this, the diffusion effect becomes too large, and the front luminance is lowered. When the incident surface is flat, light incident from various directions is condensed to some extent near the front due to refraction at the incident surface when entering the light control member. As a result, the light emission ratio in the front direction is increased. Increase. For example, when the refractive index of the light control member is 1.55, the light is condensed in an angle range within 40 degrees with respect to the normal direction of the incident surface. When unevenness is given to the incident surface, the light incident on the light control member is refracted at a wide angle and proceeds, so that the effect of increasing the light emission ratio in the front direction may be reduced. Moreover, when providing a fine unevenness | corrugation in an output surface, the effect which increases the light emission ratio to a front direction by an unevenness | corrugation similarly may be reduced by being refracted by an uneven surface. It can be adjusted to a range desired for the intended use from the balance between the obtained diffusibility and luminance unevenness eliminating effect and front luminance.

  When the light diffusing material is dispersed inside the structure, the concentration of the light diffusing material can be kept relatively low. Thereby, it is possible to suppress a decrease in transmittance and front luminance. Although the suitable concentration of the light diffusing material varies depending on the material, transmittance and haze can be used as a guide. It is desirable to use at a concentration such that the transmittance is 80% or more and the haze is 50% or less. For example, siloxane polymer particles (for example, Tospearl 120: manufactured by GE Toshiba Silicone Co., Ltd., number average particle diameter: 2 μm, CV value: 3%) as a light diffusing material are 0.04 Wt% on an MS polymer having a thickness of 2 mm. A molded plate or the like that contains it can be used.

  The light control member of the present invention can be made using a plurality of different materials as required. For example, after forming a convex part on a film, a support plate can be match | combined with the film surface which does not form a convex part, and it can also be set as a light expansion control member. For example, in the case of using an ultraviolet curable resin for forming the convex portion, it is possible to reduce the amount of the expensive ultraviolet curable resin used by using a general-purpose translucent resin other than the vicinity of the convex portion. Also, a small amount of light diffusing material can be dispersed inside or applied to the surface. By using the light diffusing material, the diffusibility of the emitted light can be enhanced and the luminance uniformity can be enhanced. In the case of applying the light diffusing material, it is more preferable to apply it on the exit surface side. As the light diffusing material, inorganic fine particles and cross-linked organic fine particles conventionally used for light diffusing plates and diffusion sheets can be used. The amount used is very small compared to a conventional general light diffusion plate, and a diffusibility equal to or higher than that can be obtained, and the transmittance is also very high.

There is no problem even when the support plate is used and the substrate portion of the light control member is a plurality of types of plates having different refractive indexes. In this case, a _i can be obtained by deriving an expression corresponding to Expression (7) in accordance with the idea described so far. However, when the variation of the respective refractive indexes is within 90%, the refractive index n ₂ can be approximated according to the ratio of the respective plate thicknesses to derive the equation (7). For example, when the base material portion is composed of three plates having refractive indexes of n ′, n ″, n ′ ″ and thicknesses of T ′, T ″, T ′ ″ respectively, n ₂ is (n It can be approximated by the value of “· T ′ + n ″ · T ″ + n ′ ″ · T ′ ″) / T.

  Further, when light diffusing materials having different refractive indexes are dispersed, the amount of the light diffusing material used is extremely small in the present invention, and therefore the influence of the refractive index need not be considered.

  The image display device of the present invention is realized by a method such as using a transmissive liquid crystal display element on a lighting device, and is not particularly limited, but the transmissive display element includes a transmissive liquid crystal panel, An image display device having excellent display surface luminance uniformity can be obtained.

The form of the Example of this invention is shown below.
The configuration of the illumination device of the present embodiment is shown by the schematic diagram of FIG.
First, the length in the X direction (not shown) is 458 mm, the length in the Y direction is 730 mm, the length in the thickness direction perpendicular to the X direction and the Y direction is 35 mm, the length in the X direction is 698 mm, and the length in the Y direction is A rectangular parallelepiped white ABS resin housing having a rectangular opening of 416 mm is prepared.
Next, the reflection plate 4 made of foamed PET resin and having a reflectance of 95% is disposed so as to cover the bottom portion at a position facing the opening on the emission side of the housing.
Next, a linear light source is arranged in parallel with the reflecting plate with an interval of 2 mm on the exit side of the reflecting plate. As the linear light source 1, a plurality of cold-cathode tubes having a diameter of 3 mm and a length of 700 mm are arranged along the X direction and parallel to the Y direction. Deploy. In Examples other than Example 7 and Comparative Examples, 16 cold cathode tubes are arranged at intervals of 22 mm. In Example 7, 12 cold cathode fluorescent lamps are arranged at intervals of 30 mm.

Next, the light control member 2 is disposed so as to cover the opening. The light control member is parallel to the reflecting plate 4 with an interval of 14 mm on the emission side of the linear light source 1. The size of the light control member is 707 mm in the Y direction and 436 mm in the X direction, and does not include the height of the convex portion in the thickness direction perpendicular to the X direction and the Y direction. A thickness T from the incident surface to the bottom of the convex portion is 2 mm.
H from the center of the linear light source 1 to the light control member 2 is 15.5 mm, and the distance D between the centers of the adjacent linear light sources 1 is 25 mm in the examples other than Example 6 and Comparative Example, and 33 mm in Example 6. It is.

The ridge-shaped convex part 3 formed on the emission surface of the light control member is formed by using a mold in which groove-shaped concave parts having a width of 0.3 mm are continuously formed in parallel by cutting. A UV curable resin having a refractive index of 1.55 is applied to the cutting surface of the mold, and a transparent material having a refractive index of 1.55 and a length of 436 mm, a width of 707 mm, and a thickness of 2 mm, which is a methyl methacrylate-styrene copolymer. A light control member is obtained by stacking resin plates and irradiating ultraviolet rays from above the transparent resin plates to cure the ultraviolet curable resin. The refractive index n of the convex portion is 1.55, and the refractive index n ₂ of the base material is 1.55. However, in Example 13, in place of the transparent resin plate, siloxane polymer particles (Tospearl 120: manufactured by GE Toshiba Silicone Co., Ltd., number average particle diameter 2 μm, CV value 3%) were used as fine particles of the light diffusing material. A light control member is produced using a molded plate containing 0.04 Wt%.

The molded plate containing the light diffusing material is produced as follows.
In other embodiments, the same methyl methacrylate-styrene copolymer resin pellets as the material of the transparent resin plate used for the production of the light control member, the light diffusing material, and 2- (5-methyl-2) which is a purple ray absorbent Hydroxyphenyl) benzotriazole (0.1% by mass) is mixed with a Henschel mixer and then melt-kneaded using an extruder to produce a molded plate having a width of 1000 mm and a thickness of 2 mm at an extrusion resin temperature of 200 ° C. By cutting this, it is set to 436 mm long and 707 mm wide.

  Moreover, about Example 14, a light control member is obtained by creating a convex part on the surface which has not embossed using the thing which embossed one main surface as a transparent plate. The embossed surface is the incident surface side of the light control member. The surface roughness of this surface is 3 μm in arithmetic average roughness Ra according to the measurement method of JIS B 0601-1994.

N shape of the grooves of the mold are shown in Table 1, f (X), X min, X max, thus each region -N~N having a width a _i of inclination Φ and X direction defined the same in Table 1 It is manufactured so as to be arranged in accordance with the order of the regions shown.

In Examples 1 to 10 and Examples 13 to 14, the entire region of each convex portion is approximated to a curve by the least square method. As points used for approximation, two points on both ends of the convex portion and all contact (2N) points in each region are used.
The evaluation results in this state are shown in Table 1.

  The light intensity distribution in the front direction is evaluated by measuring the front luminance distribution. The distribution of the front luminance is measured while moving the luminance meter by 1 mm in the X direction while keeping the distance between the luminance meter and the measurement point on the light emission surface side of the light control member constant. In the measurement of the light emission ratio in the front direction, first, the luminance of the measurement point is measured while changing the angle. At this time, the angle is changed along a cross section parallel to the normal direction of the main surface of the light control member and the X-axis direction. At this time, the distance between the luminance meter and the measurement point on the emission surface side of the light control member is kept constant. Next, the obtained luminance value for each angle is converted into an energy value, and the ratio of the energy emitted within 30 degrees to the front direction, which is the normal direction of the main surface of the light control member, is calculated. .

  Next, a transmissive liquid crystal panel is mounted on the emission side of the illumination device of Example 1 to form an image display device, which is observed from the front. As a result, a bright image without unevenness can be obtained.

(Comparative example)
As Comparative Example 1, a prism sheet having a prismatic prism with an apex angle of 90 ° formed on the exit surface is arranged so that the prism is parallel to the linear light source. As a result of observing from the front direction, the luminance is greatly reduced in the portion directly above the linear light source, and the in-plane luminance unevenness is increased.

13 and 14 show the principle of light control of the sheet. As shown in FIG. 13, since all the light 7 incident on the incident surface of the prism sheet 11 from the normal direction is totally reflected and returns to the light source side as reflected light 10, the total light transmittance in this region is 0 in principle. Yes, the measured value is very low at 5%. On the other hand, as shown in FIG. 14, the light 7 incident from an oblique direction is refracted by the convex portion and travels to the vicinity of the front surface, and thus shows a high total light transmittance. The implemented configuration is 90%. In this example, luminance unevenness is not eliminated.
In addition, a transmissive liquid crystal panel is mounted on the exit side of the illumination device to form an image display device, which is observed from the front. As a result, luminance unevenness is remarkable in the obtained image.

As Comparative Example 2, evaluation is performed in the case of using a normal light diffusing plate containing fine particles instead of the light control member.
In Example 13, the light diffusion plate was 1.9% by mass using siloxane polymer particles (Tospearl 2000B: manufactured by GE Toshiba Silicone Co., Ltd., number average particle diameter: 5 μm, CV value: 8%) as a light diffusion material. It is produced in the same manner as the molding plate used when producing the light control member.
An illuminating device is produced and compared with the structure which replaces | exchanges the light control member of the illuminating device of Example 1. FIG. When the brightness of the light diffusing plate is measured from the front direction with the cold cathode tubes turned on, the luminance is high in the portion directly above the cold cathode tubes, and the luminance is between the adjacent cold cathode tubes (upper oblique portions). Lower. As a result, there is a large difference in luminance between the direct portion and the diagonally upper portion of the cold cathode tube, and the luminance uniformity in the front direction, which is the image display surface, is greatly reduced.
In addition, a transmissive liquid crystal panel is mounted on the exit side of the illumination device to form an image display device, which is observed from the front. As a result, it can be seen that the obtained image is considerably darker than the case of using the illumination device of Example 1.

As Comparative Example 3, the same molding plate used when creating the light control member in Example 13 is used as the light diffusing plate, and the light control member of the illumination device of Example 13 is replaced with the light control member. Create and compare devices. In this case, the lamp image is remarkable, and the ratio G (X) _min / G (X) _max is 20%, and the luminance unevenness is not eliminated.

It is the schematic of the suitable example of the illuminating device of this invention. It is a figure which shows the relationship between the position of a linear light source, and the emitted light intensity to a front direction of the illuminating device of FIG. It is a figure which shows distribution of the light emission intensity | strength to the position of each linear light source, and each front direction when arrange | positioning three adjacent linear light sources. The incident angle alpha _i of the light from the linear light source is a diagram showing the relationship between the X-direction of the width a _i angle [Phi _i and region i of slope of the slope of the area i of the convex portion. It is a figure explaining the relationship between the incident angle to a light control member, and incident intensity. It is a figure which shows the principle which directs light to the front with the illuminating device of this invention. It is a figure which shows one example of distribution of the X direction of the emitted light intensity to the front direction by the light from one linear light source. It is a figure which shows one example different from FIG. 7 of the distribution of the X direction of the emitted light intensity to the front direction by the light from one linear light source. It is a figure which shows f (X) of the illuminating device shown in FIG. 7, and g (X) corresponding to it. It is a figure which shows f (X) of the illuminating device shown in FIG. 8, and g (X) corresponding to it. It is a figure which shows the example of the cross-sectional shape of the X direction of the light control member at the time of approximating the shape of the whole area | region of a convex part with a curve. It is the figure which showed arrangement | positioning of the light control member and linear light source which can be used for this invention. It is a figure which shows a mode that the light advances when the light of a linear light source injects perpendicularly on the smooth surface of the prism sheet of the comparative example 1. It is a figure which shows a mode that the light advances when the light of a linear light source injects into the smooth surface of the prism sheet of the comparative example 1 from the diagonal direction. It is the schematic of the conventional illuminating device of a direct system. It is a figure which shows distribution of the emitted light intensity to the front direction from the linear light source arranged in parallel. It is a figure which shows the ratio of the light which goes to the area | region i among the lights which go to a convex part with angle (alpha) _i . It is a diagram showing the angle [Delta] [alpha] _i anticipating the diameter of the light source in the point of coordinates X _i.

Explanation of symbols

1: linear light source, 2: light control member, 3: convex part, 4: reflector, 5: light diffusing plate, 6: incident surface 7: incident light, 8: outgoing light, 9: passing through light control member 10: reflected light 11: prism sheet

D: Distance between the centers of adjacent linear light sources H: Distance between the center of the linear light sources and the incident surface of the light control member f (X): Arrangement direction X of the linear light sources and any one of the illumination devices Function of distribution of light from linear light source and intensity of light emitted from convex part of light control member in front direction N: natural number n: refractive index n ₂ of convex part of light control member: base material of light control member the refractive index of X _max: positive direction of the X-coordinate at which f (X) is 0 X _min: f the negative direction when (X) is 0 X-coordinate g (X): f (X -D) + F (X) + f (X + D); a function of the distribution of the arrangement direction X of the linear light sources and the intensity of the light emitted from the adjacent three linear light sources in the front direction emitted from the convex portion of the light control member _{g (X) min: X min} ~X minimum g of g (X) between the _max (X) _max: maximum value of X _min to X _max between the g (X) δ: δ = (X max -X min ) / (2N + 1) met Small section [Phi _i: slope of inclination with respect to the exit surface of the area i of the convex portion X _i: X _min to X _max between the (2N + 1) of the X-coordinate of each element when it is equal center value a _i: area of the convex portion i width X in the X direction: thickness from the incident surface of the light control member to the bottom of the convex portion α _i : incident from a linear light source in a cross section parallel to the normal direction of the X direction and the main surface of the light control member The angle β _i of the light incident from the linear light source and incident on the surface through the light control member and exiting from the region i with respect to the normal of the incident surface: the X direction and the main surface of the light control member The light ray direction inside the convex part of the light control member is incident on the light that enters the incident surface from the linear light source and exits from the region i through the light control member in the cross section parallel to the normal direction of angle formed with respect to the surface normal gamma _i: in parallel to the cross section in the direction normal to the main surface of the X direction and the light control member, entering from the linear light source Of light incident on the surface is emitted from the area i through the interior light control member, the beam direction in the substrate inside the light control member, the angle b _i forms with respect to the normal line of the incident surface: X direction and light The length e _i of the slope of the region i in the cross section parallel to the normal direction of the main surface of the control member: the normal direction light source in the cross section parallel to the X direction and the normal direction of the main surface of the light control member The length of projection of the slope of the region i in the direction perpendicular to the light beam direction inside the light control member ξ _i : X direction The angle θ of the slope of the region i in the cross section parallel to the normal direction of the main surface of the light control member and the angle perpendicular to the light ray direction inside the convex portion of the light control member θ: X direction In the cross section parallel to the normal direction of the main surface of the light control member and entering the light incident surface from the linear light source. In the cross section, the light ray direction from the linear light source of the light emitted from the emission surface is in the cross section parallel to the incident angle Δθ that is made with respect to the normal line of the incident surface and the normal direction of the main surface of the light control member , An angle H ′ formed by a minute range centered on the light having the incident angle θ and the center of the linear light source: an angle from the linear light source in a cross section parallel to the X direction and the normal direction of the main surface of the light control member ( The trajectory connecting the point on the incident surface of the light control member through which the light emitted by θ−Δθ) and the center of the linear light source pass is projected longer on the trajectory through which the light emitted by the linear light source and the angle θ passes. Length (approximately equal to the distance between the point on the incident surface of the light control member through which the light emitted from the linear light source at an angle θ passes and the center of the linear light source)
V: in a region on the incident surface of the light control member through which light of Δθ around the incident angle θ from the linear light source passes in a cross section parallel to the X direction and the normal direction of the main surface of the light control member Length U: On the incident surface of the light control member through which light of Δθ from the linear light source passes in a cross section parallel to the X direction and the normal direction of the main surface of the light control member Projection of the line segment of the length V of the region to an angle perpendicular to the incident angle θ α: light incident on the light control member in a cross section parallel to the X direction and the normal direction of the main surface of the light control member The incident angle β with respect to the normal of the incident surface β: in the cross section parallel to the X direction and the normal direction of the main surface of the light control member, is incident on the incident surface from the linear light source and passes through the light control member. The angle γ of the light emitted from the convex portion inside the convex portion of the light control member with respect to the normal of the incident surface γ: the X direction and the optical control Light within the substrate of the light control member that is incident on the incident surface from the linear light source and exits from the convex portion through the light control member in a cross section parallel to the normal direction of the main surface of the member The angle ε with respect to the normal of the incident surface ε: The light source enters the incident surface from the linear light source in a cross section parallel to the X direction and the normal direction of the main surface of the light control member. The angle ω of the light ray direction inside the light control member passing through the convex portion with respect to the normal line of the slope of the convex portion passing through the X direction and the normal direction of the main surface of the light control member In the parallel cross section, the direction of the light ray emitted from the convex portion of the light incident on the incident surface from the linear light source and passing through the inside of the light control member is normal to the slope of the convex portion through which the light passes. an angle formed with respect to P: in the X direction and the light control member in the cross section parallel to a normal direction of a principal face, the width of the convex portion [Delta] [alpha] _i: the seat Angle anticipating the diameter of the linear light source than X _i

Claims (6)

It has a rectangular exit surface composed of an X direction and a Y direction perpendicular to the X direction,
A reflector, a plurality of linear light sources, and a plate-like light control member;
The reflector is arranged in parallel to the X direction and the Y direction,
The linear light source is disposed in one imaginary plane parallel to the X direction and the Y direction on the exit surface side of the reflector,
And, the linear light source has a longitudinal direction arranged parallel to the Y direction,
And it is arranged at equal intervals along the X direction,
The light control member is disposed on an emission surface side of the arranged linear light sources,
And the main surface is parallel to the virtual plane where the linear light sources are arranged,
The main surface of the light control member is composed of an incident surface that faces the linear light source and receives light from the linear light source, and an output surface that emits light received by the incident surface,
The emission surface has a plurality of ridge-shaped projections on the surface,
The convex portion is a lighting device in which a bowl-shaped ridge line corresponding to the top portion is formed in parallel to the Y direction, and arranged along the X direction,
The distance between the centers of the linear light sources is D, the distance between the center of the arbitrary linear light source and the light control member is H, and the X direction of the light incident on the light control member from one linear light source F (X) is a function representing the intensity of light emitted in the normal direction of the exit surface at the position coordinate X (where the light source position is X = 0),
g (X) = f (X−D) + f (X) + f (X + D) (1)
When
In the range of −D / 2 ≦ X ≦ D / 2,
The ratio g (X) _min / g (X) _{max of} g (X) _min that is the minimum value of g (X) and g (X) _max that is the maximum value is 0.6 or more,
The minimum value X _min of X is in the range of −3.0D ≦ X _min ≦ −0.5D, and the maximum value X _max is in the range of 0.5D ≦ X _max ≦ 3.0D (X _min and X _max are , F (X) is attenuated around a linear light source whose value is X = 0, and coordinates at both ends when it becomes substantially 0),
An illuminating device characterized in that the cross-sectional shape in the X direction of an arbitrary convex portion is composed of (2N + 1) different regions −N to N with different inclinations represented by the following formula.
δ = (X _max −X _min ) / (2N + 1) (2)
X _i = i × δ (3)
α _i = Tan ⁻¹ (X _i / H) (4)
β _i = Sin ⁻¹ ((1 / n) sin α _i ) (5)
γ _i = Sin ⁻¹ ((1 / n ₂ ) sin α _i ) (6)
_{a i αf (X i + T} · tanγ i) · cosΦ i · cosβ i / cosα i / cos (Φ i -β i) (7)
Φ _i = Tan ⁻¹ ((n · sin β _i ) / (n · cos β _i −1)) (8)
N: Natural number
i: integer from -N to N
n: Refractive index of the convex portion of the light control member
n ₂ : Refractive index of the base material of the light control member
a _i : width of region i in X direction
Φ _i : Slope inclination with respect to the exit surface of region i
T: Thickness from the incident surface of the light control member to the bottom of the convex portion It is the illuminating device of Claim 1, Comprising: Area | regions -N-N showing the cross-sectional shape of the X direction of the said convex part are located in order of the coordinate of the X-axis. 3. The lighting device according to claim 1, wherein a cross-sectional shape of the convex portion in the X direction forms at least one pair of two adjacent regions out of (2N + 1) different regions forming the convex portion. A lighting device characterized in that the shape is approximated by a curve. The illumination device according to any one of claims 1 to 3, wherein the angle is 30 degrees with respect to the normal direction of the exit surface in a cross section parallel to the X direction and the normal direction of the main surface of the light control member. An illumination device characterized in that a ratio of light emitted within a range of within an angle is 50% or more of the total light output. The light control member with which the illuminating device of any one of Claims 1-4 is provided. An image display device comprising a transmissive display element on an exit surface side of the illumination device according to claim 1.

Images