JP4515374B2 - LIGHTING DEVICE AND DISPLAY DEVICE USING THE SAME - Google Patents

Description

  The present invention relates to a so-called direct-type planar illumination device among illumination devices used in a transmissive display device such as a liquid crystal display device and a signboard. The present invention also relates to a display device using the lighting device.

  In recent years, particularly in the field of illumination and transmissive displays, there has been a demand for high brightness, thinness, and uniform brightness, and a plurality of linear light sources, a reflector provided on the back surface thereof, and light that forms a light emitting surface. A direct illumination device having a configuration in which a diffusion plate is combined is preferably used. Such a direct illumination device has a high effective utilization efficiency of the light flux emitted from the linear light source (the ratio of the light flux emitted from the lamp radiated from the light emitting surface) and can increase the number of linear light sources used. Therefore, it is easy to increase the luminance of the light emitting surface. In such a direct illumination device, a light diffusing plate is disposed at a relatively short distance right above the linear light source, and therefore contains a large amount of light diffusing fine particles for the purpose of erasing the lamp image of the linear light source. The light diffusing plate was usually used. However, although a light diffusion plate containing a large amount of light diffusing fine particles has good diffusion characteristics, there is a problem in that light loss and light reflectance due to the light diffusing fine particles are high, and light use efficiency is reduced. It was. Therefore, in recent years, a light control member using a prism lens or the like has been developed as a method for erasing a lamp image without containing light diffusing fine particles (see Patent Document 1).

  In addition, when the illuminating device is made thin, the distance between the linear light source and the light diffusing plate becomes shorter, or when the illuminating device is enlarged, the light diffusing plate becomes heavy, so the light diffusing plate becomes the linear light source. There was a problem of deformation due to heat and dead weight. Therefore, as a method for suppressing warpage or deflection of the light diffusing plate used in the lighting device in the direction of the linear light source, for example, a protrusion is formed on the reflecting plate for the purpose of holding the light diffusing plate and suppressing the deflection of the light diffusing plate. An illuminating device that employs a method of providing was used. In this case, since the reflectance of the light diffusing plate or the like is high, the projections are generally made of the same material or the same color as the surrounding reflecting plate that is opaque, and the shadow is projected onto the light diffusing plate for observation. It was prevented from being done. On the other hand, when a specially shaped protrusion such as a protrusion wall is used, a transparent material may be used (see Patent Document 2).

JP 2002-352611 A (Claims, FIG. 1, etc.) Japanese Patent Laid-Open No. 5-119316 (Claims, FIG. 3, etc.)

  However, in the method using the light control member such as the prism lens, it is difficult to strictly adjust the luminance unevenness because there is no detailed examination on the uneven shape of the prism lens or the like. Similarly, it is difficult to obtain the uniformity of the front luminance within the exit surface. For this reason, it is difficult to eliminate luminance unevenness in the front direction, and as a result, it is difficult to obtain sufficiently high quality illumination light. Further, a display device using the illumination device as a backlight has the same problem. In particular, when a light control member with high light utilization efficiency and high light transmittance is used for the purpose of improving the brightness of the lighting device, it becomes more difficult to obtain high-quality illumination light.

  In addition, when a light control member having a high light transmittance is used, there may occur a problem that the shadow of the protrusion provided on the reflection plate can be seen through the light control member in order to prevent warping and deflection. It was. Further, when a light control member using a prism or the like is used as the optical surface pattern, a problem that the shadow of the protrusion appears double is newly generated. In recent years, since further increase in brightness has been demanded for the illuminating device, an improvement in light transmittance is further demanded for the light diffusion plate and the light control member used in the illuminating device. There is also a demand for improvement in shadows caused by protrusions.

  Therefore, the present invention provides a lighting device having a plurality of linear light sources and a reflector that reflects the light from the linear light sources, has high light utilization efficiency, can eliminate luminance unevenness in the front direction, and increase front luminance. Providing a bright and high surface uniformity illumination device because the projection used for holding the member is made of a material or shape that does not substantially project shadows that degrade the illumination and display quality. The purpose is to do. Another object of the present invention is to provide a display device in which a transmissive display element is further provided in the illumination device.

  As a result of intensive studies on the above problems, the present inventors have found that the above problems can be solved by devising the configuration of the direct type illumination device and the shape and configuration of the light control member and protrusions used therefor. completed. That is, the illumination device provided by the present invention has a rectangular emission surface composed of an X direction and a Y direction perpendicular to the X direction, and includes a reflection plate, a plurality of linear light sources, and a plate-like light control member. And a projection that contacts the light control member and holds the light control member, the reflector is disposed in parallel to the X direction and the Y direction, and the linear light source emits from the reflector The linear light sources are arranged in one imaginary plane parallel to the X direction and the Y direction on the surface side, and the linear light source has a longitudinal direction arranged parallel to the Y direction, and along the X direction. The light control members are arranged on the emission surface side of the arranged linear light sources, and the main surface of the light control members is opposed to the linear light sources and emits light from the linear light sources. It consists of an incident surface that receives light and an exit surface that emits light received by the incident surface, and the main surface is linear Parallel to the virtual plane in which the sources are arranged, the emission surface has a plurality of bowl-shaped projections on the surface, and the projection has a bowl-shaped ridge line corresponding to the top formed in parallel to the Y direction. And the projections are made of a light-transmitting material, the projections have a circular cross section, and the diameter of the tip of the projection contacting the light control member is 1 mm or less. It is a certain lighting device. In the present specification, a cross section obtained by cutting the protrusion along a plane parallel to the main surface of the light control member is referred to as a “horizontal cross section of the protrusion”.

The invention according to claim 1 has a rectangular emission surface composed of an X direction and a Y direction perpendicular to the X direction, a reflection plate, a plurality of linear light sources, a plate-like light control member, An illumination device including at least a protrusion that contacts the light control member and holds the light control member, wherein the reflector is disposed in parallel to the X direction and the Y direction, and the linear light source is the reflection The light source is disposed in one imaginary plane parallel to the X direction and the Y direction on the exit surface side of the plate, and the linear light source is disposed such that the longitudinal direction is parallel to the Y direction, and the X direction The light control members are arranged on the emission surface side of the arrayed linear light sources, and the main surface of the light control members is opposed to the linear light sources and from the linear light sources. An incident surface for receiving the light and an exit surface for emitting the light received by the incident surface, and the main surface is Parallel to the virtual plane on which the light sources are arranged, and the exit surface has a plurality of hook-shaped protrusions on the surface, and the protrusions are formed with hook-shaped ridge lines corresponding to the tops parallel to the Y direction. Are arranged along the X direction, the protrusion is made of a light-transmitting material, the horizontal cross section of the protrusion is circular, and the diameter of the protrusion tip portion in contact with the light control member is 1 mm or less D is the distance between the centers of the linear light sources, H is the distance between the center of the arbitrary linear light source and the light control member, and X of the light incident on the light control member from the 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 in the direction (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 , The value of f (X) is attenuated around the linear light source where X = 0, and the coordinates of both ends when it becomes substantially 0), and the cross-sectional shape in the X direction of any convex portion is It is an illumination device characterized by comprising (2N + 1) different regions −N to N represented by the 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

  The invention described in claim 2 is characterized in that the regions -N to N representing the cross-sectional shape in the X direction of the convex portions of the light control member are arranged in the order of the position coordinates of the X axis. It is a lighting device.

  According to a third aspect of the present invention, there is provided at least one pair of two adjacent regions out of (2N + 1) different regions in which the cross-sectional shape in the X direction of the convex portion of the light control member forms the convex portion. The illumination device according to claim 1 or 2, wherein the shape is a shape approximated by a curve.

  The invention described in claim 4 emits light within a range that forms an angle of 30 degrees or less 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. The lighting device according to any one of claims 1 to 3, wherein the ratio of light is 50% or more of the total light output.

  According to a fifth aspect of the present invention, there is provided a display device characterized in that a transmissive display element is provided on the illumination device according to any one of the first to fourth aspects.

  According to the configuration of the first aspect, since the protrusion is made of a light-transmitting material, the horizontal cross section of the protrusion is circular, and the diameter of the protrusion tip portion in contact with the light control member is 1 mm or less, the light transmittance is high. Even when the light control member having the above is employed, it is possible to provide a lighting device that is difficult to see the shadow of the protrusion and has high brightness. In this case, since the deflection of the light control member can be held by the protrusions as in the conventional case, it is possible to suppress warping and deflection of the light control member.

In addition, in the distribution f (X) of the desired intensity of light emission in the front direction, the slope Φ _i of the convex region i, which is an important factor for determining the shape of the convex portion, and the width a _{i in the} X direction occupied by this are linear. It is selected based on the arrangement of the light source and the refractive index of the light control member. The convex portion serves to control the light from the linear light source and to make the distribution of the outgoing light intensity in the front direction of the outgoing 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. Therefore, it is possible to significantly reduce or avoid the use of a diffusing material that causes a decrease in light utilization efficiency.

  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 produced 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.

Light from the linear light source and light as diffused light that is reflected from the light from the linear light source 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 between g (X) _min , which is the minimum value of g (X), and g (X) _max , which is the maximum value, is 0.6 or more. The lighting device features.

  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 the light control member in the illuminating device of the present invention receives light under the same conditions for each period of the linear light source and similarly controls the light exit direction for light incident on an arbitrary point on the incident surface. By controlling the distribution of the emitted light intensity in the range of −D / 2 ≦ X ≦ D / 2, which is the period, the entire emitted light intensity distribution 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 illumination device of the present invention eliminates uneven brightness in the front direction by making the light intensity distribution in the front direction substantially constant within the exit surface.

  Since the intensity of incident light is inversely proportional to the distance from the light source, the influence of light from a distant linear light source is small. For this reason, the light output intensity in the front direction can be controlled by setting the function g (X) considering only the light output intensity from the three adjacent linear light sources within an appropriate range, and uneven brightness in the front direction is eliminated. it can. In addition, the distribution of the actual light intensity is further uniform due to the effect of the reflector, 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. Unevenness can be eliminated.

  FIG. 11 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 sources at the position of X = 0 to the entrance 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. 16, when the width of the convex portion in the X direction, 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. 17, 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 the 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. 19 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 · sin β) / (n · cos β−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 light source is selected based on the arrangement of the linear light source and the refractive index of the light control member.

  According to the configuration of claim 2, in addition to the above effects, the regions −N to N representing the cross-sectional shape of the convex portion in the X direction are arranged in the order of the coordinates of X, thereby controlling the light emission direction. It is possible to provide an illuminating device that is easy to form and that is easy to shape and advantageous in production.

  According to the configuration of claim 3, in addition to the above effects, at least one pair of adjacent regions out of the (2N + 1) different regions in which the cross-sectional shape of the convex portion in the X direction forms the convex portion. By making the shape of the two regions to be approximated by curves, the distribution of light emission intensity in the front direction and the distribution of light emission angles are smoother and easier to shape, so when creating a light control member It is advantageous, and it is possible to provide an illuminating device that is not easily damaged because the joint portion of the region is not a sharp shape.

  According to the configuration of the fourth aspect, in addition to the above effects, an angle of 30 degrees or less is formed with 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. Since the ratio of light emitted in the range is 50% or more of the total light output, the ratio of light emitted in the front direction is relatively high, so it is efficient for applications such as TVs and PC monitors that mainly observe the illumination surface from the front direction. An illumination device that can obtain bright illumination light can be provided.

  According to the fifth aspect of the present invention, since the transmissive display element such as a liquid crystal panel is provided on the lighting device, the light that is efficiently condensed and diffused by the light control member is transmitted through the transmissive display element. As a result, it is possible to easily obtain an image display device that has a simple configuration, does not require adjustment of the light source position, can eliminate the lamp image, and has excellent brightness on the exit surface. 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.

Hereinafter, the present invention will be described in detail.
An illuminating device of 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, wherein the illuminating device includes a reflector, a plurality of linear light sources, and an emission surface. A lighting device comprising at least a plate-like light control member in which a plurality of ridge-shaped convex portions are formed on the surface of the light source and a protrusion for holding the light control member, wherein the protrusion is made of a light-transmitting material. Thus, the horizontal cross section of the projection is circular, and the diameter of the tip of the projection contacting the light control member is 1 mm or less.

  The structure and function of a lighting device according to an embodiment of the present invention will be described with reference to the drawings. 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 hook-shaped ridge line corresponding to the top formed in parallel to the Y direction. The lighting device includes a reflector 4 and a protrusion 5 that are arranged along the back surface and arranged in parallel in the X direction and the Y direction.

  Next, FIGS. 2 and 3 are enlarged views of specific embodiments corresponding to the vicinity where the protrusions 5 of FIG. 1 are arranged, and FIG. 4 shows the lighting device with the light control member 2 removed from above. Each figure is shown schematically.

  As a means for fixing the light control member 2 of the protrusion 5, for example, as shown in FIG. 4, the light control member 2 is attached to the center of the lighting device in the vertical direction and symmetrically in the horizontal direction. However, the position and the number of the protrusions 5 may be appropriately changed depending on the size of the lighting device, the degree of deflection of the light diffusion plate, and the like, and a plurality of protrusions 5 may be provided. In the following description, as shown in FIG. 4, an example will be described in which a total of two are attached to the center of the lighting device in the vertical direction and symmetrically in the horizontal direction.

  2, 3, and 5, a flat surface is formed on the incident surface side of the light control member 2, a bowl-shaped convex portion 3 is formed on the emission surface side, and the light is emitted on the emission surface side of the illumination device. A bowl-shaped ridge line is formed on the surface of the control member 2 in parallel with the Y direction, and is arranged along the X direction. Further, the protrusion 5 may be integrated with the reflecting plate 4 and an adhesive tape as shown in FIG. 2, or may be embedded in the reflecting plate 4 as shown in FIG.

  Next, the reason why the light control member 2 is shaded by the protrusion 5 will be described. The light control member 2 has a plurality of hook-shaped protrusions on the light exit surface side, and the protrusions have hook-shaped ridges that are parallel to the Y-direction, and in the X-direction. In the light control members 2 arranged along the line, when the light rays from the linear light source 1 are shielded by the projections 5 made of an opaque material, the light rays can reach the light control member 2 as shown in FIG. As a result, the shadow of the projection 5 can be seen from the light exit surface of the light control member 2. In particular, when the light control member 2 that forms a ridge-like convex portion on the exit surface side in the present invention is used, there may be a problem that the shadow of the projection 5 made of an opaque material looks double.

  On the other hand, the light diffusing plate containing a large amount of light diffusing fine particles used in place of the conventional light control member has a strong light scattering action, and thus there is a light shielding portion by a protrusion on the incident surface of the light diffusing plate. Even in this case, the shadow of the protrusion was hardly recognized on the light diffusing plate exit surface by the scattered light from the other light incident portions. The degree of the light scattering action that makes it possible to recognize the shadow of the protrusion is also affected by the characteristics of the light diffusing fine particles, but generally depends on the concentration of the light diffusing fine particles, and less than 1 part by weight of the light diffusing fine particles. In the case of the light diffusing plate including, the shadow of the protrusion is recognized.

  For this reason, the projection used in the lighting device of the present invention needs to have a shape or material that does not project the shadow even on the light control member having a light diffusing fine particle content of less than 1 part by mass. Specific preferred shapes and materials of the protrusions will be described below.

  The horizontal cross-sectional shape of the protrusion used in the lighting device of the present invention is important to be a circle, but it is not necessary to be a circle in a strict sense, and includes a case where it is substantially a circle. For example, an ellipse in which the ratio of the length of the short axis to the length of the long axis is 0.8 or more, or a regular polygon having a regular hexagon or more can be regarded as a circle in the present invention, but is not limited to these shapes. Needless to say. In the lighting device according to one embodiment of the present invention, a part of light incident on the light control member from the linear light source is transmitted through the emission surface while being partly refracted by the light control member, and a part of the light enters the light control member inside the emission surface. reflect. For this reason, when the horizontal cross section of the projection has a shape having a so-called edge such as a quadrangle, the traveling direction of the light abruptly changes on both sides of the edge, so that the projection shadow easily occurs on the exit surface of the light control member. On the other hand, when the horizontal cross section of the protrusion is a relatively flat elliptical shape, the spreading state of the light passing through the protrusion from the linear light source is greatly different between the major axis direction and the minor axis direction of the ellipse. Depending on the direction, the shadow of the protrusion is likely to occur. That is, it is preferable to make the horizontal cross-sectional shape of the protrusions substantially circular, since it is difficult to recognize the shadows of the protrusions even when observed from all directions.

  In addition, it is important that the protrusion used in the lighting device of the present invention is formed of a light transmissive material. The material for forming the protrusion is preferably formed of a transparent material, and if it is so-called transparent, either a thermoplastic resin or a thermosetting resin is preferably used. Specific examples thereof include (meth) acrylic resins, (meth) acryl styrene copolymer resins, styrene resins, aromatic vinyl resins, olefin resins, ethylene vinyl acetate copolymer resins, vinyl chloride resins, Examples thereof include vinyl ester resins, polycarbonates, fluorine resins, urethane resins, silicone resins, amide resins, imide resins, polyester resins, epoxy resins, phenol resins, urea resins, melamine resins, and the like. When the protrusion is formed of an opaque material, a shadow is projected on the light diffusion plate, which is not preferable. In addition, the light transmittance of the light transmissive material that does not generate a shadow is preferably 60% or more, and more preferably 80% or more.

  And as a shape of the projection used for the lighting device of the present invention, a cross section is substantially circular, and a diameter of about 1 to 10 mm, preferably about 1 to 6 mm, is used to hold the light control member. It is important that the diameter of the tip of the protrusion contacting the light control member is 1 mm or less, preferably in the range of 0.1 to 0.8 mm, more preferably in the range of 0.1 to 0.5 mm. preferable. When a convex / concave portion is formed on the incident surface side of the light control member, it is preferable that the pitch of the convex / concave portion is at least twice as long as the light control member is held. The range is preferably 1 mm, more preferably 0.1 to 0.8 mm, and still more preferably 0.1 to 0.5 mm. Since the light from the linear light source is generally diffused light, when considering the optical path of the light ray that becomes a shadow, the shadow of the projection becomes thin by the action of the diffused light. However, since the light control member and the protrusion are in contact with each other, there is almost no light diffusing action, so that the shadow of the protrusion can be seen as it is. Therefore, it can be said that the smaller the contact point between the protrusion and the light control member, the better. In addition, the tip of the protrusion is not limited to a flat surface, and may have moderate unevenness within a range that does not hinder the contact between the protrusion and the protrusion formed on the incident surface side of the light control member. Good.

  As an arrangement form of the projection, in addition to the form arranged on the reflection plate 4 as shown in FIG. 2, any other shape or structure may be used as long as it is not projected as a shadow on the light control member 2. Absent. For example, as shown in FIG. 3, it may be embedded in the reflecting plate 4, or the linear light source 1 and the light control member 2 may be supported by one protrusion 5.

  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 1 of the present invention is disposed so as to be sandwiched between the reflector 4 and the light control member 2, about half of the light emitted from the linear light source 1 is directed toward the light control member 2. The other half is in the direction of the reflector 4. Among these, the light diffusely reflected by the reflecting plate 4 toward the reflecting plate 4 enters the light control member 2 as diffused light. Further, part of the light incident on the light control member 2 from the linear light source 1 is totally reflected and travels toward the return reflector 4. The light emitted from the linear light source 1 and directed to the reflection plate 4 and the light totally reflected by the light control member 2 and directed to the return reflection plate are diffusely reflected by the reflection plate and re-diffused to the light control member 2 as diffuse light. Incident. 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 2. Accordingly, the ratio G (X) _min / G () between the minimum value G (X) _min and the maximum value G (X) _max of the outgoing light intensity in the front direction when the diffused light is included in the state where the reflecting plate 4 is disposed. X) _max is larger than the ratio g (X) _min / g (X) _max when no reflected light is included. Further, by appropriately selecting the reflecting plate, 50% or more of the light incident on the light control member 2 becomes diffuse light.

The brightness unevenness eliminating effect by the reflector 4 will be briefly estimated below. It is assumed that 50% of the light emitted from the linear light source 1 is incident on the light control member 2 after being diffusely reflected by the reflector 4. When the reflectance of the reflector 4 is 95%, 95% of the same amount of light emitted from the linear light source 1 toward the light control member 2 in the front direction is reflected by the reflector 4 from the linear light source 1. Then, the light enters the light control member 2 as diffused light and exits in the front direction. Assuming that the light emitted from the linear light source 1 toward the light control member 2 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 reflecting plate 4 from the linear light source 1, enters the light control member 2 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 4 is disposed, G (X) _max which is the maximum value, and The ratio G (X) _min / G (X) _max is determined 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 mentioned above, since the diffused light component is actually 50% or more of the incident light to the light control member 2,
g (X) _min / g (X) _max > 0.6 (26)
You can see that.

  FIG. 6 is a diagram illustrating the relationship between the light output intensity in the front direction and the position of the linear light source 1 when the linear light sources 1 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 as follows. It is greatly different from the portion (diagonally upper portion) immediately above each of the adjacent linear light sources 1. This means that in the illumination device of the present invention, the incident intensity in the front direction on the incident surface of the light control member 2 is greatly different between the portion directly above each linear light source 1 and the obliquely upper portion.

  FIG. 7 is a diagram showing the relationship between the position of the linear light source 1 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. 8 is a diagram showing the position of the linear light source 1 and the distribution of the light emission intensity in the front direction when the three adjacent linear light sources 1 and the reflecting plate 4 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. 7, the light intensity distribution in the front direction becomes substantially constant by the light control member 2 of the present invention, so that the luminance unevenness in the front direction is eliminated.

FIG. 10 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. 9, 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. 10, 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. 10, as in the case of FIG. 9, linear light sources are arranged with D = 30 mm, and in the front direction due to 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. 9 is compared with the case where X _min = −D and X _max = D shown in FIG. 10, 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. 9, the convex shape has an inclined 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. 11 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 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. Moreover, the light emission ratio in the front direction is performed as follows.
First, the brightness 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 brightness value obtained 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. To do.

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 width a _i in the X direction of each region of protrusions is _{f (X i + T · tanβ} i) · cosΦ i · cosβ i / cosα i / cos be proportional to (Φ _i -β _i) of the present invention Although it is the characteristic of an illuminating device, although a preferable width | variety may shift | deviate a little by the influence of the height from the bottom part of a convex part to the surface, there is no big 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 is weak and the deflection is caused. Unevenness occurs. 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 production, 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. 13 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 the 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.

It is not limited to shape the shape protrusion, extrusion, injection molding, 2P molding using an ultraviolet curable resin (P hoto P olymerization Process), and the like. 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. Examples thereof include methacrylic resin, polystyrene resin, polycarbonate resin, cycloolefin resin, (meth) acrylstyrene copolymer resin, cycloolefin-alkene copolymer resin, and the like.

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, a (meth) acrylic acid methylstyrene copolymer having a thickness of 2 mm, a siloxane polymer particle (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) %)) 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 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 diffusing 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.

  Examples of the present invention will be described below, but the present invention is not limited thereto.

(Configuration of the lighting device used)
The structure of the illumination device used in the examples of the present invention is shown below.
As an example of a preferred embodiment of the lighting device in the present invention, evaluation was performed using a basic structure of a backlight unit mounted on a commercially available liquid crystal display device (trade name KDL-L32HVX manufactured by Sony Corporation). The configuration of the backlight unit will be described with reference to FIG. In a rectangular parallelepiped housing having an opening with a length of 438 mm in the X direction, a length of 758 mm in the Y direction, and a length of 19 mm in the thickness direction perpendicular to the X and Y directions, the opening on the output side of the housing The reflecting plate 4 having a length of 714 mm in the X direction and a length of 398 mm in the Y direction was arranged on the emission side so as to cover the bottom portion at the opposite position.
Next, a linear light source was arranged in parallel with the reflecting plate with an interval of 3 mm on the exit side of the reflecting plate. The linear light source 1 was 16 cold-cathode tubes having a diameter of 3 mm and a length of 700 mm, and was arranged at intervals of 21.5 mm in parallel with the Y direction along the X direction.

Next, the light control member 2 according to the present invention was arranged so as to cover the opening. The light control member was arranged in parallel with the reflecting plate 4 with an interval of 13 mm on the emission side of the linear light source 1. The size of the light control member is 732 mm in the Y direction and 407 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. The thickness T from the incident surface to the bottom of the convex portion was 2 mm.
H from the center of the linear light source 1 to the light control member 2 was 14.5 mm, and the distance D between the centers of the adjacent linear light sources 1 was 25.0 mm.

(Production of light control member)
In the light control member according to the present invention used in the embodiment, a flat surface is formed on the incident surface side of the light control member facing the linear light source, and from the expression (2) according to claim 1 on the emission surface side ( 8) A ridge-shaped convex portion led from 8 is formed, and the light control member was manufactured as follows.

(1) First, from f (x) = cos α, N = 50, X _min = −25.0, and X _max = 25.0, the shape derived from the equations (2) to (8) according to claim 1 is curved. An approximate groove-shaped shape with a width of 0.3 mm was continuously formed in parallel by cutting to produce a mold. Next, an ultraviolet curable resin having a refractive index of 1.55 is applied to the cutting surface of the mold, and a methacrylic acid methylstyrene copolymer having a length of 407 mm, a width of 732 mm, and a thickness of 2 mm is formed thereon by extrusion molding. A transparent resin plate (used resin: manufactured by Denki Kagaku Kogyo Co., Ltd., trade name “TX polymer” TX-800S, refractive index: 1.549) is layered, and the ultraviolet curable resin is applied by irradiating ultraviolet rays on the transparent resin plate. By making it harden | cure, the light control member (B-1) in which the bowl-shaped convex part was formed was obtained. It was 0.87 when g (X) _min / g (X) _max was measured about the obtained light-control member (B-1).

(2) A UV curable resin having a refractive index of 1.55 is applied to the cutting surface of the mold from the mold prepared in the above (1), and light diffusing fine particles (manufactured by GE Toshiba Silicone Co., Ltd.) Name “Tospearl” 2000B, Refractive Index: 1.420) 0.15 parts by mass added to the (meth) acrylstyrene copolymer transparent resin plate and produced by extrusion molding with a length of 407 mm, a width of 732 mm, and a thickness of 2 mm ( Light control member (B-2) in which a ridge-like convex portion is formed by stacking (meth) acryl styrene copolymer resin plates and irradiating ultraviolet rays on the resin plates to cure the ultraviolet curable resin Got. It was 0.92 when g (X) _min / g (X) _max was measured about the obtained light-control member (B-2).

(3) Further, an ultraviolet curable resin having a refractive index of 1.55 is applied to the cutting surface of the mold from the mold prepared in the above (1), and then light diffusing fine particles (GE Toshiba Silicone Co., Ltd.). Product name “Tospearl” 2000B, Refractive index: 1.420) 1.0 part by mass was added to the (meth) acrylstyrene copolymer transparent resin plate and produced by extrusion, length 407 mm, width 732 mm, thickness 2 mm. The (meth) acryl styrene copolymer resin plate is stacked, and the ultraviolet curable resin is cured by irradiating ultraviolet rays from above the resin plate, whereby the light control member (B- 3) was obtained. It was 0.95 when g (X) _min / g (X) _maxx was measured about the obtained light-control member (B-3).

(Evaluation of projection shadow and brightness measurement)
(A) About the shadow by a processus | protrusion, visual evaluation was performed and the result was shown in Table 1.
(B) About the front luminance which shows the brightness of an illuminating device, it measured with the color luminance meter (Topcon Co., Ltd. BM-5), and the result was shown in Table 1.

Example 1
Instead of the projection attached to the backlight unit mounted on the liquid crystal display device (trade name KDL-L32HVX, manufactured by Sony Corporation), an acrylic resin (trade name “Paraglass” transparent board 6 mmt, manufactured by Kuraray Co., Ltd.) is used, A projection having a horizontal cross-sectional shape shown in 14 (a) having a circular diameter of 3 mm and a tip diameter of 1 mmφ cut by a lathe was attached and fixed to the lighting device using a double-sided tape. As shown in FIG. 4, the attachment position was an intermediate position of the linear light source.
When combined with the light control member (B-1), no shadow due to the protrusion was visible at the position where the protrusion and the light control member were in contact. Further, as shown in Table 1, the measured luminance was a high value, and the effect of improving luminance unevenness was also good.

(Example 2)
The protrusions of Example 1 were used and evaluated in the same manner as Example 1 in combination with the light control member (B-2). The shadow caused by the protrusion at the position where the protrusion and the light control member contacted was not visible as in Example 1. Further, as shown in Table 1, the measured luminance was also a relatively high value, and the effect of improving luminance unevenness was also good.

(Comparative Example 1)
Using the protrusion (white opaque: the shape is the same as in Example 1) attached to the backlight unit mounted on the liquid crystal display device (trade name KDL-L32HVX, manufactured by Sony Corporation), the light control member (B-1) Evaluation was performed in combination. As a result, a shadow caused by the protrusion was clearly generated at a position where the protrusion and the light control member contact each other.

(Comparative Example 2)
The protrusion of Comparative Example 1 was used and combined with the light control member (B-3). Since the light control member (B-3) contains a larger amount of light diffusing fine particles than the light control member (B-1) of Comparative Example 1, the light control member (B-3) is caused by the protrusion at the position where the protrusion and the light control member are in contact with each other. Although the shadow was not visible, the measured luminance was low as shown in Table 1. That is, it can be said that luminance and image quality are not balanced.

(Comparative Example 3)
Instead of the projection attached to the backlight unit mounted on the liquid crystal display device (trade name KDL-L32HVX, manufactured by Sony Corporation), an acrylic resin (trade name “Paraglass” transparent board 6 mmt, manufactured by Kuraray Co., Ltd.) is used, A product obtained by cutting a projection having a circular horizontal cross section and a tip diameter of 3 mmφ as shown in 14 (b) with a lathe was attached and fixed to the lighting device using a double-sided tape. As shown in FIG. 4, the attachment position was an intermediate position of the linear light source.
When combined with the light control member (B-1), a shadow caused by the protrusion was clearly confirmed at the position where the protrusion and the light control member contacted. That is, it can be seen that the image quality is adversely affected if the tip diameter of the protrusion exceeds 1 mmφ.

It is the schematic of the suitable example of the illuminating device of this invention. It is a cross-sectional partial enlarged view of the backlight apparatus for liquid crystal display devices which is one embodiment of this invention. It is the cross-sectional partial enlarged view of the backlight apparatus for liquid crystal display devices which is other one Embodiment of this invention. It is a model top view except the light control member of the backlight apparatus for liquid crystal display devices which is one embodiment of this invention. It is a schematic diagram explaining the advancing direction of the light ray when a protrusion is provided between the linear light source and the light control member. 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 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. 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 an example different from FIG. 11 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. 10, and g (X) corresponding to it. 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 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 a figure which shows the shape of the protrusion concerning an Example and a comparative example. 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 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. 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.

Explanation of symbols

1: linear light source, 2: light control member, 3: convex part, 4: reflector, 5: protrusion, 6: incident surface, 7: incident light, 8: outgoing light, 9: passes through the inside of the light control member Light toward the convex

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 of the light emitted from the light exit surface, the light beam direction from the linear light source is an incident angle Δθ formed with respect to the normal of the light incident surface: the X direction 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. (An angle θ from the linear light source
Is approximately equal to the distance between the point on the incident surface of the light control member through which the light emitted from and the center of the linear light source passes)
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 direction is an angle ε with respect to the normal of the incident surface: The X direction and the normal direction of the main surface of the light control member in a cross section parallel to the incident surface from the linear light source. 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 (5)

It has a rectangular emission surface composed of an X direction and a Y direction perpendicular to the X direction. The light is in contact with the reflection plate, a plurality of linear light sources, a plate-like light control member, and the light control member. An illumination device including at least a protrusion for holding a control member, wherein the reflecting plate is arranged in parallel to the X direction and the Y direction, and the linear light source is in the X direction on the exit surface side of the 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. The light control member is disposed on the emission surface side of the arrayed linear light sources, and the main surface of the light control member is opposed to the linear light source and receives the light from the linear light source. It is composed of an exit surface that emits light received by the incident surface, and the main surface is before the linear light sources are arranged. Parallel to the virtual plane, the exit surface has a plurality of bowl-shaped protrusions on the surface, and the protrusion has a bowl-shaped ridge line corresponding to the top formed in parallel to the Y direction, and the X direction. The projections are made of a light-transmitting material, the projections have a circular cross section, and the tip of the projection contacting the light control member has a diameter of 1 mm or less. The distance between the centers is D, the distance between the center of the arbitrary linear light source and the light control member is H, and the position coordinate X in the X direction of the light incident on the light control member from the linear light source (light source position) F (X) is a function representing the intensity of light emitted in the normal direction of the exit surface at 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 , The value of f (X) is attenuated around the linear light source where X = 0, and the coordinates of both ends when it becomes substantially 0), and the cross-sectional shape in the X direction of any convex portion is An illumination device comprising (2N + 1) regions having different inclinations -N to N expressed by an equation.
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   2. The lighting device according to claim 1, wherein the regions −N to N representing the cross-sectional shape in the X direction of the convex portions of the light control member are arranged in the order of the position coordinates of the X axis.   The cross-sectional shape in the X direction of the convex portion of the light control member is a shape that approximates the shape of at least one pair of two adjacent regions out of (2N + 1) different regions forming the convex portion by a curve. The illumination device according to claim 1, wherein   In a cross section parallel to the X direction and the normal direction of the main surface of the light control member, the proportion of light that emits light in a range that forms an angle of 30 degrees or less with respect to the normal direction of the exit surface is 50% of the total light output. It is the above, The illuminating device of any one of Claims 1-3 characterized by the above-mentioned. A display device comprising a transmissive display element provided on the lighting device according to claim 1.