JP2007103322A - Illumination device, light control member equipped with it, and image display device using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an illumination device and an image display device wherein it is not necessary to adjust the position of light sources, a lamp image is eliminated, and homogenization of brightness is excellent in the emitting face. <P>SOLUTION: A reflecting plate 2, the light sources 1, and a light control member 4 are arranged from the light incident side toward the light emitting side in this order. The light control member 4 is provided with the incident face and the emitting face. When the distance between an arbitrary light source X and another light source Y most adjacent thereto is D and the distance between the light source X and the light control member 4 is H, the total light transmittance of the light entering an arbitrary point on the incident face at the angle α=Tan-1ä(D/2)/H} to the normal direction of the incident face is 50% or more and 1.05-3.0 times as much as that of the light entering the point on the incident face from the normal direction. A plurality of convex parts are formed on the emitting face of the light control member 4, and the convex parts are composed of a material of which the refractive index is 1.58 or more. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an illuminating device having a plurality of light sources and an image display device using the illuminating device, and is particularly suitable for a large-sized lighting signage device, a liquid crystal display device, and the like that require high luminance and luminance uniformity. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct-type illumination device, a light control member provided in the illumination device, and an image display device using the light control member.

Taking an illumination device for an image display device as an example, an edge light system in which light from a light source disposed on the side edge of the light guide plate is guided in the front direction by the light guide plate and made uniform by a diffusion sheet, and a light source on the back side of the illumination surface And a direct system in which light is made uniform with a diffuser.
The direct type has a tendency to increase the thickness because the light source is provided on the back surface of the apparatus. For this reason, it is advantageous to provide the light source at the side edge in a field where thinness is required such as a mobile phone or a mobile personal computer. The edge-light method is the mainstream.

On the other hand, in recent years, there has been an increasing demand for larger displays and higher brightness mainly in the market of televisions and personal computer monitors. In particular, with the increase in the size of the display, the edge light method reduces the ratio of the length of the peripheral portion where the light source can be arranged to the display area, and the amount of light is insufficient, so that sufficient luminance cannot be obtained.
Therefore, a method has been proposed in which a plurality of films for improving luminance are arranged on a surface light source to improve the light use efficiency (see, for example, Patent Document 1).

  However, the brightness enhancement film is not necessarily advantageous from the viewpoint of productivity and thinning because it leads to an increase in cost and the number of films to be used increases. Further, the edge light system has a problem that the weight of the light guide plate increases as the display becomes larger. As described above, in the edge light system, it has been difficult to meet market demands such as an increase in display size and brightness in recent years.

Therefore, a direct method using a plurality of light sources is attracting attention. In this method, the utilization efficiency of light emitted from the light source, that is, the ratio of the light flux emitted from the light emitting surface to the light flux emitted from the light source is high, and the number of light sources can be increased freely.
That is, since the amount of light can be increased freely, the required high brightness can be easily obtained, and there is no reduction in brightness or brightness uniformity due to an increase in size. Furthermore, since a light guide plate that directs light to the front is not necessary, the weight can be reduced.
Also, as other lighting devices, for example, lighting signboards, etc., have a simple configuration, and high brightness can be easily obtained without using a film for improving brightness. is there.

  However, the direct system has to solve unique problems such as elimination of lamp image, thinning, and energy saving. In particular, the lamp image appears as brightness unevenness much more remarkable than the edge light method. For this reason, it is difficult to eliminate the lamp image by means conventionally used in the edge light system, that is, means such as a diffusion film in which a diffusion material is applied to the film surface.

  Therefore, a diffusion plate containing a diffusion material is widely used. In this method, for example, as shown in FIG. 17, a diffusion plate 20 is installed on the front side of the light source 1 in which the reflection plate 2 is arranged on the back side. In order to obtain good diffusibility and light utilization efficiency, inorganic fine particles and cross-linked organic fine particles are blended as a light diffusing material in base resin such as methacrylic resin, polycarbonate resin, styrene resin, and vinyl chloride resin. Thus, a method for producing a light diffusing plate (for example, see Patent Document 2) has been studied.

  However, the method using these diffusing materials is not preferable from the viewpoint of energy saving because the light use efficiency decreases due to the absorption of light into the diffusing material and the diffusion of light in unnecessary directions. Moreover, although a lamp image can be reduced by arranging many light sources close to each other, there is a problem that power consumption increases.

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

  Also, a method of installing a reflective member facing the light source (for example, see Patent Document 4), a method of arranging a light beam direction conversion element such as a Fresnel lens for each light source, etc. (for example, see Patent Document 5) However, as in the method described in Patent Document 3, since accurate alignment between the member and the light source is necessary, there arises a problem that productivity is inferior.

  In large illuminating devices, the demand for thinning is not strict as compared with mobile phones, mobile personal computers, and the like, so it can be dealt with by shortening the distance between the light source and the diffusion plate or reducing the number of optical films.

In order to realize energy saving, it is necessary to increase the efficiency of light utilization. The direct method can increase the number of light sources as described above, and it is easy to obtain high brightness, but from the viewpoint of energy saving, use of light such as using a large amount of diffusing material to eliminate the lamp image. You must avoid measures that greatly reduce efficiency.
Japanese Patent Laid-Open No. 2-17 JP 54-155244 A Japanese Patent No. 2852424 JP 2000-338895 A JP 2002-352611 A

  Therefore, the present invention has high brightness on the exit surface, high light utilization efficiency, and there is no change in the optical design of the member, brightness reduction, and brightness uniformity reduction associated with the increase in size, so that it is easy to cope with the increase in size. The lamp image is eliminated without strict alignment between the light source and other members, and the lighting system directly below the multiple light sources can be used to reduce the thickness of the light source and other members close to each other or simplify the film configuration. An object of the present invention is to provide a light control member included in the device and an image display device using the light control member.

In view of the above-mentioned problems, the present inventors have made the following studies and have reached the present invention.
In the illumination device of the type directly below the plurality of light sources, the energy of the emitted light is large at a position facing each light source and small at a position facing between adjacent light sources. Therefore, the light emitted from the position facing the light source is weakened by appropriate reflection at the light control member, and the reflected light is returned to the light control member again as diffused light by the reflector.

  As a result, the energy of the light emitted from the position opposite to the light source and the position other than the light source becomes equal without greatly reducing the light use efficiency, and the lamp image is eliminated, and this object is achieved. For this reason, the inventors have found a means for controlling the ratio of the total light transmittance of the light control member at a position facing the light source and a position facing the midpoint between the two adjacent light sources to an appropriate range.

The inventors of the present invention studied in more detail and found an optimum range of the total light transmittance ratio. It has also been found that this method can avoid or greatly reduce the use of a diffusing material that lowers the light utilization efficiency, and achieves a high light utilization efficiency.
Further, in order to eliminate the need for alignment of the light source and the light control member, it is necessary to have the same property with respect to the total light transmittance at an arbitrary point on the incident surface of the light control member. That is, it was concluded that it is necessary to have a uniform optical property at an arbitrary point on the incident surface. Here, “point” indicates at least a minute region that does not affect the visual perception.

The invention according to claim 1, which is made based on the above examination results, controls a light emitting direction when a plurality of regularly arranged light sources, a reflecting plate, and light from the light source and the reflecting plate are transmitted. A direct-type illumination device including at least a light control member, wherein the reflector, the light source, and the light control member are arranged in this order from the light incident side to the light emitting side, and the light control member mainly receives light. Provided with an incident surface and an exit surface that mainly emits light, D is a distance between an arbitrary light source X and another light source Y that is nearest to it, and H is a distance between the light source X and the light control member. In this case, the total light transmittance of light incident on an arbitrary point on the incident surface at an angle of α = Tan ⁻¹ {(D / 2) / H} with respect to the normal direction of the incident surface is 50% or more. In addition, the total light transmittance is such that light enters the point on the incident surface from the normal direction. 1.05 times to 3 times the total light transmittance of the light, and a plurality of convex portions are formed on the exit surface of the light control member, and the convex portions have a refractive index of 1.58 or more. Provided is a lighting device made of a material.

According to this configuration, the total light transmittance of light incident at a predetermined angle α = Tan ⁻¹ {(D / 2) / H} with respect to the normal direction of the incident surface of the light control member is 50% or more. And the total light transmittance is 1.05 to 3 times the total light transmittance in the case of the light incident from the normal direction, that is, the light incident on the position directly above the light source. It becomes moderately higher than the total light transmittance. Therefore, the in-plane distribution of light energy emitted from the light control member is made uniform. Further, preferable optical properties can be obtained at any point on the incident surface.

  In the first aspect of the invention, since the plurality of convex portions are formed on the emission surface of the light control member, the plurality of convex portions are formed on the emission surface. The light that is incident and travels toward the exit surface is diffused and emitted in multiple directions by a plurality of convex portions.

According to a second aspect of the present invention, 10 to 50% of the light incident at an angle α with respect to the normal direction of the incident surface of the light control member has an angle of −15 ° to + 15 ° with the normal direction of the output surface. It emits in the range of.
According to this configuration, since 10 to 50% of the light incident at the angle α is emitted at the emission angle of −15 ° to + 15 °, the front direction of the light control member on the emission surface of the light control member, that is, the incidence surface. The ratio of components emitted from the normal direction is significantly increased.

According to a third aspect of the present invention, the incident surface is flat, the projection is formed on the exit surface, is perpendicular to the exit surface, and includes a top of the projection, and has a cross section in at least one predetermined direction. When the contour line in the light emitting part has a refractive index n of the light diffusion plate, the inclination θ of the contour line is 0 ≦ | Sin ⁻¹ (n · sin (θ−Sin ⁻¹ ((1 / n) Sin α))) − θ | ≦ (π / 12) is satisfied, and the absolute value θ2 of the inclination with respect to the exit surface includes a region X that is less than Sin ⁻¹ (1 / n), and the region X is the convex portion The ratio of the length x of the directional component parallel to the exit surface of the region X and the length P of the directional component parallel to the exit surface of the entire contour line is 0.15 to 0.80. A light diffusing plate according to claim 1 or 2 is provided.

According to this configuration, the convex portion is formed on the emission surface, and the inclination of the contour line of the cross section in at least one predetermined direction cut by a plane that includes the top of the convex portion and is orthogonal to the emission surface is less than θ. As a result, light exiting in an unnecessary direction greatly deviating from the front of the light incident at an angle α is suppressed, and the region X in which the absolute value of the inclination θ2 with respect to the exit surface is less than Sin ⁻¹ (1 / n) As a directional component parallel to the exit surface on the contour line, it is included at a ratio of 0.15 to 0.80 of the exit surface, and the region X includes the top, so that it becomes a region showing different light diffusibility, and the ratio of the region X is By adjusting, the balance between light collection and diffusion can be adjusted, and the incident light can be emitted in a suitable angular distribution.

According to a fourth aspect of the present invention, in the light control member, the contour line in the light emission portion of the cross section along at least a predetermined direction including the top of the convex portion is perpendicular to the emission surface, The lighting device according to any one of claims 1 to 3, comprising two substantially straight lines having an acute angle θ intersecting each other, and a convex curve connecting the respective ends of the two substantially straight lines.
According to this configuration, the contour line of the convex portion has a shape having two substantially straight lines extending in the intersecting direction of the acute angle θ and a convex curve connecting the respective ends thereof. The light collection efficiency and the diffusion efficiency are different between the portion and the curved portion.

According to a fifth aspect of the present invention, the light source is a linear light source, and a plurality of convex portions are formed on the exit surface of the light control member, and are orthogonal to the exit surface, and the on the exit surface. 5. The ridge line in the light emitting portion, which is cross-sectioned in a direction parallel to the linear light source including the top of the convex portion, is a straight line extending in a direction parallel to the linear light source. A lighting device is provided.
According to this configuration, since the linear direction of the ridge line formed on the emission surface is parallel to the longitudinal direction of the linear light source, the light that travels directly above the linear light source and enters the light control member is emitted. A part is totally reflected by the convex part on the surface side.

A sixth aspect of the present invention provides the illumination device according to any one of the first to fourth aspects, wherein the light source is a point light source.
According to this configuration, even when the plurality of light sources are point light sources, the luminance is uniform as in the case of the linear light source described above.

Invention of Claim 7 provides the light control member with which the illuminating device in any one of Claims 1-6 is provided.
With this light control member, the outgoing light distribution in the front direction can be made uniform.

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

  According to this configuration, 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.

  According to the first aspect of the present invention, the total light transmittance of the light incident on the light control member at the portion facing the intermediate point between the two adjacent light sources is calculated from the total light transmittance of the light incident on the position facing the light source. Since the distribution of light energy emitted from the light control member can be made uniform in the emission surface, the lamp image is eliminated, the luminance is high, and the luminance in the emission surface is uniform. A lighting device can be obtained.

  In addition, since favorable optical properties can be obtained at an arbitrary point on the incident surface, alignment between the light source and the light control member is unnecessary, and it is possible to flexibly respond to changes in the display size, number of light sources, and arrangement, A lighting device can be manufactured with high productivity. Furthermore, the use of a diffusing material that lowers the light utilization efficiency can be avoided or greatly reduced, and a high light utilization efficiency is achieved.

  Further, in the invention according to claim 1, since the light is effectively condensed by the plurality of convex portions on the emission surface, and diffused and emitted in multiple directions, in addition to the above effect, the light collecting performance In addition, the diffusion performance is improved as compared with the conventional case, and the uniformity of the luminance within the exit surface can be further increased.

  According to the second aspect of the present invention, since the ratio of the light beam emitted from the front direction of the light control member on the emission surface increases, in addition to the effect of the first aspect, the luminance in the front direction is increased accordingly. Has the special effect of improving.

  According to the third aspect of the present invention, it is possible to suppress light emission in an unnecessary direction greatly deviating from the front surface, to adjust the balance between light collection and diffusion, and to emit incident light in a suitable angular distribution.

  In the invention according to claim 4, in addition to the effect of the invention according to claim 1, the degree of light collection and diffusion at the light exit surface is different between the substantially straight portion and the curved portion. Condensing performance and diffusing performance on the exit surface can be further improved, thereby making it possible to more effectively increase the uniformity of the brightness within the exit surface.

  In the invention according to claim 5, since the linear direction of the ridgeline formed on the exit surface is parallel to the longitudinal direction of the linear light source, the light that has traveled directly above the linear light source and entered the light control member Is totally reflected by the convex portion on the exit surface side.

  Since the invention according to claim 6 has a uniform brightness equivalent to that of the linear light source by using a plurality of point light sources, in addition to the effect of the invention according to any one of claims 1 to 4, it is used. The number of point light sources can be determined according to conditions and the like, and the degree of freedom in design increases in terms of selection of the light source type.

  Invention of Claim 7 is a light control member with which the illuminating device in any one of Claims 1-6 is provided. The light control member partially reflects and transmits part of light incident on the incident surface from the incident surface side. This function makes it possible to make the light emission intensity constant.

  In the invention described in claim 8, since the light condensed and diffused by the light control member is transmitted through the transmissive display element, the light source position adjustment is not required and the lamp image is eliminated although it is a simple configuration. It is possible to easily obtain an image display device having excellent brightness even in the exit plane.

In the present invention, the reflector, the light source, and the light control member are arranged in this order from the light incident side to the light emission side, and the light control member includes an incident surface that mainly receives light, and an emission surface that mainly emits light, When the distance between an arbitrary light source X and another light source Y nearest to it is D and the distance between the light source X and the light control member is H, the incident is made at an arbitrary point on the incident surface. The total light transmittance of light incident at an angle of α = Tan ⁻¹ {(D / 2) / H} with respect to the normal direction of the surface is 50% or more, and the total light transmittance is 1.05 to 3 times the total light transmittance of light when light is incident on a point on the surface from the normal direction, resulting in a simple structure and improved productivity and no need to adjust the light source position In addition to eliminating the lamp image, the illumination device and the image have excellent brightness uniformity in the exit surface. I realized the objective of obtaining a Display device at low cost.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the reflector 2, the plurality of light sources 1, and the light control member 4 are arranged in this order from the light incident side to the light emission side, and the light control member 4 has a plurality of regular protrusions. Part 9. As described above, in the illumination device in which the plurality of light sources 1 are arranged between the reflector 2 and the light control member 4, as shown in FIG. 2, a virtual corresponding to the incident surface of the light control member 4. The light incident on the surface 3 has different light incident energies between a portion immediately above each light source 1 and a portion between adjacent light sources 1.
That is, in the region directly above the position of each light source 1, the incident energy is large because it is close to the light source 1. Then, since it is away from the light source 1, the incident energy is small.

  Further, as shown in FIG. 3, in the angular distribution diagram of the incident energy with respect to the virtual surface 3, that is, the luminance distribution diagram with respect to the incident angle, the luminance of the light ray incident on the virtual surface 3 in the vertical direction shows the maximum value. . On the other hand, as shown in FIG. 4, in the angle distribution diagram of the emission energy with respect to the virtual surface 3, that is, the distribution diagram of the luminance with respect to the emission angle, the luminance of the light ray incident on the virtual surface 3 in an oblique direction, The luminance of the light beam in the vicinity of the central position between the light sources shows the maximum value.

  In the illuminating device according to the present invention, as shown in FIG. 5, the distance between an arbitrary light source X and another light source Y located closest to the light source X is D, and the light source X and the light control member 4. When the distance between the light control member 4 and the light control member 4 is H, the light incident on the light incident surface of the light control member 4 is emitted from the light emission surface of the light control member 4 at any point. The light transmittance is in the range of 50% to 100% and has the following relationship.

That is, when light is incident at an angle of α = Tan ⁻¹ {(D / 2) / H} with respect to the normal direction of the incident surface, the total light transmittance R1 of the light is relative to the incident surface. The total light transmittance R2 of the light when the light is incident in the vertical direction is 1.05 to 3.00 times. The ratio R1 / R2 of the total light transmittance is more preferably 1.05 to 2.00 times from the viewpoint of light utilization efficiency.

  Here, when measuring the total light transmittance described above, the width of the light beam of the parallel light to the measurement object is, for example, an uneven shape on the surface of the light control member. In order to reflect the feature of the uneven shape on the total light transmittance, it is necessary that the light is incident on a wide region at least larger than the pitch of the uneven portion.

  FIG. 6 shows a method for measuring the total light transmittance of the parallel light 8 incident on the measuring object 7 having a flat incident surface at an incident angle β. As shown in the figure, a measuring object 7 is placed under the opening 6 of the integrating sphere 5 so as to be closed, and parallel light 8 collimated with a laser beam or a lens is used as a method of the measuring object 7. Incident at an angle β to the line direction.

  Thus, the light transmitted through the measuring object 7 is diffusely reflected in the integrating sphere 5, and the reflected energy is measured by a detector represented by a photomultiplier (not shown). Here, the measurement object 7 is installed as shown, and the output of the detector when the parallel light 8 is incident at an angle β is V (β), and the detector when the measurement object 7 is not installed is the detector. Is V0, the total light transmittance at an angle β is obtained as V (β) / V0.

As shown in FIG. 5, the angle α is an incident angle of a light beam when light emitted from the light source X or the light source Y is incident on the light control member 4 located immediately above the intermediate point between the light source X and the light source Y. It corresponds to. With respect to the total light transmittance, when the light is incident on the light control member 4 from an oblique direction at an incident angle α (≠ 0), rather than the total light transmittance R2 of light when the light is incident on the light control member 4 from the vertical direction. The total light transmittance R1 of the light is higher. For this reason, the emitted light energy of the light control member 4 can be made uniform as a whole in the portion directly above the light sources X and Y and the portion between the light sources X and Y.
Furthermore, since the total light transmittance of the light control member 4 depends only on the incident angle and does not depend on the incident position with respect to the light control member 4, it is not necessary to adjust the positions of the light sources and the light control member 4. . That is, it is not necessary to strictly set the position of the light control member 4 in the in-plane direction when the lighting device is assembled. Therefore, after manufacturing the light control member 4 of the present invention with a large area, it is possible to use one cut out from an arbitrary position according to the required dimensions, so that the productivity of the lighting device can be significantly improved.

Hereinafter, an example of specific means for adjusting the total light transmittance when light enters the light control member 4 from the vertical direction and the oblique direction will be described. First, as a first example of the specific means, a mode in which a plurality of convex portions 9 are provided on the emission surface of the light control member 4 as shown in FIG. FIG. 7 shows a preferred cross-sectional shape in which the convex portions 9 are formed in a stripe shape.
The cross-sectional shape of the convex portion 9 is composed of a contour line that is perpendicular to the emission surface of the light control member 4 and is cross-sectioned along at least one predetermined direction including the top of the convex portion 9. The contour line is composed of two substantially straight lines (parts) 10 having an acute angle θ at which the extension lines intersect, and a curve (part) 11 connecting each end of the two substantially straight lines (parts) 10. The top of the contour line is a convex curve 11.
Here, the predetermined one direction means a direction parallel to the direction from the light source X to the light source Y. Further, the radius of curvature of the curve constituting the top of the contour line may be infinite, that is, a straight line.

FIGS. 18 and 19 show the behavior of light rays when the convex portion 2 having a substantially elliptical cross section is formed on the exit surface. By constructing the convex part in a substantially elliptical shape, the absolute value of the inclination near the convex part skirt is 0 ≦ | Sin ⁻¹ (n · sin (θ−Sin ⁻¹ ((1 / n) · sin α))). −θ | ≦ (π / 12) or less satisfying θ.
In FIG. 18, the oblique incident light 12 incident at an angle α with respect to the normal can be emitted from the light diffusing plate 1 in a substantially front direction by refraction at the skirt 11 of the convex portion.
This is due to the following reason.
Assuming that the slope of the convex skirt is γ, the incident angle to the light diffusing plate 1 is φ1, and the refractive index of the light diffusing plate 1 is n, as shown in FIG. The angle φ5 with respect to the normal direction of the light diffusing plate of the light transmitted from can be obtained as follows.
φ ₂ = Sin ⁻¹ {(sin φ ₁ ) / n}
φ ₃ = γ−φ ₂
φ ₄ = Sin ⁻¹ (n × sin φ ₃ )
φ ₅ = φ ₄ −γ
That is, φ ₅ = Sin ⁻¹ (n · sin (γ−Sin ⁻¹ ((1 / n) · sin φ ₁ ))) − γ

From the gist of the present invention, it is preferable that the light emission direction is the front direction. Therefore, when φ ₁ = α, it is desirable that −15 ° ≦ φ ₅ ≦ 15 °. Further, it is more desirable that −10 ° ≦ φ ₅ ≦ 10 °. Furthermore, it is preferable to select γ so that −5 ° ≦ φ ₅ ≦ 5 °.
For example, assuming that the distance D between the light sources is 33 mm, the shortest distance H from the light source center to the light control member 4 is 15 mm, and the refractive index n of the light control member 4 is 1.6, 47 ° ≦ γ ≦ 65 ° (58 ° ≦ It is desirable that θ ≦ 67 °. Further, it is more desirable that 53 ° ≦ γ ≦ 64 ° (58 ° ≦ θ ≦ 64 °). Furthermore, it is preferable to select γ so that 57 ° ≦ γ ≦ 63 ° (59 ° ≦ θ ≦ 62 °).

The convex top 10 has a region X in which the absolute value θ2 of the inclination with respect to the exit surface is less than Sin ⁻¹ (1 / n). As described above, the slope θ2 of the region X can take a plurality of values. Since θ2 continuously changes due to the curved portion, the dispersion direction can be continuously changed, and higher luminance uniformity can be obtained. Desirably, the slope of an arbitrary point on the top of the convex portion is equal to or smaller than the absolute value of the slope of the convex skirt 11 with respect to the exit surface. This is desirable from the viewpoint of easy molding and easy control of light direction.

  In addition, as shown in FIG. 19, the light 14 incident perpendicularly to the light diffusing plate 1 is emitted with a part dispersed, and at the same time, a part of the light incident on the convex surface returns to the incident side as reflected light 16. As a result, the total light transmittance can be suppressed. Accordingly, it is possible to obtain a lighting device with high luminance uniformity and high luminance.

  As the shape of the convex portion 9, it can be formed into a three-dimensional shape having two substantially straight lines 10 and a section curve 11. The reason for this will be described below. As shown in FIG. 8, the three-dimensional shape of the convex portion 9 is constituted by two substantially slope portions (corresponding to a substantially straight line 10) and a curved surface portion (corresponding to a sectional curve 11) forming an acute angle θ, The obliquely incident light 12 that is obliquely incident on the incident surface 4a of the light control member 4 is refracted by a refraction action at a substantially straight line 10 in the cross section from the light exit surface side of the light control member 4 (substantially perpendicular to the incident surface 4a). In the same direction).

  Further, as shown in FIG. 9, the light 13 incident perpendicularly to the light control member 4 disperses the emission direction in the curved surface portion of the convex portion 9 and at the same time, a part of the light hitting the surface of the convex portion 9 is Since total reflection occurs and the light does not exit, the total light transmittance of the light can be suppressed. By reducing the total light transmittance of the vertical light 13 perpendicularly incident on the light control member 4, it is possible to easily obtain a lighting device with high luminance uniformity and high luminance.

  The ratio A / P of the projected area A of the curved portion 11 to the projected area P of the convex portion 9 of the light control member 4 is preferably 40 to 80%. For example, the area ratio A1 / P1 in FIG. 7 corresponds to the area ratio A / P. When the area ratio A / P is less than 40%, the light dispersion effect is reduced, and the luminance uniformity is lowered. Further, when the area ratio A / P exceeds 80%, the area of the substantially linear portion 10 decreases, and therefore the ratio of the light emitted in the front direction out of the oblique incident light 12 decreases. The luminance uniformity in the exit surface is reduced.

  FIG. 11 shows another shape of the convex portion 9 that can be implemented in the present invention. In this case, a cross-sectional curve (part) 14 is provided in the valley portion of the convex part 9. The cross-sectional curve portion 14 disperses the light emission direction in multiple directions, and an illumination device with high luminance uniformity can be obtained. Further, as means for propagating light in various directions within the light control member 4 to enhance the dispersion effect, means for deflecting parallel light at a plurality of angles on the incident surface of the light control member 4 may be used. . Specifically, it is possible to form a concavo-convex structure having random or periodicity on the incident surface of the light control member 4.

  When the light source is a linear light source, a plurality of convex portions 9 on the emission surface side are formed in a stripe lens arranged in parallel, and the longitudinal direction of the lens is made parallel to the longitudinal direction of the linear light source. be able to. Thereby, the angle distribution adjustment of the outgoing light on the outgoing surface of the light control member 4 is further facilitated.

  The height or depth of the unevenness 17 formed on the emission surface side is preferably 1 μm or more and 500 μm or less. If the thickness exceeds 500 μm, unevenness is observed, leading to deterioration in quality. On the other hand, when the thickness is less than 1 μm, coloring occurs due to the diffraction phenomenon of light, and the quality deteriorates. Further, particularly when using a liquid crystal panel, it is desirable that the average width of the irregularities in the direction parallel to the arrangement direction of the liquid crystal pixels is 1 / 1.5 or less of the pixel pitch of the liquid crystal. When the average width exceeds 1 / 1.5 of the pixel pitch, a moire phenomenon occurs on the surface of the liquid crystal panel, and the image quality of the liquid crystal panel is greatly deteriorated.

When the surface pattern such as the prism shown above is provided, any of extrusion molding, injection molding, 2P molding using an ultraviolet curable resin, and the like can be used. The molding method may be appropriately used in consideration of the size of the prism, the required shape, and mass productivity, and is not particularly limited. Specifically, as an example, the convex portion can be formed as follows.
A bite having the same cross-sectional shape as the convex shape or a cross-sectional shape allowing for resin shrinkage during molding is prepared. Using this cutting tool, a female mold is formed by providing a groove-shaped cut in a flat mold or a roll mold, and a light control member is obtained by extrusion molding using a roll mold.
In addition, when a planar mold is used instead of a roll mold, the stamper is formed by molding the resin once and then electroforming the resin. The light control member is obtained by injection molding using the cut flat female die or stamper. Furthermore, when this planar mold is used, after applying 2P resin to the planar female mold, a transparent sheet as a base material is laminated, and the 2P resin is cured with ultraviolet rays. Thereafter, the light control member can also be obtained by peeling the 2P resin from the planar female mold.

  Here, when the trough inclination angle of the convex portion with respect to the main surface of the light control member is large, the angle forming the groove top portion becomes too small. Therefore, the top of the groove is a problem when cutting a female tool using a cutting tool. Furthermore, in the resin molding process of extrusion molding, injection molding, and 2P molding, the releasability of the resin is lowered, so that mass productivity and mold durability are problems. With respect to these problems, in the present invention, the refractive index of the resin constituting the convex portion of the light control member is set to 1.58 or more. As a result, the angle formed by the troughs of the convex portions with respect to the main surface of the light control member can be reduced, and the above-described problems such as a decrease in the peelability of the resin and a decrease in the mass productivity can be solved.

Examples of such a high refractive index material having a refractive index of 1.58 or more include methacrylic resin, polystyrene resin, polycarbonate resin, cycloolefin resin, methacryl-styrene copolymer resin, and cycloolefin-alkene copolymer resin. And polyester resins.
Various monomers can be selected in order to secure a refractive index of 1.58 or more required in the present invention. For example, as a methacrylate monomer copolymer such as methacrylic resin or methacryl-styrene copolymer resin, aromatic methacrylate such as α-naphthyl methacrylate, halogenated aromatic methacrylate such as p-bromophenyl methacrylate, pentachlorophenyl methacrylate, etc. A monomer etc. can be used conveniently. In addition to styrene, styrene monomer copolymers such as polystyrene resin and methacryl-styrene copolymer resin include halogenated styrene such as o-chlorostyrene and alkylated styrene such as p-methylstyrene. Are listed as monomers that can be used. As the polyester resin, a diol having a bulky functional group such as a fluorene group can be used as a copolymerization monomer. These monomers can be used alone or copolymerized.
Note that by providing a transmissive display element on the lighting device of the present invention, an image display device excellent in luminance uniformity on the display surface can be easily obtained.

Example 1.
The first embodiment of the present invention will be described in detail below. First, a female mold having a cylindrical groove with an angle θ = 50 ° formed by the extension lines of two substantially straight lines 10 in FIG. 7, P1 = 260 μm, and A1 = 182 μm was produced by cutting.
Next, using this female mold, a convex prism was formed on the polycarbonate film surface with an ultraviolet curable resin having a refractive index of 1.6. Further, the surface of the polycarbonate film on which the prism was not formed was bonded to a transparent acrylic plate having a thickness of 2 mm to obtain a light control member on which a convex prism was formed.

  Next, a plurality of linear light sources were installed between the light control member and the reflecting plate. In this case, a plurality of cold-cathode tubes as linear light sources were arranged at intervals of 33 mm, and the surface having the convex portion of the acrylic plate was placed at a position 15 mm from the cold-cathode tube so as to be an emission surface. In this case, the angle α is set to 48 °. A reflective sheet was provided on the surface of the cold cathode tube facing the acrylic plate.

  In this state, the light control member was irradiated with light by turning on the cold cathode tube, and the light control member was observed. As a result, it was possible to obtain an illuminating device in which the lamp image was eliminated and the luminance within the exit surface was uniform. When the incident surface of the light control member used here is irradiated with light at an incident angle α = 48 ° with respect to the normal direction of the incident surface, the total light transmittance R1 of the light is 67%, and the normal direction When irradiated with light, the total light transmittance R2 of the light was 48%, and the ratio R1 / R2 of these total light transmittances was 1.47.

  Next, an experiment for comparing the brightness uniformity between the case where the light control member of the present invention is used in a lighting device and the case where a normal light diffusion plate containing fine particles is used instead of the light control member. Went. First, as shown in FIG. 12A, an opening 20a having a width B was formed in the light-diffusing plate 20 containing fine particles in which the prism-shaped portion was not formed. Next, a cold cathode tube 15, which is a linear light source, was installed between the fine particle-containing light diffusion plate 20 and the reflection plate 2 and turned on. In this case, nothing was placed in the opening 20a of the light diffusing plate 20.

  With the cold cathode tube 15 turned on, the brightness of the light diffusion plate 20 was measured from the front. The measurement result is shown in FIG. As can be seen from this result, the luminance was high in the region directly above the cold cathode fluorescent lamps 15, and the luminance was low between the adjacent cold cathode fluorescent tubes 15 (obliquely upper region). As a result, the brightness difference between the cold cathode fluorescent lamp 15 and the diagonally upper area is large, so the quality such as brightness uniformity on the image display surface is greatly reduced.

  Next, the acrylic plate having the polycarbonate film adhered on both sides, that is, the light control member 4 on which the incident surface prism portion and the output surface unevenness are formed is cut out in accordance with the size of the opening 20a, and the light control member 4 was installed in the opening 20a. In this case, the light control member 4 has the surface on the incident surface prism portion side facing the cold cathode tube 15, and the ridge line direction of the incident surface prism coincides with the longitudinal direction of the cold cathode tube 15. .

  Thereafter, a diffusion sheet was overlaid on the light control member 4. And the said cold-cathode tube 15 was lighted and the brightness on the said diffusion sheet surface was measured from the front direction in the state. The measurement result is shown in FIG. As can be seen from this, when the light control member 4 having a prism portion formed on the incident surface is used, the image of the linear light source 15 is eliminated, and a portion directly above the linear light source 15 and a plurality of parts A substantially uniform luminance was obtained at the portion between the linear light sources 15.

  When the brightness of the portion B in the position range corresponding to the light control member 4 in FIG. 12C and the brightness of the portion C in the position range corresponding to the fine particle-containing light diffusion plate 20 are compared, the brightness of the portion B is It is about 10% higher than the brightness of part C. That is, when the light control member 4 of the present invention is used, a brighter illumination device can be obtained than when the conventional light diffusion plate 20 containing fine particles is used.

  Further, when the light diffusion plate 20 containing fine particles is used to obtain a brightness comparable to that of the light control member 4, the brightness is high directly above the cold cathode tube 15, and a plurality of cold cathodes are obtained. Since a phenomenon in which the luminance is lowered between the tubes 15 is observed, it is difficult to obtain the same luminance as the luminance by the light control member 4.

  By the way, in this embodiment, the inclination angle of the end portion of the convex portion is 65 °, but in order to realize the same refraction action with a refractive index of 1.55, the inclination angle of the end portion of the convex portion is 68 °. In other words, the angle formed by the adjacent convex slopes is 50 ° when the refractive index is 1.6, whereas it is 44 ° when the refractive index is 1.55.

Example 2
The second embodiment of the present invention will be described in detail below.
First, a female die having a groove with an elliptical arc cross section of P1 = 300 μm in FIG. 7 is produced by cutting.
Ellipse formula ^{y = 0.139-8.33x 2 /(1+(1-38.9x 2) (} 0.5)) (- has a shape of 0.15 ≦ x ≦ 0.15 (mm) ).

  Next, using this female mold, a convex prism is formed on the polycarbonate film surface with an ultraviolet curable resin. Further, the surface of the polycarbonate film on which the prism is not formed is bonded to a transparent acrylic plate having a thickness of 2 mm to obtain a light diffusion plate having a convex portion on one side. The refractive index of the light diffusing plate is different between the acrylic plate portion, the polycarbonate portion, and the ultraviolet curable resin portion. The length x of the component in the P1 direction of the portion forming the region X in the middle is 170 μm per convex portion, and the ratio x / P1 = 0.57, which is an index indicating the ratio of the region X.

  Next, a plurality of linear light sources were installed between the light control member and the reflecting plate. In this case, a plurality of cold-cathode tubes were arranged as linear light sources at intervals of 25 mm, and the surface on the side having the convex portion of the acrylic plate was placed at the position of 15.5 mm from the cold-cathode tube center. . In this case, the angle α was set to 38 °. A reflective sheet was provided on the surface of the cold cathode tube facing the acrylic plate.

  In this state, by irradiating the light diffusing plate with light by turning on the cold cathode tube and observing the light diffusing plate, an illuminating device in which the lamp image is eliminated can be obtained. When the incident surface of the light diffusion plate used here is irradiated with light at an incident angle α = 38 ° with respect to the normal direction of the incident surface, the total light transmittance R1 of the light is 67% in the normal direction. When light is irradiated, the total light transmittance R2 of the light is 48%, and the ratio R1 / R2 of these total light transmittances is 1.4.

  By the way, in this embodiment, the inclination angle of the end portion of the convex portion is 65 °, but in order to realize the same refraction action with a refractive index of 1.55, the inclination angle of the end portion of the convex portion is 68 °. In other words, the angle formed by the adjacent convex slopes is 50 ° when the refractive index is 1.6, whereas it is 44 ° when the refractive index is 1.55.

  The light source of the present invention is not limited to a linear light source, and a plurality of point light sources can be used. In FIG. 19, the structural example at the time of installing the point light source 21 between the reflecting plate 2 and the light control member 4 is shown. Even when the point light source 21 is used, the same effect as when the linear light source is used can be expected.

FIG. 14 shows another configuration example that can be used in the present invention. In this configuration, a light diffusion film sheet (diffusion plate) 22 is superimposed on the light exit surface of the light control member 4. In this case, the light diffusion film sheet 22 makes it possible to make the luminance angle distribution of the emitted light more uniform within the emission surface, so that a higher quality illumination device can be obtained.
FIG. 15 shows another configuration example that can be used in the present invention. In this configuration, the polarization separation film 23 is superimposed on the light diffusion film sheet 22. When the polarized light separating film 23 separates orthogonal linearly polarized light, a liquid crystal panel is placed on the light emitting surface, and the transmission polarization axis of the polarized light separating film 23 and the transmission axis of the polarized light separating film 23 on the liquid crystal panel incident surface are matched. Thus, a liquid crystal display device with higher brightness can be obtained.
When the polarization separation film 23 separates clockwise and counterclockwise circularly polarized light, a quarter wavelength plate is superimposed on the exit surface of the polarization separation film 23 and converted to linearly polarized light after passing through the quarter wavelength plate. And the linear polarization direction should just become a direction which corresponds with the transmission axis of the polarization separation film 23 of a liquid crystal panel entrance plane.

  Next, regarding a schematic configuration example of a liquid crystal display device (image display device), a liquid crystal panel is mounted on the light control member 4 to obtain a liquid crystal display device having uniform brightness within the panel display surface. Can do. By using a transmissive display element on the lighting device of the present invention, an image display device having a simple configuration can be easily obtained. A typical example of the transmissive display element is a liquid crystal panel.

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. FIG. 16 shows a configuration example of an image display device in which a lighting device and a display element are combined. In this configuration, the light diffusion film sheet 22 is overlaid on the light control member 4, the polarization separation film 23 is overlaid thereon, and the liquid crystal panel 24 is overlaid thereon. In this case, the transmission polarization axis of the polarization separation film 23 and the transmission axis of the polarization film on the incident surface of the liquid crystal panel 24 are made to coincide with each other.
It should be noted that the present invention can be variously modified without departing from the spirit of the present invention, and the present invention naturally extends to the modified ones.

It is a schematic block diagram which shows one Example of the illuminating device which concerns on this invention. It is an incident energy distribution figure which illustrates typically the incident energy of the light ray which injects into the virtual surface provided on the several light source which concerns on this invention. It is a luminance distribution figure which illustrates typically the brightness | luminance (incident energy) of the light ray which injects into the light control member (virtual surface) just above the linear light source which concerns on this invention. It is a luminance distribution figure which illustrates typically the brightness | luminance (emitted energy) of the light ray which injects into the light control member (virtual surface) between the some linear light sources concerning this invention. It is a schematic block diagram explaining the incident angle of the light ray which injects into the light control member located between the some light sources which concerns on this invention. It is a schematic block diagram explaining an example of the apparatus which measures the angle dependence of the total light transmittance of the light control member which concerns on this invention. It is a schematic block diagram explaining the cross-sectional shape of the convex part in the output surface of the light control member which can be used for this invention. It is a schematic block diagram explaining the advancing state of the light beam when light injects into the diagonal direction with respect to the light control member which concerns on this invention. It is a schematic block diagram explaining the advancing state of the light ray when light is incident on the light control member according to the present invention in the vertical direction. It is a schematic block diagram explaining the relationship between the optical path and angle of the light which is refracted | emitted and radiate | emitted by the output surface convex part with respect to the light control member which concerns on this invention. It is explanatory drawing which shows an example of the cross-sectional shape of the light control member which can be used for this invention. It is explanatory drawing which shows the structure which evaluated another Example of this invention, and its result. It is explanatory drawing which shows the structural example at the time of using a point light source for the light source which concerns on this invention. It is explanatory drawing which shows an example of a structure of the illuminating device which can be used for this invention. It is explanatory drawing which shows another example of a structural example of the illuminating device which can be used for this invention. It is explanatory drawing which shows the structural example which carried the liquid crystal panel on the surface illumination device of this invention, and was set as the liquid crystal display device. It is a schematic block diagram of the conventional illuminating device. It is a schematic block diagram explaining the advancing state of the light ray when light inclines in the diagonal direction with respect to the light diffusing plate which concerns on this invention. It is a schematic block diagram explaining the advancing state of the light ray when light is incident on the light diffusing plate according to the present invention in the vertical direction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source 2 Reflector 3 Virtual surface 4 Light control member 5 Integrating sphere 6 Aperture 7 Measurement object 8 Parallel light 9 Convex part 10 Substantially straight line (part)
11 Curve (part)
12 oblique incident light 13 perpendicular incident light 15 linear light source (cold cathode tube)
20 light diffusion plate 20a opening 21 point light source 22 light diffusion film sheet (diffusion plate)
23 Polarized light separation film 24 Liquid crystal panel (transmission type display element)

Claims (8)

A direct illumination system comprising at least a plurality of regularly arranged light sources, a reflecting plate, and a light control member that controls an emission direction when light from the light source and the reflecting plate is transmitted,
The reflector, the light source, and the light control member are arranged in this order from the light incident side to the light emitting side, and includes an incident surface that the light control member mainly receives, and an emission surface that mainly emits light,
When the distance between an arbitrary light source X and another light source Y nearest to it is D and the distance between the light source X and the light control member is H, the incident is made at an arbitrary point on the incident surface. The total light transmittance of light incident at an angle of α = Tan ⁻¹ {(D / 2) / H} with respect to the normal direction of the surface is 50% or more, and the total light transmittance is 1.05 to 3 times the total light transmittance of light when light is incident on a point on the incident surface from the normal direction;
A lighting device, wherein a plurality of convex portions are formed on an emission surface of the light control member, and the convex portions are made of a material having a refractive index of 1.58 or more.   10 to 50% of light incident at an angle α with respect to the normal direction of the incident surface of the light control member is emitted in an angle range of −15 ° to + 15 ° with the normal direction of the output surface. The lighting device according to claim 1. The incident surface of the light control member is flat, the projection is formed on the exit surface, is orthogonal to the exit surface, and includes a top portion of the projection, and has a light exit portion having a cross section in at least one predetermined direction. When the refractive index of the light diffusing plate is n, the gradient θ of the contour is 0 ≦ | Sin ⁻¹ (n · sin (θ−Sin ⁻¹ ((1 / n) · sin α) )) −θ | ≦ (π / 12) is satisfied, and the absolute value θ2 of the inclination with respect to the exit surface includes a region X that is less than Sin ⁻¹ (1 / n), and the region X represents the top of the convex portion. And the ratio of the length x of the direction component parallel to the exit surface of the region X and the length P of the direction component parallel to the exit surface of the entire contour line is 0.15 to 0.80. The lighting device according to claim 1 or 2   The light control member has an acute angle θ at which an outline intersects an extended line of a contour line in a light emitting portion of a cross section along at least a predetermined direction that is orthogonal to the emission surface and includes the top of the convex portion. The lighting device according to claim 1, comprising: two substantially straight lines, and a convex curve that connects one end of each of the two substantially straight lines.   The light source is a linear light source, a plurality of convex portions are formed on the exit surface of the light control member, the line is orthogonal to the exit surface, and includes the top of the convex portion on the exit surface. 5. The illumination according to claim 1, wherein a ridge line in a light emitting portion sectioned in a direction parallel to the linear light source is a straight line extending in a direction parallel to the linear light source. apparatus.   The lighting device according to claim 1, wherein the light source is a point light source.   The light control member with which the illuminating device of any one of Claims 1-6 is provided.   A transmissive display element is provided on the illuminating device according to claim 1.

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