JP2007103323A - Lighting device, light control member lighting device has, and image display device using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lighting device and an image display device which do not need the adjustment of light source positions, eliminate the lamp image, and excels in uniformizing the luminance in the light outgoing surface. <P>SOLUTION: A light beam direction transformation part transforms light of 80% to 10% out of incident light entering an incident surface from the normal direction. Light of ≥80% out of incident light entering the incident surface from light sources passes through the light beam direction transformation part, and reaches an outgoing light control part. When among the plurality of light sources, D refers to a distance between a prescribed light source and another light source in the nearest vicinity thereof, and H refers to a distance between a prescribed light source and a light control member, a total light beam transmittance of light entering the incident surface of the light control member, which light from the light sources enters, at an angle of α=Tan<SP>-1</SP>((D/2)/H) against the normal direction of the incident surface is ≥50%, and the total light beam transmittance is 1.05 to 3 times a total light beam transmittance of light entering from the normal direction of the incident surface. <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 same.

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, making it 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.

  On the other hand, by changing the light beam direction of the desired proportion of the incident light from the light source, it has been found that the uniformity of luminance is further improved, and intensively studied, and a suitable range for the ratio of changing the light beam direction. As well as finding out, the present inventors have also found a suitable configuration for achieving the two functions of changing the light direction and controlling the ratio of the total light transmittance with a single member.

The invention according to claim 1 made on the basis of the above examination results is an illuminating device including a reflecting plate, a plurality of light sources, and a plate-like light control member,
The light sources are regularly arranged in one virtual plane,
The reflector, a virtual plane on which the light source is arranged, and the light control member are arranged in this order with their main surfaces parallel to each other,
The light control member is
A light beam direction conversion unit for converting the direction of light from the light source;
A light output control unit for controlling the emission energy of the light that has passed through the light beam direction conversion unit,
Of the plurality of light sources, when the distance between the predetermined light source and another light source nearest to the predetermined light source is D and the distance between the predetermined light source and the light control member is H, the light from the light source Is incident on the light incident surface of the light control member at an angle of α = Tan-1 {(D / 2) / H} with respect to the normal direction of the light incident surface. And the total light transmittance is 1.05 to 3 times the total light transmittance of light incident from the normal direction on the incident surface,
The light beam direction conversion unit converts the direction of 80% to 10% of the light incident on the incident surface from the normal direction, and
80% or more of the light incident on the incident surface from the light source passes through the light beam direction conversion unit and reaches the light output control unit.

  The invention according to claim 2 is a base material constituting the light control member, wherein the light control member has a base part, and the light direction change part is dispersed in the base part. 0.01 to 1 part by mass of a light direction changing material having a particle diameter of 1 to 50 μm with respect to 100 parts by weight of the part, and a difference in refractive index between the base material part and the light direction changing material is 0.005 to The illumination device according to claim 1, wherein the illumination device is 0.08.

  A third aspect of the present invention is the illumination device according to the first aspect, wherein the light beam direction changing portion is an uneven structure on the incident surface.

  Invention of Claim 4 is a light control member with which the illuminating device of Claims 1-3 is provided.

  The invention described in claim 5 is an image display device characterized in that a transmissive display element is provided on the illumination device described in claims 1-3.

Invention of Claim 1 is an illuminating device provided with a reflecting plate, a some light source, and a plate-shaped light control member, Comprising: The said light source is regularly arrange | positioned in one virtual plane,
Since the reflector, the virtual plane on which the light source is arranged, and the light control member are arranged in this order with their main surfaces parallel, the light from the light source and the reflector is efficiently emitted. Head to the control member. In addition, the fact that the light source is in one virtual plane is advantageous in terms of reducing the thickness of the apparatus and making the light intensity of the light source uniform. Since the light sources are regularly arranged, the intensity of light incident on the light control member becomes regular and can be suitably controlled by the light control member of the present invention.

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 light incident from the normal direction, that is, from the total light transmittance of light incident directly above the position facing the light source. Will be reasonably high. That is, by making the total light transmittance of light incident on the light control member at a portion facing the intermediate point between two adjacent light sources appropriately higher than the total light transmittance of light incident on the position facing the light source. Since the distribution of the light energy emitted from the light control member can be made uniform in the emission surface, the lamp image is eliminated, and the illumination device having a high luminance and a uniform luminance in the emission surface can be obtained. . Further, the light control member partially reflects the light incident on the incident surface from the incident surface side and partially transmits the light. With this function, the intensity of light emission can be made constant. Therefore, the in-plane distribution of light energy emitted from the light control member is made uniform. In addition, because it has favorable optical properties at any point on the entrance surface, it is not necessary to align the light source and the light control member, and it can flexibly respond to changes in the display size, number of light sources and arrangement, and productivity. A lighting device can be manufactured well. 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.

In addition, by changing the direction of light that is 80% to 10% of the light incident on the incident surface from the normal direction by the light direction conversion unit, it is possible to change the light direction of a suitable ratio, so that the luminance uniformity Can be further increased.
80% or more of the light incident on the incident surface from the light source passes through the light beam direction conversion unit and reaches the light output control unit, so that the effective utilization rate of light is high and the light output of a large amount of light is controlled. Therefore, the luminance is high and preferable light emission control is possible.

  The invention of claim 2 can improve the uniformity of the emitted light by using a light beam direction changing material as a light beam direction changing portion in the base material portion of the light control member. In particular, the light direction changing material is used in an amount of 0.01 to 1 part by mass, and the difference in refractive index between the light direction changing material and the base material portion is 0.005 to 0.08. Can effectively improve the uniformity of the emitted light.

  According to the third aspect of the present invention, since the light beam direction changing portion of the light control member has a concavo-convex structure on the incident surface, the light control member can be easily formed by a general molding method such as injection molding.

  The invention according to claim 4 is a light control member that can be used in the illumination device according to claims 1 to 3, and is not only suitably used in the illumination device, but also the reflector and the light control member in parallel. Illuminating device in which a single light source is disposed so as to emit light toward the light control member therebetween, or a single or multiple light sources are disposed between a plurality of light control members These lighting devices can also be suitably used for display applications such as lighting signs.

  According to the fifth aspect of the present invention, since the light condensed and diffused by the light control member is transmitted through the transmissive display element, the light source position is not required to be adjusted while the configuration is simple, and the lamp image is eliminated. It is possible to easily obtain an image display device having excellent brightness on the exit surface.

  The present invention is a lighting device including a reflector, a plurality of light sources, and a plate-like light control member, wherein the light sources are regularly arranged in one virtual plane, and the reflector, the light source A virtual plane in which the light control members are arranged in this order with their main surfaces parallel to each other, and the light control member is for converting the direction of light from the light source. A light beam direction conversion unit, and a light output control unit for controlling the emission energy of the light that has passed through the light beam direction conversion unit, and among the plurality of light sources, a predetermined light source and another light source closest thereto Is D, and the distance between the predetermined light source and the light control member is H, the incident surface of the light control member on which light from the light source is incident is in the normal direction of the incident surface. In contrast, the total light transmission of light incident at an angle of α = Tan-1 {(D / 2) / H}. And the total light transmittance is 1.05 to 3 times the total light transmittance of light incident from the normal direction on the incident surface, and the light direction conversion The unit converts the direction of 80% to 10% of the light incident on the incident surface from the normal direction, and more than 80% of the light incident on the incident surface from the light source passes through the light direction converting unit. By reaching the light emission control unit, the structure is simple, the productivity is improved, the adjustment of the light source position is unnecessary, the lamp image is eliminated, and the illumination device that is excellent in uniforming the luminance in the exit surface, The objective of obtaining the light control member and the image display device included therein at low cost was realized.

  Further, 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 is emitted within an angle range of −15 ° to + 15 ° with the normal direction of the output surface. Thus, the lighting device has a high front luminance, which is desirable for many applications. This can be controlled by the light emission control unit.

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, while the non-directly above region facing the position between the plurality of light sources 1 (the obliquely upper portion of each 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 of β with respect 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.

  Further, the light control member is suitable for controlling the light output direction of light from a plurality of light sources arranged regularly, and the regular arrangement is defined as D from a predetermined light source for the purpose of the present invention. It is desirable that the intensity of light incident at an angle α defined by H is equal to the intensity of light incident at the same angle α from any other light source, and the light output intensity of each light source is easy to achieve this. It is most desirable that the distance D between any light source and another light source nearest to it is constant, and the distance H between any light source and the light control member is constant.

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 an example of the specific means, as shown in FIG. 1, a mode in which a plurality of convex portions 9 are provided on the emission surface of the light control member 4 as a light output control portion can be mentioned. 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. And 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 slope of the convex part skirt is 0 ≦ | Sin ⁻¹ (n · sin (θ−Sin ⁻¹ ((1 / n) · sin α))) − It is set to be equal to or smaller than θ satisfying θ | ≦ (π / 12).
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 of the transmitted light with respect to the normal direction of the light diffusing plate 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, if 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 1.54, 52 ° ≦ γ ≦ 69 ° (42 ° ≦ It is desirable that θ ≦ 76 °. Further, it is more preferable that 57 ° ≦ γ ≦ 68 ° (44 ° ≦ θ ≦ 66 °). Furthermore, it is preferable to select γ so that 62 ° ≦ γ ≦ 67 ° (46 ° ≦ θ ≦ 56 °).

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.

  Further, as shown in FIG. 19, a part of the light 14 incident perpendicularly to the light diffusing plate 1 is emitted while its direction is 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 emission 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.

  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.

Moreover, when forming the light emission control part as a convex part on the exit surface side, the height or depth 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.
Any of extrusion molding, injection molding, 2P molding using an ultraviolet curable resin, or the like can be used for the convex portion. The molding method may be appropriately used in consideration of the size, shape, and mass productivity of the convex portion, and is not particularly limited.

  Further, a light beam direction control unit is provided as means for increasing the dispersion effect by propagating light in various directions inside the light control member 4.

  The light direction changing material used in the light control member of the present invention is 0.01 to 1 part by weight, preferably 0.05 to 100 parts by weight of the light direction changing material with respect to 100 parts by weight of the base material part constituting the light control member. It is 0.7 mass part, More preferably, it is 0.1-0.5 mass part. When the content is less than 0.01 parts by mass with respect to 100 parts by mass of the base material part, the light diffusibility is not sufficient (describing that the effect of eliminating luminance unevenness is not sufficient), and 1 If it exceeds the mass part, sufficient light transmittance cannot be obtained, and when the light control member is used for a lighting device or the like, sufficient brightness cannot be obtained, which is not preferable.

  Further, the particle diameter of the light beam redirecting material has an average particle diameter in the range of 1 to 50 μm, and preferably in the range of 2 to 30 μm. When the average particle diameter of the light beam redirecting material is smaller than 1 μm, the light control member obtained by dispersing it in the base material portion selectively scatters light having a short wavelength, so that the transmitted light is yellowish. It is easy and not preferable. On the other hand, when the average particle diameter of the light beam redirecting material exceeds 50 μm, the light control member obtained by dispersing in the base material portion has reduced light diffusivity (I want to describe that the effect of eliminating luminance unevenness is insufficient). Or the light beam redirecting material may be easily seen as a foreign object when light passes through the resin. The shape of the light beam redirecting material is preferably an oval or spherical shape, more preferably a spherical shape.

  In addition, the average particle diameter as used in this specification means the average particle diameter obtained by actual measurement using the photograph obtained by electron microscope observation so that it may mention later.

  As the light direction changing material, usually, inorganic and / or organic transparent fine particles having a refractive index different from that of the transparent resin of the base material are used. The difference between the refractive index of the light beam redirecting material and the refractive index of the substrate is 0.005 to 0.08, preferably 0.01 to 0.07, preferably 0.02. More preferably, it is 0.06. If the difference in refractive index is less than 0.005, the light diffusibility is not sufficient (describing that the effect of eliminating the luminance unevenness is not sufficient). The transmittance cannot be obtained, and when the light control member is used for an illumination device or the like, sufficient brightness cannot be obtained, which is not preferable. In the present invention, as described above, so-called internal diffusibility can be imparted by the difference in refractive index between the light beam redirecting material and the base material. By forming irregularities, so-called external diffusibility can be imparted.

  Moreover, it is preferable that the light redirecting material used in the present invention has a refractive index lower than that of the base resin. When the refractive index of the light beam redirecting material is larger than the refractive index of the base material, the light diffusibility increases, but the difference in the Abbe number between the base resin and the light beam direction changing material becomes large, and the diffused light is seen. A color difference tends to occur depending on the angle, which is not preferable. For this reason, it is preferable that the difference in refractive index between the base material and the light direction changing material is not usually too small or too large.

  Examples of inorganic light redirecting materials include calcium carbonate, barium sulfate, titanium oxide, aluminum hydroxide, silica, glass, talc, mica, white carbon, magnesium oxide, zinc oxide, and the like. The surface treatment may be performed. Examples of the organic light redirecting material include styrene polymer particles, acrylic polymer particles, siloxane polymer particles, and fluorine polymer particles, and are reduced by 3% by mass in the air. A high heat-resistant light diffusing agent having a temperature of 250 ° C. or higher and a crosslinked polymer particle having a gel fraction of 10% or higher when dissolved in acetone are suitably used. Of these light redirecting materials, silica, glass, acrylic polymer particles, and siloxane polymer particles are preferably used, and acrylic polymer particles and siloxane polymer particles are more preferably used. Moreover, these light direction change materials can use the 2 or more types as needed.

  The method of mixing the base material used in the light control member of the present invention and the light beam direction changing material is not particularly limited. For example, the light beam direction changing material is mixed in advance with the base material pellet, and this is extruded or injected. A method of forming a light control member in the form of pellets or the like; a method of adding a light beam redirecting material and forming a light control member in the form of pellets when extruding or injection molding the substrate; A method of forming a light control member in the form of pellets by extruding or injection-molding the base material and the master batch product to obtain a desired blending amount again after making the material and the light redirecting material into a master batch be able to.

  Further, the light beam direction conversion section may have a concavo-convex structure on the incident surface. At this time, the suitable surface state of the incident surface having the concavo-convex structure can be based on the total light transmittance, haze, and arithmetic surface roughness. 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.

  The ratio of the light incident on the incident surface from the light source passing through the light beam direction conversion unit and reaching the light output control unit is also measured by measuring the total light transmittance of the light conversion ability measuring member. If the light direction control of the light output control unit can be predicted, the total light transmittance of the light control member can be directly measured and calculated.

  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.

  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.

Measurement methods and evaluation methods of various physical properties in the examples are shown below.
The total light transmittance was measured by using the parallel light 8 collimated with a lens on the light control member by the method shown in FIG.

The rate at which the light beam direction conversion unit converts the direction of light incident on the incident surface from the normal direction is measured as follows. A light conversion ability measuring member having a configuration in which the light control member is not provided in the light control member to be measured is separately prepared. When the light emission control unit is a convex portion formed on the light emission surface of the light control member, the light emission surface of the member for measuring light beam conversion ability is a smooth surface parallel to the incident surface. The incident surface of the member for measuring light conversion ability is irradiated with parallel light from the normal direction, and the ratio of the light whose output direction is changed is measured with a haze meter. In general, the light direction control of the light output control unit can be predicted by normal calculation. In this case, the light direction conversion unit directly measures the luminance angle distribution of the light control member, so that the direction of the light incident on the incident surface from the normal direction. It is also possible to calculate the rate of converting. In Examples and Comparative Examples, measurement was performed using a haze meter (HR-100; manufactured by Murakami Color Research Laboratory Co., Ltd.) by a method based on the (JIS K7136) method.
For the rate at which the light incident on the incident surface of the light control member from the light source passes through the light beam direction conversion section and reaches the light output control section, the total light transmittance of the light conversion ability measuring member is measured, and this value and did. The light conversion ability measuring member was prepared by the same method as the light control member used in the examples except that the light output control unit was not provided.
The light direction changing materials used in the examples and comparative examples were observed with a scanning electron microscope (SEM), and the number average particle diameter was measured by measuring the particle diameter of 200 particles using the obtained photographs. The standard deviation with respect to the number average particle diameter was calculated.
Further, as an index of the particle size distribution, a coefficient of variation (CV value) expressed as a percentage (%) was obtained by the following equation.
CV = (standard deviation with respect to average particle size / average particle size) × 100

  The following examples and comparative examples were evaluated using an illumination device having the following configuration. The light output control part of the light control member is a ridge-like convex part with a width of 0.3 mm and a depth of 0.2 mm arranged in parallel on the emission surface, and using a mold provided with a groove-like parallel concave part, It is formed by injection molding.

The main surface size of the light control member is 707 mm × 436 mm and has a thickness of 2 mm.
The material of the reflector is foamed PET resin and the reflectance is 95%.
A rectangular parallelepiped white ABS resin housing having a rectangular opening of 458 mm × 730 mm × 35 mm and 698 mm × length 416 mm on the emission side is prepared.
Next, the reflection plate is disposed so as to cover a bottom portion at a position facing the opening on the emission side of the housing.

Next, a linear light source is arranged in parallel with the reflecting plate with an interval of 2 mm on the exit side of the reflecting plate. As the linear light source 1, a plurality of cold-cathode tubes having a diameter of 3 mm and a length of 700 mm are arranged along the X direction and parallel to the Y direction. Sixteen cold cathode tubes are arranged at intervals of 22 mm.
Next, the light control member is disposed so as to cover the opening.
The distance from the center of the linear light source to the light control member is 15.5 mm, and the distance between the centers of the adjacent linear light sources is 25 mm.

Example 1.
Methacryl styrene copolymer resin pellets (TX-800S: manufactured by Potential Chemical Industry Co., Ltd., refractive index nD: 1.55) and methyl methacrylate polymer particles (MBXR-8N: Sekisui Plastics Co., Ltd.) After being mixed with a Henschel mixer, a light control of 340 mm in width, 270 mm in length and 2 mm in thickness by injection molding (extrusion resin temperature 280 ° C.). A member was prepared. The above lighting device was assembled and evaluated using this light control member. The evaluation results are shown in FIG.

Example 2
Light in the same manner as in Example 1 except that 0.13% by weight of methyl methacrylate polymer particles (MBXR-8N: manufactured by Sekisui Plastics Co., Ltd., number average particle diameter 8 μm, CV value 25%) was used. A control member was created. The above lighting device was assembled and evaluated using this light control member. The evaluation results are shown in FIG.

Example 3
Styrene copolymer resin pellets (G-100C: manufactured by Toyo Styrene Co., Ltd., refractive index nD: 1.59) and methyl methacrylate polymer particles (SMX-8V: manufactured by Sekisui Plastics Co., Ltd.) After mixing with a Henschel mixer, a light control member having a width of 340 mm × length of 270 mm and a thickness of 2 mm is mixed with a Henschel mixer. Produced. The above lighting device was assembled and evaluated using this light control member. The evaluation results are shown in FIG.

Example 4
Light in the same manner as in Example 3 except that 0.25% by weight of methyl methacrylate polymer particles (MBXR-8N: manufactured by Sekisui Plastics Co., Ltd., number average particle diameter 8 μm, CV value 25%) was used. A control member was created. The above lighting device was assembled and evaluated using this light control member. The evaluation results are shown in FIG.

Example 5 FIG.
Methacryl styrene copolymer resin pellets (TX-800S: manufactured by Potential Chemical Industry Co., Ltd., refractive index nD: 1.55) were injection molded (extruded resin temperature 280 ° C.), 340 mm wide × 270 mm long, 2 mm thick A light control member was prepared. At this time, a textured surface was formed on the incident surface side by a molding die. The above lighting device was assembled and evaluated using this light control member. The evaluation results are shown in FIG.

Comparative Examples 1-4.
In Comparative Examples 1 and 2, instead of the light control member, a plate of horizontal 340 mm × longitudinal 270 mm and thickness 2 mm in which a light beam redirecting material is dispersed in a base material is used.
In Comparative Examples 3 and 4, instead of the light control member, a plate having a width of 340 mm, a length of 270 mm, and a thickness of 2 mm is used, which has a textured surface formed on the incident surface side.
In addition, Comparative Examples 1-4 does not have a light emission control part.
The evaluation results of these comparative examples 1 to 4 are shown in FIG.

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 a table | surface which shows the evaluation result of Examples 1-5 of this invention, and Comparative Examples 1-4. 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 (5)

A lighting device comprising a reflector, a plurality of light sources, and a plate-like light control member,
The light sources are regularly arranged in one virtual plane,
The reflector, a virtual plane on which the light source is arranged, and the light control member are arranged in this order with their main surfaces parallel to each other,
The light control member is
A light beam direction conversion unit for converting the direction of light from the light source;
A light output control unit for controlling the emission energy of the light that has passed through the light beam direction conversion unit,
Of the plurality of light sources, when the distance between the predetermined light source and another light source nearest to the predetermined light source is D and the distance between the predetermined light source and the light control member is H, the light from the light source Is incident on the light incident surface of the light control member at an angle of α = Tan-1 {(D / 2) / H} with respect to the normal direction of the light incident surface. And the total light transmittance is 1.05 to 3 times the total light transmittance of light incident from the normal direction on the incident surface,
The light beam direction conversion unit converts the direction of 80% to 10% of the light incident on the incident surface from the normal direction, and
80% or more of the light incident on the incident surface from the light source passes through the light beam direction conversion unit and reaches the light output control unit.   The light control member has a base material portion, and the light beam direction conversion portion is a light beam direction conversion material dispersed in the base material portion, and particles with respect to 100 parts by mass of the base material portion constituting the light control member. 0.01 to 1 part by mass of a light direction changing material having a diameter of 1 to 50 μm is contained, and a difference in refractive index between the base material part and the light direction changing material is 0.005 to 0.08. The lighting device according to claim 1.   The illuminating device according to claim 1, wherein the light beam direction conversion unit is an uneven structure on the incident surface.   The light control member with which the illuminating device of Claims 1-3 is provided.   An image display device comprising a transmissive display element on the illumination device according to claim 1.

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