JP2006140124A - Lighting system and image display apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lighting system and an image display apparatus in which it is not necessary to adjust the position of light sources, a lamp image is eliminated and the luminance in an outgoing plane is excellently uniformalized. <P>SOLUTION: In the lighting system, a reflector 2, light sources 1 and a light control member 4 are sequentially disposed from a light incident side to a light outgoing side. The light control member 4 has an incident plane and an outgoing plane. When a distance between an arbitrary light source X and another light source Y most adjacent thereto is D, and a distance between the light source X and the light control member 4 is H, the total light transmittance of the light entering to an arbitrary point on the incident plane at the angle α=Tan<SP>-1</SP>ä(D/2)/H} to the normal direction of the incident plane is more than 50%, and 1.05-3.0 times as much as that of the light entering the point on the incident plane in the normal direction. A plurality of projection portions 9 are formed on the outgoing plane, and 10-50% of the light entering at the incident angle α outgoes at the outgoing angle -15° to +15°. <P>COPYRIGHT: (C)2006,JPO&NCIPI

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 illumination signage device, liquid crystal display device and the like that are required to have high luminance and luminance uniformity. The present invention relates to a direct 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 light diffusing material is applied to the film surface.

  Therefore, a diffusion plate containing a light diffusing material is widely used. In this method, for example, as shown in FIG. 23, 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. A method using a light diffusion plate that has been used has been studied (for example, see Patent Document 2).

  However, these methods using a light diffusing material are not preferable from the viewpoint of energy saving because the light use efficiency decreases due to light absorption into the light diffusing material and 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. However, from the viewpoint of energy saving, a large amount of light diffusing material is used to eliminate the lamp image. It must be avoided by means of greatly reducing the utilization efficiency.

Japanese Patent Laid-Open No. 2-17 JP 54-155244 A Japanese Patent No. 2852424 JP 2000-338895 A JP 2002-352611 A US Pat. No. 5,161,041

  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 is to provide an apparatus and an image display apparatus using the same.

  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 significantly reduce the use of a light 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 that is 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. And the total light transmittance is such that light is transmitted from a normal direction to a point on the incident surface. To provide a lighting device which is 1.05 to 3 times of total light transmittance of light when the shines.

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.

  According to a second aspect of the present invention, there is provided the lighting device according to the first aspect, wherein a plurality of convex portions are formed on the emission surface of the light control member.

  According to this configuration, since the plurality of convex portions are formed on the emission surface, the light incident on the light control member and directed toward the emission surface is diffused and emitted in multiple directions by the plurality of convex portions. The

  According to a third aspect of the present invention, the absolute value of the slope inclination of the convex portion formed on the light exit surface of the light control member is defined as U and the light control member of the unit convex portion is U. The ratio of the projected area of U to the light control member with respect to the projected area is in the range of 0.2 to 0.8, and the illumination device according to claim 1 or 2 is provided.

  According to this configuration, out of the light incident on the light control member corresponding to the position between the light sources, the light incident on the region U is emitted substantially in the front direction, so that in-plane luminance uniformity can be obtained. .

  According to a fourth aspect of the present invention, the contour line in the light emission part of the cross section that is orthogonal to the emission surface of the light control member and includes the top of the convex part along at least one predetermined direction is an extension line. The illumination device according to claim 1, comprising two substantially straight lines having an acute angle θ intersecting with each other and a convex curve connecting each end 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. Therefore, the light condensing function and the diffusing function can be realized at the same time by appropriately selecting the ratio of the straight part and the curved part.

  According to a fifth 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. The illumination device according to claim 1, 2, 3, or 4 that emits light in a 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 sixth aspect of the present invention, the light control member has a plurality of convex portions formed on the incident surface, includes a top portion of the convex portions, and has a contour line sectioned from a direction orthogonal to the incident surface. 6. The light that includes two substantially straight lines sandwiching the top of the convex portion and that irradiates the light control member from the light source at a plurality of angles on the incident surface. A lighting device is provided.

  According to this configuration, since light is deflected at a plurality of angles on the incident surface, the latter has a total light transmittance for light incident in a direction perpendicular to the incident surface and light incident in an oblique direction. Becomes higher than the total light transmittance of the former. Furthermore, a part of the light incident in the oblique direction is emitted at an angle close to the perpendicular to the light control member by being totally reflected inside the convex portion formed on the incident surface. That is, the luminance in the normal direction between the light sources can be improved and the uniformity of the in-plane luminance distribution can be improved.

  According to a seventh aspect of the present invention, the light source is a linear light source, and a plurality of convex portions are formed on the emission surface of the light control member, orthogonal to the emission surface, and the light source on the emission surface. 6. A ridge line in a light emitting portion, which is cut in a direction parallel to the linear light source including the top of a convex portion, is a straight line extending in a direction parallel to the linear light source. Or the illuminating device of 6 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.

  According to an eighth aspect of the present invention, a layer having a thickness of 1 μm or less made of a material having a refractive index lower than that of the base material of the light control member is provided on at least one of the incident surface and the emission surface of the light control member. The lighting device according to claim 1, wherein at least one layer is formed.

  According to this configuration, since a thin (1 μm or less) layer made of a material having a refractive index smaller than that of the light control member is formed on the incident surface or the output surface of the light control member, the light control member is perpendicular to the light interference effect. The transmittance of obliquely incident light can be made larger than the transmittance of incident light.

  A ninth aspect of the present invention provides the illumination device according to the first, second, third, fourth, fifth, sixth or eighth aspect, 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.

  According to a tenth 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 ninth aspects.

  According to this configuration, since the transmissive display element such as a liquid crystal panel is provided on the illumination device, the light rays that are efficiently condensed and diffused by the light control member are transmitted through the transmissive display element.

  The present invention is a direct lighting system including 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 emission side, the light control member includes an incident surface that mainly receives light, and an emission surface that mainly emits light, and is adjacent By making the total light transmittance of light incident on the light control member at a portion facing the intermediate point of the two light sources moderately higher than the total light transmittance of light incident on the position facing the light source, the light Since the distribution of the light energy emitted from the control member in the exit surface can be made uniform, a lamp image is eliminated, the brightness is high, and the light utilization efficiency is high. To get Kill.

  The light control member used in the present invention can obtain favorable optical properties at an arbitrary point on the incident surface, so that alignment between the light source and the light control member is unnecessary. Further, the ratio of the total light transmittance of the light incident on the position facing the light source and the light incident on the position facing the middle of the adjacent light sources is related to the distance between the light sources and the distance between the light source and the light control member. ing. For this reason, it is possible to flexibly respond to changes in the display size, the number of light sources, and the arrangement for responding to the demands for enlargement, thinning, energy saving, etc., and the lighting device can be manufactured with high productivity. In addition, since high brightness, brightness uniformity, and brightness angle distribution desirable as a lighting device can be easily obtained, the use of a functional optical film or a light diffusing material can be avoided or greatly reduced.

  In 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 can be eliminated. It is possible to easily obtain an image display device having excellent brightness on the exit surface.

The present invention includes the reflector, the light source, and the light control member arranged in this order from the light incident side toward the light emission side, and includes an incident surface on which the light control member mainly receives light, and an output surface on which light is mainly emitted. 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 has excellent brightness uniformity in the exit surface, and We realized the objective of obtaining an image display device at low cost.

  Furthermore, since the total light transmittance of the light control member depends only on the incident angle and does not depend on the incident position with respect to the light control member, it is not necessary to adjust the positions of the light sources and the light control member. That is, it is not necessary to strictly set the position of the light control member in the in-plane direction when the lighting device is assembled. Therefore, after the light control member of the present invention is manufactured with a large area, it is possible to use a light control member cut out from an arbitrary position according to a required dimension, so that the productivity of the lighting device can be remarkably improved.

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 shown in FIG. 2, in the illuminating device in which a plurality of light sources 1 are arranged on the reflector 2, the light incident on the virtual plane 3 perpendicular to the front direction (up in the drawing) Incident energy is different between the portion immediately above the light source 1 and the portion immediately above each of the adjacent light sources 1. Since the virtual surface 3 corresponds to the incident surface of the light control member 4 in FIG. 1, this means that the incident energy to the light control member 4 is directly above each light source 1 and immediately above each adjacent light source 1. It means different in the part between.

  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.

  FIG. 3 is an explanatory diagram showing the relationship between the incident angle of the light beam incident on the virtual surface 3 directly above the position of the light source 1 in FIG. 2 and the incident energy. Here, the incident angle of the configuration means an angle with respect to the normal line of the virtual plane 3. As shown in FIG. 3, the luminance of the light ray that enters perpendicularly to the virtual surface 3 is the highest. Furthermore, as the traveling direction of the light beam deviates from vertical and the incident angle increases, the luminance gradually decreases.

  On the other hand, FIG. 4 is a diagram for explaining the relationship between the incident angle of light rays incident on the virtual plane 3 corresponding to the portion between the light sources 1 in FIG. 2 and the incident energy. As shown in the figure, the luminance of light rays that are perpendicularly incident on the virtual plane 3 is low, and the incident direction of the light rays deviates from the normal direction, and peaks at an angle at which the nearest light source is viewed.

  FIG. 5 is a view showing the positional relationship between an arbitrary light source X and another light source Y, the reflector 2 and the light control member 4 which are located nearest to the light source X in the illumination device according to the present invention. When the distance between an arbitrary light source X and another light source Y located closest to the light source X is D and the distance between the light source X and the light control member 4 is H, the incidence of the light control member 4 With respect to an arbitrary point on the surface, the total light transmittance is 50% or more with respect to the ratio at which light incident on the incident surface at an angle α shown below is emitted from the exit surface of the light control member 4. Or in the range of 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.

  The angle α corresponds to the incident angle of a light beam when light emitted from the light source X or the light source Y enters the light control member 4 at a position immediately above the intermediate point between the light source X and the light source Y. 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.

  FIG. 6 shows a method for measuring the total light transmittance necessary for selecting the light control member used in the present invention. In the parallel light 8 incident on the measurement object 7 having a flat incident surface at an incident angle β, the measurement object 7 is closed so as to be closed below the opening 6 of the integrating sphere 5 as shown in FIG. The collimated light 8 collimated with a laser beam or a lens is incident at an angle β with respect to the normal direction of the measurement object 7.

  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 (not shown) represented by a photomultiplier. 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.

  Here, in the present invention, when measuring the total light transmittance, the width of the light beam of the parallel light to the measurement object is, for example, an uneven shape when the uneven shape is formed 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 not to be incident on a minute region such as only a slope, but to be incident on a wide region at least larger than the pitch of the uneven portion. is there.

  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, there may be mentioned a mode in which a plurality of convex portions 9 are provided on the exit surface of the light control member 4 as shown in FIG. The following shape is preferable as the cross-sectional shape when the convex portion 9 is crossed along at least one predetermined direction including the top of the convex portion 9 perpendicular to the emission surface of the light control member 4. .

  That is, the ratio of the projected area on the light control member of U to the projected area on the light control member of the unit convex portion is 0.2, where U is a range where the absolute value of the inclination of the contour line is 50 ° to 70 °. It is in the range of ~ 0.8.

  FIG. 28 shows a contour line and a contour when the light control member 4 is provided with a plurality of convex portions 9 on the exit surface, and is crossed along a predetermined direction including the apex perpendicular to the exit surface. It is a figure which shows the relationship of the inclination of each point on a line. When the range in which the absolute value of the inclination of the contour line is 50 ° to 70 ° is U, the ratio of the projected area of U on the light control member to the projected area of the unit convex portion on the light control member is 0.2. It is in the range of ~ 0.8. When the ratio of the projected area of U to the light control member with respect to the projected area of the unit convex portion on the light control member is less than 0.2, the ratio of the light emitted in the front direction of the oblique incident light 12 is decreased. In-plane uniformity is reduced. On the other hand, if this ratio exceeds 0.8, the light dispersion effect is reduced and the luminance uniformity is lowered.

  Here, the ratio of the projected area of the region U onto the light control member is preferably in the range of 0.4 to 0.75 from the viewpoint of luminance uniformity within the exit surface, and more preferably 0.5 to 0. Is more preferably in the range of .7. The predetermined one direction is a direction in which the cross-sectional shape exhibits the light control performance most remarkably, and means a direction parallel to the direction from the light source X to the light source Y.

  As shown in FIG. 29, the light 13 incident perpendicularly to the light control member 4 is distributed in the emission direction around the apex where the absolute value of the inclination that does not correspond to the region U of the convex portion 9 is small, and the surface corresponds to the region U. The incident light also disperses the emission direction, and the light that hits the surface near the bottom of the convex portion 9 corresponding to the region U of the convex portion 9 does not emit with total reflection, and the total light transmittance of the light can be suppressed. It becomes. 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.

  In order to prevent the region U from being incident on the light control member 4 perpendicularly, the region U is not at least near the top of the convex portion 9 but near the bottom, and the top is inclined more than the region U. It is preferable that it consists of an area | region where the absolute value of is small.

  However, when the adjacent convex portions are in contact with each other at the skirt portion as shown in FIG. 29, when the hem end portion is formed by the region U, the mold for molding this becomes a sharp convex shape. Shaping defects due to deformation are likely to occur. In order to prevent this, it is preferable to set the absolute value of the inclination of the narrow region of the valley of the convex portion 9 small.

  Although not shown in the figure, the region where the absolute value of the convex portion exceeds 70 ° is also totally reflected, but the reflection angle is 40 ° or less with respect to the vertical direction. Therefore, it is difficult to suppress the total light transmittance.

  As shown in FIG. 30, the oblique incident light 12 that is obliquely incident on the incident surface 19 of the light control member 4 is refracted so as to be in a substantially vertical direction (substantially perpendicular to the incident surface 19) from the emission surface side of the light control member 4. In the same direction).

When the inclination of the tangent line of the convex slope with respect to the incident surface 19 of the light control member 4 is an angle γ,
γ = (π−θ) / 2
It can be expressed as Here, when the incident angle to the light control member 4 is φ1 and the refractive index of the light control member 4 is n, as shown in FIG. The angle φ5 with respect to the normal direction of the light control member 4 can be obtained as follows.

φ2 = Sin ⁻¹ {(sin φ1) / n}
φ3 = γ−φ2
φ4 = Sin ⁻¹ (n × sin φ3)
φ5 = φ4-γ

Here, φ4 ≦ 90 ° needs to be satisfied, while 0 ≦ γ,
0 ≦ γ ≦ Sin ⁻¹ (1 / n) + Sin ⁻¹ {(sin φ1) / n}
It becomes.

  For example, when the distance D between the light sources is 33 mm and the shortest distance H from the light source center to the light control member 4 is 15 mm, φ1 (= α) is approximately 48 ° at the center position between the light sources. When the refractive index n is 1.54, 0 ° ≦ γ ≦ 69 °. That is, if γ is greater than 69 °, the incident light enters the light control member and then enters the light exit surface at an angle exceeding the critical angle. It will come out.

  From the gist of the present invention, it is preferable that the emission direction of the light beam is as front as possible with respect to the light control member 4. Therefore, it is desirable that −15 ° ≦ φ5 ≦ 15 ° when φ1 = α. Further, it is more desirable that −10 ° ≦ φ5 ≦ 10 °. Furthermore, it is excellent and preferable to select γ so that −5 ° ≦ φ5 ≦ 5 °. And it is preferable from a viewpoint of the uniformity of a brightness | luminance that the light which injects into the area | region where (gamma) was selected so that it may be -15 degrees <= φ5 <= 15 degrees is in the range of 10 to 50% of all the incident lights. .

  For example, as described above, when 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, the desirable range of γ is 51. ° ≦ γ ≦ 69 ° (42 ° ≦ θ ≦ 78 °), a more preferable range is 57 ° ≦ γ ≦ 68 ° (44 ° ≦ θ ≦ 66 °), and a more preferable range is 62 ° ≦ γ ≦ 67. ° (46 ° ≦ θ ≦ 56 °).

  From the above relationship between the incident angle φ1, the absolute value γ of the convex portion inclination, and the outgoing angle φ5, in the illumination device suitable for the present invention, the region of the light incident on the point facing the light source of the light control member The light refracted and emitted on the slope of U is emitted near the front, and when oblique incident light is refracted and emitted on the slope other than the region U, the light is emitted obliquely with respect to the normal direction of the light control member. In order to prevent the emitted light from re-entering the adjacent convex portion and returning to the light source side, it is effective to arrange the center of the region U outside the center of the convex portion piece side.

  As shown in FIG. 4, light having a symmetric distribution is incident at a position corresponding to between light sources. Therefore, by making the convex section cross-sectional shape symmetrical, it is possible to have an outgoing light distribution that is symmetric with respect to the vertical direction of the light control member.

  FIG. 7 shows an example of a suitable cross-sectional shape in which the convex portions 9 are formed in a stripe shape. By forming the three-dimensional shape of the convex portion 9 by two substantially inclined portions (corresponding to a substantially straight section 10) and a curved surface portion (corresponding to a sectional curve 11) forming an acute angle θ, the substantially straight portion and the curve are formed. Since the degree of condensing and diffusing on the light exit surface is different from that of this part, the condensing performance and diffusing performance on the exit surface are further improved, so that the brightness in the exit surface can be made more uniform. Can be increased.

  In addition, as shown in FIGS. 8 and 9, in such a shape, light incident from the same direction and hitting the substantially straight portion 10 is refracted or reflected in the same direction, so that the light output direction can be easily controlled, and a desirable luminance angle. Optical design for obtaining the distribution is facilitated. As shown in FIG. 8, the oblique incident light 12 obliquely incident on the incident surface 19 of the light control member 4 is refracted at the portion of the substantially straight line 10 in a substantially vertical direction (from the emission surface side of the light control member 4). The light can be emitted in the same direction as the vertical direction of the incident surface 19. In addition, the curvature radius of the curve which comprises the top part of an outline may be infinite, ie, a straight line.

  As the shape of the convex portion 9, two substantially straight lines 10 and a section curve 11 may be formed in a substantially conical or substantially trapezoidal three-dimensional shape having all directions.

  FIG. 11 shows another shape of the convex portion 9 that can be implemented in the present invention. In this case, a valley portion 14 is provided in the valley portion of the convex portion 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.

  Moreover, since the tip of the convex portion of the mold for molding the trough portion 14 has a blunt shape that is curved, there is a problem of shaping failure due to the deformation of the convex portion of the mold as compared with a sharply sharp shape. Less likely to occur. Note that the radius of curvature of the curve forming the top of the contour line may be infinite, and at this time, the curve forming the top is a straight line.

  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.

  Next, FIG. 12 shows a configuration example of another light control member 4 according to the total light transmittance adjusting means. In this configuration, a plurality of linear light sources 15, a reflecting plate (not shown) that reflects light from the linear light sources 15, and light control that diffuses and transmits light from the linear light sources 15 and the reflecting plate. In the direct illumination device including the member 4, a plurality of striped prisms 16 are parallel to the longitudinal direction of the linear light source 15 on the incident surface of the light control member 4 on the side facing the linear light source 15. Is formed.

  The stripe prism 16 has a vertex angle of 30 ° to 60 ° at the ridge line portion facing the linear light source 15. Further, a plurality of irregularities 17 are formed on the light exit surface of the light control member 4. The output surface unevenness 17 is also formed in a stripe shape, and the longitudinal direction of the stripe unevenness 17 has a parallel relationship with the longitudinal direction of the light incident surface side stripe prism 16.

  As shown in FIG. 12, the normal incident light 13 incident in the direction directly above the linear light source 15 is refracted by the inclined surface of the prism 16 formed on the incident surface, and after the refraction, the unevenness 17 formed on the output surface causes the light to be reflected. Some are totally reflected. Thereby, since the transmission ratio of the light incident perpendicularly to the light control member 4 is reduced, the total light transmittance by the light control member 4 can be controlled.

  As shown in FIG. 13, the light incident between the linear light sources 15, that is, the oblique incident light 12 with respect to the light control member 4 is refracted and totally reflected by the prism 16 formed on the incident surface, and the light control member 4. The light is emitted substantially in the front direction. Thereby, the brightness | luminance of the front direction vicinity between each linear light source 15 can be improved.

  FIG. 14 shows a configuration example of still another light control member 4 that can be used in the present invention. In the light control member 4 that diffuses and transmits the light emitted from the plurality of linear light sources 15, the longitudinal direction of the linear light source 15 is formed on the incident surface of the light control member 4 that faces the linear light source 15. A plurality of stripe prisms 16 extending in parallel with the direction are formed, and a flat portion 18 having a predetermined length is provided between the plurality of prisms 16. The light output surface of the light control member 4 is formed with a plurality of light emission surface irregularities 17 extending in parallel with the longitudinal direction of the stripe prism 16, and the light emission surface irregularities 17 have a cross-sectional shape composed of a prism shape or the like. Have. As a result, the in-plane brightness was made uniform.

  As shown in FIG. 14, the normal incident light 13 incident on the linear light source 15 is refracted by the prism 16 formed on the incident surface, and part of the light is totally reflected by the unevenness 17 formed on the output surface. Thereby, it is possible to control the transmittance of the vertical light 13 incident perpendicularly to the light control member 4. Further, the flat portion 18 formed between the plurality of prisms 16 on the incident surface side makes it easy to adjust the light transmittance by the light control member 4. The ratio of the flat portion 18 to the entire incident surface is preferably 40% or less.

  As shown in FIG. 15, the obliquely incident light 12 incident between the linear light sources 15 is refracted and totally reflected by a prism 16 formed on the incident surface, and is emitted substantially in the front direction. Thereby, the brightness | luminance in the front direction between the linear light sources 15 can be improved.

  FIG. 16 shows the traveling direction of light when total reflection occurs inside the prism 16 formed on the incident surface of the light control member 4. Assuming that the incident angle of the incident light 100 with respect to the normal direction of the incident surface of the light control member 4 is ε1, after the total reflection by the prism 16 formed on the incident surface, the normal line of the traveling light 25 inside the light control member 4 The angle ε5 with respect to the direction can be calculated as follows.

ε2 = δ1−ε1
ε3 = Sin ⁻¹ {(sin ε2) / n}
ε4 = δ1-ε3 + δ2-90 °
ε5 = 90 ° − (ε4 + δ2)
From the gist of the present invention, the light emission direction is preferably the front direction of the light control member 4, that is, the same direction as the normal direction. For this purpose, it is preferable that the traveling light 25 travels in the normal direction of the emission surface inside the light control member 4. Therefore, when ε1 = α, it is desirable that −20 ° ≦ ε5 ≦ 20 °. Further, it is more desirable that −10 ° ≦ ε5 ≦ 10 °. Furthermore, it is preferable to select δ1 and δ2 so that −5 ° ≦ ε5 ≦ 5 °.

  For example, assuming that the distance D between the light sources is 33 mm, the distance H between the light source center and the light control member 4 is 15 mm, and the refractive index n of the light control member 4 is 1.54, 55 ° ≦ δ1 ≦ 72 °. desirable. Further, it is more desirable that 59 ° ≦ δ1 ≦ 67 °. Furthermore, it is preferable to select 61 ° ≦ δ1 ≦ 65 °.

  The height or depth of the irregularities 17 formed on the emission surface side is desirably 1 μm or more and 1000 μm or less. When the thickness exceeds 1000 μm, unevenness is observed, so that the quality is lowered. 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. Moreover, it is desirable that it is 10 micrometers or more and 500 micrometers or less. Furthermore, 30 μm or more and 300 μm or less are more preferable.

  Also, the prism formed on the incident surface can have a plurality of inclinations as shown in FIG. In FIG. 33, an entrance plane prism region U1 that is symmetrical to the left and right, a pair of asymmetric prisms U2 that are line symmetric with respect to the center of U1, and a minute gap between U1 and U2 to facilitate the creation of the mold. U3 is provided. The prism groups U1 and U2 can be composed of three or more sets, but are preferably symmetrical when viewed as a whole. As shown in FIG. 34, the light control member 4 whose incident surface has the shape shown in FIG. 33 is preferable in that the oblique incident light 12 from the light source (not shown) is diffused and emitted in a wider direction, and the lamp image is erased.

  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.

  In another configuration example of the light control member 4 according to the total light transmittance adjusting means, at least one of the incident surface and the exit surface of the light control member 4 is made of a material having a lower refractive index than the base material of the light control member 4. At least one thin layer having a thickness of 1 μm or less is provided. If comprised in this way, the total light transmittance at the time of perpendicular | vertical incidence with respect to the light control member 4 will become small by the interference effect | action of light, and the total light transmittance at the time of diagonal incidence will become high.

  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.

A first embodiment of the present invention is shown in FIG. In this example,
c = 8.33
k = −0.44
A female die having a cylindrical groove represented by the following formula was produced by cutting. Here, x represents the distance from the center of the unit shape. The case of k represents an elliptical shape. The width of one cylindrical shape was 0.3 mm. That is, −0.15 ≦ x ≦ 0.15 (mm).

  Next, a convex shape was formed from the mold on the polycarbonate film surface with an ultraviolet curable resin. 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. As the linear light source, cold cathode tubes were arranged at intervals of 30 mm, and the surface having the convex portion of the acrylic plate was placed at a position 18 mm from the cold cathode tube so as to be an emission surface. In this case, α = 40 °. A reflective sheet was provided on the side of the cold cathode tube facing the acrylic plate.

  As a result of observation in this state, it was possible to obtain an illumination device in which the lamp image was eliminated and the brightness of the exit surface was uniform. The incident light of the incident light control member used here has a transmittance of 66% when light is incident at an angle α = 40 ° with the normal direction of the incident surface, and the light is irradiated in the normal direction. The transmittance in this case was 52%, and the ratio of these transmittances was 1.27.

  The second embodiment of the present invention will be described in detail below. First, a female die having a columnar groove with angles θ = 50 °, P1 = 260 μm, and A1 = 182 μm formed by the extended lines of the two substantially straight lines 10 in FIG. 7 was manufactured by cutting.

  Next, using this female mold, a convex prism was formed on the polycarbonate film surface with an ultraviolet curable resin. 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 75%, and the normal direction. When irradiated with light, the total light transmittance R2 of the light was 51%, and the ratio R1 / R2 of these total light transmittances was 1.47.

  A third embodiment of the present invention is shown in FIG. In this embodiment, the angle between two straight lines θa = 40 °, P1a = 0.113 mm, S1 where A1a = 0.045 mm, and θb = 70 °, P1b = 0.113 mm, A1b = 0.045 mm. A female die having a cylindrical groove of S2 was produced by cutting. Next, a convex shape was formed on the polycarbonate film surface with an ultraviolet curable resin from the mold. 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. Cold cathode tubes were arranged as linear light sources at intervals of 33 mm, and the surface having the convex portions of the acrylic plate was placed at the position 16.5 mm away from the cold cathode tube. In this case, α = 45 °. A reflective sheet was provided on the side of the cold cathode tube facing the acrylic plate.

  As a result of observation in this state, it was possible to obtain an illumination device in which the lamp image was eliminated and the brightness of the exit surface was uniform. When light is incident on the incident surface of the incident light control member used here at an angle α = 45 ° with the normal direction of the incident surface, the transmittance is 76%, and the light is irradiated in the normal direction. The transmittance in this case was 52%, and the ratio of these transmittances was 1.46.

By having two types of cylindrical shapes in this way, as shown in FIG. 25, the vertically incident light 13 to the light control member can obtain different outgoing light characteristics L1 and L2 in the shapes S1 and S2. Further, as shown in FIG. 26, the oblique incident light 12 can also obtain L3 and L4 corresponding to S1 and S2 as the outgoing light characteristics. Thus, since the light emission direction can be dispersed, in-plane luminance unevenness can be further reduced. That is, since the degree of freedom of shape setting is increased with respect to the emission light control in one kind of cylindrical shape, it becomes easier to control the characteristics of the emission light.
It is clear that the cylindrical shape is not limited to two types, and there are no problems with three or more types.

  Next, a fourth embodiment of the present invention will be described in detail. First, a prism surface having a prism portion having an apex angle of 40 ° and a prism portion having a flat portion arranged at equal intervals at a ratio of 30% of the entire surface between each prism portion and a prism shape having an apex angle of 140 ° were formed. In order to form each uneven surface, a mold having a plurality of grooves corresponding to each prism shape was produced by cutting. In this case, the plurality of grooves were provided at intervals of 50 μm. Further, the surface shape of the mold produced by the cutting process was a symmetric shape corresponding to the prism shape, and the depth of the groove portion of the symmetric shape was also constant in the plane.

  Then, a polycarbonate film was set in the mold and an ultraviolet curable resin was injected to form a shape portion corresponding to each prism shape on one side of the polycarbonate film. Furthermore, the surface of each polycarbonate film on which the prism-shaped portion was not formed was bonded to a transparent acrylic plate having a thickness of 2 mm. In this case, convex portions are formed on both the front and back surfaces by bonding so that the ridge line of the incident side prism portion having an apex angle of 40 degrees and the ridge line of the output side uneven surface having an apex angle of 140 degrees are parallel to each other. A light control member was obtained.

  Next, a plurality of cold cathode tubes as linear light sources were arranged at intervals of 33 mm, and the light control member was arranged at a position 16.5 mm from the cold cathode tubes. In this case, the prism portion of the light control member was installed in parallel with the longitudinal direction of the cold cathode tube, and the uneven surface was on the light exit surface side of the light control member. In this case, the angle α is set to 45 °. A reflective sheet was provided on the side 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 = 45 ° with respect to the normal direction of the incident surface, the total light transmittance R1 of the light is 79%, and the normal direction When irradiated with light, the total light transmittance R2 of the light was 66%, and the ratio R1 / R2 of these total light transmittances was 1.19.

  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. 17A, 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, which is a linear light source 15, 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 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, and the luminance was low between the adjacent cold cathode fluorescent tubes (obliquely upper regions). As a result, there is a large difference in luminance between the region directly above and the obliquely upper region of the cold cathode tube, so that the quality such as luminance uniformity on the image display surface is greatly reduced.

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

  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 the 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. 17C 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, and a plurality of cold cathode tubes are provided. Since a phenomenon in which the luminance decreases during the period is observed, it is difficult to obtain the same luminance as the luminance by the light control member 4.

  A fifth embodiment of the present invention is shown in FIG. In this example, the refractive indexes are 1.48, 1.62, and 1.38 on the entrance and exit surfaces of a 2 mm thick substrate made of a methyl methacrylate-styrene copolymer having a refractive index of 1.54, respectively. Transparent control thin films N1, N2, and N3 were laminated with thicknesses of 0.1 μm, 0.078 μm, and 0.179 μm, respectively, to obtain a light control member 4. Reference numeral 26 denotes reflected light.

  A plurality of cold cathode tubes were used as a linear light source for irradiating the light control member 4 with light. In this case, the plurality of cold cathode tubes were arranged at intervals of 33 mm, and the light control member 4 was installed at a position of 16.5 mm from the cold cathode tubes. In this case, the angle α is set to 45 °. A reflective sheet was provided on the side of the cold cathode tube facing the acrylic plate.

  In this state, the light control member 4 was irradiated with light by turning on the cold cathode tube, and the light control member 4 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 = 45 ° with respect to the normal direction of the incident surface, the total light transmittance R1 of the light is 90%, and the normal direction When irradiated with light, the total light transmittance R2 of the light was 85%, and the ratio R1 / R2 of these total light transmittances was 1.09.

  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. FIG. 19 shows a configuration example when a point light source 21 is installed between the reflector 2 and the light control member 4. Even when the point light source 21 is used, the same effect as when the linear light source is used can be expected.

  FIG. 20 shows another configuration example that can be used in the present invention. In this configuration, the diffusion sheet 22 is superposed on the exit surface of the light control member 4. In this case, since the luminance angle distribution of the emitted light can be made more uniform in the emission surface by the diffusion sheet 22, a higher-quality illumination device can be obtained.

  FIG. 21 shows another configuration example that can be used in the present invention. In this configuration, the polarization separation film 23 is superimposed on the diffusion sheet 22. When the polarized light separating film 23 separates orthogonally polarized light, the liquid crystal panel is placed on the light emitting surface, and the transmission polarization axis of the polarizing separation film 23 is matched with the transmission axis of the polarizing film on the liquid crystal panel incident surface, 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 polarizing film of a liquid crystal panel entrance plane.

  Next, regarding a schematic configuration example of a liquid crystal display device (image display device), by placing a liquid crystal panel on the light control member 4, a liquid crystal display device having uniform brightness within the panel display surface is obtained. 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. 22 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.

<Comparative example>
Patent Document 6 proposes to obtain a uniform surface light source element by separating a light source into two images.
In order to compare the means proposed in Patent Document 6 and the light control member of the present invention, a prism having an apex angle of 90 ° is emitted as means for separating the light source shown in Patent Document 6 into two images. The sheet formed on the surface was arranged so that the prism was parallel to the line light source. As shown in FIG. 32, this sheet emits incident light from an oblique direction in the front direction. However, as shown in FIG. 31, the light incident perpendicularly to the sheet is significantly reduced in the light emitted in the front direction due to total reflection. As a result of observing from the front direction, the luminance was greatly reduced in the portion directly above the light source, and the in-plane luminance unevenness was increased. Further, the transmittance when light is incident on the incident surface of the sheet at an angle α = 45 ° with the normal direction of the incident surface is 90%, and the transmittance when light is irradiated in the normal direction is 5%. %Met. That is, the transmittance ratio is 18. Thus, when the transmittance ratio is increased, in-plane luminance unevenness cannot be adjusted due to a decrease in luminance directly above the light source.

  31 and 32 show the principle of light control of the sheet. As shown in FIG. 31, since all the light incident on the incident surface of the light control member from the normal direction is totally reflected and returns to the incident side, the total light transmittance in this region is 0 in principle, and the actually measured value is also Very low at 5%. On the other hand, as shown in FIG. 32, light incident from an oblique direction is refracted by the convex portion and travels to the vicinity of the front surface, and thus exhibits a high total light transmittance. In the implemented configuration, it was 90%. That is, compared with the present invention, the ratio of the total light transmittance of light incident from an oblique direction is very high.

  In order to compare in detail the difference in luminance uniformity caused by the difference in the ratio of the total light transmittance between the light incident from the oblique direction and the light incident from the normal direction, as shown in FIG. The light control member of the first example shown in FIG. 27 or the prism sheet of the comparative example shown in FIG. 27 was provided at a position of 55 mm, and an image generated in a state where the cold cathodes were lit was taken with a camera.

  As a result, in the light control member of the first example, as shown in the photograph of FIG. 36, it was confirmed that the light from the light source was emitted from a wide range. Therefore, due to the in-plane luminance uniformity, While an excellent surface light source can be obtained, in the prism sheet of the comparative example proposed in Patent Document 6, the light source is clearly divided into two images as shown in the photograph of FIG. It can be expected that a high-brightness region is formed at each position, resulting in uneven brightness. Here, the photograph in FIG. 38 is a photograph taken directly from the light source.

  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 one.

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 another example of the cross-sectional shape of the light control member which can be used for this invention. It is a schematic block diagram explaining the locus | trajectory of the light ray when light injects into the light control member which concerns on this invention diagonally. It is explanatory drawing which shows another example of the cross-sectional shape of the light control member which can be used for this invention. It is a schematic block diagram explaining the locus | trajectory of the light ray when light injects into the light control member which has the flat part which concerns on this invention diagonally. It is a schematic block diagram explaining the relationship between the optical path and angle of the light which injected into the prism provided in the incident surface which concerns on 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 another Example of this invention which formed the thin film in the light-control member surface based on this invention. 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 explanatory drawing which shows the 3rd Example of the light control member which can be used for this invention. It is a schematic block diagram explaining the locus | trajectory of the light ray which injected into the light control member which has the some cylindrical convex part in connection with this invention perpendicularly | vertically. It is a schematic block diagram explaining the locus | trajectory of the light ray which injected into the light control member which has the some cylindrical convex part in connection with this invention diagonally. It is explanatory drawing which shows the convex part cross-sectional shape of a 1st Example of the light control member which can be used for this invention. In the convex portion of the first embodiment of the light control member that can be used in the present invention, a contour line when it is crossed along a predetermined direction including the apex, perpendicular to the exit surface, and on the contour line It is a figure explaining the relationship of the inclination of each point. It is a schematic block diagram explaining the locus | trajectory of the light ray injected perpendicular | vertical in the 1st Example of the light control member which can be used for this invention. It is a schematic block diagram explaining the locus | trajectory of the light ray which injected diagonally in the 1st Example of the light control member which can be used for this invention. It is a schematic block diagram explaining the locus | trajectory of the light ray which injected from the perpendicular | vertical direction of the sheet | seat in which the prism whose apex angle is 90 degrees was formed in the output surface. It is a schematic block diagram explaining the locus | trajectory of the light ray which injected from the diagonal direction of the sheet | seat in which the prism whose apex angle is 90 degrees was formed in the output surface. It is explanatory drawing which shows another example of the cross-sectional shape of the light control member which can be used for this invention. It is a schematic block diagram explaining the locus | trajectory of the light ray which injected into the light control member which provided the asymmetric prism in the incident surface which concerns on this invention in the diagonal direction. It is explanatory drawing which shows the installation state of the camera for comparing the light control member which concerns on this invention, and the means proposed by patent document 6. FIG. It is the photograph which compares the light control member which concerns on this invention, and the means proposed by patent document 6, It is a photograph of the light control member of 1st Example. It is the photograph which compares the light control member which concerns on this invention, and the means proposed by patent document 6, It is a photograph of the prism sheet proposed by patent document 6. FIG. It is the photograph which compared the light control member concerning the present invention with the means proposed by patent documents 6, and is the photograph which photoed the light source directly.

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 Linear part 11 Curved part 12 Oblique incident light 13 Vertical incident light 14 Valley part 15 Linear light source 16 Prism 17 Emitting surface unevenness 18 Flat portion 19 Incident surface 20 Fine particle-containing light diffusion plate 20a Opening portion 21 Point-like light source 22 Diffusion sheet 23 Polarization separation film 24 Liquid crystal panel 25 Progressive light 26 Reflected light 100 Incident light

Claims (10)

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 reflection plate, the light source, and the light control member are arranged in this order from the incident side to the light emission side, the light control member includes an incident surface that mainly receives light, and an emission surface that mainly emits light. When the distance between the nearest light source Y is D and the distance between the light source X and the light control member is H, the normal direction of the incident surface at any point on the incident surface The total light transmittance of light incident at an angle of α = Tan ⁻¹ {(D / 2) / H} is 50% or more, and the total light transmittance is a point on the incident surface. 1.05 times to 3 times the total light transmittance of light when light is incident from the normal direction to Lighting apparatus according to claim and.   The lighting device according to claim 1, wherein a plurality of convex portions are formed on an emission surface of the light control member.   The light control of U with respect to the projected area of the unit convex portion on the light control member, where U is a range where the slope slope of the convex portion formed on the light exit surface of the light control member is 50 ° to 70 °. The lighting device according to claim 1, wherein a ratio of a projected area onto the member is in a range of 0.2 to 0.8.   The light control member has an acute angle θ at which an outline intersects an extension line of a contour line in a light emission part of a cross section along at least a predetermined direction that is orthogonal to the emission surface and includes the top of the convex part. 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.   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 illumination device according to any one of claims 1 to 4.   The light control member includes a plurality of convex portions formed on the incident surface, includes a top portion of the convex portion, and a contour line sectioned from a direction orthogonal to the incident surface sandwiches the top portion of the convex portion. The illumination device according to claim 1, wherein the illumination device includes two substantially straight lines, and deflects light emitted from the light source to the light control member at a plurality of angles on the incident surface. .   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. 7. 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.   At least one layer having a thickness of 1 μm or less made of a material having a refractive index lower than that of the base material of the light control member is formed on at least one of the incident surface and the emission surface of the light control member. The lighting device according to claim 1.   The lighting device according to claim 1, wherein the light source is a point light source.   An image display device comprising a transmissive display element on the illumination device according to claim 1.