JP4498987B2 - Lighting device and display device - Google Patents

Description

  The present invention relates to a lighting device and a display device using the same.

  In recent years, in many fields such as the display field and the optical communication field, it has been required to align light rays that have spread to a certain extent in a certain direction. In order to meet such demands, in many lighting devices, an optical sheet for controlling the light directivity is provided on the exit port of the light source housing. This optical sheet has optical transparency and aligns incident light in a predetermined direction. As a typical example of an optical sheet having light transmittance for controlling such light directivity, there is a prism sheet (see, for example, Patent Document 1).

  The prism sheet is typically a sheet in which prisms having a triangular prism shape or a kamaboko shape are arranged in parallel, and the traveling direction of the light beam is controlled by the prism effect or the lens effect. However, regardless of the shape of the prism of the prism sheet, there is a limit to the control of the light directivity as long as the light source light enters the prism sheet from all directions. For example, when the illuminating device is used as a backlight of a liquid crystal device, the limit is that the light is condensed within an angle of about ± 40 ° from the vertical direction of the liquid crystal surface, and the front luminance of the liquid crystal surface is improved more than twice. It was difficult.

Patent Document 2 discloses an illumination device using another example of an optical sheet. In the illumination device disclosed in Patent Document 2, a lenticular lens sheet is used, and a reflector is provided on the back surface of the lenticular lens sheet. Such a lenticular lens sheet is attached to a housing (light box) in which a light source is stored, and the inner surface of the housing is configured to have a high reflectance. On the back side of the lenticular lens sheet, an opening (slot) is provided in the reflector, and light from the light source is emitted to the outside from this opening.
However, in the illumination device disclosed in Patent Document 2, specific numerical values are not disclosed for the reflectance on the inner surface of the light box and the reflectance of the reflector. Moreover, it is not disclosed how the characteristics of the lighting device change due to the reflection characteristics inside the light box.
JP 2004-281270 A JP-A-2-214287

As described above, the conventional illumination device has a problem that the light directivity is incident on the optical sheet from all directions regardless of the shape of the lens of the optical sheet, so that the effect of improving the light directivity is limited.
The present invention has been made to solve such problems, and an object thereof is to provide an illumination device and a display device with higher light directivity and higher light utilization efficiency.

An illumination device according to the present invention includes a light source that emits light, a housing that houses the light source and is provided with an emission port that emits light from the light source, and an optical sheet disposed in the emission port. An inner surface of the housing has a reflection effect of reflecting light emitted from the light source, and the optical sheet is disposed on the light emission side and is incident from the light source. A lens structure that aligns the direction of the emitted light, a reflector that is disposed on the light incident side, reflects 80% or more of visible light, and is opened in the reflector, and receives light incident from the light source. And a light-transmitting opening that transmits light.
In such a configuration, since the amount of light absorbed from the light source in the housing can be reduced, the light utilization efficiency can be increased. Furthermore, incident light can be aligned in a predetermined direction by the lens structure. Therefore, it is possible to realize a lighting device that aligns light in this predetermined direction and has higher directivity and higher light utilization efficiency.

  Further, the lens structure aligns the incident light in a direction substantially perpendicular to the sheet surface of the optical sheet. As a result, the directivity of light incident on the optical sheet can be increased in a direction substantially perpendicular to the sheet surface.

  Furthermore, the inner surface of the housing has a reflective effect of reflecting 80% or more of visible light. Thereby, it can prevent reliably that the light from a light source is absorbed inside a housing.

  Further, the reflector has a plurality of reflecting portions spaced apart from each other with the light transmitting opening portion interposed therebetween.

  Furthermore, the lens structure has a plurality of lens portions, and the light transmission opening is formed near the optical axis of the lens structure. Thereby, the directivity of the light incident on the optical sheet can be easily adjusted so as to be in a direction substantially perpendicular to the sheet surface.

  The lens structure includes a plurality of non-lens portions that are disposed between the plurality of lens portions and have a lens effect smaller than the lens effect of the lens portions.

  Preferably, the lens structure has a repetitive structure in which the plurality of lens portions are repeatedly arranged, and a distance P between the plurality of lens portions and an end of the lens portion from an end of the light transmission opening. The distance D to the portion satisfies the relationship of P / D> 2.4.

  Furthermore, the non-lens portion is a flat surface parallel to the sheet surface of the optical sheet, and the plurality of lens portions are connected via the plurality of flat surfaces. Thereby, since light can be incident only on the predetermined lens portion, the light directivity can be further improved.

  Preferably, the lens portion may be a long lenticular lens, and the light transmission opening is formed between the plurality of reflection portions in a stripe shape extending in the longitudinal direction of the lenticular lens. The

  Further, for example, the lens portion can be a microlens array, and the light transmission openings are formed in the reflector in a scattered state.

  The lens structure and the light transmission opening may be adjusted so that the maximum luminance value of the main peak in the viewing angle dependence of the luminance of the emitted light is at least twice the maximum luminance value of the sub peak. preferable.

On the other hand, an illumination device according to the present invention includes a light source that emits light, a housing that houses the light source and is provided with an emission port that emits light from the light source, and an optical sheet disposed in the emission port. The inner surface of the housing has a reflection effect of reflecting the light emitted from the light source, and the optical sheet is disposed on the light emission side, and is from the light source. A plurality of lens portions that align the emission direction of incident light, a plurality of non-lens portions that are disposed between the plurality of lens portions and have a lens effect smaller than the lens effect of the lens portions, and the light The reflector includes a reflector that is disposed on the incident side and reflects light emitted from the light source, and a light transmission opening that is opened in the reflector and transmits light incident from the light source.
In such a configuration, since the amount of light absorbed from the light source in the housing can be reduced, the light utilization efficiency can be increased. Furthermore, incident light can be aligned in a predetermined direction by the lens structure, and at the same time, light can be incident only on the predetermined lens part by the non-lens part. Therefore, it is possible to realize a lighting device that aligns light in this predetermined direction and has higher directivity and higher light utilization efficiency.

  The display device according to the present invention includes such an illumination device. In such a configuration, since a lighting device with higher light directivity is used, a display device with higher directivity can be realized.

  Preferably, the display device according to the present invention is a liquid crystal display device in which the illumination device is used as a backlight. Particularly in this case, since the viewing angle control can be reliably performed, a display device with higher directivity can be realized.

  According to the present invention, it is possible to provide an illumination device and a display device with higher light directivity and higher light utilization efficiency.

The illumination device according to the present invention has a function of aligning incident light rays in an arbitrary direction by an optical structure. Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.
Embodiment 1 of the Invention
First, the whole structure of the illuminating device concerning this invention is demonstrated using FIG. Fig.1 (a) is a schematic diagram which shows an example of the illuminating device which concerns on this invention. As shown in FIG. 1A, the lighting device 1 according to the present invention includes a light source 11, a housing 12, and an optical sheet 13.
The light source 11 is a device that supplies light from the lighting device 1 and is, for example, a fluorescent tube, an LED (Light Emitting Device), or the like.

  The housing 12 is a housing that houses the light source 11, and has a light emission port 120 for emitting light emitted from the light source 11 to the outside. The inner surface of the housing 12 is composed of a reflecting surface that diffusely reflects light from the light source 11 and is covered with a reflecting member such as titanium oxide. In this case, the entire inner surface of the housing 12 has substantially reflective characteristics, and preferably about 90% or more thereof is covered with the reflective member. Further, the inner surface of the housing 12 can be made a reflective surface by mixing a material having reflection characteristics into the inner surface of the housing 12. As the reflecting member or the mixed material as described above, a high reflectance material that reflects visible light with an average reflectance of 80% can be used.

  The optical sheet 13 is provided at the light exit 120 of the housing 12. Specifically, the optical sheet 13 is fitted in the light exit port 120 and closes the light exit port 120. Thus, the light source sheet 13 constitutes a housing part that houses the light source 11 together with the housing 12, and the housing part covers the entire light source 11. The optical sheet 13 preferably seals the inside of the housing 12 so that the light from the light source 11 does not leak outside the housing 12. Thereby, the utilization efficiency of the light supplied from the light source 11 can be increased.

Then, the optical sheet 13 of the illuminating device 1 which concerns on this invention is demonstrated in detail using FIG. FIG. 1B is a schematic side view showing an example of the optical sheet 13. As shown in FIG. 1B, the optical sheet 13 includes a reflector 131, an opening 132, and a lens structure 133.
The reflector 131 is composed of a reflecting member having a reflecting effect. For example, a reflecting member that reflects visible light with a high reflectance of 80% or more on average can be used as the reflecting member. The reflector 131 is provided on the light incident side (light incident side) of the optical sheet 13. That is, the reflector 131 is disposed on the light source 11 side of the optical sheet 13, that is, on the inside of the housing 12. In other words, the reflector 131 is fixed to the back surface (surface on the light incident surface side) of the optical sheet 13.

The opening 132 is a light transmission opening through which the light of the optical sheet 13 is transmitted, and is a portion opened by the reflector 131 disposed on the back surface of the optical sheet 13. Therefore, the back surface of the optical sheet 13 is exposed from the opening 132. Except for the opening 132, the reflector 131 reflects incident light. When the opening 132 separates the reflector 131 into a plurality, the reflector 131 includes a plurality of reflectors 134.
The lens structure 133 is an example of a structure (optical structure) having optical characteristics, and is a structure having a lens effect in particular. The lens structure 133 includes a plurality of lens parts 135, and the plurality of lens parts 135 are connected in a state of being in direct contact with each other. As shown in FIG. 1B, the lens portion 135 can be a long lenticular lens having a substantially cross-sectional shape. These lens parts 135, which are lenticular lenses, are arranged in the short direction (left and right direction on the paper surface), and are connected so that the valleys between the lens parts 135 are sharply cut.

  The lens structure 133 is provided on the side from which the light of the optical sheet 13 is emitted (light emission side), and changes the direction of incident light. More specifically, the lens structure 133 collimates incident light into parallel light, that is, the lens structure 133 has the direction of incident light perpendicular to the main surface (optical sheet surface) of the optical sheet 13. Direction, that is, the normal direction of the optical sheet surface. Therefore, the opening 132 into which the light from the light source 11 is incident is disposed in the vicinity of the optical axis of each lens portion 135 of the lens structure 133.

  When the lens unit 135 is a long lenticular lens, the optical axis thereof extends in the longitudinal direction of the lens unit 135. Accordingly, the opening 132 in this case has a stripe shape, and the reflector 131 is separated in the lateral direction of the lenticular lens to constitute a plurality of reflecting portions 134. In other words, the gaps between the plurality of reflecting portions 134 arranged in a separated state function as the openings 132.

Next, the operation in which the lighting device 1 according to the present invention emits light will be described. This will be described with reference to FIG. 1 as appropriate.
The light emitted from the light source 11 enters the lens structure 133 through the opening 132 of the optical sheet 13. On the other hand, the light irradiated to the part other than the opening 132 is reflected between the inner surface of the housing 12 constituting the reflecting surface or the reflector 131 of the optical sheet 13. This reflection is repeated several times, after which this reflected light reaches the opening 132. The light that reaches the opening 132 enters the lens structure 133 through the opening 132. In this way, the optical axis of the incident light is aligned in a certain direction (a direction perpendicular to the optical sheet surface) according to the optical characteristics of the lens structure 133.

  As described above, in the illuminating device 1 according to the present invention, the portion other than the opening 132 of the optical sheet 13 in the housing 12 has reflection characteristics. Therefore, the light supplied from the light source 11 is diffusely reflected inside the housing 12 and emitted from the opening 132 of the optical sheet 13. In particular, the inner surface of the housing 12 substantially constitutes a reflecting surface, and the reflector 131 of the optical sheet 13 reflects visible light by 80% or more. Therefore, since the amount of light absorption inside the housing 12 can be reduced, it is possible to suppress the loss of emitted light. Therefore, since the emitted light flux increases, the utilization efficiency of the light supplied from the light source 11 can be improved. Such a remarkable effect is not disclosed in the above Patent Document 2 (Japanese Patent Laid-Open No. 2-2214287), and is not even suggested.

  Furthermore, since the light emitted from the lens structure 133 becomes parallel light, the luminance in the direction perpendicular to the optical sheet surface can be increased. Thereby, the directivity of light in the direction perpendicular to the optical sheet surface can be improved. Such a highly directional lighting device 1 is preferably used for a backlight of a mobile phone terminal or an ATM display. When used in the backlight of the display in this way, it is possible to prevent the display from being looked into from the surroundings, and it is possible to improve the confidentiality of information.

  In the present embodiment, only one optical sheet 13 is used for the light exit port 120, but the present invention is not limited to this. For example, a plurality of other optical sheets can be used, such as providing a commercially available diffusion plate on the light incident side of the optical sheet 13 or providing a scattering sheet on the light emitting side. Further, the inner surface of the housing 12 and the surface of the optical sheet 13 mean an optical surface, and includes a case where a transparent protective film or the like is provided on the surface of the reflecting member arranged on these surfaces.

Embodiment 2 of the Invention
The arrangement relationship between the reflector and the lens structure in the optical sheet according to the second embodiment is different from the arrangement relationship between the reflector 131 and the lens structure 133 in the optical sheet 13 according to the first embodiment. As will be described later, the configuration of the optical sheet in the second embodiment is a configuration for enhancing directivity as compared with the optical sheet 13 in the first embodiment.

  First, the configuration of the optical sheet in the present embodiment will be specifically described with reference to FIG. Another example of the optical sheet according to the present invention is shown in the schematic side view of FIG. In FIG. 2A, the distance (lens pitch) between the lens portions 235 of the optical sheet 23 in Embodiment 2 is indicated by P1. In FIG. 2A, the distance from the lens end of the lens unit 235 to the end of the reflection unit 234 of the reflector 231, that is, the boundary between the reflection unit 234 and the opening 232 is indicated by D 1. Yes. Hereinafter, the distance D1 from the end portion of the lens portion 235 to the end portion of the reflecting portion 234 is abbreviated as an end portion distance.

The optical sheet 13 in Embodiment 1 is shown in the schematic side view of FIG. The optical sheet 13 shown in FIG. 2B is the same as the optical sheet 13 shown in FIG. In FIG. 2B, the lens pitch between the plurality of lens portions 135 is indicated by P0, and the distance between the end portions is indicated by D0.
As shown in FIGS. 2A and 2B, the lens portions 235 of the optical sheet 23 of the second embodiment are arranged with a lens interval wider than the lens intervals of the optical sheet 13 of the first embodiment. Briefly, the lens pitch P1 in the optical sheet 23 is larger than the lens pitch P0 in the optical sheet 13 of the first embodiment. Accordingly, the end-to-end distance D1 of the optical sheet 23 is larger than the end-to-end distance D0 of the optical sheet 13. In contrast, the opening widths of the openings 132 and 232 of the optical sheets 13 and 23, that is, the distance between the reflecting portions 134 and 234 that are separated from each other are the same.

Subsequently, directivity in the optical sheet 13 in the first embodiment will be described. Here, it demonstrates, referring suitably FIG. 7 which shows the luminance distribution in the optical sheet 13 of Embodiment 1. FIG. In FIG. 7, graph A is a measurement result in Example 1 described later.
In the graph A shown in FIG. 7, sub-peaks A11 and A12 are generated separately from the main peak A10 in the direction perpendicular to the optical sheet surface. This is due to the following reason. Specifically, in the optical sheet 13 of the first embodiment, each opening 132 is provided near the optical axis of each lens unit 135. For this reason, the light incident from the opening 132 does not enter only the predetermined lens part 135 but also enters the adjacent lens part 135. Therefore, the light rays are aligned even at an angle different from the direction perpendicular to the optical sheet surface, and these light rays appear as sub-peaks A11 and A12.

In FIG. 7, a graph B shows a measurement result when the opening 132 of the optical sheet 13 is displaced from the optical axis of the lens unit 135.
As shown in the graph B of FIG. 7, even when the opening 132 is separated from the optical axis, the same phenomenon as when the opening 132 is on the optical axis occurs. Therefore, the light rays are aligned at a plurality of angles, and sub-peaks B11 and B12 are generated in addition to the main peak B10.
The effect of aligning rays at a plurality of angles is particularly great with a lens having a structure that is long in one direction, such as a lenticular lens. In a structure in which lens portions are two-dimensionally separated, such as a microlens array, subpeaks may occur depending on conditions, but it is relatively less likely to occur than a lens having a structure that is long in one direction.

  The occurrence of sub-peaks does not pose a problem in applications where the brightness at the target angle may be strong and there may be places where the brightness is strong at other angles. However, the occurrence of sub-peaks becomes a problem in applications where it is necessary to prevent light rays from being aligned at angles other than a desired angle, such as a light source of a liquid crystal display that requires a viewing angle restriction.

In the optical sheet 13 of the first embodiment, the problem of directivity that a sub-peak occurs is solved by the second embodiment as follows.
As shown in FIG. 2A, the end-to-end distance D1 in the optical sheet 23 is made larger than the end-to-end distance D0 in the optical sheet 13. Specifically, the lens pitch P1 is set larger than the lens pitch P0 in a state where the opening width of the opening 232 is the same as the opening width of the opening 132. As a result, the interval between the lens portions 235 is widened, so that light incident on the predetermined lens portion 235 from the predetermined opening 232 can be prevented from entering the adjacent lens portion 235. Therefore, by using the optical sheet 23 of the second embodiment, it is possible to align the light rays only in a predetermined angle, for example, a direction perpendicular to the optical sheet surface, so that it corresponds to an application that requires a viewing angle limitation. be able to.

Embodiment 3 of the Invention
In the third embodiment of the invention, another example of the optical sheet in which the distance between the lenses is widened as in the second embodiment will be described. As will be described later, the configuration of the optical sheet in the third embodiment is a configuration for increasing the directivity more reliably than the optical sheet 23 of the second embodiment.
First, the configuration of the optical sheet in the present embodiment will be specifically described with reference to FIG. Another example of the optical sheet according to the present invention is shown in the schematic side view of FIG.

As shown in FIG. 3, the lens structure 333 of the optical sheet 33 in Embodiment 3 includes a plurality of flat portions 336 in addition to the plurality of lens portions 335. Unlike the lens portion 335, the flat portion 336 is an example of a non-lens portion that has substantially no lens effect. Since the flat portion 336 has no lens effect, the incident light is not collected, and the incident light does not generate a sub-peak. The flat portion 336 may have any planar structure as long as it does not have a condensing function, but is preferably a plane that satisfies the total reflection condition. Accordingly, the flat portion 336 has a function of preventing incident light from being emitted. The plurality of flat portions 336 are disposed between the lens portions 335 and connect the plurality of lens portions 335.
Here, the non-lens portion includes not only a portion having no lens effect but also a portion having a small lens effect, and includes a portion that emits light only to a negligible level. Accordingly, the flat portion 336 may be a surface having a small lens effect, a flat surface having no lens effect, or a surface close to a flat surface, and includes a surface that can be generally considered to be a flat surface even if there is some lens effect.

In FIG. 3, the lens pitch between the plurality of lens portions 335 in the optical sheet 33 is indicated by P2, and the end-to-end distance is indicated by D2.
As shown in FIG. 3, the lens pitch P2 in the optical sheet 33 of the third embodiment is larger than the lens pitch P0 in the optical sheet 13 of the first embodiment shown in FIG. Accordingly, the end-to-end distance D1 of the optical sheet 23 is larger than the end-to-end distance D0 of the optical sheet 13. On the other hand, the opening widths of the openings 132 and 332 of the optical sheets 13 and 33, that is, the distances between the reflecting portions 134 and 334 that are separated from each other are the same.

  Thus, in the optical sheet 33 according to the third embodiment, a flat portion 336 that does not emit light is provided between the lens portions 335. Therefore, the light incident from the predetermined opening 332 reaches the flat portion 336 and is reflected or transmitted, but does not enter the adjacent lens portion 335. Therefore, the optical sheet 33 according to the third embodiment can more reliably prevent the sub-peak from occurring.

Furthermore, the optical sheet 33 according to the third embodiment can cope with a minute lens while suppressing the occurrence of sub-peaks.
Specifically, as in the optical sheet 23 of the second embodiment, when the lens shape is larger than a certain extent, the occurrence of sub-peaks can be eliminated by widening the lens pitch P1 and increasing the interval between the reflecting portions 234. However, when the lens shape is small, it is difficult from the viewpoint of manufacturing to separate the end-to-end distance D1.
Specifically, as shown in FIG. 2, when the lens pitch P1 is increased with respect to the end-to-end distance D1 in a state where the lens portions 235 are in contact with each other, the lens portions 235 in the portion where the lens portions 235 are in contact with each other. The angle formed by is cut into an acute angle. When such a lens portion 235 is manufactured by machining, an acute angle portion sharpened to a certain extent is easily deformed. Therefore, when the lens shape is small, it becomes difficult to manufacture. The same applies to the case of using a laser beam or the like, and it is difficult to produce an acute angle portion.

  Thus, in the optical sheet 23 in Embodiment 2, it cannot respond to the case where the size of the lens is reduced. On the other hand, in the optical sheet 33 of the third embodiment, the lens pitch P2 is increased with respect to the end portion distance D2, and at the same time, the portion where the flat portion 336 and the lens portion 335 are in contact with each other does not become an acute angle. Then, widen the angle of the contact part. This makes it possible to manufacture a lens structure 333 having a minute lens. Therefore, the optical sheet 33 according to the third embodiment can suppress the occurrence of sub-peaks and can easily cope with the minute lens structure.

Embodiment 4 of the Invention
Although the lens portions 135, 235, and 335 in Embodiments 1 to 3 are lenticular lenses, the present invention can also be applied to microlenses. In Embodiment 4 of the invention, a case where the lens portion 135 of the optical sheet 13 in Embodiment 1 is a microlens will be described.
FIG. 4 shows a configuration example of the optical sheet 43 according to the fourth embodiment. 4A is a schematic perspective view thereof, FIG. 4B is a schematic top view thereof, and FIG. 4C is a schematic side view thereof. As shown in FIG. 4, the lens structure 433 of the optical sheet 43 includes a plurality of lens portions 435 arranged in a matrix. That is, the optical sheet 43 is a microlens array sheet in which a plurality of lens portions 435 are configured from a microlens array.

FIG. 5 shows an optical sheet 43 that is a microlens array sheet. FIG. 5A is a schematic top view thereof, FIG. 5B is a schematic side view thereof, and FIG. It is a cross-sectional schematic diagram of A 'cross section. As shown in FIG. 5, the reflector 431 of the optical sheet 43 is formed integrally with the back surface of the optical sheet 43. A plurality of openings 432 of the optical sheet 43 are formed in the vicinity of the optical axis of the lens portion 435 that is a microlens. Therefore, the plurality of openings 432 are scattered in a matrix. Therefore, in the first embodiment, the reflector 131 is composed of a plurality of lens portions 135, whereas the reflector 433 in the present embodiment 4 is integrally connected. In other words, the reflector 433 of the fourth embodiment is composed of a single reflecting portion 435.
5C, the lens pitch between the plurality of lens portions 435 in the optical sheet 43 is indicated by P3, and the distance between the end portions is indicated by D3.

In this manner, the opening 432 and the reflector 434 can be formed on the back surface of the optical sheet 43 that is a microlens array sheet. Even in this case, the same effect as in the first embodiment can be obtained. Furthermore, not only Embodiment 1 but Embodiments 2 and 3 can be applied to a microlens array sheet.
Specifically, the lens pitch P3 of the matrix-shaped microlens (lens portion 435) can be increased, or a non-lens portion can be formed between the microlenses. Even in this case, the same effects as those of the second and third embodiments can be obtained. In particular, by forming a non-lens portion between the microlenses (lens portion 435), it is possible to deal with a minute microlens array.

Other Embodiments of the Invention
In the first embodiment of the invention, the opening 132 is provided in the vicinity of the optical axis of the lens unit 135, and the optical axis of the incident light is aligned in a direction perpendicular to the optical sheet surface. On the other hand, the opening can be provided at a position slightly deviated from the optical axis of the lens part 135. In this case, the light beams emitted from the optical sheet 13 can be aligned at an angle slightly shifted from the direction perpendicular to the optical sheet surface.
Graph B in FIG. 7 shows the luminance distribution in the optical sheet 13 when the opening 132 is shifted from the optical axis. As shown in the graph B of FIG. 7, in this case, the main peak B0 is generated at a position shifted from a direction (angle 0 °) substantially perpendicular to the optical sheet surface. That is, the light rays in this case are aligned at an angle deviated from the direction deviated from the direction perpendicular to the optical sheet surface. Similarly to the graph A, in the graph B, sub-peaks B11 and B12 are generated in addition to the main peak B10.

  In addition, an opening 132 with an appropriately controlled shift amount can be manufactured, such as a corrugated opening 132 or an opening 132 in which a plurality of dotted opening windows are overlapped. As a result, the direction in which the outgoing rays are aligned can be controlled as appropriate, and the viewing angle characteristics can be controlled more precisely. Thus, in the illuminating device 1 which concerns on this invention, the light ray generate | occur | produced from the light source 11 can be arrange | equalized in arbitrary directions in arbitrary directions.

In addition, although the illuminating device of this embodiment is a structure which can isolate | separate a housing and an optical sheet physically, a physically integrated structure may be sufficient. That is, a plurality of lenses can be provided at the light exit of the housing that can accommodate the light source, and a plurality of reflecting portions and openings can be disposed inside the housing in accordance with the arrangement positions of the plurality of lenses. .
Hereinafter, the Example of the illuminating device which concerns on this invention is described in detail. In addition, in the following, after describing Examples 1 to 3, a comparative example serving as a comparative control of Examples 1 to 3 will be described.

Example 1.
The optical sheet produced in Example 1 is an example of Embodiment 1. Specifically, first, a lenticular lens sheet having a structure shown in FIG. 1B was produced as an optical sheet 13 by a hot embossing method. Using acrylic having a refractive index of 1.5 as a molding material, the radius of curvature of the lenticular lens (lens portion 135) was 45 μm, and the thickness from the lens apex position to the back of the sheet was 120 μm.

  A reflective metal was formed by sputtering on the back surface (smooth surface) of the optical sheet 13, and the opening 132 was formed by photolithography. Thereby, the reflector 131 was formed on the back surface of the optical sheet 13. Samples having different reflectivities were prepared by sputtering using materials having different reflectivities such as magnesium carbonate, silver, aluminum, chromium, nickel as the reflective metal.

  On the inner surface of the housing 12, samples having different reflectivities were produced by sputtering the same reflective material. The shape of the opening 132 was a slit shape, and the opening width was 10 μm. An opening 132 was provided on the optical axis of the lenticular lens (lens portion 135), and several types of optical sheets 13 were produced. The optical sheet 13 was attached to the light exit 120 of the housing 12 to produce the lighting device 1 and the luminance characteristics thereof were measured.

FIG. 7 shows the viewing angle dependence of the luminance of the manufactured lighting device 1. In FIG. 7, the graph A1 is the measurement result of the luminance characteristic in Example 1, and the graph C1 is the measurement result of the luminance characteristic in Comparative Example 1 described later. FIG. 7 shows the relative luminance when the peak luminance intensity of Comparative Example 1 described later is 1.
As shown in FIG. 7, when compared with the optical sheet 13 of Example 1 and the conventional optical sheet of the comparative example, the front (angle 0 °) luminance of Example 1 sharply increases in a very narrow angle range. I understand that. Therefore, the directivity in the front direction could be improved by using the optical sheet 13 according to the present invention.

FIG. 8 shows the relationship between the reflectance and the luminance of the housing 12 and the optical sheet 13 produced in Example 1. In FIG. 8, the solid line indicates the relationship between the reflectance of the inner surface of the housing 12 and the luminance, and the dotted line indicates the relationship between the reflectance of the reflector 131 and the luminance.
As shown in FIG. 8, it can be seen that the luminance decreases to half or less when the reflectance is 80% or less. From these results, by configuring the inner surface of the housing 12 of the optical sheet 13 and the reflector 131 of the optical sheet 13 according to the present invention so as to reflect visible light with an average reflectance of 80% or more, very steep light collection characteristics are obtained. It can be seen that can be obtained.

Example 2
The opening part 132 of the lenticular lens sheet in Example 1 was manufactured by shifting by 5 μm laterally from the optical axis of the lenticular lens (lens part 135) in Example 1.
Graph B in FIG. 7 shows the viewing angle dependence of the luminance in this case. As shown in FIG. 7, it can be seen that the angle at which light is collected changes by shifting the position of the opening 132 from the optical axis of the lens portion 135. Thus, it can be seen that the angle range of light collection can be arbitrarily controlled by changing the position of the opening 132.

Example 3 FIG.
The optical sheet produced in Example 3 is an example of Embodiment 3. Specifically, first, a lenticular lens sheet having the structure shown in FIG. As the molding material, acrylic having a refractive index of 1.5 was used, the radius of curvature of the lenticular lens (lens portion 235) was 20 μm, and the thickness from the lens apex position to the back surface of the sheet was 55 μm. A flat portion (flat portion 336) was provided between the adjacent lenticular lenses (lens portion 335), and several types of samples were produced by changing the width of the flat surface.

  Silver was formed by sputtering on the back surface (smooth surface) of the optical sheet 33, and the opening 332 was formed by a photolithography method. Thereby, the reflector 331 was formed on the back surface of the optical sheet 33. The shape of the opening 332 was a slit shape, and the opening width was 10 μm. An opening 332 was provided on the optical axis of the lenticular lens (lens portion 335) to produce an optical sheet 33. The optical sheet 33 was attached to the light exit port 120 of the housing 12 to produce the lighting device 1 and its luminance characteristics were measured.

FIG. 9 shows the viewing angle dependence of the luminance of the manufactured lighting device 1. In FIG. 9, the graph A2 is the measurement result of the luminance characteristics in Example 3, and the graph C2 is the measurement result of the luminance characteristics in Comparative Example 1 described later. Further, FIG. 9 shows the relative luminance when the peak luminance intensity of Comparative Example 1 described later is 1. FIG. 9 shows the measurement results when the width between the lenticular lenses of Example 3 is 10 μm, that is, the width of the flat portion 336 is 10 μm.
As shown in FIG. 9, by using the optical sheet 33 of Example 3, only the main peak A20 was generated in the front direction in the luminance peak. Therefore, by providing the flat portion 336 between the lens portions 335, the sub-peaks can be almost removed, and the directivity in the front direction can be reliably increased.

  FIG. 10 shows the ratio between the main peak and the sub-peak when the width of the flat portion 336 is changed in the optical sheet 33 produced in Example 3. It can be seen that when the ratio P / D between the repeated lens pitch P2 and the end-to-end distance D2 from the opening to the lens end is 2.4 or less, the sub-peak decreases to more than half of the main peak.

Example 4
The optical sheet produced in Example 4 is an example of Embodiment 4. Specifically, first, a microlens array sheet having a structure shown in FIG. 4 was produced as an optical sheet 43 by a hot embossing method. As the molding material, acrylic having a refractive index of 1.5 was used, the radius of curvature of the microlens (lens portion 435) of the lens structure 433 was 45 μm, and the thickness from the lens apex position to the back surface of the sheet was 120 μm. The arrangement of the microlenses (lens portion 435) was a hexagonal close-packed arrangement, and the shortest distance (lens pitch) between the lens apexes was 50 μm.

  On the back surface (smooth surface) of the optical sheet 43, silver is formed by sputtering to form the reflector 431 and the opening 432. As shown in FIG. 5, an opening 432 was formed by a photolithography method, thereby forming a reflector 431 on the back surface of the optical sheet 43. The shape of the opening 432 was circular, and the opening diameter was 10 μm. The position of the opening 432 was provided on the optical axis of the microlens (lens part 435), and the optical sheet 43 was produced. The optical sheet 43 was attached to the light exit port 120 of the housing 12 to produce the lighting device 1 and the luminance characteristics thereof were measured.

FIG. 11 shows the viewing angle dependence of the luminance of the manufactured lighting device 1. In FIG. 11, a graph A3 is a measurement result of luminance characteristics in Example 4, and a graph C3 is a measurement result of luminance characteristics in Comparative Example 1 described later. Further, in FIG. 11, the relative luminance when the peak luminance intensity of Comparative Example 1 described later is set to 1 is shown.
As shown in FIG. 11, in the case of the optical sheet 43 of Example 4, as in the case of the optical sheet 13 of Example 1, the main peak A30 occurred in the luminance peak in the front direction. Therefore, in the case of the optical sheet 43 that is a microlens array sheet, sub-peaks A31 and A32 are generated as in the first embodiment, but the directivity in the front direction can be improved.

Comparative Example 1
First, a triangular prism sheet 93 having a structure shown in FIG. 6 was produced by a hot embossing method. Acrylic having a refractive index of 1.5 was used as a molding material, and the thickness from the prism apex position to the back surface of the sheet was 120 μm. The apex angle of the triangular prism 931 was 90 °, and the lens pitch was 50 μm. This optical sheet was attached to the exit of the housing to produce a conventional lighting device, and its luminance characteristics were measured.
FIG. 12 shows the viewing angle dependence of the luminance of this conventional lighting device, graph C4 shows the luminance characteristics, and graph C5 shows a case where two triangular prism sheets 93 are stacked so that the triangular prisms 931 are orthogonal to each other. The luminance characteristic is shown. Moreover, the comparative example shown by the graph C4 is a comparative example serving as a comparative control of the above-described Examples 1 to 3.
In this embodiment, the reflective layer constituting the reflector is formed by the sputtering method, and the opening is formed by the photolithography method. However, the present invention is not limited to this method. There is no problem even if other methods such as Chemical Vapor Deposition), coating method and printing method are used.

It is a schematic diagram which shows the example of 1 structure of the illuminating device which concerns on this invention. It is a side surface schematic diagram which shows another example of the optical sheet which concerns on this invention. It is a side surface schematic diagram which shows another example of the optical sheet which concerns on this invention. It is a schematic diagram which shows another example of the optical sheet which concerns on this invention. It is a schematic diagram which shows another example of the optical sheet which concerns on this invention. It is a perspective schematic diagram which shows an example of the conventional optical sheet. It is a graph which shows an example of the luminance characteristic of the illuminating device which concerns on this invention. It is a relationship graph of the reflectance and the brightness | luminance of the reflector of the optical sheet which concerns on this invention. It is a graph which shows another example of the luminance characteristic of the illuminating device which concerns on this invention. It is a graph which shows the ratio of the main peak of the illuminating device which concerns on this invention, and a subpeak. It is a graph which shows another example of the luminance characteristic of the illuminating device which concerns on this invention. It is a graph which shows the luminance characteristic of the conventional illuminating device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Illuminating device, 11 ... Light source, 12 ... Housing, 13 ... Optical sheet,
DESCRIPTION OF SYMBOLS 120 ... Light exit port, 131 ... Reflector, 132 ... Opening part, 133 ... Lens structure,
134: Reflection part, 135 ... Lens part 23 ... Optical sheet, 231 ... Reflector, 232 ... Opening part, 233 ... Lens structure,
234: Reflection part, 235 ... Lens part 33 ... Optical sheet, 331 ... Reflector, 332 ... Opening part, 333 ... Lens structure,
334: Reflecting part, 335 ... Lens part, 336 ... Flat part 43 ... Micro lens array sheet, 431 ... Reflector, 432 ... Opening part,
434 ... Lens structure 435 ... Micro lens 93 ... Triangular prism sheet, 931 ... Triangular prism

Claims (14)

A light source that emits light;
A housing that houses the light source and is provided with an exit for emitting light from the light source;
An illumination device having an optical sheet disposed at the exit port,
The inner surface of the housing has a reflection effect of reflecting light emitted from the light source,
The optical sheet is
A lens structure that is disposed on the light emission side and aligns the emission direction of the light incident from the light source;
A reflector disposed on the light incident side and reflecting 80% or more of visible light;
Is opened to the reflector, it has a light transmission opening for transmitting incident light from the light source,
The lens structure has a plurality of lens portions,
The light transmission opening is formed so that a center position of the light transmission opening is shifted from an optical axis of the lens unit .   The lighting device according to claim 1, wherein the lens structure aligns the incident light in a direction substantially perpendicular to a sheet surface of the optical sheet.   The lighting device according to claim 1, wherein an inner surface of the housing has a reflection effect of reflecting visible light of 80% or more.   The lighting device according to claim 1, wherein the reflector has a plurality of reflecting portions that are spaced apart from each other with the light transmitting opening portion interposed therebetween. The illumination device according to claim 1, wherein the light transmission opening is formed in the vicinity of an optical axis of the lens structure.   6. The illumination according to claim 5, wherein the lens structure includes a plurality of non-lens portions that are disposed between the plurality of lens portions and have a lens effect smaller than a lens effect of the lens portions. apparatus. The lens structure has a repeating structure in which the plurality of lens portions are repeatedly arranged,
The distance P between the plurality of lens portions and the distance D from the end portion of the light transmission opening to the end portion of the lens portion satisfy a relationship of P / D> 2.4. Item 7. The lighting device according to Item 6. The non-lens portion is a flat surface parallel to the sheet surface of the optical sheet,
The lighting device according to claim 7, wherein the plurality of lens units are connected via the plurality of flat surfaces. The lens part is a long lenticular lens,
The lighting device according to claim 4, wherein the light transmission opening is formed between the plurality of reflection portions in a stripe shape extending in a longitudinal direction of the lenticular lens. The lens unit is a microlens array,
The lighting device according to claim 4, wherein the light transmission openings are formed in the reflector in a scattered state.   The lens structure and the light transmission opening are adjusted so that the maximum luminance value of the main peak in the viewing angle dependence of the luminance of the emitted light is more than twice the maximum luminance value of the sub peak. The illumination device according to any one of claims 1 to 10. A light source that emits light;
A housing that houses the light source and is provided with an exit for emitting light from the light source;
An illumination device having an optical sheet disposed at the exit port,
The inner surface of the housing has a reflection effect of reflecting light emitted from the light source,
The optical sheet is disposed on the light emission side, and a plurality of lens portions that align the emission direction of the light incident from the light source;
A plurality of non-lens portions disposed between the plurality of lens portions and having a lens effect smaller than the lens effect of the lens portions;
A reflector disposed on the light incident side and reflecting the light emitted from the light source;
Is opened to the reflector, it has a light transmission opening for transmitting incident light from the light source,
The light transmission opening is formed so that a center position of the light transmission opening is shifted from an optical axis of the lens unit .   The display apparatus provided with the illuminating device in any one of Claims 1 thru | or 12.   The display device according to claim 13, wherein the illumination device is a liquid crystal display device used as a backlight.

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