JP2011141450A - Lens member and optical unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens member and an optical unit which significantly increases utilization efficiency of incident light, improves distribution of emitted light, and suppresses color unevenness. <P>SOLUTION: The lens member 10 includes, on an incident surface, a Fresnel lens part 14 obtained by dividing the incident surface of a virtual lens into a plurality of concentric sub-areas and comprising a plurality of prism parts 13 corresponding thereto. The virtual lens includes a concave lens part into which the light from a light source is incident, and a convex lens part totally reflecting the light incident from the concave lens part. A prism part 13 comprises a prism incident surface 13a corresponding to the sub-area of the concave lens part, and a prism reflective surface 13b corresponding to the sub-area on the convex lens part. In the Fresnel lens part 14, the prism part 13 of the convex lens part at the outer sub-area is arranged on the inner side, and the prism part 13 corresponding to the inner sub-area is arranged at the outer side. The Fresnel lens part is formed up to the center of the incident surface. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a lens member and an optical unit used for LED lighting, for example.

In general, LED optical products that use LEDs such as headlights and tail lamps for lighting, projectors, flashes, automobiles, etc. as light sources and basic light devices such as narrow directivity LEDs collect light emitted from LEDs. Or a collimating lens is used.
As such a lens, a convex refracting lens is usually used, but it has also been proposed to adopt a Fresnel lens in order to reduce the height and thickness.

  Conventionally, for example, in Patent Document 1, a lattice-like refractive prism portion is formed in the central portion of the inner surface near the optical axis, and a lattice-like reflective prism portion is formed around the lattice-like refractive prism portion. Lamp lenses have been proposed. Further, Patent Document 2 discloses a Fresnel lens formed such that a part of a prism of a Fresnel lens surface which is an incident surface is emitted to an output surface after a part of incident light is totally reflected by a non-lens surface. Has been proposed. Furthermore, Patent Document 3 is composed of a refractive lens part having a lens body provided at the center of the optical axis, and a reflector part. The reflector part allows a light beam to be incident from an inner surface part and has a parabolic shape. There has been proposed an optical device that totally reflects the light from a reflecting surface that converts the light into parallel rays.

JP-A-57-55002 JP 59-119340 A Japanese Patent Laid-Open No. 5-281402

However, the following problems remain in the conventional technology.
That is, the lenses disclosed in Patent Documents 1 to 3 have a disadvantage in that part of the incident light does not reach the reflecting surface and a loss occurs, making it difficult to maximize the light utilization efficiency. For example, in Patent Document 3, since there is a portion where the incident light does not reach the reflection surface between the incident surface and the refractive lens portion, the light transmitted through this portion is a loss.
Further, when an LED is used as a light source, the emitted light has a light distribution in which the light intensity decreases as the radiation angle increases. Therefore, as shown in FIG. 3, a conventional TIR (Total Internal Reflection) lens 1 is used. When light is used, the light incident from the incident surface of the concave lens portion 3 of the TIR lens 1 disposed facing the light source 2 is totally reflected by the reflective surface of the outer convex lens portion 4. The light L <b> 2 around the central portion having a strong target light intensity is reflected by the reflecting surface on the outer peripheral side of the convex lens portion 4. Therefore, in the TIR lens 1, the luminous intensity near the center is high, but the luminous intensity near the middle decreases and the outer luminous intensity increases. For this reason, even if the TIR lens 1 is converted to a Fresnel lens by a conventional method, ring-shaped flare centering on the optical axis is generated in the emitted light, and the appearance is deteriorated.
Furthermore, in the lens of patent document 3, since both the entrance surface and the exit surface of the reflective lens portion are aspherical surfaces, there is a problem that processing is difficult and cost is increased.
In addition, when a downwardly convex refractive lens portion is formed at the center as in this lens, or when the vicinity of the center is a flat incident surface, the color unevenness of the light source is reflected (imaged) on the irradiation surface. There was an inconvenience.

  The present invention has been made in view of the above-described problems, and provides a lens member and an optical unit that can dramatically increase the efficiency of use of incident light and can adjust the distribution of emitted light, and can suppress color unevenness. The purpose is to provide.

  The present invention employs the following configuration in order to solve the above problems. That is, the lens member according to the present invention divides the incident surface of the virtual lens disposed opposite to the light source into a plurality of concentric divided regions centered on the optical axis of the light source, and a plurality of different refraction angles corresponding to these. A concave lens part having a Fresnel lens part composed of a prism part on the incident surface, the virtual lens being arranged around the optical axis and allowing light from the light source to enter the concave lens part, and the concave lens A convex lens part arranged around the part and totally reflecting the light incident from the concave lens part on the surface to the exit surface side, and the prism part corresponds to a divided region of the concave lens part A prism incidence surface and a prism reflection surface corresponding to a division region of the convex lens portion that totally reflects the light incident from the division region, and the Fresnel lens portion is included in the convex lens portion. The prism portion corresponding to the divided region on the side is arranged on the inner side, the prism portion corresponding to the inner divided region is arranged on the outer side, and is formed up to the center of the incident surface. It is characterized by being.

In this lens member, the Fresnel lens portion is configured such that the prism portion corresponding to the outer divided region of the convex lens portion is arranged on the inner side, and the prism portion corresponding to the inner divided region is arranged on the outer side. Therefore, the central light having a high light intensity is incident from the incident surface of the central prism portion and is totally reflected by the reflecting surface of the prism portion. Therefore, the strong light emitted from the outside in the conventional TIR lens can be emitted from the central portion in the present invention. As a result, a luminance distribution can be obtained in which the luminous intensity gradually decreases from the center toward the outside, the center is bright, and the outside is dark, and the occurrence of ring-like flare can be suppressed and the appearance can be improved.
In addition, since the incident surface and the reflecting surface corresponding to each other continuously form the prism portion via the ridgeline, all the light incident from the incident surface reaches the reflecting surface and is totally reflected, Use efficiency can be improved dramatically.
Furthermore, since the Fresnel lens portion is formed up to the center of the incident surface, it is possible to suppress the color unevenness of the light source from being reflected (imaged, projected) on the irradiated surface.
Note that it is possible to further improve the light condensing property by increasing the number of divisions when the Fresnel lens portion is made Fresnel.

Further, the lens member of the present invention is characterized in that an unevenness for controlling at least one of the diffusibility and directivity of the emitted light is formed on the exit surface opposite to the Fresnel lens portion.
In other words, in this lens member, the unevenness that controls at least one of the diffusibility and directivity of the emitted light is formed on the exit surface on the opposite side of the Fresnel lens portion. It becomes easy to emit light with desired diffusivity and directivity by refraction and scattering due to the unevenness of the exit surface.

Furthermore, in the lens member of the present invention, the unevenness has a diffusive shape for diffusing the emitted light, and the central portion side of the emission surface has the diffusive unevenness higher than the outer peripheral side. It is characterized by that.
That is, in this lens member, the center side of the emission surface has higher diffusive unevenness than the outer peripheral side, so that more light is diffused particularly on the center side where color unevenness of the light source is easily reflected. As a result, color unevenness can be effectively suppressed, and a decrease in front illuminance can be suppressed or narrow directivity can be obtained due to low diffusibility on the outer peripheral side.

In the lens member according to the present invention, the unevenness has an anisotropic diffusion shape that diffuses a large amount of the emitted light in a specific direction.
That is, in this lens member, the unevenness has an anisotropic diffusion shape that diffuses a large amount of emitted light in a specific direction, so that it does not diffuse light uniformly but has a narrow directivity in the specific direction. Can be emitted.

The lens member of the present invention is characterized in that an optical sheet for controlling at least one of the diffusibility and directivity of the transmitted light is installed on the exit surface opposite to the Fresnel lens portion. .
That is, in this lens member, an optical sheet that controls at least one of the diffusibility and directivity of the transmitted light is installed on the exit surface on the opposite side of the Fresnel lens portion. It becomes easy to emit the condensed light with a desired diffusivity and directivity by refraction and scattering by the optical sheet on the exit surface side. For example, by using a diffusion sheet that uniformly scatters transmitted light, an anisotropic diffusion sheet that diffuses or refracts much transmitted light in a specific direction, or an optical sheet such as a prism sheet, various light diffusibility and directivity Can be set arbitrarily.

The optical unit of the present invention includes a light source that is an LED and the lens member of the present invention.
That is, since this optical unit includes the lens member of the present invention disposed opposite to the light source that is an LED, the illumination, projector, flash, LED optical products such as automobile headlamps and taillamps can be obtained.

Moreover, the optical unit of the present invention is characterized in that the light source is an array of a plurality of LED elements.
That is, in this optical unit, since the light source is an array of a plurality of LED elements, the arrangement and color unevenness of the arrayed LED elements are caused on the irradiation surface by the lens member formed by the Fresnel lens part to the center part. It is possible to suppress the reflection.

The present invention has the following effects.
That is, according to the lens member and the optical unit according to the present invention, the Fresnel lens portion is disposed more inside the prism portion corresponding to the outer divided region of the convex lens portion, and the prism portion corresponding to the inner divided region. Since it is arranged so as to be closer to the outside, the appearance of the emitted light can be improved and the light use efficiency can be dramatically improved. In addition, since the Fresnel lens portion is formed up to the center of the incident surface, it is possible to suppress the color unevenness of the light source from being reflected (image formation, projection) on the irradiation surface, and good illumination light with a small chromaticity difference. Can be obtained.

FIG. 2 is a plan view showing the lens member in the first embodiment of the lens member and the optical unit according to the present invention. It is the sectional view on the AA line of FIG. In 1st Embodiment, it is a principle explanatory drawing of the conventional TIR lens and the virtual lens. In 1st Embodiment, it is a principle explanatory drawing of a lens member and an optical unit. In 1st Embodiment, it is sectional drawing which shows an optical unit. In 1st Embodiment, it is a perspective view which shows an optical unit. In 1st Embodiment, it is an image which shows a color nonuniformity image. It is sectional drawing which shows a lens member in the comparative example of the lens member which concerns on this invention, and an optical unit. In a comparative example, it is an image which shows a color nonuniformity image. It is sectional drawing which shows a lens member in 2nd Embodiment of the lens member and optical unit which concern on this invention. In 2nd Embodiment, it is an enlarged view which shows the output surface of a lens member. In 2nd Embodiment, it is an image which shows a color nonuniformity image. In 3rd Embodiment of the lens member and optical unit which concern on this invention, it is a schematic diagram which shows the output surface of a lens member. In 3rd Embodiment, it is a typical enlarged plan view which shows the unevenness | corrugation with the outer peripheral side and center part side in the output surface of a lens member. In 3rd Embodiment, it is a typical expanded sectional view which shows the example of the unevenness | corrugation in the output surface of a lens member. In 4th Embodiment of the lens member and optical unit which concern on this invention, it is a perspective view which shows the lens member seen from the output surface side. In 4th Embodiment, it is an image which shows an illumination intensity distribution image. In 5th Embodiment of the lens member and optical unit which concern on this invention, it is a perspective view which shows the lens member seen from the output surface side. In 6th Embodiment of the lens member and optical unit which concern on this invention, it is a perspective view which shows the lens member seen from the output surface side. In 6th Embodiment, it is a graph which shows directivity. In 6th Embodiment, it is an image which shows an illuminance distribution image. It is sectional drawing which shows a lens member in 7th Embodiment of the lens member and optical unit which concern on this invention.

  Hereinafter, a first embodiment of a lens member and an optical unit according to the present invention will be described with reference to FIGS. In each drawing used in the following description, the scale is appropriately changed to make each member a recognizable size.

As shown in FIGS. 1 to 4, the lens member 10 in the present embodiment has a plurality of concentric circles with the incident surface of the virtual lens 11 disposed opposite to the light source 2 that is an LED centered on the optical axis AX of the light source 2. The TIR lens has a Fresnel lens portion 14 formed of a plurality of prism portions 13 and 13A to 13C having different refraction angles corresponding to these divided regions 3a to 3c and 4a to 4c.
The lens member 10 is integrally formed of a light transmissive material such as acrylic resin.

  The lens member 10 includes a concave lens unit 3 in which the virtual lens 11 is disposed around the optical axis AX and allows light from the light source 2 to enter the inside, and a concave lens unit 3 disposed around the concave lens unit 3. Assuming that the TIR lens has a convex lens portion 4 that totally reflects light incident from the surface toward the exit surface side, the prism portions 13 and 13A to 13C are divided regions of the concave lens portion 3. The prism incident surface 13a corresponding to 3a to 3c and the prism reflecting surface 13b corresponding to the divided regions 4a to 4c of the convex lens portion 4 that totally reflects the light incident from the divided regions 3a to 3c. .

  That is, as shown in FIG. 3 and FIG. 4, in the concave lens portion 3 of the virtual lens 11, the inner divided region 3 a around the central portion and the convex lens portion 4 where the light incident from the divided region 3 a is totally reflected. The outer divided region 4a around the outer peripheral portion corresponds to the prism incident surface 13a of the prism portion 13A and the prism reflecting surface 13b of the prism portion 13A around the central portion of the lens member 10 according to the present embodiment by forming a Fresnel lens. To do.

Further, in the concave lens part 3 of the virtual lens 11, the divided area 3b outside the divided area 3a and the divided area 4b inside the divided area 4a of the convex lens part 4 where the light incident from the divided area 3b is totally reflected are defined. This corresponds to the prism incident surface 13a of the prism portion 13B and the prism reflecting surface 13b of the prism portion 13B at the intermediate portion between the center portion and the vicinity of the outer periphery of the lens member 10 of the present embodiment.
Further, in the concave lens portion 3 of the virtual lens 11, an outer divided region 3c near the convex lens portion 4 and an inner portion around the inner peripheral portion of the convex lens portion 4 where the light incident from the divided region 3c is totally reflected. The divided region 4c corresponds to the prism incident surface 13a of the prism portion 13C around the outer peripheral portion of the lens member 10 of the present embodiment and the prism reflecting surface 13b of the prism portion 13C.

  As described above, the Fresnel lens portion 14 is arranged closer to the prism portion 13 corresponding to the outer divided regions 4a to 4c in the convex lens portion 4, and closer to the prism portion 13 corresponding to the inner divided regions 4a to 4c. It is arranged outside and is formed up to the center of the incident surface. Accordingly, each prism portion 13 has an apex angle that changes depending on the relative position with respect to the light source 2.

The prism reflecting surface 13b is formed of a flat surface or a quadratic curved surface such as a paraboloid, a hyperboloid, or an ellipsoid.
The prism incident surface 13a is inclined with respect to the optical axis AX and is directed to the light source 2 side. The prism incident surface 13a is formed of a flat surface or a convex secondary curved surface, but is preferably formed of a flat surface in consideration of workability.
In the present embodiment, the exit surface on the opposite side of the Fresnel lens portion 14 is a flat surface.

  The light source 2 is an array of a plurality of LED elements. For example, a so-called multichip LED in which a plurality of LED elements are arranged in a lattice shape is employed. As the light source 2, not only a multi-chip LED but also one having one LED element can be adopted.

  Next, the incidence and emission of light from the light source 2 in the lens member 10 of the present embodiment will be described.

For example, in the virtual lens 11 shown in FIG. 3, the light L1 having the strongest light intensity emitted from the light source 2 toward the central portion directly above is transmitted from the central portion (divided region 3a) of the incident surface of the inner concave lens portion 3. In addition to being incident, it is totally reflected by the reflection surface (divided region 4a) in the vicinity of the outer edge of the convex lens portion 4, and is emitted from the vicinity of the outer peripheral portion of the emission surface.
On the other hand, in the lens member 10 of the present embodiment in which the virtual lens 11 is formed into Fresnel as shown in FIG. 4, the light L1 having the strongest light intensity emitted from the light source 2 toward the central portion directly above is the inner center. The light is incident from the prism incident surface 13a of the prism portion 13A, is totally reflected by the prism reflection surface 13b of the prism portion 13A, and is emitted from the central portion of the emission surface.

In the virtual lens 11, the light L2 around the central portion having a relatively strong light intensity emitted from the light source 2 in a slightly oblique direction with respect to the optical axis AX is incident on the incident surface (divided region 3b) of the inner concave lens portion 3. ) And is totally reflected by the outer reflecting surface (divided region 4b) of the convex lens portion 4, and is emitted from an intermediate portion between the central portion and the outer edge of the emitting surface.
On the other hand, in the lens member 10 of the present embodiment, the light L2 around the central portion having a relatively strong light intensity emitted from the light source 2 in a slightly oblique direction with respect to the optical axis AX is the prism of the inner prism portion 13B. The light is incident from the incident surface 13a and is totally reflected by the prism reflecting surface 13b of the prism portion 13B, and is emitted from an intermediate portion between the central portion and the outer edge of the emitting surface.

Further, in the virtual lens 11, light L3 having a relatively low light intensity emitted from the light source 2 in a largely oblique direction with respect to the optical axis AX is incident from the incident surface (divided region 3c) of the inner concave lens portion 3. And is totally reflected by the reflection surface (divided region 4c) inside the convex lens portion 4 and emitted from the periphery of the central portion of the emission surface.
On the other hand, in the lens member 10 of the present embodiment, the light L3 having a relatively low light intensity emitted from the light source 2 in a largely oblique direction with respect to the optical axis AX is transmitted from the prism incident surface 13a of the outer prism portion 13C. The light is incident and totally reflected by the prism reflecting surface 13b of the prism portion 13C, and is emitted from the vicinity of the outer edge portion of the emitting surface.

Next, as shown in FIGS. 5 and 6, the optical unit 120 of the present embodiment includes the light source 2 that is an LED, the lens member 10, and a housing 121 that houses them.
The housing 121 includes a hemispherical portion 122 in which the light source 2 is installed at the center of the upper surface portion, and a substantially cylindrical lens support frame that houses the lens member 10 and is disposed on the upper surface portion of the hemispherical portion 122. Part 123. The lens support frame portion 123 is placed on the upper surface portion of the hemispherical portion 122 with the lens members 10 facing the light source 2 with the center axes thereof aligned.

  Next, FIG. 7 shows the result of examining the color unevenness of the illumination light when the light emitted from the light source 2 is transmitted for the lens member 10 of the present embodiment. For comparison, as shown in FIG. 8, a lens member 100 having a convex lens portion 101 formed at the center of the incident surface was produced as a comparative example, and color unevenness was similarly examined for this lens member 100. The results are shown in FIG. The color unevenness images shown in FIGS. 7 and 9 are obtained by converting a color image into a grayscale monochrome image, and XY chromaticity coordinates are shown beside the image.

  From these results, in the lens member 100 of the comparative example, a region near yellow or a region near blue is locally generated and has color unevenness, whereas in the lens member 10 of the present embodiment, the region is yellow or blue. It can be seen that color unevenness is reduced as a whole with few close areas.

  As described above, in the lens member 10 of the present embodiment, the Fresnel lens portion 14 is arranged on the inner side of the convex lens portion 4 as the prism portion 13 corresponding to the outer divided regions 3a to 3c, and the inner divided region 3a. Since the prism portion 13 corresponding to ˜3c is arranged on the outer side, the light of the central portion having a strong light intensity is incident from the prism incident surface 13a of the prism portion 13A of the central portion and the prism portion 13A It is totally reflected by the prism reflecting surface 13b.

Therefore, strong light emitted from the outside in the conventional TIR lens or Fresnel lens can be emitted from the central portion in the lens member 10 of the present embodiment.
Thus, in the lens member 10 of the present embodiment, a luminance distribution is obtained in which the luminous intensity gradually decreases from the center toward the outside, the center is bright, and the outside is dark, and the occurrence of ring-like flare is suppressed and the appearance is improved. be able to.

In addition, since the incident surface and the reflecting surface corresponding to each other continuously form the prism portions 13 via the ridgeline, all the light incident from the incident surface reaches the reflecting surface and is totally reflected, and the light The utilization efficiency can be dramatically improved.
Further, since the Fresnel lens portion 14 is formed up to the center of the incident surface, it is possible to suppress the color unevenness of the light source 2 from being reflected (imaged, projected) on the irradiated surface.
Note that the light condensing property can be further improved by increasing the number of divisions when the Fresnel lens unit 14 is made Fresnel.

In addition, since the prism reflecting surface 13b is a flat surface, the processing becomes very easy and can be manufactured at low cost.
Further, since the prism incident surface 13a is inclined with respect to the optical axis AX and directed toward the light source 2, the light easily enters, and the prism incident surface 13a and the optical axis AX are not parallel to each other. In this case, the releasability can be improved and the lens member 10 with good quality can be obtained.

Therefore, in the optical unit 120 provided with the lens member 10, LED optical products such as illumination, projector, flash, and headlight / taillight of automobiles having high use efficiency and good appearance of light emitted from the light source 2 of the LED. Etc. can be obtained.
Moreover, in this optical unit 120, since the light source 2 has a plurality of LED elements arranged, the arrangement and color unevenness of the arranged LED elements by the lens member 10 formed by the Fresnel lens part 14 up to the center. Can be prevented from being reflected on the irradiated surface.

  Next, second and third embodiments of the lens member and the optical unit according to the present invention will be described below with reference to FIGS. In the following description of each embodiment, the same constituent elements described in the above embodiment are denoted by the same reference numerals, and the description thereof is omitted.

The difference between the second embodiment and the first embodiment is that in the first embodiment, the exit surface on the opposite side of the Fresnel lens portion 14 is a flat surface, whereas in the lens member 20 of the second embodiment, As shown in FIG. 10 and FIG. 11, an uneven surface 21 that controls at least one of the diffusibility and directivity of the emitted light is formed on the exit surface on the opposite side of the Fresnel lens portion 14.
That is, in the lens member 20 of the second embodiment, as shown in FIG. 11, for example, a plurality of elliptical convex portions having diffusibility for diffusing emitted light are arranged on the emission surface as the unevenness 21. . In addition, it is preferable that this unevenness | corrugation 21 is an aspherical convex part in order to refract light efficiently. Further, for example, a quadrangular pyramid shape or the like may be adopted as another unevenness.

FIG. 12 shows the result of examining the color unevenness of the lens member 20 of the second embodiment, as in the first embodiment. From this result, it can be seen that the color unevenness is further reduced as compared with the lens member 10 of the first embodiment.
Thus, in the lens member 20 of 2nd Embodiment, since the unevenness | corrugation 21 which controls at least one of the diffusibility of the emitted light and directivity is formed in the output surface on the opposite side of the Fresnel lens part 14. FIG. The light condensed as much as possible by the Fresnel lens unit 14 can be easily emitted with desired diffusivity and directivity by refraction and scattering by the unevenness 21 on the emission surface.

  Further, the difference between the third embodiment and the second embodiment is that, in the second embodiment, the irregularities 21 are uniformly arranged on the exit surface, whereas in the lens member 30 of the third embodiment, FIG. As shown in FIG. 13, the center side of the emission surface has a higher diffusive unevenness 31 than the outer peripheral side.

  That is, in the lens member 30 of the third embodiment, as shown in FIG. 13 and FIG. 14A, the installation density of the convex lens-shaped irregularities 31 provided on the center side is increased and the light diffusibility is high. As shown in FIG. 14B, the high diffusibility region 32A is provided around the high diffusibility region 32A up to the outer periphery, and the installation density of the irregularities 31 is made lower than that of the high diffusibility region 32A to diffuse light. The low diffusibility region 32B having a low property is formed on the emission surface. In FIG. 13, the highly diffusive region 32A is hatched.

  As described above, in the lens member 30 of the third embodiment, the central portion of the emission surface has the diffusive unevenness 31 that is higher than that of the outer peripheral side. By diffusing more light on the side, color unevenness can be effectively suppressed, and on the outer peripheral side, it is also possible to suppress a decrease in front illuminance or obtain a narrow directivity due to low diffusivity. .

As another example of the third embodiment, the convex lens-shaped irregularities 31 formed in the high diffusibility region 32A on the center side shown in FIG. 15A are arranged on the outer peripheral side shown in FIG. The height may be set higher than the convex lens-shaped irregularities 31 formed in the low diffusibility region 32B, and the diffusibility may be increased.
As another example, the convex lens-shaped irregularities 31 formed in the high diffusibility region 32A on the center side shown in FIG. 15A are converted into the low diffusivity region on the outer periphery side shown in FIG. It is also possible to set the curvature smaller than that of the convex lens-shaped irregularities 31 formed in 32B so as to have high diffusibility.
In the third embodiment, the high diffusibility region 32A and the low diffusibility region 32B are clearly separated on the inner side and the outer side. You may make it raise from the outside to the inside.

  Next, fourth to seventh embodiments of the lens member and the optical unit according to the present invention will be described below with reference to FIGS.

The difference between the fourth embodiment and the second embodiment is that, in the second embodiment, a plurality of convex dot-like irregularities 21 are formed on the exit surface on the opposite side of the Fresnel lens portion 14, whereas In the lens member 40 of the fourth embodiment, as shown in FIG. 16, a plurality of annular protrusions and recesses 41 centering on the central axis are formed on a concentric circle on the exit surface.
The irregularities 41 are, for example, saddle-shaped convex portions having a circular arc cross section.

  FIG. 17 shows the result of examining the illuminance distribution image for the lens member 40 of the fourth embodiment. Note that FIG. 17 is obtained by converting an illuminance distribution image of a color image into a grayscale monochrome image. From this result, it can be seen that an isotropic diffusibility with higher illuminance is obtained toward the center side.

Further, the fifth embodiment differs from the fourth embodiment in that the fourth embodiment has a plurality of conical circles 41 having a ring-shaped ridge shape on the exit surface, whereas the fifth embodiment is different from the fifth embodiment. In the lens member 50 of the embodiment, as shown in FIG. 18, a plurality of linear protrusion-shaped irregularities 51 extending radially from the center of the exit surface are formed.
Also in the lens member 50 of the fifth embodiment, as in the fourth embodiment, isotropic diffusibility with higher illuminance is obtained toward the center side.

Next, the difference between the sixth embodiment and the fourth embodiment is that in the fourth embodiment, a plurality of annular protrusions 41 are formed on the light exit surface on the concentric circles. In the lens member 60 of the embodiment, as shown in FIG. 19, a plurality of linear protrusion-shaped irregularities 61 extending in parallel with each other in a specific direction are formed.
That is, in the sixth embodiment, the unevenness 61 has an anisotropic diffusion shape that diffuses a large amount of emitted light in a specific direction.

  In the lens member 60 of the sixth embodiment, as shown in FIG. 20, the directivity in the extending direction (X direction) of the unevenness 61 is narrow, and the directivity in the direction (Y direction) orthogonal to the extending direction of the unevenness 61. It has directivity that widens the nature. Therefore, in the lens member 60 of the sixth embodiment, unlike the fourth and fifth embodiments, as shown in FIG. 21, an anisotropic diffusivity in which the illuminance distribution image is widely biased in the Y direction is obtained. .

As described above, in the lens member 60 of the sixth embodiment, since the unevenness 61 has an anisotropic diffusion shape that diffuses a large amount of emitted light in a specific direction, it does not diffuse light uniformly. It is possible to emit light with a narrow directivity in a specific direction.
As in the lens member 20 of the second embodiment, even when all the elliptical irregularities 21 having a long diameter in a certain direction are arranged in the same direction, a large amount of light is emitted in a specific direction. Anisotropy to diffuse can be obtained.

  In addition, although the unevenness | corrugation of the output surface in the said 2nd to 6th embodiment is all convex shape, it is possible to obtain the same diffusibility and directivity even if it is concave shape.

  Next, the difference between the seventh embodiment and the second embodiment is that, in the second embodiment, the unevenness that controls the diffusivity and directivity of the emitted light on the opposite exit surface of the Fresnel lens portion 14. On the other hand, in the lens member 70 of the seventh embodiment, as shown in FIG. 22, the diffusibility and directivity of the transmitted light are transmitted to the exit surface on the opposite side of the Fresnel lens portion 14. An optical sheet 71 for controlling at least one of them is installed.

  That is, in the lens member 70 of the seventh embodiment, the unevenness is not directly formed on the exit surface on the opposite side of the Fresnel lens portion 14, but a diffusion sheet that uniformly scatters the transmitted light, and the transmitted light is specified. An optical sheet 71 such as an anisotropic diffusion sheet or a prism sheet that scatters or refracts a lot in the direction is provided, so that various light diffusibility and directivity can be arbitrarily set. The optical sheet 71 is preferably a material having a small refractive index difference from the material of the lens member body.

  As described above, in the lens member 70 of the seventh embodiment, the optical sheet 71 that controls at least one of the diffusibility and the directivity of the transmitted light is installed on the exit surface on the opposite side of the Fresnel lens portion 14. The light condensed as much as possible by the Fresnel lens unit 14 can be easily emitted with desired diffusivity and directivity by refraction and scattering by the optical sheet 71 on the emission surface side.

  Next, the lens member of the comparative example, the lens member of the first embodiment, the lens member using a diffusion sheet having a haze value of 29% and 46% in the seventh embodiment as an optical sheet, and the lens member of the second embodiment Table 1 below shows the results of measuring the in-plane chromaticity difference, the front illuminance, and the full width at half maximum (FWHM).

  From this result, compared with the lens member of the comparative example, the lens member of the first embodiment, the lens member using the diffusion sheet having the haze values of 29% and 46% in the seventh embodiment as the optical sheet, and the lens of the second embodiment It can be seen that the in-plane chromaticity difference decreases in the order of the members, and the color unevenness is reduced.

  In addition, this invention is not limited to said each embodiment, A various change can be added in the range which does not deviate from the meaning of this invention.

  DESCRIPTION OF SYMBOLS 2 ... Light source, 3 ... Concave lens part, 3a-3c ... Divided area | region of concave lens part, 4 ... Convex lens part, 4a-4c ... Divided area | region of convex lens part 10, 20, ... 70 ... Lens Member, 11 ... virtual lens, 13, 13A to 13C ... prism portion, 13a ... prism incident surface, 13b ... prism reflecting surface, 14 ... Fresnel lens portion, 21, 31, ... 61 ... irregularities, 71 ... optical sheet, 120: Optical unit, AX: Optical axis of light source

Claims (7)

A Fresnel lens unit comprising a plurality of prism units having different refraction angles corresponding to a plurality of concentric divided regions centered on the optical axis of the light source by dividing an incident surface of a virtual lens disposed opposite to the light source A lens member on an incident surface,
The virtual lens is arranged around the optical axis and has a concave lens portion that allows light from the light source to enter the inside, and the light that is arranged around the concave lens portion and incident from the concave lens portion is emitted from the surface. A convex lens part that totally reflects to the surface side,
The prism portion includes a prism incident surface corresponding to a divided region of the concave lens portion and a prism reflecting surface corresponding to a divided region of the convex lens portion that totally reflects the light incident from the divided region. ,
The Fresnel lens part is arranged such that the prism part corresponding to the outer divided area is arranged on the inner side of the convex lens part, and the prism part corresponding to the inner divided area is arranged on the outer side. And a lens member formed to the center of the incident surface. The lens member according to claim 1,
A lens member, wherein an unevenness for controlling at least one of diffusibility and directivity of the emitted light is formed on an exit surface opposite to the Fresnel lens portion. The lens member according to claim 2,
The unevenness has a diffusive shape for diffusing the emitted light,
The lens member characterized in that a central portion side of the emission surface has the diffusive unevenness higher than that of the outer peripheral side. The lens member according to claim 2 or 3,
The lens member, wherein the unevenness has an anisotropic diffusion shape that diffuses a large amount of the emitted light in a specific direction. The lens member according to claim 1,
An optical sheet for controlling at least one of the diffusibility and directivity of the transmitted light is installed on an exit surface opposite to the Fresnel lens portion. A light source that is an LED;
An optical unit comprising: the lens member according to claim 1. The optical unit according to claim 6,
An optical unit, wherein the light source is an array of a plurality of LED elements.