JP2012063736A - Luminous flux control member and optical device having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a luminous flux control member with which desired and excellent light distribution characteristics can be simply and securely obtained and light use efficiency can be improved, by layout having no unreasonableness on manufacturing.SOLUTION: An incident part 24 comprises: a first incident surface 25 formed of a part of relatively wide range on a side of a surface to be irradiated; and a second incident surface 26 which is connected to both of the first incident surface 25 and a total reflection part 15 and is formed of a part of relatively narrow range on a light source side. The second incident surface 26 is formed on an inclined surface such that a tip of a projection part 11 is cut out and which is inclined to the outside in a radial direction against an optical axis as the tip goes toward the light source side.

Description

  The present invention relates to a light beam control member and an optical device including the same, and more particularly to a light beam control member suitable for irradiating a surface to be irradiated with light emitted from a light source and an optical device including the same.

  Conventionally, as a light flux control member suitable for thinning and lightening, a light incident area is divided into a plurality of concentric annular (annular) divided areas (hereinafter referred to as Fresnel shape). A light beam control member (so-called Fresnel lens) is known, and this type of light beam control member is particularly advantageous for thinning and applications where the influence of unnecessary light generation can be ignored (for example, loupes, illumination systems) (See, for example, Patent Document 1).

  When this type of light flux control member is incorporated into a product for lighting applications, a light source (light emitting element) such as an LED (Light Emitting Diode) is emitted from the light source on the incident area side formed in the Fresnel shape. The light beam is fixed after being aligned so that the central axis of the light is coaxial with the optical axis of the light flux controlling member.

  In addition, the Fresnel shape of this type of light flux controlling member includes a type having only a refracting surface that refracts light emitted from a light source, and a type having a reflecting surface as well as a refracting surface. However, the latter is more advantageous than the former in efficiently capturing and converging light emitted from a light source (for example, LED) with a large spread angle.

  Here, FIG. 14 shows a conventional design example of the light flux controlling member 1 having this kind of reflecting surface.

  As shown in FIG. 14, the light flux control member 1 includes a disk-shaped light flux control unit 2 including an optical axis OA involved in the control of the light flux, and a cylindrical edge portion 3 surrounding the light flux control unit 2. It is configured. The light flux controlling member 1 is made of gold by an injection molding method using a transparent resin material such as PMMA (polymethyl methacrylate), PC (polycarbonate), COP (cycloolefin resin), EP (epoxy resin), or silicone resin. It can be integrally formed using a mold.

  As shown in FIG. 14, the light flux control unit 2 has two light flux control surfaces 4 and 5, which are an entrance region 4 and an exit region 5 that face each other in the optical axis OA direction. In addition, the light beam control unit 2 of the light beam control member 1 shown in a sectional view in FIG. 14 is formed to be circular in the plan view.

  Here, as shown in FIG. 14 and FIG. 15, the light L emitted from the light source 6 such as an LED disposed at a position facing the incident region 4 on the optical axis OA is incident on the incident region 4. It has become. However, the light source 6 emits light L having a predetermined spread angle with respect to the optical axis OA direction toward the light flux controlling member 1 side. Further, the central axis of the light L emitted from the light source 6 coincides with the optical axis OA of the light flux controlling member 1 in design. In FIG. 14, only the optical path of the light L emitted from one light emitting point on the optical axis OA in the light source 6 is shown, but actually, the entire light source 6 performs surface light emission. It has become.

  On the other hand, the light L of the light source 6 incident on the incident region 4 is incident on the inside of the light beam control unit 2 after entering the light beam control unit 2 (internal incidence). The internally incident light L is emitted from the emission region 5 to the irradiated surface side.

  The incident region 4 will be described in more detail. The incident region 4 shown in an enlarged cross-sectional view in FIG. 15 includes a circular central portion 8 centered on the optical axis OA and a plurality of protrusions 11 surrounding the central portion 8. Have.

  As shown in FIGS. 14 and 15, the plurality of protrusions 11 are adjacent to each other in the radial direction (lateral direction in FIGS. 14 and 15).

  Each protrusion 11 has a concentric annular shape centered on the optical axis OA when viewed from the optical axis OA direction, and has a cross-sectional shape (longitudinal section) in the optical axis OA direction as shown in FIGS. Shape) has a saw-tooth shape, forming a Fresnel shape as a whole.

  Furthermore, as shown in FIG. 15, each protrusion 11 is formed on the entrance surface 14 and at all positions on the outside in the radial direction with reference to the optical axis OA with respect to the entrance surface 14 (inner end in the radial direction). And a reflective surface 15. The incident surface 14 is formed in a cylindrical surface centered on the optical axis OA, and the total reflection surface 15 has a predetermined acute angle (for example, 25 °) inclination angle (taper angle) with respect to the optical axis OA. A tapered surface with the optical axis OA as the central axis is formed. The incident surface 14 and the total reflection surface 15 are connected to each other at both tip portions (lower end portions in FIG. 15).

  Here, the light L emitted from the light source 6 is incident on the incident surface 14, and the incident light L is refracted by the incident surface 14 toward the total reflection surface 15. Yes.

  On the other hand, the light L of the light source 6 refracted by the incident surface 14 is incident on the total reflection surface 15 from the inner side of the protrusion 11 at an incident angle greater than the critical angle. The total reflection surface 15 reflects the light toward the emission region 5 side, that is, the irradiated surface side.

  Since the total reflection surface 15 is formed in a shape to be rotated with the optical axis OA as the axis of symmetry, as shown in FIG. 16, the total reflection surface 15 as shown in FIG. Cone-like (conical) light having an angle of ± θ [°] (acute angle) with the clockwise direction being positive is emitted.

  Then, the light emitted from the total reflection surface 15 in this way reaches the emission region 5 and is emitted from the emission region 5 toward the irradiated surface.

  According to such a light flux controlling member 1, the light emitted from the light source 6 by the incident surface 14 having the sharp protrusion 11 formed at a sufficient height (for example, 0.2 mm) in the optical axis OA direction. Can be efficiently captured, and the luminous flux can be controlled so that most of the captured light is totally reflected by the total reflection surface 15 onto the optical path toward the irradiated surface.

  Thereby, the light flux controlling member 1 can obtain light distribution characteristics as shown in FIG. 17, for example. Here, FIG. 17 shows the distribution of the intensity (cd) of the emitted light from the light flux controlling member 1, that is, the light distribution of the emitted light from the light flux controlling member 1. In FIG. 17, an angle of 0 ° corresponds to the front (irradiation direction) in the direction of the optical axis OA. Further, FIG. 17 shows a distribution having a lateral extension in FIG. 14 with the optical axis OA direction as the center (0 °). In this light distribution characteristic, the intensity of the emitted light shows a maximum value (peak intensity) in the vicinity of an angle of 0 °, the intensity of the emitted light at an angle of 0 ° shows a value close to the maximum value, and the maximum value The full width at half maximum, which is the width (angle) of the distribution at the half value to the left and right, is about 30 ° (± 15 °).

JP 2007-134316 A

  However, when the light distribution characteristic shown in FIG. 17 is set as an ideal (design) light distribution characteristic and the light flux controlling member 1 is actually molded using a mold aiming at the light distribution characteristic, projections on the mold are formed. In some cases, the transfer surface of the tip of the portion 11 is insufficiently filled with the resin material.

  The light flux controlling member 1 ′ actually obtained when such insufficient filling occurs, for example, as shown in FIG. 18, the height of the protrusion 11 (incident surface 14) is the designed height. On the other hand, it is reduced to, for example, 85%, and the edge that should originally be formed is not formed at the tip of the protrusion 11, but instead a defectively formed part such as a rounded part or a curved part is formed It was.

  Such a light distribution characteristic of the light flux controlling member 1 'is deteriorated from the ideal light distribution characteristic (FIG. 17) as shown in FIG. Specifically, as described above, the maximum value of the intensity of the emitted light when insufficient filling occurs is reduced by 20% or more with respect to the maximum value of the intensity of the emitted light in the case of an ideal light distribution characteristic. It was. In the case of an ideal light distribution characteristic, the intensity of the emitted light is close to the maximum value at an angle of 0 °, whereas when insufficient filling occurs, as shown in FIG. At an angle of 0 °, the intensity of the emitted light was far below the maximum value.

  Here, in the light flux controlling member 1 ′ of FIG. 18, the poorly shaped part at the tip of the protrusion 11 acts like a lens surface, so that the incident light to the poorly shaped part is concentrated near the center of curvature. Will be. Then, the condensed light does not enter the total reflection surface 15 but travels in a direction different from the normal optical path totally reflected by the total reflection surface 15, so that the surface to be irradiated (effective irradiation target) Unnecessary light (stray light) that is not irradiated to (range). As a result, the obtained light distribution characteristic is deteriorated more than ideal, and such a light flux controlling member 1 ′ cannot obtain sufficient illuminance in the irradiated range by the emitted light.

  Such deterioration of the light distribution characteristics is a serious problem not only from the viewpoint of obtaining desired optical performance, but also from the viewpoint of efficiently using light from the light source.

  Here, the problem is that if the original shape is corrected, the shape of the protrusion 11 that is too sharp is difficult to transfer from the mold on the mold, so that the mold shape is reproducible so that insufficient filling does not occur from the beginning. It may be possible to solve the problem easily by designing a good shape of the protrusion 11.

  From this point of view, it is not difficult to come up with, for example, a light flux controlling member 1 ″ with improved resin material filling properties as shown in FIG. 20. This light flux controlling member 1 ″ is shown in FIGS. The tip end portion of the protrusion 11 of the light flux controlling member 1 shown in FIG. 6 is simply cut off by a cutting line perpendicular to the optical axis OA. Since such a light flux controlling member 1 ″ has a flat tip portion of the protrusion 11, the transfer material of the tip portion can be appropriately filled with a resin material.

  However, such a light flux controlling member 1 ″ can cope with the above-mentioned problem in terms of suppressing the deterioration of the light distribution characteristic due to insufficient filling of the resin material, but the tip of the protrusion 11 ( The light incident on the flat portion does not enter the total reflection surface 15 but travels in a direction different from the normal optical path totally reflected by the total reflection surface 15 and becomes unnecessary light that is not irradiated on the irradiated surface. Therefore, similar to the light flux controlling member 1 ′ in FIG. 18, the obtained light distribution characteristic (see FIG. 21) is different from the target.

  Therefore, as shown in FIG. 20, even if the sharpness of the protrusion 11 is simply relaxed, the target light distribution characteristic and light utilization efficiency can be obtained even if the problem of insufficient filling of the resin material can be solved. The problem of being unable to continue remains.

  Therefore, the present invention has been made in view of such problems, and it is possible to easily and surely obtain a desired light distribution characteristic as a result of a design that does not have a problem in manufacturing, and to improve the light utilization efficiency. It is an object of the present invention to provide a luminous flux control member that can be made and an optical device including the same.

  In order to achieve the above-described object, a feature of the light flux controlling member according to claim 1 of the present invention is that an incident area where light emitted from a light source enters is opposed to the incident area in the optical axis direction, and the incident area A light beam control member having an emission region that emits the light incident on the irradiated surface side toward the irradiated surface, wherein the incident region has a concentric ring shape centered on the optical axis when viewed from the optical axis direction. And a plurality of protrusions that are adjacent to each other in the radial direction such that the cross-sectional shape has a saw-tooth shape, and the protrusions receive light emitted from the light source and refract the incident light. And a total reflection portion that is formed at an outer position in the radial direction with respect to the optical axis with respect to the incident portion, and totally reflects the light incident from the incident portion toward the emission region, The incident part is on the irradiated surface side A first incident surface having a relatively wide range of positions, and a relatively narrow range of portions positioned on the light source side connected to both the first incident surface and the total reflection portion. A second incident surface, and the second incident surface is arranged on the outer side in the radial direction with respect to the optical axis toward the light source side such that a tip portion of the protrusion is cut away. It is in the point formed in the inclined inclined surface. According to the first aspect of the present invention, the sharpness of the protrusion is reduced by sandwiching the second incident surface between the first incident surface and the total reflection portion. It is possible to design, and by forming the second incident surface as an inclined surface, the light incident on the second incident surface is incident on the total reflection portion, and the incident light is totally reflected. Since it is possible to totally reflect the light path toward the surface to be irradiated by the unit, it is possible to easily and surely obtain the desired light distribution characteristic and to sufficiently efficiently emit the light emitted from the light source. In addition, the productivity and the yield can be improved.

  The light flux controlling member according to claim 2 is characterized in that, in claim 1, the first incident surface, the second incident surface, and the total reflection portion are the light in the light incident on the incident portion. The angle with respect to the optical axis is set such that the first light incident on the first incident surface and the second light incident on the second incident surface intersect at least after total reflection by the total reflection portion. There is in point. According to the second aspect of the invention, since the spread around the optical axis of the second light totally reflected by the total reflection portion can be suppressed, the productivity and the yield can be improved. In addition, the utilization efficiency of light from the light source can be further improved.

  Further, the light beam control member according to claim 3 is characterized in that, in claim 2, the angle setting further comprises: the first light and the second light after the total reflection are parallel to the optical axis. The angle setting is such that it intersects with a virtual straight line in between. According to the third aspect of the present invention, the second light totally reflected by the total reflection portion can be irradiated to a region close to the irradiated range of the first light totally reflected by the total reflection portion. In addition, productivity and yield can be improved, and utilization efficiency of light from the light source can be further improved.

Furthermore, the light flux controlling member according to claim 4 is characterized in that, in claim 3, the first incident surface, the second incident surface, and the total reflection portion are defined by the following (1) and (2 ) (1) QL ₁ > QL ₂ , (2) | θ _1max | ≧ | θ _2max |, where QL _{1 is} the amount of the first light, and QL _{2 is} the amount of the second light. _{Amount of} light, θ _1max : Maximum value of acute angle θ _{1 made} by the first light after total reflection with the optical axis, θ _2max : Sharp angle θ _{2 made by} the second light after total reflection with the optical axis However, the maximum value of (which is different from θ ₁ ) is satisfied. According to the fourth aspect of the invention, the second light can be reliably prevented from becoming unnecessary light by further satisfying the conditional expressions (1) and (2). Further, the light distribution characteristics and the light utilization efficiency can be further improved.

  According to a fifth aspect of the present invention, there is provided the light beam control member according to the third or fourth aspect, wherein the angle setting further includes the first light and the second light after the total reflection on the virtual straight line. The angle setting is such that the axes intersect with each other in a line-symmetric state as a symmetry axis. According to the fifth aspect of the present invention, the second light totally reflected at an arbitrary position on the total reflection surface is shifted from the other position on the total reflection surface by 180 ° around the optical axis. Since it can be controlled to be in a state parallel to the first light totally reflected at the position, even better light distribution characteristics can be obtained.

  Furthermore, the light flux controlling member according to claim 6 is characterized in that, in any one of claims 1 to 5, the incident region is located on the light source side at an inner position in the radial direction than the plurality of protrusions. It is in the point which has the convex surface which faced. According to the sixth aspect of the present invention, since the light emitted from the light source and incident on the convex surface can be effectively converged by the convex surface, a light beam close to parallel light suitable as a light source for a projector or the like is emitted. The light can be emitted from the region.

  Furthermore, the optical device according to claim 7 is an optical device that irradiates the irradiated surface with light emitted from a light source, and is located at a position on the light emission side with respect to the light source. The light flux controlling member according to any one of the above is arranged in a state in which the incident area is directed toward the light source and the optical axis thereof is aligned with the central axis of the light emitted from the light source. . And according to this invention concerning Claim 7, a light distribution characteristic and light utilization efficiency can be improved, and productivity and a yield can be improved collectively.

  The optical device according to an eighth aspect is the optical device according to the seventh aspect, wherein the first incident surface and the second incident surface are each of the incident portions of the plurality of protrusions. A part of the incident part where light emitted from the light source at an angle of 30 to 60 ° with respect to the optical axis is incident is formed, and the other incident part is only a flat single incident surface. It is in the point formed by. According to the eighth aspect of the present invention, the LED as the light source can be obtained by disposing the protrusions having the first incident surface and the second incident surface at the position corresponding to the angle at which the amount of light emitted from the LED is large. It is possible to improve the light distribution characteristic and the light utilization efficiency when using the light source and to simplify the shape of the other protrusions.

  Further, the optical device according to claim 9 is characterized in that, in claim 8, the light beam control member arranged at a position on the light emission side with respect to the light source is in any one of claims 1 to 5. The predetermined number of the protrusions close to the optical axis among the plurality of protrusions is located at an inner position in the radial direction than the radial end portion of the light emitting surface of the light source. It is in the point where it is arranged. According to the ninth aspect of the present invention, it is possible to reliably obtain good light distribution characteristics and light utilization efficiency in a thin optical device in which the light source is disposed in the immediate vicinity of the light flux controlling member.

  Furthermore, the optical device according to claim 10 is characterized in that in claim 7 or 8, the light beam control member disposed at a position on the light emission side with respect to the light source is the light beam control according to claim 6. The radial end of the light emitting surface of the light source is formed at an inner position in the radial direction than the outer peripheral end of the convex surface. According to the invention of claim 10, since the light emitted from the light source can be efficiently incident on the convex surface, the convex surface can be effectively functioned and a desired light beam suitable for a projector or the like can be reliably obtained. Obtainable.

  ADVANTAGE OF THE INVENTION According to this invention, while being able to obtain the favorable light distribution characteristic as aimed simply and reliably by the design without a manufacturing effort, light utilization efficiency can be improved.

The front view which shows 1st Embodiment of the light beam control member which concerns on this invention Plan view of FIG. Bottom view of FIG. (A) is AA sectional drawing of FIG. 2, (b) is the elements on larger scale of (a). The principal part enlarged view which shows 1st Embodiment of the light beam control member which concerns on this invention. Explanatory drawing for demonstrating the crossing state of 1st light and 2nd light in 1st Embodiment of the light beam control member which concerns on this invention. Explanatory drawing for demonstrating a conditional expression in 1st Embodiment of the light beam control member which concerns on this invention The graph which shows a light distribution characteristic in 1st Embodiment of the light beam control member which concerns on this invention. The block diagram which shows 2nd Embodiment of the light beam control member which concerns on this invention. The graph which shows a light distribution characteristic in 2nd Embodiment of the light beam control member which concerns on this invention. The block diagram which shows the design example of the ideal light beam control member corresponding to 2nd Embodiment In 2nd Embodiment of the light beam control member which concerns on this invention, the block diagram which shows the light beam control member used as a comparative example FIG. 12 is a comparative diagram comparing the light distribution characteristics of the light flux controlling member of FIG. 12 and the light distribution characteristics of the light flux controlling member of the second embodiment when a sufficiently small light source is used. Configuration diagram showing a design example of an ideal luminous flux control member Enlarged view of the main part of an ideal luminous flux control member Explanatory drawing for demonstrating the reflection direction of the light in the total reflection surface of an ideal light beam control member Graph showing the light distribution characteristics of an ideal luminous flux control member Enlarged view of the main part showing the light flux controlling member in which molding failure has occurred due to insufficient filling of the resin material The graph which shows the light distribution characteristic of the light beam control member of FIG. Enlarged view of the main part showing a light flux control member whose design has been changed from its ideal shape. The graph which shows the light distribution characteristic of the light beam control member of FIG.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.

  Parts having the same or similar basic configuration as the conventional light flux controlling members 1, 1 ′, 1 ″ described in FIGS. 14 to 21 will be described using the same reference numerals.

  FIG. 1 is a front view showing a light flux controlling member 21 in the present embodiment. FIG. 2 is a plan view of FIG. Further, FIG. 3 is a bottom view of FIG. 4A is a cross-sectional view taken along line AA in FIG. 2, and FIG. 4B is a partially enlarged view of FIG. 4A.

  As shown in FIGS. 1 to 4, the light flux controlling member 21 in the present embodiment is configured by a circular light flux controlling portion 2 and a cylindrical edge portion 3 surrounding the light flux controlling portion 2 in a plan view. In addition, the light beam control unit 2 has the incident region 4 having the Fresnel shape and the emission region 5 facing this in the direction of the optical axis OA, similarly to the conventional light beam control members 1, 1 ′, 1 ″. It is.

  In addition, the light flux controlling member 21 in the present embodiment has a light source 6 (surface light source) having a predetermined divergence angle such as an LED at a position facing the incident region 4 in the direction of the optical axis OA, as in the conventional case. In an arranged state, the emitted light beam from the light source 6 is controlled to irradiate the irradiated surface.

  However, the light flux controlling member 21 in the present embodiment has a characteristic configuration that the plurality of protrusions 11 of the incident region 4 forming the Fresnel shape does not have.

  That is, as shown in FIG. 5, in the present embodiment, the protrusion 11 has an incident portion 24 and a total reflection surface 15 as a reflecting portion disposed at a radially outer position with respect to the incident portion 24. The incident portion 24 is composed of two incident surfaces 25 and 26, which are a first incident surface 25 and a second incident surface 26. The total reflection surface 15 is provided with the same reference numeral as in the past. However, the total reflection surface 15 may be formed at the same inclination angle (for example, 25 °) as in the past by setting the angle, which will be described later, or different from the conventional one. It may be formed at an inclination angle. Further, the height of the protrusion 11 can be formed to a height (for example, 0.18 mm) lower than the height (for example, 0.2 mm) of the conventional protrusion 11 shown in FIG.

  As shown in FIG. 5, the first incident surface 25 is a relatively wide area located on the irradiated surface side (upper side in FIG. 5) of the incident portion 24, and this first incident surface 25 is formed in the cylindrical surface centering on the optical axis OA. The first incident surface 25 is not limited to a cylindrical surface, and takes into consideration the incident angle and the refraction angle of light from the light source 6 on the first incident surface 25, and passes through the first incident surface 25 to give a total reflection surface. 15 may be formed on a tapered surface adjusted so that the light reflected by 15 irradiates an effective irradiation range.

  On the other hand, as shown in FIG. 5, the second incident surface 26 is a relatively narrow region located on the light source 6 side (lower side in FIG. 5) of the incident portion 24. The incident surface 26 is connected to the tip portions (lower end portions in FIG. 5) of both the first incident surface 25 and the total reflection surface 15. Further, the second incident surface 26 has a predetermined acute angle (for example, 17 °) outward in the radial direction with respect to the optical axis OA as it goes toward the light source 6 side where the tip of the protrusion 11 is cut away. It is formed in the inclined surface (taper surface) inclined so that it may have the following inclination angle.

  By forming the second incident surface 26 in this manner, the apex angle of the tip portion of the protrusion 11 is 42 ° (the inclination angle 25 ° of the total reflection surface 15 + the inclination angle 17 ° of the second incident surface 26). Thus, the protrusion 11 can have a larger apex angle than when the second incident surface 26 is not formed.

  That is, in addition to keeping the height of the protrusion 11 low, the apex angle of the protrusion 11 can be increased, so that the mold shape can be easily transferred during molding.

  Here, as shown in FIG. 5, adjacent lights of the light L emitted from the light source 6 are incident on the first incident surface 25 and the second incident surface 26 at different incident angles. It is supposed to be. The light incident on the first incident surface 25 (hereinafter referred to as first light) and the light incident on the second incident surface 26 (hereinafter referred to as second light) After being refracted at 26 according to Snell's law, the light passes through the optical path inside the protrusion 11 toward the total reflection surface 15. Thereafter, the first light and the second light are incident on the total reflection surface 15 at different incident angles (however, incident angles greater than the critical angle), and are then directed toward the emission region 5 by the total reflection surface 15. Total reflection is performed at different reflection angles.

Further, in the present embodiment, the first incident surface 25, the second incident surface 26 and the total reflection surface 15, as shown in FIG. 6, the first light L ₁ after total reflection by the total reflection surface 15 angle setting is made with respect to the optical axis OA, such as the second and the light L ₂ intersect. More specifically, this angle setting, the total reflection surface first after total reflection by 15 light L ₁ and the second light L ₂ parallel to the optical axis OA a virtual straight line VL (see Figure 6) The angle is set so as to intersect in a sandwiched state. More preferably, the angle is set such that the first light and the second light are intersected in a substantially line-symmetric state with the virtual straight line VL as the symmetry axis after total reflection by the total reflection surface 15. However, as described above angular setting, total reflection surface 15 and the first light L ₁ prior to total reflection by the second light L ₂ it is not intended to exclude the crossing.

Further, in the present embodiment, the first incident surface 25, the second incident surface 26, and the total reflection portion 15 satisfy the following conditional expressions (1) and (2).
QL ₁ > QL ₂ (1)
| Θ _1max | ≧ | θ _2max | (2)

However, QL ₁ is in (1), a first amount of light _{L 1,} QL ₂ is a second amount of light _{L 2.} In addition, as shown in FIG. 7, | θ _1max | in the expression (1) is the absolute value of the maximum value of the acute angle θ ₁ formed by the first light L ₁ after total reflection by the total reflection surface 15 and the optical axis OA. It is. Further, | θ _2max | in the expression (1) is the absolute value of the maximum value of the acute angle θ ₂ formed by the second light L ₂ after total reflection by the total reflection surface 15 and the optical axis OA as shown in FIG. It is. Note that θ ₁ has a negative sign when the clockwise direction in FIG. 7 is positive, and conversely θ ₂ has a positive sign.

  Here, when the expression (1) is not satisfied, the second incident surface 26 becomes too large in the optical axis direction, so that the second incident surface 26 is incident on the end of the irradiated surface side. 2 light is greatly diverged in the direction away from the optical axis OA after total reflection by the total reflection surface 15. Even when the expression (2) is not satisfied, the second light incident on the second incident surface 26 diverges greatly in the direction away from the optical axis OA after total reflection by the total reflection surface 15.

By thus (1) and to satisfy the conditional expression (2), the second light L ₂ is incident on the second incident surface 26 can be directed toward the illuminated surface without becoming unnecessary light.

According to the present embodiment configured as described above, the sharpness of the protrusion 11 is reduced by sandwiching the second incident surface 26 between the first incident surface 25 and the total reflection surface 15. It is possible to make a design that is reasonable in manufacturing, and by forming the second incident surface 26 as an inclined surface, the light incident on the second incident surface 26 is incident on the total reflection surface 15, The incident light can be totally reflected by the total reflection surface 15 onto the optical path toward the irradiated surface. Further, the second light L ₂ totally reflected at an arbitrary position on the total reflection surface 15 is totally reflected at another position on the total reflection surface 15 that is shifted from the position about the optical axis OA by 180 °. it is possible to control a state close parallel or to the first light L _1, it is possible to approximate the second of the irradiated range of the light L ₂ to the first of the irradiation range of the light L _1, though Light emitted by the conventional light flux controlling member 1 in which the second incident surface 26 shown in FIGS. 14 and 15 is not formed or light having a light distribution close thereto can be irradiated onto the irradiated surface. Furthermore, (1) and by satisfying the expression (2) can be the second light L ₂ is reliably prevented from becoming unnecessary light.

  As a result, good light distribution characteristics as intended (as designed) can be obtained easily and reliably, and the light emitted from the light source 6 can be used sufficiently efficiently. In addition, the yield can be improved.

  Specifically, according to the present embodiment, a decrease in the maximum value of the intensity of the emitted light from the light beam control member 21 is suppressed with respect to the conventional light beam control member 1 and is close to the target light distribution characteristic shown in FIG. Good light distribution characteristics can be obtained (see FIG. 8).

  In addition to the above-described configuration, the first incident surface 25 and the second incident surface 26 are further provided with respect to the optical axis OA from the light source 6 among the incident portions 24 formed on the plurality of protrusions 11. It is formed only on a part of incident parts 24 where light emitted at an angle of ˜60 ° is incident, and only a single flat incident surface 14 similar to FIG. 14 is formed on the other incident parts 11. Also good. If comprised in this way, since the emitted light from general LED has the light distribution characteristic of Lambert distribution, the 1st incident surface 25 and the 2nd incident will be in the position corresponding to the angle with many emitted light quantities from LED. By disposing the protrusion 11 having the surface 26, it is possible to improve the light distribution characteristics and the light utilization efficiency, and to simplify the shape of the other protrusions.

  In addition to the above-described configuration, the predetermined number of protrusions 11 near the optical axis OA among the plurality of protrusions 11 are arranged at a radially inner position than the radial end of the light emitting surface of the light source 6. May be. If comprised in this way, in the thin optical apparatus with which the light source 6 was arrange | positioned in the immediate vicinity of the light beam control member 21, a favorable light distribution characteristic and light utilization efficiency can be acquired reliably.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. 9 to 13 with a focus on differences from the first embodiment. Note that portions having the same or similar basic configuration as the first embodiment will be described using the same reference numerals.

  In the present embodiment, the light distribution characteristic such that the light beam is concentrated on the optical axis OA side (0 ° side) further than the target light distribution characteristic (see FIG. 17) in the first embodiment, that is, the first embodiment. The above-mentioned light distribution characteristic is narrower than the target light distribution characteristic, and the light distribution characteristic has a high peak intensity.

  And in order to implement | achieve such a light distribution characteristic peculiar to this embodiment, the structure of this embodiment has the following differences with respect to the structure of 1st Embodiment.

  That is, as shown in FIG. 9, the difference of the present embodiment from the first embodiment is that the shape of the radially inner portion with respect to each protrusion 11 in the incident region 4 (that is, the shape of the central portion 8) and The light emitting surface of the light source 6 has a relative size with respect to the central portion 8.

  Specifically, as shown in FIG. 9, the light flux controlling member 31 in the present embodiment is such that the central portion 8 is not on a plane orthogonal to the optical axis OA as in the first embodiment but toward the light source 6 side. It is formed on a convex surface (curved surface). Hereinafter, the central portion 8 in the present embodiment is referred to as a convex surface 8. The convex surface 8 may be, for example, a spherical lens surface concentric with the optical axis OA or an aspheric lens surface concentric with the optical axis OA.

  In the present embodiment, the radial end of the light emitting surface of the light source 6 is formed at a radially inner position than the outer peripheral end of the convex surface 8. This indicates that the light source 6 is sufficiently smaller than the light flux controlling member 31 as shown in FIG.

  Since the other configuration is basically the same as that of the first embodiment, the details will be given to the first embodiment.

  According to such a configuration of the present embodiment, as shown in FIG. 10, it is possible to reliably obtain the light distribution characteristics aimed at in the present embodiment. The light distribution characteristic shown in the figure is a preferable light distribution characteristic in an application such as a projector that is required to emit a light beam close to parallel light. Although the light source 6 in the present embodiment and the light source 6 in the conventional design example (FIG. 14) have the same light distribution characteristics, the intensities are different, so the intensity [cd] in the light distribution characteristic graph of FIG. It is meaningless to compare the intensity in the light distribution characteristic graph of FIG.

  By the way, such a light distribution characteristic of FIG. 10 includes a light beam control member 31 ′ having a sharp projection 11 as shown in FIG. 11 and a light source 6 that is sufficiently small with respect to the light beam control member 31 ′. It can be realized by using it. However, the light flux controlling member 31 ′ having such a sharp protrusion 11 can be realized by design for the same reason as the ideal light flux controlling member 1 in the first embodiment. It is extremely difficult to manufacture by resin molding using a mold. Therefore, an advanced molding technique is required to obtain the light distribution characteristics shown in FIG. 10 using such a light flux controlling member 31 ′ and the light source 6.

  Further, the light distribution characteristics of the light beam control member 31 ″ shown in FIG. 12 and the light beam control member 31 in the present embodiment are compared in the case where the light source 6 that is sufficiently smaller than the light beam control members 31 ″ and 31 is used. Then, it becomes what is shown to Fig.13 (a) and (b). In addition, the horizontal axis in the figure shows the spread angle [°] to the left and right (±) with the optical axis OA direction as the center (0 °), and the vertical axis in the figure shows a predetermined luminous intensity. Relative luminous intensity [%] as a reference (100%) is shown. FIG. 13B shows the light distribution characteristics on the narrow-angle side (optical axis OA side) in FIG. Here, the light distribution characteristics of the light flux controlling member 31 having the convex surface 8 shown in FIG. 9 are shown by black circles (●) in FIGS. 13A and 13B. The peak intensity of the light flux controlling member 31 is approximately equal to the peak intensity of the light flux controlling member 31 ″ in which the central portion 8 shown by the triangle (Δ) plots in FIGS. 13A and 13B is formed as a plane. Thus, by forming the central portion 8 as a convex surface, the peak intensity can be improved while maintaining a narrow light distribution characteristic.

  In the present embodiment, the example in which the light source 6 having a 1.0 mm square is combined with the light flux controlling member 31 ″ whose planar shape of the central portion 8 is a circle having a radius of 0.55 mm is shown. For example, when a 0.3 mm square light source 6 is used, the central portion 8 is convex as compared to the case where the central portion 8 is a flat surface. In some cases, the peak intensity can be improved by about 10% while maintaining a narrow light distribution characteristic.

  Therefore, in this embodiment as well, as in the first embodiment, by forming the two incident surfaces 25 and 26 on each of the protrusions 11, it is possible to easily achieve a narrow light distribution characteristic that is aimed at. Furthermore, the peak intensity can be improved by making the central portion 8 convex.

  In addition, this invention is not limited to embodiment mentioned above, A various change can be made in the limit which does not impair the characteristic of this invention.

  For example, the light flux controlling member 21 in the present embodiment can be effectively applied to spot illumination, for example, illumination of a show window or illumination (flash) for an imaging camera mounted on a mobile phone.

4 Incident area 5 Emission area 11 Projection 15 Total reflection surface 25 First incident surface 26 Second incident surface

Claims (10)

An incident region where light emitted from the light source is incident;
A light beam control member having an emission region facing the incident region in the optical axis direction and emitting the light incident on the incident region toward the irradiated surface,
The incident region has a plurality of protrusions adjacent to each other in the radial direction such that the shape viewed from the optical axis direction has a concentric annular shape centering on the optical axis and the cross-sectional shape is sawtooth-shaped,
The protrusion is formed with an incident portion where light emitted from the light source is incident and refracts the incident light, and an outer position in the radial direction with respect to the incident portion with respect to the optical axis. A total reflection part that totally reflects light incident from the incident part toward the emission region;
The incident portion includes a first incident surface having a relatively wide range located on the irradiated surface side, and the light source side connected to both the first incident surface and the total reflection portion. A second incident surface consisting of a relatively narrow region located,
The second incident surface is formed on an inclined surface that is inclined outward in the radial direction with respect to the optical axis as it goes toward the light source such that a tip portion of the protrusion is cut out. A light flux controlling member characterized by the above. The first incident surface, the second incident surface, and the total reflection portion are incident on the first light and the second incident surface that are incident on the first incident surface in the light incident on the incident portion. 2. The light flux controlling member according to claim 1, wherein an angle is set with respect to the optical axis so that the second light intersects at least after total reflection by the total reflection portion. The angle setting is an angle setting such that the first light after the total reflection and the second light intersect with each other with a virtual straight line parallel to the optical axis interposed therebetween. Item 3. The light flux controlling member according to Item 2. The first incident surface, the second incident surface, and the total reflection portion are expressed by the following conditional expressions (1) and (2):
QL ₁ > QL ₂ (1)
| Θ _1max | ≧ | θ _2max | (2)
However,
QL _1: said first amount of light QL _2: the second light quantity theta _1max: the maximum value of the acute angle theta ₁ which the first light after the total reflection makes with the optical axis theta _2max: the total 4. The light flux controlling member according to claim 3, wherein the second light after reflection satisfies a maximum value of an acute angle θ ₂ (which is different from θ ₁ ) formed by the optical axis. 5. The angle setting is an angle setting that intersects the first light and the second light after the total reflection in a line-symmetric state with the virtual straight line as an axis of symmetry. 5. The light flux controlling member according to 3 or 4. 6. The light flux controlling member according to claim 1, wherein the incident region has a convex surface facing the light source side at an inner position in the radial direction than the plurality of protrusions. . An optical device for irradiating a surface to be irradiated with light emitted from a light source,
The light flux controlling member according to any one of claims 1 to 6 directs its incident area toward the light source and emits its optical axis from the light source at a position on the light emitting side with respect to the light source. An optical device, wherein the optical device is arranged in alignment with the central axis of light. The first incident surface and the second incident surface are light emitted from the light source at an angle of 30 to 60 degrees with respect to the optical axis, of the incident portions of the plurality of protrusions. Forms a part of the incident part on which is incident,
The optical device according to claim 7, wherein the other incident portions are formed by only a single flat incident surface. The light flux controlling member arranged at a position on the light emission side with respect to the light source is the light flux controlling member according to any one of claims 1 to 5,
The predetermined number of the protrusions close to the optical axis among the plurality of protrusions is arranged at an inner position in the radial direction than an end portion in the radial direction on the light emitting surface of the light source. The optical device according to claim 8. The light flux controlling member disposed at a position on the light emission side with respect to the light source is the light flux controlling member according to claim 6,
The optical device according to claim 7, wherein an end portion in the radial direction of the light emitting surface of the light source is formed at an inner position in the radial direction with respect to an outer peripheral end portion of the convex surface.