JP2014130212A - Optical element and luminaire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical element that can achieve a narrow light distribution angle, and hardly causes color unevenness and color coding even if it is applied to a light source including a light emission surface (light emission section) having a size, and to provide a luminaire using the optical element.SOLUTION: The coordinates of any two points mutually shifted in the optical axis direction on a C incident side surface of a recess are denoted with P1(Px1,Pz1), P2(Px2,Pz2), and satisfy the following equation Px1<Px2 (1), Pz1>Pz2 (2), and α1>α2 (3). Here, the optical axis is set as the Z-axis having a positive direction from the incident surface to the outgoing surface, and the axis orthogonal to the optical axis is set as the X-axis having a positive direction separating from the optical axis. The angle between the optical axis and the normal line that passes the point P1 and is perpendicular to the incident side surface is denoted with α1(°), and the angle between the optical axis and the normal line that passes the point P2 and is perpendicular to the incident side surface is denoted with α2(°).

Description

  The present invention relates to an optical element and an illuminating device, and more particularly to an illuminating device having high directivity such as a downlight and a spotlight and an optical element used therefor.

  When illuminating a surface to be irradiated by controlling a light beam emitted from a light source, an optical element such as a lens or a mirror is often used. Such an optical element has a function of controlling light from a light source and generating a light beam suitable for the purpose. For example, light from a light source having a light distribution close to Lambertian, such as an LED, is difficult to handle as illumination as it is, and is used for spreading or narrowing by transmitting through an optical element.

  Here, an optical element having both a refraction action and a total reflection action disclosed in Patent Documents 1 and 2 and the like is often used when a light collecting action is given as an application of a downlight or the like. In particular, by using an optical element having a total reflection surface, it is easy to manufacture and the cost is low, and it becomes easy to align the angles of light beams without loss of light quantity. However, when the near-field luminance distribution of the light source has color unevenness, particularly when the light emitting surface (light emitting portion) of the light source has a certain size and cannot be regarded as a point light source, as described above. When an optical element having a light condensing function is used, there is a problem that an image of a light source is formed on the irradiated surface. In general, the above phenomenon occurs when the optical surface of the optical element on which light is incident first is set within a range of 5 L from the light source (light emitting portion) with respect to the maximum dimension L of the light source. Is likely to occur. When such a light source has color unevenness, a multicolor light source, or a pseudo-white light source due to the excitation action of a phosphor, color unevenness or color separation occurs on the irradiated surface. It is clear that when a human observes it with dark eyes, it will stand out. Naturally, such color unevenness and color separation are not desirable in actual use. In the present specification, “color unevenness” refers to images of light sources of different colors formed on the surface to be irradiated, and generally refers to those generated around the optical axis. Further, “color separation” refers to a state where color mixture is insufficient on the surface to be irradiated, and is generally likely to occur at the periphery of illumination light. In particular, the color separation is likely to occur in a dark area of the periphery of the illumination light, and thus has a feature that it is easily noticeable.

Japanese Patent No. 4993434 Japanese Patent No. 4179176 Japanese Patent No. 5030938 JP 2009-266523 A

  Incidentally, there is a technical idea that color unevenness is reduced by providing a structure having an action of scattering and diffusing light rays on the optical surface of an optical element. As such a structure, for example, the optical surface may be roughened or textured, or an array shape in which the same shape is two-dimensionally arranged may be considered. In particular, in an optical element having the above-described function, it is possible to prevent the image of the light source from being formed on the irradiated surface by providing such a structure on the emitting surface.

  However, in illumination devices such as downlights and spotlights, it is necessary to narrow the light distribution angle in order to increase the directivity of the emitted light. Therefore, the luminous flux emitted from the optical element is controlled by controlling the luminous flux from the light source. If the light intensity distribution (light distribution distribution) of the optical element is made narrower, even if a structure having the function of scattering and diffusing light rays is provided on the optical surface of the optical element, color separation of the spot periphery on the irradiated surface ( There arises a problem that color separation occurs. In particular, there has been a case where a spot illumination device using a light source of a plurality of colors, which has not been implemented in the past, is desired even in a lighting device with a narrow light distribution angle such as a spot illumination device. There is a case where a color is emitted to create one color (specifically, pseudo white using a plurality of colors). In such a case, it has been found that the problem of color separation at the periphery of a single color spot of one light source becomes more prominent. The reason why such a phenomenon occurs is as follows. In the case of a single color spot of one light source as in the prior art, even if the light deviates from the central portion on the non-irradiated surface, there is no color unevenness because there is one color. However, when a single color is produced by simultaneously emitting a plurality of colors, a plurality of colors are mixed at the center, and one color (for example, pseudo white) is irradiated onto the non-irradiated surface, so that the desired color can be illuminated. However, there is a case where the light does not mix like the center of a part of the light that falls on the non-irradiated surface far from the optical axis, and the desired color (for example, pseudo white) may not be obtained. In such a case, the central color and the peripheral color are different, and color unevenness (color separation) is likely to occur. Furthermore, color separation tends to be more prominent as the light distribution is narrower and the light emitting part of the light source has an area.

  On the other hand, Patent Document 3 discloses that color unevenness can be suppressed by providing a convex portion on the incident side surface, but the light distribution angle is determined by the total reflection surface. In this configuration, no measures are taken against the totally reflected light beam, so it is difficult to say that a narrow-angle light distribution without color unevenness (light source image) can be obtained. . Further, no means for preventing color separation is disclosed.

  On the other hand, Patent Document 4 discloses a technical idea of countermeasures against color unevenness using an optical surface having a diffusing function. However, with this technology alone, only the light rays that are totally reflected and the light rays that are not reflected can be separated. It cannot be said that it is difficult to prevent color separation that occurs at the periphery of the spot due to the total reflected light.

  The present invention has been made in view of such problems of the prior art, and even when applied to a light source capable of realizing a narrow light distribution angle and having a light emitting surface (light emitting portion) having a size, color unevenness and color It is an object of the present invention to provide an optical element that hardly causes separation and an illumination device using the optical element.

The optical element according to claim 1 is an optical element for illuminating an irradiated surface by transmitting light emitted from a light source,
An incident surface having an incident bottom surface and an incident side surface; a side surface that totally reflects incident light incident from the incident surface; and an exit surface that emits light toward the irradiated surface;
When a cross section passing through the optical axis of the optical element is taken, the coordinates of any two points on the incident side surface are P1 (Px1, Pz1) and P2 (Px2, Pz2), and at least one P1 that satisfies the following expression: , P2 exists.
Px1 <Px2 (1)
Pz1> Pz2 (2)
α1> α2 (3)
However, the optical axis is the Z-axis with the positive direction from the incident surface toward the exit surface, the axis orthogonal to the optical axis is the X-axis with the direction away from the optical axis as the positive direction, and passes through the incident point P1 The angle formed between the normal line perpendicular to the side surface and the optical axis is α1 (°), and the angle formed between the normal line perpendicular to the incident side surface and the optical axis is α2 (°).

  FIG. 1 is a diagram for explaining the principle of the present invention. FIG. 1 shows a part of the light source LS and the optical element OE in a cross section passing through the optical axis OA. As for the incident surface, the coordinates of two arbitrary points on the incident side surface C are represented by P1 ( When Px1, Pz1) and P2 (Px2, Pz2), the points P1 and P2 satisfy Px1 <Px2, Pz1> Pz2. The optical axis OA here is an axis passing through the center of the optical element OE. However, the optical axis OA is defined as a Z axis having a plus direction from the incident surface toward the exit surface, and an axis orthogonal to the optical axis is defined as an X axis having a direction away from the optical axis as a plus direction.

  Furthermore, the angle between the optical axis and the normal line NL1 perpendicular to the incident side surface of the concave portion C through the point P1 is α1 (°), and the normal line NL2 perpendicular to the incident side surface of the concave portion C through the point P2 and the optical axis. When the formed angle is α2 (°), α1> α2 is satisfied. It is more preferable that 0.85 ≦ α2 / α1 <1 is satisfied.

  Here, when the light source LS is not regarded as a point light source and has a light emitting surface (light emitting portion) having a certain area, the light beam LB1 emitted from the center of the light source LS and the most distant from the center of the light source LS. The incident position (P3, P4) on the incident surface is different from the light beam LB2 emitted from the place even if the light exit angle β is the same. Even at the same incident position, even if the side surface is formed of a complete paraboloid, the position where the light reaches the irradiated surface is different after being totally reflected.

  Assuming that the incident side surface of the concave portion C is represented by a single straight line, the distance from the periphery of the light emitting portion RP of the light source LS is larger than the distance from the center of the light emitting portion RP of the light source LS to the incident side surface of the concave portion C. The distance to the incident side surface of the recess C is shorter. Therefore, the light rays from the emission position far from the center of the light emission part RP are more likely to pass through the entrance side of the recess, but this tendency tends to occur when the light emission part RP has a certain area. Become stronger. In addition, since the light beam emitted from the vicinity of the optical axis and the light beam emitted from a position away from the optical axis are refracted with the same refraction angle when entering the recess C, they are orthogonal to the optical axis. The light emission point position deviation in the direction to be the same is the light collection point position deviation on the irradiated surface, and after being totally reflected by the side surface of the optical element, the emitted light close to the optical axis is directed inward (optical axis center side), The outgoing light far from the optical axis tends to be directed outward (side away from the optical axis). Color separation is caused by a group of light beams with uniform angles after exiting the optical element. In addition, the refraction angle said here is a refraction angle in the incident side with respect to the light ray radiate | emitted at the same angle from the light emission part.

  In particular, optical elements for lighting devices with a very narrow far-field light distribution, such as spotlights and downlights (strong directivity), have the above-mentioned characteristics, and near the optical axis on the irradiated surface. However, as the distance from the optical axis increases, the illuminance decreases rapidly. Therefore, the illuminance is lower and darker at the periphery of the spot, and the color separation becomes conspicuous. That is, the color separation becomes conspicuous because the group of light beams emitted from a place away from the center of the light source reaches a place away from the optical axis on the irradiated surface. In general, since an LED light source has a Lambertian emission characteristic, even if a light beam is emitted from a location away from the center of the light source, the intensity does not become weak depending on the emission angle, so that color separation becomes more conspicuous. Such a problem does not change even if the diffusing action is weak even if the emitting surface has a diffusing action.

  More specifically, based on the drawings, for example, in FIG. 31A showing a cross section of a surface-emitting light source LS and a reflecting surface MR of a radial optical element symmetrical to the optical axis, the center O of the light source LS is shown. The light reflected by the reflecting surface MR out of the group of rays emitted from the light exits in a concentrated manner (along the optical axis OA) as it is, but has a distance in a direction orthogonal to the optical axis. From the GP, a group of light rays (solid line) inclined in the direction (direction A) having the distance is emitted, and after being reflected by the reflecting surface MR, they are concentrated in a direction away from the optical axis. In this way, light rays having substantially the same angle are concentrated on a portion where the illuminance is weak, so that when a plurality of colors are emitted at the same time, color separation becomes particularly conspicuous.

  The present inventor who paid attention to this point has repeated research on whether or not color separation can be suppressed by making some contrivance on the entrance side of the concave portion through which the light beam passes in an optical element having a very narrow light distribution in the far field. . Then, as shown in FIG. 1, it has been found that color separation can be suppressed by satisfying Px1 <Px2, Pz1> Pz2, and α1> α2. More specifically, if Px1 <Px2, Pz1> Pz2, and α1> α2 are satisfied, the angle of the light beam emitted from a certain point of the optical element can be dispersed, and the distance from the light source center can be increased. First, a part of the light ray group that has exited from the spot is incident on the entrance-side surface having a relatively large inclination angle with respect to the optical axis for a part of the light ray group that reaches the incident side surface of the concave portion C on the closer side. When the angle is reduced and combined with total reflection on the side surface, the light distribution characteristic is such that the distance from the optical axis is further away on the irradiated surface. Further, a part of the light beam that reaches the incident side surface of the concave portion C on the farther side on the opposite side is incident on the surface on the entrance side having a relatively large inclination angle with respect to the optical axis. By combining the total reflection on the side surface, the light distribution characteristic becomes closer to the optical axis on the irradiated surface. That is, by combining these effects, it is possible to scatter a group of light rays that reach a place (spot edge) away from the optical axis, which tends to be concentrated, and to suppress color separation. Here, the side surface that totally reflects the incident light incident from the incident surface does not totally reflect all the light rays incident from the incident surface. Mainly, it has the effect of totally reflecting most of the light beam that has passed through the incident side surface of the recess C (for example, 90% or more of the incident light that has passed through the incident side surface of the recess C).

  More specifically, based on the drawings, as shown in FIG. 31 (b), the angle of a part of the light beam emitted from the point GP having a distance in the direction orthogonal to the optical axis OA is expressed by some means. The angle of the light beam group is not aligned and the color separation is suppressed. As a means for changing the angle of a part of the light beam, the present inventor reduces the refraction angle on the entrance side of the concave portion C of the incident surface of the optical element so that the light beam emitted in the direction (direction A) having the distance. Found that light rays emitted outward (in the direction away from the optical axis) and emitted in the opposite direction tend to change in angle toward the optical axis. The above is the effect of the present invention.

  The optical element according to claim 2 is characterized in that, in the invention according to claim 1, a diffusion surface is provided on the exit surface.

  By providing a diffusing surface on the emitting surface, it is possible to give scattering and diffusing action to the light emitted from the emitting surface side, thereby preventing the image of the light source from being projected onto the irradiated surface. Color unevenness can be suppressed.

  According to a third aspect of the present invention, there is provided the optical element according to the second aspect of the present invention, wherein the diffusing surface is formed by arranging minute uneven shapes in an array.

  When the diffusing surface is formed by arranging minute irregularities in an array, a higher scattering / diffusing action can be obtained. It is preferable that a shape composed of a part of a spherical surface (referred to as a concavo-convex unit) as a fine concavo-convex shape is arranged with a rule overlapping two-dimensionally. The larger the radius of curvature of the spherical surface, the smaller the light diffusion effect, and the smaller the curvature radius, the greater the diffusion effect. However, if it is too small, there is a limit because light is totally reflected on the surface and returned. As shown in FIG. 2 (a), the concavo-convex units arranged in an array form are two-dimensionally composed of a row A linearly arranged at equal intervals and a row B arranged at equal intervals with a certain angle. Has a spread. When the column crossing angle δ is 60 degrees, the lines are neatly aligned. However, by making the column crossing angle δ smaller than 60 degrees, the light distribution angle of the light beam can be narrowed. However, if it is too narrow, the peak shifts from the center, and color unevenness occurs, so δ = 40 to 90 degrees is desirable. The array-shaped uneven shape does not need to be formed in the entire range of the exit surface, and may be formed in a range that covers the effective diameter of the side surface.

  The intervals between the concavo-convex units arranged in an array may not be too far or too close. When the shape of the concavo-convex unit is a spherical surface, the height AH of the concavo-convex unit needs to be 20 μm or more in FIG. 2B, although it depends on the radius of curvature and the column crossing angle. The row interval AD may be determined so as to satisfy this value, but it is naturally undesirable that the overlap between the curved surfaces adjacent in all directions is larger than the effective diameter of the spherical surface forming the concavo-convex unit. The shape of the concavo-convex unit is a spherical surface here, but may be any concavo-convex shape. For example, an elliptic curve, a hyperbola, a parabola, or a sine curve may be rotated.

  An optical element according to a fourth aspect is the invention according to any one of the first to third aspects, wherein a surface-emitting light source is disposed so as to face the incident surface.

When a surface-emitting light source is used as the light source, the effects of the optical element of the present invention can be further exhibited. The surface emitting light source here refers to a light source having a light emitting portion of 0.25 mm ² or more. When the light source has a plurality of light emitting parts (RGBW), the area of the light emitting part means the area of a rectangular region TR circumscribing each light emitting part, as shown in FIG. The center of the region TR circumscribing the light emitting portion is used. As an example of the surface emitting light source, there is a light emitting area in the near field such as an LED (Light Emitting Diode) having a finite area instead of a point. The surface-emitting light source includes, for example, an LED chip that emits light having a peak wavelength in a blue wavelength region, and a phosphor that is excited by the light emitted from the LED chip and converts the wavelength into light of a yellow or yellow-green color tone. Examples include white LEDs.

  According to a fifth aspect of the present invention, there is provided the optical element according to the fourth aspect of the invention, wherein the surface-emitting light source has light emitting portions of different colors that simultaneously emit two or more colors.

  For example, a light source with R (red) G (green) B (blue) light emitting surface (light emitting part), or R (red) G (green) B (blue) W (white) light emitting surface (light emitting part) When a light source having a light source is used and light is emitted at the same time, light that does not mix well may be generated because one color is selected from a plurality of colors. In such a case, color unevenness and color separation are particularly likely to occur, but color unevenness and color separation can be effectively suppressed by using the optical element of the present invention. Examples of such a light source having light emitting portions of different colors include OSRAM SOST series LEATBS2W and LERTDUW (product name).

  When the optical element of Claim 6 takes the cross section which passes along the optical axis of the said optical element in the invention in any one of Claims 1-5, the incident side surface of the said recessed part is represented by several straight lines. It is characterized by that.

  By forming the incident side surface of the concave portion from two or more straight lines, it is possible to scatter the light rays reaching the spot periphery and reduce color separation. When the incident side surface of the recess is formed by a single straight line, the light beam that passes through the incident side surface of the recess is totally reflected from the side surface of the optical element and then emitted in a state where the angles are substantially uniform from the emission surface. . Therefore, in the case of a light source in which the light emitting surface (light emitting portion) has a size and a plurality of colors are separated by near-field distribution, the color separation becomes conspicuous even on the irradiated surface. By forming the incident side surface of the concave portion from two or more straight lines having different angles, for example, a group of light beams incident on the respective straight lines pass through the respective straight lines and are emitted from the optical element, and then the light beam angles are aligned. The angle can be different from the angle, whereby the group of rays reaching the place away from the optical axis is scattered on the irradiated surface, and the color separation formed at the place away from the optical axis can be prevented. Also, depending on the shape of the side surface of the optical element, in the case of a light source having a large light emitting part, the emission point position is intentionally shifted from the focal point of the paraboloid forming the side surface, and from other than on the optical axis. By adjusting the distribution of the emitted light, the light distribution angle can be narrowed when viewed over the entire light emitting surface (light emitting portion). When two or more straight lines are provided, it is preferable that the smaller angle with respect to the optical axis is formed on the upper surface side of the recess and the larger angle with respect to the optical axis is formed on the entrance side.

  The optical element according to claim 7 is the invention according to claim 6, wherein at least one of the intersections of the plurality of straight lines is from the entrance of the recess when the depth of the recess is 1. It is in the position of 7/10 or less.

  In the example of FIG. 1, the intersection CP of the straight lines L <b> 1 and L <b> 2 is at a position 7/10 or less from the entrance of the recess C. By setting the intersection point CP of the two straight lines to 7/10 or less from the entrance of the recess C, it is possible to effectively reduce the color unevenness. The depth of the recess means the distance from the entrance end to the bottom of the recess (d in FIG. 1). The position of the intersection CP (referred to as a CP ratio in the embodiments described later) is more preferably 0.2 or more and 1/2 or less. If the entrance of the concave portion is not clear, the intersection point where the straight line on the entrance side of the concave portion and the tangent of the bottom surface around the concave portion perpendicular to the optical axis of the optical element intersect in the cross section in the optical axis direction of the optical element is the entrance. Measure the length in the depth direction.

  An optical element according to an eighth aspect of the present invention is the optical element according to the sixth aspect or the seventh aspect, wherein an intersection of any two straight lines forming the incident side surface of the concave portion is a light emitting portion of the light source and the light of the optical element. It is characterized by being within 30 to 70 degrees with respect to the optical axis with reference to the intersection with the axis.

  In the example of FIG. 1, when the intersection of the optical axis OA and the light emitting part RP of the light source LS is defined as O, the angle γ between the line segment connecting the point O and the point CP and the optical axis OA is 30. Means ~ 70 degrees. If the angle γ is within this range, color unevenness and color separation can be effectively reduced. The angle γ is more preferably within 30 to 65 degrees.

  The optical element according to claim 9 is the invention according to any one of claims 6 to 8, wherein an angle formed by any straight line forming the incident side surface of the recess with the optical axis of the optical element is 3 to 3 It is characterized by 10 degrees.

  In the example of FIG. 1, it means that the angle θ formed by at least one of the straight lines L1 and L2 (here, L1) constituting the incident side surface of the recess C and the optical axis OA is 3 to 10 degrees. If the straight line constituting the incident side surface of the recess C is within this angular range, the light distribution angle can be narrowed by guiding the light beam that has passed through the incident side surface of the recess to the side surface of the optical element and totally reflecting it. In particular, the vicinity of the bottom of the recess or a straight line extending from the vicinity of the bottom of the recess (L1 in this case) is preferably within the above angle range.

  An optical element according to a tenth aspect is characterized in that, in the invention according to any one of the first to fifth aspects, when the cross section passing through the optical axis of the optical element is taken, the incident side surface of the concave portion is a curve. And

  If the incident side surface is formed by a plurality of straight lines in the cross section passing through the optical axis, the refraction angle changes suddenly. Therefore, the incident side surface has a higher effect of suppressing color separation than the case where the incident side surface is formed by a smooth curve, and is more desirable. . However, even when the incident side surface of the concave portion is not a single straight line but a curved line, a certain degree of color separation can be reduced. When a cross section passing through the optical axis of the optical element is taken, a line segment connecting the point O with a point at which the double differential value in the curve constituting the incident side surface of the recess becomes an extreme value (maximum), and the optical axis OA, Is more preferably 30 to 65 degrees.

  An optical element according to an eleventh aspect is characterized in that, in the invention according to any one of the first to tenth aspects, a side surface of the optical element has a shape based on a paraboloid.

By making the shape of the side surface based on a parabolic surface (similar to a parabolic surface), the light distribution angle of the light beam that has passed through the optical element is narrowed, and the irradiated surface is locally illuminated. It becomes possible. The term “surface having a shape based on a paraboloid” here means that k satisfies the following range when the shape of a rotationally symmetric side surface is fitted with a radius of curvature R and a conic coefficient k.
−1.2 ≦ k ≦ −0.9
However, it is more preferable that the conic coefficient is smaller than -1.

  When the side surface has a shape based on a paraboloid, it is preferable that a light source is placed near the focal position of the paraboloid. Here, the vicinity of the focal position means that it is within √S from the focal position, where S is the area of the light emitting portion (see FIG. 2). When the side surface has a shape based on a paraboloid, it is preferable that the light emitting portion of the light source is closer to the optical element than the focal position of the paraboloid.

  An optical element according to a twelfth aspect is characterized in that, in the invention according to any one of the first to eleventh aspects, a flange portion is formed in a peripheral portion of the optical element.

  Since the optical element includes the flange portion, the gate can be provided here to fill the resin, so that the moldability is improved, and the use of the flange portion facilitates installation to other parts.

  According to a thirteenth aspect of the present invention, in the invention according to any one of the first to twelfth aspects, the optical element is made of a resin.

  By making the optical element made of resin, mass production by injection molding or the like becomes possible.

  The illuminating device of Claim 14 has the optical element in any one of Claims 1-13, and a light source, It is characterized by the above-mentioned.

  The effective diameter of the exit surface of the optical element is preferably within 35 mm. The height of the optical element is preferably 25 mm or less. In general, the light beams that pass through the upper surface side of the recess are more easily aligned, and the light beams that pass through the entrance side of the recess are more difficult to align. The light distribution angle of the light emitted from this optical element is preferably 10 degrees or less (more preferably 8 degrees or less) in terms of full width at half maximum (angle).

  The radius of the incident side surface (distance from the optical axis) is preferably monotonously increased with respect to the distance from the bottom of the recess. Further, it is preferable that the incident side surface does not have a portion having a primary differential value of 0 (surface inclination is 0) (no flat portion). Of course, it is preferable that there is no extreme value.

  According to the present invention, an optical element capable of realizing a narrow light distribution angle and hardly causing color unevenness and color separation even when applied to a light source having a light emitting surface (light emitting portion) having a size, and an illumination device using the same Can be provided.

It is a figure which shows typically a light source and the recessed part of an entrance plane. (A) is the figure which looked at the uneven | corrugated shape arranged in the array form in the optical axis direction, (b) is the figure seen in the optical axis orthogonal direction. It is the figure which looked at the light source from the light emission surface (light-emitting part) side. It is the figure which looked at the illuminating device concerning this Embodiment from the output surface side. It is the figure which cut | disconnected the structure of FIG. 4 by the VV line and looked at the arrow direction. (A) is a figure which shows the optical path of the light ray which radiate | emits from the illuminating device of this Embodiment, and reaches to a to-be-irradiated surface, (b) is a figure which shows the optical path of the light ray which passes an optical element from a light source. . It is a graph which shows the relationship between the intersection angle of the uneven | corrugated shape arranged in the array form, and a light distribution angle. 1 is a cross-sectional view of an optical element of Example 1. FIG. 6 is a cross-sectional view of an optical element according to Example 2. FIG. 6 is a cross-sectional view of an optical element according to Example 3. FIG. 6 is a sectional view of an optical element according to Example 4. FIG. 10 is a cross-sectional view of an optical element according to Example 5. FIG. 10 is a cross-sectional view of an optical element according to Example 6. FIG. 10 is a sectional view of an optical element according to Example 7. FIG. 10 is a sectional view of an optical element according to Example 8. FIG. It is sectional drawing of the optical element of the comparative examples 1 and 2. FIG. 10 is a cross-sectional view of an optical element of Comparative Example 3. FIG. (A) shows the relationship between the x value in the CIE color system in the EW cross section of FIG. 4 and the irradiated surface position, and (b) shows the CIE table in the EW cross section of FIG. It is a graph which shows the relationship between y value in a color system, and a to-be-irradiated surface position, and compares and shows Example 1 and Comparative Examples 1-3. (A) shows the relationship between the x value in the CIE color system in the NS cross section of FIG. 4 and the irradiated surface position, and (b) shows the CIE table in the NS cross section of FIG. It is a graph which shows the relationship between y value in a color system, and a to-be-irradiated surface position, and compares and shows Example 1 and Comparative Examples 1-3. (A) shows the relationship between the x value in the CIE color system in the NE-SW direction cross section of FIG. 4 and the irradiated surface position, and (b) shows the CIE table in the NE-SW direction cross section of FIG. It is a graph which shows the relationship between y value in a color system, and a to-be-irradiated surface position, and compares and shows Example 1 and Comparative Examples 1-3. (A) shows the relationship between the x value in the CIE color system in the NW-SE direction cross section of FIG. 4 and the irradiated surface position, and (b) shows the CIE table in the NW-SE direction cross section of FIG. It is a graph which shows the relationship between y value in a color system, and a to-be-irradiated surface position, and compares and shows Example 1 and Comparative Examples 1-3. (A) shows the relationship between the x value in the CIE color system in the EW cross section of FIG. 4 and the irradiated surface position, and (b) shows the CIE table in the EW cross section of FIG. It is a graph which shows the relationship between y value in a color system, and to-be-irradiated surface position, and shows Examples 1-3 by comparison. (A) shows the relationship between the x value in the CIE color system in the NS cross section of FIG. 4 and the irradiated surface position, and (b) shows the CIE table in the NS cross section of FIG. It is a graph which shows the relationship between y value in a color system, and to-be-irradiated surface position, and shows Examples 1-3 by comparison. (A) shows the relationship between the x value in the CIE color system in the NE-SW direction cross section of FIG. 4 and the irradiated surface position, and (b) shows the CIE table in the NE-SW direction cross section of FIG. It is a graph which shows the relationship between y value in a color system, and to-be-irradiated surface position, and shows Examples 1-3 by comparison. (A) shows the relationship between the x value in the CIE color system in the NW-SE direction cross section of FIG. 4 and the irradiated surface position, and (b) shows the CIE table in the NW-SE direction cross section of FIG. It is a graph which shows the relationship between y value in a color system, and to-be-irradiated surface position, and shows Examples 1-3 by comparison. (A) shows the relationship between the x value in the CIE color system in the EW cross section of FIG. 4 and the irradiated surface position, and (b) shows the CIE table in the EW cross section of FIG. It is a graph which shows the relationship between y value in a color system, and a to-be-irradiated surface position, and shows Example 1 and 6-8 in comparison. (A) shows the relationship between the x value in the CIE color system in the NS cross section of FIG. 4 and the irradiated surface position, and (b) shows the CIE table in the NS cross section of FIG. It is a graph which shows the relationship between y value in a color system, and a to-be-irradiated surface position, and shows Example 1 and 6-8 in comparison. (A) shows the relationship between the x value in the CIE color system in the NE-SW direction cross section of FIG. 4 and the irradiated surface position, and (b) shows the CIE table in the NE-SW direction cross section of FIG. It is a graph which shows the relationship between y value in a color system, and a to-be-irradiated surface position, and shows Example 1 and 6-8 in comparison. (A) shows the relationship between the x value in the CIE color system in the NW-SE direction cross section of FIG. 4 and the irradiated surface position, and (b) shows the CIE table in the NW-SE direction cross section of FIG. It is a graph which shows the relationship between y value in a color system, and a to-be-irradiated surface position, and shows Example 1 and 6-8 in comparison. It is a figure which shows the state which radiate | emitted the light to the to-be-irradiated surface (2 m of length and width) 5 m ahead using the optical element of Example 1. FIG. It is a figure which adds an optical path to the model of a light source and a radiation | emission surface in the optical axis direction cross section of an optical element.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 4 is a view of the illumination device according to the present embodiment as viewed from the exit surface side. FIG. 5 is a view of the configuration of FIG. 4 taken along the line VV and viewed in the direction of the arrow. The LED lighting device according to the present embodiment includes an optical element 1 and an LED light source 2.

  The LED light source 2 has LED chips of different emission colors as shown in FIG. The center of the light emitting part 2 a of the LED light source 2 is on the optical axis OA of the optical element 1.

  The optical element 1 is formed using polycarbonate or acrylic as plastic. Further, the optical element 1 is disposed on the light emission side of the LED light source 2, and has an incident surface 3 having a concave portion into which light emitted from the LED light source 2 is incident, and a parabola that totally reflects light incident from the incident surface. It is formed integrally with a side surface 4 based on a surface, an emission surface 5 that emits emitted light to the outside, and a flange portion 6 formed around the emission surface 5, and has a rotationally symmetric shape around the optical axis. is there.

In the present embodiment, the position of the light emitting portion 2a is intentionally shifted from the focal point FS of the paraboloid forming the side surface 4 so as to approach the optical element 1 side (the area of the light emitting portion is S (mm ^2). ), Within the range of √S (mm) from the focal position), the distribution of light emitted from other than on the optical axis OA is adjusted, and the light distribution angle when viewed from the entire light emitting surface (light emitting portion) Is narrowed.

The incident surface 3 intersects the bottom (incident bottom) 3a facing the LED light source 2, the first incident side 3b extending along the optical axis of the bottom 3a, the first incident side 3b, and along the optical axis. The second incident side surface 3c extends. In the present embodiment, referring to FIG. 1, the coordinates of any two points shifted from each other in the optical axis direction on the incident side surface of the concave portion C are P1 (Px1, Pz1) and P2 (Px2, Pz2), and the optical axis OA is a Z-axis that is a plus direction from the incident surface 3 toward the exit surface 5, an axis that is orthogonal to the optical axis OA is an X-axis that is a plus direction that is away from the optical axis OA, and passes through the point P1. If the angle between the normal and the optical axis perpendicular to the C incident side is α1 (°), and the angle between the normal and the optical axis perpendicular to the concave C incident side through the point P2 is α2 (°), The following formula is satisfied.
Px1 <Px2 (1)
Pz1> Pz2 (2)
α1> α2 (3)

  At this time, the radius at the point P1 farther from the entrance side of the recess C (light source LS side) of the incident surface 3 is h1 (mm), and the radius at the point P2 closer to the entrance side of the recess C (light source side) of the entrance surface 3 When h is a radius h2 (mm), h1 <h2 is satisfied. Furthermore, the angle between the optical axis and the normal line NL1 perpendicular to the incident side surface of the concave portion C through the point P1 is α1 (°), and the normal line NL2 perpendicular to the incident side surface of the concave portion C through the point P2 and the optical axis. When the formed angle is α2 (°), α1> α2 is satisfied.

  The optical element 1 and the LED light source 2 are not in contact with each other, and the periphery of the LED light source 2 is surrounded by a second incident side surface 3c. On the emission surface 5, an array structure LA is formed in which fine uneven units MS that are part of a spherical surface are arranged. As shown in FIG. 4, the adjacent concavo-convex units MS are in contact with each other, and the outer shape thereof is a hexagonal shape. In the present embodiment, the curvature radius AR of the concavo-convex unit MS = 4 mm, the row interval AD = 0.9 mm, and the height of the concavo-convex unit AH = 25 μm. The diffusion angle in this embodiment is about 0.35 °.

  The upper end of the side surface 4 is joined to the flange portion 6 projecting outward in the radial direction, and the joint portion has an effective diameter. An upper surface of the flange portion 6 is an emission surface 5.

  FIG. 6 is a diagram illustrating an optical path of a light beam emitted from the illumination device according to the present embodiment. In the present embodiment, light emitted from the LED light source 2 by surface emission enters the optical element 1 from the incident surface 3. Here, the light incident on the bottom 3 a of the incident surface 3 is emitted from the emission surface 5 with almost no refraction. The light incident on the first incident side surface 3b of the incident surface 3 is refracted, totally reflected by the side surface 4, and then emitted from the emission surface 5 substantially along the optical axis direction. Further, the light incident on the second incident side surface 3 c of the incident surface 3 is totally reflected by the side surface 4 and then emitted from the emission surface 5 so as to be away from the optical axis direction. Thereby, color separation can be suppressed. Since all the light beams enter the irradiated surface SC that is 5 m away along the optical axis direction, it is possible to provide a lighting device with high directivity. Further, by forming the array structure LA on the emission surface 5, a diffusion effect can be given and color unevenness can be suppressed. In this embodiment, 88% or more of the total output power passes through the incident side surfaces 3 b and 3 c of the incident surface 3 and is totally reflected by the side surface 4.

  The inventor examined the effect of the array structure LA. The light distribution angle was obtained by changing the value of the intersection angle δ between the rows A and B of the concavo-convex units in FIG. FIG. 7 shows the relative luminous intensity on the vertical axis and the angle on the horizontal axis. Table 1 shows the relationship between the crossing angle and the light distribution angle (full width at half maximum). As shown in Table 1, when the crossing angle δ is 45 degrees, the light distribution angle is 7.12 degrees, and when the crossing angle δ is 60 degrees, the light distribution angle is 7.64 degrees, Is 90 degrees, the light distribution angle is 8.32 degrees, which satisfies the condition of within 10 degrees.

(Example)
Examples of the present invention will be described with reference to comparative examples. 8 is a cross-sectional view of the optical element according to Example 1, FIG. 9 is a cross-sectional view of the optical element according to Example 2, and FIG. 10 is a cross-sectional view of the optical element according to Example 3. 11 is a cross-sectional view of the optical element according to Example 4, FIG. 12 is a cross-sectional view of the optical element according to Example 5, and FIG. 13 is a cross-sectional view of the optical element according to Example 6. FIG. 14 is a cross-sectional view of the optical element according to Example 7, FIG. 15 is a cross-sectional view of the optical element according to Example 8, and FIG. 16 is a cross-sectional view of the optical element according to Comparative Examples 1 and 2. It is sectional drawing. FIG. 17 is a cross-sectional view of an optical element according to Comparative Example 3. In addition, Tables 2 and 3 show various values in Examples and Comparative Examples. However, the values of P1 (Px1, Pz1) and P2 (Px2, Pz2) in Table 2 are examples.

  Example 1 has the same shape as the above-described embodiment. In Example 2, the incident side surface of the concave portion of the incident surface is represented by a single free curve on the optical axis cross section, and its radius gradually increases from the bottom toward the entrance. In the third embodiment, the concave portion of the incident surface includes three regions, that is, the incident side surface of the concave portion is formed by three straight lines in the cross section in the optical axis direction. Here, the intersection of the incident side surface in the innermost region and the incident side surface in the middle region is CP. The fourth embodiment is different from the first embodiment in that a parabolic concave portion is formed at the center of the emission surface. The arrayed uneven shape is provided on the inner periphery and the periphery of the recess on the exit surface. The fifth embodiment is different from the first embodiment in that a cup-shaped recess is formed at the center of the emission surface. The cup-shaped bottom surface is a flat surface and the peripheral surface is a tapered surface. The arrayed uneven shape is provided around the cup bottom surface and the recessed portion. In Examples 6 and 7, the concave shape is changed with respect to Example 1, and in Example 8, the concave shape is changed with respect to Example 3.

  On the other hand, in Comparative Example 1, the incident side surface of the incident surface is represented by a single straight line on the optical axis cross section. Further, Comparative Example 2 is obtained by omitting the array-shaped uneven shape on the exit surface side as compared with Comparative Example 1. Further, in Comparative Example 3, the incident side surface of the incident surface is represented by two straight lines on the optical axis cross section, but is a tapered surface whose diameter increases as the incident side surface on the bottom side approaches the inlet side. The incident side surface is an example of a cylindrical surface. That is, in Comparative Example 3, α1 <α2.

  Table 2 shows various design values of the example and the comparative example, and Table 3 shows values of α1, α2, and θ in the example and the comparative example. The angle α1 is an angle formed by a normal line perpendicular to the incident side surface of the concave portion on the bottom side and the optical axis across the intersection CP in the cross section in the optical axis direction, and the angle α2 is perpendicular to the incident side surface of the concave portion on the entrance side. The normal θ is an angle formed with the optical axis, and the angle θ is an angle formed by a straight line (or a tangent to the incident side surface of the concave portion) that forms the incident side surface of the concave portion on the most bottom side with the optical axis. Here, the position of the light emitting portion that intersects the optical axis of the optical element is taken as the origin of coordinates. The CP ratio is the ratio of the distance from the entrance end of the recess to the intersection point CP when the depth of the recess (distance from the entrance end to the bottom of the recess) is 1 (CP ratio = intersection point from the entrance end of the recess) The distance to CP / the distance from the entrance end to the bottom of the recess), and the focal position is a value on the optical axis, and the origin is zero.

  18 to 21, in Example 1 and Comparative Examples 1 to 3, the ordinate represents the x value in the CIE color system or the y value in the CIE color system, and the abscissa represents 0 as the optical axis. The position of the irradiated surface is taken for comparison. As these graphs become closer to flat, the color of the emitted light approaches more uniformly (there is less color separation) regardless of the position of the irradiated surface.

  Referring to FIGS. 18 to 21, the graph of Comparative Example 3 has the largest undulation, and the graph of Comparative Example 2 is the most, in both the x value (a) and the y value (b) in the CIE color system. The undulation is large, then the undulation of the graph of Comparative Example 1 is large, and the undulation of the graph of Example 1 is closest to the flat. Thereby, the effect of the present invention was confirmed.

  22 to 25, for Examples 1 to 3, the vertical axis represents the x value in the CIE color system, or the y value in the CIE color system, and the horizontal axis represents the irradiated surface when the optical axis is zero. The positions are taken for comparison. All the graphs of Examples 1 to 3 are nearly flat. In addition, the x and y values in Examples 4 and 5 are substantially the same as in Example 1.

  When the x and y values of the CIE color system are uniform over the entire irradiated surface, color unevenness and color separation are less. Furthermore, it is better that the slope of the value at the irradiated surface position coordinates (the slope of the graph) is substantially the same slope for x and y. That is, when comparing graphs of the same cross section with x and y values, color unevenness and color separation are less when the graph shapes are similar. Furthermore, it is better that the slopes of the x and y values (the slope of the graph) have the same sign throughout. For example, as the irradiated surface position changes from minus to plus, color unevenness and color separation are less when the graph is monotonously decreasing or monotonically increasing. That is, even if the value is not uniform at the irradiated surface position, there is less up-down of the graph, and there is less color unevenness and color separation when changing almost monotonously. Examples 1 to 5 satisfy such a condition.

  26 to 29, for Example 1 and Examples 6 to 8, the vertical axis represents the x value in the CIE color system or the y value in the CIE color system, and the horizontal axis represents 0 as the optical axis. The position of the surface to be irradiated is shown for comparison. Compared to the graph of Example 1, the graphs of Examples 6 to 8 have relatively large undulations, and some color separation is recognized, but it is better than Comparative Examples 1 to 3, and is actually used in a somewhat bright place. Above is a level that is almost no problem. FIG. 30 is a diagram illustrating a state in which light is emitted to an irradiated surface (2 m in length and width) 5 m ahead using the optical element of Example 1. Further, in this example and the comparative example, the product name LEATBS2W of OSRAM Co. (light emitting surface (light emitting part) shape is schematically shown in FIG. 3) is used as the light source, so that the cross section in the 45 degree direction (XII-XII direction) is the most. Although the undulations of the graph are large, there is a possibility that the color separation is further improved by using another light source. Further, the light emitting area of LEATBS2W is about 20 square millimeters.

1 Lens 2 LED light source 2a Light emitting surface (light emitting part)
3 entrance surface 3a bottom (incident bottom)
3b 1st incident side surface 3c 2nd incident side surface 5 Outgoing surface 6 Flange part

Claims (14)

An optical element for illuminating a surface to be irradiated by transmitting light emitted from a light source,
An incident surface having an incident bottom surface and an incident side surface; a side surface that totally reflects incident light incident from the incident surface; and an exit surface that emits light toward the irradiated surface;
When a cross section passing through the optical axis of the optical element is taken, the coordinates of any two points on the incident side surface are P1 (Px1, Pz1) and P2 (Px2, Pz2), and at least one P1 that satisfies the following expression: , P2 exists, and the optical element.
Px1 <Px2 (1)
Pz1> Pz2 (2)
α1> α2 (3)
However, the optical axis is the Z-axis with the positive direction from the incident surface toward the exit surface, the axis orthogonal to the optical axis is the X-axis with the direction away from the optical axis as the positive direction, and passes through the incident point P1 The angle formed between the normal line perpendicular to the side surface and the optical axis is α1 (°), and the angle formed between the normal line perpendicular to the incident side surface and the optical axis is α2 (°).   The optical element according to claim 1, wherein a diffusion surface is provided on the emission surface.   The optical element according to claim 2, wherein the diffusion surface is formed by arranging minute uneven shapes in an array.   The optical element according to claim 1, wherein a surface-emitting light source is disposed so as to face the incident surface.   The optical element according to claim 4, wherein the surface-emitting light source has light emitting portions of different colors that emit light of two or more colors simultaneously.   The optical element according to claim 1, wherein an incident side surface of the concave portion is represented by a plurality of straight lines when a cross section passing through the optical axis of the optical element is taken.   The at least one of the intersections of the plurality of straight lines is located at a position of 7/10 or less from the entrance of the recess when the depth of the recess is 1. Optical element.   The intersection of any two straight lines forming the incident side surface of the concave portion exists within 30 to 70 degrees with respect to the optical axis with respect to the intersection of the light emitting portion of the light source and the optical axis of the optical element. The optical element according to claim 6 or 7, wherein   The optical element according to any one of claims 6 to 8, wherein an angle formed by any straight line forming the incident side surface of the concave portion with the optical axis of the optical element is 3 to 10 degrees.   The optical element according to claim 1, wherein when the cross section passing through the optical axis of the optical element is taken, the incident side surface of the concave portion is a curve.   The optical element according to claim 1, wherein a side surface of the optical element has a shape based on a paraboloid.   The optical element according to claim 1, wherein a flange part is formed in a peripheral part of the optical element.   The optical element according to claim 1, wherein the optical element is made of resin.   An illumination device comprising the optical element according to claim 1 and a light source.