JP2016075833A - Fresnel-lens optical system and lighting system using the optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical system that offers a high efficiency and a high maximum luminous intensity while collecting luminous flux from a light source.SOLUTION: There is provided an optical element opposed to a light source and including a plurality of grooved ring bands, in which each ring band has an entrance surface, an exit surface, and a side surface substantially perpendicular to the exit surface, the optical element having a first region where a rise angle of the entrance surface is smaller in the ring band at the center and is larger in ring bands at the periphery, and the rise angle of the entrance surface of one of ring bands outside the first region which is the nearest to the center is smaller than the rise angle of the entrance surface of the outermost ring band in the first region.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a Fresnel lens optical system that changes a light distribution of a light source.

  As a technology related to the Fresnel lens, for example, the one described in Patent Document 1 is known.

JP 2013-190788 A

  As light sources for lighting devices such as ceiling lights and base lights, LEDs (Light Emitting Diodes) are being used in place of conventional fluorescent and incandescent bulbs for environmental considerations and low power consumption. . The LED light source has a light distribution different from that of conventional fluorescent lamps and incandescent lamps, has the highest luminous intensity toward the front of the light source, and is very dark in the orthogonal direction, that is, in the horizontal direction. is there. As described above, since the LED is a light source having high directivity, there is a concern that when it is mounted on a conventional lighting fixture, the lighting method is different, so that the lighting environment becomes different.

  In conventional spotlights and beam bulbs, like an incandescent bulb, an optical system is configured by combining a light source that emits a filament, a mirror mirror that collects a luminous flux, and a lens. When the light source is replaced with an LED using this optical system, the directivity of the incandescent bulb and the LED light source is different, so that there is a problem that an appropriate light distribution cannot be obtained and the efficiency is lowered. In order to solve this problem, it is necessary to develop a new dedicated optical system.

  For example, there is an optical system using a Fresnel lens as a method of condensing the luminous flux of a light source. The Fresnel lens has a shape in which the lens surface is cut with a concentric annular zone and dropped into a substantially flat surface. Light rays are refracted in each ring zone to obtain a lens effect.

  In the above-mentioned Patent Document 1, an optical element that changes the direction of light from a light source, comprising a refractive lens part around the center of the optical element and a reflector part outside thereof, the refractive lens part being from the light source The light is refracted and irradiated forward, and the reflector portion is configured to totally reflect light from the light source and irradiate forward, and a line connecting the center of the optical element and the center of the light source is light. As the axis, the focal length near the center of the refractive lens portion is smaller than the distance on the optical axis to the center position of the light source, and the focal length of the peripheral portion of the refractive lens portion reaches the center position of the light source. An optical element configured to be larger than the distance on the optical axis is disclosed.

  In the configuration described in Patent Document 1, the focal length near the center of the refractive lens portion is smaller than the distance on the optical axis to the center position of the light source, and the focal length of the peripheral portion of the refractive lens portion is Since the distance is larger than the distance on the optical axis to the center position of the light source, the emitted light beam is condensed near the center of the refractive lens portion and diverges at the peripheral portion. In this configuration, the condensed light beam near the center becomes a divergent light beam beyond the imaging position of the light source at a position sufficiently away from the emission surface. When the light beam is refracted in the condensing direction, the larger the refraction angle, the shallower the angle between the incident surface and the incident light beam, the more likely Fresnel reflection occurs, and the lower the transmittance, resulting in a decrease in the maximum luminous intensity. In other words, since the angle of refraction is large inside the refractive lens part, the angle between the incident surface of the optical element and the incident light beam becomes shallow, Fresnel reflection is likely to occur, and the transmittance decreases, so that the maximum luminous intensity decreases. is there. Moreover, although the maximum luminous intensity can be improved by providing the reflector part which has a condensing function in the outer side of a refractive lens part, the subject that the optical element to which a reflector part is added becomes large occurs.

  The present invention has been made in view of the above-described problems of the prior art, and an object thereof is to provide an optical system having high efficiency and high maximum luminous intensity while condensing a light beam from a light source.

  The above problem is solved by, for example, the invention described in the claims.

More specifically, an optical system according to the present invention is arranged to face a light source, and in an optical element including a plurality of groove-shaped annular zones,
Each annular zone is composed of an incident surface and a side surface substantially perpendicular to the exit surface, and the rising angle of the incident surface of each annular zone is small in the central annular zone of the optical element and exists on the outer peripheral side. The first zone has a first region that changes so as to increase, and the rising angle of the incident surface of the most central ring zone outside the first region is the outermost ring zone of the first region. The optical element is smaller than the rising angle of the incident surface.

  According to the present invention, it is possible to provide an optical system with high efficiency and high maximum luminous intensity while condensing a light beam from a light source.

Sectional drawing which shows an example of the illuminating device carrying the optical element which concerns on this invention. The bird's-eye view which shows the optical element which concerns on this invention. Sectional drawing of the optical element which concerns on this invention. Sectional drawing of the ring zone of the optical element which concerns on this invention. An example of the ring zone and optical path of the optical element according to the present invention. Sectional drawing of the ring zone of the optical element which concerns on this invention. An example of distribution of the inclination angle of the entrance plane of the annular zone of the optical element according to the first embodiment. An example of change rate distribution of the inclination-angle of the entrance plane of the annular zone of the optical element which concerns on a 2nd Example.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  In the embodiment, the rising angle of the incident surface of each annular zone of the optical element is adjacent between the region where the central side of the optical element changes so that the central side is small and the outer peripheral side is large, and the outermost circumference is reached. The distribution zone with a high maximum luminous intensity while narrowing to the desired beam angle by the configuration in which there is a portion where the rising angle is smaller on the outer peripheral incident surface than on the central incident surface. A technique suitable for obtaining will be described.

  In addition, the following description is for describing one embodiment of the present invention, and does not limit the scope of the present invention. Accordingly, those skilled in the art can employ embodiments in which each of these elements or all of the elements are replaced with equivalent ones, and these embodiments are also included in the scope of the present invention.

  The first embodiment will be described with reference to FIGS. 1, 2, 3, 4, and 5. Here, FIG. 1 shows a cross-sectional view of an example of a lighting device equipped with the optical element according to the present invention. In FIG. 1, an illumination device including a light source substrate 11, a reflection unit 2, an optical element 3, a housing 4, and a socket 5 is illustrated.

  The housing 4 has a structure with high rigidity, and supports the light source substrate 11, the reflection means 2, and the optical element 3. The housing 4 has a power supply circuit for supplying power to the light source substrate 11, and has a circuit for appropriately distributing the power supplied to the socket 5 to the light source 1. The housing 4 is configured to release heat from the light source substrate 11 and the power source, and is made of a material with high heat dissipation. In some cases, a heat dissipating paint may be applied to the surface.

  The light source substrate 11 has at least one light source 1 mounted thereon. For example, an LED can be used as the light source 1, and a light beam is emitted toward the optical element 3 arranged so as to face the light source 1. Various types of light sources can be selected as the light source 1, and for example, a white LED that emits white light can be used.

  An example of the configuration of the white LED will be described. It is composed of an LED chip that emits blue light upon receiving electric power, and a phosphor that is excited by receiving the energy of blue light from the LED chip and emits light in a spectrum in a wavelength region from green to red. The phosphor may be mixed in a resin for sealing the LED chip. In addition, the phosphor may have a light emission spectrum that looks yellow when a plurality of phosphors that emit red and green light are mixed and excited to emit light. Of course, the emission spectrum of the phosphor may be changed so that light is emitted at different color temperatures. Further, in one LED, a large light amount type LED on which a plurality of light emitting chips are mounted may be used. In an LED equipped with a plurality of LED chips, it is preferable to arrange the LED chips in, for example, a rectangular shape or a concentric circle so as to be symmetrical with respect to the center of the light emitting surface (light emitting surface) of the LED. It is not limited to this.

  The light source 1 may be provided with optical components such as a lens and a reflector for adjusting light distribution and improving light extraction efficiency. As such an optical component, for example, a convex lens formed of a transmissive material, a metal-deposited mirror, or a reflector using total reflection can be provided at the periphery of the chip.

  The light source 1 is mounted on the light source substrate 11. Although FIG. 1 illustrates a configuration in which three light sources are confirmed from the side surface on the light source substrate 11, a plurality of light sources 1 may be mounted as necessary, and the number of light sources 1 is not limited.

  In addition to the light source 1, the light source substrate 11 adjusts the supplied power to a desired power and supplies the light source 1 with a drive circuit (driver) and wiring, or a current amount or voltage to the light source 1. It is connected to an electronic component such as a control circuit for controlling the power and an electric circuit.

The light source 1 may include a plurality of light sources 1 having different performances. For example, if there are a plurality of light sources 1 having different emission colors, and each of the emission colors can be driven by a circuit of an independent system, the power inputted to each system is controlled to emit light from each light source 1. Since the amount of light can be adjusted for each emitted color, it is possible to provide an optical system and an illumination device that can adjust the emitted color of emitted light.
The optical characteristics of the surface of the light source substrate 1 are desirably less absorbed.

  The reflecting means 2 has a function of reflecting a light beam that does not directly reach the optical element 3 from the light source 1, and makes it reach the optical element 3 and emit it. The reflection means 2 is made of a material having reflection characteristics. The material may be, for example, a mirror made of metal having a mirror surface or a dielectric multilayer film, a resin having white diffusion characteristics, or a metal surface having fine irregularities on the surface. Also good. Since the reflecting means 2 generally has a slight absorption characteristic, it is desirable that the light beam emitted from the light source 1 is directly incident on the optical element 3 in order to increase the emission efficiency of the illumination device. The shape of the reflecting means 2 is a shape that is small on the light source substrate 11 side and spreads toward the optical element 3 side, and may be a conical surface or a curved surface.

  If it is such a shape, since the light beam reflected by the reflection means 2 will increase the light beam which goes to the optical element 3, the light beam radiate | emitted from the light source 1 can be guide | induced to the optical element 3 effectively, and is used as an illuminating device. The effect of improving the efficiency of.

  The optical element 3 will be described with reference to FIGS.

  FIG. 2 is an overhead view of the optical element 3, and FIG. 3 is a cross-sectional view of the optical element 3.

  The optical element 3 is provided with a lens 31 at the center and includes at least one or more annular zones 32. The material of the optical element 3 is transparent, and is molded from, for example, resin or glass. As the molding method, injection molding using a mold can be used.

  The annular zone 32 is arranged on a substantially concentric circle and has a groove shape. The lens 31 and the plurality of annular zones 32 refract the light beam from the light source 1 and emit it with a desired light distribution.

  When used in the lighting device, the shape of the lens 31 and the annular zone 32 is formed on the light source 1 side from the viewpoint of maintenance properties. Further, the optical element 3 may be provided with a holding portion for assembling with the housing, for example, a claw or a positioning dowel.

  FIG. 4 shows the configuration of the annular zone 32, which includes an incident surface 321 and a side surface 322.

  FIG. 5 shows the optical path of the light beam 6 from the light source 1 that has reached the annular zone 32. The light beam 6 incident on the incident surface 321 is refracted by the incident surface 321, passes through the inside of the optical element 3, is guided to the output surface 33, and is refracted again by the output surface 33, thereby exiting from the output surface 33.

The emission angle is determined by the emission angle of the light beam 6 from the light source 1 toward the annular zone 32 and the inclination angle α _k of the incident surface of the annular zone 32. Here, α _k indicates the inclination angle of the incident surface 321 of the k-th annular zone 32 counted from the center (k is a natural number), and an example in which the ray 6 is incident on the k-th annular zone 32 will be described. Yes.

The side surface 322 has a steep slope and is substantially perpendicular to the emission surface 33. When the inclination angle with respect to the normal line of the exit surface 33 was beta _k, beta _k is easily dislodged from the mold during molding larger, has good manufacturability.

  Depending on the manufacturing method, R is attached to the switching portion between the incident surface 321 and the side surface 322. When molding with a mold, in order to extend the life of the mold, it is better to provide R in order to prevent chipping of the mold at the time of manufacture. If priority is given to optical performance, it will cause the light beam to be disturbed. It is desirable to make R as small as possible. This may be appropriately selected depending on the manufacturing capability and the optical characteristics required for the optical element 3.

  The first embodiment will be described with reference to FIG.

  In this embodiment, as shown in FIG. 6, in the optical element 3 that is arranged to face the light source and includes a plurality of groove-like annular zones 32, each annular zone 32 has an incident surface 321 and an outgoing surface 33. The rising angle of the incident surface 321 of each annular zone 32 is small in the central annular zone 32 of the optical element 3 and large in the annular zone 32 existing on the outer peripheral side. The rising angle of the incident surface 321 of the most annular zone 32 existing outside the first region 71 is the outermost annular zone of the first region 71. An optical element 3 smaller than the rising angle of 32 incident surfaces 321 is shown.

  FIG. 7 shows the distribution of the inclination angle of the incident surface of each annular zone 32 of the present embodiment. The horizontal axis is a position on the optical element 3 and a direction viewed from the light source. In the present embodiment, the first region 71 has a structure in which the inclination angle of the annular zone 32 monotonously increases, and the first region 71 on the center side has a light collecting effect, and In the second region 72 where the outer ring zone 32 is present, the light collection effect is weaker than in the first region, and the inclination angle of the incident surface 321 is set to the incidence of the outermost ring zone 32 of the first region 71. The angle of inclination of the surface 321 is made smaller to prevent the width of the annular zone 32 from being reduced.

  Incident light that reaches the annular zone 32 on the relatively outer peripheral side like the second region 72 from the light source 1 travels toward the annular zone 32 at a relatively shallow angle with respect to the emission surface 33. The positional relationship is also incident on the incident surface 321 at a shallow angle. If the incident angle is shallow, Fresnel reflection occurs at the interface having a different refractive index, so that a light beam that can be transmitted through the incident surface 321 occurs. As a result, the emission efficiency of the optical element 3 is reduced. In addition, since the light flux that is refracted by the incident surface 321 and is emitted in the intended direction is reduced, the effect of converting the light distribution of the optical element 3 is reduced.

  In addition, since the inclination angle of the incident surface 321 increases as the angle for changing the direction of the light beam increases, if the emission angle is narrowed in the second region 72 to collect light, the incident surface 321 is inclined. The angle increases. When the inclination angle of the incident surface 321 increases and rises, the width of the annular zone 32 becomes narrower or the depth of the annular zone 32 becomes deeper. It becomes difficult. That is, in the second region 72, if an annular zone 32 having a strong light collecting function is to be molded, it is very difficult to manufacture.

  With the configuration of the present embodiment, the above-described problems can be solved, so that the optical element 3 having high emission efficiency can be provided.

  A second embodiment will be described with reference to FIG.

  The optical element 3 according to the present embodiment is disposed so as to face the light source 1, and in the optical element 3 including a plurality of groove-shaped annular zones 32, each annular zone 32 is in relation to the incident surface 321 and the outgoing surface 33. The rising angle of the incident surface 321 of each annular zone 32 is small in the central annular zone 32 of the optical element 3 and large in the annular zone 32 existing on the outer peripheral side. The rising zone of the incident surface 321 of the most annular zone 32 that is provided outside the first zone 71 is provided with a first zone 71 that changes, and the outermost zone 32 of the first zone 71 In the optical element 3, which is smaller than the rising angle of the incident surface 321, the rate of change of the incident angle of the adjacent annular zone 32 has a peak 8 in the positive direction inside the first region 71. This is an optical element.

  When trying to spread the light distribution in the region outside the optical element 3, the light beam traveling from the light source 1 toward the annular zone 32 is angled with respect to the axis of symmetry of the optical element 3, so that there is little light beam traveling in the front direction. For this reason, since the light flux toward the front surface is reduced, there is a tendency to form a ring-shaped light distribution. If the light distribution is not sufficiently narrowed, undulations occur.

  With the configuration of this embodiment, the above-described problem can be solved. The inner region 711 of the first region 71 can make the inclination angle of the incident surface 321 of the annular zone 32 shallower than that of the outer region 712, and the light beam incident on the central region 711 is ring-shaped light distribution. A relatively wide light distribution can be achieved without becoming a distribution. In the region 712 outside the first region 71, the maximum luminous intensity can be increased because the light can be condensed relatively strongly on the front side. In the second region 72, the incident angle of the annular zone 32 is shallow, and the width of the annular zone 32 is relatively large, so that the emission efficiency is high. Therefore, with the configuration of the present embodiment, it is possible to provide the optical element 3 having high light emission efficiency and good light distribution characteristics with no undulations. In particular, this configuration is suitable for alleviating the restriction that the light distribution must be narrowed in order to suppress the undulation of the light distribution.

  The optical element 3 according to the present embodiment is any one of the optical elements 3 described in the first to second embodiments, and is an optical element 3 in which the exit surface 33 is subjected to graining.

  In the optical element 3 of this embodiment, the inclination angle of the incident surface 321 is shallow and the width of the annular zone 32 is increased in order to increase the transmittance. Therefore, the light beam incident on one annular zone 32 from the light source 1 and emitted from the optical element 3 becomes a ring-like light beam having a width substantially equal to the annular zone 32 at least in the vicinity of the emission surface 33 of the optical element 3. Yes. When a position sufficiently distant from the exit surface 33 is irradiated, a smooth illuminance distribution according to the light distribution is obtained. However, when it is not sufficiently distant, phosphorus-like illuminance unevenness on the exit surface 33 is generated. May remain. In the case of the configuration of the present embodiment, the ring-shaped illuminance distribution on the emission surface 33 by each annular zone 32 is blurred by the surface 33 of the optical element 3 so that the irradiation surface is close to the emission surface 33. However, the optical element 3 having a smooth light distribution can be provided.

  The optical element 3 according to the present embodiment is one of the optical elements 3 described in the first to third embodiments, and the optical element 3 in which the annular zone 32 has a straight section.

  If it is the optical element 3 of a present Example, one certain annular zone 32 will not image the light source 1. FIG. Therefore, the light beam emitted from the optical element 3 is relaxed to form an image of the light source 1, and the optical element 3 having a smooth illuminance distribution that does not reflect the arrangement of the light source 1 on the irradiation surface or the light emission intensity distribution of the light source 1 on the irradiation surface. Can be provided.

  As shown in FIG. 1, the illumination device according to the present embodiment is an illumination device including any one of the optical elements 3 described in the first to fourth aspects, the reflection unit 2, the light source 1, and the housing 4. is there.

  If it is an illuminating device of a present Example, the illuminating device with the characteristic of the optical element 3 of the above-mentioned Example can be comprised, Especially in the illuminating device which condenses the light beam from the light source 1 and narrows light distribution, it is smooth. In addition, it is possible to provide a lighting device having a high maximum luminous intensity while maintaining a good light distribution without undulations.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

DESCRIPTION OF SYMBOLS 1 ... Light source, 11 ... Light source board | substrate, 2 ... Reflection means, 3 ... Optical element, 31 ... Lens, 32 ... Ring zone, 321 ... Incident surface, 322 ... Side surface, 33 ... Output surface, 4 ... Housing | casing, 5 ... Socket , 6 ... light rays, 71 ... first area, 711 ... area inside the first area, 712 ... area outside the first area, 72 ... second area, 8 ... change in inclination angle of the incident surface. Rate peak

Claims (5)

In an optical element that is arranged to face the light source and includes a plurality of groove-shaped annular zones,
Each annular zone is composed of an incident surface and a side surface substantially perpendicular to the exit surface, and the rising angle of the incident surface of each annular zone is small in the central annular zone of the optical element and exists on the outer peripheral side. The first zone has a first region that changes so as to increase, and the rising angle of the incident surface of the most central ring zone outside the first region is the outermost ring zone of the first region. An optical element smaller than the rising angle of the incident surface. In an optical element that is arranged to face a light source and has a plurality of groove-shaped annular zones, each annular zone is composed of an incident surface and a side surface that is substantially perpendicular to the exit surface. A first region that has a first region that changes so that the rising angle of the surface is small in the central annular zone of the optical element and large in the annular zone existing on the outer peripheral side, and exists outside the first region. The rising angle of the incident surface of the side annular zone is smaller than the rising angle of the incident surface of the outermost annular zone of the first region, and in the first region, An optical element characterized in that the rate of change in incident angle between adjacent annular zones has a peak in the positive direction. The optical element according to claim 1 or 2,
An optical element characterized in that the exit surface is textured. The optical element according to any one of claims 1 to 3,
An optical element characterized in that the annular zone has a straight section. The illuminating device which has an optical element in any one of Claims 1-4, a reflection part, a light source, and a housing | casing.

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