JP2013182717A - Lighting optical system and lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce luminous unevenness of irradiated light flux and continuously change an irradiation region from a narrow range to a wider range, or downsize, save weight of, and reduce manufacturing cost of a structure of a device.SOLUTION: A lighting optical system 1 is composed of a lens 3, a lens 4, and a lens 5 arrayed in order from a light source 2 and a moving mechanism 6 for moving the lens 4 along an optical axis direction.

Description

  The present invention relates to an illumination optical system and an illumination device.

  An illumination device capable of adjusting the expansion / contraction of the light irradiation area has been proposed so as to be suitable for spot illumination or the like (see, for example, Patent Document 1). In the illuminating device of Patent Document 1, the spread of the light beam emitted from the light source is adjusted by moving a concave lens arranged in front of the light source along the optical axis.

Japanese Patent No. 4376289

  In the illumination device of Patent Document 1, as shown in FIG. 11B or FIG. 21B of the document, the light beam applied to the wall surface has a rough portion and a dense portion, and uneven illumination. It can be seen that The illumination device of Patent Document 1 is intended to guide light from a light source to a light irradiation area without loss, assuming a light source for product inspection or plant growth, as described in paragraph “0009” of the document. It is. For this reason, in the illuminating device of patent document 1, it is not a big problem that illuminance nonuniformity arises in the irradiated light beam.

  On the other hand, when the illumination device of Patent Document 1 is used as display illumination or indoor illumination, the occurrence of uneven illuminance in the irradiated light beam becomes a serious problem. For example, it is not preferable from the viewpoint of the design of the display or interior such that a donut-shaped light ring is generated in the light illumination area, or the illuminance near the center of the light illumination area becomes extremely high.

  Moreover, since the illuminating device of patent document 1 uses only the concave lens which has negative power, the light beam radiate | emitted from the light source diverges with a concave lens. In such a configuration, the aperture of the illumination device is increased so as not to disturb the diverging light flux. This hinders the reduction in size, weight, and cost of the lighting device.

  The present invention has been performed under such a background, and reduces unevenness in the illuminance of the irradiated light beam, and continuously changes the illumination area from a narrow range to a wide range, or It is an object of the present invention to provide an illumination optical system and an illumination apparatus that can achieve any one or more of a configuration that is reduced in size, weight, and cost.

  One aspect of the present invention is a viewpoint as an illumination optical system. The illumination optical system of the present invention includes a first lens, a second lens, a third lens, and a moving mechanism that moves the second lens along the optical axis direction, which are arranged in order from the light source. It is what has.

  In the illumination optical system of the present invention, the first lens is a lens having a positive power, and the light emitted from the light source includes an inner light beam including a light beam on the optical axis and an outer surface positioned outside the inner light beam. The second lens emits light so as to have a non-intersecting region where the inner and outer light beams do not intersect with each other, and the second lens can move in the optical axis direction in the non-intersecting region. It is preferable to have an aperture through which the luminous flux and the outer luminous flux are transmitted.

  Moreover, it is preferable that a 1st lens has an inner lens which is arrange | positioned on an optical axis and has the positive power which radiate | emits an inner light beam, and a reflector part arrange | positioned on the outer side of an inner lens.

  The second lens has positive power, at least one surface is an aspherical lens, and the region through which the outer light beam is transmitted preferably has a lower positive power than the region through which the inner light beam is transmitted.

  Furthermore, it is preferable that at least one surface of the third lens is an aspheric lens, and the negative power increases as the distance from the optical axis increases.

  In addition, a means for diffusing light can be disposed on the emission side of the third lens. Alternatively, the third lens may have a light scattering function. Alternatively, a Fresnel lens may be arranged on the emission side of the third lens.

  Alternatively, in the illumination optical system of the present invention, at least one of the second lens and the third lens may be a Fresnel lens.

  Another aspect of the present invention is a lighting device. The illumination device of the present invention has the illumination optical system of the present invention.

  According to the present invention, the illuminance unevenness of the irradiated light flux is reduced, and the illumination area is continuously changed from a narrow range to a wide range, or the configuration of the apparatus is reduced in size, weight, and cost. Any one or more of the above can be achieved.

It is a block diagram of the illumination optical system which concerns on 1st embodiment of this invention, and is a figure which shows a lens position in case the irradiation angle of an illumination optical system is a narrow angle. It is a block diagram of the illumination optical system which concerns on 1st embodiment of this invention, and is a figure which shows a lens position in case the irradiation angle of an illumination optical system is an intermediate angle. It is a block diagram of the illumination optical system which concerns on 1st embodiment of this invention, and is a figure which shows a lens position in case the irradiation angle of an illumination optical system is a wide angle. It is a perspective view of the illuminating device which has the illumination optical system which concerns on 1st embodiment of this invention. It is sectional drawing which cut | disconnected the illuminating device shown in FIG. 4 in the plane containing the optical axis of an illumination optical system. It is a figure which shows the far field light distribution in the lens position of the narrow angle of the illumination optical system shown in FIG. It is a figure which shows the illumination intensity distribution just under 1 m in the lens position of the narrow angle of the illumination optical system shown in FIG. It is a figure which shows the far field light distribution in the lens position of the intermediate angle of the illumination optical system shown in FIG. It is a figure which shows the illumination intensity distribution just under 1 m in the lens position of the intermediate angle of the illumination optical system shown in FIG. It is a figure which shows the far field light distribution in the wide-angle lens position of the illumination optical system shown in FIG. It is a figure which shows the illumination intensity distribution just under 1 m in the wide-angle lens position of the illumination optical system shown in FIG. It is a block diagram of the illumination optical system which concerns on 2nd embodiment of this invention, and is a figure which shows a lens position in case the irradiation angle of an illumination optical system is a narrow angle. It is a figure which shows the far field light distribution in the lens position of the narrow angle of the illumination optical system shown in FIG. It is a figure which shows the far field light distribution in the lens position of the narrow angle of the illumination optical system shown in FIG. 12 when not using a diffusion sheet as a comparative example. It is a block diagram of the illumination optical system which concerns on 2nd embodiment of this invention, and is a figure which shows a lens position in case the irradiation angle of an illumination optical system is an intermediate angle. It is a figure which shows the far field light distribution in the lens position of the intermediate angle of the illumination optical system shown in FIG. It is a figure which shows the far field light distribution in the lens position of the intermediate | middle angle of the illumination optical system shown in FIG. 15 when not using a diffusion sheet as a comparative example. It is a block diagram of the illumination optical system which concerns on 2nd embodiment of this invention, and is a figure which shows a lens position in case the irradiation angle of an illumination optical system is a wide angle. It is a figure which shows the far field light distribution in the wide-angle lens position of the illumination optical system shown in FIG. It is a figure which shows the far field light distribution in the wide-angle lens position of the illumination optical system shown in FIG. 18 when not using a diffusion sheet as a comparative example. It is a block diagram of the illumination optical system which concerns on 3rd embodiment of this invention, and is a figure which shows a lens position in case the irradiation angle of an illumination optical system is a narrow angle. It is a figure which shows the far field light distribution in the lens position of the narrow angle of the illumination optical system shown in FIG. It is a block diagram of the illumination optical system which concerns on 3rd embodiment of this invention, and is a figure which shows a lens position in case the irradiation angle of an illumination optical system is an intermediate angle. It is a figure which shows the far field light distribution in the lens position of the intermediate angle of the illumination optical system shown in FIG. It is a block diagram of the illumination optical system which concerns on 3rd embodiment of this invention, and is a figure which shows a lens position in case the irradiation angle of an illumination optical system is a wide angle. FIG. 26 is a diagram showing a far-field light distribution at a wide-angle lens position of the illumination optical system shown in FIG. 25.

(First embodiment)
An illumination optical system 1 and an illumination apparatus according to a first embodiment of the present invention will be described with reference to FIGS.

  As shown in FIGS. 1 to 3, the illumination optical system 1 includes a reflector type lens 3 as a first lens and a convex lens as a second lens in order from the light source 2 side which is an LED (Light Emitting Diode). A lens 4, a lens 5 that is a concave lens as a third lens, and a moving mechanism 6 that moves the lens 4 along the optical axis direction are provided.

  FIG. 1 shows the position of the lens 4 of the illumination optical system 1 when the irradiation angle is narrow. In this case, the illumination area on the projection surface S located at a predetermined distance from the illumination optical system 1 is the illumination area L1. FIG. 2 shows the position of the lens 4 of the illumination optical system 1 when the irradiation angle is an intermediate angle. In this case, the illumination area on the projection surface S located at a predetermined distance from the illumination optical system 1 is an illumination area L2 (> L1). FIG. 3 shows the position of the lens 4 of the illumination optical system 1 when the irradiation angle is a wide angle. In this case, the illumination area on the projection surface S located at a predetermined distance from the illumination optical system 1 is an illumination area L3 (> L3). 1 to 3 extract only characteristic ones of the light beams constituting the light flux for easy understanding. Therefore, in reality, a large number of light beams pass through the place indicated by “...

  The lens 3 is a lens having positive power, and the light emitted from the light source 2 is converted into an inner luminous flux 7 including a light beam on the optical axis and an outer luminous flux 8 positioned outside the inner luminous flux 7. And the outer luminous flux 8 are emitted so as to have a non-intersecting region N where they do not intersect each other. More specifically, the lens 3 includes an inner lens portion 9 that is disposed on the optical axis and has a positive power that emits the inner luminous flux 7, and a reflector portion 10 that is disposed outside the inner lens portion 9. The material of the lens 3 must be able to withstand the heat generated by the light source 2. For example, the lens 3 is made of polycarbonate. Polycarbonate is suitable as a material for the lens 3 because the normal heat-resistant temperature is 130 degrees or less.

  The lens 4 can be moved in the optical axis direction within the above-described non-intersecting region N by the moving mechanism 6, and has a diameter through which the inner luminous flux 7 and the outer luminous flux 8 in the non-intersecting region N are transmitted. More specifically, the lens 4 has positive power, at least one surface is an aspherical lens, and the region where the outer light beam 8 is transmitted has a lower positive power than the region where the inner light beam 7 is transmitted.

  The lens 5 is a concave lens having a diameter through which the light beam emitted from the lens 4 is transmitted. At least one surface of the lens 5 is an aspheric lens, and the negative power increases as the distance from the optical axis increases.

  The material of the lenses 4 and 5 does not require a high heat resistant temperature like the lens 3 and may be acrylic (ordinary heat resistant temperature of 90 degrees or less).

  As shown in FIGS. 4 and 5, the illumination optical system 1 can be configured using a lens moving barrel Z as a moving mechanism for moving the lens 4 in the optical axis direction. The lenses 3, 4, and 5 are disposed inside the lens moving barrel Z. The lens moving lens barrel Z includes a fixed cylinder 13 in which the rectilinear groove 12 is formed, a pedestal portion 17 to which the fixed cylinder 13 is attached, and a cam cylinder 15 in which the cam groove 14 is formed. As shown in FIG. 5, a protruding portion 16 is attached to the outer periphery of the lens 4, and the protruding portion 16 is fitted into the rectilinear groove 12 and the cam groove 14. Here, when the cam cylinder 15 is rotated in the circumferential direction, the projecting portion 16 obtains a driving force in the front-rear direction by the cam groove 14 while being guided back and forth in the optical axis direction by the rectilinear groove 12, thereby generating a straight line in the front-rear direction portion. Can move. Along with the movement of the protruding portion 16, the lens 4 also moves in the optical axis direction.

  As shown in FIGS. 4 and 5, the illumination optical system 1 can be configured as the illumination device 11 by including a light source unit 19. The light source unit 19 is attached to the pedestal 17 by rivets 20. Further, a protective lens 21 is provided on the exit side of the lens 5. The protective lens 21 is, for example, a transparent flat plate and is an optically neutral lens. The material of the protective lens 21 may be acrylic. Further, the protective lens 21 may be omitted.

  FIG. 6 shows the far-field light distribution of the illumination optical system 1 at the position (narrow angle position) of the lens 4 shown in FIG. Here, the far-field light distribution is determined by ignoring the size of the illumination optical system 1 and assuming that a point light source regarded as light emission from one point is at infinity, and in which direction and how much light is emitted. It is distribution shown. FIG. 6 shows an angle (on the same plane) between the optical axis of the illumination optical system 1 and the light measurement direction, and the vertical axis is obtained by normalizing the illuminance intensity with the maximum value. 1 is a light distribution angle at which the measurement light intensity of the illumination optical system 1 at the position of the lens 4 (narrow angle position) shown in FIG. 1 is half the maximum measurement light intensity at the optical axis position. The light distribution angle is 13.5 degrees.

  As shown in FIG. 6, at the position of the lens 4 shown in FIG. 1, the irradiation light intensity viewed from the optical axis direction of the illumination optical system 1 is the strongest, and the light intensity suddenly decreases as the angle formed with the optical axis increases. You can see how they are doing.

  FIG. 7 shows an illuminance distribution at a distance of 1 m from the light source 2 of the illumination optical system 1 at the position (narrow angle position) of the lens 4 shown in FIG. 7 shows the illumination area L1 projected onto the projection plane S. In the lower diagram of FIG. 7, the horizontal axis represents the distance (mm: millimeter) from the optical axis of the illumination optical system 1 projected onto the projection surface S, and the vertical axis represents the illuminance (Lux: lux). The illuminance distribution in the X direction in the illumination area L1 is shown. 7 shows the illuminance distribution at a position shifted by 90 degrees around the optical axis from the illuminance measurement position in the lower diagram of FIG. 7 (that is, the Y direction in the illumination region L1). Yes. The vertical axis represents the distance from the optical axis of the illumination optical system 1 projected onto the projection surface S, and the horizontal axis represents the illuminance.

  As shown in FIG. 7, at the position of the lens 4 shown in FIG. 1, there is a small region 30 with high illuminance (about 10 mm in radius from the optical axis) near the center of the illumination region L <b> 1, and around the region 30. The region 31 has a lower illuminance than the region 30 and occupies most of the region L1 (radius of about 50 mm from the optical axis). Around the region 31, there is a small region 32 having a lower illuminance than the region 31. Although there is a region having a slight illuminance around the region 32, the illustration in FIG. 7 is omitted. The light distribution in the upper right diagram in FIG. 7 and the light distribution in the lower diagram in FIG. 7 are substantially the same.

  FIG. 8 shows a far-field light distribution of the illumination optical system 1 at the position (intermediate angle position) of the lens 4 shown in FIG. In addition, the half value light distribution angle of the illumination optical system 1 in the position (intermediate angle position) of the lens 4 shown in FIG. 2 is 20 degrees. As shown in FIG. 8, at the position of the lens 4 shown in FIG. 2, the range in which the illumination intensity of the illumination optical system 1 is the strongest as compared with FIG. 6 is widened, and the skirt portion of the light distribution curve is widened. I understand. That is, the illumination area L2 is wider than the illumination area L1.

  FIG. 9 shows an illuminance distribution at a distance of 1 m from the light source 2 of the illumination optical system 1 at the position (intermediate angle position) of the lens 4 shown in FIG. 9 shows the illumination area L2 projected on the projection plane S. The upper left diagram in FIG. As shown in FIG. 9, at the position of the lens 4 shown in FIG. 2, there is a region 40 (radius of about 100 mm from the optical axis) having a higher illuminance near the center of the illumination region L <b> 2. There is a region 41 (a radius of about 150 mm from the optical axis) that is slightly lower in illuminance than the region 40 in the periphery. Although there is a region having a slight illuminance around the region 41, the illustration in FIG. 9 is omitted. The illuminance distribution in the upper right diagram in FIG. 9 and the illuminance distribution in the lower diagram in FIG. 9 are substantially the same. Compared with FIG. 7, it can be seen that the number of regions with different illuminances is reduced and the illuminance is equalized over a wide range.

  FIG. 10 shows the far-field light distribution of the illumination optical system 1 at the position (wide-angle position) of the lens 4 shown in FIG. Note that the half-value light distribution angle of the illumination optical system 1 at the position of the lens 4 shown in FIG. 3 (wide-angle position) is 32 degrees. As shown in FIG. 10, it can be seen that the skirt portion of the light distribution curve of the illumination optical system 1 is further expanded at the position of the lens 4 shown in FIG. That is, the illumination area L3 is wider than the illumination area L2.

  FIG. 11 shows an illuminance distribution at a distance of 1 m from the light source 2 of the illumination optical system 1 at the position (wide angle position) of the lens 4 shown in FIG. 11 shows the illumination area L3 projected on the projection surface S. As shown in FIG. 11, at the position of the lens 4 shown in FIG. 3, there is a region 50 (radius of about 80 mm from the optical axis) having a slightly higher illuminance near the center of the illumination region L3. , There is a region 51 (radius of about 300 mm from the optical axis) having a slightly lower illuminance than the region 50. Further, there is a region 52 (radius of about 400 mm or more from the optical axis) around the region 51 that has slightly lower illuminance than the region 51. Note that the illuminance distribution in the upper right diagram in FIG. 11 and the illuminance distribution in the lower diagram in FIG. 11 are substantially the same. Compared to FIG. 9, it can be seen that the illuminance is equalized in a wider range.

  As described above, the illumination optical system 1 includes the lens 3, the lens 4, and the lens 5 in this order from the light source 2, and the lens 4 can be moved in the optical axis direction by the moving mechanism 6 (lens moving barrel Z). It is configured. In such a configuration, when the lens 4 moves, the distance between the lens 3 and the lens 4 and the distance between the lens 4 and the lens 5 change, and the light distribution angle (the width of the illumination area) of the illumination optical system 1 is changed. Can be changed. That is, the focal distance on the front side of the lens 3 can be changed by changing the distance between the lens 4 and the lens 5. Therefore, the illumination area (light distribution angle) of the light emitted from the illumination optical system 1 can be continuously changed.

  The lens 3 of the illumination optical system 1 is a lens having a positive power, and the light emitted from the light source 2 is converted into an inner luminous flux 7 including a light beam on the optical axis and an outer side located outside the inner luminous flux 7. The light beam 8 can be emitted so as to have a non-intersecting region N where the inner light beam 7 and the outer light beam 8 do not intersect each other. More specifically, the lens 3 includes an inner lens portion 9 that is disposed on the optical axis and has a positive power for emitting the inner light flux 7, and a reflector portion 10 that is disposed outside the inner lens portion 9. Therefore, the inner luminous flux 7 and the outer luminous flux 8 can be separated with good and high efficiency. The lens 3 may be a lens or a reflector that can emit the light emitted from the light source 2 as a parallel light beam. By making the light emitted from the lens 3 into parallel light beams, the inner light beam 7 and the outer light beam 8 can be brought into a non-intersecting state.

  According to this, the inner luminous flux 7 and the outer luminous flux 8 can be transmitted through different parts of the lens 4 in the next stage, and the inner luminous flux 7 and the outer luminous flux 8 emitted from the lens 3 are separated in the design of the lens 4. And can be designed to be controlled. That is, when designing the shape of the lens 4, the inner luminous flux 7 emitted from the lens 3 is controlled by adjusting the curvature near the center of the lens 4, and the outer luminous flux 8 emitted from the lens 3 4 can be controlled by adjusting the curvature of the outer peripheral portion. For this reason, the illumination optical system 1 can easily design the shape of the lens 4 so as to reduce the illuminance unevenness of the irradiated light beam.

  Further, the lens 4 can move in the optical axis direction within the above-described non-intersecting region N, and has a diameter through which the inner luminous flux 7 and the outer luminous flux 8 in the non-intersecting region N are transmitted. That is, even when the lens 4 moves in the non-intersecting region N in the optical axis direction, the inner luminous flux 7 and the outer light 8 bundle pass through different portions of the lens 4. That is, the inner luminous flux 7 is transmitted in the vicinity of the central portion, and the outer light 8 bundle is transmitted through the outer peripheral portion of the lens 4. Thus, according to the illumination optical system 1, illumination is reduced while reducing illuminance unevenness of the irradiated luminous flux. The region can be continuously changed from a narrow range to a wide range.

  The lens 4 has positive power, at least one surface is an aspherical lens, and the region where the outer light beam 8 is transmitted is weaker than the region where the inner light beam 7 is transmitted. . By setting the lens 4 to positive power, the light emitted from the lens 3 is not expanded (diverged), and therefore the aperture of the lens 5 can be reduced. That is, the entire diameter of the illumination optical system 1 can be reduced. According to this, the illuminating device 1 can be reduced in size, weight, and cost. Further, by making the lens 4 an aspherical lens, the aspherical coefficient of the outer peripheral portion of the lens 4 can be adjusted, the outer light beam 8 emitted from the lens 3 can be controlled more easily, and the lens 4 is moved. It is possible to reduce illuminance unevenness over a wide range. Further, even after passing through the lens 4, it is possible to make many regions where the inner luminous flux 7 and the outer luminous flux 8 are not crossed. According to this, similarly to the design of the shape of the lens 4 described above, the inner luminous flux 7 emitted from the lens 4 is also in the vicinity of the central portion of the lens 5 in the design of the shape of the lens 5 whose at least one surface is an aspherical lens. The outer light beam 8 emitted from the lens 4 can be controlled by adjusting the aspheric coefficient of the outer peripheral portion of the lens 5. For this reason, in the illumination optical system 1, it is possible to easily design the shape of the lens 5 so as to reduce the illuminance unevenness of the irradiated light beam.

  Further, at least one surface of the lens 5 is an aspheric lens, and the negative power increases as the distance from the optical axis increases. Therefore, even after passing through the lens 5, the inner luminous flux 7 and the outer luminous flux 8 It is possible to create many areas where are non-intersecting. In this way, according to the illumination optical system 1, the illumination area can be continuously changed from a narrow range to a wide range while reducing illuminance unevenness of the irradiated light beam.

(Second embodiment)
An illumination optical system 1A according to a second embodiment of the present invention will be described with reference to FIGS. The illumination optical system 1A is partially different from the illumination optical system 1. Therefore, in the following description, the illumination optical system 1A is mainly described in parts different from the illumination optical system 1, and description of parts common to the illumination optical system 1 is omitted or simplified.

  As shown in FIG. 12, the illumination optical system 1 </ b> A has a diffusion sheet 60 for diffusing a light beam on the exit side of the lens 5 of the illumination optical system 1. 4 and 5, the diffusion sheet 60 may be provided instead of the protective lens 21, or the diffusion sheet 60 may be further provided on the exit side of the protective lens 21. Further, the haze value (the degree of diffusion) of the diffusion sheet 60 of the illumination optical system 1A was set to about 35%. Moreover, the illuminance unevenness of the illumination area L4 can be reduced by the diffusion of the light flux in the diffusion sheet 60.

  FIG. 13 shows the far-field light distribution of the illumination optical system 1A at the position (narrow angle position) of the lens 4 shown in FIG. The half-value light distribution angle of the illumination optical system 1A at the position of the lens 4 (narrow angle position) shown in FIG. 12 is 14 degrees. FIG. 14 is a comparative example, and shows a far-field light distribution when the diffusion sheet 60 is removed from the illumination optical system 1A at the position (narrow angle position) of the lens 4 shown in FIG. In the light distribution shown in FIG. 13, it can be seen that the change in the illumination intensity of the light in the vicinity of the optical axis direction is moderated compared to the light distribution shown in FIG.

  FIG. 16 shows the far-field light distribution of the illumination optical system 1A at the position (intermediate angle position) of the lens 4 shown in FIG. The half-value light distribution angle of the illumination optical system 1A at the position of the lens 4 (intermediate angle position) shown in FIG. 15 is 25 degrees. FIG. 17 is a comparative example, and shows a far-field light distribution when the diffusion sheet 60 is removed from the illumination optical system 1A at the position (intermediate angle position) of the lens 4 shown in FIG. In the light distribution shown in FIG. 16, it can be seen that the change in the illumination intensity of the light in the vicinity of the optical axis direction is relaxed and equalized as compared with the light distribution shown in FIG. That is, the illuminance unevenness of the illumination area L5 can be reduced by the diffusion of the light flux in the diffusion sheet 60.

  FIG. 19 shows the far-field light distribution of the illumination optical system 1A at the position (wide angle position) of the lens 4 shown in FIG. The half-value light distribution angle of the illumination optical system 1A at the position of the lens 4 shown in FIG. 18 (wide-angle position) is 36 degrees. FIG. 20 is a comparative example, and shows a far-field light distribution when the diffusion sheet 60 is removed from the illumination optical system 1A at the position of the lens 4 shown in FIG. 18 (wide-angle position). In the light distribution shown in FIG. 19, it can be seen that the change in the illumination intensity of the light in the vicinity of the optical axis direction is moderated as compared with the light distribution shown in FIG. That is, the illuminance unevenness of the illumination area L6 can be reduced by the diffusion of the light flux in the diffusion sheet 60.

  Thus, it can be seen that in the illumination optical system 1A, the change in the illumination intensity of the light in the vicinity of the optical axis direction is moderated at any position of the lens 4 (narrow angle position, intermediate angle position, wide angle position). . Further, the half-value light distribution angle of the illumination optical system 1A is larger than that of the illumination optical system 1. According to this, since it becomes difficult for a region with high illuminance to appear near the center of the illumination region and the change in illuminance in the region other than the center is mitigated, the illumination optical system 1A further includes the illumination optical system 1. The illumination area can be continuously changed from a narrow range to a wide range while reducing illuminance unevenness of the irradiated light beam. Further, according to the illumination optical system 1A, the entire light distribution angle is set to 14 degrees to 36 degrees, which is wider than the entire light distribution angle of the illumination optical system 1 from 13.5 degrees to 32 degrees. According to the illumination optical system 1 </ b> A, the illuminance unevenness of the light flux that easily occurs when the light distribution angle is widened can be solved by the diffusion sheet 60.

(Third embodiment)
An illumination optical system 1B according to a third embodiment of the present invention will be described with reference to FIGS. The illumination optical system 1B is partially different from the illumination optical system 1. Therefore, in the following description, the illumination optical system 1 </ b> B is mainly described with respect to portions that are different from the illumination optical system 1, and descriptions of portions that are common to the illumination optical system 1 are omitted or simplified.

  As shown in FIG. 21, the illumination optical system 1 </ b> B includes a Fresnel lens 70 instead of the lens 5 of the illumination optical system 1. FIG. 22 shows the far-field light distribution of the illumination optical system 1B at the position (narrow angle position) of the lens 4 shown in FIG. The half-value light distribution angle of the illumination optical system 1B at the position of the lens 4 (narrow angle position) shown in FIG. 21 is 15 degrees. In the light distribution shown in FIG. 22, it can be seen that the change in the illumination intensity of the light in the vicinity of the optical axis direction is reduced as compared with the light distribution shown in FIG. 13, for example.

  FIG. 24 shows the far-field light distribution of the illumination optical system 1B at the position (intermediate angle position) of the lens 4 shown in FIG. The half-value light distribution angle of the illumination optical system 1B at the position of the lens 4 (intermediate angle position) shown in FIG. 23 is 23.5 degrees. In the light distribution shown in FIG. 24, it can be seen that the change in illuminance in the vicinity of the optical axis direction is further relaxed, for example, compared to the light distribution shown in FIG.

  FIG. 26 shows the far-field light distribution of the illumination optical system 1B at the position (wide-angle position) of the lens 4 shown in FIG. Note that the half-value light distribution angle of the illumination optical system 1B at the position of the lens 4 (wide-angle position) shown in FIG. 25 is 32 degrees. In the light distribution shown in FIG. 26, for example, it can be seen that the illuminance change in the vicinity of the optical axis direction is further reduced as compared with the light distribution shown in FIG.

  Thus, it can be seen that the illumination optical system 1B further reduces the illuminance change in the vicinity of the optical axis direction at any position (narrow angle position, intermediate angle position, wide angle position) of the lens 4. According to this, in the illumination optical system 1B, a region with higher illuminance is less likely to appear near the center of the illumination region than in the illumination optical system 1A. It is possible to continuously change the illumination area from a narrow range to a wide range while reducing. That is, the illumination optical system 1B can eliminate unevenness in the illuminance of the light beam, which is likely to occur when the light distribution angle is widened, by the Fresnel lens 70, similarly to the illumination optical system 1A. Further, by using the Fresnel lens 70, the illumination optical system 1B can be reduced in size and weight.

(Other embodiments)
The embodiment described above can be variously modified without departing from the gist thereof. For example, the lens 4 may be a positive power Fresnel lens and the lens 5 may be a negative power Fresnel lens. According to this, since the thickness of the lenses 4 and 5 can be reduced, the weight, size and cost of the lighting device 1 can be reduced. Alternatively, only one of the lens 4 and the lens 5 may be a Fresnel lens.

  In addition, the lens 5 itself may be formed of a synthetic resin containing a light scatterer without using the diffusion sheet 60 of the illumination optical system 1A according to the second embodiment described above. According to this, the light beam can be diffused by the lens 5 itself without using the diffusion sheet 60.

  Further, if the angle of the cam groove 14 of the lighting device 11 is constant, the size of the illumination area from the narrow angle to the wide angle changes smoothly as the cam cylinder 15 rotates, but the angle of the cam groove 14 changes. It may be allowed. For example, when a range where light distribution unevenness (illuminance unevenness) is likely to occur is known while the illumination area of the illumination device 11 is changing from a narrow angle to a wide angle, the illumination area rapidly changes in that range. To do. According to this, it is possible to prevent the user from using a range in which unevenness of the light distribution is likely to occur. Further, the illumination area of the narrow-angle to wide-angle is changed stepwise instead of steplessly, and the illumination area is changed by skipping the above-described range where the uneven distribution of light distribution is likely to occur. Good.

  In addition, as for the lens 3, an example in which the inner lens portion 9 and the reflector portion 10 are integrally molded, such as made of polycarbonate, is illustrated. However, by placing a specular reflection plate at a position corresponding to the reflector portion 10, A light beam 8 may be obtained. In this case, the inner light beam 7 can be obtained as a light beam directly emitted from the light source 2. According to this, the lens 3 can be replaced by a single reflector.

DESCRIPTION OF SYMBOLS 1 ... Illumination optical system, 2 ... Light source, 3 ... Lens (1st lens), 4 ... Lens (2nd lens), 5 ... Lens (3rd lens), 6 ... Moving mechanism, 7 ... Inside light beam, 8 ... Outside Luminous flux, 9 ... inner lens, 10 ... reflector part, 11 ... illuminating device, N ... non-intersecting region

Claims (10)

A first lens, a second lens, and a third lens, arranged in order from the light source;
A moving mechanism for moving the second lens along the optical axis direction;
An illumination optical system comprising: The illumination optical system according to claim 1,
The first lens is a lens having a positive power, and the light emitted from the light source is an inner luminous flux including a light beam on an optical axis and an outer luminous flux positioned outside the inner luminous flux, and the inner lens The light beam and the outer light beam are emitted so as to have a non-intersecting region where they do not intersect each other,
The second lens is capable of moving in the optical axis direction in the non-intersecting region, and has an aperture through which the inner luminous flux and the outer luminous flux pass in the non-intersecting region.
An illumination optical system characterized by that. The illumination optical system according to claim 2,
The first lens is
An inner lens arranged on the optical axis and having a positive power to emit the inner luminous flux;
A reflector portion disposed outside the inner lens;
An illumination optical system comprising: The illumination optical system according to claim 2 or 3,
The second lens is
Has positive power,
At least one surface is an aspheric lens,
The area where the outer luminous flux is transmitted is weaker in positive power than the area where the inner luminous flux is transmitted,
An illumination optical system characterized by that. The illumination optical system according to any one of claims 2 to 4,
At least one surface of the third lens is an aspheric lens, and the negative power increases as the distance from the optical axis increases.
An illumination optical system characterized by that. The illumination optical system according to any one of claims 1 to 5,
A means for diffusing light on the exit side of the third lens;
An illumination optical system characterized by that. The illumination optical system according to any one of claims 1 to 5,
The third lens has a light scattering function;
An illumination optical system characterized by that. The illumination optical system according to any one of claims 1 to 5,
Disposing a Fresnel lens on the exit side of the third lens;
An illumination optical system characterized by that. The illumination optical system according to any one of claims 1 to 5,
At least one of the second lens and the third lens is a Fresnel lens;
An illumination optical system characterized by that.   An illumination apparatus comprising the illumination optical system according to claim 1.

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