Optical system and illumination device

Abstract

An optical system according to the present disclosure projects a light beam from a light source onto a projection surface and comprises an optical element having a central portion including an optical axis and an outer portion located farther from the optical axis than the central portion in a first direction orthogonal to the optical axis. A first light beam incident on the central portion from the light source is directed onto a first region on the projection surface, and a second light beam incident on the outer portion from the light source is directed onto a second region on the projection surface, the second region including the first region and having a larger area than that of the first region.

Description

Optical system and lighting device

[0001] The present disclosure relates to an optical system that projects an image and illuminates the periphery of the image. The present disclosure also relates to a lighting device using such an optical system.

[0002] Patent Document 1 discloses a lighting device including an image projection unit that projects an image onto a first region, and a peripheral illumination unit that emits a light flux of peripheral illumination light for illuminating a second region surrounding the first region. The lighting device disclosed in Patent Document 1 provides a smooth illuminance distribution that suppresses uneven illuminance of illumination light around an image by densely arranging light sources, and emits natural illumination light with inconspicuous boundaries by controlling the light distribution of the peripheral illumination light.

[0003] International Publication No. 2018 / 055722

[0004] In the lighting device disclosed in Patent Document 1, central illumination light emitted from a central illumination unit illuminates an image projection area, and the irradiation position of the illumination light is predetermined by a light source and an optical element. The peripheral illumination unit illuminates an image peripheral area surrounding the image projection area. In the peripheral illumination unit, the irradiation range and irradiation position of the illumination light do not change according to the shape and position of the light source image of the image projection unit, and it cannot illuminate the area around an actually projected image. Furthermore, the image projection unit that emits image light, the peripheral illumination unit that emits peripheral illumination light, and the central illumination unit are each configured of separate optical systems, resulting in a large and complicated lighting device.

[0005] The present disclosure provides an optical system capable of illuminating the periphery of an image according to the position and shape of the image while projecting the image. The present disclosure also provides a lighting device using such an optical system.

[0006] An optical system according to one aspect of the present disclosure is an optical system that projects a light flux from a light source onto a projection surface, and includes an optical element having a central portion including an optical axis and an outer portion located farther from the optical axis than the central portion in a first direction orthogonal to the optical axis. A first light flux incident on the central portion from the light source irradiates a first region on the projection surface, and a second light flux incident on the outer portion from the light source irradiates a second region that includes the first region and has a larger area than the first region on the projection surface.

[0007] The illumination device relating to this disclosure comprises a light source and the optical system described above.

[0008] According to this disclosure, it is possible to provide an optical system and illumination device that can project an image while illuminating the area surrounding the image according to the position and shape of the image.

[0009] An explanatory diagram showing the usage of the lighting device according to Embodiment 1. An explanatory diagram showing the image projected onto the projection surface by the lighting device according to Embodiment 1. A layout diagram showing the optical system of Embodiment 1. A plan view showing the image projected onto the projection surface by the lighting device using the optical system of Embodiment 1. A graph showing the illuminance distribution along the A-A line of the image. A plan view of the aperture of the optical system of Embodiment 1 as seen from the optical axis direction. A diagram of transverse aberration in the optical system of Embodiment 1. A layout diagram showing the optical system of Embodiment 2. A layout diagram showing the optical system of Embodiment 3. A plan view of the optical filter of the optical system of Embodiment 3 as seen from the optical axis direction. A layout diagram showing the optical system of Embodiment 4. The image projected onto the projection surface by the lighting device using the optical system of Embodiment 4. Plan view showing the image Plan view showing the optical system of Embodiment 5 Plan view showing the image projected onto the projection surface by the illumination device using the optical system of Embodiment 5 Plan view showing the optical system of Embodiment 6 Plan view showing the optical system of Embodiment 6 Explanation diagram showing the usage of the illumination device according to Embodiment 6 Explanation diagram showing the image projected onto the projection surface by the illumination device according to Embodiment 6 Plan view showing the optical system of Embodiment 7 Explanation diagram showing the usage of the illumination device according to Embodiment 2 Plan view showing the image projected onto the projection surface by the illumination device according to Embodiment 2 Plan view showing the optical system of Embodiment 8 Block diagram showing the illumination device according to Embodiment 3 of this disclosure Block diagram showing the illumination device according to Embodiment 4 of this disclosure

[0010] To provide an illumination optical system that can achieve high illuminance on the projection target and form a projection position and projection area on the projection target according to the position and shape of the light source, critical illumination using an imaging optical system that directly projects the image of the light source onto the projection target is preferable, and various optical systems using critical illumination are available. On the other hand, for the purpose of illuminating a projection target, there is a growing need to illuminate the projection area and the surrounding desired area corresponding to the projection area with a lower intensity than the projection area itself. Furthermore, to improve the quality of the illumination light, the spatial distribution of light around the projection area is important. Spatial distributions that show repeated fluctuations in brightness or extreme step-like changes in spatial intensity distribution are generally undesirable, and a minimum smooth spatial intensity distribution, that is, natural illumination, is required.

[0011] Therefore, the inventors investigated a simple optical system that can project an image while illuminating the area around the image with a naturally smooth intensity distribution according to the position and shape of the image, leading to this disclosure.

[0012] The embodiments will be described in detail below, with reference to the drawings as appropriate. However, unnecessarily detailed explanations may be omitted. For example, detailed explanations of already well-known matters or redundant explanations of substantially identical configurations may be omitted. This is to avoid the following explanation becoming unnecessarily verbose and to facilitate understanding for those skilled in the art.

[0013] The applicant provides the accompanying drawings and the following description so that a person skilled in the art can fully understand the disclosure, and not to limit the subject matter described in the claims.

[0014] Furthermore, in this specification, terms such as "first," "second," etc., are used solely for descriptive purposes and should not be understood as expressing or implying relative importance or ranking of technical features. Features designated as "first" and "second" express or imply that they include one or more such features.

[0015] The optical systems according to each embodiment of this disclosure are used in lighting devices. A lighting device is a device for illuminating an object by irradiating it with light emitted from a light source. The object to be illuminated may consist of a flat surface such as a screen, wall, or floor, or it may consist of a three-dimensional object such as a work of art.

[0016] (Embodiment 1) Embodiment 1 of the present disclosure will be described with reference to Figures 1 to 13.

[0017] Figure 1 is an explanatory diagram showing how to use the lighting device 100 according to Embodiment 1. The lighting device 100 may be placed horizontally on a support base such as a table or on the floor, or it may be suspended from the ceiling and placed horizontally or vertically. The lighting device 100 may also be placed at a predetermined angle to the horizontal or vertical.

[0018] As shown in Figure 1, the lighting device 100 includes an optical system 1 and a light source 2. In Embodiment 1, the light source 2 is composed of an LED (light-emitting diode). The light source may be composed of an OLED or a laser, or it may be composed of a white light source including a blue LED and a yellow phosphor.

[0019] Light source 2, for example, emits image light to project an image. The image may be a video or a still image. The image may include shapes such as signs or scenery, or shapes such as circles or squares.

[0020] Figures 3, 7, 8, 10, 12, 14, and 17 are arrangement diagrams showing the optical system 1 of Examples 1 to 7, respectively. In each figure, the optical axis is in the Z direction (hereinafter referred to as "optical axis direction Z") in the X-Y-Z Cartesian coordinate system, and the arrangement diagram of the optical system 1 is shown as viewed from a direction perpendicular to the Y-Z plane (meridional plane).

[0021] The optical systems 1 of Examples 1 to 7 are composed of optical elements arranged on the optical axis OA extending in the direction of the optical axis Z. Specifically, the optical systems 1 of Examples 1 to 4 and 6 to 7 have lens elements as optical elements. The optical system 1 of Example 5 has mirrors as optical elements. In the optical systems 1 of Examples 1 to 7, the light rays passing through the top surface of each lens element or mirror are defined as the optical axis OA. The direction perpendicular to the optical axis OA and the radial direction K are defined as the direction perpendicular to the optical axis OA.

[0022] As shown in Figure 1, a portion of the light emitted from the light source 2 (first luminous beam S1) is focused by the optical system 1 at a first focusing position P1. The first luminous beam S1 is incident on the central portion of the optical element of the optical system 1 (specifically, the central opening 13 of the aperture ST in Examples 1 to 7), including the optical axis OA. The first luminous beam S1 is focused at the first focusing position P1 by passing through or being reflected from the central portion.

[0023] The projection plane R is a virtual XY plane that includes the first focusing position P1. That is, the first focusing position P1 is a position on the projection plane R. Note that if the object to be illuminated by the illumination device 100 is composed of a plane, the projection plane R may coincide with the object to be illuminated, or it may be offset in the optical axis direction Z relative to the object to be illuminated.

[0024] The remaining light (second luminous beam S2) emitted from the light source 2 is focused by the optical system 1 to a second luminous position P2, which is shifted in the optical axis direction Z relative to the first luminous position P1. That is, the second luminous position P2 is located at a different position in the optical axis direction Z from the first luminous position P1 (i.e., the projection surface R). The second luminous position P2 is far from the projection surface R, and the first luminous position P1 on the projection surface R is closer to the projection surface R than the second luminous position P2. The second luminous beam S2 is incident on the outer portion of the optical element of the optical system 1 (the aperture 13 of the aperture ST in Examples 1 to 7), which is located radially outside the central portion, in the radial direction K away from the optical axis OA. The second luminous beam S2 is focused to the second luminous position P2 by passing through the outer portion or by being reflected from the outer portion.

[0025] In Embodiment 1, the second focusing position P2 is located between the optical element of the optical system 1 (the central aperture 13 of the aperture ST in Embodiments 1 to 7) and the first focusing position P1. The second focusing position P2 is continuously distributed in the optical axis direction Z within a predetermined range between the optical element and the first focusing position P1. Specifically, the second light beam S2 is focused near the optical element when it passes through the radially outer portion of the optical element, and as it moves radially inward, the second focusing position P2 moves from the optical element towards the first focusing position P1.

[0026] The distribution pattern, such as the position and range of the second light-gathering position P2, can be adjusted according to the specifications of the optical elements of the optical system 1.

[0027] In Embodiment 1, the maximum angle at which the rays of the second luminous beam S2 intersect is between 2° and 30°. Specifically, the rays of the second luminous beam S2 that pass through the outermost radial portion of the outer portion 12 intersect at an angle of 2° to 30°. In addition, the spacing between the rays of the second luminous beam S2 increases in the direction away from the optical axis OA. Therefore, in the second region R2 from which the second luminous beam S2 is projected, the brightness decreases towards the radially outward K, achieving a natural blurred light.

[0028] The second focal length D2 between the optical element of the optical system 1 and the second focusing position P2 is smaller than the first focal length D1 between the optical element of the optical system 1 and the first focusing position P1. The second focal length D2 is, for example, 50% or less of the first focal length D1. If the second focusing positions P2 are continuously distributed in the optical axis direction Z, the second focal length D2 may be defined as the distance from the optical element of the optical system 1 to the second focusing position P2 closest to the optical element. More specifically, the second focal length D2 may be defined as the distance between the optical element of the optical system 1 and the position where the light beam passing the radially outermost part of the optical element of the optical system 1 in the second light beam S2 emitted from the light source 2 on the optical axis OA converges and the width of the light beam is smallest.

[0029] Figure 2 is an explanatory diagram showing an image projected onto the projection surface R by the illumination device 100 according to the embodiment. As shown in Figure 2, when light is emitted from the light source 2, a first region R1 is formed on the projection surface R where the first luminous beam S1 is irradiated, and a second region R2 is formed where the second luminous beam S2 is irradiated.

[0030] The first luminous beam S1 is focused at the first focusing position P1, i.e., the projection surface R, and thus projects the light source image of the light source 2 onto the first region R1. The light source image of the light source 2 may have a circular shape, for example, but may be any shape, character, symbol, or any other two-dimensional pattern. The light source image of the light source 2 may also be an image, in which case the image light emitted by the light source 2 may be a moving image or a still image.

[0031] On the other hand, because the focus is off relative to the projection surface R, the second luminous beam S2 spreads radially K with respect to the optical axis OA on the projection surface R. Therefore, the second region R2, which is illuminated by the second luminous beam S2, spreads out relative to the first region R1, which is illuminated by the first luminous beam S1 that is focused on the projection surface R. Specifically, the second region R2 spreads radially K relative to the first region R1 so as to include the area surrounding the first region R1. For this reason, the second luminous beam S2 may be called blurred light.

[0032] More specifically, because the second luminous beam S2 spreads radially K, the second luminous beams S2 emitted from each point of the light source 2 overlap. As a result, the illuminance distribution of the light source image is not easily reflected in the second region R2. In the second region R2, the contours of the light source image and the shapes and patterns contained in the light source image due to the second luminous beam S2 emitted from each point of the light source 2 become difficult for the user to recognize. In other words, the blurred light projected onto the second region R2 has a smooth illuminance distribution. Such a smooth illuminance distribution may also be called an "averaged illuminance distribution."

[0033] Comparing the light projected onto the respective regions R1 and R2, the light projected onto the first region R1 has a difference in illuminance compared to the light projected onto the second region R2. Therefore, the first region R1 forms a boundary J that is recognizable by the user relative to the second region R2. The boundary J corresponds to the light source image and may, for example, be similar to the light source image, or more specifically, it may correspond to the outline of the light source image magnified at a predetermined magnification.

[0034] Furthermore, since the second focusing position P2 is continuously distributed in the optical axis direction Z, the brightness of the first region R1 of the projection surface R illuminated by the second luminous beam S2 can be made uniform, and the illuminance distribution of the second region can be made such that it attenuates as it spreads in the radial direction K.

[0035] In Embodiment 1, the second region R2 includes the first region R1 and has a larger area than the first region R1. The second region R2 includes the entirety of the first region R1.

[0036] The annular region obtained by removing the first region R1 from the second region R2 is defined as the annular region R3. The first luminous beam S1 does not irradiate the annular region R3, and only the second luminous beam S2, which is shifted in focus relative to the projection surface R and spread radially K, irradiates it. Therefore, the maximum illuminance of the annular region R3 is less than the maximum illuminance of the first region R1. In addition, luminous rays emitted from light source 2 or other light sources, which are focused on the projection surface R, may also irradiate the annular region R3.

[0037] (Example 1) Figure 3 is a layout diagram showing the optical system 1 of Example 1. The surface data for Example 1 is shown in the numerical example 1 described later.

[0038] As shown in Figure 3, in Embodiment 1, the optical system 1 includes a plurality of lens elements L1 to L6 and an aperture ST. The plurality of lens elements L1 to L6 are arranged in order from the light source side to the projection surface side. Lens element L1 has a positive meniscus shape with a convex surface facing the projection surface side. Lens element L2 has a positive meniscus shape with a convex surface facing the projection surface side. Lens element L3 has a biconvex shape with convex surfaces facing both the light source side and the projection surface side. Lens element L4 has a negative meniscus shape with a concave surface facing the light source side and a convex surface facing the projection surface side. Lens element L5 has a biconvex shape and has a first transmissive surface T1 on the light source side and a second transmissive surface T2 on the projection surface side. The first transmissive surface T1 and the second transmissive surface T2 have an aspherical shape. Lens element L6 has a negative meniscus shape with a convex surface facing the projection surface side. Lens elements L1 to L6 have, for example, a circular outer shape. The aperture ST has, for example, a circular opening 13, and the outer circumference of the light transmitted through the aperture ST is determined by passing through the opening 13. The opening 13 may have other shapes.

[0039] The aperture ST has an opening 13 which includes a central portion 11 and an outer portion 12 located radially outside the central portion 11. The first light beam S1 passing through the central portion 11 is focused at a first focusing position P1. The second light beam S2 passing through the outer portion 12 is focused at a second focusing position P2.

[0040] The aperture ST is located between lens element L4 and lens element L5.

[0041] Figure 4A is a plan view showing the image projected onto the projection surface R by the illumination device 100 using the optical system 1 of Example 1. Figure 4B is a graph showing the illuminance distribution along the line A-A in Figure 4A.

[0042] Regions R1 and R2 may be defined by the illuminance of the irradiated light. Region R1 may be defined as the region irradiated with light having an illuminance of 1 or more than a first threshold, and region R2 may be defined as the region irradiated with light having an illuminance of 2 or more than a second threshold. The first threshold may be an illuminance of 50% or more of the maximum illuminance of region R1. The second threshold may be lower than the first threshold and may be an illuminance of 1% to 30% of the maximum illuminance of region R1. The maximum illuminance of region R1 may be, for example, the illuminance at the optical axis OA (center of the image) on the projection surface R.

[0043] Referring to Figures 4A and 4B, we will now describe the case where the first region R1 is defined as a region irradiated with light having an illuminance of 80% or more of the maximum illuminance. The second region R2 includes a point P11 located radially outward from the outer periphery of the first region R1 at a distance of 1 / 100th of the first focal length D1. The illuminance of the second region R2 at point P11 is 1% to 30% of the maximum illuminance of the first region R1. In Example 1, when the first focal length D1 is 2000 mm, the illuminance of the second region R2 at point P11 is 1.4% of the maximum illuminance of the first region R1.

[0044] When comparing the sizes of the regions R1 and R2 defined as described above, as shown in FIG. 4A, the second region R2 extends outward from the outer periphery of the first region R1 by a distance D5 in the radial direction K. The distance D5 is, for example, not less than 1 / 100 times and not more than 1 / 5 times the first focal length D1. In the first embodiment, when the first focal length D1 is 2000 mm, the second region R2 extends outward from the outer periphery of the first region R1 by 100 mm in the radial direction K.

[0045] The size (that is, the distance D3 in the radial direction K) and shape of the first region R1 are determined by the size and shape of the light source image formed by the light source 2. Note that the size of the first region R1 may be adjusted by adjusting the distance between the light source 2 and the optical system 1 on the optical axis OA.

[0046] The size (that is, the distance D4 in the radial direction K) and shape of the second region R2 are also determined by the size and shape of the light source image formed by the light source 2. On the other hand, the size of the second region outside the outer periphery of the first region R1 (that is, the distance D5 in the radial direction K) is determined by the optical system 1, and remains constant even if the size or shape of the light source image formed by the light source 2 changes.

[0047] Further, the gradient of the illuminance distribution may be calculated, a point at which the gradient exceeds a predetermined value from the optical axis OA toward the radially outer side may be specified, and a region inside that point may be defined as the first region R1.

[0048] By defining the regions R1 and R2, the light beams irradiated to the respective regions can be defined as the first light beam S1 and the second light beam S2. The central portion 11 and the outer portion 12 can be defined by specifying the portions of the opening 13 of the stop ST through which the defined light beams S1 and S2 respectively pass.

[0049] FIG. 5 is a plan view of the stop ST as viewed from the optical axis direction Z. As shown in FIG. 5, when viewed from the optical axis direction Z, the opening 13 of the stop ST includes a first stop region R11 concentric with the opening 13, and a second stop region R12 outside the first stop region R11. The area of the first stop region R11 is, for example, not less than 5% and not more than 80% of the area of the opening 13.

[0050] Returning to FIG. 3, the light beam passing through the first stop region R11 may be defined as the first light beam S1, and the light beam passing through the second stop region R12 may be defined as the second light beam S2.

[0051] Furthermore, the extent of the spread of the second region R2 may be defined by the passage area in the aperture 13. The second light beam S2 that passes in contact with the edge of the aperture ST defining the aperture 13 and irradiates the second region R2 is irradiated on the projection surface R at a position radially K away from the outer periphery of the first region R1 at a distance D5 (see Figure 4A). The distance D5 is, for example, 1 / 100 or more of the first focal length D1 to the first focusing position P1. In Embodiment 1, if the first focal length D1 is 2000 mm, the second light beam S2 that passes in contact with the edge of the aperture ST is irradiated at a position radially K away from the outer periphery of the first region R1 at a distance of 40 mm or more. Specifically, if the first focal length D1 is 2000 mm, the second light beam S2 that passes in contact with the edge of the aperture ST may be irradiated at a position radially K away from the outer periphery of the first region R1 at a distance of 150 mm or 400 mm.

[0052] Lens elements L3 and L4 perform a function to reduce chromatic aberration. When chromatic aberration occurs in the optical system 1, color fringing occurs in the outer periphery of the second region R2, making it difficult to naturally illuminate the periphery of the image. By reducing chromatic aberration with lens elements L3 and L4, the color fringing in the outer periphery of the second region R2 can be reduced. Lens elements L3 and L4 are mainly composed of different materials and have different Abbe numbers or refractive indices. Lens element L3 has a higher Abbe number or a lower refractive index than lens element L4. Note that the fact that they are mainly composed of different materials means that a common material may be added to lens elements L3 and L4.

[0053] Figure 6 is a lateral aberration diagram of the optical system 1 of Example 1. (A), (B), (C), (D), and (E) in Figure 6 show the lateral aberration diagrams of the tangential (meridional) plane and sagittal plane at positions shifted from the center in the Y direction, respectively.

[0054] The lens element L3 only needs to have at least one convex surface, and may have a flat surface on the opposite side of the convex surface, or it may have a concave surface with less power than the convex surface.

[0055] (Example 2) Figure 7 is a layout diagram showing the optical system 1 of Example 2. The surface data for Example 2 is shown in the numerical example 2 described later.

[0056] As shown in Figure 7, in Embodiment 2, the optical system 1 includes a plurality of lens elements L1 to L6 and an aperture ST. The plurality of lens elements L1 to L6 are arranged in order from the light source side to the projection surface side. Lens element L1 has a positive meniscus shape with a convex surface facing the projection surface side. Lens element L2 has a positive meniscus shape with a convex surface facing the projection surface side. Lens element L3 has a biconvex shape with convex surfaces facing both the light source side and the projection surface side. Lens element L4 has a biconcave shape with concave surfaces facing both the light source side and the projection surface side. Lens element L5 has a biconvex shape and has a first transmissive surface T1 on the light source side and a second transmissive surface T2 on the projection surface side. The first transmissive surface T1 and the second transmissive surface T2 have an aspherical shape. Lens element L6 has a negative meniscus shape with a convex surface facing the projection surface side. Lens elements L1 to L6 have, for example, a circular outer shape. The aperture ST has, for example, a circular opening 13, and the outer circumference of the light transmitted through the aperture ST is determined by passing through the opening 13.

[0057] The aperture 13 of the aperture ST has a central portion 11 and an outer portion 12. The first light beam S1 passing through the central portion 11 is focused at a first focusing position P1. The second light beam S2 passing through the outer portion 12 is focused at a second focusing position P2.

[0058] The aperture ST is located between lens element L4 and lens element L5.

[0059] (Example 3) Figure 8 is a layout diagram showing the optical system 1 of Example 3. The surface data for Example 3 is shown in the numerical Example 3 described later.

[0060] As shown in Figure 8, in Embodiment 3, the optical system 1 includes a plurality of lens elements L1, L2, L5, L6, an aperture ST, and an optical filter OF. The plurality of lens elements L1, L2, L5, L6 are arranged in order from the light source side to the projection surface side. Lens element L1 has a plano-convex shape with its convex surface facing the projection surface side. Lens element L2 has a plano-convex shape with its convex surface facing the projection surface side. Lens element L5 has a biconvex shape and has a first transmissive surface T1 on the light source side and a second transmissive surface T2 on the projection surface side. The first transmissive surface T1 has a spherical shape, and the second transmissive surface T2 has an aspherical shape. Lens element L6 has a negative meniscus shape with its convex surface facing the projection surface side. Lens elements L1, L2, L5, L6 have, for example, a circular outer shape. The aperture ST has, for example, a circular opening 13, and the outer circumference of the light transmitted through the aperture ST is determined by passing through the opening 13.

[0061] The aperture 13 of the aperture ST has a central portion 11 and an outer portion 12. The first light beam S1 passing through the central portion 11 is focused at a first focusing position P1. The second light beam S2 passing through the outer portion 12 is focused at a second focusing position P2.

[0062] The aperture ST is located between lens elements L2 and L5. The aperture ST may further have an AR coating.

[0063] The optical filter OF is an annular filter positioned on the light source side of the aperture ST, which absorbs or reflects short-wavelength light and transmits other light. When viewed from the optical axis direction Z, the optical filter OF overlaps with the outer portion 12 of the lens element L5. Specifically, the optical filter OF overlaps with a part of the outer portion 12 of the lens element L5.

[0064] In Example 3, the optical filter OF is provided by coating the light source side surface of the aperture ST, but it may also be provided away from the surface of the aperture ST, or it may be placed between other elements.

[0065] Figure 9 is a plan view of the optical filter OF as seen from the optical axis direction Z. As shown in Figure 9, the optical filter OF has two concentrically arranged annular portions 14 and 15, with the first portion 14 located radially outward of the second portion 15. The dotted line in Figure 9 indicates the effective diameter of the aperture ST. The first portion 14 transmits light having a wavelength of 550 nm or longer. The second portion 15 transmits light having a wavelength of 470 nm or longer. In Embodiment 3, portions 14 and 15 are provided integrally, but they may be configured as separate components.

[0066] In Example 3, an example was described in which the optical filter OF has two parts 14 and 15 having different characteristics, but the optical filter OF is not limited to this. The optical filter OF may have three or more annular parts having different characteristics.

[0067] (Example 4) Figure 10 is a layout diagram showing the optical system 1 of Example 4. The surface data for Example 4 is shown in the numerical example 4 described later.

[0068] As shown in Figure 10, in Embodiment 4, the optical system 1 includes one lens element L5 and an aperture ST. The lens element L5 has a biconvex shape and has a first transmissive surface T1 on the light source side and a second transmissive surface T2 on the projection surface side. The first transmissive surface T1 and the second transmissive surface T2 have a spherical shape. The lens element L5 has, for example, a circular outer shape. The aperture ST has, for example, a circular opening 13, and the outer circumference of the light transmitted through the aperture ST is determined by passing through the opening 13.

[0069] The aperture 13 of the aperture ST has a central portion 11 and an outer portion 12. The first light beam S1 passing through the central portion 11 is focused at a first focusing position P1. The second light beam S2 passing through the outer portion 12 is focused at a second focusing position P2.

[0070] The aperture ST is located between the light source 2 and the lens element L5.

[0071] Figure 11 is a plan view showing the image projected onto the projection surface R by the illumination device 100 using the optical system 1 of Example 4. The size and illuminance of regions R1 and R2 in Figure 11 may differ from those of regions R1 and R2 in Figure 4A of Example 1.

[0072] (Example 5) Figure 12 is a layout diagram showing the optical system 1 of Example 5. The surface data for Example 5 is shown in the numerical example 5 described later.

[0073] As shown in Figure 12, in Embodiment 5, the optical system 1 includes one mirror M1 and an aperture ST. The mirror M1 has a first reflective surface T11. The first reflective surface T11 has a concave shape when viewed from the side on which the light beam is incident on and reflected by the first reflective surface T11. Specifically, the first reflective surface T11 has an aspherical shape. The mirror M1 has, for example, a circular outer shape. The aperture ST has, for example, a circular opening 13, and the outer circumference of the light transmitted through the aperture ST is determined by passing through the opening 13.

[0074] The aperture 13 of the aperture ST has a central portion 11 and an outer portion 12. The first light beam S1 passing through the central portion 11 is focused at a first focusing position P1. The second light beam S2 passing through the outer portion 12 is focused at a second focusing position P2.

[0075] The aperture ST is located between the light source 2 and the mirror M1.

[0076] Figure 13 is a plan view showing the image projected onto the projection surface R by the illumination device 100 using the optical system 1 of Example 5. Comparing Figure 13 with Figure 4A of Example 1, it can be seen that even when a common light source 2 is used, the size and illuminance of regions R1 and R2 may differ.

[0077] (Example 6) Figure 14 is a layout diagram showing the optical system 1 of Example 6. The surface data for Example 6 will be shown in the numerical example 6 described later.

[0078] As shown in Figure 14, in Embodiment 6, the optical system 1 includes a plurality of lens elements L1, L3 to L6, and an aperture ST. The plurality of lens elements L1, L3 to L6 are arranged in order from the light source side to the projection surface side. Lens element L1 has a plano-convex shape with a convex surface facing the projection surface side. Lens element L3 has a biconvex shape with convex surfaces facing both the light source side and the projection surface side. Lens element L4 has a plano-concave shape with a concave surface facing the light source side. Lens element L5 has a biconvex shape and has a first transmissive surface T1 on the light source side and a second transmissive surface T2 on the projection surface side. The first transmissive surface T1 and the second transmissive surface T2 have an aspherical shape. Lens element L6 has a negative meniscus shape with a convex surface facing the projection surface side. Lens elements L1, L3 to L6 have, for example, a circular outer shape. The aperture ST has, for example, a circular opening 13, and the outer circumference of the light transmitted through the aperture ST is determined by passing through the opening 13.

[0079] Lens element L1 is an element that focuses light and may be called a focusing lens. Lens elements L3 and L4 are elements that correct chromatic aberration and may be called chromatic aberration correction lenses. Lens element L5 is an element that corrects aberration and may be called an aberration correction lens. Lens element L6 is an element that reduces the image plane shift of light rays that pass through different positions in the radial direction K and may be called an image plane correction lens.

[0080] The aperture ST is located between lens element L4 and lens element L5.

[0081] In Embodiment 6, the light source 2 has an emission unit 2A located on the optical axis OA and emitting light along the optical axis OA, and an emission unit 2B that emits light from a position at a distance d in the radial direction K from the optical axis OA. The light emitted from emission units 2A and 2B may be referred to as on-axis light SA and off-axis light SB, respectively. The light source 2 may also have emission units other than emission units 2A and 2B that emit light.

[0082] Figure 15 is an explanatory diagram showing how the lighting device 100 according to Embodiment 6 is used. Figure 16 is an explanatory diagram showing the image projected onto the projection surface R by the lighting device 100 according to Embodiment 6.

[0083] As shown in Figures 15 and 16, the on-axis light SA emitted from the emission unit 2A and the off-axis light SB emitted from the emission unit 2B are projected onto the projection surface R at different positions in the radial direction K. Specifically, the on-axis light SA and the off-axis light SB each form both the first region R1, R21 and the second region R2, R22.

[0084] The first luminous beam S1 emitted from the emission unit 2A enters the central portion of the aperture ST's opening 13, including the optical axis OA, is focused at the first focusing position P1, and projected onto the first region R1. The second luminous beam S2 emitted from the emission unit 2A enters the outer portion of the aperture ST's opening 13, located radially outside the central portion, is focused at the second focusing position P2, and projected onto the second region R2. The first luminous beam S11 emitted from the emission unit 2B enters the central portion of the aperture ST's opening 13, including the optical axis OA, is focused at the first focusing position P1, and projected onto the first region R21. The second luminous beam S12 emitted from the emission unit 2B enters the outer portion of the aperture ST's opening 13, located radially outside the central portion, is focused at the second focusing position P2, and projected onto the second region R22.

[0085] The second regions R2 and R22 are located at a distance from each other, but may overlap.

[0086] Returning to Figure 14, we will explain the lens elements L1, L5, and L6 in more detail.

[0087] The lens element L1 (focusing lens) reduces the divergence angle of the light taken in from the light source 2 for both the on-axis light SA and the off-axis light SB, while generating aberrations between the light beam that passes through the central part and the light beam that passes through the outer part, thereby generating image light and blurred light.

[0088] If La is the distance between the light source 2 and the lens element L1, and t is the thickness of the lens element L1, then the effective diameter φ1 of the lens element L1 satisfies the following equation (1).

[0089]

[0090] This configuration generates aberrations to produce blurred light, while also capturing at least 15% of the light from light source 2 and a total divergence angle of 47.2 degrees or more, thereby achieving bright illumination.

[0091] Furthermore, if the lens element L1 is a glass spherical lens, and the radius of curvature on the light source side is r1 and the radius of curvature on the projection surface side is r2, then the effective diameter φ1 of the lens element L1 satisfies equation (1) in addition to the following equation (2).

[0092]

[0093] This configuration allows for efficient utilization of light from the light source 2, while also making it easier to secure the edge of the lens element L1, simplifying the manufacturing of the lens element L1 and improving the heat resistance of the lens element L1 to the light source 2.

[0094] The lens element L5 (aberration-correcting lens) is an aspherical lens having at least one convex surface. The convex surface has a radius of curvature r3 and an effective diameter φ3. The sag amount z1 of the lens element L5 at the effective diameter φ3 is smaller than the radius of curvature r3. Specifically, the sag amount z1 of the lens element L5 at the effective diameter φ3 satisfies the following equation (3).

[0095]

[0096] This configuration makes the sag amount z1 at the effective diameter end smaller than the sag amount at the radius of curvature r3, thereby correcting the difference in aberration between the on-axis light SA and the off-axis light SB. Consequently, the difference in the size of the blurred light caused by the on-axis light SA and the off-axis light SB can be reduced.

[0097] Furthermore, if α1 is the angle between the downward ray of the on-axis light SA and the optical axis OA at the incident surface of the lens element L5, and α2 is the angle between the downward ray of the off-axis light SB and the optical axis OA, then the distance Lb between the lens element L5 and the aperture ST satisfies the following equation (4). Note that when the output section 2B is located at a distance d from the optical axis OA only in the +Y direction and not in the X direction, the downward ray is the ray that passes through the lower end (the -Y side end) of the aperture ST. In contrast, the upward ray is the ray that passes through the upper end (the +Y side end) of the aperture ST.

[0098]

[0099] With this configuration, the larger the light emission size of light source 2 corresponding to distance d, the larger the distance Lb between the lens element L5 and the aperture ST. By separating the lens element L5 and the aperture ST, the difference in aberration between the on-axis light SA and the off-axis light SB can be efficiently corrected. Furthermore, by correcting the difference in aberration between the upper and lower rays of the off-axis light SB, a uniform blurred light can be achieved on both sides.

[0100] The lens element L6 (image plane correction lens) is an aspherical lens having at least one concave surface. The concave surface has a radius of curvature r4 and an effective diameter φ4. The sag amount z2 of the lens element L6 at the effective diameter φ4 satisfies the following equation (5).

[0101]

[0102] This configuration makes it possible to reduce the difference in image planes (i.e., imaging positions in the optical axis direction Z) between the on-axis light SA and the off-axis light SB. Therefore, even when the off-axis emitter 2B is illuminated, the same imaging performance as when the on-axis emitter 2A is illuminated can be achieved on the projection surface R.

[0103] Furthermore, increasing the sag amount z2 can improve the imaging performance of off-axis light SB, particularly in the sagittal direction. As a result, it is possible to project image light with uniform performance over a wider area. Note that the sagittal direction is the X direction in Figure 14.

[0104] It is desirable to arrange the lens elements L1 (focusing lens), L5 (aberration correction lens), and L6 (image plane correction lens) in order from the light source side to the projection plane side. By placing lens element L1 closest to the light source, the light beam from light source 2 can be captured, increasing the light utilization efficiency of the optical system 1. By placing lens element L5 closer to the projection plane than lens element L1, the aberrations of on-axis light SA and off-axis light SB generated by lens element L1 can be efficiently corrected. By placing lens element L6 closest to the projection plane, the light beams of on-axis light SA and off-axis light SB can be placed at the furthest distance from each other, efficiently reducing the difference in the image plane.

[0105] Lens element L3 may be a convex lens having at least one convex surface, and lens element L4 may be a concave lens having at least one concave surface. In this case, lens elements L3 and L4 may have different refractive indices or Abbe numbers. For example, lens element L3 may have a larger Abbe number or a smaller refractive index than lens element L4.

[0106] (Example 7) Figure 17 is a layout diagram showing the optical system 1 of Example 7. The surface data for Example 7 is shown in the numerical example 7 described later.

[0107] As shown in Figure 17, in Embodiment 7, the optical system 1 includes a plurality of lens elements L1, L5, L6 and an aperture ST. The plurality of lens elements L1, L5, L6 are arranged in order from the light source side to the projection surface side. Lens element L1 has a plano-convex shape with its convex surface facing the projection surface side. Lens element L5 has a biconvex shape and has a first transmissive surface T1 on the light source side and a second transmissive surface T2 on the projection surface side. The first transmissive surface T1 and the second transmissive surface T2 have an aspherical shape. Lens element L6 has a negative meniscus shape with its convex surface facing the projection surface side. Lens elements L1, L5, L6 have, for example, a circular outer shape.

[0108] The aperture ST is located between lens element L1 and lens element L5.

[0109] (Effects) Next, the conditions that the optical system 1 according to this disclosure can satisfy will be explained. Although multiple conditions are specified for the optical system according to each embodiment, the corresponding effects can be obtained by satisfying all of these multiple conditions, or by satisfying the individual conditions.

[0110] The optical system 1 according to Examples 1 to 7 is an optical system that projects a light beam from a light source onto a projection surface. The optical system 1 includes an optical element (the aperture 13 of the aperture ST in Examples 1 to 7) having a central portion 11 including the optical axis OA and an outer portion 12 that is further from the optical axis OA than the central portion 11 in the radial direction K (first direction) perpendicular to the optical axis OA. The first light beam S1 incident from the light source 2 onto the central portion 11 irradiates a first region R1 on the projection surface R. The second light beam S2 incident from the light source 2 onto the outer portion 12 irradiates a second region R2 on the projection surface R that includes the first region R1 and has a larger area than the first region R1.

[0111] With this configuration, a predetermined two-dimensional pattern of light source image is projected by the first luminous beam S1, while the second luminous beam S2 illuminates the second region R2, which includes the first region R1 and extends beyond the first region R1. Therefore, the area around the image can be naturally illuminated according to the position and shape of the light source image. For example, the first luminous beam S1 can be focused onto the projection surface R to realize a display of shapes or characters, while the area around the display can be naturally illuminated by the second luminous beam S2. Furthermore, even if foreign matter adheres to the light source 2 and the image of the foreign matter is projected onto the projection surface R by the first luminous beam S1, the image of the foreign matter becomes less noticeable because the second luminous beam S2 illuminates the second region R2, which includes the first region R1.

[0112] In the optical system 1 according to Examples 1 to 7, the first region R1 corresponds to the light source image of the light source 2, and a boundary J is formed between it and the second region R2 because its illuminance is higher than or equal to a predetermined value than that of the second region R2.

[0113] With this configuration, the user can recognize the light source image even when the second luminous beam S2 is irradiated onto the second region R2.

[0114] In the optical system 1 according to Examples 1 to 7, blurred light obtained by averaging the light source image of the light source 2 is projected onto the second region R2.

[0115] This configuration makes it easy to naturally illuminate the area around the light source image.

[0116] In the optical system 1 according to Examples 1 to 7, the light source image is an image, the image is projected onto the first region R1, and blurred light with an averaged illuminance distribution of the image is projected onto the second region R2.

[0117] This configuration makes it easy to project a light source image while naturally illuminating the area surrounding the light source image.

[0118] In the optical system 1 according to Examples 1 to 7, in the optical axis direction Z (second direction) along which the optical axis OA extends, the first focusing position P1 of the first light beam S1 by the optical element is different from the second focusing position P2 of the second light beam S2 by the optical element. The distance between the second focusing position P2 and the optical element is 50% or less of the distance between the first focusing position P1 and the optical element.

[0119] With this configuration, the second luminous beam S2 becomes a blurred light, making it easy to naturally illuminate the area around the image with the second luminous beam S2. In addition, the structure of the optical system 1 is simpler compared to a configuration in which the distance between the second focusing position P2 and the light source 2 is greater than the distance between the first focusing position P1 and the light source 2.

[0120] In the optical system 1 according to Examples 1 to 7, the second focusing position P2 is continuously distributed in the direction of the optical axis Z. On the projection surface R, the spacing between the second luminous beams S2 increases in the direction away from the optical axis OA in the radial direction K.

[0121] With this configuration, the brightness from the second luminous beam S2 decreases towards the radially outward direction K, resulting in a natural blurred light.

[0122] The optical system 1 according to Embodiment 1 further comprises an aperture ST disposed between the light source 2 and the optical element (lens element L5 of Embodiment 1). When viewed from the optical axis direction Z, the second light beam S2, which is in contact with the edge defining the opening 13 of the aperture ST, irradiates the projection surface R at a position radially K away from the first region R1 by a first distance (distance D4). The first distance (distance D4) is 1 / 100 times or more the distance from the optical element (lens element L5 of Embodiment 1) to the first focusing position P1 (first focal length D1).

[0123] This configuration allows the second region R2, which extends beyond the first region R1, to be illuminated, making it easier to naturally illuminate the periphery of the image with the second light beam S2.

[0124] In the optical system 1 according to Example 1, the distance D4 is 1 / 5 times or less the distance from the lens element L5 to the first focusing position P1.

[0125] This configuration makes it even easier to naturally illuminate the area around the image with the second luminous beam S2.

[0126] In the optical system 1 according to Examples 1 to 3, the optical elements of Examples 1 to 3 have lenses that transmit light from the light source 2.

[0127] With this configuration, by passing light through the lens element L5, the second luminous beam S2 becomes blurred light with the desired characteristics, making it easy to naturally illuminate the periphery of the image with the second luminous beam S2.

[0128] In the optical system 1 according to Examples 1 to 3, the optical elements of Examples 1 to 3 have aspherical lenses that transmit light from the light source 2.

[0129] With this configuration, by passing light through the lens element L5, the second luminous beam S2 becomes blurred light with the desired characteristics, making it even easier to naturally illuminate the periphery of the image with the second luminous beam S2.

[0130] The optical system 1 according to Examples 6 to 7 includes at least a condensing lens (lens element L1 in Examples 6 to 7), an aberration correction lens (lens element L5 in Examples 6 to 7), and an image plane correction lens (lens element L6 in Examples 6 to 7).

[0131] With this configuration, when the light source 2 emits light from a position radially K away from the optical axis OA, blurred light is generated, and the difference in the magnitude of the blurred light between the on-axis light SA and the off-axis light SB is corrected, thereby reducing the difference in imaging performance between the on-axis light SA and the off-axis light SB.

[0132] In the optical system 1 according to Examples 6 to 7, if La is the distance between the light source 2 and the condensing lens, and t is the thickness of the condensing lens, then the effective diameter φ1 of the condensing lens satisfies the following relation (6).

[0133]

[0134] This configuration generates aberrations to create blurred light, while also allowing more light to be taken in from light source 2, resulting in brighter illumination.

[0135] In the optical system 1 according to Examples 6 to 7, the condensing lens is a spherical lens having radii of curvature r1 and r2, and the effective diameter φ1 of the condensing lens satisfies the following relational expression (7).

[0136]

[0137] This configuration allows for efficient utilization of light from light source 2 while facilitating the manufacture of focusing lenses.

[0138] In the optical system 1 according to Examples 6 to 7, an aperture ST is further provided, which is positioned between the condensing lens and the aberration correction lens. The aberration correction lens is an aspherical lens having at least one convex surface having a radius of curvature r3 and an effective diameter φ3. The sag amount z1 of the aberration correction lens at the effective diameter φ3 satisfies the following relation (8).

[0139]

[0140] Light source 2 emits on-axial light SA along the optical axis OA, and off-axial light SB from a position radially distanced d from the optical axis OA. At the incident surface of the aberration correction lens, the under-ray of the on-axial light SA passing through the lower end of the aperture ST forms an angle α1 with the optical axis OA, and the under-ray of the off-axial light SB passing through the lower end of the aperture ST forms an angle α2 with the optical axis OA. The distance Lb between the aberration correction lens and the aperture ST satisfies the following relation (9).

[0141]

[0142] This configuration reduces the sag amount z1 at the effective diameter end, corrects the difference in aberrations between the on-axis light SA and the off-axis light SB, and efficiently corrects the difference in aberrations between the on-axis light SA and the off-axis light SB by increasing the distance Lb.

[0143] In the optical system 1 according to Examples 6 to 7, the image plane correction lens is an aspherical lens having at least one concave surface having a radius of curvature r4 and an effective diameter φ4. The sag amount z2 of the image plane correction lens at the effective diameter φ4 satisfies the following relation (10).

[0144]

[0145] This configuration makes it possible to reduce the difference in imaging performance between on-axis light SA and off-axis light SB.

[0146] The optical system 1 according to Example 6 further comprises a convex lens (lens element L3) having at least one convex surface and a concave lens (lens element L4) having at least one concave surface. The convex lens and the concave lens have different refractive indices or Abbe numbers.

[0147] This configuration makes it possible to suppress the coloration of light in the outer periphery of the second region R2.

[0148] In the optical system 1 according to Example 6, the convex lens and concave lens are arranged in that order from the light source. The convex lens has a larger Abbe number or a smaller refractive index than the concave lens.

[0149] This configuration further suppresses the coloration of light in the outer periphery of the second region R2.

[0150] The optical system 1 according to Embodiment 3 further includes an annular optical filter OF positioned between the light source 2 and the image plane correction lens, which overlaps with a part of the outer portion 12 when viewed from the optical axis direction Z. The optical filter OF absorbs or reflects short-wavelength light.

[0151] This configuration makes it possible to suppress the coloration of light in the outer periphery of the second region R2.

[0152] The lighting device 100 according to Examples 1 to 7 comprises a light source 2 and an optical system 1.

[0153] With this configuration, the first luminous beam S1 projects an image of a predetermined two-dimensional pattern, while the second luminous beam S2 naturally illuminates the area around the image.

[0154] This disclosure is not limited to the embodiments described above, and can be implemented in various other forms.

[0155] Furthermore, the lens elements L1 to L6 or the mirror M1 may have an external shape other than a circle, such as a square, and may have notches or protrusions in part of their external shape. In this case, the "radial direction K" may be referred to as the "first direction".

[0156] In Embodiment 1, an example was described in which the second focusing position P2 is located between the light source 2 and the first focusing position P1, but the invention is not limited to this. The second focal length D2 may be longer than the first focal length D1.

[0157] In Examples 1 to 7, the aperture ST was described as being provided independently of the surface of the optical element, but the invention is not limited to this. The aperture ST may be integrally formed with the surface of the optical element, for example, a surface that determines the outer circumference of the light beam may be provided on the surface of the optical element. In other words, the surface of the optical element and the aperture ST may be a common surface.

[0158] (Numerical Example 1) For the optical system of Numerical Example 1 (corresponding to Example 1), surface data is shown in Table 1 and aspherical shape data is shown in Table 2. In Table 1 and the following tables, surface numbers are assigned sequentially from the light source 2 toward the projection surface R.

[0159]

[0160]

[0161] (Numerical Example 2) For the optical system of Numerical Example 2 (corresponding to Example 2), the surface data is shown in Table 3 and the aspherical shape data is shown in Table 4.

[0162]

[0163]

[0164] (Numerical Example 3) For the optical system of Numerical Example 3 (corresponding to Example 3), the surface data is shown in Table 5 and the aspherical shape data is shown in Table 6.

[0165]

[0166]

[0167] (Numerical Example 4) For the optical system of Numerical Example 4 (corresponding to Example 4), the surface data is shown in Table 7.

[0168]

[0169] (Numerical Example 5) For the optical system of Numerical Example 5 (corresponding to Example 5), the aspherical shape data of the first reflective surface T11 is shown in Table 8.

[0170]

[0171] (Numerical Example 6) For the optical system of Numerical Example 6 (corresponding to Example 6), the surface data is shown in Table 9 and the aspherical shape data is shown in Table 10.

[0172]

[0173]

[0174] (Numerical Example 7) For the optical system of Numerical Example 7 (corresponding to Example 7), the surface data is shown in Table 11 and the aspherical shape data is shown in Table 12.

[0175]

[0176]

[0177] (Embodiment 2) Hereinafter, Embodiment 2 of the present disclosure will be described with reference to Figures 18 to 20. In Embodiment 2, the differences from Embodiment 1 will be mainly described, and explanations that overlap with Embodiment 1 will be omitted. In Embodiment 2, components that are the same as or equivalent to those in Embodiment 1 will be denoted by the same reference numerals.

[0178] Figure 18 is an explanatory diagram showing the usage of the illumination device 200 according to Embodiment 2, and shows the focusing positions P1 and P22. As shown in Figure 18, the illumination device 200 includes an optical system 201 and a light source 2. A portion of the light emitted from the light source 2 (first luminous beam S1) is focused at the first focusing position P1 by the central portion of the optical element (lens element L25 of Embodiment 8) of the optical system 201. The remaining light emitted from the light source 2 (second luminous beam S22) is focused at a second focusing position P22, which is different from the first focusing position P1 in the optical axis direction Z, by the outer portion of the optical element (lens element L25 of Embodiment 8) of the optical system 201. The second focusing position P22 is far from the projection surface R, and the first focusing position P1 on the projection surface R is closer to the projection surface R than the second focusing position P22.

[0179] In Embodiment 2, the second focusing position P22 is located between the optical element of the optical system 201 (the lens element L25 in Embodiment 8) and the first focusing position P1. In Embodiment 8, the second focusing position P22 is distributed over a narrower range in the optical axis direction Z than the second focusing position P2 in Embodiment 1, depending on the specifications of the optical element of the optical system 201 described later. The second focusing position P22 may be a single point.

[0180] The second focal length D22 between the optical elements of the optical system 201 and the second focusing position P22 is smaller than the first focal length D1 between the optical elements of the optical system 201 and the first focusing position P1, for example, it is 50% or less of the first focal length D1.

[0181] Figure 19 is a plan view showing the image projected onto the projection surface R by the illumination device 200 using the optical system 201. As shown in Figure 19, when light is emitted from the light source 2, a first region R1 is formed on the projection surface R where the first luminous beam S1 is irradiated, and a second region R22 is formed where the second luminous beam S22 is irradiated.

[0182] The first luminous beam S1 is focused at the first focusing position P1, i.e., the projection surface R, and thus projects the optical image of the light source 2 onto the first region R1.

[0183] Because the focal point is offset from the projection surface R, the second luminous beam S22 spreads radially K with respect to the optical axis OA on the projection surface R. Therefore, the second region R22 irradiated by the second luminous beam S22 includes a region that is radially K away from the first region R1. In Embodiment 2, the second region R22 is an annular region that is radially K away from the outer circumference of the first region R1. There is a gap between the inner circumference of the second region R22 and the outer circumference of the first region R1.

[0184] Furthermore, depending on the size of the light source 2, the second region R22 may include the first region R1. Specifically, as the light source 2 increases in size, the second region R22 expands radially inward and comes to include the first region R1.

[0185] For example, in Embodiment 8 described later, when the light source size is greater than φ0.2 mm, the second region R22 includes a part of the first region R1, and when the light source size is greater than φ0.4 mm, the second region R22 includes the entirety of the first region R1.

[0186] (Example 8) Figure 20 is a layout diagram showing the optical system 201 of Example 8. The surface data for Example 8 is shown in the numerical example 8 described later.

[0187] As shown in Figure 20, the optical system 201 includes a plurality of lens elements L21 to L26 and an aperture ST. Lens element L21 has a positive meniscus shape with its convex surface facing the projection surface. Lens element L22 has a positive meniscus shape with its convex surface facing the projection surface. Lens element L23 has a biconvex shape. Lens element L24 has a negative meniscus shape with its concave surface facing the light source and its convex surface facing the projection surface. Lens element L25 has a biconvex shape and has a first transmissive surface T21 on the light source side and a second transmissive surface T22 on the projection surface side. The first transmissive surface T21 and the second transmissive surface T22 have an aspherical shape. Lens element L26 has a negative meniscus shape with its convex surface facing the projection surface.

[0188] The aperture 13 of the aperture ST has a central portion 11 and an outer portion 212. The first luminous beam S1 emitted from the light source 2 and passing through the central portion 11 is focused at the first focusing position P1. The second luminous beam S22 emitted from the light source 2 and passing through the outer portion 212 is focused at the second focusing position P22.

[0189] In the lens element L25, the formula defining the aspherical shape differs between the central portion 11 and the outer portion 212. Specifically, the higher-order coefficients of the formula defining the aspherical shape differ between the central portion 11 and the outer portion 212 of the lens element L25. With this configuration, the second focusing position P22 can be separated from the first focusing position P1 and distributed within a predetermined range on the optical axis OA.

[0190] Furthermore, in lens elements L21 to L24, the radius of curvature differs between the central portion that overlaps with the central portion 11 of lens element L25 when viewed from the optical axis direction Z, and the outer portion that overlaps with the outer portion 212.

[0191] The aperture ST is located between lens elements L24 and L25.

[0192] (Effects) The optical system 201 according to Example 8 is an optical system that projects a light beam from a light source onto a projection surface. The optical system 1 includes an optical element (lens element L25 of Example 8) having a central portion 11 including the optical axis and an outer portion 12 that is further from the optical axis OA in the radial direction K than the central portion 11. The first light beam S1 incident from the light source 2 onto the central portion 11 irradiates a first region R1 on the projection surface R. The second light beam S22 incident from the light source 2 onto the outer portion 212 irradiates a second region R22 on the projection surface R that includes a region that is radially separated from the first region R1 in the radial direction K. In the optical axis direction Z, the first focusing position P1 of the first light beam S1 by the optical element is located at a different position from the second focusing position P22 of the second light beam S22 by the optical element.

[0193] With this configuration, when the first focusing position P1 is located on the projection surface R, the first luminous beam S1 projects an image of a predetermined two-dimensional pattern, while the second luminous beam S2 naturally illuminates the second region R22 surrounding the image.

[0194] (Numerical Example 8) For the optical system of Numerical Example 8 (corresponding to Example 8), the surface data of the central portion is shown in Table 13, the aspherical shape data of the central portion is shown in Table 14, the surface data of the outer portion is shown in Table 15, and the aspherical shape data of the outer portion is shown in Table 16.

[0195]

[0196]

[0197]

[0198]

[0199] (Embodiment 3) Hereinafter, Embodiment 3 of the present disclosure will be described with reference to Figure 21. Figure 21 is a block diagram showing an example of a lighting device 300 according to the present disclosure. The lighting device 300 comprises the optical system 1 disclosed in Embodiment 1 and a light source 302.

[0200] In Embodiment 3, the light source 302 has a plurality of light-emitting units 303. The plurality of light-emitting units 303 may be composed of LEDs, OLEDs, or liquid crystal panels. When each of the light-emitting units 303 is composed of an LED, the light distribution of the emitted light is large, so the light utilization efficiency can be increased by increasing the numerical aperture (NA) of the optical system 1. The plurality of light-emitting units 303 may be composed of monochromatic or multi-colored LEDs. For example, the plurality of light-emitting units 303 may be composed of red LEDs, green LEDs, and blue LEDs arranged in a row.

[0201] Since the light source 302 has multiple light-emitting units 303, localized dark areas caused by defects in the light-emitting units 303 become less noticeable in the projected image.

[0202] Multiple light-emitting units 303 are arranged in a predetermined pattern. For example, multiple light-emitting units 303 are arranged two-dimensionally. When arranged two-dimensionally, multiple light-emitting units 303 may be arranged in a vertical and horizontal matrix or in concentric circles. Multiple light-emitting units 303 may also be arranged one-dimensionally.

[0203] Adjacent light-emitting units 303 are spaced apart such that, on the projection surface R, the second region R2 illuminated by one light-emitting unit 303 overlaps with the first region R1 illuminated by the other light-emitting unit 303.

[0204] This configuration allows the second region R2 to overlap the first region R1, making the gaps between the first regions R1 less noticeable.

[0205] For example, the second region R2 created by one light-emitting unit 303 overlaps with the central position of the first region R1 created by the other light-emitting unit 303. In this case, the illuminance of the second region R2 created by one light-emitting unit 303 is 4% to 50% of the maximum illuminance of the first region R1 at the central position of the first region R1 created by the other light-emitting unit 303.

[0206] Let's consider the case where the first region R1 is defined as a region having an illuminance of 50% or more of the maximum illuminance of the first region R1, and the second region R2 is defined as a region having an illuminance of 1% or more of the maximum illuminance of the first region R1. In this case, the width of the second region R2 by one light-emitting unit 303 (for example, distance D4 in Figure 4A) is 5 times or more the width of the first region R1 by one light-emitting unit 303 (for example, distance D3 in Figure 4A). Also, the area of ​​the second region R2 by one light-emitting unit 303 is 25 times or more the area of ​​the first region R1 by one light-emitting unit 303.

[0207] This configuration makes it easy to superimpose the second region R2 onto the first region R1.

[0208] The MTF of the optical system 1 at the spatial frequency of the pitch of adjacent light-emitting units 303 is 0.5 or less. For example, if the pitch of the light-emitting units 303 is 50 μm, the MTF (Modulation Transfer Function) of the optical system 1 at a 10 cycles / mm sine wave on the light source side is 0.5 or less.

[0209] This configuration makes localized dark areas caused by defects in the light-emitting section 303 even less noticeable.

[0210] (Embodiment 4) Hereinafter, Embodiment 4 of the present disclosure will be described with reference to Figure 22. Figure 22 is a block diagram showing an example of a lighting device 400 according to the present disclosure. The lighting device 400 comprises the optical system 1 disclosed in Embodiment 1 and a light source 402.

[0211] In Embodiment 4, the light source 402 is composed of a plurality of arranged light-emitting units 403. The plurality of light-emitting units 403 are arranged in a predetermined pattern. For example, the plurality of light-emitting units 403 are arranged two-dimensionally or one-dimensionally. Each light-emitting unit 403 has a blue LED 404 and a yellow phosphor 405, and emits white light. The yellow phosphor 405 fluoresces yellow light using the blue light emitted from the blue LED 404 as excitation light.

[0212] With this configuration, if unevenness in color occurs in the white light emitted from the light source 402 due to the density of the fluorescent material in the yellow phosphor 405, the unevenness in color of the projected image can be suppressed by superimposing the second region R2 on the first region R1. In addition, since the light source 402 has multiple light-emitting units 403, the yellow tint between adjacent light-emitting units 403 can be reduced.

[0213] The light source 402 may also have a light-emitting section 403 that includes LEDs of other colors and phosphors. The light-emitting section 403 may have a blue LED and a green phosphor and a red phosphor, or a purple LED and multiple phosphors such as red, green, and blue fluorescent LEDs, or an ultraviolet LED and multiple phosphors. When the light-emitting section 403 includes LEDs and phosphors, the light source 402 converts the wavelength of a portion of the light emitted from the LEDs using the phosphors.

[0214] The light source 402 may also be composed of a single light-emitting unit 403.

[0215] As described above, embodiments have been explained as part of the technical disclosure in this disclosure. For this purpose, accompanying drawings and a detailed description have been provided.

[0216] Therefore, the components described in the attached drawings and detailed descriptions may include not only components essential for solving the problem, but also components that are not essential for solving the problem, provided that they illustrate the technology described above. For this reason, the mere presence of such non-essential components in the attached drawings or detailed descriptions should not be immediately assumed to mean that these non-essential components are essential.

[0217] Furthermore, since the embodiments described above are for illustrative purposes of the technology described herein, various modifications, substitutions, additions, omissions, etc., can be made within the scope of the claims or their equivalents.

[0218] The optical system in the first embodiment is an optical system that projects a light beam from a light source onto a projection surface, and comprises an optical element having a central portion including the optical axis and an outer portion that is further from the optical axis than the central portion in a first direction perpendicular to the optical axis, wherein a first light beam incident on the central portion from the light source irradiates a first region on the projection surface, and a second light beam incident on the outer portion from the light source irradiates a second region on the projection surface that includes the first region and has a larger area than the first region.

[0219] In the second embodiment, the optical system is such that, in the optical system of the first embodiment, the first region corresponds to the light source image of the light source, and a boundary is formed between it and the second region by having an illuminance higher than that of the second region by a predetermined value or more.

[0220] In the third embodiment, as an optical system, blurred light obtained by averaging the light source image of the light source is projected onto the second region, as in the optical system of the second embodiment.

[0221] In the fourth embodiment, the optical system is the same as in the third embodiment, where the light source image is an image, the image is projected onto the first region, and blurred light with an averaged illuminance distribution of the image is projected onto the second region.

[0222] In the fifth embodiment, in the optical system of any of the first to fourth embodiments, in the second direction in which the optical axis extends, the first focusing position of the first light beam by the optical element is different from the second focusing position of the second light beam by the optical element, and the distance between the second focusing position and the optical element is 50% or less of the distance between the first focusing position and the optical element.

[0223] In the sixth embodiment, the optical system is such that, in the optical system of the fifth embodiment, the second focusing position is continuously distributed in the second direction, and the spacing of the second luminous beams increases in the direction away from the optical axis in the first direction on the projection surface.

[0224] As an optical system in the seventh embodiment, the optical system in the fifth or sixth embodiment further comprises an aperture disposed between the light source and the optical element, wherein, when viewed from a second direction, a second light beam in contact with the edge defining the opening of the aperture is irradiated on the projection surface at a position a first distance away from the first region in a first direction, and the first distance is 1 / 100 or more the distance from the optical element to the first focusing position.

[0225] In the optical system of the eighth embodiment, the first distance is 1 / 5 times or less the distance from the optical element to the first focusing position.

[0226] In the ninth embodiment, the optical system is one of the optical systems in any of the first to eighth embodiments, and the optical element has a lens that transmits light from a light source.

[0227] In the optical system of the tenth embodiment, as in the optical system of the ninth embodiment, the optical element has an aspherical lens that transmits light from a light source.

[0228] In the eleventh embodiment, the optical system is such that, in the optical system of the ninth or tenth embodiment, the optical elements include at least a condensing lens, an aberration correction lens, and an image plane correction lens.

[0229] As the optical system in the twelfth embodiment, in the optical system in the eleventh embodiment, if the distance between the light source and the condensing lens is La and the thickness of the condensing lens is t, then the effective diameter φ1 of the condensing lens satisfies the following relation (11).

[0230]

[0231] As an optical system in the 13th embodiment, in the optical system in the 12th embodiment, the condensing lens is a spherical lens having radii of curvature r1 and r2, and the effective diameter φ1 of the condensing lens satisfies the following relation (12).

[0232]

[0233] As an optical system in the 14th embodiment, the optical system in any of the 11th to 13 embodiments further comprises an aperture disposed between a condensing lens and an aberration correction lens, wherein the aberration correction lens is an aspherical lens having at least one convex surface having a radius of curvature r3 and an effective diameter φ3, and the sag amount z1 of the aberration correction lens at the effective diameter φ3 satisfies the following relation (13):

[0234]

[0235] The light source emits on-axis light along the optical axis and off-axis light from a position radially separated from the optical axis by a distance d. At the incident surface of the aberration correction lens, the under-ray of the on-axis light passing through the lower end of the aperture forms an angle α1 with the optical axis, and the under-ray of the off-axis light passing through the lower end of the aperture forms an angle α2 with the optical axis. The distance Lb between the aberration correction lens and the aperture satisfies the following relation (14).

[0236]

[0237] As an optical system in the 15th embodiment, in the optical system in any of the 11th to 14th embodiments, the image plane correction lens is an aspherical lens having at least one concave surface having a radius of curvature r4 and an effective diameter φ4, and the sag amount z2 of the image plane correction lens at the effective diameter φ4 satisfies the following relation (15).

[0238]

[0239] As an optical system in the 16th embodiment, the optical system in any of the 11th to 15th embodiments further comprises a convex lens having at least one convex surface and a concave lens having at least one concave surface, wherein the convex lens and the concave lens have different refractive indices or Abbe numbers.

[0240] In the optical system of the 17th embodiment, the convex lens and concave lens are arranged in the same order as in the optical system of the 16th embodiment, with the convex lens having a larger Abbe number or a smaller refractive index than the concave lens.

[0241] As an optical system in the 18th embodiment, the optical system in any of the 11th to 17th embodiments further comprises an annular optical filter positioned between the light source and the image plane correction lens, which overlaps with a portion of the outer part when viewed from a second direction in which the optical axis extends, and the optical filter absorbs or reflects short-wavelength light.

[0242] The illumination device in the 19th embodiment comprises a light source and an optical system according to any of the first to 18 embodiments.

[0243] As a lighting device of the 20th embodiment, in the lighting device of the 19th embodiment, the light source has a plurality of arranged light-emitting parts.

[0244] As a lighting device of the 21st embodiment, in a lighting device of the 19th or 20th embodiment, on the projection surface, a second region by one light-emitting unit overlaps with a first region by an adjacent light-emitting unit.

[0245] As a lighting device of the 22nd embodiment, in a lighting device of any of the 19th to 21st embodiments, on the projection surface, the illuminance of the first region is 50% or more of the maximum illuminance of the first region, the illuminance of the second region is 1% or more of the maximum illuminance of the first region, and the area of ​​the second region by one light-emitting unit is 25 times or more of the area of ​​the first region by one light-emitting unit.

[0246] As a lighting device of the 23rd embodiment, in a lighting device of any of the 20th to 22nd embodiments, the MTF of the optical system at the spatial frequency of the pitch of the plurality of light-emitting parts is 0.5 or less.

[0247] As a lighting device of the 24th embodiment, in a lighting device of any of the 19th to 23rd embodiments, the light source has a light-emitting section including an LED and a phosphor, and a portion of the light emitted from the LED is wavelength-converted by the phosphor.

[0248] As a lighting device of the 25th embodiment, in the lighting device of the 24th embodiment, the light source has a plurality of arranged light-emitting parts.

[0249] This disclosure is applicable to lighting devices that illuminate objects or project display images.

[0250] 1 Optical System 2 Light Source 11 Central Section 12 Outer Section 13 Openings L1-L6 Lens Element R1 First Field R2 Second Field S1 First Beam S2 Second Beam T11 Reflecting Surfaces T1, T2 Transmitting Surface ST Twisting OF Optical Field 100 Illumination Device

Claims

1. An optical system for projecting a luminous beam from a light source onto a projection surface, comprising an optical element having a central portion including the optical axis and an outer portion that is further from the optical axis than the central portion in a first direction perpendicular to the optical axis, wherein a first luminous beam incident from the light source onto the central portion irradiates a first region on the projection surface, and a second luminous beam incident from the light source onto the outer portion irradiates a second region on the projection surface that includes the first region and has a larger area than the first region.

2. The optical system according to claim 1, wherein the first region corresponds to the light source image of the light source and forms a boundary with the second region by having an illuminance higher than a predetermined value than the second region.

3. The optical system according to claim 2, wherein blurred light obtained by averaging the light source image of the light source is projected onto the second region.

4. The optical system according to claim 3, wherein the light source image is an image, the image is projected onto the first region, and blurred light with an averaged illuminance distribution of the image is projected onto the second region.

5. In the second direction in which the optical axis extends, the first focusing position of the first light beam by the optical element is different from the second focusing position of the second light beam by the optical element, and the distance between the second focusing position and the optical element is 50% or less of the distance between the first focusing position and the optical element, the optical system according to claim 1.

6. The optical system according to claim 5, wherein the second focusing positions are continuously distributed in the second direction, and the spacing between the second luminous beams increases in the projection surface in the direction away from the optical axis in the first direction.

7. The optical system according to claim 5, further comprising an aperture disposed between the light source and the optical element, wherein, when viewed from the second direction, the second light beam in contact with the edge defining the opening of the aperture is irradiated onto the projection surface at a position a first distance away from the first region in the first direction, and the first distance is 1 / 100 or more the distance from the optical element to the first focusing position.

8. The optical system according to claim 7, wherein the first distance is 1 / 5 times or less the distance from the optical element to the first light-gathering position.

9. The optical system according to claim 1, wherein the optical element has a lens that transmits light from the light source.

10. The optical system according to claim 9, wherein the optical element has an aspherical lens that transmits light from the light source.

11. The optical system according to claim 9, wherein the optical element comprises at least a condensing lens, an aberration correction lens, and an image plane correction lens.

12. If La is the distance between the light source and the focusing lens, and t is the thickness of the focusing lens, then the effective diameter φ1 of the focusing lens satisfies the following relationship: The optical system according to claim 11.

13. The condensing lens is a spherical lens having radii of curvature r1 and r2, and the effective diameter φ1 of the condensing lens satisfies the following relationship: The optical system according to claim 12.

14. The device further comprises an aperture positioned between the condensing lens and the aberration correction lens, wherein the aberration correction lens is an aspherical lens having at least one convex surface having a radius of curvature r3 and an effective diameter φ3, and the sag amount z1 of the aberration correction lens at the effective diameter φ3 satisfies the following relationship: The light source emits on-axis light along the optical axis and off-axis light from a position radially distanced d from the optical axis, and at the incident surface of the aberration correction lens, the under-ray of the on-axis light passing through the lower end of the aperture forms an angle α1 with the optical axis, and the under-ray of the off-axis light passing through the lower end of the aperture forms an angle α2 with the optical axis, and the distance Lb between the aberration correction lens and the aperture satisfies the following relationship: The optical system according to claim 11.

15. The image plane correction lens is an aspherical lens having at least one concave surface having a radius of curvature r4 and an effective diameter φ4, wherein the sag amount z2 of the image plane correction lens at the effective diameter φ4 satisfies the following relationship: The optical system according to claim 11.

16. The optical system according to claim 11, further comprising a convex lens having at least one convex surface and a concave lens having at least one concave surface, wherein the convex lens and the concave lens have different refractive indices or Abbe numbers.

17. The optical system according to claim 16, wherein the convex lens and the concave lens are arranged in the order of the light source, and the convex lens has a larger Abbe number or a smaller refractive index than the concave lens.

18. The optical system according to claim 11, further comprising an annular optical filter disposed between the light source and the image plane correction lens, which, when viewed from a second direction in which the optical axis extends, overlaps with a portion of the outer portion, wherein the optical filter absorbs or reflects short-wavelength light.

19. An illumination device comprising the light source and the optical system according to any one of claims 1 to 18.

20. The lighting device according to claim 19, wherein the light source has a plurality of arranged light-emitting units.

21. The lighting device according to claim 19, wherein, on the projection surface, the second region formed by one light-emitting unit overlaps with the first region formed by an adjacent light-emitting unit.

22. The lighting device according to claim 19, wherein, on the projection surface, the illuminance of the first region is 50% or more of the maximum illuminance of the first region, the illuminance of the second region is 1% or more of the maximum illuminance of the first region, and the area of ​​the second region by one light-emitting unit is 25 times or more of the area of ​​the first region by one light-emitting unit.

23. The illumination device according to claim 20, wherein the MTF of the optical system at the spatial frequency of the pitch of the plurality of light-emitting parts is 0.5 or less.

24. The lighting device according to claim 19, wherein the light source has a light-emitting section including an LED and a phosphor, and a portion of the light emitted from the LED is wavelength-converted by the phosphor.

25. The lighting device according to claim 24, wherein the light source has a plurality of the light-emitting units arranged in a row.

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