Illumination device

According to one embodiment, an illumination device includes a plurality of light emitting elements and a plurality of reflectors. The plurality of reflectors include at least one first reflector and at least one second reflector. The first reflector is provided corresponding to the first region at the center and is provided so that the corresponding light emitting element is positioned within a focal region in the vicinity of a focal point. The second reflector is provided corresponding to the second region, has an angular eccentricity so as to collect light on one region on the optical axis, and is provided so as to be positioned within a margin region in which one of the corresponding light emitting elements is provided at a position farther away than a second focal region in the vicinity of the focal point.

FIELD

Embodiments described herein relate generally to an illumination device capable of illuminating an object with light.

BACKGROUND

There are LED illumination devices that can be used for dental treatment. Such an LED illumination device is often configured to secure necessary illuminance by using a plurality of light emitting elements.

DETAILED DESCRIPTION

According to one embodiment, an illumination device of an embodiment includes: a plurality of light emitting elements provided on a surface intersecting with an optical axis; and a plurality of reflectors provided so as to correspond to the plurality of light emitting elements, each of the plurality of reflectors having a curved cross section with at least one focal point. The plurality of reflectors includes: at least one first reflector provided corresponding to a central first region corresponding to the optical axis on the surface intersecting with the optical axis, the at least one first reflector being provided so that one of the plurality of corresponding light emitting elements are positioned within a focal region in the vicinity of the focal point; and at least one second reflector provided corresponding to a second region positioned on the surface intersecting with the optical axis that is deviated from the first region in a direction intersecting with the optical axis, the at least one second reflector having an angular eccentricity so as to collect light on one region on the optical axis and being provided so as to be positioned within a margin region in which one of the plurality of corresponding light emitting elements are provided at positions farther away than a second focal region in the vicinity of the focal point.

First Embodiment

Hereinafter, a first embodiment of an illumination device will be described with reference toFIGS. 1 to 21. Although the illumination device11is mainly used for dental treatment, it can naturally be applied to other medical applications or desk lamps. The illumination device11includes a pair of illumination units12(light emitting element array).

As illustrated inFIGS. 1 to 3, the illumination device11includes a support body13, a lamp shade portion14provided in a frame shape so as to be continuous with the support body13, a transmissive cover15provided so as to cover a distal end portion of the lamp shade portion14(end portion on the opposite side to an end portion on the support body13side), and a pair of illumination units12(array of light emitting elements16) fixed to the support body13through leg portions17or the like. The support body13is supported by an arm or the like. For example, the support body13can be supported at a predetermined position and angle through the arm so as to face a patient. The leg portion17has, for example, a triangular cross-sectional shape. An optical axis18(illumination optical axis) of the illumination device11as a whole is defined by a set of light irradiated from a plurality of light emitting elements16described later. The optical axis18(illumination optical axis) passes through the center of the support body13and coincides with the central axis intersecting with (orthogonal to) the support body13.

Further, as illustrated inFIGS. 2 and 3, a surface21(light emitting surface) intersecting with the optical axis can be defined in the illumination device11. An example of the surface21intersecting with the optical axis can be a surface orthogonal to the optical axis18, but the present embodiment is not limited thereto. Another example of the surface21intersecting with the optical axis may be a surface substantially orthogonal to the optical axis18.

The surface21intersecting with the optical axis has a first region21A at the center corresponding to the optical axis18and a second region21B deviating from the first region21A in a direction intersecting with the optical axis18. In the present embodiment, an example of the direction intersecting with the optical axis18is a horizontal direction (transverse direction), but the present embodiment is not limited thereto. It is obvious that the direction intersecting with the optical axis18may be, for example, a vertical direction (longitudinal direction).

As illustrated inFIGS. 1 to 3, the illumination unit12includes a mirror block22having a plurality of reflectors23formed thereon, a substrate24provided so as to face the mirror block22and the plurality of reflectors23, and a plurality of light emitting elements16(light source) provided on a plurality of support portions25of the substrate24described later.

The plurality of light emitting elements16are linearly provided at substantially constant intervals on the surface21(light emitting surface) intersecting with the optical axis, for example, in the direction intersecting with the optical axis18(for example, the horizontal direction). Each of the plurality of light emitting elements16includes, for example, a white LED, but may include LEDs of other colors. In addition, the colors of some light emitting elements16included in the plurality of light emitting elements16may be different from the colors of the other light emitting elements16included in the plurality of light emitting elements16. The light emitting elements16may appropriately use commercially available light emitting elements.

The substrate24includes a printed wiring board made of a glass epoxy resin or the like. The substrate24is a so-called multilayer substrate formed by laminating a plurality of wiring layers. The substrate24has an elongated plate shape. The substrate24may be provided so as to cover the mirror block22. The substrate24includes a substrate body26, a plurality of opening portions27provided in the substrate body26, and a plurality of support portions25provided in the substrate body26. The plurality of opening portions27is linearly disposed along the extending direction of the substrate24. Each of the plurality of support portions25is positioned inside each of the plurality of opening portions27. Each of the plurality of support portions25is provided so as to correspond to each of the plurality of reflectors23.

As illustrated inFIGS. 4 and 5, the opening portion27has a pair of through-hole portions27A passing through a front surface and a back surface of the substrate24. The pair of through-hole portions27A is provided on both sides with the support portion25interposed therebetween. The opening portion27has, for example, an approximately octagonal shape, and may have other polygonal shapes. The opening portion27is provided so as to expose the plurality of reflectors23of the mirror block22to the outside, which will be described later. Therefore, each of the plurality of opening portions27is provided so as to correspond to each of the plurality of reflectors23.

As illustrated inFIGS. 3 and 4, each of the plurality of support portions25is formed in a bridge shape passing through the opening portion27. The support portion25includes a bridge portion28and a placement portion31provided at the middle of the bridge portion28. One light emitting element16is mounted on the placement portion31. The placement portion31has, for example, a circular shape and is provided in the middle of the bridge portion28. The light emitting element16receives supply of power from a power supply32through wirings provided in the bridge portion28.

The support portion25at the position corresponding to the first region21A is provided so as to be positioned at the center of the first reflector23A corresponding thereto, which will be described later. The support portion25at the position corresponding to the second region21B is provided so as to be position-deviated in the direction away from the first region21A with respect to the center of the second reflector23B corresponding thereto. The magnitude of the positional deviation changes according to the position from the first region21A. More specifically, the magnitude of the positional deviation of the support portion25in the direction away from the first region21A increases as the position of the support portion25moves away from the first region21A (the center of the illumination device11). That is, the magnitude of the positional deviation of the support portion25positioned in the vicinity of the first region21A among the support portions25at positions corresponding to the second region21B is relatively small as compared with that of the center of the second reflector23B corresponding thereto (positional deviation in the direction away from the first region21A). In addition, the magnitude of the positional deviation of the support portion25positioned at the position away from the first region21A among the support portions25positioned in the second region21B is relatively large as compared with that of the center of the second reflector23B corresponding thereto (positional deviation in the direction away from the first region21A).

The mirror block22is formed in, for example, an elongated plate shape by a resin material or the like. The mirror block22includes the plurality of reflectors23. The plurality of reflectors23are provided so as to correspond to the plurality of light emitting elements16. The plurality of reflectors23are linearly provided at one side of the mirror block22, for example, at substantially constant intervals. Each of the plurality of reflectors23is provided in a substantially semispherical shape recessed from one surface.

The mirror block22can be formed by, for example, the following method. Machining (for example, cutting work) is performed from one surface side of a plate material on an elongated plate material made of a resin material to form a semispherical surface on the one surface. The plurality of reflectors23can be formed on the mirror block22by forming a mirror layer on the spherical surface by various thin film forming methods such as vapor deposition or electroless plating.

The plurality of reflectors23includes at least one first reflector23A and at least one second reflector23E. The at least one first reflector23A is provided corresponding to the central first region21A corresponding to the optical axis18. In the present embodiment, for example, the first reflector23A is constituted by one piece, but it is obvious that the first reflector23A may be constituted by a plurality of pieces. The first reflector23A faces the light emitting element16positioned in the first region21A. A cross section of the first reflector23A forms, for example, a curve, and more specifically, forms a quadratic curve. A cross section of the curve of the first reflector23A is, for example, parabolic, but the shape of the cross section of the curve of the first reflector23A is not limited thereto. The cross-sectional shape of the curve of the first reflector23A may be a shape of a quadratic curve other than a parabola, for example, a hyperbolic shape or an elliptical shape. In the case where the cross section of the curve of the first reflector23A is formed by a parabola or a hyperbola, it has one focal point33. In the case where the cross section of the curve of the first reflector23A is formed in an elliptical shape, it has two focal points33. A distance from the apex34of the curve to the focal point33can be determined mathematically by a known mathematical formula.

As illustrated inFIGS. 3 and 4, the at least one second reflector23B is provided corresponding to the second region21B positioned away from the first region21A in a direction intersecting with (orthogonal to) the optical axis18. In the present embodiment, for example, the second reflector23B is constituted by a plurality of pieces. Each of the plurality of second reflectors23B faces each of the plurality of light emitting elements16positioned in the second region21B. Each of the second reflectors23B has a curved cross section, and the curve has, for example, a quadratic curve shape. A cross section of the curve of the second reflector23B is formed, for example, in a parabolic shape. However, the axis of the curve (parabola) of the second reflector23B is inclined with respect to the optical axis18so as to collect light toward one region35(seeFIG. 15) on the optical axis18(illumination optical axis). More specifically, the axis of the curve of the second reflector23B, that is, the optical axis (individual optical axis36) of each light emitting element is inclined so as to approach the optical axis18(illumination optical axis) as the distance from the illumination device11increases. The inclination of the axis of the curve of the second reflector23B is different from the inclination of the axis of the curve of another adjacent second reflector23B. That is, the inclination of the axis of the curve of the second reflector23B is larger as the distance from the central first region21A corresponding to the optical axis18increases.

The shape of the cross section of the curve of the second reflector23B is not limited to the parabolic shape. The shape of the cross section of the curve of the second reflector23B may be a shape of a quadratic curve other than a parabola, for example, a hyperbolic shape or an elliptical shape. In the case where the cross section of the curve of the first reflector23A is formed by a parabola or a hyperbola, it has one focal point33. In the case where the cross section of the curve of the first reflector23A is formed in an elliptical shape, it has two focal points33. A distance from the apex34of the curve to the focal point33can be determined mathematically by a known mathematical formula.

Here, as illustrated inFIG. 6, an attempt was made to arrange the plurality of reflectors23and the light emitting elements16, such that an irradiation pattern which remarkably suppressed illuminance could be obtained at a position deviated from the illumination target region37, while collecting light from the plurality of light emitting elements16to obtain sufficient illuminance with respect to the illumination target region37around the oral cavity of the patient. It is also required by Japanese Industrial Standards (JIS) (JIS T5753: 2012 dental illuminator) to extremely lower illuminance at a position deviated from the illumination target region37, especially at the eye position of the patient. Note that JIS T5753 corresponds to ISO 9680:2014, Dentistry-Operating lights (MOD). In order to reduce the burden on the patient's eyes, intensive studies were carried out to the realization of the illumination device11with excellent irradiation pattern cutoff characteristics such that light does not reach the patient's eyes.

First, it was examined at which position of the illumination unit12(light emitting element array) the light emitting element16most affects the convergence of light of the illumination device11as a whole. The convergence of light (degree of convergence) is an important parameter to consider so as not to illuminate the position of the patient's eyes. The result is omitted, but in the light emitting element array, the light emitted from the light emitting element16and the first reflector23A positioned at the center did not particularly adversely affect the convergence of light of the entire illumination device11. On the other hand, in the light emitting element array, blurring (blurring like defocusing, coma aberration) over which the irradiation pattern protrudes from the illumination target region37is remarkable in the light emitted from the light emitting element16and the second reflector23B at a position away from the central first region21A (position close to the end portion). Therefore, it was found that the improvement of the convergence of the light emitted from the light emitting element16and the second reflector23B positioned in the vicinity of the end portion as described above was important for improving the convergence of light of the illumination device11as a whole.

Subsequently, a theoretical analysis was performed on the convergence of the light emitted from the light emitting element16by using the simplified model illustrated inFIG. 7. The reflector23was formed with a parabolic surface such that the cross-sectional shape of the reflector23became a parabola. For example, z=0.025×(x2+y2)+C was used as the mathematical formula of the parabolic surface of the reflector23. The light emitting element16was disposed in the vicinity of the focal point33of the parabola of the reflector23. In addition, a screen38on which light was irradiated was installed at a position 300 mm away from the light emitting element16(reflector23). In this model, the light emitted from the light emitting element16is reflected by the reflector23and irradiated in the direction of the optical axis18. Using this model, the influence of the distance between the reflector23and the light emitting element16on the convergence of light (illuminance distribution) was studied.

The examination results are shown inFIG. 8. The horizontal axis Y represents the distance (mm) from the center of light (optical axis18). The vertical axis represents the normalized illuminance. The case where the light emitting element16is placed at the position of the focal point33is set as ±0.00. The case where the light emitting element16was moved in the direction away from the reflector23in the direction of the optical axis18with the focal point33set at the reference (±0.00) was set as plus, and the case where the light emitting element16was moved in the direction approaching the reflector23in the direction of the optical axis18was set as minus. In the direction away from the reflector23, the position of the light emitting element16was moved in the range of 0.10 mm to 1.00 mm. In the direction approaching the reflector23, the light emitting element16was moved in the range of 0.25 mm to 1.0 mm. In this simulation result, the illuminance on the screen38when the light emitting element16was placed at the focal point33was normalized to 1 with respect to the vertical axis.

According to this result, as the light emitting element16was moved in the direction away from the reflector23, the width of the illuminance distribution in the Y axis direction became small, the convergence of the light irradiated from the light emitting element16became excellent, and the center illuminance was also high. When the convergence of light becomes excellent as described above, the patient does not feel dazzling, and the intended ideal illumination device11is obtained. The center illuminance when the light emitting element16was moved by 1.00 mm from the focal point33in the direction away from the reflector23in the direction of the optical axis18was lower than the center illuminance when the light emitting element16was moved by 0.75 mm from the focal point33in the direction away from the reflector23in the direction of the optical axis18. On the other hand, it was found that when the light emitting element16was moved in the direction approaching the reflector23in the direction of the optical axis18, the convergence of the light irradiated from the light emitting element16deteriorated.

FIG. 9illustrates a simulation result when the light emitting element16was moved by a distance larger than 1.00 mm from the focal point33. For example, it was found that when the light emitting element16was moved so as to be away from the focal point33by 1.50 mm, the center illuminance of the light decreased. Further, it was found that when the light emitting element16was moved away from the focal point33by 2.00 mm, the center illuminance of the light further decreased and the convergence of light also deteriorated.

Therefore, from the above simulation result, when the position of the light emitting element16was deviated from the focal point33in the direction away from the reflector23in the direction of the optical axis (individual optical axis36) of the light emitting element16within the range of 0.10 mm to 1.00 mm, it was possible to obtain a suggestion that it was remarkably superior to the result outside this range in the convergence and luminance of light. Therefore, the idea was obtained that the blurring (light diffusion) in which the irradiation pattern protruded from the illumination target region37could be efficiently reduced in the light emitting element16and the second reflector23B when the structure for deviating the position of the light emitting element16from the focal point33as described above was applied with respect to the light emitting element16and the second reflector23B positioned at the position (in the vicinity of the end portion) far from the first region21A of the array of the light emitting elements16(illumination unit12).

Despite the above suggestion and idea, industrially, deviating the position of the light emitting element16in the direction of the optical axis18(illumination optical axis) as the entire illumination device11as illustrated inFIGS. 10 and 11is realistic in view of the manufacturing cost and the like rather than deviating the position of the light emitting element16in the direction of the optical axis (individual optical axis36) of each light emitting element16. Therefore, in the present embodiment, in consideration of the suggestion of the range in which the convergence and illuminance of light were remarkably excellent as described above, the region between a point where a distance equivalent to 1% of the distance from the apex34of the curve of the second reflector23B to the focal point33was moved in the direction away from the apex34in the direction of the optical axis18from the focal point33and a point where a distance equivalent to 10% of the distance from the apex34of the curve of the second reflector23B to the focal point33was moved in the direction away from the apex34in the direction of the optical axis18from the focal point33was set as the margin region41, as illustrated inFIG. 10. The margin region41means a region having a margin with respect to the convergence of light and is a region in which the convergence and illuminance distribution of the light irradiated from the light emitting element16are excellent. Therefore, by deviating the position of the light emitting element16from the state illustrated inFIG. 10to the state illustrated inFIG. 11and disposing the light emitting element16in the margin region41, it is possible to effectively prevent blurring (light diffusion) in which the irradiation pattern protrudes from the illumination target region37irradiated from the light emitting element16and the second reflector23B positioned in the vicinity of the end portion of the light emitting element array.

As illustrated inFIG. 10, in the present embodiment, the distance from the apex34of the curve of the reflector23to the focal point33of the curve is 10 mm. Therefore, according to the definition of the margin region41, a region between a point moved by a distance of 0.10 mm in the direction away from the second reflector23B in the direction of the optical axis18from the focal point33and a point moved by a distance of 1.00 mm in the direction away from the second reflector23B in the direction of the optical axis18from the focal point33is taken as the margin region41on the actual product.

On the other hand, a region positioned closer to the focal point33than the margin region41was set as a second focal region42. The second focal region42is slightly deviated from the focal point33, but is defined as a region having substantially no difference as compared with the case where the light emitting element16is disposed at the focal point33. In addition, the margin region41is provided at a position farther away from the second reflector23B than the second focal region42.

The second focal region42is set as a region between a point where a distance equivalent to 0% or more and less than 1% of the distance from the apex34of the curve of the second reflector23B to the focal point33is moved in the direction approaching the apex34in the direction of the optical axis18from the focal point33and a point where a distance equivalent to 0% or more and less than 1% of the distance from the apex34of the curve of the second reflector23B to the focal point33is moved in the direction away from the apex34in the direction of the optical axis18from the focal point33.

In the present embodiment, the distance from the apex34of the curve of the second reflector23B to the focal point33is 10 mm. Therefore, according to the definition of the second focal region42, a region between a point moved by a distance of less than 0.10 mm in the direction approaching the second reflector23B in the direction along the optical axis18from the focal point33and a point moved by a distance of less than 0.10 mm in the direction away from the second reflector23B in the direction along the optical axis18from the focal point33is taken as the second focal region42on the actual product. In the second reflector23B and the light emitting element16corresponding to the second region21B, the light emitting element16is not actually disposed in the second focal region42.

A region in the vicinity of the focal point33of the curved surface of the first reflector23A is set as a focal region43even in the light emitting element16and the first reflector23A corresponding to the first region21A. The focal region43is slightly deviated from the focal point33, but is defined as a region having substantially no difference as compared with the case where the light emitting element16is disposed at the focal point33. Since the light emitting element16and the first reflector23A corresponding to the first region21A are positioned at the center of the array of the light emitting elements16(the illumination unit12), there will be no blurring in which the irradiation pattern protrudes from the illumination target region37to the light irradiated therefrom. Therefore, at the position corresponding to the first region21A, the light emitting element16may be disposed at the focal point of the first reflector23A, or the light emitting element16may be disposed in the focal region43in the vicinity of the focal point33.

Since the focal region43is set almost similarly to the second focal region42illustrated inFIG. 10, the focal region43will be described as a representative inFIG. 10(in this case, the actual individual optical axis36is parallel to the optical axis18). The focal region43is a region between a point where a distance equivalent to 0% or more and less than 1% of the distance from the apex34of the curve of the first reflector23A to the focal point33is moved in the direction approaching the apex34in the direction of the optical axis18from the focal point33and a point where a distance equivalent to 0% or more and less than 1% of the distance from the apex34of the curve of the first reflector23A to the focal point33is moved in the direction away from the apex34in the direction of the optical axis18from the focal point33.

In the present embodiment, the distance from the apex34of the curve of the first reflector23A to the focal point33of the curve is 10 mm. Therefore, a region between a point moved by a distance of less than 0.10 mm in the direction approaching the first reflector23A in the direction of the optical axis18from the focal point33and a point moved by a distance of less than 0.10 mm in the direction away from the first reflector23A in the direction of the optical axis18from the focal point33is taken as the focal region43on the actual product.

In the present embodiment, in view of the manufacturing cost and the like as described above, a region deviated by a predetermined distance from the focal point33is set as the margin region41and the second focal region42in the direction of the optical axis18of the entire illumination device11, but a method of setting the margin region41and the second focal region42is not limited thereto. As illustrated inFIG. 12, it is obvious that the margin region41and the second focal region42may be set in the direction of the optical axis (individual optical axis36) of the individual light emitting element16. In the case of the modification (first modification), the margin region41was set as a region between a point where a distance equivalent to 1% of the distance from the apex34of the curve of the second reflector23B to the focal point33was moved in the direction away from the apex34in the direction of the individual optical axis36from the focal point33and a point where a distance equivalent to 10% of the distance from the apex34of the curve of the second reflector23B to the focal point33was moved in the direction away from the apex34in the direction of the individual optical axis36from the focal point33. As illustrated inFIG. 13, by disposing the light emitting element16in the margin region41, it is possible to effectively prevent blurring in which the irradiation pattern protrudes from the illumination target region37of the light irradiated from the light emitting element16and the second reflector23B positioned in the vicinity of the end portion of the array of the light emitting element16, as in the embodiment.

As illustrated inFIG. 12, in the first modification, the distance from the apex34of the curve of the second reflector23B to the focal point33of the curve is 10 mm. Therefore, the margin region41is set as a region between a point moved by a distance of 0.10 mm in the direction away from the second reflector23B in the direction of the individual optical axis36from the focal point33and a point moved by a distance of 1.00 mm in the direction away from the reflector23in the direction of the individual optical axis36from the focal point33.

Similarly, in the first modification, the second focal region42is a region between a point where a distance equivalent to 0% or more and less than 1% of the distance from the apex34of the curve of the second reflector23B to the focal point33is moved in the direction approaching the apex34in the direction of the individual optical axis36from the focal point33and a point where a distance equivalent to 0% or more and less than 1% of the distance from the apex34of the curve of the second reflector23B to the focal point33is moved in the direction away from the apex34in the direction of the individual optical axis36from the focal point. In the first modification, the distance from the apex34of the curve of the second reflector23B to the focal point33of the curve is 10 mm. Therefore, in the present modification, the second focal region42is set as region between a point moved by a distance of less than 0.10 mm in the direction approaching the second reflector23B in the direction of the individual optical axis36from the focal point33and a point moved by a distance of less than 0.10 mm in the direction away from the second reflector23B in the direction of the individual optical axis36from the focal point33.

From the above, according to the present embodiment and the first modification, in order to improve the convergence of the light irradiated from the light emitting element16and the second reflector23B positioned in the vicinity of the end portion of the array of the light emitting elements16, the position of the light emitting element16may be deviated in the direction of the optical axis18of the illumination device11, or the position of the light emitting element16may be deviated in the direction of the individual optical axis36of the individual light emitting element16. Therefore, the “direction along the optical axis” in the present specification includes both the direction of the optical axis18of the illumination device11as a whole and the direction of the optical axis of each of the light emitting elements16(the direction of the individual optical axis36) which is deviated by a predetermined angle from the direction of the optical axis18, according to the first modification.

Subsequently, the actual illumination device11was manufactured according to the theoretical examination result described above.FIG. 14illustrates a substrate24, a light emitting element16, and a mirror block22of an illumination unit12of the present embodiment. A first reflector23A and a second reflector23B formed in the mirror block22were formed in a positional relationship as illustrated inFIG. 14. InFIG. 14, the distance from the apex34of the curve of the second reflector23B to the light emitting element16at the position corresponding to the second region21B is set to be larger as going away from the central first region21A of the illumination device11and approaching the end portion of the illumination unit12(array of light emitting elements16). Therefore, the distance from the apex34of the curve of the second reflector23B in the vicinity of the end portion of the illumination unit12to the corresponding light emitting element16is larger than the distance from the apex34of the curve of the second reflector23B in the vicinity of the first region21A to the corresponding light emitting element16.

The first reflector23A corresponding to the center (the first region21A) of the illumination device11was formed so that the light emitting element16was positioned within the focal region43and the light emitting element16had a positional deviation amount of ±0.0 mm with respect to the focal point33. This arrangement is an example, and the first reflector23A corresponding to the first region21A may be at any position as long as the position is within the range of the focal region43(within a range between a point moved by a distance of less than 0.10 mm in the direction approaching the first reflector23A in the direction of the optical axis18from the focal point33and a point moved by a distance of less than 0.10 mm in the direction away from the first reflector23A in the direction of the optical axis18from the focal point33).

The second reflector23B corresponding to the first region21A side (in the vicinity of the first region21A) of the second region21B was formed so that the light emitting element16was positioned within the margin region41and the light emitting element16had a positional deviation amount of +0.2 mm with respect to the focal point33. At this time, the apex34of the curve of the second reflector23B is formed at a position that is lower by −0.2 mm than the apex34of the curve of the first reflector23A. Therefore, the light emitting element16is disposed at a position deviated by +0.2 mm in the direction away from the second reflector23B in the direction of the optical axis18from the focal point33. The positional deviation amount of the light emitting element16with respect to the focal point33is an example, and any positional deviation amount may be used as long as the light emitting element16is within the margin region41. In the second reflector23B of the second region21B on the first region21A side, the positional deviation amount of the light emitting element16with respect to the focal point33may be, for example, +0.1 mm to +0.2 mm in the direction of the optical axis18from the focal point33or the direction away from the second reflector23B in the direction of the individual optical axis36.

The second reflector23B corresponding to the center of the second region21B was formed so that the light emitting element16was positioned within the margin region41and the light emitting element16had a positional deviation amount of +0.4 mm with respect to the focal point33. At this time, the apex34of the curve of the second reflector23B is formed at a position that is lower by −0.4 mm than the apex34of the curve of the first reflector23A. Therefore, the light emitting element16is disposed at a position deviated by +0.4 mm in the direction away from the second reflector23B in the direction of the optical axis18from the focal point33. The positional deviation amount of the light emitting element16with respect to the focal point33is an example, and any positional deviation amount may be used as long as the light emitting element16is within the margin region41. In the second reflector23B corresponding to the center of the second region21B, the positional deviation amount of the light emitting element16with respect to the focal point33may be, for example, +0.3 mm to +0.4 mm in the direction of the optical axis18from the focal point33or the direction away from the second reflector23B in the direction of the individual optical axis36.

The second reflector23B corresponding to the end portion side (side away from the first region21A) of the second region21B was formed so that the light emitting element16was positioned within the margin region41and the light emitting element16had a positional deviation amount of +0.5 mm with respect to the focal point33. At this time, the apex34of the curve of the second reflector23B is formed at a position that is lower by −0.5 mm than the apex34of the curve of the first reflector23A. Therefore, the light emitting element16is disposed at a position deviated by +0.5 mm in the direction away from the second reflector in the direction of the optical axis18from the focal point33. The positional deviation amount of the light emitting element16with respect to the focal point33is an example, and any positional deviation amount may be used as long as the light emitting element16is within the margin region41. In the second reflector23B corresponding to the center of the second region21B, the positional deviation amount of the light emitting element16with respect to the focal point33may be, for example, +0.5 mm to +1.0 mm in the direction of the optical axis18from the focal point33or the direction away from the second reflector23B in the direction of the individual optical axis36.

Subsequently, the evaluation result related to the cutoff characteristics of the illumination device11including the substrate24, the light emitting element16, and the mirror block22of the illumination unit12of the present embodiment, which is formed as illustrated inFIG. 14, will be described with reference toFIGS. 15 to 21.

As illustrated inFIG. 15, a screen38(target) was set at a position (standard measurement position) separated by 700 mm from the light emitting element. The cutoff characteristics (difficulty in entering light to the patient's eyes) of the illumination device11was evaluated by examining the illuminance distribution of the light irradiated on the screen38.FIG. 15illustrates an aspect in which the second reflector23B corresponding to the second region21B is inclined (angular eccentricity) to the axis of the curve toward the end portion side (outer side), and the light irradiated from the light emitting element16and the second reflector23B on the end portion side (outer side) is collected in the direction approaching the optical axis18of the entire illumination device11. The light irradiated from the light emitting element16and the second reflector23B corresponding to the second region21B as described above is collected toward one region35on the optical axis18, and spreads to a predetermined region around one region35.

FIGS. 16 and 17illustrate the results of irradiating the screen38with light by using the illumination device of the reference example. In the illumination device of the reference example, the light emitting element16corresponding thereto is disposed at the position of the focal point33of the curve of the first reflector23A, and the light emitting element16corresponding thereto is disposed at the position of the focal point33of the curve of the second reflector23B. Therefore, in the reference example, the position of the light emitting element16is not deviated in the direction along the optical axis18from the focal point33of the curve of the second reflector23B (the light emitting element16is disposed within the margin region41).

FIG. 16illustrates the result when the illuminance distribution (contour) of the light irradiated from the illumination device of the reference example on the screen38was set to the maximum value of 60,000 lux (lx). According to the JIS standard, the maximum illuminance is determined to be 15,000 lux or more, but in practice, the maximum illuminance needs to be about 60,000 lux. The horizontal axis X represents the horizontal direction on the screen38, and the vertical axis Y represents the vertical direction on the screen38. From this drawing, it seems that there is no particular problem in the cutoff characteristics at first glance.FIG. 17further illustrates the result when the illuminance distribution (contour) of the light irradiated from the illumination device of the present reference example on the screen38was displayed with only the low illuminance range with the maximum value being 1,200 lux. As a result, it was found that the illuminance distribution was disturbed at four corners of the illuminance distribution (position of B-B′ line, position of C-C′ line).

FIG. 18illustrates an A-A′ cross section, a B-B′ cross section, and a C-C′ cross section of the contour inFIG. 17. It was found fromFIG. 18that any of the A-A′ cross section, the B-B′ cross section, and the C-C′ cross section satisfied the requirement of 1,200 lux or less, which was the reference value specified by the JIS standard (JIS T5753: 2012 dental illuminator), at a position 60 mm or more away from the center of light of the illumination device in the Y axis direction. However, as illustrated in the B-B′ cross section and the C-C′ cross section, the illuminance was maintained at around 500 lux at the position of 60 mm in the Y-axis direction from the center of the light emitted from the illumination device of the reference example. Therefore, the illumination device of the reference example has room for improvement in cutoff characteristics.

FIGS. 19 and 20illustrate the result of irradiating the screen38with light by using the illumination device11of the present embodiment, that is, the illumination device11including the substrate24, the light emitting element16, and the mirror block22of the illumination unit12illustrated inFIG. 14.

FIG. 19illustrates the result when the illuminance distribution (contour) of the light irradiated from the illumination device11of the present embodiment on the screen38was set to the maximum value of 60,000 lux (lx). The horizontal axis X represents the horizontal direction on the screen38, and the vertical axis Y represents the vertical direction on the screen38. Also in this drawing, as in the case of the above-described reference example, it seemed that there was no particular problem in the cutoff characteristics.

FIG. 20further illustrates the result when the illuminance distribution (contour) of the light irradiated from the illumination device11of the present embodiment on the screen38was displayed with only the low illuminance range with the maximum value being 1,200 lux. As a result, it was found that there was no disturbance in the illuminance distribution even at the four corners of the illuminance distribution (position of B-B′ line, position of C-C′ line).

FIG. 21illustrates an A-A′ cross section, a B-B′ cross section, and a C-C′ cross section of the contour inFIG. 20. FromFIG. 21, any of the A-A′ cross section, the B-B′ cross section, and the C-C′ cross section satisfied the requirement of 1,200 lux or less, which was the reference value specified by the JIS standard (JIS T5753: 2012 dental illuminator), at a position 60 mm or more away from the center of light of the illumination device11in the Y axis direction. Further, as illustrated in the B-B′ cross section and the C-C′ cross section, the result ofFIG. 21showed that the illuminance was reduced to around 50 lux at the position of 60 mm in the Y axis direction from the center of the light, and the remarkable improvement in the cutoff characteristics was seen. Therefore, it was confirmed that the burden on the patient's eyes could be remarkably reduced by performing examination and treatment by using the illumination device11of the present embodiment.

According to the present embodiment, the following can be said. The illumination device11includes a plurality of light emitting elements16provided on a surface21intersecting with an optical axis, and a plurality of reflectors23provided so as to correspond to the plurality of light emitting elements16, and each of the plurality of reflectors23includes a plurality of reflectors23having a curved cross section having at least one focal point33. The plurality of reflectors23include: at least one first reflector23A provided corresponding to a central first region21A corresponding to the optical axis18on the surface21intersecting with the optical axis, each of the at least one first reflector23A being providing so as to position one of the plurality of corresponding light emitting elements16within a focal region43in the vicinity of the focal point33; and at least one second reflector23B provided corresponding to a second region21B positioned on the surface21intersecting with an optical axis deviated from the first region21A in the direction intersecting with the optical axis18, each of the at least one second reflector23B having an angular eccentricity so as to collect light on one region35on the optical axis18and being provided so as to position within a margin region41in which one of the plurality of corresponding light emitting elements16is provided at a position away from each of the at least one second reflector23B rather than the second focal region42in the vicinity of the focal point33.

According to this configuration, by positioning the corresponding light emitting element16in the margin region41in the second reflector23B corresponding to the second region21B where blurring (light diffusion) in which the irradiation pattern protrudes from the illumination target region37easily occurs, it is possible to efficiently prevent disturbance of the illuminance distribution in which light enters the patient's eyes when the patient's mouth is irradiated with light. Due to this, it is possible to realize the ideal illumination device11in which the burden on the patient's eyes is reduced while securing sufficient illuminance so that the inside of the mouth can be illuminated brightly.

The at least one second reflector23B includes one second reflector23B positioned on the first region21A side, and the other second reflector23B provided at a position farther away from the first region21A than the second reflector23B. A distance from the apex34of the curve of the other second reflector23B to one of the plurality of light emitting elements16corresponding to the other second reflector23B is larger than a distance from the apex34of the curve of the one second reflector23B to one of the plurality of light emitting elements16corresponding to the one second reflector23B.

According to this configuration, it is possible to ensure a long distance between the apex34of the curved surface of the second reflector23B and the light emitting element16as much as the second reflector23B and the light emitting element16positioned farther from the so-called first region21A. Due to this, the convergence (degree of convergence) of the light irradiated from the light emitting element16can be increased at a position away from the first region21A where the irradiation pattern protrudes from the illumination target region37, which is likely to cause blurring. Therefore, it is possible to more effectively prevent disturbance of the illuminance distribution caused by the light irradiated from the second reflector23B and the light emitting element16positioned away from the first region21A.

The margin region41is defined as a region between a point where a distance equivalent to 1% of the distance from the apex34of the curve to the focal point33is moved in the direction away from the apex34in the direction along the optical axis18from the focal point33and a point where a distance equivalent to 10% of the distance from the apex34of the curve to the focal point33is moved in the direction away from the apex34in the direction along the optical axis18from the focal point33. According to this configuration, the range where the convergence of the light irradiated from the light emitting element16is the most excellent can be set as the margin region41.

The focal region43and the second focal region42are defined as a region between a point where a distance equivalent to 0% or more and less than 1% of the distance from the apex34of the curve to the focal point33is moved in the direction approaching the apex34in the direction along the optical axis18from the focal point33and a point where a distance equivalent to 0% or more and less than 1% of the distance from the apex34of the curve to the focal point33is moved in the direction away from the apex34in the direction along the optical axis18from the focal point33. According to this configuration, the position in the vicinity of the focal point33can be set as the focal region43and the second focal region42.

The plurality of light emitting elements16are linearly disposed in the direction intersecting with the optical axis18. In this way, when the light emitting elements16are linearly aligned, the distance from the central first region21A becomes farther toward the end portion of the array of the light emitting elements16. According to the above configuration, it is possible to efficiently prevent the blurring in which the irradiation pattern protrudes from the illumination target region37by the light irradiated from the second reflector23B and the light emitting element16on the end portion side, thereby preventing disturbance of the illuminance distribution when the patient's mouth is irradiated with light.

Each of the plurality of light emitting elements16is an LED. According to this configuration, it is possible to provide the illumination device11with energy saving as the whole illumination by adopting an energy-saving LED as the light emitting element16.

The illumination device11includes a substrate24provided so as to face a plurality of reflectors23, a plurality of opening portions27provided in the substrate24so as to expose the plurality of reflectors23, and a plurality of support portions25provided on the substrate24, wherein each of the plurality of support portions25includes a plurality of support portions25positioned inside each of the plurality of opening portions27and supports each of the plurality of light emitting elements16.

According to this configuration, a structure that supports the light emitting element16and also supplies power to the light emitting element16can be realized by the substrate24. Therefore, it is possible to realize the illumination device11that can reduce the number of parts and can make the entire structure compact.

The plurality of light emitting elements16are provided on the surface sides of the plurality of support portions25that face the plurality of reflectors23. According to this configuration, it is possible to realize the illumination device11that further reduces the burden on the patient, without the situation in which the light from the LED with higher brightness than the other light sources directly enter the patients' eyes.

Each of the plurality of support portions25provided at positions corresponding to the second region21B is deviated in the direction away from the first region21A with respect to each center of at least one second reflector23B corresponding thereto. According to this configuration, the configuration in which the optical axis (individual optical axis36) of the individual light emitting element16is inclined in the direction approaching the optical axis18of the entire illumination device11can be realized by a simple structure.

The magnitude of the positional deviation becomes larger as the distance from the first region21A increases. According to this configuration, the configuration in which the inclination of the optical axis (individual optical axis36) of the individual light emitting element16is increased as the distance from the first region21A increases can be realized by a simple structure.

Hereinafter, a modification of the illumination device11of the first embodiment will be described with reference toFIGS. 22 and 23. In the following modification, parts different from the first embodiment will be mainly described, and illustration and explanation of parts common to the first embodiment will be omitted.

Second Modification of First Embodiment

Subsequently, a second modification of the illumination device11of the first embodiment will be described with reference toFIG. 22. The illumination device11of the second modification is different from the illumination device11of the first embodiment in that a mirror block22is divided into each unit for each reflector23.

In the present modification, the mirror block22is divided into individual blocks44corresponding to each reflector23. Therefore, the distance between an apex34of a curve of a second reflector23B and a focal point33can be freely changed. Therefore, for example, the position (height) of the individual block44can be finely adjusted by providing a position adjustment knob (screw) on a support body13of the illumination device11. Therefore, the illumination device11of the present modification is particularly useful when it is desired to change the convergence (degree of convergence) of light according to the usage situation, and the like.

Third Modification of First Embodiment

Subsequently, a third modification of the illumination device11of the first embodiment will be described with reference toFIG. 23. The illumination device11of the third modification differs from the illumination device11of the first embodiment in that the distance between the apex34of the curve of the second reflector23B and the corresponding light emitting element16is adjusted by changing the height of the surface of the substrate24.

In the present modification, as the distance from the first region21A increases, the height of the surface of the substrate24on the side facing the reflector23, that is, the position of the surface of the substrate24with respect to the direction of the optical axis18gradually decreases (inFIG. 23, the position of the surface of the substrate24is gradually shifted upward). Such a structure can be realized by, for example, the following method. The substrate24is constituted by a multilayer substrate and may be configured so that the number of layers constituting the substrate24gradually decreases as the distance from the first region21A increases, and the thickness thereof gradually decreases. Alternatively, the substrate24may be formed as one stepped substrate by bonding a plurality of substrates in a stepwise fashion while electrically connecting the plurality of substrates, and the height of the surface of the substrate24may be gradually lowered.

In the present modification, the first reflector23A corresponding to the center (the first region21A) of the illumination device11was formed so that the light emitting element16was positioned within the focal region43and the light emitting element16was formed so as to have a positional deviation amount of ±0.0 mm with respect to the focal point33. This arrangement is an example, and the first reflector23A corresponding to the first region21A may be at any position as long as the position is within the range of the focal region43(within a range between a point moved by a distance of less than 0.10 mm in the direction approaching the first reflector23A in the direction of the optical axis18from the focal point33and a point moved by a distance of less than 0.10 mm in the direction away from the first reflector23A in the direction of the optical axis18from the focal point33or in the direction of the individual optical axis36).

The second reflector23B corresponding to the first region21A side (in the vicinity of the first region21A) of the second region21B was formed so that the light emitting element16was positioned within the margin region41and the light emitting element16had a positional deviation amount of +0.2 mm with respect to the focal point33. At this time, the light emitting element16corresponding to the second reflector23B was disposed at a position 0.2 mm lower than the height of the light emitting element16corresponding to the first reflector23A (inFIG. 23, the position 0.2 mm above the light emitting element16corresponding to the first reflector23A). Therefore, the light emitting element16is disposed at a position deviated by +0.2 mm in the direction away from the second reflector23B in the direction of the optical axis18from the focal point33. The positional deviation amount of the second reflector23B corresponding to the first region21A side of the second region21B is an example, and the same positional deviation amount as in the first embodiment can be obtained.

The second reflector23B corresponding to the center of the second region21B was formed so that the light emitting element16was positioned within the margin region41and the light emitting element16had a positional deviation amount of +0.4 mm with respect to the focal point33. At this time, the light emitting element16corresponding to the second reflector23B was disposed at a position 0.4 mm lower than the height of the light emitting element16corresponding to the first reflector23A (inFIG. 23, the position 0.4 mm above the light emitting element16corresponding to the first reflector23A). Therefore, the light emitting element16is disposed at a position deviated by +0.4 mm in the direction away from the second reflector23B in the direction of the optical axis18from the focal point33. The positional deviation amount of the second reflector23B corresponding to the center of the second region21B is an example, and the same positional deviation amount as in the first embodiment can be obtained.

The second reflector23B corresponding to the end portion side (side away from the first region21A) of the second region21B was formed so that the light emitting element16was positioned within the margin region41and the light emitting element16had a positional deviation amount of +0.5 mm with respect to the focal point33. At this time, the light emitting element16corresponding to the second reflector23B was disposed at a position 0.5 mm lower than the height of the light emitting element16corresponding to the first reflector23A (inFIG. 23, the position 0.5 mm above the light emitting element16corresponding to the first reflector23A). Therefore, the light emitting element16is disposed at a position deviated by +0.5 mm in the direction away from the second reflector23B in the direction of the optical axis18from the focal point33. The positional deviation amount of the second reflector23B corresponding to the end portion side of the second region21B is an example, and the same positional deviation amount as in the first embodiment can be obtained.

The same operations and effects as those of the first embodiment can also be exerted by the illumination device11of the present modification.

Second Embodiment

Hereinafter, an illumination device11of a second embodiment will be described with reference toFIGS. 24 and 25. The second embodiment differs from the first embodiment in that the illumination unit12is constituted by one illumination unit. Hereinafter, parts different from those of the first embodiment will be mainly described, and the illustration and explanation of parts common to those of the first embodiment will be omitted.

The illumination device11includes a support body13, a lamp shade portion14provided in a frame shape so as to be continuous with the support body13, a transmissive cover15provided so as to cover a distal end portion of the lamp shade portion14(end portion on the opposite side to an end portion on the support body13side), and one illumination unit12(array of light emitting elements16) fixed to the support body13. The support body13is supported by an arm or the like. For example, the support body13can be supported at a predetermined position and angle through the arm so as to face a patient. An optical axis18(illumination optical axis) of the illumination device11as a whole is defined by a set of light irradiated from a plurality of light emitting elements16described later. The optical axis18(illumination optical axis) passes through the central portion of the support body13and coincides with the central axis that intersects (orthogonally) with the support body13.

Further, a surface21intersecting with the optical axis can be defined in the illumination device11. As an example of the surface21intersecting with the optical axis, a surface orthogonal to the optical axis18can be mentioned, but is not limited thereto. Another example of the surface21intersecting with the optical axis may be a surface substantially orthogonal to the optical axis18.

The surface21intersecting with the optical axis has a first region21A at the center corresponding to the optical axis18and a second region21B deviating from the first region21A in a direction intersecting with the optical axis18. In the present embodiment, an example of the direction intersecting with the optical axis18is a horizontal direction (lateral direction), but the present embodiment is not limited thereto. For example, the direction intersecting with the optical axis18may be a vertical direction (longitudinal direction).

The configuration of the illumination unit12is the same as that in the first embodiment. The plurality of light emitting elements16are linearly provided at substantially constant intervals on the surface21intersecting with the optical axis in the direction intersecting with the optical axis18.

According to the present embodiment, it is possible to exert substantially the same operations and effects as those of the first embodiment. In the present embodiment, the illuminance of the illumination device11is reduced by the small number of the light emitting elements16, but for example, in addition to the illumination device11of the first embodiment, it is particularly useful in the case where it is desired to provide a low-cost low-price illumination device11as another product lineup.