JP3686660B2 - Light irradiation device and optical unit - Google Patents

Description

  The present invention relates to a light irradiation apparatus that emits light from a columnar light guide using an LED as a light source and an optical unit used for the light irradiation apparatus, and more particularly to a light irradiation apparatus that is suitably used for dentistry and product inspection.

  Recently, a high-brightness LED called a power LED has been developed, and the use of the LED has been greatly expanded. For example, a light irradiation device that guides light emitted from an LED to a transparent rod and is used for dentistry from the tip of the light, or similarly guides light emitted from an LED to an optical fiber bundle. A light irradiation device or the like that has been derived from the tip of the laser and used to detect product defects and marks has been developed.

By the way, in such a light irradiation apparatus, in order to guide the light emitted from the LED to a light guide such as a transparent rod without waste as much as possible, an optical unit is interposed between them. As this optical unit, for example, as shown in Patent Document 1, an optical unit using a transparent and solid bowl-shaped body is known. A recess is provided in the base end surface of the body, and the LED is disposed in the recess. The light emitted from the LED is totally reflected on the curved side surface of the body or directly emitted from the front end surface of the body. On the other hand, the front end surface is flat, and the front end surface is tightly connected to the light guide surface of the light guide so that substantially all light emitted from the LED is introduced into the light guide.
JP 2003-227974 A

  However, according to the body having the above-described shape, a certain diameter is required on the front end surface because of the design reason that the light must be totally reflected on the curved side surface. A similar diameter is required for the light guide, and the light guide cannot be made thinner than a certain amount in the light introduction portion. For this reason, when a light guide with a small diameter is required, such as for dentistry, the diameter of the light guide is squeezed from the front end or halfway. There is a problem that loss or directivity changes.

  In addition, since the light reflected from the curved side and the light directly reaching the curved side from the LED are mixed inside the body, the direction and the amount of light emitted from the tip surface are designed to be uniform. It is difficult. As a result, when the object is irradiated with light output from the body via the light guide, there is a problem that the light intensity is uneven and partly looks dark.

  The present invention has been made in view of such inconveniences, and is capable of efficiently introducing light emitted from an LED into a light guide having various diameters including a thin diameter, while having a compact configuration. The main aim of the present invention is to provide an optical unit capable of making the light irradiated from the light guide to the irradiation target region very uniform and a light irradiation device using the optical unit. .

  That is, the present invention relates to an LED that is a light source, a columnar light guide such as an optical fiber or a glass rod that receives light emitted from the LED and emits light from the tip, and is interposed between the LED and the light guide. An optical unit for transmission,

  The optical unit has a concave portion for accommodating an LED opened on a base end surface of a body having a rotating body shape centered on the optical axis, a central convex lens portion formed at a central portion of the front end surface of the body, and a center thereof A ring-shaped convex lens portion formed around the convex lens portion, and a curved bulging surface that is formed on the side surface of the body and totally reflects the light from the LED inward,

The bottom surface of the concave portion is a convex lens shape bulging toward the base end surface side, and the side surface of the concave portion is a tapered surface that gradually expands toward the base end surface side, and the light emitted from the LED Among them, substantially all of the light passing through the side surface of the concave portion reaches the curved bulging surface and is totally reflected, and is emitted to the outside as light in a direction close to each other via the ring-shaped convex lens portion, While substantially all the light passing through the bottom surface of the recess is configured to be emitted to the outside as light in a direction close to each other via the central convex lens portion,

  The light intensity at each angle included in the light emitted to the outside is made substantially constant, and the light is incident on the light receiving surface of the light guide set at a predetermined distance from the tip surface. It is a light irradiation apparatus or its optical unit.

  If this is the case, the light emitted from the body travels in the direction toward the optical axis, and the body and the light guide are separated from each other. Light can be easily introduced into a thin light guide.

  Further, since the light intensity at each angle included in the light emitted to the outside is substantially constant, the illuminance on the irradiation surface of the light emitted from the light guide is uniform and suitable for inspection and the like.

  Further, among the light emitted from the LED, the path of light (light passing through the side surface of the recess) that spreads more than a certain angle and the path of light that does not (light passing through the bottom surface of the recess) are completely within the body. Therefore, the design considering the direction of the light emitted from the front end surface of the body and the uniformity of the light quantity becomes very easy, and the above-described effects can be realized without difficulty.

  In addition, for light that spreads more than a certain angle, the exit direction can be set by three parameters: the refraction angle at the side surface of the concave portion, the total reflection angle at the curved bulging surface, and the refraction angle at the ring-shaped convex lens portion. The degree of freedom in designing the shape and size is greatly increased, and further, it is possible to suppress as much as possible a problem that a light amount loss occurs due to refraction or reflection at each part.

  On the other hand, almost all of the light radiated to the outside falls within the light receiving surface of the light guide set at a predetermined distance from the tip surface, and the illuminance within the fixed effective diameter is substantially uniform. For example, when the light guide is an optical fiber bundle, light can be uniformly introduced into each optical fiber.

  Preferably, the condensing position of the light emitted from each convex lens portion is set at substantially the same position.

Furthermore, if the distance between the front end surface and the light receiving surface of the light guide can be changed, it is effective for fine adjustment in assembly and can easily cope with a change in the diameter of the light guide. .
In order to make the effect of the present invention more remarkable, it is ideal that the LED can be regarded as a point light source. For this purpose, the LED is formed by joining a P-type semiconductor and an N-type semiconductor, and is a flat substrate. It is desirable to be mounted on.
Further, in order to reliably reflect and emit light from the LED with the optical unit, and to efficiently dissipate heat, the LED is mounted on the substrate via a spacer, and among the side surfaces of the LED, It is desirable that a surface close to a boundary portion between the P-type semiconductor and the N-type semiconductor is on the substrate side.

  An embodiment of the present invention will be described below with reference to the drawings.

  As shown in FIGS. 1 to 4, the light irradiation device 1 according to the present embodiment receives an LED 21 that is a light source and a light L emitted from the LED 21 and emits it from a front end surface (not shown). , An optical unit 4 interposed between the LED 21 and the optical fiber bundle 3, and a casing (not shown) that accommodates and holds the LED 21, the optical unit 4, and at least the light introduction portion of the optical fiber bundle 3. For example, in dentistry, it is preferably used when the resin packed in the teeth is cured by the light L emitted from the tip of the optical fiber bundle 3.

  Each part will be described in detail. As shown in FIGS. 6 to 8, the LED 21 is a so-called power LED that can flow a current of 200 mA or more, and is mounted on a substrate 22 via a spacer SP. A package 2 is formed. In addition, the code | symbol 24 is the hemispherical transparent solid resin cover attached in order to protect LED21.

  Specifically, the LED 21 has a surface mount type very small rectangular block shape, has a PN junction structure, and is extremely thin (several tens of μm) on the bottom surface of one semiconductor layer (for example, P layer) 211. The semiconductor layer (for example, N layer) 212 is provided. In general, the LED emits light at the boundary between the P layer and the N layer, and heat is also generated at that portion, but this LED 21 has much more power consumption and generated heat than a normal LED. In order to efficiently dissipate heat, the surface close to the boundary portion, that is, in this embodiment, the bottom surface is set as a bonding surface that is in close contact with the substrate 22 side, contrary to a normal LED.

  The substrate 22 is a plate having a substantially circular shape in plan view, and is mainly composed of a heat radiating member 221 made of aluminum. The top surface of the heat radiating member 221 is covered with a thin layer of insulator 222, and A wiring pattern C is provided on the insulator 222. The insulator 222 is made of, for example, a polyimide resin, an epoxy resin, or the like, and has an extremely thin layer of several tens of μm so as not to hinder heat conduction. The wiring pattern C is a thin one of several μm formed by applying gold (silver) plating to a copper foil. In this embodiment, a pair of positive and negative wiring patterns C (1) and C (2) are provided, and each of them is a wire W. It is connected to the P layer 211 and the N layer 222 via

  The spacer SP is a solid rectangular block having an area larger than that of the LED 21, for example, an insulating material made of aluminum nitride, and the LED 21 is bonded to the top surface thereof using a gold-tin alloy. It is like that. The spacer SP formed by attaching the LED 21 is soldered onto the substrate 22 using cream solder or the like.

  As shown in FIG. 1 and the like, the optical fiber bundle 3 is a light receiving surface 3a in which the light introduction end faces of the optical fibers are aligned and tightly bundled. In this embodiment, a plastic fiber is used.

  As shown in FIGS. 1 to 4, the optical unit 4 includes a solid transparent body 41 having a rotating body shape so that a cross-sectional area gradually increases from the base end surface 4 a toward the front end surface 4 b. It is a thing.

  A recess 42 for accommodating the LED 21 is opened on the body base end face 4a. The bottom surface 42a of the concave portion 42 has a convex lens shape that swells toward the base end surface 4a, and the side surface 42b is a tapered surface that gradually expands toward the base end surface 4a. On the other hand, a central convex lens portion 43 is formed on the front end surface 4b of the body by bulging the central portion, and a ring-shaped convex lens portion 44 having a different curvature is formed around the central convex lens portion 43. It is formed. Further, a curved bulging surface 45 formed so that the cross-sectional contour forms a parabola is provided on the side surface of the body 41.

  In the present embodiment, as shown particularly in FIG. 4, among the light L emitted from the LED 21, almost all the light L that has passed through the side surface 42 b of the recess 42 reaches the curved bulging surface 45. Therefore, the light is totally reflected and radiated to the outside as light L in a direction close to each other toward the optical axis via the ring-shaped convex lens portion 44. On the other hand, among the light L emitted from the LED 21, substantially all the light L that has passed through the bottom surface 42 a of the concave portion 42 passes through the central convex lens portion 43 and is also directed toward each other toward the optical axis. L is emitted to the outside. The condensing position of the light L emitted from the convex lens portions 43 and 44 is set to be substantially the same position.

  Then, as shown in FIG. 5, substantially all the light L emitted from the LED 21 and radiated to the outside from the body front end surface 4b of the optical unit 4 is set at a position separated from the front end surface 4b by a predetermined distance. It is configured such that the illuminance within the light receiving surface 3a of the fiber bundle 3 and within a certain effective diameter thereof changes substantially uniformly or smoothly. In FIG. 5, among the light rays emitted from the LEDs, the ones traveling to the side are narrower when leaving the optical unit, but the light emitted from the LEDs is weaker as the ones emitted from the side. Actual illuminance is substantially uniform as described above.

  In addition, in the present embodiment, the light intensity at each angle included in the light L emitted to the outside is substantially constant or changes smoothly according to the angle.

  According to the present embodiment configured as described above, it is possible to obtain a basic effect that the light L emitted from the LED 21 can be emitted from the front end surface 4b of the body 21 without leaking with only the single body 41.

  Further, since the light L emitted from the body 41 proceeds toward the optical axis, and the body 41 and the light receiving surface 3a of the optical fiber bundle 3 are separated from each other, the separation distance is appropriately set. Thus, light can be easily introduced into the very thin optical fiber bundle 3.

  Furthermore, since the light intensity at each angle included in the light L emitted to the outside is substantially constant, the illuminance on the irradiation surface of the light L emitted from the optical fiber bundle 3 becomes uniform. At the same time, the illuminance of the light L radiated to the outside is substantially uniform within a certain effective diameter on the light receiving surface 3a of the optical fiber bundle 3, so that the light L can be uniformly introduced into each optical fiber.

  Of the light L emitted from the LED 21, the path of the light L (light passing through the concave side surface 42 b) that spreads by a certain angle and the path of the light L (light passing through the concave bottom surface 42 a) that is not so are the body. 41, since it is completely separated in 41, the design considering the direction of the light L emitted from the body front end surface 4b and the uniformity of the light amount can be reasonably possible as described above. That ’s it.

  In particular, for the light L spreading above a certain angle, the emission direction can be set by three parameters: the refraction angle at the concave side surface 42b, the total reflection angle at the curved bulging surface 45, and the refraction angle at the ring-shaped convex lens portion 44. In addition, the degree of freedom in designing the shape and size of the body 41 is greatly increased, and problems such as a loss of light amount due to refraction or reflection at each part can be suppressed as much as possible. On the other hand, also for the light L within a certain angle, the refraction angle at the two locations of the concave bottom surface 42a and the central convex lens portion 43 can be set.

  The present invention is not limited to the above embodiment. For example, a rod lens or a single optical fiber may be used instead of the optical fiber bundle, or a rod lens may be interposed between the light introduction end face of the optical fiber bundle and the optical unit. In this way, the uniformity of the light introduced into the optical fiber bundle is further improved.

  Furthermore, if the distance between the front end surface of the body and the light receiving surface of the light guide can be changed, it is effective for fine adjustment during assembly and can easily respond to changes in the diameter of the light guide. .

  Although not shown, the casing is integrally provided with a heat dissipation structure such as a fin, and when the LED, the optical unit, and the light guide are incorporated in the casing, a positioning structure is provided for positioning them, and the positioning is further performed. If it is a light irradiation apparatus which has the contact | adherence press structure which closely_contact | adheres LED to a casing in connection with, it is more suitable. With such a configuration, for example, heat can be effectively radiated while maintaining compactness, and the light emitted from the LED can be effectively transmitted to the light guide by the optical unit by the positioning structure.

  Specifically, the first casing element includes an LED and an optical unit, and a casing that includes the LED and the optical unit and has a heat dissipation portion, and the casing is connected in series along a predetermined axis. A second casing element, and a first pressing surface provided on the first casing element side and a second pressing surface provided on the second casing element side when the casing elements are coupled to each other. A close-contact pressing structure for narrowly fixing the LED and the optical unit between them, and a positioning structure for positioning the LED and the optical unit so that the optical axes of the LED and the optical unit coincide with the axis along with the coupling. Can be listed.

  In addition, a Fresnel lens structure may be employed for each convex lens portion, and not only the concave bottom surface but also the concave side surface may be curved to form a lens surface.

  Of course, the present invention is not limited to the light irradiation device for dentistry, and may be used for the purpose of changing the material form such as resin curing. For example, the tip portion of the optical fiber bundle is discretely arranged to perform product inspection or alignment mark detection. You may make it use for the objectives.

  In addition, the present invention is not limited to the above-described embodiment and the like, and various modifications can be made without departing from the spirit of the present invention.

1 is a schematic overall view of a light irradiation apparatus according to an embodiment of the present invention. The top view of the optical unit in the embodiment. The bottom view of the optical unit in the embodiment. Operation | movement explanatory drawing which shows operation | movement of the light irradiation apparatus in the embodiment. The illumination intensity graph which shows the relationship between the illumination intensity in the light-receiving surface in the same embodiment, and a position. The fragmentary longitudinal cross-section which shows the LED package in the embodiment. The top view which shows the LED package in the embodiment. The expanded partial longitudinal cross-sectional view which shows LED in the same embodiment.

Explanation of symbols

L ... Light 21 ... LED
3. Light guide (fiber optic bundle)
4 ... Optical unit 41 ... Body 42 ... Concave 43 ... Central convex lens part 44 ... Ring-shaped convex lens part 45 ... Curve bulging surface 4a ... Base end surface 4b ... Tip surface

Claims (11)

A light irradiation device comprising: an LED as a light source; a columnar light guide that receives light emitted from the LED and emits light from the tip; and an optical unit that is interposed between the LED and the light guide and transmits light Because
The optical unit has a concave portion for accommodating an LED opened on a base end surface of a body having a rotating body shape centered on the optical axis, a central convex lens portion formed at a central portion of the front end surface of the body, and a center thereof A ring-shaped convex lens portion formed around the convex lens portion, and a curved bulging surface that is formed on the side surface of the body and totally reflects the light from the LED inward,
The bottom surface of the concave portion is a convex lens shape bulging toward the base end surface side, and the side surface of the concave portion is a tapered surface that gradually expands toward the base end surface side,
Of the light emitted from the LED, substantially all of the light passing through the side surface of the concave portion is totally reflected by the curved bulging surface and radiated to the outside through the ring-shaped convex lens portion as light in a direction close to each other. On the other hand, it is configured to radiate almost all the light passing through the bottom surface of the concave portion to the outside as light in a direction close to each other via the central convex lens portion,
The light intensity at each angle included in the light emitted to the outside is made substantially constant, and the light is incident on the light receiving surface of the light guide set at a predetermined distance from the tip surface. A light irradiation apparatus characterized by being a thing. An LED that is a light source, a columnar light guide such as an optical fiber or a glass rod that receives light emitted from the LED and emits it from the tip, and an optical unit that transmits light by being interposed between the LED and the light guide A light irradiation device comprising:
The optical unit has a concave portion for accommodating an LED opened on a base end surface of a body having a rotating body shape centered on the optical axis, a central convex lens portion formed at a central portion of the front end surface of the body, and a center thereof A ring-shaped convex lens portion formed around the convex lens portion, and a curved bulging surface that is formed on the side surface of the body and totally reflects the light from the LED inward,
The bottom surface of the concave portion is a convex lens shape bulging toward the base end surface side, and the side surface of the concave portion is a tapered surface that gradually expands toward the base end surface side,
Of the light emitted from the LED, substantially all of the light passing through the side surface of the concave portion is totally reflected by the curved bulging surface and radiated to the outside through the ring-shaped convex lens portion. On the other hand, it is configured to radiate substantially all the light passing through the bottom surface of the concave portion to the outside as light in a direction close to each other via the central convex lens portion,
The configuration is such that almost all of the light radiated to the outside falls within the light receiving surface of the light guide set at a predetermined distance from the tip surface, and the illuminance within the fixed diameter is substantially uniform. A light irradiation apparatus characterized by being a thing. The light irradiation apparatus according to claim 1, wherein the LED is formed by bonding a P-type semiconductor and an N-type semiconductor and mounted on a flat substrate. 2. The LED is mounted on the substrate via a spacer, and a surface close to a boundary portion between the P-type semiconductor and the N-type semiconductor among the side surfaces of the LED is the substrate side. 2. The light irradiation device according to 2 or 3. The light guide according to claim 1, 2, 3 or 4 light irradiation device, wherein the rod lens. The light guide according to claim 1, 2, 3 or 4 light irradiation apparatus, wherein the optical fiber bundle. The LED is claim 1, 2, 3 is a power LED that can flow continuously over current 200 mA, 4, 5 or light irradiation device according 6. The Set condensing position of light emitted from the convex lens portion at substantially the same position and claims 1, 2, 3, 4, 5, the light irradiation device 6 or 7, wherein. The distal end surface and the light guide of the light-receiving surface and the distance modifiable configured to have claim 1, 2, 3, 4, 5, 6 or 7 light irradiation device according. It has a transparent body that forms a rotating body around the optical axis,
A concave portion for accommodating the LED opened at the base end surface of the body, a central convex lens portion formed at a central portion of the distal end surface of the body, a ring-shaped convex lens portion formed around the central convex lens portion, and the body And a curved bulging surface that totally reflects inward light from the LED,
The bottom surface of the concave portion is a convex lens shape bulging toward the base end surface side, and the side surface of the concave portion is a tapered surface that gradually expands toward the base end surface side,
Of the light emitted from the LED, substantially all of the light passing through the side surface of the concave portion reaches the curved bulging surface and is totally reflected, and is directed toward each other via the ring-shaped convex lens portion. While configured to radiate outside, substantially all of the light passing through the bottom surface of the concave portion is radiated to the outside as light in a direction close to each other via the central convex lens portion,
An optical unit characterized in that the light intensity at each angle included in the light emitted to the outside is substantially constant. It has a transparent body that forms a rotating body around the optical axis,
A concave portion for accommodating the LED opened at the base end surface of the body, a central convex lens portion formed at a central portion of the distal end surface of the body, a ring-shaped convex lens portion formed around the central convex lens portion, and the body And a curved bulging surface that totally reflects inward light from the LED,
The bottom surface of the concave portion is a convex lens shape bulging toward the base end surface side, and the side surface of the concave portion is a tapered surface that gradually expands toward the base end surface side,
Of the light emitted from the LED, substantially all of the light passing through the side surface of the concave portion reaches the curved bulging surface and is totally reflected, and is directed toward each other via the ring-shaped convex lens portion. While configured to radiate outside, substantially all of the light passing through the bottom surface of the concave portion is radiated to the outside as light in a direction close to each other via the central convex lens portion,
An optical unit characterized in that substantially all of the light emitted to the outside is configured so that the illuminance within a certain diameter is substantially uniform.