JP2010165477A - Light irradiation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light irradiation device which is easy to manufacture, high in yield, compact in the thickness direction, and by using various LEDs as a light-emitter, capable of uniformly radiating light without unevenness. <P>SOLUTION: The device includes a flat substrate having an observation hole in the center, a plurality of light-emitters juxtaposed in a plurality of rows in a concentric form in its flat substrate, and the same number of lenses as that of the light-emitters installed opposed to the flat substrate, and an optical axis of the light-emitters is parallel to the axial line of the concentric circle and the optical axis of the respective light-emitters and the optical axis of the corresponding respective lenses are made different. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a light irradiation device that is suitably used for product inspection and the like.

  As a method for inspecting the surface of a workpiece such as a product, a method for inspecting the workpiece by illuminating the workpiece using a light irradiation device that emits light from the bottom and performing visual inspection or photographing is generally known. Among the apparatuses for performing such surface inspection, as shown in Patent Document 1, the bottom surface of the light irradiation apparatus is a truncated conical concave surface as used when the inspection surface is three-dimensional, and the truncated cone. A lot of LEDs are arranged vertically on the concave surface so that the work can be illuminated from almost all the sky except the observation hole so that it can cover not only from one direction but also from the surrounding direction. Yes.

  More recently, as shown in Patent Document 2, a plurality of LEDs are soldered and disposed on a flexible wiring board having a predetermined annular shape, and the edges of the flexible wiring board are attached to each other. There is a large market for light irradiating devices that are curved in a straight line so that the LED can be arranged and wired on the truncated conical concave surface and the formation of the truncated conical concave surface can be easily and accurately performed at once.

JP-A-8-106809 Japanese Patent Laid-Open No. 10-21729

  Conventionally, the face-up type (cannonball type) LED used in such a light irradiation device is composed of an epoxy resin whose resin mold part is transparent and excellent in moldability. Epoxy resins are prone to resin degradation due to light, and have a problem that they have low heat resistance and deteriorate during soldering. For this reason, careful attention is required when soldering the bullet-type LED to the substrate, resulting in a complicated manufacturing process and a reduction in productivity.

  In addition, polycarbonate and acrylic resins, which are transparent as well as epoxy resins and have excellent moldability, are light resistant and hardly cause resin deterioration due to light, but are also inferior in heat resistance. Even if it is used for the resin mold part of the LED, the reliability during soldering is not sufficient.

  On the other hand, by combining LED elements that emit blue light or ultraviolet rays and various fluorescent materials using a gallium nitride compound semiconductor, recently, light of a color different from the emission color of LED elements such as white light can be obtained. LEDs that emit light have been developed. As such an LED, a flip chip type in which a silicone resin in which a fluorescent material is dispersed is accommodated in a concave base body on which an LED element is mainly mounted is used. However, although silicone resin has durability against both heat and light, it has a defect that it is easily damaged because of its low hardness.

  Furthermore, if the flexible wiring board is bent into a truncated conical shape as in the conventional light irradiation device, the location where the LED is soldered to the board is distorted and the electrical communication is disconnected. Is likely to occur, causing a decrease in yield.

  The present invention has been made in view of such problems, is easy to manufacture, has a high yield, is compact in the thickness direction, and uniformly irradiates light using various LEDs as a light emitter. Providing a light irradiating device that can perform the above-mentioned is a main intended task.

  That is, the light irradiation apparatus according to the present invention includes a planar substrate having an observation hole in the center, a plurality of light emitters arranged in a plurality of rows concentrically on the planar substrate, and the planar substrate facing the planar substrate. And the optical axis of the light emitter is parallel to the axis of the concentric circle, and the optical axis of each light emitter and the optical axis of each lens corresponding thereto are: It is characterized by being different.

  If this is the case, the illuminant is protected by a lens provided opposite to the illuminant, so even if a silicone resin having a low hardness is used for the illuminant, damage to the silicone resin is avoided. Various LEDs including a flip chip type LED can be used as the light emitter. Since it is possible to mount an LED using a silicone resin that has a low hardness but has excellent heat resistance as a light emitter, soldering to a substrate is facilitated, and the manufacturing process can be simplified. it can.

  In addition, according to the present invention, it is possible to refract the light emitted from each light emitter by a separately provided lens and condense it on a predetermined region in the center of the observation hole. Since it is not necessary to bend the substrate into a truncated conical shape after installation, the manufacturing process can be simplified, and distortion is caused in the place where the light emitter is soldered to the substrate. It is possible to improve yield without causing problems such as disconnection. In addition, since the light irradiation apparatus according to the present invention does not need to bend the substrate into a truncated cone shape, it is compact in the thickness direction, is not bulky, and the usable substrate is not limited to one having flexibility. .

  In order to facilitate the assembly, it is preferable that the same number of lenses as the light emitting body are integrally molded to constitute a lens plate.

  The optical axis of the illuminant and the optical axis of each lens corresponding thereto are parallel or intersecting.

  The lens formed on the lens plate is preferably a parallel light generating lens, for example, in order to irradiate light uniformly to the workpiece.

  As the constituent material of the lens plate, polycarbonate or acrylic resin is suitably used because it is transparent, hardly undergoes resin deterioration due to light, has excellent moldability, and has high hardness.

  The shape of the flat substrate is not particularly limited, but is preferably a ring shape from the viewpoint of ease of production, handling properties, and the like.

  Instead of a flat substrate having an observation hole in the center, a flat substrate without an observation hole may be used. That is, such a light irradiation apparatus includes a flat substrate, a plurality of light emitters arranged in a plurality of rows on the flat substrate, and the same number of lenses as the light emitters provided to face the flat substrate. The optical axis of the light emitter is perpendicular to the plane of the planar substrate, and the optical axis of each light emitter and the optical axis of each lens corresponding thereto are different from each other. . Such a light irradiation apparatus can be used as an exposure apparatus of a reduction projection type semiconductor exposure apparatus (stepper).

  Conventionally, mercury lamps have been used as light sources for g-line and i-line steppers, but mercury is subject to EU RoHS regulations (European Hazardous Substances Regulations), which came into effect in July 2006. In addition, the LED used as a light emitter by the light irradiation apparatus according to the present invention has excellent characteristics such as low power consumption, long life, and low heat generation. Therefore, by using the light irradiation device according to the present invention instead of the mercury lamp as the light source of the stepper, it is possible to reduce the burden on the environment and to be advantageous in terms of cost.

  According to the present invention having such a configuration, the manufacturing process can be simplified, the yield can be improved, the thickness direction is compact and not bulky, and various types of light emitters are used as a light source. Thus, it is possible to provide a light irradiation apparatus capable of irradiating the workpiece with uniform light without unevenness.

It is a top view of the light irradiation apparatus in one Embodiment of this invention. It is a longitudinal cross-sectional view of the light irradiation apparatus in the same embodiment. It is a graph which shows the relationship between the eccentric amount of an optical axis, illuminance distribution, and illuminance. It is a perspective view at the time of making the light irradiation apparatus which concerns on the same embodiment into the illuminating device for microscopes. It is an AA 'line end view of the microscope irradiation apparatus shown in FIG. It is a longitudinal cross-sectional view of the light irradiation apparatus in other embodiment of this invention. It is a top view of the light irradiation apparatus in other embodiment of this invention. It is a longitudinal cross-sectional view of the light irradiation apparatus in the same embodiment. It is a top view of a rectangular matrix microlens array. The top view of a hexagonal honeycomb-shaped microlens array.

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

  The light irradiation apparatus 1 according to the present embodiment is used for surface inspection of a product (work), and as shown in FIG. 1 and FIG. 2, forms a schematic ring shape having an observation hole 1a in the center. The ring-shaped holding frame 2, the ring-shaped printed wiring board 3 held in the holding frame 2, the numerous LEDs 4 mounted on the printed wiring board 3, and the holding frame 2 A lens plate 5 having a ring shape is also provided.

  Explaining each part, the holding frame 2 forms a metal block body in a ring shape in plan view, and a bottomed circumferential holding groove for holding the printed wiring board 3 on the inner peripheral surface and outer peripheral surface of the recess. 2a and a bottomed holding groove 2b for holding the lens plate 5 are formed. A flange portion 2c, 2d is provided around each of the holding grooves 2a, 2b so that the inner periphery and the outer periphery of the printed wiring board 3 and the lens plate are engaged with each other.

  The printed wiring board 3 has an insulating property and has a flat ring shape in which wiring is printed in advance and a through hole is formed in the center. The through hole functions as the observation hole 1a.

  The LEDs 4 are of a so-called flip chip type, but each LED 4 is not provided with a lens member. Of course, the LED 4 may be a face-up type (bullet type). The LEDs 4 are mounted on the surface of the printed wiring board 3 in a plurality of rows concentrically around the axis X of the observation hole 1a and perpendicular to the surface. In this embodiment, the number of LEDs 4 in each row is made different, that is, the number of LEDs 4 is increased in the outer row, so that the arrangement density of the LEDs 4 is almost equal.

  The lens plate 5 is formed by integrally forming a plurality of parallel light generating lenses 51 in a plurality of rows concentrically around the axis X of the observation hole 1a, and is transparent such as polycarbonate or acrylic resin. It is made of a resin having high hardness and durability against light. The same number of lenses 51 as the LEDs 4 are formed on the lens plate 5, and each lens 51 is fitted in the circumferential holding groove 2 b of the holding frame 2 so that the lens plate 5 is parallel to the printed arrangement substrate 3. The optical axis Z of the lens 51 is parallel to the optical axis Y of the LED 4 and is shifted from the optical axis Y of the corresponding LED 4 so as to be deviated toward the center of the observation hole 1a. Thereby, the light emitted from each LED 4 is bent in the direction toward the center of the observation hole 1a by the corresponding lens 51, and is condensed as a parallel light in a predetermined region in the direction toward the center of the observation hole 1a.

  The amount of eccentricity of the optical axis Y of each LED 4 and the optical axis Z of each lens 51 corresponding to the LED 4 is adjusted to be larger toward the outer peripheral side and smaller toward the inner peripheral side. Thereby, the light emitted from each LED 4 can be condensed in a narrower region. As shown in FIG. 3, the illuminance and illuminance distribution of the light of the light illuminating device 1 can be freely adjusted by changing the amount of eccentricity. In FIG. 3, in the light irradiation device 1 in which LEDs are provided in a circular shape with a diameter of 100 mm, the center diameter of the lens is changed in three ways (a) to (c) to adjust the eccentricity of the optical axis. The illuminance distribution at the time. The arrow in the graph indicates the half width.

  Further, in this embodiment, the viscoelastic member 6 made of silicone or the like, which has viscoelasticity while having a regularity, is substantially spaced between the bottom surface of the recessed portion of the holding frame 2 and the back surface of the printed wiring board 3. There is no intervention. The viscoelastic member 6 is a flat plate ring having a width substantially the same as the width of the printed wiring board 3, or is composed of one or a plurality of partial ring elements having a predetermined width. The viscoelastic member 6 is deformed so as to envelop the parts such as the leads and resistors of the LED 4 protruding from the back surface of the printed wiring board 3, and the gap between the bottom surface of the concave portion of the holding frame 2 and the back surface of the printed wiring board 3. Is almost completely buried and is in close contact with both sides.

  According to the light irradiation apparatus 1 according to the present embodiment, since the LED 4 is protected by the lens plate 5 provided to face the LED 4, even if a low-hardness silicone resin is used for the LED 4, the silicone resin Therefore, it is possible to use various LEDs 4 including a flip chip type LED. And since it becomes possible to mount what used the silicone resin excellent in heat resistance as LED4 although it is low hardness, soldering to the board | substrate 3 becomes easy and can simplify a manufacturing process. it can.

  Moreover, according to the light irradiation apparatus 1, the light emitted from each LED 4 can be refracted by the lens 51 formed on the lens plate 5 provided separately, and can be condensed in a predetermined region in the central direction of the observation hole 1a. Therefore, since it is not necessary to bend the board 3 in a truncated conical shape after arranging the LED 4 on the printed board 3, the manufacturing process can be simplified and the LED 4 is soldered to the board 3 Therefore, distortion is caused at the arranged locations, and there is no problem such as disconnection of electrical communication, so that the yield can be improved.

  Moreover, since the light irradiation apparatus 1 does not need to curve the printed arrangement board | substrate 3 to a truncated cone shape, it is compact in the thickness direction and is not bulky. In addition, since there is no need to bend the printed arrangement board 3 into a truncated cone shape, the usable printed arrangement board 3 is not limited to one having flexibility.

  The light illumination device 1 having the observation hole 1a in the center according to the present embodiment can be used as a microscope illumination device, for example, as shown in FIGS. When used as a microscope illumination device in this way, the work is observed with the microscope objective lens fitted in the observation hole 1a. In the embodiment shown in FIGS. 4 and 5, each lens 51 is independent, and the lens 51 is fitted into the hole 71 provided in the holding plate 7 so that the tip portion protrudes, thereby each lens 51. Positioning is performed.

  The present invention is not limited to the above embodiment.

  For example, as shown in FIG. 6, each lens 51 may be arranged so as to have an inclination so that its optical axis Z is not parallel to the corresponding optical axis Y of each LED 4. Also in this case, the traveling direction of the light emitted from each LED 4 is bent as in the above embodiment, and is condensed as a parallel light in a predetermined region in the central direction of the observation hole 1a. Further, by changing the inclination of the optical axis Z with respect to the optical axis Y, the range of illuminance distribution and the illuminance can be freely adjusted.

  Moreover, in the said embodiment, although the light irradiation apparatus 1 was the outline ring shape which has the observation hole 1a in the center, as shown to FIG. 7, 8, the holding frame 20 which makes a planar view rectangular shape, respectively, and a print The wiring board 30 and the lens plate 50 may be used and the observation hole 1a may not be provided. Here, a microlens array can be used as the lens plate 50. The planar view shape of each lens 51 constituting the microlens array can be a rectangular shape as shown in FIG. 9 or as shown in FIG. Examples include hexagonal shapes. Further, in this case, the light irradiation apparatus 1 can be used as an exposure apparatus of a reduction projection type semiconductor exposure apparatus (stepper), and according to the present invention using an LED as a light emitter, a stepper using a conventional mercury lamp is used. A stepper with higher exposure efficiency can be configured.

  Further, the lens 51 formed on the lens plate 5 does not have to be a parallel light emitting lens. If the light emitted from each LED 4 can be condensed in the central direction of the observation hole 1a, the lens 51 is collected depending on the application. It is also possible to use an optical lens or the like.

  Furthermore, for example, in order to irradiate light on a larger workpiece, it is preferable that the condensing area of the light emitted from the LED 4 is wider, etc., the optical axis Y of each LED 4 and the corresponding lens 51 of each lens 51 The amount of eccentricity of the optical axis Z may be made uniform between the outer peripheral side and the inner peripheral side.

  In addition, the present invention is not limited to the above-described embodiments, and may be configured by appropriately combining some or all of the various configurations described above without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Light irradiation apparatus 2, 20 ... Holding frame 3, 30 ... Resin printed wiring board 4 ... Light-emitting body (LED)
5, 50 ... Lens plate 51 ... Lens 6 ... Viscoelastic member

Claims (8)

A planar substrate having an observation hole in the center; a plurality of light emitters arranged in a concentric array on the planar substrate; and the same number of lenses as the light emitters provided facing the planar substrate. And
The optical axis of the luminous body is parallel to the axis of the concentric circles,
The light irradiation apparatus according to claim 1, wherein an optical axis of each of the light emitters is different from an optical axis of each of the lenses corresponding thereto.   The light irradiation device according to claim 1, wherein the same number of lenses as the light emitters are integrally molded to constitute a lens plate.   The light irradiation apparatus according to claim 1, wherein an optical axis of the light emitter and an optical axis of each lens corresponding thereto are parallel.   The light irradiation apparatus according to claim 1, wherein an optical axis of the light emitter intersects with an optical axis of each lens corresponding to the light emitter.   The light irradiation apparatus according to claim 1, wherein the lens is a parallel light generating lens.   The light irradiation device according to claim 1, wherein the lens plate is made of polycarbonate or acrylic resin.   The light irradiation apparatus according to claim 1, wherein the planar substrate has a ring shape. A flat substrate, a plurality of light emitters arranged in a plurality of rows on the flat substrate, and the same number of lenses as the light emitters provided facing the flat substrate,
The optical axis of the light emitter is perpendicular to the plane of the planar substrate;
The light irradiation apparatus according to claim 1, wherein an optical axis of each of the light emitters is different from an optical axis of each of the lenses corresponding thereto.