JP2001250409A - Lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting device capable of getting a lighting part close to a work and lighting the work at a high lighting illuminance without enlarging the diameter of the lighting part, and of efficient lighting without center drop of light on a lighted surface even if the lighting part and the work are far apart. SOLUTION: This lighting device enters light from a discharge lamp into an incident end of a light guide F and concentrates light emitted from an emission end of the light guide F on a lighted surface by a projection optics system, and lights a work arranged on the lighted surface. The projection optics system is comprised of a rod lens 40 having spherical surfaces of the same radius of curvature on both ends, a plano-convex lens 50 or a both-side convex lens. Also, this projection optics system is constructed with the rod lens having spherical surface on both ends and a radius of curvature of the emission end spherical surface of the rod lens is kept smaller than the radius of curvature of the incident end spherical surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light irradiating apparatus for performing light processing by guiding light emitted from a discharge lamp by a light guide to irradiate an object (work) disposed on an irradiated surface. Further, the present invention relates to a light irradiation device suitable for performing ultraviolet treatment by irradiating light containing ultraviolet light to a narrow area.

[0002]

2. Description of the Related Art Light emitted from a light irradiation device is irradiated onto an adhesive, paint, ink, resist or the like applied to a work to cure or dry the work. Conversely, various processes such as melting and softening these are performed. In the case of bonding a pickup lens for an optical disk with an ultraviolet-curing adhesive or bonding an electronic component to a substrate, it is necessary to irradiate light in a very small area. The light is guided by a light guide configured to irradiate a minute area.

FIG. 1 shows an example of the internal configuration of a light irradiation device for irradiating a minute area. The mirror 20 is the holding member 30
The discharge lamp 10 is also fixed to the through hole 21 of the mirror 20.
Is fixed to the holding member 30 while being inserted through the holding member 30. The discharge lamp 10 is a short arc type discharge lamp such as a xenon lamp or an ultra-high pressure mercury lamp, for example, in which a cathode 11 and an anode 12 are arranged opposite to each other in an arc tube. The mirror 20 has an elliptical cross-sectional shape, and the bright spot of the light emitting portion between the cathode 11 and the anode 12 of the discharge lamp 10 is located at the first focal point of the mirror 20. Usually, the bright spot of the light emitting portion is near the tip of the cathode. A light guide F on the optical axis L of the mirror 20;
Are arranged, and the light receiving end F of the light guide F
0 is located at the second focal point. In addition, a shutter S is provided between the incident end Fin of the light guide F and the discharge lamp 10.
When the shutter St is opened, the light condensed by the mirror 20 is incident on the incident end Fin of the light guide F. Then, the light emitted from the emission end Fou of the light guide F is applied to a work to be subjected to light irradiation processing, for example, a lens component or a substrate to which an ultraviolet-curable adhesive is applied, which is arranged in a light irradiation area on the irradiated surface. You.

In such a light irradiation device, since the through hole 21 is formed in the central portion of the mirror 20 as described above, there is no reflected light in this portion, and the light reflected by the mirror 20 is not shown in FIG. In FIG. 1, only the light indicated by the dotted diagonal line is incident on the incident end Fin of the light guide F. That is, a large amount of light having a large incident angle is incident on the incident end Fin, and almost no light having a small incident angle near 0 ° is incident.

The light incident on the light input end Fin of the light guide F is repeatedly reflected and transmitted through the light guide F while maintaining the angle as a property of the optical fiber, and is emitted from the light output end Fou at the same angle as the incident angle. I do. As described above, since a large amount of light having a large incident angle is incident on the light guide F, a large amount of light having a large outgoing angle indicated by a hatched dotted line in FIG. 1 is emitted from the outgoing end Fou. Here, if the distance d between the emission end Fou of the light guide F and the surface to be illuminated on which the workpiece is arranged is short, the illuminance distribution of the surface to be illuminated is small even if there is little light with a small emission angle close to 0 °. The converging diameter of the optical fiber of the guide F is
For example, since it has a size of φ5 mm or φ3.5 mm, the illuminance at the center is high, and the peripheral portion has a lower mountain shape.

However, when the distance d between the emission end Fou of the light guide F and the surface to be illuminated becomes large, the illuminance of the illuminated area on the illuminated surface becomes lower at the central portion than at the peripheral portion,
A phenomenon called "hollow" occurs. FIG. 2 shows the relationship between the distance d between the emission end Fou of the light guide F and the irradiated surface and the “hollow hole” when the converging diameter of the optical fiber is φ3.5 mm. "Punching" phenomenon becomes remarkable. In addition, the distance d between the emission end Fou of the light guide F and the irradiation surface on which the work is arranged is often set to 20 mm or more due to the size and shape of the work, the clearance between the work loading and unloading mechanism, and the like. .

In order to shorten the light processing time, it is necessary to perform processing with high illuminance. However, if a small work such as a pickup lens for an optical disk is arranged at the center of the irradiation area when the distance between the emission end Fou and the irradiation surface on which the work is arranged is long, the work may be lost due to the "hollow-out" phenomenon. The illuminance of the irradiated light decreases, and the processing time increases. For this reason, the workpiece is shifted from the center of the irradiation area,
Irradiation is performed by arranging in the periphery of the irradiation area with high illuminance.
However, when different types of workpieces are subjected to light processing, or when the distance d between the emission end Fou of the light guide F and the workpiece surface on which the workpiece is arranged is changed, the illuminance distribution of the workpiece surface is measured each time. Therefore, it is necessary to find a place where the illuminance is the highest, and to set appropriately so that the work comes to that position. In addition, the region with high illuminance is the peripheral portion of the irradiation region, and the range is narrow. Therefore, it is necessary to accurately adjust the work position, and it takes time and effort to change the setup.

[0008]

In order to solve this "hollow-out" phenomenon, light emitted from the light-emitting end of the light guide is condensed on a surface to be irradiated by a projection optical system and arranged on the surface to be irradiated. It is conceivable that the irradiated work is irradiated. in this case,
Since the illuminance distribution at the light-emitting end of the light guide is projected onto the illuminated surface by the projection optical system, it is possible to efficiently irradiate the area requiring illumination on the illuminated surface, The phenomenon can be eliminated.

Japanese Patent Application Laid-Open No. 64-75067 discloses the use of a lens unit combining a plurality of lenses as the projection optical system. FIG. 3 shows the first
Lens unit L including lens L1 and second lens L2
An example of U is shown, in which a lens unit LU is attached to a light guide emission end to constitute a light irradiation unit. FIG.
, The light emitted from the emission end Fou of the light guide F has a certain spread according to the numerical aperture NA of the optical fiber forming the light guide F. For example, in the case of an optical fiber made of quartz glass, the numerical aperture NA is about 0.22, and the divergence angle in the air is about 12.7 °.

Here, the lens L of the lens unit LU
When 1 and L2 are brought closer to the emission end Fou of the light guide F, the magnification projected on the irradiated surface by the lens unit LU increases. In other words, the projection area on the irradiation surface increases, so that the illuminance of the entire irradiation area decreases. Therefore, in order to irradiate a narrow area with high illuminance, it is necessary to separate the lenses L1 and L2 of the lens unit LU from the emission end Fou of the light guide F by a predetermined distance. In order to effectively use the light emitted from the emission end Fou of the light guide F, most of the light spread at a divergence angle of about 12.7 ° has to be collected by a lens. As shown in FIG. 3, it is necessary to increase the lens diameter of the lens unit LU. For this reason,
The diameter of the lens unit including the holder H that holds the lens is considerably larger than the diameter of the light guide F, and the shape of the light emitting portion is increased. When the distance between the lens and the surface to be irradiated is increased, the distance from the output end Fou of the light guide F to the lens needs to be increased. The shape of the part becomes large.

In an actual light irradiation process, when a jig for fixing a work surrounds the periphery of the work, or when a part to be irradiated with light is positioned inside another part mounted on a substrate. In any case, if the shape of the light emitting portion is large, the light emitting portion cannot be illuminated sufficiently close to a portion of the workpiece to be irradiated with light, and a desired irradiance cannot be obtained. There is a problem that cannot be obtained.

Therefore, the present invention makes it possible to irradiate light with high irradiance by bringing the light emitting portion close to the work without increasing the diameter of the light emitting portion. It is an object of the present invention to provide a light irradiation device capable of efficiently irradiating light without causing “missing” of light applied to a surface to be irradiated even when the light irradiation device is away from the object.

[0013]

In order to achieve the above object, according to the first aspect of the present invention, light emitted from a discharge lamp is condensed by a mirror, and the condensed light is focused on an optical axis of the mirror. A light irradiating device, which irradiates the light incident on the incident end of the arranged light guide and converges the light emitted from the exit end of the light guide onto the surface to be irradiated by the projection optical system and irradiates the work arranged on the surface to be irradiated with the light, The optical system includes a rod lens having a spherical surface having the same radius of curvature at both ends, an entrance end disposed close to the exit end of the light guide, and a plano-convex or a convex arrangement disposed close to the exit end of the rod lens. It consists of a biconvex lens.
According to a second aspect of the present invention, the projection optical system includes a rod lens having a spherical end at both ends, the entrance end of which is disposed close to the exit end of the light guide, and the curvature of the spherical surface at the exit end of the rod lens. The radius is made smaller than the radius of curvature of the spherical surface at the entrance end. Further, the invention of claim 3 uses a light irradiation device having the projection optical system configured as described above to cure the ultraviolet-curable adhesive.

[0014]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 4 is a sectional view of an embodiment of the light emitting section according to the first aspect of the present invention. That is, the light source portion of the light irradiation device of the present invention is as shown in FIG. 1, and the distal end of the light guide F in FIG. 1 has the structure shown in FIG. In FIG. 4, a light guide F is formed by bundling a large number of optical fibers made of quartz glass in such a manner that the positions of the optical fibers at the input end Fin and the output end Fou are random. The side surface of the emission end Fou of the light guide F is covered with a joint FJ which is a cylindrical metal member, and a cylindrical holder H is joined to the joint FJ. And in the holder H,
A quartz glass rod lens 40 serving as a projection optical system
And a plano-convex lens 50 are held. Here, the outer diameters of the rod lens 40 and the plano-convex lens 50 are almost equal to or slightly larger than the converging diameter of the optical fiber. A specific example of the convergent diameter of the optical fiber is, for example, 3.5 mm, and the outer diameter of the joint FJ is 9 mm. The outer diameters of the rod lens 40 and the plano-convex lens 50 are equal to or slightly larger than φ3.5 mm. Therefore, since the projection optical system can be provided without making the outer diameter of the holder H larger than the outer diameter of the joint FJ, the outer diameter of the light emitting portion does not increase.

Both ends of the rod lens 40 are spherical, one end is an entrance surface for receiving light from the light guide F, and the other end is an exit surface for emitting the incident light. The entrance surface of the rod lens 40 is connected to the exit end Fou of the light guide F.
It is provided close to. That is, the entrance surface of the rod lens 40 is in contact with the exit end Fou of the light guide F or is held at a short interval of 1 mm or less. The radius of curvature R1 of the entrance surface of the rod lens 40 and the radius of curvature R2 of the exit surface
Is equal to The radius of curvature of the plano-convex lens 50 provided on the exit surface side of the rod lens 40 is R3. This radius of curvature R3, the radius of curvature R1 (= R2) of the rod lens 40, and the radius of curvature of the rod lens 40 in the optical axis direction. The length is designed according to the distance d to the surface to be irradiated on which the light emitted from the plano-convex lens 50 is collected. Note that the plano-convex lens 50 may be a biconvex lens.

FIG. 5 shows an embodiment of the light emitting portion according to the second aspect of the present invention. In the holder H, only the rod lens 40 whose outer diameter is almost equal to or slightly larger than the converging diameter of the optical fiber is held. ing. Both ends of the rod lens 40 are spherical as in the case of the first embodiment. However, by making the radius of curvature R2 of the exit surface smaller than the radius of curvature R1 of the entrance surface, a convex lens is formed on the exit side of the rod lens 40. Can be dispensed with. And the radius of curvature R1
The length of R2 and the length of the rod lens 40 in the optical axis direction are designed in accordance with the distance d to the irradiated surface on which the light emitted from the rod lens 40 is collected.

When the discharge lamp 10 shown in FIG. 1 is turned on and the shutter St is opened, the light condensed by the mirror 20 is incident on the incident end Fin of the light guide F, and is emitted from the output end Fou of the light guide F. In the case of the first aspect of the invention, as shown in FIG. 6, the light emitted from the optical fiber substantially at the center of the emission end Fou of the light guide F has a maximum emission angle of 12.7 ° (fiber). (Approximately 0.22 of NA), the light is refracted on the incident surface of the rod lens 40 and reaches the exit surface of the rod lens 40 while spreading at an angle of about 8.6 °. Then, the light exits from the exit surface of the rod lens 40 as light substantially parallel to the optical axis. on the other hand,
The light emitted from the optical fiber around the emission end Fou of the light guide F is refracted in the optical axis direction of the light guide F and enters the rod lens 40 because the incidence surface of the rod lens 40 has a spherical shape. Reaches the exit surface of the rod lens 40 while spreading at an angle of about 8.6 °.
Then, the light exits from the central portion of the light guide F on the exit surface of the rod lens 40 and overlaps with the light axis by 12.7.
The light exits from the exit surface of the rod lens 40 at an angle close to ゜. The spread angle θ ′ (about 8.6 °) in the rod lens 40 is determined by the refractive index n ′ (= 1.47) of quartz glass, which is the material of the rod lens 40, and the refractive index n (=
1) From the spread angle θ in air (12.7 °), it can be obtained based on Snell's law (n sin θ = n′sin θ ′).

In order to use the light most efficiently, the light incident on the rod lens 40 must spread to the exit surface of the rod lens 40 without hitting the outer peripheral surface of the rod lens 40 as shown in FIG. Is desirable. Therefore, the length of the rod lens 40 is preferably about 12 mm or slightly shorter than 12 mm because the material is quartz glass and the divergence angle is about 8.6 ° when the diameter is 3.5 mm. .

The light emitted from the exit surface of the rod lens 40 enters the plano-convex lens 50, and the light emitted from the plano-convex lens 50 is refracted based on the radius of curvature R3 of the plano-convex lens 50, and the light at the set position is obtained. Focus on the irradiation surface. here,
The distance d from the plano-convex lens 50 to the irradiated surface corresponds to the focal length of the plano-convex lens 50. That is, the rod lens 4
0 and the plano-convex lens 50 are positioned at the exit end Fou of the light guide F.
Illuminance distribution on the surface to be irradiated. Further, the illuminance distribution at the output end Fou of the light guide F is made uniform by the effect of the random arrangement of the optical fibers. Therefore, due to the function of the rod lens 40, even when the distance d from the emission unit to the surface to be irradiated is increased, “hollowness” does not occur in the illuminance distribution of the irradiation area on the surface to be irradiated.

FIG. 8 shows the above-described embodiment in which the projection optical system including the rod lens 40 and the plano-convex lens 50 is provided at the emission end Fou of the light guide F, and no projection optical system is provided at the emission end Fou of the light guide F. 2 shows an irradiance distribution curve of the conventional example shown in FIG. 1. The distance d from the plano-convex lens 50 or the emission end Fou of the light guide F to the surface to be irradiated is 1
The irradiance distribution curves at 5 mm and 20 mm were obtained, and the rod lens 40 and the plano-convex lens 50 were designed with the above distance d = 15 mm. The convergent diameter of the optical fiber is 3.5 mm.

As can be seen from FIG. 8, in the present embodiment, d =
In both cases of 15 mm and d = 20 mm, the “hollow-out” phenomenon was not recognized. In this embodiment, since light is condensed on the surface to be irradiated with d = 15 mm, the illuminance at the center of the irradiation area is much larger than in the conventional example, and a sharp distribution curve is obtained. On the other hand, in the conventional example, the illuminance at the center of the irradiation area is not only lower than that of the present embodiment, but also d = 20 m.
In the case of m, a "hollow-out" phenomenon was observed.

FIG. 7 shows an example of an optical path diagram according to the second embodiment in which the plano-convex lens 50 is not used.
Until the light incident on the light source reaches the emission surface, it is the same as FIG. 6 showing the optical path diagram of the first aspect of the present invention. However, the radius of curvature R2 of the exit surface of the rod lens 40 is equal to the radius of curvature R of the entrance surface.
Since it is smaller than 1, the light is refracted more than at the time of incidence, exits from the rod lens 40, and is condensed on the light irradiation surface at a set position. That is, since the rod lens 40 functions as a projection lens for projecting the illuminance distribution of the emission end Fou of the light guide F onto the surface to be illuminated, the same effect as using the plano-convex lens 50 is obtained. There is no "void" in the illuminance distribution of the area. And the plano-convex lens 5
Since 0 is not used, the number of parts can be reduced, and light loss due to reflection and absorption is reduced, so that illuminance is increased.

[0023]

As described above, according to the present invention, light emitted from a light guide is condensed on a surface to be irradiated by a rod lens or a projection optical system including a rod lens and a plano-convex or biconvex lens. Even when the distance to the irradiation surface is large, the "hollowness" phenomenon does not occur in the illuminance distribution, and the irradiance at the center of the irradiation area can be increased. Further, conventionally, the air layer between the light guide and the lens and between the lens and the lens occupy a large proportion, and the lens diameter is increased accordingly, but the air layer is replaced with a rod lens having a large refractive index. Thus, the diameter of the rod lens and the plano-convex or biconvex lens can be made substantially equal to the diameter of the light guide. Therefore, despite the provision of the projection optical system at the exit end of the light guide, the diameter of the light exit section does not increase. Therefore, even when the clearance between the work to be irradiated and the loading mechanism is small, the light emitting portion can be made to approach the work. In addition, even when the distance from the emission unit to the workpiece increases, light without “holes” can be emitted. Therefore, regardless of the length of the distance from the emission end to the surface to be irradiated, it is possible to easily adjust the irradiation conditions, and to cope with the irradiation conditions freely even if the material or type of the work changes. .

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a light irradiation device.

FIG. 2 is an explanatory diagram of “hollow” in the illuminance distribution.

FIG. 3 is an explanatory view of a conventional example of a light emitting unit.

FIG. 4 is a sectional view of a light emitting portion according to the first embodiment of the present invention.

FIG. 5 is a sectional view of a light emitting portion according to the second aspect of the present invention.

FIG. 6 is an optical path diagram according to the first aspect of the present invention.

FIG. 7 is an optical path diagram according to the second aspect of the present invention.

FIG. 8 is an irradiance distribution curve diagram.

[Explanation of symbols]

 Reference Signs List 10 discharge lamp 11 cathode 12 anode 20 mirror 30 holding member 40 rod lens 50 plano-convex lens F light guide Fin light guide incident end Fou light guide exit end FJ joint H holder St shutter

Claims (3)

[Claims] 1. A light radiated from a discharge lamp is condensed by a mirror, and the condensed light is incident on an incident end of a light guide disposed on an optical axis of the mirror and is emitted from an exit end of the light guide. The light is condensed on the surface to be irradiated by the projection optical system,
In a light irradiation device that irradiates an object to be illuminated disposed on an illuminated surface, the projection optical system has a spherical surface having the same radius of curvature at both ends,
A light irradiating device comprising: a rod lens having an incident end close to an exit end of the light guide; and a plano-convex or biconvex lens arranged close to the exit end of the rod lens. 2. A light emitted from a discharge lamp is condensed by a mirror, and the condensed light is incident on an incident end of a light guide disposed on an optical axis of the mirror and is emitted from an exit end of the light guide. The light is condensed on the surface to be irradiated by the projection optical system,
In a light irradiation device that irradiates an object to be illuminated disposed on a surface to be illuminated, the projection optical system includes a rod lens having a spherical end at both ends, the incident end of which is arranged close to the emission end of the light guide. A light irradiation device, wherein the radius of curvature of the spherical surface at the exit end of the rod lens is smaller than the radius of curvature of the spherical surface at the entrance end. 3. The light irradiation apparatus according to claim 1, wherein the light is irradiated to the object to which the ultraviolet curing adhesive is applied.