JP2000266938A - Light irradiation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light irradiation device capable of heightening a condensing degre of light irradiated from the head of a light guide part. SOLUTION: A light guide part 4 is fixed on an emission function part 3 in the abutting state on a light source 5. The light guide part 4 is formed by, for example, a quartz glass rod, and in the periphery of the light guide part 4, an inclined face 4c is formed so that a sectional area becomes larger gradually from an outgoing side end face toward the back end side. The structure of an ultraviolet ray irradiation device 1 can be simplified in this way, to thereby manufacture the device 1 inexpensive and capable of miniaturizing. And besides, by forming the inclined face 4c from the back end side to the outgoing side end face on the periphery of the light guide part 4, light entering the light guide part 4 is condensed in the light guide part 4 and transferred to the head direction, and light having a high condensing degree is irradiated from the outgoing side end face.

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 comprising a light emitting function unit having a light source and a light guide unit for irradiating light from the light source from an end surface on an emission side.
In particular, the present invention relates to a light irradiation device that can increase the degree of condensing light and that can be reduced in size and inexpensive.

[0002]

2. Description of the Related Art For example, when joining certain members, an ultraviolet curing resin is applied to a joint surface of the members, and the resin is cured by irradiating the resin with ultraviolet rays by an ultraviolet irradiation device. The members may be joined together.

A light source and a reflector for reflecting light from the light source are provided inside the ultraviolet irradiation device. The reflector is, for example, an aluminum plate or the like having a reflective surface on the inner surface, and has a hemispherical shape or a parabolic or elliptical cross section.

[0004] When a processed material having an ultraviolet curable resin applied between members is supplied into the ultraviolet irradiation device, ultraviolet light emitted from a light source is reflected by the inner surface of the reflector, and the reflected ultraviolet light is emitted. However, the resin is irradiated to cure the resin, whereby the members are joined to each other.

[0005]

However, in the above-described ultraviolet irradiation apparatus, the concentration of the ultraviolet light reflected in the reflector is low, and the ultraviolet light is applied to a target object over a wide range. For this reason, for example, when it is desired to irradiate only a predetermined portion of an object with ultraviolet light, the above-described ultraviolet irradiation device cannot irradiate the ultraviolet ray intensively only to that portion.

Therefore, the ultraviolet light from the light source reflected in the reflector is focused using a condenser lens, and the focused ultraviolet light is incident from the rear end of the optical fiber using an optical fiber. By irradiating from the tip, it is considered that the degree of concentration of the irradiated ultraviolet light can be increased, and the ultraviolet light can be appropriately applied to a predetermined portion of the target object. However, this method has the following problems.

First, optical alignment between the optical fiber and the light-emitting side is required, such as adjustment of the distance between the incident end face of the optical fiber and the condenser lens. Is complicated. Second, the optical fiber has a structure in which a plurality of thin wires usually formed by a clad and a core are bundled, and the thickness of the optical fiber is uniformly formed from the incident side to the emission side. It is not possible to narrow the irradiation range of diffused light emitted from the exit side end face of the optical fiber,
It does not have a light-collecting degree that can irradiate a narrow spot intensively with ultraviolet rays.

Further, in the conventional ultraviolet irradiation apparatus, a large light source which requires a large amount of electric power so as to emit strong light from the light source has been used. Therefore, the shape of the reflector for reflecting the light from the light source also needs to be increased according to the size of the light source,
Conventional ultraviolet irradiation devices have become large and expensive.

However, for the purpose of using the ultraviolet irradiation device, it is not necessary to irradiate such a strong ultraviolet light.
For example, when it is desired to irradiate only a predetermined portion of an object with ultraviolet rays, a conventional large-sized ultraviolet irradiation apparatus is inconvenient and requires a simpler ultraviolet irradiation apparatus.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and in particular, to provide a light irradiation device capable of increasing the degree of condensing of light irradiated from the tip of a light guide portion as compared with the conventional one. Is the first object. The present invention also provides
It is a second object of the present invention to provide a light irradiation device which is inexpensive and can be made small enough to be held by hand.

[0011]

According to the present invention, there is provided a light irradiating device having a light emitting function unit having a light source and a light guide unit for guiding light from the light source, wherein the light guide unit is provided with a light from the light source. Is formed so that the area of the light exit side end face is smaller than the area of the incident side end face where the light enters.

By making the area of the exit side end face of the light guide section smaller than the area of the incident side end face, light from the light source incident from the entrance side end face of the light guide section becomes smaller in the front end direction where the cross-sectional area becomes smaller. The light is transmitted while being condensed toward, and it is possible to irradiate light having a high degree of condensing from the exit side end face of the light guide portion. In the present invention, the light emitting function section may have any structure, and, for example, an existing optical fiber is interposed between the light source and the light guide section, and light from the light source is transmitted through the optical fiber. The light may be emitted from the end face on the emission side of the light guide section.

As a specific shape of the light guide portion in the present invention, it is preferable that the light guide portion has such a shape that a cross-sectional area becomes gradually smaller toward the emission side end surface at least in the vicinity of the emission side end surface. Thereby, the light incident from the incident side end face of the light guide section is transmitted while being condensed in the tip direction where the cross-sectional area gradually decreases, and the light condensing degree is high from the exit side end face of the light guide section. Light will be irradiated.

Particularly, in the present invention, it is preferable that the light guide portion is formed of a light-transmitting rod such as a quartz glass rod. The translucent rod may be an acrylic resin or the like. The light incident on the rod material such as the quartz glass is almost totally reflected, propagates through the rod material, and has a high light-condensing degree and is appropriate from the emission-side end face of the light guide portion having the smallest area. Light of high intensity is emitted. In addition, since the quartz glass rod can be purchased at a low cost, it is possible to manufacture a light irradiating device having a high light condensing degree at a low cost.

Further, although diffused light is emitted from the exit side end face of the light guide section, since the exit end face has a small area,
By bringing the emission-side end face close to the processing object, the processing object can be irradiated with a minute spot. In addition, if the exit side end face of the light guide section such as a bar is formed in a lens shape, the diameter of the light spot given to the processing section can be further reduced.

According to another aspect of the present invention, there is provided a light irradiating apparatus including a light emitting function unit having a light source therein, and a light guide unit for receiving light from the light source and irradiating the light from an end surface on an emission side. Wherein the light guide section is attached to the light emitting function section with its incident side end face in contact with the light source.

According to the present invention, unlike the related art, the light guide section is directly in contact with the light source without using a condenser lens or a condenser reflector in the light emitting function section. The light emitting function unit includes, for example, a reflecting mirror member made of aluminum and a light source provided inside the reflecting mirror member, and a part of light from the light source is a light guide unit. Light that is incident from the incident side end face as it is and that is reflected by the inner surface of the reflecting mirror member is incident from the rear end side of the light guide section. The incident light is transmitted through the inside of the light guide section, and is emitted from the exit side end face of the light guide section.

The light irradiating device according to the present invention has a simplified structure as compared with the prior art in which the light guide portion is directly in contact with the light source. By using a light source with a small light-emitting part (light-emitting tube) used in such as, the size of the light irradiation device can be reduced to a size that can be held by human hands,
And it can be manufactured at low cost.

The light irradiating device of the present invention does not require so intense light, and can be used particularly effectively, for example, when it is desired to irradiate light only to a certain predetermined portion of an object. As described above, since the light irradiation device can be used by being held by a person, it is easy to use and the work efficiency can be improved.

Further, in the present invention, it is preferable that the light guide section has a shape having a cross-sectional area gradually reduced toward at least the exit side end face at least in the vicinity of the exit side end face, and more preferably the light guide section. Is formed of a translucent rod. This makes it possible to increase the degree of concentration of light emitted from the tip of the light guide.

Further, in the present invention, it is preferable that the light guide portion is formed of a translucent rod such as quartz glass. By using a quartz glass rod as the light guide portion, the light incident on the rod material such as the quartz glass is almost totally reflected, propagates through the rod material, and has an appropriate intensity from the tip of the rod material. Is irradiated. Alternatively, the light-emitting end face may be formed into a lens shape to condense light. In addition, by using the rod material such as the quartz glass as the light guide portion, the light irradiation device can be further reduced in size, and the usability is good.

For example, if the light emitting function section is housed in a protective member, and the light guide section is fixed so as to protrude from the protective member, the light guide section can be held and used by hand. The light irradiation device according to the present invention can be applied to various light irradiation devices using visible light, infrared light, ultraviolet light, or the like.

[0023]

FIG. 1 is a partial perspective view showing an external shape of a light irradiation device according to the present invention. FIG. 2 is a sectional view of the light irradiation device shown in FIG. It is sectional drawing seen. The light irradiation device 1 shown in FIG. 1 is, for example, an ultraviolet irradiation device. As the application, the ultraviolet irradiation device 1 irradiates an ultraviolet ray toward an ultraviolet curable resin applied between members, thereby forming the resin. Is used for curing and bonding between members.

As shown in FIG. 1, the ultraviolet irradiation device 1
A light emitting function unit 3 having a light source therein;
And a light guide section 4 attached to the light guide section. As shown in FIG. 2, a light source 5
The light source 5 is, for example, a high-pressure mercury bulb. The bulb 6 constituting the high-pressure mercury bulb is formed of, for example, quartz glass, and the bulb 6 is filled with mercury. In the bulb 6, two electrodes 7, 8 and one auxiliary electrode 9 are provided. First, after a discharge occurs between the electrode 7 and the auxiliary electrode 9, the electrodes 7, 8
Discharge occurs between the two, and the mercury sealed in the bulb 6 is excited to emit ultraviolet light having a wavelength of 365 nm.

As shown in FIG. 2, the light source 5 is housed in a glass tube 10 made of, for example, quartz glass, and the glass tube 10 is made of a reflecting mirror member 11 made of, for example, aluminum having a high reflectance. It is housed inside. Light source 5
Is housed in the glass tube 10 so that the light emitted from the light source 5 is not excessively emitted to the outside of the glass tube 10 and the reflection mirror member 11 and the like are prevented from becoming excessively hot. I have.

The reflecting mirror member 11 reflects the ultraviolet light emitted from the light source 5 on its inner surface, and
The reflecting mirror member 11 is preferably provided with a shape capable of appropriately focusing ultraviolet light emitted from the light source 5 in the direction of the light guide portion 4. .

For example, when the reflecting mirror member 11 is formed in a cylindrical shape having a circular cross section and the light source 5 is arranged at the center of the circle, light radiated from the light source 5 to the periphery is reflected on the inner surface of the reflecting mirror member 11. Then, the light returns to the light source 5 and the light given to the incident end face of the light guide 4 can be effectively collected. Further, the reflecting mirror member 11 may be formed of a material having a high reflectance other than aluminum.
An aluminum film may be vapor-deposited on the inner surface of the first electrode.

Further, as shown in FIG. 2, the reflecting mirror member 11 is housed in a protective member 12, and as shown in FIG.
2 is visible. The protection member 12
May be formed of any material as long as it is formed of a material having a high heat dissipation property, and examples thereof include stainless steel and aluminum.

The protective member 12 may have any shape. In the present invention, for example, as shown in FIGS. 1 and 2, the protective member 12 is formed in a cylindrical shape.
As shown in FIGS. 1 and 2, lid members 15 are provided on both sides of the protection member 12. This lid material 1
5 and 15 have, for example, a quadrangular cross section.

The light guide section 4 receives ultraviolet rays from the light source 5 on the rear end side and irradiates the ultraviolet rays from the exit side end face. In the present invention, as shown in FIG. The incident side end face 4 a of the unit 4 is attached to the light emitting function unit 3 in a state of directly contacting the light source 5.

Conventionally, a condenser lens for focusing ultraviolet rays from the light source 5 is used, and the ultraviolet rays focused by the condenser lens are incident on the light guide portion. In the invention, the light guide unit 4 is brought into contact with the light source 5 without using the condenser lens, and the ultraviolet light emitted from the light source 5 is incident on the light guide unit 4.

Therefore, according to the present invention, it is not necessary to perform a very complicated operation such as the positioning of the condensing lens and the light guide portion as in the related art, and the manufacturing efficiency of the ultraviolet irradiation apparatus 1 can be improved. It is.

A part of the ultraviolet light emitted from the light source 5 is incident on the incident side end face 4 of the light guide portion 4 which comes into contact with the light source 5.
a, and the ultraviolet light reflected directly on the inner surface of the reflecting mirror member 11 is also incident on the incident side end face 4 of the light guide section 4.
a.

In the present invention, as shown in FIGS. 1 and 2, the area of the exit side end face 4b of the light guide section 4 is formed to be smaller than the area of the incident side end face 4a of the light guide section 4. preferable. Thereby, the ultraviolet rays incident from the incident side end face 4a of the light guide section 4 are transmitted while being condensed toward the tip end of the light guide section 4 and irradiated from the exit side end face 4b of the light guide section 4. It is possible to increase the degree of concentration of ultraviolet light.

As described above, the exit side end face 4b of the light guide section 4
As a method for reducing the area of the light guide portion 4a as compared with the area of the incident side end surface 4a, as shown in FIG. 1 or 2, at least near the front end of the light guide portion 4 from the output side end surface 4b to the rear end direction. It is preferable to form an inclined surface (tapered surface) 4c having a larger sectional area. The inclined surface 4c is formed by, for example, tapering by grinding or the like.

The inclined surface 4c may be formed not only near the front end of the light guide portion 4 but also toward the rear end, or the inclined surface 4c may extend from the exit side end surface 4b to the entrance side end surface 4a. May be formed.

In the present invention, it is preferable that the light guide section 4 is formed of, for example, a quartz glass rod. This is because the quartz glass rod can be purchased at a low cost, and the inclined surface 4c can be easily processed as described above.

In the light guide portion 4 formed of a quartz glass rod, when the ultraviolet light emitted from the light source 5 is incident from the rear end side, the ultraviolet light is totally reflected inside the light guide portion 4 toward the front end. Ultraviolet rays are radiated as diffused light from the exit side end face 4b of the light guide section 4 while being transmitted. In addition,
If the emission side end face 4b is formed in a convex lens shape, light emitted from the emission side end face 4b can be collected.

However, a part of the ultraviolet light is emitted from the light guide section 4.
When the light is transmitted from the rear end side to the front end side, it leaks from the periphery of the light guide portion 4, and therefore, a metal film is formed on the outer peripheral surface of the light guide portion 4 except the incident side end surface 4 a and the output side end surface 4 b. A reflective film such as the one described above may be deposited to increase the light reflectance on the outer peripheral surface of the light guide unit 4.

When a reflection film is formed on the outer peripheral surface of the light guide portion 4 protruding from the light emitting function portion 3 as described above, ultraviolet rays do not leak from the periphery of the light guide portion 4, and Ultraviolet rays from the light source 5 incident from the rear end side of the part 4 are transmitted while being condensed in the direction of the front end where the cross-sectional area is reduced, and from the exit side end face 4 b of the light guide part 4, High UV light is applied.

Further, as shown in FIG. 1 or 2, it is preferable to provide a protective cylinder 14 also around the light guide section 4 at a portion protruding from the light emitting function section 3. The provision of the protective tube 14 can prevent the light guide portion 4 from being damaged.
The protection cylinder 14 may be formed of a material having a high reflectance such as aluminum, or a light reflection film may be formed on the inner surface to prevent light from leaking from the peripheral surface of the light guide unit 4.

This protective tube 14 may be formed integrally with the reflecting mirror member 11 provided inside the light emitting function part 3, or may be formed integrally with the protective member 12. May be. Further, the protection cylinder 14 provided around the light guide section 4 may be provided separately from the reflection mirror member 11 and the protection member 12.

As shown in FIG. 2, the light guide 4 is
The protection cylinder 14 is fixed to the protection cylinder 14 by a locking member 13 such as a screw. Also, in FIG. 1 or 2, the protection tube 14 provided around the light guide unit 4 is provided only up to the vicinity of the middle of the light guide unit 4. It may be formed so as to extend to the vicinity of the tip of the portion 4.

As described above, the light source 5 provided inside the light emitting function unit 3 is a high-pressure mercury bulb, and it is known that the temperature of the light source 5 becomes extremely high during use. In the present invention, a material having good heat dissipation properties is selected for the reflecting mirror member 11 and the protection member 12, and the light emitting function part 3 is provided.
It has a role to mitigate the sudden rise in temperature inside.

Further, according to the present invention, as shown in FIG. 2, a cooling port 16 is formed in the reflecting mirror member 11 and the protection member 12 constituting the light emitting function section 3, and the cool air flowing through the cooling port 16 is The light emitting function unit 3 passes through the inside of the light emitting function unit 3.
Flow from the holes 17 provided in the lid members 15 on both sides of the light-emitting function part 3, and it is possible to more effectively mitigate the rapid temperature rise in the light emitting function part 3. .

However, the cool air flowing from the cooling port 16 must not directly hit the light source 5. This is because, when the cool light hits the light source 5, the mercury pressure changes due to a change in the temperature inside the light source 5, and the output efficiency of the ultraviolet light emitted from the light source 5 also changes.

As described above, the ultraviolet irradiation apparatus 1 according to the present invention has the light guide section 4 attached to the light emitting function section 3 in a state in which the light guide section 4 is in contact with the light source 5. The ultraviolet irradiation device 1 can be manufactured at low cost, and the size can be reduced to a level that can be held by a worker by hand.
Light source 5 provided in ultraviolet irradiation device 1 in the present invention
Is an existing light source used for lamps such as high-pressure mercury bulbs, and the intensity of the ultraviolet light emitted from these light sources is the same as the intensity of the ultraviolet light emitted from the light source provided in the conventional ultraviolet irradiation device. Weaker than
The ultraviolet irradiation device 1 according to the present invention does not require so strong light, and is effectively used, for example, when it is desired to irradiate light only to a certain predetermined portion of an object.

As described above, in the present invention, the size itself of the light source 5 can be reduced by using the existing light source 5, and in the present invention, the light guide portion 4 is connected to the light source 5
2 is attached to the light emitting function unit 3 to simplify the structure, so that the size of the light emitting function unit 3 can be made extremely small as compared with the conventional case. For example, the light emitting function unit 3 shown in FIG. Is about 100 mm, and the diameter φ1 of the light emitting function unit 3 (the diameter φ1 when the protection member 12 is formed in a cylindrical shape) is about 35 mm.

Further, in the present invention, for example, a quartz glass rod can be used as the light guide section 4. The light guide portion 4 formed of the quartz glass rod is, for example, as shown in FIG.
However, in the present invention, as shown in FIG. 1 or 2, the area of the output side end face 4 b of the light guide section 4 is changed to the incident side end face 4 a. By making the area smaller than the area, the ultraviolet rays can be transmitted while being condensed inside the light guide section 4, and the ultraviolet rays having a high degree of condensing can be irradiated from the exit side end face 4 b of the light guide section 4. For this reason, if the ultraviolet irradiation device 1 according to the present invention is used, it is possible to irradiate the ultraviolet rays intensively only at a predetermined position of the target object, for example.

Also, by using a rod-shaped one such as a quartz glass rod as the light guide part 4, the light emitting function part 3 is provided.
The length L1 of the light guide portion 4 protruding from the optical fiber can be made extremely short as compared with, for example, the case where an optical fiber is used as in the related art. Specifically, the length L1 is set to 1
It can be formed in about 50 mm.

As described above, according to the present invention, it is possible to reduce the size of the ultraviolet irradiating device 1 having the light emitting function unit 3 and the light guide unit 4 to the extent that it can be held by hand. The operator can hold the portion of the light guide portion 4 protruding from the hand 3 and work while pointing the emission side end face 4b of the light guide portion 4 to a predetermined portion of the target object. With the device 1, work efficiency can be improved.

The protection tube 14 provided around the light guide portion 4 and the protection member 1 which is the outer surface of the light emitting function portion 3
2 may be heated by the heat emitted from the light source 5 and may be difficult for a person to hold by hand. Therefore, it is necessary to further provide a heat insulating material as the exterior of the protective tube 14 and the light emitting function unit 3. preferable.

In the present invention, an existing optical fiber or the like may be used as the light guide section 4. At this time, the front end of the optical fiber is provided from the rear end side shown in FIG. It is preferable to attach, for example, a quartz glass rod having an inclined surface so that the cross-sectional area gradually decreases toward the end face. Thereby, it is possible to improve the degree of condensing the ultraviolet light emitted from the end face on the emission side of the light guide section 4.

In the present invention, the ultraviolet irradiation apparatus 1 has been described in the embodiment, but in the present invention, the ultraviolet irradiation apparatus 1
However, the present invention can be applied to a light irradiation device using visible light or infrared light.

[0055]

In the present invention, a light guide (formed from a quartz glass rod or the like) is directly attached to a light source (high-pressure mercury bulb) 5 shown in FIG. The strength (mW) was measured. The measurement was carried out using a sensor having a hole (sensor part) having a diameter of 1 mm in the center and examining the intensity of light irradiated into the hole.

First, as an experiment, the intensity of light emitted from the light source itself was examined and found to be 296 (mW). Next, the length from the exit side end face to the entrance side end face is 1800 m.
m and the thickness is φ5.5 from the front end to the rear end.
When the intensity of the light emitted from the exit side end face of the liquid fiber by contacting the liquid fiber uniform in mm with the light source was measured, it was 103 (mW). The light incident from the input end face of the liquid fiber is considerably attenuated before being transmitted to the output end face, and the intensity of the light emitted from the output end face is low because the convergence of the light emitted from the output end face is low. It is considered that the intensity is considerably lower than the light intensity (296 (mW)) of itself.

Next, a uniform quartz glass rod having a length of 150 mm from the exit side end face to the incident side end face and having a diameter of 7 mm from the front end to the rear end was brought into contact with the light source.
When the intensity of light emitted from the exit side end face of the quartz glass rod was examined, it was 147 (mW). Although the intensity of light emitted from the output end face can be increased as compared with the case where a liquid fiber is used, using a quartz glass rod of uniform thickness enables the light emitted from the output end face to be increased. It is considered that the degree of light collection is low, and thus the light intensity is considerably lower than the light intensity (296 (mW)) of the light source itself.

Finally, the length from the outgoing end face to the incoming end face is 150 mm, and the thickness at the incoming end face is φ
A quartz glass rod having an inclined surface extending from the exit side end face to the rear end side is brought into contact with the light source so that the thickness at the exit side end face is φ2 mm, and the exit side end face of the quartz glass rod is 7 mm. The intensity of the light emitted from
86 (mW). Compared to the intensity of the light emitted from the light source (296 (mW)), the intensity is only slightly attenuated, and it can be seen that light with good intensity can be obtained.

This is because, by gradually reducing the cross-sectional area from the rear end side of the quartz glass rod to the exit end face, light incident from the incident end face of the quartz glass rod is collected toward the tip end. It is considered that the light is transmitted while being transmitted, and the light having a high light-condensing degree is irradiated on the exit side end face of the quartz glass rod.

[0060]

According to the present invention described in detail above, the area of the exit side end face of the light guide section is made smaller than the area of the incident side end face, so that the light source incident from the entrance side end face of the light guide section is provided. Is transmitted while being condensed in the light guide portion toward the emission-side end face, and it is possible to irradiate light having a high degree of condensing from the emission-side end face.

Further, according to the present invention, a light irradiating device which is inexpensive and can be downsized as compared with a conventional light irradiating device is manufactured by adopting a structure in which the incident side end face of the light guide portion is mounted in contact with the light source. can do. Further, in this case, by forming the area of the exit side end face of the light guide section smaller than the area of the incident side end face, it is possible to increase the degree of condensing light emitted from the tip of the light guide section.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an external shape of a light irradiation device (ultraviolet irradiation device) according to a first embodiment of the present invention;

FIG. 2 is a partial cross-sectional view of the light irradiation device, taken along line 2-2 shown in FIG.

FIG. 3 is a plan view showing a shape of a light irradiation device (ultraviolet irradiation device) according to a second embodiment of the present invention;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light irradiation device (ultraviolet irradiation device) 3 Light emitting function part 4 Light guide part 4c Inclined surface 5 Light source 6 Bulb 7, 8 electrode 9 Auxiliary electrode 10 Glass tube 11 Reflecting mirror member 12 Protective member 14 Protective cylinder 15 Lid 16 Cooling port

Claims (8)

[Claims] 1. A light irradiation device having a light-emitting function section having a light source and a light guide section for guiding light from the light source, wherein the light guide section has an area of an incident-side end face on which light from the light source is incident. A light irradiation apparatus characterized in that the area of the end surface on the light emission side is formed smaller than that of the light emission side. 2. The light irradiation device according to claim 1, wherein the light guide has a shape in which a cross-sectional area is gradually reduced toward at least the emission side end surface at least in the vicinity of the emission side end surface. 3. The light irradiation device according to claim 1, wherein the light guide portion is formed of a translucent rod. 4. A light irradiation device comprising: a light-emitting function unit having a light source therein; and a light guide unit that receives light from the light source and irradiates the light from an end surface on an emission side. A light irradiation device, wherein the light-emitting device is attached to the light-emitting function section with its incident-side end face in contact with a light source. 5. The area of the light-emitting end face of the light guide section is:
The light irradiation device according to claim 4, wherein the light irradiation device is formed to be smaller than the area of the incident side end surface. 6. The light irradiation device according to claim 5, wherein the light guide has a shape in which a cross-sectional area gradually decreases toward at least the emission side end face at least in the vicinity of the emission side end face. 7. The light irradiation device according to claim 4, wherein the light guide portion is formed of a translucent rod. 8. The light irradiation device according to claim 4, wherein the light emitting function unit is housed in a protective member, and the light guide unit is fixed so as to protrude from the protective member.