JP2002324404A - Fiber lighting equipment - Google Patents

Abstract

(57) [PROBLEMS] To provide a fiber illuminating device in which the amount of illumination applied to a surface to be illuminated via a light guide does not substantially change even when a light source unit is replaced. SOLUTION: A light source unit (1) for supplying illumination light condensed at a predetermined position, and a light guide (4) having an incident end positioned near the predetermined position, and an output end of the light guide (1) are provided. A fiber illumination device for illuminating the object (5) with the light emitted from 4b). Light guide entrance end (4a)
And a diffusing element (3) for diffusing incident light from the light source unit with a substantially high transmittance to guide the incident light to the incident end of the light guide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber illuminating device, and more particularly to a illuminating device suitable for illuminating a CCD camera used for observing living things, minerals, and workpieces and inspecting products.

[0002]

2. Description of the Related Art When a product is inspected using a CCD camera, image information obtained through the CCD camera is analyzed.
Inspect products for good or bad based on changes in brightness. A so-called fiber illuminator is known as an illuminator for a CCD camera. In a fiber illuminator, for example, light from a halogen lamp is condensed by an elliptical mirror, made incident on an incident end of a light guide composed of a large number of optical fibers, and the object to be inspected (e.g. (Illuminated surface).

[0003]

However, in the conventional fiber illuminator, when the light source unit including the halogen lamp and the elliptical mirror is replaced, the light collection efficiency, the light distribution pattern (irradiation pattern), and the light collection point are changed. Etc. change.
As a result, the light intensity distribution at the entrance end face of the light guide changes, and the amount of light emitted from the exit end of the light guide, that is, the amount of illumination light applied to the irradiated surface changes. In this case, since the change in the amount of illumination light causes the above-described change in luminance,
There is an inconvenience that the reliability of quality judgment regarding the quality of the test object is impaired.

In a conventional fiber illuminating device, when a halogen lamp and an elliptical mirror are arranged along the optical axis of an incident end face of a light guide, a phenomenon that a central portion of an illuminated surface is darker than a peripheral portion (a so-called hollow portion). Phenomenon) occurs. For this reason, the halogen lamp is decentered from the optical axis of the incident end face of the light guide, and the optical axis of the elliptical mirror is inclined by a predetermined angle (for example, 10 degrees) with respect to the optical axis of the incident end face of the light guide. The apparent illuminance uniformity on the irradiated surface is ensured.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and provides a fiber illuminating apparatus in which the amount of illumination applied to an illuminated surface via a light guide does not substantially change even when a light source unit is replaced. The purpose is to provide. It is another object of the present invention to provide a fiber illuminating device capable of securing uniform illuminance on a surface to be illuminated even when a light source unit is arranged along an optical axis of an incident end face of a light guide.

[0006]

In order to solve the above-mentioned problems, according to the present invention, a light source unit for supplying illumination light condensed at a predetermined position, and an incident end positioned near the predetermined position are provided. A fiber illuminator that includes a light guide and illuminates an object with light emitted from an emission end of the light guide, wherein the fiber illumination device is disposed close to an incidence end of the light guide and substantially reduces incident light from the light source unit. A fiber illuminating device comprising a diffusing element for diffusing at a high transmittance and guiding the light to an entrance end of the light guide.

According to a preferred aspect of the present invention, the diffusion element has a microlens array composed of a large number of microlenses arranged vertically and horizontally and densely. Further, it is preferable that the light source unit is disposed along an optical axis of an incident end face of the light guide. Further, the light guide has one input end and two output ends, and controls an output of the light source unit based on output light from one of the two output ends. It is preferable to have a control unit.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A fiber illuminating apparatus according to a typical embodiment of the present invention has, for example, a halogen lamp and an elliptical mirror as a light source unit for supplying illumination light focused on a predetermined position. Therefore, the illumination light from the halogen lamp is condensed via the elliptical mirror, and is incident on the light guide whose entrance end is positioned near the position of the condensing point. The light that has propagated inside the light guide is emitted from the emission end, and illuminates the test object.

According to the present invention, in addition to the above-described basic structure, a diffusing element for diffusing incident light from the light source unit with a substantially high transmittance and leading the light to the incident end of the light guide is provided. It is arranged close to the entrance end.
In this case, as a diffusion element, a microlens array including a large number of minute lenses arranged vertically and horizontally and densely,
A Fresnel optical element (Fresnel lens element) or the like can be used. Since the basic structure of a microlens array or a Fresnel optical element is a lens, light transmittance is very high, and efficient diffused light can be obtained.

As described above, according to the present invention, the illumination light from the light source unit is diffused with a substantially high transmittance through the diffusion element, and is then guided to the light guide entrance end.
Therefore, even if there are variations in characteristics such as the light-collecting efficiency, light distribution pattern (irradiation pattern), and light-converging point of each light source unit, the diffusion element absorbs the influence of the characteristic variations due to the diffusion action, and the light guide. The change in the light intensity distribution at the incident end face of the light emitting device is satisfactorily suppressed. As a result, it is possible to realize a fiber illuminating device in which the illumination light amount applied to the irradiated surface via the light guide does not substantially change even when the light source unit is replaced.

Therefore, when the fiber illuminating device of the present invention is applied to product inspection using a CCD camera, the quality of the object to be inspected is not changed even if the light source unit is replaced without causing a luminance change based on a change in the amount of illumination light. Judgment reliability is not impaired. Further, in the present invention, since the occurrence of the hollow phenomenon can be avoided by the action of the diffusion element, a simple configuration in which the light source unit is arranged along the optical axis of the incident end face of the light guide can be realized. As a result, the degree of freedom in design in terms of the mechanism is significantly improved.

An embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a diagram schematically illustrating a configuration of a fiber illumination device according to an embodiment of the present invention. FIG.
FIG. 2 is a diagram schematically illustrating an internal configuration of a light source unit in FIG. 1. Referring to FIG. 1, the fiber illumination device of the present embodiment includes a light source unit 1 for supplying illumination light.

As shown in FIG. 2, the light source unit 1 comprises a halogen lamp 1a for supplying light having a wavelength of, for example, 400 nm to 1300 nm, and an elliptical mirror 1b having an elliptical reflecting surface rotationally symmetric with respect to the optical axis AX. I have. Here, the halogen lamp 1a is positioned at the first focal position of the elliptical mirror 1b. Therefore, halogen lamp 1
The illumination light emitted from a is set to be condensed at the second focal position P of the elliptical mirror 1b.

Referring again to FIG. 1, the halogen lamp 1
The illumination light emitted from a enters the IR cut filter 2. The IR cut filter 2 is, for example, 750
It has a characteristic of selectively transmitting light having a wavelength of nm or less. Therefore, the illumination light whose wavelength is selected via the IR cut filter 2 (for example, 400 nm to 750 n)
The light guide 4 has a wavelength of m) through a microlens array 3 arranged near the second focal point P of the elliptical mirror 1b. 4a.

FIG. 3 is a diagram for explaining the configuration and operation of the microlens array of FIG. The microlens array 3 is an optical element including a large number of microlenses arranged vertically and horizontally and densely. In general, a microlens array is formed by, for example, performing etching on a parallel flat glass plate to form a microlens group.
In FIG. 3, the number of microlenses constituting the microlens array 3 is much smaller than the actual number for clarity.

Referring to FIG. 3, when a parallel light beam enters the microlens array 3, the incident light beam is divided two-dimensionally by a large number of microlenses, and one microlens is located near the rear focal plane of each microlens. Two light spots are formed. Then, divergent light beams from a number of light spots formed near the rear focal plane of the microlens array 3 are incident on the incident end 4 a of the light guide 4.

In the case of the present embodiment, since the microlens array 3 is arranged near the converging point P, the incident light beam is not a parallel light beam. However, the microlens array 3 functions as a diffusing element for diffusing incident light from the light source unit 1 and guiding it to the incident end 4 a of the light guide 4. Further, the microlens array 3 is a condenser of microlenses and has a substantially high transmittance. In this way, the light incident on the light guide 4 via the microlens array 3 propagates through the inside thereof, is emitted from the emission end 4b, and illuminates the irradiated surface 5.

As described above, in the present embodiment, the microlens array 3 as a diffusing element for diffusing the incident light from the light source unit 1 with a substantially high transmittance and guiding the light to the incident end 4a of the light guide 4 Are arranged close to the incident end 4a of the light guide 4. As a result, the illumination light from the halogen lamp 1a is diffused through the microlens array 3 with a substantially high transmittance, and then guided to the incident end 4a of the light guide 4.

Therefore, even if there are variations in the light-collecting efficiency, light distribution pattern (irradiation pattern), light-converging point, and other characteristics of the individual light source units 1, the microlens array 3 is affected by the dispersion of the characteristics due to its diffusion action. And a change in the light intensity distribution on the incident end face 4a of the light guide 4 can be suppressed well. As a result, the light source unit 1
Can be realized, the fiber illuminating apparatus in which the illumination light amount applied to the irradiated surface 5 via the light guide 4 does not substantially change even when the light guide 4 is replaced.

Therefore, when the fiber illuminating apparatus according to the present embodiment is applied to product inspection using a CCD camera, even if the light source unit 1 is replaced, the quality of the object to be inspected does not change due to a change in the amount of illumination light. There is no loss in the reliability of the quality decision. Further, in the present embodiment, it is possible to avoid the occurrence of the hollow phenomenon due to the diffusion action of the microlens array 3. As a result, a simple configuration in which the light source unit 1 is arranged along the optical axis AX of the incident end face 4a of the light guide 4 can be realized, and the degree of freedom in design in terms of the mechanism is significantly improved.

In the above-described embodiment, an example is shown in which the halogen lamp 1a is used as the light source. However, the present invention is not limited to this. For example, a discharge lamp such as a xenon lamp light source or a metal halide light source may be used. it can.
Further, in the above-described embodiment, an example in which the microlens array 3 is used as the diffusing element is shown. However, the present invention is not limited to this. For example, a Fresnel optical element (Fresnel lens element) can be used.

When the output of the halogen lamp 1a deteriorates with time in the above-described embodiment, the amount of light emitted from the emission end 4b of the light guide 4, that is, the amount of illumination light applied to the irradiated surface 5 changes. In this case, since the change in the amount of illumination light causes the above-described change in luminance, the reliability of the quality judgment of the test object is impaired. Hereinafter, even if the output of the halogen lamp 1a deteriorates with time,
In the following, a description will be given of a modification in which a constant illumination light amount can be obtained.

FIG. 4 is a diagram schematically showing a configuration of a fiber illuminating device according to a modification of the present embodiment. In the modification of FIG. 4, the illumination light from the halogen lamp 1a is reflected by the elliptical mirror 1b, and then enters the light guide 4 via the IR cut filter 2 (not shown) and the microlens array 3. The light guide 4 has a form of a two-branch light guide having one incident end and two incident ends. That is, the light guide 4 includes a fiber bundle 4c for illumination and a fiber bundle 4d for monitoring.

The light guided through the illumination fiber bundle 4c illuminates the surface 5 to be illuminated. On the other hand, the light guided via the monitor optical fiber bundle 4d reaches the optical sensor 11.
The output signal of the optical sensor 11 is supplied to the comparator 12.
The comparator 12 compares an output signal from the optical sensor 11 with a command signal from the target light quantity setting device 13. Comparator 1
2 is supplied to the up / down counter 14. The up / down counter 14 counts the difference between the output signal from the optical sensor 11 and the command signal from the target light quantity setting device 13, and outputs a voltage control signal as binary data.

The output signal of the up / down counter 14 is
It is supplied to the D / A converter 15. The D / A converter 15 converts the binary data from the up / down counter 14 into an analog signal. The analog signal from the D / A converter 15, that is, the voltage control signal is supplied to a power supply unit 16 for applying a voltage to the halogen lamp 1a. Power supply unit 1
At 6, the voltage applied to the halogen lamp 1a is changed based on the voltage control signal from the D / A converter 15.

As described above, in the modification of FIG. 4, when the desired light amount is set in the target light amount setting device 13 by operating, for example, a volume or a numeric keypad, the light amount detected by the optical sensor 11 always coincides with the target light amount. The voltage applied to the halogen lamp 1a is feedback-controlled. As a result, even if the output of the halogen lamp 1a deteriorates with time,
The amount of light emitted from the emission end of the illumination fiber bundle 4c, that is, the amount of illumination applied to the irradiated surface 5 can be kept constant. For a more detailed configuration and operation of the modification of FIG. 4, for example, Japanese Patent Application Laid-Open No. 8-327826 can be referred to.

[0027]

As described above, according to the present invention, the illumination light from the light source unit is diffused with a substantially high transmittance through the diffusion element, and then guided to the light guide entrance end. Therefore, even if there are variations in characteristics such as the light-collecting efficiency, light distribution pattern (irradiation pattern), and light-converging point of each light source unit, the diffusion element absorbs the influence of the characteristic variations due to the diffusion action, and the light guide. The change in the light intensity distribution at the incident end face of the light emitting device is satisfactorily suppressed. As a result, it is possible to realize a fiber illuminating device in which the illumination light amount applied to the irradiated surface via the light guide does not substantially change even when the light source unit is replaced.

Therefore, when the fiber illuminating device of the present invention is applied to product inspection using a CCD camera, the quality of the object to be inspected is not changed even if the light source unit is replaced without causing a luminance change based on a change in the amount of illumination light. Judgment reliability is not impaired. Further, in the present invention, since the occurrence of the hollow phenomenon can be avoided by the action of the diffusion element, a simple configuration in which the light source unit is arranged along the optical axis of the incident end face of the light guide can be realized. As a result, the degree of freedom in design in terms of the mechanism is significantly improved.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a configuration of a fiber lighting device according to an embodiment of the present invention.

FIG. 2 is a diagram schematically showing an internal configuration of the light source unit of FIG.

FIG. 3 is a diagram illustrating the configuration and operation of the microlens array of FIG. 1;

FIG. 4 is a diagram schematically showing a configuration of a fiber illuminating device according to a modification of the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light source unit 1a Halogen lamp 1b Elliptic mirror 2 IR cut filter 3 Macro lens array 4 Light guide 4c Optical fiber bundle for illumination 4d Optical fiber bundle for monitoring 5 Surface to be illuminated 11 Optical sensor 12 Comparator 13 Target light quantity setting unit 14 Up / down Counter 15 D / A converter 16 Power supply unit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // F21Y 101: 00 F21S 1/00 F

Claims (4)

[Claims] 1. A light source unit for supplying illumination light condensed at a predetermined position, and a light guide having an incident end positioned near the predetermined position, and light emitted from an emission end of the light guide. In the fiber illuminating device for illuminating an object with, in order to guide the incident light from the light source unit to the incident end of the light guide by diffusing the incident light from the light source unit at a substantially high transmittance. A fiber illuminating device comprising: 2. The fiber illuminating apparatus according to claim 1, wherein the diffusing element has a microlens array including a large number of microlenses arranged vertically and horizontally and densely. 3. The fiber illuminator according to claim 1, wherein the light source unit is disposed along an optical axis of an incident end face of the light guide. 4. The light guide has one incident end and two
And a control unit for controlling an output of the light source unit based on light emitted from one of the two light-emitting ends. The fiber lighting device according to any one of claims 1 to 3.