JP2007101465A - Luminous energy monitor, and light source device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate an individual difference among light guide rods, to increase luminous energy of detection light output from the light guide rod to enhance detection precision, without measuring a leaked light quantity depending on an internal defect or a flaw, and to emit a uniform luminous energy distribution of light from the light guide rods. <P>SOLUTION: The light guide rod 7 comprising a polygonal pole of rod integrator is arranged to uniformize the light incident from one end side serving as a light incident end face 7in and to emit it from the other end side serving as a light emitting end face 7out, in an optical path from a light source 2 to an irradiated object, a light diffusion body 10 is provided to diffuse further the light scattered in an edge part 9 to be emitted to an outside, in an outer circumferential face of the edge part 9 of the light emitting end face 7out, and a photosensor 15 is provided to detect the luminous energy of the light diffused by the light diffusion body 10 as irradiation light. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a light amount monitor that detects an irradiation light amount of illumination light irradiated on an object to be irradiated from a light source and a light source device that performs light amount control using the light amount monitor, and more particularly to an image processing inspection device using a CCD camera or the like. Thus, it is suitable for use as a light source of an inspection apparatus that needs to maintain a constant amount of light irradiated to an inspection object.

  For example, in the flat panel display manufacturing process, conventionally, image processing inspection that detects defects such as scratches and paint defects by irradiating light on the glass plate or paint coating surface that is the inspection object and observing this with a CCD camera etc. The device is in use.

  At that time, as a condition required for the light source device, the amount of light to the inspection object (object to be irradiated) does not change at least during the inspection time, and the necessary amount of light according to the light receiving sensitivity performance level of the camera to be used. For example, it can be irradiated with light.

As light sources of light source devices for image processing inspection, halogen lamps, solid state light elements such as LEDs, discharge lamps such as mercury lamps and metal halide lamps are used. Among them, discharge lamps such as mercury lamps and metal halide lamps are Although it is slow in time, a high amount of light can be obtained, so it is optimal as this type of light source.
However, when these discharge lamps are lit for 1000 to 2000 hours, the amount of light irradiated to the inspection object gradually attenuates. Therefore, when using these lamps, the amount of light must be adjusted each time so that the brightness of the image does not change. Is required.

  Here, the cause of the decrease in the amount of light emitted is that the discharge location changes with the change in the lamp electrode, the light emission point deviates from the first focal point, etc. A change in the light quantity distribution pattern can be considered.

Therefore, the present applicant accurately detects whether there is a change in the amount of irradiation light due to a change in the light amount of the lamp or a change in the amount of light distribution due to a change in the light amount distribution pattern, and keeps the amount of irradiation light constant. Proposed light source device.
JP 2005-233927 A

According to this, when the light emitted from the lamp and collected by the reflecting mirror is incident on the light guide rod, countless internal defects formed in the light guide rod and fine scratches on the peripheral surface are formed. As a result, light is irregularly reflected, and a part of the light leaks from the peripheral surface.
And, when a light sensor is provided on the circumferential surface of the light guide rod to detect the amount of light leaked from the light guide rod and the amount of light irradiated to the irradiated object from the bundle fiber tip connected to the light exit port of the light guide rod, In addition to the change in the amount of light emitted due to the change in the amount of light emitted from the lamp itself, the change in the amount of light emitted due to the change in the light quantity distribution pattern could be detected fairly accurately.

However, since the amount of leakage depends on internal defects and scratches, the amount of leakage is significantly different for each light guide rod, which makes it difficult to adjust calibration at the time of shipment.
Also, the better the quality of the light guide rod with fewer internal defects and scratches, the lower the light leakage, so the detection accuracy is reduced. Depending on the light guide rod, the amount of irradiation light is not always detected accurately when the light distribution pattern changes. It turns out that there are cases where it is not possible.
Furthermore, since the light emitted from the conventional cylindrical light guide rod maintains the light quantity distribution of the incident light, when an illumination light having a uniform light quantity distribution is required, a separate optical system for uniformizing the light is provided. There is a problem that it must be provided.

  Therefore, the present invention eliminates individual differences between the light guide rods and improves the detection accuracy by increasing the light amount of the detection light output from the light guide rod without measuring the amount of leakage light depending on internal defects and scratches. A technical problem is to enable the light guide rod to emit light having a uniform light amount distribution.

In order to solve this problem, the light amount monitor according to the present invention is for detecting the amount of light emitted from the light source to the object to be irradiated. A light guide rod composed of a polygonal rod integrator that emits light from the other end, which is a light output end face, is uniformized from light incident from one end, which is the end face, and the edge is arranged on the outer peripheral surface of the edge portion of the light output end face. A light diffuser for further diffusing the light scattered and emitted to the outside is provided, and an optical sensor for detecting the light diffused by the diffuser is provided.
The light source device according to the present invention is characterized by including a light amount controller that controls the amount of irradiation light in accordance with the amount of light detected by the light amount monitor described above.

Since the light quantity monitor according to the present invention is provided with a light guide rod made of a rod integrator in the optical path from the light source to the irradiated object, even if there is a light distribution in the light emitted from the light source, the rod integrator is uniform. And emitted from the light emitting end face.
The emitted light is directly applied to the irradiated object, or is guided by a light guide or the like to be applied to the irradiated object.

Here, since the edge portion formed by the ridge line between the light emitting end surface and the side surface of the light guide rod is formed as a rough surface when viewed microscopically, the edge portion of the light traveling through the rod is irradiated to the edge portion. The scattered light is scattered and emitted to the outside of the rod.
In addition, the amount of scattered light emitted from the rough surface of the edge is much larger than light leakage due to internal defects formed inside the rod and scratches on the side surfaces, and clears certain quality inspections. Since all rods are substantially uniform, the amount of scattered light from the edge portion is substantially constant and there is almost no individual difference between the light guide rods.
However, since the traveling direction and directivity of the scattered light toward the outside of the rod differ depending on the rod, the scattered light is further diffused by a light diffuser provided on the outer peripheral surface of the edge portion, and averaged and guided to the optical sensor. Is detected as the amount of irradiation light.

Thus, in the present invention, the scattered light from the edge portion of the light exit end face of the light guide rod is further diffused by the diffuser and detected for averaging, so there is no individual difference of the light guide rod and the detection accuracy Can be improved.
In addition, since the light guide rod is formed by a rod integrator, even if the incident light has a light amount distribution such as a Gaussian distribution, the light amount distribution of the emitted light can be made uniform and uniform. When illumination light having a certain light quantity distribution is required, it is not necessary to provide an optical system for making the light uniform separately.

  In this example, the individual difference of the light guide rod is eliminated, and the detection accuracy is improved by increasing the light amount of the detection light output from the light guide rod without measuring the leakage light amount depending on internal defects and scratches, In order to achieve the task of emitting light with a uniform light distribution from the light guide rod, a polygonal rod integrator that emits light with uniform light is used as the light guide rod, and the edge of the light exit end face The scattered light from the part was further diffused by the light diffuser and averaged, and the light quantity was detected by the optical sensor as the irradiation light quantity.

  FIG. 1 is an explanatory view showing a light source device according to the present invention, FIG. 2 is an explanatory view showing a light guide rod, FIG. 3 is an explanatory view showing a dimming filter, and FIG. 4 is an explanatory view showing a light detection mechanism by a light amount monitor. FIG. 5 is an explanatory diagram showing the relationship between the detected light amount and the irradiated light amount.

  The light source device 1 shown in FIG. 1 irradiates illumination light to the inspection object via the bundle fiber 2 when, for example, imaging the surface of the inspection object (object to be irradiated) and performing product inspection by image processing. The light amount monitor 5 for detecting the irradiation light amount of the illumination light irradiated to the inspection object (irradiated object) from the light source 4 such as a metal halide lamp is irradiated on the housing 3 according to the detected light amount. A light amount controller 6 for feedback control of the light amount is provided.

The light quantity monitor 5 is a regular hexagonal columnar rod that uniformizes light incident from one end side that becomes the light incident end face 7in and emits it from the other end side that becomes the light exit end face 7out in the optical path from the light source 4 to the irradiated object. A light guide rod 7 made of an integrator is provided.
In this example, the light guide rod 7 is formed of a regular hexagonal glass body having a cross section of 21 mm between the opposite sides and a length of 120 mm, and the optical axis X of the elliptical reflecting mirror 8 that collects the light emitted from the light source 4. In addition to being disposed coaxially, the second focal point F of the reflecting mirror 8 is disposed at the center of the light incident end face 7in, and the light incident end 2in of the bundle fiber 2 is disposed opposite to the light exit end face 7out. ing.

  Further, as shown in FIG. 2, the light guide rod 7 is provided with a light diffuser 10 that further diffuses light scattered from the edge portion 9 to the outside on the outer peripheral surface of the edge portion 9 of the light emitting end face 7out. In this example, a light diffuser 10 also serving as a spacer made of Teflon resin (trade name of DuPont) is attached in the longitudinal direction along the side surface of the hexagonal column and is inserted into the light shielding case 11.

The light shielding case 11 is formed with a hexagonal insertion hole 12 into which the light guide rod 7 is inserted, and a light diffusion space comprising an annular groove having an inner peripheral surface 13 formed on the light diffusion surface on the light emitting end surface 7out side. 14 is formed so as to surround the edge portion 9 of the light emitting end face 7out, and a photoelectric conversion type optical sensor 15 such as a silicon photocell that detects the amount of light diffused by the light diffuser 10 as the amount of irradiation light. The light diffusion space 14 is provided with a surface parallel to the side surface of the light guide rod 7.
As a result, the light scattered by the edge portion 9 facing the optical sensor 15 is diffused by the light diffuser 10, averaged and incident on the optical sensor 15, and the back surface of the light guide rod 7 with respect to the optical sensor 15. The light scattered by the edge portion 9 on the side enters the optical sensor 15 while being scattered in the light diffusion space 14.
In this case, if the frost processing is performed on the light emitting end face 7out of the light guide rod 7 so as not to affect the amount of irradiation light, a part of the light transmitted through the light guide rod 7 is put in the light guide rod 7. Since a part of the return light is incident on the light diffusion space 14 from the side surface of the rod, the detected light quantity can be further increased.

The light quantity controller 6 is connected to the optical sensor 15 of the light quantity monitor 5 on the input side, and includes a step motor 17 that rotates the dimming filter 16 by a predetermined angle on the output side.
The light control filter 16 is formed so that a large number of slits whose aperture ratio gradually changes are arranged on the circumference (see FIG. 3), and the amount of transmitted light gradually increases / decreases in accordance with the rotation direction with rotation. It has become.

  In addition, 18 is a lighting circuit such as a metal halide lamp serving as the light source 4, and 19 is an infrared cut filter.

The above is one configuration example of the present invention, and the operation thereof will be described next.
The light emitted from the light source 4 is condensed at the second focal point F by the elliptical reflecting mirror 8 and is incident on the hexagonal columnar light guide rod 7 and travels straight toward the light emitting end surface 7out or is reflected by the side surface. While going to the light exit end face 7out.
Since the light guide rod 7 is formed by a rod integrator, the light quantity distribution is made uniform and emitted from the light emitting end face 7out, guided to the inspection object (irradiated object) by the bundle fiber 2, and irradiated as illumination light. The
Therefore, even if the light incident on the light guide rod 7 has a light amount distribution such as a Gaussian distribution, the light amount distribution of the emitted light can be made uniform, and illumination light having a uniform light amount distribution can be obtained. When required, it is not necessary to separately provide an optical system for uniformizing light.

When viewed microscopically, the edge portion 9 of the light emitting end surface 7out is formed with a rough surface as shown in FIG. 4, and therefore, the light reaching the edge portion 9 among the light traveling in the light guide rod 7 is scattered. The light is emitted from the light guide rod 7 in a random direction.
At this time, since the light diffuser 10 is disposed on the outer peripheral surface of the edge portion 9, of the light scattered in a random direction, the scattered light emitted from the edge portion 9 facing the optical sensor 15 is The scattered light diffused by the light diffuser 10, averaged and incident on the light sensor 15, and scattered light emitted from the edge portion 9 on the back surface side of the light guide rod 7 with respect to the light sensor 15 diffuses in the light diffusion space 14. While entering the optical sensor 15.

The amount of light emitted from the rough surface of the edge portion 9 is much larger than light leakage caused by internal defects formed inside the rod 7 or scratches on the side surfaces, and has cleared certain quality inspections. Since all the light guide rods 7 are substantially uniform, the amount of scattered light from the edge portion 9 is substantially constant, and there is almost no individual difference due to the light guide rod 7.
In this way, since the detection light detected by the optical sensor has no individual difference due to the light guide rod 7, there is no large difference in gain when performing calibration at the time of shipment from the factory. There is an advantage that it becomes easy.

  Further, since the scattered light from the edge portion 9 is further diffused by the light diffuser 10 and averaged and detected by the optical sensor 15, the traveling direction and directivity of the scattered light toward the outside of the rod 7 are guided. Even if there is a difference depending on the rod 7, the amount of irradiation light can be detected without being affected by the influence.

According to the inventor's experiment, the irradiation light amount change regardless of whether the light amount change of the illumination light is caused by the light amount change of the light source 4 or the light amount distribution of the light incident on the light guide rod 7 is irradiated. A correlation was found between the light amount and the detected light amount detected by the optical sensor 16.
That is, the amount of irradiation light is detected by an optical sensor (not shown) placed at the light emitting end of the bundle fiber 2 and the detected amount of light when a rated voltage is applied is set to 100%. When comparison was made with the detected light quantity set to 100%, a linear relationship as shown in FIG. 5 was obtained.

When this light source device 1 is used as an illumination light source for inspection, the irradiation light quantity after lighting for 1500 to 2000 hours is expected to be reduced by about 40% compared to the initial light quantity. The light quantity 4 is reduced to about 60% of the maximum light quantity.
In this state, the detected light quantity Q ₀ detected by the optical sensor 15 of the light quantity monitor 5 is stored as 100% in the light quantity controller 6 so that the detected light quantity Q becomes equal to the initially stored detected light quantity Q ₀ when the detected light quantity Q changes. The dimming filter 16 is rotated.
Since the detected light quantity Q tends to decrease with time, for example, when the detected light quantity Q decreases by 1%, the dimming filter 16 is rotated in the direction in which the slit 16a becomes larger, and the detected light quantity Q = 100 (% ) Adjust the amount of light so that

  In this case, the detected light quantity Q is always maintained at 100 (%), and the light quantity is adjusted every time the detected light quantity Q changes by 1%, and the cause is due to the change in the light quantity of the light source 4. Even if it is caused by a change in the light amount distribution, the irradiation light amount can be accurately detected regardless of the cause.

  In this way, the light amount incident on the light guide rod 7 is gradually increased by the dimming filter 16 according to the detected light amount, so that the light amount is maintained substantially equal to the initial irradiation light amount even after lighting for 1500 to 2000 hours. Can be irradiated.

In the above description, the dimming filter 16 that variably controls the amount of light incident on the light guide rod 8 is used as the light amount controller 6. However, the present invention is not limited to this, and is a dimming circuit that variably controls the lamp light amount. May be.
The light source 4 is not limited to a lamp that emits visible light, but can be applied to a light irradiation device that uses an ultraviolet lamp or an infrared lamp as a light source.
Further, the scattered light emitted from the edge portion 9 on the back surface side is guided to the optical sensor 15 while being diffused on the inner peripheral surface of the light diffusion space 14 even if the light diffuser 10 is not provided. It is sufficient that the body 10 is formed at least on the side facing the optical sensor 15, and the body 10 is not necessarily provided on the back side.
The light guide rod 7 is not limited to a regular hexagonal column, and may be an arbitrary polygonal rod integrator. In particular, when the irradiation light is projected as it is onto a rectangular screen or substrate, the cross section is vertical and horizontal such as the screen. A square columnar rod integrator equal to the ratio may be used.

  As described above, the present invention is applied to the use of a light source device such as an inspection device that needs to maintain a constant amount of light irradiated to an inspection object, such as an image processing inspection device using a CCD camera or the like. can do.

An explanatory view showing a light source device concerning the present invention. Explanatory drawing which shows a light guide rod. Explanatory drawing which shows a light control filter. Explanatory drawing which shows the detection mechanism of the light by a light quantity monitor. The graph which shows the relationship between detected light quantity and irradiation light quantity.

Explanation of symbols

1 Light source device
4 Light source
5 Light intensity monitor
6 Light quantity controller 7 Light guide rod
7in light incident end face 7in
7out Light exit end face 7out
9 Edge part
10 Light diffuser
14 Light diffusion space
15 Optical sensor

Claims (3)

A light amount monitor for detecting the amount of illumination light irradiated from the light source to the object,
In the optical path from the light source to the object to be irradiated, a light guide rod composed of a polygonal column-shaped rod integrator that uniformizes the light incident from one end that is the light incident end face and emits it from the other end that is the light exit end face is arranged. A light diffuser for further diffusing the light scattered at the edge portion and emitted to the outside is provided on the outer peripheral surface of the edge portion of the light emitting end face, and the amount of light diffused by the diffuser is A light amount monitor characterized in that an optical sensor for detecting as is arranged.   An annular light diffusing space having an inner peripheral surface formed as a light diffusing surface is formed on the light emitting rod end surface side so as to surround the edge portion, and the light sensor is disposed in the light diffusing space, The light quantity monitor according to claim 1, wherein a light diffuser is provided at least at an edge portion facing the optical sensor among the edge portions. In a light source device including a light amount monitor that detects an irradiation light amount of illumination light irradiated on an object to be irradiated from a light source, and a light amount controller that controls the irradiation light amount according to the detected light amount,
As the light amount monitor, in the optical path from the light source to the object to be irradiated, light introduced from one end side that is the light incident end face is made uniform, and is guided by a polygonal columnar rod integrator that is emitted from the other end side that is the light exit end face. An optical rod is provided, and a light diffuser is provided on the outer peripheral surface of the edge portion of the light emitting end face to further diffuse the light scattered and emitted to the outside, and the amount of light diffused by the diffuser A light source device is provided, in which an optical sensor for detecting the irradiation light quantity is disposed.

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