KR100655638B1 - Light source and light intensity monitor for the same - Google Patents

Abstract

Even if there is a change in the amount of irradiation light due to the amount of lamp light or there is a change in the amount of irradiation light due to the change in the light quantity distribution pattern, it is a problem to make it possible to detect this accurately and to keep the amount of irradiation light constant.

Light quantity monitor which collects the light of the lamp 4 with the reflecting mirror 5, it exits from the light exit opening 6, and detects the irradiation light quantity of the light irradiated to an irradiated object when it irradiates to an irradiated object directly or indirectly ( In the light source device 1 provided with M) and the light amount controller 7 which feedback-controls the amount of irradiation light according to the detected light amount, the light amount monitor M is configured to emit light condensed by the reflector 5 to the light exit port. The light guide rod 8 used as the optical path leading to (6), and the optical sensor 9 which detects the light leakage amount from the circumferential surface 8a of this light guide rod 8 as irradiation light quantity were provided.

Lamps, reflectors, light exit ports, light controllers, light guide rods, light sensors, light filters, light diffusers, light shields, apertures.

Description

LIGHT SOURCE AND LIGHT INTENSITY MONITOR FOR THE SAME}

1 is an explanatory diagram showing a light source device according to the present invention;

2 is an explanatory diagram showing a dimming filter;

3 is an explanatory diagram showing a light quantity monitor;

4 is an explanatory diagram showing a light quantity monitor;

5 is an explanatory diagram showing a light quantity monitor;

6 is an explanatory diagram showing a light quantity monitor;

7 is an explanatory diagram showing a light quantity monitor;

8 is an explanatory diagram showing a light quantity monitor;

9 is a graph showing the relationship between the light loss and the detected light amount and the irradiated light amount by frost processing;

10 is a graph showing the relationship between the amount of irradiation light and the amount of detection light;

It is explanatory drawing which shows the conventional apparatus.

(Description of the sign)

1 Light source unit 4 Lamp

5 Reflector 6 Light exit                 

M (M _{1 to} M ₆ ) Light Monitor 7 Light Controller

8 light guide rod 8a perimeter

9 Optical sensor 9a photodetection surface

10 Dimming Filter 12a, 16a Light Diffusion Surface

13, 15 Shading Pipe (Shading) 14, 17 Light Diffusion Space

16 annular recess 18 aperture

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light source device having a light amount controller, and is particularly suitable for use in a light source of an inspection apparatus that needs to maintain a constant amount of light irradiated to an inspection object, such as an image processing inspection apparatus using a CCD camera or the like. will be.

For example, in the flat panel display manufacturing process, the image processing inspection apparatus which conventionally irradiates light to the glass plate or coating surface which becomes an inspection object, observes this with a CCD camera, etc., and detects defects, such as a flaw and coating defect, are used. .

In this case, as a condition required for the light source device, the amount of light to the inspection object (irradiation object) does not change at least during the inspection time, and the light of the required amount of light can be irradiated according to the light receiving sensitivity performance level of the camera to be used. And the like.

As a light source of the light source device for the image processing inspection, a discharge lamp such as a solid state optical device such as a halogen lamp, an LED, a mercury lamp, and a metal halide lamp is used, and among these, a discharge lamp such as a mercury lamp or a metal halide lamp has a start time. Although it is slow, a high light quantity can be obtained, and it is optimal as this kind of light source.

However, when these discharge lamps are turned on for 1000 to 2000 hours, the amount of irradiation light to the inspection object is gradually attenuated. Therefore, the light amount adjustment is necessary every time so that the brightness of the camera side does not change during use.

Therefore, conventionally, as shown in FIG. 11, the light of the mixing rod 33 which uniformly distributes the light quantity distribution of the light irradiated from the lamp 31 and transmitted through the infrared cutoff filter 37 to the bundle fiber 32 is shown. One end of the detection optical fiber 34 is connected to the output end 33out, and is output from the driving circuit 36 based on the amount of light detected by the light receiving element 35 connected to the other end of the detection optical fiber 34. The power supply of the lamp 31 is controlled.

(Patent Document 1) Japanese Patent Laid-Open No. 2001-307523

By the way, according to the experiment of the inventors, when the amount of light emitted from the light exiting end 33out of the mixing rod 33 is detected, it is possible to accurately detect the change in the amount of emitted light of the lamp itself 31, When it was used, it turned out that this irradiation light quantity change may not be detected, although the irradiation light quantity to an inspection object changes.

Further, in pursuit of the cause, the cause of the attenuation of the amount of light emitted to the inspection object with time decreases, rather than a change in the amount of emitted light of the lamp 31 itself, rather than a change in the amount of light emitted by the change of the electrode, It turned out that the influence by the change of the light-distribution pattern of a lamp is strong, for example, moving away from a focus.

That is, even if there is almost no change in the light emission amount of the lamp 31, if the light quantity distribution pattern is changed, the amount of irradiation light irradiated to the inspection object through the bundle fiber or the like is changed.

When the light is extracted from the light output end 33out of the mixing rod 33 and the amount of light is detected, even if the amount of irradiation light changes, for example, the light emitting point is out of the first focus, the amount of light emitted by the lamp 31 itself changes. If not, this could not be detected, and eventually a fatal defect occurred that the amount of irradiation light to the inspection object could not be kept constant.

This is considered to be because a part of the strong light irradiated from the lamp 31 is directly irradiated to the part which connects the optical fiber 34 for a detection of the light output end part 33out.

At present, the apparatus has a characteristic that the ratio between the amount of light incident on the bundle fiber 32 and the amount of light of the optical fiber for detection is not changed even if the light amount distribution pattern is different by the lamp 31. It was hardly possible to detect a change in the amount of irradiation light due to the change.

Therefore, an object of the present invention is to accurately detect this and to keep the amount of irradiation light constant even if there is a change in irradiation light amount due to a change in the lamp light quantity or a change in irradiation light amount due to a change in the light quantity distribution pattern. .

In order to solve this problem, the present invention provides a light amount for detecting the amount of light irradiated onto an irradiated object when the light of the lamp is collected by a reflector and emitted from the light exit port, and irradiated directly or indirectly onto the irradiated object. A light source device including a monitor and a light amount controller for feedback-controlling the amount of irradiation light according to the detected light amount, wherein the light amount monitor is a light guide rod serving as an optical path for guiding light collected by a reflector to a light exit port; And an optical sensor for detecting the amount of light leakage from the circumferential surface of the rod as the amount of irradiation light.

(The best form to carry out invention)

In this example, even if there is a change in the irradiation light amount due to the change in the light emission amount of the lamp itself as well as a change in the irradiation light amount due to the change in the light quantity distribution pattern, the problem of accurately detecting this and keeping the irradiation light amount constant is extremely simple. Realized.

1 is an explanatory diagram showing a light source device according to the present invention, FIG. 2 is an explanatory diagram showing a dimming filter, 3 to 8 are explanatory diagrams showing a light quantity monitor, and FIG. 9 is an optical loss due to frost processing. And a graph showing the relationship between the detected light amount and the irradiated light amount, and FIG. 10 is a graph showing the relationship between the irradiated light amount and the detected light amount.

The light source device 1 shown in FIG. 1 irradiates illumination light to an inspection object through the bundle fiber 2, for example, when imaging the surface of an inspection object (irradiation object) and performing product inspection by image processing. Used for

The light source device 1 condenses the light emitted from the metal halide lamp 4 disposed in the casing 3 with an ellipsoidal reflector 5, passes through the infrared cutoff filter 20, and emits the light exit port 6 2) is irradiated to the inspection object through the bundle fiber 2 connected to the light exit port 6.

In addition, in the casing 3, a light amount monitor M for detecting the amount of irradiation light of the light irradiated to the inspection object and a light amount controller 7 for feedback control of the amount of irradiation light according to the detected light amount are provided. The lighting circuit 21 and the cooling fan 22 of the lamp 4 are arranged.

The light quantity monitor M includes a light guide rod 8 serving as an optical path for guiding the light collected by the reflector 5 to the light exit port 6, and a leak from the peripheral surface 8a of the light guide rod 8. The photoelectric conversion type optical sensor 9, such as a silicon photocell, which detects light quantity as an irradiation light quantity, is provided.

The light guide rod 8 is formed of a transparent glass body, and in this example, is made of a cylindrical rod having a diameter of 12.4 mm and a length of 40 mm, so that the second focal point of the reflector 5 is located at the center of the light incident cross section 8 in. Attached.

The light quantity controller 7 is provided with the step motor 11 which connects the optical sensor 9 of the light quantity monitor M to the input side, and rotates the dimming filter 10 by the predetermined angle on the output side.

In the dimming filter 10, a plurality of slits in which the passage ratio gradually changes are arranged on the circumference (see Fig. 2), and the amount of transmitted light increases and decreases in accordance with the rotational direction with rotation.                     

3 to 8 show examples of the light amount monitors M _{1 to} M ₆ according to the present invention.

The light amount monitor M ₁ shown in FIG. 3A makes the light detection surface 9a of the optical sensor 9 touch the circumferential surface 8a of the light guide rod 8.

Thereby, the light which permeate | transmits in the light guide rod 8 hits the defect C in the light guide rod 8, or shows the inside of the light guide rod 8, as shown to FIG. 3 (b). If light propagating while totally reflecting the surface is scratched on the circumferential surface 8a or diffusely reflected, part of the light leaks to the optical sensor 9 side, and thus the amount of light leakage is detected by the optical sensor 9.

In the light quantity monitor M ₂ shown in FIG. 4A, a light shielding pipe (light shielding material) 13 in which a mounting hole 12 for mounting the optical sensor 9 is formed through the pipe wall 13a is provided with a light guide rod. The peripheral surface 8a of the light guide rod 8 is covered with a light shielding material, except for a part that is externally mounted on (8) and guides out light leakage detected by the optical sensor 9 to the outside.

According to the configuration, the optical sensor brightness (9) to the other press is that the amount of light detected light quantity monitor (M ₁₎ with the same, a peripheral surface (8a) as shown in Fig. 4 (b) is, the light guide rod 8 It is not affected by the change of or external light leaking into the casing 3.

Moreover, when the inner surface of the mounting hole 12 is formed with the light-diffusion surface 12a, when the light detection surface 9a of the optical sensor 9 is mounted facing the circumferential surface 8a of the light guide rod 8, The light diffusion space 14 surrounded by the light diffusion surface 12a has a gap (for example, about 8 mm) between the light detection surface 9a and the circumferential surface 8a of the light guide rod 8.

As a result, light leakage from the mounting hole 12 is scattered and averaged in the light diffusion space 14, which is considered to increase detection accuracy.

In the light quantity monitor M ₃ shown in FIG. An annular light diffusion space 17 serving as the surface 16a is formed, and the optical sensor 9 faces the circumferential surface of the light guide rod 8 with a predetermined gap (for example, about 8 mm). It is attached to (17).

According to this, as shown in FIG.5 (b), the light-diffusion space 17 is formed over the perimeter of the circumferential surface 8a of the light guide rod 8, and opposes the optical sensor 9 Light leakage from the entire circumference of the light guide rod 8 as well as the portion is diffused into the light diffusion space 17, so that the amount of light leakage of the entire light can be detected by the optical sensor, so that the detection accuracy is improved.

The light quantity monitor M ₄ shown in FIG. 6 (a) is projected to a light incidence end surface 8 in of the light guide rod 8 of the light quantity monitor M ₃ smaller than the diameter of the light guide rod 8. The aperture 18 in which the light part 18a was formed is attached, and the light incident side end surface peripheral edge part 8b of the light guide rod 8 is covered by this.

According to this, even if a large defect or a flaw generate | occur | produces in the circumferential edge part 8b of the light guide rod 8, as shown to FIG. 6 (b), the light which permeate | transmits the defect or a flaw can be interrupted | blocked. This does not adversely affect the detection accuracy, and as a result, the detection accuracy is improved.                     

FIG light quantity monitor (M ₅₎ shown in 7 (a) is, on the light exit cross section (8out) of the light guide rod 8 of the light quantity monitor (M _3), so the irradiation light amount is not significantly reduced, the light guide rod Frost processing is performed to return a part of the light passing through (8) into the light guide rod (8).

According to this, as shown in FIG.7 (b), a part of the light which permeate | transmits the light guide rod 8 is returned to the light guide rod 8, and a return light carries out the diffuse reflection by the internal defect or the flaw of the light guide rod 8 And part of the light leakage occurs, the light leakage amount increases, and the detection accuracy is further improved.

Although the frost process is formed by roughening the light exit cross section 8out, the light passing through the light exit cross section 8out is diffusely reflected to produce a light amount loss by the frost process, but the amount of detection light is improved by that amount.

Fig. 9 is a graph showing the change in the amount of detection light and the amount of irradiation light with respect to the light loss by frost processing, wherein the horizontal axis is the light loss of the transmitted light of the light guide rod when the frost processing is performed, and the scale on the left side of the vertical axis is the amount of irradiation light and the right side of the vertical axis The scale of is the amount of detected light, and the amount of light when the frost process is not all performed (light loss 0) is 100% is shown.

According to this, as the surface becomes rough by the frosting process and the light loss increases, the amount of detection light increases and detection accuracy is improved, but the amount of irradiation light from the bundled fiber 2 is lowered.                     

Therefore, for example, if it is desired to secure 90% or more of the irradiation light amount and 200% or more of the detection light amount, it is necessary to suppress the light loss due to the frost treatment to about 4.5 to 5.5%.

Further, the light amount monitor (M ₆₎ as shown in 8 (a) has, to the light input end face (8in) of the light guide rod 8 of the light quantity monitor (M _5), baby with a light quantity monitor (M ₄₎ aperture 18 is made by mounting.

According to this, as shown in FIG.8 (b), the disturbance is removed by the aperture 18, Furthermore, the amount of light leakage is large by frosting process, and detection accuracy improves more.

Figure 10 is a graph showing a detected light quantity of the irradiation light amount and a light intensity monitor (M ₁ ~M ₆₎ emitted from each of the light amount by using the monitor (M ₁ ~M _6), the fiber bundle (2) thus formed.

The change in the amount of irradiation light is largely divided into a case due to a change in the amount of light of the lamp 4 or a change in the amount of light distribution incident on the bundled fiber 2.

Therefore, the amount of light detected by the light amount monitors M _{1 to} M ₆ is measured against the amount of light emitted when the amount of light incident on the light guide rod 8 from the lamp 4 is changed, and at the same time, the second focus of the reflector 5 By detecting the position of the light guide rod 8 from the center of the light guide rod 8, the amount of detected light with respect to the amount of light emitted when the light amount distribution was changed was measured.

In the graph, the horizontal axis represents the irradiation light quantity and the vertical axis represents the detection light quantity, and the irradiation light quantity represents the amount of light detected by the optical sensor disposed at the light output end of the bundle fiber 2 when the lamp 4 is turned on at the rated voltage. The detected value and the amount of detected light are normalized by setting the amount of light detected by the light amount monitors M _{1 to} M ₆ at the time of irradiation light amount 100 as 100.

The broken line L ₀ indicates the amount of light detected by the light amount monitors M _{1 to} M ₆ with respect to the amount of light emitted when the light control filter 10 is rotated to change the amount of incident light to the light guide rod 8.

In this case, the measurement results of any of the light amount monitors M _{1 to} M ₆ coincide with each other, and the detected light amount accurately follows the irradiation light amount.

Further, the solid line of L ₁ ~L ₆ is a reflector 5, the light quantity monitor for the irradiation light amount change is changed by placing it shifted from the position of the focus from the center of the light guide rod _{(8) (M 1 ~M 6} ) of The change in the detected light amount is shown.

In this case, the amount of detected light of the light quantity monitor M ₆ having the aperture 18 mounted on the light incidence end surface 8in of the light guide rod 8 and subjected to a frost treatment on the light output end face 8out is applied to the irradiation light amount. Followed correctly (see solid line L ₆ ).

Therefore, the light quantity monitor M ₆ can detect the light leakage amount as the irradiation light amount even when the change in the irradiation light amount is due to the change in the light quantity of the lamp 4 or the change in the light amount distribution.

In addition, other light quantity monitors M _{1 to} M ₅ do not accurately track the amount of detected light over the entire range, but are detected like the light amount monitor M _{6 in} the range of 100% of the emitted light amount. The amount of light accurately follows the amount of irradiation light (see solid lines L _{1 to} L ₅ ).

That is, since the light leakage amount detected by the optical sensor 9 corresponds to the irradiation light quantity irradiated from the bundle fiber 2, even when the change in the irradiation light quantity is due to the light quantity change of the lamp 4, Even when it originates, it becomes possible to detect the light leakage amount as an irradiation light amount.

The above is one structural example of this invention, and the effect | action is demonstrated next.

Since the amount of irradiated light after lighting for 1500 to 2000 hours is expected to be about 40% as compared with the initial amount of light, the dimming filter 10 initially reduces the light amount of the lamp 4 to about 60%.

In this state, the detected light quantity Q ₀ detected by the light sensor 9 of the light quantity monitor M (M _{1 to} M ₆ ) is set to 100% and stored in the light quantity controller 7 so that the detected light quantity Q is when a change is detected to be the same as the initial storage amount of light (Q ₀₎ which rotates the light control filter 10.

Since the detection light quantity Q tends to decrease with time, for example, when the detection light quantity Q falls 1%, the dimming filter 10 is rotated in the direction in which the slit 10a becomes large, and the detection light quantity The amount of light is adjusted so that (Q) = 100 (%).

In this case, the detection light quantity Q is always kept at 100%, and since the light quantity is adjusted every time the detection light quantity Q changes by 1%, the detection light quantity Q always changes in the vicinity of 100%. Accordingly, even when any of the light amount monitors M _{1 to} M ₆ is used, the change in the irradiation light amount can be detected accurately.

In addition, even if the cause is due to the change in the light quantity of the lamp 4 or the change in the light quantity distribution, the irradiated light amount can be detected accurately regardless of the cause.

In this way, the incident light to the light guide rod 8 is gradually increased by the dimming filter 10 in accordance with the detected light amount, so that light can be irradiated at approximately the same light amount as the original irradiation light even after 1500 to 2000 hours of lighting.

In addition, in the above description, as the light amount controller 7, the dimming filter 10 which variably controls the amount of incident light to the light guiding rod 8 is used, but the present invention is not limited thereto, and the light control circuit variably controls the amount of lamp light. good.

The present invention is not limited to the case of using the lamp 4 for irradiating visible light, but can also be applied to a light irradiation apparatus using an ultraviolet lamp or an infrared lamp as a light source.

As described above, according to the light source device according to the present invention, since the change in the irradiation light amount due to the change in the lamp light amount and the change in the irradiation light amount due to the change in the light amount distribution can be detected in the same manner, A very good effect can be achieved that can be controlled to keep the irradiation light constant.

 Since the light guide rod has numerous internal defects and also scratches on the outer surface of the light guide rod, when light collected by a reflector enters the light guide rod, it causes diffuse reflection with internal defects or scratches, and part of the light leaks from the circumferential surface. .

According to the inventor's experiment, an optical sensor was installed on the circumferential surface of the light guide rod to detect an amount of light leakage from the light guide rod and the amount of irradiation light to the irradiated object from the tip of the bundle fiber connected to the light exit port of the light guide rod. Even if there was a change in the irradiation light amount due to the change in the light emission amount of the lamp itself as well as a change in the irradiation light amount due to the change in the light quantity distribution pattern, this could be accurately detected.

That is, even if the cause is unknown, the amount of irradiation light of the light irradiated onto the irradiated object can be detected reliably.

Therefore, if the amount of light incident on the light guide rod from the lamp is adjusted when the amount of detected light changes, the amount of light can be kept constant.

In this case, as described in claim 2, the light amount adjustment may be performed by variably controlling the amount of incident light to the light guide rod by the dimming filter.

In addition, as shown in claim 4, if the circumferential surface of the light guide rod of the light quantity monitor is covered with the light shielding material except for a portion which leads out leakage of light detected by the optical sensor to the outside, the light quantity is not affected by the light incident from the outside. Can be detected.

In addition, as shown in claim 5, when the light detecting surface of the optical sensor is disposed opposite to the circumferential surface of the light guide rod, and a light diffusion space surrounded by the light diffusion surface is formed in the gap between the circumferential surface of the light guide rod and the light detecting surface. Since light leaked in the light diffusion space is averaged, it can be detected more accurately.

In addition, as shown in claim 6, when a light diffusion space made of annular concave grooves formed on an inner circumferential surface of a light shielding pipe that is external to the light guide rod is formed, and an optical sensor is attached to the light diffusion space, light leakage from the entire circumference of the light guide rod is obtained. Since the light is diffused in the light diffusion space and the light leakage amount of the whole can be detected by the optical sensor, the detection accuracy is improved.

Since large defects or scratches are likely to occur in the peripheral edge of the light guide rod, and the presence of such defects or scratches affects the detection accuracy, the aperture formed with a light-transmitting portion having a diameter smaller than the diameter of the light guide rod is guided as in claim 7. If it adheres to the light incidence side end surface of a rod and it covers the edge part of the cross section, the light which permeate | transmits the defect and a damage | wound can be interrupted | blocked, and a detection accuracy improves as a result.

In addition, as described in claim 8, when the frost treatment is applied to the light output cross section of the light guide rod so as not to affect the amount of irradiation light, a part of the light passing through the light guide rod is returned to the light guide rod, and the return light is an internal defect of the light guide rod. Since light reflection causes scratches and a part of light leakage occurs, the amount of light leakage increases and detection accuracy is improved.

(Industrial availability)

According to the present invention, the amount of light to be inspected (irradiated object) does not change at least during the inspection time, and the image processing inspection is requested to be able to irradiate light of the required amount of light according to the light receiving sensitivity performance level of the camera to be used. It can be applied to a light source device such as a device.

Claims (8)

A light amount monitor for detecting the amount of light emitted from the light to be irradiated onto the irradiated object when the light of the lamp is condensed with a reflector and emitted from the light exit port, and irradiated directly or indirectly to the irradiated object, and the amount of irradiated light according to the detected light quantity A light source device having a light amount controller for controlling feedback, The light quantity monitor includes a light guide rod serving as an optical path for guiding light collected by a reflector to a light exit port, and an optical sensor for detecting an amount of light leakage from a circumferential surface of the light guide rod as the irradiation light quantity. Light source device. The light source device according to claim 1, wherein the light amount controller includes a dimming filter for variably controlling the amount of incident light to the light guide rod. A light amount monitor for detecting the amount of light emitted from a light source and irradiated to the irradiated object, the light guide rod serving as an optical path for guiding light emitted from the light source, and the amount of light leakage from the circumferential surface of the light guide rod as the irradiation light amount. Light quantity monitor comprising a light sensor to. The light quantity monitor according to claim 3, wherein the circumferential surface of the light guide rod is covered with a light shielding material, except for a portion which leads light leakage detected by an optical sensor to the outside. 4. The light diffusion surface of claim 3, wherein the light detection surface of the optical sensor is disposed opposite to the circumferential surface of the light guide rod, and a light diffusion space surrounded by the light diffusion surface is formed in a gap between the light detection surface and the circumference of the light guide rod. Light quantity monitor characterized in that. 4. The light diffusion space according to claim 3, wherein a light diffusion space is formed on an inner circumferential surface of the light shielding pipe which is external to the light guide rod, the light diffusing surface having an inner surface of an annular concave groove formed along the circumferential direction thereof as a light diffusion surface. The light quantity monitor which is attached to this light-diffusion space opposing a circumferential surface. 4. The light quantity monitor according to claim 3, wherein the light incident-side end surface circumferential edge portion of the light guide rod is covered by an aperture formed with a light transmitting portion having a diameter smaller than the diameter of the light guide rod. The light quantity monitor according to claim 3, wherein a frosting process of returning a part of the light passing through the light guiding rod into the light guiding rod is applied to the light exit section of the light guiding rod.

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