JPH10142050A - Illuminance discriminating device for illuminator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and surely optimize the illuminance level of an illuminator. SOLUTION: When an illuminator irradiates semiconductor pellets 21 which are the object of a camera 11 with light, a generation discriminator 15 is incorporated in the illuminance discriminating device 10 of the illuminator 20 so that the appropriateness of the illuminance of the illuminator 20 can be discriminated by generating a gradation histogram indicating the brightness distribution in a picture taken with the camera 11 and checking whether or not the histogram satisfies at least one of the following conditions (a) to (c) by comparison: (a) The distribution center of gravity of the gradation histogram exists in a prescribed extent, (b) The distributed extent of the histogram exists out of the prescribed extent, and (c) The maximum peak value of the histogram exceeds a prescribed value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illuminance judging device for an illuminating device for judging an illuminance level of the illuminating device.

[0002]

2. Description of the Related Art For example, an image processing apparatus is provided in a semiconductor manufacturing apparatus, and an object such as a semiconductor pellet or a lead frame is imaged by an image capturing apparatus, and the captured image is processed by the image processing apparatus. , The position of the target object and the like are detected. At this time, in order to capture an image of the object in an easily recognizable state, the object is irradiated with light from a lighting device to improve the accuracy of the position detection.

[0003]

By the way, the illuminance level of the lighting device is adjusted based on the operator's feeling and experience value by the operator viewing the image processed by the image processing device on a monitor. I have.

[0004] For this reason, there is a possibility that the operator may have individual differences in the optimal illuminance level of the illumination device, and the accuracy of position detection by the image processing device may vary.

SUMMARY OF THE INVENTION [0005] An object of the present invention is to provide an illuminance determination device for an illuminating device that can easily and reliably optimize the illuminance level of the illuminating device.

[0006]

According to a first aspect of the present invention, there is provided an illuminance determination device for an illumination device which irradiates an object to be imaged by an imaging device with a brightness distribution of an image captured by the imaging device. A shading histogram is created, at least one of the following (a) to (C) is compared and examined, and a creation determiner that determines that the illuminance of the lighting device is appropriate when satisfied is satisfied. .

(A) The distribution center of the density histogram is within a predetermined range. (B) The distribution range of the density histogram is within a predetermined range. (C) The maximum peak value in the density histogram exceeds a predetermined value.

According to a second aspect of the present invention, in the first aspect of the present invention, the predetermined range relating to the distribution center of the density histogram is obtained by dividing the density of the density histogram with respect to the median value of the density histogram. Approximately ±
It is intended to be in the range of 10%.

According to a third aspect of the present invention, in the first aspect of the present invention, the predetermined range regarding the distribution range of the density histogram is a difference between a maximum value and a minimum value in the distribution range. Is in the range of about 50 to 70% of the number of divided gradations.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the predetermined value relating to the maximum peak value of the density histogram is about 60% with respect to the total number of pixels of the captured image.
%.

According to a fifth aspect of the present invention, there is provided an illuminance determination device for an illumination device for irradiating an object to be imaged with an imaging device with an illuminance adjustment device capable of adjusting the illuminance by the illumination device, and Create a density histogram indicating the brightness distribution of the captured image, compare and examine the following (a) to (c), and determine that the illuminance of the lighting device is appropriate if all are satisfied, A control device that controls the illuminance adjustment device based on an output signal of the creation determination device to adjust the illuminance of the illumination device.

(A) The distribution center of the density histogram is within a predetermined range. (B) The distribution range of the density histogram is within a predetermined range. (C) The maximum peak value in the density histogram exceeds a predetermined value.

According to a sixth aspect of the present invention, there is provided an illuminance determination device for an illumination device for irradiating a semiconductor wafer imaged by an imaging device with light, wherein the illuminance of the illumination device can be adjusted, and Create a density histogram showing the brightness distribution of the captured image, compare and examine the following (a) to (d), and determine that the illuminance of the lighting device is appropriate if all are satisfied, A control device that controls the illuminance adjustment device based on an output signal of the creation determination device to adjust the illuminance of the illumination device.

(A) The distribution center of the density histogram is within a predetermined range. (B) The distribution range of the density histogram is within a predetermined range. (C) The maximum peak value in the density histogram exceeds a predetermined value. (D) The density histogram In the above, the interval between the peak values corresponding to each image of the semiconductor pellet and the dicing line on the semiconductor wafer is within a predetermined range.

The first to fourth aspects of the present invention have the following effects. The creation determiner determines that the illuminance of the lighting device is appropriate by satisfying at least one of the following (a) to (c) when the grayscale histogram created from the image captured by the imaging device: The illuminance of the lighting device can be adjusted based on the determination of the creation determiner, and the individual difference of the optimal illuminance level that occurs when the illuminance of the lighting device is determined based on the feeling or experience value of the operator can be eliminated. The illuminance level can be easily and accurately optimized.

(A) The distribution center of the density histogram is within a predetermined range. (B) The distribution range of the density histogram is within a predetermined range. (C) The maximum peak value in the density histogram exceeds a predetermined value.

The fifth aspect of the invention has the following operation. The creation determiner determines that the illuminance of the lighting device is appropriate when the grayscale histogram created from the image captured by the imaging device satisfies all of the following (a) to (c), and the control device: Since the illuminance of the lighting device is adjusted by controlling the illuminance adjusting device based on the output signal of the creation determiner, the individual difference of the optimum illuminance level that occurs when the illuminance of the lighting device is determined based on the operator's sense or experience value. Can be resolved,
The illumination level of the lighting device can be easily and accurately optimized.

(A) The distribution center of the density histogram is within a predetermined range. (B) The distribution range of the density histogram is within a predetermined range. (C) The maximum peak value in the density histogram exceeds a predetermined value.

The invention according to claim 6 has the following operation. The creation determiner determines that the illuminance of the lighting device is appropriate when the grayscale histogram created from the image captured by the imaging device satisfies all of the following (a) to (d), and the control device: Since the illuminance of the lighting device is adjusted by controlling the illuminance adjusting device based on the output signal of the creation determiner, the individual difference of the optimum illuminance level that occurs when the illuminance of the lighting device is determined based on the operator's sense or experience value. Can be resolved,
The illumination level of the lighting device can be easily and accurately optimized.

(A) The distribution center of the density histogram is within a predetermined range. (B) The distribution range of the density histogram is within a predetermined range. (C) The maximum peak value of the density histogram exceeds a predetermined value. (D) The density histogram In the above, the interval between the peak values corresponding to each image of the semiconductor pellet and the dicing line on the semiconductor wafer is within a predetermined range.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a first embodiment of an illuminance determination device for an illumination device according to the present invention. FIG. 2 is a front view showing a semiconductor wafer as an object. FIG. 3 is a diagram showing an image of the semiconductor wafer of FIG. 2 taken by a camera. FIG. 4 is a diagram showing the coordinate axes of the grayscale histogram. FIG. 5 is a graph showing the pattern I of the grayscale histogram. FIG. 6 is a graph showing the pattern II of the grayscale histogram. FIG. 7 is a graph showing a pattern III of the grayscale histogram. FIG. 8 is a graph showing a pattern IV of the grayscale histogram. FIG.
Is a graph showing a pattern V of a light and shade histogram.

As shown in FIG. 1, an illuminance judging device 10 of an illuminating device includes a camera 11 as an image pickup device, an image processing device 14 having an A / D converter 12 and a memory 13, a creation judging device 15 and a memory 16 And a lighting device adjuster 18, and an object to be imaged by the camera 11 (for example, the semiconductor pellet 2 of the semiconductor wafer 19).
This is for determining the illuminance level of the illumination device 20 that irradiates light to 1).

The semiconductor wafer 19 shown in FIG. 2 is diced and divided into a large number of semiconductor pellets 21.
Reference numeral 22 denotes a dicing line. A pellet bonding apparatus (not shown) of the semiconductor manufacturing apparatus takes out the semiconductor pellet 21 from the semiconductor wafer 19 and bonds it to an island portion of a lead frame (not shown). The camera 11 and the image processing apparatus 14 The position of the pellet 21 is detected.

When the camera 11 is irradiated with light from the illumination device 20, as shown in FIG.
The semiconductor pellet 21 is imaged.

The image picked up by the camera 11 is converted into a digital signal by the A / D converter 12 of the image processing device 14 and stored in the memory 13.
Is displayed on the monitor 23 via the. Further, based on the image data stored in the memory 13 and the reference image data set in advance in a reference image memory (not shown), the image processing device 14 executes the semiconductor pellet 21 by a known pattern matching method or the like. Detect the position of.

The creation judging unit 15 of the control unit 17 first takes in the image data stored in the memory 13 of the image processing unit 14 and, for each illuminance level of the illuminating device 20, a density histogram indicating the brightness distribution of the image. Create As shown in FIG. 4, the grayscale histogram is obtained by taking the frequency of appearance indicating the total value of the number of pixels on the vertical axis and the grayscale value (brightness) on the horizontal axis. Is divided into 256 gradations.

The density histograms shown in FIGS. 5 to 9 created for each illuminance level of the illumination device 20 are as follows.
It is stored in the memory 16 of the control device 17.

Next, the creation judgment unit 15 of the control device 17
For the density histogram stored in the memory 16,
(a) to (d) are compared and determined, and the illuminance level of the illuminating device 20 exhibiting the density histogram satisfying all of them is determined to be appropriate, and the illuminance adjuster 18 is controlled to change the illuminance level of the illuminating device 20 to Adjust to the illuminance level described above.

(A) The distribution center of gravity G is within an allowable value. As shown in FIG. 9, when the density of the density histogram is divided into 256 gradations, as shown in FIG. 9, the allowable value of the distribution center G of the density histogram is the median T of the density of the density histogram.
(128 gradations) and ± α gradation (for example, about ± 10% of the 256 gradations). If the distribution center of gravity G is in this range, even if the illuminance level of the illumination device 20 fluctuates, the grayscale histogram will not be extremely deviated as shown in FIGS. The image is less susceptible to fluctuations.

(B) The distribution range is within a predetermined range. The predetermined range of the distribution range of the density histogram, when the concentration of the density histogram is divided into 256 gradations, as shown in FIG. 9, the difference between the maximum value K _max and the minimum value K _min gray value (K
_max -K _min) is in the range of β ₁ ~β ₂ gradation (e.g., about 50% to 70% relative to the 256 gradations). If the distribution range is within this range, an image which is not too dark or too bright and is easily visible is obtained.

(C) The appearance frequency of the maximum (first) peak A is not less than a predetermined value. The largest peak in the grayscale histogram is the first peak A, and the predetermined value of the appearance frequency of the first peak A is determined by the total number of pixels (X pixels × Y shown in FIG. This is the frequency of appearance corresponding to the number of pixels of about 60% or more of (pixels). If the appearance frequency of the first peak A is equal to or higher than the above-described predetermined value, the image has a characteristic portion in the grayscale histogram and is easy to recognize.

(D) The peak interval L between the first peak A and the second peak B is equal to or greater than a predetermined shading difference. The predetermined shading difference of the peak interval L between the first peak A and the second peak B in the shading histogram is, when the shading of the shading histogram is divided into 256 gradations, about γ gradation (for example, about 256 gradations). 15%). The reason for setting it to about 15% is that the image processing device 14
Considering the detection accuracy in image processing by, even if the same image is detected under the same lighting device conditions,
This is because the detection result includes an error of about 10% for 256 gradations. Peak interval L between first peak A and second peak B
Is the above-mentioned predetermined shade difference, an image with clear contrast and easy to recognize is obtained.

Here, the second peak B in the density histogram is a peak having an appearance frequency of 50% or more when the appearance frequency of the first peak A is 100%, and
A peak whose peak interval with respect to peak A is equal to or greater than γ gradation. In FIG. 9, two peaks having an appearance frequency of 50% or more with respect to the appearance frequency of the first peak A are two peaks B and C, and these peaks B and C are respectively different from the first peak A. The intervals are intervals L and M. By the way, since M <γ <L, in the case of the peak C, the first
Although it has an appearance frequency of 50% or more with respect to the appearance frequency of the peak A, the difference between the first peak A and the peak interval M is not more than γ gradation, so that it is inappropriate as the second peak.
On the other hand, in the case of the peak B, the appearance frequency and the shading difference both satisfy the above-described conditions, and are suitable as the second peak. In FIG. 9, for example, the first peak A corresponds to the image of the semiconductor pellet 21 in FIG. 3, and the second peak B corresponds to the image of the dicing line 22.

Since the creation judgment unit 15 of the control unit 17 analyzes the grayscale histogram as described above,
As shown in FIG. 6, when the density histogram is distributed to the dark side, it is determined that the illuminance level of the lighting device 20 is too dark, and as shown in FIG. 6, the density histogram is shifted to the light side. In this case, it is determined that the illuminance level of the illumination device 20 is too bright, and as shown in FIG. 7, when the interval between the peaks of the grayscale histogram is narrow, it is determined that the contrast of the image is low. As shown in (1), when the peak height of the grayscale histogram is low, it is determined that an image that is easy to recognize cannot be obtained. This creation determiner 15
As shown in FIG. 9, the gray-scale histogram
When all of the conditions (1) to (d) are satisfied, it is determined that the illuminance level of the illuminating device 20 exhibiting the density histogram is appropriate, and the illuminating device 20 is
Is adjusted to this proper illumination level.

Next, the operation of the illuminance determination device 10 of the lighting device will be described. The creation judging unit 15 of the control device 17 generates a gray-scale histogram based on an image captured by the camera 11 and image-processed by the image processing device 14 in a state where light is not emitted from the illumination device 20 via the illuminance adjuster 18. It is created and stored in the memory 16.

Next, the creation judging unit 15 includes an illuminance adjuster 18
To increase the illuminance level of the illuminating device 20 stepwise by illuminance levels at regular intervals up to the maximum illuminance of the illuminating device 20, and for each of these illuminance levels, the image is taken by the camera 11 and transmitted to the image processing device 14. The density histogram is sequentially created based on the image subjected to the image processing, and is stored in the memory 16.

The creation judging unit 15 selects, from among the density histograms stored in the memory 16, a density histogram satisfying all of the above-mentioned conditions (a) to (d), and adjusts the illuminance level presenting the density histogram to an appropriate level. Then, the illuminator 20 is set to the appropriate illuminance level by controlling the illuminance adjuster 18.

When a plurality of gray level histograms satisfying all of the conditions (a) to (d) are selected, an intermediate one of a plurality of illuminance levels of the illuminating device 20 exhibiting the selected plurality of gray level histograms is selected. May be determined to be optimal, and the illuminance level of the lighting device 20 may be set to the illuminance level.

According to the above embodiment, the following effects can be obtained. The control device 17 controls, for each illuminance level of the lighting device 20,
A density histogram is created for the image captured by the camera 11, and (a) the distribution center is within an allowable value (within a range of ± α gradation with respect to the median value T of the density), and (b) the distribution range is within a predetermined range. (The maximum value K _{max of} the gray value and the minimum value K _min are β
₁ is in ~β the range of ₂ gradations), (c) about the frequency of occurrence of the first (largest) peak A is the total number of pixels of the predetermined value (captured image
60%) or more, and (d) an illuminance level exhibiting a gray-scale histogram in which the peak interval L between the first peak A and the second peak B is equal to or greater than a predetermined gray-scale difference (gray scale). From the determination, the optimum illuminance level of the lighting device 20 can be quantitatively analyzed and determined. As a result, it is possible to eliminate individual differences in an appropriate illuminance level when the operator sets the optimum illuminance level of the lighting device 20 based on the senses and experience values, and it is possible to easily and accurately optimize the illuminance level of the lighting device 20. Therefore, the detection accuracy by the image processing device 14 can be stabilized.

The creation determining unit 15 of the control device 17 creates a density histogram with the illumination device 20 at an arbitrary illuminance level, and the density histogram is determined by the condition (a).
To (d) are satisfied, and if so, the illuminating device 20 is set to this illuminance level,
If not, the illuminance level of the lighting device 20 is changed in the increasing direction or the decreasing direction by a predetermined amount, and thereafter, the changing direction of the illuminance level is alternately switched, and the change amount is increased by a predetermined amount for each change. The generation and determination of the above-described gray-scale histogram may be repeated for each changed illuminance level, and the illumination device 20 may be set to the illuminance level of the gray-scale histogram that satisfies all of the above conditions (a) to (d).

In the above embodiment, (a)
It is determined that the illuminance level of the lighting device 20 that satisfies all of the conditions (a) to (d) is appropriate.
It is not necessary to satisfy all of the conditions (a) to (d). For example,
The illuminance level of the lighting device 20 may satisfy all of the conditions (a) to (c) or may satisfy at least one of the conditions (a) to (c). . Also in this case, it is possible to eliminate individual differences in an appropriate illuminance level that occurs when an operator sets the illuminance level of the lighting device 20 based on senses and experience values, and it is possible to easily and accurately optimize the illuminance level of the lighting device 20.

Further, the illuminance adjuster 18 is controlled based on the determination result of the creation determiner 15 to automatically adjust the illuminance level of the illumination device 20 to an appropriate illuminance level. The adjustment may be performed manually. That is, based on the determination result of the illuminance level of the illumination device 20 by the creation determiner 15, the operator operates the illuminance adjuster 18 to gradually adjust the illuminance level of the illumination device 20 to an appropriate illuminance level. May be.

Further, the present invention may be applied to a wire bonding apparatus of a semiconductor manufacturing apparatus, and may be applied to another apparatus other than the semiconductor manufacturing apparatus.

[0044]

As described above, according to the illuminance determination device for an illumination device according to the present invention, the illuminance level of the illumination device can be easily and reliably optimized.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a first embodiment of an illuminance determination device for an illumination device according to the present invention.

FIG. 2 is a front view showing a semiconductor wafer as an object;

FIG. 3 is a diagram showing an image of the semiconductor wafer of FIG. 2 taken by a camera;

FIG. 4 is a diagram illustrating coordinate axes of a grayscale histogram;

FIG. 5 is a graph showing a pattern I of a density histogram.

FIG. 6 is a graph showing a pattern II of a gray-scale histogram.

FIG. 7 is a graph showing a pattern III of a gray-scale histogram.

FIG. 8 is a graph showing a pattern IV of a gray-scale histogram.

FIG. 9 is a graph showing a pattern V of a gray-scale histogram.

[Explanation of symbols]

Reference Signs List 10 illuminance determination device of illumination device 11 camera (imaging device) 15 creation determination device 16 memory 17 control device 18 illuminance adjustment device 20 illumination device 21 semiconductor pellet (object) A first peak B second peak G distribution center of density histogram minimum gray value L peak interval in the distribution range of the maximum gray value K _min density histogram in the distribution range of K _MAX density histogram

Claims (6)

[Claims] An illuminance determination device for an illumination device that irradiates an object to be imaged with an imaging device with an illumination device, wherein a density histogram indicating a brightness distribution of an image captured by the imaging device is created. (C) comparing and examining at least one of the following, and determining that the illuminance of the illuminating device is appropriate when satisfied, the illuminance judging device for the illuminating device. (a) The distribution center of the density histogram is within a predetermined range. (b) The distribution range of the density histogram is within a predetermined range. (c) The maximum peak value in the density histogram exceeds a predetermined value. 2. The predetermined range related to the distribution center of gravity of the density histogram is defined by:
Approximately ± 10% of the number of gradations where the gradation of the gradation histogram is divided
The illuminance determination device of the lighting device according to claim 1, wherein 3. The predetermined range relating to the distribution range of the density histogram is defined as the difference between the maximum value and the minimum value in the distribution range being approximately the number of gradations into which the density of the density histogram is divided.
The illuminance determination device for an illumination device according to claim 1, wherein the illuminance is in a range of 50 to 70%. 4. The predetermined value relating to the maximum peak value of the density histogram is about 60% of the total number of pixels of the captured image.
The illuminance determination device for an illumination device according to claim 1, wherein: 5. An illuminance determination device for an illumination device for irradiating an object to be imaged by an imaging device with an illuminance, wherein the illuminance adjustment device capable of adjusting the illuminance by the illumination device, A shaded histogram is created, and the following (a) to (c) are compared and examined.A creation determiner that determines that the illuminance of the lighting device is appropriate when all are satisfied, and an output signal of the creation determination device. And a control device for controlling the illuminance adjusting device to adjust the illuminance of the illuminating device based on the illuminance adjusting device. (a) The distribution center of the density histogram is within a predetermined range. (b) The distribution range of the density histogram is within a predetermined range. (c) The maximum peak value in the density histogram exceeds a predetermined value. 6. An illuminance determination device for an illumination device that irradiates light to a semiconductor wafer imaged by an imaging device, comprising: an illuminance adjustment device capable of adjusting the illuminance of the illumination device; and a brightness distribution of an image captured by the imaging device. A shaded histogram is created, and the following (a) to (d) are compared and examined, and when all of them are satisfied, the illuminance of the lighting device is judged to be appropriate. And a control device for controlling the illuminance adjusting device to adjust the illuminance of the illuminating device based on the illuminance adjusting device. (a) The distribution center of the density histogram is within a predetermined range. (b) The distribution range of the density histogram is within a predetermined range. (c) The maximum peak value in the density histogram exceeds a predetermined value. The interval between the peak values corresponding to each image of the semiconductor pellet and the dicing line on the wafer is within a predetermined range.