JP4695535B2 - Image processing system having illumination device with brightness correction - Google Patents

Description

  The present invention relates to an image processing system that inspects an inspection object by processing imaging data of the inspection object that is illuminated by an illuminating device and is imaged by the imaging apparatus, and more particularly to the illumination device with brightness correction.

  Conventionally, there is known an image processing system that processes image data of an inspection object and inspects the inspection object. This system, as shown in FIG. The object M is imaged by the imaging device 2 such as a camera to obtain the image data of the inspection object M to obtain image data, and the image data is processed by the image processing device 3 to determine whether the inspection object M is good or bad. Determine. The illumination device 1 includes a light emitter 1a such as a light emitting diode (LED) or a halogen lamp, and an illumination power source 1b that supplies power to the light emitter 1a. Usually, the illumination device 1 is independent from the image processing device 3 independently. Is provided.

  By the way, as shown in FIG. 5, for example, LEDs generally have a tendency that the relative luminance decreases with the passage of lighting time. When the brightness decreases, the illumination becomes dark, which affects image processing. In this case, by appropriately increasing the power supply amount of the illumination power source 1b of the illumination device 1 by volume operation, the luminance of the light emitter 1a is increased to brighten the illumination.

  On the other hand, this reduction in luminance depends on the characteristics of the light emitter, drive current, lighting time, ambient temperature, humidity, and the like. It also varies depending on the variation of individual light emitters. In the lighting power source 1b for driving the light emitter 1a, the lighting time and drive current can be grasped with a counter or the like. However, the decrease in the luminance of the light emitter 1a varies greatly depending on the ambient temperature and humidity. It is difficult to accurately calculate the luminance of the light emitter 1a. On the other hand, in the image processing apparatus 3, a luminance distribution such as average luminance and maximum luminance can be obtained from the captured image. For example, when a defective product is mixed in the inspection object M or disturbance light enters temporarily. Since the luminance distribution changes depending on the state and environment of the inspection object M to be imaged, it is difficult to calculate the required accurate luminance of illumination only with the luminance distribution.

For this reason, conventionally, there has been known a method of increasing the current to the LED or increasing the sensitivity of the light receiving unit so that the luminance of the LED of the light projecting unit of the photoelectric sensor is monitored by the light receiving element and the reduced luminance is recovered. (For example, Patent Document 1). In general, an illuminating device for an image processing system often uses a large number of LEDs in order to ensure sufficient luminance of illumination (for example, Patent Document 2).
Japanese Examined Patent Publication No. 6-151221 JP 2002-207994 A

  However, in the prior art, for a large number of LEDs (light emitters) used in an image processing system, a large number of light-receiving elements for monitoring are required to accurately grasp the reduced luminance, and the component mounting area and cost are reduced. From the surface, there is a problem that it is difficult to put the luminance correction into practical use.

  The present invention provides an image processing system having an illumination device with brightness correction, which solves the above-described problems and can accurately grasp brightness reduction of a plurality of light emitters and facilitate appropriate brightness correction. It is aimed.

In order to achieve the above object, an image processing system having an illumination device with brightness correction according to the present invention includes a plurality of light emitters that illuminate an inspection object, and an illumination power source that supplies power to the light emitters. An image processing system comprising: an apparatus; an imaging apparatus that captures an image of an illuminated inspection object and acquires image data; and an image processing apparatus that processes the image data to inspect the inspection object. ,
The image processing apparatus includes a luminance correction unit that corrects the luminance of the light emitter, and the luminance correction unit displays luminance distribution information on an image for image data of an inspection object obtained using the illumination device. It has a luminance distribution information acquisition unit to acquire, and at the time of inspection of an inspection object, based on the luminance distribution information on the image, from the start of illumination use at the time of installation of the illumination device to the time of illumination use at the time of inspection It is determined whether or not the luminance decreasing tendency of the luminous body generated in the meantime is normal, and when it is determined normal, the illumination power source is controlled so as to recover the decreased luminance.
In addition, the luminance correction unit starts using the illumination based on a luminance reduction rate per hour of the luminous body obtained from luminance degradation conditions including characteristics of the luminous body, driving current, lighting time, ambient temperature, and humidity. A luminance range setting unit that sets a normal luminance reduction range of the light emitter from the time of use to the use of the illumination, and within the luminance reduction range in which the luminance reduction during the use of the illumination is set at the time of inspection of the inspection object When it is determined that the inspection object is good and the luminance distribution at the time of using the illumination is determined to be similar to the previously registered luminance distribution at the start of the use of the illumination. And a luminance decrease determination unit that determines that the luminance decrease tendency of the light emitter is normal.

According to this configuration, when inspecting the inspection object, based on the luminance distribution information on the image, a plurality of light emissions generated between the start of the use of illumination at the time of installation of the illumination device and the use of illumination at the time of the inspection It is determined whether or not the tendency of the body brightness to decrease is normal, and when it is determined to be normal, the lighting power supply is controlled so that the decreased brightness is restored. Therefore, it is possible to accurately grasp the decrease in luminance of the plurality of light emitters and easily perform appropriate luminance correction. In addition, since the luminance correction unit includes the luminance range setting unit and the luminance reduction determination unit, it is possible to more accurately grasp the luminance reduction of the light emitter when the current illumination is used.

  Preferably, the brightness correction unit further updates the brightness correction coefficient of the light emitter according to the brightness decrease when the illumination is used when it is determined that the brightness decrease tendency of the light emitter is normal. An update unit, and a correction control unit that controls the illumination power source to correct the luminance of the light emitter so that the luminance is increased by a luminance decrease based on the updated luminance correction coefficient. Therefore, it is possible to easily perform more appropriate correction with respect to a decrease in luminance of the plurality of light emitters.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an image processing system having an illumination device with brightness correction according to an embodiment of the present invention. The system includes a lighting device 1 having a plurality of (for example, 100) light emitters such as LEDs 1a that illuminate an inspection object M and an illumination power source 1b that supplies power to the LEDs 1a, and an inspection that is illuminated. An imaging apparatus 2 that is an image processing camera such as a CCD camera that captures an image of the object M and acquires image data, and an image processing apparatus 3 that processes the image data and inspects the inspection object M are provided. Yes. In this example, the illumination power source 1b is built in the image processing apparatus 3. However, the illumination power source 1b may be provided outside and controlled by the brightness correction unit 10 using communication means or the like.

  In addition to the illumination power supply 1b, the image processing apparatus 3 includes a luminance correction unit 10 that corrects the luminance of the LED 1a. Further, as shown in FIG. 2, an image input unit that inputs captured image data. 8 and an image processing determination unit 9 that processes the image data and determines the quality of the inspection object M.

  The luminance correction unit 10 in FIG. 2 includes a luminance distribution information acquisition unit 11 that acquires luminance distribution information on an image for the image data of the inspection object M obtained using the illumination device 1. This luminance distribution information is luminance distribution information acquired for the same inspection object from the start of illumination use at the time of installation of the illumination device 1 to the time of illumination use at the time of inspection. Based on the luminance distribution information when the illumination device 1 is applied to the inspection object M, the luminance of the LED 1a when using the illumination is obtained.

  When inspecting the inspection object M using the illumination device 1, the brightness correction unit 10 starts using the illumination at the time of installation of the illumination device 1 based on the brightness distribution information on the image (the usage progress of the LED 1 a). It is determined whether or not the luminance decreasing tendency that has occurred between time 0) and when the illumination is used at the time of inspection is normal, and when it is determined that the luminance is normal, the illumination power source is restored. 1b is controlled. In this example, the luminance of the plurality of LEDs 1a is entirely corrected based on the luminance distribution of the entire image on the inspection object M.

  In addition to using the image input unit 8 and the image processing determination unit 9, the luminance correction unit 10 includes a luminance range setting unit 12, a luminance decrease determination unit 14, a luminance correction coefficient update unit 19, and a correction control unit 20. .

  The brightness range setting unit 12 is a setting unit 21 that sets characteristics based on the ambient environment (temperature, humidity) and the model of the LED 1a, and a light emitter drive calculation unit 22 that calculates the drive current by integrating the lighting time of the LED 1a. And a luminous body drive memory 23 for storing the accumulated lighting time of the LED 1a and the calculated drive current. The luminance range setting unit 12 determines the current illumination from the start of illumination use based on the luminance reduction rate per hour of the LED 1a obtained from the luminance reduction conditions including the LED 1a characteristics, drive current, lighting time and ambient temperature, and humidity. Set the normal brightness reduction range until use. Although the ambient temperature and humidity change from moment to moment, the LED 1a decreases in luminance every year, so in this example, an average value for the year is set. FIG. 3 shows an example of the set normal luminance reduction range. In this example, the normal luminance reduction range R shows a slight spread over time. This corresponds to the fact that the variation in luminance decrease gradually increases with time.

  The luminance reduction determination unit 14 includes a luminance reduction range determination unit 15, a use start luminance distribution storage unit 16, a similar distribution determination unit 17, and a normality determination unit 18. In the image processing system, normally, it is necessary to register a non-defective inspection object M at the start (introduction) of illumination use of the illuminating device 1 at the time of installation of the system. At the same time, the luminance distribution at the start of lighting use (introduction) for the non-defective product acquired by the luminance distribution information acquisition unit 11 is stored (saved).

  When the inspection target M is determined by the image processing determination unit 9, the luminance reduction range determination unit 15 is based on the luminance distribution information on the image from the luminance distribution information acquisition unit 11 and is currently in use. It is determined whether or not the luminance at is within the luminance reduction range set by the luminance range setting unit 12. For example, when the ambient temperature or humidity is low, the luminance reduction range is a range in which the luminance reduction is small. Further, since the LED 1a has a characteristic that when the driving current is increased, the lifetime is shortened and the luminance is decreased, the luminance decreasing range is accordingly set to a range in which the luminance is further decreased. The similarity distribution determination unit 17 is similar to the luminance distribution at the start of use registered in advance in the use start luminance distribution storage unit 16 in the luminance distribution at the time of using the current illumination. It is determined whether or not many common points are found in the luminance distribution state for each area of the image.

  In the luminance reduction determination unit 14, (a) the luminance reduction range determination unit 15 determines that the luminance when the current illumination is used is within the luminance reduction range, and (b) the image processing determination unit 9 performs the inspection. The object M is determined to be good (OK), and (c) the similarity distribution determination unit 17 determines that the luminance distribution at the time of using the current illumination is similar to the luminance distribution at the start of the use of the illumination. Sometimes, the normality determination unit (AND logic unit) 18 determines that the tendency of the LED 1a to decrease in luminance is normal. When all the three conditions (a) to (c) are satisfied, it is determined that the luminance decreasing tendency of the LED 1a is normal, and when even one condition is not satisfied, it is determined abnormal. The condition that the inspection object M is determined to be good by the image processing apparatus 3 is that the inspection object M is mixed with a defective product or the ambient light temporarily enters when the luminance distribution changes greatly. In this case, since it is usually determined to be defective, this good determination is used as a condition.

  The brightness correction coefficient updating unit 19 updates the brightness correction coefficient of the LED 1a according to the brightness decrease when the current illumination is used when it is determined that the tendency of the LED 1a to decrease in brightness is normal. For example, when the luminance drop is 1 / (1.1) from the start of lighting use of the lighting device 1 to the current lighting use, the luminance correction coefficient is updated to 1.1 accordingly. When it is determined that the luminance decreasing tendency of the LED 1a is abnormal, the luminance correction coefficient is not updated.

  The correction control unit 20 is based on a luminance designation unit 24 that gives a designated value of illumination luminance, a correction coefficient addition unit 25 that adds the luminance correction coefficient to the luminance designation value, and a luminance designation value in which the luminance correction coefficient is added. The drive current calculation unit 26 that calculates the drive current of the illumination power supply 1b and the drive current upper limit check unit 27 that checks the calculated drive current rating are provided. Based on the brightness correction coefficient updated by the brightness correction coefficient update unit 19, the correction control unit 20 controls to increase the drive current of the illumination power supply 1b in order to increase the brightness by the brightness decrease of the LED 1a. Then, the brightness of the LED 1a is corrected. In the drive current upper limit check unit 27, if the corrected drive current of the LED 1a exceeds the rating, for example, a warning is generated to notify the replacement with a new LED 1a.

  An example of the operation of the luminance correction unit 10 having the above configuration will be described below with reference to FIG. First, when the image processing determination unit 9 determines the quality of the inspection object M, the luminance reduction determination unit 14 determines the luminance reduction range determination unit based on the luminance distribution information on the image from the luminance distribution information acquisition unit 11. 15, it is determined that the luminance when the current illumination is used is within the luminance reduction range set by the luminance range setting unit 12, the image processing determination unit 9 determines that the inspection object M is good, and When it is determined by the similar distribution determination unit 17 that the luminance distribution at the time of using the current illumination is similar to the luminance distribution at the start of use registered in advance in the luminance distribution storage unit 16 at the start of use. The normality determination unit 18 determines that the tendency of the luminance decrease of the LED 1a is normal. If it is determined that the luminance decrease tendency is normal, the luminance correction coefficient update unit 19 then updates the luminance correction coefficient of the LED 1a to 1.1, for example, according to the luminance decrease when the current illumination is used.

  When the luminance reduction determination unit 14 determines that the luminance reduction tendency of the LED 1a is abnormal, the luminance correction coefficient is not updated. For example, when strong gloss appears in a part of the image due to disturbance light, the image processing determination unit 9 is defective and the luminance distribution is collapsed, so that the luminance reduction range determination unit 15 is out of the luminance reduction range, and the similarity distribution determination unit 17 Since it is determined that the luminance distribution corresponds to at least one of dissimilarities and the luminance decreasing tendency is determined to be abnormal, the luminance correction coefficient is not updated. In addition, when the determination result of the image processing determination unit 9 is not good, there is a possibility that an object different from the inspection object M has been picked up. In this case, the luminance correction coefficient is not updated. Furthermore, when the luminance distribution is brighter than when the use is started, it is considered that this is temporarily brightened by disturbance light, or the LED 1a is replaced with a new one. Even in such a case, the luminance correction coefficient is not updated.

  Based on the brightness correction coefficient updated by the brightness correction coefficient update unit 19, the correction control unit 20 controls the drive current of the illumination power source 1b to increase in order to increase the brightness by the brightness decrease. The brightness of the LED 1a is corrected. When the above-described brightness correction coefficient is updated to 1.1, the drive current supplied from the illumination power supply 1b to the LED 1a is multiplied by 1.1 to increase the brightness of the LED 1a. In the next inspection, the LED 1a illuminates the inspection object M with the corrected luminance, so that sufficient brightness is ensured.

  Thus, when determining the quality of the inspection object, the luminance of the plurality of LEDs 1a generated between the start of use of the illumination when the lighting device 1 is installed and the use of the illumination at the time of determination based on the luminance distribution information on the image. When the lighting power supply 1b is controlled so as to restore the reduced brightness when it is determined that the brightness is normal, it is possible to accurately reduce the brightness of the LED 1a when the current lighting is used. Since it can grasp | ascertain, the brightness | luminance fall of several LED1a can be grasped | ascertained correctly and appropriate brightness correction can be performed easily.

  In this embodiment, the LED (light emitting diode) 1a is used as the light emitter, but the present invention is not limited to this, and a halogen lamp, a high pressure discharge lamp, or the like may be used.

  In this embodiment, the brightness of the plurality of LEDs 1a is corrected as a whole based on the brightness distribution of the entire image in the inspection object M, but each area is determined based on the brightness distribution for each area of the image. You may make it correct | amend partially the brightness | luminance of several LED1a for every.

1 is a block diagram illustrating an image processing system according to an embodiment of the present invention. It is a block diagram which shows the brightness | luminance correction | amendment part of FIG. It is a characteristic view which shows an example of a normal luminance fall range. It is a block diagram which shows the conventional image processing system. It is a characteristic view which shows an example of the luminance characteristic of LED.

Explanation of symbols

1: Lighting device 1a: Light emitter (LED)
1b: power supply for illumination 2: imaging device 3: image processing device 9: image processing determination unit 10: luminance correction unit 12: luminance range setting unit 14: luminance reduction determination unit 19: luminance correction coefficient update unit 20: correction control unit M : Inspection object

Claims (2)

An illumination device having a plurality of light emitters that illuminate an inspection object and an illumination power source that supplies electric power to the light emitter; an imaging device that images the inspection object illuminated and obtains image data; An image processing system comprising an image processing device that processes the image data and inspects an inspection object,
The image processing apparatus includes a luminance correction unit that corrects the luminance of the light emitter.
The brightness correction unit
For the image data of the inspection object obtained using the illumination device, it has a luminance distribution information acquisition unit for acquiring luminance distribution information on the image,
When the inspection object is inspected, based on the luminance distribution information on the image, a decrease in luminance of the illuminant that occurs between the start of illumination use at the time of installation of the illumination device and the use of illumination at the time of inspection. tendency to determine normal or not, when it is determined to be normal, so to restore the brightness and the decrease, which controls the lighting power source,
Based on the luminance reduction rate per hour of the luminous body obtained from the luminance reduction conditions including the characteristics of the luminous body, driving current, lighting time and ambient temperature, and humidity, from the start of use of the illumination to the time of use of the illumination. A luminance range setting unit for setting a normal luminance reduction range of the luminous body;
At the time of inspection of the inspection object, it is determined that the luminance reduction when using the illumination is within the set luminance reduction range, the inspection object is determined to be good, and the luminance distribution when using the illumination is A luminance decrease determination unit that determines that the luminance decrease tendency of the light emitter is normal when it is determined that the luminance distribution at the start of use of the illumination registered in advance is similar to the luminance distribution;
An image processing system having an illumination device with brightness correction. In claim 1 ,
The brightness correction unit further includes:
A brightness correction coefficient updating unit that updates the brightness correction coefficient of the light emitter in accordance with the brightness decrease when the illumination is used when it is determined that the brightness decrease tendency of the light emitter is normal;
Based on the updated luminance correction coefficient, a correction control unit that controls the illumination power source and corrects the luminance of the light emitter so that the luminance is increased by a luminance decrease, and
An image processing system having an illumination device with brightness correction.

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