JP3409108B2 - Full color photoelectric sensor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a full-color photoelectric sensor that determines the color of an object based on the difference in the optical characteristics of the detected object, and more particularly to a full-color photoelectric sensor having a function of preventing chattering.

[0002]

2. Description of the Related Art A full-color photoelectric sensor has been known as a sensor for determining the color of a detected object. FIG. 1 shows an example of a conventional full-color photoelectric sensor. The full-color photoelectric sensor 101 projects light of three primary colors of red (R), green (G), and blue (B) from a light projecting unit 102 in a time-division manner, and reflects light from a detection object at each timing. The light receiving unit 103 receives light, and the light receiving signal output from the light receiving unit 103 is processed by the microcomputer unit 104 to determine the color of the detected object. External input section 1
Reference numeral 05 denotes an input from the outside such as a switch or an external input signal, and outputs it to the microcomputer unit 104. The external output unit 106 outputs the measurement result and the like to an external device such as a PC under the control of the microcomputer unit 104.

Next, a conventional full-color photoelectric sensor 101
The processing of the color discrimination operation performed by the microcomputer section 104 will be described with reference to the flowchart of FIG. 2 and the schematic diagram of the threshold setting level of FIG. In this process, first, a registration process is performed for a detected object of a reference color to be extracted (referred to as teaching) (S1). In this registration, light of different wavelengths is time-divisionally projected onto a reference color detection object, and the following evaluation values (each wavelength) are based on the received light amounts R, G, and B for each light. The ratio of the amount of received light to the total amount of received light) is calculated, and the calculated value is stored. The stored value is used as the registered value. R component evaluation value: R / (R + G + B) G component evaluation value: G / (R + G + B) B component evaluation value: B / (R + G + B)

Next, based on this registered value, a range (permissible difference) of evaluation values regarded as the same color is set (S2). At the time of inspection, similarly to S1, the R, G, and B lights are projected and received on the target detection object (S3), the evaluation values are calculated, and all the R, G, and B evaluation values are calculated. If it is within the range set in S2, it is determined to be the same color, and if it is outside the range, it is determined to be a different color, and the result is output (S4). Next, when changing the detected object, the teaching process is required again (YES in S5), and thus the process proceeds to S1 to perform teaching. On the other hand, if the inspection is continued without changing the detected object (N in S5
O), and returns to S3.

In the full-color photoelectric sensor 101, when setting the range of evaluation values (same color range) that are regarded as the same color,
A hysteresis width for preventing chattering (malfunction) is set in consideration of the influence of noise components in the received light signal. When it is determined that there is no detected object from the state where the sensor 101 has determined that there is a detected object (ON state), detection is performed using the threshold values TH1 (OFF) and TH2 (OFF). On the other hand, when it is determined that there is a detected object from the state in which it is determined that there is no detected object (OFF state), detection is performed using the threshold values of TH1 (ON) and TH2 (ON). This hysteresis width is determined by a noise width determined by hardware such as gain setting of the light receiving circuit amplifier, and is a constant value unless the hardware setting of the amplifier or the like changes.

[0006]

However, in such a conventional full-color photoelectric sensor device 101, since evaluation is performed using a constant hysteresis width during inspection,
If the amount of light received during inspection is small and the influence of noise on the evaluation value is large, chattering is likely to occur. For example, R,
The amount of received light of G and B consists of signal components R ', G', B'and noise components r, g, b (the maximum value is constant depending on the hardware), so the R component evaluation value is (R '+ r ) / (R '+ G' + B '+ r + g + b). Here, the signal components R ′, G ′,
When B ′ is sufficiently larger than the noise components r, g, and b, the influence of noise on the evaluation value is small, but when the signal component is small, the influence of noise is large and chattering is likely to occur. . Therefore, for example, in the case of detecting a black-colored detection object having a low reflectance, the amount of received light becomes small, and the influence of noise on the evaluation value becomes large, so there is a problem that chattering easily occurs.
Further, even when the detection distance fluctuates and the amount of received light decreases, similarly, the influence of noise on the evaluation value increases, and thus there is a problem that chattering easily occurs.

The present invention has been made in order to solve the above-mentioned problems, and in a sensor device for discriminating the color of a detected object by using at least two light sources having different wavelengths from each other, the sensor device projects at the time of inspection. Each time the light receiving process is performed, the hysteresis width with respect to the evaluation value is calculated, and by performing color determination using the value, even when detecting a detection object with low reflectance, or when the detection distance varies, An object of the present invention is to provide a full-color photoelectric sensor capable of preventing chattering.

[0008]

In order to achieve the above object, the present invention provides a full-color photoelectric sensor for discriminating the color of a detection object, comprising at least two light sources for projecting lights having different wavelengths. , A light projecting means for projecting each light in a time-division manner and a light reflected or transmitted by a detection object of the light projected from the light projecting means, and received in accordance with the optical characteristics of reflection or transmission of the detection object. A light receiving means for outputting a signal,
Evaluation value calculation means for calculating an evaluation value from the received light signal, evaluation value storage means for storing the evaluation value obtained by the evaluation value calculation means for the reference color detection object, and each time the received light signal is obtained at the time of inspection In addition, the threshold value is set based on the hysteresis width calculation means for calculating the hysteresis width for the evaluation value from the evaluation value calculation means, and the hysteresis width and the evaluation value stored in the evaluation value storage means. A value setting means, a comparison means for comparing the evaluation value from the evaluation value calculation means at the time of inspection with a threshold value, and a determination means for performing color determination based on the comparison result from the comparison means. is there.

In this structure, the hysteresis width for the detected object is calculated by the hysteresis width calculation means for each light projection and reception, and the determination processing is performed using the calculated value, so that the reflectance is low and the amount of light received by the light reception means is small. Even when an object is detected, the inspection is performed with a hysteresis width suitable for the detected object, so that chattering can be prevented. Further, even when the amount of received light is reduced due to variation in the detection distance, chattering can be prevented in the same manner.

Further, the present invention may further include an error information output means for outputting error information to the outside of the sensor when the hysteresis width is equal to or larger than a certain width in the above structure. In this configuration, the hysteresis width for the target detection object is checked, and if it is more than a certain width, error information indicating that it cannot be detected is output to the outside of the sensor, so the set detection distance It can be easily judged whether or not it can be detected.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 4 is a block diagram showing the configuration of the optical sensor according to the embodiment of the present invention. The optical sensor 1 is a device that projects light of the three primary colors of red, green, and blue in a time-division manner, and detects the color of the detection object 2 from the intensity of reflected light from the detection object 2 at each timing. . In the figure, three LEDs 3a, 3b, 3c (light sources) have different wavelengths of light (red: λ = 680 nm, green: λ =).
565 nm, blue: λ = 450 nm) is emitted according to an instruction from the light projecting circuit 4 (light projecting means), and the light is irradiated toward the detection object 2. The light reflected by the detection object 2 is received by the light receiving element 5 and converted into a light receiving signal by the light receiving circuit 6 (light receiving means). This received light signal is discriminated by the R, G, B discrimination circuit 7 into signals for light of respective wavelengths. The R, G, B discriminating circuit 7 and the light projecting circuit 4 described above are driven based on the oscillation pulse signal supplied from the pulse signal generating circuit 8, and the R, G, B
The R, G, and B signals output from the B discrimination circuit 7 are sampled and held by the sample and hold circuit 9.

The R, G, and B signals sample-held by the sample-hold circuit 9 are evaluated value calculation circuit 1
0 (evaluation value calculation means), the evaluation value is calculated, and when the mode change switch 11 is in the teaching mode for performing the registration processing for the detection object 2 of the color to be extracted, the evaluation value storage circuit 12 (evaluation value storage) Means) and stored. On the other hand, when the mode changeover switch 11 is in the inspection mode, the signal from the sample hold circuit 9 and the noise component stored in the noise storage circuit 13 for storing the noise component in the received light signal are obtained every time the received light signal is obtained. From the maximum value to the hysteresis width setting circuit 14
The (hysteresis width calculating means) calculates the hysteresis width. This hysteresis width and evaluation value storage circuit 12
From the evaluation value stored in the threshold value setting circuit 15
A threshold value is set in the (threshold value setting means) and the same color range is set. Each time the threshold value and the received light signal are obtained, the evaluation value obtained from the evaluation value calculation circuit 10 is compared in the comparison circuit 16 (comparison means), and in the judgment circuit (judgment means) 17 it is judged whether or not they are in the same color range. It is determined and the result is output from the output circuit 18. Further, when the hysteresis width is set in the hysteresis width setting circuit 14, the value is sent to the hysteresis width check circuit 19 (error information output circuit), and when the width is equal to or larger than a predetermined value, an error signal is output. .

The hysteresis width for the R, G, B component evaluation values by the hysteresis width setting circuit 14 of the photoelectric sensor 1 is calculated by the following arithmetic expression, and the judgment is made based on this hysteresis width (hysteresis in FIG. 3). The width depends on the measurement target). Hr = rr / (R + G + B-rr-gg-bb) Hg = gg / (R + G + B-rr-gg-bb) Hb = bb / (R + G + B-rr-gg-bb) Here, Hr, Hg, Hb: each component. Hysteresis widths for evaluation values R, G, B: signal components rr, gg, bb: maximum values of noise components for each received light amount.

FIG. 5 is a flow chart showing the processing of the color discrimination operation of the full-color photoelectric sensor according to this embodiment. In this process, first, the mode changeover switch 11 is set to the teaching mode, and the detection object 2 to be extracted by teaching is registered (S1). This registration is performed by the three LEDs 3a, 3b,
Light having a different wavelength from 3c is time-divisionally projected, an evaluation value is calculated based on the received light amounts R, G, and B for each light, and the value (registered value) is stored. Next, based on this registered value, a range (permissible difference) of evaluation values regarded as the same color is set (S2). When the mode changeover switch 11 is switched to enter the inspection mode, the light emitting / receiving process is performed (S3), and the hysteresis width setting circuit 14 sets the hysteresis width (S3-1). The calculated hysteresis width is checked by the hysteresis width check circuit 19 (S3-2). If the hysteresis width is less than or equal to a predetermined value, it is determined that detection is possible and color determination is performed (S4). Next, if the detected object 2 is changed, the teaching process is required again (YES in S5).
S) and S1 to perform teaching. On the other hand, if the inspection is continued without changing the detected object 2 (NO in S5), S3
Return to.

In the conventional photoelectric sensor 101, since the hysteresis width has a constant value, chattering may occur when the amount of received light becomes small. However, the full-color photoelectric sensor 1 according to the present embodiment performs light emitting and receiving processing. The hysteresis width is calculated each time the measurement is performed, and the determination is performed based on the threshold value obtained based on the hysteresis width. Therefore, even when the detection object 2 having a low reflectance and a small amount of received light is detected, the detection object is detected. Since color determination can be performed with a hysteresis width suitable for 2, chattering can be prevented. Even when the amount of received light decreases due to the variation in the detection distance, the hysteresis width is calculated each time the light emitting / receiving process is performed, so that chattering can be prevented.

The present invention is not limited to the above embodiment, but various modifications can be made. In the detection method described above, the detection is performed by the reflected light from the detection object 2. However, when the detection object 2 is formed of a transparent material such as transparent glass, a transparent PET bottle or a transparent bottle, The detection may be performed by these transmitted lights.

[0017]

As described above, according to the full-color photoelectric sensor of the present invention, the hysteresis width calculation means calculates the hysteresis width each time the light emitting / receiving processing is performed, and the judgment processing is performed using this value. Even when a detection object having a low reflectance and a small amount of received light is detected, the detection can be performed with a hysteresis width suitable for the detection object, and thus chattering can be prevented. Further, even when the amount of received light is reduced due to the distance variation, the hysteresis width varies, so that chattering can be prevented. Further, according to the full-color photoelectric sensor of the present invention, the hysteresis width obtained each time the light emitting / receiving process is performed in the above configuration is chucked, and error information is output if the hysteresis width is equal to or more than a certain width, thereby setting the set detection distance. It is possible to easily judge whether or not it can be detected by.

[Brief description of drawings]

FIG. 1 is a block diagram showing a processing system of a conventional full-color photoelectric sensor.

FIG. 2 is a flowchart showing a process of a color discrimination operation of a conventional full-color photoelectric sensor.

FIG. 3 is a schematic diagram of setting levels of threshold values with respect to evaluation values.

FIG. 4 is a block diagram showing a configuration of a full-color photoelectric sensor according to an embodiment of the present invention.

FIG. 5 is a flowchart showing a process of a color discrimination operation of the full-color photoelectric sensor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Full-color photoelectric sensor 2 Detecting objects 3a, 3b, 3c LED (light source) 4 Light emitting circuit (light emitting means) 5 Light receiving element (light receiving means) 6 Light receiving circuit (light receiving means) 10 Evaluation value calculation circuit (evaluation value calculation means) 12 evaluation value storage circuit (evaluation value storage means) 14 hysteresis width setting circuit (hysteresis width setting means) 15 threshold value setting circuit (threshold value setting means) 16 comparison circuit (comparison means) 17 determination circuit (determination means) 19 Hysteresis width check circuit (error information output means)

Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01J 3/00-3/52 G01V 8/00-8/26 G01N 21/00-21/61 JISST file (JOIS) WPI (DIALOG)

Claims (2)

(57) [Claims] 1. A full-color photoelectric sensor for discriminating a color of a detection object, comprising at least two light sources for projecting lights having different wavelengths, and projecting means for projecting each light in a time division manner, A light receiving unit that receives reflected light or transmitted light of the detection object of the light projected from the light projecting unit, and outputs a light reception signal according to the optical characteristics of the reflection or transmission of the detection object, and an evaluation value is calculated from the light reception signal. And an evaluation value storage unit for storing an evaluation value obtained by the evaluation value calculation unit for a reference color detection object, and an evaluation value calculation unit each time the light reception signal is obtained during inspection. Hysteresis width calculation means for calculating a hysteresis width for the evaluation value from the calculation means, the hysteresis width, and the threshold value is set based on the evaluation value stored in the evaluation value storage means. Threshold value setting means, comparing means for comparing the evaluation value from the evaluation value calculating means at the time of inspection with the threshold value, and judging means for performing color judgment based on the comparison result from the comparing means. And a full-color photoelectric sensor. 2. The full-color photoelectric sensor according to claim 1, further comprising error information output means for outputting error information to the outside of the sensor when the hysteresis width is a predetermined width or more.