JPH0579928B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a color sensor capable of determining the hue of an object by irradiating the object with colored light and detecting reflected light from the object. Conventionally, in order to extract a specific item from among a large number of different items or to classify each item, a method of identifying each item by color has been widely used. . For example, if we consider a manufacturing line where a variety of finished products coexist, each finished product has a unique hue, such as a color mark or the color of the finished product itself. By detecting such hue portions, each finished product can be distinguished and classified. By the way, in cases such as on a production line where a huge number of items must be distinguished and classified, it is not preferable to do it manually, especially when the hue portion to be detected is very small. , is virtually impossible. Therefore, a method is usually adopted in which a color sensor is used to automatically determine the hue. FIG. 1 is a configuration diagram showing an example of a conventional color sensor, in which 1 is a light emitting element, 2 and 3 are optical fiber transmission lines, 2a is an output section, 3a is an input section, 4 is an object to be inspected, and 5 is an optical fiber transmission line. In the light receiving section, 6 is an amplifier, and 7 is a comparator. Next, the operation of this prior art will be explained. In FIG. 1, a light emitting element 1 is a monochromatic light source and emits, for example, red light. This red light passes through an optical fiber transmission line 2 made up of a plurality of optical fibers bundled together, and passes through an optical fiber transmission line 2 that is colored by the object 4 to be inspected.
Alternatively, a portion having a unique color (hereinafter referred to as an object) is irradiated. When this object has a hue consisting of a red component such as red or yellow, it reflects red light, and this reflected light passes through the optical fiber transmission line 3 made up of a plurality of optical fibers bundled together and passes through the light receiving section. The light is received at 5. The light receiving section 5 is composed of a light receiving element such as a phototransistor, for example, and generates an analog signal a by receiving red light reflected from an object. The amount of received red light varies depending on the red component contained in the hue of the object, and the amplitude of the analog signal a varies depending on this amount of light. For example, when the hue of the object is red, the amplitude of the analog signal a is large, but when the hue of the object is yellow, the amplitude of the analog signal a is small. Further, if the hue of the object does not include a red component, for example, if it is green, the light receiving section 5 does not receive light, so the amplitude of the analog signal a becomes zero. Analog signal a from light receiving section 5 is amplified by amplifier 6 and supplied to comparator 7. A predetermined reference level is set in the comparator 7, and the input analog signal is compared with this reference level, and when the amplitude is equal to or higher than the reference level, it becomes a high level (hereinafter referred to as "1").
), when it is below the reference level, it is low level (hereinafter referred to as
It is converted into a digital signal b, which is referred to as "0"). The reference level of the comparator 7 can be set according to the hue judgment standard. For example, when the hues of red, yellow, and green are targeted, hue judgment is performed to distinguish red from other hues. For example, the reference level is set high, and for hue determination such as distinguishing red and yellow from green, the reference level is set low. Therefore, the hue of the object can be known from the level of the digital signal b. In this conventional technology, since the area of the output part 2a on the side of the object to be inspected 4 of the optical fiber transmission line 2 can be made extremely small, by providing the output part close to the object to be inspected 4, the output part 2a can be made very small. It is possible to reduce the light spot of the red light emitted from the optical fiber transmission line 3 on the object 4 to be inspected.
By positioning the entrance section 3a on the side of the inspected object 4 so that only the red light reflected by the inspected object 4 is incident, the hue of a minute object of the inspected object 4 can be determined. . However, in this conventional color sensor, hue determination is determined by the type of light emitting element 1, and moreover, only two types of hue can be determined. For example, in FIG. 1, if the light-emitting element 1 is a light-emitting diode that emits red light, the color sensor detects whether the hue of the object to be inspected 4 is red or if it does not contain a red component. It is only possible to determine whether the hue is . By the way, when distinguishing and classifying articles using hue determination, it is desirable to be able to perform three or more types of hue determination. Therefore, in order to determine various hues using a color sensor as shown in FIG. A method was used to judge the hue of objects. For example, if the hue of the object is red, green,
If it is yellow or any of the other four colors, first,
The light-emitting element 1 is a light-emitting diode that emits red light, and the hue of all objects is determined and divided into two groups. Next, the light-emitting element 1 is replaced with a light-emitting diode that emits green light, and each object is divided into two groups. The hue is determined for each group, and each group is further divided into two groups, so that the object is divided into the four colors described above. In this method, hue determination must be repeated for the number of light emitting elements 1 to be replaced, which requires time and effort, making real-time hue determination impossible. Each time it is replaced, it is necessary to adjust the reference level of the comparator for converting the analog signal from the light receiving section into a digital signal, and furthermore,
This adjustment requires great precision. Another conventional method is to use a plurality of color sensors, each of which is equipped with a different light emitting diode. Taking as an example the hue judgment of an object for the four colors mentioned above, a color sensor equipped with a light emitting diode that emits red light and a color sensor equipped with a light emitting diode that emits green light are used to determine the hue of the object. The determination is made by first irradiating the object with red light, and then by irradiating the same object with green light. With this method, each color sensor can be placed along the flow of the inspection object on the production line, etc., and hue judgment can be made, so there is no need to replace light emitting diodes or make adjustments for each replacement. This reduces the time required for judgment. However, on the other hand, it requires a plurality of color sensors, and furthermore, variations in characteristics among the color sensors greatly affect hue determination. For example, the reference level of a comparator for converting an analog signal from a light receiving section into a digital signal must be set to a predetermined value for each color sensor, but there are variations in the characteristics of the light emitting diode, light receiving section, etc. If so, it becomes very difficult to adjust the reference level. Furthermore, since light-emitting elements such as light-emitting diodes have relatively sharp emission directional characteristics, in such conventional color sensors, in order to efficiently input colored light from such light-emitting elements into the optical fiber transmission path, Extremely high precision is required in the arrangement of the light emitting elements. The purpose of the present invention is to eliminate the drawbacks of the above-mentioned prior art,
It is possible to determine various hues in real time by using a plurality of light emitting elements with different emission wavelengths, it is possible to reduce the placement accuracy of the light emitting elements having emission directional characteristics, and moreover, it is possible to efficiently transmit colored light to an optical fiber transmission path. An object of the present invention is to provide a color sensor that allows light to enter. In order to achieve this object, the present invention is characterized in that a light diffusion means is provided, the color light from the light emitting element is diffused by the light diffusion means, and the diffused color light is made to enter the optical fiber transmission line. shall be. By irradiating the same object with a plurality of different colored lights and detecting the colored lights reflected by the object, it is possible to determine the hue of a wide variety of objects in real time. However, in order to generate a plurality of colored lights in this way, a plurality of light emitting elements that emit different colored lights are required. These light-emitting elements are naturally arranged at different spatial positions, but since each light-emitting element has relatively sharp emission directional characteristics, the beam-shaped colored light from each light-emitting element In order for the light to enter the optical fiber transmission line accurately, extremely high precision is required in the arrangement of each light emitting element with respect to the entrance surface of the optical fiber transmission line. However, if the light emission directivity characteristics of the light emitting elements can be made gentler, the accuracy of arrangement of each light emitting element can be relaxed. The present invention has been made in view of this point. Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a configuration diagram showing an embodiment of a color sensor according to the present invention, in which 1a and 1b are light emitting elements,
8 is an optical fiber transmission line, 8a is an input/output section, 9, 1
0 is an optical fiber group, 9a is an input section, 10a is an output section, 11 is a light emitting section, 12 is a light diffusion plate, 13 is a time division drive circuit, 14 is a timing signal generation circuit, 1
5, 16 are D-type flip-flops, 17, 18,
19 and 20 are AND gates, and parts corresponding to those in FIG. 1 are given the same reference numerals. FIG. 3 is a waveform diagram showing signals at various parts in FIG. 2, and signals corresponding to those in FIG. 2 are given the same symbols. In FIG. 2, the optical fiber groups 9 and 10 are
Each consists of a plurality of optical fiber strands. The optical fibers forming the optical fiber group 9 are bundled together and their ends form the entrance section 9a, and the end surfaces of the optical fibers forming the entrance section 9a serve as entrance ports, respectively, to the light emitting section 11. Inject colored light generated by The optical fiber strands forming the optical fiber group 10 are also bundled together so that the end portions form the output section 10a, and the end surfaces of the optical fiber strands forming the output section 10a respectively serve as output ports to form the inspection object 4. The light reflected from the target object is emitted to the light emitting unit 5. Further, all of the optical fiber wires forming the optical fiber groups 9 and 10 are bundled together, and the ends thereof form the entrance/exit part 8a. Input/output section 8a
The end faces of the optical fibers are composed of the end faces of the optical fiber elements forming the optical fiber group 9 and the end faces of the optical fiber elements forming the optical fiber group 10, which are arranged in a uniform distribution with respect to each other, forming the optical fiber group 9. The end face of the optical fiber serves as an exit port through which the colored light generated by the light emitting section 11 is emitted to irradiate the target object of the inspection object 4, and also serves as an exit port for emitting the colored light generated by the light emitting section 11 to irradiate the target object of the optical fiber group 10. This serves as an entrance for reflected light. As described above, the optical fiber transmission line 8 is composed of a plurality of optical fibers, and the input section 9
The colored light incident from the end face of a is emitted from the end face of the entrance/exit portion 8a and is irradiated onto the object of the inspection object 4, and the colored light reflected from the object is emitted from the end face of the entrance/exit portion 8a.
The light enters from the end surface of the light emitting section 10a, exits from the end surface of the light emitting section 10a, and is received by the light receiving section 5. The light receiving section 5 generates an analog signal corresponding to the amount of the received colored light. Therefore, the output ports of the optical fibers of the optical fiber group 9 and the input ports of the optical fibers of the optical fiber group 10, which form the end face of the input/output section 8a, are arranged uniformly within a common plane area. Since it has been
Colored light is emitted uniformly over the entire end face of the entrance/exit section 8a, and by placing the entrance/exit section 8a very close to the object 4 to be inspected, the intensity distribution of the reflected light from the object 4 is adjusted to the entrance/exit direction. The reflected light is uniform over the entire end surface of the portion 8a, and almost all of this reflected light is irradiated onto the end surface of the entrance/exit portion 8a. Therefore, the colored light reflected by the object is
The reflected light is efficiently incident on the end face of the input/output section 8a of the optical fiber transmission line 8, and the reflected light is received by the light receiving section 5 without waste. The light emitting section 11 is provided with light emitting elements 1a and 1b and a light diffusing plate 12. Light emitting elements 1a, 1b
each has a light emission directional characteristic. For example, a light emitting element such as a light emitting diode is driven alternately in a time division manner by drive currents d and e from a time division drive circuit 13, and the light emitting element 1a emits red light and the light emitting element 1b emits green light. . These red light and green light are diffused by the light diffusing plate 12, and a part of them enters the optical fiber group 9 from the end face of the input portion 9a. That is, the light diffusing plate 12 includes the light emitting elements 1a,
The relatively sharp light emission directional characteristics of the light emitting elements 1b are made gentler, and the direction of the light emission directional characteristics of each of the light emitting elements 1a and 1b is aligned with the end surface of the incident part 9a and each light emitting element 1.
Even if it deviates somewhat from the straight line connecting the points a and 1b, the amount of colored light incident on the end face of the incident portion 9a can be made relatively large. Therefore, the light emitting section 1
The accuracy of arrangement of the light emitting elements 1a and 1b with respect to the incident part 9a in the case of FIG. Next, the operation of this embodiment will be explained. In FIGS. 2 and 3, the timing signal generation circuit 14 supplies a timing signal to the time division drive circuit 13, and this timing signal causes the time division drive circuit 13 to operate so that the duty ratio is shifted by 180° from each other. Rectangular drive currents d and e of 50% are generated to cause the light emitting elements 1a and 1b to emit light alternately in a time-division manner as described above. Red light and green light from the light emitting elements 1a and 1b are transmitted through the optical transmission line 8 and are alternately irradiated onto the object to be inspected 4. The object reflects colored light according to its hue, and the reflected light passes through the optical fiber transmission line 8 and is received by the light receiving section 5. The light receiving section 5 generates an analog signal with an amplitude corresponding to the amount of received light, but it is important to ensure that a sufficient amount of light is incident on the end face of the input section 9a of the optical fiber transmission line 8 and that the reflected light to the input/output section 8a is Since the incidence is efficient, an analog signal with a large amplitude and a good S/N ratio can be obtained from the light receiving section 5. The light receiving section 5 consists of a single light receiving element (for example, a phototransistor), and the obtained analog signal is a signal ( This is a time-division multiplexed signal consisting of a red signal (hereinafter referred to as a red signal) and a signal with an amplitude corresponding to the amount of light received by the light receiving unit 5 during the period when the light emitting element 1b emits green light (hereinafter referred to as a green signal). It is converted into a digital signal b similar to that of the prior art shown in FIG. 1 through an amplifier 6 and a comparator 7 similar to those shown in the figure. By the way, when the object to be inspected 4 is red, only red light is reflected, so the amplitude of the red signal of the analog signal a amplified by the amplifier 6 is large.
The amplitude of the green signal is zero or extremely small, and when the object is green, the amplitude of the green signal is large, and the amplitude of the red signal is zero or extremely small, but when the object is yellow. At certain times, the amplitudes of both the red and green signals become large, although the amplitudes are smaller than when the object is red or green. Therefore, the reference level Vs of the comparator 7 is set in consideration of these points, this reference level Vs and the analog signal a are compared, and the level of the analog signal a is set to the reference level.
The digital signal b is "1" when it is higher than Vs, and "0" when it is lower than the reference level Vs. Figure 3 shows each signal when determining the hue of the object to be inspected 4, which is red, after time _t1 .

[Table] The AND gates 17, 18, 19, and 20 determine the hue of the object to be inspected 4 by determining the states of the D-type flip-flops 15 and 16. signal h,
k, and the AND gate 19 has output signals i, j,
The AND gate 20 has output signals h, j, and
Output signals i and k are supplied to the AND gate 17, respectively. The states of the D-type flip-flops 15 and 16 are determined by these AND gates after the states of both the D-type flip-flops 15 and 16 are set, and the hue is determined from the combination of the respective states. That is, if the difference in the light emission timing of the light emitting elements 1a and 1b is T _0/2 as shown in FIG. 3, the generation timing of the strobe pulses f and g will also be
Therefore, the timing for setting the state of the D-type flip-flops 15 and 16 is also shifted by T _0/2 .
Shift by T _0/2 . Therefore, in order to determine the hue of an object using the time point at which the light emitting element 1a starts emitting light as a reference, the light emitting element 1a irradiates the object with red light, and then the same object is irradiated with green light using the light emitting element 1b. Assuming that red light and green light are repeatedly irradiated in a time-division manner, the state set in the D-type flip-flop 15 by the strobe pulse f is changed to D by the strobe pulse g.
This state held in the D-type flip-flop 15 and the state set in the D-type flip-flop 15 by the strobe pulse g are determined by the logic of the AND gates 17, 18, 19, and 20. This is the state of the object determined by calculation. Therefore, the third
The period Y in the figure is the retention period, and the period X is the determination period. There are four combinations of the states of the D-type flip-flops 15 and 16, and the outputs of the AND gates 17, 18, 19, and 20 differ depending on each combination.As is clear from Table 1, the difference in output is This represents the hue of the object to be inspected 4. These relationships are shown in Table 2 below.

[Table] Therefore, as mentioned above, the D-type flip-flop 15 is in the "1" state, and the D-type flip-flop 1 is in the "1" state.
6 is set to the "0" state, only the output B of the AND gate 18 is "1", and the outputs A, C, and D of the other AND gates 17, 19, and 20 are all "0", The hue of the object to be inspected 4 is determined to be red. Note that the retention period Y and determination period X shown in FIG.
is not necessarily uniquely determined, and when considering that the light emission timing of the light emitting element 1b precedes the light emission timing of the light emitting element 1a,
Period X is a retention period, and period Y is a determination period. The light emitting elements 1a and 1b are respectively attached to the object to be inspected 4.
When irradiating colored light one time at a time, the holding period and the judgment period are clearly distinguished depending on the timing of the light emission of these light emitting elements 1a and 1b. However, when the same object is repeatedly irradiated many times, , there is no distinction between the holding period and the determination period, and as long as the object is irradiated, the AND gates 17, 1
Outputs for hue determination are obtained from 8, 19, and 20. In addition, in Table 2, other colors are:
A hue that does not contain red or green components. In FIG. 3, before time _t1 , the object is green, the output C of the AND gate 19 is "1", and the outputs A, B, D of the other AND gates 17, 18, 20 are "1". This indicates that it is “0”. As described above, in this embodiment, four types of hues can be determined in real time by using two light emitting elements to emit light in a time-sharing manner, and moreover, a single light receiving element is used as the light receiving section 5. Since each color signal can be processed by a common processing circuit, the circuit configuration can be simplified and the comparator 7 can be used.
This has the advantage that the reference level of the light emitting elements 1a, 1 can be set commonly for the color signals, making it easier to set the reference level.
For any of the colored lights from b, the amplitude of the analog signal obtained by the light receiving section 5 is large, the S/N ratio is good, and the accuracy of hue determination is greatly improved. FIG. 4 is a block diagram of main parts showing another embodiment of the color sensor according to the present invention, 21 is a sealing body, and the same reference numerals are used for parts corresponding to those in FIG. 2. In FIG. 4, the light emitting section 11 is constructed by arranging light emitting elements 1a and 1b on a single stem, and sealing them with a sealing body 21 in which a light scattering material is mixed in a uniform distribution. For this purpose, the light emitting elements 1a, 1b
The beam-shaped red light and green light generated with relatively sharp emission directional characteristics from the light emitting elements 1a and 1b are scattered and spread within the sealing body 21, and therefore, the relatively sharp emission directional characteristics of the light emitting elements 1a and 1b are caused by the The stopper 21 provides a gentle directivity characteristic, and even though the light emitting elements 1a and 1b have relatively sharp light emission directivity characteristics, each color light is sufficiently incident on the incident portion 9a. FIG. 5 is a block diagram showing still another embodiment of the color sensor according to the present invention, in which 1b' is a light emitting element, 22 is a sealing body, and parts corresponding to those in FIG. 2 are denoted by the same reference numerals. is attached. In this embodiment, a red light emitting diode such as GaAlAs is used as the light emitting element 1a, and an infrared light emitting element such as GaAs:Si is used as the light emitting element 1b'. The light emitting elements 1a, 1b' are arranged on a single stem and sealed with a sealing body 22 containing an anti-Stokes phosphor mixed in a uniform distribution, thereby forming a light emitting section 11. The light emitting elements 1a and 1b' are driven to emit light alternately in a time-sharing manner, and the red light from the light emitting element 1a is scattered by the anti-Stokes phosphor in the sealing body 22, and the red light from the light emitting element 1a is scattered by the anti-Stokes fluorescent material. The infrared rays from 1b' excites the anti-Stokes phosphor in the sealing body 22, causing the sealing body 22 to emit green light. Therefore, the sealing body 22 acts as a diffusing means for red light, and also acts as a green light emitter together with the infrared light emitting element 1b'. Therefore, both red light and green light are emitted from the sealing body 22 in all directions, and the relatively sharp light emission directional characteristics of the light emitting elements 1a, 1b' are relaxed, and the light emitting elements 1a, 1b' have relatively sharp light emission directivity characteristics. Regardless of the light emission directivity characteristic of 1b', the amount of light incident on the incident portion 9a increases. In the embodiment shown in FIGS. 4 and 5, the two light emitting elements are integrated by the sealing body, so the work of attaching the light emitting part is easy.
Furthermore, the light emitting section can be configured to be compact. In this case, the arrangement relationship between the two light emitting elements does not require particularly high precision, and therefore the process for integrating the light emitting elements and the sealing body does not become complicated. Furthermore, in the embodiment shown in FIG. 4, the beam-shaped colored light generated from the light emitting elements 1a and 1b having relatively sharp emission directional characteristics is scattered inside the sealing body 21 and has a gentle directional characteristic. The colored light exits from the spherical surface of the sealing body 21, but at this time, this spherical surface exerts a slight condensing effect on the colored light with gentle directional characteristics. This results in
The amount of light incident on the incident portion 9a increases. This means that
The same applies to the embodiment shown in FIG. In the embodiments described above, the case where hue determination is performed using red light and green light has been explained, but the same effect can be obtained by using other colored lights. It is also possible to use light-emitting elements that emit light of different colors, and 2 ⁿ types of hue determination can be performed. Furthermore, as for the optical fiber transmission line, as in the prior art shown in FIG. In addition, the object to be hue judged is not limited to a reflector,
Similar effects can be obtained even with a transparent material. As explained above, according to the present invention, colored light generated by each of the light emitting means having a plurality of different emission wavelengths can be efficiently input into an optical fiber transmission path, and the amount of colored light irradiated onto an object can be reduced. At the same time, the placement accuracy of the plurality of light emitting means is relaxed, making installation easier, and it is possible to judge various hues in real time and with high precision, providing a color sensor with superior functions not found in the above-mentioned conventional technology. can do.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of a conventional color sensor, FIG. 2 is a block diagram showing an embodiment of a color sensor according to the present invention, FIG. 3 is a waveform diagram showing signals of each part in FIG. FIG. 4 is a block diagram of main parts showing another embodiment of the color sensor according to the present invention, and FIG. 5 is a block diagram of main parts showing still another embodiment of the color sensor according to the present invention. 1a, 1b, 1b'... Light emitting element, 4... Test object, 5... Light emitting section, 8... Optical fiber transmission line, 1
1... Light emitting part, 12... Light diffusing plate, 21, 22...
...Encapsulation body.

Claims (1)

[Scope of Claims] 1. Light of different wavelengths from a plurality of light emitting means having emission directional characteristics is transmitted through a single incident surface of an optical fiber transmission line, and is irradiated onto an object to emit light from the object. In a color sensor capable of determining the hue of the object by detecting reflected light, a light diffusing means consisting of a spherical surface and a flat surface is provided, and the light diffusing means and the light diffusing means are arranged on the flat side of the light diffusing means. A color sensor characterized in that the light emitting means are arranged integrally, and the incident surface of the optical fiber transmission line is arranged on the spherical side of the light diffusing means. 2. In claim 1, one of the light emitting means is an infrared light emitting means, and when the light diffusing means is excited by infrared rays and the other light emitting means are generated, it generates light of a different color from the light. A color sensor characterized by: