JPS592546B2 - Tea leaf sorting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tea leaf sorting device that sorts grass and tea leaves contained in raw tea confectionery using the difference in reflectance.

A photoelectric tea and confectionery sorting method using a cadmium sulfide photoconductive cell as a photosensitive member (Japanese Patent Publication No. 40-4310) is known.

This invention method takes advantage of the fact that when the raw material is irradiated with white light, yellow trees and plants change the resistance of a cadmium sulfide photoconductive cell more than dark green tea confections.

As is well known, the amount of reflected light R is proportional to the product S-r of the reflection area S and the reflectance r.

Therefore, in order to know the reflectance r from the amount R of reflected light, the reflection area S needs to be known.

In the photoelectric tea leaf sorting method, the diameter of the light receiving window is 1 to 2 mr.
Let n be the same as or smaller than the minimum raw material, and the reflection area S
By artificially setting R to a constant value, the amount of reflected light R is made proportional only to the reflectance r.

However, as mentioned above, if the reflection area cannot be set artificially, the above method cannot be used.

A method of calculating the reflectance from the projected area of the raw tea leaves and the amount of reflected light R may be considered, but this may complicate the arrangement of the light source and the calculation device.

Furthermore, when sorting a large quantity of raw confections, continuous processing is required.

Since the shape and size of the raw tea leaves are not constant, it is not easy to accurately and automatically exclude a specific portion from the raw tea leaves that are fed almost seamlessly.

The purpose of the present invention is to enable sorting based on reflectance without being affected by the shape and size of the raw confectionery without restricting the reflection area using the light receiving window as described above, and to also enable sorting timing signals. The purpose of the present invention is to provide a tea leaf sorting device that can simultaneously generate tea leaves.

The inventors of the present application conducted precise measurements of the spectral reflectance of tea confectionery, light-colored tree grass, and brown-colored tree grass contained in raw tea leaves, and found that the infrared rays (more than 800 nanometers) of each
It was found that the reflectance in the visible light region is smaller than the reflectance in the infrared region, and that the ratio differs depending on tea leaves, pale-colored trees, and brown and colored trees. Ta.

Therefore, in order to achieve the above object, the tea and confectionery sorting device according to the present invention includes a continuous feeding device that connects and feeds the raw confectionery in a linear manner, and a feeding process by the continuous feeding device that includes infrared and visible light. An irradiation device that irradiates raw tea leaves; an infrared detector that photoelectrically converts infrared components and detects the amount of infrared light contained in the reflected light reflected from the raw tea leaves irradiated by the irradiation device; a visible light detector that detects the amount of visible light reflected from the raw tea confectionery irradiated by the irradiation device; and a ratio of the output of the infrared detector to the output of the visible light detector to be output. a ratio calculation circuit consisting of a calculation circuit that calculates a ratio, a comparison circuit comprising a comparator that generates an output signal when the output of the ratio calculation circuit exceeds a predetermined ratio, and either the visible light detector or the infrared detector. A peak position detection circuit that detects the peak value of one output and generates an output signal at the time of peak occurrence, and an AND circuit that outputs a selection signal when the output signals of the peak position detection circuit and the comparison circuit match. a route changing device that is driven by the sorting signal and changes the route of the raw material having the portion where the peak has occurred in the raw tea confectionery; and a container that separates the raw material whose route has been changed from the raw material whose route has not been changed. It is configured.

That is, by calculating the ratio of the output of the infrared detector and the output of the visible light detector using the ratio calculation circuit, the influence of fluctuations in the amount of reflected light due to the shape and size of the raw material is removed, and the reflectance in the infrared region is calculated. Sorting is performed based on the difference in the ratio of reflectance in the visible region.

Furthermore, the center (large width part) of the raw material is detected by detecting the maximum point in time of the amount of reflected light from the moving raw material using a peak position detection circuit.

Then, on the condition that a signal indicating the detection point of this peak position is generated and the output of the ratio calculation circuit exceeds a predetermined ratio, the route of the corresponding part of the raw tea leaves is changed. Drive the device.

The present invention will be described in detail below with reference to the drawings and the like.

FIG. 1 is a block diagram of an embodiment of an apparatus according to the present invention.

In the figure, 1 is a gutter, and when the raw tea leaves are slid down along the gutter 1, they are aligned in a line and can be discharged from the lower end of the gutter 1 at a constant speed.

The above discharge rate varies depending on the length of the trough 1 and the smoothness of the surface of the slope 2, but a rate of 5 meters/second can be easily obtained.

The raw tea leaves are thrown into the receiving box 7 if no external force is applied after they are discharged.

Reference numeral 2 denotes a light irradiation device, which consists of a light source and an optical system.

As the light source, a tungsten incandescent lamp is used because, as will be described later, infrared rays and visible light are used, and the brightness does not change in sync with changes in the power supply voltage.

The optical system is used to project the light emitted from the light source onto the raw tea confectionery emitted from the gutter 1 in a predetermined projection pattern.

The pattern to be projected is a rectangle measuring 2 mm in the running direction of the raw tea leaves and 30 mm in the direction perpendicular to the running direction.

The above 2 mm is set as short as possible considering the running speed of the raw confectionery, the size of the raw confectionery, the detection speed, etc. The above 30 mm is set as short as possible because it limits the field of view for discrimination. It is set to be longer than the diffusion width of the raw tea confectionery in the direction perpendicular to the running direction.

3 is an infrared detector having sensitivity in the wavelength region of 750 to 900 nanometers by combining a silicon photocell with sensitivity from the visible region to the infrared region and an optical filter that blocks visible light.

4 is a visible light detector using a gallium arsenide phosphide photodiode sensitive to a wavelength range of 500 to 650 nanometers.

The infrared detector 3 and the visible light detector 4 are placed close to each other so that only the raw tea leaves irradiated by the irradiation device 2 are viewed from the same direction.

Reference numeral 5 denotes an air valve control device, and its configuration and operation will be explained based on FIG. 2.

In FIG. 2, 30 is a silicon photocell that is incorporated in the infrared detector 3 in FIG. 1, and 40 is a gallium arsenide phosphorous photodiode that is incorporated in the visible light detector 4 in FIG. .

12 and 22 are conversion circuits; the conversion circuit 12 converts a current corresponding to the amount of incident infrared light emitted by the infrared detector 3 into a voltage, and the conversion circuit 22 converts the current corresponding to the amount of incident visible light emitted by the visible light detector 4 Convert the current corresponding to to voltage.

The conversion rate of the conversion circuit 12 and the conversion circuit is such that the detectors 3 and 4 convert the current detected by the reflected light of standard tea leaves into voltage, and the background removal circuits 13 and 23 described later convert the reflected light of the tea leaves into voltage. The settings are made so that the outputs of the background removal circuits 13 and 23 are equal when voltage components due to incidence of light other than that and the dark current of the photocell are removed.

In order to obtain only the amount of reflected light from the raw tea leaves as a signal, the background removal circuits 13 and 23 send out a voltage obtained by subtracting the voltage corresponding to the incident light other than the reflection from the raw tea leaves and the dark current of the photocell from the input voltage. do.

Here, the relationship between the optical properties of tea leaves and xylophones and the outputs of the background removal circuits 13 and 23 will be explained.

FIG. 3 shows typical spectral reflectances of tea cake (1), pale colored xylophone (It), and brown and colored xylophone (1).

For convenience of comparison, these values are normalized to 1 at a wavelength of 800 nanometers.

The figure shows that the average reflectance in the visible light region of 500 to 650 nanometers is small for tea leaves and large for xylophone compared to the average reflectance in the infrared region of 750 to 900 nanometers.

The spectral characteristic curves of the tea confections and the two types of xylophones that are actually identified are distributed within a certain range centered on the curve showing the spectral reflectance shown in FIG.

Therefore, even if the ratio of the output from the background removal circuit 13 and the output from the background removal circuit 23 is adjusted to be 1 in the ideal reflected light from the tea leaves shown in FIG. Greater output is obtained with the thin-rimmed xylophone, which can vary from 0.8 to 1.2, and from 1.4 to 1.8, centered around 1.6.

For brown and colored xylophones, the value varies from 1.8 to 2.2, with a value of 2.

The state of this distribution is shown in FIG.

In the figure, IV, V, and Vl are tea leaves, respectively. It shows the output distribution of water stems with pale edges and xylophones with brown and colored edges.

The ratio calculation circuit 14 is a background removal circuit 13.23
This circuit uses the outputs of as a divisor signal and a dividend signal, respectively.

The output of the ratio arithmetic circuit 14 is larger for the xylophone with a light edge color than that of the tea leaves, and is larger for the xylophone with a brown color than the xylophone with a light edge color.

FIG. 5 is a graph showing the correspondence between the output of the ratio calculation circuit 14 and FIG.

That is, the ratio calculation circuit 14 calculates a voltage corresponding to the amount of infrared light reflected from the tea leaves sent out from the background removal circuit 13 and a voltage corresponding to the amount of visible light reflected from the raw tea confectionery sent out from the background removal circuit 23. A voltage of 4 to 6 volts for tea leaves, 7 to 9 volts for thin-edged stems, and 9 volts or more for brown and colored stems is sent out.

15 is a comparator circuit which sends out a logic signal, ie, a constant voltage pulse having an amplitude between 2.4 and 5 volts, only when the input signal is above the reference level.

Therefore, the comparison circuit 15 sets the reference level to 6.5.
If set to volt, it will send out a logic signal when it receives the reflected light from the xylophone.

Reference numeral 16 denotes a peak position detection circuit, which corresponds to the time at which the peak value is taken when the voltage corresponding to the amount of reflected infrared light from the tea leaves sent out from the background removal circuit 13 has a waveform as shown in Fig. 6 (■). and send out a pulse ■.

The configuration example and operation of this peak detector 15 will be further explained with reference to FIG.

When the tea leaves slide down the gutter 1 shown in Fig. 1 and enter the projection pattern of the light irradiation device 20, the light emitted from the infrared detector B as shown in Fig. 6
An increasing output signal is obtained as shown at A1, and as it leaves the projection pattern, a decreasing output signal is obtained as shown at A2, reaching a maximum value at a point or short time A in between.

In other words, since A corresponds to the point in time when the center of the tea leaves is within the projection pattern of the light irradiation device 2, if the air valve 6, which will be described later, is operated after a certain time delay based on A, air will always be blown to the center of the tea leaves. You can blow the tea leaves by

In order to enable the above-described operation, the peak position detection circuit 16 inputs the signal sent out from the silicon photocell 30 incorporated in the infrared detector 3 via the background removal circuit 13, and calculates the maximum value of the input signal. At value point A, a pulse as shown in FIG. 6 is sent out.

The peak position detection circuit 16 is realized, for example, by a circuit as shown in FIG.

That is, the positive electrode of the diode 32 is connected to the output terminal of the differential amplifier 31 with high input resistance, and the negative electrode is connected to the output terminal of the differential amplifier 31 with high input resistance.
10 is connected to the inverting input terminal.

The negative electrode of the diode 32 is grounded through a parallel circuit consisting of a capacitor 33 and a resistor 34.

A differentiating circuit 37 is connected to the output terminal of the differential amplifier 31, a polarity inverting circuit 38 is connected to the differentiating circuit 37, and a waveform shaping circuit is connected to the polarity inverting circuit.

A positive voltage pulse corresponding to the amount of reflected light from the tea leaves is input to the non-inverting input terminal of the differential amplifier 31, and when the positive voltage pulse falls from the maximum amount, the voltage at the output terminal of the differential amplifier 31 falls suddenly. .

This voltage is differentiated by a differentiating circuit 37, its polarity is inverted by a polarity reversing circuit 38, and the waveform shaping circuit 39 shapes the pulse waveform into a logic signal level pulse waveform and sends it out.

Note that the peak position detection circuit 16 may input the output signal of the visible light detector 4.

Reference numeral 17 denotes an AND gate circuit which sends out a signal obtained by ANDing the logic signal from the comparison circuit 15 and the logic signal from the peak position detection circuit 16.

Reference numeral 18 denotes an air valve drive voltage generation circuit, which generates drive power for operating the air valve 6 based on the logic signal sent out by the AND gate circuit 17 and corresponding to the reflection at the center of the grass.

Reference numeral 6 denotes an air valve whose nozzle is directed toward a point downstream from the projection position of the light of the irradiation device 2 on the travel path of the tea and confectionery discharged from the gutter 1 .

The air valve 6 is used to irradiate the plants contained in the raw tea leaves with the irradiation device 20.
It operates based on the output signal of the AND gate circuit 17 indicating that the projection position is present.

The receiving box 7 is arranged in such a position that the raw tea leaves discharged from the gutter 1 will be thrown into the receiving box 7 unless an external force is applied afterwards, and the receiving box 8 is arranged so that the raw tea leaves are blown away by the airflow from the valve 6. It is arranged at such a position that it can be thrown into the receiving box 8 when the container is loaded.

In the above-mentioned apparatus, since the length of the raw confectionery is about 5 mm, the pulse width of the reflected light is about 700 microseconds.

Both the silicon photocell and the gallium arsenide phosphorus photocell used in the two photodetectors 3 and 4 that detect this reflected light have a rise time of 10 microseconds or less, and the rise time of each circuit used in the air valve driving device 5 is 10 microseconds or less. Time is also number 1
Since it is 0 microseconds or less, the delay time due to signal processing remains at several hundred microseconds or less.

In contrast, the rise time of the air valve requires 2 milliseconds.

Since the traveling distance of the raw confectionery from the projection position of the irradiation device 20 to the front of the nozzle of the air valve 6 is 12.5 mm, the reflected light from the trees and plants is detected and the air valve 6 is driven. When the air is ejected, the center thereof is located just in front of the nozzle of the air valve 6, and is blown away in a direction perpendicular to the traveling direction and stored in the receiving box 8.

As explained in detail above, since the device according to the present invention performs selection based on the difference in the ratio of reflectance in the infrared region and reflectance in the visible region, the element of reflection area is eliminated when calculating the ratio. be done.

Therefore, it is possible to perform selection without being affected by such influences without artificially limiting the reflection area.

Furthermore, since the peak position detection circuit can detect the center position of the raw confectionery, the air valve, which is a path changing device, can be operated at an appropriate timing.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a tea and confectionery sorting device according to the present invention;
FIG. 2 is a block diagram of the air valve drive circuit, infrared detector, and visible light detector shown in FIG. 1. Figure 3 is a graph showing the spectral reflection characteristics of tea confectionery and trees and plants.
The figure is a graph showing the distribution of the ratio of the output signals of the background removal circuits 13 and 23 shown in Fig. 2, divided into tea confectionery, pale colored water stems, and brown and colored trees, and Fig. 5 is shown in Fig. 2. A graph showing the correlation between the input and output of the ratio calculation circuit, Figure 6 is a diagram showing the output signal waveform of the infrared detector and the pulse waveform at the peak position of the output signal waveform, and Figure 7 is a circuit diagram of the peak position detection circuit. It is. 1... Gutter, 2... Irradiation device, 3...
...Infrared detector, 4...Visible light detector,
5... Air valve control device, 6... Air valve, 7, 8... Receiving box, 14...
Ratio calculation circuit, 15... Comparison circuit, 16...
. . . Peak position detection circuit, 17 . . . AND gate circuit, 18 . . . Air valve drive voltage generation circuit.

Claims (1)

[Scope of Claims] 1. A continuous feeding device that continuously feeds raw tea leaves in a linear manner, an irradiation device that includes infrared rays and visible light and irradiates the raw tea leaves that are in the process of being fed by the continuous feeding device, and an infrared detector that photoelectrically converts the components and detects the amount of infrared light contained in the reflected light reflected from the raw tea confectionery irradiated by the irradiation device; a ratio calculation circuit consisting of a visible light detector that detects the amount of visible light reflected from the raw tea leaves; and a calculation circuit that calculates and outputs a ratio between the output of the infrared detector and the output of the visible light detector; a comparison circuit comprising a comparator that generates an output signal when the output of the ratio calculation circuit exceeds a predetermined ratio; and detecting the peak value of the output of either the visible light detector or the infrared detector; a peak position detection circuit that generates an output signal at the time of peak occurrence; an AND circuit that outputs a sorting signal when the output signals of the peak position detection circuit and the comparison circuit match; A tea confectionery sorting device comprising: a route changing device for changing the route of a raw material having a portion where the peak occurs in a tea confection; and a container for separating the raw material whose route has been changed from the raw material whose route has not been changed. 2. The tea leaf sorting device according to claim 1, wherein the continuous feeding device guides raw tea leaves through a gutter and causes them to fall freely in a linear manner. 3. The tea leaf sorting device according to claim 1, wherein the visible light detector uses a photodiode sensitive to a wavelength range of 500 to 650 nanometers as a visible light detection element. 4. The tea leaf sorting device according to claim 1, wherein the infrared detector is configured to block visible light by combining an optical filter and photoelectrically convert light in a wavelength range of 750 to 900 nanometers. 5. The tea and confectionery sorting device according to claim 1, wherein the route changing device is an air valve.