CN102553830B - Laser scanning sorting machine - Google Patents

Abstract

The invention discloses a laser scanning sorting machine, which comprises a feeding chute, a baffle plate, a background drum, an optical scanning box, a discharge chute and a spray valve; the side surface of the background drum is a concave arc surface, and the optical scanning The incident light that the box scans on the arc surface is perpendicular to the tangential position of the arc surface; the aforementioned baffle is an arc baffle, and the outlet is also arc-shaped; the baffle, the outlet and the background drum are three same arc. The present invention has a simple structure, the arc-shaped discharge port, the arc-shaped baffle plate, and the arc-shaped drum have low precision requirements, low processing difficulty, and the price is only several hundred yuan more than the original linear processing, and the scanning signal intensity is consistent. The scanning effect is good, the laser utilization rate is high, and it can realize fast intelligence, high precision, simple operation and easy maintenance.

Description

A laser scanning sorter

technical field

The invention relates to a sorting machine, in particular to a laser scanning sorting machine.

Background technique

With the rapid development of various sorting technologies, sorting objects have become more and more abundant, involving food, vegetables, fruits, tobacco, electronic devices, ores and many other fields. Among them, people pay more and more attention to the quality of food. The selection requirements are getting higher and higher. At this time, the traditional sorting technology based on digital image processing can no longer meet the current accuracy requirements. In this context, people introduce laser technology, use semiconductor lasers, design and build optical paths, and cooperate with rotating prisms to form a laser scanning system with a large field of view.

However, this large field of view scanning technology has several disadvantages:

1. When scanning a plane, it is difficult to obtain a relatively consistent scanning signal. The signal in the middle of the scanning line is strong, and the signal on both sides is weak. The horizontal axis is the scanning position, and the vertical axis is the detection illumination. This is mainly caused by the inconsistency of the light incident angle, the optical path and the aperture of the rotating mirror.

2. When scanning the plane, the size of the scanning spot will change with the scanning angle. The specific performance is that when the spot is focused on the center of the scanning line, the center spot is circular, the two ends of the spot are elliptical, and the width of the spot is from two scan lines to Tapers gradually toward the center.

3. When scanning the plane, although the scanning angular velocity is uniform, the displacement of the scanning point per unit time is changing. The displacement is small at the center of the scanning line and large at both ends of the scanning line.

In view of the above three shortcomings, someone proposed the design of optical lens group and movable baffle:

Through the optical lens group, that is, the ftheta lens group, a consistent scanning angle can be obtained, which partially solves the first shortcoming, and better solves the second and third shortcoming, but the structure is complicated. With the increase of the scanning angle, the lens size increase. High-precision plano-concave and plano-convex lenses, if the processing size of each piece reaches a width of 50cm, the price will be nearly 10,000 yuan, and this large field of view scanning system requires at least 3 large-sized lenses to form an ftheta lens group.

In the design of the movable baffle, the light transmission area is adjustable. If the central light-transmitting area is reduced and the light-transmitting areas at both ends are increased, the first shortcoming can be well solved. This structure is relatively simple, easy to operate and implement. However, this design cannot eliminate the effects of the second and third disadvantages, and reduces the effective utilization of the laser.

Contents of the invention

The technical problem to be solved by the present invention is that the existing laser scanning sorting machine has good effect, complex structure and high cost, poor effect with simple structure, and low effective utilization rate of laser.

In order to solve the above-mentioned technical problems, the technical solution adopted in the present invention is: a laser scanning sorter, including a feed chute, a baffle, a background drum, an optical scanning box, a discharge chute and a spray valve; the materials to be sorted The flow average speed is conveyed from back to front along the feeding chute, and thrown out from the outlet of the feeding chute; the baffle is located at the front of the feeding chute, and its top is flush with the bottom of the feeding chute; the background drum is located at the front of the baffle Below; the discharge chute is located at the bottom of the background drum, including the rejecting chute and receiving chute arranged side by side; the output end of the optical scanning box is connected to the input end of the peripheral control system, and its scanning position is located behind the material flow. And this position corresponds to the position of the background drum located in front of the material flow; the spray valve is located between the background drum and the discharge chute, and its control end is connected to the output end of the peripheral control system, and the side surface of the background drum It is a concave arc surface, and the incident light scanned by the optical scanning box on the arc surface is perpendicular to the tangential position of the arc surface; the aforementioned baffle is an arc surface baffle, and the discharge port is also arc-shaped; The radians of the feed port and the background drum are the same.

The aforementioned optical scanning box adopts the existing product. The arc-shaped discharge port can make the material flow fall in an arc when it falls, and the arc-shaped baffle can slow down the throwing of the material flow while keeping the material flow on the arc surface. The effect of the horizontal speed at the time; the material flow falls from between the baffle plate and the discharge port to between the optical scanning box and the background drum, the optical scanning box scans the material flow on the arc surface, and the reflected scanning signal is passed through the original scanning The optical path returns to the optical scanning box for sampling, and the central control system compares and analyzes the sampling signals, and at the same time controls the opening and closing of the spray valve, so that the material flow enters the rejection tank or the receiving tank respectively. Since the curvature of the arc-shaped baffle, the arc-shaped discharge port and the arc-shaped background drum are consistent, and the incident light scanned by the optical scanning box on the arc surface is perpendicular to the tangential position of the arc surface, the incidence of the sweep light is guaranteed The angle and the optical path from the scanning light to each point on the plane are basically the same, and on the same scanning plane, the analysis of each point is almost under the same conditions, so that the comparative analysis formed is more consistent and accurate.

The advantages of the present invention are: simple structure, low precision requirements for arc-shaped discharge port, arc-shaped baffle plate, and arc-shaped drum, low processing difficulty, and the price is only several hundred yuan more expensive than the original linear processing, and the scanning The signal strength is consistent, the scanning effect is good, the laser utilization rate is high, and it can realize fast intelligence, high precision, simple operation and easy maintenance.

Description of drawings

Figure 1 is a schematic diagram of the scanning principle of an existing laser scanning sorter.

Fig. 2 is a schematic diagram of the scanning effect of the laser scanning sorter shown in Fig. 1 .

Fig. 3 is a schematic diagram of the structure of the present invention.

Fig. 4 is a schematic diagram of the scanning principle of the present invention.

Fig. 5 is a schematic diagram of the scanning effect of the present invention.

Detailed ways

The present invention will be further described below in conjunction with accompanying drawing.

As shown in Figure 1, the background drum 4 used in the existing laser scanning sorter is cylindrical, while the optical scanning box 2 includes a beam splitter 2-1, a rotating prism 2-2 driven by a high-speed motor , at least one photodetector 2-3, at least one laser 2-4, at least one focusing lens 2-5, and at least one prism 2-6.

When in use, the laser light emitted by the laser 2-4 is transmitted through the beam splitter 2-1 to the focusing lens 2-5 for focusing, and the rotating prism 2-2 is then reflected by the rotating prism 2-2 to scan the material. The optical signal is reflected by the rotating prism 2-2 along the original optical path to the focusing lens 2-5 and the beam splitter 2-1, then reflected by the beam splitter 2-1 to the prism 2-6, and received by the optical detector 2-3. By using the characteristics of the beam splitter 2-1, the scanning and reflection signal sampling share the same optical path.

As shown in Figure 2, the horizontal axis is the scanning position, and the vertical axis is the detected signal intensity. The scanning effect of the existing laser scanning sorter is difficult to scan the signal due to the inconsistent light incident angle, optical path and light aperture of the rotating mirror. Keep consistent, showing the phenomenon that the signal in the middle of the scan line is strong and the signal on both sides is weak. Experimental data: plane scanning optical path, the vertical distance between the plane and the rotating mirror scanner is 45cm, every scan 10 degrees, sampling the current point, scanning 60 degrees from left to right, recording 7 point data, which are: 0.25, 0.27, 0.31, 0.32 , 0.31, 0.28, 0.26, unit lux.

As shown in Figure 3, the present invention comprises feed chute 1, baffle plate 3, background drum 4, optical scanning box 2, discharge chute and spray valve 6; Convey from the back to the front, and throw out from the outlet 1-1 of the feeding chute 1; the baffle plate 3 is located at the front end of the feeding chute 1, and its top is flush with the bottom surface of the feeding chute 1; the background drum 4 is cylindrical , and is located below the front end of the baffle plate 3; the discharge chute is located at the bottom of the background drum 4, including the rejecting chute 7 and the receiving chute 8 arranged side by side; the output end of the optical scanning box 2 and the input end of the control system of the peripheral connected, its sweeping position is located behind the material flow 5, and this position corresponds to the position of the background drum 4 located in front of the material flow 5; the spray valve 6 is installed on the top of the discharge chute, and its control end is connected to the external control system output terminal. Any section of the background drum 4 along the axial direction is circular, and its side surface is a concave arc surface. The incident light scanned by the optical scanning box 2 on the arc surface is perpendicular to the tangential position of the arc surface; the aforementioned The baffle 3 is an arc-shaped baffle, and the outlet 1-1 is also arc-shaped; the arcs of the baffle 3, the outlet 1-1 and the background drum 4 are the same.

When working, the material flow 5 to be sorted is first sent out evenly from the rear end to the front end by the conveyor belt in the feeding chute 1, and the horizontal speed slows down when passing through the baffle plate 3, and it falls on an arc surface, and the optical scanning box 2 is on the material flow 5 The arc surface corresponding to the position of the background drum 4 is scanned, and the reflected scanning signal is returned to the optical scanning box 2 for sampling through the original scanning optical path, and the sampled signal is sent to the control system of the peripheral device, and is transferred to the control system in the control system. Sampling signal comparison and analysis, the control system controls the opening and closing of the spray valve 6 located between the background drum 4 and the discharge chute at the same time, when the scanning signal is normal, that is, when the product meets the specified standards, the spray valve 6 is in the closed state, and the product enters the receiving trough 8. When the scanning signal is abnormal, that is, when the product is a defective product or foreign matter, the spray valve 6 is opened, and the defective product is rejected into the rejection tank 7 by the spray force, thereby completing the material sorting process. The spray valve 6 is an existing product, generally composed of a compressor and a pneumatic nozzle array.

As shown in Figure 4, the background drum 4 used in the present invention is an arc background drum, any section along the axial direction is circular, and its side surface is a concave arc surface, while the optical scanning box 2 is Use an existing product. Two or more sets of lasers 2-4 and photodetectors 2-3 can be selected according to needs, and they can be used in combination with different wavelengths to achieve the best sorting effect.

The rotating prism 2-2 relies on the existing high-speed motor for its rotational drive, and its rotating speed reaches more than 10,000 revolutions per minute. The surface position information of 2-2 is fed back to the control system.

The photodetector 2-3 is composed of a photomultiplier tube and its associated low-noise amplifier or devices with similar performance, and is used to convert optical signals into electrical signals. The photomultiplier tube is an existing high-sensitivity weak light signal detection device, which has the characteristics of strong signal amplification capability, high precision, and small size. The signal of each sampling is the reflected light intensity of a point.

When in use, the laser 2-4 only scans one point at a time, and every time the rotating prism 2-2 rotates one side, a scanning line is formed. And select the photomultiplier tube as the photodetector 2-3 to convert the optical signal into an electrical signal; the signal sampled each time is the reflected light intensity at a certain point on the scanning line, and the photodetector 2-3 needs to continuously scan the signal. sampling.

As shown in Figure 5, the horizontal axis is the scanning position, and the vertical axis is the signal strength of the detection. In the present invention, since the light incident angle and the optical path are kept consistent, the scanning signal is also consistent, and the intensity of the middle signal and the signals on both sides of the scanning line is consistent. Weak also remains consistent. Experimental data: arc scanning optical path, the vertical distance between the arc and the rotating mirror scanner is 45cm, every scan 10 degrees, sampling the current point, scanning 60 degrees from left to right, recording 7 point data, which are: 0.31, 0.32, 0.32 , 0.32, 0.33, 0.33, 0.32, unit lux.

Claims (1)

1. A laser scanning sorter, comprising a feed chute, a baffle, a background drum, an optical scanning box, a discharge chute and a spray valve; The material flow to be sorted is conveyed from back to front along the feeding chute at an even speed, and thrown out from the outlet of the feeding chute; The baffle is located at the front end of the feeding chute, and its top is flush with the bottom surface of the feeding chute; The background drum is located under the front end of the baffle; The discharge chute is located at the bottom of the background drum, including a rejection chute and a receiving chute arranged side by side; The output end of the optical scanning box is connected to the input end of the peripheral control system, and its scanning position is located behind the material flow, and this position corresponds to the position of the background drum located in front of the material flow; The spray valve is located between the background drum and the discharge chute, and its control end is connected to the output end of the peripheral control system. It is characterized in that any section of the background drum along the axial direction is circular, and its side The surface is a concave arc surface, and the incident light scanned by the optical scanning box on the arc surface is perpendicular to the tangential position of the arc surface; the aforementioned baffle is an arc baffle, and the discharge port is also arc-shaped; the baffle, The radians of the discharge port and the background drum are the same.