TWM643408U - Non-contact conveyor belt offset detection device - Google Patents

Abstract

The non-contact conveyor belt deviation detection device of the present invention is applied to a conveyor provided with a conveyor belt, and the conveyor belt circulates between the entrance side and the exit side of the conveyor. The conveyor has a support plate on the inlet side at the bottom of the conveyor belt, which is located in the standard mounting area of the support plate. The distance between the corresponding two edges of the standard installation area and the corresponding two edges of the conveyor belt is defined as the detection reference position. The non-contact conveyor belt deviation detection device includes a non-contact displacement detection unit. The non-contact displacement detection unit is set on the conveyor corresponding to the detection reference position. The non-contact displacement detection unit detects that any edge of the conveyor belt is displaced to the detection reference position, and then generates an abnormal signal to the conveyor, and the conveyor stops the operation of the conveyor belt according to the abnormal signal.

Description

Non-contact conveyor belt deviation detection device

The invention provides a conveyor belt offset detection device, especially a non-contact conveyor belt offset detection device.

The current conveyors, especially the conveyor belts used in inspection machines for wide-format printed matter, are often made of soft materials such as Teflon, and the width of the conveyor belt is quite large, so they usually deform due to insufficient rigidity when squeezed. However, the contact-type conveyor belt deviation detection device used to detect the conveyor belt deviation of the conventional inspection machine needs sufficient thrust to be actuated.

Therefore, when the conveyor belt deviates to an abnormal position and hits the contact conveyor belt deviation detection device, the conveyor belt is often squeezed by the contact conveyor belt deviation detection device and deformed due to insufficient rigidity, resulting in insufficient thrust of the conveyor belt to the contact conveyor belt deviation detection device. Furthermore, contact conveyor belt deviation detection devices are unable to warn personnel and/or stop the conveyor belt if the conveyor belt is worn.

In this way, the continuously worn conveyor belt will continue to generate debris, thereby affecting the inspection quality, and the continuously worn conveyor belt cannot operate stably, which also affects the inspection quality. In more serious cases, the entire conveyor belt may even fall off or be damaged, resulting in costs such as man-hours, manpower, and money for replacing or repairing the conveyor belt.

Even if the conveyor belt is not worn due to abnormal deflection, occasional minor deflection still touches the contact conveyor belt deflection detection device. As a result, slight abrasion and dust generation may affect the inspection quality.

In addition, if the sensitivity of the contact conveyor belt deviation detection device is to be improved, the mechanical parameters for the contact conveyor belt deviation detection device to trigger a warning due to the thrust of the conveyor belt can usually be set. However, a setting that is too sensitive may easily lead to false alarms, while a setting that reduces false alarms is not sensitive enough. This makes it difficult to use the contact conveyor belt deviation detection device.

In addition, the conventional contact conveyor belt deviation detection device is also arranged on the downstream side of the conveyor belt where the conveyor belt deviation is small. This wrong setting position causes errors in the detection of conveyor belt deviation, making the conveyor unable to operate stably. Therefore, there is still a need to improve the conventional contact conveyor belt deviation detection device applied to conveyors.

The main purpose of this creation is to provide a non-contact conveyor belt offset detection device.

According to the above purpose, the present invention provides a non-contact conveyor belt offset detection device, which is applied to a conveyor. The conveyor is provided with a conveyor belt, and the conveyor belt circulates between the inlet side and the outlet side of the conveyor. The conveyor has a support plate on the inlet side at the bottom of the conveyor belt, which is located in the standard mounting area of the support plate. The distance between the corresponding two edges of the standard installation area and the corresponding two edges of the conveyor belt is defined as the detection reference position. The non-contact conveyor belt deviation detection device includes a non-contact displacement detection unit. The non-contact displacement detection unit is set on the conveyor corresponding to the detection reference position. The non-contact displacement detection unit detects the conveyor belt If any edge of the conveyor moves to the detection reference position, an abnormal signal will be sent to the conveyor, and the conveyor will stop the operation of the conveyor belt according to the abnormal signal.

Among them, the non-contact displacement detection unit is provided with a height reference value, and the non-contact displacement detection unit detects that the height value between the detection reference position and the non-contact displacement detection unit is less than the height reference value, indicating that any edge of the conveyor belt has displaced to the detection reference position, and an abnormal signal is generated.

Wherein, the non-contact displacement detection unit includes a bracket and a laser displacement sensor. The support straddles the corresponding two edges of the conveyor and the conveyor belt. The two laser displacement sensors are set at the corresponding detection reference position. The laser displacement sensor emits laser light towards the detection reference position, and calculates the height value based on the reflected light of the laser light at the detection reference position, and generates an abnormal signal to the conveyor when the height value is less than the height reference value.

Among them, the distance between the laser displacement sensor and the support plate is the reference height value, and the relationship between the height reference value and the reference height value is expressed by the following formula: D=H0-T; while D is the height reference value, H0 is the reference height value, and T is the thickness of the conveyor belt.

Among them, the non-contact conveyor belt deviation detection device further includes an alarm unit, the alarm unit is connected to the non-contact displacement detection unit, the non-contact displacement detection unit judges that the height value is less than the height reference value, the non-contact displacement detection unit transmits the abnormal signal to the alarm unit, and the alarm unit sends out an alarm according to the abnormal signal.

D；則狀態指示模組產生表示輸送帶的任一邊緣位移到檢測基準位置的第一狀態訊號；在高度值屬於以下的第二狀態關係式：H<S<D；則狀態指示模組產生表示支撐板上有異物的第二狀態訊號；在高度值屬於以下的第二狀態關係式：S=H；則狀態指示模組產生表示輸送帶位於標準安裝區域內的第三狀態訊號。 Among them, the non-contact conveyor belt offset detection device also includes a status indication module, the status indication module is connected to the non-contact displacement detection unit, and the height value belongs to the following first state relationship: S

D; then the state indication module generates a first state signal indicating that any edge of the conveyor belt is displaced to the detection reference position; the height value belongs to the second state relational expression: H<S<D; then the state indication module generates a second state signal indicating that there are foreign objects on the support plate; the height value belongs to the following second state relational expression: S=H; then the state indication module generates a third state signal indicating that the conveyor belt is located in the standard installation area.

Among them, the two laser displacement sensors obtain the reference height value according to the time difference between emitting the laser light and receiving the support plate to reflect the laser light into the support plate reflected light, the speed of light and the refractive index of the light propagation medium.

Among them, the two laser displacement sensors are respectively provided with a laser light generator and a light sensor. The laser light generator and the light sensor are located directly above the detection reference position. The laser light, the path between the laser light generator and the light sensor, and the reflected light of the laser light form a triangle.

According to the above, the invention can improve the detection sensitivity of the conveyor belt deviation by using the optical non-contact displacement detection device, and can avoid the problem of dust generation caused by friction between the conveyor belt and the displacement detection device. This invention can also effectively detect conveyor belts that are prone to large deviations. In addition, the non-contact displacement detection device can detect the deviation of the conveyor belt more sensitively, but can still reduce the probability of false alarms and reduce the difficulty of adjusting the detection of the deviation of the conveyor belt.

1: Non-contact conveyor belt offset detection device

10: Non-contact displacement detection unit

100: Laser displacement sensor

1000: laser light generator

1001: Light sensor

11:Alarm unit

12: Status indication module

2: Conveyor

20: Entrance side

21: Exit side

22: Conveyor belt

220: Bottom

221: top surface

23: Support plate

24: Bracket

25: frame

26: Optical inspector

4: Foreign matter

A: area

D: altitude reference value

H: height value

H0: base height value

L1: laser light

L2: Support plate reflected light

L3: Conveyor Belt Reflected Light

L4: Reflected light from foreign matter

P: allowable offset distance

S: Detection reference position

SA: standard installation area

T: conveyor belt thickness

The first figure is a schematic diagram of the non-contact conveyor belt deviation detection device of the present invention using the time difference measurement method.

The second figure is a cross-sectional view of the conveyor belt in the standard installation area and the non-contact displacement detection unit viewed from between the optical inspector and the laser displacement sensor towards the laser displacement sensor when the conveyor belt is located in the standard installation area.

The third figure is a schematic diagram of the non-contact conveyor belt deviation detection device detecting the conveyor belt deviation.

Figure 4 is a cross-sectional view of the conveyor and the non-contact displacement detection unit viewed from between the optical inspector and the laser displacement sensor toward the laser displacement sensor when the conveyor belt deviates to the detection reference position.

The fifth figure is the block diagram of the non-contact conveyor belt deviation detection device of this creation.

Figure 6 is a schematic diagram of the non-contact conveyor belt deviation detection device of the present invention when a foreign object is detected.

The seventh figure is a schematic diagram of the non-contact conveyor belt deviation detection device of the present invention using the triangular geometry method.

Embodiments of the invention will be further explained below with the help of related drawings. Wherever possible, the same reference numerals have been used throughout the drawings and description to refer to the same or similar components. In the drawings, the shape and thickness may be exaggerated for the sake of simplification and convenient labeling. It is to be understood that elements not particularly shown in the drawings or described in the specification are those in the technical field. Has a form known to those skilled in the art. Those skilled in the art can make various changes and modifications based on the content of this creation.

Please refer to the first figure, which is a schematic diagram of the non-contact conveyor belt deviation detection device of the present invention using the time difference measurement method. The non-contact conveyor belt deviation detection device 1 of the present invention is applied to a conveyor 2, for example, the conveyor 2 is a printed matter inspection machine. The conveyor 2 is provided with a conveyor belt 22 which circulates between an inlet side 20 and an outlet side 21 of the conveyor 2 and which is provided with a support plate 23 at the bottom of the conveyor belt 22 at the inlet side 20 .

Under normal conditions, the conveyor belt 22 is located in the standard installation area SA of the support plate 23 . The allowable offset distance P between the two corresponding edges of the standard installation area SA and the corresponding two edges of the conveyor belt 22 is respectively defined as the detection reference position S.

In order to more clearly show the geometric structure of the conveyor 2 and the non-contact displacement detection unit 10 in the first figure, please refer to the second figure. The second figure is a cross-sectional view of the conveyor 2 and the non-contact displacement detection unit 100 as viewed from between the optical inspection device 26 and the laser displacement sensor 100 toward the laser displacement sensor 100 when the conveyor belt 22 is located in the standard installation area SA. In order to make the second figure as a whole more clear, however, the components at the inlet side 20 of the conveyor 2 are omitted from being shown.

The right border of the dotted line box in the second figure shows the situation where the conveyor belt 22 is shifted to the detection reference position S, for comparison with the position of the conveyor belt 22 located in the standard installation area SA.

In some embodiments, the non-contact conveyor belt deviation detection device 1 includes a non-contact displacement detection unit 10 . The non-contact displacement detection unit 10 is provided at a position close to the entrance side 20 of the conveyor 2 . The non-contact displacement detection unit 10 spans two sides of the conveyor belt 22 . Here, a bracket 24 is disposed above the conveyor belt 22 and the support plate 23 , so that the bracket 24 can be straddled on the conveyor 2 and the corresponding two edges of the conveyor belt 22 . For example, in the direction from the inlet side 20 to the outlet side 21, the support on both sides of the conveyor belt 22 Frames 25 are respectively arranged above the board 23 , and two opposite ends of the bracket 24 are respectively arranged on one of the two frames 25 . Or the frame 25 is arranged on the outside of the conveyor 2, and the height of the frame 25 is higher than the thickness of the conveyor belt 22, and the two opposite ends of the bracket 24 are respectively arranged on one of the two frames 25, and a fixing plate is provided on the bracket, and the fixing plate is used for installing the non-contact displacement detection unit 10.

The non-contact displacement detection unit 10 includes two laser displacement sensors 100 , and the two laser displacement sensors 100 are arranged at corresponding detection reference positions S. As shown in FIG. For the non-contact conveyor belt deviation detection device 1 using the time difference measurement method, since the two laser displacement sensors 100 are respectively arranged at opposite ends of the bracket 24, the laser light generator 1000 and the light sensor 1001 of the laser displacement sensor 100 are located directly above the detection reference position S, so that the laser displacement sensor 100 is perpendicular to the surface of the support plate 23, and is used to emit laser light to the detection reference position S and receive reflected laser light from the detection reference position S .

The laser displacement sensor 100 emits laser light L1 toward the detection reference position S. As shown in FIG. That is, in the first figure, the laser light L1 emitted by the laser light generator 1000 is incident on the detection reference position S of the support plate 23 .

Afterwards, the laser displacement sensor 100 calculates the height value according to the reflected light of the laser light L1 at the detection reference position S. If the conveyor belt 22 has not reached the abnormal offset position (also the detection reference position S) or there is no foreign object on the support plate 23, the height value is the reference height value H0, which is the distance between the laser displacement sensor 100 and the support plate 23.

In detail, the support plate 23 reflects the laser light L1 into the support plate reflected light L2 , and the support plate reflected light L2 returns to the light sensor 1001 . Since the time of emitting the laser light L1 is known, the laser displacement sensor 100 obtains the reference height value H0 according to the time difference between emitting the laser light L1 and receiving the reflected light L2 from the support plate, the speed of light, and the refractive index of the light propagation medium.

As shown in the third figure, and please also refer to the fourth figure, if the non-contact displacement detection unit 10 detects that any edge of the conveyor belt 22 is displaced to the detection reference position S, an abnormal signal is sent to the conveyor 2, and the conveyor 2 stops the operation of the conveyor belt 22 according to the abnormal signal.

In detail, taking the deviation of the conveyor belt 22 near the drawing side in FIG. 3 as an example, the edge of the offset side of the conveyor belt 22 reflects the laser light L1 to become the conveyor belt reflected light L3 , and the conveyor belt reflected light L3 returns to the light sensor 1001 . Since the time of emitting the laser light L1 is known, the laser displacement sensor 100 obtains the height value H at this time according to the time difference between emitting the laser light L1 and receiving the reflected light L3 from the conveyor belt, the speed of light, and the refractive index of the light propagation medium.

Further, the non-contact displacement detection unit 10 is provided with a height reference value D, and the non-contact displacement detection unit 10 detects that the height value H between the detection reference position S and the non-contact displacement detection unit 10 is less than the height reference value D, indicating that any edge of the conveyor belt 22 has displaced to the detection reference position S, and an abnormal signal is generated. Generally speaking, when the height value H is less than the height reference value D, the laser displacement sensor 100 generates an abnormal signal to the conveyor 2 .

Explained by the formula, the relationship between the height reference value D and the reference height value H0 is expressed by the following formula: D=H0-T; where, D is the height reference value, H0 is the reference height value, and T is the conveyor belt thickness.

Alternatively, when the non-contact displacement detection unit 10 takes the detection reference position S, the height between the support plate 23 and the non-contact displacement detection unit 10 as the offset center, the reference height H0 can be regarded as an offset value of 0, and the height reference value D can be regarded as a negative offset value T.

In this way, the non-contact displacement detection device of this invention can eliminate the insensitive problem of the conventional contact displacement detector, and also solve the conventional conveyor belt deflection caused by insufficient rigidity and excessive width. As a result, the conveyor belt is worn out, but the personnel don't know it and the conveyor can't stop the loss of the conveyor belt wear.

In addition, the non-contact displacement detection device of the present invention can detect the deviation of the conveyor belt without any contact with the conveyor belt, thus further reducing the friction loss of the conveyor belt. The adjustment of the non-contact displacement detection device to the conveyor belt deviation detection is also simpler and more convenient.

In addition, the non-contact displacement detection device installed near the entrance side of the conveyor can also effectively detect the conveyor belt that is prone to large deviations.

As shown in FIG. 5 , the non-contact conveyor belt deviation detection device 1 further includes an alarm unit 11 . The alarm unit 11 is connected to the non-contact displacement detection unit 10 . When the non-contact displacement detection unit 10 determines that the height H is less than the height reference value D, the non-contact displacement detection unit 10 transmits an abnormal signal to the alarm unit 11, and the alarm unit 11 issues an alarm according to the abnormal signal. For example, the alarm unit 11 is a light signal, a flashing light, a loudspeaker, a buzzer, etc., but the present invention is not limited thereto.

On the other hand, any edge of the conveyor belt 22 is not displaced to the detection reference position S, but a foreign object, such as debris, falls on the detection reference position S. In detail, as shown in FIG. 6 , the foreign object 4 reflects the laser light L1 into the foreign object reflected light L4 , and the foreign object reflected light L4 returns to the light sensor 1001 . Since the time of emitting the laser light L1 is known, the laser displacement sensor 100 obtains the height value H at this time according to the time difference between emitting the laser light L1 and receiving the reflected light L4 from the foreign object, the speed of light, and the refractive index of the light propagation medium.

In this way, in order to detect the deviation of the conveyor belt 22 more sensitively and reduce the probability of false alarms, the height reference value D can be set to the following conditions: H-T<D<H; for example, when H0 is 3cm and T is 0.19cm, the height reference value D can be set between 2.81cm and 3cm. In the above-mentioned offset value judging method, H0 is regarded as an offset value of 0, and D can be set between an offset value of 0m and -0.19cm. For example, D can be set to -0.15cm, that is, no alarm will be issued when debris below 0.15cm in height falls on the detection reference position S. However, if debris with a height of 0.15 cm or more is located on the detection reference position S with the conveyor belt 22 , an alarm will be issued.

D；則狀態指示模組12產生表示輸送帶22的任一邊緣位移到檢測基準位置S的第一狀態訊號。 Moreover, as shown in the fifth figure, the non-contact conveyor belt deviation detection device 1 also includes a status indication module 12, the status indication module 12 is connected to the non-contact displacement detection unit 10, and the height value H belongs to the following first state relationship: H

D ; then the state indication module 12 generates a first state signal indicating that any edge of the conveyor belt 22 is displaced to the detection reference position S.

When the height value H belongs to the following second state relationship: H0 < H <D; then the state indication module 12 generates a second state signal indicating that there is a foreign object 4 on the support plate 23.

When the height value H belongs to the following third state relationship: D = H ; then the state indication module 12 generates a third state signal indicating that the conveyor belt 22 is located in the standard installation area SA.

For example, the status indication module 12 is a status indicator, and the status indicator includes two lamps, and the two lamps are for example all off, one on and one off, and all on to represent the above first status signal to The third state signal, more specifically, the first state signal is that both lamps are off, the second state signal is that two lamps are on and one is off, and the third state signal is that both lamps are on.

As shown in FIG. 7 , the non-contact displacement detection unit 10 generates a height value by calculating according to the triangular geometry method according to the reflected light sensing data. In detail, the difference between the non-contact displacement detection unit 10 that calculates the height value by using the triangular geometry method and the above-mentioned non-contact displacement detection unit 10 with the vertical back-and-forth optical path lies in that the laser light L1, the path between the laser light generator 1000 and the light sensor 1001, and the reflected light form a triangle.

In this way, the distance from the laser light L1 reflected by the support plate 23 to the support plate reflected light L2 and then back to the photosensor 1001 is used as the reference, and there will be an optical path difference between the distance from the laser light L1 reflected by the conveyor belt 22 to the conveyor belt reflected light L3 back to the photosensor 1001, or the distance from the laser light L1 reflected by the foreign object 4 to the foreign object reflected light L4 back to the photosensor 1001. For example, the optical path difference can be used to calculate the height difference (height deviation value) between the support plate 23 and the conveyor belt 22, or to calculate the height difference (height deviation value) between the support plate 23 and the foreign object 4, and then detect whether any edge of the conveyor belt 22 or the foreign object 4 is displaced to the detection reference position S.

Alternatively, the position where the laser light L1 is reflected by the support plate 23 to become the reflected light L2 of the support plate and then returned to the photosensor 1001 is used as a reference, and there will be a position difference between the position where the laser light L1 is reflected by the conveyor belt 22 and becomes the reflected light L3 of the conveyor belt and returns to the photosensor 1001, or the position where the laser light L1 is reflected by the foreign object 4 and becomes the reflected light L4 of the foreign object and returns to the photosensor 1001. Therefore, the position difference can be calculated using triangular geometry to calculate the height difference (height deviation value) between the support plate 23 and the conveyor belt 22, or to calculate the height difference (height deviation value) between the support plate 23 and the foreign object 4, and then detect whether any edge of the conveyor belt 22 or the foreign object 4 is displaced to the detection reference position S.

To sum up, this invention can eliminate the problem of insensitivity of the contact displacement detector with the optical non-contact displacement detection device, so that the conveyor belt can stop running when the conveyor belt deviates from the friction machine wall. In addition, the non-contact displacement detection device of the present invention does not need to make any contact with the conveyor belt, thereby further reducing the friction loss of the conveyor belt.

Furthermore, since the non-contact displacement detection device is arranged near the entrance side of the conveyor, the non-contact displacement detection device can effectively detect the conveyor belt that is prone to large deviation. In addition, the non-contact displacement detection device of the present invention can detect the deviation of the conveyor belt more sensitively, but can still reduce the probability of false alarms and reduce the difficulty of adjusting the detection of the deviation of the conveyor belt. Therefore, this creation can greatly reduce the friction loss or friction damage of the conveyor belt, thereby ensuring the quality of printed matter inspection and saving the cost of conveyor belt maintenance and replacement.

The above is just an example to illustrate the preferred implementation of this creation, not to limit the scope of implementation. All simple replacements and equivalent changes made according to the patent scope of this creation application and the content of the patent specification all belong to the patent application category of this creation.

1: Non-contact conveyor belt offset detection device

10: Non-contact displacement detection unit

100: Laser displacement sensor

1000: laser light generator

1001: Light sensor

2: Conveyor

20: Entrance side

21: Exit side

22: Conveyor belt

220: Bottom

221: top surface

23: Support plate

24: Bracket

25: frame

26: Optical inspector

H: height value

H0: base height value

L1: laser light

L2: Support plate reflected light

P: allowable offset distance

S: Detection reference position

T: conveyor belt thickness

Claims (8)

A non-contact conveyor belt offset detection device is applied to a conveyor. The conveyor is provided with a conveyor belt. The conveyor belt circulates between an inlet side and an outlet side of the conveyor, and the conveyor is provided with a support plate at the bottom of the conveyor belt on the inlet side. The conveyor belt is located in a standard installation area of the support plate. The distance between two corresponding edges of the standard installation area and the corresponding two edges of the conveyor belt is defined as a detection reference position. : a non-contact displacement detection unit, the non-contact displacement detection unit is arranged on the conveyor corresponding to the detection reference position, the non-contact displacement detection unit detects that any edge of the conveyor belt is displaced to the detection reference position, and promptly generates an abnormal signal to the conveyor, and the conveyor stops the operation of the conveyor belt according to the abnormal signal. The non-contact conveyor belt deviation detection device as described in Claim 1, wherein the non-contact displacement detection unit is provided with a height reference value, and the non-contact displacement detection unit detects that a height value between the detection reference position and the non-contact displacement detection unit is less than the height reference value, indicating that any edge of the conveyor belt has displaced to the detection reference position, and the abnormal signal is generated. The non-contact conveyor belt deviation detection device as described in claim 2, wherein the non-contact displacement detection unit includes: a bracket straddling the conveyor on two corresponding edges of the conveyor belt; two laser displacement sensors, the two laser displacement sensors are arranged at the corresponding detection reference position, and the two laser displacement sensors emit a laser light towards the detection reference position, and calculate the height value based on the reflected light of the laser light at the detection reference position, and when the height value is smaller than the height reference value, the abnormality occurs signal to the conveyor. The non-contact conveyor belt deviation detection device as described in claim 3, wherein the distance between the two laser displacement sensors and the support plate is a reference height value, and the relationship between the height reference value and the reference height value is expressed by the following formula: D=H0-T; wherein, D is the height reference value, H0 is the reference height value, and T is the conveyor belt thickness. The non-contact conveyor belt deviation detection device as described in claim 4 further includes an alarm unit, the alarm unit is connected to the non-contact displacement detection unit, the non-contact displacement detection unit judges that the height value is less than the height reference value, the non-contact displacement detection unit transmits the abnormal signal to the alarm unit, and the alarm unit issues an alarm according to the abnormal signal. The non-contact conveyor belt deviation detection device as described in claim 4 further includes a status indication module connected to the non-contact displacement detection unit, and the height value belongs to the following first state relationship: H

D ; then the state indication module produces a first state signal indicating that any edge of the conveyor belt is displaced to the detection reference position; the height value belongs to a second state relational expression as follows: H0 < H <D; then the state indication module generates a second state signal representing foreign matter on the support plate; the height value belongs to the following second state relational expression: H = H0 ; then the state indication module generates a third state signal representing that the conveyor belt is located in the standard installation area. The non-contact conveyor belt deviation detection device as described in claim 4, wherein the two laser displacement sensors obtain the reference height value based on the time difference between emitting the laser light and receiving the support plate to reflect the laser light into the support plate reflected light, the speed of light and the refractive index of the light propagation medium. The non-contact conveyor belt deviation detection device as described in claim 4, wherein the two laser displacement sensors are respectively provided with a laser light generator and a light sensor, the laser light generator and the light sensor are located directly above the detection reference position, the laser light, the path between the laser light generator and the light sensor, and the reflected light of the laser light form a triangle. .