A photoelectric sensor with a light guide column

Abstract

The present invention is applicable to the field of sensor technology, and provides a photoelectric sensor with a light guide column, comprising: a light emitting portion, used for emitting a light beam to the outside, the light beam can be directed to an object moving from a distance to the sensor, the light beam generates scattered light on the surface of the object, and the scattered light returns to the sensor; a receiving lens, used for converging the returned scattered light and generating a light spot on a photoelectric sensor chip, the photoelectric sensor chip comprises adjacent photoelectric conversion plates 1 and 2; at least one light guide column, used for guiding the returned scattered light to the photoelectric conversion plate 1 or the photoelectric conversion plate 2; the present invention is provided with a light emitting portion, a receiving lens and a light guide column, in an area very close to the sensor, the light can be incident on the light guide column, undergo multiple internal reflections of the light guide column, and then generate effective signals on the photoelectric conversion plate 1 and the photoelectric conversion plate 2, which provides an optical path for the scattered light of an object particularly close to the photoelectric sensor, eliminating the blind spot.

Description

Technical Field

[0001] The invention belongs to the technical field of sensors, and in particular relates to a photoelectric sensor with a light guide column. Background Art

[0002] At present, background suppression sensors are widely used. This type of sensor will not affect the detection of objects outside the set detection distance. The principle is that the sensor emits a beam of light. If the beam encounters the detection object, it will produce reflected scattered light on the surface of the object. The scattered light returns to the sensor and is focused by the receiving lens to produce a light spot on the photoelectric sensor chip. The photoelectric sensor chip generally includes two photoelectric conversion plates close together; the axis of the receiving lens is at a distance from the emitted light beam. Therefore, it can be known from the ranging triangulation method that when the object moves closer or farther, the light spot will move from one photoelectric conversion plate to another photoelectric conversion plate, so the difference between the signals of the two photoelectric conversion plates can be used to determine whether an object exists.

[0003] When the object moves closer to the sensor, the light spot moves. As the distance between the object and the sensor decreases, the light spot will eventually move out of the photoelectric conversion board, resulting in a difference of zero. At this time, the sensor will not be able to detect whether there is an object. However, customers using the sensor often need to be able to detect whether there is an object at this time, because the object on the conveyor belt may be very close to the sensor.

[0004] In particular, when the object is close to the sensor at the millimeter level, after the light is emitted to the focusing lens, total reflection will occur inside the focusing lens at the rear surface of the focusing lens due to the large incident angle, causing all the light to be reflected back and overflow from the front surface or side of the focusing lens, and cannot be emitted to the photoelectric sensor chip at all.

[0005] The distance where the object is located is the blind area of ​​the photoelectric sensor. For smaller photoelectric conversion board sizes, this blind area will become larger. How to avoid or reduce this situation is a very important part of the design. Summary of the invention

[0006] The present invention provides a photoelectric sensor with a light guide column, aiming to solve the problem of blind areas in existing photoelectric sensors.

[0007] The present invention is implemented in this way: a photoelectric sensor with a light guide column comprises:

[0008] A light emitting part, used for emitting a light beam to the outside, wherein the light beam can be directed to an object moving from a distance to the sensor, and the light beam generates scattered light on the surface of the object, and the scattered light returns to the sensor;

[0009] A receiving lens, used to converge the returned scattered light and generate a light spot on the photoelectric sensor chip, wherein a distance is provided between the axis of the receiving lens and the light beam, and the photoelectric sensor chip comprises adjacent photoelectric conversion plates 1 and 2, used to convert the optical signal into an electrical signal;

[0010] At least one light guide column, used to guide the returned scattered light to the first photoelectric conversion plate or the second photoelectric conversion plate;

[0011] The light emitting part, receiving lens and photoelectric sensor chip are all installed in the sensor housing.

[0012] Preferably, the light emitting portion comprises a light source and a second lens, and the light emitted by the light source is converged by the second lens to form a light beam.

[0013] Preferably, the light source is an LED or a laser.

[0014] Preferably, a sensor incident window is further included, which is installed on the sensor housing and located on the path of the scattered light returning to the receiving lens. The sensor incident window is provided with a lens incident window directly facing the receiving lens.

[0015] Preferably, both side surfaces of the lens incident window are smooth surfaces.

[0016] Preferably, the outer side surface of the sensor incident window is a frosted surface, and the inner side surface is a frosted surface or a smooth surface.

[0017] Preferably, one end of the light guide column extends to the portion of the sensor incident window located below the lens incident window, and the other end extends close to the first photoelectric conversion plate or the second photoelectric conversion plate.

[0018] Preferably, the size of one end of the light guide column close to the photoelectric sensor chip is smaller than that of the other end.

[0019] Compared with the prior art, the embodiments of the present application have the following beneficial effects:

[0020] The present invention is provided with a light emitting part, a receiving lens and a light guide column. In an area very close to the sensor, light can be emitted into the light guide column, undergo multiple internal reflections of the light guide column, and then generate effective signals on the first photoelectric conversion board and the second photoelectric conversion board. This provides an optical path for the scattered light of objects that are particularly close to the photoelectric sensor, eliminating blind spots. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic structural diagram of an embodiment of the present invention;

[0022] Figure 2 Schematic diagram of the structure of the sensor incident window in an embodiment of the present invention.

[0023] Figure 3 Schematic diagram of the top view of the light guide column and the sensor incident window in the embodiment of the present invention.

[0024] Figure 4 It is a schematic diagram of the structure of an embodiment of the present invention in one state.

[0025] Figure 5 It is a schematic diagram of the structure of an embodiment of the present invention in another state.

[0026] Notes on figure marks: 1-light beam, 11-light emitting part, 111-light source, 112-lens 2, 2-object, 3-sensor housing, 31-receiving lens, 32-photoelectric conversion plate 1, 33-photoelectric conversion plate 2, 35-sensor incident window, 36-lens incident window, 41-light guide column. DETAILED DESCRIPTION

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by technicians in the technical field of this application; the terms used in the specification of the application herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, not to describe a specific order.

[0028] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0029] The embodiment of the present invention provides a photoelectric sensor with a light guide column 41, such as Figure 1-3 As shown, including:

[0030] The light emitting unit 11 is used to emit a light beam 1 to the outside. The light beam 1 can be emitted to an object 2 that moves from a distance to the sensor. The light beam 1 generates scattered light on the surface of the object 2, and the scattered light returns to the sensor. In this embodiment, it is preferred that the moving direction of the object 2 is directly opposite to the direction of the light beam 1. Specifically, the light emitting unit 11 includes a light source 111 and a second lens 112. The light emitted by the light source 111 is converged by the second lens 112 to form the light beam 1. The light source 111 is an LED or a laser. The light emitted by the LED or the laser is collimated and emitted through the lens, or it can be uncollimated to generate a light beam 1 with a certain divergence angle.

[0031] The receiving lens 31 is used to converge the returned scattered light and generate a light spot on the photoelectric sensor chip. A distance is set between the axis of the receiving lens 31 and the light beam 1. In this embodiment, the receiving lens 31 is preferably located above the light emitting portion 11. The photoelectric sensor chip includes adjacent photoelectric conversion plates 1 32 and 33, which are used to convert optical signals into electrical signals. Specifically, the photoelectric conversion plates 1 32 and 33 are adjacent to each other and the photoelectric conversion plates 1 32 are located above the photoelectric conversion plates 2 33.

[0032] At least one light guide column 41, used to guide the returned scattered light to the photoelectric conversion plate 1 32 or the photoelectric conversion plate 2 33. In this embodiment, preferably, there are two light guide columns 41, which are arranged in a V shape, with one end of the light guide column 41 close to the photoelectric conversion plate 1 32;

[0033] The light emitting unit 11, receiving lens 31 and photoelectric sensor chip are all installed in the sensor housing 3, and can be installed by screws, clamping, etc.;

[0034] When using, Figure 4 As shown, the light emitting unit 11 emits a light beam 1. If the light beam 1 encounters the detection object 2, reflected scattered light will be generated on the surface of the object 2. The scattered light returns to the sensor and enters the receiving lens 31. The receiving lens 31 converges the scattered light to first generate a light spot on the photoelectric sensor chip. There is a distance between the axis of the receiving lens 31 and the emitted light beam 1. Therefore, it can be known from the ranging triangulation method that when the object 2 moves closer, the light spot moves from the photoelectric conversion plate 2 33 to the photoelectric conversion plate 1 32. When the object 2 moves away, the light spot moves from the photoelectric conversion plate 1 32 to the photoelectric conversion plate 2 33. Therefore, it can be judged whether the object 2 exists by subtracting the difference between the photoelectric conversion plate 1 32 and the photoelectric conversion plate 2 33. Assuming that the light signal generates a positive electrical signal, the difference is positive, which means that the light intensity on the photoelectric conversion plate 1 32 is greater than that on the photoelectric conversion plate 2 33.

[0035] When the object 2 is far away, after the scattered light is focused, the main light flux is on the photoelectric conversion plate 2 33. The circuit compares the difference between the light flux on the photoelectric conversion plate 1 32 and the light flux on the photoelectric conversion plate 2 33. If the difference is negative, it indicates that there is no object 2 or the object 2 is far away and outside the detection range. Therefore, the object 2 beyond the detection distance will not interfere with the detection of the object 2 within the distance, that is, only the existence of the object 2 within the set distance is detected.

[0036] When object 2 moves closer to the sensor, the focused light spot formed by the scattered light moves from photoelectric conversion board 2 33 to photoelectric conversion board 1 32 on the photoelectric sensor chip. When the luminous flux on photoelectric conversion board 1 32 is greater than the luminous flux on photoelectric conversion board 2 33, the circuit compares the difference between the luminous flux on photoelectric conversion board 1 32 and the luminous flux on photoelectric conversion board 2 33. If the difference is positive, it is considered that object 2 exists.

[0037] like Figure 5 As shown, when the object 2 continues to move toward the sensor, the light spot moves out of the photoelectric conversion plate 32. When the object 2 is several centimeters or millimeters away from the sensor, the light enters the light guide column 41. In the light guide column 41, the light is continuously reflected for multiple times or not reflected at all to illuminate the photoelectric conversion plate. In this embodiment, the light guide column 41 is close to the photoelectric conversion plate 32, so the light intensity on the photoelectric conversion plate 32 is stronger, and the difference between the photoelectric conversion plate 32 and the photoelectric conversion plate 33 is positive, so it is judged that the object 2 exists, and the blind spot closest to the photoelectric sensor in the moving range of the object 2 is eliminated.

[0038] In a further preferred embodiment of the present invention, a sensor incident window 35 is also included, which is installed on the sensor housing 3 and is located on the path of the scattered light returning to the receiving lens 31. The sensor incident window 35 is provided with a lens incident window 36 that is directly opposite to the receiving lens 31. When the scattered light returns, it enters the receiving lens 31 through the lens incident window 36; in this embodiment, the light beam 1 passes through the sensor incident window 35; further, the surfaces on both sides of the lens incident window 36 are smooth surfaces, the outer side surface of the sensor incident window 35 is a frosted surface, and the inner side surface is a frosted surface or a smooth surface.

[0039] Preferably, one end of the light guide column 41 extends to the portion of the sensor incident window 35 located below the lens incident window 36, and the other end extends close to the photoelectric conversion plate 1 32 or the photoelectric conversion plate 2 33. In this embodiment, the other end of the light guide column 41 extends to the photoelectric conversion plate 1 32. When the object 2 is several centimeters or millimeters away from the sensor, the light enters the light guide column 41 after passing through the sensor incident window 35. In the light guide column 41, the light is continuously reflected multiple times or is not reflected before illuminating the photoelectric conversion plate. Preferably, the size of one end of the light guide column 41 close to the photoelectric sensor chip is smaller than the size of the other end.

[0040] In summary, the working principle of the present invention is as follows: after the light beam 1 is directed to the object 2, scattered light is generated on the rough surface of the object 2, and the scattered light returns to the sensor. The scattered light first passes through the receiving lens 31 of the sensor for focus, and the focused light beam 1 generates a light spot on the photoelectric sensor chip. When the object 2 is far away, after the scattered light is focused, the main light flux is on the photoelectric conversion board 2 33, and the circuit compares the difference between the light flux on the photoelectric conversion board 2 32 and the light flux on the photoelectric conversion board 1 33. When the difference is negative, it indicates that there is no object 2 or the object 2 is far away and out of the detection range. When the object 2 moves closer, the light spot moves from the photoelectric conversion board 2 33 to the photoelectric conversion board 1 32. When the photoelectric conversion board 2 32 is closer, the light spot moves from the photoelectric conversion board 2 33 to the photoelectric conversion board 1 32. When the luminous flux on photoelectric conversion plate 1 32 is greater than the luminous flux on photoelectric conversion plate 2 33, it is considered that object 2 exists. When object 2 continues to move toward the sensor, the light spot moves out of photoelectric conversion plate 1 32. When object 2 is several centimeters or millimeters away from the sensor, the light enters the light guide column 41 after passing through the sensor incident window 35. In the light guide column 41, the light is continuously reflected for multiple times or not reflected at all to illuminate the photoelectric conversion plate. Since light guide column 41 is relatively close to photoelectric conversion plate 1 32, the light intensity on photoelectric conversion plate 1 32 is stronger, and the difference between photoelectric conversion plate 1 32 and photoelectric conversion plate 2 33 is positive, thereby judging that object 2 exists, and thus eliminating the blind spot closest to the photoelectric sensor in the moving range of object 2.

[0041] It should be noted that, for the above-mentioned embodiments, for the sake of simplicity, they are all described as a series of action combinations, but those skilled in the art should know that the present invention is not limited by the described order of actions, because according to the present invention, some steps may be performed in other orders or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily required by the present invention.

[0042] In the several embodiments provided in the present application, it should be understood that the disclosed device can be implemented in other ways. For example, the device embodiments described above are only schematic, such as the division of the above-mentioned units, which is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or communication connection shown or discussed can be through some interfaces, and the indirect coupling or communication connection between devices or units can be in the form of telecommunication or other forms.

[0043] The units described above as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0044] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the scope of protection of the invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on these embodiments, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in this field can still combine, add, delete or make other adjustments to the features in the various embodiments of the present invention according to the circumstances without conflict, without making creative work, so as to obtain different other technical solutions that do not deviate from the concept of the present invention in essence, and these technical solutions also belong to the scope of protection of the present invention.

Claims

1. A photoelectric sensor with a light guide column, characterized in that: include: A light emitting part, used for emitting a light beam to the outside, wherein the light beam can be directed to an object moving from a distance to the sensor, and the light beam generates scattered light on the surface of the object, and the scattered light returns to the sensor; A receiving lens, used to converge the returned scattered light and generate a light spot on the photoelectric sensor chip, wherein a distance is provided between the axis of the receiving lens and the light beam, and the photoelectric sensor chip comprises adjacent photoelectric conversion plates 1 and 2, used to convert the optical signal into an electrical signal; At least one light guide column, used to guide the returned scattered light to the first photoelectric conversion plate or the second photoelectric conversion plate; The light emitting part, receiving lens and photoelectric sensor chip are all installed in the sensor housing; It also includes a sensor incident window, which is installed on the sensor housing and is located on the path of the scattered light returning to the receiving lens. The sensor incident window is provided with a lens incident window that is directly opposite to the receiving lens. Both side surfaces of the lens incident window are smooth surfaces. The outer side surface of the sensor incident window is a frosted surface, and the inner side surface is a frosted surface or a smooth surface. One end of the light guide column extends to the part of the sensor incident window located below the lens incident window, and the other end extends close to the photoelectric conversion board one or the photoelectric conversion board two.

2. The photoelectric sensor with a light guide column as claimed in claim 1, characterized in that: The light emitting part comprises a light source and a second lens, and the light emitted by the light source is converged by the second lens to form a light beam.

3. The photoelectric sensor with a light guide column as claimed in claim 2, characterized in that: The light source is an LED or a laser.

4. The photoelectric sensor with a light guide column as claimed in claim 1, characterized in that: The size of one end of the light guide column close to the photoelectric sensor chip is smaller than the size of the other end.

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