JP7483204B2 - Photoelectric Sensor - Google Patents

Description

The present invention relates to a photoelectric sensor.

Photoelectric sensors are used to measure the distance from the photoelectric sensor to the object to be detected, or to determine whether or not an object to be detected is present at a specified distance from the photoelectric sensor, by projecting detection light toward the object to be detected and detecting the reflected light.

For example, Patent Document 1 discloses a technology that uses multiple VCSELs (Vertical Cavity Surface Emitting LASERs) that emit spot beams as light sources to detect objects over a wide range.

JP 2019-67831 A

Detection of detection light by a photoelectric sensor is affected by the color and pattern or surface condition (roughness, deflection, etc.) of the object being detected. In order to prevent photoelectric sensors from being affected by the color and pattern of the object being detected, attempts have been made to use as small a spot beam as possible as the detection light. However, if the spot beam is small, the detection of the detection light is more likely to be affected by the surface condition of the object. For example, it may be difficult to detect the detection light when the object is highly rough.

One method that can be considered to suppress the effects of the color and pattern of the object being detected while also suppressing the effects of the surface condition is to use a thin, linear line beam as the detection light. This averages the effects of the surface condition of the object being detected across the width of the line beam (the length of the line), suppressing the effects of the surface condition of the object being detected on detection.

However, if the size of the object to be detected changes, it is necessary to change the settings of the optical system of the photoelectric sensor and adjust the length of the line beam, which is a time-consuming task.

The present invention aims to provide a photoelectric sensor that can more easily accommodate detection targets of various sizes.

A photoelectric sensor according to one aspect of the present invention is a photoelectric sensor for detecting an object to be detected, and includes a plurality of light sources that emit detection light, a light receiving unit that receives the detection light emitted by at least one of the plurality of light sources, and a control unit that controls the light emission by the plurality of light sources, in which the control unit selects at least two light sources from the plurality of light sources and causes the selected at least two light sources to emit light simultaneously, and the detection light emitted from the plurality of light sources has different light emission areas.

According to this aspect, the control unit can control the number of multiple light sources that emit detection light depending on the size of the detection object. In this case, there is no need to change the settings of the optical system provided in the photoelectric sensor, and it is possible to more easily accommodate detection objects of various sizes.

In the above embodiment, the multiple light sources may be electrically connected in parallel.

According to this aspect, the voltage applied to each of the light sources connected in parallel can be easily controlled. This makes it easier to select the light source to project light from.

In the above embodiment, the multiple light sources may be arranged along a virtual first straight line.

This aspect makes it possible to easily design the light receiving unit for receiving the detection light emitted by the light projecting unit.

In the above embodiment, the light receiving unit may include a light receiving element array having a plurality of light receiving elements arranged along a virtual second straight line, and the virtual first straight line and the virtual second straight line may intersect.

According to this aspect, since the virtual first straight line and the virtual second straight line intersect, the detection light emitted from one light source is prevented from being incident on the light receiving element array for receiving the detection light from another light source. As a result, it becomes possible to detect the detection target with greater accuracy.

In the above embodiment, the multiple light sources may be a VCSEL (Vertical Cavity Surface Emitting LASER) array.

According to this aspect, the light sources can be arrayed more easily. Therefore, it becomes possible to manufacture the photoelectric sensor more easily.

In the above aspect, the detection light emitted from the light source includes a first light in the visible light band and a second light in the infrared light band, and may further include a separation unit that separates the first light from the second light, and the light receiving unit may receive the separated second light.

According to this aspect, reception of the first light by the light receiving unit is suppressed, so that the light receiving unit is less susceptible to the effects of light in the visible light band, which is disturbing light. As a result, it is possible to detect the detection target with greater accuracy. In addition, because the first light is visible, the user can recognize the range in which the second light is projected onto the detection target based on the first light.

The present invention provides a photoelectric sensor that can more easily accommodate detection targets of various sizes.

1 is a functional block diagram showing a configuration of a detection system according to a first embodiment. 3 is a configuration diagram showing an example of a light projecting unit according to the embodiment. FIG. 1 is a diagram showing a state in which a photoelectric sensor projects one detection light toward a detection object; 1 is a diagram showing a state in which a photoelectric sensor projects three detection lights toward a detection object. FIG. FIG. 2 is a functional block diagram showing a configuration of a light receiving unit according to the first embodiment. 2 is a diagram showing a configuration of a light receiving unit according to the embodiment; FIG. FIG. 11 is a diagram illustrating an example of a gain adjustment table. 5 is a flowchart illustrating an example of a process when a light projection condition is set for the photoelectric sensor according to the first embodiment. 5 is a flowchart illustrating an example of a process performed when the photoelectric sensor according to the first embodiment detects a detection target. FIG. 11 is a functional block diagram showing a configuration of a photoelectric sensor according to a second embodiment. 10A and 10B are diagrams illustrating an example of a state in which detection light and guide light are projected onto a detection target; 10A and 10B are diagrams illustrating an example of a state in which detection light and guide light are projected onto a detection target;

A preferred embodiment of the present invention will be described with reference to the attached drawings. In each drawing, the same reference numerals are used to denote the same or similar configurations.

[First embodiment]
1 is a diagram showing the configuration of a detection system according to an embodiment of the present invention. The detection system according to this embodiment determines the presence or absence of a detection target and outputs the determination result, and mainly includes an input unit 110, a photoelectric sensor 10, and an output unit 30.

The input unit 110 can receive input operations from a user and generate an input signal. The input unit 110 may include a device for receiving various input operations, such as a button, a keyboard, a mouse, a touch panel, or a switch. The input unit 110 may receive, for example, an operation for selecting a light source from which the photoelectric sensor 10 will project light, or an operation for selecting the number of light sources to project light. The input unit 110 may generate an input signal according to the received operation, and may transmit the input signal to the photoelectric sensor 10 using, for example, IO-LINK communication.

The input unit 110 can set each light source to ON or OFF individually, for example, depending on the number of light sources provided in the photoelectric sensor 10. The input unit 110 may receive button operation from the user, select ON or OFF for multiple light sources, and generate an input signal representing the selection result. Alternatively, the input unit 110 may specify ON or OFF using a bit pattern (1: ON, 0: OFF) according to the number of light sources by a communication command, and transmit the specified result to the photoelectric sensor 10.

In addition, the input unit 110 may have preregistered ON/OFF patterns of light sources that are expected to be used frequently. In this case, the input unit 110 may select a bit pattern through a selection operation by the user, and transmit the selected bit pattern to the photoelectric sensor 10. Here, the selection operation may be, for example, an operation of a button provided on the input unit 110, or an operation of inputting a communication command.

Here, three bit patterns are illustrated for a case where there are nine light sources. Here, the nine light sources are described as being arranged at equal intervals from the left end to the right end on a straight line connecting the two ends (the left end and the right end). In the bit patterns shown here, 1 corresponds to ON and 0 corresponds to OFF. For example, a bit pattern that turns all nine light sources ON is "111111111". A bit pattern that turns two light sources on each end of the nine light sources OFF and turns the five central light sources ON is "001111100". A bit pattern that turns only one central light source ON and all the remaining light sources OFF is "000010000".

The bit pattern is not limited to these examples, and any bit pattern may be set as appropriate by the user's operation. The user can select one bit pattern from the set bit patterns according to the size of the type of object to be detected, and select the light source to project light. At this time, the operation of selecting the bit pattern may be an operation of pressing a button on the input unit 110, an operation of inputting a communication command to the input unit 110, or an operation of giving an instruction via an external line connected to the input unit 110.

The user can also select the location of the light projection depending on the position of the object on the line along which the object moves, or the location of the detection target. Here, too, the explanation is given assuming that there are nine light sources arranged in a straight line. When the object 10 passes through a location to the left of the location where the photoelectric sensor 10 is installed, for example, a bit pattern of "010000000" that turns on only the second light source from the left end may be used. When the object 10 passes through the center of the location where the photoelectric sensor 10 is installed, a bit pattern of "000010000" that turns on only the central light source may be used. Furthermore, when the object 10 passes through a location to the right of the location where the photoelectric sensor 10 is installed, a bit pattern of "000000010" that turns on only the second light source from the right end may be used.

The input unit 110 may have a function for detecting an image. Based on this function, the input unit 110 may detect, for example, the size of the object to be detected, and generate an input signal for specifying a light source to project light according to the size.

The photoelectric sensor 10 according to this embodiment is a triangulation type photoelectric sensor that can simultaneously project detection light from multiple light sources and receive the detection light reflected by a detection object 20 located at a predetermined distance from the photoelectric sensor 10. The photoelectric sensor 10 can determine that a detection object is present when it receives detection light, and can determine that a detection object is not present when it does not receive detection light. The photoelectric sensor 10 may also be a distance setting type photoelectric sensor that can determine the distance to the detection object 10. The photoelectric sensor 10 can output the determination result to the output unit 30.

The output unit 30 may be any of a variety of output devices, such as a liquid crystal display. The output unit 30 can output various types of information. The output unit 30 may display, for example, the determination result of the photoelectric sensor 10.

As shown in FIG. 1, the photoelectric sensor 10 includes a control unit 120, a light-projecting unit 130, a light-receiving unit 140, a light-projecting lens 150, and a light-receiving lens 152.

The control unit 120 may be configured, for example, by a CPU (Central Processing Unit). The control unit 120 can control the operation of the light projecting unit 130 and the light receiving unit 140 based on an input signal. More specifically, the control unit 120 can select at least two light sources from among the multiple light sources provided in the light projecting unit 130, and can cause the selected at least two light sources to project light simultaneously.

The light-projecting unit 130 can project detection light. The light-projecting unit 130 has a light-projecting section including a plurality of light sources. Each of the plurality of light sources can project a spot beam as detection light. Each of the plurality of light sources may be, for example, various types of semiconductor lasers such as VCSELs. Furthermore, the plurality of light sources may be arrayed, and by using VCSELs as the light sources, it is possible to easily array the plurality of light sources.

Figure 2 is a configuration diagram showing an example of the light projecting unit 132 according to this embodiment. As shown in Figure 2, the light projecting unit 132 includes three anode electrodes 134a-c, three light sources 136a-c, and a grounded cathode electrode 138. In the light projecting unit 132 according to this embodiment, the light sources 136a-c are arranged along a straight line in the x-axis direction (a first imaginary line 160 shown by a dashed line). Note that the centers of these light sources 136a-c do not all need to be located on the first imaginary line 160, and the centers of the light sources 136a-c may be shifted from the first imaginary line 160 as long as the detection target can be detected.

These light sources 136 are electrically connected in parallel. In this manner, in this embodiment, since the multiple light sources 136 are electrically connected in parallel, the voltage applied to each of the multiple light sources 136 can be easily controlled. As a result, it is possible to easily control whether the multiple light sources 136 emit light or not, and to easily select the light source 136 that emits light.

When a predetermined voltage is applied between the anode electrode 134 and the cathode electrode 138, the light source 136 emits detection light. In this embodiment, the multiple light sources 136 can emit detection light simultaneously. The emitted detection light passes through the light-emitting lens 150 and is emitted from the photoelectric sensor 10 toward the detection object 20. At this time, the projection areas of the detection light emitted from the multiple light sources 136 are different from one another. In other words, the areas of the multiple detection lights irradiated onto the surface of the detection object do not overlap with one another.

In addition, the light source to be used for emitting light can be selected by selecting the light source 136 to which a voltage is applied. For example, a switch or the like may be provided for each of the light sources 136a-c, and the control unit 120 may control whether each of the light sources 136a-c emits light or not by switching the switch on/off.

The light projecting unit 132 according to this embodiment is provided with three light sources 136a-c, but the number of light sources provided in the light projecting unit 132 may be two, or may be four or more. In addition, in FIG. 2, the three light sources 136a-c are connected at a connection point 137, but this is not limited thereto, and each light source 136 may be connected directly to the cathode electrode 138 without going through the connection point 137.

Figures 3 and 4 show an example of how detection light is projected by the photoelectric sensor 10 toward the object to be detected.

The photoelectric sensor 10 can change the number of detection lights to be projected depending on the size of the detection object. In FIG. 3, the photoelectric sensor 10 projects one detection light 40 toward the detection object 22. In FIG. 4, the photoelectric sensor 10 simultaneously projects three detection lights 42 toward the detection object 24. In the example shown in FIG. 4, the photoelectric sensor 10 determines the presence or absence of a detection object 24 that is larger than the detection object 22 detected in FIG. 3. In this way, the photoelectric sensor 10 according to this embodiment can select a light source to project depending on the size of the detection object. In this embodiment, when changing the number of detection lights, there is no need to take the time to change the settings in the optical system of the photoelectric sensor 10, so it is possible to easily accommodate various sizes of detection objects.

In addition, by reducing the spot size of the detection light, the influence of the color and pattern of the object to be detected can be suppressed. Furthermore, by simultaneously projecting detection light from multiple light sources so that the multiple light projection areas are different from one another, the influence of the surface condition of the object to be detected can be suppressed. Therefore, the photoelectric sensor 10 according to this embodiment can easily accommodate detection objects of various sizes while suppressing the influence of the color and pattern and surface condition of the object to be detected.

Figure 5 is a functional block diagram showing the configuration of the light receiving unit 140 according to this embodiment. As shown in Figure 5, the light receiving unit 140 includes a light receiving section 142, a gain adjustment section 144, and a signal processing section 146.

The light receiving unit 142 can receive detection light emitted by at least one of the multiple light sources. More specifically, the light receiving unit 142 can receive detection light reflected by the detection object 20 through the light receiving lens 152. The light receiving unit 142 may, for example, include a plurality of light receiving element arrays having a plurality of light receiving elements arranged along a predetermined straight line. More specifically, the light receiving unit 142 may, for example, include a light receiving element array such as a multi-segment photodiode, or may include a one-dimensional CMOS (Complementary Metal Oxide Semiconductor) imaging element array. When the photoelectric sensor 10 is a distance setting type, the light receiving unit 142 may be composed of a two-segment photodiode. Here, one of the two-segment photodiodes is also referred to as the N (Near) side, and the other is also referred to as the F (Far) side. At this time, the position of the two-segment photodiode can be adjusted so that when the distance from the photoelectric sensor 10 to the detection object 20 is closer than a predetermined distance, the amount of light on the N side is greater than the amount of light on the F side, and when the distance from the photoelectric sensor 10 to the detection object 20 is farther than a predetermined distance, the amount of light on the F side is greater than the amount of light on the N side. When the light receiving unit 142 receives the detection light, it generates a light receiving signal according to the amount of light of the received detection light, etc., and transmits it to the gain adjustment unit 144.

FIG. 6 is a diagram showing an example of a light receiving element provided in the light receiving unit 142 according to this embodiment. As shown in FIG. 6, a six-segment photodiode 143 is arranged in the light receiving unit 142. The six-segment photodiode 143 receives the detection light 139a-c projected by the three light sources 136a-c provided in the light projecting unit 130. The six-segment photodiode 143 has six photodiodes along a straight line (a second imaginary line 162 shown by a dashed line) in the y-axis direction perpendicular to the x-axis. FIG. 6 shows a virtual line 161 parallel to the first imaginary line 160. Here, the second imaginary line 162 intersects (more specifically, perpendicular to) the virtual line 161. Therefore, the six-segment photodiode 143 can receive the detection light from the light sources 136a-c, and the effect on detection due to the surface condition of the inspection object is averaged, thereby making it possible to detect the detection object more accurately. Note that, although the multi-segment photodiode 143 has been described here as having six divisions, the number of divisions of the multi-segment photodiode is not limited to this. Also, although the light receiving unit 142 has been described here as having one light receiving element array (six-segment photodiode 143), the light receiving unit 142 may have multiple light receiving element arrays. For example, the light receiving unit 142 may have image sensor arrays in a number corresponding to the number of light sources.

Returning to FIG. 5, the configuration of the light receiving unit 140 will be described. The gain adjustment unit 144 has a function of performing gain adjustment according to the control by the control unit 120. Specifically, the gain adjustment unit 144 performs gain adjustment according to the number of light sources that project light. The control unit 120 holds a gain adjustment table as shown in FIG. 7 as an internal parameter. The gain adjustment table records gain setting values according to the number of light sources that project light. More specifically, the gain setting value is set so as to be approximately inversely proportional to the number of light sources that project light. The control unit 120 transmits the gain setting value to the gain adjustment unit 144 based on the gain adjustment table. The gain adjustment unit 144 performs gain adjustment of the light receiving signal based on the gain setting value, and generates an adjusted signal. For example, the gain adjustment unit 144 may generate an adjusted signal by adjusting the resistance in an amplifier circuit (not shown) using an operational amplifier according to the gain setting value and amplifying the light receiving signal. The generated adjusted signal is transmitted to the signal processing unit 146.

The signal processing unit 146 can perform various processes on the various acquired signals. For example, the signal processing unit 146 generates a light projection signal for the light source to project detection light based on the control signal, and transmits the signal to the light projection unit 130. This controls the light projection of the light projection unit 130. In this way, in this embodiment, the control unit 120 can control the projection of detection light by the light projection unit 130 via the signal processing unit 146.

The signal processing unit 146 can also generate a judgment result based on the adjusted signal and transmit it to the output unit 30. The signal processing unit 146 can, for example, compare the adjusted signal with a threshold value and generate a judgment result regarding the presence or absence of an object to be detected based on the comparison result. In addition, when the photoelectric sensor 10 is a distance setting type and the light receiving unit 142 is a two-segment photodiode, the signal processing unit 146 can determine whether the object to be detected 20 is farther than a predetermined distance depending on the magnitude relationship of the light amount between the two regions (N side and F side). Thus, in this embodiment, the signal processing unit 146 functions as a judgment unit.

Figure 8 is a flowchart showing an example of processing when setting light projection conditions for the photoelectric sensor 10 according to this embodiment. Below, an example of processing in the photoelectric sensor 10 will be explained according to the flowchart in the figure.

First, the input unit 110 of the photoelectric sensor 10 accepts input from a user (step S101). For example, the input unit 110 accepts an operation of pressing a button to set the projection of detection light from three light sources. The input unit 110 transmits an input signal corresponding to the operation to the control unit 120 as a projection condition.

Next, the control unit 120 switches the light projection conditions (step S103). For example, based on the input signal, the control unit 120 transmits a control signal to the gain adjustment unit 144 and the signal processing unit 146 to cause the three light sources provided in the light projection unit 130 to project detection light. This causes the light projection conditions to be switched according to the light projection conditions input in step S101.

Next, the gain adjustment unit 144 performs gain adjustment based on the gain setting value (e.g., 16.7 kΩ) using the gain adjustment table described with reference to FIG. 7.

Above, an example of the processing when the light projection conditions are set in the photoelectric sensor 10 has been described. Next, with reference to FIG. 9, an example of the processing when the photoelectric sensor 10 detects the detection target 20 will be described. FIG. 9 is a flowchart showing an example of the processing when the photoelectric sensor 10 according to this embodiment detects the detection target 20. The processing shown in FIG. 9 may be started, for example, when the input unit 110 receives an operation to start light projection.

First, the signal processing unit 146 generates a light projection signal based on the set light projection conditions (step S201). Here, the signal processing unit 146 generates a light projection signal for the three light sources to project detection light, and transmits the signal to the light projection unit 130.

Next, the light-projecting unit 130 projects detection light based on the light-projecting signal (step S203). For example, the light-projecting unit 130 causes three light sources to simultaneously project detection light. When the detection target 20 is present at a predetermined position, the projected detection light is reflected by the detection target 20.

Next, the light receiving section 142 of the light receiving unit 140 receives the detection light reflected by the detection object 20 via the light receiving lens 152 (step S205). When the light receiving section 142 receives the detection light, it generates a light receiving signal and transmits it to the gain adjustment section 144. The gain adjustment section 144 amplifies the light receiving signal and transmits the adjusted signal to the signal processing section 146.

Next, the signal processing unit 146 generates a determination result based on the adjusted signal (S207). For example, the signal processing unit 146 generates a determination result indicating that the object to be detected 20 is present. Alternatively, the signal processing unit 146 may determine whether the object to be detected 20 is farther than a predetermined distance and generate a determination result. The signal processing unit 146 transmits the generated determination result to the output unit 30.

Next, the output unit 30 outputs the determination result (step S209). For example, the output unit 30 may display text information indicating that the detection target object 20 has been detected.

The above describes the processing of the photoelectric sensor 10 according to this embodiment. According to this embodiment, the control unit 120 selects at least two light sources from among the multiple light sources provided in the light-projecting unit 132 of the light-projecting unit 130, and causes the selected at least two light sources to project light simultaneously. At this time, the projection areas of the detection light projected by these light sources are different from each other. According to this embodiment, since there is no need to change the settings of the optical system of the photoelectric sensor 10 when changing the light source to be projected, it is possible to easily change the range into which the detection light is projected. As a result, it becomes possible to more easily accommodate detection targets of various sizes.

In addition, with the photoelectric sensor 10 according to this embodiment, detection light can be projected from more light sources onto a larger detection object. As a result, the effect of the surface condition of the detection object is averaged out, making it possible to detect the detection object with greater accuracy.

In addition, according to this embodiment, because a spot beam is used as the detection light, there is no need to use the complex optical system required to realize a line beam. Therefore, the photoelectric sensor 10 according to this embodiment can be manufactured using a simpler optical system.

In addition, if the photoelectric sensor 10 is a distance setting type and the light receiving section 142 is a two-part photodiode, when the spot size of the detection light becomes large, excess reflected light enters the two areas of the two-part photodiode. Therefore, if the object to be detected 20 has a color or pattern, the amount of reflected light due to the color or pattern becomes noise, affecting the balance of the amount of light in the two areas. Therefore, by making the spot beam smaller and reducing the probability that the balance will be affected, the effect of the color or pattern of the object to be detected can be reduced, and the object to be detected 20 can be detected more accurately.

[Second embodiment]
In the second embodiment, a description of matters common to the first embodiment will be omitted, and differences will be mainly described.

Figure 10 is a functional block diagram showing the configuration of a photoelectric sensor 12 according to the second embodiment. Unlike the photoelectric sensor 10 according to the first embodiment, the photoelectric sensor 12 according to the second embodiment includes a separation section 153. The separation section 153 includes a filter that transmits only light of a specific wavelength.

The light source provided in the light-projecting unit 131 according to the second embodiment projects guide light in addition to detection light. Specifically, the light source projects light in the infrared band (hereinafter also simply referred to as "infrared light") as detection light, and light in the visible light band (hereinafter also simply referred to as "visible light") as guide light. The visible light may be, for example, red light. Infrared light also includes light having a wavelength of about 850 to 950 nm.

In this embodiment, the control unit 120 transmits to the signal processing unit 146 not only a control signal for controlling the projection of detection light by the light source provided in the light projection unit 130, but also a control signal for controlling the projection of guide light by the light source. Specifically, the control unit 120 associates a light source that projects detection light with a light source that projects guide light that satisfies a predetermined positional relationship with the light source, and controls the projection of the light sources so that the associated light sources project light in conjunction with each other.

In this embodiment, the detection light and the guide light are alternately projected onto the inspection target 10. The control unit 120 associates a light source that projects the detection light with a light source that projects a guide light adjacent to the light source, and controls the light source so that the associated light sources project light in conjunction with each other. In other words, when a light source that projects a certain detection light is selected, a light source that projects a guide light adjacent to the light source is also selected, and the detection light and the guide light adjacent to each other are simultaneously projected. This allows the user to check whether or not the light source that projects the detection light has been selected for each light source. In other words, the user can check which light source is projecting the detection light. At this time, the gain adjustment may be performed in conjunction with the projection of the guide light. For example, the gain adjustment may be performed according to the number of light sources that project the guide light.

With reference to Figures 11 and 12, an example of how detection light and guide light are projected onto the surface of a detection object will be described. In Figure 11, five detection light projection areas (first light projection areas 400) and ten guide light projection areas (second light projection areas 402) are shown on the surface 200 of the detection object. Second light projection areas 402 are shown above and below each of the five first light projection areas 400. As shown in Figure 11, the detection light is projected so that the five first light projection areas 400 do not overlap each other.

In this embodiment, since the detection light is infrared light, the user cannot see the first light projection area 400, but can infer the projection area of the detection light by seeing the second light projection area 402 using visible light. In particular, when the number of detection lights projected changes, the user can easily infer the range into which the detection light is projected.

Also, as shown in FIG. 12, the detection light and the guide light may be projected so that the detection light projection area (first light projection area 404) and the guide light projection area (second light projection area 406) are alternately aligned in a straight line.

The detection light projection area and the guide light projection area are not limited to the areas shown in FIG. 11 or FIG. 12. The spacing between the multiple first light projection areas can be designed as appropriate. For example, the detection light may be projected by multiple light sources so that the multiple first light projection areas are in contact with each other. Furthermore, the multiple second light projection areas may overlap each other.

Returning to FIG. 10, the configuration of the photoelectric sensor 12 according to the second embodiment will be described. When the detection light and guide light reflected by the object to be detected 20 enter the photoelectric sensor 12, the guide light is blocked by the separator 153, and mainly the detection light passes through the light receiving lens 152 and is received by the light receiving unit 141. The light receiving unit 141 can determine the presence or absence of the object to be detected 20 based on the received detection light.

According to the photoelectric sensor 12 of the second embodiment described above, the light receiving unit 141 receives infrared light as detection light and determines the presence or absence of the detection object 20. This prevents visible light from being received as disturbance light, making it possible to more accurately determine the presence or absence of the detection object 20. In addition, by recognizing the guide light, which is visible light, the user can easily estimate the change in the range in which the detection light is projected when the light source to be projected is changed.

The above-described embodiments are intended to facilitate understanding of the present invention, and are not intended to limit the present invention. The elements of the embodiments, as well as their arrangement, materials, conditions, shapes, sizes, etc., are not limited to those exemplified, and may be modified as appropriate. In addition, configurations shown in different embodiments may be partially substituted or combined.

In the above embodiment, the photoelectric sensor 10 has been described as determining whether or not an object to be detected is present at a position a predetermined distance away from the photoelectric sensor 10. However, the photoelectric sensor is not limited to this, and may be any of various photoelectric sensors that use a triangulation method, such as a displacement sensor that can detect the displacement of an object to be detected.

In the above embodiment, an example in which three light sources 136a-c are connected in parallel has been described. However, this is not limiting, and some of the light sources may be connected in series. In this case, these some of the light sources connected in series may be configured to simultaneously emit light or not emit light.

In the above embodiment, the gain adjustment unit 144 adjusts the gain according to the number of light sources that project light. Alternatively, the time for which the light source projects light or the power (current flowing through the light source) may be changed according to the number of light sources that project light. The time for which the light receiving unit 142 receives light may be adjusted by adjusting the time for which a shutter (not shown) provided in the light receiving unit 142 is opened according to the number of light sources that project light. The light receiving unit may also change a threshold value for determining the presence or absence of a detection target according to the number of light sources that project light.

In addition, in the above embodiment, an example was described in which the virtual first line 160 and the virtual second line 162 are perpendicular to each other, but the virtual first line and the virtual second line do not have to be perpendicular to each other, and it is sufficient that the virtual first line and the virtual second line intersect within a range where the detection light can be detected.

[Appendix 1]
A photoelectric sensor (10, 12) for detecting a detection object (20, 22, 24),
A plurality of light sources (136) for projecting detection light (40, 42);
a light receiving unit (142) that receives the detection light (40, 42) emitted by at least one of the plurality of light sources (136);
A control unit (120) that controls light projection by the plurality of light sources (136);
Equipped with
The control unit (120) selects at least two of the light sources (136) from among the plurality of light sources (136) and causes the selected at least two light sources (136) to project light simultaneously;
The detection light (40, 42) projected from the plurality of light sources (136) has different projection areas.
Photoelectric sensor (10, 12).

[Appendix 2]
The plurality of light sources (136) are electrically connected in parallel.
2. The photoelectric sensor (10, 12) according to claim 1.

[Appendix 3]
The plurality of light sources (136) are arranged along an imaginary first straight line.
3. The photoelectric sensor (10, 12) according to claim 1 or 2.

[Appendix 4]
The light receiving section (142) includes a light receiving element array (143) having a plurality of light receiving elements arranged along a virtual second straight line,
The first imaginary line and the second imaginary line intersect with each other.
4. The photoelectric sensor (10, 12) according to claim 3.

[Appendix 5]
The plurality of light sources (136) includes a VCSEL (Vertical Cavity Surface Emitting LASER) array;
A photoelectric sensor (10, 12) according to any one of appendixes 1 to 4.

[Appendix 6]
the detection light (40, 42) emitted from the light source (136) includes a first light in a visible light band and a second light in an infrared light band;
Further comprising a separation unit (153) that separates the first light and the second light,
The light receiving unit (142) receives the separated second light.
A photoelectric sensor (10, 12) according to any one of appendixes 1 to 5.

10, 12...photoelectric sensor, 20, 22, 24...detection object, 30...output section, 40, 42...detection light, 110...input section, 120...control section, 130, 131...light projecting unit, 132...light projecting section, 134...anode electrode, 136...light source, 137...connection point, 138...cathode electrode, 140, 141...light receiving unit, 142...light receiving section, 143...light receiving element array, 144...gain adjustment section, 146...signal processing section, 150...light projecting lens, 152...light receiving lens, 153...separation section, 160...virtual first straight line, 162...virtual second straight line, 200...surface, 40, 42...detection light, 400, 404...first light projecting area, 402, 406...second light projecting area

Claims (6)

A photoelectric sensor for detecting a detection target,
A plurality of light sources for projecting detection light;
a light receiving unit that receives the detection light projected by at least one of the plurality of light sources;
A control unit that controls light projection from the plurality of light sources;
A photoelectric sensor comprising:
an input unit that receives an operation for selecting the number of light sources to project light and generates an input signal in accordance with the operation;
Equipped with
the control unit selects at least two of the light sources from among the plurality of light sources based on the input signal, and causes the selected at least two light sources to project light simultaneously;
The detection light projected from the plurality of light sources has different projection areas.
Detection system . The plurality of light sources are electrically connected in parallel.
The detection system of claim 1 . The plurality of light sources are arranged along a virtual first straight line.
3. A detection system according to claim 1 or 2. the light receiving unit includes a light receiving element array having a plurality of light receiving elements arranged along an imaginary second straight line;
The first imaginary line and the second imaginary line intersect with each other.
The detection system of claim 3 . The plurality of light sources include a VCSEL (Vertical Cavity Surface Emitting LASER) array;
A detection system according to any one of claims 1 to 4. the detection light emitted from the light source includes a first light in a visible light band and a second light in an infrared light band;
a separation unit that separates the first light and the second light,
The light receiving unit receives the separated second light.
A detection system according to any one of claims 1 to 5.

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