Optical sensor

Abstract

To provide an optical sensor that can reduce stray light. [Solution] The optical sensor (100) comprises a light-emitting unit (11) including a light source (12) that emits light and a light-emitting lens (16) configured to concentrate the light from the light source (12), a light-receiving unit (21) that receives light, and a detection unit (40) that detects an object (TA) based on the received light, wherein the light-emitting unit (11) further includes a package (13) on which the light source (12) is installed at the bottom surface (13b) of a formed recess (13a), and a light-transmitting resin (14) that covers the light source (12), and the side surface (13c) of the recess (13a) includes a material that absorbs the light from the light source (12).

Description

Technical Field

[0001] The present invention relates to an optical sensor.

Background Art

[0002] As optical sensors, there are generally a type that detects an object based on the amount of received light and a type that converts the received light amount distribution into an object position to detect the object. As a specific example of the latter type, when a received light amount distribution is obtained and a plurality of maxima are detected in the received light amount distribution, it is determined that multiple reflections have occurred and it is determined that an object is present. On the other hand, even when no maximum value is detected, it is determined that an object is present because the state has changed. Also, even if the number of maximum values is one, if the position of the peak exceeds the threshold range, it is determined that an object is present. Furthermore, it is known that even when the width of the received light waveform exceeds the specified range, it is determined that an object is present (see Patent Document 1). This optical sensor can execute control according to the presence or absence of multiple reflections by detecting the presence or absence of multiple reflections based on the received light amount distribution and outputting a signal related to the presence or absence of multiple reflections.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Conventionally, in the light projecting section of an optical sensor, a packaged product including a light source and a package, which is widely distributed in the market, has been used.

[0005] However, when such packaged products are used as is, light from the light source is reflected off the package, resulting in unintended light, or stray light, being generated. Conventionally, measures such as reducing the light output of the light source were taken to prevent this stray light from affecting the performance of the optical sensor. As a result, conventional measures led to a decrease in the signal-to-noise ratio (hereinafter also referred to as "S / N ratio").

[0006] This invention has been made in view of these circumstances, and one of its objectives is to provide an optical sensor that can reduce stray light. [Means for solving the problem]

[0007] An optical sensor according to one aspect of the present disclosure comprises a light-emitting unit including a light source that emits light and a light-collecting element configured to collect light from the light source; a light-receiving unit that receives light; and a detection unit that detects an object based on the received light, wherein the light-emitting unit further includes a package on which the light source is installed at the bottom surface of a formed recess, and a light-transmitting resin that covers the light source, and the side surface of the recess includes a material that absorbs light from the light source.

[0008] According to this embodiment, the light-emitting section further includes a package on which a light source is installed at the bottom of a formed recess, and a light-transmitting resin that covers the light source, and the side surface of the recess contains a material that absorbs light from the light source. As a result, light incident on the side surface from the light source installed at the bottom surface is absorbed, making it possible to absorb stray light, which is the main cause of stray light and whose generation path includes the side surface. Therefore, stray light can be reduced and a decrease in the signal-to-noise ratio can be suppressed. In addition, the visibility of the spot of main light illuminating an object can be improved.

[0009] In the embodiment described above, the side surface is connected to the bottom surface, and the angle between it and the bottom surface may be greater than 90 degrees.

[0010] In this embodiment, the side surface is connected to the bottom surface, and the angle between the side surface and the bottom surface is greater than 90 degrees. This allows for a larger opening in the recess, enabling more light from the light source installed on the bottom to be emitted from the package.

[0011] In the embodiment described above, the reflectance of the side surface to light from the light source may be 10% or less.

[0012] According to this embodiment, the reflectivity of the side surface to light from the light source is 10% or less. This allows for efficient absorption of stray light originating from the side surface, thereby reducing the possibility of false detection of the target object.

[0013] In the embodiment described above, the side surface may be rough.

[0014] In this embodiment, the side surface is rough. This causes light to be diffusely reflected off the surface, resulting in a reduction in the reflectivity of the side surface.

[0015] In the embodiments described above, the package may be formed from a material that absorbs light from a light source.

[0016] According to this embodiment, the package is formed from a material that absorbs light from a light source. This stabilizes the stray light suppression properties and allows the package to be manufactured easily.

[0017] In the embodiments described above, the package may be formed from a material that absorbs light from a light source, have a metal electrode pattern on the surface of its bottom, and the light source may be connected to the metal electrode pattern.

[0018] In this embodiment, the package is formed from a material that absorbs light from a light source, has a metal electrode pattern on the surface of its bottom, and the light source is connected to the metal electrode pattern. When using the lead frame of an LED as a light source, various reflections occur, causing stray light to be a problem. However, by forming electrodes as a metal wiring pattern on the bottom surface, even if light from the light source strikes the electrodes, the pattern surface is mirror-like and the angle of incidence is large, so the generation of diffuse reflected light can be suppressed, and the generation of stray light can be reduced.

[0019] In the embodiment described above, the light-emitting unit and the light-receiving unit are housed in separate enclosures, the light-emitting unit emits a light beam outward, the light-receiving unit is configured to receive light emitted from the light-emitting unit, and the detection unit may detect an object based on changes in the amount of received light.

[0020] In this embodiment, the light-emitting unit and the light-receiving unit are housed in separate enclosures. The light-emitting unit emits a light beam outward, the light-receiving unit is configured to receive the light emitted from the light-emitting unit, and the detection unit detects the target object based on changes in the amount of received light. This suppresses false detection of the target object caused by stray light being received or by stray light being reflected off objects other than the target object, such as equipment.

[0021] In the embodiment described above, the light-emitting unit and the light-receiving unit are provided in a common housing, the light-emitting unit irradiates a light beam toward a retroreflector, the light-receiving unit is arranged to receive light reflected by the retroreflector, and the detection unit may detect an object based on the change in the amount of received light.

[0022] In this embodiment, the light-emitting unit and the light-receiving unit are housed in a common housing. The light-emitting unit irradiates a light beam toward a retroreflector, the light-receiving unit is positioned to receive light reflected by the retroreflector, and the detection unit detects an object based on changes in the amount of received light. This suppresses false detection of objects due to stray light being reflected by the object and received, a decrease in installation flexibility, and a decrease in detection performance for transparent objects.

[0023] In the above-described aspect, the light projecting unit and the light receiving unit are provided in a common housing. The light projecting unit irradiates an external object with a light beam. The light receiving unit has a light receiving field of view and is arranged to be able to receive reflected light from a region where the light beam intersects the light receiving field of view. The detecting unit may detect an object based on a change in the amount of received light of the received light.

[0024] According to this aspect, the light projecting unit and the light receiving unit are provided in a common housing. The light projecting unit irradiates an external object with a light beam. The light receiving unit has a light receiving field of view and is arranged to be able to receive reflected light from a region where the light beam intersects the light receiving field of view. The detecting unit detects an object based on a change in the amount of received light of the received light. Thereby, an expansion of the detection range due to stray light can be suppressed, the detection range can be maintained, and false detection caused by stray light being reflected by an object other than the target object, for example, equipment and being received can be suppressed.

[0025] In the above-described aspect, the light receiving axis of the light receiving unit and the light projecting axis of the light projecting unit may be configured to intersect so that the region where the light beam intersects the light receiving field of view is finite.

[0026] According to this aspect, the light receiving axis of the light receiving unit and the light projecting axis of the light projecting unit are configured to intersect so that the region where the light beam intersects the light receiving field of view is finite. Thereby, the problem that it becomes difficult to realize region limitation when there is stray light is solved.

[0027] In the above-described aspect, the light projecting unit irradiates an external object with a light beam, the light receiving unit is configured such that each of a plurality of pixels can detect the amount of received light, and is configured to obtain a received light amount distribution signal for each pixel for the received light. The detecting unit may detect an object based on the received light amount distribution signal.

[0028] In this embodiment, the light-emitting unit emits a light beam outward, the light-receiving unit is configured such that each of the multiple pixels can detect the amount of light received, and is configured to obtain a light-receiving amount distribution signal for each pixel based on the received light, and the detection unit detects the object based on the light-receiving amount distribution signal. This suppresses the stray light component in the light-receiving amount distribution signal, reduces fluctuations in the centroid of the light-receiving amount signal, and suppresses false detection of the object. [Effects of the Invention]

[0029] According to the present invention, stray light can be reduced. [Brief explanation of the drawing]

[0030] [Figure 1] Figure 1 is a block diagram illustrating the schematic configuration of the optical sensor in the first embodiment. [Figure 2] Figure 2 is a diagram illustrating the detection principle of the optical sensor in the first embodiment. [Figure 3] Figure 3 is a cross-sectional view illustrating the schematic configuration around the light-emitting section of the optical sensor in the first embodiment. [Figure 4] Figure 4 is an enlarged cross-sectional view illustrating the schematic configuration of the light-emitting section of the optical sensor in the first embodiment. [Figure 5] Figure 5 is a diagram illustrating the stray light path in a hypothetical light-emitting unit. [Figure 6] Figure 6 is an image illustrating the spot formed when light emitted from the light-emitting section of the optical sensor in the first embodiment is shone onto an object. [Figure 7] Figure 7 illustrates an example of the effect of stray light in a conventional optical sensor. [Figure 8] Figure 8 illustrates another example of the effects of stray light in conventional optical sensors. [Figure 9] Figure 9 is a diagram illustrating the detection principle of the optical sensor in the second embodiment when there is no object to be detected. [Figure 10]Figure 10 is a diagram illustrating the detection principle of an optical sensor in the second embodiment when there is an object. [Figure 11] Figure 11 is a diagram illustrating the detection principle of the optical sensor in the second embodiment when there are other objects present. [Figure 12] Figure 12 illustrates the effect of stray light when detecting an object in a conventional optical sensor. [Figure 13] Figure 13 illustrates the effect of stray light when detecting a single object in a conventional optical sensor. [Figure 14] Figure 14 illustrates the effect of stray light when detecting other objects in a conventional optical sensor. [Figure 15] Figure 15 is a diagram illustrating the detection principle of the optical sensor in the third embodiment. [Figure 16] Figure 16 is a diagram illustrating the effect of stray light in conventional optical sensors. [Figure 17] Figure 17 is a diagram illustrating the effect of stray light in conventional optical sensors. [Figure 18] Figure 18 is a diagram illustrating the detection principle of the optical sensor in the fourth embodiment. [Figure 19] Figure 19 is a diagram illustrating the effect of stray light in conventional optical sensors. [Figure 20] Figure 20 is a block diagram illustrating the schematic configuration of the optical sensor in the fifth embodiment. [Figure 21] Figure 21 is a diagram illustrating the detection principle of the optical sensor in the fifth embodiment. [Figure 22] Figure 22 is a schematic diagram illustrating an example of the application of an optical sensor in the fifth embodiment. [Figure 23] Figure 23 is a waveform diagram illustrating an example of a light reception distribution signal. [Figure 24] Figure 24 is a waveform diagram illustrating the effect of stray light in conventional optical sensors. [Modes for carrying out the invention]

[0031] Embodiments of the present invention are described below. In the following drawings, identical or similar parts are denoted by identical or similar reference numerals. However, the drawings are schematic. Therefore, specific dimensions and other details should be determined by referring to the following description. It should also be noted that there are parts in the drawings where the relationships and ratios of dimensions differ from one another. Furthermore, the technical scope of the present invention should not be interpreted as being limited to these embodiments.

[0032] [First Embodiment] First, the configuration of the optical sensor according to the first embodiment will be described with reference to Figure 1. Figure 1 is a block diagram illustrating the schematic configuration of the optical sensor 100 in the first embodiment.

[0033] As shown in Figure 1, the optical sensor 100 comprises a light emitter 10 and a light receiver 20. The optical sensor 100 is, for example, a photoelectric sensor and is configured to detect an object TA by utilizing various properties of light.

[0034] The optical sensor 100 in this embodiment is a transmissive photoelectric sensor, and the light emitter 10 and the light receiver 20 are each housed in separate enclosures (cases).

[0035] The light emitter 10 includes a control unit 50A, an input / output interface 60A, a storage unit 70A, an input / output control unit 80A, an operation unit 81A, and an output unit 82A. The light receiver 20 includes a detection unit 40, a control unit 50B, an input / output interface 60B, a storage unit 70B, an input / output control unit 80B, an operation unit 81B, and an output unit 82B.

[0036] The detection unit 40 is configured to detect an object TA based on light received by the light receiving unit 21, which will be described later. The detection unit 40 includes a processor. In this case, the processor of the detection unit 40 incorporates a program and data for detecting the object TA. Specifically, the detection unit 40 is configured to control the light emitter 10. The detection unit 40 generates control signals to control, for example, the intensity (power) of the light emitted by the light emitter 10, the duration of the light emission, the period or interval of the light emission, and the timing of the light emission. The generated control signals are output to the signal processing circuit 29.

[0037] The detection unit 40 includes a determination unit 41 as a functional block. The detection unit 40 receives a light intensity signal (hereinafter also referred to as "light intensity") indicating the amount of light received by the light receiving unit 21 via the signal processing circuit 29. The detection unit 40 is configured to detect the target object TA based on the change in the light intensity. In one example, the detection unit 40 outputs the detection signal and light intensity, which will be described later, to the outside via the input / output I / F 60. Details of the determination unit 41 will be described later.

[0038] The control unit 50A is configured to control the operation of each part of the light emitter 10, and the control unit 50B is configured to control the operation of each part of the light receiver 20. For example, the control unit 50B is connected to the detection unit 40 and exchanges signals and data with the detection unit 40. The control unit 50A is configured to include a processor such as a CPU (Central Processing Unit). The control unit 50B is configured to include a processor such as an ASIC (Application Specific Integrated Circuit).

[0039] Input / output interface 60A is the interface between the light emitter 10 and external devices, and input / output interface 60B is the interface between the light receiver 20 and external devices. Input / output interfaces 60A and 60B are configured to exchange data and signals with external devices. In addition, input / output interfaces 60A and 60B are configured to control communication with external devices.

[0040] The memory units 70A and 70B are configured to store programs, data, etc. Specifically, memory unit 70A stores data such as programs executed by the control unit 50A, setting items and setting contents, and set values, while memory unit 70B stores data such as programs executed by the control unit 50B, setting items and setting contents, and set values. The memory units 70A and 70B are configured to include, for example, memory such as ROM (Read Only Memory), RAM (Random Access Memory), and flash memory.

[0041] The input / output control unit 80A is configured to control the operation of the output unit 82A, and the input / output control unit 80B is configured to control the operation of the output unit 82B. The input / output control unit 80A is connected to the operation unit 81A and the output unit 82A, and the input / output control unit 80B is connected to the operation unit 81B and the output unit 82B. In addition, the input / output control unit 80A is connected to the control unit 50A and exchanges data with the control unit 50A, and the input / output control unit 80B is connected to the control unit 50B and exchanges data with the control unit 50B. The input / output control unit 80 is configured to include, for example, a processor such as a CPU.

[0042] In the example shown in Figure 1, the control unit 50A and the input / output control unit 80A are shown as independent elements, but the configuration is not limited to this. For example, the control unit 50A and the input / output control unit 80A may be configured as a single unit. In this case, the control unit 50A and the input / output control unit 80A may include a processor such as a CPU. Similarly, the detection unit 40, the control unit 50B, and the input / output control unit 80B are shown as independent elements, but the configuration is not limited to this. For example, at least two of the detection unit 40, the control unit 50B, and the input / output control unit 80 may be configured as a single unit. When the detection unit 40, the control unit 50B, and the input / output control unit 80 are configured as a single unit, they may include a processor such as an ASIC.

[0043] The operation unit 81A is for inputting information to the light emitter 10, and the operation unit 81B is for inputting information to the light receiver 20. The operation units 81A and 81B are composed of, for example, buttons, switches, touch panels, keyboards, etc. For example, when a user operates at least one of the buttons, switches, touch panels, keyboards, etc., the input / output control units 80A and 80B generate data corresponding to that operation. In this way, information is input to the light emitter 10 and the light receiver 20.

[0044] Output units 82A and 82B are for outputting information. Output units 82A and 82B are composed of, for example, a display device, an indicator light, and a speaker. The indicator light is composed of, for example, an indicator light using a single conventional light-emitting diode (LED) or a 7-segment LED. In this case, a surface-emitting LED is used as the light-emitting element. The display device is composed of, for example, a display panel such as a liquid crystal display, an electro-luminescence (EL) display, a plasma display, an organic electro-luminescence (OLED) display, a quantum dot organic EL (QD-OLED) display, a mini-LED display, or a micro-LED display. Output unit 82 outputs information by driving at least one of the display device, indicator light, and speaker based on a control signal input from the input / output control unit 80.

[0045] In this embodiment, examples of using an ASIC or CPU as the processor are shown, but the invention is not limited to these. The processor of the optical sensor 100 may be an integrated circuit such as a DSP (Digital Signal Processor), FPGA (Field-Programmable Gate Array), PLD (Programmable Logic Device), or SoC (System-on-a-Chip) instead of an ASIC or CPU, or in conjunction with an ASIC or CPU.

[0046] The light emitter 10 further comprises a light-emitting unit 11 and a light-emitting drive circuit 19. The light-emitting unit 11 is configured to emit light from, for example, a light-emitting window (not shown) formed in the housing. The light-emitting drive circuit 19 is for driving the light-emitting unit 11. Specifically, the light-emitting drive circuit 19 outputs a drive signal to the light-emitting unit 11 based on a control signal input from the control unit 50A. The light-emitting unit 11 is driven by the drive signal and emits light.

[0047] The light receiver 20 further comprises a light receiving unit 21 and a signal processing circuit 29. The light receiving unit 21 is configured to receive light incident from, for example, a light receiving window (not shown) formed in the housing. More specifically, the light receiving unit 21 is configured to receive light emitted from the light emitting unit 11. The light receiving unit 21 is composed of, for example, one or more light receiving elements. The light receiving element is, for example, a photodiode (PD). In addition to the light receiving element, the light receiving unit 21 may further include a condensing lens, a filter, etc. The light receiving element outputs an electrical signal corresponding to the amount of light received during a predetermined exposure time. When a PD is used as the light receiving element, an external charge storage unit may be provided to store charge according to the amount of light received during the exposure time.

[0048] The signal processing circuit 29 controls the light reception by the light receiving unit 21. For example, the signal processing circuit 29 outputs a control signal to the light receiving unit 21 so that the light receiving element receives light during the aforementioned exposure time and outputs an electrical signal during periods other than the exposure time, i.e., non-exposure periods. This control signal is input from the detection unit 40.

[0049] Furthermore, the signal processing circuit 29 receives an electrical signal from the light-receiving element of the light-receiving unit 21. The signal processing circuit 29 includes an amplification circuit (not shown) and amplifies the input electrical signal with a predetermined gain and outputs it. If the electrical signal from the light-receiving unit 21 is a current signal, the signal processing circuit 29 may also include a current-to-voltage conversion circuit. In this case, the signal processing circuit 29 converts the input current signal into a voltage value corresponding to the current value. The signal processing circuit 29 then amplifies the converted voltage signal with an amplification circuit and outputs it. This amplified signal is output to the detection unit 40 as a signal indicating the amount of light received.

[0050] Here, the detection principle of the optical sensor according to the first embodiment will be explained. Figure 2 is a diagram illustrating the detection principle of the optical sensor 100 in the first embodiment.

[0051] As shown in Figure 2, the light emitter 10 and the light receiver 20 are positioned such that light emitted from the light emitter 10 enters the light receiver 20. More specifically, the light emitter 10 and the light receiver 20 are positioned so that the light-emitting window of the light emitter 10 and the light-receiving window of the light receiver 20 face each other. If an object TA is present in the space between the light emitter 10 and the light receiver 20, the object TA will block or attenuate the light emitted from the light emitter 10, reducing the amount of light entering the light receiver 20. Based on this change in the amount of light received, which is received by the light-receiving section 21 of the light receiver 20, the detection unit 40 shown in Figure 1 is configured to detect the object TA and generate a detection signal for the object TA.

[0052] Specifically, the determination unit 41 of the detection unit 40 shown in Figure 1 compares the value of the amount of light received by the light receiver 20 with a threshold value for determination to determine the presence or absence of an object TA. As long as the amount of light received is above the threshold value, it is considered that there is no object TA between the light emitter 10 and the light receiver 20. Therefore, the detection unit 40 sets the signal level of the detection signal to a level indicating the off state, for example, a low level. On the other hand, if the amount of light received falls below the threshold value, it is considered that there is an object TA between the light emitter 10 and the light receiver 20, and that the light from the light emitter 10 to the light receiver 20 is blocked or attenuated by the object TA. Therefore, the detection unit 40 sets the signal level of the detection signal to a level indicating the on state, for example, a high level. In this way, the detection unit 40 can detect the presence or absence of an object TA.

[0053] Next, the configuration of the light-emitting section of the optical sensor according to the first embodiment will be described with reference to Figures 3 and 4. Figure 3 is a cross-sectional view illustrating the schematic configuration around the light-emitting section 11 of the optical sensor 100 in the first embodiment. Figure 4 is an enlarged cross-sectional view of the main part illustrating the schematic configuration of the package 13 of the optical sensor 100 in the first embodiment.

[0054] The light-emitting unit 11 is housed inside the housing of the light emitter 10. The light-emitting unit 11 emits a light beam outwards. As shown in Figure 3, the housing of the light emitter 10 further includes a lens holder 17 and a substrate 18 in addition to the light-emitting unit 11.

[0055] The light-emitting unit 11 includes a light source 12, a package 13, and a light-emitting lens 16. The light source 12 is configured to emit light. The light source 12 is composed of, for example, a light-emitting element such as an LED or a laser diode.

[0056] Furthermore, the light source 12 can be a wide variety of types, regardless of the type of light it emits. For example, the light source 12 may be a point light source, or it may be a surface-emitting LED. Alternatively, a laser diode that emits a vertical cavity surface-emitting laser (VCSEL) may be used.

[0057] Package 13 has a recess 13a, such as a cavity or depression, formed on one side (the top surface in Figures 3 and 4). The material of package 13 is, for example, epoxy resin or ceramic such as aluminum oxide (Al2O3) or aluminum nitride (AlN). Package 13 is formed together with the recess 13a, for example, using a mold.

[0058] As shown in Figure 4, the recess 13a includes an opening 13d that is open in the direction of light projection from the floodlight 10, for example, in the positive Y-axis direction in Figures 3 and 4. The recess 13a further includes a bottom surface 13b on which the light source 12 is installed. The light source 12 is installed such that the light-emitting surface (top surface in Figures 3 and 4) that emits the main light (hereinafter also referred to as "main light") faces the opening 13d.

[0059] The light-emitting section 11 further includes a resin 14 that covers the light source 12. The resin 14 is light-transmitting to the light from the light source 12. For example, epoxy resin or silicone resin can be used as the material for the resin 14. The resin 14 is filled into the recess 13a after the light source 12 is installed on the bottom surface 13b.

[0060] Thus, the light-emitting section 11 further includes a light-transmitting resin 14 that covers the light source 12. This protects the light source 12 and allows the light source 12 to be fixed to the bottom surface 13b of the recess 13a.

[0061] The recess 13a further includes a side surface 13c that connects the bottom surface 12b and the opening 13d. The side surface 13c has an angle θ with respect to the bottom surface 12b. The recess 13a is formed such that the area of ​​the bottom surface 12b is smaller than the area of ​​the surface including the opening 13d (hereinafter also referred to as the "opening surface"). Therefore, the side surface 13c is inclined, and its angle θ is greater than 90 degrees and less than 180 degrees (180°>θ>90°). This makes the opening surface of the recess 13a larger, allowing more light from the light source 12 installed on the bottom surface 13b to be emitted from the package 13.

[0062] The light-emitting section 11 further includes bonding wires 15 connected to the light source 12. The bonding wires 15 are, for example, wiring made of gold (Au), and electrically connect the light source 12 and the substrate 18.

[0063] The light-emitting lens 16 is configured to focus the light from the light source 12. Specifically, the light-emitting lens 16 is positioned at a predetermined distance from the package 13. More specifically, the light-emitting lens 16 is positioned on one side (the positive Y-axis side in Figure 3) of the package 13 so that light emitted from the opening 13d of the recess 13a is incident on it. The light-emitting lens 16 is fixed and held by the lens holder 17.

[0064] The light projection lens 16 is, for example, a convex lens. In this case, the light projection lens 16 refracts the light beam incident on one surface (the bottom surface in Figure 3) and emits the refracted light beam from the other surface (the top surface in Figure 3) so that it converges at a predetermined focal point.

[0065] Thus, the optical sensor 100 further includes a light-emitting lens 16 positioned relative to the package 13 so that light emitted from the opening 13d of the recess 13a is incident on it. This allows the light emitted from the package 13 to be refracted, diverged, or focused, making it easy to illuminate the target object TA, the light-receiving unit 21, etc.

[0066] In this embodiment, an example is shown in which there is one light-emitting lens 16, but the optical sensor 100 is not limited to this. The optical sensor 100 may have two or more light-emitting lenses. In addition, the optical sensor 100 may have other lenses instead of, or together with, the light-emitting lenses, or it may have other optical components, such as mirrors.

[0067] Here, we will explain the generation of stray light. Figure 5 is a diagram illustrating the stray light path in a hypothetical light-emitting unit. Note that the hypothetical light-emitting unit is one that a conventional optical sensor has, and components identical or similar to the light-emitting unit 11 of this embodiment are denoted by the same or similar reference numerals, and their descriptions are omitted as appropriate. Also, Figure 5 corresponds to the enlarged cross-sectional view of the main part of the package 13 shown in Figure 4.

[0068] As shown in Figure 5, the light source 12 is installed on the bottom surface of a recess (not shown) formed in the package 13' and is covered with resin 14. A bonding wire 15 is also connected to the light source 12.

[0069] Stray light generated in a virtual light-emitting section can be exemplified by the following: As shown by the dashed line in Figure 5, stray light is generated when light emitted from the side of the light source 12 reflects off the side of the recess formed in the package 13' and follows a path that enters the light-emitting lens (not shown). Also, as shown by the dashed line in Figure 5, stray light is generated when light emitted from the top surface of the light source 12 reflects off the surface of the resin 14, then reflects off the bottom surface of the recess formed in the package 13' and follows a path that enters the light-emitting lens. Furthermore, as shown by the double dashed line in Figure 5, stray light is generated when light emitted from the top surface of the light source 12 reflects off the bonding wire 15, then reflects off the bottom surface of the recess formed in the package 13' and follows a path that enters the light-emitting lens.

[0070] The inventors of this invention analyzed stray light in a hypothetical light-emitting unit using optical simulations and found that, among the various paths that stray light follows, the stray light following the dashed line in Figure 5 is the main cause. They then conceived that by implementing means to reduce the amount of this stray light, it would be possible to significantly suppress the effects of stray light.

[0071] In contrast, the side surface 13c of the recess 13a formed in the package 13 of this embodiment shown in Figure 4 contains a material that absorbs light emitted by the light source 12. Specifically, the side surface 13c is made of a material that has a black color. For example, the side surface 13c is made of black epoxy resin. Alternatively, the side surface 13c is made by mixing a black pigment with a powder such as alumina and sintering it. It is preferable that all side surfaces 13c surrounding the light source 12 contain a material that absorbs light from the light source 12. Furthermore, not only the side surfaces 13c, but the entire package 13 may be molded from a material that absorbs light from the light source 12.

[0072] For comparison, the light intensity and reflectance of the hypothetical light-emitting unit shown in Figure 5 will be explained. In the hypothetical light-emitting unit, when a white package 13' with relatively high reflectance was used, the amount of stray light irradiated onto the target object, such as a screen, was 153% of the amount of main light, meaning the stray light was more than 1.5 times that of the main light. At this time, the reflectance of package 13' for the wavelength band of light source 12 from 610 nm to 980 nm was approximately 90%.

[0073] The reflectance (=numerator / denominator) here is defined as follows: • Denominator: The denominator is the total amount of light emitted from the light source 12 that directly enters the side surface 13c of the package 13. Light reflected by other paths and entering the side surface 13c is not included. • Molecular: The numerator is the total amount of light that enters the aforementioned side surface 13c, is reflected near the interface of side surface 13c, and directly passes through aperture 13d. This does not include light that passes through aperture 13d through other paths.

[0074] In contrast, in the package 13 of this embodiment shown in Figure 4, when a package 13 that is entirely black, including the side surface 13c, is used, the amount of stray light irradiated onto an object, such as a screen, is 0.03% of the amount of main light, meaning that stray light is almost nonexistent. At this time, the reflectance of the package 13 for the wavelength band of the light source 12 from 610 nm to 980 nm was approximately 4%.

[0075] Next, with reference to Figure 6, the light emitted from the light-emitting section of the optical sensor according to the first embodiment will be described. Figure 6 is an image illustrating the spot formed when light emitted from the light-emitting section 11 of the optical sensor 100 in the first embodiment is shone onto an object. The image shown in Figure 6 was taken by placing graph paper at a predetermined distance from the light emitter 10 and photographing the light shone onto the paper.

[0076] As shown in Figure 6, when a surface-emitting LED was used as the light source 12, it was confirmed that the stray light IL1 on graph paper at a distance of 100 mm from the light source 10 showed a significant reduction in stray light and a high proportion of main light intensity. Similarly, it was confirmed that the stray light IL2 on graph paper at a distance of 200 mm from the light source 10 also showed a significant reduction in stray light and a high proportion of main light intensity. Furthermore, even when a point-emitting LED was used as the light source 12, it was confirmed that the stray light IL3 showed a significant reduction in stray light and a high proportion of main light intensity.

[0077] Thus, in the optical sensor 100, the light-emitting section 11 further includes a package 13 on which a light source 12 is installed on the bottom surface 13b of a formed recess 13a, and a light-transmitting resin 14 that covers the light source 12, and the side surface 13c of the recess 13a contains a material that absorbs light from the light source 12. As a result, light incident from the light source 12 installed on the bottom surface 13b to the side surface 13c is absorbed, making it possible to absorb stray light, which is the main cause of stray light and whose generation path includes the side surface 13c. Therefore, stray light can be reduced and a decrease in the signal-to-noise ratio can be suppressed. In addition, the visibility of the spot of main light irradiated onto the target object TA can be improved.

[0078] It is preferable that the reflectance of the side surface 13c to the light emitted by the light source 12 is greater than 0% and 10% or less. Generally, when considering black paper as the object with the lowest reflectance in practical terms among the objects detected by a photoelectric sensor, its reflectance is 6%. On the other hand, when considering metallic objects such as aluminum (Al) as objects with relatively high reflectance, their reflectance is 60% or more. Furthermore, when using an LED as a light source, assuming that the amount of light emitted from the front and sides is approximately the same, when the light from the front illuminates the black paper at the center of the spot, and the light from the side hits a metallic object surrounding the spot and is reflected, it is necessary to avoid the object being mistakenly detected by ambient light, or the object being mistakenly not detected (hereinafter, both will be collectively referred to as "false detection"). For this reason, it is desirable that the reflectance of the side surface of the package into which light from the side of the LED enters is 10% or less.

[0079] Thus, the reflectivity of the side surface 13c to the light emitted by the light source 12 is 10% or less. This allows for efficient absorption of stray light originating from the side surface 13c, thereby reducing the possibility of false detection of the target object TA.

[0080] Furthermore, it is even more preferable that the reflectance of the side surface 13c to the light emitted by the light source 12 is greater than 0% and 6% or less. In other words, if nearly 100% of the light is reflected by a highly reflective object such as a reflective film in the surrounding area, the theoretical maximum value may be reached, which could lead to false detection of the object due to ambient light. In this case, it is desirable that the reflectance of the side surface of the package to which the light from the LED side surface enters is 6% or less.

[0081] Thus, the reflectivity of the side surface 13c to the light emitted by the light source 12 is 6% or less. This allows for more efficient absorption of stray light originating from the side surface 13c, further reducing the possibility of false detection of the target object TA.

[0082] Furthermore, the side surface 13c may be rough. In this case, the side surface 13c is formed using a mold with a roughened surface. Specifically, the surface roughness of the side surface 13c, for example, the arithmetic mean roughness (Ra), has a maximum value of 0.03 μm or more. In this way, because the side surface 13c is rough, light is diffusely reflected off its surface, and as a result, the reflectance of the side surface 13c can be reduced.

[0083] The flatness of the side surface 13c may be lower than the flatness of the opening 13d (the interface of the resin 14). The opening 13d is usually manufactured to be flat. If the opening 13d is rough, scattering will occur there, which is undesirable.

[0084] Package 13 is formed from a material that absorbs light from the light source 12. This stabilizes the stray light suppression characteristics and allows for easy manufacturing of package 13.

[0085] Furthermore, the package 13 may have a metal electrode pattern on the surface of its bottom surface 13b, and the light source 12 may be connected to the metal electrode pattern. When using the lead frame of an LED as the light source 12, various reflections occur, causing stray light to become a problem. However, by forming electrodes as a metal wiring pattern on the bottom surface 13b, even if light from the light source 12 strikes the electrodes, the pattern surface is mirror-like and the angle of incidence is large, so the generation of diffuse reflected light can be suppressed, and the generation of stray light can be reduced.

[0086] Next, the effects of stray light in conventional optical sensors will be explained with reference to Figures 7 and 8. Figure 7 is a diagram illustrating an example of the effects of stray light in a conventional optical sensor. Figure 8 is a diagram illustrating another example of the effects of stray light in a conventional optical sensor. Note that the conventional optical sensors in Figures 7 and 8 are through-beam photoelectric sensors, and for the sake of simplicity, only the light emitter and light receiver of a conventional optical sensor are shown.

[0087] As shown in Figure 7, when multiple optical sensors are placed close together, if the light emitted from the light emitter 10' contains stray light (indicated by the dashed line), this stray light may enter the receiver 20'' of an adjacent optical sensor. In this case, the light emitted from the light emitter 10'' should ideally be blocked by the object TA, and the object TA should be detected. However, if stray light enters and is received by the receiver 20'', it may be incorrectly determined that there is no object TA.

[0088] Furthermore, as shown in Figure 8, if an equipment EQ is located near the optical sensor, and the light emitted from the light emitter 10' contains stray light (indicated by the dashed line), this stray light may be reflected by the equipment EQ, and the reflected light may enter the light receiver 20'. In this case, the light emitted from the light emitter 10' should be blocked by the object TA between it and the light receiver 20', and the object TA should be detected by a decrease in the amount of light received. However, the reflected light that was reflected by the equipment EQ enters the light receiver 20' and is received. As a result, the amount of light received may not decrease significantly, and it may be incorrectly determined that there is no object TA.

[0089] In contrast, in the optical sensor 100 of this embodiment, the light-emitting unit 11 and the light-receiving unit 21 are housed in separate enclosures. The light-emitting unit 11 emits a light beam outward, and the light-receiving unit 21 is configured to receive the light emitted from the light-emitting unit 11. The detection unit 40 detects the target object TA based on the change in the amount of received light. This suppresses false detection of the target object TA caused by stray light being received, or by stray light being reflected by an object other than the target object, such as equipment EQ, and then received.

[0090] [Second Embodiment] Next, the detection principle of the optical sensor according to the second embodiment will be described with reference to Figures 9 to 11. Figure 9 is a diagram illustrating the detection principle of the optical sensor 200 in the second embodiment when there is no object. Figure 10 is a diagram illustrating the detection principle of the optical sensor 200 in the second embodiment when there is one object TA1. Figure 11 is a diagram illustrating the detection principle of the optical sensor 200 in the second embodiment when there is another object TA2. In the second embodiment, the same or similar reference numerals are used for components identical or similar to those in the first embodiment, and their descriptions are omitted as appropriate unless otherwise specified. Furthermore, in the following, the differences from the first embodiment will be mainly described, and similar effects and benefits due to the same configuration as the first embodiment will not be mentioned sequentially.

[0091] The optical sensor 200 in this embodiment is a retroreflective photoelectric sensor. As shown in Figure 9, the light-emitting unit 11 and the light-receiving unit 21 are housed in the same housing as a light-emitting / receiving unit 110. The light-emitting / receiving unit 110 is positioned opposite the retroreflector RP. The retroreflector RP can be, for example, a resin molded product or a sheet. The light-emitting unit 11 irradiates a light beam from a package 13, on which the light source 12 is installed on the bottom surface 13b, towards the retroreflector RP via a light-emitting lens 16. The irradiated light is reflected by the retroreflector RP and returns to the light-emitting / receiving unit 110. This reflected light is configured to be received by the light-receiving unit 21 via a light-receiving lens 26.

[0092] As shown in Figure 10, when an object TA1 is present in the space between the light emitter 110 and the retroreflector RP, the light beam emitted from the light emitter 11 is blocked by the object TA. The light reflected by the object TA is configured not to enter the light receiving unit 21. More specifically, the light receiving unit 21 is provided with a shielding object 22, such as a slit, and the light reflected at a position in front of the retroreflector RP is designed to enter the shielding object 22. As a result, the amount of reflected light received by the light receiving unit 21 decreases, and, as in the first embodiment, the detection unit 40 is configured to detect the object TA1 and generate a detection signal for the object TA1 based on this change in the amount of reflected light received.

[0093] Furthermore, as shown in Figure 11, when a transparent object TA2 is present in the space between the light emitter 110 and the retroreflector RP, a portion of the light beam emitted from the light emitter 11 may pass through the object TA2, be reflected by the retroreflector RP, and the reflected light may pass through the object TA2 again and enter the light receiving unit 21. At this time, a portion of the light incident on the surface of the object TA2 is refracted, and the refracted light does not enter the light receiving unit 21, so the amount of reflected light received by the light receiving unit 21 decreases. Similar to the first embodiment, the detection unit 40 is configured to detect the object TA2 and generate a detection signal for the object TA2 based on this change in the amount of reflected light received.

[0094] Next, the effects of stray light in conventional optical sensors will be explained with reference to Figures 12 to 14. Figure 12 is a diagram illustrating the effect of stray light when detecting one object TA1 in a conventional optical sensor 200'. Figure 13 is a diagram illustrating the effect of stray light when detecting one object TA1 in a conventional optical sensor 200'. Figure 14 is a diagram illustrating the effect of stray light when detecting another object TA2 in a conventional optical sensor 200'. Note that the conventional optical sensor 200' in Figures 12 to 14 is a retroreflective photoelectric sensor, and for the sake of simplicity, only the light emitter / receiver 210' of the conventional optical sensor is shown.

[0095] As shown in Figure 12, if the light emitted from the package 13' and the light-emitting lens 16 of the light-emitting unit 11' contains stray light, indicated by the dashed line, then if the object TA1 is a blank sheet of paper or the like, this stray light will be diffusely reflected by the object TA1 and easily incident on the light-receiving unit 21' for detection. In this case, normally, the light emitted from the light-emitting unit 11' would be reflected by the object TA1, and this reflected light would be blocked by the shielding object 22, allowing the object TA to be detected. However, because stray light is incident on the light-receiving unit 21' and detected, it may be incorrectly determined that there is no object TA.

[0096] Furthermore, as shown in Figure 13, when multiple retroreflectors RP1 and RP2 are placed adjacent to each other at close range, if the light emitted from the light-emitting unit 11' contains stray light indicated by the dashed line, this stray light may be reflected by the adjacent retroreflector RP2 and incident on the light-receiving unit 21', resulting in it being received. In this case, ideally, the light emitted from the light-emitting unit 11' should be reflected by the object TA1, and this reflected light should be blocked by the shielding object 22, thus detecting the object TA. However, because the reflected light reflected by the retroreflector RP2 is incident on the light-receiving unit 21', it may be incorrectly determined that there is no object TA. Therefore, the conventional optical sensor 200' has a low degree of installation flexibility.

[0097] Furthermore, as shown in Figure 14, if the object TA2 is transparent, and the light emitted from the light-emitting unit 11' contains stray light (indicated by the dashed line), this stray light may be refracted by the object TA2 and reflected by the retroreflector RP, and this reflected light may be refracted again by the object TA2 and incident on the light-receiving unit 21'. In this case, the light emitted from the light-emitting unit 11' should be attenuated by the object TA2, and the object TA2 should be detected by the decrease in the amount of light received. However, the reflected light of the stray light refracted by the object TA2 is incident on the light-receiving unit 21' and is received. As a result, the decrease in the amount of light received is suppressed, or even the amount of light received increases, which may lead to the incorrect determination that the object TA2 is not present. Therefore, the conventional optical sensor 200' has poor detection performance for transparent objects TA2.

[0098] In contrast, in the optical sensor 200 of this embodiment, the light-emitting unit 11 and the light-receiving unit 21 are provided in a common housing, the light-emitting unit 11 irradiates a light beam toward the retroreflector RP, the light-receiving unit 21 is positioned to receive light reflected by the retroreflector RP, and the detection unit 40 detects objects TA1 and TA2 based on changes in the amount of received light. This makes it possible to suppress false detection of object TA1 due to stray light being reflected by object TA1 and received, a decrease in installation flexibility, and a decrease in detection performance of transparent object TA2.

[0099] [Third Embodiment] Next, the detection principle of the optical sensor according to the third embodiment will be described with reference to Figure 15. Figure 15 is a diagram illustrating the detection principle of the optical sensor 300 in the third embodiment. In the third embodiment, the same or similar reference numerals are used for components identical or similar to those in the previously described embodiments, and their descriptions are omitted as appropriate unless otherwise specified. Furthermore, in the following, the differences from the previously described embodiments will be mainly explained, and similar effects and benefits due to the same configuration as the previously described embodiments will not be mentioned sequentially.

[0100] The optical sensor 300 in this embodiment is a diffuse reflection type photoelectric sensor. As shown in Figure 15, the light-emitting unit 11 and the light-receiving unit 21 are housed in the same housing as a light-emitting and light-receiving unit 310. The light-emitting unit 11 emits a light beam outwards. The light-receiving unit 21 has a light-receiving field of view and is positioned to receive reflected light from the region where the light beam and the light-receiving field of view intersect. When there is no object TA, the light beam emitted from the package 13, on which the light source 12 is installed on the bottom surface 13b, via the light-emitting lens 16, is not reflected and does not return to the light-emitting and light-receiving unit 310. On the other hand, as shown in Figure 15, if there is an object TA in the area where the spot of the light beam emitted from the light-emitting unit 11 and the light-receiving field of view of the light-receiving unit 21 overlap, the light is reflected by the object TA and returns to the light-emitting and light-receiving unit 310. This reflected light is received by the light-receiving unit 21 via the light-receiving lens 26. Therefore, compared to when there is no object TA, the amount of reflected light received by the light receiving unit 21 increases. The detection unit 40 is configured to detect the object TA based on this change in the amount of reflected light received and to generate a detection signal for the object TA.

[0101] Next, the effects of stray light in conventional optical sensors will be explained with reference to Figures 16 and 17. Figure 16 is a diagram illustrating the effects of stray light in a conventional optical sensor 300'. Figure 17 is a diagram illustrating the effects of stray light in a conventional optical sensor 300'. Note that the conventional optical sensor 300' in Figures 16 and 17 is a diffuse reflection type photoelectric sensor, and for the sake of simplicity, only the light emitter / receiver 310' of the conventional optical sensor 300' is shown.

[0102] As shown in Figure 16, if the light emitted from the package 13' and the light-emitting lens 16 of the light-emitting unit 11' contains stray light, indicated by the dashed line, the portion that overlaps with the light-receiving field of view, i.e., the detection range, expands. As a result, objects such as object TA that are in the light-receiving field of view but do not overlap with the light-emitting spot are illuminated by the light emitted from the light-emitting unit 11'. In applications where it is desired to limit the spot of light emitted from the light-emitting unit 11', the detection range is the target of control, but since stray light is not intended in the design, it becomes difficult to maintain the detection range of light containing stray light.

[0103] Furthermore, as shown in Figure 17, in environments where highly reflective objects such as equipment EQs exist, if the light emitted from the light-emitting unit 11' contains stray light indicated by the dashed line, this stray light may be reflected by the equipment EQ and incident on the light-receiving unit 21', where it may be received. In this case, although the object TA should not be present and therefore the reflected light should not be received, the reflected light reflected by the equipment EQ may incident on the light-receiving unit 21' and be received, potentially leading to the incorrect detection of the presence of the object TA.

[0104] In contrast, in the optical sensor 300 of this embodiment, the light-emitting unit 11 and the light-receiving unit 21 are provided in a common housing, the light-emitting unit 11 irradiates a light beam outward, the light-receiving unit 21 has a light-receiving field and is arranged to receive reflected light from the region where the light beam and the light-receiving field intersect, and the detection unit 40 detects the target object TA based on the change in the amount of received light. This suppresses the expansion of the detection range due to stray light and maintains the detection range, and also suppresses false detections caused by stray light being reflected and received by objects other than the target object, such as equipment EQ.

[0105] [Fourth Embodiment] Next, the detection principle of the optical sensor according to the fourth embodiment will be described with reference to Figure 18. Figure 18 is a diagram illustrating the detection principle of the optical sensor 400 in the fourth embodiment. In the fourth embodiment, the same or similar reference numerals are used for components identical or similar to those in the previously described embodiments, and their descriptions are omitted as appropriate unless otherwise specified. Furthermore, in the following, the differences from the previously described embodiments will be mainly explained, and similar effects and benefits due to the same configuration as the previously described embodiments will not be mentioned sequentially.

[0106] The optical sensor 400 in this embodiment is a limited reflection type photoelectric sensor. As shown in Figure 16, the light-emitting unit 11 and the light-receiving unit 21 are housed in the same housing as a light-emitting and light-receiving unit 410. The axis of light emitted from the light-emitting unit 11 of the light-emitting and light-receiving unit 410 (hereinafter also referred to as the "light-emitting axis") and the axis of light incident on the light-receiving unit 21 of the light-emitting and light-receiving unit 410 (hereinafter also referred to as the "light-receiving axis") intersect. More specifically, the light-receiving axis of the light-receiving unit 21 and the light-emitting axis of the light-emitting unit 11 are configured to intersect such that the region where the light beam and the light-receiving field of view intersect is finite. In Figure 18, the light-emitting axis of the light-emitting unit 11 is shown by a dashed line, and the light-receiving axis of the light-receiving unit 21 is shown by a double-dashed line. The overlapping area of ​​the range of light emitted from the light-emitting unit 11 and the light-receiving area of ​​the light-receiving unit 21 becomes the detection area. In the example shown in Figure 18, the detection region DA is a limited rectangular area enclosed by the light range shown by the thick line and the light receiving area shown by the dotted line. When an object TA is present in the detection region DA, the light beam emitted from the package 13, on which the light source 12 is installed on the bottom surface 13b, via the light-emitting lens 16, is reflected by the object TA and returns to the light-transmitting receiver 410. This reflected light is received by the light-receiving unit 21 via the light-receiving lens 26, so the amount of reflected light received by the light-receiving unit 21 increases compared to when there is no object TA in the detection region DA. The detection unit 40 is configured to detect the object TA based on this change in the amount of reflected light received and to generate a detection signal for the object TA.

[0107] Next, the effect of stray light in conventional optical sensors will be explained with reference to Figure 19. Figure 19 is a diagram illustrating the effect of stray light in a conventional optical sensor 400'. Note that the conventional optical sensor 400' in Figure 19 is a limited reflection type photoelectric sensor, and for the sake of simplicity, only the light emitter / receiver 410' of the conventional optical sensor 400' is shown.

[0108] As shown in Figure 19, if stray light, indicated by the dashed line, is included in the light emitted from the package 13' and the light-emitting lens 16 in the light-emitting unit 11', the detection area expands. In the example shown in Figure 19, the detection area DA' expands to a rectangular area enclosed by the stray light area indicated by the dashed line and the light-receiving area indicated by the dotted line. Therefore, an object TA that would normally be outside the detection area is included in the detection area DA'. Since stray light is not intended in the design, it becomes difficult to maintain the limitation of the detection area.

[0109] In contrast, in the optical sensor 400 of this embodiment, the light-receiving axis of the light-receiving unit 21 and the light-emitting axis of the light-emitting unit 11 are configured to intersect so that the region where the light beam and the light-receiving field of view intersect is finite. This solves the problem that it becomes difficult to achieve region limitation when stray light is present.

[0110] [Fifth Embodiment] Next, the configuration of the optical sensor according to the fifth embodiment will be described with reference to Figure 20. Figure 20 is a block diagram illustrating the schematic configuration of the optical sensor 500 in the fifth embodiment. In the fifth embodiment, the same or similar reference numerals are used for components that are the same or similar as those in the previously described embodiments, and their descriptions are omitted as appropriate unless otherwise specified. Furthermore, in the following, the differences from the previously described embodiments will be mainly described, and similar effects and advantages due to the same configuration as in the previously described embodiments will not be mentioned sequentially.

[0111] The optical sensor 500 in this embodiment is a distance-setting type photoelectric sensor. As shown in Figure 20, the optical sensor 500 includes a main body 530. The main body 530 includes a light-emitting unit 11, a light-emitting drive circuit 19, a light-receiving unit 21A, a signal processing circuit 29, a detection unit 40A, a control unit 50, an input / output interface 60, a storage unit 70, an input / output control unit 80, an operation unit 81, and an output unit 82, all housed in the same enclosure.

[0112] The light-receiving unit 21A is configured such that multiple pixels each receive light, and the amount of light received can be detected for each pixel. In addition, the light-receiving unit 21A is configured to obtain a light-receiving amount distribution signal that indicates the amount of light received for each pixel, as described later. The light-receiving unit 21A is composed of, for example, an image sensor. The image sensor is, for example, a CMOS (Complementary MOS) image sensor or a CCD (Charge-Coupled Device) image sensor. The image sensor contains multiple pixels, and each pixel is arranged in one or two dimensions. Each pixel accumulates charge according to the amount of light received during a predetermined exposure time. Then, each pixel outputs an electrical signal corresponding to the accumulated charge.

[0113] The detection unit 40A includes a determination unit 41 and a calculation unit 42 as functional blocks. The detection unit 40 receives a light intensity distribution signal obtained by the light receiving unit 21A via a signal processing circuit 29. The detection unit 40A is configured to detect the target object TA based on the change in the light intensity distribution signal. Details of the determination unit 41 and the calculation unit 42 will be described later.

[0114] In the example shown in Figure 20, the determination unit 41 and the calculation unit 42 are shown as functional blocks of the detection unit 40A, but the configuration is not limited to this. For example, the determination unit 41 and the calculation unit 42 may be configured as independent elements. Also, the light projection drive circuit 19, light receiving unit 21A, signal processing circuit 29, determination unit 41, calculation unit 42, control unit 50, and input / output control unit 80 are not limited to being independent elements. For example, at least two of the light projection drive circuit 19, light receiving unit 21A, signal processing circuit 29, determination unit 41, calculation unit 42, control unit 50, and input / output control unit 80 may be configured as an integrated unit. More specifically, the light receiving unit 21A, signal processing circuit 29, and determination unit 41 may be configured as an integrated unit including a processor such as an ASIC, and the light projection drive circuit 19, calculation unit 42, control unit 50, and input / output control unit 80 may be configured as an integrated unit including a processor such as an ASIC. Alternatively, the light projection drive circuit 19, light receiving unit 21A, signal processing circuit 29, and calculation unit 42 are configured as a single unit including a processor such as an ASIC, and the determination unit 41, control unit 50, and input / output control unit 80 are configured as a single unit including a processor such as an ASIC.

[0115] Furthermore, the optical sensors 200, 300, and 400 mentioned above may also be configured in the same manner as the optical sensor 500 in this embodiment.

[0116] Here, with reference to Figure 21, the principle by which the optical sensor according to the fifth embodiment detects an object will be explained. Figure 21 is a diagram illustrating the detection principle of the optical sensor 500 in the fifth embodiment.

[0117] As shown in Figure 21, the main body 530 of the optical sensor 500 is positioned at a predetermined distance D1 from the object TA. In the light-emitting unit 11, the light beam emitted from the package 13, on which the light source 12 is installed on the bottom surface 13b, via the light-emitting lens 16 is reflected by the object TA. The reflected light is incident on some pixels of the light-receiving unit 21A via the light-receiving lens 26. Meanwhile, for example, a background BG is positioned at a distance D2 (distance D2 > distance D1) from the main body 530. The light reflected by the background BG is incident on other pixels of the light-receiving unit 21A via the light-receiving lens 26. In this way, each pixel of the light-receiving unit 21A, which is arranged in one dimension, vertically in the example of Figure 21, corresponds to a distance D from the main body 530. Alternatively, each pixel of the light-receiving unit 21A may be arranged in two dimensions, vertically and in depth (perpendicular to the plane of the paper), as shown in the example of Figure 21. Therefore, because each pixel of the light-receiving unit 21A is arranged in one or two dimensions, a light-receiving amount distribution signal indicating the amount of light received for each pixel is obtained, that is, a light-receiving amount distribution signal indicating the amount of light received according to the distance D from the main unit 530.

[0118] Next, with reference to Figure 22, an example of the application of the optical sensor according to the fifth embodiment will be described. Figure 22 is a schematic diagram illustrating an example of the application of the optical sensor 500 in the fifth embodiment.

[0119] As shown in Figure 22, the main body 530 of the optical sensor 500 is positioned above the background BG and is set up to project light towards the background BG and receive reflected light. The object TA is placed on top of the background BG, and the background BG on which the object TA is placed is moving in the direction of the black arrow shown in Figure 22.

[0120] Here, we will explain the distance based on the light intensity distribution signal, referring to Figure 23. Figure 23 is a waveform diagram illustrating an example of a light intensity distribution signal. In Figure 23, the horizontal axis represents each pixel of the light receiving unit 21A, and the vertical axis represents the amount of light received.

[0121] As shown in Figure 23, the light reception distribution signal typically has a waveform in which the light reception amount of a certain pixel is at its peak. The pixel with the peak light reception amount in the light reception distribution signal obtained from the light receiving unit 21A is the pixel into which light emitted from the main unit 530 and reflected by the object TA is incident. This pixel corresponds to the distance from the main unit 530 to the object TA.

[0122] Specifically, the calculation unit 42 of the detection unit 40A calculates the coordinates of the centroid in the received light distribution signal. Then, the calculation unit 42 converts the calculated coordinates into distance. In this way, the calculation unit 42 can calculate the distance from the light emitter 510 to the object TA.

[0123] The determination unit 41 of the detection unit 40A determines whether the distance calculated by the calculation unit 42 based on the maximum peak in the light intensity distribution signal is within a predetermined range (±ΔD) from a preset distance D1 of the object TA. In this way, the detection unit 40A can detect the object TA which is at a distance D1 from the light emitter 510.

[0124] Next, the effect of stray light in conventional optical sensors will be explained with reference to Figure 24. Figure 24 is a waveform diagram illustrating the effect of stray light in conventional optical sensors. In Figure 24, the conventional optical sensor is a distance-setting type photoelectric sensor, and the light-receiving unit is configured to obtain a light-receiving amount distribution signal for each pixel for the received light. In Figure 24, the horizontal axis represents each pixel of the light-receiving unit, and the vertical axis represents the amount of light received.

[0125] If stray light is present in the light emitted from the light emitter, the illumination range of the emitted light will widen, and the stray light may be reflected by the background BG as described above and incident on the light receiver. Also, if the surface of the target object TA is a packaging package and this packaging package contains colors or patterns with different reflectivity, these colors and patterns may reflect the stray light, and the reflected stray light may incident on the light receiver. In these cases, as shown in Figure 24, the light intensity distribution signal of the light receiver will include the stray light component SLE in addition to the main light component. As a result, the centroid in the light intensity distribution signal will fluctuate, and the calculated distance will change, which may lead to an incorrect determination of the presence or absence of the target object TA.

[0126] In contrast, in the optical sensor 500 of this embodiment, the light-emitting unit 11 irradiates a light beam outward, the light-receiving unit 21A is configured such that each of the multiple pixels can detect the amount of light received, and is configured to obtain a light-receiving amount distribution signal for each pixel for the received light, and the detection unit 40A detects the target object TA based on the light-receiving amount distribution signal. As described above, since the light incident on the side surface 13c from the light source 12 installed on the bottom surface 13b is absorbed, the stray light component SLE in the light-receiving amount distribution signal can be suppressed, the fluctuation of the centroid of the signal due to the amount of light received can be reduced, and false detection of the target object TA can be suppressed.

[0127] The above describes exemplary embodiments of the present invention. According to one embodiment of the optical sensor 100, the sensor comprises a light-emitting unit 11 including a light source 12 that emits light and a light-emitting lens 16 configured to concentrate the light from the light source 12, a light-receiving unit 21 that receives light, and a detection unit 40 that detects an object TA based on the received light. The light-emitting unit 11 further includes a package 13 on which the light source 12 is installed at the bottom surface 13b of a formed recess 13a, and a light-transmitting resin 14 that covers the light source 12. The side surface 13c of the recess 13a contains a material that absorbs the light from the light source 12. As a result, the light incident on the side surface 13c from the light source 12 installed at the bottom surface 13b is absorbed, making it possible to absorb stray light, which is the main cause of stray light and whose generation path includes the side surface 13c. Therefore, stray light can be reduced, and a decrease in the S / N ratio can be suppressed. In addition, the visibility of the spot of main light irradiated onto the object TA can be improved.

[0128] The embodiments described above are provided to facilitate understanding of the present invention and are not intended to limit its interpretation. The present invention can be modified or improved without departing from its spirit, and equivalents thereof are also included. That is, any design modifications made to each embodiment by those skilled in the art are also included within the scope of the present invention, as long as they retain the features of the present invention. For example, the elements and their arrangement, materials, conditions, shapes, sizes, etc., of each embodiment are not limited to those exemplified and can be modified as appropriate. Furthermore, each embodiment is illustrative, and it goes without saying that partial substitution or combination of the configurations shown in different embodiments is possible, and these are also included within the scope of the present invention as long as they retain the features of the present invention.

[0129] (Appendix) 1. A light-emitting unit (11) including a light source (12) that emits light and a light-emitting lens (16) configured to concentrate the light from the light source (12), A light-receiving section (21, 21A) that receives light, It comprises a detection unit (40, 40A) that detects an object (TA) based on the received light, The light-emitting section (11) further includes a package (13) in which a light source (12) is installed on the bottom surface (13b) of a formed recess (13a), and a resin (14) that is light-transmitting and covers the light source (12). The side surface (13c) of the recess (13a) contains a material that absorbs light from the light source (12). Optical sensors (100, 200, 300, 400, 500). [Explanation of Symbols]

[0130] 10... Streamer, 11... Streamer unit, 12... Light source, 13... Package, 13a... Recess, 13b... Bottom, 13c... Side, 13d... Opening, 14... Resin, 15... Bonding wire, 16... Streamer lens, 19... Streamer drive circuit, 20... Receiver, 21, 21A... Receiver unit, 22... Shielding object, 26... Receiver lens, 29... Signal processing circuit, 40, 40A... Detection unit, 41... Determination unit, 42... Calculation unit, 50, 50A, 50B... Control unit 60, 60A, 60B... Input / Output I / F, 70, 70A, 70B... Memory Unit, 80, 80A, 80B... Input / Output Control Unit, 81, 81A, 81B... Operation Unit, 82, 82A, 82B... Output Unit, 100, 200, 300, 400, 500... Optical Sensor, 210, 310, 410, 510... Transmitter / Receiver, 530... Main Unit, BG... Background, EQ... Equipment, RP... Retroreflector, TA, TA1, TA2... Object, θ... Angle.

Claims

1. A light-emitting unit including a light source that emits light and a light-collecting element configured to concentrate the light from the light source, A light-receiving part that receives light, The system includes a detection unit that detects an object based on the received light, The light-emitting section further includes a package on which the light source is installed at the bottom surface of a formed recess, and a light-transmitting resin that covers the light source. The side surface of the recess contains a material that absorbs the light from the light source. Optical sensor.

2. The aforementioned side surface is connected to the bottom surface, and the angle between it and the bottom surface is greater than 90 degrees. The optical sensor according to claim 1.

3. The aforementioned side surface has a reflectance of 10% or less to the light of the light source. The optical sensor according to claim 1.

4. The aforementioned side surface is rough. The optical sensor according to claim 1.

5. The package is formed from a material that absorbs the light from the light source. The optical sensor according to claim 1.

6. The package is formed from a material that absorbs the light from the light source, and has a metal electrode pattern on the surface of its bottom, and the light source is connected to the metal electrode pattern. The optical sensor according to claim 1.

7. The light-emitting unit and the light-receiving unit are housed in separate enclosures. The light-emitting unit directs a light beam outwards, The light receiving unit is configured to be able to receive light emitted from the light emitting unit, The detection unit detects the object based on the change in the amount of light received. The optical sensor according to claim 1.

8. The light-emitting unit and the light-receiving unit are provided in a common housing. The light-emitting unit directs a light beam toward the retroreflector, The light-receiving unit is arranged to be able to receive light reflected by the retroreflector, The detection unit detects the object based on the change in the amount of light received. The optical sensor according to claim 1.

9. The light-emitting unit and the light-receiving unit are provided in a common housing. The light-emitting unit directs a light beam outwards, The light-receiving unit has a light-receiving field of view and is arranged to receive reflected light from the region where the light beam and the light-receiving field of view intersect. The detection unit detects the object based on the change in the amount of light received. The optical sensor according to claim 1.

10. The light-receiving axis of the light-receiving unit and the light-emitting axis of the light-emitting unit are configured to intersect such that the region where the light beam and the light-receiving field of view intersect is finite. The optical sensor according to claim 9.

11. The light-emitting unit directs a light beam outwards, The light-receiving unit is configured such that each of the multiple pixels can detect the amount of light received, and is configured to obtain a light-receiving amount distribution signal for each pixel with respect to the received light. The detection unit detects the target object based on the light reception distribution signal. The optical sensor according to claim 1.

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