Composite Sensor

Abstract

Provided is a composite sensor in which a substrate has a first surface and a second surface that face directions opposite to each other. An optical proximity sensor includes a first light emitting element and a first light receiving element that are disposed on the first surface of the substrate, and outputs a signal depending on the distance to an object through the first light receiving element receiving light emitted from the first light emitting element and reflected off the object. A force sensor is disposed on the second surface of the substrate, and outputs a signal depending on a component of force vertical to the substrate. A processing unit processes the signal from the optical proximity sensor and the signal from the force sensor, and calculates information regarding the distance to the object and information regarding the force received from the object.

Description

[Technical Field]

[0001] The present invention relates to a composite sensor. [Background technology]

[0002] For example, in next-generation game controllers, etc., there is a demand for the development of a sensor that can continuously acquire proximity information and pressure information in order to acquire information on finger movements and more detailed actions without being affected by hand size, etc. A composite sensor that combines a proximity sensor that measures the distance to an object and a force sensor that detects applied force is known (Patent Documents 1 and 2).

[0003] The composite sensor disclosed in Patent Document 1 includes a distance measurement sensor mounted on the front surface of a substrate, and a pressure measurement sensor and a contact detection sensor mounted on the back surface. The distance measurement sensor calculates distance by measuring the time interval between transmission and reception of ultrasonic waves. The pressure measurement sensor detects changes in capacitance due to deformation of a membrane and calculates pressure from the change in capacitance. The contact detection sensor is designed to have a larger amount of membrane deformation than the pressure measurement sensor, and detects contact with high sensitivity.

[0004] The composite sensor disclosed in Patent Document 2 includes a light-emitting unit, a light-receiving unit, and a dome-shaped elastic member that covers the light-emitting unit and the light-receiving unit. Light emitted from the light-emitting unit passes through the elastic member and is guided to the outside, and light reflected by the object passes through the elastic member and is received by the light-receiving unit. A mirror is disposed in a portion of the elastic member, and light emitted from the light-emitting unit and reflected by the mirror is received by the light-receiving unit. When the elastic member deforms, the amount of light reflected from the mirror disposed on the elastic member changes. From this change, the force applied to the elastic member is calculated. The distance to the object is calculated based on the light reception information of the light that passes through the elastic member, is reflected by the object, and is received by the light-receiving unit. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-39835 [Patent Document 2] International Publication No. 2020 / 017177 Summary of the Invention [Problem to be solved by the invention]

[0006] The composite sensor disclosed in Patent Document 1 uses an ultrasonic sensor as a distance measurement sensor. When an object approaches the distance measurement sensor, it becomes difficult to measure the distance due to the effects of reverberation time. Contact with the object is detected by a contact detection sensor, but when the distance to the object is between a certain proximity distance and contact (zero distance), it becomes impossible to measure the distance to the object. In other words, when an object approaches, it is difficult to continuously measure the distance from the proximity state to contact.

[0007] In the combined sensor disclosed in Patent Document 2, the light-emitting unit and the light-receiving unit are shared for measuring distance and force, which makes it difficult to design a sensor for measuring distance and a sensor for measuring force independently.

[0008] An object of the present invention is to provide a composite sensor that can perform measurements almost continuously, from measuring the distance to an object to measuring the force after contact, and that allows the sensor for measuring distance and the sensor for measuring force to be designed independently and appropriately. [Means for solving the problem]

[0009] According to one aspect of the present invention, a substrate having a first surface and a second surface facing in opposite directions; an optical proximity sensor including a first light emitting element and a first light receiving element disposed on the first surface of the substrate, the optical proximity sensor outputting a signal dependent on the distance to the object by receiving light emitted from the first light emitting element and reflected by the object with the first light receiving element; a force sensor disposed on the second surface of the substrate, the force sensor outputting a signal dependent on a component of a force perpendicular to the substrate; Equipped with 、 The force sensor includes a second light-emitting element, a second light-receiving element, an elastic member, and a reflector whose relative position with respect to the second light-emitting element and the second light-receiving element changes due to elastic deformation of the elastic member, and measures a change in the position of the reflector by receiving light, which is emitted from the second light-emitting element and reflected by the reflector, with the second light-receiving element. A composite sensor is provided. [Effects of the Invention]

[0010] Because an optical proximity sensor is used to measure distance, there is no reverberation effect like with ultrasonic sensors. This eliminates the measurement difficulties caused by the reverberation effect when an object approaches the sensor. In addition, because the optical proximity sensor is placed on the first surface of the board and the force sensor is placed on the second surface of the board, the design independence of the optical proximity sensor and the force sensor can be increased compared to a configuration in which the optical proximity sensor and force sensor share a light-emitting / receiving element. [Brief explanation of the drawings]

[0011] [Figure 1] 1A and 1B are a schematic perspective view and a schematic side view, respectively, of a composite sensor according to a first embodiment. [Figure 2] FIG. 2 is a schematic cross-sectional view of a composite sensor focusing on an optical proximity sensor. [Figure 3] FIG. 3 is a graph showing an example of measured distance and measured force values ​​when an object gradually approaches the composite sensor, comes into contact with the cover, and then applies force to the cover. [Figure 4] FIG. 4A is a schematic cross-sectional view of the composite sensor according to the second embodiment, and FIG. 4B is a schematic cross-sectional view of the composite sensor in a state where the elastic member is elastically deformed. [Figure 5] FIG. 5 is a diagram showing the positional relationship of a plurality of components when the first surface or the second surface of the substrate is viewed in plan. [Figure 6] FIG. 6 is a block diagram of a processing unit of a composite sensor according to the second embodiment. [Figure 7] FIG. 7 is a schematic cross-sectional view of a composite sensor according to the third embodiment. [Figure 8] FIG. 8 is a schematic cross-sectional view of a composite sensor according to a modified example of the third embodiment. [Figure 9] Figure 9A is a schematic oblique view of the substrate of a composite sensor according to the fourth embodiment, and the first light-emitting element and first light-receiving element of an optical proximity sensor, and Figure 9B is a diagram showing an example of the positional relationship in a planar view of four first light-emitting elements and one first light-receiving element. [Figure 10] FIG. 10 is a diagram showing the positional relationship and coordinate system between one first light-emitting element, a first light-receiving element, and an object. [Figure 11] FIG. 11 is a diagram showing the planar positional relationship between the first light emitting element and the first light receiving element of a composite sensor according to a modified example of the fourth embodiment. [Figure 12] FIG. 12 is a graph showing an example of a signal output by the composite sensor according to the fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] [First Example] A composite sensor according to a first embodiment will be described with reference to FIGS. 1A, 1B, 2, and 3. FIG. 1A and 1B are a schematic perspective view and a schematic side view, respectively, of a composite sensor 10 according to the first embodiment. The composite sensor 10 according to the first embodiment includes a substrate 11, an optical proximity sensor 20, and a force sensor 40. The optical proximity sensor 20 is disposed on one surface of the substrate 11 (hereinafter referred to as the first surface 11A), and the force sensor 40 is disposed on the surface of the substrate 11 facing in the opposite direction to the first surface 11A (hereinafter referred to as the second surface 11B).

[0013] A multilayer wiring board, such as a printed wiring board or a low temperature co-fired ceramic (LTCC) board, is used as the substrate 11. The substrate 11 includes wiring connected to the optical proximity sensor 20 and the force sensor 40.

[0014] The surface of the force sensor 40 facing the same direction as the second surface 11B is fixed to a device, such as a game controller, in contact with the housing 70. The housing 70 is made of a thermoplastic plastic commonly used for housings of home appliances, for example. The surface of the optical proximity sensor 20 facing the same direction as the first surface 11A is in contact with a cover 71 of the device. The cover 71 is transparent in the wavelength range of light used by the optical proximity sensor 20.

[0015] The optical proximity sensor 20 emits measurement light to the outside through the cover 71 under the control of the processing unit 50. The light reflected by the object passes through the cover 71 and is received by the optical proximity sensor 20. A signal including received light information is sent to the processing unit 50. The processing unit 50 calculates the distance to the object based on the received light information. The processing unit 50 is mounted on the substrate 11, for example.

[0016] When a force is applied to the cover 71, the force applied to the cover 71 is transmitted to the housing 70 via the optical proximity sensor 20, the substrate 11, and the force sensor 40. The force sensor 40 receives a reaction force from the housing 70 and measures the magnitude of the reaction force. That is, the force sensor sends a signal that depends on the component of the force perpendicular to the substrate 11 to the processing unit 50. The processing unit 50 calculates the magnitude of the force applied to the cover 71 based on the signal received from the force sensor 40. Note that the force sensor 40 may have a function to measure not only the component perpendicular to the substrate 11, but also the component of the force parallel to the substrate 11 (shear force).

[0017] Various known sensors can be used as the force sensor 40. For example, a piezoelectric force sensor, an optical force sensor, a capacitance force sensor, etc. can be used.

[0018] Next, the configuration of the optical proximity sensor 20 will be described with reference to Fig. 2. Fig. 2 is a schematic cross-sectional view of the composite sensor 10 focusing on the optical proximity sensor 20. The optical proximity sensor 20 includes a first light-emitting element 21 and a first light-receiving element 22 arranged on the first surface 11A of the substrate 11. The first light-emitting element 21 may be, for example, a light-emitting diode (LED) or a vertical-cavity surface-emitting laser (VCSEL). The first light-receiving element 22 may be, for example, a photodiode, a phototransistor, a CdS cell, or the like.

[0019] A spacer 25 is disposed between the cover 71 and the substrate 11. The spacer 25 maintains a constant distance between the first surface 11A and the cover 71. The surface of the cover 71 facing outward is referred to as the measurement reference surface 71A. The measurement reference surface 71A is parallel to the first surface 11A. The height from the light-receiving surface of the first light-receiving element 22 to the measurement reference surface 71A is denoted as H. The distance from the measurement reference surface 71A to the object 80 in the direction perpendicular to the first surface 11A is denoted as L.

[0020] Under control of the processing unit 50, measurement light is emitted from the first light-emitting element 21. The light emitted from the first light-emitting element 21 passes through the cover 71 and is emitted outside the device, and is reflected by the object 80. A portion of the light reflected from the object 80 passes through the cover 71 and is received by the first light-receiving element 22. A signal including light reception information by the first light-receiving element 22 is input to the processing unit 50.

[0021] The processing unit 50 acquires the signal from the optical proximity sensor 20 and the signal from the force sensor 40 in synchronization with each other. Here, "acquiring in synchronization" includes cases where the two signals are acquired simultaneously, where the acquisition times of the two signals are shifted in time but the amount of shift in acquisition time falls within a predetermined range, and where acquisition of one signal triggers acquisition of the other signal.

[0022] Furthermore, the processing unit 50 correlates and outputs data based on the signal from the optical proximity sensor 20 and data based on the signal from the force sensor 40, which are acquired in synchronization with each other. For example, the data based on the two signals may be stored in the same packet and output. Alternatively, a timestamp may be added to each piece of data based on the two signals, and the two pieces of data may be correlated via the timestamps.

[0023] The processing unit 50 may have a function of calculating the distance to the object 80 based on the received light information. For example, if the reflectance of the object 80 is known, the processing unit 50 can calculate the distance to the object 80 based on the amount of received light. The composite sensor 10 is calibrated so that the calculation result (measured value) of the distance L becomes zero when the object 80 comes into contact with the cover 71.

[0024] 3 is a graph showing an example of the measured values ​​of distance L and force F when an object 80 (FIG. 2) gradually approaches the composite sensor 10, comes into contact with the cover 71, and then applies force F to the cover 71. The horizontal axis represents elapsed time, the left vertical axis represents distance L, and the right vertical axis represents force F. In the graph, the solid line represents the measured value of distance L, and the dashed line represents the measured value of force F.

[0025] As time passes, the object 80 (FIG. 2) approaches the composite sensor 10 and comes into contact with the cover 71 at time t0. That is, the measured value of the distance L becomes zero. After time t0, the measured value of the distance L is maintained at zero. During the period in which the measured value of the distance L is greater than zero (the period before time t0), the measured value of the force F by the force sensor 40 is zero. After the object 80 comes into contact with the cover 71, a force is applied from the object 80 toward the housing 70 (FIG. 2). As a result, the measured value of the force F by the force sensor 40 rises from zero and fluctuates over time.

[0026] 3 shows an example in which the time when the measurement value of the distance L by the optical proximity sensor 20 reaches zero and the time when the measurement value of the force F by the force sensor 40 reaches zero coincide with each other, but they do not have to coincide exactly. For example, the measurement value of the force F may rise before the measurement value of the distance L reaches zero, or the measurement value of the force F may rise after the measurement value of the distance L reaches zero. Even if the time when the measurement value of the distance L reaches zero and the time when the measurement value of the force F reaches zero do not coincide with each other, it is acceptable as long as the difference between them is within an allowable range determined by the application that uses the output from the composite sensor 10.

[0027] Depending on the required specifications of the application, it is advisable to calibrate the processing unit 50 so that the measured value of the force F by the force sensor 40 rises from the point when the measured value of the distance L based on the signal from the optical proximity sensor 20 becomes zero.

[0028] Next, the excellent effects of the first embodiment will be described. In the first embodiment, an optical proximity sensor 20 is used as a sensor for measuring the distance to an object 80 (FIG. 2). Because it is not affected by reverberation time, etc., which occurs when an ultrasonic sensor is used, the distance can be measured until the object 80 almost comes into contact with the cover 71 (FIG. 2). When the object 80 comes into contact with the cover 71, a force F is measured based on a signal from the force sensor 40. Therefore, the distance and force can be measured almost continuously (seamlessly) from when the object 80 is away from the cover 71 until it approaches the cover 71, comes into contact with the cover 71, and applies a force to the cover 71.

[0029] Furthermore, because the processing unit 50 acquires the signals from the optical proximity sensor 20 and the force sensor 40 in synchronization with each other, it is possible to obtain distance measurements and force measurements at approximately the same time from these signals. Furthermore, because the processing unit 50 outputs data based on the signals from the optical proximity sensor 20 and the signals from the force sensor 40 acquired in synchronization with each other in a correlated manner, an application using the composite sensor 10 can continuously transition on the time axis from a state in which distance changes over time to a state in which force changes over time, or vice versa.

[0030] Furthermore, in the first embodiment, the optical proximity sensor 20 and the force sensor 40 can be designed independently, as long as the condition that the force applied to the cover 71 is transmitted to the force sensor 40 via the optical proximity sensor 20 is satisfied. This makes it easier to design the two sensors to meet the required specifications for the optical proximity sensor 20 and the force sensor 40, compared to a configuration in which the operations of the two sensors affect each other.

[0031] [Second Example] Next, a composite sensor according to a second embodiment will be described with reference to Figures 4A to 7. Below, a description of the configuration common to the composite sensor according to the first embodiment described with reference to Figures 1A to 3 will be omitted.

[0032] 4A is a schematic cross-sectional view of the composite sensor 10 according to the second embodiment. The configuration of the optical proximity sensor 20 is the same as the configuration of the optical proximity sensor 20 (FIG. 2) of the composite sensor 10 according to the first embodiment. In the second embodiment, an optical proximity sensor is also used for the force sensor 40. The force sensor 40 includes a second light-emitting element 41, a second light-receiving element 42, an elastic member 43, and a reflector 44. The second light-emitting element 41 may be, for example, a light-emitting diode (LED) or a vertical-cavity surface-emitting laser (VCSEL). The second light-receiving element 42 may be, for example, a photodiode, a phototransistor, a CdS cell, or the like.

[0033] The second light-emitting element 41 and the second light-receiving element 42 are disposed on the second surface 11B of the substrate 11. A reflector 44 is disposed at a distance from the second surface 11B. The reflector 44 is supported by the substrate 11 via an elastic member 43.

[0034] The reflector 44 is in contact with the housing 70. The Young's modulus of the elastic member 43 is lower than that of any of the housing 70, the substrate 11, and the spacer 25. When a force is applied to the cover 71, the elastic member 43 is elastically deformed. For example, the Young's modulus (flexural modulus) of the elastic member 43 is less than 1000 MPa.

[0035] 4B is a schematic cross-sectional view of the composite sensor 10 in a state where the elastic member 43 is elastically deformed. The elastic deformation of the elastic member 43 changes the relative position of the reflector 44 with respect to the second light-emitting element 41 and the second light-receiving element 42. As an example, the reflector 44 moves closer to the second light-emitting element 41 and the second light-receiving element 42. The amount of change in the relative position depends on the magnitude of the applied force.

[0036] Light emitted from the second light-emitting element 41 is reflected by the reflector 44, and a portion of the reflected light is received by the second light-receiving element 42. When the relative position of the reflector 44 with respect to the second light-emitting element 41 and the second light-receiving element 42 changes, the light reception information by the second light-receiving element 42, for example, the amount of light received, changes. A signal including the light reception information of the second light-receiving element 42 is input to the processing unit 50 (FIG. 1B). The processing unit 50 calculates the amount of displacement of the reflector 44 based on the light reception information of the second light-receiving element 42, and calculates the magnitude of the applied force from the amount of displacement.

[0037] 5 is a diagram showing the positional relationship of multiple components when the first surface 11A or the second surface 11B (FIG. 4A) of the substrate 11 is viewed from above (hereinafter simply referred to as "in a plan view"). An elastic member 43 is disposed so as to surround the second light-emitting element 41 and the second light-receiving element 42. The elastic member 43 has, for example, a circular ring shape.

[0038] The smallest inclusive circle 26 that encompasses the first light-emitting element 21 and the first light-receiving element 22 of the optical proximity sensor 20 and the smallest inclusive circle 46 that encompasses the second light-emitting element 41 and the second light-receiving element 42 of the force sensor 40 have a mutually overlapping portion. The composite sensor 10 has a structure in which the force sensor 40 and the optical proximity sensor 20 are stacked in the thickness direction of the substrate 11. While FIG. 5 shows an example in which the smallest inclusive circle 26 that encompasses the first light-emitting element 21 and the first light-receiving element 22 is smaller than the smallest inclusive circle 46 that encompasses the second light-emitting element 41 and the second light-receiving element 42, the size relationship may be reversed. Also, a configuration in which a portion of one smallest inclusive circle 26 overlaps a portion of the other smallest inclusive circle 46 may be used.

[0039] 6 is a block diagram of a processing unit 50 of the composite sensor 10 according to the second embodiment. The anodes of the first light-emitting element 21 and the second light-emitting element 41 are each connected to a power supply 51, and the cathodes are connected to a light-emitting element driver 53 via a switch matrix 52. A calculation unit 58 controls the light-emitting element driver 53 and the switch matrix 52 via an interface unit 54. When one of the first light-emitting element 21 and the second light-emitting element 41 is selected by the switch matrix 52, the selected light-emitting element emits light.

[0040] The first light receiving element 22 and the second light receiving element 42 are connected to a switch matrix 55. A calculation unit 58 controls the switch matrix 55 via an interface unit 54. When one of the first light receiving element 22 and the second light receiving element 42 is selected by the switch matrix 55, a current generated in the selected light receiving element according to the amount of light received is input to a transimpedance amplifier 56 via the switch matrix 55.

[0041] The current output from the first light receiving element 22 or the second light receiving element 42 is converted into a voltage signal by the transimpedance amplifier 56 and input to the AD converter 57. The voltage signal is converted into a digital signal by the AD converter 57 and input to the calculation unit 58 via the interface unit 54.

[0042] The calculation unit 58 alternately causes the first light-emitting element 21 and the second light-emitting element 41 to emit light at different timings. When the first light-emitting element 21 emits light, light reception information by the first light-receiving element 22 is obtained, and when the second light-emitting element 41 emits light, light reception information by the second light-receiving element 42 is obtained. The calculation unit 58 calculates the distance L to the object 80 (FIG. 2) from the light reception information by the first light-receiving element 22, and calculates the magnitude of the force F applied to the cover 71 (FIG. 4B) from the light reception information by the second light-receiving element 42. That is, the calculation unit 58 alternately calculates the distance L and the force F.

[0043] Next, the excellent effects of the second embodiment will be described. In the second embodiment, the force sensor 40 also uses an optical proximity sensor for measuring distance similar to the optical proximity sensor 20. Therefore, the optical proximity sensor 20 and the force sensor 40 can share the same analog front-end circuit including the light-emitting element driver 53, the transimpedance amplifier 56, the AD converter 57, etc.

[0044] Sharing the analog front-end circuit facilitates synchronization and timing control between the optical proximity sensor 20 and the force sensor 40. This makes it easy to seamlessly measure distance using the optical proximity sensor 20 and measure force using the force sensor 40.

[0045] 5, the smallest including circle 26 of the first light-emitting element 21 and the first light-receiving element 22 and the smallest including circle 46 of the second light-emitting element 41 and the second light-receiving element 42 at least partially overlap in a plan view, so that the position serving as the reference for measuring distance and the position serving as the reference for measuring force are close to each other within the first surface 11A (FIG. 4A) of the substrate 11. This reduces the deviation between the approach detection position and the contact detection position of the object 80 (FIG. 2), making it possible to provide a detection result that is less uncomfortable for the user.

[0046] Because the Young's modulus of the elastic member 43 of the force sensor 40 is smaller than the Young's modulus of the spacer 25, the substrate 11, and the housing 70 (FIG. 4A), deformation due to a force applied to the cover 71 is mostly localized to the elastic member 43. This allows the force sensor 40 to accurately measure the force applied to the cover 71. Furthermore, if the condition that the rigidity of the elastic member 43 of the force sensor 40 is lower than the rigidity of the spacer 25 of the optical proximity sensor 20 is met, the independence of the designs of the optical proximity sensor 20 and the force sensor 40 can be increased. This makes it easier to design the two sensors to meet the required specifications for the optical proximity sensor 20 and the force sensor 40, compared to a configuration in which the operations of the two sensors affect each other.

[0047] Next, a composite sensor according to a modification of the second embodiment will be described. In the second embodiment, the analog front-end circuit (FIG. 6) including the light-emitting element driver 53, transimpedance amplifier 56, AD converter 57, etc. is shared by the optical proximity sensor 20 and the force sensor 40. However, one analog front-end circuit may be provided for each of the optical proximity sensor 20 and the force sensor 40. In this case, the optical proximity sensor 20 and the force sensor 40 can be operated simultaneously. This eliminates the timing difference between the acquisition of distance information and the acquisition of force information when the object 80 comes into contact with the cover 71 (FIG. 4A). Furthermore, the time resolution of the measured distance and force values ​​can be improved.

[0048] [Third Example] Next, a composite sensor according to a third embodiment will be described with reference to Fig. 7. Below, a description of the configuration common to the composite sensor according to the first embodiment described with reference to Figs. 1A to 3 will be omitted.

[0049] 7 is a schematic cross-sectional view of a composite sensor 10 according to a third embodiment. In the first embodiment (FIG. 2), the optical proximity sensor 20 includes one first light-emitting element 21 and one first light-receiving element 22. In contrast, in the third embodiment, the optical proximity sensor 20 includes two first light-emitting elements 21 and one first light-receiving element 22. An optical proximity sensor 20 having such a configuration is shown in, for example, Japanese Patent Publication No. 57-133306. The principle of distance measurement using the optical proximity sensor 20 according to the third embodiment will be briefly described below.

[0050] Each of the two first light-emitting elements 21 emits light that is highly diffused and spreads uniformly. The centers of the light-emitting portions of the two first light-emitting elements 21 are denoted as Q and R, respectively. The first light-receiving element 22 has strong directivity in the normal direction of the first surface 11A. The center of the light-receiving surface of the first light-receiving element 22 is denoted as S.

[0051] The two first light-emitting elements 21 are driven by repeating signals that are 90° out of phase with each other. An object 80 exists on a line extending from point S in a direction perpendicular to the first surface 11A. The intersection of the surface of the object 80 and the line extending from point S in a direction perpendicular to the first surface 11A is labeled P. The angle between line segments PQ and PS is labeled θ1, and the angle between line segments PR and PS is labeled θ2. The lengths of line segments QS and RS are labeled a and b, respectively.

[0052] The light emitted from each of the two first light-emitting elements 21 is diffusely reflected at point P on the surface of the object 80, and part of the diffusely reflected light is received by the first light-receiving element 22. The brightness of the light emitted from each of the two first light-emitting elements 21 can be considered to change periodically in the form of sine waves and cosine waves.

[0053] At this time, the length of line segment PS can be calculated using the relationship between the phase of the intensity change of light emitted from one of the first light-emitting elements 21 and the phase of the intensity change of light received by first light-receiving element 22, lengths a, b, and angles θ1 and θ2. The calculation formula is shown in Japanese Patent Publication No. 57-133306. Since the height H from the light-receiving surface of first light-receiving element 22 to measurement reference surface 71A is known, the distance L from measurement reference surface 71A to object 80 can be calculated.

[0054] Next, the excellent effects of the third embodiment will be described. In the third embodiment, the distance L to the object 80 can be measured without depending on the reflectance of the surface of the object 80 .

[0055] Next, a modified example of the third embodiment will be described with reference to FIG. 8 is a schematic cross-sectional view of a composite sensor 10 according to a modification of the third embodiment. In this modification, the force sensor 40 includes two second light-emitting elements 41 and one second light-receiving element 42, similar to the optical proximity sensor 20. With this configuration, the distance from the second light-receiving element 42 to the reflector 44 can be measured without depending on the reflectance of the reflector 44.

[0056] [Fourth Example] Next, a composite sensor according to a fourth embodiment will be described with reference to Figures 9A, 9B, and 10. Below, a description of the configuration common to the composite sensor according to the first embodiment described with reference to Figures 1A to 3 will be omitted. The fourth embodiment differs from the first embodiment in the configuration of the optical proximity sensor 20.

[0057] 9A is a schematic perspective view of the substrate 11 of the composite sensor according to the fourth embodiment, and the first light-emitting element 21 and the first light-receiving element 22 of the optical proximity sensor 20. In the fourth embodiment, the optical proximity sensor 20 includes four first light-emitting elements 21 and one first light-receiving element 22. In FIG. 9A, the first light-emitting element 21 is represented by a hollow circle, and the first light-receiving element 22 is represented by a hatched circle.

[0058] The four first light-emitting elements 21 and one first light-receiving element 22 are arranged on a common imaginary plane. For example, the four first light-emitting elements 21 and one first light-receiving element 22 are mounted on the flat first surface 11A of the substrate 11. The object 80 is located on an imaginary line (hereinafter referred to as a reference axis 27) that passes through the first light-receiving element 22 and extends in the normal direction of the first surface 11A. The distance from the first surface 11A to the object 80 and the attitude of the object 80 are detected based on the intensity of light that is emitted from each of the first light-emitting elements 21, reflected by the object 80, and incident on the first light-receiving element 22. Here, "passing through the first light-receiving element 22" means passing through the geometric center of the light-receiving area of ​​the first light-receiving element 22.

[0059] FIG. 9B is a diagram illustrating an example of the positional relationship between four first light-emitting elements 21 and one first light-receiving element 22 in a plan view. The four first light-emitting elements 21 are not arranged on a common straight line passing through the first light-receiving element 22, nor are they arranged on a common circumference centered on the first light-receiving element 22. That is, when a line SL is drawn passing through the first light-receiving element 22 and one first light-emitting element 21, at least one of the other three first light-emitting elements 21 is arranged at a position deviating from the line SL. In the example illustrated in FIG. 9B, two first light-emitting elements 21 are arranged at a position deviating from the line SL. Furthermore, when a circumference C is drawn centered on the first light-receiving element 22 and passing through one first light-emitting element 21, at least one of the other three first light-emitting elements 21 is arranged at a position deviating from the circumference C. In the example illustrated in FIG. 1B, two first light-emitting elements 21 are arranged at a position deviating from the circumference C.

[0060] Here, whether the first light-emitting element 21 is located on the line SL or the circumference C is determined based on the geometric center of the light-emitting area of ​​the first light-emitting element 21. Whether the first light-receiving element 22 is located on the line SL is determined based on the geometric center of the light-receiving area of ​​the first light-receiving element 22. The circumference centered on the first light-receiving element 22 means the circumference centered on the geometric center of the light-receiving area of ​​the first light-receiving element 22. Due to this arrangement, the distance between at least one first light-emitting element 21 and the first light-receiving element 22 is different from the distances between the other three first light-emitting elements 21 and the first light-receiving element 22. A total of four light-emitting and receiving pairs are configured by each of the four first light-emitting elements 21 and one first light-receiving element 22.

[0061] Next, the definitions of the coordinate system and various parameters used in the description of the fourth embodiment will be described with reference to Fig. 10. Fig. 10 is a diagram showing the positional relationship and coordinate system between one first light-emitting element 21i, the first light-receiving element 22, and the target object 80. The xy plane of the xyz Cartesian coordinate system corresponds to the first surface 11A (Fig. 9A), and the first light-receiving element 22 is disposed at the origin O. The z axis corresponds to the reference axis 27. Note that a left-handed system is used as the xyz Cartesian coordinate system.

[0062] When the four first light-emitting elements 21 are numbered in order starting from 1, the i-th first light-emitting element 21 is denoted as 21i. The x and y coordinates of the first light-emitting element 21i are respectively xi , a yi The distance from the origin O to the first light-emitting element 21i is denoted as r i The azimuth angle of the position of the first light-emitting element 21 when the x-axis is the reference direction is denoted as θ ri It is marked as follows.

[0063] The intersection of the surface of the object 80 facing the origin O and the reference axis 27 (hereinafter referred to as the representative point of the object 80) is denoted as P. The distance from the origin O (first light receiving element 22) to the representative point P of the object 80 is denoted as z. In the explanation of the fourth embodiment, the distance z from the first light receiving element 22 to the representative point P of the object 80 may be simply referred to as the distance z from the first light receiving element 22 to the object 80. The unit vector pointing from the representative point P of the object 80 to the first light emitting element 21i is denoted as n.i The unit vector n i The angle between the reference axis 27 and i It is marked as follows.

[0064] The unit normal vector of the surface of the object 80 at the position of the representative point P is n s The unit normal vector n s and the angle between the reference axis 27 is φ z The angle φ is z is called the tilt angle of the object 80. The unit normal vector n s The angle between the vertical projection onto the xy plane and the x-axis is φ x The angle φ is x is called the tilt azimuth angle of the surface of the object 80.

[0065] Next, the directivity characteristics of the first light emitting element 21 and the first light receiving element 22 will be described. In the first light emitting element 21, the light intensity is maximum in the front direction, and as the tilt angle θ from the front direction increases, the light intensity decreases. The tilt angle θ at which the light intensity becomes half of the light intensity in the front direction is called the half-maximum angle θ. 1 / 2 The first light receiving element 22 has a maximum light sensitivity in the front direction, and the light sensitivity decreases as the tilt angle θ increases. The tilt angle θ at which the light sensitivity becomes half of the light sensitivity in the front direction is called the half-maximum half-angle θ. 1 / 2 That's what they say.

[0066] The first light-emitting element 21 has a wider angle of directivity than the first light-receiving element 22. For example, the first light-emitting element 21 has a wide-angle of directivity such that light of sufficient intensity is irradiated onto an object 80 (FIG. 9A) located on the reference axis 27. The first light-receiving element 22 has a sharp directional characteristic such that the sensitivity is sufficiently low to reflected light from an object located far away from the reference axis 27. For example, the half-angle at half maximum θ of the directional characteristic of the first light-receiving element 22 is 1 / 2 is preferably 15° or less, more preferably 10° or less, and most preferably 5° or less.

[0067] When the directivity characteristic of the first light-emitting element 21 does not depend on the azimuth angle, the directivity characteristic LD(θ) of the first light-emitting element 21 can generally be approximated by the following equation.

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[0068] The light emission intensity of the i-th first light emitting element 21i in the front direction is G i and the light receiving sensitivity of the first light receiving element 22 is denoted as C. The reflectance of the surface of the object 80 is denoted as α. The light intensity LIi at the representative point P is expressed by the following equation. Note that the four first light emitting elements 21 have the same directional characteristic LD(θ).

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[0069] The intensity of light detected by the first light receiving element 22, that is, the luminance Li of the representative point P when the representative point P is viewed as a new light source from the first light receiving element 22, is expressed by the following formula.

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[0070] The denominator z on the right side of equation (3) β The term z indicates that as the distance z increases, the field of view of the first light receiving element 22 widens, and the contribution of the luminance per unit area of ​​the surface of the object 80 (FIG. 1A) decreases. When light is irradiated onto a wide area of ​​the surface of the object 80, and the surface of the object 80 is larger than the field of view of the first light receiving element 22, the light is received over the entire field of view of the first light receiving element 22 even if the distance z increases. In such a case, z β The influence of the term (a) is small depending on the shape and size of the object 80, the half-angle at half maximum θ of the directional characteristics of the first light receiving element 22, and the 1 / 2 In reality, β in equation (3) takes any value in the range of 0 to 2, depending on the magnitude of

[0071] The parameter CαG on the right side of equation (3) i / z β is common to the four first light-emitting elements 21, so in equation (3), the unknown is the parameter CαG i / z β , distance z, tilt azimuth φ x , inclination angle φ z and four equations (3) are generated for i=1, 2, 3, 4. The four first light-emitting elements 21 are not arranged on a single common line passing through the first light-receiving element 22, nor are they arranged on a single common circumference centered on the first light-receiving element 22, so the four equations are linearly independent. For this reason, the processing unit 50 solves this simultaneous equation with four unknowns to calculate the parameter CαG i / z β , distance z, tilt azimuth φ x , inclination angle φ z can be obtained.

[0072] Next, the excellent effects of the fourth embodiment will be described. In the fourth embodiment, four first light-emitting elements 21 and one first light-receiving element 22 are used to measure the distance z and the tilt azimuth angle φ x , inclination angle φ z That is, in addition to the distance to the object 80, the azimuth and tilt angle at which the surface of the object 80 is inclined can be obtained.

[0073] In the object detection sensor according to the fourth embodiment, the directional characteristics LD(θ) of the four first light-emitting elements 21 are isotropic and do not depend on the azimuth angle, but they do not necessarily have to be isotropic. For example, if the directional characteristics can be converted into a form that is not azimuth-angle dependent by coordinate transformation, the directional characteristics do not necessarily have to be isotropic.

[0074] For example, the half-width at half maximum θ in the xz plane shown in FIG. 1 / 2 is the half-angle θ in the yz plane 1 / 2 If the value of the y-axis is doubled, the half-angle at half maximum θ in the xz plane 1 / 2 is the half-angle θ in the yz plane 1 / 2This is equivalent to the case where the directional characteristics do not have azimuth angle dependency. Therefore, by performing coordinate transformation, a simultaneous equation of the same form as equation (3) can be obtained.

[0075] Next, a composite sensor according to a modification of the fourth embodiment will be described with reference to FIG. FIG. 11 is a diagram showing the planar positional relationship between the first light-emitting element 21 and the first light-receiving element 22 of a composite sensor according to a modified example of the fourth embodiment.

[0076] In the fourth example (FIG. 9B), none of the three first light-emitting elements 21 among the four first light-emitting elements 21 are arranged on a single straight line, and the four first light-emitting elements 21 are not arranged on a common circumference centered on the first light-receiving element 22. In this modified example, the four first light-emitting elements 21 are arranged so as to satisfy not only this condition but also the following condition.

[0077] In this modification, two of the four first light-emitting elements 21, 21a1 and 21a2, are arranged in point-symmetric positions with respect to the first light-receiving element 22, and the other two first light-emitting elements 21b1 and 21b2 are also arranged in point-symmetric positions with respect to the second light element. The distances from the first light-receiving element 22 to each of the first light-emitting elements 21a1 and 21a2 are defined as r a and the distance from the first light receiving element 22 to each of the first light emitting elements 21b1 and 21b2 is represented by r b The angle formed by a line passing through the two first light-emitting elements 21a1 and 21a2 and a line passing through the other two first light-emitting elements 21b1 and 21b2 is denoted as δ. The angle δ is greater than 0° and less than 180°.

[0078] Two first light-emitting elements 21 positioned point-symmetrically to each other are referred to as a first light-emitting element pair. In this modification, two first light-emitting elements 21a1 and 21a2 constitute one first light-emitting element pair 21a, and the other two first light-emitting elements 21b1 and 21b2 constitute another first light-emitting element pair 21b.

[0079] When formula (3) is applied to the first light-emitting element 21a1, the following formula is obtained.

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[0080] When formula (3) is applied to the first light-emitting element 21a2, the following formula is obtained.

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[0081] In formulas (4) and (5), G a1 =G a2 , θ ra1 +θ ra2 = 180°, the following equation is obtained from equations (4) and (5):

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[0082] Similarly, the following equations are obtained for the first light-emitting elements 21b1 and 21b2:

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[0083] The ratio R between the sum of the measurement values ​​when each of the first light-emitting element pair 21a consisting of the first light-emitting elements 21a1 and 21a2 is made to emit light and the light is received by the first light-receiving element 22 and the sum of the measurement values ​​when each of the first light-emitting element pair 21b consisting of the first light-emitting elements 21b1 and 21b2 is made to emit light and the light is received by the first light-receiving element 22 is expressed by the following equation from equations (6) and (7).

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[0084] Since the only unknown in equation (8) is z, the distance z to the object 80 can be calculated from the ratio R.

[0085] Furthermore, for the first light-emitting element pair 21a, the following equation is obtained from equations (4) and (5):

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[0086] Similarly, the following equation is obtained for the first light-emitting element pair 21b.

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[0087] From equations (9) and (10), the following equation is derived:

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[0088] The value of parameter A1 can be calculated from equation (11). Once the value of parameter A1 is known, the tilt angle φ can be calculated from equation (12). z Furthermore, from equation (9), the tilt azimuth angle φ x In this way, the tilt angle φ can be calculated by finding the sum and difference of the measured values ​​from the two first light-emitting element pairs 21a and 21b and performing simple algebraic calculations. z and inclination azimuth φ x can be calculated.

[0089] Next, the excellent effects of the modification of the fourth embodiment shown in FIG. 11 will be described. In the modification of the fourth embodiment, the distance z to the object 80 and the inclination angle φ of the surface of the object 80 can be calculated by simple algebraic calculations without solving simultaneous equations with four unknowns. z , and the tilt azimuth angle φ x can be obtained.

[0090] [Fifth Example] Next, a composite sensor according to a fifth embodiment will be described with reference to Fig. 12. Below, a description of the configuration common to the composite sensors according to the first and second embodiments described with reference to Figs. 1A to 6 will be omitted.

[0091] 12 is a graph showing an example of signals output by the composite sensor according to Example 5. As an example, as shown in FIG. 3, the composite sensor 10 according to Example 1 outputs a measurement value of distance L calculated based on a signal from the optical proximity sensor 20 and a measurement value of force F calculated based on a signal from the force sensor 40.

[0092] In contrast, the composite sensor 10 according to the fifth embodiment determines the amount of displacement of the reflector 44 relative to the second light-emitting element 41 and the second light-receiving element 42 shown in FIG. 4A based on a signal from the force sensor 40. The amount of displacement when no external force is applied to the force sensor 40 is defined as zero. When an external force is applied to the force sensor 40, the reflector 44 is displaced in a direction approaching the second light-emitting element 41 and the second light-receiving element 42. The amount of displacement in this direction is defined as negative. The magnitude of the amount of displacement changes depending on the magnitude of the force applied to the composite sensor 10. In FIG. 12, the change in the amount of displacement over time is indicated by a dashed line.

[0093] 12, when the object 80 (FIG. 2) is gradually brought closer to the composite sensor 10 and the measurement value of the distance L by the optical proximity sensor 20 becomes zero (time t0), if the object 80 is further pressed, the measured value of the displacement amount rises in the negative direction. The measured value of the displacement amount changes as the amount of pressing changes.

[0094] An application that uses the composite sensor 10 can calculate the force applied to the composite sensor 10 based on the measured value of the displacement output from the composite sensor 10.

[0095] Next, the excellent effects of the fifth embodiment will be described. Even in a configuration in which the amount of displacement is calculated based on a signal from the force sensor 40, as in the fifth embodiment, it is possible to continuously transition from a state in which the measurement value of the distance L by the optical proximity sensor 20 changes over time to a state in which the measurement value of the amount of displacement by the force sensor 40 changes over time, or vice versa. In addition, the application can calculate the force being applied to the force sensor 40 based on the measurement value of the amount of displacement output from the composite sensor 10.

[0096] The above-described embodiments are merely examples, and it goes without saying that partial substitution or combination of the configurations shown in different embodiments is possible. Similar effects resulting from similar configurations of multiple embodiments will not be mentioned sequentially for each embodiment. Furthermore, the present invention is not limited to the above-described embodiments. For example, it will be obvious to those skilled in the art that various modifications, improvements, combinations, etc. are possible. [Explanation of symbols]

[0097] 10 Composite Sensor 11 Circuit Board 11A 1st page 11B 2nd side 20 Optical proximity sensor 21, 21a1, 21a2, 21b1, 21b2 first light-emitting element 21a, 21b First light-emitting element pair 22 First light receiving element 25 spacer 26 Minimum Enclosing Circle 40 Force Sensor 41 Second light-emitting element 42 Second light receiving element 43 Elastic member 44 Reflector 46 Minimum Enclosing Circle 47 Reference plane 50 Processing section 51 Power supply 52 Switch Matrix 53 Light Emitting Device Driver 54 Interface section 55 Switch Matrix 56 Transimpedance Amplifier 57 AD converter 58 Arithmetic section 70 Case 71 Cover 71A Measuring reference plane 80 Objects

Claims

1. a substrate having a first surface and a second surface facing in opposite directions; an optical proximity sensor including a first light emitting element and a first light receiving element disposed on the first surface of the substrate, the optical proximity sensor outputting a signal dependent on the distance to the object by receiving light emitted from the first light emitting element and reflected by the object with the first light receiving element; a force sensor disposed on the second surface of the substrate, the force sensor outputting a signal dependent on a component of a force perpendicular to the substrate; Equipped with The force sensor includes a second light-emitting element, a second light-receiving element, an elastic member, and a reflector whose relative position with respect to the second light-emitting element and the second light-receiving element changes due to elastic deformation of the elastic member, and measures changes in the position of the reflector by receiving reflected light emitted from the second light-emitting element and reflected by the reflector with the second light-receiving element.

2. The composite sensor according to claim 1 , wherein the elastic member is disposed so as to surround the second light emitting element and the second light receiving element when the second surface of the substrate is viewed in plan view.

3. 3. The composite sensor according to claim 1, wherein when the first surface of the substrate is viewed in a plane, the smallest inclusive circle that encompasses the first light-emitting element and the first light-receiving element of the optical proximity sensor and the smallest inclusive circle that encompasses the second light-emitting element and the second light-receiving element of the force sensor have mutually overlapping portions.

4. 4. The composite sensor according to claim 1, wherein when the force sensor is mounted on a device with a surface of the force sensor facing the same direction as the second surface in contact with the housing of the device, and the optical proximity sensor is used with a surface of the optical proximity sensor facing the same direction as the first surface in contact with a cover that is transparent in the wavelength range of light emitted from the first light-emitting element, the composite sensor has a structure in which a force applied to the cover is transmitted to the housing via the optical proximity sensor, the substrate, and the force sensor.

5. The composite sensor according to claim 1 , further comprising a processing unit that acquires a signal from the optical proximity sensor and a signal from the force sensor in synchronization with each other.

6. The composite sensor according to claim 5 , wherein the processing unit outputs data based on the signal from the optical proximity sensor and data based on the signal from the force sensor, which are acquired in synchronization with each other, in association with each other.

7. 7. The composite sensor according to claim 5, wherein the processing unit is shared by the optical proximity sensor and the force sensor, and the optical proximity sensor and the force sensor are operated alternately to alternately acquire signals from the optical proximity sensor and signals from the force sensor.

8. The composite sensor according to claim 5 , wherein the processing unit calculates a distance to the object based on a signal from the optical proximity sensor, and calculates a force based on a signal from the force sensor.

9. 9. The composite sensor according to claim 8, wherein the processing unit is calibrated so that, when the object gradually approaches the optical proximity sensor, the calculation result of the force based on the signal from the force sensor starts to rise from the point when the calculation result of the distance based on the signal from the optical proximity sensor becomes zero.

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