JP6505506B2 - Optical sensor and electronic device - Google Patents

Description

  The present invention relates to an optical sensor that measures the distance to a detection object using light reflected by the detection object.

  Patent Document 1 discloses a triangulation distance measuring apparatus which measures the distance to a specular object using the principle of triangulation. Patent Document 2 discloses a distance measuring device including a device for projecting and receiving light at different angles, and determining whether or not the received light is multi-reflected light with specular reflection. Patent Document 3 discloses an optical three-dimensional camera which selects one of a triangulation method and a time of flight (TOF) method.

JP-A-8-261752 (released on October 11, 1996) Unexamined-Japanese-Patent No. 2009-150862 (July 9, 2009 publication) Unexamined-Japanese-Patent No. 2013-104784 (May 30, 2013 publication)

  The triangulation type distance measuring device of Patent Document 1 and the light three-dimensional camera of Patent Document 3 can not determine whether the surface of the detection object is a mirror surface. The distance measuring device of Patent Document 2 has a complicated mechanism for changing the angle of the light emitting device. In view of the above problems, the present invention is an optical sensor that measures the distance to a detection object using light reflected by the detection object, and provides an optical sensor and an electronic device that can easily determine the surface state of the detection object. The purpose is to

  In order to solve the above-mentioned subject, an optical sensor concerning one mode of the present invention is an optical sensor which measures distance to a detection object using light reflected to a detection object, and emits light to one way. A light emitting element, a plurality of avalanche photodiodes arranged in a direction perpendicular to the one direction of the light emitting element, a case separating the detection object and the light emitting element, the light emitting element and the plurality of avalanche photodiodes And a control unit for specifying the distance by TOF method and triangulation method, and a distance between the light emitting element and the avalanche photodiode closest to the The light emitted from the light emitting element is equal to the spot diameter spread on the surface of the detection object when contacting the housing, and the control unit determines the specified distance and the aba. By comparing the light receiving position of the emission Chez photodiode, for detecting the surface state of the detection object.

  Further, an electronic device according to one aspect of the present invention includes the light sensor.

  According to each aspect of the present invention, it is possible to easily determine the surface state of the detection object.

FIG. 1 is a front view showing a configuration of an optical sensor of Embodiment 1. The surface of the detection object is a mirror surface. It is a front view which shows the structure of the optical sensor shown by FIG. The surface of the detection object is not a mirror surface. FIG. 7 is a front view showing a configuration of an optical sensor of Embodiment 2. It is a front view which shows the structure of the optical sensor shown by FIG. The detection object is tilted with respect to the light sensor. FIG. 13 is a schematic view showing a configuration for determining the surface state of a detection object according to Embodiment 3. FIG. 16 is a circuit diagram showing a configuration for measuring the distance from the light sensor of the fourth embodiment to a detection object. It is a front view and a bottom view showing composition of a robot cleaner of Embodiment 5.

Embodiment 1
A first embodiment of the present invention will be described with reference to FIGS. 1 and 2.

<< Configuration of optical sensor 1 >>
FIG. 1 is a front view showing the configuration of the light sensor 1 according to the present embodiment, in which (a) shows the entire configuration, and (b) shows a partial configuration around the light emitting element 11 and the light receiving element 12. In FIG. 1, the surface of the detection object A is a mirror surface. As shown in (a) of FIG. 1, the light sensor 1 includes a light emitting element 11, a plurality of light receiving elements 12, a lens 13, a control unit 15, and a housing indicated by a broken line.

(Light emitting element)
The light emitting element 11 emits light in one direction along the optical axis OA. For example, a light emitting diode (LED; Light Emitting Diode) can be used as the light emitting element 11. The light emitted from the light emitting element 11 spreads as it propagates in space. The light beams Ll and Lr are lines visually indicating the range in which the light emitted from the light emitting element 11 spreads. In FIG. 1, the light emitted from the light emitting element 11 spreads in the horizontal direction in FIG. 1, but also spreads in the depth direction in FIG. 1. When the detection object A is in the light propagation path, the light is reflected on the surface of the detection object A. The light reflected to the detection object A is condensed to the light receiving element 12 through the lens 13.

(Light receiving element)
The light receiving element 12 is an avalanche photodiode arranged in a direction perpendicular to the optical axis OA. An avalanche photodiode is a light detection diode provided with an amplification function by using electron avalanche multiplication (avalanche multiplication) in a semiconductor. In an avalanche photodiode, light with energy larger than the forbidden band width of a semiconductor is irradiated, and free electrons and holes generated as carriers are subjected to avalanche multiplication in a diode to which a reverse voltage is applied. The light is converted into an electrical signal and amplified at the same time. For this reason, the response speed of the avalanche photodiode is faster than, for example, other diodes, for example, 1 GHz or more. The optical sensor 1 can calculate the distance to the detection object A by the TOF method by providing such a light receiving element 12. Although not limited to this, the dimension of the light receiving element 12 is about 10 μm in the horizontal direction of FIG.

(Operation mode of light receiving element)
It is preferable that the light receiving element 12 operate in Geiger mode. In the light receiving element 12 operating in Geiger mode, avalanche amplification also occurs by the incidence of a single photon. Therefore, the light receiving element 12 can obtain a large output current. Such a light receiving element 12 is called a single photon avalanche diode (SPAD).

  The detection signal obtained by converting the light into an electric signal by the light receiving element 12 is affected by parasitic capacitance as the frequency is higher, and a signal delay occurs and the amplitude decreases. At this time, detection of the detection signal becomes difficult. Then, the closer the detection object A and the light sensor 1 are, the higher the detection signal becomes. However, when the light receiving element 12 operates in Geiger mode, the amplitude can be increased along with the high speed driving of the detection signal. Therefore, by providing such a light receiving element 12, the light sensor 1 can calculate the distance to the detection object A closer by the TOF method.

  When the light receiving element 12 operates in Geiger mode, the adverse effect of disturbance light may increase in the calculation of the distance. This adverse effect can be suppressed by changing the bias voltage of the light receiving element 12 or changing the amount of current of the current source connected in series to the light receiving element 12 together with the disturbance light.

(Detected object)
The detection object A can move to, for example, a position closer to the light sensor 1 indicated by the detection object Aa, or a position farther from the light sensor 1 indicated by the detection object Ab. The detection object Aa is moved to a position where the detection object A contacts the housing (dotted line) of the light sensor 1. The closest contact distance d is the distance between the detection object Aa and the light emitting element 11. The housing of the light sensor 1 separates the detection object A from the light emitting element 11. Therefore, the detection object A does not move to a position closer to the light sensor 1 than the detection object Aa.

  As shown in (b) of FIG. 1, the light beam Lr emitted from the light emitting element 11 is incident on the surface of the detection object Aa at an angle θ with respect to the symmetry axis SA. The light ray LR is a reflection of the light ray Lr to the detection object Aa, and reflects from the surface of the detection object Aa at an angle θ with respect to the symmetry axis SA. Then, the light beam LR enters the light receiving element 121 via the lens 13. When the refraction by the lens 13 is very small, the light emitted from the light emitting element 11 is a detection object at a distance r between the optical axis OA and the end of the light receiving element 121 disposed closest to the light emitting element 11 It is approximately equal to the spot diameter D spreading on the surface of Aa. That is, the end on the light emitting element 11 side of the light receiving element 121 is disposed at a position symmetrical to the light emitting element 11 with respect to the symmetry axis SA.

(Control unit)
The control unit 15 is connected to the light emitting element 11 and the light receiving element 12, and includes a TOF unit 151 that specifies the distance to the detection object by the TOF method, and a triangulation unit 152 that specifies this distance by the triangulation method. Prepare. The control unit 15 may be realized by a logic circuit (hardware) formed in an integrated circuit (IC chip) or the like, or may be realized by software using a CPU (Central Processing Unit). In the latter case, the optical sensor 1 is a CPU that executes instructions of a program that is software that realizes each function, a ROM (Read Only Memory) in which the program and various data are readably recorded by a computer (or CPU) or A storage device (these are referred to as a "recording medium"), a RAM (Random Access Memory) for developing the program, and the like are provided. The object of the present invention is achieved by the computer (or CPU) reading the program from the recording medium and executing the program. As the recording medium, “a non-temporary tangible medium”, for example, a tape, a disk, a card, a semiconductor memory, a programmable logic circuit and the like can be used. The program may be supplied to the computer via any transmission medium (communication network, broadcast wave, etc.) capable of transmitting the program. The present invention can also be realized in the form of a data signal embedded in a carrier wave, in which the program is embodied by electronic transmission.

(Housing)
Usually, the light emitting element 11, the light receiving element 12, the lens 13, and the control unit 15 are assembled as one package. The housing of the light sensor 1 is this package. Furthermore, when the light sensor 1 is installed in a robot cleaner or the like, an outer frame is disposed in the light sensor 1. The housing may be this outer frame. In this case, the closest distance d described above is the distance from the light emitting element 11 to the outer frame. In addition, in the robot cleaner provided with the wheel, the closest contact distance between the traveling surface which is the target for detecting the distance and the light emitting element 11 of the light sensor 1 is defined by the wheel. Thus, the wheel may be part of the housing.

  The housing of the optical sensor 1 is provided with a hole so that the light emitted from the light emitting element 11 is irradiated to the detection object A, and the light reflected to the detection object A is incident to the light receiving element 12 It is done. The hole may be a member that transmits light.

<< Operation of optical sensor 1 and effect of this embodiment >>
(Distance measurement)
As shown in FIG. 1, when the surface of the detection object A is a mirror surface, light emitted from the light emitting element 11 in one direction along the optical axis OA is reflected by the detection object A to the optical axis OA. In the vertical direction, the light emitted from the light emitting element 11 propagates a length equal to the spot diameter D spreading on the surface of the detection object A. Therefore, even if the light sensor 1 and the detection object A are in closest contact with each other, the light reflected by the detection object A can be incident on the light receiving element 12 which is an avalanche photodiode closest to the light emitting element 11. And an avalanche photodiode is suitable for measurement of TOF of light. Therefore, the distance from the light sensor 1 to the detection object A can be measured by the TOF method.

(Surface judgment)
FIG. 2 is a front view showing the configuration of the light sensor 1 shown in FIG. In FIG. 2, the surface of the detection object A is not a mirror surface. In FIG. 2, the housing of the light sensor 1 and the control unit 15 are omitted to simplify the drawing.

  As shown in FIG. 2, when the surface of the detection object A is not a mirror surface, this distance can be measured by triangulation. The position of the light receiving element 12 on which the light reflected by the detection object A is incident differs between when the surface of the detection object A is a mirror surface and when the surface is not a mirror surface. Specifically, as the light sensor 1 includes the lens 13, the diffused light collected by the lens 13 moves closer to the light emitting element 11 as the distance between the detection object A and the light sensor 1 increases. Move. Further, as the distance between the detection object A and the light sensor 1 becomes smaller, this diffused light moves to the side farther from the light emitting element 11.

  Therefore, based on the identification results of the TOF unit 151 and the triangulation unit 152 and the position (light receiving position) of the light receiving element 12 where the light is incident, the control unit 15 determines whether the surface of the detection object A is a mirror surface. It can be determined. In this determination, a complicated configuration in which light is projected and received at different angles is not used. Therefore, the light sensor 1 can easily determine the surface state of the detection object A.

Second Embodiment
A second embodiment of the present invention will be described with reference to FIGS. In addition, about the member which has the same function as the member demonstrated in the above-mentioned embodiment for convenience of explanation, the same code | symbol is written in addition and the description is abbreviate | omitted. The same applies to the embodiments described later.

<< Configuration of optical sensor 1a >>
FIG. 3 is a front view showing the configuration of the light sensor 1a of the present embodiment. In FIG. 3, the surface of the detection object A is a mirror surface. As shown in FIG. 3, the light sensor 1 a includes a light emitting element 11, a plurality of light receiving elements 12, lenses 13 l and 13 r, a control unit 15, and a housing indicated by a broken line.

(Light receiving element)
The light receiving element 12 includes a left light receiving element 12l and a right light receiving element 12r. A part of the light emitted from the light emitting element 11 and reflected to the detection object A is condensed to the left light receiving element 12 l through the lens 13 l. In addition, another part of this light is condensed to the right light receiving element 12r through the lens 13r. The left side light receiving element 12l and the right side light receiving element 12r are avalanche photodiodes arranged in a direction perpendicular to the optical axis OA, and are arranged symmetrically with respect to the optical axis OA.

  The light receiving element 1211 is disposed at a position closest to the light emitting element 11 in the left side light receiving element 12l. The light beam L1 emitted from the light emitting element 11 is incident on the surface of the detection object Aa at an angle to the symmetry axis SAl. The incident light ray is reflected from the surface of the detection object Aa at the same angle as the certain angle with respect to the symmetry axis SAl. Then, the reflected light beam enters the light receiving element 1211 through the lens 13l. The distance between the optical axis OA and the end of the light receiving element 1211 is approximately equal to the spot diameter of the light emitted from the light emitting element 11 spreading on the surface of the detection object Aa. That is, the end on the light emitting element 11 side of the light receiving element 1211 is disposed at a position symmetrical to the light emitting element 11 with respect to the symmetry axis SAl.

  The light receiving element 121 r is disposed at a position closest to the light emitting element 11 in the right side light receiving element 12 r. The light beam Lr emitted from the light emitting element 11 is incident on the surface of the detection object Aa at an angle to the symmetry axis SAr. The incident light ray is reflected from the surface of the detection object Aa at the same angle as the certain angle with respect to the symmetry axis SAr. Then, the reflected light beam enters the light receiving element 121 r through the lens 13 r. The distance between the optical axis OA and the end of the light receiving element 121r is approximately equal to the spot diameter of the light emitted from the light emitting element 11 spreading on the surface of the detection object Aa. That is, the end on the light emitting element 11 side of the light receiving element 121 r is disposed at a position symmetrical to the light emitting element 11 with respect to the symmetry axis SAR.

<< Operation of Optical Sensor 1a and Effect of This Embodiment >>
As shown in FIG. 3, when the surface of the detection object A is a mirror surface, light emitted from the light emitting element 11 in one direction along the optical axis OA is reflected by the detection object A to the optical axis OA. In the vertical direction, the light emitted from the light emitting element 11 propagates a length equal to the spot diameter spreading on the surface of the detection object A. Therefore, even if the light sensor 1a and the detection object A are in closest contact with each other, light reflected by the detection object A can be incident on the light receiving elements 1211 and 121r, which are avalanche photodiodes closest to the light emitting element 11. And an avalanche photodiode is suitable for measurement of TOF of light. Therefore, the distance from the light sensor 1a to the detection object A can be measured by the TOF method. Also, as described above, the control unit 15 can determine whether the surface of the detection object A is a mirror surface. As described above, the light sensor 1a can easily determine the surface state of the detection object A.

  FIG. 4 is a front view showing the configuration of the light sensor 1a shown in FIG. In FIG. 4, the surface of the detection object A is a mirror surface, and the detection object A is inclined with respect to the light sensor 1 a. In FIG. 4, the housing of the light sensor 1 a and the control unit 15 are omitted to simplify the drawing.

  As shown in FIG. 4, when the surface of the detection object A is a mirror surface and the detection object A is inclined with respect to the light sensor 1a, for example, the left light receiving element 12l may not be able to receive light. However, since the left light receiving element 12l and the right light receiving element 12r are disposed symmetrically with respect to the optical axis OA, the right light receiving element 12r can receive this light. As described above, at least one of the left light receiving element 12 l and the right light receiving element 12 r can receive the light emitted from the light emitting element 11 and reflected by the detection object A. Therefore, even if the detection object A is inclined with respect to the light sensor 1a, the light sensor 1a can easily determine the surface state of the detection object A.

Third Embodiment
A third embodiment of the present invention will be described with reference to FIG.

<< Configuration and effect for determining the surface state of a detection object with high precision >>
FIG. 5 is a schematic view showing a configuration for determining the surface state of the detection object A of the present embodiment, wherein (a) shows a configuration in which the surface of the detection object A is a mirror surface, and (b) shows detection The structure where the surface of an object is not a mirror surface is shown. The configuration of FIG. 5 is similarly applicable to the optical sensor 1a.

  As shown in (a) of FIG. 5, when the surface of the detection object A is a mirror surface, the light emitted from the light emitting element 11 and reflected by the detection object A is disposed at a position closest to the light emitting element 11 The light enters the light receiving element 121. The photocurrent distribution Da indicates the position at which the light receiving element 12 receives light and the photocurrent. The photocurrent is distributed only at the position of the light receiving element 121. Since the light emitted from the light emitting element 11 is specularly reflected by the detection object A, the peak value of the photocurrent becomes relatively high.

  On the other hand, as shown in (b) of FIG. 5, when the surface of the detection object A is not a mirror surface, the light emitted from the light emitting element 11 and reflected to the detection object A is closer to the light emitting element 11 than the light receiving element 121. It enters far light receiving elements 122-124. The photocurrent of the photocurrent distribution Db is distributed at the positions of the light receiving elements 122 to 124. The light emitted from the light emitting element 11 is diffused and reflected by the detection object A, so the peak value of the photocurrent becomes relatively small. When the surface of the detection object A is not a mirror surface, light emitted from the light emitting element 11 is diffusely reflected by the detection object A, and is collected and received with reference to the center of the lens 13. Thus, the optical axis center of the diffusely reflected light passes through the center of the lens 13.

  As described above, not only the position (number) of the light receiving elements 12 on which light is incident but also the peak value of the photocurrent differs depending on whether the surface of the detection object A is a mirror surface or not. For this reason, the surface state of the detection object A can be determined with higher accuracy from the number of light receiving elements into which light has entered and the peak value.

Embodiment 4
A fourth embodiment of the present invention will be described with reference to FIG.

<< Configuration for reliably measuring the distance from the optical sensor to the detected object >>
FIG. 6 is a circuit diagram showing a configuration for measuring the distance from the light sensor 1 of the present embodiment to the detection object A. The configuration of FIG. 6 can be applied to the optical sensor 1a as well. As shown in FIG. 6, the photosensor 1 further includes a resistance element R, a transistor T, and a constant current source S for each light receiving element. In FIG. 6, one of the plurality of light receiving elements provided in the light sensor 1 is shown as the light receiving element 12. The transistor T is a metal oxide semiconductor field effect transistor (MOSFET). The present invention is not limited to this configuration, and the transistor T may be any transistor that can be turned on / off at high speed according to the response speed of the light receiving element 12 which is an avalanche photodiode.

  The cathode of the light receiving element 12 is connected to the high voltage line HV. The anode of the light receiving element 12 is connected to one end of the resistive element R. The other end of the resistive element R, the gate terminal of the transistor T, and one end of the constant current source S are connected to the node N. The other end of the constant current source S and the source terminal of the transistor T are grounded to GND or connected to a relatively low voltage wiring. The drain terminal of the transistor T is connected to the control unit 15, and the output signal I flows.

  Thus, by inserting a resistance element in series with the light receiving element 12, an output signal I corresponding to the potential of the node N can be obtained, and quenching for limiting the photocurrent of the light receiving element 12 is possible. Become. The resistance element R can also be configured as a resistance by a transistor.

<< Effect of this embodiment >>
As shown in (a) of FIG. 5, when the surface of the detection object A is a mirror surface, the peak value of the photocurrent obtained from the light receiving element 12 becomes high. At this time, since it takes time to quench the photocurrent, high-speed detection of the distance from the light sensor to the detection object may be difficult. By increasing the resistance value of the resistance element R shown in FIG. 6, stable and high-speed detection can be performed.

  The attenuation of the quenched photocurrent depends on the coefficient exp (-t / RC), where t is the time from the start of detection to quenching, R is the resistance of resistor element R, and C is its parasitic capacitance. Do. As the light receiving element 12 is closer to the light emitting element 11, the photocurrent obtained from the light receiving element 12 is larger, so the time t tends to be longer. Therefore, the resistance value of the resistance element R may be selected so that the above coefficient relating to the attenuation becomes equal to or more than a predetermined value according to the time t.

Fifth Embodiment
A fifth embodiment of the present invention will be described with reference to FIG.

<< Configuration of Robot Vacuum Cleaner >>
FIG. 7 is a view showing the configuration of a robot cleaner 5 (electronic device) of the present embodiment, where (a) is a front view and (b) is a bottom view. In addition, in order to clarify a figure, the floor 6 is abbreviate | omitted in (b) of FIG. Further, the XYZ axes in (a) of FIG. 7 correspond to the XYZ axes in (b) of FIG. 7.

  As shown in (a) of FIG. 7, the robot cleaner 5 includes the light sensor 1 or 1 a, a housing 51, and a tire 52. The light sensor 1 or 1 a is provided in the housing 51. Then, light is emitted from the light emitting element provided in the optical sensor 1 or 1a to the floor surface 6 along the optical axis OA. As shown in (b) of FIG. 7, a suction unit 53 is provided in the housing 51 of the robot cleaner 5. The suction unit 53 is provided with a roller (not shown) that sucks in dust from the floor surface 6.

<< Operation and effect of robot vacuum cleaner >>
The robot cleaner 5 transmits the rotation of the tire 52 to the floor surface 6 and travels in the positive Y-axis direction. The robot cleaner 5 may have a mechanism for keeping the bottom surface and the floor surface 6 substantially parallel. As shown in (b) of FIG. 7, the light sensor 1 or 1 a is disposed on the bottom of the robot cleaner 5 on the front side in the traveling direction of the robot cleaner 5 with respect to the suction unit 53. The robot cleaner 5 can change the suction force by detecting the state of the floor 6 to be cleaned, and thus can contribute to the improvement of the dust collection capability and energy saving. As described above, the electronic device provided with the light sensor 1 or 1a is also included in the present invention.

[Summary]
The optical sensor 1 / 1a according to aspect 1 of the present invention is an optical sensor that measures the distance to a detection object using light reflected by the detection object A, and is a light emitting element 11 that emits light in one direction; A plurality of avalanche photodiodes (light receiving element 12, left side light receiving element 12l, right side light receiving element 12r) disposed in a direction perpendicular to the one direction of the light emitting element, and a casing separating the detection object and the light emitting element A control unit 15 connected to the light emitting element and the plurality of avalanche photodiodes and specifying the distance by the TOF method and the triangulation method; the light emitting element and the avalanche photodiode closest to the light emitting element The distance r between the light emitting element and the light emitting element is a spot diameter D in which the light emitted from the light emitting element spreads on the surface of the detection object when the Properly, the control unit and the distance specified, by comparing the light receiving position of the avalanche photodiode, for detecting the surface state of the detection object.

  According to the above configuration, when the surface of the detection object is a mirror surface, the light emitted in one direction from the light emitting element is reflected by the detection object, whereby the light emitted from the light emitting element in the direction perpendicular to the one direction Propagates a length equal to the spot diameter spreading on the surface of the sensing object. Therefore, even when the light sensor and the detection object are in closest contact with each other, that is, even when the detection object is in contact with the housing, light reflected by the detection object can be incident on the avalanche photodiode closest to the light emitting element.

  Furthermore, when the surface of the detection object is a mirror surface, the distance from the light sensor to the detection object can be measured by the TOF method. If the surface of the object to be detected is not specular, this distance can be measured by triangulation. And, when the surface of the detection object is a mirror surface and when the surface is not a mirror surface, the avalanche photodiodes to which the light reflected by the detection object is incident are different. Therefore, based on the distance specified by the TOF method / triangulation method and the position of the avalanche photodiode on which the light is incident, the control unit can determine whether the surface of the detection object is a mirror surface. This determination does not require a complicated configuration in which light is projected and received at different angles.

  As described above, in the optical sensor that measures the distance to the detection object using the light reflected by the detection object, the surface state of the detection object can be easily determined.

  In the optical sensor according to aspect 2 of the present invention, in the above aspect 1, the avalanche photodiode may operate in Geiger mode.

  The detection signal obtained by converting the light into an electrical signal by the avalanche photodiode has a smaller amplitude as the frequency is higher. At this time, detection of the detection signal becomes difficult. Then, the closer the detection object and the light sensor, the higher the detection signal.

  According to the above configuration, the amplitude of the detection signal can be increased by operating the avalanche photodiode in the Geiger mode. Therefore, the light sensor can calculate the distance to the closer detected object.

  In the optical sensor according to aspect 3 of the present invention, the surface of the detection object according to aspect 1 or 2 from the number of avalanche photodiodes that have received light and the peak value of the photocurrent output from the avalanche photodiode. The state may be detected.

  According to the above configuration, not only the position (number) of avalanche photodiodes on which light is incident but also the peak value of the photocurrent differs depending on whether the surface of the detection object is a mirror surface or not. For this reason, the surface state of the detection object can be determined with higher accuracy from the number of avalanche photodiodes on which light has entered and the peak value.

  The optical sensor according to aspect 4 of the present invention further comprises a resistance element R connected in series to each of the plurality of avalanche photodiodes in any one of the aspects 1 to 3, and the resistance value of the resistance element The distance between the light emitting element and the avalanche photodiode connected to the resistance element may be higher.

  When the surface of the detection object is a mirror surface, the peak value of the photocurrent obtained from the avalanche photodiode becomes high. At this time, since it takes time to quench the photocurrent, high-speed detection of the distance from the light sensor to the detection object may be difficult.

  According to the above configuration, as the avalanche photodiode is closer to the light emitting element, the photocurrent obtained from the avalanche photodiode is larger, so the time from the detection start to the quenching tends to be longer. By increasing the resistance value of the resistance element according to this tendency, stable and high-speed detection can be performed.

  An electronic device according to aspect 5 of the present invention includes the optical sensor according to any one of the aspects 1 to 4.

(Other modes)
In the optical sensor according to another aspect of the present invention, in any one of the aspects 1 to 4, the avalanche photodiodes may be arranged symmetrically with respect to the light emitting element.

  If the surface of the detection object is a mirror surface and the detection object is tilted with respect to the light sensor, the avalanche photodiode may not be able to receive light.

  According to the above configuration, at least one of the plurality of symmetrically arranged avalanche photodiodes can receive the light emitted from the light emitting element and reflected by the detection object. Therefore, even if the detected object is tilted with respect to the light sensor, the light sensor can easily determine the surface state of the detected object.

[Items to be added]
The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and embodiments obtained by appropriately combining the technical means disclosed in the different embodiments. Is also included in the technical scope of the present invention. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment.

  The present invention can be used to detect the floor condition of a robot cleaner.

1 ・ 1a Optical Sensor 5 Robot Cleaner (Electronic Equipment)
11 light emitting element 12 light receiving element (avalanche photodiode)
12 l Left light receiving element (avalanche photodiode)
12r Right light receiving element (avalanche photodiode)
13 · 13 l · 13r Lens 15 control unit 151 TOF unit 152 triangulation unit A detection object D spot diameter R resistance element T transistor d closest distance r distance

Claims (5)

An optical sensor that measures the distance to a detection object using light reflected by the detection object,
A light emitting element that emits light in one direction;
A plurality of avalanche photodiodes disposed in a direction perpendicular to the one direction of the light emitting element;
A housing separating the detection object and the light emitting element;
A control unit connected to the light emitting element and the plurality of avalanche photodiodes and specifying the distance by the TOF method and the triangulation method;
Equipped with
The distance between the light emitting element and the avalanche photodiode closest to the light emitting element is such that light emitted from the light emitting element spreads on the surface of the detection object when the detection object contacts the casing. Equal to the spot diameter,
The control unit detects the surface state of the detection object by comparing the specified distance with the light receiving position of the avalanche photodiode.
An optical sensor characterized by   The light sensor according to claim 1, wherein the avalanche photodiode operates in Geiger mode.   The light according to claim 1 or 2, wherein the surface state of the detection object is detected from the number of avalanche photodiodes that have received light and the peak value of the photocurrent output from the avalanche photodiode. Sensor. And a resistive element connected in series to each of the plurality of avalanche photodiodes,
The resistance value of the said resistive element is so high that it is so high that the distance between the said avalanche photodiode connected to the said resistive element and the said light emitting element is near, It is described in any one of Claim 1 to 3 characterized by the above-mentioned. Light sensor.   An electronic device comprising the light sensor according to any one of claims 1 to 4.

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