DEVICE AND METHOD FOR DETECTING AN OBJECT

Abstract

DEVICE AND METHOD FOR DETECTING AN OBJECT The invention relates to a method for detecting an object comprising the following steps: the generation of a control signal (31) to produce the emission of a light signal (111) by a phototransmitter (110); characterized in that said generated light signal (111) is a periodic signal at a predetermined frequency; detection by a photodetector (2) of a light comprising at least one reflected signal (112), said reflected signal comprising a part of the light signal (111) emitted by the photoemitter (110) which is reflected on an object (103) and arrives at the photodetector (2) and the production of a detection signal (41); filtering said detection signal (41) to generate a filtered signal (46); measuring the amplitude of the filtered signal (46) to generate an amplitude indicator (51) of said filtered signal (46); detecting the presence of an object (103) from said amplitude indicator (51).Figure for the abridged version: Fig.3.

Description

Title of the invention: DEVICE AND METHOD FOR DETECTING AN OBJECT Field of invention

[0001] The invention relates to a method and an associated electronic device for detecting an object, in particular an object in the near field in front of a detection surface. State of the art

[0002] Today there are devices for detecting an object or several objects based on the use of optics.

[0003] For example, document FR3103341 describes the use of a device such as a camera or a depth camera to detect a user's hand or the recognition of a hand gesture.

[0004] A disadvantage of this type of device is that the detection cone or field of view of such a camera is narrow and defined by its optical lens. Therefore, this type of device is not suitable for detecting an object in the near field, i.e. at almost zero height relative to the detection device.

[0005] To solve this drawback, document EP2843509 describes a device comprising a peripheral border of a screen making it possible to estimate the coordinates of an object above the screen. This device emits infrared light onto the object and detects the light reflected by said object to detect its presence.

[0006] However, a disadvantage of this device is that the light detected by the photodetector is a sum of the reflected light from the photoemitter and a surrounding light emitted by a stray light source. In most cases of use, and as illustrated in [Fig.l], the portion of the detected light due to the reflected light R by the object is negligible or very small compared to the portion due to the surrounding light L. It is possible to measure the difference in light detected by the photodetector when the photoemitter is switched off and then on. However, since the variation can be very small, the calculated value is not sufficiently precise to obtain satisfactory results.

[0007] There is a need for a method and device for detecting an object in the near field capable of obtaining a sufficiently precise estimate even in the presence of ambient light or stray light sources. Summary of the invention

[0008] According to a first aspect, the invention relates to a method for detecting an object, in particular an object located in the detection field of an electronic device.

[0009] Said method comprises a step of generating a control signal to produce the emission of a light signal by a photoemitter. Said generated light signal is a periodic signal at a predetermined frequency.

[0010] Said method comprises detecting by a photodetector a light comprising at least one reflected signal, said reflected signal comprising a portion of the light signal emitted by the photoemitter which reflects on an object and arrives at the photodetector and producing a detection signal.

[0011] Said method comprises a step of filtering said detection signal so as to retain, from the detection signal produced, only the frequencies included in a predetermined frequency interval to generate a filtered signal; said predetermined frequency being included in said predetermined frequency interval.

[0012] Said method comprises measuring the amplitude of the filtered signal to generate an amplitude indicator of said filtered signal.

[0013] According to one embodiment, the method comprises a step of detecting the presence of an object from said amplitude indicator.

[0014] According to one embodiment, the light detected by the photodetector further comprises surrounding light.

[0015] According to one embodiment, the intensity of said surrounding light captured by the detector is significantly greater than the intensity of the reflected signal captured by the detector.

[0016] According to one embodiment, the measuring step further comprises a sub-step of converting the filtered signal into a constant converted signal.

[0017] According to one embodiment, the converted signal is generated so as to be constant at least for the duration of the measurement of the amplitude of the signal.

[0018] According to one embodiment, the conversion of the filtered signal into a constant signal is carried out synchronously with the control signal.

[0019] According to one embodiment, the conversion of the filtered signal into a constant signal is carried out by a sample-and-hold circuit.

[0020] According to one embodiment, the detection of the presence of an object comprises the comparison of the amplitude indicator with a predefined threshold value.

[0021] According to one embodiment, the step of detecting the presence of an object comprises calculating a distance and / or position data item for said object from at least one amplitude indicator.

[0022] According to one embodiment, the calculation of a distance data item is carried out by comparing the amplitude indicator with one or more predetermined threshold values. In one embodiment, the calculation of the distance data item is calculated from a predetermined mathematical function such as a calibration function.

[0023] According to a second aspect, the invention relates to an electronic device for detecting an object.

[0024] In one embodiment, the device comprises software and / or hardware means for implementing the method according to the invention.

[0025] In one embodiment, the device comprises a controller adapted to produce a control signal, having a predetermined periodic frequency, and intended to be used to drive a photoemitter in order to cause the photoemitter to emit a periodic light signal having a predetermined periodic frequency.

[0026] In one embodiment, the device comprises a photodetector configured to produce a light detection signal comprising at least one reflected signal, said reflected signal comprising a portion of the light emitted by the photoemitter which reflects off an object and arrives at the photodetector.

[0027] In one embodiment, the device comprises a signal processing unit adapted to filter said detection signal so as to retain, from the detection signal, only the frequencies included in a predetermined frequency interval to generate a filtered signal; said predetermined frequency being included in said predetermined frequency interval.

[0028] In one embodiment, the device comprises a unit for measuring the amplitude of the filtered signal to generate an amplitude indicator of said filtered signal.

[0029] In one embodiment, the device comprises a calculation unit configured to detect from said amplitude indicator the presence of an object.

[0030] In one embodiment, the signal processing unit comprises a high-pass filter for performing the signal filtering step, said high-pass filter being designed so that the frequency interval between its cut-off frequencies comprises the predetermined frequency of said light signal emitted by the photoemitter.

[0031] In one embodiment, the device further comprises at least one photoemitter configured to emit a signal based on the control signal emitted by the controller. Brief description of the figures

[0032] Other characteristics and advantages of the invention will emerge on reading the detailed description which follows, with reference to the appended figures, which illustrate:

[0033] [Fig-1]: a graphical representation of the intensity of the signal detected by a photo detector according to the methods of the prior art.

[0034] [Fig.2]: a graphical representation of the intensity of the signal detected by a photodetector according to an embodiment of the invention.

[0035] [Fig.3]: a schematic representation of an electronic device according to an embodiment of the invention.

[0036] [Fig.4]: a schematic representation of a signal measurement unit according to one embodiment of the invention.

[0037] [Fig.5]: a schematic representation of a computing unit according to an embodiment of the invention.

[0038] [Fig.6]: a flowchart representing a mode of execution of the method according to the invention.

[0039] [Fig.7]: a simplified representation of the values ​​of the different signals during the detection of an object according to a mode of execution of the method according to the invention.

[0040] [Fig.8]: a simplified representation of an electronic assembly according to an embodiment of the electronic device according to the invention in which the measurement unit comprises a sample-and-hold component.

[0041] [Fig.9]: a schematic representation of the device according to an embodiment in which a plurality of photodetectors are connected in parallel and each photodetector is connected to a different circuit in parallel comprising a processing unit and a measuring unit.

[0042] [Fig. 10]: a schematic representation of the device according to an embodiment in which a plurality of photodetectors are each connected to a processing unit in parallel.

[0043] [Fig. 11]: a schematic representation of the device according to an embodiment in which a plurality of photodetectors are connected to a single group composed of a single processing unit, a single measuring unit and a single computing unit. Definitions

[0044] By “photodetector” is meant any type of structural means making it possible to detect a light intensity and to generate a signal as a function of said detected intensity.

[0045] By "photoemitter" is meant any type of means capable of emitting light radiation when activated, for example by application of a current or voltage.

[0046] By “significantly higher” is meant at least 2 times higher, at least 10 times higher or preferably at least 100 times higher.

[0047] By "computation unit" is preferably meant any type of software and / or hardware means allowing the execution of a method or a process comprising an electronic circuit comprising at least one processor or calculator coupled to at least one data medium, preferably non-transitory, such as a memory, and on which is encoded an algorithm or a series of instructions executable by the processor to execute said method by the processor.

[0048] By “substantially” followed by a numerical value means said numerical value + / - 5% or 10%.

[0049] By "an object located in the detection field" is meant an object located in front of a detection surface illuminated by the photoemitters when the latter are switched on so that the reflected rays reach at least one photodetector. It can also simply be understood as an object in the light beam generated by the photoemitters of the detection surface when the latter are switched on or activated.

[0050] By "luminous" we mean any signal in the visible range, in the infrared (near or far) or in the ultraviolet range.

[0051] By "constant signal" is meant that the signal is constant for the duration of the measurement of its amplitude, for example over the duration of an analog / digital conversion. The duration of the measurement can be between 20 periods of the control signal to a fraction of a period such as 1 / 10 of a period or 1 / 20 of a period. The signal is considered constant when its amplitude varies, during the duration of the measurement, by less than 25%, preferably by less than 1%. Detailed description of the invention

[0052] An example device is described below with reference to the figures. Detection surface

[0053] According to a first aspect, the invention relates to an electronic device.

[0054] The electronic device comprises at least one photodetector 2.

[0055] The electronic device may comprise or be coupled to at least one photoemitter 110. Preferably, the photoemitters 110 are designed to emit photons by electroluminescence effect. The photoemitters may also comprise fluorescent tubes or incandescent light producing means such as an incandescent lamp. The photoemitters 110 are preferably designed to emit light rays in a predefined wavelength range. The photoemitters may comprise light-emitting diodes, laser emitting devices.

[0056] The photodetectors 2 are designed to detect a light ray. Preferably, the at least one photodetector 2 is designed to detect a light ray emitted by the plurality of photoemitters 110. The photodetectors 2 are designed to transform the light absorbed in a range of wavelengths into a measurable quantity such as an electric current or an electric voltage.

[0057] The photodetectors 2 and the photoemitters 110 are arranged so that a light ray emitted by a photoemitter and reflected by an object 103 arrives directly at the photodetector 2 without being reflected by another object. Preferably, the photodetectors 2 and the photoemitters 110 are arranged on the same side of a surface of the electronic device 1.

[0058] An object is considered in the detection field of the device when the rays 111 emitted by the photoemitter 110 directly reach (i.e. without reflection) said object 103 and the rays 112, coming from the photoemitter 110, and reflected by the object directly reach the photodetector.

[0059] The photoemitters 110 are designed to emit photons by electroluminescence effect. The photoemitters 110 are preferably designed to emit light rays in a predefined wavelength range.

[0060] Preferably, the photoemitters 110 are designed to emit infrared light radiation.

[0061] The photodetectors 2 are designed to detect a light ray emitted by the plurality of photoemitters 110. The photodetectors 2 are designed to transform the absorbed light in a range of wavelengths into a measurable quantity such as an electric current or an electric voltage. The photodetectors are designed to produce an electrical light detection signal whose intensity or power is a function of the detected light intensity.

[0062] The photodetectors 2 comprise, for example, fiber optic sensors, photodiodes or light-emitting diodes. Preferably, the photodetectors 2 are infrared light photodetectors such as infrared photodiodes.

[0063] Preferably, the photoemitters are designed so that their emitted light diffusion cone is as small as possible. In one embodiment, the photodetectors are designed so as to have the smallest possible detection cone.

[0064] The angle formed by the diffusion cone of one or more photoemitters may be different from the angle of the detection cone of one or more photodetectors.

[0065] Preferably, the photodetectors and the photoemitters are regularly distributed along the two directions of space (x,y) of the detection surface, or along a single direction of space.

[0066] Each photodetector is preferably arranged between at least two photoemitters in the two directions of space. In one example, the photodetectors and the photoemitters are regularly distributed along two orthogonal directions of the plane of the detection surface.

[0067] In one embodiment, a transparent plate or layer arranged to cover the plurality of photoemitters 110 and photodetectors 2 may be integrated. By “transparent” is meant transparent to the light rays emitted by the photoemitters. Such a plate advantageously makes it possible to protect the physical integrity of the components of the detection surface while allowing outgoing and incoming light rays to pass through. In one example, the covering layer is transparent to infrared rays. In one example, the covering layer is transparent to light rays emitted by the photoemitters 110 and to rays in the visible range such as a quartz plate. Controller

[0068] The remainder of the description describes an embodiment of the invention comprising a single photoemitter and a single photodetector, but also applies to the embodiment comprising a plurality of photodetectors and / or a plurality of photoemitters.

[0069] The electronic device 1 according to the invention comprises a controller 3. The controller 3 is designed to allow the control of the photoemitter 110. In one embodiment, the controller 3 is designed to independently control each photoemitter 110. Each photoemitter 110 can therefore be activated (to emit light radiation) or switched off independently of the activation of the other photoemitters 110.

[0070] The controller 2 can also control the intensity emitted by the or each photoemitter so as to vary the light intensity emitted by the photoemitter 110.

[0071] The controller 3 may comprise an electronic circuit connected to a power source. The controller 3 may comprise an electronic circuit capable of producing a control signal 31.

[0072] The controller 3 produces a control signal 31 to the photoemitter to produce the emission of a light signal 111 by the photoemitter in response to said control signal 31.

[0073] The control signal is generated so that the emitted light signal 111 is a signal whose intensity is periodic. Generally, the emitted light signal 111 follows a pattern (also called “phase”) comprising a variation in the value of the intensity over time in a periodic manner. For example, the control signal 31 is generated in such a way that the emitted light signal is a sinusoidal or square-wave signal, successively taking a first value then a second value greater than the first value. The first value is preferably a zero value. In other words, the photoemitter is controlled by the control signal to successively switch from the off state to the on state in a periodic manner.

[0074] By “periodically” is meant that the control signal and / or the emitted light signal 111 follows a unique pattern (also called “phase”) repeatedly at a predetermined frequency.

[0075] The control signal 31 may be, for example, a 500 kHz square wave signal, but it is not limited to this. This control signal 31 is used to control the photoemitter 110, in response to which said photoemitter 110 emits light, for example example infrared (emitted light signal). The modulation frequency of the emitted infrared light, which can also be called the carrier frequency, depends on the frequency of the control signal 110. In other words, when the photoemitter 110 is driven by a control signal 31 of 500 kHz, the carrier frequency of the emitted infrared light signal 111 can be 500 kHz or a multiple (or a fraction) of this frequency, for example 250 kHz or 1000 kHz.

[0076] The control signal may be generated as a function of a synchronization signal 33 produced by a synchronization generator 120. The synchronization signal 33 may be generated so as to control the start of a phase of the control signal 31. In another embodiment, the controller comprises an internal clock capable of detecting and / or time-stamping the start of a phase of the control signal 31.

[0077] In this respect, the synchronization generator 120 or the controller 3 may comprise a clock. The synchronization generator may generate a first synchronization signal 33 for controlling the control signal 31 generated by the controller 3 and a second synchronization signal 32 transmitted to the measurement unit described below to allow rectification of the signal synchronously with the control signal and / or the detection signal 4L Detection signal processing unit

[0078] The device further comprises a processing unit 4 for the detection signal 41 produced by the photodetector 2.

[0079] The processing unit is designed to receive, as input, an electrical signal generated by the photodetector and to generate, as output, a filtered signal 46 so as to retain from the input signal only the modulation frequencies of said input signal included in a predetermined frequency interval.

[0080] The advantage of this processing unit is to retain, from the detection signal, only the components of the signal whose frequency is included in the predetermined frequency interval.

[0081] In a preferred embodiment illustrated in [Fig.8], the processing unit 4 comprises an electronic circuit comprising a bandpass filter and / or a bandpass filter and a transimpedance amplifier. Optionally, the processing unit 4 further comprises an electronic circuit further comprising an amplifier 411 for amplifying the signal from the bandpass filter such as an operational amplifier or a bandpass voltage amplifier with operational amplifier. An advantage is to increase the amplitude of the filtered signal 46 to improve the quality of the final measurement.

[0082] In the remainder of the description, the term “filtered signal” will be used to designate both the filtered signal 46 coming directly from the band-pass filter and the filtered signal 461 coming from an amplifier or another filter using said filtered signal 46 coming from the band-pass filter. band. Unit of measurement

[0083] The device further comprises a unit 5 for measuring the amplitude of the filtered signal 46, one embodiment of which is illustrated in [Fig.4].

[0084] The measuring unit is designed to receive as input the filtered signal 46 from the processing unit 4 and to generate a value 51 which is a function of the amplitude of said filtered signal 46.

[0085] The measured amplitude of the filtered signal advantageously makes it possible to go back to the component R corresponding to the reflected signal 112.

[0086] Preferably, the measurement unit comprises at least one signal converter 52 designed to receive as input the filtered signal 46 comprising a periodic component and to generate in response a constant converted signal. An advantage is to measure the amplitude of a constant converted signal 54 rather than a variable signal.

[0087] By “constant” signal, we mean that the signal is constant or substantially constant at least for the duration of the amplitude measurement.

[0088] Several solutions make it possible to convert said filtered signal 46 into a constant converted signal 54. For example, the converter 52 may comprise an electrical circuit.

[0089] In a first example not shown, the converter 52 comprises a rectifier circuit. The rectifier circuit may comprise at least one diode which only allows the positive phase of the signal to pass. Optionally, the converter further comprises a low-pass filter for the signal generated by the rectifier circuit to obtain a signal whose value is proportional to the amplitude of the filtered signal 46. Any other voltage rectifier assembly may be used here to improve the performance of the converter. The converter may thus comprise an electronic circuit designed for the successive application to the filtered signal 46 of a square function then a square root function such as a transistor and diode assembly and / or operational amplifiers.Those skilled in the art will be able to identify that the rectification assemblies that can be applied here are numerous and include in particular precision rectification circuits comprising an operational amplifier assembly, or a rectification circuit taking into account an offset when the filtered signal 46 is not centered on 0.

[0090] In an alternative or cumulative embodiment, the converter 52 is a synchronous converter. By “synchronous” is meant that the converter is designed to receive as input a synchronization signal 32 from the synchronization generator and / or from the controller 3. The synchronization signal is generated as a function of the start date of the phase of the control signal 31. The converter thus synchronizes with the control signal 31 generated to convert the filtered signal 46 into a constant converted signal 54.

[0091] An advantage of converting the filtered signal 46 into a constant converted signal 54 in a synchronized manner with the control signal 51 is to allow filtering of parasitic signals from the surrounding light 113 which would have a frequency equal to or close to the frequency of the control signal 51 (i.e. a frequency included in the predetermined frequency interval of the filter of the processing unit 4).

[0092] In a second example not shown, the converter 52 comprises a rectification circuit as described above taking into account said synchronization signal. For example, the rectifier circuit comprises a module for centering the detection signal 46 on 0 and a switch configured to divert the signal to a first branch or a second branch depending on the synchronization signal. Preferably, one of the two branches, intended to receive the detection signal 46 when the latter is negative, comprises a module for inverting the sign of said signal (i.e. converting the negative signal into a positive signal). The two branches subsequently join towards the signal measurement means. Preferably, a low-pass filter is used between the connection point between the two branches and the measurement means to obtain a constant signal whose value corresponds to the average of the amplitude of the detection signal 46.

[0093] In a third example shown in [Fig.8], the converter 52 comprises an electronic sample-and-hold assembly 521.

[0094] The sample-and-hold electronic circuit 521 is designed to receive the filtered signal 46 as input. The electronic circuit comprises a switch 522 capable of closing or opening the circuit. The closing and opening of the switch are controlled by the synchronization signal 32.

[0095] Preferably, the synchronization signal is generated so as to cause the circuit to close over a time interval corresponding to the moment when the phase of the filtered signal 46 reaches a maximum and / or a minimum.

[0096] In one embodiment, the synchronization signal is synchronized with the control signal 31 emitted by the controller to drive the photoemitter 110.

[0097] When the circuit is closed, a capacitor 523 charges with each successive closing of the switch, until the capacitor is fully charged and generates a constant converted signal 54 representative of the amplitude of the filtered signal 46.

[0098] Preferably, in this embodiment, the circuit comprises means for centering the filtered signal 46 on 0 before arriving at the converter.

[0099] This example is described below in more detail with reference to [Fig.7] representing as a function of time the detection signal 41 from the photodetector 2, the filtered signal 46, the synchronization signal 32 and the converted signal 54.

[0100] In a first step A, an object is placed in the detection field of the device.

[0101] The photodetector emits a detection signal 41 whose intensity comprises a first component L corresponding to the ambient light emitted by a parasitic source and a second component R corresponding to the light emitted by the photoemitter and reflected by the object. The second component is an intensity varying periodically at a predefined frequency.

[0102] The detection signal 41 is filtered by the processing unit 4 so as to generate a filtered signal 46. The processing unit 4 is designed to retain from the detection signal 41 only the frequencies in a frequency interval including the frequency of the second component R.

[0103] In the described mode, the filtering causes an inversion of the voltage and the centering on 0 of the filtered signal 46.

[0104] The processing unit 4 further comprises a signal amplification module 411 for generating an amplified signal 461 from the filtered signal 46.

[0105] The synchronization signal 32 then controls the closing of the electronic sample-and-hold circuit 521. For example, the synchronization signal 32 controls the closing on 1 / 20 of the carrier frequency and is phase-shifted relative to the control signal 31 so as to cause the circuit to close when the amplified signal 461 is at the peak of its phase. Indeed, the various components such as the filters generate a phase shift of the filtered signal relative to the detection signal 41 which is characteristic of the component used for filtering and can thus be anticipated.

[0106] In one embodiment, the synchronization signal is generated as a function of the control signal 31 and a pre-recorded offset data.

[0107] When closing, the capacitor 523 charges closing after closing until it is fully charged. Once fully charged, the capacitor generates a constant converted signal 54 whose power or amplitude can be measured and transferred to the computing unit 6.

[0108] In a second step B, the object is removed from the detection field of the device. The second component R of the detection signal becomes zero as well as the filtered signal 46. The capacitor 523 then discharges until a zero signal is generated. The measurable value is then also zero.

[0109] In a fourth example not shown, the converter 52 comprises a circuit comprising a signal multiplier.

[0110] Said signal multiplier comprises two inputs and one output.

[0111] The circuit is designed so that the signal multiplier receives by its first input the filtered signal 46 and by its second input a synchronization signal. The multiplier is designed to generate a signal whose voltage or intensity is a multiplication of respectively the voltage or intensity of the filtered signal 46 arriving by the first input and the synchronization signal arriving by the second input.

[0112] In this example, the synchronization signal 32 may comprise a sinusoidal signal generated as a function of the control signal. The synchronization signal is generated so as to be positive when the filtered signal 46 is on a positive phase portion and negative when the filtered signal 46 is on a negative phase portion. Preferably, the synchronization signal is phase-shifted relative to the control signal in the same manner as that described for the third example. The generated signal is therefore a rectified positive signal.

[0113] Optionally, the converter further comprises a low-pass filter of the signal generated by the multiplier to obtain a signal whose value is proportional to the amplitude of the filtered signal 46.

[0114] In one embodiment, the measuring unit 5 also comprises a means for measuring the amplitude of the intensity and / or the voltage of said converted signal 54. Said measuring means preferably comprises a voltmeter, an oscilloscope or any other means known to those skilled in the art for measuring a voltage in an electronic circuit. Said measuring means may comprise an integrator and / or an analog / digital converter 53. Said measuring means generates, from said converted signal, data representative of the amplitude of the filtered signal 46. Said data may be directly equal to the amplitude of the filtered signal 46 or be proportional to said amplitude, or follow a predetermined equation in which the data generated is a function of the amplitude of the filtered signal 46. Said data is hereinafter called “amplitude indicator”.

[0115] In another example not shown, the measurement unit comprises an analog / digital converter designed to convert the analog filtered signal 46 into digital data and designed to convert said digital data of the filtered signal 46 into an amplitude indicator of said filtered signal 46. In this example, said measurement unit comprises a processor or computer coupled to at least one data medium, preferably non-transitory, such as a memory, and on which is encoded an algorithm or a series of instructions executable by the processor to execute said conversion of the digital data into an amplitude indicator by the processor. The measurement unit is then designed so that the processor receives said digital data.In one embodiment, said measurement unit comprises an integrated circuit such as a programmable logic circuit or a field-programmable gate array (also known as "FPGA") or a specialized integrated circuit such as an application-specific integrated circuit (also known as "ASIC") for generating and / or storing said digital data. Calculation unit

[0116] In one embodiment, the electronic device 1 further comprises a computing unit 6, one embodiment of which is illustrated in [Fig.5]. The computing unit is configured to receive at least one amplitude indicator 51 generated by the measuring unit 5.

[0117] Preferably, the calculation unit 6 is configured to detect, from at least one amplitude indicator 51 received, the presence of an object 103. For example, when the amplitude indicator 51 is greater than a predetermined threshold value, the calculation unit 6 considers that an object is present in the detection field.

[0118] Preferably, the calculation unit is configured to generate, from at least one amplitude indicator 51 received, a distance and / or position data item for the object 103, relative to a reference frame. The reference frame may be a point of said electronic device fixed relative to the at least one photodetector.

[0119] Many variants are known to those skilled in the art for determining the presence, distance and / or position of an object relative to a device from the amplitude of the signal detected by a photodetector. For example, documents WO2023 / 175162 or EP2843509 describe means for measuring a distance between an object and a detection device. In another example, the distance of an object with the device may be proportional to the drop in light amplitude detected or follow another rule resulting from a prior calibration.

[0120] The position of an object may comprise the coordinates in at least two, preferably 3, directions of space relative to a fixed reference frame of the electronic device, for example relative to a predetermined point of the detection surface. In one embodiment, the position data further comprises information on the shape and / or dimensions of the object in question. For example, the position data comprises a point cloud or a depth map of the object detected in the detection field of the electronic device. In one embodiment, the position data may further comprise information on the pose of the object such as the position of the fingers of a hand.

[0121] In an embodiment illustrated in [Fig.5], the calculation unit comprises a processor or a group of processors configured to receive the amplitude indicators generated by one or more photodetectors and connected to one or more memories on which is stored an algorithm or a series of instructions allowing the processor or the group of processors to implement the generation of the presence detection, the distance and / or position data. Parallel systems

[0122] In an embodiment described above, the electronic device comprises a single photodetector.

[0123] In another embodiment shown in [Fig.9] or [Fig.10], the device comprises at least two photodetectors or a plurality of photodetectors for detecting a brightness comprising at least in part a component corresponding to the light intensity emitted by the photoemitter and reflected by the object.

[0124] In an embodiment illustrated in [Fig.9], the device comprises a plurality of parallel circuits where each photodetector is connected in parallel to a circuit comprising the processing unit and the measuring unit. In this mode, the calculation unit 6 is connected to each circuit to receive the amplitude indicator 51 from each photodetector.

[0125] In an alternative embodiment illustrated in [Fig. 10], the electronic device comprises a plurality of photodetectors, each connected to a different processing unit in parallel and each processing unit is connected to a single measuring unit 5. Preferably, the measuring unit makes it possible to generate an amplitude indicator associated with each photodetector, for example by multiplexing. An advantage is to reduce the number of components of the electronic device.

[0126] In another preferred embodiment illustrated in [Fig.l 1], the electronic device comprises a plurality of photodetectors 2. The photodetectors are connected to a single processing unit 4, itself connected to a measurement unit 5. The processing unit 4 is thus configured to process the detection signal from each photodetector.

[0127] Preferably, the device comprises a multiplexer 401 comprising a plurality of inputs and an output connected to the processing unit. Each photodetector 2 is connected to a different input of the multiplexer 401. The multiplexer makes it possible to pass the detection signal 41 of a photodetector 2 to the processing unit 4 one by one or one after the other. An advantage is to be able, with a single assembly comprising a processing unit 4, a measurement unit 5 and a calculation unit, to take into account all of the photodetectors. In an alternative embodiment not shown, each photodetector 2 is designed to receive an activation signal. The activation signal of each photodetector is generated by a controller so as to activate each photodetector one after the other. Each detector 2 is designed to generate a detection signal 41 only upon receipt of the activation signal.By activating the photodetectors 2 one after the other, the processing unit 4 receives the signal from a single photodetector one after the other.

[0128] In another alternative or cumulative embodiment, the device 1 comprises a plurality of photoemitters 110 which can be activated by the control signal 31 in a dependent or independent manner. Object detection method.

[0129] The method according to one embodiment is now described with reference in particular to [Fig.6] and [Fig.3].

[0130] The method comprises a COM generation of the control signal 31 by the controller. The control signal is generated so that the photoemitter emits a light signal 111 periodically. For example, the emitted light signal is a square wave signal changing from the "off" state to the "on" state at a predetermined frequency. In another embodiment, the emitted light signal may be a sinusoidal signal and / or a signal varying between two non-zero intensities periodically at a predetermined frequency.

[0131] The light signal 111 emitted by the photoemitter 110 is reflected by an object 103 located in the detection field of the electronic device 1 and reaches the photodetector 2. In this case, light rays 113 from the environment, emitted for example by a parasitic source 104, also reach the photodetector. The parasitic light source 104 may be an ambient light source such as sunlight, a screen, or any other light source that one does not wish to measure and which would be detected by the photodetector. The invention is particularly advantageous when the intensity of the light rays 113 from the environment is significantly greater than the intensity of the reflected light rays 111 112.

[0132] The photodetector 2 detects DET a light intensity corresponding to the light rays 111 and 113 and produces in response a detection signal 4L

[0133] The detection signal is at least FIL filtered so as to retain the signal whose frequency is the predetermined frequency of the light emitted by the photoemitter 110.

[0134] The advantage is to recover a filtered signal 46 comprising the component from the photoemitter reflected by the object without the component emitted by the parasitic source 104.

[0135] Once the filtered signal has been generated, the method comprises the MES measurement of the amplitude of said filtered signal 46. It should be noted that the term “filtered signal” is used for any signal originating from the filtered signal 46, but which could have, after filtering, been amplified, refiltered, refocused, inverted, phase-shifted or undergo other signal processing. For example, the filtered signal may be centered around a non-zero value greater than its amplitude, for example IV. This advantageously ensures that the signal voltage is systematically positive. The MES measurement makes it possible to generate an amplitude indicator 51. The amplitude indicator is preferably a function of the amplitude of the filtered signal 46. For example, the amplitude indicator may be a value of the average of the amplitude of the filtered signal or the amplitude of the filtered signal after a predefined amplification operation.The functional relationship between the amplitude of the filtered signal and the amplitude indicator may depend on the components used to amplify, refilter, or convert the filtered signal 46. .

[0136] Preferably, the measurement step MES comprises a first sub-step of converting the filtered signal 46 into a constant converted signal 54. The converted signal must be constant at least for the duration of the measurement of the amplitude of the signal.

[0137] In one embodiment, the converted signal 54 is generated as a function of a synchronization signal 33. The synchronization signal can be generated as a function of the phase start date of the control signal on the one hand, and of a predetermined phase shift value on the other hand. The phase shift value is predetermined as a function of the phase shift induced by the various components (photoemitter, photodetector, processing unit) on the filtered signal 46 with respect to the control signal 31, in particular as a function of the frequency used for the control signal 31.

[0138] The MES measurement step may comprise a second sub-step of measuring the signal which is carried out for example by an analog / digital converter. The digital value is preferably recorded on a memory or other data storage medium. The digital value is preferably transmitted to the calculation unit 6.

[0139] Preferably, the converted signal must be constant for at least two transmission periods according to the predetermined frequency to allow its measurement or for at least two periods of the filtered signal 46 and / or at least two periods according to the frequency corresponding to the upper or lower limit of the predetermined filtering frequency interval of the processing unit.

[0140] In one embodiment, the converted signal 54 may be amplified and / or filtered before the second measurement sub-step, for example by a separating amplifier 541 to advantageously ensure the integrity of the converted signal 54.

[0141] Once the measurement of the amplitude index has been carried out, the method includes the EMM calculation of the presence of an object.

[0142] Preferably, the detection of the presence of an object is determined by a comparison of the amplitude indicator with a predetermined threshold value.

[0143] In one embodiment, the method comprises the calculation EMM of a distance and / or position data of said object from said amplitude indicator.

[0144] The calculation is preferably carried out by the calculation unit 6. The distance data may comprise the distance between the object and a fixed point of the detection device such as the distance with the detection surface or the distance with a photodetector.

[0145] In one embodiment, the predetermined carrier frequency of the transmitted signal 111 is approximately 50 kHz but other frequencies may be considered.

[0146] The predetermined carrier frequency may also depend on the number of photodetectors 2 of the electronic device 1 and the frequency at which it is desired to generate a presence detection, or the generation of distance and / or position data of the object.

[0147] For example, if 5 periods are needed to perform the amplitude measurement of the converted signal 54, that we have 200 photodetectors, and that we wish to generate 100 distance data per second, a carrier frequency of at least 100 kHz is necessary. Software resources

[0148] The device according to the invention also comprises software and / or hardware means for implementing the method(s) according to the invention described below. These hardware means may comprise calculation units, processors, memories and are described in more detail in the present description.

[0149] When it is mentioned that a processor is used, this terminology also includes cases where the device comprises several processors, each configured to carry out a portion of the method and which can all be integrated into a single system or at least part of which are remote and connected to each other by wireless connections such as Bluetooth, Wi-Fi, via a remote network or any other remote communication mode.

[0150] The invention thus advantageously makes it possible to precisely measure the position or distance of an object relative to a detection surface by reducing the negative impact of the surrounding light on the measurement.

Claims

Claims

1. Method (10) for detecting an object comprising the following steps: • The generation (COM) of a control signal (31) to produce the emission of a light signal (111) by a photoemitter (110); characterized in that said light signal (111) generated is a periodic signal at a predetermined frequency; • a detection (DET) by a photodetector (2) of a light comprising at least one reflected signal (112), said reflected signal comprising a part of the light signal (111) emitted by the photoemitter (110) which is reflected on an object (103) and arrives at the photodetector (2) and the production of a detection signal (41); • the filtering (FIL) of said detection signal (41) so as to retain, from the detection signal (41) produced, only the frequencies included in a predetermined frequency interval to generate a filtered signal (46);said predetermined frequency being included in said predetermined frequency interval; • a measurement (MES) of the amplitude of the filtered signal (46) to generate an amplitude indicator (51) of said filtered signal (46); • the detection (EMM) of the presence of an object (103) from said amplitude indicator (51).;

2. Method according to claim 1, characterized in that the light detected by the photodetector (2) further comprises surrounding light (113).

3. A method according to claim 2 wherein the intensity of said surrounding light (113) sensed by the detector (102) is significantly greater than the intensity of the reflected signal (112) sensed by the detector (102).

4. Method according to claim 1, characterized in that the measuring step further comprises a sub-step of converting the filtered signal (46) into a constant converted signal (54).

5. Method according to claim 4, characterized in that the converted signal (54) is generated so as to be constant at least for the time of the measurement of the signal amplitude.

6. Method according to one of claims 4 or 5, characterized in that the conversion of the filtered signal (46) into a constant signal (54) is carried out synchronously with the control signal (31).

7. Method according to claim 4, characterized in that the conversion of the filtered signal (46) into a constant signal is carried out by a sample-and-hold circuit (521).

8. Method according to one of the preceding claims, characterized in that the step of detecting the presence of an object (103) comprises the calculation of a distance and / or position data item for said object (103) from at least one amplitude indicator (51).

9. An electronic device for detecting an object (103) for implementing the method according to any one of claims 1 to 8 and comprising: • a controller (3) adapted to produce a control signal (31), having a predetermined periodic frequency, and intended to be used to drive a photoemitter (110) in order to cause the photoemitter (110) to emit a periodic light signal (111) having a predetermined periodic frequency; • a photodetector (2) adapted to produce a light detection signal (41) comprising at least one reflected signal (112), said reflected signal comprising a portion of the light emitted by the photoemitter (110) which is reflected on an object (103) and arrives at the photodetector (2);• a signal processing unit (4) adapted to carry out the filtering of said detection signal (41) so as to retain, from the detection signal (41), only the frequencies included in a predetermined frequency interval to generate a filtered signal (46); said predetermined periodic frequency of the control signal being included in said predetermined frequency interval; • a unit (5) for measuring the amplitude of the filtered signal (46) to generate an amplitude indicator (51) of said filtered signal (46); • a calculation unit (6) configured to detect from said amplitude indicator (51) the presence of an object (103).;

10. Device according to claim 9, characterized in that the signal processing unit (4) comprises a high-pass filter for carrying out the signal filtering step, said high-pass filter being designed so that the frequency interval between its cut-off frequencies comprises the predetermined frequency of said light signal (111) emitted by the photoemitter (110).

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