Optical proximity sensor and corresponding operation method

Abstract

Embodiments of the present disclosure relate to an optical proximity sensor and a corresponding method of operation. The optical proximity sensor includes a solid-state photoelectric converter, a bias circuit for biasing the solid-state photoelectric converter, and a drive circuit. The drive circuit is configured to control the bias circuit to apply a bias signal modulated between a first value and a second value, different from the first value, to the photoelectric converter, and the solid-state photoelectric converter emits a modulated optical signal towards a target object. The drive circuit is configured to receive an electrical output signal from the solid-state photoelectric converter, the electrical output signal varying according to the modulated optical signal received at the solid-state photoelectric converter due to the reflection of the emitted modulated optical signal at the target object. The drive circuit is configured to perform a phase comparison between the modulated bias signal and the electrical output signal and generate a phase shift signal as a result of the phase comparison. The drive circuit is configured to calculate the distance between the optical proximity sensor and the target object based on the phase shift signal.

Description

Technical Field

[0001] This description relates to optical proximity sensors. One or more embodiments may rely on measuring the phase difference between a (periodically) modulated optical signal emitted from a device and the corresponding optical signal received at the device to evaluate the distance to a particular object that (at least partially) reflects the optical signal. Background Art

[0002] Optical proximity sensors are used in a variety of applications. For example, they are used in many industries and research for distance measurement, and in engineering for quality control and process monitoring. Non-contact sensor systems represent an ideal solution, especially in confined spaces.

[0003] Optical proximity sensors are also suitable for the fields of automation, chemical industry, medical technology, special machine construction, autonomous robots, mobile phones, and consumer electronics.

[0004] As non-limiting examples, other possible applications involving optical proximity sensors may include user detection (e.g., turning on / off a device and locking / unlocking a device), autonomous triggering of low-power modes for Internet of Things devices, service robots, and vacuum cleaners, drones, smart shelves and vending machines, sanitary equipment, smart buildings and smart lighting devices, gesture recognition devices. Summary of the Invention

[0005] Optical proximity sensors may rely on time-domain reflectometry (also known as direct time-of-flight sensors), frequency-domain reflectometry (also known as phase-difference sensors), and light intensity evaluation.

[0006] As Figure 1 illustrated in start FIG. 1, an optical proximity sensor 10 that relies on direct time-of-flight technology may include a timing and control unit 100, an optical transmitter 102, an optical receiver 104, and an optional human-machine interface 106. The timing and control unit 100 generates a control signal for the optical transmitter 102, which causes an optical pulse to be emitted from the optical transmitter, and simultaneously stop triggers a timer inside the timing and control unit 100. The optical pulse propagates towards the target object 110, and some of the backscattered light in the backscattered light propagates back towards the optical receiver 104. The optical pulse sensed at the receiver 104 causes the internal timer to stop at a specific time stop t start .

[0007] A mechanical scanning LIDAR (Light Detection and Ranging) device used, for example, in an advanced driver assistance system (ADAS) is an exemplary optical proximity sensor that relies on direct time-of-flight technology.

[0008] Note that sensors relying on time-domain reflectometry are generally not suitable for providing a low-cost rangefinder with good resolution at short distances, as this may involve the use of expensive broadband electronics. For example, because it involves a time resolution of a few picoseconds (1 ps = 10 -12 s) to obtain a distance resolution of millimeter scale (1 mm = 10 -3 m). Similarly, sensors relying on time-domain reflectometry may generally involve large and complex instruments, which may not be suitable for low-cost applications.

[0009] As Figure 2 illustrated, an optical proximity sensor 20 relying on frequency-domain reflectometry may include a timing and control unit 200, an optical transmitter 202, an optical receiver 204, and an optional human-machine interface 206. The timing and control unit 200 generates a control signal for the optical transmitter 202, which causes an optical signal whose intensity (amplitude) is modulated over time to be emitted from the optical transmitter 202. The intensity of the emitted optical signal may be modulated periodically and, for example, expressed as I TX (t) = I1(1 + cos(ω m t + Φ TX ))), where ω m is the modulation frequency of the emitted optical signal (in rad / s), and Φ TX is the phase of the emitted optical signal. The optical signal propagates towards the target object 210 and has an intensity I RX (t) = I2(1 + cos(ω m t + Φ RX )) + I BL of the reflected optical signal that returns to the optical receiver 204, where ω m is the modulation frequency of the received optical signal (in rad / s) (equal to the modulation frequency of the emitted optical signal), Φ RX is the phase of the received optical signal, and I BL is the intensity of the ambient background light. The reflected optical signal (e.g., its envelope) received at the receiver 204 is compared with the emitted (reference) optical signal to determine the phase shift ΔΦ = Φ RX - Φ TX . In an exemplary embodiment, the distance D between the optical proximity sensor 20 and the target object 210 can be calculated as D = c·ΔΦ / (2ω m), where again c is the speed of light propagation.

[0010] Sensors relying on frequency domain reflectometry are generally not suitable for providing low-cost optical sensors because they may involve complex systems, expensive electronics, precise mechanical alignment between the optical transmitter 202 and the optical detector 204, and may involve temperature calibration.

[0011] Sensors relying on light intensity evaluation may be affected by different light intensity environmental conditions and may involve the implementation of a calibration phase and / or a calibration look-up table.

[0012] Despite the extensive activities in this field, there is still a need for further improved solutions.

[0013] For example, there is a need for low-cost optical proximity sensors suitable for short-range distance measurement (e.g., having a range of approximately 0.5 m).

[0014] One or more embodiments of the present disclosure contribute to providing such an improved solution.

[0015] According to one or more embodiments, such an improved solution can be achieved by means of an optical proximity sensor having the features set forth in the embodiments described below.

[0016] One or more embodiments may relate to a corresponding method of operating an optical proximity sensor.

[0017] One or more embodiments may provide an optical proximity sensor that includes at least one (solid-state) device that serves both as an optical transmitter and as an optical detector. An array of single-photon avalanche diodes (SPADs), an array of avalanche photodiodes (APDs), or a silicon photomultiplier (SiPM) may be examples of such a device.

[0018] In one or more embodiments, the optical proximity sensor may include a driver circuit configured to bias the above-mentioned transmitter / detector device with a (periodically) modulated signal to cause the emission of a modulated optical signal (e.g., having a time-varying intensity).

[0019] In one or more embodiments, the driver circuit may be (fully) integrated within the optical proximity sensor to provide a so-called "single-chip" device. Alternatively, the driver circuit may be implemented on a different chip and coupled to the transmitter / detector device.

[0020] In one or more embodiments, the optical components of the sensor (e.g., lenses and / or coatings and / or layers having optical properties) may be (fully) integrated within the optical proximity sensor, e.g., by process integration. Alternatively, the optical components of the sensor may be discrete components.

[0021] Accordingly, one or more embodiments may facilitate providing a low-cost optical proximity sensor for short-range measurements with improved accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] One or more embodiments will now be described by way of example with reference to the accompanying drawings, in which:

[0023] Figure 1 and Figure 2 are schematic block diagrams of an exemplary optical proximity sensor and have been described previously;

[0024] Figures 3 to 8 is a schematic block diagram of an exemplary optical proximity sensor according to various embodiments; and

[0025] Figure 9 and Figure 10 are exploded cross-sectional views (side views) of exemplary implementation details of an optical proximity sensor according to various embodiments. DETAILED DESCRIPTION

[0026] In the following description, one or more specific details are set forth in order to provide an in-depth understanding of examples of embodiments of this description. Embodiments may be obtained without one or more specific details, or by using other methods, components, materials, etc. In other instances, well-known structures, materials, or operations have not been shown or described in detail so that certain aspects of the embodiments will not be obscured.

[0027] References to "an embodiment" or "one embodiment" in the context of this description are intended to indicate that a particular configuration, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, phrases such as "in an embodiment" or "in one embodiment" that may appear in one or more places in this description do not necessarily refer to the same embodiment. Moreover, in one or more embodiments, particular configurations, structures, or characteristics may be combined in any suitable manner.

[0028] Throughout the accompanying drawings, like parts or elements are denoted by like reference numerals / numbers, and the corresponding description will not be repeated for the sake of brevity.

[0029] The reference numerals used herein are provided solely for convenience and thus do not define the scope of protection or the scope of embodiments.

[0030] Figure 3 FIG. 1 is a schematic block diagram of an exemplary optical proximity sensor 30 according to one or more embodiments. The sensor 30 may include a (solid-state) device 300 configured to operate both as a light emitter and as a light detector (e.g., a photoelectric conversion device). For example, the emitter / detector device 300 may include an array of single-photon avalanche diodes (SPADs) or an array of avalanche photodiodes (APDs), or include a silicon photomultiplier (SiPM). As a non-limiting example, the array may include between 100 and 10,000 SPADs or APDs.

[0031] Additionally, the emitter / detector device 300 may include optical components having special optical properties, such as lenses, coatings, and layers, which will be further described below.

[0032] The sensor 30 may include a driver circuit 302 configured to drive the emitter / detector device 300. In particular, the driver circuit 302 may include a modulation circuit configured to bias the emitter / detector device 300 with a modulation signal, e.g., the modulation signal is a periodic signal having a certain modulation frequency (e.g., in the range of 100 MHz to 3 GHz). The driver circuit 302 may be integrated on the same chip as the emitter / detector device 300, or may be implemented on a different chip and coupled to the emitter / detector device 300.

[0033] The sensor 30 may include a signal conditioning circuit 304 configured to receive an output signal indicating light intensity from the emitter / detector device 300 and condition the output signal, e.g., for subsequent processing in a digital processing circuit or an analog processing circuit. For example, the signal conditioning circuit 304 may include an (analog) amplification stage, an analog-to-digital converter (ADC), and a logic interface to the processing circuit. The signal conditioning circuit 304 may be integrated on the same chip as the emitter / detector device 300, or may be implemented on a different chip and coupled to the emitter / detector device 300.

[0034] The sensor 30 may include a timing and control circuit 306 (which may be referred to herein as the timing and control unit 306) configured to generate one or more control signals for the operation of the driver circuit 302, and / or configured to process one or more conditioned signals received from the signal conditioning circuit 304. The timing and control unit 306 may thus be configured to control the operation of the entire sensor 30. For example, the timing and control unit 306 may include a microcontroller circuit (MCU).

[0035] Thus, one or more embodiments may include a device 300 configured to operate both as an optical transmitter and as an optical detector, which may advantageously result in a cost reduction and / or complexity reduction of the sensor 30.

[0036] In particular, the transmitter / detector device 300 may include an array of SPADs or an array of APDs, or include a SiPM, which is biased with a reverse bias voltage (far) above the breakdown voltage and which is nominally used as a photodetector device.

[0037] Note that, under such operating conditions, each SPAD or APD in the device 300 remains in a “static” state (i.e., it prevents current from flowing through it) statistically for a time interval of, for example, 1 ms (1 ms = 10 -3 s). In fact, due to the thermal noise in the transmitter / detector device 300, the SPADs or APDs in the array may randomly generate avalanche events at a certain rate.

[0038] Note that an avalanche event occurring in a SPAD or APD may in turn cause the emission of one or more photons from that SPAD or APD, i.e., the avalanche process in silicon may result in light emission. For example, note that during the avalanche process, every 10 5 carriers generated in a SPAD or APD may emit approximately three photons. Since a SiPM may operate with a certain gain factor (e.g., about 5·10 6 ), during the avalanche process, each SPAD or APD may emit approximately 150 photons on average.

[0039] Thus, an array of SPADs or an array of APDs or a SiPM biased with a reverse bias voltage above the breakdown voltage emits light with a certain intensity, which varies according to the biasing conditions. Since an array of SPADs or an array of APDs or a SiPM may include a large number of individual units (e.g., hundreds or thousands of SPADs or APDs), due to the thermal generation of charge carriers, avalanche events occur statistically at a constant rate even in the absence of illumination.

[0040] Therefore, due to the thermal generation effect (which in turn may cause an avalanche effect, which in turn may result in light emission), the light emitted from an array of SPADs or an array of APDs or a SiPM may be modulated over time (e.g., at a certain frequency) by modulating the biasing conditions of the array of SPADs or an array of APDs or a SiPM.

[0041] For example, in one embodiment, the bias voltage of an array of SPADs or an array of APDs or an SiPM can be switched (i.e., alternately) between a first value above the breakdown voltage and a second value below the breakdown voltage (e.g., periodically). Since light emission from an array of SPADs or an array of APDs occurs when the bias voltage is above the breakdown voltage, this bias modulation scheme can result in the emission of a (e.g., periodically) modulated optical signal (an on / off modulation), which, after being reflected by the target object, is received at the same array of SPADs or an array of APDs (which can also operate as a light detector).

[0042] Alternatively, the bias voltage of an array of SPADs or an array of APDs or an SiPM can be modulated between two values that are both above the breakdown voltage but different from each other, resulting in the modulation of the intensity of a continuous optical signal.

[0043] In one or more embodiments, the distance D between the optical proximity sensor 30 and the target object can be calculated as D = c·ΔΦ / (2ω m ) or D = c·ΔΦ / (2·2πf m ), where ω m is the modulation frequency of the emitted optical signal (in rad / s), f m is the modulation frequency of the emitted optical signal (in Hz, ω m = 2πf m ), and ΔΦ is the phase difference, which is measured between the modulated optical signal emitted by the transmitter / detector device 300 and the corresponding modulated optical signal received at the transmitter / detector device 300 after being reflected by the target object. Therefore, for a measurement system with a given phase accuracy (e.g., fixed by design), the modulation frequency can be selected as high as possible, resulting in better distance accuracy. In one embodiment, the distance D is calculated by the timing and control unit 306.

[0044] The modulation frequency f m can determine the unambiguous distance range L of the sensor, where L = c / 2f m . For example, a modulation frequency of 300 MHz can produce a range of approximately 0.5 m for the sensor, and a modulation frequency of 1 GHz can produce a range of approximately 0.15 m for the sensor. In one or more embodiments, the modulation frequency f m can be selected in the range of 100 MHz to 3 GHz. For example, the modulation frequency f m can be selected as a compromise between the target distance accuracy and the target distance range of the sensor.

[0045] Note that APDs, SPADs, and / or SiPMs can have good timing jitter performance (e.g., on the order of tens of picoseconds), but this may not be sufficient to provide millimeter-level distance accuracy for the optical proximity sensor 30.

[0046] The distance accuracy can be calculated as σ(d) = c·σ(t) / 2, where σ(t) is the uncertainty of a single time measurement, where is the phase accuracy). In one or more embodiments, the distance accuracy can be improved by increasing the number of measurements M, provided that the M measurement results can be approximated as a set of (e.g., independent and identically distributed) random variables. Thus, by performing M measurements, the time uncertainty can be reduced by a factor of resulting in a distance accuracy equal to For example, a distance accuracy of σ(d) ≈ 0.3 mm can be obtained when σ(t) ≈ 65 ps and M = 1000.

[0047] Figure 3 is an example of an embodiment in which the transmitter / detector device 300, the driver circuit 302, the signal conditioning circuit 304, and the timing and control unit 306 are implemented on different chips.

[0048] Alternatively, as illustrated in the schematic block diagram of Figure 4 the transmitter / detector device 300 and the driver circuit 302 can be implemented on the same chip 34.

[0049] Alternatively, as illustrated in the schematic block diagram of Figure 5 the transmitter / detector device 300 and the signal conditioning circuit 304 can be implemented on the same chip 35.

[0050] Alternatively, as illustrated in the schematic block diagram of Figure 6 the transmitter / detector device 300, the driver circuit 302, and the signal conditioning circuit 304 can be implemented on the same chip 36.

[0051] In one or more embodiments illustrated in Figure 7 the transmitter / detector device 300 can include a plurality of optical transmitter / detectors 3007, e.g., an array of multiple APDs or an array of multiple SPADs or multiple SiPMs. Providing multiple optical transmitter / detectors 3007 can facilitate performing multiple M measurements simultaneously.

[0052] Additionally or alternatively, in embodiments such as Figure 8In one or more of the embodiments illustrated, the transmitter / detector device 300 may include a reference channel 3008. Such a reference channel 3008 may be integrated (in a manner similar to that of the plurality of arrays) in a single chip within the main device 30. For example, in some applications, the reference channel 3008 may be useful for evaluating background light.

[0053] In one or more embodiments, the transmitter / detector device 300 may be placed in a housing to avoid background illumination.

[0054] As Figure 9 illustrated in the exploded side view of, the transmitter / detector device 300 may include the following components / layers, which may be, for example, discrete components:

[0055] 900: Substrate

[0056] 901: Array of APDs or array of SPADs, or SiPM

[0057] 902: Anti-reflection coating

[0058] 903: Background light (attenuation) filter, and

[0059] 904: Lens system

[0060] Alternatively, as Figure 10 illustrated in the exploded side view of, the optical components of the transmitter / detector device 300 may be integrated by process integration. For example, the transmitter / detector device 300 may include a substrate 1000, an array of APDs or an array of SPADs or SiPM 1001, and include an array of corresponding microlenses 1002 having an integrated anti-reflection coating and background light (attenuation) filter.

[0061] In one or more embodiments, a metal layer (e.g., a tungsten layer) may be provided between adjacent APD or SPAD cells to avoid optical crosstalk.

[0062] Of course, it will be understood that Figures 3 to 6 the embodiments illustrated in Figure 7 , Figure 8 and Figure 9 and Figure 10 any of the embodiments illustrated in any of the embodiments of may be combined.

[0063] Thus, relative to the prior art, one or more embodiments may provide one or more of the following advantages:

[0064] Good resolution for low-cost and short-range applications,

[0065] A compact and simplified system, due to the use of a device that simultaneously provides the emission and detection of optical signals,

[0066] does not require mechanical alignment between the optical transmitter and the detector,

[0067] the distance measurement is independent of the light intensity,

[0068] does not require calibration using distance or a look-up table,

[0069] does not require temperature calibration as long as the mechanical mismatch between the transmitter and the detector is suppressed and the measurement result is independent of the light intensity and thus independent of the detector / transmitter sensitivity.

[0070] As illustrated herein, an optical proximity sensor (e.g., 30) may include a solid-state photoelectric converter (e.g., 300), a bias circuit (e.g., 302) for biasing the solid-state photoelectric converter, and a drive circuit (e.g., 306). The drive circuit may be configured to:

[0071] control the bias circuit to apply a bias signal modulated between a first value and a second value, the second value being different from the first value, to the solid-state photoelectric converter, wherein the solid-state photoelectric converter emits a modulated optical signal towards a target object;

[0072] receive (e.g., 304) an electrical output signal from the solid-state photoelectric converter, the electrical output signal varying according to the modulated optical signal, which is received at the solid-state photoelectric converter due to the reflection of the emitted modulated optical signal at the target object,

[0073] perform a phase comparison between the modulated bias signal applied to the photoelectric converter and the electrical output signal received from the solid-state photoelectric converter, and as a result of the phase comparison, generate a phase shift signal that varies according to the phase shift between the modulated optical signal emitted by the solid-state photoelectric converter and the modulated optical signal received at the solid-state photoelectric converter, and

[0074] calculate the distance between the optical proximity sensor and the target object according to the phase shift signal.

[0075] As illustrated herein, the bias circuit may include a modulation circuit configured to periodically modulate the bias signal between the first value and the second value at a frequency of 100 MHz to 3 GHz (e.g., between 100 MHz and 3 GHz), wherein the solid-state photoelectric converter emits an optical signal periodically modulated at a frequency of 100 MHz to 3 GHz.

[0076] As illustrated herein, a first value of a bias signal can be higher than a breakdown voltage of a solid-state photoelectric converter, and a second value of the bias signal can be lower than the breakdown voltage of the solid-state photoelectric converter.

[0077] As illustrated herein, both a first value and a second value of a bias signal can be higher than a breakdown voltage of a solid-state photoelectric converter.

[0078] As illustrated herein, an optical proximity sensor can include an adjustment circuit (such as 304) configured to adjust an electrical output signal from a solid-state photoelectric converter and provide the adjusted electrical signal to a drive circuit.

[0079] As illustrated herein, at least two of a solid-state photoelectric converter, a bias circuit, and an adjustment circuit can be implemented on the same semiconductor chip (such as 34, 35, 36).

[0080] As illustrated herein, a solid-state photoelectric converter can include:

[0081] an antireflection coating (such as 902),

[0082] a background light attenuation filter (such as 903), and

[0083] a lens (such as 904).

[0084] As illustrated herein, a solid-state photoelectric converter can include at least one of the following:

[0085] an array of single-photon avalanche diodes,

[0086] an array of avalanche photodiodes, and

[0087] a silicon photomultiplier.

[0088] As illustrated herein, a solid-state photoelectric converter can include an array of corresponding lenses (for example, microlens 1002 positioned at a position corresponding to the position of diode 1001 in the array), and the lenses in the array of lenses have an antireflection coating and a background light attenuation filter included therein.

[0089] As illustrated herein, a solid-state photoelectric converter can include a reference channel (such as 3008) configured to evaluate background light (such as its intensity).

[0090] As illustrated herein, a drive circuit can be configured to:

[0091] perform a plurality of phase comparisons of the above-mentioned modulated bias signal applied to the photoelectric converter and the above-mentioned electrical output signal received from the solid-state photoelectric converter, and generate corresponding plurality of values of the above-mentioned phase shift signal, and

[0092] Calculate a distance between the optical proximity sensor and the target object based on the multiple values of the phase shift signal (e.g., on average) as described above.

[0093] As illustrated herein, a method of operating an optical proximity sensor according to one or more embodiments may include:

[0094] Apply a bias signal modulated between a first value and a second value, different from the first value, to a solid-state photoelectric converter, wherein a modulated optical signal is emitted by the solid-state photoelectric converter toward the target object;

[0095] Receive an electrical output signal from the solid-state photoelectric converter, the electrical output signal varying according to the modulated optical signal, the modulated optical signal being received at the solid-state photoelectric converter due to reflection of the emitted modulated optical signal at the target object;

[0096] Perform a phase comparison between the modulated bias signal applied to the solid-state photoelectric converter and the electrical output signal received from the solid-state photoelectric converter,

[0097] As a result of the phase comparison, generate a phase shift signal that varies according to a phase shift between the modulated optical signal emitted by the solid-state photoelectric converter and the modulated optical signal received at the solid-state photoelectric converter, and

[0098] Calculate a distance between the optical proximity sensor and the target object based on the phase shift signal.

[0099] Without affecting the basic principles, details and embodiments may vary, even significantly, from what is described by way of example, without departing from the scope of protection.

[0100] The various embodiments described above may be combined to provide additional embodiments. These and other changes may be made to the embodiments in light of the above detailed description. Generally, in the appended claims, the terms used should not be construed as limiting the claims to the specific embodiments disclosed in the specification and claims, but should be construed to include all possible embodiments and the full scope of equivalents to such claims. Thus, the claims are not limited by the disclosure.

Claims

1. An optical proximity sensor, comprising: A solid-state photoelectric converter; A bias circuit configured to bias the solid-state photoelectric converter; And A control circuit, wherein the control circuit is configured to: Control the bias circuit to apply a bias signal modulated between a first value and a second value to the solid-state photoelectric converter, the second value being different from the first value, both the first value and the second value being higher than the breakdown voltage of the solid-state photoelectric converter, wherein in response to the bias signal being applied to the solid-state photoelectric converter, a modulated optical signal is emitted by the solid-state photoelectric converter towards a target object; Receive an electrical output signal from the solid-state photoelectric converter, the electrical output signal varying according to the received modulated optical signal, the received modulated optical signal being received at the solid-state photoelectric converter due to reflection of the modulated optical signal emitted towards the target object; Perform a phase comparison between the bias signal applied to the solid-state photoelectric converter and the electrical output signal received from the solid-state photoelectric converter; Based on the phase comparison, generate a phase shift signal, the phase shift signal varying according to the phase shift between the modulated optical signal emitted towards the target object and the received modulated optical signal received at the solid-state photoelectric converter, and Calculate the distance between the optical proximity sensor and the target object according to the phase shift signal.

2. The optical proximity sensor according to claim 1, wherein the bias circuit includes a modulation circuit configured to periodically modulate the bias signal between the first value and the second value at a frequency between 100 MHz and 3 GHz, and the modulated optical signal emitted towards the target object is periodically modulated at the frequency between 100 MHz and 3 GHz.

3. The optical proximity sensor according to claim 1, further comprising: An adjustment circuit configured to adjust the electrical output signal from the solid-state photoelectric converter and configured to provide an adjusted electrical signal to the control circuit.

4. The optical proximity sensor according to claim 3, wherein at least two of the solid-state photoelectric converter, the bias circuit, or the adjustment circuit are implemented on the same semiconductor chip.

5. The optical proximity sensor according to claim 1, wherein the solid-state photoelectric converter includes an anti-reflection coating, a background light attenuation filter, and a lens.

6. The optical proximity sensor according to claim 1, wherein the solid-state photoelectric converter includes at least one of an array of single-photon avalanche diodes, an array of avalanche photodiodes, or a silicon photomultiplier.

7. The optical proximity sensor according to claim 6, wherein the solid-state photoelectric converter includes an array of lenses, each lens in the array of lenses having an anti-reflection coating and a background light attenuation filter included therein.

8. The optical proximity sensor according to claim 1, wherein the solid-state photoelectric converter includes a reference channel for evaluating background light.

9. The optical proximity sensor according to claim 1, wherein the control circuit is configured to: perform a plurality of phase comparisons of the modulated bias signal applied to the photoelectric converter and the electrical output signal received from the solid-state photoelectric converter, and based on the plurality of phase comparisons, generate a plurality of values of the phase shift signal, and calculate the distance between the optical proximity sensor and the target object according to the plurality of values of the phase shift signal.

10. A method of operating an optical proximity sensor, the method comprising: applying a bias signal modulated between a first value and a second value to a solid-state photoelectric converter of the optical proximity sensor, the second value being different from the first value, both the first value and the second value being higher than the breakdown voltage of the solid-state photoelectric converter, wherein in response to the bias signal being applied to the solid-state photoelectric converter, a modulated optical signal is emitted by the solid-state photoelectric converter towards a target object; receiving an electrical output signal from the solid-state photoelectric converter, the electrical output signal varying according to the received modulated optical signal, the received modulated optical signal being received at the solid-state photoelectric converter due to reflection of the modulated optical signal emitted towards the target object; performing a phase comparison of the modulated bias signal applied to the solid-state photoelectric converter and the electrical output signal received from the solid-state photoelectric converter; generating a phase shift signal based on the phase comparison, the phase shift signal varying according to a phase shift between the modulated optical signal emitted towards the target object and the received modulated optical signal received at the solid-state photoelectric converter; and calculating the distance between the optical proximity sensor and the target object according to the phase shift signal.

11. The method according to claim 10, wherein the bias signal is modulated between the first value and the second value at a frequency between 100 MHz and 3 GHz.

12. A proximity sensor, comprising: a substrate; an optical sensor on the substrate, the optical sensor being configured to: emit a modulated optical signal towards a target object in response to a bias signal being applied to the optical sensor, and being configured to detect a reflected modulated optical signal received by the optical sensor due to the modulated optical signal being reflected off the target object; a driver circuit on the substrate, the driver circuit being configured to apply the bias signal to the optical sensor, the bias signal alternating between a first value and a second value different from the first value, both the first value and the second value being higher than the breakdown voltage of the optical sensor; and a control circuit configured to calculate a phase shift between the modulated optical signal and the reflected modulated optical signal, and determine the distance between the proximity sensor and the target object based on the phase shift.

13. The proximity sensor according to claim 12, further comprising: A signal conditioning circuit on the substrate, the signal conditioning circuit being configured to process the reflected modulated optical signal for the control circuit, the signal conditioning circuit including at least one of an amplifier, an analog-to-digital converter, or a logic interface.

14. The proximity sensor according to claim 12, further comprising: An anti-reflection coating on the optical sensor; A filter on the anti-reflection coating; And A lens on the filter.

15. The proximity sensor according to claim 12, wherein The optical sensor includes at least one of an array of single photon avalanche diodes, an array of avalanche photodiodes, or a silicon photomultiplier.

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