Detection system for detecting presence or absence of user

Abstract

Embodiments of the present disclosure relate to a detection system for detecting the presence or absence of a user. An apparatus includes an infrared (IR) radiation sensor and control circuitry coupled to the IR radiation sensor. The IR radiation sensor in operation generates an IR radiation signal indicative of an intensity of IR radiation in a field of view of the IR radiation sensor. The control circuitry in operation receives the IR radiation signal, performs a motion analysis using the IR radiation signal, and determines whether a user presence check condition is satisfied based on the motion analysis. In response to determining that the user presence check condition is satisfied, the control circuitry uses a baseline analysis of the IR radiation signal to determine whether verification criteria related to the user presence check condition are satisfied. In response to determining that a verification criterion related to the user presence check condition is satisfied, the control circuitry generates a control signal indicative of the user presence condition based on the detection confidence signal and a baseline analysis of the IR radiation signal.

Description

Technical Field

[0001] The present disclosure relates to a detection system for detecting the presence or absence of a user. Furthermore, it relates to an electronic device including the detection system, a detection method for detecting the presence or absence of a user implemented by the detection system, and a corresponding computer program product. Background Art

[0002] As is known, in a personal computer (PC), detecting human presence allows improving the user experience by means of automatic control of PC functions based on human presence / absence.

[0003] For example, the Wake on Approach (WoA) function and the Lock on Leave (LoL) function are currently implemented on several PCs, especially based on the Windows system. Specifically, once human presence (in detail, the PC user is present in the usage location of the PC, e.g., in front of the PC screen and within a predefined distance from the PC) is detected, the WoA is triggered and the PC is reactivated and the user interface is enabled, while once human absence is detected, the LoL is triggered and the PC disables the user interface and enters the standby state. These are well-known functions and are typically implemented in several PCs, especially in the Windows system.

[0004] The WoA and LoL functions need to be triggered in the Windows operating system according to strict requirements based on human presence / absence. For example, the WoA needs to be triggered with a maximum delay of 1 second relative to the user entering the usage location of the PC, while the LoL needs to be triggered with a maximum delay of 5 seconds relative to the user exiting the usage location of the PC.

[0005] Known solutions for controlling the triggering of the WoA and LoL functions are generally based on detecting the pure movement of the user (e.g., motion analysis by means of a charge change sensor), detecting the presence and the towards / away movement of the user based on a Time-of-Flight (ToF) sensor, and detecting the presence of the user based on an infrared radiation sensor (e.g., “thermal MOS” TMOS sensor). Summary of the Invention

[0006] Solutions based on the use of charge change sensors have a low manufacturing cost, but have proven to have reliability problems in some cases, which makes them difficult to use on a large scale. Specifically, these solutions are generally not able to detect the continuous state of human presence (e.g., the user is stationary in front of the PC for a long period).

[0007] Solutions based on the use of ToF sensors are generally accurate in detection but are also typically very expensive, both in terms of production costs and energy consumption during use. For example, it is well known that even the cheapest ToF sensors (e.g., single-pixel type) have a much higher current consumption than other devices such as TMOS sensors. Specifically, typically ToF sensors have a current consumption of about several tens of mA, while TMOS sensors have a current consumption of about several tens of μA. In addition, ToF sensors are sensitive to the presence of any type of object (e.g., including inanimate objects) and this can lead to false detections.

[0008] TMOS sensors are very promising in the field of human presence / absence detection, thanks to their versatility of use, their lower manufacturing cost, their reduced energy consumption, and their detection selectivity for warm bodies (i.e., objects that emit infrared radiation, such as humans). However, the currently known presence / absence detection techniques using TMOS sensors are currently unable to detect whether a user is present in the field of view (FoV) of the TMOS sensor at the startup of the algorithm, do not provide feedback on the detection confidence, and are affected by long-term drift due to changes in the ambient temperature in the presence of a user.

[0009] Therefore, none of the currently known solutions can ensure a sufficiently accurate human presence / absence check to allow reliable control of the WoA and LoL functions of a PC.

[0010] In one embodiment, the device includes an infrared (IR) radiation sensor and control circuitry coupled to the IR radiation sensor. The IR radiation sensor generates an IR radiation signal in operation, the IR radiation signal indicating the intensity of IR radiation in the field of view of the IR radiation sensor. The control circuitry receives the IR radiation signal in operation, performs motion analysis using the IR radiation signal, and determines whether a user presence check condition is satisfied based on the motion analysis. In response to determining that the user presence check condition is satisfied, the control circuitry uses baseline analysis of the IR radiation signal to determine whether verification criteria related to the user presence check condition are satisfied. In response to determining that the verification criteria related to the user presence check condition are satisfied, the control circuitry generates a control signal indicating the user presence condition based on the detection confidence signal and the baseline analysis of the IR radiation signal.

[0011] In one embodiment, the system includes an infrared (IR) radiation sensor and control circuitry. The IR radiation sensor detects IR radiation in the field of view of the IR radiation sensor during operation. The control circuitry receives the IR radiation signal during operation, performs motion analysis using the IR radiation signal, and determines whether a user presence check condition is satisfied based on the motion analysis. In response to determining that the user presence check condition is satisfied, the control circuitry determines whether verification criteria related to the user presence check condition are satisfied using baseline analysis of the IR radiation signal. In response to determining that the verification criteria related to the user presence check condition are satisfied, the control circuitry generates one or more system control signals indicative of the user presence condition based on a detection confidence signal and baseline analysis of the IR radiation signal.

[0012] In one embodiment, the method includes: using an infrared (IR) radiation sensor to generate an IR radiation signal indicative of the intensity of IR radiation in the field of view of the IR radiation sensor; performing motion analysis using the IR radiation signal; determining whether a user presence check condition is satisfied based on the motion analysis; in response to determining that the user presence check condition is satisfied, determining whether verification criteria related to the user presence check condition are satisfied using baseline analysis of the IR radiation signal; and in response to determining that the verification criteria related to the user presence check condition are satisfied, generating a control signal indicative of the user presence condition based on a detection confidence signal and baseline analysis of the IR radiation signal.

[0013] In one embodiment, the content of a non-transitory computer-readable medium configures processing circuitry to perform a method that includes: performing motion analysis using an infrared (IR) radiation signal; determining whether a user presence check condition is satisfied based on the motion analysis; in response to determining that the user presence check condition is satisfied, determining whether verification criteria related to the user presence check condition are satisfied using baseline analysis of the IR radiation signal; and in response to determining that the verification criteria related to the user presence check condition are satisfied, generating a control signal indicative of the user presence condition based on a detection confidence signal and baseline analysis of the IR radiation signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] To better understand the present disclosure, example embodiments are now described by way of non-limiting examples only with reference to the accompanying drawings, in which:

[0015] Figure 1 is a schematic perspective view of an electronic device according to an embodiment of the present disclosure;

[0016] Figure 2 is according to an embodiment of the present disclosure Figure 1 of the electronic device, the electronic device including a detection system;

[0017] Figure 3 is a block diagram of a detection system according to an embodiment of the present disclosure; Figure 2

[0018] Figure 4 is a block diagram showing a detection method implemented by the detection system according to an embodiment of the present disclosure; Figure 2

[0019] Figure 5 is a block diagram showing a finite state machine according to an embodiment of the present disclosure, the finite state machine providing for Figure 2 the detection method;

[0020] Figure 6A , Figure 6B , Figure 6C , Figure 6D , Figure 6E and Figure 6F is a graph showing examples of quantities measured by the detection system or generated by the detection system during the execution of the detection method in a first exemplary use case;

[0021] Figure 7A , Figure 7B , Figure 7C , Figure 7D , Figure 7E and Figure 7F is a graph showing examples of quantities measured by the detection system or generated by the detection system during the execution of the detection method in a second exemplary use case;

[0022] Figure 8A , Figure 8B , Figure 8C , Figure 8D , Figure 8E and Figure 8F is a graph showing examples of quantities measured by the detection system or generated by the detection system during the execution of the detection method in a third exemplary use case;

[0023] Figure 9A , Figure 9B , Figure 9C , Figure 9D , Figure 9E and Figure 9F is a graph showing examples of quantities measured by the detection system or generated by the detection system during the execution of the detection method in a fourth exemplary use case; and

[0024] Figure 10A , Figure 10B , Figure 10C , Figure 10D , Figure 10E and Figure 10F ​​It is a graph showing an example of a quantity measured by a detection system or generated by the detection system during the execution of a detection method in a fifth exemplary use case.

[0025] Specifically, the accompanying drawings are shown with reference to a three-axis Cartesian system defined by an X-axis, a Y-axis, and a Z-axis, and the X-axis, Y-axis, and Z-axis are orthogonal to each other.

[0026] In the following description, elements common to different embodiments have been indicated using the same reference numerals. Detailed Description

[0027] Figure 1 Shows an electronic device 10 that a user can use, such as Figure 2 shown by reference numeral 11 in the figure.

[0028] Figure 1 Shows an exemplary and non-limiting case where the electronic device 10 is a PC (and thus also indicated by reference numeral 10 hereinafter).

[0029] Hereinafter, this exemplary case is considered, however, other types of electronic devices 10 can be considered similarly. For illustrative and non-limiting purposes, the electronic device 10 can also be a soundbar, a smart home appliance, an IoT device, a tablet computer, an industrial machine, etc.

[0030] The PC 10 includes a detection system 20, which is better described below and is configured to detect the presence or absence of the user 11 at the PC 10.

[0031] Specifically, the detection system 20 extends at the main surface 12 of the PC 10, and the user 11 faces the main surface 12 of the PC 10 when the user 11 is present and in the use position (or position of interest, defined position, etc.) of the PC 10.

[0032] In detail, the use position is the position where the user 11 can use the PC 10, or more generally, the set of positions where the user 11 can use the PC 10. For example, the use position is identified by the fact that the user 11 is in the front of the PC 10 (he / she faces the main surface 12) and the distance from the PC 10 is less than a threshold distance. More specifically, the distance between the user 11 and the detection system 20 can be considered as the distance between the user 11 and the PC 10, and for illustrative and non-limiting purposes, the threshold distance can be equal to about 80 centimeters.

[0033] For example, the PC 10 includes a screen 14 that defines a part of the main surface 12, and as Figure 1 shown, the detection system 20 can extend above the screen 14, for example, extending laterally to the camera 16 of the PC 10.

[0034] In this way, when the user 11 is in the usage position of the PC 10, the user 11 faces the detection system 20, and thus the detection system 20 can detect the presence of the user 11.

[0035] Reference Figure 2 , the detection system 20 will now be described in more detail.

[0036] The detection system 20 includes an infrared IR radiation sensor 22 and a main control unit or circuit 24 that are coupled to each other. Hereinafter, the IR radiation sensor 22 is also more simply referred to as the IR sensor 22.

[0037] According to an exemplary embodiment, the main control unit 24 (such as a microprocessor, a microcontroller, a dedicated computing unit, or other circuit devices) is an electronic control unit or circuit, which may include a data storage unit (not shown, such as a memory, for example, a non-volatile memory) for storing the collected data and a processing unit or core (not shown) for processing the collected data that are coupled to each other. In a manner not shown and known per se, the main control unit or circuit 24 may also include one or more of the following components: an electrical energy storage module (such as a battery), a power management module for power management, a digital front-end interface module having the IR sensor 22, a communication module (such as radio communication based on Bluetooth technology).

[0038] The IR sensor 22 is coupled (e.g., electrically coupled) to the main control unit 24. For example, the IR sensor 22 is coupled to the main control unit 24 by means of a digital front-end interface module of the main control unit 24 of a known type per se.

[0039] For example, the IR sensor 22 can be formed at least in part using known microfabrication techniques for processing semiconductor materials such as, for example, silicon. However, other techniques can also be considered similarly.

[0040] The IR sensor 22 is an IR radiation sensor that is configured to detect the IR radiation emitted when an emitter (a hot body and particularly the user 11) is within the field of view (FoV) 26 of the IR sensor 22.

[0041] Specifically, the field of view 26 covers and includes the usage position of the PC 10. For example, the field of view 26 is defined by an angular opening α and a maximum depth D max such that the angular opening α is equal to approximately 80°, and the maximum depth D max is, for example, equal to approximately 1.5 m. For example, the maximum depth D maxThis can be understood as the maximum distance at which user 11 can be located relative to PC 10 such that the IR radiation emitted by user 11 is detected by IR sensor 22 with an accuracy equal to the defined minimum accuracy. In order for the usage position of PC 10 to be covered by the field of view 26, IR sensor 22 may also include an integrated lens and / or a cover of a known type, which allows the nature of the field of view to be modified so as to be adapted to a specific application.

[0042] Specifically, the size and orientation of the field of view 26 are determined such that when user 11 is in the usage position of PC 10, he / she may be present in the field of view 26. In addition, its size and orientation are determined such that it is substantially impossible for multiple users to be present in the field of view 26 simultaneously. Therefore, the case where there may be only one user 11 in the field of view 26 is considered hereinafter.

[0043] Specifically, IR sensor 22 includes a "thermal MOS" TMOS sensor.

[0044] TMOS is a field-effect transistor device of a known type and is generally used in sensor applications to determine the amount of radiation (specifically IR radiation) emitted by an emitter (here user 11). An emitter is any hot body that emits IR radiation, such as a person or an animal. The radiation emitted by the emitter and received by TMOS causes carriers to be generated at the conductive channel of TMOS, and thus, the output current of TMOS changes correspondingly; the output current of TMOS can be related to the amount of radiation emitted by the object under inspection, such that the radiation emitted by the emitter can be measured.

[0045] Generally, TMOS allows the presence or absence of user 11 in its field of view 26 to be detected.

[0046] According to the embodiment exemplarily considered below, the TMOS sensor present in detection system 20 is an infrared temperature sensor TMOS, such as the TMOS sensor with the reference code STHS34PF80 sold by STMicroelectronics.

[0047] Specifically, the TMOS sensor is capable of generating an infrared (IR) radiation signal related to the presence / absence of user 11 in the field of view 26.

[0048] The IR radiation signal is a signal indicating the intensity of the IR radiation present in the field of view 26 of IR sensor 22, and the intensity of the IR radiation is related to the temperature of an entity (a living being, such as a person, or an inanimate but heated object, such as a heating device) present in the field of view 26 of IR sensor 22.

[0049] Thus, the IR radiation signal is determined based on both the IR radiation emitted by the user 11 present in the field of view 26 of the TMOS sensor and the IR radiation that may generally be present in the environment where the TMOS sensor is located even in the absence of living beings. In other words, the IR radiation signal has an environmental baseline that depends on the amount of environmental IR radiation measured by the TMOS sensor in the absence of the user 11 in the field of view 26 (e.g., due to the temperature of the air surrounding the TMOS sensor, in the presence of a heating system, etc.), and can change relative to this environmental baseline when the TMOS sensor detects the IR radiation emitted by the user 11 (which is added to the existing environmental IR radiation). Thus, as described better below, the change in the IR radiation signal of the TMOS sensor relative to its environmental baseline can be related to the presence of the user 11 in the field of view 26 of the IR sensor 22.

[0050] Specifically, the TMOS sensor can be of the temperature-compensated type in a manner known per se.

[0051] For example, in the present application, the TMOS sensor can operate at an output data rate (ODR) equal to approximately 30 Hz.

[0052] In the embodiment exemplarily considered herein, where the TMOS sensor is the STHS34PF80 of STMicroelectronics, the IR radiation signal corresponds to the signal T object (or also corresponds to T obj ). Thus, the reference numeral T object is used hereinafter to indicate the IR radiation signal.

[0053] As Figure 3 shown, in use, the IR sensor 22 generates an IR radiation signal T object , and the IR radiation signal T object indicates the intensity of the IR radiation emitted by the user 11 and detected by the IR sensor 22 when the user 11 is in the field of view 26. Thus, the IR radiation signal T object indicates (in an indirect manner) the presence / absence of the user 11 in the field of view 26.

[0054] In Figure 3 the exemplified embodiment, the IR radiation signal T object is received by the main control unit or circuitry 24.

[0055] Specifically, the main control unit 24 includes a finite state machine (FSM) module or circuitry 30 and an evaluation module or circuitry 32 that are coupled to each other. In detail, the FSM module 30 is also coupled to the IR sensor 22.

[0056] In use, the FSM module 30 receives the IR radiation signal T from the IR sensor 22. object , realize the detection method (such as Figure 4 50 ), and by detecting the method 50 and radiating the IR signal T object Initially, a detection confidence signal R_CONF is generated indicating the detection confidence, in particular with respect to the presence or absence of the user 11 in the field of view 26 .

[0057] In detail, the detection confidence signal R_CONF (e.g., a digital electrical signal) can assume a value between 0% and 100% (including boundary values), where 0% represents absolute confidence that the user 11 does not exist in the field of view 26, 100% represents absolute confidence that the user 11 is present in the field of view 26, and intermediate values represent corresponding intermediate confidence levels that the user 11 is present in the field of view 26 (specifically, 50% represents absolute uncertainty about the actual situation of the user 11 in the field of view 26, since there is equal confidence between presence and absence).

[0058] In use, the evaluation module 32 receives the detection confidence signal R_CONF and generates a state signal STATE and a state confidence signal S_CONF based on the detection confidence signal R_CONF.

[0059] The state signal STATE (eg, a digital electric signal) indicates a state of the user 11 in the field of view 26 , and in detail may assume a first value indicating that the user 11 is present in the field of view 26 or a second value indicating that the user 11 is not present in the field of view 26 .

[0060] The state confidence signal S_CONF (e.g., a digital electrical signal) indicates the confidence level of the detected presence / absence of the user 11 in the field of view 26. Specifically, the state confidence signal S_CONF may assume a value between 50% and 100% (inclusive), where 50% represents absolute uncertainty of the detected presence / absence of the user 11 in the field of view 26, 100% represents absolute confidence in the presence / absence of the user 11 in the field of view 26, and intermediate values represent corresponding intermediate confidence levels of the presence / absence of the user in the field of view 26.

[0061] More specifically, if the detection confidence signal R_CONF received by the evaluation module 32 indicates a confidence level less than the presence confidence threshold level (e.g., equal to 50%), the evaluation module 32 generates a status signal STATE indicating the absence state of the user 11. Conversely, if the detection confidence signal R_CONF received by the evaluation module 32 indicates a confidence level greater than or equal to the presence confidence threshold level, the evaluation module 32 generates a status signal STATE indicating the presence state of the user 11.

[0062] In addition, if the status signal STATE indicates the presence state of the user 11, the evaluation module 32 generates a status confidence signal S_CONF having a value equal to the value assumed by the detection confidence signal R_CONF. Conversely, if the status signal STATE indicates the absence state of the user 11, the evaluation module 32 generates a status confidence signal S_CONF having a value equal to the difference between 100% and the value assumed by the detection confidence signal R_CONF.

[0063] For example, if the detection confidence signal R_CONF is equal to 30%, the status signal STATE indicates the absence state of the user 11 and the status confidence signal S_CONF is equal to 70%; conversely, if the detection confidence signal R_CONF is equal to 90%, the status signal STATE indicates the presence state of the user 11 and the status confidence signal S_CONF is equal to 90%.

[0064] Figure 4 A detection method 50 implemented by the FSM module 30 to detect the presence or absence of the user 11 in the field of view 26 is shown (specifically, to generate a detection confidence signal R_CONF indicating the detection confidence of the presence of the user 11).

[0065] Now referring generally to Figure 4 to describe the detection method 50, but additional details are provided below with reference to Figure 5 The detection method 50 is executed in real time and thus allows the generation of a detection confidence signal R_CONF, which is updated in real time and continuously based on the IR radiation signal T

[0066] The changes that occur during the following steps are the criteria by which the detection confidence signal R_CONF is updated based on the IR radiation signal T, as described below. object As described below, the changes that occur during the following steps are the criteria by which the detection confidence signal R_CONF is updated based on the IR radiation signal T object In other words, at each moment, the corresponding value of the detection confidence signal R_CONF (and thus the corresponding value of the status signal STATE and the corresponding value of the status confidence signal S_CONF) is based on the IR radiation signal T

[0067] and the IR radiation signal T object(Specifically, the value of the IR radiation signal T object at the considered moment and the value of the IR radiation signal T object before the considered moment) are generated. However, the mode in which the value of the detection confidence signal R_CONF is calculated changes at each moment by means of the steps of the detection method 50.

[0068] Specifically, at step S10 of the detection method 50, the presence / absence of the user 11 in the field of view 26 is determined based on the IR radiation signal T object received from the IR sensor 22 and by means of motion analysis. The motion analysis is better explained in detail below with reference to Figure 5 .

[0069] The presence / absence of the user 11 in the field of view 26 continues to be determined by means of motion analysis until a presence / absence check condition is detected, which is better described below and is related to a sudden and significant change in the baseline of the IR radiation signal T object , and a sudden and significant change in the baseline of the IR radiation signal T object can indicate that the user 11 enters or exits the field of view 26.

[0070] Specifically, at step S12 of the detection method 50, it is verified whether the presence / absence check condition is detected. As long as it is not detected (output "no" of step S12), the method returns to step S10 and step S10 is repeated again. On the contrary, when the presence / absence check condition is detected (output "yes" of step S12), the method proceeds to step S14 of the detection method 50.

[0071] At step S14, it is verified whether the presence / absence check condition indicates a presence check or an absence check.

[0072] If the presence / absence check condition indicates a presence check (output "presence" of step S14), the method proceeds to step S16 of the detection method 50.

[0073] On the contrary, if the presence / absence check condition indicates an absence check (output "absence" of step S14), the method proceeds to step S20 of the detection method 50.

[0074] At step S16, a presence check is performed to verify whether the presence check is verified (whether the entry of the user 11 into the field of view 26 is confirmed). As better described below, this situation occurs when the change in the baseline of the IR radiation signal T object complies with certain criteria in terms of duration and thus effectively indicates that the user 11 enters the field of view 26.

[0075] At step S18, which follows step S16 of detection method 50, it is verified whether the presence check performed at step S16 has confirmed that user 11 has entered the field of view 26 and, thus, has confirmed the current presence of user 11 in the field of view 26.

[0076] If entry is confirmed (output “yes” of step S18), the method proceeds to step S24 of detection method 50.

[0077] Conversely, if entry is not confirmed (output “no” of step S18), the method returns to step S10 and step S19 is repeated again.

[0078] At step S20, an absence check is performed to verify whether the absence check has been verified (whether the exit of user 11 from the field of view 16 has been confirmed). As described better below, this situation occurs when the baseline change of the IR radiation signal T object complies with certain criteria in terms of duration and, thus, effectively indicates the exit of user 11 from the field of view 26.

[0079] At step S22, which follows step S20 of detection method 50, it is verified whether the absence check performed at step S20 has confirmed the exit of user 11 from the field of view 26 and, thus, has confirmed the current absence of user 11 in the field of view 26.

[0080] If exit is confirmed (output “yes” of step S22), the method proceeds to step S24 of detection method 50.

[0081] Conversely, if exit is not confirmed (output “no” of step S22), the method returns to step S10 and step S10 is repeated again.

[0082] At step S24 of detection method 50, the presence / absence of user 11 in the field of view 26 is determined based on the IR radiation signal T received from the IR sensor 22 object , by means of baseline analysis and based on certain previously obtained information on presence or absence (e.g., due to steps S16 - S22). Baseline analysis is better explained below with reference to Figure 5 to better explain baseline analysis.

[0083] Once step S24 is reached, detection method 50 repeatedly executes this step until the operation ends (e.g., until PC10 is switched off).

[0084] In other words, initially, the presence / absence of user 11 is determined by means of motion analysis (step S10) because it is not yet known whether user 11 is actually present or absent in the field of view 26. The advantage of this analysis is that it can be performed without prior knowledge of the actual presence / absence of user 11 in the field of view 26, but its disadvantage is that it generates inaccurate detections.

[0085] The motion analysis is performed until an event (presence / absence check condition) occurs, which can mean that user 11 enters the field of view 26 / exits from the field of view 26 (steps S12 - S22).

[0086] If these events are not verified (e.g., they are caused by events other than user 11 entering the field of view 26 / exiting from the field of view 26), the method returns to the motion analysis.

[0087] On the contrary, if these events are verified, information regarding the actual presence / absence of user 11 in the field of view 26 is obtained.

[0088] Therefore, after that, the method proceeds (step S24) to determine the presence / absence of user 11, and the determination of the presence / absence of user 11 occurs by means of baseline analysis, based on the previously obtained information. In fact, the disadvantage of baseline analysis is that it requires prior knowledge of the actual presence / absence of user 11 in the field of view 26 and the range of baseline changes of the IR radiation signal T object The range of baseline changes of the IR radiation signal T object in fact indicates that user 11 enters the field of view 26 or exits from the field of view 26. However, its advantage is that it allows for a more accurate and reliable detection compared to motion analysis.

[0089] Furthermore and in a way not shown in Figure 4 one or more functions of the electronic device 10 can be controlled based on the status signal STATE or the detection confidence signal R_CONF. Specifically, the presence or absence information carried by the status signal STATE and the detection confidence signal R_CONF can be used to selectively trigger the wake - on - approach (WoA) function and the leave - on - lock (LoL) function. For example, the WoA function can be triggered when the average human presence delay is up to 1 second, while the LoL function can be triggered when the average human absence delay is up to 5 seconds.

[0090] Figure 5 An embodiment of a finite - state machine (FSM, indicated here by the reference numeral 30’) implemented by the FSM module or circuit 30 is shown.

[0091] Specifically, the FSM 30’ includes the following states: an initialization state 40, a presence check state 42, an absence check state 44, and a final state 46.

[0092] The initialization state 40 implements step S10 of the detection method 50.

[0093] The presence check state 42 implements step S16 of the detection method 50.

[0094] The absence check state 44 implements step S20 of the detection method 50.

[0095] The final state 46 implements step S24 of the detection method 50.

[0096] In addition, the transition conditions between the initialization state 40 and the presence check state 42 implement steps S12 and S14 (outputting "present"), the transition conditions between the initialization state 40 and the absence check state 44 implement steps S12 and S14 (outputting "absent"), the transition conditions between the presence check state 42 and the initialization state 40 implement step S18 (outputting "no"), the transition conditions between the absence check state 44 and the initialization state 40 implement step S22 (outputting "no"), the transition conditions between the presence check state 42 and the final state 46 implement step S18 (outputting "yes"), and the transition conditions between the absence check state 44 and the final state 46 implement step S22 (outputting "yes").

[0097] More specifically, in the initialization state 40, the presence / absence of the user 11 in the field of view 26 is determined by means of motion analysis because it is not yet known whether the user 11 actually exists in the field of view 26.

[0098] In this state, the detection confidence signal R_CONF is initialized to an initial confidence level (e.g., equal to 100%), and then it can vary between two thresholds (such as 0% and 100%) according to the standard deviation of the IR radiation signal T object .

[0099] Specifically, in this state, if the standard deviation of the IR radiation signal T object is less than a first motion threshold (indicating the absence of motion of a hot body in the field of view 26 and, for example, equal to approximately 30 LSB), then the confidence value of the detection confidence signal R_CONF decreases at a decreasing rate, and if the standard deviation of the IR radiation signal T object is greater than a second motion threshold (greater than the first motion threshold and indicating the presence of hot body motion in the field of view 26 and, for example, equal to approximately 40 LSB), then the confidence value of the detection confidence signal R_CONF increases at an increasing rate. In addition, if the IR radiation signal T objectIf the standard deviation of is between the first motion threshold and the second motion threshold or is equal to the first motion threshold and the second motion threshold, the confidence value of the detection confidence signal R_CONF remains unchanged.

[0100] Alternatively, similar actions can be implemented based on a single motion threshold (e.g., having an intermediate value between the first motion threshold and the second motion threshold and exemplarily equal to about 35 LSB here). In this case, if the IR radiation signal T object If the standard deviation of is less than the motion threshold, the confidence value of the detection confidence signal R_CONF decreases at a decreasing rate, otherwise, it increases at an increasing rate. However, hereinafter, reference is made to the case described above using the first motion threshold and the second motion threshold.

[0101] It is obvious that when the confidence value of the detection confidence signal R_CONF reaches 100%, the increase stops (and in this case, the confidence value remains unchanged as long as the increase condition continues to exist), and when the confidence value of the detection confidence signal R_CONF reaches 0%, the decrease stops (and in this case, the confidence value remains unchanged as long as the decrease condition continues to exist).

[0102] For example, the rate of decrease may be a defined or fixed rate and, for example, equal to 3% per second. The rate of increase may be variable and, for example, equal to a defined or fixed rate (for example, 3% per second) and a value corresponding to the value of the IR radiation signal T. object The sum of the standard deviation of the variable rate (e.g., equal to a defined or fixed rate (e.g., 3% per second) and the measured IR radiation signal T object =(t(t)) / (t) = ( ... a =T k (1+V m / V s ), where T a is the rate of increase, T k is the defined or fixed rate, V m is the measured IR radiation signal T object The standard deviation of V s is the second motion threshold. Specifically, according to the IR radiation signal T object This variable rate of standard deviation of allows giving greater weight to possible movements of the user 11 so as to make the analysis more sensitive to the detection of presence in the event of movement or gesture. Thus, in general, the rate of decrease is equal to or smaller than the rate of increase in absolute value.

[0103] The confidence update based on the criteria listed here defines the motion analysis mentioned previously and performed in step S10 .

[0104] In addition, in the initialization state 40, the baseline change of the IR radiation signal T object is also calculated and compared with a baseline change threshold to verify the presence / absence of a check condition.

[0105] Specifically, the baseline change of the IR radiation signal T object is calculated as the difference between the fast average signal and the slow average signal of the IR radiation signal T object . The fast average signal and the slow average signal are shown in the following object,f and object,s using the reference signs T Figure 6B , Figure 6C , Figure 7B , Figure 7C , Figure 8B , Figure 8C , Figure 9B , Figure 9C , Figure 10B and Figure 10C .

[0106] The fast average signal and the slow average signal are calculated by filtering the IR radiation signal T object using corresponding filters with different time constants (specifically, such that the fast average signal is more sensitive to fast changes of the IR radiation signal T object than the slow average signal). Specifically, the fast average signal and the slow average signal are calculated using exponential average filters, where each exponential average filter has a corresponding time decay coefficient, and the time decay coefficient is larger for the fast average signal and smaller for the slow average signal. For example, the time decay coefficient for the fast average signal is equal to 0.05, and the time decay coefficient for the slow average signal is equal to 0.0025.

[0107] More specifically, the fast average signal T object,f and the slow average signal T object,s can be determined according to: T object,i (t) = T object,i (t - 1) + k i ·(T object (t) - T object,i (t - 1)), where i = f, s are indices respectively identifying the fast average signal T object,f and the slow average signal T object,s , and k f and k s are the time decay coefficients for the fast average signal T object,f and the slow average signal T object,s respectively.

[0108] In addition, the slow average signal may not be continuously updated, but rather updated in a selective manner based on the fast average signal to reduce its dependence on fast movements or postures. Specifically, the update of the slow average signal may occur only when the value of the standard deviation of the fast average signal is less than an average update threshold (which is defined or fixed and, for example, equal to 150 LSB). Conversely, when the value of the standard deviation of the fast average signal is greater than or equal to the average update threshold, the slow average signal remains unchanged. In other words, when the standard deviation of the fast average signal is greater than or equal to the average update threshold (e.g., when a positive or negative peak of the IR radiation signal T object associated with the entry / exit movement or posture of user 11 is detected), the slow average signal undergoes clamping.

[0109] The baseline change of the IR radiation signal T object is then compared with a baseline change threshold (e.g., at each moment) in absolute value to implement the control of step S12. The baseline change threshold is of a defined or fixed type (e.g., it is equal to 500 LSB). Specifically, if the baseline change of the IR radiation signal T object is greater than the baseline change threshold in absolute value, a presence / absence check condition is detected; otherwise, the presence / absence check condition is not detected. If the presence / absence check condition is detected, the method proceeds from the initialization state 40 to either the presence check state 42 or the absence check state 44.

[0110] Specifically, the selection between the presence check state 42 and the absence check state 44 occurs based on the sign of the baseline change of the IR radiation signal T object (step S14). If the difference between the fast average signal and the slow average signal of the IR radiation signal T object is positive, a positive drift (i.e., an increase) of the baseline of the IR radiation signal T object corresponding to the possible entry of user 11 into the field of view 26 occurs, and then the method proceeds to the presence check state 42 (the output "present" of step S14). Conversely, if the difference between the fast average signal and the slow average signal of the IR radiation signal T object is negative, a negative drift (i.e., a decrease) of the baseline of the IR radiation signal T object corresponding to the possible exit of user 11 from the field of view 26 occurs, and then the method proceeds to the absence check state 44 (the output "absent" of step S14).

[0111] In the presence check state 42, it is verified whether the IR radiation signal T objectWhether the baseline change of the IR radiation signal T actually indicates that the user 11 has entered the field of view 26, or whether it is due to other events (e.g., the movement or posture of the user 11 already present in the field of view 26, or other events of an increase in IR radiation detected by the IR sensor 22 that is not caused by the user 11) object has a brief but significant increase in its baseline. This verification corresponds to steps S16 and S18.

[0112] Specifically, in this state, it is verified whether the IR radiation signal T object has a baseline change that remains greater in absolute value than a first baseline change percentage threshold for a time interval longer than a first threshold time interval, where the first threshold time interval is of a defined or fixed type and is, for example, equal to 1 second and generally not greater than 1 second. The first baseline change percentage threshold is related to the baseline change threshold, and specifically, it is directly proportional to the baseline change threshold and less than the baseline change threshold. For example, the first baseline change percentage threshold is equal to a first percentage (e.g., 90%) of the baseline change threshold.

[0113] If this condition is confirmed (the output "yes" of step S18), then the significant and persistent baseline change of the IR radiation signal T object effectively indicates that the user 11 has entered the field of view 26, and thus indicates his / her presence in the field of view 26. In this case, the method then proceeds to the final state 46.

[0114] Conversely, if this condition is not confirmed (the output "no" of step S18), then the significant but brief baseline change of the IR radiation signal T object is not considered to indicate that the user 11 has entered the field of view 26, but is attributable to other events, and thus does not allow verification of the presence of the user 11 in the field of view 26. In this case, the method then returns to the initialization state 40.

[0115] In the absence check state 44, it is verified whether the baseline change of the IR radiation signal T object actually indicates that the user 11 has exited the field of view 26, or whether it is due to other events (e.g., the movement or posture of the user 11 already present in the field of view 26, or other events of a decrease in IR radiation detected by the IR sensor 22 that is not caused by the user 11) that result in a brief but significant decrease in the baseline of the IR radiation signal T object has a brief but significant decrease in its baseline. This verification corresponds to steps S20 and S22.

[0116] Specifically, in this state, it is verified whether the IR radiation signal T objectwhether the baseline change remains greater in absolute value than a first baseline change percentage threshold over a time interval longer than a second threshold time interval, the second threshold time interval having a defined or fixed type and being equal to, for example, 5 seconds and generally not greater than 5 seconds.

[0117] If this condition is confirmed (output “yes” of step S22), then the IR radiation signal T object a significant and persistent baseline change effectively indicates that user 11 has exited the field of view 26 and thus indicates his / her absence in the field of view 26. In this case, the method then proceeds to the final state 46.

[0118] Conversely, if this condition is not confirmed (output “no” of step S22), then the IR radiation signal T object a significant but transient baseline change is not considered to indicate that user 11 has exited the field of view 26 but is attributable to other events and thus does not allow verification of the absence of user 11 entering the field of view 26. In this case, the method then returns to the initialization state 40.

[0119] In the final state 46, the presence / absence of user 11 is determined by means of baseline analysis, which is performed based on prior knowledge of the presence and absence of user 11 in the field of view 26. This corresponds to step S24.

[0120] Specifically, when the method proceeds to the final state 46, if the method arrives from the presence check state 42, the detection confidence signal R_CONF is detected with an initial assumption equal to 100% (determined presence of user 11), and if the method arrives from the absence check state 44, the detection confidence signal R_CONF is detected with an initial assumption equal to 0% (determined absence of user 11).

[0121] Thereafter, the transition from detection of presence to detection of absence and the transition from detection of absence to detection of presence are decided in the final state 46 by the detection of an event, where the IR radiation signal T object has a baseline change greater in absolute value than the baseline change threshold.

[0122] Specifically, if the detection confidence signal R_CONF at the considered previous moment indicates the absence of user 11 and at the considered moment, a positive baseline change of the IR radiation signal T object is detected and becomes greater in absolute value than the baseline change threshold, the value of the detection confidence signal R_CONF is set to 100%.

[0123] Furthermore, in this case, the value of the slow average signal can also be temporarily set (clamped), thus preventing it from depending on the IR radiation signal T objectvaries and updates with values having such a significant baseline change. As long as the IR radiation signal T object has stabilized to a new stable baseline, this box of the updated slow average signal continues. In other words, as long as the standard deviation of the IR radiation signal T object is greater than a clamping threshold (defined or fixed and, for example, equal to about 50 LSB), this box of the updated slow average signal continues. Once the standard deviation of the IR radiation signal T object becomes equal to or less than the clamping threshold, the slow average signal is again initialized to the value that the fast average signal has at that moment. This can prevent inevitable fluctuations of the IR radiation signal T object at the transition from non - existence to existence from significantly affecting the slow average signal, which then takes a long time to stabilize back to a value that truly represents the new baseline of the IR radiation signal T object .

[0124] Furthermore, in this case, if the baseline change of the IR radiation signal T object becomes less than or equal to the first baseline change percentage threshold in absolute value before the slow average signal is re - initialized at the end of clamping, the value of the detection confidence signal R_CONF is reset to 0% and the box of the updated slow average signal is interrupted.

[0125] Conversely, if the detection confidence signal R_CONF at the previously considered moment indicates the presence of the user 11, and at the considered moment, a negative baseline change of the IR radiation signal T object is detected and becomes greater than the baseline change threshold in absolute value, the value of the detection confidence signal R_CONF decreases at a final decrease rate, which is defined or fixed and, for example, equal to 20% per second.

[0126] Furthermore, in this case, similar to what has been described previously, the value of the slow average signal can also be temporarily set (clamped). However, in this case, once a negative baseline change of the IR radiation signal T object is detected and becomes greater than the baseline change threshold in absolute value, and for the time required for the continuous detection confidence signal R_CONF to reach 0% (in the considered example, equal to 5 seconds), and then for the time required for the IR radiation signal T object to stabilize to a new stable baseline, the box of the updated slow average signal is executed. Thereafter, the updated box is interrupted and the slow average signal is re - initialized as described above.

[0127] Furthermore, in this case, if the IR radiation signal T objectIf the baseline change of [signal name] becomes less than or equal to the first baseline change percentage threshold in absolute value before the slow average signal is re-initialized at the end of the clamping, then the value of the detection confidence signal R_CONF is reset to 100% and the update frame of the slow average signal is interrupted.

[0128] If the detection confidence signal R_CONF indicates the presence of user 11 and the IR radiation signal T is detected object has a positive baseline change and becomes greater than the second baseline change percentage threshold in absolute value, then, similar to what was described previously, the value of the slow average signal can be temporarily set (clamped). In this case, as long as the IR radiation signal T object stabilizes to a new stable baseline, the update frame of the slow average signal continues. Thereafter, the update frame is interrupted and the slow average signal is re-initialized as described above. The second baseline change percentage threshold is related to the baseline change threshold, and specifically, it is directly proportional to the baseline change threshold and less than the baseline change threshold (more specifically, it is also less than the first baseline change percentage threshold). For example, the second baseline change percentage threshold is equal to the second percentage of the baseline change threshold (e.g., 50%).

[0129] Furthermore, if in this case, the baseline change of the IR radiation signal T object returns to be less than or equal to the second baseline change percentage threshold in absolute value before the slow average signal is re-initialized at the end of the clamping, then the update frame of the slow average signal is interrupted and the slow average signal is re-initialized.

[0130] Figures 6A to 10F An exemplary case of presence / absence detection performed by the FSM 30’ is shown.

[0131] Specifically, Figures 6A to 10F a time scale is shown on the corresponding horizontal axis, with the time scale referring to the number of samples (also denoted by the reference numeral “sam” hereinafter) obtained since the start of the measurement. For illustrative purposes, considering an ODR equal to 30 Hz, each sample is equivalent to approximately 33 milliseconds (thus 1000 samples are equivalent to 33 seconds). Therefore, hereinafter, the number of samples is referred to as a measure of time because, as described above, these quantities are clearly related to each other by the ODR.

[0132] Furthermore, for each set in Figures 6A to 6F 、 Figures 7A to 7F 、 Figures 8A to 8F 、 Figures 9A to 9F 、 Figures 10A to 10F , the diagram identified by the letter A shows the corresponding example of the IR radiation signal T object , and the diagram identified by the letter B shows the fast average signal T object,fA corresponding example, the illustration identified by the letter C shows the slow average signal T object,s A corresponding example, the illustration identified by the letter D shows a corresponding example of the detection confidence signal R_CONF, the illustration identified by the letter E shows a corresponding example of the state of the FSM 30’, and the illustration identified by the letter F shows a corresponding example of the state signal STATE.

[0133] Specifically, Figures 6A to 6F It shows a situation where a series of different events occur over time.

[0134] For example, approximately in the initial interval 0sam < t < 1100sam, the IR radiation signal T object Is basically stable (its standard deviation is less than the first motion threshold). Therefore, the method is in the initialization state 40 and the detection confidence signal R_CONF, which is initialized to 100%, gradually decreases, causing the state signal STATE to switch from the initial present value to the absent value (at approximately t = 500sam).

[0135] Subsequently, approximately in the interval 1100sam < t < 2200sam, a short and repetitive positive fluctuation of the IR radiation signal T object Occurs (i.e., the standard deviation of the IR radiation signal T object Repeatedly but briefly exceeds the second motion threshold). In this case, it can be seen how the fast average signal very faithfully follows the trend of the IR radiation signal T object While the slow average signal only has a gradual and slow increase, which is basically negligible compared to the change of the fast average signal over time. Due to these positive fluctuations, the method briefly proceeds from the initialization state 40 to the presence check state 42 (at approximately t = 1200sam). Therefore, the detection confidence signal R_CONF is set to 100% and causes the state signal STATE to switch from the absent value to the present value (at approximately t = 1200sam). However, since none of the fluctuations of the IR radiation signal T object Remain high for a period longer than the first threshold time interval, the method returns to the initialization state 40, where the detection confidence signal R_CONF is maintained at 100% in view of the fluctuations.

[0136] At the end of the fluctuations, the detection confidence signal R_CONF gradually decreases again, causing the state signal STATE to switch from the present value to the absent value again (at approximately t = 2900sam).

[0137] Approximately in the interval 3200sam < t < 4100sam, the IR radiation signal T objectA significant and stable baseline change of the positive type. This change is initially greater than the baseline change threshold in absolute value and remains greater than the first baseline change percentage threshold for a period longer than the first threshold time interval. Thus, at approximately t = 3200 sam, the method proceeds to the presence check state 42 and then reaches the final state 46, where it remains unchanged for the remaining time under consideration. Therefore, at approximately t = 3200 sam, the detection confidence signal R_CONF is set to 100% and causes the state signal STATE to switch from the absence value to the presence value. Specifically, in this case, it can be noted how the slow average signal is approximately clamped within the interval 3200 sam < t < 3700 sam and then initialized at approximately t = 3700 sam to the value that the fast average signal has at that moment.

[0138] At approximately t = 4000 sam, the change just discussed ends and thus the detection confidence signal R_CONF rapidly decreases and causes the state signal STATE to switch. Specifically, in this case, it can be noted how the slow average signal T object,s is approximately clamped within the interval 4000 sam < t < 4100 sam and then initialized at approximately t = 4100 sam to the value that the fast average signal T object,f has at that moment.

[0139] Approximately at 5000 sam < t < 6000 sam, a significant and stable baseline change of the positive type of the IR radiation signal T object is repeated again. Thus, changes similar to those of the detection confidence signal R_CONF and the state signal STATE described previously occur.

[0140] Approximately at 7000 sam < t < 8000 sam, a significant and stable baseline change of the positive type of the IR radiation signal T object is repeated again. Additionally, there are short and repeated peaks of the IR radiation signal T object in this interval. The trends of the detection confidence signal R_CONF and the state signal STATE are similar to those described previously for similar cases and thus, as expected, are not affected by these peaks (e.g., due to the posture or movement of user 11).

[0141] As shown approximately in the interval 9000 sam < t < 10000 sam, the switching of the state signal STATE can also occur rapidly in the final state 46 (e.g., approximately every 100 sam).

[0142] Figures 7A to 7FConversely, it shows a situation where user 11 is initially present in the field of view 26, then exits (approximately in 600sam < t < 1100sam), and finally enters again.

[0143] Figures 8A to 8F It shows a situation where user 11 enters and exits the field of view 26 multiple times.

[0144] Figures 9A to 9F It shows a situation where user 11 persists in the field of view 26.

[0145] Figures 10A to 10F It shows a situation where user 11 is continuously absent from the field of view 26.

[0146] By referring to the features of the present disclosure made in accordance with the present disclosure, the advantages provided by the present disclosure are obvious.

[0147] Specifically, compared to known solutions, the detection method 50 and the FSM 30' allow for the detection of the presence / absence of user 11 in the field of view 26 with higher accuracy and reliability, thanks to different types of analysis implemented based on current conditions and available information.

[0148] Specifically, the method allows for the detection of the initial presence / absence of user 11 by means of motion analysis (e.g., at the startup of PC 10), and moreover, subsequent reliable presence / absence detection is performed to transition to a more accurate baseline analysis.

[0149] In addition, the detection confidence information is very useful because it not only indicates the absence / presence state but also indicates the degree of reliability of the detection.

[0150] This detection is not affected by time drift caused by factors such as changes in environmental temperature.

[0151] In addition, compared to different currently known solutions, this detection can be performed with extremely low energy consumption (e.g., if considering known solutions based on ToF sensors, the energy savings reach two orders of magnitude).

[0152] Finally, it is obvious that modifications and variations can be made to the present disclosure described and illustrated herein without thereby departing from the scope of the present disclosure as defined in the appended claims. For example, the different described embodiments can be combined with each other to provide other solutions.

[0153] In addition, the IR sensor 22 can include a sensor control unit 28, and different from the foregoing, the detection method 50 can be performed by the sensor control unit 28 instead of the main control unit 24. For example, the sensor control unit 28 can be a microcontroller or a coprocessor integrated into the IR sensor 22.

[0154] Thus, the FSM module 30 and the evaluation module 32 can be generally included in the control unit of the detection system 20, and the control unit of the detection system 20 can be the main control unit 24 or the sensor control unit 28. Thus, the detection method 50 is implemented by this general control unit of the detection system 20.

[0155] In addition, instead of the same baseline change threshold for both the presence check condition and the absence check condition, a first positive baseline change threshold for the presence check condition and a first negative baseline change threshold for the absence check condition can also be used in the initialization state 40. Thus, two different thresholds can be used. For example, the first positive baseline change threshold is equal to 500 LSB, while the first negative baseline change threshold is equal to 400 LSB.

[0156] Similarly, a first positive baseline change percentage threshold in the presence check state 42 and a first negative baseline change percentage threshold in the absence check state 44 can be used, instead of using the same first baseline change percentage threshold in both cases. For example, the first positive baseline change percentage threshold is equal to a first percentage (e.g., 90%) of the first positive baseline change threshold, while the first negative baseline change percentage threshold is equal to a second percentage (e.g., 90%) of the first negative baseline change threshold.

[0157] In addition, a second positive baseline change threshold for determining the presence of the user 11 and a second negative baseline change threshold for determining the absence of the user 11 can be used in the final state 46, instead of using the same baseline change threshold in both cases. For example, the second positive baseline change threshold is equal to 1000 LSB, while the second negative baseline change threshold is equal to 800 LSB.

[0158] In one embodiment, a detection system (20) for detecting the presence or absence of a user (11), the detection system (20) comprising: an infrared IR radiation sensor (22), the infrared IR radiation sensor (22) being configured to detect IR radiation emitted by the user (11) when the user (11) is in the field of view (26) of the IR radiation sensor (22); and a control unit (24; 28), the control unit (24; 28) being configured to receive an IR radiation signal (T object ) from the IR radiation sensor (22), the IR radiation signal indicating the intensity of the IR radiation emitted by the user (11) when the user (11) is in the field of view (26), the control unit (24; 28) being configured to: determine the presence or absence of the user (11) in the field of view (26) by means of motion analysis performed on the IR radiation signal (T object ) ; based on the IR radiation signal (T object) to verify whether a presence check condition or an absence check condition is detected; if the presence check condition is detected, then based on the IR radiation signal (T object ) to verify whether the presence of the user (11) in the field of view (26) is confirmed, or, if the absence check condition is detected, then based on the IR radiation signal (T object ) to verify whether the absence of the user (11) in the field of view (26) is confirmed; if the presence or absence of the user (11) in the field of view (26) is confirmed, then based on the previously confirmed information on the presence or absence of the user (11) in the field of view (26), continue to determine the presence or absence of the user (11) in the field of view (26) by performing a baseline analysis on the IR radiation signal (T object ).

[0159] In one embodiment, the control unit (24; 28) includes a finite state machine FSM module (30), and the finite state machine FSM module is configured to receive the IR radiation signal (T object ) and can generate a detection confidence signal (R_CONF), and the detection confidence signal (R_CONF) indicates the detection confidence of the presence of the user (11) in the field of view (26).

[0160] In one embodiment, the FSM module (30) is configured to implement an FSM (30'), and the FSM (30') includes: an initialization state (40), in which the presence or absence of the user (11) in the field of view (26) is determined by motion analysis, and it is verified whether a presence check condition or an absence check condition is detected; a presence check state (42), in which if the presence check condition is detected, then the presence check state (42) is reached, and in which it is verified whether the presence of the user (11) in the field of view (26) is confirmed; an absence check state (44), in which if the absence check condition is detected, then the absence check state (44) is reached, and in which it is verified whether the absence of the user (11) in the field of view (26) is confirmed; and a final state (46), in which if the presence or absence of the user (11) in the field of view (26) is confirmed, then the final state (46) is reached, and in which the presence or absence of the user (11) in the field of view (26) is continued to be determined by baseline analysis.

[0161] In one embodiment, the control unit (24; 28) includes an evaluation module (32) which is coupled to the FSM module (30) and is configured to receive a detection confidence signal (R_CONF) and to generate a state signal (STATE) and a state confidence signal (S_CONF) based on the detection confidence signal (R_CONF), the state signal (STATE) indicating the presence or absence state of the user (11) in the field of view (26), and the state confidence signal (S_CONF) indicating the confidence in the detected presence or absence state of the user (11) in the field of view (26).

[0162] In one embodiment, the IR radiation sensor (22) includes a "thermal MOS" TMOS.

[0163] In one embodiment, the control unit (24; 28) is either the main control unit (24) of the detection system (20) or the sensor control unit (28). The main control unit (24) of the detection system (20) is external to the IR radiation sensor (22) and is operatively coupled to the IR radiation sensor (22) to receive the IR radiation signal (T object ), and the sensor control unit (28) is within the IR radiation sensor (22) and is configured to receive the IR radiation signal (T object ).

[0164] In one embodiment, the electronic device (10) is usable by a user (11) and includes a detection system (20) for detecting the presence or absence of the user (11). The detection system (20) includes: an infrared IR radiation sensor (22) configured to detect IR radiation emitted by the user (11) when the user (11) is in the field of view (26) of the IR radiation sensor (22); and a control unit (24; 28) configured to receive an IR radiation signal (T object ) from the IR radiation sensor (22), the IR radiation signal indicating the intensity of the IR radiation emitted by the user (11) when the user (11) is in the field of view (26). The control unit (24; 28) is configured to: determine the presence or absence of the user (11) in the field of view (26) by performing motion analysis on the IR radiation signal (T object ); verify whether a presence check condition or an absence check condition is detected based on the IR radiation signal (T object ); if the presence check condition is detected, verify whether the presence of the user (11) in the field of view (26) is confirmed based on the IR radiation signal (T object ), or, if the absence check condition is detected, verify whether the absence of the user (11) in the field of view (26) is confirmed based on the IR radiation signal (T object) to verify whether the non - existence of the user (11) in the field of view (26) is confirmed; if the existence or non - existence of the user (11) in the field of view (26) is confirmed, then based on the previously confirmed information about the existence or non - existence of the user (11) in the field of view (26), by means of a baseline analysis performed on the IR radiation signal (T object ) continue to determine the existence or non - existence of the user (11) in the field of view (26).

[0165] In one embodiment, the electronic device is configured to have one or more functions, specifically a proximity wake - up function and a leave - lock function, and the one or more functions can be controlled by means of the determined information about the existence or non - existence of the user (11) in the field of view (26).

[0166] In this embodiment, a detection method (50) for detecting the existence or non - existence of the user (11) is performed by means of a detection system (20). The detection system includes: an infrared (IR) radiation sensor (22), which is configured to detect the IR radiation emitted by the user (11) when the user (11) is in the field of view (26) of the IR radiation sensor (22); and a control unit (24; 28), which is configured to receive an IR radiation signal (T object ) from the IR radiation sensor (22), and the IR radiation signal indicates the intensity of the IR radiation emitted by the user (11) when the user (11) is in the field of view (26). The detection method (50) includes the following steps: by the control unit (24; 28): determine the existence or non - existence of the user (11) in the field of view (26) by means of a motion analysis performed on the IR radiation signal (T object ); based on the IR radiation signal (T object ), verify whether an existence check condition or a non - existence check condition is detected; if an existence check condition is detected, then based on the IR radiation signal (T object ), verify whether the existence of the user (11) in the field of view (26) is confirmed, or, if a non - existence check condition is detected, then based on the IR radiation signal (T object ), verify whether the non - existence of the user (11) in the field of view (26) is confirmed; if the existence or non - existence of the user (11) in the field of view (26) is confirmed, then based on the previously confirmed information about the existence or non - existence of the user (11) in the field of view (26), continue to determine the existence or non - existence of the user (l1) in the field of view (26) by means of a baseline analysis performed on the IR radiation signal (T object ).

[0167] In one embodiment, determining the presence or absence of a user (11) includes generating a detection confidence signal (R_CONF) that indicates the detection confidence of the presence of the user (11) in the field of view (26).

[0168] In one embodiment, determining (S10) the presence or absence of a user (11) in the field of view (26) by means of motion analysis includes: if the standard deviation of the IR radiation signal (T object ) is less than a first motion threshold, reducing the confidence value of the detection confidence signal (R_CONF) at a decreasing rate, or, if the standard deviation of the IR radiation signal (T object ) is greater than a second motion threshold that is larger than the first motion threshold, increasing the confidence value of the detection confidence signal (R_CONF) at an increasing rate.

[0169] In one embodiment, the decreasing rate is defined or fixed, and the increasing rate is variable and equal to the sum of the fixed and pre-defined rate and the rate that varies according to the standard deviation of the IR radiation signal (T object ).

[0170] In one embodiment, verifying (S12, S14) whether a presence check condition or an absence check condition is detected includes: verifying (S12) whether a presence / absence check condition is detected; and if a presence / absence check condition is detected, verifying (S14) whether the detected presence / absence check condition indicates a presence check or an absence check, where verifying (S12) whether a presence / absence check condition is detected includes: calculating the baseline change of the IR radiation signal (T object ) and comparing the baseline change of the IR radiation signal (T object ) with a baseline change threshold, where the baseline change of the IR radiation signal (T object ) is correlated with the difference between the fast average signal and the slow average signal of the IR radiation signal (T object ), and the fast average signal and the slow average signal are calculated by filtering the IR radiation signal (T object ) using corresponding filters with different time constants, where if the baseline change of the IR radiation signal (T object ) is greater than the baseline change threshold in absolute value, a presence / absence check condition is detected, and where verifying (S14) whether the detected presence / absence check condition indicates a presence check or an absence check includes: verifying whether the baseline change of the IR radiation signal (T object ) is positive or negative, and if the baseline change of the IR radiation signal (T object ) is positive, the detected presence / absence check condition indicates a presence check, and if the baseline change of the IR radiation signal (Tobject ) has a negative baseline change, the detected presence / absence check condition indicates the absence of the check.

[0171] In one embodiment, verifying whether the presence or absence of the verified user (11) in the field of view (26) is confirmed includes: verifying that the IR radiation signal (T object ) has a baseline change that remains greater than a first baseline change percentage threshold in absolute value over a time interval that is longer than a first threshold time interval or a second threshold time interval, respectively.

[0172] In one embodiment, determining the presence or absence of the user (11) in the field of view (26) by means of baseline analysis includes: verifying that the IR radiation signal (T object ) has a baseline change that is greater than a baseline change threshold in absolute value, where if during the baseline analysis, the IR radiation signal (T object ) has a positive baseline change and is greater than the baseline change threshold in absolute value, the presence of the user (11) in the field of view (26) is determined, and where if during the baseline analysis, the IR radiation signal (T object ) has a negative baseline change and is greater than the baseline change threshold in absolute value, the absence of the user (11) in the field of view (26) is determined.

[0173] In one embodiment, during motion analysis, when the standard deviation of the fast average signal is less than an average update threshold, the value of the slow average signal is updated based on the IR radiation signal (T object ), and when the standard deviation of the fast average signal is greater than or equal to the average update threshold, the value of the slow average signal remains unchanged, and during baseline analysis and after the baseline change of the IR radiation signal (T object ) becomes greater than a second baseline change percentage threshold in absolute value, as long as the standard deviation of the IR radiation signal (T object ) is greater than a clamping threshold, the value of the slow average signal remains unchanged, and when the standard deviation of the IR radiation signal (T object ) becomes equal to or less than the clamping threshold, it is initialized to the value that the fast average signal has at that moment and then resumes updating based on the IR radiation signal (T object ).

[0174] In one embodiment, if a presence check condition or an absence check condition is detected, but the presence or absence of the user (11) in the field of view (26) is not confirmed, the detection method (50) returns to the following step: determining (S10) the presence or absence of the user (11) in the field of view (26) by means of motion analysis performed on the IR radiation signal (T object ).

[0175] In one embodiment, a computer program product may be stored in the control unit (24; 28), and the computer program is designed such that when executed, the control unit (24; 28) is configured to perform the detection method (50) disclosed herein.

[0176] In one embodiment, the device includes an infrared (IR) radiation sensor and control circuitry coupled to the IR radiation sensor. The IR radiation sensor generates an IR radiation signal during operation, and the IR radiation signal indicates the intensity of IR radiation in the field of view of the IR radiation sensor. The control circuitry receives the IR radiation signal during operation, performs motion analysis using the IR radiation signal, and determines whether a user presence check condition is satisfied based on the motion analysis. In response to determining that the user presence check condition is satisfied, the control circuitry uses baseline analysis of the IR radiation signal to determine whether verification criteria related to the user presence check condition are satisfied. In response to determining that the verification criteria related to the user presence check condition are satisfied, the control circuitry generates a control signal indicating the user presence condition based on a detection confidence signal and baseline analysis of the IR radiation signal.

[0177] In one embodiment, the control signal indicating the user presence condition indicates that a user presence in the field of view is detected, or indicates that no user presence in the field of view is detected.

[0178] In one embodiment, the control circuitry implements a finite state machine (FSM) during operation, and the finite state machine generates a detection confidence signal during operation.

[0179] In one embodiment, the FSM implements the following states during operation: an initialization state to determine whether a user presence check condition is satisfied based on motion analysis and to determine whether the user presence check condition is associated with a presence check or an absence check; a presence check state to determine whether verification criteria related to the user presence check condition are satisfied in response to determining that the user presence check condition is associated with a presence check at the initialization state; an absence check state to determine whether verification criteria related to the user presence check condition are satisfied in response to determining that the user presence check condition is associated with an absence check at the initialization state; and a final state to generate a control signal indicating the user presence condition based on a detection confidence signal and baseline analysis of the IR radiation signal in response to determining that the verification criteria related to the user presence check condition are satisfied in the presence check state or in response to determining that the verification criteria related to the user presence check condition are satisfied in the absence check state.

[0180] In one embodiment, the control circuitry generates a status signal and a status confidence signal during operation based on a detection confidence signal, the status signal indicating that a user presence has been detected in the field of view or indicating that no user presence has been detected in the field of view, and the status confidence signal indicating the confidence in the detected status of the status signal.

[0181] In one embodiment, the IR radiation sensor includes a thermal MOS (TMOS) sensor.

[0182] In one embodiment, the device includes a host system that is coupled to the IR radiation sensor and includes control circuitry.

[0183] In one embodiment, the device includes an integrated circuit that includes an IR radiation sensor and control circuitry.

[0184] In one embodiment, the system includes an infrared (IR) radiation sensor and control circuitry. The IR radiation sensor detects IR radiation in the field of view of the IR radiation sensor during operation. The control circuitry receives the IR radiation signal during operation, performs motion analysis using the IR radiation signal, and determines whether a user presence check condition is satisfied based on the motion analysis. In response to determining that the user presence check condition is satisfied, the control circuitry uses baseline analysis of the IR radiation signal to determine whether verification criteria related to the user presence check condition are satisfied. In response to determining that the verification criteria related to the user presence check condition are satisfied, the control circuitry generates one or more system control signals indicating a user presence condition based on the detection confidence signal and baseline analysis of the IR radiation signal.

[0185] In one embodiment, one or more system control signals control the proximity wake-up function and the departure lock function of the system.

[0186] In one embodiment, the control circuitry includes circuitry that includes an IR radiation sensor and a host processor coupled to the IR radiation sensor.

[0187] In one embodiment, the method includes: using an infrared (IR) radiation sensor to generate an IR radiation signal that indicates the intensity of IR radiation in the field of view of the IR radiation sensor; using the IR radiation signal to perform motion analysis; based on the motion analysis, determining whether a user presence check condition is satisfied; in response to determining that the user presence check condition is satisfied, using baseline analysis of the IR radiation signal to determine whether verification criteria related to the user presence check condition are satisfied; in response to determining that the verification criteria related to the user presence check condition are satisfied, generating a control signal indicating a user presence condition based on the detection confidence signal and baseline analysis of the IR radiation signal.

[0188] In one embodiment, a control signal indicating the presence of a condition for a user indicates that a user presence in the field of view is detected, or indicates that no user presence in the field of view is detected.

[0189] In one embodiment, the method includes implementing a finite state machine (FSM) to generate a detection confidence signal.

[0190] In one embodiment, the FSM has: an initialization state to determine, based on motion analysis, whether a user presence check condition is satisfied and whether the user presence check condition is associated with a presence check or an absence check; a presence check state to determine, in response to determining at the initialization state that the user presence check condition is associated with a presence check, whether verification criteria related to the user presence check condition are satisfied; an absence check state to determine, in response to determining at the initialization state that the user presence check condition is associated with an absence check, whether verification criteria related to the user presence check condition are satisfied; and a final state to generate, in response to determining at the presence check state that the verification criteria related to the user presence check condition are satisfied, or in response to determining at the absence check state that the verification criteria related to the user presence check condition are satisfied, a control signal indicating the user presence condition based on the detection confidence signal and a baseline analysis of the IR radiation signal.

[0191] In one embodiment, the method includes: generating a status signal based on the detection confidence signal, the status signal indicating that a user presence in the field of view is detected or indicating that no user presence in the field of view is detected; and generating a status confidence signal, the status confidence signal indicating the confidence in the detected status of the status signal.

[0192] In one embodiment, the detection confidence signal indicates the detection confidence of a user presence in the field of view.

[0193] In one embodiment, the method includes: if the standard deviation of the IR radiation signal is less than a first motion threshold, reducing the confidence value of the detection confidence signal at a decreasing rate; and if the standard deviation of the IR radiation signal is greater than a second motion threshold that is larger than the first motion threshold, increasing the confidence value of the detection confidence signal at an increasing rate.

[0194] In one embodiment, the decreasing rate is fixed and the increasing rate is variable.

[0195] In one embodiment, the increase rate is determined based on the sum of a threshold rate and a rate that varies according to the standard deviation of the IR radiation signal. In one embodiment, the method includes: calculating a baseline change of the IR radiation signal and comparing the baseline change of the IR radiation signal with a baseline change threshold, wherein the baseline change of the IR radiation signal is related to the difference between a fast average signal and a slow average signal of the IR radiation signal, and the fast average signal and the slow average signal are calculated by filtering the IR radiation signal using corresponding filters having different time constants; if the baseline change of the IR radiation signal is greater than the baseline change threshold in absolute value, determining that a user presence check condition is satisfied; in response to determining that the user presence check condition is satisfied, determining whether the baseline change of the IR radiation signal is positive or negative; in response to determining that the baseline change of the IR radiation signal is positive, determining that the user presence check condition indicates a presence check; and in response to determining that the baseline change of the IR radiation signal is negative, determining that the user presence check condition indicates an absence check.

[0196] In one embodiment, determining whether a verification criterion related to the user presence check condition is satisfied includes: in response to the user presence check condition indicating a presence check: determining whether the baseline change signal remains greater than a first baseline change percentage threshold in absolute value for a time interval longer than a first threshold time interval; and in response to determining that the baseline change signal remains greater than the first baseline change percentage threshold in absolute value for a time interval longer than the first threshold time interval, determining that the verification criterion related to the user presence check condition is satisfied; and in response to the user presence check condition indicating an absence check, determining whether the baseline change signal remains greater than a second baseline change percentage threshold in absolute value for a time interval longer than a second threshold time interval; and in response to determining that the baseline change signal remains greater than the second baseline change percentage threshold in absolute value for a time interval longer than the second threshold time interval, determining that the verification criterion related to the user presence check condition is satisfied.

[0197] In one embodiment, during motion analysis, when the standard deviation of the fast average signal is less than an average update threshold, the value of the slow average signal is updated based on the IR radiation signal, and when the standard deviation of the fast average signal is greater than or equal to the average update threshold, the value of the slow average signal remains unchanged, and during baseline analysis, when the baseline change of the IR radiation signal becomes greater than a second baseline change percentage threshold in absolute value, as long as the standard deviation of the IR radiation signal is greater than a clamping threshold, the value of the slow average signal remains unchanged, and when the standard deviation of the IR radiation signal becomes equal to or less than the clamping threshold, the slow average signal is initialized to the value of the fast average signal.

[0198] In one embodiment, in response to determining that verification criteria related to a user presence check condition are not met in a presence check state or an absence check state, the FSM returns to an initialization state.

[0199] In one embodiment, the content of a non-transitory computer-readable medium configures processing circuitry to perform a method that includes: performing motion analysis using an infrared (IR) radiation signal; determining, based on the motion analysis, whether a user presence check condition is met; in response to determining that the user presence check condition is met, determining, using baseline analysis of the IR radiation signal, whether verification criteria related to the user presence check condition are met; and in response to determining that the verification criteria related to the user presence check condition are met, generating a control signal indicative of the user presence condition based on a detection confidence signal and baseline analysis of the IR radiation signal.

[0200] In one embodiment, the content includes instructions executable by the processing circuitry

[0201] Some embodiments may take the form of a computer program product or include a computer program product. For example, according to one embodiment, a computer-readable medium is provided that includes a computer program that is adapted to execute one or more of the methods or functions described above. The medium may be a physical storage medium such as, for example, a read-only memory (ROM) chip, or a magnetic disk such as a digital versatile disk (DVD-ROM), a compact disk (CD-ROM), a hard disk, a memory, a network, or a portable media item that will be read via an appropriate drive or via an appropriate connection, including other relevant codes encoded in one or more barcodes or stored on one or more such computer-readable media and readable by an appropriate reader device.

[0202] In addition, in some embodiments, some or all of the methods and / or functions may be implemented or provided in other ways, such as at least partially in firmware and / or hardware, including but not limited to one or more application specific integrated circuits (ASICs), digital signal processors, discrete circuitry, logic gates, standard integrated circuits, controllers (e.g., by executing appropriate instructions and including microcontrollers and / or embedded controllers), field programmable gate arrays (FPGAs), complex programmable logic devices (CPLDs), etc., as well as devices employing RFID technology, and various combinations thereof.

[0203] The various embodiments described above may be combined to provide other embodiments. Aspects of the embodiments may be modified as needed to incorporate concepts from various patents, applications, and publications to provide other embodiments.

[0204] These and other changes may be made to the embodiments in light of the above detailed description. In general, in the following claims, the terms used should not be construed so as to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments and the full scope of equivalents to such claims. Accordingly, the claims are not limited by the disclosure.

Claims

1. An apparatus, comprising: an infrared (IR) radiation sensor that generates, in operation, an IR radiation signal indicative of an intensity of IR radiation in a field of view of the IR radiation sensor; and control circuitry coupled to the IR radiation sensor, wherein the control circuitry, in operation: receives the IR radiation signal; performs motion analysis using the IR radiation signal; determines whether a user presence check condition is satisfied based on the motion analysis; in response to determining that the user presence check condition is satisfied, determines whether verification criteria associated with the user presence check condition are satisfied using baseline analysis of the IR radiation signal; in response to determining that the verification criteria associated with the user presence check condition are satisfied, generates a control signal indicative of a user presence condition based on a detection confidence signal and the baseline analysis of the IR radiation signal.

2. The apparatus according to claim 1, wherein the control signal indicative of the user presence condition indicates that a user presence is detected in the field of view or indicates that no user presence is detected in the field of view.

3. The apparatus according to claim 2, wherein the control circuitry implements, in operation, a finite state machine (FSM) that generates, in operation, the detection confidence signal.

4. The apparatus according to claim 3, wherein the FSM implements, in operation, the following states: an initialization state to determine whether the user presence check condition is satisfied based on the motion analysis and to determine whether the user presence check condition is associated with a presence check or an absence check; a presence check state to determine whether verification criteria associated with the user presence check condition are satisfied in response to determining at the initialization state that the user presence check condition is associated with a presence check; an absence check state to determine whether verification criteria associated with the user presence check condition are satisfied in response to determining at the initialization state that the user presence check condition is associated with an absence check; and a final state to generate the control signal indicative of the user presence condition based on the detection confidence signal and the baseline analysis of the IR radiation signal in response to determining that the verification criteria associated with the user presence check condition are satisfied in the presence check state or in response to determining that the verification criteria associated with the user presence check condition are satisfied in the absence check state.

5. The apparatus according to claim 1, wherein the control circuitry generates, in operation, a status signal and a status confidence signal based on the detection confidence signal, the status signal indicating that a user presence is detected in the field of view or indicating that no user presence is detected in the field of view, and the status confidence signal indicating a confidence in the detected status of the status signal.

6. The apparatus according to claim 1, wherein the IR radiation sensor includes a thermal MOS (TMOS) sensor.

7. The apparatus according to claim 1, comprising a host system, the host system being coupled to the IR radiation sensor and including the control circuitry.

8. The apparatus according to claim 1, comprising an integrated circuit, the integrated circuit including the IR radiation sensor and the control circuitry.

9. A system, comprising: an infrared (IR) radiation sensor that, in operation, detects IR radiation in a field of view of the IR radiation sensor; and control circuitry that, in operation: receives the IR radiation signal; uses the IR radiation signal to perform motion analysis; determines whether a user presence check condition is satisfied based on the motion analysis; in response to determining that the user presence check condition is satisfied, determines whether verification criteria related to the user presence check condition are satisfied using baseline analysis of the IR radiation signal; in response to determining that the verification criteria related to the user presence check condition are satisfied, generates one or more system control signals based on a detection confidence signal and the baseline analysis of the IR radiation signal, the one or more system control signals indicating a user presence condition.

10. The system according to claim 9, wherein the one or more system control signals control a proximity wake-up function and a leave-lock function of the system.

11. The system according to claim 9, wherein the control circuitry includes circuitry including the IR radiation sensor and a host processor, the host processor being coupled to the IR radiation sensor.

12. A method, comprising: using an infrared (IR) radiation sensor to generate an IR radiation signal that indicates an intensity of IR radiation in a field of view of the IR radiation sensor; using the IR radiation signal to perform motion analysis; determining whether a user presence check condition is satisfied based on the motion analysis; in response to determining that the user presence check condition is satisfied, determining whether verification criteria related to the user presence check condition are satisfied using baseline analysis of the IR radiation signal; in response to determining that the verification criteria related to the user presence check condition are satisfied, generating a control signal based on a detection confidence signal and the baseline analysis of the IR radiation signal, the control signal indicating a user presence condition.

13. The method according to claim 12, wherein the control signal indicating a user presence condition indicates that a user presence is detected in the field of view or indicates that a user presence is not detected in the field of view.

14. The method according to claim 13, comprising: Implementing a finite state machine (FSM) to generate the detection confidence signal.

15. The method according to claim 14, wherein the FSM has: an initialization state to determine whether the user presence check condition is satisfied based on the motion analysis and to determine whether the user presence check condition is associated with a presence check or an absence check. There is a presence check state to determine whether the verification criteria related to the user presence check condition are met in response to determining that the user presence check condition is associated with a presence check at the initialization state; There is an absence check state to determine whether the verification criteria related to the user presence check condition are met in response to determining that the user presence check condition is associated with an absence check at the initialization state; and A final state to generate the control signal indicating the user presence condition based on the detection confidence signal and the baseline analysis of the IR radiation signal in response to determining that the verification criteria related to the user presence check condition are met in the presence check state or in response to determining that the verification criteria related to the user presence check condition are met in the absence check state.

16. The method according to claim 12, comprising: Generating a status signal based on the detection confidence signal, the status signal indicating that a user presence in the field of view is detected or indicating that no user presence in the field of view is detected; and Generating a status confidence signal, the status confidence signal indicating the confidence in the detected status of the status signal.

17. The method according to claim 12, wherein the detection confidence signal indicates the detection confidence of detecting a user presence in the field of view.

18. The method according to claim 17, comprising: If the standard deviation of the IR radiation signal is less than a first motion threshold, reducing the confidence value of the detection confidence signal at a decreasing rate; and If the standard deviation of the IR radiation signal is greater than a second motion threshold, increasing the confidence value of the detection confidence signal at an increasing rate, the second motion threshold being greater than the first motion threshold.

19. The method according to claim 18, wherein the decreasing rate is fixed and the increasing rate is variable.

20. The method according to claim 19, wherein the increasing rate is determined based on the sum of a threshold rate and a rate that can vary according to the standard deviation of the IR radiation signal.

21. The method according to claim 12, comprising: Calculating a baseline change of the IR radiation signal and comparing the baseline change of the IR radiation signal with a baseline change threshold, wherein the baseline change of the IR radiation signal is related to the difference between a fast average signal and a slow average signal of the IR radiation signal, the fast average signal and the slow average signal being calculated by filtering the IR radiation signal using corresponding filters with different time constants; If the absolute value of the baseline change of the IR radiation signal is greater than the baseline change threshold, determining that the user presence check condition is met; In response to determining that the user presence check condition is met, determining whether the baseline change of the IR radiation signal is positive or negative; In response to determining that the baseline change of the IR radiation signal is positive, determining that the user presence check condition indicates a presence check; and In response to determining that the baseline change of the IR radiation signal is negative, determine that the user presence check condition indicates the absence of a check.

22. The method according to claim 21, wherein determining whether verification criteria related to the user presence check condition are met includes: In response to the user presence check condition indicating a presence check, Determine whether the baseline change signal remains greater than a first baseline change percentage threshold in absolute value for a time interval longer than a first threshold time interval; And In response to determining that the baseline change signal remains greater than the first baseline change percentage threshold in absolute value for a time interval longer than the first threshold time interval, determine that the verification criteria related to the user presence check condition are met; and In response to the user presence check condition indicating an absence check: Determine whether the baseline change signal remains greater than a second baseline change percentage threshold in absolute value for a time interval longer than a second threshold time interval; and In response to determining that the baseline change signal remains greater than the second baseline change percentage threshold in absolute value for a time interval longer than the second threshold time interval, determine that the verification criteria related to the user presence check condition are met.

23. The method according to claim 21, wherein, During the motion analysis, the value of the slow average signal is updated based on the IR radiation signal when the standard deviation of the fast average signal is less than an average update threshold, and remains unchanged when the standard deviation of the fast average signal is greater than or equal to the average update threshold, and wherein, during the baseline analysis, when the baseline change of the IR radiation signal becomes greater than a second baseline change percentage threshold in absolute value, as long as the standard deviation of the IR radiation signal is greater than a clamping threshold, the value of the slow average signal remains unchanged, and when the standard deviation of the IR radiation signal becomes equal to or less than the clamping threshold, the slow average signal is initialized to the value of the fast average signal.

24. The method according to claim 15, wherein In response to determining that the verification criteria related to the user presence check condition are not met in the presence check state or the absence check state, the FSM returns to the initialization state.

25. A non-transitory computer-readable medium having content that configures a processing circuit to perform a method, the method including: Performing motion analysis using an infrared (IR) radiation signal; Determining whether a user presence check condition is met based on the motion analysis; In response to determining that the user presence check condition is met, using baseline analysis of the IR radiation signal to determine whether verification criteria related to the user presence check condition are met; In response to determining that the verification criteria related to the user presence check condition are met, generating a control signal based on a detection confidence signal and the baseline analysis of the IR radiation signal, the control signal indicating a user presence condition.

26. The non-transitory computer-readable medium according to claim 25, wherein the content includes instructions that are executable by the processing circuitry.

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