BOUT, Marcelis (High Tech Campus Building 44, AE Eindhoven, NL-5656, NL)
NIESSEN, Rogier, Adrianus, Henrica (High Tech Campus Building 44, AE Eindhoven, NL-5656, NL)
U.S. PHILIPS CORPORATION (3000 Minuteman Road Building 1, MS 109Andover, Massachusetts, 01810, US)
PASVEER, Willem, Franke (High Tech Campus Building 44, AE Eindhoven, NL-5656, NL)
BOUT, Marcelis (High Tech Campus Building 44, AE Eindhoven, NL-5656, NL)
NIESSEN, Rogier, Adrianus, Henrica (High Tech Campus Building 44, AE Eindhoven, NL-5656, NL)
| CLAIMS: 1. A tracking system in areas with light dispersive media, comprising: a transducer array (20) located at a designated area and configured to perform an ultrasonic sweep of the area, the transducer array being capable of determining a presence and position of beings or objects in the area in accordance with the ultrasonic sweep; a controller (14) configured to receive results of the sweep and create a map (30) of the area; and at least one action module (25) configured to receive a control signal from the controller, the control signal being transmitted to the at least one action module in accordance with density information plotted on the map such that the at least one action module is activated by the control signal in accordance with the map. 2. The system as recited in claim 1, wherein the transducer array (20) includes a thin-film piezoelectric membrane transducer array. 3. The system as recited in claim 1, wherein the transducer array (20) includes a plurality of transducers configured in an array having a pitch between transducers such that operating frequencies are between about 30 KHz and about 450 KHz. 4. The system as recited in claim 3, wherein the pitch is between about 200 micrometers and about 4000 micrometers. 5. The system as recited in claim 1, wherein the at least one action module (25) includes one of a speaker, an alarm and a lighting source. 6. The system as recited in claim 1, wherein the controller (14) and the action modules (25) communicate wirelessly. 7. The system as recited in claim 1, wherein the sweep measures population density in the area. 8. The system as recited in claim 7, wherein the map includes a population density map of the area. 9. The system as recited in claim 8, wherein the controller (14) activates the at least one action module to provide an action in an area having a highest population density. 10. The system as recited in claim 8, wherein the controller (14) deactivates the at least one action module if a presence of people is not detected. 11. The system as recited in claim 1 , wherein the transducer array (20) is configured to perform the scan when triggered by an event. 12. A tracking system in areas with light dispersive media, comprising: a transducer array (20) located at a designated area and configured to perform an ultrasonic sweep of the area, the transducer array being capable of determining a presence and position of people in the area where light through air in the area is at least partially attenuated due to light dispersive matter; a controller (14) configured to receive results of the sweep and create a map (30) of the area including a number of people and their location in the area; and a plurality of modules (25) configured to be responsive to a control signal from the controller, the control signal being selectively transmitted to the modules in accordance with the number of people and their location in the area such that the modules are activated when the number of people at a location exceeds a threshold level. 13. The system as recited in claim 12, wherein the transducer array (20) includes a thin-film piezoelectric membrane transducer array. 14. The system as recited in claim 12, wherein the modules (25) include at least one of a speaker, an alarm, a camera and a lighting source. 15. The system as recited in claim 12, wherein the controller (14) and the modules (25) communicate wirelessly. 16. The system as recited in claim 12, wherein the sweep measures population density in the area. 17. The system as recited in claim 12, wherein the map (30) includes a population density map of the area. 18. The system as recited in claim 12, wherein the controller (14) activates the modules to provide an action in an area having a highest population density. 19. The system as recited in claim 12, wherein the controller (14) deactivates the at least one action module if a presence of people is not detected. 20. The system as recited in claim 12, wherein the transducer array (20) is configured to perform the scan when triggered by an event. 21. A method for tracking activity in the presence of light dispersive media, comprising: ultrasonically sweeping (502) an area where light through air in the area is at least partially attenuated due to the light dispersive media by employing an ultrasonic transducer array to scan the area to determine one of activity and presence of beings or objects; mapping (504) the one of activity and presence in the area to create an activity map; and selectively activating (510) action modules throughout the area in accordance with the activity map. 22. The method as recited in claim 21, wherein the selectively activating (510) action modules includes activating the action modules when a number of people exceeds a threshold in a given portion of the area. 23. The device as recited in claim 21, wherein the action modules include at least one of a speaker, an alarm, a camera and a lighting source. 24. The device as recited in claim 21, wherein the light dispersive media includes one of smoke, mining dust and fog. 25. The device as recited in claim 21, wherein the sweep measures population density in the area. |
Related applications and patents are U.S. provisional application no.
61/095685, filed September 10, 2008, "System, Device and Method for Emergency Presence Detection," which was filed [insert filing date] as PCT/IB [insert application serial number] (applicants' docket no. 010950) and PCT/IB 2008/052610, filed June 30, 2008, "Thin Film Detector for Presence Detection" (applicant's docket no. 008783). This disclosure relates to presence detection and tracking, and more particularly to a system, method and device configured to scan an area to detect and track the presence of humans, animals or objects in the area and provide an action in accordance with the presence detected.
Tracking people can be done well using infrared technology (which also works well in darkness). However, infrared tracking suffers in a highly dispersive media, such as in smoke filled rooms, fog, or areas with other dispersive particulates. Security systems and the like that depend on infrared to track people are often ineffective in smoky or dispersive media. When the environment is filled with smoke (or partially filled) infrared technology is no longer capable of tracking people. In accordance with the present principles, ultrasound technology is employed as a tracking mechanism for objects, and in particular, people or animals. In one embodiment, tracking is performed in a smoky or dispersive media, such as a disco. The tracking mechanism may be employed to adjust the lighting or perform other actions depending on the position of people and possibly on the number of people at a location. This may be performed even in a smoke-filled location or environment. The tracking mechanism may also be useful in directing the spreading of people by providing an indication of high density areas where there may be too many people. In another embodiment, the tracking mechanism may be employed to set an alarm if there are too many people in a given area. For example, an indication may be provided if the number of people in a room or building exceeds the maximum permitted by a fire code or the like. Currently, lighting for a stage show or in a disco is pre-programmed (or adjusted manually) to sweep through space. In one useful embodiment, by using ultrasound technology, it is possible to obtain information about position of people, which can be employed to automatically direct the lighting in all circumstances.
A tracking system in areas where light dispersive media is present includes a transducer array located at a designated area and configured to perform an ultrasonic sweep of the area. The transducer array is capable of determining a presence and position of people, animals or objects in the area in accordance with the ultrasonic sweep. A controller is configured to receive results of the sweep and create a map of the area. An action module is configured to receive a control signal from the controller. The control signal is transmitted to the action module in accordance with density information plotted on the map such that the at least one action module is activated by the control signal in accordance with the map.
A method for tracking activity in the presence of light dispersive media includes ultras onically sweeping an area where light through air in the area is at least partially attenuated due to particulate matter by employing an ultrasonic transducer array to scan the area to determine presence or activity. The presence or activity in the area is mapped to create an activity map. Action modules are selectively activated throughout the area in accordance with the activity map.
These and other objects, features and advantages of the present disclosure will become apparent from the following detailed description of illustrative embodiments thereof, which is to be read in connection with the accompanying drawings. This disclosure will present in detail the following description of preferred embodiments with reference to the following figures wherein:
FIG. 1 is a block diagram illustratively depicting a system for tracking activity/presence to determine equipment to be employed under given conditions in accordance with one embodiment;
FIG. 2 is a diagram showing a transducer device for transmitting and receiving ultrasonic energy for determining activity in an area;
FIG. 3 is a block diagram showing an array of transducers according to one embodiment; FIGS. 4A-4B show a transducer having electrodes on one side of a piezoelectric material according to one embodiment of the present system; and
FIG. 5 is a block/flow diagram showing a system/method for detecting and tracking activity using ultrasonic waves.
The present disclosure describes a presence detection system, device and method in terms of an ultrasonic tracking system. It should be understood that such an application is merely illustrative, and the present principles find utility in a plurality of applications and scenarios. For example, the presence detection/tracking system may be employed on boats or ships, in vehicles, in mining operations or other scenarios were people or pets need to be located despite being in a light dispersive environment. In one embodiment, a presence detection device is implemented on a semiconductor chip, printed circuit board or other substrate.
In particularly useful embodiments, a device is presented which is able to detect persons in a room while the room is filled with smoke, fog, dry ice fog, coal dust, airborne particulates, etc. The detection of people is employed as criteria for moving or adjusting lights or other fixtures. An ultrasound detection sweep may be performed through the room or location to scan for persons or objects present in the room or environment. The result of the measurement is communicated to a central processor or controller and employed to make decisions on environmental controls such as, but not limited to lighting, temperature, ventilation, people density, maximum occupancy, etc. Communication to and from the central processor may be provided either wirelessly or via a wired link.
The functions of the various elements shown in the figures can be provided through the use of dedicated hardware as well as hardware capable of executing software in association therewith. When provided by a processor, the functions can be provided by a single dedicated processor, by a single shared processor, or by a plurality of individual processors, some of which can be shared. Moreover, explicit use of the term "processor" or "controller" should not be construed to refer exclusively to hardware capable of executing software, and can implicitly include, without limitation, digital signal processor ("DSP") hardware, read-only memory ("ROM") for storing software, random access memory ("RAM"), and non-volatile storage. Moreover, all statements herein reciting principles, aspects, and embodiments of the invention, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents as well as equivalents developed in the future (i.e., any elements developed that perform the same function, regardless of structure). Thus, for example, it will be appreciated by those skilled in the art that the block diagrams presented herein represent conceptual views of illustrative system components and/or circuitry embodying the principles of the invention. Similarly, it will be appreciated that any flow charts, flow diagrams and the like represent various processes which may be substantially represented in computer readable media and so executed by a computer or processor, whether or not such computer or processor is explicitly shown. The elements depicted in the FIGS, may be implemented in various combinations of hardware and provide functions which may be combined in a single element or multiple elements.
It should be understood that the illustrative example of a disco is not limiting and other environments can benefit from such tracking devices. For example, manufacturing plants, coal or other mines, construction sites, ships, high altitudes or other locations where fog is present, etc.
Referring now to the drawings in which like numerals represent the same or similar elements and initially to FIG. 1, a system 100 provides for detection of humans, animals or objects 16 in a monitored area 10. The area 10 may include a room, a building, a vehicle, a mine cavern, an enclosed area or other monitored area. In one embodiment, a transducer or sensor array 20 is connected to a processor or controller 14. When the system 100 is triggered or activated, the transducer array 20 begins to scan the area 10 looking for people 16 (objects, pets, etc.) that may be present. The transducer array 20 preferably includes an array of thin-film ultra-sound transducers which are able to perform a full scan of the room 10 to check for the presence of people, etc. and determine their number and/or location. An illustrative example of such a thin-film ultra-sound transducer will be described below. An ultra-sonic solution is particularly useful when the room is completely or partially filled with smoke or other light dispersive media 23. A power supply(s) 22 is needed to power the transducer 20 and processor 14. In one embodiment, the transducer array 20 and processor 14 may include their own battery or back-up energy system.
The transducer array 20 sends out ultrasonic signals 11 and maps the population density of the room. This mapping is employed as feedback to configure or reconfigure action modules 25. Modules 25 may include lights, cameras, dry ice machines, speakers, pyrotechnics or any other devices or mechanisms that are desired to be controlled based upon the human behavior, presence or activity within the environment 10 being monitored. In one embodiment, an ultrasound scanning device 20 is integrated with the lighting fixture or module 25 and based on the input from the sensor 20 the lighting is directed in a desired/optimal way. In another embodiment, a plurality of sensors 20 may be employed to monitor crowd movements and may be employed to control the crowd with warnings and other feedback. The coupling of sensors 20 to each other and/or to processor 14 could be performed either wirelessly or via a wired solution (which may already be present to allow for manual control of the lighting).
The control of the effects in a disco or other application may be performed using software programs written to provide an appropriate response to feedback conditions measured by the transducer array 20. In one example, the modules 25 include lighting effects. The sensor or transducer array 20 senses the presence of a higher density of people in a given area of the environment 10. The controller 14 is programmed to respond by selectively activating only those modules 25 in the area where the higher density of people is detected. The criteria for activation of modules 25 can be varied with the application and/or user preference.
Such programs can be provided to reduce energy and to reduce costs or to provide a way of extending the useable life of equipment. For example, the controller 14 may control a thermostat module (e.g., a module 25), and the sensor 20 could be employed to determine where people are in area 10 and adjust a temperature setting in accordance with a number of people sensed in a portion of the area 10. In another embodiment, one module 25 may include an alarm. When a number of people in a room or on a floor of a building have exceeded a maximum capacity, the alarm is tripped. The alarm may be audible, may be visual or may be a message sent to a service center or other monitoring location.
The array 20 preferably includes an array of ultrasonic transducers which may be shaped or directed in a plurality of directions in the room 10. Ultrasonic waves 11 are omni-directional and bounce off walls, floors etc. so that a direct line of sight is not needed between a living being (16) and the transducer 20. Ultrasonic waves are capable of determining density changes (areas of different densities) in the room 10 and whether these areas of different density are moving (motion sensing) by comparing a sequence of images or data. Ultrasonic technology is known in the art for other applications. The scan uses ultrasonic waves to penetrate any visual impairment, such as smoke, to detect the person 16, etc. The scan information may be stored e.g., in a memory 26. The scan patterns are monitored by processor 14 to determine whether an adjustment to modules is needed or desired in accordance with preprogrammed and stored (e.g., in memory 26) criteria 28. The criteria 28 may include thresholds for density profiles, number of persons, amount of activity, etc. When one or more thresholds have been exceeded, a predetermined action may be taken. The criteria 28 may be stored in a look-up table or the like to associate a response to a mapping of scan information. Such look-up table may be user-configured.
A scan map 30 may be generated and stored in memory 26. The map 30 may include a snap shot at a given time of a number and location of people or objects in a room. This can be compared to subsequent snap shots to monitor changes over time, or the map may be used to determine a particular measurement such as population in an area of a room. In one embodiment, the area 10 may be separated into portions or a grid. Each portion would than be serviced by a particular module 25. When the portion exceeds a threshold or undergoes a change, the criteria is consulted to determine whether an action module 25 corresponding to that portion is to be activated or deactivated. For example, the controller 14 may deactivate (or activate) an action module 25 if a presence of people is not detected.
Referring to FIG. 2, the transducer array 20 may include a device 200 having an array 202 of thin-film ultra-sound transducers that are connected to a microcontroller which is capable of generating ultrasonic waves and processing received presence detection signals. In one embodiment, the thin film ultrasound transducer array 202 may include about 20 elements (transducers), with an element pitch of, e.g., 400 micrometers, and a total device size is about 10x10 mm. The size and dimensions given herein are for illustrative purposes, and should not be construed as limiting. It should be understood that the size of the device 200 permits ease of deployment in any tracking or detection system, including security systems. The size and dimensions of the transducer array are preferably unobtrusive in appearance and are energy efficient.
Because the device 200 has a transducer array 202, the device 200 is capable of performing a sweep or scan. Moreover, the device 200 as prototyped has shown transmit efficiency in air at a surprisingly low power consumption. In one illustrative example, for, say, a 5 Volt peak-peak power level, it is possible to cover about 2.5 meters with a few milliWatts. This can be further optimized, but is described for illustrative purposes. It should be understood that a plurality of devices 200 may be employed to provide scan maps employed to trigger actions of modules 25 (FIG. 1). In this way, more accurate mapping of a given space can be achieved.
According to illustrative embodiments, a transducer and/or an array of transducers are provided which may be used, e.g., for real-time imaging in air, as well as fluids and solids, and for presence and/or motion detection of object(s) by using Doppler effects, for example, including inanimate and animate object(s), and determination of various parameters such as speed, direction of movement, location, and/or the number of the object(s). In one embodiment, the transducer is a thin-film, which comprises a membrane formed over a front substrate. A piezoelectric layer is formed over the membrane at an active portion, and peripheral portions are adjacent to the active portion. If desired, the piezoelectric layer may be patterned. A patterned conductive layer including first and second electrodes is formed over the piezoelectric layer. Further, a back substrate structure is provided having supports located at the peripheral portions adjacent the active portion. The height of the supports is greater than a combined height of the patterned piezoelectric layer and the patterned conductive layer. Many transducers may be connected to form an array, where a controller or controllers (14) may be provided for controlling the array, such as steering a beam of the array, and processing signals received by the array, for presence or motion detection and/or imaging, for example.
Various sensors may be provided on flexible foils to form flexible sensors which may be formed into any desired shape. Further, different types of sensors or detectors may be combined or integrated into a single multi-sensor, such as a multi-sensor including ultrasound detectors for detecting ultrasound signals. The sensors may be used in various applications, such as imaging (ultrasound) as well as motion or presence detection, where the ultrasound sensor(s) does not require line of sight for operation, in contrast to the IR sensor(s) which does require line of sight for operation.
Referring to FIG. 3, in an illustrative embodiment, thin film piezoelectric transducer arrays are used for presence and/or motion detection or the like, where FIG. 3 shows an array 300 of thin film piezoelectric transducer elements 310. The array 300 and/or each element 310 may have any size and shape. A pitch 320 of the elements 310 is selected based on application. For motion detectors, to achieve a low attenuation in air, the arrays are designed to operate at frequencies of, e.g., 30-450 KHz. To operate at these low frequencies, the element pitches 320 are approximately a few hundred micrometers to several thousand micrometers (e.g., the pitch may be between about 200 micrometers and about 4000 micrometers). The pitch 320 is the width 330 of an element plus the gap 340 that separate one element from an adjacent element.
As shown in FIG. 3, the array 300 may be connected to a controller or processor 350 with associated electronics, such as phase shifters, delay taps, converters and the like for control of the array and processing information received from the array 300, such as to enable electronic steering the ultrasonic beam for wider coverage and reduction or elimination of blind spots. The processor 350 may be a processor for the individual array chip, or the functionality of processor 350 may be performed by processor 14 (FIG. 1). Processor 14 may be used instead of processor 350 or in conjunction with processor 350 to provide the control for transducers 310 of the array 300, and control the activities of the modules 25. A memory 360 may also be operatively coupled to the processor 350 for storing various data and application programs and software instructions or codes for control and operation of the array system when executed by the processor 350. The memory 360 may be a memory device for the individual array chip 300 or the memory 26 may be employed to provide this function. The processor 350 and memory 360 may be located at or near the transducer array, located remotely from the transducer array or located on a same chip as the transducer array.
Array 300 may be employed to scan a room or zone (e.g., in a discotheque). The array 300 is triggered (or it may always be on) to perform a sweep to detect whether there are people present in a room or area and their respective locations. The array 300 would be able to see areas of high densities of people based on ultrasonic waves generated and detected by the array 300. The result of the measurement will be communicated to the processor 350 where the data received back from the sensors of the array 300 can be mapped to determine an action to be taken. The action to be taken will depend on the preprogrammed criteria (28) and the available modules (25). The communication between sensors/array 300 and the processors 350 or 14 can be either via a wireless interface or via a wired communication line. For one illustrative wireless application, a transceiver 345 is employed. The transceiver 345 receives the transducer information from transducer array 300 through the processor 350 and transmits the information to controller 14, which in turn communicates with the modules 25.
The processor or microcontroller 350 provides signal processing to transceiver 345 compliant with, e.g., the Zigbee standard, but any other protocol may be employed. The transceiver 345 is triggered to send a message with the needed content. To achieve a high coupling coefficient of the transducer devices, which is the amount of electrical energy transferred into mechanical energy (i.e., the efficiency of the electro-mechanical conversion), a sensor 400 may be provided, as shown in FIG. 4A where, electrodes 430, 440 and 430', 440' are processed on the same side of the piezoelectric thin film, and the elements operate in a poling direction parallel to the plane of the transducer. In particular, the in-plane electric field between a pair of electrodes 430, 440, and 430', 440', which may be inter-digitated, causes longitudinal stress oscillation in the plane of the piezoelectric thin film that in turn leads to a flexural oscillation of the membrane. A reduced spacing between the electrodes 430, 440 allows operation at lower voltages. In the following description, "positive" and "negative" voltages are used to indicate that the electric field in the piezoelectric material is parallel or anti-parallel to the poling direction, respectively. The sensor 400 includes a membrane 410 formed on a substrate which is removed after formation of the sensor 400 to allow movement of the membrane 410. Piezoelectric material 420, 420' is formed on the membrane 410 which, for example, may be patterned if desired to increase performance. Further, pairs of electrodes 430, 440, and 430', 440' are formed over respective piezoelectric regions 420, 420' of the patterned piezoelectric material.
As shown in FIG. 4A, when a positive voltage is applied to the inner edge electrode 440, 440', and a negative voltage is applied to the outer edge electrode 430, 430', which may alternatively be grounded, elongation 450 of the piezoelectric layers results in a downward bending 460 of the membrane stack, as shown in FIG. 4B. Reversing the polarity of the voltages applied to the electrodes pairs 430, 440 and 430', 440', bends the membrane stack upward. Voltage pulses or any alternating current (AC) signal applied to the piezoelectric layers create ultrasonic waves that may be reflected from objects for detection thereof. The operating principle of a membrane transducer is depicted in FIG. 4B, where a fundamental bending mode is shown. A displacement 404 of the membrane results in bending of the sections 401, 401' and 402. The sections 403 remain almost unstrained. Piezoelectric actuation is used to bend one or several curved sections 401, 401', or 402. A layered membrane is used at least in these strainable or movable parts 401, 401', 402 and will be exemplified in the following sections. The given implementations should impose no limitation on the freedom of choosing which section of the membrane is actuated. For example, the stack 440, 430, 420, 410 of FIG. 4A forms the actuation section 401 shown in FIG. 4B. Of course, a strainable or movable stack may also be placed at section 402.
If desired, the pair of electrodes, instead of being on one side, e.g., on the top side of the piezoelectric material, may be on both sides, e.g., to sandwich the piezoelectric material. In this case, voltage is provided across top and bottom electrode pairs.
The basic module of the piezoelectric thin film transducers is a stack of thin film membranes, as shown by reference numeral 410 in FIG. 4A, respectively. Illustratively, the membrane 410 is formed from silicon nitride, silicon oxide, or combinations of silicon nitride and silicon oxide. The membrane 410 may be deposited for example in a low pressure chemical vapor deposition (CVD) process. On top of the membranes 410, a thin film barrier layer of, e.g., titanium oxide, zirconium oxide or aluminum oxide, may be applied as necessary.
On top of the membrane layer 410 (or on top of the barrier layer when present), a piezoelectric thin film is formed, processed and patterned (if desired) to form the piezoelectric regions 420, 420'. Illustratively, the piezoelectric thin film may be lead titanate zirconate which is either undoped or doped with, e.g., La, but may be also any other piezoelectric material. The piezoelectric layer 420 may be continuous or patterned to match the width of the actuation section (402 in FIG. 4B). A plurality of the transducer elements may be arranged into a one or two dimensional array where the pitch of the elements may be as small as the width of an element (shown as reference numeral 330 in FIG. 3).
As described in connection with FIG. 3, a plurality of elements 310 may be provided in an array 300, which may range from one element to several thousands of elements of the same and/or different size and/or shape. To operate the devices at frequencies of e.g. 30-450 KHz, the elements are designed with pitches in the order of several hundred micrometers to several thousand micrometers. It should be understood that any other designs, which enable the efficient operation of the transducer at these low frequencies, e.g., circular shaped membranes or elements and any shaped array, are also possible. The pitch 320 is preferably between about 200 micrometers and about 4000 micrometers. To enable the operation at low voltages and still achieve the desired resonance frequencies of the devices of approximately in the range of 30-450 KHz, a transducer element may have a pitch of 400-1500 μm, which is the design associated with FIG. 4A where interdigital electrodes are formed on only one side of the piezoelectric layer 420. An array (300 in FIG. 3) of transducer elements may be formed and configured for scanning and beam steering where the elements, having a pitch 320 (FIG. 3) of 400-800 μm, may be connected in parallel, for example. A voltage signal is applied to the interdigital electrodes 430, 440 (430', 440') to provide different sign (or polarity) voltages on adjacent electrodes thus creating an in-plane electric field between the electrodes 430, 440 thus exciting the piezoelectric layer 420 into a longitudinal oscillation in the plane of the piezoelectric layer 420. The change in length of the piezoelectric element excites the membrane 410 into oscillation. The reverse process of converting a mechanical wave (ultrasound) into an electrical signal is also performed by the transducers. In this way, ultrasound waves can be generated and received by transducers of the array 300. Various modifications may be provided as recognized by those skilled in the art in view of the description herein. For example, actuation electrodes may form a single plate capacitor in the center or at the edges of the membrane. Alternatively, the single plate capacitor may be divided into smaller areas that may be connected in a series configuration to match the operation voltage of the driving circuit. Each of the above transducers, sensors and systems may be utilized in conjunction with further systems. In certain applications, different shapes of transducer arrays are desirable. For example, a capacitive membrane ultrasound transducer array formed on slabs of carrier substrates of semiconductor material may be employed. Two slabs of a substrate may be separated or connected by a thinner substrate bridge which permits bending. The separated or thinly connected slabs may be positioned along a curved surface resulting in a curved array. The slabs are connected by conductive interconnects that are flexible enough to withstand the degree of curvature. For example, the array 300 shown in FIG. 3 may include at least one thin film flexible ultrasound transducer, configured as at least one omni-directional motion and presence detector. The ultrasound sensor(s) detect ultrasound signals around barriers and do not need a direct line of sight as the mechanical waves can bounce around obstacles. The obstacles could include highly dispersive media such as smoke, or particulate matter that may be present in an environment. Flexibility of the array of ultrasound transducers enables realization of arrays in various shapes. Such flexible transducer arrays may be formed and mounted in any desired shape, e.g., a cone shape on the ceiling. This enables omni-directional transmission and detection of ultrasound signals. A sensor array can form or steer a beam that can cover a 360 degree space around the region Embodiments including a flexible array of transducers of any type of transducer, may be realized, such as ceramic piezoelectric elements, and/or thin film transducers, for example. Piezoelectric material may be used for both generation/transmission and reception/detection of ultrasound. Referring to FIG. 5, a method for tracking activity in the presence of light dispersive media is illustratively depicted. In block 502, an area where light through air in the area is at least partially attenuated due to particulate matter is ultrasonically swept by employing an ultrasonic transducer array to scan the area to determine human activity or the presence of objects or animals. The transducer array may be configured to perform the scan when triggered by an event, e.g., a number of people increases, a time elapses, etc. A thin film ultrasound device can be used to scan a space and determine if people, objects, etc. are present. The device has an array, which enables formation and steering of an ultrasound beam, making scanning (of up to 360 degrees) of the space possible. Multiple arrays may be used, e.g., facing in different directions. The device can track people (for example, in discotheques) even if the space or a part of the space is filled with smoke.
In block 504, the activity in the area is mapped to create an activity map. This may include, in block 506, that the area may be divided in to regions or portions. In block 508, activity for each region may be mapped.
In block 510, action modules are selectively activated throughout the area in accordance with the activity map. Action modules are configured or reconfigured based upon the mapping of the space. For example, lighting of the space can be adjusted according to the location of people. The modules may include mechanisms such as light switches, servos, speakers, cameras or any other mechanism, which are controlled by a controller to activate or deactivate the mechanisms in accordance with the activity map. In regions, corresponding modules may be activated or deactivated based upon the activity within that region. For example, the action modules may be activated when a number of people exceeds a threshold in a given portion of the area.
In interpreting the appended claims, it should be understood that: a) the word "comprising" does not exclude the presence of other elements or acts than those listed in a given claim; b) the word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements; c) any reference signs in the claims do not limit their scope; d) several "means" may be represented by the same item or hardware or software implemented structure or function; and e) no specific sequence of acts is intended to be required unless specifically indicated.
Having described preferred embodiments for ultrasonic sensors for tracking objects even in a light dispersive media (which are intended to be illustrative and not limiting), it is noted that modifications and variations can be made by persons skilled in the art in light of the above teachings. It is therefore to be understood that changes may be made in the particular embodiments of the disclosure disclosed which are within the scope and spirit of the embodiments disclosed herein as outlined by the appended claims. Having thus described the details and particularity required by the patent laws, what is claimed and desired protected by Letters Patent is set forth in the appended claims.