WO2013084152A1

WO2013084152A1 - Adaptable thin film ultrasound array for presence detection

Info

Publication number: WO2013084152A1
Application number: PCT/IB2012/056964
Authority: WO
Inventors: Wouter Anthon Soer; Willem Franke Pasveer; Mareike Klee
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 2011-12-07
Filing date: 2012-12-05
Publication date: 2013-06-13

Abstract

A transducer assembly (100) is disclosed, configured such that an adaptable beam shape of an ultrasound beam emitted by the transducer assembly (100) may be achieved. This is achieved by a controlled selection of the set of transducer elements (101) of a plurality of transducer elements (101) of the transducer assembly (100) that are to be actuated, particularly with respect to the number of transducer elements (101) included in the set. The beam shape or beam profile of the ultrasound beam emitted by the transducer assembly (100) may be modified, e.g., in accordance with application requirements, by actuating fewer or more transducer elements (101) in the transducer assembly (100), by the ultrasound beam emitted by the transducer assembly (100) being based on superposition of the ultrasound beams produced by the respective transducer elements (101) in the selected set.

Description

Adaptable thin film ultrasound array for presence detection

FIELD OF THE INVENTION

The present invention generally relates to presence or motion detection systems. Specifically, the present invention relates to a transducer assembly suitable for use in a presence sensor, and a presence sensor comprising a transducer assembly.

BACKGROUND OF THE INVENTION

Presence or motion detectors or sensors are known, which may use different techniques for detecting presence or motion. Examples include Passive Infrared (PIR) detectors, ultrasonic (US) motion detectors and detectors based on a combination of PIR and US techniques. Further examples include detectors based on radar, sound and pressure. Applications of presence or motion detectors are numerous, including for example lighting control systems, e.g. for switching one or more light sources on and/or off based on detection of presence or motion of a person in the proximity of the light source or light sources, and burglar alarms, where detection of presence or motion by the detector of a person in the proximity of the detectors causes an alarm to go off.

In order to realize localized presence detection, i.e. determination of presence of the position of a person within the detection area or region, ultrasound based detector arrays have been proposed. Such ultrasound detector arrays generally comprise multiple transducer elements configured for example as a linear array and are capable of creating beams that can scan a location such as a room in order to determine presence and possibly also location of a person or object situated therein.

US-2004/0267138-A1 discloses an ultrasound system using selective sets of ultrasound elements to generate an ultrasound beam, scanning the beam over a series of ultrasound elements in order to collect echo data covering an area, and generating an image from the resulting data. The scanning process includes shifting the set of ultrasound elements used to form the ultrasound beam by more than one ultrasound element between each step in the scanning process.

The scanning procedure of ultrasound arrays may lead to delayed or missed detection of presence or motion since it typically takes 1 or 2 seconds for a scanning ultrasound array to complete a scan. Furthermore, for non-scanning ultrasound arrays, the beam shape is generally determined by the geometry of the transducer elements.

SUMMARY OF THE INVENTION

In view of the above discussion, a concern of the present invention is to provide a transducer assembly suitable for use in a presence detector, which transducer assembly has an increased adaptability with regards to application requirements.

A further concern of the present invention is to provide a transducer assembly facilitating or even enabling adaptation of the beam profile or beam shape of an ultrasound beam emitted by the transducer assembly to specific requirements, without the need for performing a beam scanning procedure.

To address at least one of these concerns and other concerns, a transducer assembly in accordance with the independent claim is provided. Preferred embodiments are defined by the dependent claims.

According to a first aspect of the present invention, there is provided a transducer assembly comprising a plurality of actuatable transducer elements, each transducer element being configured to produce an ultrasound beam, ultrasound pulse, ultrasound wave, or ultrasound signal, when actuated. The transducer assembly comprises an actuation unit configured to selectively and controllably actuate each transducer element in a first set of the plurality of transducer elements, thereby producing a first ultrasound beam based on superposition of the ultrasound beams produced by the respective transducer elements in the first set, and actuate each transducer element in a second set of the plurality of transducer elements, thereby producing a second ultrasound beam based on super position of the ultrasound beams produced by the respective transducer elements in the second set. The actuation unit is configured to controllably select the first and second sets, respectively, such that the number of transducer elements in the first set is different from the number of transducer elements in the second set, whereby the first ultrasound beam exhibits a beam shape different from the beam shape of the second ultrasound beam.

In other words, by a transducer assembly according to the present invention, an adaptable beam shape of an ultrasound beam emitted by the transducer assembly may be achieved. This is achieved by the controlled selection of the set of transducer elements of the plurality of transducer elements that are to be actuated, particularly with respect to the number of elements in the set. The beam shape or beam profile of the ultrasound beam emitted by the transducer assembly may be modified, e.g., in accordance with application requirements, by actuating fewer or more transducer elements in the transducer assembly. Since the ultrasound beam emitted by the transducer assembly is based on superposition of the ultrasound beams produced by the respective transducer elements in the selected set, a change in beam shape or beam profile can hence be effectuated. For example in a presence or motion detection application, on one hand, actuation of relatively few transducer elements in the transducer assembly, e.g. one or two transducer elements, may result in a relatively wide ultrasound beam being emitted by the transducer assembly that can be used for detection of relatively large movements of a person or object in a relatively large detection region, e.g., movements of the limbs of a person walking. On the other hand, actuation of relatively many transducer elements in the transducer assembly, e.g. actuation of more than two transducer elements, may narrow the ultrasound beam being emitted by the transducer assembly and increase the output power of the ultrasound beam, so that it can be used for detection of relatively small movements of a person or object in a part of the detection region, e.g., movements of the arms of a person sitting at a desk working (e.g., writing).

Hence, by means of a transducer assembly according to the present invention, the beam profile or shape of an ultrasound beam emitted by the transducer assembly may be adapted to specific requirements, without need for performing beam scanning, and without need for beam steering electronics.

By appropriate adaptation of the beam profile or shape of an ultrasound beam emitted by the transducer assembly, a selective and/or controllable directivity of the ultrasound beam emitted by the transducer assembly may be facilitated or even enabled. Each transducer element may be independently actuatable with respect to the other transducer elements.

According to embodiments of the present invention, a set of transducer elements of the plurality of transducer elements may be concertedly actuatable. In other words, the actuation unit may be configured to actuate each transducer element in a set of transducer elements as a single collective transducer element.

The actuation unit may be configured to selectively and controllably actuate each transducer element in one or more further sets, where the number of transducer elements in the one or more further sets differs from the number of transducer elements in the first and/or second set. Thereby, one or more additional ultrasound beams may be emitted by the transducer assembly having in general different beam shapes or beam profiles. According to a second aspect of the present invention, there is provided a presence sensor for sensing presence of an object or person. The presence sensor comprises a transducer assembly according to the present invention.

According to a third aspect of the present invention, there is provided a lighting system comprising a presence sensor according to the present invention.

The lighting system may for example comprise a luminaire with the presence sensor being integrally arranged therein.

The transducer assembly may comprise an output surface arranged such that the first and second ultrasound beams, respectively, leave the transducer assembly via the output surface.

The actuation unit may be configured to controllably select the first and/or second set such that the second ultrasound beam exhibits an angular range in relation to a normal of the output surface that is smaller than the angular range of the first ultrasound beam in relation to the normal of the output surface, or vice versa. In other words, the transducer elements in the first and/or second set, in particular the number of transducer elements in the first and/or second set, may be chosen such that the resulting first and second ultrasound beams, respectively, have different beam widths with respect to the output surface, and/or different beam solid angles. Hence, the beam shape of an ultrasound beam emitted by the transducer assembly may be switched between at least two modes, for example between a relatively wide ultrasound beam and a relatively narrow ultrasound beam. In a presence or motion detection application, this may for example be utilized for detecting remote and nearby presence of a person or an object, respectively, with respect to the detector or sensor location.

Optionally or alternatively, the actuation unit may be configured to controllably select the first and/or second set such that the second ultrasound beam exhibits an intensity in a predefined angular range in relation to a normal of the output surface, e.g., the normal of the output surface mentioned in the foregoing, that is larger than the intensity of the first ultrasound beam in the predefined angular range in relation to the normal of the output surface, or vice versa. In other words, the transducer elements in the first and/or second set, in particular the number of transducer elements in the first and/or second set, may be chosen such that the resulting first and second ultrasound beam, respectively, have different intensity or signal amplitude in a given direction or in a plurality of given directions. Hence, the intensity of an ultrasound beam emitted by the transducer assembly may be switched between at least two modes. In a presence or motion detection application, this may for example be utilized for detecting relatively small movements of a person or an object in the proximity of the detector, by choosing the transducer elements in the first and/or second set, in particular the number of transducer elements in the first and/or second set, so at as to achieve a resulting ultrasound beam having a relatively high intensity in a given direction or in a plurality of given directions.

Optionally or alternatively, the actuation unit may be configured to

controllably select the first and/or second set such that the number of transducer elements in the first and/or second set, respectively, is at least two, and such that each transducer element in the first and/or second set, respectively, is coupled to at least one other transducer element in the first and/or second set, respectively. In other words, optionally or alternatively, the transducer elements in the first and/or second set may be chosen from the plurality of transducer elements such that neighboring transducer elements in the transducer assembly, e.g. adjacent transducer elements in the transducer assembly are chosen for the first and/or second set, respectively.

In the context of the present application, the term coupled is not limited to be construed as directly coupled, but also encompasses functional couplings or connections having intermediate components. For example, on one hand, if an output of a first component is coupled to an input of a second component, this comprises a direct coupling or connection. On the other hand, if an electrical conductor directly supplies an electrical signal from the output of the first component substantially unchanged to the input of the second component, alternatively via one or more additional components, the first and second component are also coupled. However, the connection is functional in the sense that a gradual or sudden change in the electrical signal from the output of the first component results in a corresponding or modified change in the signal that is input to the second component.

The transducer assembly may comprise a power module adapted to selectively convey electrical power to each of the transducer elements.

Each transducer element may be actuatable responsive to supply of electrical power thereto.

The actuation unit may be configured to actuate each transducer element in the first and/or second set by causing the power module to supply power to each transducer element in the first and/or the second set of transducer elements, respectively, synchronously with respect to phase associated with electrical power, i.e. phase of voltage or current, supplied to each transducer element in the first and/or the second set, respectively. This may be carried out, e.g., by controlling timing of electrical signals supplied to each of the transducer elements in the first and/or the second set of transducer elements, respectively.

The power module may be configured to supply continuous or pulsed electrical signals to each of the transducer elements in the first and/or the second set of transducer elements. In other words, the transducer assembly may operate according to a pulsed or continuous ultrasound beam emission mode.

The actuation unit may be configured to controllably select the first set and/or second set such that the first set is a proper subset of the second set, or such that the second set is a proper subset of the first set.

In the context of the present application, by a proper subset of a set it is meant a set that is a subset of the set but not equal to it.

The actuation unit may be configured so as to selectively and controllably produce the first and second ultrasound beams at different times.

The plurality of transducer elements may be arranged in an array. The array may be a linear array. The array may be a two-dimensional array.

The array may be circular, square, or rectangular array, or shaped otherwise.

Each transducer element may be constituted by a respective layer such that the plurality of transducer elements comprises a layered structure.

For example, each transducer element may be constituted by a respective thin film, i.e. a layer of material having a thickness ranging from about 1 nanometer to about 10 micrometers, such as described in US patent application US-2010/0277040-A1 by the same applicant.

At least one transducer element may be based on a ceramic piezoelectric transducer element.

At least one transducer element may comprise or be constituted by a piezoelectric thin film processed on top of a membrane, in order to realize a piezoelectric thin film micro-machined ultrasound transducer element.

The presence sensor may comprise a receiving and processing module.

The presence sensor may comprise a control module.

The control module may be configured to cause the actuation unit of the transducer assembly to actuate each transducer element in the first set.

The receiving and processing module may be configured to receive a reflected ultrasound beam generated by reflection of the first ultrasound beam from structures in the surroundings of the presence sensor. The receiving and processing module may on basis of the reflected ultrasound beam determine whether the object or person is present.

In the context of the present application, by "structures in the surroundings of the presence sensor" it is meant objects, persons, walls, ceilings, etc. located around the presence sensor.

Determination whether the object is present may for example be based on Doppler shift of the reflected ultrasound beam, time-of-flight of the ultrasound beam emitted by the transducer assembly, or a combination of these techniques.

On a condition that the receiving and processing module determines presence of the object or person on basis of the reflected ultrasound beam, the control module may be configured to cause the actuation unit to actuate each transducer element in the second set, and the receiving and processing module may be configured to receive a reflected ultrasound beam generated by reflection of the second ultrasound beam from structures in the surroundings of the presence sensor. The receiving and processing module may on basis of the reflected ultrasound beam determine whether the object or person is present.

In other words, the presence detector may be adapted to switch the transducer assembly between at least two different modes of operation so as to adapt to application requirements.

For example in switching between two modes, a first mode may comprise each transducer element in the first set being actuated, with the resulting first ultrasound beam being emitted by the transducer assembly, the first ultrasound beam having a first beam shape or beam profile. The first ultrasound beam may have a relatively large width that can be used for detection of relatively large movements of a person or object in a relatively large detection region, e.g., movements of the limbs by a person walking. A second mode may comprise each transducer element in the second set being actuated, with the resulting second ultrasound beam being emitted by the transducer assembly, the second ultrasound beam having a second beam shape or beam profile different from the first beam shape. The second ultrasound beam may have a relatively small width and increased output power relatively the first ultrasound beam, so that it can be used for detection of relatively small movements of a person or object in a part of the detection region, e.g., movements of the arms of a person sitting at a desk working.

For facilitating or even enabling receiving a reflected ultrasound beam, the receiving and processing module may for example comprise at least one transducer element adapted to receive a reflected ultrasound beam. The at least one transducer element may be constituted by or comprise a respective transducer element of the plurality of transducer elements comprised in the transducer assembly.

The receiving and processing module may be configured to convert a reflected ultrasound beam to a respective electric signal. Presence of the object may be determined on basis of the electric signal.

The lighting system may comprise a presence sensor comprising a receiving and processing module and a control module, as described in the foregoing.

The lighting system may comprise a light-emitting module adapted to controllably emit light with regards to a set of light characteristics including luminous flux.

The control module of the presence sensor may be configured to control the light-emitting module at least with regards to luminous flux of the light emitted by the light- emitting module.

On a condition that the receiving and processing module of the presence sensor determines presence of the object or object on basis of the reflected ultrasound beam generated by reflection of the first ultrasound beam from structures in the surroundings of the presence sensor, the control module may be configured to control the light-emitting module so as to emit light having a first predefined luminous flux.

On a condition that the receiving and processing module of the presence sensor determines presence of the object or person on basis of the reflected ultrasound beam generated by reflection of the second ultrasound beam from structures in the surroundings of the presence sensor, the control module may be configured to control the light-emitting module so as to emit light having a second predefined luminous flux.

The second predefined luminous flux may be different from the first predefined luminous flux.

According to a fourth aspect of the present invention, there is provided a method for operating a lighting system. The lighting system comprises a presence detector comprising a receiving and processing module and a control module, such as described in the foregoing. The lighting system comprises a light-emitting module adapted to controllably emit light with regards to a set of light characteristics including luminous flux.

The method comprises, on a condition that the receiving and processing module of the presence sensor determines presence of the object or person on basis of the reflected ultrasound beam generated by reflection of the first ultrasound beam from structures in the surroundings of the presence sensor, controlling the light-emitting module so as to emit light having a first predefined luminous flux. On a condition that the receiving and processing module of the presence sensor determines presence of the object or person on basis of the reflected ultrasound beam generated by reflection of the second ultrasound beam from structures in the surroundings of the presence sensor, the light-emitting module is controlled so as to emit light having a second predefined luminous flux different from the first predefined luminous flux.

On a condition that the receiving and processing module of the presence sensor fails to determine presence of the object or person on basis of the reflected ultrasound beam generated by reflection of the second ultrasound beam from structures in the surroundings of the presence sensor, the light-emitting module may be controlled so as to emit light having the first predefined luminous flux.

In other words, in case presence of the object or person is determined on basis of the reflected ultrasound beam generated by reflection of the first ultrasound beam from structures in the surroundings of the presence sensor, the light-emitting module may be controlled so as to emit light having the first predefined luminous flux. Then, presence of the object or person on basis of the reflected ultrasound beam generated by reflection of the second ultrasound beam from structures in the surroundings of the presence sensor may be determined, wherein in case presence of the object or person is determined, the light-emitting module may be controlled so as to emit light having the second predefined luminous flux. Otherwise, in case presence of the object or person on basis of the reflected ultrasound beam generated by reflection of the second ultrasound beam from structures in the surroundings of the presence sensor cannot be established or determined, the light-emitting module may be controlled so as to continue emit light having the first predefined luminous flux.

Hence, different operating modes of the transducer assembly, i.e. emission of at least the first and second ultrasound beams, or further beams having beam shapes different from the first and/or second ultrasound beams, may be used so as to control light output, particularly for example luminous flux output, from the lighting system.

Optionally, on a condition that the receiving and processing module of the presence sensor fails to determine presence of the object or person on basis of the reflected ultrasound beam generated by reflection of the second ultrasound beam from structures in the surroundings of the presence sensor, the control module may be configured to control the light-emitting module so as to emit light having the first predefined luminous flux.

According to a fifth aspect of the present invention, there is provided a computer program product adapted to, when executed in a processor unit, perform a method according to the present invention. According to a sixth aspect of the present invention, there is provided a computer-readable storage medium on which there is stored a computer program product adapted to, when executed in a processor unit, perform a method according to the present invention.

According to a seventh aspect of the present invention, there is provided a gesture recognition device. The gesture recognition device comprises a presence sensor according to the present invention adapted to determine a gesture made by an object or person by means of determining at least one of presence and location of at least a portion of the object or person.

Hence, the presence sensor may be configured to determine at least one of presence and location of at least a portion of an object or person. On basis of the determined presence and/or location, the presence sensor may be configured to determine a gesture made by the object or person.

The at least a portion of the object or person may comprise or be constituted by at least one marker arranged on the object or person. The at least one marker may be arranged on the object or person such that the gesture made by the object or person changes the position and/or orientation of the at least one marker.

With regards to a gesture made by a person, a gesture may be defined as a movement of the body, e.g., a movement of one of the limbs of the person. Generally speaking, a gesture is a non-vocal communication, used instead of or to supplement verbal communication, to express a meaning to another person. The gesture may for example be articulated by means of a hand, an arm, or even by means of the entire body as a whole. The gesture may be a movement of the head, the face and/or the eyes.

In the context of the present application, by the wording ultrasound it is meant sound waves having a frequency greater than about 20 kHz.

In the context of the present application, by a transducer element it is meant a device that converts one type of energy to another type.

In the context of the present application, by a piezoelectric ultrasound transducer element it is meant a device that converts electrical energy in mechanical energy.

In the context of the present application, by a piezoelectric thin film ultrasound transducer element, it is meant a device that is based on thin film technology where a piezoelectric thin film is processed on top of a membrane and where electrical energy is converted into mechanical energy. For a transducer element configured to produce an ultrasound beam when actuated, the transducer element converts one type of energy, generally electrical energy, which is discussed further in the following, to mechanical energy in the form of ultrasound.

In the context of the present application, by the wording "ultrasound beam" it is referred to an output of a sound wave source producing sound waves having a frequency greater than about 20 kHz, irrespective of the sound wave source producing pulses that are continuous or being of a predetermined duration.

In the context of the present application, by choosing or selecting a set of the plurality of transducers, it is meant selecting one or more particular transducers.

A set of transducer elements may according to one example comprise at least one transducer element.

A set of transducer elements may include a single transducer element only. In general, a set of transducer elements may include a plurality of transducer elements.

Further objects and advantages of the present invention are described in the following by means of exemplifying embodiments.

It is noted that the present invention relates to all possible combinations of features recited in the claims. Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the following description. Those skilled in the art realize that different features of the present invention can be combined to create embodiments other than those described in the following.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplifying embodiments of the invention will be described below with reference to the accompanying drawings, in which:

Figs, la to lc are schematic block diagrams of transducer assemblies according to embodiments of the present invention;

Fig. 2 is a graph of beam profiles of ultrasound beams emitted by transducer assemblies according to embodiments of the present invention;

Fig. 3 is a schematic block diagram of a presence sensor according to an embodiment of the present invention;

Fig. 4 is a schematic block diagram of a lighting system according to an embodiment of the present invention;

Fig. 5 is a schematic flow diagram of a method according to an embodiment of the present invention; Fig. 6 is a schematic view for illustrating principles of the present invention; Fig. 7 is a schematic view of a computer readable storage medium according to an embodiment of the present invention; and

Fig. 8 is a schematic block diagram of a gesture recognition device according to an embodiment of the present invention.

In the accompanying drawings, the same reference numerals denote the same or similar elements throughout the views.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplifying embodiments of the present invention are shown. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will convey the scope of the invention to those skilled in the art. Furthermore, like numbers refer to like or similar elements or components throughout.

In the following examples, the number of transducer elements included in the transducer assembly, and the respective numbers of transducer elements included in different sets of transducer elements, is given by way of example only. The present invention encompasses embodiments comprising any integer number of transducer elements included in the transducer assembly. Furthermore, a set of transducer elements comprises at least one transducer element.

Referring now to Fig. la, there is shown a schematic block diagram of a transducer assembly 100 according to an exemplifying embodiment of the present invention.

The transducer assembly 100 comprises a plurality of actuatable transducer elements 101, i.e. transducer elements 101 that can be actuated. Only a few transducer elements 101 are indicated by reference numerals in Fig. la, and also in Figs, lb and lc, to be discussed further in the following.

Each transducer element 101 is configured to produce an ultrasound beam, ultrasound pulse, ultrasound wave or ultrasound signal when actuated.

The transducer assembly 100 comprises an actuation unit 102.

The actuation unit 102 is configured so as to be able to selectively and controllably actuate each transducer element 101 in a first set of transducer elements 101 comprised in the transducer assembly 100. According to the depicted embodiment, the first set of transducer elements 101 is indicated by the filled elements 101 in Fig. la, and hence the first set of transducer elements 101 comprises two transducer elements 101.

The unfilled elements 101 indicate transducer elements 101 that are not actuated, i.e. transducer elements 101 which are switched off.

By actuation of the transducer elements 101 in the first set, a first ultrasound beam is produced based on superposition of the ultrasound beams produced by the respective transducer elements 101 in the first set, which first ultrasound beam is emitted by the transducer assembly 100.

The first ultrasound beam may be formed by interference of the ultrasound beams or waves of the respective transducer elements 101 in the first set, as a consequence of the principle of linear superposition.

In general, any ultrasound beam caused to be emitted by the transducer assembly may be formed by interference of the ultrasound beams or waves of the respective transducer elements in a set of transducer elements, where each transducer element is being actuated, as a consequence of the principle of linear superposition.

The ultrasound beam leaves the transducer assembly 100 via, or is emitted from the transducer assembly 100 from, an output surface 104 arranged in the transducer assembly 100.

Referring now to Figs, lb and lc, there are shown schematic block diagram of a transducer assemblies 100 according to exemplifying embodiment of the present invention.

The transducer assemblies depicted in Figs, lb and lc, respectively, are similar to the transducer assembly depicted in Fig. la.

According to the embodiments depicted in Figs, lb and lc, the actuation unit 102 is configured so as to be able to selectively and controllably actuate each transducer element 101 in a second and third set of transducer elements 101, respectively, comprised in the transducer assembly 100. As seen in Figs, lb and lc, the second set comprises four transducer elements 101 and the third set comprises eight transducer elements 101, respectively.

The unfilled elements 101 in Fig. lb indicate transducer elements 101 that are not actuated, i.e. transducer elements 101 which are switched off.

With reference to Fig. lb, similarly to the embodiment depicted in Fig. la, by actuation of the transducer elements 101 in the second set, a second ultrasound beam is produced based on superposition of the ultrasound beams produced by the respective transducer elements 101 in the second set, which second ultrasound beam is emitted by the transducer assembly 100.

With reference to Fig. lc, similarly to the embodiment depicted in Fig. la, by actuation of the transducer elements 101 in the third set, a third ultrasound beam is produced based on superposition of the ultrasound beams produced by the respective transducer elements 101 in the third set, which third ultrasound beam is emitted by the transducer assembly 100.

With reference to Figs, la to lc, each transducer element 101 in the first, second and/or third may be actuated by supplying electrical power to each transducer element 101 in the respective set synchronously with respect to phase associated with the electrical power. This may for example be carried out by controlling timing of electrical signals supplied to each of the transducer elements 101 in the respective set.

To this end, the transducer assembly 100 comprises a power module 103 adapted to selectively convey electrical power to each of the transducer elements 101.

For conveying power to each of the respective transducer elements 101, the transducer assembly 100 and/or the power module 103 may comprise a current and/or power multiplexer (not shown in Figs, la to lc) adapted to selectively channel or convey electrical current and/or power to each transducer element 101 in a chosen set of transducer elements 101.

Hence, the actuation unit 102 may be configured to actuate each transducer element 101 in the first, second and/or third set by causing the power module 103 to supply power to each transducer element 101 in the respective set.

The power module 103 may be configured to generate power, e.g. by means of a battery. Optionally or alternatively, the power module 103 and/or or the transducer assembly 100 may be coupled to an external electrical power source supplying electrical power.

Referring now to Fig. 2, there are shown graphs of beam profiles of ultrasound beams emitted by transducer assemblies according to embodiments of the present invention. The graphs have been obtained by means of simulations.

The graphs in Fig. 2 illustrate how the beam shape or beam profile of an ultrasound beams emitted by a transducer assembly according to an embodiment of the present invention can be modified by actuating different sets of transducer elements in the transducer assembly, particularly where the different sets comprise different number of transducer elements. Each graph in Fig. 2 shows the intensity I, expressed in dB, of the ultrasound beam emitted by the transducer assembly versus the angle a, expressed in degrees, in an angular range in relation to a normal of the output surface 104 of the transducer assembly, for the three cases depicted in Figs, la to lc, where the transducer elements in the first, second and third set, respectively, are actuated synchronously with respect to phase associated with the electrical power supplied to each transducer element for actuation thereof.

The solid line corresponds to actuation of each of the transducer elements in the first set comprising two transducer elements, the dashed line corresponds to actuation of each of the transducer elements in the second set comprising four transducer elements, and the dotted line corresponds to actuation of each of the transducer elements in the third set comprising eight transducer elements.

As can be seen in Fig. 2, with two transducer elements being actuated (cf. solid line), the ultrasound beam emitted from the transducer assembly extends over a relatively large angular range. With additional transducer elements being actuated (cf. dashed and dotted lines), the ultrasound beam emitted from the transducer assembly becomes confined to an increasingly smaller angular range and obtains increasingly higher amplitude compared to the case where two transducer elements are being actuated.

Hence, as can be seen in Fig. 2, by appropriate adaptation of the beam profile or shape of the ultrasound beam emitted by the transducer assembly, by means of actuating different sets of transducer elements in the transducer assembly, a selective and/or controllable directivity of the ultrasound beam emitted by the transducer assembly may be facilitated or even enabled.

Referring now to Fig. 3, there is shown a schematic block diagram of a presence sensor 300 according to an embodiment of the present invention.

The presence sensor 300 is suitable for sensing presence and possibly also motion of an object or person 301, situated in the surroundings of the presence sensor 300.

The presence sensor 300 comprises a transducer assembly 100 according to the present invention, such as has been described in the foregoing with respect to Figs, la to lc and Fig. 2.

The presence sensor 300 comprises a receiving and processing module 302 and a control module 303.

The receiving and processing module 302 may be at least partially constituted by the transducer assembly 100. For example, for facilitating or even enabling receiving a reflected ultrasound beam, the receiving and processing module 302 may comprise at least one transducer element adapted to receive a reflected ultrasound beam, wherein the at least one transducer element is constituted or comprised by a respective transducer element of the plurality of transducer elements comprised in the transducer assembly 100.

With reference to Fig. la, the control module 303 is configured to cause the actuation unit 102 to actuate each transducer element 101 in the first set. The receiving and processing module 302 is configured to receive a reflected ultrasound beam generated by reflection of the first ultrasound beam from structures (not shown in Fig. 3) in the

surroundings of the presence sensor 300. The receiving and processing module 302 is configured to determine whether the object or person 301 is present on basis of the reflected ultrasound beam.

Now, with reference to Fig. lb and/or Fig. lc, on a condition that the receiving and processing module 302 determines presence of the object or person 301 on basis of the reflected ultrasound beam, the control module 303 is configured to cause the actuation unit 102 to actuate each transducer element 101 in the second and/or third set. The receiving and processing module 302 is configured to receive a reflected ultrasound beam generated by reflection of the second and/or third ultrasound beam from structures in the surroundings of the presence sensor 300. The receiving and processing module 302 is configured to determine whether the object or person 301 is present on basis of the reflected ultrasound beam.

Referring now to Fig. 4, there is shown a schematic block diagram of a lighting system 400 comprising a presence sensor 300 according to an embodiment of the present invention, such as has been described in the foregoing with respect to Fig. 3.

The lighting system 400 comprises a light-emitting module 401 adapted to controllably emit light with regards to a set of light characteristics including luminous flux;

The control module 303 of the presence sensor 300 is configured to control the light-emitting module 401 at least with regards to luminous flux of the light emitted by the light-emitting module 401.

With reference to Fig. la and Fig. 3, on a condition that the receiving and processing module 302 of the presence sensor 300 determines presence of the object or person 301 on basis of the reflected ultrasound beam generated by reflection of the first ultrasound beam from structures in the surroundings of the presence sensor 300, the control module 303 is configured to control the light-emitting module 401 so as to emit light having a first predefined luminous flux.

Now, with reference to Figs, lb and/or lc and Fig. 3, on a condition that the receiving and processing module 302 of the presence sensor 300 determines presence of the object or person 301 on basis of the reflected ultrasound beam generated by reflection of the second and/or third ultrasound beam from structures in the surroundings of the presence sensor 300, the control module 303 is configured to control the light-emitting module 401 so as to emit light having a second predefined luminous flux, different from the first predefined luminous flux.

On a condition that the receiving and processing module 302 fails to determine presence of the object or person 301 on basis of the reflected ultrasound beam generated by reflection of the second and/or third ultrasound beam from structures in the surroundings of the presence sensor 300, the light-emitting module 401 is controlled by the control module 303 so as to continue to emit light having the first predefined luminous flux.

Referring now to Fig. 5, there is shown a schematic flow diagram of a method

500 according to an embodiment of the present invention for operating a lighting system according to the present invention.

The lighting system comprises a presence detector and a light-emitting module adapted to controllably emit light with regards to a set of light characteristics including luminous flux.

The method 500 comprises, on a condition that the receiving and processing module of the presence sensor determines presence of the object or person on basis of the reflected ultrasound beam generated by reflection of the first ultrasound beam from structures in the surroundings of the presence sensor, controlling, S501, the light-emitting module so as to emit light having a first predefined luminous flux.

In case presence is not determined, the light-emitting module may be switched off if already turned on.

On a condition that the receiving and processing module of the presence sensor determines presence of the object or person on basis of the reflected ultrasound beam generated by reflection of the second ultrasound beam from structures in the surroundings of the presence sensor, the light-emitting module is controlled, S502, so as to emit light having a second predefined luminous flux, different from the first predefined luminous flux.

For example, the first ultrasound beam may be relatively wide so as to it can be used for detection of relatively large movements of a person or object in a relatively large detection region, e.g., movements of the limbs by a person walking in a room. The first predefined luminous flux may be such that it is suitable for 'presence illumination', i.e.

sufficient for, e.g., allowing the person to orient himself or herself in the room. The second ultrasound beam may be relatively narrow and have an increased output power compared to the first ultrasound beam so that it can be used for detection of relatively small movements of a person or object in a part of the detection region, e.g., movements of the arms of a person sitting at a desk in the room and working, e.g. writing. The second predefined luminous flux may be such that it is suitable for 'task illumination', i.e. sufficient for, e.g., allowing the person to conveniently perform his or her work at the desk. Hence, the second predefined luminous flux may be larger than the first predefined luminous flux.

For example, in a relatively small room such as an office, the lighting system may comprise a luminaire with the presence sensor integrally arranged therein, and with the luminaire positioned above a desk of an office worker, e.g. close to or adjacent to the ceiling. As soon as the office worker enters the office, the presence sensor may detect presence of the office worker on basis of the reflected ultrasound beam generated by reflection of the first ultrasound beam from structures in office, whereby the light-emitting module of the luminaire is controlled so provide 'presence illumination' as discussed in the foregoing. When the office worker sits down at the desk and starts working, the presence sensor may additionally detect presence of the office worker on basis of the reflected ultrasound beam generated by reflection of the second ultrasound beam from structures in office, whereby the light-emitting module of the luminaire is controlled so provide 'task illumination' as discussed in the foregoing.

In case the receiving and processing module of the presence sensor fails to determine presence of the object or person on basis of the reflected ultrasound beam generated by reflection of the second ultrasound beam from structures in the surroundings of the presence sensor, the control module may be configured to control the light-emitting module so as to continue emit light having the first predefined luminous flux.

Referring now to Fig. 6, there is shown a schematic view for illustrating principles of the present invention.

In Fig. 6 there is schematically illustrated a side view of relatively large space or location, for example a hallway in a building, having a plurality of presence sensors 300, each being integrally arranged in a respective lighting system (not shown in Fig. 6) such as a luminaire or a light-emitting surface, arranged close to or adjacent to the ceiling (not shown in Fig. 6). Only a few presence sensors 300 are indicated by reference numerals in Fig. 6. Hence, a plurality of luminaires are arranged along the hallway.

When a person 301 walks through the hallway, the luminaires of the respective presence sensors 300 that are detecting presence of the person 301 relatively close to the respective presence sensors 300 on basis of reflected ultrasound beams generated by reflection of respective second ultrasound beams from structures in the hallway may be controlled so as to emit light having a relatively high luminous flux (e.g., corresponding to 'task illumination'). This is indicated by number "2" in Fig. 6. The second ultrasound beams, having a relatively small width and high output power, are indicated by the dashed lines emanating from the presence sensors 300 in Fig. 6.

The luminaires of the respective presence sensors 300 that are detecting presence of the person 301 more remotely with respect to the respective presence sensors 300 on basis of reflected ultrasound beams generated by reflection of respective first ultrasound beams from structures in the hallway may be controlled so as to emit light having a lower luminous flux (e.g., corresponding to 'presence illumination'). This is indicated by number "1" in Fig. 6. The first ultrasound beams, having a relatively large width, are indicated by the dotted lines emanating from the presence sensors 300 in Fig. 6.

The luminaires of the respective presence sensors 300 that are not detecting presence of the person 301 on basis of reflected ultrasound beams generated by reflection of respective first ultrasound beams from structures in the hallway are switched off so that they do emit any light at all. This is indicated by number "0" in Fig. 6.

Hence, a region surrounding the person 301while walking along the hallway may be illuminated in a natural way. Savings in energy can be achieved compared to 'full' illumination of the entire hallway, e.g. 'task illumination' of the entire hallway. The illumination can be carried out without need for signaling or communication between the different lighting systems or luminaires taking place.

Referring now to Fig. 7, there is shown a schematic view of a computer readable storage medium 700 according to an embodiment of the present invention, comprising a floppy disk 700. On the floppy disk 700 there may be stored a computer program comprising computer code adapted to, when executed in a processor unit, perform a method according to the present invention, such as the method 500 as described in the foregoing.

Although only one type of computer-readable storage medium has been described above with reference to Fig. 7, the present invention encompasses embodiments employing any other suitable type of computer-readable digital storage medium, such as, but not limited to, a non- volatile memory, a hard disk drive, a CD, a DVD, a flash memory, magnetic tape, a USB stick, a Zip drive, etc.

Referring now to Fig. 8, there is shown a gesture recognition device 800. The gesture recognition device 800 comprises a presence sensor 300 according to an embodiment of the present invention. The presence sensor 300 is adapted to determine a gesture made by an object or person 301, by means of determining at least one of presence and location of at least a portion 304 of the object or person 301.

In conclusion, a transducer assembly is disclosed, configured such that an adaptable beam shape of an ultrasound beam emitted by the transducer assembly may be achieved. This is achieved by a controlled selection of the set of transducer elements of a plurality of transducer elements of the transducer assembly that are to be actuated, particularly with respect to the number of transducer elements included in the set. The beam shape or beam profile of the ultrasound beam emitted by the transducer assembly may be modified, e.g., in accordance with application requirements, by actuating fewer or more transducer elements in the transducer assembly, by the ultrasound beam emitted by the transducer assembly being based on superposition of the ultrasound beams produced by the respective transducer elements in the selected set.

While the present invention has been illustrated and described in detail in the appended drawings and the foregoing description, such illustration and description are to be considered illustrative or exemplifying and not restrictive; the present invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

Claims

CLAIMS:

1. A transducer assembly (100) comprising:

a plurality of actuatable transducer elements (101), each transducer element being configured to produce an ultrasound beam when actuated; and

an actuation unit (102) configured to selectively and controllably actuate each transducer element in a first set of the plurality of transducer elements, thereby producing a first ultrasound beam based on superposition of the ultrasound beams produced by the respective transducer elements in the first set; and actuate each transducer element in a second set of the plurality of transducer elements, thereby producing a second ultrasound beam based on superposition of the ultrasound beams produced by the respective transducer elements in the second set,

wherein the actuation unit is configured to controllably select the first and second sets, respectively, such that the number of transducer elements in the first set is different from the number of transducer elements in the second set, whereby the first ultrasound beam exhibits a beam shape different from the beam shape of the second ultrasound beam.

2. A transducer assembly according to claim 1, wherein the transducer assembly comprises an output surface (104) arranged such that the first and second ultrasound beams, respectively, leave the transducer assembly via the output surface, wherein the actuation unit is configured to controllably select the first and/or second set such that the second ultrasound beam exhibits an angular range in relation to a normal of the output surface that is smaller than the angular range of the first ultrasound beam in relation to the normal of the output surface, or vice versa.

3. A transducer assembly according to claim 2, wherein the actuation unit is configured to controllably select the first and/or second set such that the second ultrasound beam exhibits an intensity in a predefined angular range in relation to the normal of the output surface that is larger than the intensity of the first ultrasound beam in the predefined angular range in relation to the normal of the output surface, or vice versa.

4. A transducer assembly according to claim 1, wherein the transducer assembly comprises an output surface (104) arranged such that the first and second ultrasound beams, respectively, leave the transducer assembly via the output surface, wherein the actuation unit is configured to controllably select the first and/or second set such that the second ultrasound beam exhibits an intensity in a predefined angular range in relation to a normal of the output surface that is larger than the intensity of the first ultrasound beam in the predefined angular range in relation to the normal of the output surface, or vice versa.

5. A transducer assembly according to any one of claims 1 to 4, further comprising a power module (103) adapted to selectively convey electrical power to each of the transducer elements, wherein each transducer element is actuatable responsive to supply of electrical power thereto, and wherein the actuation unit is configured to actuate each transducer element in the first and/or second set by causing the power module to supply power to each transducer element in the first and/or the second set of transducer elements, respectively, synchronously with respect to phase associated with electrical power supplied to each transducer element in the first and/or the second set, respectively, by controlling timing of electrical signals supplied to each of the transducer elements in the first and/or the second set of transducer elements, respectively.

6. A transducer assembly according to any one of claims 1 to 5, wherein the actuation unit is configured to controllably select the first set and/or second set such that the first set is a proper subset of the second set, or vice versa.

7. A presence sensor (300) for sensing presence of an object or person (301), the presence sensor comprising a transducer assembly (100) according to any one of claims 1 to 6.

8. A presence sensor according to claim 7, comprising:

- a receiving and processing module (302); and

a control module (303);

wherein the control module is configured to cause the actuation unit to actuate each transducer element in the first set, and the receiving and processing module is configured to receive a reflected ultrasound beam generated by reflection of the first ultrasound beam from structures in the surroundings of the presence sensor, and on basis of the reflected ultrasound beam determine whether the object or person is present, and

wherein, on a condition that the receiving and processing module determines presence of the object on basis of the reflected ultrasound beam, the control module is configured to cause the actuation unit to actuate each transducer element in the second set, and the receiving and processing module is configured to receive a reflected ultrasound beam generated by reflection of the second ultrasound beam from structures in the surroundings of the presence sensor, and on basis of the reflected ultrasound beam determine whether the object or person is present.

9. A gesture recognition device (800) comprising a presence sensor (300) according to claim 7 or 8 adapted to determine a gesture made by an object or person by means of determining at least one of presence and location of at least a portion of the object or person.

10. A lighting system (400) comprising a presence sensor (300) according to claim

7 or 8.

11. A lighting system (400) comprising:

- a presence sensor (300) according to claim 8; and

a light-emitting module (401) adapted to controllably emit light with regards to a set of light characteristics including luminous flux,

wherein the control module (303) of the presence sensor is configured to control the light-emitting module at least with regards to luminous flux of the light emitted by the light-emitting module,

wherein, on a condition that the receiving and processing module (302) of the presence sensor determines presence of the object or person on basis of the reflected ultrasound beam generated by reflection of the first ultrasound beam from structures in the surroundings of the presence sensor, the control module is configured to control the light- emitting module so as to emit light having a first predefined luminous flux, and

wherein, on a condition that the receiving and processing module of the presence sensor determines presence of the object or person on basis of the reflected ultrasound beam generated by reflection of the second ultrasound beam from structures in the surroundings of the presence sensor, the control module is configured to control the light- emitting module so as to emit light having a second predefined luminous flux different from the first predefined luminous flux.

12. A lighting system according to claim 11, wherein, on a condition that the receiving and processing module of the presence sensor fails to determine presence of the object or person on basis of the reflected ultrasound beam generated by reflection of the second ultrasound beam from structures in the surroundings of the presence sensor, the control module is configured to control the light-emitting module so as to emit light having the first predefined luminous flux.

13. A method (500) for operating a lighting system comprising a presence detector according to claim 8 and a light-emitting module adapted to controllably emit light with regards to a set of light characteristics including luminous flux, the method comprising:

on a condition that the receiving and processing module of the presence sensor determines presence of the object or person on basis of the reflected ultrasound beam generated by reflection of the first ultrasound beam from structures in the surroundings of the presence sensor, controlling (S501) the light-emitting module so as to emit light having a first predefined luminous flux; and

on a condition that the receiving and processing module of the presence sensor determines presence of the object or person on basis of the reflected ultrasound beam generated by reflection of the second ultrasound beam from structures in the surroundings of the presence sensor, controlling (S502) the light-emitting module so as to emit light having a second predefined luminous flux different from the first predefined luminous flux.

14. A computer program product adapted to, when executed in a processor unit, perform a method according to claim 13.

15. A computer-readable storage medium (700) on which there is stored a computer program product adapted to, when executed in a processor unit, perform a method according to claim 13.