Ultrasonic device and control method, in particular for time-of-flight measurement based applications

Abstract

The present disclosure relates to an ultrasound device and a control method, in particular for applications based on time-of-flight measurements. The ultrasound device uses MEMS type of transmitting transduction modules, wherein each transmitting transduction module emits a respective ultrasound sound wave. MEMS type of receiving transduction modules are configured to each generate an electrical signal in response to detection of impinging ultrasound sound waves. Control circuitry comprises one or more transmitting channels configured to drive emission of ultrasound sound waves by the transmitting transduction modules. A receiving channel of the control circuitry detects electrical signals generated by the receiving transduction modules connected in series to input the electrical signals to the receiving channel.

Description

Priority requirements

[0001] This application claims priority to Italian Patent Application No. 102024000026940, filed on November 28, 2024, the contents of which are incorporated herein by reference in their entirety to the fullest extent permitted by law. Technical Field

[0002] This invention relates to an ultrasonic device and a corresponding control method. In particular, this invention relates to an ultrasonic device for applications based on time-of-flight measurements, such as eye tracking, gesture recognition, and proximity sensors. Background Technology

[0003] As is well known, there are now many ultrasonic devices that are suitable for transmitting and receiving sound waves at frequencies higher than 20 kHz.

[0004] In particular, ultrasonic devices (including piezoelectric micromechanical ultrasonic transducers (PMUTs)) manufactured using microelectromechanical systems (MEMS) technology are widely used due to their small size, light weight, low power consumption, and high sensitivity.

[0005] Furthermore, MEMS ultrasonic devices can operate at high frequencies, even in the range of a few MHz, allowing for high resolution.

[0006] In many applications, the use of a large number of ultrasonic transducer modules can be useful, which has led to known devices comprising electronic control circuits for multiple transducer modules, which are complex and costly to manufacture.

[0007] For example, ultrasound devices such as PMUT can be used for eye tracking. The use of sound waves allows operation even under extreme conditions, such as in darkness or in the presence of bright light, and these sound waves are safe for the user's health.

[0008] Furthermore, PMUT's high operating frequency allows for the accurate detection of even very small eye movements, such as those of a few hundred micrometers.

[0009] Ultrasonic eye tracking is based on the time-of-flight measurement between the emission of sound waves and the reception of the same sound wave by the eye.

[0010] like Figure 1A and 1B As illustrated, the time of flight (and distance) measured between transmitting PMUT 1 and receiving PMUT 2 depends on the rotation of eye 3.

[0011] In fact, depending on the position (rotation) of eye 3 relative to PMUT 1 and 2, and relative to cornea 4 ( Figure 1A The measured flight time was lower than that relative to the sclera (5 ( Figure 1B (The flight time was measured.)

[0012] Therefore, the position of eye 3 can be identified based on the change in flight time measured between PMUT 1 and 2.

[0013] A pair of PMUT 1 and 2 may be sufficient to determine whether the eyes are looking to the right or left.

[0014] However, in order to follow eye movement with greater freedom, such as determining whether the eye is looking up or down, multiple pairs of PMUTs may be needed, such as even four or five pairs of PMUTs.

[0015] In known devices, each transmitting PMUT includes a dedicated driving circuit for driving the transmission of acoustic waves, and each receiving PMUT includes a dedicated receiving circuit with a corresponding amplifier for detecting the reflected acoustic waves.

[0016] In fact, in known devices, the control circuit consists of multiple transmission channels and multiple receiving channels, where each transmission channel drives a single transmission PMUT module, and each receiving channel detects the electrical signal generated by a single receiving PMUT.

[0017] As the number of ultrasonic transducers increases, the control circuit system becomes more and more complex, leading to increased manufacturing costs and energy consumption.

[0018] There is a need in the art to overcome, at least in part, the aforementioned disadvantages. Summary of the Invention

[0019] Therefore, according to the present invention, an ultrasonic device and a control method are provided.

[0020] In one embodiment, an ultrasonic device includes: a plurality of MEMS-type transmission transducers, each configured to emit a corresponding ultrasonic wave; a plurality of MEMS-type receiving transducers, each configured to generate an electrical signal in response to the detection of an impact ultrasonic wave; and a control circuit system including one or more transmission channels configured to drive the plurality of transmission transducers to emit ultrasonic waves and receiving channels configured to detect the electrical signals generated by the plurality of receiving transducers.

[0021] In one embodiment, a method for controlling an ultrasonic device, the ultrasonic device including a plurality of MEMS-type transmission transducers and a plurality of MEMS-type receiving transducers, includes: driving the plurality of transmission transducers to transmit ultrasonic waves via one or more transmission channels; and detecting electrical signals generated by the plurality of receiving transducers in response to the detection of impact ultrasonic waves via receiving channels. Attached Figure Description

[0022] To better understand the invention, embodiments thereof are now described by way of non-limiting example only with reference to the accompanying drawings, wherein:

[0023] Figure 1A and 1B Two PMUT devices are schematically shown for tracking eye movement at two different locations on the eye;

[0024] Figure 2 A block diagram of an ultrasound device is shown;

[0025] Figure 3 It shows Figure 2 A block diagram of the transducer module of the device;

[0026] Figure 4 An ultrasound device for eye tracking is shown under first usage conditions;

[0027] Figure 5 It shows Figure 4 An example of a signal received by the device under the first usage condition;

[0028] Figure 6 It is shown that under the second use condition, it is used for Figure 4 Eye-tracking devices;

[0029] Figure 7 It shows Figure 4 An example of a signal received by the device under the second usage condition;

[0030] Figure 8 It is shown that under the third use condition, it is used for Figure 4 Eye-tracking devices;

[0031] Figure 9 It shows Figure 4 An example of a signal received by the device under the third usage condition;

[0032] Figure 10 A block diagram of an ultrasound device is shown;

[0033] Figure 11 An ultrasonic device is shown; and

[0034] Figure 12 The circuit diagram of the receiving circuit of the ultrasonic device is shown. Detailed Implementation

[0035] Figure 2 An ultrasonic device 20 is shown, which includes a transducer 21 and a control circuit 22 for the transducer 21.

[0036] The transducer 21 includes multiple transmission transducer modules (particularly transmission modules 23A, 23B, and 23C) and multiple receiving transducer modules (particularly receiving modules 24A, 24B, and 24C).

[0037] Transmission modules 23A, 23B, and 23C are each configured to transmit corresponding ultrasonic waves.

[0038] Receiver modules 24A, 24B, and 23C are each configured to detect impact ultrasonic waves.

[0039] Specifically, the transmission modules 23A to 23C and the receiving modules 24A to 24C are configured to transmit / detect sound waves at frequencies on the order of several MHz (e.g., greater than or equal to 1 MHz).

[0040] Transmission modules 23A to 23C and receiving modules 24A to 24C are MEMS ultrasonic transducers, which are fabricated using microfabrication and nanofabrication techniques, such as starting from a wafer of semiconductor material.

[0041] Figure 3 A schematic diagram showing the internal structure of any one of the transmission modules 23A to 23C or the receiving modules 24A to 24C is shown; in particular, by way of example only, Figure 3 This refers to receiver module 24A. However, reference Figure 3 The content of the discussion can be applied to each of modules 23A to 23C and 24A to 24C.

[0042] The receiving module 24A includes a transducer structure 28 and a movable structure 29 that are mechanically coupled to each other.

[0043] Depending on the specific implementation and application of device 20, movable structure 29 may include one or more membranes, cantilever or other elements.

[0044] The movable structure 29 is configured to move in response to the reception of the shock wave in receiving mode.

[0045] In particular, the movable structure 29 can undergo displacement and / or deformation in response to the reception of the impact sound wave.

[0046] The transducer structure 28 is configured to undergo deformation depending on the movement of the movable structure 29, and in response, generates an electrical signal (specifically a voltage) between the two nodes 30, 31 of the receiving module 23A.

[0047] In fact, the transducer module 24A can be schematically represented as an element having at least two terminals (nodes 30, 31) from an electrical point of view.

[0048] In detail, the movable structure 29 and the transducer structure 28 can be rigidly or elastically coupled to each other.

[0049] Depending on the specific application, the transducer structure 28 can be based on piezoelectric, piezoresistive, capacitive, magnetic, or other transducer mechanisms.

[0050] In the following text, reference will be made to a transducer structure 28 based on a piezoelectric transducer mechanism, which allows for high sensitivity and low energy consumption.

[0051] It will be apparent to those skilled in the art that, with reference to Figure 3 The discussion of receiving module 24A can also be applied to each of the receiving modules 24B and 24C and each of the transmitting modules 23A to 23C.

[0052] When transmission modules 23A to 23C operate in transmit mode, transducer structure 28 is configured to undergo deformation and / or displacement according to an electrical drive signal (e.g., voltage) received between nodes 30 and 31. Movable structure 29, mechanically coupled to transducer structure 28, is configured to move in response to the deformation and / or movement of transducer structure 28, and generates a corresponding acoustic wave in response.

[0053] Depending on the specific implementation, the transducer structure 28 may include one or more transducer elements, and the movable structure 29 may include one or more movable elements.

[0054] In particular, each of the receiving modules 24A to 24C and the transmitting modules 23A to 23C can be a PMUT device.

[0055] For example, if each of the transducer modules 23A to 23C, 24A to 24C is a PMUT device, the transducer structure 28 and the movable structure 29 may include an array of transducer elements and movable elements.

[0056] Refer again Figure 2 From an electrical perspective, multiple receiving transducer modules 24A to 24C can be connected in series.

[0057] In detail, receiving module 24B has a corresponding node 30 connected to node 31 of receiving module 24A and a corresponding node 31 connected to node 30 of receiving module 24C.

[0058] Node 31 of receiver module 24C can be coupled to a reference potential, such as ground.

[0059] Node 30 of the receiving module 24A is coupled (e.g., directly connected) to the control circuit 22.

[0060] From an electrical perspective, multiple transmission transducer modules 23A to 23C are arranged in parallel.

[0061] In detail, transmission modules 23A to 23C have corresponding nodes 30 and corresponding nodes 31 that are connected to each other.

[0062] Node 30 of transmission modules 23A to 23C is coupled (e.g., directly connected) to control circuit 22. Node 31 of transmission modules 23A to 23C is coupled (e.g., directly connected) to a reference potential node, such as ground.

[0063] The spatial arrangement of the transmission modules 23A to 23C and the receiving modules 24A to 24C (especially the relative arrangement between the transmission modules 23A to 23C and the receiving modules 24A to 24C) can vary depending on the specific application of the ultrasonic equipment 20, for example, as shown in the following reference. Figure 4 and 11 Detailed description.

[0064] The control circuit 22 includes a drive circuit 33 coupled to the transmission modules 23A to 23C and configured to drive the transmission modules 23A to 23C to transmit sound waves; and a receiver circuit 34 coupled to the receiver modules 24A to 24C and configured to read the electrical signals generated by the receiver modules 24A to 24C in response to the detection of sound waves.

[0065] Specifically, the receiving circuit 34 is coupled to node 30 of the receiving module 24A. The receiving circuit 34 may include an amplifier, such as a low-noise amplifier (LNA).

[0066] In fact, the receiving circuit 34 includes a single receiving channel, which is configured to amplify and read the signals generated by all the receiving modules 24A to 24C.

[0067] exist Figure 2 In one embodiment, the drive circuit 33 includes a single transmission channel configured to drive all transmission modules 23A to 23C.

[0068] Furthermore, the control circuit 22 also includes a control module 35, which is coupled to the drive circuit 33 and the receiving circuit 34.

[0069] The control module 35 can control the drive circuit 33 and receive amplified electrical signals from the receiving circuit 34.

[0070] The control module 35 can be configured to determine one or more time-of-flight values ​​between the transmission modules 23A to 23C transmitting sound waves and the receiving modules 24A to 24C receiving sound waves.

[0071] The control module 35 can also be configured to process the measured time of flight and, based on the measured time of flight, determine further quantities or parameters depending on the specific application of the ultrasonic device 20.

[0072] In detail, the transmission modules 23A to 23C and the receiving modules 24A to 24C can be configured to form multiple TX-RX pairs, also referred to below as transducer pairs, wherein each transducer pair includes one transmission transducer of the transmission transducers 23A to 23C and one receiving transducer of the receiving transducers 24A to 24C.

[0073] In practice, the receiving module (e.g., receiving module 24A) of each transducer pair can be configured to detect the reception of acoustic waves emitted by the corresponding transmission module (e.g., transmission module 23A).

[0074] For example, the transmission module (e.g., 23A) and the receiving module (e.g., 24A) of the transducer pair are configured to have the same operating frequency.

[0075] In particular, Figure 2 In one embodiment, the first transducer pair includes a transmission transducer module 23A and a receiving transducer module 24A, the second transducer pair includes a transmission transducer module 23B and a receiving transducer module 24B, and the third transducer pair includes a transmission transducer module 23C and a receiving transducer module 24C.

[0076] The control module 35 can be configured to measure the corresponding flight time for each pair.

[0077] In detail, the control module 35 can be configured to measure the flight time of each transducer pair (23A, 24A; 23B, 24B; and 23C, 24C) using time division multiplexing (TDM) or frequency division multiplexing (FDM) techniques.

[0078] The TX-RX pairs can have the same operating frequency or different operating frequencies, depending on whether the control circuit 22 is configured to perform TDM or FDM.

[0079] In practice, when in use, the ultrasonic device 20 can be configured to measure relative to Figure 2 The flight time of the target object, which is not shown, is located near the ultrasonic device 20.

[0080] In use, the drive circuit 33 provides drive signals to the transmission modules 23A to 23C, causing each of them to emit corresponding sound waves 40, 41 and 42 respectively.

[0081] exist Figure 2 In one embodiment, the drive circuit 33 forms a single drive channel and the transmission modules 23A to 23C are connected in parallel with each other, and the transmission modules 23A to 23C simultaneously emit corresponding sound waves 40, 41, and 42.

[0082] In this case, the transducer pairs (23A, 24A; 23B, 24B; and 23C, 24C) can be arranged at different distances from the target.

[0083] Sound waves 40, 41, and 42 propagate from the corresponding transmission modules 23A, 23B, and 23C toward the target and are reflected by the target. The reflected waves then propagate toward the receiving modules 24A to 24C, and each receiving module generates a corresponding electrical receiving signal 43, 44, and 45 in response to the reception of the reflected wave associated with the corresponding transmission module 23A to 23C.

[0084] Since the receiving circuit 34 is coupled to all three receiving transducers 24A to 24C, the receiving circuit 34 receives individual signals indicating electrical signals 43, 44, and 45. Therefore, the individual signal received by the receiving circuit 34 can be defined as the overall signal indicating the electrical received signals 43, 44, and 45 generated by the receiving transducers 24A to 24C.

[0085] Furthermore, since the transducer pairs (23A, 24A; 23B, 24B; and 23C, 24C) are arranged at different distances from each other relative to the target, the received signals include electrical received signals 43, 44, 45 that are spaced apart from each other in time.

[0086] Therefore, the control module 35 can distinguish the electrical received signals 43, 44, and 45 from each other starting from the received signals.

[0087] Therefore, the control module 35 can determine the corresponding flight time based on the time distance between the sound waves 40 to 42 transmitted by the transmission modules 23A to 23C and the corresponding reflected components received by the receiving modules 24A to 24C.

[0088] Even with a large number of transducer modules, the fact that receiver modules 24A to 24C are coupled to a single receiver channel allows for a simplified design of receiver circuit 34, reducing its manufacturing cost and energy consumption.

[0089] Therefore, the ultrasound device 20 can be efficiently used in applications such as eye tracking, gesture recognition, proximity sensors, and other general applications based on time-of-flight measurements.

[0090] Figure 4 An ultrasound device 120 is shown, configured to detect movement of an eye 116 having a sclera 117 and a cornea 118.

[0091] The ultrasound device 120 can be incorporated into an individual wearable device, such as glasses, augmented or virtual reality headsets, or other similar devices.

[0092] The ultrasonic device 120 has a similar structure to that discussed for the ultrasonic device 20; therefore, common elements are indicated by the same reference numerals and will not be described in further detail. Thus, unless otherwise specified, detailed descriptions of such elements are provided in the appendix concerning... Figure 2 The content described.

[0093] The ultrasonic device 120 includes a control circuit 22, which includes a drive circuit 33, a receiving circuit 34, and a control module 35.

[0094] In the same embodiment, the driving circuit 33 includes a single transmission channel, and the receiving circuit 34 includes a single receiving channel.

[0095] The ultrasonic device 120 also includes a transducer 121, which includes multiple transmission transducer modules and multiple receiving transducer modules.

[0096] In detail, the transducer device 121 includes two TX-RX transducer pairs 123 and 124, wherein transducer pair 123 includes a transmission transducer module 23A and a receiving transducer module 24A, and transducer pair 124 includes a transmission transducer module 23B and a receiving transducer module 24B.

[0097] Depending on the specific application, modules 23A and 24A of transducer pair 123 can be formed in the same die or in different dies.

[0098] Depending on the specific application, modules 23B and 24B of transducer pair 124 can be formed in the same die or in different dies.

[0099] For reference Figure 2 As discussed, transmission modules 23A and 23B are connected in parallel to each other and connected to the drive circuit 33.

[0100] For reference Figure 2 As discussed, receiving modules 24A and 24B are connected in series with each other and connected to receiving circuit 34.

[0101] The ultrasound device 120 is configured to detect the orientation of the eye 116 based on time-of-flight measurements associated with transducer pair 123 and time-of-flight measurements associated with transducer pair 124.

[0102] The ultrasonic device 120 is configured to perform time division multiplexing (TDM), that is, to enable one of the receiving transducers (specifically) to transmit signals via a receiving transducer module. Figure 4 The electrical signal generated by module 24B in the receiving transducer module is relative to another receiving transducer module in the receiving transducer module (especially...). Figure 4The electrical signal generated by module 24A in the transducer pair 120 has a time delay. In this way, the ultrasound device 120 can use a single receiving channel to measure the time of flight associated with transducer pair 123 and the time of flight associated with transducer pair 124.

[0103] In this respect, in this embodiment, the transducer pairs 123 and 124 are arranged at different distances from each other relative to the eye 116.

[0104] Specifically, the transducer pair 123 is configured to be arranged at a nominal distance d2 from the eye 116, while the transducer pair 124 is configured to be arranged at a nominal distance d1 from the eye 116, which is different from the nominal distance d2.

[0105] exist Figure 4 In the embodiment, distance d1 is greater than distance d2.

[0106] In fact, the ultrasound device 120 is configured such that, under at least one rotational condition of the eye 116, the transducer pairs 123, 124 are arranged relative to the eye 116 such that the measurable flight time between modules 23A, 24A is lower than the measurable flight time between modules 23B, 24B.

[0107] exist Figure 4 In one embodiment, the rotation condition of eye 116 is a condition in which eye 116 is not pointed at transducer pair 123, 124; that is, a condition in which cornea 118 is not pointed at transducer pair 123, 124. In other words, in Figure 4 Under the indicated usage conditions, the sound waves emitted by the transmission modules 23A and 23B propagate toward the sclera 117 of the eye 116 and are reflected by the sclera 117 toward the receiving modules 24A and 24B.

[0108] In detail, distance d1 can be defined as a function of the distance between transmission module 23B and eye 116 and the distance between receiving module 24B and eye 116; and distance d2 can be defined as a function of the distance between transmission module 23B and eye 116 and the distance between receiving module 24B and eye 116.

[0109] like Figure 6 As shown, transducer pairs 123 and 124 are arranged relative to eye 116 such that when eye 116 is pointed at transducer pair 124, sound wave 41 emitted by transducer module 23B propagates toward cornea 118, but wave 131 reflected by cornea 118 does not propagate toward receiver module 24B.

[0110] like Figure 8As shown, transducer pairs 123 and 124 are arranged relative to eye 116 such that when eye 116 is pointed at transducer pair 123, sound wave 40 emitted by transducer module 23A propagates toward cornea 118, but wave 130 reflected by cornea 118 does not propagate toward receiver module 24A.

[0111] Refer again Figure 4 When in use, the drive circuit 33 drives the transmission modules 23A and 23B to emit sound waves 40 and 41 respectively.

[0112] exist Figure 4 In the scene, eye 116 is neither pointing at transducer pair 123 nor at transducer pair 124.

[0113] Therefore, sound waves 40 and 41 both impact the sclera 117 of the eye 116, and then reflect towards the receiving module 24A and the receiving module 24B, respectively.

[0114] In response to the reception of the corresponding reflected wave 130, the receiving module 24A generates a corresponding electrical signal R1.

[0115] In response to the reception of the corresponding reflected wave 131, the receiving module 24B generates a corresponding electrical signal R2.

[0116] Electrical signals R1 and R2 are detected by receiving circuit 34.

[0117] Since transducer pair 124 is positioned at a greater distance from eye 116 than transducer pair 123, the electrical signal R2 generated by receiver module 24B is delayed relative to the electrical signal R1 generated by receiver module 24A.

[0118] Therefore, the control module 35 is able to distinguish between electrical signal R1 and electrical signal R2 within a single signal received by the receiving circuit 34.

[0119] Figure 5 An example of the overall signal received and detected by the receiving circuit 34 is shown, where the peaks associated with the electrical signals R1 and R2 are visible.

[0120] The peak associated with signal R1 precedes the peak associated with signal R2 in time.

[0121] Therefore, the control module 35 can identify the peaks associated with signals R1 and R2, for example, using signal processing techniques known per se, and determine the orientation of the eye 116 in response.

[0122] In particular, Figure 5 In the example, control module 35 determines that the flight time associated with peak R1 is approximately 200 µs and the flight time associated with peak R2 is approximately 300 µs.

[0123] exist Figure 4 In the scenario described, the control module 35 determines that the eye 116 is neither pointing to the transducer pair 123 nor to the transducer pair 124.

[0124] Furthermore, the control module 35 can also be configured to determine a more accurate position of the eye 116 (e.g., the degree of rotation of the eye 116 relative to the transducer pairs 123 and / or 124) based on the time distance between the two peaks R1 and R2, the width of the peaks, the intensity of the peaks, or other similar parameters that can be derived from the analysis of signals R1 and R2, depending on the specific algorithm implemented.

[0125] refer to Figure 6 During use, eye 116 points to transducer pair 124.

[0126] Then, the sound wave 40 impacts the sclera 117 of the eye 116 and is reflected toward the receiving module 24A.

[0127] In response to the reception of the corresponding reflected wave 130, the receiving module 24A generates a corresponding electrical signal R1.

[0128] Conversely, sound wave 41 impacts the cornea 118 of eye 116, thus the reflected wave 131 is misaligned with the receiving module 24B.

[0129] exist Figure 6 In this scenario, the receiving module 24B does not detect any reflected wave, and therefore does not generate an electrical signal R2 that can be detected by the receiving circuit 34. For example, the receiving module 24B may generate an electrical signal depending on the specific bias or configuration, but this signal is below noise or below a certain threshold.

[0130] Therefore, in this case, the receiving circuit 34 detects only the electrical signal R1 in the received signal.

[0131] Figure 7 An example of the overall signal received and detected by the receiving circuit 34 is shown, where the peak associated with the electrical signal R1 is visible.

[0132] Therefore, the control module 35 can identify the peak value associated with signal R1.

[0133] Control module 35 determines the flight time associated with peak value R1 (in Figure 7 (Approximately 200 µs in the example) Refer to transducer pair 123.

[0134] In response to the detection of a unique peak R1 associated with transducer pair 123, control circuit 35 determines that eye 116 is pointing at transducer pair 124.

[0135] refer to Figure 8When in use, eye 116 points to transducer pair 123.

[0136] Then, the sound wave 41 impacts the sclera 117 of the eye 116 and is reflected toward the receiving module 24B of the transducer pair 124.

[0137] In response to the reception of the corresponding reflected wave 131, the receiving module 24B generates a corresponding electrical signal R2.

[0138] Conversely, sound wave 40 impacts the cornea 118 of eye 116, thus the reflected wave 130 is misaligned with the receiving module 24A.

[0139] exist Figure 8 In this scenario, the receiving module 24A does not detect any reflected wave, and therefore does not generate an electrical signal R1 that can be detected by the receiving circuit 34. For example, the receiving module 24A may generate an electrical signal depending on the specific bias or configuration, but this signal is below noise or below a certain threshold.

[0140] Therefore, in this case, the receiving circuit 34 detects only the electrical signal R2 in the received signal.

[0141] Figure 9 An example of the overall signal received and detected by the receiving circuit 34 is shown, where the peak associated with the electrical signal R2 is visible.

[0142] Therefore, the control module 35 can identify the peak value associated with signal R2.

[0143] Control module 35 determines the flight time associated with peak value R2 (in Figure 9 (Approximately 300 µs in the example) Refer to the farthest sensor pair, i.e., transducer pair 124.

[0144] In response to the detection of a unique peak R2 associated with transducer pair 124, control circuit 35 determines that eye 116 is pointing at transducer pair 123.

[0145] Therefore, the ultrasound device 120 allows the use of multiple transmission and reception modules to track the movement of the eye 116.

[0146] The fact that receiving modules 24A and 24B are connected to the same receiving circuit means that a single receiving channel can be used to perform tracking of the movement of the eye 116, thereby simplifying the control circuit 22.

[0147] Therefore, device 120 can have a simple design, low design cost and low energy consumption.

[0148] Figure 10 An ultrasonic device 220 according to different embodiments is shown.

[0149] Ultrasonic device 220 has a general structure similar to that of devices 20 and 120; therefore, common elements are indicated by the same reference numerals and will not be described in further detail. Thus, unless otherwise specified, detailed descriptions of such elements are provided in reference to the... Figure 2 Or the content described in 4.

[0150] The ultrasonic device 220 includes a control circuit 222, which includes a drive circuit, in this embodiment including three transmission drivers 233A, 233B, and 233C; a receiving circuit 34; and a control module 235.

[0151] Therefore, the drive circuit includes three drive channels.

[0152] The receiving circuit 34 includes a receiving analog front end 240 coupled to a series circuit formed by receiving modules 24A to 24C and an analog-to-digital converter 241.

[0153] In fact, in the same embodiment, the receiving circuit 34 includes a single receiving channel.

[0154] The ultrasound device 220 also includes a transducer 221, which includes a plurality of transmission transducer modules 223A to 223C and a plurality of receiving transducer modules 24A to 24C.

[0155] Transmitter modules 223A to 223C and receiver modules 24A to 24C can be organized into TX-RX using transducers that each include a transmit module and a receive module.

[0156] For reference Figure 2 As discussed, receiving modules 24A and 24B are connected in series with each other and connected to receiving circuit 34.

[0157] In this embodiment, transmission modules 233A, 233B, and 233C are driven by corresponding drivers 233A, 233, and 233C, respectively, so that transmission modules 223A, 223B, and 223C can be driven independently of each other.

[0158] In detail, the ultrasound device 220 is configured to perform frequency division multiplexing (FDM).

[0159] In this respect, the transducers TX-RX are configured to transmit and receive sound waves in different frequency bands, especially when the corresponding frequency bands do not overlap.

[0160] For example, transmission module 223A and receiving module 24A can form a first transducer pair TX-RX_1; transmission module 223B and receiving module 24B can form a second transducer pair TX-RX_2; and transmission module 223C and receiving module 24C can form a third transducer pair TX-RX_3, which operate in separate frequency bands.

[0161] The control module 235 includes three processing channels, each including a bandpass filter ( Figure 10 Filters 244A, 244B and 244C) and Time-of-Flight Processing Module ( Figure 10 TOF modules 245A, 245B, and 245C.

[0162] The bandpass filters 244A to 244C have different passbands from each other, and each passband corresponds to the frequency band of the corresponding transducer pair TX-RX_1, TX-RX_2, TX-RX_3.

[0163] Each of the TOF processing modules 245A to 245C is configured to determine the time of flight (TOF1, TOF2, TOF3) associated with the corresponding transducer pairs TX-RX_1, TX-RX_2, and TX-RX_3, starting from the filtered signal provided by the corresponding bandpass filters 244A to 244C.

[0164] The control module 246 also includes a processing unit, such as a DSP 246, which is configured to process the measured time of flight (TOF1, TFO2, TOF3) and determine further quantities or parameters depending on the specific application of the ultrasound device 220.

[0165] Even though the receiving circuit 34 has only one receiving channel for all receiving modules 24A to 24C, the frequency multiplexing provided by the ultrasonic device 220 allows the ultrasonic device 220 to distinguish the signals received by the receiving circuit 34.

[0166] Therefore, even when the ultrasonic device 220 has a large number of receiving modules, the ultrasonic device 220 can still have low manufacturing costs and low energy consumption.

[0167] Those skilled in the art will appreciate that device 220 can be used in a wide range of applications, including eye tracking, gesture recognition, proximity sensors, etc.

[0168] For example, with regard to Figure 4 , 6 Similar to that discussed in section 8, device 220 can be used to detect the orientation of eye 116 and track its movement. In this respect, the frequency multiplexing implemented by device 220 means that the transducer pair TX-RX can be positioned at the same distance from eye 116.

[0169] Figure 11An ultrasonic device 320 according to yet another embodiment is shown, which includes a transducer 321 and a control circuit 322.

[0170] Ultrasonic device 320 has a general structure similar to that of ultrasonic device 120; therefore, common elements are indicated by the same reference numerals and will not be described in further detail. Thus, unless otherwise specified, detailed descriptions of such elements are provided in the appendix. Figure 4 The content described.

[0171] The transducer 321 includes four transmission transducer modules 23A to 23D and four receiving transducer modules 24A to 24D.

[0172] In detail, the transducer modules are organized in a manner that forms four TX-RX pairs, also referred to below as transducer pairs 323, 324, 325, and 326.

[0173] Transmission modules 23A to 23D are electrically arranged in parallel with each other, similar to the reference. Figure 2 As described.

[0174] Receiver modules 24A to 24D are electrically arranged in series with each other, similar to the reference. Figure 2 As described.

[0175] Furthermore, in this embodiment, the device 320 is configured to determine the morphology of the surface S of a target body arranged at a certain distance from the transducer 321.

[0176] In detail, transducers 323 to 326 are arranged along the contour of surface S at a certain distance from surface S.

[0177] For each transducer pair 323 to 326, the corresponding transmission modules 23A to 23D and receiving modules 24A to 24D are arranged such that, in use, the acoustic waves emitted by each of the transmission modules 23A to 23D impact the corresponding portion of the surface S and are reflected back to the corresponding receiving modules 24A to 24D.

[0178] The control circuit 322 includes a drive circuit 33 configured to drive the transmission modules 23A to 23D and a receiving circuit 34 configured to detect the electrical signals generated by the receiving modules 24A to 24D.

[0179] The control circuit 322 also includes a control module 335 configured to determine the flight time of each transducer pair among the sensor pairs 323 to 326, and determine the distance between each transducer pair 323 to 326 and the surface S based on the flight time, and then determine the morphology of the surface S in response.

[0180] Figure 12A detailed embodiment of the receiving circuit 434, which can be used in any of the above-described ultrasonic devices, is shown.

[0181] To make the explanation simple and clear, the receiving circuit 434 will be described with reference to the receiving modules 24A to 24C of the ultrasonic device 220.

[0182] The receiving circuit 434 includes a receiving analog front end 240.

[0183] The receiving circuit 434 also includes bias circuitry for the receiving modules 24A to 24C, which is configured to apply a bias voltage, specifically a DC voltage, to each of the receiving modules 24A to 24C.

[0184] A bias voltage can be applied to the ends 30, 31 of each receiver module 24A to 24C.

[0185] Specifically, the receiving circuit 434 includes a bias voltage generator 440, which is configured to generate a bias voltage V. BIAS ; and voltage divider network 441.

[0186] The receiving modules 24A to 24C are arranged such that they form a series circuit together with the voltage divider network 441 between the bias node 442 and the reference potential node (here grounded).

[0187] In detail, the voltage divider network 441 includes multiple resistors 443A, 443B, and 443C, each of which is coupled in parallel to the corresponding receiving module 24A, 24B, and 24C.

[0188] Resistors 443A, 443B, and 443C have resistors R1, R2, and R3, respectively. Resistors R1, R2, and R3 can be equal; this allows for a bias voltage V. BIAS They are evenly distributed between receiving modules 24A and 24C.

[0189] A resistor 445 with resistor RB can be arranged between voltage generator 440 and bias node 442 to facilitate DC coupling between voltage generator 440 and receiving modules 24A to 24C. In particular, resistor RB can be much lower than each of resistors R1, R2, R3.

[0190] Capacitor 446 can be arranged between bias node 442 and receiving analog front-end 240, which allows receiving analog front-end 240 to be biased by bias voltage V. BIAS Decoupling; when the receiving analog front-end 240 is configured to operate below the bias voltage V BIAS This can be useful when operating at low voltage.

[0191] Finally, it is clear that modifications and variations can be made to the content already described and illustrated without departing from the scope of the invention, as defined in the appended claims.

[0192] When an ultrasound device is configured to use time-division multiplexing (TDM), such as reference ultrasound device 120, the time division of signals R1 and R2 generated by receiving modules 24A and 24B can be achieved by independently driving two transmission modules 23A and 23B, thereby introducing a delay between the emission of sound waves 40 and 41. This can be achieved, for example, by using two drive channels in the drive circuit. In practice, this allows transducer pairs 123 and 124 to be positioned at the same nominal distance from the eye 116, simultaneously acquiring the time delay of the electrical signals generated by receiving transducer modules 24A and 24B, thus ensuring that control module 35 can distinguish signals R1 and R2. In fact, in this case, the time distance between signals R1 and R2 is obtained by delaying the emission of sound waves 40 and 41 relative to each other.

[0193] For example, with reference Figures 2 to 12 The descriptions differ, but from an electrical perspective, the receiving transducers 24A to 24C can be coupled to each other to form a circuit other than a series circuit, provided that the signal received by the receiving circuit 34 or 434 indicates the electrical signal generated by the multiple receiving transducers. For example, when the receiving circuit is configured to read a current signal instead of a voltage signal, from an electrical perspective, the receiving transducers 24A to 24C can be coupled to each other to form a parallel circuit.

[0194] Alternatively or additionally, when the drive circuit 33 is formed by a single transmission channel, from an electrical perspective, the transmission transducer modules 23A to 23C can be coupled to each other to form a circuit other than a parallel circuit. For example, when the drive circuit 33 is configured to drive the transmission transducer modules 23A to 23C by a current signal, the transmission transducer modules can be coupled to form a series circuit.

[0195] For example, an ultrasound device can be configured, depending on the specific application and the specific target, to determine parameters or physical quantities associated with the target, starting from the time of flight measured between the emission of ultrasound waves and the detection of ultrasound waves reflected from the target, that are different from those described above (i.e., different from the position / movement of an individual's eye and the morphology of the target's surface).

[0196] For example, an ultrasound device may include a different number of receiving and / or transmitting modules than those shown.

[0197] For example, control circuits can be formed from circuits, modules, units, etc., and depending on the specific application, they can be implemented using digital, analog, or mixed-signal circuits.

[0198] For example, depending on the specific application, one or more of the drive circuit, receiver circuit, and control module may be implemented, in whole or in part, through dedicated hardware circuitry (such as ASICs or FPGAs) and / or through software modules.

[0199] For example, depending on the specific implementation and application, the transducer and control circuitry can be formed entirely or partially in the same die of semiconductor material, or they can be distributed in two or more dies.

[0200] Finally, the different embodiments described can be combined to provide other solutions.

Claims

1. An ultrasonic device, comprising: Multiple transmission transducer modules of the microelectromechanical system (MEMS) type, each transmission transducer module is configured to emit a corresponding ultrasonic wave; Multiple MEMS-type receiver transducers, each configured to generate an electrical signal in response to the detection of impact ultrasonic waves; The plurality of receiving transducer modules are connected in series with each other; as well as A control circuit system includes: one or more transmission channels configured to drive the plurality of transmission transducer modules to transmit ultrasonic waves; And a single receiving channel configured to detect the electrical signal generated by the plurality of receiving transducers, wherein the single receiving channel is connected to the plurality of receiving transducers connected in series with each other.

2. The ultrasonic device of claim 1, wherein the control circuit system is configured to: starting from one or more of the detected electrical signals, determine at least one time of flight between the transmission of at least one ultrasonic wave by the plurality of transmission transducers and the detection of at least one ultrasonic wave by the plurality of receiving transducers.

3. The ultrasonic device of claim 2, wherein the control circuitry is configured to implement frequency division multiplexing to determine, starting from one or more of the detected electrical signals, a plurality of flight times between the ultrasonic waves emitted by the plurality of transmission transducers and the ultrasonic waves detected by the plurality of receiving transducers.

4. The ultrasonic device of claim 2, wherein the control circuitry is configured to implement time-division multiplexing to determine, starting from one or more of the detected electrical signals, multiple flight times between the ultrasonic waves emitted by the plurality of transmit transducer modules and the ultrasonic waves detected by the plurality of receive transducer modules.

5. The ultrasound device of claim 2, wherein the control circuitry is configured to: detect the at least one time of flight relative to a target body, wherein the target body is an individual's eye, and determine the orientation or position of the eye based on the at least one time of flight.

6. The ultrasonic device according to claim 5, comprising a plurality of transducer pairs, the plurality of transducer pairs comprising at least a first transducer pair and a second transducer pair, wherein the first transducer pair comprises one of the plurality of transmission transducer modules and one of the plurality of receiving transducer modules, wherein the second transducer pair comprises another of the plurality of transmission transducer modules and another of the plurality of receiving transducer modules; The control circuitry is configured to determine a first flight time associated with the first transducer pair and a second flight time associated with the second transducer pair; and At least one of the first transducer pair and the second transducer pair is configured such that, in use, when the eye is pointed at the at least one of the first transducer pair and the second transducer pair, the ultrasonic wave emitted by the corresponding transmitting transducer module propagates toward the cornea of ​​the eye, and the corresponding reflected ultrasonic wave does not propagate toward the corresponding receiving transducer module.

7. The ultrasonic device according to claim 5, comprising a plurality of transducer pairs, the plurality of transducer pairs comprising at least a first transducer pair and a second transducer pair, wherein the first transducer pair comprises one of the plurality of transmission transducer modules and one of the plurality of receiving transducer modules, wherein the second transducer pair comprises another of the plurality of transmission transducer modules and another of the plurality of receiving transducer modules; The control circuitry is configured to determine a first flight time associated with the first transducer pair and a second flight time associated with the second transducer pair; and At least one of the first transducer pair and the second transducer pair is configured such that, in use, when the eye is not pointed at the at least one of the first transducer pair and the second transducer pair, the ultrasonic wave emitted by the corresponding transmitting transducer module propagates toward the sclera of the eye, and the corresponding reflected ultrasonic wave propagates toward the corresponding receiving transducer module.

8. The ultrasonic device according to claim 1, comprising a plurality of transducer pairs, the plurality of transducer pairs comprising at least a first transducer pair and a second transducer pair, wherein the first transducer pair comprises one of the plurality of transmission transducer modules and one of the plurality of receiving transducer modules, wherein the second transducer pair comprises another of the plurality of transmission transducer modules and another of the plurality of receiving transducer modules; The control circuitry is configured to determine a first flight time associated with the first transducer pair and a second flight time associated with the second transducer pair.

9. The ultrasonic device of claim 8, wherein the control circuitry is configured to implement time-division multiplexing such that the electrical signal generated by the receiving transducer module of one of the first transducer pair and the second transducer pair is time-delayed relative to the electrical signal generated by the receiving transducer module of the other of the first transducer pair and the second transducer pair.

10. The ultrasonic device of claim 9, wherein the first transducer pair is configured to be arranged at a first nominal distance from the target body to measure the first time of flight relative to the target body, and wherein the second transducer pair is configured to be arranged at a second nominal distance from the target body to measure the second time of flight relative to the target body, the first distance being different from the second distance.

11. The ultrasonic device of claim 8, wherein the control circuit system is configured to implement frequency division multiplexing, wherein the first transducer pair is configured to operate at an operating frequency different from the operating frequency of the second transducer pair.

12. The ultrasonic device according to claim 1, wherein at least one of the plurality of receiving transducers and the plurality of transmitting transducers comprises a piezoelectric micromechanical ultrasonic transducer (PMUT) device.

13. The ultrasound device of claim 1, wherein the series-connected receiving transducer modules generate a total signal, the total signal indicating the electrical signal generated by the receiving transducer modules for application to the receiving channel.

14. The ultrasonic device of claim 1, wherein the control circuit system includes a transmission channel configured to drive the plurality of transmission transducer modules to transmit ultrasonic waves.

15. The ultrasonic device of claim 1, wherein the transmission transducer modules are coupled to each other to form a parallel circuit.

16. The ultrasound device of claim 1, wherein the receiving channel includes a bias circuit coupled to the plurality of receiving transducers and configured to apply a bias voltage to each of the receiving transducers.

17. A method for controlling an ultrasonic device, the ultrasonic device comprising a plurality of transmission transducer modules of the microelectromechanical system (MEMS) type and a plurality of receiving transducer modules of the MEMS type, the method comprising: The plurality of transmission transducer modules are driven by one or more transmission channels to transmit ultrasonic waves; The plurality of receiving transducer modules are connected in series with each other; as well as The electrical signal generated by the plurality of receiver transducers connected in series in response to the detection of the impact ultrasonic wave is detected by a single receiver channel.

18. The method of claim 17, further comprising: Starting from one or more of the detected electrical signals, determine at least one time of flight between the transmission of at least one ultrasonic wave by the plurality of transmission transducers and the detection of at least one ultrasonic wave by the plurality of receiving transducers.

19. The method of claim 17, comprising: Frequency division multiplexing is performed to detect multiple times of flight between the ultrasonic waves emitted by the plurality of transmit transducer modules and the ultrasonic waves detected by the plurality of receive transducer modules, based on the detected electrical signals.

20. The method of claim 17, comprising: Time-division multiplexing is performed to detect multiple times of flight between the ultrasonic waves emitted by the plurality of transmit transducer modules and the ultrasonic waves detected by the plurality of receive transducer modules, based on the detected electrical signals.

21. The method of claim 17, wherein the ultrasonic waves are emitted in the direction of the target body, and the receiving transducer module is configured to detect the ultrasonic waves emitted by the transmitting transducer module and reflected by the target body. The method further comprises: At least one parameter associated with the target body is determined based on one or more flight times detected between the emission of the ultrasonic wave and the detection of the reflected ultrasonic wave.

22. The method of claim 21, wherein the target body is an eye, and the parameter associated with the target body includes the orientation or position of the eye.

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