Ultrasound matrix imaging equipment

Abstract

The present invention relates to an ultrasonic imaging device (100), comprising a line (L i ) and columns (C j ) are provided with a plurality of ultrasonic transducers (101) arranged in a matrix, each transducer having a first electrode (E1) and a second electrode (E2), wherein the first electrodes of the transducers in the same row are connected to each other, and the second electrodes of the transducers in the same column are connected to each other.

Description

[0001] This patent application claims the benefit of priority from French patent application FR 19 / 06515, which is incorporated herein by reference. Technical Field

[0002] The present disclosure relates to the field of ultrasound imaging and, more particularly, is directed to an apparatus comprising an array of ultrasound transducers and electronic circuitry for controlling these transducers. Background Art

[0003] Ultrasonic imaging equipment conventionally includes a plurality of ultrasonic transducers and electronic control circuits connected to the transducers. In operation, the transducer assembly is placed in front of a subject whose image is to be acquired. The electronic device is configured to apply an electrical excitation signal to the transducer so that ultrasonic waves are emitted by the transducer toward the subject to be analyzed. The ultrasonic waves emitted by the transducer are reflected by the subject to be analyzed (through its internal and / or surface structures) and then return to the transducer, which converts them back into electrical signals. The electrical response signals are read by the electronic control circuit and can be stored and analyzed to derive information related to the subject under investigation.

[0004] In the case of a two-dimensional image acquisition device, the ultrasound transducers can be arranged in a linear array, or in the case of a three-dimensional image acquisition device, in an array. In the case of a two-dimensional image acquisition device, the acquired image represents, on the one hand, a cross-section of the subject under investigation in a plane defined by the alignment axes of the transducers in the linear array, and, on the other hand, a cross-section of the subject under investigation in a plane defined by the emission directions of the transducers. In the case of a three-dimensional image acquisition device, the acquired image represents a volume defined by the two alignment directions of the transducers in the array and the emission direction of the transducers.

[0005] In three-dimensional image acquisition devices, devices known as fully populated (in which each transducer in the array is individually addressable) can be distinguished from devices known as row-column addressed or RCA (in which the transducers in the array are addressable both in rows and in columns).

[0006] Fully populated devices offer greater flexibility in shaping the ultrasound beam in both transmit and receive modes. However, the electronics for controlling the array are complex, and the number of transmit / receive channels required for an array of M rows and M columns is equal to M*N. Furthermore, the signal-to-noise ratio is typically relatively low because each transducer has a smaller surface area exposed to ultrasound waves.

[0007] RCA-type devices use algorithms to form different ultrasound beams. With fully populated devices, the potential for beamforming may be reduced. However, the electronics for controlling the array are significantly simplified, reducing the number of required transmit / receive channels to M+N for an array with M rows and N columns. Furthermore, the signal-to-noise ratio is improved during the transmit and receive phases due to the interconnection of the transducers in each row or column.

[0008] Row-column addressed (RCA) three-dimensional image acquisition devices are more particularly considered herein. Summary of the Invention

[0009] An object of the embodiment is to provide a three-dimensional ultrasound image acquisition device that overcomes all or part of the disadvantages of the known devices.

[0010] To this end, this embodiment provides an ultrasonic imaging device, including:

[0011] a plurality of ultrasound transducers arranged in an array of rows and columns, each transducer comprising a first electrode and a second electrode, the first electrodes of the transducers in the same row being connected to each other and the second electrodes of the transducers in the same column being connected to each other;

[0012] a transmit circuit, a receive circuit, and a switch for each row, the switch being configurable to connect the first electrodes of the transducers in the row to the transmit circuit of the row in a first configuration and to connect the first electrodes of the transducers in the row to the receive circuit of the row in a second configuration;

[0013] a transmit circuit, a receive circuit, and a switch for each column, the switch being configurable to connect the second electrodes of the transducers in the column to the transmit circuit of the column in a first configuration, and to connect the second electrodes of the transducers in the column to the receive circuit of the column in a second configuration; and

[0014] - a control circuit configured to:

[0015] In a first transmit phase, controlling the switches of the row and column to a first configuration, controlling the transmit circuitry of the row to apply a DC bias signal to the first electrodes of the transducers in the row, and controlling the transmit circuitry of the column to apply a variable excitation signal to the second electrodes of the transducers in the column; and / or

[0016] In a first receiving phase, the switches of the row and column are controlled to a first configuration and a second configuration, respectively, the transmit circuit of the row is controlled to apply a DC bias signal to the first electrode of the transducer in the row, and the receive circuit of the column is controlled to read the variable response signal from the second electrode of the transducer in the column. According to one embodiment, the control circuit is further configured to:

[0017] In a second transmit phase, controlling the switches of the row and column to a first configuration, controlling the transmit circuit of the column to apply a DC bias signal to the second electrode of the transducers in the column, and controlling the transmit circuit of the row to apply a variable excitation signal to the first electrode of the transducers in the row; and / or

[0018] In a second receiving phase, the switches of the row and column are controlled to the second configuration and the first configuration, respectively, the transmit circuit of the column is controlled to apply a DC bias signal to the second electrode of the transducers in the column, and the receive circuit of the column is controlled to read the variable response signal from the first electrode of the transducers in the row.

[0019] According to one embodiment:

[0020] - in each row, the switches of the row are further controllable to connect, in a third configuration, the first electrodes of the transducers in the row to a node to which a fixed bias potential is applied; and

[0021] - In each column, the switches of the column are further controllable to connect, in a third configuration, the second electrodes of the transducers in the column to a node to which a fixed bias potential is applied.

[0022] According to one embodiment:

[0023] - switches in different rows have a common control terminal; and

[0024] -Switches in different columns have a common control terminal.

[0025] According to one embodiment:

[0026] - switches in different rows have distinguishable control terminals; and

[0027] -Switches in different columns have distinguishable control terminals.

[0028] According to one embodiment, the ultrasound transducer is a CMUT transducer or a PMUT transducer.

[0029] According to one embodiment, the switch is integrally co-integrated with the array of ultrasound transducers.

[0030] According to one embodiment, each switch includes electrostatically controlled first and second MEMS interrupters.

[0031] According to one embodiment:

[0032] - for each row, the first and second interrupters of the switches of the row are arranged at the two ends of the row, respectively; and

[0033] - For each column, the first and second interrupters of the switches of the column are arranged at the two ends of the column, respectively. According to one embodiment:

[0034] - for each row, the first and second interrupters of the switches of the row are arranged on one side of the same end of the row; and

[0035] - For each column, the first and second interrupters of the switches of the column are arranged on one side of a same end of the column.

[0036] According to one embodiment, each switch further comprises an electrostatically controlled third MEMS interrupter, and:

[0037] - for each row, the third interrupter of the switches of the row is arranged on the side of the row at the same end as the first interrupter in the row, or on the side of the row at the opposite end to the first interrupter in the row; and

[0038] For each column, the third interrupter of the switches of the column is arranged on the side of the column at the same end as the first interrupter in the column or on the side of the column at the opposite end to the first interrupter in the column. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The foregoing features and advantages, as well as other features and advantages, will be described in detail in the following description of specific embodiments given by way of illustration and not limitation, with reference to the accompanying drawings, in which:

[0040] Figure 1 is an electrical diagram of an example of an array of imaging devices according to an embodiment.

[0041] Figure 2 Is to show the control Figure 1 A timing diagram of an example of a method of a device;

[0042] Figure 3 Shown Figure 1 Examples of embodiments of switches of devices;

[0043] Figure 4 Schematically and partially shown Figure 1 A first example of an embodiment of the device;

[0044] Figure 5 Schematically and partially shown Figure 1 A second example of embodiment of the apparatus;

[0045] Figure 6 Schematically and partially shown Figure 1 A third example of embodiment of the apparatus of; and

[0046] Figure 7 yes Figure 4 A simplified partial cross-sectional view of the device. DETAILED DESCRIPTION

[0047] In different drawings, the same features are represented by the same reference numerals. In particular, common structural and / or functional features between various embodiments may have the same reference numerals and may be provided with the same structure, dimensions and material properties.

[0048] For the sake of clarity, only the steps and elements that are useful for understanding the embodiments described herein are shown and described in detail. In particular, the various possible applications of the imaging device described are not described in detail, and the described embodiments are compatible with the common applications of ultrasonic imaging devices. Further, the properties (frequency, shape, amplitude, etc.) of the electrical excitation signal applied to the ultrasonic transducer by the control circuit are not described in detail, and the described embodiments are compatible with the excitation signals currently used in ultrasonic imaging systems, which can be selected according to the application under consideration, and in particular according to the properties of the subject to be analyzed and according to the type of information desired to be collected. Similarly, the various processing applied to the electrical signal delivered by the ultrasonic transducer and read by the control circuit to extract useful information related to the subject to be analyzed is not described in detail, and the described embodiments are compatible with the processing currently used in ultrasonic imaging systems. Further, the formation of the ultrasonic transducer and the circuit for controlling the described imaging device is not described in detail, and the detailed formation of these elements is within the capabilities of those skilled in the art based on the instructions of this specification.

[0049] Unless otherwise specified, when two elements are referred to as being connected together, this means a direct connection without any intermediate elements other than conductors, and when two elements are referred to as being coupled together, this means the two elements may be connected through one or more other elements or they may be coupled through one or more other elements.

[0050] In the following description, when reference is made to terms that define absolute positions (such as terms "front", "back", "top", "bottom", "left", "right", etc.) or relative positions (such as terms "above", "below", "upper", "below", etc.), or terms that define directions (such as terms "horizontal", "vertical", etc.), unless otherwise stated, this refers to the orientation of the accompanying drawings, and it should be understood that, in practice, the described device may be oriented differently.

[0051] Unless otherwise indicated, the expressions "about," "approximately," "substantially," and "approximately" mean within 10%, and preferably within 5%.

[0052] Figure 1 is an electrical diagram of an example of the array imaging device 100 according to the embodiment.

[0053] The device 100 includes a plurality of i and N columns C iA plurality of ultrasonic transducers in an array, M and N are integers greater than or equal to 2, i is an integer in the range of 1 to M, and j is an integer in the range of 1 to N.

[0054] Each transducer 101 comprises two electrodes, E1 and E2. When an appropriate excitation voltage is applied between electrodes E1 and E2, the transducer emits ultrasonic waves. When a transducer receives ultrasonic waves within a given wavelength range, it transmits a voltage representing the received wave between its electrodes, E1 and E2.

[0055] In this example, the transducer 101 is a CMUT type (capacitive membrane ultrasonic transducer) transducer.

[0056] In each row L of the transducer array i In the example, the transducers 101 in the row have their corresponding electrodes E1 connected to each other. However, the electrodes E1 of the transducers 101 in different rows are not connected to each other. In addition, in each column C of the transducer array, j , the transducers 101 in that column have their corresponding electrodes E2 connected to each other. However, the electrodes E2 of the transducers 101 in different columns are not connected to each other.

[0057] For each row L of the transducer array i , the device 100 comprises a transmitting circuit TX, a receiving circuit RX and a switch SW, which can be controlled to connect the electrodes E1 of the transducers in the row to the output terminals of the transmitting circuit TX of the row in a first configuration (1), and to connect the electrodes E1 of the transducers in the row to the input terminals of the receiving circuit RX of the row in a second configuration (2).

[0058] In addition, for each column C of the transducer array j , the device 100 comprises a transmitting circuit TX, a receiving circuit RX and a switch SW, which can be controlled to connect the electrodes E2 of the transducers in the column to the output terminals of the transmitting circuit TX of the column in a first configuration (1), and to connect the electrodes E2 of the transducers in the column to the input terminals of the receiving circuit RX of the column in a second configuration (2).

[0059] For each row L i , the switches SW of the row can also be controlled to connect the electrodes E1 of the transducers in the row to a node GND to which a fixed bias potential is applied, for example, ground, in a third configuration (3). i , the switches SW of the column can also be controlled to connect the electrodes E2 of the transducers in the row to the node GND in a third configuration (3).

[0060] The device 100 further comprises a control circuit CTRL adapted to control the switch SW and the transmitting circuit TX and to read the signal delivered by the receiving circuit RX. The control circuit CTRL forms a circuit for controlling the transducer array 101 with the transmitting and receiving circuits TX and RX and the switch SW.

[0061] Each transmit circuit TX further comprises a pulse generator having an output terminal coupled (e.g., connected) to an output terminal of the circuit TX and a control input terminal coupled (e.g., connected) to an output terminal of the control circuit CTRL. Each receive circuit RX may comprise an amplifier, preferably a low-noise amplifier, having a terminal input coupled (e.g., connected) to an input terminal of the circuit RX and an output terminal coupled (e.g., connected) to an input terminal of the control circuit CTRL.

[0062] In order to transmit and / or receive ultrasonic waves, a CMUT transducer must typically be biased. To this end, a DC bias potential is applied between its electrodes E1 and E2, while a variable (i.e., discontinuous) excitation voltage is applied to one of its electrodes E1 and E2, or a variable response voltage is read from one of its electrodes E1 and E2.

[0063] In known ultrasound imaging devices, the bias voltage is provided by a specific bias voltage that is different from that of the transmit and receive circuits, and decoupling capacitors are provided to isolate the bias circuit from the transmit and receive circuits. However, the provision of the bias circuit and decoupling capacitors increases the complexity and cost of the circuitry used to control the device. Furthermore, the presence of the decoupling capacitors can lead to parasitic coupling between the different transducers of the device. In particular, the presence of the decoupling capacitors significantly limits the possibility of dynamic switching of rows and columns, and therefore restricts the array's ability to effectively scan two planes orthogonal to the propagation axis of the ultrasound waves. In practice, this leads to non-uniform reconstruction of the volume under consideration.

[0064] According to one aspect of the embodiment, Figure 1 In the device 100, the biasing of the ultrasonic transducer is directly ensured by the transmitting circuit TX of the control circuit. This makes it possible to eliminate the specific circuit for biasing the transducer 101 and the decoupling capacitors for isolating the biasing circuit from the transmitting circuit RX and the receiving circuit TX.

[0065] During the phase of transmitting ultrasound waves by means of the transducer 101 of the device 100, the control circuit CTRL controls the switches SW connected to the electrodes E1 and E2 of the transducer 101 to a first configuration (1) so as to connect the electrodes E1 and E2 of the transducer 101 to the respective rows L to which the transducers belong. i The transmitting circuit TX and the transducer 101 belong to column C j The control circuit CTRL then controls the transducer to which row L belongs.i The transmitting circuit TX applies a DC bias potential to the electrode E1 of the transducer and simultaneously controls the column C to which the transducer belongs. j The transmitting circuit TX applies a variable excitation voltage, for example an AC voltage, to the electrode E2 of the transducer.

[0066] During the phase of receiving ultrasound waves by means of the transducer 101 of the device 100, the control circuit CTRL controls the switches SW connected to the electrodes E1 and E2 of the transducer 101 to the first configuration (1) and the second configuration (2), respectively, so as to connect the electrodes E1 and E2 of the transducer 101 to the rows L to which the transducers belong. i The transmitting circuit TX and the transducer 101 belong to column C j The receiving circuit RX. The control circuit CTRL then controls the transducer row L i The transmitting circuit TX applies a DC bias potential to the electrode E1 of the transducer and simultaneously controls the column C to which the transducer belongs. j The receiving circuit RX reads the AC response voltage from the electrode E2 of the transducer.

[0067] As a variation, a DC bias potential may be applied to electrode E2, and the variable excitation voltage and the variable response voltage are then applied to and read from electrode El, respectively.

[0068] In another variation, a DC bias potential may be applied to one of electrodes E1 and E2 during the transmit phase and then applied to the other electrode during the receive phase. For example, during the transmit phase, a DC bias voltage is applied to electrode E1 and a variable excitation voltage is applied to electrode E2, and during the receive phase, a DC bias voltage is applied to electrode E2 and a variable response voltage is read from electrode E1.

[0069] Figure 2 is a schematic diagram showing the control Figure 1 The timing diagram of an example of a method of the device 100 can be implemented by the control circuit CTRL. In this example, the rows L of the array of transducers 101 are considered more specifically. i and column C j . Figure 2 shows the control column C j The signal S of the switch SW Cj , used to control the line L i The signal S of the switch SW Li 、By Line L i The voltage O delivered by the transmitter circuit TX LTXi , by column C j The voltage O delivered by the transmitting circuit TX CTXj , by column C jThe receiving circuit RX delivers the voltage O CRXj 、By Line L i The receiving circuit RX delivers the voltage O LRXi And in line L i The transducer electrode E1 and column C j The voltage V between the transducer electrodes E2 LC It should be noted that for simplicity, Figure 2 The signal S is not specified in detail. Cj and S Li More specifically, for the signal S Cj and S Li In each of the embodiments, only the state "TX" corresponding to the control state of the switch SW to the first configuration (connection to the transmitting circuit TX) and the state "RX" corresponding to the control state of the switch SW to the second configuration (connection to the receiving circuit RX) have been shown. Moreover, for the sake of simplicity, the response signal O delivered by the receiving circuit RX during the receiving phase is not shown. CRXj and O LRXi exist Figure 2 More specifically, for signal O CRXj and O LRXi Each of them has been simply shown a state "ACQ" corresponding to the variable signal delivered by the circuit RX during the reception phase of the ultrasound waves.

[0070] From time t0 to time t1 after time t0, the switch SW of column Cj and the switch SW of row L i The switches SW of the L1 and L2 are controlled to the first configuration (TX) to i The transducer electrode E1 is connected to the line L i The transmitting circuit TX, and the column C j The transducer electrode E2 is connected to column C j The transmitting circuit TX. i The transmitting circuit TX is controlled to be in line L i A substantially zero DC voltage O is applied to the electrode E1 of the transducer. LTXi , and the transmitting circuit TX of column Cj is controlled to j A negative DC bias voltage O is applied to the electrode E2 of the transducer. CTXj -V POL , for example, about -10 volts. Then the voltage V LC is equal to +V POL In the absence of a receiving circuit RX connected to electrodes E1 and E2, respectively, by column C j The receiving circuit RX and the line L i The receiving circuit delivers the voltage O CRXjand O LRXi The value is basically zero.

[0071] From time t1 to time t2 after time t1, the control circuit CTRL controls the line L i The transmitting circuit TX is used to apply a variable excitation signal (eg, a series of positive and / or negative voltage pulses) to the row L. i In the example shown, the excitation signal corresponds to an electrode E1 of the transducer 101 having a value of V POL The positive square wave voltage pulse and value is -V POL The voltage V LC is between 0V and 2*V POL Square wave pulse voltage alternating between.

[0072] Times t1 and t2 are marked by lines L i and column C j The common transducer 101 transmits the ultrasonic wave at the beginning and end of the phase. In fact, the DC bias potential -V POL It can also be applied to the electrodes E2 of the transducers 101 of the other columns of the device. In this case, during the transmission phase from time t1 to time t2, the electrodes E2 of the transducers 101 of the row L i All transducers 101 transmit ultrasonic waves.

[0073] From time t2 to time t3 after time t2, column C j The switch SW is controlled to the second configuration (RX) to place the j The electrode E2 of the transducer in row L is connected to the receiving circuit RX of the column. i The switches SW of row L are maintained in the first configuration (TX). i The transmitting circuit TX is controlled to transmit to the line L i The electrode E1 of the transducer applies a positive DC voltage O LTXi +V POL Ignoring the oscillation caused by the transducer receiving the returned ultrasonic wave (in fact, the amplitude of the return signal derived from the acoustic-electric conversion is at least four orders of magnitude smaller than the amplitude of the excitation signal, that is, 80dB smaller), the voltage V LC is equal to +V POL A positive DC voltage.

[0074] Times t2 and t3 are marked by lines L i and column C j The common transducer 101 receives the return ultrasound wave during the reception phase. j The receiving circuit RX delivers the voltage O CRXj Represented by line L i and column C jThe common transducer 101 receives the ultrasonic wave. The control circuit CTRL can read the voltage O CRXj In fact, in the receiving stage, the DC bias voltage V POL is applied to the electrodes E1 of the transducers 101 of the other rows of the device. In this case, the voltage O CRXj Represented by Column C j The returned ultrasonic waves are received by all the transducers 101 .

[0075] Figure 2 A second example of the transmission and reception phases of ultrasound waves performed by the device 100 after time t3 is further shown. In this second example, the electrodes applying the DC bias voltage and the electrodes applying the excitation signal and the reading of the return signal are inverted with respect to the example just described.

[0076] From time t3 to time t4 after time t3, column C j The switch SW and line L i The switches SW of column C are all controlled to the first configuration (TX). j The transmitter circuit TX is in column C j A substantially zero DC voltage O is applied to the electrode E2 of the transducer. CTXj , and control line L i The transmitting circuit TX is in line L i A positive DC bias voltage O is applied to the electrode E1 of the transducer. LTXi +V POL Then the voltage V LC is equal to +V POL A positive DC voltage.

[0077] From time t4 to time t5 after time t4, the control circuit CTRL controls column C j The transmitter circuit TX is in column C j A variable excitation signal is applied to the electrode E2 of the transducer 101.

[0078] Times t4 and t5 are marked by lines L i and column C j The common transducer 101 transmits the ultrasonic wave at the beginning and end of the phase. In fact, the DC bias voltage +V POL It can also be applied to the electrodes E1 of the transducers 101 of the other rows of the device. In this case, during the emission phase lasting from time t4 to time t5, the electrodes E1 of the transducers 101 of the column C j All transducers 101 transmit ultrasonic waves.

[0079] From time t5 to time t6 after time t5, row L iThe switch SW is controlled to the second configuration (RX) to turn row L i The electrode E1 of the transducer is connected to the receiving circuit RX of the row. Column C j The switches SW are maintained in the first configuration (TX). Column C j The transmitting circuit TX is controlled to j A negative DC voltage O is applied to the electrode E2 of the transducer CTXj -V POL Ignoring the oscillation caused by the reception of the returning ultrasonic wave, the voltage V LC is equal to +V POL A positive DC voltage.

[0080] Times t5 and t6 are marked by lines L i and column C j The common transducer 101 receives the return ultrasound wave during the reception phase. i The receiving circuit RX delivers the voltage O LRXi Represented by line L i and column C j The ultrasonic wave received by the common transducer 101. Voltage O LRXi It can be read by the control circuit CTRL. In fact, in the receiving stage, the DC bias voltage -V POL is applied to the electrodes E2 of the transducers 101 of the other columns of the device. In this case, the voltage O LRXi Represented by column L i The returned ultrasonic waves are received by all the transducers 101 .

[0081] exist Figure 2 In the example of , starting from time t6 , the method continues with a new transmit-receive phase similar to that implemented from time t0 .

[0082] exist Figure 1 In the example of FIG. 1 , the third configuration (3) of the switches SW can further enable the array of transducers 101 to be controlled as a linear array of transducers to acquire a two-dimensional image. To this end, all rows L of the array i The switch SW can be controlled to the third configuration, for example, to apply the same DC bias potential GND to the electrodes E1 of all transducers. j This then corresponds to a single transducer that is alternately controlled in transmit mode (the switches SW of the columns are then in a first configuration) and in receive mode (the switches of the columns are then in a second configuration). It should be noted that the node GND is not necessarily connected to ground, but can be coupled to a terminal for delivering a fixed bias potential suitable for biasing the transducer.

[0083] Similarly, all columns C of the array jThe switch SW can be controlled to a third configuration. Then, each row of the array is equivalent to a single transducer that is alternately controlled in transmit and receive modes.

[0084] As a variant, the third configuration (3) of the switches SW can be used in array mode (acquisition of three-dimensional images) to apply to the transducers a bias voltage different from the level defined by the high and low values of the voltage delivered by the transmit circuit TX.

[0085] exist Figure 1 In the example of , each switch SW includes, for example, first, second and third interrupters, each interrupter having a first conduction node connected to the electrode E1 of the corresponding row or the electrode E2 of the corresponding column, and a second conduction node connected to the output terminal of the transmitting circuit TX of the corresponding row or column, the input terminal of the receiving circuit RX of the corresponding row or column, and the node GND, respectively.

[0086] As a variant, the third configuration of switches SW may be omitted, which makes it possible to simplify their formation.

[0087] The interrupter of the switch SW can be formed by a transistor, such as a MOS transistor. In this case, the switch is integrated into a semiconductor chip different from the substrate, and the transducer 101 is formed on top of the semiconductor chip. For example, the transmit RX and receive TX circuits, the control circuit CTRL, and the switch SW are integrated into the same semiconductor chip.

[0088] In a preferred embodiment, the interrupter of the switch SW is formed in MEMS (“micro-electromechanical systems”) technology. The switch SW is then preferably integrated with the ultrasonic transducer array, for example as described in the article entitled “A Fast-Switching (1.35-μs) Low-Control-Voltage (2.5-V) MEMS T / R Switch Monolithically Integrated With a Capacitive Micromachined Ultrasonic Transducer” by Xiao Zhang et al. (Journal of Microelectromechanical Systems, PP(99):1, January 11, 2018).

[0089] Figure 3 An example of embodiment of such an interrupter is schematically shown. Figure 3More specifically, two side cross-sectional views (A) and (B) of the interrupter are shown, respectively, in the off (blocking) state and the on (conducting) state, as well as a top cross-sectional view (C) and a bottom cross-sectional view (D) of the interrupter. Views (A) and (B) are cross-sectional views along plane P1 of views (C) and (D), and views (C) and (D) are cross-sectional views along plane P2 of view (A).

[0090] Figure 3 The interrupter comprises a flexible membrane 301 suspended above a cavity 303 formed in a rigid support layer 305. The layer 305, for example made of silicon oxide, is arranged on the upper surface of a support substrate 307 (for example, made of glass). In the example shown, the cavity 303 is through-hole, that is, the bottom of the cavity is formed by the upper surface of the substrate 307.

[0091] Figure 3 The interrupter comprises two separate metallizations 309 and 311 arranged at the top of the cavity 303 and in contact with the bottom of the cavity 303, forming the two main conducting terminals of the interrupter. Figure 3 The interrupter further comprises a coupling metallization 313 arranged on top of the membrane 301 and in contact with the lower surface of the membrane 301, which is arranged so that when the membrane 301 is in a first position called the high position (corresponding to Figure 3 (A)), the metallization 313 is not in contact with the metallizations 309 and 311, and when the membrane 301 is in a second position called the low position (corresponding to Figure 3 (B)), the metallization 313 connects the metallizations 309 and 311 to each other. Thus, in the high position of the membrane 301, the interrupter is in the off state, and in the low position of the membrane 301, the interrupter is in the on state.

[0092] The interrupter includes a first control electrode arranged on top of the cavity 303 and in contact with the bottom of the cavity 303 and electrically insulated from the metallizations 309 and 311 , and a second control electrode 317 arranged on top of the membrane 303 and in contact with the upper surface of the membrane 303 and electrically insulated from the coupling metallization 313 .

[0093] Applying an appropriate control voltage between electrodes 315 and 317 causes the membrane to be placed in the low position by electrostatic effect and thus turns the interrupter on. In the absence of voltage between electrodes 315 and 317, the membrane returns to its high position, causing the interrupter to turn off.

[0094] The flexible membrane 301 can be made of silicon and / or silicon oxide. Preferably, the membrane 301 includes at least one insulating layer, for example, made of silicon oxide, which ensures electrical insulation between the upper control electrode 317 and the metallization 313 on the one hand, and between the upper control electrode 317 and the lower control electrode 315 on the other hand. For example, the flexible membrane 301 includes a stack of silicon layers and an insulating layer (for example, made of silicon oxide, coating the lower surface of the silicon layer) (not shown in detail in the figure).

[0095] Furthermore, in order to avoid any interference of the signals transmitted between the metallizations 309 and 311 via the metallization 313 , the upper control electrode 317 is preferably interrupted with respect to the metallizations 309 , 311 and 313 .

[0096] Figure 4 It is schematically shown Figure 1 The ultrasonic transducer array 101 of the device 100 and the switch SW are arranged on the same supporting substrate 307 (on the Figure 4 For example, the transmitting circuit RX and the receiving circuit TX and the control circuit CTRL (not visible in FIG) are integrated in an integral form. Figure 4 1 and 2) are integrated in one or more semiconductor chips that are different from the integral chip that integrates the transducer 101 and the switch SW.

[0097] In this example, for simplicity, an array of 3*3 ultrasound transducers 101 has been considered.

[0098] Each transducer has a Figure 3 The structure of the switch is different in that, in the transducer 101, there are no conductive metallizations 309 and 311 and coupling metallization 313. In each transducer 101, the lower control electrode 315 and the upper control electrode 317 correspond to Figure 1 electrodes E2 and E1.

[0099] exist Figure 4 In the example of the transducer array, each row L i In FIG, the upper control electrodes (corresponding to electrode E1) of the transducers 101 in the row are connected to each other and form a continuous metal strip 401 extending substantially along the entire length of the row. j , the lower control electrodes (corresponding to electrode E2) of the transducers 101 in a row are connected to each other and form a continuous metal strip 402 that extends substantially along the entire length of the column. In this example, the metal strips 401 are parallel to each other, and the metal strips 402 are parallel to each other and perpendicular to the strips 401.

[0100] exist Figure 4 In the example, for each row L of the transducer arrayi , the device comprises a first interrupter K1 arranged at a first end of the row of metal strips 401 and a second interrupter K2 arranged at an opposite end of the row of metal strips 401. Interrupters K1 and K2 are about Figure 3 Each of the interrupters K1 and K2 has a conductive metallization 309 connected to the metal strip 401. The conductive metallization 311 of the interrupter K1 is connected to a metal pad RX intended to be connected to an output terminal of the transmit circuit TX of the row.

[0101] exist Figure 4 In an example, the device further comprises: for each column C of the transducer array j , a first interrupter K1 arranged at a first end of the metal strip 402 of the column, and a second interrupter K2 arranged at the opposite end of the metal strip 402 of the column. Each of the interrupters K1 and K2 has a conductive metallization 309 connected to the metal strip 402. The conductive metallization 311 of the interrupter K1 is connected to a metal pad TX intended to be connected to an output terminal of the transmit circuit TX of the column. The conductive metallization 311 of the interrupter K2 is connected to a metal pad RX intended to be connected to an input terminal of the receive circuit RX of the column.

[0102] For each row L i , the interrupters K1 and K2 of the row form the switch SW of the row. Similarly, for each column C j , the interrupters K1 and K2 of the column form the switch SW of the column. In this example, the switch SW is a two-position switch that can only be controlled into a first configuration (1) and a second configuration (2).

[0103] exist Figure 4 In the example, different rows of the array L i The interrupters K1 are all located on one side of the same side of the array, on the left hand side in the example shown, and different rows L of the array i The interrupters K2 are all located on one side of the opposite edge of the array, on the right hand side in the example shown. Further, in this example, the different columns C of the array j The interrupters K1 are all located on one side of the same side of the array, the lower side in the example shown, and different columns C of the array j The interrupters K2 are all located on one side of the opposite edge of the array, the upper edge in the example shown.

[0104] exist Figure 4 In the example:

[0105] - different rows L of the array i The control electrodes 315 of the interrupters K1 are all connected to the same metal pad PLK1A, and the different rows L of the arrayi The control electrodes 317 of the interrupters K1 are all connected to the same metal pad PLK1B;

[0106] - different rows L of the array i The control electrodes 315 of the interrupters K2 are all connected to the same metal pad PLK2A, and the different rows L of the array i The control electrodes 317 of the interrupters K2 are all connected to the same metal pad PLK2B;

[0107] - different columns of array C j The control electrodes 315 of the interrupters K1 are all connected to the same metal pad PCK1A, and different columns C of the array j The control electrodes 317 of the interrupters K1 are all connected to the same metal pad PCK1B; and

[0108] - different columns of array C j The control electrodes 315 of the interrupters K2 are all connected to the same metal pad PCK2A, and different columns C of the array j The control electrodes 317 of the interrupters K2 are all connected to the same metal pad PCK2B.

[0109] The metal pads PLK1A, PLK1B, PLK2A, PLK2B, PCK1A, PCK1B, PCK2A, PCK2B are intended to be connected to the device control circuit CTRL.

[0110] In this example, different rows L i The interrupters K1 of the different rows are controlled simultaneously by applying appropriate control voltages between pads PLK1A and PLK1B. i The interrupters K2 of the different columns are controlled simultaneously by applying appropriate control voltages between pads PLK2A and PLK2B. j The interrupters K1 of the different columns are controlled simultaneously by applying appropriate control voltages between pads PCK1A and PCK1B. j All interrupters K2 are controlled simultaneously by applying an appropriate control voltage between pads PCK2A and PCK2B. This makes it possible to limit the number of connection pads required to control the switch SW and thus limit the overall size and cost of the device.

[0111] Figure 5 Shown Figure 4 An alternative embodiment of the device.

[0112] exist Figure 5In a variant of , each of the interrupters K1 and K2 of the device is provided with two specific metal conductive pads A and B, which are connected to the lower control electrode 315 and the upper control electrode 317 of the interrupter, respectively. This enables the interrupters K1 and K2 to be controlled individually.

[0113] For simplicity, Figure 5 Only a single interrupter K1 and a portion of the metal strip 401 connected to the interrupter are shown.

[0114] Figure 6 Shown Figure 4 Another alternative embodiment of the device. Figure 6 In the example, for each row of device L i , the interrupters K1 and K2 of the row are arranged on one side of the same end of the row. Similarly, for each column C of the device j , the interrupters K1 and K2 of the column may be arranged on one side of the same end of the column.

[0115] exist Figure 6 In the example, and in Figure 5 In the example of FIG. 1 , two specific metal conductive pads A and B are provided for each of the interrupters K1 and K2 of the device. As a variant, the corresponding control electrodes of the interrupters K1 and K2 of different rows and the corresponding control electrodes of the interrupters K1 and K2 of different columns can be connected to each other, similar to the ones already combined. Figure 4 described to reduce the total number of connection pads of the device.

[0116] For simplicity, Figure 6 Only a single interrupter K1 , a single interrupter K2 and a portion of the metal strip 401 connected to these interrupters are shown.

[0117] In the case where each switch SW includes three interrupters, the three interrupters may be arranged on one side of the same end of the corresponding metal strip 401 or 402. As a variation, two interrupters may be arranged on one side of the same end of the corresponding metal strip 401 or 402, and the third switch may be arranged on one side of the opposite end of the metal strip. Figure 5 In the example of FIG. 1 , two specific metal conductive pads A and B may be provided for each interrupter. As a variant, the corresponding electrodes for controlling the interrupters of different rows and the corresponding electrodes for controlling the interrupters of different columns may be connected to each other, similar to the one already combined. Figure 4 described.

[0118] Figure 7 Schematically and partially shown Figure 4 Examples of embodiments of the apparatus. Figure 7More specifically, it includes a view (A) showing a longitudinal cross section of the device in the direction of the metal strip 402, and a view (B) showing a longitudinal cross section of the device in the direction of the metal strip 401. For the sake of simplicity, in each view, only two transducers 101 and one interrupter K1 located at the end of the corresponding metal strip 401 or 402 are shown.

[0119] like Figure 7 As shown, the transducer 101 and the interrupter are formed on the same support substrate 307. The metal strip 402, the conductive electrodes 309 and 311 of the interrupter, and the lower control electrode 315 of the interrupter (not shown) are formed on the same support substrate 307. Figure 7 305 are formed in the same first metallization level of the upper surface of the coated substrate 307. A support layer 305 is formed on top of the first metallization level. The membrane 301 is located above the support layer 305. The metal strips 401 and the upper control electrodes 317 of the interrupters are formed in the same metallization level arranged above the membrane 301. Each metal strip 401 is connected to the conductive terminal 309 of the interrupter of the switch SW of the corresponding row via a conductive via 701 through the membrane layer 301 and the support layer 305. The connection pads RX and TX (at Figure 7 401 ).

[0120] It should be noted that in Figure 7 In the example shown, in each transducer 101, the cavity 303 above which the membrane 301 is suspended is divided into a plurality of elementary cavities, for example, in an array of 3*3 elementary cavities separated in pairs by walls made of the material of the layer 305. However, the described embodiments are not limited to this particular case.

[0121] Various embodiments and variations have been described. Those skilled in the art will appreciate that certain features of these various embodiments and variations may be combined, and that other variations will occur to those skilled in the art. In particular, although only examples of embodiments in which the ultrasound transducer 101 is a CMUT transducer have been described, the invention may be combined with other embodiments in which the ultrasound transducer 101 is a CMUT transducer. Figure 1 and 2 The described embodiments may be applied to any other type of transducer that needs to be biased to a DC voltage when transmitting and / or receiving ultrasonic waves, such as PMUT type (“Piezoelectric Micromachined Ultrasonic Transducer”) transducers.

Claims

1. Ultrasonic imaging device (100), comprising: Line (L i ) and columns (C j ), each transducer comprising a first electrode (E1) and a second electrode (E2), the first electrodes of the transducers in the same row being connected to each other and the second electrodes of the transducers in the same column being connected to each other; For each row (L i ), a transmitting circuit (TX), a receiving circuit (RX) and a switch (SW) controllable to connect the first electrodes (E1) of the transducers in the row to the transmitting circuit (TX) of the row in a first configuration and to connect the first electrodes (E1) of the transducers in the row to the receiving circuit (RX) of the row in a second configuration; For each column (C j ), a transmission circuit (TX), a reception circuit (RX) and a switch (SW) controllable to connect the second electrodes (E2) of the transducers in the column to the transmission circuit (TX) of the column in a first configuration and to connect the second electrodes (E2) of the transducers in the column to the reception circuit (RX) of the column in a second configuration; as well as A control circuit (CTRL) configured to: During the first emission phase, the row (L i ) and columns (C j ) is controlled to the first configuration, controlling the transmitting circuit (TX) of the row to transmit the signal in the row (L i ) applies a DC bias signal to the first electrode (E1) of the transducer in the column and controls the transmitting circuit (TX) of the column to transmit the signal to the first electrode (E1) of the transducer in the column (C j ) in the second electrode (E2) of the transducer; and / or During the first receiving phase, the line (L i ) and columns (C j ) are respectively controlled to the first configuration and the second configuration, and the transmitting circuit (TX) of the row is controlled to transmit the signal in the row (L i ) applies a DC bias signal to the first electrode (E1) of the transducer in the column and controls the receiving circuit (RX) of the column to receive the signal from the column (C j ) reads the variable response signal from the second electrode (E2) of the transducer.

2. The device according to claim 1, wherein The control circuit (CTRL) is further configured to: During the second emission phase, the row (L i ) and columns (C j ) is controlled to the first configuration, controlling the transmitting circuit (TX) of the column to transmit the signal in the column (C j ) applies a DC bias signal to the second electrode (E2) of the transducer in the row and controls the transmitting circuit (TX) of the row to transmit the signal to the second electrode (E2) of the transducer in the row (L i ) applies a variable excitation signal to the first electrode (E1) of the transducer; and / or During the second receiving phase, the line (L i ) and columns (C j ) are respectively controlled to the second configuration and the first configuration, and the transmitting circuit (TX) of the column is controlled to transmit the signal in the column (C j ) applies a DC bias signal to the second electrode (E2) of the transducer in the column and controls the receiving circuit (RX) of the column to receive the signal from the row (L i ) reads the variable response signal from the first electrode (E1) of the transducer.

3. The apparatus according to claim 1 or 2, wherein: In each row (L i ), the switches (SW) of the row are further controllable to connect, in a third configuration, the first electrodes (E1) of the transducers in the row to a node (GND) to which a fixed bias potential is applied; and In each column (C j ), the switches (SW) of the column can also be controlled to connect the second electrodes (E2) of the transducers in the column to the node (GND) to which the fixed bias potential is applied in a third configuration.

4. The apparatus according to claim 1 or 2, wherein: Different lines (L i ) of the switches (SW) having a common control terminal; and Different columns (C j )'s switches (SW) have a common control terminal.

5. The apparatus according to claim 1 or 2, wherein: Different lines (L i ) having different control terminals; and Different columns (C j ) has different control terminals.

6. The device according to claim 1 or 2, wherein: The ultrasonic transducer (101) is a CMUT transducer or a PMUT transducer.

7. The apparatus according to claim 1 or 2, wherein: The switch (SW) is integrally integrated with the array of ultrasonic transducers (101).

8. The apparatus according to claim 7, wherein Each switch (SW) includes an electrostatically controlled first MEMS interrupter (K1) and an electrostatically controlled second MEMS interrupter (K2).

9. The apparatus according to claim 8, wherein: For each row (L i ), the first MEMS interrupter (K1) and the second MEMS interrupter (K2) of the switch (SW) of the row are respectively arranged in the row (L i ) at both ends; and For each column (C j ), the first MEMS interrupter (K1) and the second MEMS interrupter (K2) of the switch (SW) of the column are respectively arranged in the column (C j ) at both ends.

10. The apparatus of claim 8, wherein: For each row (L i ), the first MEMS interrupter (K1) and the second MEMS interrupter (K2) of the switch (SW) of the row are arranged in the row (L i ) on one side of the same end as the and For each column (C j ), the first MEMS interrupter (K1) and the second MEMS interrupter (K2) of the switch (SW) of the column are arranged in the column (C j ) on one side of the same end.

11. The apparatus according to any one of claims 8 to 10, wherein Each switch (SW) further comprises an electrostatically controlled third MEMS interrupter, and wherein: For each row (L i ), the third MEMS interrupter of the switch (SW) of the row is arranged in the row (L i ) on the same side as the first MEMS interrupter (K1) in the row, or on the same side as the first MEMS interrupter (K1) in the row (L i ) on a side of an end opposite to the first MEMS interrupter (K1) in the row; For each column (C j ), the third MEMS interrupter of the switch (SW) of the column is arranged in the column (C j ) on the same side as the first MEMS interrupter (K1) in the column, or on the same side as the first MEMS interrupter (K1) in the column (C j ) on a side of the opposite end of the first MEMS interrupter (K1) in the column.

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