# US 8,539,837 B2 · Ultrasonic imaging using thin film transistor backplane

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- Number: US 8,539,837 B2
- Document ID: US8539837B2
- Status: Granted
- Kind: B2
- Application number: 12/965,784
- Filed: 2010-12-10
- Published: 2012-06-14
- Granted: 2013-09-24
- Earliest claimed: 2010-12-10
- Assignees: Palo Alto Research Center Incorporated
- Applicants: Serena Han Ying Wong; Jeng Ping Lu; Raj B. Apte
- Inventors: Serena Han Ying Wong; Jeng Ping Lu; Raj B. Apte
- Web page: https://patentgrep.com/patent/US8539837B2

## CPC

- G01S 15/89: for mapping or imaging
- B06B 1/02: making use of electrical energy (B06B1/18, B06B1/20 take precedence)
- G01S 15/8915: {using a transducer array}
- G01S 15/8977: {using special techniques for image reconstruction, e.g. FFT, geometrical transformations, spatial deconvolution, time deconvolution}
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- B06B: METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, {e.g.} FOR PERFORMING MECHANICAL WORK IN GENERAL (for particular applications, see the relevant subclasses, e.g. B07B1/40, B23Q17/12, B24B31/06; measurement of mechanical vibrations G01H; in direction finding, locating, distance or velocity measuring G01S; {generating seismic energy G01V1/02}; control of mechanical vibrations in general G05D; sound-producing devices, e.g. bells, sirens, whistles G10K, {e.g. methods or devices for transmitting, conducting, or directing sound in general G10K11/00}; generation of electrical oscillations H03B; electromechanical resonators in general H03H; electromechanical transducers {for communication techniques, e.g. microphones, speakers} H04R)

## Abstract

An embodiment is a method and apparatus for coherent ultrasonic imaging. A receiver array has a plurality of receiver elements on a substrate to detect in-phase and quadrature components of a received signal corresponding to a transmit signal. Each of the receiver elements includes a receiver transducer and a thin-film transistor (TFT) receiver circuit. The TFT receiver circuit includes a quadrature detector having a mixer to mix a received signal with a reference signal in a composite bias signal that is distributed across the plurality of receiver elements. A transmitter is acoustically coupled to the plurality of receiver elements to generate the transmit signal through an imaging medium.

## Claims

### Claim 1

An apparatus comprising:
a receiver array having a plurality of receiver elements on a substrate to detect in-phase and quadrature components of a received signal corresponding to a transmit signal, each of the receiver elements including a receiver transducer and a thin-film transistor (TFT) receiver circuit, the TFT receiver circuit comprising a quadrature detector having a mixer to mix the received signal with a reference signal in a composite bias signal that is distributed across the plurality of receiver elements; and
a transmitter acoustically coupled to the plurality of receiver elements to generate the transmit signal through an imaging medium.

### Claim 2 (depends on 1)

The apparatus of claim 1 wherein the composite bias signal is distributed across the plurality of receiver elements via a conductive layer.

### Claim 3 (depends on 1)

The apparatus of claim 1 wherein the composite bias signal is a combination of a range gate signal and a reference signal.

### Claim 4 (depends on 1)

The apparatus of claim 1 wherein the receiver circuit further comprises:
a control circuit coupled to the quadrature detector to generate the composite bias signal that is a combination of a range gate signal and a reference signal, the range gate signal activating an integration time period that is longer than a carrier frequency period.

### Claim 5 (depends on 4)

The apparatus of claim 4 wherein the integration time period is a multiple of the carrier frequency period.

### Claim 6 (depends on 1)

The apparatus of claim 1 wherein the TFT receiver circuit further comprises a reset switch to reset charge.

### Claim 7 (depends on 1)

The apparatus of claim 1 wherein the transmitter is deposited on surface of the receiver array, on backside of the substrate, or on the imaging medium opposite of the receiver array.

### Claim 8 (depends on 1)

The apparatus of claim 1 wherein the reference signal is generated by the receiver array or the transmitter.

### Claim 9 (depends on 1)

The apparatus of claim 1 wherein the reference signal is a sinusoidal signal or a 90-degree-phase-shifted sinusoidal signal.

### Claim 10 (depends on 3)

The apparatus of claim 3 wherein the reference signal is synchronized with the transmit signal and has same frequency with the transmit signal.

### Claim 11 (depends on 1)

The apparatus of claim 1 wherein the range gate signal has a minimum sampling frequency equal to a product of bandwidth of the transmit signal and a center frequency of the transmit signal.

### Claim 12 (depends on 1)

The apparatus of claim 1 wherein the receiver transducer is made of polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE).

### Claim 13

A method comprising:
forming a receiver array having a plurality of receiver elements on a substrate, each of the receiver elements including a receiver transducer and a thin-film transistor (TFT) receiver circuit, the TFT receiver circuit comprising a quadrature detector having a mixer to mix a received signal corresponding to a transmit signal with a reference signal in a composite bias signal distributed across the plurality of receiver elements; and
acoustically coupling a transmitter to the plurality of receiver elements to generate the transmit signal through an imaging medium.

### Claim 14

The method of claiml3 wherein forming the receiver array comprises distributing the composite bias signal across the plurality of receiver elements via a conductive layer.

### Claim 15 (depends on 13)

The method of claim 13 wherein the composite bias signal is a combination of a range gate signal and a reference signal.

### Claim 16 (depends on 13)

The method of claim 13 wherein forming the receiver array comprises:
forming a control circuit to generate the composite bias signal that is a combination of a range gate signal and a reference signal, the range gate signal activating -an integration time period that is longer than a carrier frequency period.

### Claim 17 (depends on 16)

The method of claim 16 wherein the integration time period is a multiple of the carrier frequency period.

### Claim 18 (depends on 13)

The method of claim 13 wherein forming the receiver array comprises forming a reset switch to reset charge.

### Claim 19 (depends on 13)

The method of claim 13 wherein acoustically coupling the transmitter comprises depositing the transmitter on surface of the receiver, on backside of the substrate, or on the imaging medium opposite of the receiver.

### Claim 20 (depends on 13)

The method of claim 13 wherein the receiver transducer is made of polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE).

### Claim 21

A system comprising:
an imaging structure comprising:
a substrate,
a receiver array having a plurality of receiver elements deposited on the substrate to detect in-phase and quadrature components of a received signal corresponding to a transmit signal, each of the receiver elements including a receiver transducer and a thin-film transistor (TFT) receiver circuit, the TFT receiver circuit comprising a quadrature detector having a mixer to mix the received signal with a reference signal in a composite bias signal that is distributed across the plurality of receiver elements, and
a transmitter acoustically coupled to the plurality of receiver elements to generate the transmit signal through an imaging medium; and
a processing circuit coupled to the imaging structure to process the detected in-phase and quadrature signals to form a focused image.

### Claim 22 (depends on 21)

The system of claim 21 wherein the processing circuit comprises:
a plurality of delay and phase shift elements to obtain amplitudes and phases of the detected in-phase and quadrature signals corresponding to a plurality of desired plane locations in the imaging medium; and
a summer coupled to the plurality of delay and phase shift elements to sum the amplitudes and phases of the detected in-phase and quadrature signals to provide individual pixels of the focused image.