# US 2017/0285877 A1 · Drive scheme for ultrasonic transducer pixel readout > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2017/0285877 A1 - Document ID: US20170285877A1 - Status: Published application - Kind: A1 - Application number: 15/474,084 - Filed: 2017-03-30 - Published: 2017-10-05 - Earliest claimed: 2016-04-04 - Assignees: QUALCOMM Incorporated - Applicants: QUALCOMM Incorporated - Inventors: Ashish Hinger - Web page: https://patentgrep.com/patent/US20170285877A1 ## CPC - G06F 3/0416: {Control or interface arrangements specially adapted for digitisers} - A61B 5/1172: using fingerprinting - B06B 1/0622: {on one surface} - G01N 29/2437: {Piezoelectric probes} - G01N 29/26: Arrangements for orientation or scanning {by relative movement of the head and the sensor (mechanical steering of sound transducers or their beams G10K11/35)} - G06F 3/043: using propagating acoustic waves - G06V 40/1306: {non-optical, e.g. ultrasonic or capacitive sensing} - H03K 17/74: by the use, as active elements, of diodes (by the use of more than one type of semiconductor device H03K17/567; by the use of tunnel diodes H03K17/58; by the use of negative resistance diodes H03K17/70) - H04R 17/005: {using a piezoelectric polymer} - G01H 1/00: Measuring {characteristics of} vibrations in solids by using direct conduction to the detector (G01H9/00, G01H11/00 take precedence) - G06F 3/03547: {Touch pads, in which fingers can move on a surface} - G06F 2203/0338: Fingerprint track pad, i.e. fingerprint sensor used as pointing device tracking the fingertip image - H04R 17/10: Resonant transducers, i.e. adapted to produce maximum output at a predetermined frequency - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) - 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) - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - G06V: IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING - H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M) - H04R: LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS (producing sounds with frequency not determined by supply frequency G10K) - G01H: MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES ## Abstract This disclosure provides some implementations of systems, methods and apparatus associated with a drive scheme for ultrasonic transducer pixel readout. In some implementations, a piezoelectric ultrasonic transducer has a first electrode, a second electrode, and a piezoelectric layer disposed between the first and second electrodes. The second electrode is coupled with a sampling node. A sampling diode has an input and an output. The input is coupled to receive a diode bias signal. The output is coupled with the sampling node. Controller circuitry is configured to control the diode bias signal to at least partially drive a voltage at the sampling node. Read circuitry is coupled with the sampling node to read the voltage. ## Claims ### Claim 1 An apparatus comprising: a piezoelectric ultrasonic transducer having a first electrode, a second electrode, and a piezoelectric layer disposed between the first and second electrodes, the second electrode being coupled with a sampling node; a sampling diode having an input and an output, the input coupled to receive a diode bias signal, the output coupled with the sampling node; controller circuitry configured to control the diode bias signal to at least partially drive a voltage at the sampling node; and read circuitry coupled with the sampling node to read the voltage. ### Claim 2 (depends on 1) The apparatus of claim 1, wherein the controller circuitry is configured to control the diode bias signal to switch between two voltage levels comprising a first level and a second level, the second level being asserted during a sampling window corresponding to activation of the read circuitry. ### Claim 3 (depends on 2) The apparatus of claim 2, wherein the first level corresponds to a normal mode of operation of the read circuitry, and the second level corresponds to a sampling mode of operation of the read circuitry. ### Claim 4 (depends on 1) The apparatus of claim 1, further comprising a substrate disposed adjacent to the second electrode opposite the piezoelectric layer, the substrate being a thin-film transistor (TFT) layer and comprising the sampling diode. ### Claim 5 (depends on 4) The apparatus of claim 4, further comprising a reset transistor formed in the TFT layer and coupled with the sampling diode to control resetting of the voltage. ### Claim 6 (depends on 1) The apparatus of claim 1, wherein the first electrode is coupled with one of: a ground terminal, a DC voltage source or a fixed AC voltage source. ### Claim 7 (depends on 1) The apparatus of claim 1, wherein the first electrode is floating. ### Claim 8 (depends on 1) The apparatus of claim 1, further comprising a touch controller coupled with the first electrode, the touch controller configured to provide touch control of the piezoelectric layer. ### Claim 9 (depends on 1) The apparatus of claim 1, further comprising a platen disposed adjacent to the first electrode opposite the piezoelectric layer. ### Claim 10 A method comprising: providing a diode bias signal to a sampling diode coupled with a sampling node; initiating transmission of an ultrasonic signal using a piezoelectric ultrasonic transducer having a first electrode, a second electrode, and a piezoelectric layer disposed between the first and second electrodes, the second electrode being coupled with the sampling node, the piezoelectric ultrasonic transducer capable of receiving a reflected portion of the ultrasonic signal and generating a response characteristic based on the reflected portion of the ultrasonic signal; controlling the diode bias signal to bias the diode in association with a temporary transition of a mode of operation from a normal mode to a sampling mode; and enabling sampling, during the sampling mode of operation, of an electrical signal at the sampling node. ### Claim 11 (depends on 10) The method of claim 10, wherein the diode bias signal is controlled to switch between two voltage levels comprising a first level and a second level, the first level being asserted during the normal mode of operation, the second level being asserted during the sampling mode of operation. ### Claim 12 (depends on 10) The method of claim 10, wherein read circuitry is controlled to perform the sampling during the sampling mode of operation. ### Claim 13 (depends on 10) The method of claim 10, further comprising: resetting a voltage at the sampling node using a reset switch coupled with the diode. ### Claim 14 (depends on 10) The method of claim 10, wherein a substrate is disposed adjacent to the second electrode opposite the piezoelectric layer, the substrate being a thin-film transistor (TFT) layer and comprising the sampling diode. ### Claim 15 A non-transitory computer readable medium storing program code to be executed by one or more processors, the program code comprising instructions configured to cause: providing a diode bias signal to a sampling diode coupled with a sampling node; initiating transmission of an ultrasonic signal using a piezoelectric ultrasonic transducer having a first electrode, a second electrode, and a piezoelectric layer disposed between the first and second electrodes, the second electrode being coupled with the sampling node, the piezoelectric ultrasonic transducer capable of receiving a reflected portion of the ultrasonic signal and generating a response characteristic based on the reflected portion of the ultrasonic signal; controlling the diode bias signal to bias the diode in association with a temporary transition of a mode of operation from a normal mode to a sampling mode; and enabling sampling, during the sampling mode of operation, of an electrical signal at the sampling node. ### Claim 16 (depends on 15) The computer readable medium of claim 15, wherein the diode bias signal is controlled to switch between two voltage levels comprising a first level and a second level, the first level being asserted during the normal mode of operation, the second level being asserted during the sampling mode of operation. ### Claim 17 (depends on 15) The computer readable medium of claim 15, the instructions further configured to cause: resetting a voltage at the sampling node using a reset switch coupled to the diode. ### Claim 18 An apparatus comprising: transducer means for generating an ultrasonic wave and receiving a reflected portion of the wave, the transducer means having a first electrode, a second electrode, and a piezoelectric layer disposed between the first and second electrodes, the second electrode being coupled with a sampling node; diode bias means for at least partially driving an electrical signal at the sampling node, the diode bias means coupled with the sampling node; and reading means for reading the electrical signal, the reading means coupled with the sampling node. ### Claim 19 (depends on 18) The apparatus of claim 18, wherein the diode bias means is responsive to a bias signal controlled to switch between two voltage levels comprising a first level and a second level, the second level being asserted during a sampling window corresponding to activation of the reading means. ### Claim 20 (depends on 19) The apparatus of claim 19, wherein the first level corresponds to a normal mode of operation of the reading means, and the second level corresponds to a sampling mode of operation of the reading means.