# US 11,029,397 B2 · Correlated time-of-flight sensor

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- Number: US 11,029,397 B2
- Document ID: US11029397B2
- Status: Granted
- Kind: B2
- Application number: 15/958,364
- Filed: 2018-04-20
- Published: 2019-10-24
- Granted: 2021-06-08
- Earliest claimed: 2018-04-20
- Assignees: OmniVision Technologies, Inc.
- Applicants: OmniVision Technologies, Inc.
- Inventors: Olivier Bulteel; Eric A. G. Webster; Lindsay Grant
- Web page: https://patentgrep.com/patent/US11029397B2

## CPC

- G01S 7/4863: Detector arrays, e.g. charge-transfer gates
- G01S 7/4865: Time delay measurement, e.g. time-of-flight measurement, time of arrival measurement or determining the exact position of a peak (peak detection in noise, signal conditioning G01S7/487)
- G01S 7/4914: of detector arrays, e.g. charge-transfer gates
- G01S 7/497: Means for monitoring or calibrating
- G01S 17/10: using transmission of interrupted, pulse-modulated waves (determination of distance by phase measurements G01S17/32)
- G01S 17/36: with phase comparison between the received signal and the contemporaneously transmitted signal
- G01S 17/894: Three-dimensional [3D] imaging with simultaneous measurement of time-of-flight at a two-dimensional [2D] array of receiver pixels, e.g. time-of-flight cameras or flash lidar
- 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

## Abstract

A time-of-flight (TOF) sensor includes a light source structured to emit light and a plurality of avalanche photodiodes. The TOF sensor also includes a plurality of pulse generators, where individual pulse generators are coupled to individual avalanche photodiodes in the plurality of avalanche photodiodes. Control circuitry is coupled to the light source, the plurality of avalanche photodiodes, and the plurality of pulse generators, to perform operations. Operations may include emitting the light from the light source, and receiving the light reflected from an object with the plurality of avalanche photodiodes. In response to receiving the light with the plurality of avalanche photodiodes, a plurality of pulses may be output from the individual pulse generators corresponding to the individual photodiodes that received the light. And, in response to outputting the plurality of pulses, a timing signal may be output when the plurality of pulses overlap temporally.

## Claims

### Claim 1

A time-of-flight (TOF) sensor, comprising:
a light source structured to emit light;
a plurality of avalanche photodiodes structured to receive the light;
a plurality of pulse generators, wherein individual pulse generators in the plurality of pulse generators are coupled to individual avalanche photodiodes in the plurality of avalanche photodiodes; and
control circuitry coupled to the light source, the plurality of avalanche photodiodes, and the plurality of pulse generators, wherein the control circuitry includes logic that when executed by the control circuitry causes the time-of-flight sensor to perform operations, including:
emitting the light from the light source;
receiving the light reflected from an object with the plurality of avalanche photodiodes;
in response to receiving the light with the plurality of avalanche photodiodes, outputting a plurality of pulses from the individual pulse generators corresponding to the individual avalanche photodiodes that received the light; and
in response to outputting the plurality of pulses, outputting a timing signal when the plurality of pulses overlap temporally.

### Claim 2 (depends on 1)

The TOF sensor of claim 1, wherein the control circuitry includes a plurality of AND gates to output the timing signal.

### Claim 3 (depends on 2)

The TOF sensor of claim 2, wherein the plurality of AND gates includes a plurality of NAND gates coupled to one or more NOR gates.

### Claim 4 (depends on 1)

The TOF sensor of claim 1, wherein the plurality of avalanche photodiodes output an analog signal, and wherein the plurality of pulses include a digital signal with a fixed duration in response to receiving the analog signal.

### Claim 5 (depends on 4)

The TOF sensor of claim 4, wherein the timing signal has a duration equal to or less than the fixed duration of the digital signal output from the plurality of pulse generators.

### Claim 6 (depends on 1)

The TOF sensor of claim 1, wherein the control circuitry further includes logic that when executed by the control circuitry causes the time-of-flight sensor to perform operations, including:
calculating a time-of-flight, using the timing signal, with the control circuitry, and wherein the time-of-flight is calculated using a time to digital converter (TDC) coupled to receive the timing signal and included in the control circuitry.

### Claim 7 (depends on 1)

The TOF sensor of claim 1, wherein the control circuitry further includes a first D flip-flop and a second D flip-flop, wherein the second D-flip flop is coupled to the first D flip-flop to receive a lock signal from the first D-flip flop.

### Claim 8 (depends on 7)

The TOF sensor of claim 7, wherein the first D flip-flop and the second D flip-flop are both coupled to receive a frame reset signal.

### Claim 9 (depends on 1)

The TOF sensor of claim 1, wherein the TOF sensor does not generate a histogram of data depicting when the light reflected from the object is received by the plurality of avalanche photodiodes.

### Claim 10

A method of calculating a time-of-flight (TOF), comprising:
emitting light from a light source;
receiving the light reflected from an object with a plurality of avalanche photodiodes;
in response to receiving the light with the plurality of avalanche photodiodes, outputting a plurality of pulses from individual pulse generators included in a plurality of pulse generators coupled to individual avalanche photodiodes included in the plurality of avalanche photodiodes, wherein the individual pulse generators that output the plurality of pulses are coupled to the individual avalanche photodiodes that received the light;
in response to outputting the plurality of pulses, outputting a timing signal from control circuitry when the plurality of pulses overlap temporally; and
calculating the time-of-flight, using the timing signal, with the control circuitry.

### Claim 11 (depends on 10)

The method of claim 10, wherein outputting the timing signal includes receiving the plurality of pulses with a plurality of AND gates coupled to the plurality of pulse generators, and wherein the plurality of AND gates output the timing signal.

### Claim 12 (depends on 11)

The method of claim 11, wherein the plurality of AND gates includes a plurality of NAND gates coupled to one or more NOR gates.

### Claim 13 (depends on 10)

The method of claim 10, wherein the plurality of avalanche photodiodes output an analog signal, and wherein the plurality of pulses include a digital signal with a fixed duration in response to receiving the analog signal.

### Claim 14 (depends on 13)

The method of claim 13, wherein the timing signal has a duration equal to or less than the fixed duration of the digital signal output from the plurality of pulse generators.

### Claim 15 (depends on 1)

The method of claim 1, wherein calculating the time-of-flight includes using a time to digital converter (TDC) coupled to receive the timing signal and included in the control circuitry.

### Claim 16 (depends on 15)

The method of claim 15, wherein calculating the time-of-flight further includes using a first D flip-flop and a second D flip-flop disposed in the control circuitry, wherein the second D-flip flop is coupled to the first D flip-flop to receive a lock signal from the first D-flip Flop.

### Claim 17 (depends on 16)

The method of claim 16, wherein the first D flip-flop and the second D flip-flop are both coupled to receive a frame reset signal.

### Claim 18 (depends on 16)

The method of claim 16, further comprising disabling the plurality of avalanche photodiodes when the lock signal is present, wherein the plurality of photodiodes are coupled to be actively quenched.

### Claim 19 (depends on 10)

The method of claim 10, wherein the control circuitry does not generate a histogram of data depicting when the light reflected from the object is received by the individual avalanche photodiodes in the plurality of avalanche photodiodes.