# US 2017/0254703 A1 · Pyroelectric ir motion sensor

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- Number: US 2017/0254703 A1
- Document ID: US20170254703A1
- Status: Published application
- Kind: A1
- Application number: 15/057,423
- Filed: 2016-03-01
- Published: 2017-09-07
- Earliest claimed: 2016-03-01
- Assignees: Google Inc.
- Applicants: Google Inc.
- Inventors: Aveek Ravishekhar Purohit; Anurag Gupta
- Web page: https://patentgrep.com/patent/US20170254703A1

## CPC

- G01J 5/0025: {Living bodies (ear thermometers G01J5/0011; detecting, measuring or recording for diagnostic purposes A61B5/00)}
- G01J 5/0275: {Control or determination of height or distance or angle information for sensors or receivers}
- G01J 5/0806: Focusing or collimating elements, e.g. lenses or concave mirrors
- G01J 5/34: using capacitors, e.g. pyroelectric capacitors
- G01S 17/04: Systems determining the presence of a target
- G01J: MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY (light sources F21, H01J, H01K, H05B; investigating properties of materials by optical means G01N)
- 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

Methods and apparatus relating to a pyroelectric IR (PIR) motion sensor are provided. The provided PIR motion sensor can be used to determine an angular position of a moving person relative to the PIR motion sensor. The provided PIR motion sensor can be used to determine a proximity of a moving person relative to the PIR motion sensor. The angular position and the proximity can be used to identify a false alarm, estimate occupancy of a region, enable tracking of a target, and the like. In an example, the provided PIR motion sensor includes multiple PIR sensors and a Fresnel lens including lenslets configured to direct received IR radiation to at least two of the PIR sensors.

## Claims

### Claim 1

A motion sensing device, comprising:
an array of pyroelectric IR (PIR) sensors; and
a Fresnel lens including a plurality of lenslets, wherein two or more lenslets are configured to direct received IR (IR) radiation to at least two of the PIR sensors in the array of PIR sensors.

### Claim 2 (depends on 1)

The motion sensing device of claim 1, wherein the Fresnel lens is asymmetric.

### Claim 3 (depends on 1)

The motion sensing device of claim 1, wherein the focal point of the Fresnel lens is behind the array of PIR sensors.

### Claim 4 (depends on 1)

The motion sensing device of claim 1, wherein the array of PIR sensors has at least a pair of PIR sensors separated from a third PIR sensor by a substantially similar distance.

### Claim 5 (depends on 1)

The motion sensing device of claim 1, wherein the array of PIR sensors includes at least two PIR sensors mounted such that the array of PIR sensors has a wider field of detection than the field of detection of a single constituent PIR sensor.

### Claim 6 (depends on 1)

The motion sensing device of claim 1, further comprising a security system coupled to the array of PIR sensors.

### Claim 7

A non-transitory computer-readable medium, comprising:
instructions stored by the non-transitory computer-readable medium, wherein the instructions are configured to cause a processor to:
initiate receiving pyroelectric IR (PIR) sensor array data;
initiate extracting angular position features from the PIR sensor array data; and
initiate identifying the relative angular position by applying a pattern matching algorithm to the angular position features.

### Claim 8 (depends on 7)

The non-transitory computer-readable medium of claim 7, wherein the PIR sensor array data is a time series of data.

### Claim 9 (depends on 7)

The non-transitory computer-readable medium of claim 7, wherein the angular position features include one or more of a peak position, an amplitude, or a polarity.

### Claim 10 (depends on 7)

The non-transitory computer-readable medium of claim 7, wherein the instructions are configured to cause the processor to initiate training the pattern matching algorithm with training data.

### Claim 11 (depends on 7)

The non-transitory computer-readable medium of claim 7, wherein the instructions are configured to cause the processor to:
initiate determining, from the PIR sensor array data, a normalized output magnitude across all PIR sensors;
initiate comparing the relative angular position to a proximity lookup table to identify a proximity threshold; and
initiate comparing the normalized output magnitude to the proximity threshold to determine if the target is within a threshold distance, beyond a threshold distance, or at a threshold distance.

### Claim 12 (depends on 11)

The non-transitory computer-readable medium of claim 11, wherein the instructions are configured to cause the processor to initiate training the proximity lookup table with training data.

### Claim 13 (depends on 11)

The non-transitory computer-readable medium of claim 11, wherein the instructions are configured to cause the processor to initiate, in response to identifying the target is within the threshold distance, initiating turning on one or more of a camera, a light, an alarm, or a combination thereof.

### Claim 14

An apparatus, comprising:
a processor; and
a memory coupled to the processor and configured to cause the processor to:
initiate receiving pyroelectric IR (PIR) sensor array data;
initiate extracting angular position features from the PIR sensor array data; and
initiate identifying the relative angular position by applying a pattern matching algorithm to the angular position features.

### Claim 15 (depends on 14)

The apparatus of claim 14, wherein the PIR sensor array data is a time series of data.

### Claim 16 (depends on 14)

The apparatus of claim 14, wherein the angular position features include one or more of a peak position, an amplitude, or a polarity.

### Claim 17 (depends on 14)

The apparatus of claim 14, wherein the memory is further configured to cause the processor to initiate training the pattern matching algorithm with training data.

### Claim 18 (depends on 14)

The apparatus of claim 14, wherein the memory is further configured to cause the processor to:
initiate determining, from the PIR sensor array data, a normalized output magnitude across all PIR sensors;
initiate comparing the relative angular position to a proximity lookup table to identify a proximity threshold; and
initiate comparing the normalized output magnitude to the proximity threshold to determine if the target is within a threshold distance, beyond a threshold distance, or at a threshold distance.

### Claim 19 (depends on 18)

The apparatus of claim 18, wherein the memory is further configured to cause the processor to initiate training the proximity lookup table with training data.

### Claim 20 (depends on 18)

The apparatus of claim 18, wherein the memory is further configured to cause the processor to initiate, in response to identifying the target is within the threshold distance, turning on one or more of a camera, a light, an alarm, or a combination thereof.

### Claim 21 (depends on 14)

The apparatus of claim 14, further comprising a security system coupled to the processor.

### Claim 22 (depends on 14)

The apparatus of claim 14, wherein the processor is a microprocessor, a microcontroller, a digital signal processor, a field programmable gate array, a programmable logic device, an application-specific integrated circuit, a controller, a non-generic special-purpose processor, a state machine, a gated logic device, a discrete hardware component, a dedicated hardware finite state machine, or a combination thereof.

### Claim 23

A method for determining a relative angular position of a target of a motion sensor, comprising:
receiving pyroelectric IR (PIR) sensor array data;
extracting angular position features from the PIR sensor array data; and
identifying the relative angular position by applying a pattern matching algorithm to the angular position features.

### Claim 24 (depends on 23)

The method of claim 23, wherein the PIR sensor array data is a time series of data.

### Claim 25 (depends on 23)

The method of claim 23, wherein the angular position features include one or more of a peak position, an amplitude, or a polarity.

### Claim 26 (depends on 23)

The method of claim 23, further comprising training the pattern matching algorithm with training data.

### Claim 27 (depends on 23)

The method of claim 23, further comprising:
determining, from the PIR sensor array data, a normalized output magnitude across all PIR sensors;
comparing the relative angular position to a proximity lookup table to identify a proximity threshold; and
comparing the normalized output magnitude to the proximity threshold to determine if the target is within a threshold distance, beyond a threshold distance, or at a threshold distance.

### Claim 28 (depends on 27)

The method of claim 27, further comprising training the proximity lookup table with training data.

### Claim 29 (depends on 27)

The method of claim 27, further comprising, in response to identifying the target is within the threshold distance, initiating turning on one or more of a camera, a light, an alarm, or a combination thereof.