# US 4,397,531 A · Eye closure discrimination system

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- Number: US 4,397,531 A
- Document ID: US4397531A
- Status: Granted
- Kind: A
- Application number: 06/278,525
- Filed: 1981-06-29
- Granted: 1983-08-09
- Earliest claimed: 1981-06-29
- Assignees: Honeywell Inc.
- Inventors: David E. B. Lees
- Web page: https://patentgrep.com/patent/US4397531A

## CPC

- A61B 3/145: {by video means}
- A61B 5/1103: {Detecting muscular movement of the eye, e.g. eyelid movement}
- A61B 5/6821: {Eye}
- A61B 2503/22: Motor vehicles operators, e.g. drivers, pilots, captains
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)

## Abstract

A system for determining whether an eye within a field of view is closed for a predetermined period of time and for distinguishing between reflections from an open eye and any specular reflections within the field of view. The system comprises detection apparatus for viewing the field of view. Also included is a first light source positioned so that light arising from the light source causes reflections from both an open eye and from any specular reflectors within the field of view to be detected by the detection apparatus. The system further includes a second light source positioned so that light arising from the light source causes reflections from the open eye to be directed so as not to be detected by the detection apparatus and so that light arising from the light source causes reflections from any specular reflectors in the field of view to be directed so as they are detected by the detection apparatus. The detection apparatus comprises apparatus for comparing over a predetermined period of time the number of reflections arising from the first and second light sources. If the number of reflections arising from the first and second light sources during the predetermined period of time are equal, it is assumed that the eye was closed for the predetermined period of time.

## Claims

### Claim 1

A system for determining whether an eye within a field of view is closed for a predetermined period of time and for distinguishing between reflections from an open eye and any specular reflections within the field of view, comprising:
detection means for viewing the field of view;
a first light source positioned so that light arising from the light source causes reflections from both an open eye and from any specular reflectors within the field of view to be detected by the detection means;
a second light source positioned so that light arising from the light source causes reflections from the open eye to be directed so as not to be detected by the detection means and so that light arising from the light source causes reflections from any specular reflectors in the field of view to be directed so as to be detected by the detection means;
the detection means comprising means for comparing over a predetermined period of time the number of reflections arising from the first and second light sources;
whereby, if the number of reflections arising from first and second light sources are equal during the predetermined period of time, it is assumed that the eye was closed for the predetermined period of time.

### Claim 2 (depends on 1)

The apparatus of claim 1 wherein the detection means comprises means for alternately sequencing the first and second light sources.

### Claim 3 (depends on 2)

The apparatus of claim 2 wherein the detection means comprises a beamsplitter for reflecting light from the first and second light sources into the field of view and for transmitting reflected light to the detection means.

### Claim 4 (depends on 3)

The apparatus of claim 3 wherein the detection means comprises means for providing a first control signal if the eye is closed for the predetermined period of time.

### Claim 5 (depends on 4)

The apparatus of claim 4 wherein the detection means further comprises means for requiring the presence of a second control signal occurring concurrently with the first control signal before a third control signal is generated.

### Claim 6 (depends on 1)

The apparatus of claim 1 wherein the detection means comprises a beamsplitter for reflecting light from the first and second light sources and into the field of view and for transmitting reflected light to the detection means.

### Claim 7 (depends on 6)

The apparatus of claim 6 wherein the detection means comprises means for providing a first control signal if the eye is closed for the predetermined period of time.

### Claim 8 (depends on 7)

The apparatus of claim 7 wherein the detection means further comprises means for requiring the presence of a second control signal occurring concurrently with the first control signal before a third control signal is generated.

### Claim 9 (depends on 1)

The apparatus of claim 1 wherein the detection means comprises means for providing a first control signal if the eye is closed for the predetermined period of time.

### Claim 10 (depends on 9)

The apparatus of claim 9 wherein the detection means further comprises means for requiring the presence of a second control signal occurring concurrently with the first control signal before a third control signal is generated.