System and method for monitoring eye movement

Abstract

Apparatus for monitoring movement of a person's eye, e.g., to monitor drowsiness. The system includes a frame that is worn on a person's head, an array of emitters on the frame for directing light towards the person's eye, and an array of sensors on the frame for detecting light from the array of emitters. The sensors detect light that is reflected off of respective portions of the eye or its eyelid, thereby producing output signals indicating when the respective portions of the eye is covered by the eyelid. The emitters project a reference frame towards the eye, and a camera on the frame monitors movement of the eye relative to the reference frame. This movement may be correlated with the signals from the array of sensors and / or with signals from other sensors on the frame to monitor the person's level of drowsiness.

Description

[0001]This application is a continuation of application Ser. No. 11 / 097,942, filed Apr. 1, 2005, issued as Re 39,539 on Apr. 3, 2007, which is a reissue of application Ser. No. 09 / 740,738, U.S. Pat. No. 6,542,081, which is a continuation-in-part of application Ser. No. 09 / 104,258, filed Jun. 24, 1998, issuing as U.S. Pat. No. 6,163,281 on Dec. 19, 2000, which is a continuation-in-part of application Ser. No. 08 / 978,100, filed Nov. 25, 1997, now U.S. Pat. No. 6,246,344 issued Jun. 12, 2001, which is a continuation-in-part of application Ser. No. 08 / 699,670, filed Aug. 19, 1996, now U.S. Pat. No. 5,748,113 issued May 5, 1998, the disclosures of which are expressly incorporated herein by reference.[0002]Notice: More than one reissue application has been filed for the reissue of U.S. Pat. No. 6,163,281. The reissue applications are application Ser. No. 11 / 097,942, issued as Re 39,539, Ser. No. 11 / 732,828 (the present application), which is a continuation reissue of Re 39,539, and Ser. N...

AI Technical Summary

Benefits of technology

[0020]Thus, a system in accordance with the present invention may detect eyelid movement of the user, distinguish normal blinks from other voluntary or involuntary eyelid movement, and produce a stream of data. The stream of data may be converted into an understandable message, such as a binary code, a command for controlling a piece of equipment, or an indicator of the user's physical, mental or emotional state. Thus, the system may provide a convenient and / or effective method for voluntary or involuntary communication based simply upon movement of the user's eye.

[0026]In addition, the output signal from the one or more sensors may be correlated with video signals produced by the camera monitoring movement of the eye relative to the reference frame, thereby determining the person's level of drowsiness.

Problems solved by technology

This device, however, requires running wires and fiber optic bundles from the frame to external components, e.g., the pulse generator and the required circuitry, and for this reason, the device may be awkward or inconvenient to use.

These mechanical devices may be mounted directly onto the skin to detect muscle movement or may involve placing a mechanical arm against the eyelid, and consequently may be uncomfortable to wear and use.

In addition, some devices may detect eye movement, but may not be able to distinguish when the eye is opened or closed.

Devices that merely detect eye muscle movement or eyelash movement may not be able to distinguish when the eye is open or closed, and consequently may not be able to measure PERCLOS.

Similarly, such devices may not measure other parameters, such as velocity of eyelid closing or opening, acceleration or deceleration characteristics, duration of open or closed eye states, intervals between eye blinks and / or partial versus full eye blinks or eye closures.

Such devices, however, require that the user maintain constant eye contact with the camera.

In addition, they do not monitor eyelid movement if the user looks sideways or downwards, turns around, exits the vehicle or compartment in which he or she is being monitored, or if the camera moves relative to the individual.

Further, such cameras may have problems seeing through eyeglasses, sunglasses, or even contact lenses, and may not operate effectively in sunlight.

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