Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
2000-12-18
2003-04-01
Tong, Nina (Department: 2632)
Communications: electrical
Condition responsive indicating system
Specific condition
C340S576000, C340S573100, C382S117000, C600S558000
Reexamination Certificate
active
06542081
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to systems and methods for monitoring movement of a human eye, and more particularly to systems and methods for real-time monitoring of fatigue and other states of mind in individuals, purposeful communication, and/or controlling devices based upon movement of their eye, eyelid, and/or other components of their eye.
BACKGROUND
There have been attempts to use movement of the human eye to monitor involuntary conditions, specifically a person's wakefulness or drowsiness. For example, U.S. Pat. No. 3,863,243 discloses a device that sounds an alarm to warn a person using the device that they are beginning to fall asleep. The device includes a frame similar to a set of eyeglasses onto which is mounted a fiber optic bundle and a photocell that are directed towards the user's eye when the frame is worn. The fiber optic bundle is coupled to a source of light and a pulse generator to emit light towards the user's eye.
The photocell detects the intensity of light reflected off of the user's eye, i.e., either by the eyelid when the eye is closed or the eye surface when the eye is open. Circuitry receives a signal from the photocell, and uses a timer to distinguish between regular blinks, and an extended time period during which the eye is closed, i.e., a time period that may indicate that the person is falling asleep. When a threshold time elapses, an alarm is sounded to notify and/or wake the user. 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.
Other devices, such as those disclosed in U.S. Pat. Nos. 5,469,143 and 4,359,724, directly engage the eyelid or eyebrow of a user to detect movement of the eye and activate an alarm when a drowsiness condition is detected. 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. For example, it may be desirable to measure the percentage of total time that the eyelids are closed as a function of time or the area of the palpebral fissure that is covered by the eyelid as the eye is opened or closed, commonly known as “PERCLOS,” for example during medical research or when monitoring driver alertness. 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.
Further, infrared cameras or other devices may be used to monitor a driver's awareness, which are typically mounted on the dashboard, roof or other fixed mounting within the user's vehicle. 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.
Accordingly, it is believed that a more effective system and method for monitoring eye and/or eyelid movement would be considered useful.
SUMMARY OF THE INVENTION
The present invention is directed to systems and methods for monitoring eye movement. Generally, humans blink at least about 5-30 times per minute, or about 7,000-43,000 times per day. Each involuntary-reflexive blink lasts about 200-300 milliseconds, and generally averaging about 250 milliseconds, amounting to about 1,750-10,800 seconds per day of eye closure due to involuntary blinking. As tiredness or sleepiness occurs, the eye blink gets longer and slower until the eyes begin to close for short term “microsleeps,” i.e., sleep conditions that last for about 3-5 seconds or longer, or for prolonged sleep. The present invention provides systems and methods for monitoring, measuring, and/or responding to eye movement, e.g., nonpurposeful reflexive eyeblinks.
In a preferred embodiment, the system includes an emitter and a sensor in a predetermined relationship with an eye such that the emitter emits light and the sensor detects light from the emitter, the sensor producing a light intensity signal indicating when the eye is open or closed. More preferably, the emitter is directed or aimed at the eyelid and eye, while the sensor detects eyelid-reflected light, since, unlike the eyelid, the eye ball (except the retina, which may cause a “red reflex” under white light conditions or “white pupil” under infrared light) does not reflect substantial light back to the sensor. Circuitry is coupled to the sensor for converting sequential light intensity signals corresponding to eyelid movement received from the sensor into a stream of data, and a processor converts the stream of data into an understandable message.
The circuitry for converting sequential light intensity signals may compare the sequential light intensity signals with a predetermined time threshold to detect voluntary-intentional or unintentional-involuntary sequences of eyelid movements, corresponding, for example, to a predetermined binary code. Memory circuitry may be coupled to the processor for storing the stream of data and/or a communication device, such as a video monitor or synthesized voice module, may be coupled to the processor for communicating the understandable message. In addition, a control system may be coupled to the processor, and the understandable message may include a command for controlling equipment, including electrical or electronic equipment, machinery, or a computer or computer accessory devices coupled to the control system.
The system preferably also includes a transmitter, preferably a radio frequency transmitter, for wireless transmission of the stream of data to a remote location. Alternatively, other forms of wireless transmission, e.g. infrared, as well as hard-wire connections may be used. The processor, as well as the memory circuitry, communication device, and/or control system, may be located at the remote location, and a receiver may be coupled to the processor for receiving the stream of data from the transmitter.
In a preferred form, the system includes a detection device having a frame adapted to be worn on a person's head, e.g., with the frame resting on the bridge of the user's nose and/or ears. The frame has the emitter and sensor thereon such that the emitter and sensor are oriented towards the person's eye when the frame is worn on the person's head. Preferably, the emitter and sensor are a single solid state device, such as a biosensor device, that emits light within a predetermined frequency range, for example infrared light, towards the eye and detects the emitted light reflected off of the eyelid, respectively.
In another preferred embodiment, a system for monitoring a blinking cycle of a person from a remote location is provided that includes an emitter for directing light towards an eye, and a sensor in a predetermined relationship with the emitter for detecting the emitted light reflected off of the eye, the sensor producing an output signal indicating when the eye is open or closed. Depending upon the relative position of the emitter and sensor with respect to the moving eyelid, the emitter light may be reflected off of the eyelid back to the sensor, or diffused by the surface of the eyeball.
A transmitter is coupled to the sensor for wire
Bingham & McCutchen LLP
Tong Nina
LandOfFree
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