Also included is a controller unit that contains a low-frequency oscillator and a switchable driver that receives the rotation-sensor readings. Sensors that measure the rates of rotation about the yaw and pitch axis are attached to the frame. The shutters are installed in the lens spaces in the goggle or eyeglass frame. The shutters are compact, fast-acting, low-voltage, low-current liquid-crystal display devices of the polymer-dispersed liquid-crystal type. In the event that a higher rate of strobing is necessary for adequate viewing of the changing scene during rapid head movements, the rate of strobing (but not the exposure time) can be controlled in response to the readings of rate-of-rotation sensors attached to the device. The exposure time for each snapshot is less than 5 ms. A device according to this concept helps to prevent retinal slip by providing snapshots of the visual environment through electronic shutters that are brief enough that each snapshot freezes the image on each retina. The present concept of stroboscopic goggles or eyeglasses (see figure) is based on the proposition that prevention of retinal slip, and hence, the prevention of sensory mismatch, can be expected to reduce the tendency toward motion sickness. In almost every known environment that induces motion sickness, a change in the gain (in the signal-processing sense of "gain") of the vestibular system causes the motion of the eye to fail to hold images stationary on the retina, and the resulting motion of the images is termed retinal slip. Normally, an observer’s eye moves, compensating for the anticipated effect of motion, in such a manner that the image of an object moving relatively to an observer is held stationary on the retina. The shutters can be strobed at either a constant rate or a rate that depends on the rates of yaw and pitch of the wearer’s head. A Pair of Goggles or Eyeglasses contains electronic shutters in place of or in addition to lenses. When one or more sensory input(s) to the brain is not expected, or conflicts with what is anticipated, the end product is motion sickness. When information from the eyes, ears, joints, and pressure receptors are all in agreement as to one’s orientation, there is no motion sickness. Motion sickness is a product of misinformation arriving at a central point in the nervous system from the senses from which one determines one’s spatial orientation. While a number of different environmental factors can induce motion sickness, a common factor associated with every known motion environment is sensory confusion or sensory mismatch. The momentary opening of the shutters helps to suppress a phenomenon that is known in the art as retinal slip and is described more fully below. Johnson Space Center, Houston, TexasĪ device built around a pair of electronic shutters has been demonstrated to be effective as a prototype of stroboscopic goggles or eyeglasses for preventing or reducing motion sickness.
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