Optics: eye examining – vision testing and correcting – Spectacles and eyeglasses – With antiglare or shading
Reexamination Certificate
2000-03-15
2001-06-12
Mack, Ricky (Department: 2873)
Optics: eye examining, vision testing and correcting
Spectacles and eyeglasses
With antiglare or shading
C351S045000
Reexamination Certificate
active
06244703
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to the field of glare reduction devices and other electronic vision devices. In particular, it relates to a method and apparatus for calibrating such a device to accommodate differences in facial geometry and other variations in the placement of a lens element of the device relative to the eye of a user.
When driving into the sun, the sun's glare frequently results in considerable discomfort to the driver. In some cases, the glare is so intense that the driver's pupils constrict to the point at which the rest of the field of view appears dark. This interruption in the driver's ability to see can arise without warning, for example when the driver turns a corner or goes around a bend, only to be greeted with the full force of the solar glare.
If the driver continues to drive, there is a significant risk of a collision arising from the driver's inability to see.
A personal glare reduction device has a lens medium that can be selectively darkened to at least partially cover a user's eye. Such a lens medium can, for example, employ the technology of an LCD display with individually addressable elements. A personal glare reduction device is typically coupled with a directional light sensor that determines the angular positions of bright light sources in the user's field of view. A processor obtains these angular positions and uses them to determine what points are to be darkened in order to prevent light from those light sources from reaching the user's eyes. The processor then automatically darkens the lens medium at those points through which light from the bright light sources passes on its way to the eye. This improves vision elsewhere in the user's field of view and reduces, if not eliminates, the onset of temporary blindness resulting from solar glare.
In order to locate the darkened portions of the lens medium correctly, it is desirable that a personal glare reduction device has accurate information as to the location of the lens element relative to the pupil of the user's eye. A common embodiment of a personal glare reduction device, which is one form of an electronic vision device according to the invention, is sunglasses, and other forms of eyeglasses. These embodiments have two optical windows, typically lens elements, one for each eye of the wearer. Because of both the natural variation in the way eyeglasses sit on people's faces and on the natural variations in eye spacing, it is desirable that a personal glare reduction device be provided with a calibration procedure. Such a calibration procedure is preferably intuitive and simple to perform.
U.S. Pat. No. 4,848,890 to Horn teaches a visor in which points on the visor are selectively darkened in response to the location of a light source. The Horn device includes a processor for identifying the angular location of a light source relative to the visor. In response to the angular location of the light source, the Horn device looks up a corresponding point or points in a look-up table, and darkens the visor at those points. However, no explicit means of adjustment is taught for calibrating the device to a particular user. Thus, in response to light incident from a particular angle, the Horn device darkens the same points on the visor without regard to any variations in the location of the visor relative to the user's pupil.
US Pat. No. 5,671,035 to Barnes teaches a light intensity reduction device containing a photosensitive element with a masking array to selectively darken output lenses for point-by-point light blocking. Barnes teaches a method for calibrating the device to an individual user by entering a programming mode in which the user manipulates a plurality of switches in an effort to direct a single darkened element on each lens to a position directly above the center of the eye.
One problem with the calibration method taught by Barnes is that it may be difficult for the user to determine exactly where the position directly above the center of the eye is. Even small errors in attempting to ‘look straight ahead,’ or in perceiving the location of the darkened element, can lead to inaccurate calibration. In addition, the method taught by Barnes is time-consuming and requires that the user perform physically demanding tasks such as holding the head perfectly steady while attempting to adjust the location of a small darkened region or spot using controls with which, given the frequency of calibration, a user is unlikely to be familiar. The hand-eye coordination required to calibrate the Barnes device successfully is thus comparable to that required to do well in many video-games.
It is thus a purpose of the present invention to provide a quick, simple, and accurate method of calibrating a personal glare reduction device and other electronic vision devices, and to provide corresponding apparatus.
Other objects of the invention will in part be obvious and will in part appear hereinafter.
SUMMARY OF THE INVENTION
One aspect of the present invention is a method for calibrating a personal glare reduction device having a darkened spot at a location defined by lens coordinates. A processor calculates the lens coordinates on the basis of the direction to the glare source, as measured by a directional light sensor associated with the glare reduction device. By frequently updating the lens coordinates in response to the direction to the glare source, the processor causes the darkened spot to track the glare source. Due to variations as in facial geometry or placement of the eyes relative to the device, the device may be out of alignment with the user's eye, causing the desired effect of the device to be compromised or absent. For this reason, it is necessary to calibrate the personal glare reduction device to account for differences in facial geometry.
The method of the invention includes the step of suspending the tracking function of the personal glare reduction device, thereby fixing the lens coordinates of the darkened spot at a calibration site. The user then turns its head so as to place the darkened spot in line with the glare source, thereby occluding the glare source with the darkened spot. The motion of the user's head results in a change in the direction to the glare source, as seen from the directional light sensor. The user then instructs the personal glare reduction device to evaluate a correction angle on the basis of this new direction angle to the glare source as measured by the directional light sensor.
In a preferred embodiment, calibration is made quick and intuitive by providing a user-interface having one or more buttons which, when pressed, signal the device to suspend its usual tracking of bright light sources and instead to keep the darkened spot fixed in place on the lens until the button is released. The user then turns its head so that the darkened spot on the lens occludes the glare source. With the glare source thus occluded, the user releases the button. This sends a signal instructing the processor to use geometrical relationships and the information from the directional light sensor to determine the amount of correction to the previous coordinate value.
Further, the method and apparatus of the invention adaptively calibrate an electronic vision device to a user who wears, mounts or otherwise locates a lens element of the device in front of an eye. The adaptive calibration according to the invention provides coordinate information that the EVDevice employs to match the placement of one or a pair of lens elements relative to one or both eyes of the user.
The method and apparatus of the invention are understood to be applicable to many types and forms of optical viewing devices. Examples include eye glasses (spectacles), sunglasses, goggles, ophthalmoscopes, microscopes, and other viewers and like displays. For clarity of description and without restriction on the scope of practice, the invention is described with particular reference to eyeglasses.
In general, an electronic vision
Resnikoff Howard L.
Resnikoff Nathaniel
Foley Hoag & Eliot LLP
Mack Ricky
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