Optics: eye examining – vision testing and correcting – Eye examining or testing instrument – Subjective type
Reexamination Certificate
2000-02-22
2001-04-24
Manuel, George (Department: 3737)
Optics: eye examining, vision testing and correcting
Eye examining or testing instrument
Subjective type
C351S243000
Reexamination Certificate
active
06220708
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a method and a device for producing multicolored patterns, for example, patterns for testing the color vision or the reaction by means of at least one switchable light source and at least two differently colored, transparent color segments, which are moved alternately into the beam path of the light source.
BACKGROUND OF THE INVENTION
In order to test the color vision of a person, ophthalmologist and optometrists often use Ishihara images, which images are named after their developer. These are patterns of colored dots, which are presented to the person being tested. If the person recognizes the patterns, the person being tested may lack color recognition in this area. The lack of color recognition is possible in various degrees and expressions. The most familiar expression is the red-green weakness in men. In order to be able to determine the exact extent of the color blindness, a plurality of Ishihara images are needed. At a time of testing, the course of testing, which has so far taken place, is thereby important and determines which images will be presented to the person being testing during the further course of testing. In order to be able to cover the entire spectrum of the possible color blindness, an ophthalmologist or an optometrist must therefore have available a plurality of Ishihara images. The images, which as a rule are collected in books, are however, expensive to purchase. It is furthermore complicated to manually select the images necessary for the respective next step of testing from the plurality of existing images.
An alternative to the printed Ishihara images would be, for example, dias of the Ishihara images, which would be projected onto a screen by a slide projector. However, even when using slide transparencies, the problem of the scope, the image collection or the unsatisfactory possibility of the control of the sequence of the color vision test would continue to exist.
Also, as an alternative, it would be conceivable to use a picture screen, such as a LCD picture screen or a classic tube screen. However, these would be too expensive in relationship to their purpose so that the use of a picture screen to data does not represent a satisfactory alternative to the printed Ishihara images.
A device of the above-mentioned type, however, is not limited to the production of Ishihara images. Rather any desired patterns can be created with such a device. These may also, in the case of one single light source, be timed patterns of signals from the light source.
The purpose of the invention is therefore to provide a technically simple and inexpensive method and a vision-testing device, with which multicolored patterns can be produced. Whereby, in particular, a quick flexible automatic change between the multicolored patterns is possible.
SUMMARY OF THE INVENTION
This purpose is attained according to the invention in such a manner that the light source or the light sources shine through each color segment in a time interval predetermined by a control and individual colors are produced in this manner, whereby the time intervals of the individual colors follow one another so quickly that the color-merging frequency is reached or exceeded. The individual colors of each individual light source merge into a mixed color so that a flicker-free image is created.
A light beam, which starts out from a light source, thus moves through a color segment. Such a color segment may, for example, be a transparent foil. From there, the now colored light beam enters the eye of a viewer. Various color segments are now alternately moved into the light beam. This is done so quickly that the eye can no longer recognize the change between the individual color segments. A mixed color is thus created in the eye of the viewer from the colors of the color segments which are moved into the light beam. The time intervals, during which the light source thus shines through the color segments, must be shorter than the color-merging frequency of the eye. The method is made possible by the inertia of the eye.
An advantageous further development of the invention is that the color segments can be moved in equal time intervals into the beam path of each light source, and the switch-on duration of the light sources is controlled individually for each individual light source and for each individual color segment. It is advantageous when the color segments are parts of a circular color screen which is rotated about its center axis, and the light sources which shine through the color screen or the color segments of the color screen, are light diodes. The light diodes are then arranged parallel in a plane with respect to the color screen, and the control regulates the speed of the color screen and controls the switch-on duration of each individual light diode for each individual color segment.
A further advantageous development of the method is that the light source is continuously switched on and the color segments are moved into the beam paths of the light sources for varying times.
A device of the invention, which attains the set purpose, has at least one switchable light source and at least two transparent color segments which can be moved alternately into the beam path of the light source. The set purpose is attained in such a manner that the color segments form parts of a circular color screen which can be rotatably driven about the center axis and above the light source. A control is provided with which the rotational speed of the color screen can be regulated. The switch-on duration of each individual light source can be controlled for each color segment.
The light sources can, according to the invention, be light emitting diodes. Particular advantageous are white light diodes.
The light sources can, according to the invention, be arranged in one plane parallel to the color screen. It is thereby advantageous that the light sources are arranged in one line radially with respect to the axis of rotation of the color screen or are arranged matrix-shaped.
A special embodiment of the invention makes it possible to control the light intensity of each individual light source with the control. The device also can, according to the invention, be protected against stray or scattered light leakage by a housing having a viewing window. It is possible thereby to arrange only the light sources and the color screen in the housing. The device can, according to the invention, be a part of an anomaloscope of a projector, a vision-testing device or a reaction-testing device.
The purpose of the invention can be attained in a vision-testing device, in particular a vision-testing device with a clear view, which is provided with an imaging device of a test object provided within the focal distance of the imaging device and being reproducible at varying distances or intervals. In order to produce the test object, a device is provided having at least one switchable light source and at least two transparent color segments. The color segments must be movable alternately into a beam path of the light source, and the color segments must form parts of a circular color screen. The color screen can be driven rotatably about its center axis. A control can regulate the speed of the color screen and control the switch-on duration of each individual light source for each color segment.
Such a vision-testing device can advantageously have an optic deflecting device in the beam path between the imaging or reproducing device and the test object, which deflects the beam path at 180° into two beam-path fragments. This optic deflecting device can then be moved in the direction of the two thus formed beam-path fragments, which are parallel to one another, and the test object is constructed nonmovably in this direction. The optic structural elements lying in the beam path have a width such that, even in the case of a large spacing between the pupils of a person being tested, both eyes can participate in the test. In order to produce further test objects, it is possible to provide a test screen
Flynn ,Thiel, Boutell & Tanis, P.C.
Manuel George
Oculus Optikgeraete GmbH
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