Device for measuring pupillary distance
First Claim
1. A device for measuring a pupillary distance comprising:
- fixation target forming means disposed in said device and including at least a light source;
a window provided in a front panel of said device in such a manner as to enable a subject to look at a fixation target in the device;
locating means for locating said front panel properly in relation to a face of said subject;
at least a converging lens fixedly mounted in said device such that an appearant viewing distance of said fixation target has a predetermined distance value and said converging lens is disposed corresponding to at least one eye of the subject;
sighting mark forming means provided on an inner side of said front panel such as to form a sighting mark which corresponds to a position of a cornea reflection image of said fixation target formed on a cornea of said subject;
sighting mark position control means for enabling an inspector to control a position of said sighting mark in relation to the position of said cornea reflection image;
observation means for enabling said inspector to observe a front portion of an eye of said subject;
sighting mark position reading means for reading a position of said sighting mark at least at a preselected viewing distance;
viewing distance setting means for setting a viewing distance at which said pupillary distance is desired to be determined;
computing means for determining the pupillary distance at the desired viewing distance set by said viewing distance setting means based upon the position of said sighting mark at said preselected viewing distance; and
computing display means for displaying the result of said means.
1 Assignment
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Accused Products
Abstract
Since a certain relationship exists between a pupillary distance at a viewing distance and a pupillary distance to another viewing distance, the pupillary distance at a desired viewing distance can be obtained by making a predetermined correction in the results of a pupillary distance measurement at a fixed viewing distance, without requiring a convexed lens in the device to be moved. The fixed viewing distance is preferably set at a small value such as 1 to 2 meters so that problems such as failure in forming a fused image due to machine near sightedness can be avoided. The device has a sighting mark forming device which can be installed at any portion of the measuring device for enabling easy assembly, unlike conventional measuring devices which require that the sighting mark forming device is located in relation to the (corneal) vertex distance of the subject.
18 Citations
11 Claims
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1. A device for measuring a pupillary distance comprising:
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fixation target forming means disposed in said device and including at least a light source; a window provided in a front panel of said device in such a manner as to enable a subject to look at a fixation target in the device; locating means for locating said front panel properly in relation to a face of said subject; at least a converging lens fixedly mounted in said device such that an appearant viewing distance of said fixation target has a predetermined distance value and said converging lens is disposed corresponding to at least one eye of the subject; sighting mark forming means provided on an inner side of said front panel such as to form a sighting mark which corresponds to a position of a cornea reflection image of said fixation target formed on a cornea of said subject; sighting mark position control means for enabling an inspector to control a position of said sighting mark in relation to the position of said cornea reflection image; observation means for enabling said inspector to observe a front portion of an eye of said subject;
sighting mark position reading means for reading a position of said sighting mark at least at a preselected viewing distance;viewing distance setting means for setting a viewing distance at which said pupillary distance is desired to be determined; computing means for determining the pupillary distance at the desired viewing distance set by said viewing distance setting means based upon the position of said sighting mark at said preselected viewing distance; and computing display means for displaying the result of said means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification