DE2845173C2 - Device for measuring the interpupillary distance - Google Patents

Description

20th

The invention relates to a device for measuring the interpupillary distance according to the preamble of the claim 1.

The parallax-free measurement of the total interpupillary distance is essential for the production of corrective optical glasses (Distance of the pupils from each other) and the individual pupil distances (distance of one pupil in each case from the bridge of the nose) with a given working distance of the utmost importance, otherwise incorrect corrections possible are.

Devices for measuring the interpupillary distance using) 5 Light rays emitted by light sources that project a light mark directly onto the cornea already described in US Patents 1,443,704 and 1,327,163. You assign two on a rail arranged with a scale on projection devices, one of which is displaceable along the rail. Their beam paths are aligned parallel to one another. A handle attached to the rail is used for Holding the device during the measuring process with one projection device on the rail is shifted until the respective lamp filament as on both pupils of the patient light line is shown. The patient looks at any point chosen.

Since this device must be held freely in the hand, parallax errors are caused by holding it at an angle inevitable. In addition, only a total interpupillary distance can be measured, which often does not have exact lens centering made possible because in many people the bridge of the nose is not exactly in the middle.

According to Prof. Dr. Th. Graff "Measurements of the optical magnitudes of the eyes and glasses", Karlsruhe 1960, page 13 bis 17, and DE-Auslegeschrift 12 97 357 it is on known to also measure the interpupillary distance, including corresponding arrows or lines each eye should be brought and, while aiming, pushed into the middle of the pupils as possible, whereupon read off the measured values separately for each eye on a scale. But this principle is also included Parallax errors afflicted.

Accordingly, the object on which the invention is based is that of US Pat 13 27 163 described device for measuring the total pupil distance to the effect that parallax errors are eliminated in the measurement and also the measurement of the interpupillary distances is made possible.

By fixing the device on the nose by means of an adjustable arm attached A parallax-free measurement can be carried out on the nose pad, which corresponds to a bridge of glasses. In addition, results a correct reference point for measuring the interpupillary distance from the bridge of the nose. Next to the Total interpupillary distance, the individual interpupillary distances are displayed on special scales. An advantageous one Embodiment of the invention provides according to claim 2 that the device has a defined near fixation point having.

The invention is explained in more detail below, for example with reference to the drawings; it shows

Fig. 1 is a plan view of the opened device with arranged on the bridge of the nose of a patient Nose pad,

F i g. 2 shows a section along the optical axis a projection unit.

The device shown in the embodiment has a box-shaped housing (1) in which a extendable nose pad (2) is installed perpendicular to the front. This is with a tape measure (3) coupled, which shows the working distance, parallel to this axis are two movable left and right Tubes (4) attached, which contain the light sources (5) and converging lenses (6). These are adjustable. With With the help of rotary knobs mounted on the drive shafts (7), the tubes are individually parallel to the axis to move the nasal pad. The individual interpupillary distances can be read on the scales (8) and on the The scale (9) shows the total interpupillary distance. The near fixation point (10) is above the extendable Nose hook attached.

The device is handled as follows.

If the test object and the examiner sit opposite each other, the device is placed on the table between the two. Means The nose pad (2) ensures that the device sits securely on the bridge of the nose. With the possibility of Changing the distance of the nose pad allows you to set the desired working distance. Of the The test specimen fixes the near fixation point (10). To measure the distance between the pupils, the person looks DUT into the distance, or into the opposite Eye of the examiner, with the eye not to be measured being covered (measuring method according to Viktorin, switching off of measurement errors in heterophorias, described in "The Phories, their Examination and Correction" by Th. Glaser, VEB Verlag Technik, Berlin, page 212). When the eye position to be measured is reached, means The rotary knobs align the projection of the light marks onto the pupils. The interpupillary distance can now can be read individually or as a whole on the scales (8, 9).

For this purpose 2 sheets of drawings

Claims (2)

Patent claims: 1. Device for measuring the interpupillary distance, with two devices that can be moved parallel to each other ί gen for the projection of light marks onto the cornea of a patient and with a scale (9) for Display of the interpupillary distance, characterized in that one on a selectable Working distance adjustable nose pad (2) is provided that each of the projection facilities a light mark can be moved by a rotary knob (7) and each with a further scale (8) interacts to display the interpupillary distance. 2. Device according to claim 1, characterized in that a near fixation point (10) on the device is appropriate.