DE102004032819A1 - Eye testing system, has micro-retarder placed in front of monitor screen, with image covering regions having different phase-shift states - Google Patents

Abstract

The system includes a TFT monitor with individually-controllable image producing regions (7). A micro-retarder (5) is placed in front of the screen, and comprises alternately light-permeable image covering regions (11,12) with different phase shift states. Image covering regions (12) of the first state in which polarized light passes from the screen through the micro-retarder unaltered, are associated with a first group of image producing regions (7). Image covering regions (11) of the second phase-shift state, in which the polarization axis of the polarized light from the screen is rotated by 90 degrees by the micro-retarder, are associated with a second group of image producing regions (7).

Description

The The invention relates to a vision inspection system for testing monocular and binocular vision of a Subjects with an imaging device and polarized glasses in front of the subject.

It are visual inspection systems known to work on the projector principle. Here are Chart symbols and symbols projected on a metal screen. With help an input unit the illustrated optotypes and symbols are exchanged. adversely Here is the limited choice at test facilities, because the discs can not be exchanged without enormous effort.

Furthermore, a visual inspection system for studying stereoscopic vision ( EP 0 595 023 B1 ) using an image forming apparatus which emits polarized light and in front of which a vector graphene film whose polarizing elements are arranged in a pattern corresponding to the emitted image pattern is used. The polarization axes of adjacent polarization elements of the vector graphene film are perpendicular to each other. The vision test system also has a connected computer with input unit. In this system, it is disadvantageous that the production and orientation of the vector graphene film is very complicated. In addition, the resulting polarization directions of 0 ° and 90 ° are unusual for ophthalmic optics and ophthalmology; The polarization directions of 45 ° and 135 ° are preferred.

It Accordingly, it is the object to provide a visual inspection system that the avoids the disadvantages mentioned with which a large variety of visual and test marks can be represented and with those used in the investigation Polarization directions favorable are arranged.

• – einen linear polarisiertes Licht ausstrahlenden Bildschirm mit rasterartig aufgeteilten und individuell ansteuerbaren Bilderzeugungsbereichen,
• – einen vor dem Bildschirm angebrachten Mikro-Retarder mit alternierend angeordneten, lichtdurchlässigen Bildabdeckungsbereichen, die mit Bilderzeugungsbereichen des Bildschirms deckungsgleich sind und Bildabdeckungsbereiche mit zwei unterschiedlichen Phasenverschiebungszuständen aufweisen,
• – wobei Bildabdeckungsbereiche des ersten optischen Phasenverschiebungszustandes, bei dem das polarisierte Licht des Bildschirms den Mikroretarder ungeändert passiert, einer ersten Gruppe von Bilderzeugungsbereichen zugeordnet sind,
• – und Bildabdeckungsbereiche des zweiten optischen Phasenveschiebungszustandes, bei dem die Polarisati onsachse des polarisierten Lichtes des Bildschirms durch den Mikroretarder um 90° gedreht wird, einer zweiten Gruppe von Bilderzeugungsbereichen zugeordnet sind,
• – und mit einer rechnergesteuerten Eingabeeinheit zur Steuerung des Bildschirms.

This object is achieved in a visual inspection system for testing the eyesight of a subject, comprising:

• A linearly polarized light-emitting screen with raster-type and individually controllable image-forming areas,
• A micro-retarder, mounted in front of the screen, with alternately arranged translucent image coverage areas which are congruent with image forming areas of the screen and have image coverage areas with two different phase shift states;
• Wherein image coverage areas of the first optical phase-shift state in which the polarized light of the screen passes the micro-retarder unaltered are associated with a first group of imaging areas;
• And image coverage areas of the second optical phase shift state, in which the polarization axis of the polarized light of the screen is rotated through the micro-retarder by 90 °, associated with a second group of imaging areas,
• - And with a computer-controlled input unit for controlling the screen.

Under a light-emitting screen is preferably a so-called TFT monitor to understand. TFT is the abbreviation for Thin Film Transistor. such Monitors are also referred to as "Active Matrix Screens." she result in a flicker-free, sharp image with a wide viewing angle and fast image construction. The picture can also be colored. Usually own commercial Flat screens already have corresponding control circuits, so that a computer can be connected directly. Every pixel the picture line is assigned at least one controlling transistor.

A micro-retarder is understood to mean an optical element in which there is an arrangement with alternating different phase delay regions which act on the continuous polarized light. In this case, a strip-shaped structure with two alternating optical phase shift states is preferably selected. The orientation of the phase delay ranges can be either horizontal (in rows) or vertical (in columns). The first optical phase shift state does not change the properties of the translucent light, the second optical phase shift state changes the polarization axis of the light by 90 °. Realized is the production of such a micro-retarder, for example, with a after US Pat. No. 6,498,679 B1 known methods. This document also describes the basic physical properties of such micro-retarders.

A "proband" is in the following a viewer, observer, examinee, Subject or patient.

By means of the vision inspection system according to the invention, for example, the so-called "reversal sample", ie the interchange of the visual impressions of the right and left eyes, can be realized electronically by an interlaced scan by shifting the content of the screen by one line by operating the input unit without mechanically moving parts reali which makes it very robust, wear-free and prone to failure.

It allows a simple distance-dependent size variation of the illustrated Characters, where the characters have different shapes and colors can.

The vision testing under monocular or binocular conditions may also be without wearing polarizing glasses, but are preferred exams carried out, in which one of the subject's eye pair polarizing glasses is used with two polarizing filters whose polarization axes perpendicular to each other and with the polarization axes of match directionally from the screen and the micro-retarder emerging light.

following The invention and the principle of operation with reference to the drawing explained in more detail. there demonstrate:

1 an arrangement for explaining the principle of operation with a micro-retarder;

2 a visual inspection system, shown schematically.

The emergence of a stereoscopic visual impression, as required for the study of subjects, is based on the 1 explained.

A TFT monitor comprises - schematically - a light source 1 which emits unpolarized light, passing through a first polarizing film 2 the irradiated light is given a preferential polarization direction, which is indicated by the hatching. A transistor arrangement with liquid crystals in an LC matrix 3 (LC = liquid crystal = liquid crystal) has rows and columns 7 on, which can be referred to as raster arrangement. The desired characters are represented by pixels. Alternating are the rows of the LC matrix 3 exemplified with different symbols (au and AU).

In the LC matrix 3 is a second polarizing film 4 downstream of the first polarizing film 2 has a rotated by 90 ° polarization direction. The between the two polarizing films 4 and 2 located LC layer with individually controllable pixels, represented by pixels, rotate with appropriate control, the polarization direction by 90 °. Because the polarizing films 2 and 4 can have mutually perpendicular directions, only in the LC matrix 3 turned light the foil 4 happen. Contrasts of the image are created by rotating the light only at the desired image areas (pixels) in the LC layer.

That from the second polarization foil 4 Exiting linearly polarized light falls on a micro-retarder 5 with two optical phase shift states, the regions of the individual retardation states coinciding in size and orientation with the individual imaging regions, here lines.

Due to the structure of the micro-retarder 5 This is the result of the polarizing film 4 polarized light of lines AG, HN, OU unchanged by the micro-retarder at its lines 12 pass through. The polarized in the same direction light of the lines ag, hn, ou, however, when passing through the lines 11 turned by 90 degrees.

That from the micro-retarder 5 Exiting light now has alternating polarization directions that are perpendicular to each other. Will the picture through the eyes 14 . 15 a subject 16 observed in front of which polarized glasses 6 with two polarizing films 6a . 6b the subject sees with one eye either the lines AG, HN, OU or ag, hn, ou. The polarization axis of a polarizing film 6a stands perpendicular to the polarization axis of the second polarizing film 6b ,

Through the in 1 illustrated visual inspection system, it is possible that the image forming areas ag, hn, ou LC grid through the left filter disc 6a the polarization glasses 6 be imaged on the left eye of an observer, while the image forming areas AG, HN, OU of the grid through the right filter disc 6b the polarization goggles 6 be imaged on the right eye of the observer.

By appropriate control of the screen by the computer can also color vision, e.g. on suspicion of red-green blindness, to be checked.

In summary may characterize the operation of these arrangements be that a polarization direction constantly associated with an eye is and the other, perpendicular to the above polarization direction the other eye of the beholder when wearing polarized glasses whose Filter the same, perpendicular to each other polarization axes own, like the test system.

Based on the described principle is in 2 a Sehprüfgerät the invention 16 shown schematically. In the 1 illustrated elements light source 1 , Polarization filter 2 , LC matrix 3 , Polarizing film 4 as well as the driving circuit are through a TFT monitor 10 embodies. The micro-retarder 5 will appear on the display of the monitor 10 appropriate.

The control of the optotypes takes place via a computer 22 with attached memory containing the vision software, and an input unit 23 , At the calculator 22 it is a computer including non-volatile memory with appropriate software for displaying the images and optotypes, wherein the characters can have the desired shape and color.

Under an input unit 23 is understood a device or group of devices, with the ge wished action is triggered on the screen, connected to a corresponding receiving unit, such as. IR remote control, IR receiver, keyboard and the like.

Claims (5)

Vision test system for testing the eyesight of a subject, comprising: - a linearly polarized light emitting screen ( 10 ), preferably a TFT monitor, with raster-like and individually controllable image generation areas ( 7 ), - a micro-retarder mounted in front of the screen ( 5 ) with alternately arranged translucent image coverage areas (lines 11 . 12 ) associated with image-forming areas of the screen ( 10 ) are congruent and have two different phase shift states, wherein image coverage areas (lines 12 ) of the first optical phase-shift state, in which the polarized light of the screen passes the micro-retarder unaltered, to a first group of image-forming regions ( 7 ), and image coverage areas (lines 11 ) of the second optical phase-shift state, in which the polarization axis of the polarized light of the screen is rotated through the micro-retarder by 90 °, a second group of image-forming regions ( 7 ), and with a computer-controlled input unit for controlling the screen. Vision testing according to claim 1, characterized in that the grid-like arrangement the image-forming areas consist of rows and / or columns. Visual inspection system according to claim 1 or 2, characterized in that the image coverage areas ( 11 . 12 ) of the micro-retarder ( 5 ) are arranged alternately either in rows or columns. Visual inspection system according to claims 1 to 3, characterized in that a pair of polarization spectacles associated with the eye pair of the subject ( 6 . 14 ) with two polarizing filters ( 6a . 6b ) whose polarization axes are perpendicular to each other and coincide with the polarization axes of the emerging from the screen and the micro-retarder light directionally, is used. Vision testing according to claim 1 to 4, characterized in that the screen produces colored images.