WO2002054944A1 - Appareil de mesure du pouvoir visuel d'une personne aveugle - Google Patents

Appareil de mesure du pouvoir visuel d'une personne aveugle Download PDF

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Publication number
WO2002054944A1
WO2002054944A1 PCT/KR2001/000031 KR0100031W WO02054944A1 WO 2002054944 A1 WO2002054944 A1 WO 2002054944A1 KR 0100031 W KR0100031 W KR 0100031W WO 02054944 A1 WO02054944 A1 WO 02054944A1
Authority
WO
WIPO (PCT)
Prior art keywords
light
lens
measuring
tft lcd
visual power
Prior art date
Application number
PCT/KR2001/000031
Other languages
English (en)
Inventor
Sung-Wook Cho
Original Assignee
Hopia Co., Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hopia Co., Ltd filed Critical Hopia Co., Ltd
Priority to PCT/KR2001/000031 priority Critical patent/WO2002054944A1/fr
Publication of WO2002054944A1 publication Critical patent/WO2002054944A1/fr

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B3/00—Apparatus for testing the eyes; Instruments for examining the eyes
    • A61B3/10—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions
    • A61B3/12—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions for looking at the eye fundus, e.g. ophthalmoscopes

Definitions

  • the present invention concerns an apparatus for measuring the sight or visual power of a blind or visually handicapped person.
  • the type of the human eye varies according to the position of the retina (focal length) or the curvature of the lens.
  • a person usually called visually handicapped is not able to even distinguish brightness due to lost light sense and sight caused by various eye diseases, or otherwise can slightly distinguish brightness or feel motion of the hand immediately before the eye, whose visual problems can not be resolved by conventional eyeglasses or lenses .
  • a visual power generator disclosed in a patent application No. PCT/KR00/00056 filed in the name of the present invention.
  • the invention of this application is to enable a person visually handicapped due to optic nerve withering, defective or lost lens, cerebral infarction, encephaloma, nystagmus, retina detachment, etc. to see things. Namely, this enables the image to be focused on a relatively active region of the retina, imparts strong optical stimuli to the withered optic nerve, or adjusts the focus over a wide range, thereby providing the visually handicapped person with sight.
  • an apparatus for measuring the visual power of a blind or a visually handicapped person which comprises a main frame provided with a plurality of input terminals connected to external devices, a TFT LCD monitor installed in the main frame for displaying an image received from an external video device, a light source for illuminating the rear surface of the TFT LCD monitor so as to adjust the illumination of the image displayed on the TFT LCD, a filter for removing harmful light from the light of the light source illuminating the TFT LCD, an objective lens part installed in the main frame for transmitting the image displayed on the TFT LCD with prevention of losing light, an eyepiece installed so as to be tilted or slid in the main frame for magnifying the image transmitted by the objective lens part and adjusting the focal length and the light path, and a testing unit detachably attached to the objective lens part for detecting a recognizably effective region of the retina .
  • the inventive apparatus for measuring the visual power of a blind and a visually handicapped person further includes an external monitor connected to the main frame so as to externally display the image displayed on the TFT LCD.
  • the light source includes a reflector for reflecting the light from a halogen lamp arranged at its focus, a first non-spherical lens for collecting the light reflected from the reflector, and a second large-diameter lens for horizontally transmitting the light collected by the first lens.
  • the reflector is adjusted forward and backward and leftward and rightward, and its reflection surface is coated with dichromic acid to absorb most of infrared light.
  • At least one of the first and second lenses is preferably coated with a multi-layer filter formed of Ti0 2 , Ta0 2 and Si0 2 for reflecting infrared light but transmitting visible light.
  • the first lens may be displaced forward and backward and leftward and rightward so as to adjust the path of the light reflected from the reflector.
  • the filter is an infrared and ultraviolet light filter to remove harmful wavelengths from the light reflected from the reflector.
  • the objective lens part further comprises a plurality of large-diameter lenses to eliminate various aberrations together with harmful light.
  • the testing unit comprises a cylindrical casing mounted on the periphery of the eyepiece, lens housing provided in the rear of the casing, eye-like lens provided in the front of the lens housing, testing plate arranged behind the eye-like lens for taking the image displayed on the TFT LCD, objective lens for adjusting the light path of the image taken by the testing plate, and camera for taking the image to display on the external monitor.
  • the testing plate is made of a translucent circular plate provided with directional angles and coordinates of 360°.
  • Fig. 1 is a schematic side elevation of an apparatus for measuring the visual power of a blind or a visually handicapped person according to the present invention
  • Fig. 2 is a schematic diagram for illustrating the structure of an eyepiece used in the inventive apparatus for measuring the visual power of a blind or a visually handicapped person;
  • Figs. 3A and 3B are schematic diagrams for showing the light path with the eyepiece tilted
  • Fig. 4 is a diagram for illustrating the optical system of the inventive apparatus for measuring the visual power of a blind or a visually handicapped person
  • Fig. 5 is a diagram for illustrating the light path of the objective lens part consisting of a single lens in the optical system of Fig. 4;
  • Fig. 6 is a diagram for illustrating the light path of the objective lens part consisting of a plurality of lenses in the optical system of Fig. 4;
  • Figs. 7A to 7C are diagrams for illustrating the lens formulas used in the inventive apparatus for measuring the visual power of a blind or a visually handicapped person;
  • Fig. 8 is a schematic diagram for showing a retina testing unit installed against the eyepiece.
  • Fig. 9 is a schematic diagram for showing the testing plate used in the retina testing unit of Fig. Best Mode for Carrying Out the Invention
  • Fig. 1 illustrates the inventive apparatus for measuring the visual power of a visually handicapped person.
  • the inventive apparatus comprises a main frame 1 provided with a plurality of input terminals 2 connected to external monitoring devices 9a, 9b such as video tape recorder, computer monitor, television and camera.
  • the main frame 1 is moveable by a plurality of wheels provided at the bottom.
  • the main frame 1 has an X-Y stage 5 arranged below the front part, which is shaped in the form of a table to receive things.
  • the main frame 1 is also provided with an illumination adjustment knob 6 for adjusting the illumination of a light source 12 (refer to Fig. 4) such as halogen lamp installed therein.
  • a tilted part 3 provided with an eyepiece 7, against which is put the eye of a visually handicapped person, and which is slidably mounted in the main frame 1 and may be tilted by moving a tilting handle 8 upward and downward and leftward and rightward, as shown in Figs. 3A and 3B.
  • the eyepiece 7 has a surface provided with a scale 10 to indicate its relative position to the main frame 1 when sliding thereto.
  • the upward and downward and leftward and rightward tilting of the eyepiece 7 enables the visual power generator to be adjusted so as to form the image on the most effective region of the retina of the visually handicapped person, while the sliding movement enables the focus to be adjusted according to the degree of the myopia or hyperopia.
  • Fig. 4 illustrates a display, and an optical system for magnifying the image displayed thereon, which are arranged in the main frame 1 including the objective lens part 7.
  • a TFT LCD monitor 11 is installed in the main frame 1, displaying the images received from the external devices 9a, 9b such as video tape recorder, computer monitor, television and camera.
  • the TFT LCD monitor 11 may express the colors and brightness of high resolution with the scanning lines of high density, being compatible with various video and computer signals.
  • the TFT LCD monitor 11 also provides a testing unit 20 hereinafter described with an image required for detecting the recognizably effective region of the retina of the visually handicapped person.
  • the image displayed on the TFT LCD monitor 11 can be transmitted to him by illuminating its rear surface with a light generated from a light source 12 arranged behind the TFT LCD monitor 11.
  • the illumination of the light source 12 can be properly adjusted by the illumination adjustment knob 6 provided in the main frame 1, so as to adjust the illumination of the image displayed on the TFT LCD monitor 11 for him to see it according to the defective state of the eye.
  • the light source 12 emits light of more than 600W, from which are eliminated infrared and ultraviolet rays harmful to the human body in the manner hereinafter described.
  • the light source 12 is disposed at the focus of a reflector 13.
  • the light source 12 may consist of a halogen lamp with wavelengths similar to natural light that is designed so as to be displaced forward and backward and leftward and rightward.
  • the light source 12 may have short wavelengths as is the case.
  • the reflector 13 may be adjusted forward and backward and leftward and rightward, and has an internal surface facing the light source 12 that is coated with dichromic acid to absorb about 80% of the infrared rays generated from the light source 12 but to reflect all the visible light.
  • the focal length of the reflector 13 is preferably R/2, at which is disposed the light source 12, wherein R represents the radius of the reflector 13.
  • the light reflected from the reflector 13, as shown in Fig. 4, is collected by first non-spherical lens 14, transferred to second lens 15.
  • the first lens 14 is coated with a multi-layer filter consisting of Ti0 , Ta0 2 and Si0 2 to protect the eye, adjusted forward and backward and leftward and rightward to adapt the light path for the light generated from the reflector 13.
  • the second lens 15 has a large diameter to horizontally transmit the light from the first lens 14 to a filter 16, coated with an infrared ray blocking film to reflect all the light other than the visible light.
  • the first and second lenses 14 and 15 are made of a heat resistant glass according to the present invention.
  • the filter 16 is to eliminate harmful light such as ultraviolet and infrared rays from the light generated from the light source 12 to illuminate the rear surface of the TFT LCD monitor 11.
  • the filter 16 is a kind of infrared and ultraviolet filter consisting of a plurality of layers to filter the harmful wavelengths from the light reflected from the reflector 13 in order to protect the eye of a visually handicapped person using the inventive apparatus.
  • the light transmitted through the filter 16 to the rear surface of the TFT LCD monitor 11 may be adjusted by the illumination adjustment knob 6 to be adapted to the eye.
  • the image with the illumination adjusted as described above is transmitted through an objective lens group 17 arranged in front of the TFT LCD monitor 11 to the eye without loss of the light.
  • the objective lens group 17, as shown in Fig. 4, consists of four large-diameter lenses 17a, 17b, 17c and 17d.
  • the reason that the objective lens group 17 consists of large-diameter lenses is to horizontally guide the light rays horizontally transferred from the light source 12 through the TFT LCD monitor 11 without loss, and thus the image displayed on the TFT LCD monitor 11,
  • the reason that the objective lens group 17 consists of four lenses is to eliminate various aberrations.
  • the objective lens group 17 may be suitably coated to eliminate infrared and ultraviolet rays.
  • Fig. 5 illustrates the determination of the focusing reference line H of the objective lens group 17 consisting of a single lens with respect to the TFT LCD monitor 11.
  • the light ray L 1 incident on the lens 17' is converged through the incident and emitting points Q 1 and O 1 at the focus F, and the light ray L 2 through the incident and emitting points Q 2 and O 2 at the focus F.
  • Fig. 6 illustrates the focusing reference line H of the objective lens part consisting of a plurality of lenses.
  • the focusing reference line is assumed as the reference line for calculating the combined focal length F of the lens group 17, which is calculated by the following formula:
  • f each focal length
  • D the distance between adjacent lenses, and in this case, if D is small, the third term of the left expression of the equal sign may be ignored. If the number of the lenses is N, the focal length is obtained by the following formula:
  • the magnification becomes 0.364, which may be interpreted as the size of the image formed at the position b' in Fig. 5 when the size of the image displayed on the TFT LCD monitor 11 is assumed as 1.
  • the eyepiece 7 is provided with an eyepiece lens group 18 as shown in Fig. 4, which corresponds to the eyepiece of a microscope or telescope, and has a large diameter than the ordinary eyepiece in order to reduce the loss of the light and to provide convenience to the visually handicapped person according to the present invention.
  • the first lens 18a of the eyepiece lens group 18 is coated with a film for eliminating harmful light rays to protect the eye of the user.
  • the focal length of the eyepiece lens group 18 is designed to be 50mm to give 6 times magnification.
  • the overall magnification of the inventive apparatus for measuring the visual power of the visually handicapped person is about 2.184.
  • the focal length ef of the human eye is calculated, and the retina distance b between the lens and retina with respect to the focusing reference line H.
  • the biological effect such as the lens control is excluded from the calculation.
  • the focal length of the eye is about 19.001mm, and the retina distance b about 20.564mm.
  • the conventional theory of virtual image may be used to calculate the distance between the lens 51 and a thing, and thus the magnification, as follows:
  • a represents the distance between the object and the center of the lens 51
  • b the clear vision range between the lens 51 and the virtual image
  • f the focal length of the lens 51
  • m the magnification of the lens 51.
  • the maximum clear vision range becomes 2499.95m for the distance between the lens and object of 49.999mm.
  • the combined focal length using a lens with a focal length of 50mm is obtained the combined focal length using a lens with a focal length of 50mm.
  • the object to be seen must be at 212.555mm before the lens.
  • the distance between the lens and object greatly exceeds 50mm, which is the case for most of the handicapped persons and for person of serious myopia.
  • the value of b is 20.564. This means that one cannot clear see a distant image if the combined focal length of the eye with a focal length ef of 19.001 and the mechanical lens exceeds 20.564mm. Considering this, the adjustment range of the focal length of the apparatus is increased.
  • the magnification of the inventive apparatus is calculated as 2.184 by applying the formulas described above .
  • Fig. 8 illustrates the retina testing unit mounted against the eyepiece.
  • the retina testing unit 20 comprises a cylindrical casing 21 mounted on the periphery of the eyepiece 7, and lens housing 22 arranged at the rear part of the casing 21. Mounted on the front of the lens housing 22 is a lens 23 corresponding to the eye lens of a testee, after which is arranged a testing plate 19 corresponding to the retina of the testee.
  • the testing plate 19, as shown in Fig. 9, is a circular plate made of a translucent material provided with directional angles and coordinates of 360°, which takes the image displayed on the TFT LCD monitor 11.
  • the image pictured on the testing plate 19 is transferred through the objective lenses 24 arranged behind it to a camera 25 arranged at the rear end of the lens housing 22, displayed on an external computer monitor.
  • the image pictured on the testing plate 19 is also detected of the illumination together with the coordinates and angles.
  • the distance between the testing plate 19 and the objective lens 24 corresponds to the value a of the lens formula, and the distance between the objective lens 24 and the camera 25 to the value b.
  • the retina testing unit 20 is used to locate the portion of the retina on which the image can be best pictured after the eye is tested through the eyepiece 7 for the user to be sure which portion of the retina can best take the image displayed on the TFT LCD monitor 11.
  • the portion of the testing plate 19 taking the image corresponds to the user's retina
  • the light path of the visual power generator filed by the present inventor is adjusted by the inventive measuring apparatus so as to correctly transmit the image displayed on the TFT LCD monitor 11 to the portion of the retina that has been confirmed to best take it, thus enabling the visually handicapped person to effectively see.
  • the inventive apparatus for measuring the visual power can locate a portion of the retina of the visually handicapped person having vital cells, and readily determine the illumination enough for the person to see the object and the focus for the object, so that the visual power generator can be specifically adjusted for the person to clearly see the object.
  • the inventive measuring apparatus may be used as an audio-visual education instrument for a visually handicapped person by means of the image displayed on the TFT LCD monitor in addition to the function of measuring the visual power of the person.

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  • Life Sciences & Earth Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Medical Informatics (AREA)
  • Biophysics (AREA)
  • Ophthalmology & Optometry (AREA)
  • Engineering & Computer Science (AREA)
  • Biomedical Technology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Physics & Mathematics (AREA)
  • Molecular Biology (AREA)
  • Surgery (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Eye Examination Apparatus (AREA)

Abstract

L'invention concerne un appareil de mesure du pouvoir visuel latent des personnes handicapées visuelles, qui permet de localiser la région récupérable de la rétine et de déterminer la quantité d'illumination nécessaire pour leur faciliter la vision ainsi que la longueur focale qui leur est adaptée pour utiliser le générateur de pouvoir visuel. Cet appareil comprend une structure principale pourvue d'un ensemble de plusieurs terminaux reliés à des dispositifs externes, un écran LCD à matrice active fixé sur la structure principale pour afficher l'image reçue d'un dispositif vidéo externe, une source lumineuse pour éclairer la surface arrière du moniteur et régler l'illumination de l'image affichée sur ledit écran LCD à matrice active, un filtre pour éliminer les rayons dangereux de la lumière provenant de la source lumineuse éclairant l'écran LCD à matrice active, et enfin un objectif monté dans la structure principale pour transmettre l'image affichée sur l'écran LCD à matrice active.
PCT/KR2001/000031 2001-01-10 2001-01-10 Appareil de mesure du pouvoir visuel d'une personne aveugle WO2002054944A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/KR2001/000031 WO2002054944A1 (fr) 2001-01-10 2001-01-10 Appareil de mesure du pouvoir visuel d'une personne aveugle

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/KR2001/000031 WO2002054944A1 (fr) 2001-01-10 2001-01-10 Appareil de mesure du pouvoir visuel d'une personne aveugle

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010517653A (ja) * 2007-02-07 2010-05-27 ウニベルシダッド・コンプルテンセ・デ・マドリッド 短波長の放出が減少された眼を保護するための光源

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5975698A (en) * 1997-10-09 1999-11-02 Kabushiki Kaisha Topcon Ophthalmic instrument
US6050687A (en) * 1999-06-11 2000-04-18 20/10 Perfect Vision Optische Geraete Gmbh Method and apparatus for measurement of the refractive properties of the human eye

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5975698A (en) * 1997-10-09 1999-11-02 Kabushiki Kaisha Topcon Ophthalmic instrument
US6050687A (en) * 1999-06-11 2000-04-18 20/10 Perfect Vision Optische Geraete Gmbh Method and apparatus for measurement of the refractive properties of the human eye

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010517653A (ja) * 2007-02-07 2010-05-27 ウニベルシダッド・コンプルテンセ・デ・マドリッド 短波長の放出が減少された眼を保護するための光源

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