KR20020085983A - chart projector for the examination of eyes - Google Patents

Abstract

PURPOSE: A chart projector for the examination of eyes is provided to increase size of usable chart window by imaging image of lamp filament incident from a condenser lens on a screen. CONSTITUTION: A lamp(10) is a source of light. A reflector(20) reflects the light to the back of the lamp(10). A condenser lens(30) refracts the reflected light. A mask board(40) has a through-hole so as to partially pass the light refracted through the condenser lens(30). A chart board(50) is provided to the same axis with the mask board(40), has a window on which a kinds of chart is etched, and moves the window to a position corresponding to the through-hole of the mask board(40). An incident lens(60) is provided on the front of the optotype chart board(50) and magnifies an image etched on the window to project the image on a screen.

Description

Sight Table Projector {chart projector for the examination of eyes}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projector for projecting an eye table, and more particularly, to an apparatus for projecting an eye table on a screen for visual inspection.

In general, a device for checking vision is to install a black printed sheet on a white acrylic plate facing the subject, and to install a light source on the back side of the target to irradiate a letter or a sign of the target by the light of the light source. It is designed to read a character or sign at a certain distance away.

However, such a visual inspection apparatus has difficulty in accurate measurement because the wavelength of light emitted from the light source affects the subject, and it is also bulky and should be used by being fixed to the wall. Since the test was to be 5m away, the space availability decreased and there was an inconvenience in the test. Sight table projectors are used as a way to solve this problem.

The sight table projector includes a mask board including a lamp as a light source and a condenser lens positioned in front of the lamp to deflect and project the light of the lamp, and a pass hole installed to be rotated in front of the condenser lens to pass only a part of the light. And a target chart board which is coupled to the mask board on the same axis as the pivot board, and has a surface on which a plurality of targets are printed, and a target projected by a lamp located in front of the target chart board. The projection lens is formed of a screen and the image is located in front of the projection lens and the screen passing through the projection lens appears, a plurality of targets provided on the target chart board by rotating the mask board 40 and the target chart board is printed. The required mark is placed on the screen by placing the glass on which the required mark is printed, corresponding to the passage hole on the mask board. Can tanael.

Of course, the sight table projector is provided with a driving body for rotating the sight chart board and the mask board, and the driving body has a circuit configured to be driven by a remote control.

The principle of the visual acuity projector is as follows.

FIG. 1 is a diagram illustrating the principle of an eye sight projector, and adopts a Kohler illumination method to display an image by the condenser lens 30 of the lamp filament 11 as a principal plane of the projection lens 60 ( 61). This arrangement prevents the image by the condenser lens 30 of the filament 11 from appearing on the screen, thereby preventing the image of the target projected on the screen from being disturbed by the filament image 70.

However, this approach creates a problem in that the size of the window 52 on the available chart board is limited. FIG. 1A shows the size area of the chart window 52 which is available, wherein the window 52 on which the size-limited sheet is printed is difficult to print or etch. In this case, a high magnification projection lens is used according to the use of a small target, so that it is difficult to project a clear target onto the screen. In addition, the letters and symbols used in conventional timetables are composed of the English alphabet, there is a problem that can not be used for the elderly and children who do not know English.

Accordingly, the technical problem to be achieved by the present invention is to provide a projector for increasing the size of the window on which the target is printed or etched so as to solve the above-mentioned problems, and for projecting a sight table in which the characters of the target are displayed in Korean. have.

1 is a schematic diagram showing an illumination optical system of a conventional optometry projector;

2 is a schematic view showing an illumination optical system of the present invention;

3 is a view showing a target of the present invention,

4A is a schematic cross-sectional view of an eye sight projector of the present invention;

Figure 4b is a plan view of the target chart board of the present invention.

* Description of the major symbols in the drawings

10: lamp, 52: chart glass,

11: filament, 53: target,

20: reflector, 60: projection lens,

30: condenser lens, 61: first main surface,

40: mask board, 62: second main surface,

50: target chart board, 70: filament phase,

51: joining hole, A: size area of chart glass available

The above-mentioned technical problem is that a vision table projector including a lamp, a reflector reflecting light of a lamp, a condenser lens, a chart board equipped with an eye sight measurement indicator, a mask board, and a projection lens, wherein the image of the lamp filament is different from the projection lens. It is arranged on the screen side outside of the main surface of the to enlarge the available area of the chart (window), it can be achieved by writing the characters of the chart in Korean and Arabic numerals.

Hereinafter, described in detail with reference to an embodiment of the present invention.

2 is a view showing an illumination optical system according to the present invention, Figure 3 is a view showing an example of a target according to the present invention, Figure 4a is a schematic cross-sectional view of the sight table projector according to the present invention, Figure 4b A plan view of a target chart board according to the invention.

As shown in FIG. 4A, the present invention includes a lamp 10 that is a light source, a reflector 20 that reflects light from the back of the lamp 10, a condenser lens 30 that refracts the reflected light, and a condenser lens. The mask board 40 is provided with a passage hole so as to pass only a part of the light refracted through the 30, and is rotated provided on the same axis as the mask board, and various kinds of targets are etched on the surface thereof. a window (52) is provided to move the glass 52 to a position corresponding to the passage hole of the mask board by rotation, and the glass 52 is provided in front of the target chart board (50) And an projection lens 60 for magnifying and projecting the image etched on the screen.

Of course, the sight table projector of the present invention is fixed to each of the components, is provided with a case 80 for protecting the components by blocking the components and the outside, for the rotation of the mask board 40 and the target chart board 50 A motor (not shown) is provided, and the motor is provided with a circuit to be driven by a remote control.

As shown in FIG. 4B, the chart chart board is a disk having a coupling hole 51 coupled to its axis in the center thereof, and the chart glass 52 whose target is etched around the coupling hole 51 in the border of the disk is formed. Since it is combined, it is possible to select and project the chart glass 52 whose suitable target is etched by the rotation of the chart board. In addition, the target may be composed of Korean characters and Arabic numerals, and may be composed of only Korean characters, consonants, or vowels without a backing for uniform readability. The Hangul characters may be composed of a combination of all the consonants and vowels 'ㅏ' and 'TT' so that the readability is almost uniform.

In addition, Arabic numerals may be arranged in an arrangement except 1,7 for easy identification and homogeneity of readability.

Features of the present invention will be described with the illumination optical system shown in FIG.

A characteristic of the present invention is to widen the available size area A of the chart glass through which the chart glass 52 can be seen, and to make the refractive angle of the condenser lens 30 small, so that the size area A of the chart glass can be used. ) So that the filament image of the lamp is placed on the screen side rather than the main surface of the projection lens. Of course, it is also possible to project the image of the filament on the projection lens main surface by moving the projection lens 60 toward the screen, in this case, the problem that the size of the projector is increased, the effectiveness is reduced.

The present invention makes the size of the chart glass available (A) large, thereby making the size of the chart glass large to facilitate etching or printing of the target, and as the size of the target grows, the projection lens screen of low magnification is increased. It has the effect of projecting a clear image.

In addition, the characters of the timetable consists of Hangul and Arabic numerals can be easily used by the elderly or children.

Claims (5)

A sight table projector consisting of a lamp 10, a reflector 20, a condenser lens 30, a chart board 50 in which a target glass is etched, and a projection lens 60 for projecting the target at a specific position. In this case, the image of the lamp filament 11 projected on the condenser lens 30 is formed on the screen rather than the main surface 61 of the projection lens 60 so that the size area A of the available chart glass 52 is made larger. Sight table projector, characterized in that formed. The method of claim 1, Sight table projector, characterized in that the timetable on the chart comprises a Hangul and Arabic numerals. The method according to claim 1 or 2, Sight table projector, characterized in that the Hangul schedule consists of Hangul characters without support. The method according to claim 1 or 2, Sight table projector characterized in that the Hangul characters of the Korean timetable consists of all the consonants and vowels 'ㅏ', 'TT'. The method according to claim 1 or 2, An eye sight projector according to claim 1, wherein the Arabic numeral indicators are arranged in an array except 1,7.