JPS60190831A - Lens meter - Google Patents

Abstract

PURPOSE:To make it possible to measure each refracting power of a lens to be examined without providing a movable part, by providing an objective lens, which projects the images of specified charts on the lens to be examined, and providing the charts, which are arranged at the position of the front focal point of the objective lens. CONSTITUTION:A lens meter has an objective lens 2, which projects the images of specified charts on a lens to be examined 1. The charts 3, 4 and 5 are arranged on optical axes 01, 02 and 03 of the objective lens 2. A one-dimensional- position detecting element 12 is provided at the conjugate positions of the charts 3, 4 and 5. Therefore, the images formed by opening parts 10a and 10b, 10c and 10d, and 10e and 10f are formed on the same positions, respectively. The refracting power in the direction of the opening parts 10a and 10b is obtained by the distance of the images formed by the respective opening parts 10a and 10b. Thus each refracting power of the lens to be examined can be measured without providing a movable part.

Description

Detailed Description of the Invention The present invention is a lens that measures the refractive power of a test lens such as a spectacle lens or a contact lens, and calculates the spherical refractive power, astigmatic refractive power, astigmatic axis, and prismatic refractive power of the test lens. It is related to meters.

Conventionally, lensmeters that measure the refractive power of the lens being tested are
- A predetermined chart called a corona target or cross line target was projected onto the lens to be tested, the image was observed, and the refractive power was measured based on the position where the image was most clearly formed. Recently, automatic lens meters have been put into practical use that automatically measure spherical refractive power, astigmatic refractive power, and astigmatic axis. The structure is quite complex and expensive, as it involves rotating a disk with a special shape at the aperture position.

The object of the present invention is to provide a lens that is capable of measuring each refractive power and astigmatism axis of a lens to be tested without having any moving parts, and that can widen the measurement range of prism refractive power by changing the shape of the chart. The purpose of the meter is to provide an objective lens for projecting a predetermined chart onto the eye lens to be examined, a chart corresponding to at least three meridian directions arranged at the front focal position of the objective lens, and a meter for each chart. a diaphragm having at least two openings in a direction perpendicular to the meridian, means for selecting a predetermined meridian direction portion of the chart, and a one-dimensional position detection element for detecting a chart image position; One meridian direction is characterized by having a plurality of parallel slits.

The present invention will be explained in detail based on illustrated embodiments.

FIG. 1 shows an embodiment of the present invention, in which the light beams intersect with each other at least at 120' at the front focal position of the objective lens 2 which makes the light beam incident on the test lens l to be measured, and at a position equivalent thereto. Charts 3.4.5 each having slits as shown in FIGS. 2(a), (b), and (C) are arranged in three meridian directions. Specifically, two semi-transparent mirrors 6°7 are diagonally installed as optical path splitting members on the optical axis 01 of the objective lens 2, and the light beam is divided into optical paths having optical axes 02 and 03 perpendicular to the optical axis 01, respectively. A chart 3.4.5 is arranged on each optical axis 01.02.03.

Also, regarding these three optical axes 01.02.03,
In order to illuminate each chart 3.4.5, light sources 8a to 8f, such as infrared light emitting diodes, are installed in pairs, and in front of each of these light sources 8a to 8f, a condenser is installed for each light source. Lenses 9a to 9f are arranged correspondingly. Further, behind the lens 1 to be tested on the optical axis 01''2, there is a ridge 10 having six openings 10a to 10f arranged at regular intervals on the same circumference as shown in FIG. A projection lens 11 and a -dimensional position detection element 12 are sequentially arranged. Here, the aperture 10 and the light source 8a~
8f is located at a substantially conjugate position, and each opening 10a of the diaphragm 10
~10f correspond to the light sources 8a~8f conjugately, respectively.

As mentioned above, FIGS. 2(a), 2(b), and 2(c) each show the shape of chart 3.4.5, and correspond to the meridian in the direction perpendicular to the -dimensional position detection element 12. Chart 3 consists of only a single slit S3, while the other chart 4.5 consists of a plurality of parallel slits. That is, the chart 4 has short sleeves (R4, T4) parallel to both sides of the long sleeve (S4), and the chart 5 has short sleeves (R5, T5) parallel to both sides of the long sleeve (S5). It is set in. In addition, these auxiliary sleeves) R4, T4, R5,
The width of T5 is narrow, unlike the slits S4 and S5.

In FIG. 1, the light emitted from each light source 8a to 8f is condensed by each condenser lens 9a to 9f, and is focused at the front focal position of the objective lens 2 and at a position 1
Char placed δ in 11), 3, 4, and 5 respectively! send, clarify. The light that has passed through each chart 3.4.5 is combined by a semi-transparent mirror 6.7, turned into parallel light by the objective lens 2, and enters the lens 1 to be tested. The light that has passed through the test lens is refracted by the projection lens 11 with its aperture limited by the aperture [O] located at the conjugate position of the light sources 8a to 8f, and is then refracted by the projection lens 11, and a chart image is transmitted to the -dimensional position detection element 12H. to project.

As mentioned above, since the aperture 1o and the wide tips f8a to 8f are arranged at substantially conjugate positions, each light source 8a to 8f is located at the aperture 10.
An image is formed in the apertures 10a to 10f of the light source, and the light emitted from one light source passes through only one part of the aperture corresponding to that light source. Therefore, light 71A8 a~
If 8f is sequentially turned on, the position of the chart image formed thereby, %9.1, can be detected from the output by scanning the -dimensional position detecting element 12 each time. That is, the chart 4.5 simultaneously detects the one-dimensional position detecting element 1.
It will no longer be projected onto 2. In other words, a predetermined radial direction portion of the chart is selected.

FIG. 4 shows all the cases where the lens 1 to be tested is an O diopter or the lens 1 to be tested is not inserted. Note that the slit images Sa and Sb are images formed by the openings 10a and 10b of the slits3, and Sc and Sd are the images formed by the openings 10a and 10b of the slits3.
, 1-34 opening 10c, image by lod, Se,
Sf is the image of the slit 1-34 at the open 1'' portions 10e and 10f, Rc and Rd are the images of the slit R5(7) at the open 1'' portion 10c
, image by lod, Re, Rf is thrill 1-R$
The image by the opening 1'' portion 10e, lof, Tc, Td is the image by the opening 10c, 10d of the slit T5, Te,
Tf is an image formed by the openings foe and lOf of the slit T4.

Here, the -dimensional position detection element 12 is as shown in chart 3.4.5.
Since it is in the conjugate position j〆1, the opening 10a and lOb,1
Images formed by lod such as 0c and 10f such as 10e are formed at the same position. Open section 10a, lo
The refractive power D1 in the b-i direction is determined by the respective opening 1'' portions 10a,
], the distance of the image formed by Ob, that is, the distance between both slit images? It can be determined by the difference in rq coordinates. Also,
Since the refractive powers D2.03 in the directions of the open portions 10c and 10d and the directions 10e and 10f can be set in the same way, the refractive powers D1 to D3 in these three meridian directions 01 to θ2
The following formula, Dn=A 5in2 ((7n+ψ) 1 B (where n=1
．． By substituting into 2.3) and finding A, B, and ψ, the spherical refractive power, astigmatic refractive power, and astigmatic axis can be calculated.

On the other hand, the prism 1 has a refractive power of apertures 10a and 10b, lo
It can be determined from the midpoint of the images formed by c and 10d, foe and lof.

FIG. 5 shows the relationship between the chart image and the -dimensional position detecting element 12 when the lens 1 to be tested has a considerably large prism refractive power. The images Sa, Sb, and R
c, Rd, images Re, Rf, and images Sc”S
f is not crossed. Therefore, as mentioned above, the slit S
If the widths of the slits S5 and R4 and T4 and the slits S5 and R5 and T5 are made different, the -dimensional position detection element 12
It is possible to distinguish between these images above. Fifth
In the case of the figure, the refractive power of the subject 1/lens 1 is only the prism refractive power, but the spherical and astigmatic refractive powers are added to this (≠)
, if we consider the position of the midpoint of the image in one meridian direction as mentioned above, these can be similarly set.6 Next, Figure 6 shows another embodiment, in which liquid crystal is used for the chart and the aperture. 1, and members such as circuits and circuits are indicated by the same reference numerals as in FIG. In this case, only one light source 8 is required, the chart 1 is formed by the liquid crystal chart 13, and the opening of the diaphragm behind the test lens 1 is also formed by the liquid crystal shutter 1.
It is formed by 4. Note that a pinhole plate 15 is arranged in front of the light source 8.

FIG. 7 shows the liquid crystal charts 1 and 13, which include a large number of elements E1 to E17.
By opening appropriate elements according to the direction of A11 + constant meridian and closing the remaining elements, a chart similar to that shown in FIG. 2 can be created.

As for the liquid crystal shutter 14, as shown in FIG.
6 open lower elements arranged as shown in the figure;・1.4
a to 14f, and the opening elements in the direction perpendicular to the meridian opened at 13 are sequentially opened and the light is projected onto the one-dimensional position detection element 121-, in the same manner as in the previous embodiment. Measurement is possible. This embodiment has the advantage that the number of constituent members can be drastically reduced compared to the previous embodiment.

As described above, the lens meter according to the present invention has no moving parts, has a simplified structure, is small and can be manufactured at a low cost, and is not only capable of measuring each refractive power and astigmatic axis, but also has an auxiliary function in the measurement meridian direction. By using a chart provided with a slit, the effect of expanding the measurement range of prism refractive power is remarkable.

[Brief explanation of the drawing]

The drawings show an embodiment of the lens meter according to the present invention, and FIG. 1 is an optical layout diagram of the first embodiment, and FIG.
a), (b), and (c) are front views of the chart, Figure 3 is a front view of the diaphragm, Figures 4 and 5 are relationship diagrams between the Char I image and the one-dimensional position detection element, and Figure 6 The figure is an optical layout diagram of the second embodiment, FIG. 7 is a front view of a liquid crystal chart, and FIG. 8 is a front view of a liquid crystal shutter. Reference numeral 1 is the test lens, 2 is the objective lens, 3.4.5 is the chart, 6.7 is the hemi-lingual mirror, 8.8a to 8f is the light source, 9a
~9 f If condenser lens, 10 is aperture, loa
10f is an aperture, 11 is a projection lens, 12 is a one-dimensional position detection element, 13 is a liquid crystal chart, 14 is a liquid crystal shutter, and 14a to 14f are aperture elements. Patent applicant: Canon Co., Ltd. Figure 2 (G) (b) (C) Figure 3. figure

Claims (1)

[Claims] 1. An objective lens for projecting a predetermined chart I onto the eye lens to be examined; a chart corresponding to at least three meridian directions disposed at the front focal position of the objective lens; an aperture having at least two openings in perpendicular directions; and means for selecting a predetermined meridian direction portion of the chart;
1. A lens meter comprising: a one-dimensional position one-image detection element for detecting a chart image position, and having a plurality of slits parallel to each other in at least one meridian direction of the chart. 2. The lens meter according to claim 1, wherein the chart is formed of three parallel slits in meridians other than the direction perpendicular to the one-dimensional position detection element. 3. The lens meter according to claim 2, wherein at least one of the three slits has a different width. 4. The lens meter according to claim 1, wherein the meridians are three meridians intersecting each other at 120 degrees. 5. The char I consists of three pieces, and the optical path splitter7. H
6. The lens meter according to claim 1, wherein each chart light source is arranged in an optical path divided into three by the optical path to identify and project the chart. 6. The optical path division The lens meter according to claim 5, in which the member is a semi-transparent mirror. 7. The light source and the aperture are in conjugate positions, and the lens meter has six light sources corresponding to the aperture of the aperture. 8. The lens meter according to claim 1, wherein the chart and the aperture are constituted by a liquid crystal chart 1 and a liquid crystal shutter each having a structure of opening a slit aperture opening corresponding to a specific meridian. 8. The lens meter according to claim 8, wherein the liquid crystal chart I divides the liquid crystal into a plurality of elements to form slits corresponding to three meridians.