JPS6346130A - Objective eye refractive power measuring apparatus - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to an objective eye refractive power measuring device, and in particular an objective eye refractive power measuring device that is easy to manufacture and that can accurately and easily measure the refractive power of the eye. This invention relates to a type eye refractive power measuring device.

(Prior art and its problems) Usually, objective eye refractive power measurement is performed by determining the principal meridian direction of astigmatism (cylinder axis angle): θ, spherical refraction Kani S, and cylindrical refraction Kani C in the eye to be examined. and the practical method of making such measurements is generally
Three types of measurement methods have been used in the past: the matching method, the imaging method, and the area method.

By the way, the above-mentioned area method, which is a type of eye refractive power measurement method, sends a slit-shaped light beam into the pupil of the eye being examined, and when the light beam moves, the movement of the reflected light from the fundus of the eye within the pupil is observed. However, the refractive power is basically measured by finding a neutral state in which no movement is observed in the light shape within the pupil.

Using this type of area method as the basic principle, we aim to simplify the structure, improve measurement accuracy, and facilitate operation.
Various improvements have been made in the past. For example, in Japanese Patent Application Laid-Open No. 55-160538, instead of simply finding the neutralization point using the area method, the speed and direction of the movement of the light shape in the pupil are From these measured values, the refractive power of the eye to be examined, (spherical refractive power (S) and cylindrical refractive power (C)
)) is disclosed.

However, in such an eye refractive power measuring device, unlike the previous measuring device using the area method, there is a rotational drive mechanism for the entire device to measure the astigmatic axis direction of the eye to be examined, or a rotational drive mechanism for the entire device to measure the astigmatic axis direction of the eye to be examined, or Although a high-precision servo mechanism is not required to accurately match the direction, the principal meridian direction of astigmatism (θ)
In order to detect this, an image rotating prism that rotates the light beam is required, and it is difficult to maintain the rotational accuracy of the image rotating prism on the optical axis, and there is an inherent problem that the amount of light is attenuated by the prism. It was something.

Therefore, in order to solve these drawbacks, Japanese Patent Application Laid-Open No. 1987-
In Japanese Patent No. 165735, the subject's eye is periodically scanned with a slit-shaped light beam that is selectively scanned in two directions, and the moving speed, direction, and inclination (phase difference) of the light shape in the pupil due to these light beams are measured. By doing so, an eye refractive power measurement device has been proposed that calculates the spherical refractive power (S), cylindrical refractive power (C), and even astigmatism principal meridian direction (θ) of the eye to be examined from these measured values. has been done.

However, although such an eye refractive power measuring device does not require an image rotation prism, it requires a reflecting prism because the slit-shaped light beam must be scanned alternatively in two directions, which reduces the amount of light. In addition to this, it was difficult to equalize the positions and amounts of light of the two light sources for obtaining these two light beams, which caused manufacturing defects.

Furthermore, in the eye refractive power measuring device as described above,
Each of the slit-nod members for obtaining a slit-shaped light beam is constituted by a thin-walled cylindrical body that is rotatable around its axis and has a plurality of slits extending in the axial direction on its peripheral wall. However, in order to improve the measurement accuracy, it was necessary to finish the slits in the cylindrical body, especially the straight edge portions, with high precision, which made manufacturing difficult and made it difficult to process the cylindrical body. There was also the problem that the measurement accuracy of refractive power was affected by the degree of refraction.

(Solution Means) Here, the present invention has been made with the above-mentioned circumstances in mind, and its features include a projection optical system that projects a slit-shaped light beam onto the fundus of the examinee's eye; a condensing optical system that receives reflected light from the fundus of the examinee's eye of a light flux projected by a projection optical system, using two or more pairs of photoelectric conversion elements; and a position of an output signal between the aforementioned pre-sense conversion elements constituting each pair. In the objective eye refractive power measurement apparatus including a processing system for calculating the refractive power of the eye to be examined based on the phase difference, the slit is arranged so that the inclination angle of the slit-shaped light beam becomes two or more different angles. A plate provided with the above is disposed in the optical path of the projection optical system, and two or more slit-shaped light beams having different inclination angles are projected onto the fundus of the eye to be examined through the plate.

(Effects of the Invention) In the objective eye refractive power measuring device having the structure according to the present invention, a plate having a plurality of slits arranged in the optical path of the projection optical system is rotated, By periodically blocking or transmitting light from a predetermined light source, the eye to be examined is periodically scanned with a slit-shaped light beam.

Since the slits in such a plate are provided at two or more different angles, by rotating the plate in only one direction, the eye to be examined can produce slit-like light beams having two or more different angles of inclination. The refraction of the subject's eye can be determined from the moving speed, direction, and inclination (phase difference) of the light shape within the pupil, which is measured using a slit-shaped light beam with an oblique angle of about 1. The force will be calculated by calculation.

Therefore, in the eye refractive power measuring device according to the present invention, there is no need to selectively scan a slit-shaped light beam in two directions as in the past, there is no need for a reflecting prism, and there is only one light source. Therefore, it is possible to effectively simplify the structure and facilitate manufacturing, and also to facilitate and speed up refractive power measurement.

In addition, since the slit member for obtaining such a slit-like luminous flux is composed of a plate, it is extremely easy to manufacture and process compared to a conventional cylindrical body, and the processing accuracy of the straight edge part of the slit is improved. By improving this, it is possible to further improve measurement accuracy.

(Example) Hereinafter, in order to clarify the present invention more specifically, an example of the present invention will be described in detail with reference to the drawings.

First, FIG. 1 shows a configuration diagram of an objective type eye refractive power measuring device having a structure according to the present invention.

In this figure, 10 is a light source such as an infrared light emitting diode, and the light beam from the light source 10 is made into a substantially parallel light beam by a projection lens 14 arranged on a projection optical path 12, and then by a half mirror 16. reflected, the subject's eye 18
The light is projected into the pupil of the child.

Further, on the projection optical path 12, a disk-shaped plate 20 is disposed between the light source 10 and the projection lens 14, and the rotation axis 20 is approximately parallel to the optical axis of the projection lens 14.
A motor 24 having a rotary shaft 22 rotates around the rotation axis 22 . In this play) 20, as shown in FIG.
The slit 26 is formed in a linear shape in which edge portions facing each other in one direction are exposed at a predetermined interval and extend parallel to each other.
and 28 are provided, four each.

As shown in the figure, each of the slits 26 has an intersection point between the linear edge portion located forward in the rotation direction and an arbitrary circumference centered on the mounting hole 30 as the rotation center. , the inclination angle α between the radius of the circumference and the edge portion of the cough thrift 26 at this location is the same, and the other slit 28 is provided with The slit 28 is located at the intersection of the linear edge located forward in the rotational direction and an arbitrary circumference centered on the mounting hole 30.
The inclination angle (
α) is provided with a different inclination angle: β.

In addition, in the plate 20 in this embodiment, the inclination angle of each slit 26 and 28 with respect to one circumference centered on the attachment hole 30 as the locus of the optical path center of the projection optical path 12 on the plate 20 are set to have a relative inclination angle difference of 90 degrees from each other for measurement accuracy, that is, for example, α=45 degrees and β=−45 degrees with respect to the circumference.

Therefore, the light flux reaching the projection lens 14 from the light source 10 is
By the rotation of the plate 20 disposed on the projection optical path 12 between them, the beam is discontinuously interrupted, and a linear slit-like beam whose cross section has an inclination angle corresponding to the shape of the slits 26 to 28 is formed. In addition, such a slit-shaped light beam scans the inside of the pupil of the eye 18 according to the rotation of the plate 20.

Furthermore, as is clear from the above description, in this embodiment, the slits 26 and 28 projected onto the eye 18 are
In the slit-shaped light beam formed in , the linear portions in front of the rotation direction are projected with an inclination angle difference of 90 degrees from each other.

As is clear from this, in this embodiment, the light source 10. The projection lens 14, half mirror 16, and plate 20 constitute a projection optical system that projects a slit-shaped light beam onto the fundus of the eye 18 to be examined.

Furthermore, among the scanning light flux projected into the pupil of the eye 18 to be examined, the light reflected by the fundus and transmitted through the half mirror 16 is
The light is condensed by a condenser lens 32 disposed on a condensing optical path 30, and is irradiated onto a light receiving member 38 through a circular aperture 36 provided on the optical axis of a diaphragm 34 disposed behind the condenser lens 32. It has become. In this embodiment, the diaphragm 34 is arranged to be approximately conjugate to the fundus of the eye 18 to be examined.
Further, the positions of the light receiving surfaces of the light receiving members 38 on their respective optical axes are determined so that they are approximately conjugate to the cornea of the eye 18 to be examined.

The light receiving member 38, as shown in FIG.
On the light receiving surface, arranged around the optical axis,
A photoelectric conversion element 40 for alignment and four photoelectric conversion elements 42a each independently arranged off the optical axis.
, 42b, 42c, and 42d. As is well known, the misalignment between the measuring device and the subject's eye can be detected based on the presence or absence of output from the photoelectric conversion element 40 for corneal reflected light.

On the other hand, the four photoelectric conversion elements 42 arranged on the light-receiving surface of the light-receiving member 38 are arranged at approximately the same angle with each other centered on the optical axis.
The photoelectric conversion elements 42a and 42b are arranged on the circumference, and the photoelectric conversion elements 42a and 42b are symmetrical to each other with respect to the optical axis,
Further, other photoelectric conversion elements 42C and 42d are arranged symmetrically with respect to the optical axis. These photoelectric conversion elements 42a and 42b are arranged on the light-receiving surface with an inclination angle corresponding to the inclination angle of the linear portion in front of the rotational direction of the slit-shaped light beam by the slit 26 of the plate 20 projected onto the eye 18 to be examined. The other photoelectric conversion elements 42C and 42d are arranged at an inclination angle corresponding to the inclination angle of the linear portion in the forward direction of rotation of the slit-shaped light beam by the slit 28 of the plate 20 projected onto the eye 18 to be examined. It is arranged on the light-receiving surface at an angle. That is, in this embodiment, one pair of photoelectric conversion elements 42a and 42b and the other pair of photoelectric conversion elements 4
2c and 42d are arranged on a straight line having an inclination angle difference of 90 degrees with respect to the optical axis.

As is clear from this, in this embodiment, the condensing lens 32, the aperture 34, and the light receiving member 38 photoelectrically convert the light reflected from the fundus of the subject's eye of the light beam projected by the projection optical system. This constitutes a condensing optical system that receives light from the element.

Although not shown in the drawings, in the eye refractive power measuring device of this embodiment, the data from the four photoelectric conversion elements 42 constituting the condensing optical system under a predetermined operating state of the projection optical system is Based on the output signal,
It is constructed by including a calculation system for calculating the refractive power of the eye 18 to be examined based on the theory and calculation circuit as shown in Japanese Patent No. 165735.

Below, we will add a brief explanation of the principle of measurement and the calculation system.

First, if the eye 18 to be examined does not have astigmatism, the plate 20
The slit-shaped light beam from the light source 10 projected onto the eye 18 through the slits 26 and 28 is not rotated around the optical axis by the eye 18. Therefore, when the eye 1B to be examined is being scanned with a slit-shaped light beam by the slit 26, the pair of photoelectric conversion elements 42a and 42b in the light-receiving member 38 that receives the reflected light reflected from the fundus, when the light is incident, Exactly the same signal is obtained from the other pair of photoelectric conversion elements 42c and 42d.
A signal with a phase shift corresponding to the speed of the light reflected by the slit-shaped light beam on the light receiving member 38 is obtained. On the other hand, when the eye 18 to be examined is being scanned with the slit-shaped light beam by the slit 28, the light receiving members 42c, 42
The signals obtained from d are exactly the same when the light is incident, and the signals obtained from the photoelectric conversion elements 42c and 42d when the slit-shaped light flux by the slit 26 is scanned from the light receiving members 42a and 42b. A signal with the same phase shift as the signal will be obtained.

Based on the signals obtained from these photoelectric conversion elements 42, the velocity and time of the slit-shaped light beam on the light receiving member 38 and the plate 20 are determined as shown in the above-mentioned Japanese Patent Laid-Open No. 55-160538. The refractive power (spherical refractive index S) in the subject's eye 18 is calculated in the calculation system based on the relational expression with the rotational speed.

Next, if the subject's eye 18 has astigmatism, as is well known,
The eye 18 through the slits 26, 28 of the plate 20
The slit-shaped light beam from the light a1o projected onto the eye 18 is twisted along the optical axis by an angle (θ) corresponding to the scanning direction and the direction of the principal meridian of astigmatism. Therefore, each photoelectric conversion element 4 in the light receiving member 38 when the eye 18 to be examined is scanned with a slit-shaped light beam.
In addition to the spherical refractive power (S) in the subject's eye 18, the signal obtained from 2 is determined by the cylinder axis angle (θ) and the cylinder refractive power (
This means that it also has information regarding C).

That is, when the eye 18 to be examined is being scanned by the slit-shaped light beam from the slit 26, from the phase difference between the output signals of one pair of photoelectric conversion elements 42a and 42b,
The value obtained as the spherical refractive power based on the relational expression when there is no astigmatism is Dl, and the photoelectric conversion element 42 forming the other pair
From the phase difference of the output signal of C142d, the value obtained as the spherical refractive power based on the above relational expression is set as D2, and similarly when the eye 18 to be examined is scanned with the slit-shaped light beam by the slit 28, the photoelectric conversion element 42a, 42b
If the value obtained from the phase difference between the output signals of the photoelectric conversion elements 42c and 42d is D4, then So, these values 3, D2, D
3. D4 and the spherical refractive power (S
), the cylinder axis angle (θ), and the cylinder refractive power (C), the following relational expression is established.

D+=S+Ccos2θ □(1)D! =
−5in2 θ □(2)[), = −−si
n 2 θ □ (3) Da = S + Cs
in”θ □ (4) As is clear from the relational expressions (11 to (4)), there are three unknowns, S and C1θ, and the measured data are Dl, 1:h (=D3), and D4. Therefore, by processing these relational expressions in the calculation system, the spherical refractive power (
S), cylinder refractive power (C), and cylinder axis angle (θ) can be determined.

In the eye refractive power measuring device of this embodiment having the configuration described in detail above, the plate 2 having a plurality of slits 26 and 28 is disposed on the projection optical path 12.
0 is rotated and the light from a predetermined light source projected onto the eye 18 to be examined is periodically blocked or transmitted, so that the eye 18 to be examined is periodically scanned with a slit-shaped light beam. Since the slits 26 and 28 in the plate 20 are provided with different inclination angles, the plate 20
By rotating the eye in only one direction, the eye to be examined 18
is scanned by slit-shaped light beams with different inclination angles, and from the moving speed, direction, and inclination (phase difference) of the fundus reflected light measured by slit-shaped light beams with different inclination angles. , the refractive power of the eye to be examined is calculated by calculation.

Therefore, in such an eye refractive power measuring device, there is no need to selectively scan a slit-shaped light beam in two directions as in the past, there is no need for a reflecting prism, and only one light source 10 is required. Simplification of structure and ease of manufacture can be effectively achieved, and refractive power measurement can be made easier and faster.

In addition, since the plate 20 for obtaining such a slit-shaped light beam is formed in a disk shape, it is extremely easy to manufacture and process compared to the conventional cylindrical shape, and the slit 26.28 By improving the machining accuracy of the edge straight portion, it is possible to further improve the measurement accuracy.

Furthermore, since the plate 20 is shaped like a disk, the installation space can be smaller than that of a cylindrical plate, and the weight can be reduced, which reduces the burden on the motor 24. Therefore, it is possible to effectively reduce the size and weight of such a measuring device.

Next, FIG. 4 shows another embodiment of a plate suitably used in the eye refractive power measuring device according to the present invention.

That is, the plate 44 has four slits 46 and 48 each provided at different angles of inclination with respect to the radius.

The linear edge portions located on the one rotation direction side of each of the slits 46 and 48 are similar to the linear edge portions located on the rotation direction front side of the slits 26 and 28 shown in the above embodiment. The inclination angles α and β formed by the radius of the circumference at the intersection point with an arbitrary circumference centered on the mounting hole 30 as the center of rotation are set to be the same, and Even if the linear edge portions of the slits 46 and 48 are located on the other rotational direction side, the angle of inclination α゛ formed by the radius of the circumference at the intersection with an arbitrary circumference centered on the mounting hole 30 and β゛ are respectively α”−
In particular, in this embodiment, a circle centered on the mounting hole 30 as a locus of the optical path center of the projection optical path on the plate 44. The angle of inclination of the straight edges on both sides of each slit 46 and 48 with respect to the circumference is α=α
1=45 degrees and β-β"=-45 degrees.

Therefore, when such a plate 44 is used in the apparatus according to the above embodiment, refractive power can be well measured according to the theory described above, regardless of which direction the plate 44 is rotated. Therefore, the assembly of the plate 44 to the rotating shaft 22 is directional, in other words, the plate 4
There is no need to consider the distinction between the front and back surfaces in step 4, and the ease of assembly during device manufacturing can be further improved.

Although one embodiment of the eye refractive power measuring device structured according to the present invention has been described above, this is a literal illustration, and the present invention should be construed as being limited only to this specific example. isn't it.

For example, in the eye refractive power measuring device in the above embodiment, the slit 26 (46) in the play 20 (44)
) and 28 (48) are formed in a form capable of projecting two mutually orthogonal slit-shaped light beams onto the subject's eye 18, but the shape, number, and relative angle difference are not limited. Alternatively, they may be formed at three or more different angles.

In addition, in the eye refractive power measuring device in the above embodiment, only the main parts of its configuration are illustrated, and in order to further improve the measurement accuracy, for example, the reference line of the eye to be examined is fixed. It is preferable to add a fixation target optical system as shown in Japanese Patent Publication No. 55-160538.

Furthermore, as shown in Japanese Unexamined Patent Publication No. 57-165735, a so-called automatic fogging device is added, and the movement of the optotype is controlled by the subject's eye based on the refractive power calculated by the calculation system of the device itself. It is also possible to obtain the refractive power by repeating this process until the refractive power of 2 does not change.

Furthermore, in the calculation system of the eye refractive power measurement device in the above embodiment, the refractive power was calculated from the measured values, but this method is not disclosed in Japanese Patent Application Laid-open No. 165735/1983. After completing the device, measurements were taken using a simulated eye, and the output value of each photoelectric conversion element 42 at that time (
It is also possible to store the phase difference) in the calculation system in correspondence with the known refractive power of the simulated eye, and by doing so, the projection optical system and the condensing optical system can be The arrangement of the constituent members can be relatively freely arranged. Furthermore, when the output value of each photoelectric conversion element 42 and the refractive power of the eye 18 to be examined are correlated in this way and the correspondence relationship is entered into the calculation system,
There is no need to make the inclination direction of the slit-shaped light beam of the projection optical system coincide with the arrangement direction of the photoelectric conversion elements 42 forming a pair in the light receiving member 38 of the condensing optical system, and the plate 20 (4
4) The inclination angle and shape of the slits 26, 28 (46, 48) can be freely set to a certain extent.

Furthermore, in the above embodiment, the plate 20 is
Although the plate 20 is disposed between the projection lens 10 and the projection lens 14, the plate 20 may be disposed between the projection lens 14 and the half mirror 16.

In addition, although not listed, the present invention includes various modifications,
It goes without saying that the present invention may be implemented in a manner with improvements, modifications, etc., and that such aspects are included within the scope of the present invention as long as they do not depart from the spirit of the present invention. It's a good place.

Furthermore, the present invention can be applied to, in principle, no changes in any way, in addition to the eye refractive power measuring device as described above, for example, to a lens meter or a corneal curvature radius measuring device. .

[Brief explanation of the drawing]

FIG. 1 is a block diagram schematically showing an embodiment of an eye refractive power measuring device structured according to the present invention, and FIG. 2 is a front view showing a plate used in such an eye refractive power measuring device. FIG. 3 is a front view showing a light receiving member used in such an eye refractive power measuring device. Moreover, FIG. 4 is a front view corresponding to FIG. 2, showing another embodiment of the plate used in the ocular refractive power measuring device structured according to the present invention. 10: Light source 12: Projection optical path 14: Projection lens 16: Half mirror 18: Eye to be examined 2
0.44 Nibrate 26.28, 46, 48 Nislit 30: Condensing optical path 32: Condensing lens 34: Aperture
38: Light receiving members 42a, 42b, 42c, 4
2d: Photoelectric conversion element Applicant: Toyo Medical Co., Ltd. Figure 1 Figure 3 Figure 2 ~ -111111'

Claims (1)

[Claims] a projection optical system that projects a slit-shaped light flux onto the fundus of the subject's eye; and a condensing optical system that receives reflected light from the fundus of the subject's eye of the light flux projected by the projection optical system using two or more pairs of photoelectric conversion elements. , an objective eye refractive power measurement apparatus including a processing system for calculating the refractive power of the eye to be examined based on the phase difference of output signals between the photoelectric conversion elements constituting each pair, the slit-shaped A plate provided with slits so that the inclination angles of the light beams are two or more different angles is disposed in the optical path of the projection optical system, and the slit-shaped light beams with two or more different inclination angles are exposed through the plate. An objective eye refractive power measurement device characterized by projecting the image onto the fundus of the eye.