JPS6254005B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optometric apparatus that subjectively measures the refractive power of a spectacle lens appropriate for a subject.

Conventionally, in order to determine the appropriate refractive power of eyeglass lenses for the examinee, the examinee is asked to wear various lenses and look at indicators, and the lens with the optimal refractive power is determined based on the examinee's vision. In addition, there are testing instruments that have multiple lenses inserted between the subject and the index by switching between them.
In this case as well, the refractive power of the lens when the examinee judged that the index was easiest to see was determined to be the optimal refractive power for the examinee.

In such conventional measurement methods and devices,
Since the test subject's reaction is observed by switching between various lenses, not only is the measurement time-consuming, but both the tester and the test subject feel troublesome. Furthermore, the device has a large number of lenses and requires a complicated switching mechanism, making it large and
Moreover, it had become expensive.

An object of the present invention is to provide an optometry device that can accurately measure the refractive power of a spectacle lens that is optimal for a subject with a simple configuration and operation.

The present invention will be described below based on embodiments shown in the drawings.

FIG. 1 shows an optical system according to an embodiment of the present invention and an electrical system that operates upon receiving signals from its elements. A pair of cylindrical lenses 3 and 4 having the same refractive power, as shown in a perspective view in FIG. 2, are provided by the relay lens at a position conjugate with the eyeglass wearing position P of the eye _E1 to be examined. The pair of cylindrical lenses 3 and 4 are arranged adjacently so that the intersection of their axes coincides with the optical axis O, and the initial position is the position where the axes intersect perpendicularly, and the lenses are arranged in opposite directions with respect to the optical axis O. Rotate an equal amount to . Such a double cylindrical lens, whose power changes continuously and whose axis remains constant, is known to have been devised by Mr. Snellen. Eye to be examined E ₁ in front of a pair of cylindrical lenses 3 and 4
A diaphragm 2 for limiting light flux is provided at a position conjugate to the cornea. The front focal position of the objective lens 5 corresponds to a position conjugate with the glasses wearing position P by the relay lens 1, that is, between the pair of cylindrical lenses 3 and 4, and the eye E ₁ to be examined is visible behind the objective lens 5. An index 6 is provided for this purpose. Note that the distance from the corneal apex of the eye to be examined _E1 to the glasses wearing position P is generally 12 mm.

A pair of cylindrical lenses 3 and 4 each have a circular holding frame 3 having a gear formed on its outer peripheral surface as shown in FIG.
0,40, and the circular holding frame 30,4
0 are meshed with gears 31 and 41, respectively, and the gears 31 and 41 are coupled to rotating shafts of pulse motors 32 and 42, respectively, which rotate by the same amount in opposite directions with one pulse. The pulse motors 32 and 42 are the drive circuit 3
3 output, rotates by pulse. As will be described later, this number of pulses corresponds to the cylindrical surface refractive power. Above members 30, 31, 32, 33, 40, 41, 4
2 constitutes a rotating device 34 for the pair of cylindrical lenses 3 and 4. The indicator 6 is held on a holding member 60, and between the holding member 60 and the indicator 6,
A linear encoder 61 is provided. The amount of movement of the index 6 with respect to the holding member 60 can be obtained from the output of the encoder 61. As will be described later, this amount of movement corresponds to the spherical refractive power. Holding member 6
0 is further placed on a moving member 62, and the moving member 62 is moved in the optical axis direction by a motor 63. Motor 63 is driven by control circuit 64 . The control circuit 64 sequentially counts the number of pulses output from the drive circuit 33 (FIG. 3) and determines the rotation amount of the motor 63 so as to move the moving member 62 in the optical axis direction by an amount corresponding to the counted value. The relationship between the number of pulses output from the drive circuit 33 and the amount of movement of the moving member 62 will be described later.

As shown in FIG. 2, a pair of cylindrical lenses 3, 4
are usually arranged so that their radial directions X and Y are perpendicular to each other. At this time, it is in the initial state, and the counter of the control circuit 64 has been reset so that the number of pulses output from the drive circuit 33 is zero. In such a state, a pair of cylindrical lenses 3,
4 have the same refractive power D ₀ , the double cylindrical lenses 3 and 4 function as if they were a single spherical lens with refractive power D ₀ . When a pulse is output from the drive circuit 33 and the pair of cylindrical lenses 3 and 4 are rotated by an equal amount in opposite directions, the direction of the main axis of the double cylindrical lenses 3 and 4 does not change, and The refractive powers D ₁ and D ₂ in the directions of the two main meridians change as shown in equations (1) and (2) below.

D ₁ = 2D ₀ cos ² (45-θ) ……(1) D ₂ = 2D ₀ sin ² (45-θ) ……(2) However, θ is a pair of cylindrical lenses as shown in Figure 2. This is the angle formed by the directions X' and Y' of the radial lines No. 3 and No. 4 with respect to the directions X and Y at the initial position where they are arranged so as to be perpendicular to each other.

When equations (1) and (2) are expressed in a graph, the result is as shown in Figure 4. According to Figure 4, the refractive power is from θ=0 to θe.
The changes in D ₁ and D ₂ are almost linear, and if the proportional number is k, D ₁ (=-D ₂ )=kθ (however, θ=0 to θe)
It turns out that it can be regarded as (3).

Therefore, when θ=0 to θe, the number of pulses output from the drive circuit 33 (proportional to θ) is proportional to the refractive power D ₁ of one main meridian.

On the other hand, if the focal length of the objective lens 5 is f ₀ ,
Refractive power D of the eyeglass lens required by the eye to be examined _E1
and the moving distance Z of the index 6.
When the pair of cylindrical lenses 3 and 4 are in the initial state,
If it is defined as the moving distance from the index position (reference position) where a person with emmetropia can clearly see the index, then the following formula (4) can be obtained.
holds true.

D=f ₀ ² Z ...(4) Here, the refractive power D ₁ (-D ₂ ) in one principal radius in the above equation (3) and the refractive power D in the above equation (4) are made equal. If you put a pair of cylindrical lenses 3 and 4
The following equation is established between the rotation angle θ and the movement amount Z of the index 6.
(5) The following relationship is established.

θ=f ₀ ² /kZ ...(5) Equation (5) is expressed by the refractive power D ₁ (-D ₂ ) of the main meridian obtained by the rotation of the pair of cylindrical lenses 3 and 4 and the movement of the index 6. Since the change in refractive power D obtained by is equal to the change in refractive power D obtained by It is possible to change only the refractive power in the other main radial line without changing the refractive power in the main radial line.

That is, the control circuit 64 counts pulses from the drive circuit 33 of the rotating device 34, controls the motor 63 to move the moving member 62 in the optical axis direction based on the above equation (5), and thereby , while changing the refractive power in one main meridian while keeping the refractive power in the other main meridian constant.

Because of this configuration, if an index with a shape as shown in Figure 5 is used, and a subject with astigmatism sees an index that extends in the vertical direction and is twisted as shown in Figure 6a. To do this, the device 20 is rotated about the optical axis. If the subject observes an index that extends vertically but is not twisted, as shown in Figure 6b, the rotation of the device 20 is stopped, and then the height of the index is adjusted as shown in Figure 6c. The indicator 6 is moved on the holding member 60 until the distance is minimized. The amount of movement of the index 6 is read by a linear encoder 61. Index 6 obtained by linear encoder 61
The amount of movement Z can be converted into a refractive power D using equation (4), and the refractive power D obtained at this time is the spherical power (S) of the eye _E1 to be examined. Also, the rotation angle of the device 20 when the rotation is stopped gives the direction of one of the main meridians. This direction will be the reference.

Next, when the apparatus 20 is further rotated around the optical axis by 90 degrees, the subject will notice that the index is not twisted as shown in FIG. 6d, but is shifted in the vertical direction. Then, the subject rotates the pair of cylindrical lenses 3, 4 by sequentially applying pulses to the pulse motors 32, 42 from the drive circuit 33 so that the height of the index is minimized as shown in FIG. 6e. On the other hand, as the cylindrical lenses 3 and 4 rotate, the movable member 62 is moved by the motor 63 driven by the control circuit 64 that receives pulses from the drive circuit 33, and the refractive power in the direction of the main radius that has already been measured is The index 6 moves in the direction of the optical axis so as not to change.
Since the indicator 6 and the holding member 60 are integrated, the reading of the linear encoder 61 does not change. When the subject recognizes that the height of the index as shown in FIG. 6e has reached the minimum, the generation of pulses from the drive circuit 33 is stopped. The astigmatic power C can be determined from the rotation angle θ of the pair of cylindrical lenses 3 and 4 at this time.
If the above-mentioned moving member 60 moves to the right, the astigmatic power C
will be displayed as +, and if you move to the left, it will be displayed as -. That is, in FIG. 7, curves D ₁ and D ₂ are exactly the same as curves D ₁ and D ₂ in FIG.
As the pair of cylindrical lenses 3 and 4 rotate, the index 6
Moving based on equation (5) means that
Change the index 6 as shown in the curve D ₃ or D ₅ in Figure 7 (when the curve is D ₃ , the index 6 is moved to the left in Figure 1, and when it is D ₅ , the index 6 is moved to the right). It means that. That is, D ₁ (θ) + D ₃ (θ) =
D ₂ (θ) + D ₅ (θ) = D ₀ . D ₃ (θ) or D ₅ (θ) that satisfies these conditions is D ₃ (θ)=
It is given by D ₀ - _{D 1} (θ), D ₅ (θ) = D ₀ - D ₂ (θ). Therefore, the refractive power in the other main radial direction changes with the rotation of the pair of cylindrical lenses 3 and 4, or D ₄
(θ)=D ₁ (θ)−D ₂ (θ)+D ₀ , D ₆ (θ)=D ₂
(θ) − D ₁ (θ) + D ₀ , so the seventh
It will look like curve D ₄ or D ₆ in the figure. Rotation angle θ
The astigmatic power C is obtained by the correspondence between and the refractive power. The sign of the astigmatic power C is determined by the moving direction of the holding member 60.

Through the above operations, the direction of the main radial line, the spherical power S, and the astigmatic power C of the eye _E1 to be examined can be determined. In order to unify the astigmatic power C to be positive or negative, a well-known power conversion method may be used.

The above explanation is an example of the most common case,
Depending on the state of the eye _E1 to be examined and the initial state of the device, measurements may be performed from the state shown in Figure 6b, but the operations are the same as in the general case described above. When the subject's eye _E1 is spherical, the subject visually recognizes an index extending only in the vertical direction, as shown in FIG. 6f. (However, protrusion 6 of index 6
If point a is correctly oriented in the vertical direction as shown in FIG. 5, and the indicator 6 is tilted, then, for example, FIGS. 6 b and d will be viewed accordingly. ) In that case, rotating the device will not change the orientation of the image.

In addition, in the above explanation, for the sake of simplicity (to simplify the interlocking mechanism), equation (2) is treated as equation (4), and the rotation angle of the pair of cylindrical lenses 3 and 4 is the refractive power. Although the explanation has been made in terms of a range that has a proportional relationship within the error range, Z=2D ₀ /
If the relationship f ₀ sin ² (45-θ) is obtained and the index 6 is corrected, that is, the holding member 60 is moved based on the relationship, the astigmatic eye can be measured more accurately and over a wider range. However, the purpose of this device is primarily to determine the refractive power of eyeglass lenses, and no matter how accurate or
Even if measurements can be made over a wide range, there is no suitable lens available, so we believe that a method based on the linear approximation of equation (2) as described above is sufficient in practice. Furthermore, if the front focal position of the objective lens is made to coincide with the spectacle wearing position, the refractive power D and the movement amount Z of the index 6 can be easily expressed as in equation (4), which is convenient. The front focal position of the objective lens does not need to match the spectacle wearing position, as long as the relationship with the movement amount Z of the index 6 is willing to be complicated.

If the diaphragm 2 is configured as in the above-described embodiment, the subject will have to visually recognize the indicators as shown in FIGS. 6a to 6f, which may make it troublesome to identify the shape and orientation. In such a case, instead of the diaphragm 2 in Fig. 1, as shown in Fig. 8, a diaphragm 2' may be installed outside the optical axis.
If one having two openings 2'a and 2'b is provided,
Complete matching of two indicators as shown in Figure 9 a to e (a to e correspond to a to e in Figure 6) (Figure 9
Since the spherical power S and the astigmatic power C can be determined from Figure c or e), identification is relatively easy.

Furthermore, instead of moving index 6 directly, the first
As shown in FIG. 0, a triangular prism 100 movable in the optical axis direction is provided between the objective lens 5 and the index 6,
The indicator 6 may be indirectly moved by the movement of the prism 100. Of course, in this case, the amount of movement Z' of the prism 100 is in the relationship Z'/2=Z with the amount of movement Z of the indicator 6 when the above-mentioned indicator 6 is directly moved.

Furthermore, by controlling this device with a microcomputer, it can be made into a completely automated device that does not require an examiner to set up the device. In this case, the examiner only needs to align the device and the subject.

That is, after the examiner has completed the alignment, the examinee operates the operation buttons, etc. to instruct the rotation of the device and the movement of the index, and when an image like that shown in Figure 6 or Figure 9 c is seen, the examinee presses the OK button. Press. Then, the rotation angle of the device from the rear encoder 61 and the reference position is read into the computer, and then the device is further rotated by 90 degrees according to a command from the computer. When the rotation is completed, the double cylindrical lenses 3 and 4 start rotating according to the command from the computer, and the subject presses the OK button again when the image as shown in Figure 6 or Figure 9 e is seen. . Of course, there is also a rotary operation button for the examinee to ensure accuracy. Furthermore, in consideration of the case where the eye to be examined _E1 is spherical, a button is provided to command whether or not the vision has changed after the device has rotated 90 degrees, and the rotation of the double cylindrical lens starts only when there is no change. , otherwise it is sufficient to indicate that it is a spherical lens. In this way, the rotation angles of the double cylindrical lenses 3 and 4 are read into the computer, and the computer reads S, C,
(spherical power, astigmatic power, axis angle) and drives the display. After performing alignment in this way, the examiner only has to wait for the value to be displayed on the display.

As described above, according to the present invention, it is possible to obtain an optometry device that can accurately measure the refractive power of a spectacle lens that is optimal for a subject with a simple configuration and operation.

[Brief explanation of the drawing]

FIG. 1 shows the optical system and electrical system of one embodiment of the present invention. FIG. 2 is a perspective view of a pair of cylindrical lenses, FIG. 3 is a diagram showing the relationship between the cylindrical lenses and the electrical system, and FIG. 4 is a diagram showing changes in the refractive power D ₀ of the cylindrical lenses.
Figure 5 is an example of the index, Figures 6a to 6f are examples of the shape of the index in Figure 5 that the subject recognizes, and Figure 7 is the index that is calculated using formula (5) as the cylindrical lens rotates. Figure 8 shows another example of the diaphragm 2, and Figures 9a to 9e show the changes in D when moving based on the figure 6a.
- Figure 10, which corresponds to Figure 6e, shows another embodiment in which the indicator is moved indirectly. Explanation of symbols of main parts, 1... Relay lens,
3, 4... Cylindrical lens, 5... Objective lens, 6...
...Indicator, 62...Moving member, 33...Drive circuit.

Claims (1)

[Claims] 1 A pair of identical refractive powers that are arranged adjacently so that the intersection points of their axes coincide with the optical axis, and that are rotatable in opposite directions at the same angle, with the initial position being the position where the mutual axes intersect at right angles. a cylindrical lens, a relay optical system that makes the cylindrical lens conjugate to the eyeglass wearing position of the eye to be examined, an objective optical system located behind the eyeglass wearing position of the optical system, and an objective optical system located behind the objective optical system. , a visual indicator movable in the optical axis direction, and a rotation of the cylindrical lens in order to change the refractive power in the other main radial direction without changing the refractive power in one main radial direction. A subjective optometry device comprising: an interlocking device that interlocks to move the index in the optical axis direction.