JPS6128331B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for measuring the refractive power of an eye, and in particular to a device for automatically performing objective measurements.

Ocular refractometers have been used for a long time as basic tests in clinical ophthalmology and to obtain data for preparing eyeglasses, and various measurement methods and device structures have been proposed, but recently they have received attention. The product automatically performs the measurement of refractive power and then determines the spherical diopter, degree of astigmatism, and angle of the astigmatic axis. These devices usually project a measurement pattern toward the fundus of the eye being examined, perform servo control so that the pattern is clearly imaged on the fundus, measure the eye refractive power, and center the pattern on the optical axis. In order to obtain information about astigmatism by rotating the lens, a measurement time of several seconds is required for a short measurement, and several tens of seconds for a long measurement. Therefore, the test subject's eyes must remain fixed on the fixation target without changing their eye accommodation, which is painful for adults as well, but measurement is often impossible for children, and the results are inaccurate. Even if it is obtained, it often contains errors, resulting in the inconvenience that the adjusted glasses may not fit the eyes or that it takes time to make corrections.

The present invention has the purpose of rapidly measuring the refractive power of the eye to be examined, and also has the purpose of providing a structure that allows rapid measurement operations.

An example will be described below, but since its configuration is somewhat complex, an outline of the configuration will be explained first.

In this example, a beam of light forming images of three measurement indicators is projected onto the fundus of the eye to be examined, and an optical member such as a relay lens is moved in the optical axis direction of the projection system in order to move the image of the indicators with respect to the fundus. The refractive power of the eye to be examined is measured based on the deviation from the reference position when the index image satisfies a predetermined condition by moving the index image, and prior to measurement, the position of the movable optical member on the optical axis is detected. When the movable optical member is positioned at one end of the moving range according to the signal from the detector and the measurement start switch is turned on, the movable optical member rapidly and continuously moves toward the other end of the moving range, and the light is reflected off the fundus. The deviation difference signals incident on the three photoresponsive elements corresponding to each of the index images and the signal of the position on the optical axis of the movable optical member related to the eye refractive power are sequentially sent to the signal processing circuit as the movable optical member moves. , the acquisition of measurement data is completed when the movable optical member reaches the other end of the movement range. That is, the movable optical member moves continuously in one direction, moves one outward path or one backward path, and completes the acquisition of measurement data. In this method, the optical member is continuously moved in one direction, so even if it is moved at high speed, overshoot and hysteresis errors that tend to occur when moving the optical member back and forth using servo control as in conventional methods do not occur. Accurate measurement is possible.

In the embodiment, the relay lens is moved to move the target image, but for example, the mask providing the target may be moved, or the optical path length may be changed midway. Further, as the measurement light beam, in order not to make the subject nervous during the measurement, it is preferable to use a light beam in the infrared or near-infrared wavelength range that does not cause eye sensitivity. Furthermore, in the example, measurements were made on three diameter lines, and the reason for this will be explained.
First, if it is assumed that the change in diopter in the meridian direction in astigmatism changes sinusoidally, the diopter can be expressed as a function of the angle in the meridian direction by the following equation.

D=A sin(2θ+α)+B (1) The variables D and θ represent diopter and meridian angle, respectively. The constants A, B, and α are the degree of astigmatism, the average diopter, and
Corresponds to the astigmatism axis direction. Since there are three unknowns in equation (1), if there are measured values in at least three meridian directions,
By applying equation (1), each value of the degree of astigmatism, average diopter, and astigmatism axis direction can be determined for any meridian direction. It goes without saying that by increasing the number of meridian directions to be measured without limiting it to three, the accuracy can be improved by finding the above values in any three of them and averaging them with the values found in other combinations. do not have.

FIG. 1 shows a first embodiment of the automatic ocular refractometer of the present invention. In the figure, E indicates the eye to be examined, Ef indicates the fundus of the eye, that is, the retina, and Ep indicates the pupil. Further, reference numeral 1 is an objective lens, and 2 is a light splitter, which is a mirror with a central aperture. 3 is a relay lens, which is coaxial with the objective lens and movable in the optical axis direction. 4 is a projection mask, and 5 is a set of triangular prism columns. The planar form of this mask 4 is as shown in FIG. 4c
and a prism column 5 according to each slit.
a, 5b, and 5c are arranged. This prism pillar is
It has the function of refracting the light beams emitted from each slit to separate them from each other so that they do not mix on the pupil. Note that these slits serve as measurement indicators.

Next, 6 is a condenser lens, 7 is a light source,
The condenser lens 6 has a function of condensing the light emitted from the light source 7 onto the mask 4.

The above members 1 to 7 constitute a projection system, the aperture 2a of the light splitter and the pupil Ep are conjugate with respect to the objective lens 1, and the mask 4 and the fundus Ef, including intermediate imaging, are conjugate with respect to the objective lens 1 and the relay lens 3. Can be tuned conjugately.

Furthermore, 8 is another relay lens, 9 is a detection mask, 10 is a photodetector, the objective lens 1 and the reflective surface of the light splitter 2, and members 8 to 10 constitute a detection system. The projection system and the detection system are optically conjugate and equivalent with respect to the light splitter 2.

The planar configuration of the detection mask 9 is as shown in FIG.
The projection mask 4 is arranged so as to satisfy a conjugate relationship with the projection mask 4. Slit groups 9a, 9 of detection mask 9
Behind b, 9c are photoresponsive elements 10a, 10b,
10c are arranged individually, and the output of the photoresponsive element will be described later. are added to amplifiers 40a, 40b, and 40c, respectively.

Next, reference numeral 11 is a support member that supports the relay lens 3, and is inscribed inside a cylinder 12 that guides the relay lens 3 in the optical axis direction so as to be able to slide in the optical axis direction. Reference numeral 13 denotes a connecting member that protrudes from the support member 11 and has a roller 14 fitted at its tip. The tube 12 also has a groove 12a long in the optical axis direction, and the width of the groove fits lightly into the connecting member 13 to prevent the support member 11 from rotating. 15 is a spring, 16 is a spring fixing member implanted in the housing, and 17 is an eccentric disk-like circumferential cam. The spring 15 brings the roller 14 into close contact with the cam surface of the cam 17. cam 17
When rotated by the member described below, the roller 14
is pushed out in the optical axis direction, and the relay lens 3 moves in the optical axis direction. Reference numeral 19 denotes a rotating shaft, which is supported by a bearing (not shown). A gear 18 is fixed to a rotating shaft 19, and a cam 17 is fixed to the other end. 18' is a gear that meshes with gear 18, 20 is a rotating shaft, and a cam 17' similar to gears 18' and 17 is fixed thereto. Further, 11' to 17' have the same functions as 11 to 17, and each number corresponds to an individual member.

Here, 11 to 17 act to move the relay lens 3 in the optical axis direction, and 11' to 17' act to move the relay lens 8 in the optical axis direction.
Note that if the refractive powers of the relay lenses 3 and 8 are made equal, the amount of movement of both lenses will always be the same, and the members 11 to 18 and the members 11' to 18' can be made of the same material, which is convenient. good.

The relay lenses 3 and 8 reciprocate once per cam rotation, and the cams 17 and 17' are fixed to the rotation shafts 19 and 20 so that the lift relative to the rotation angle of the cams 17 and 17' matches the phase. The engagement is maintained by 18'. Therefore, when the rotating shaft 20 rotates, the relay lenses 3 and 8 move synchronously.

Note that in this configuration, the cam only needs to rotate in one direction.

Next, 21 is an electromagnetic brake, and 22 is an electromagnetic clutch. 23 connects the gear head 24 to the clutch 22.
The shaft 25 that transmits the rotation of the motor is an electric motor, which rotates in one direction. Here, the electromagnetic brake 21 has a function of stopping the rotation of the rotating shaft 20, and the electromagnetic clutch 22 has a function of connecting or disconnecting the power of the motor 25 to the rotating shaft 20. The above members 11 to 25 and 11' to 17' constitute a mechanism for moving the relay lenses 3 and 8.

On the other hand, 26 is a bar implanted in the support member 11 of the relay lens 3, 27 is a position detector;
is fed to the position detector 27, and as a result, the output of the position detector 27 changes as the position of the relay lens 3 on the optical axis changes. A direct-acting potentiometer or linear encoder is suitable for the position detector, but if the amount of rotation of the rotating shaft 19 is to be detected, it would be better to use a rotary potentiometer or rotary encoder. It will be done.
28 is a chopper reticle of the light source 7, which is rotated by a motor (not shown) at a frequency suitable for removing disturbances.

In this embodiment, a direct-acting potentiometer is used as the position detector 27, and the output of this potentiometer is fed to a non-linear amplifier 31, which will be described later.
and 34 comparators. In addition, the output of the direct acting potentiometer 27 is the relay lens 3.
Within the movement range, the lowest voltage is generated when it is closest to the mask 4, increases as it moves in the direction of the arrow, and the highest voltage is generated when the relay lens 3 is farthest from the mask 4. do. Reference numeral 33 is a reference voltage generator, which is set at a very small distance in the direction of the arrow from the position where the relay lens 3 is closest to the mask 4, for example, approximately
Direct-acting potentiometer 2 with 0.5mm movement
The output of the reference voltage generator is applied to a comparator 34. The comparator 34 compares the reference voltage and the output of the direct-acting potentiometer 27,
When the output of the direct-acting potentiometer is lower than the reference voltage, a logic output "H" is output. With the above configuration, the position of the relay lens 3 is set to the mask 4.
The area from the closest position to the position moved approximately 0.5 mm in the direction of the arrow is defined as the stop area of the relay lens 3, and when the relay lens 3 is located in this stop area, the comparator 34 outputs a logic output "H". .

In addition, in this configuration, the section approximately 0.5 mm from the position where the relay lens 3 is closest to the mask is defined as the stopping section, but the section approximately 0.5 mm from the position where the relay lens 3 is farthest from the mask is defined as the stopping section. It's okay. The output of the direct-acting potentiometer 27 may be configured such that the relay lens 3 outputs the highest voltage at the extreme end of its movement range, and the output voltage decreases as the relay lens 3 moves.

35 is a diode-like indicator, which lights up when the comparator 34 is outputting an H level, that is, when the relay lens 3 is located in the stop zone, to notify the latter. The output of comparator 34 is applied to microprocessor 36. The microprocessor 36 includes a CPU, memory elements (ROM,
RAM) consists of an input/output control circuit, a clock, etc., and is programmed to perform centralized control, sequence control, function calculation processing, and display control of the signal processing circuit, which will be described later.

Next, 31 is a non-linear amplifier that corrects a change in the output voltage of the direct-acting potentiometer 27 corresponding to a change in the optical position of the relay lens 3 so that it becomes a linear change in diopter. The output of the non-linear amplifier 31 is sent to an A/D converter 32 and converted into a digital signal in synchronization with the clock signal output by the microprocessor. The frequency of this clock signal is determined based on the moving speed of the relay lens 3 and the desired diopter detection resolution.

Furthermore, 40a is an amplifier for demodulating only the light intensity signal superimposed on the carrier wave from the output of the photodetector 10a, and includes a preamplifier, a bandpass filter whose center frequency is the chop frequency of the light source 7, and a signal It consists of a demodulator that detects waves.

The demodulated output signal is sent to the A/D converter 41a, where it is converted into a digital signal in synchronization with the clock signal output by the microprocessor 36, and sent to the microprocessor for storage one by one.
Here, the A/D converter 32 and the A/D converter 41
The same clock is applied to A and A, and each time a clock pulse is input, it is A/D converted and sequentially stored in the microprocessor. The microprocessor immediately reads out the stored digital value and compares it with the digital signal A/D converted by the A/D converter 41a using the next clock signal.
When the measurement switch 39 is turned on, the relay lens begins to move, and the output sign of the comparator 34 is reversed, the microprocessor 36 outputs the clock and starts the comparison. The input from the A/D converter 41a is compared with the digital value A/D converted and stored by the previous clock pulse, and if the former is larger than the latter, the comparison is repeated one by one and erased to the former. When the latter is memorized and the former becomes smaller than the latter, the A/D converter 32
A command is issued to store the optical position of the relay lens input from the A/D converter 41a, the command is stored in the memory, the comparison is stopped, and input from the A/D converter 41a is prohibited.
In addition, a program is written in the microprocessor to convert the optical position of the relay lens into a diopter in response to a clock pulse. Create a program to correct it to the degree value. The diopter value obtained here is the maximum value obtained in one measurement, and is the spherical diopter in one radius of the eye to be examined, and is stored in the memory. 40a and 40b process the output from 10b, and 40c and 41c process the output from 10c in the same way, and store the spherical diopter in the other two meridians of the eye to be examined.

Next, the microprocessor stops clock generation to each A/D converter when the spherical diopter of the three meridians of the eye to be examined is stored.

Further, in this configuration, the stop section is detected by the reference voltage generator and the comparator, but the output of the nonlinear amplifier 31 may be constantly A/D converted and detected by the microprocessor. The operation of the above-mentioned configuration will be explained below.

When the device of this embodiment is connected to a commercial power source 37 and the power switch 38 is turned on, the light source 7, a motor (not shown) that rotates the chopper reticle 28, the motor 25, and each circuit are activated by commands from the microprocessor 36. A predetermined energization is performed. Next, the output of the direct-acting potentiometer 27 and the output of the reference voltage generator 33 are compared by a comparator 34 to detect whether the position of the relay lens 3 is in the stop zone. When the relay lens 3 is located in the stop zone, the display 35 lights up and an "H" level signal is sent to the microprocessor 36, which causes the microprocessor to switch the switch circuit to the electromagnetic brake 21. is turned on to energize the brake 21 and apply an electromagnetic brake to the rotating shaft 20. or,
Microprocessor 36 commands the switch circuit to electromagnetic clutch 22 to turn off, causing electromagnetic clutch 2 to turn off.
2 remains open, and only the driving side of the motor 25, gear head 24, transmission shaft 23, and clutch are rotating.

Next, if the relay lens 3 is not located in the stop section, the comparator 34 is at logic level "L".
Upon receiving the output, the microprocessor 36 commands the switch circuit to the electromagnetic brake 21 to turn off, and commands the switch circuit to the electromagnetic clutch 22 to turn on.
0. The rotation of the rotating shaft 20 is caused by the gear 1
Cams 17 and 17' are transmitted to the rotating shaft 19 by 8' and 18 and fixed to one end of the rotating shafts 19 and 20.
rotates synchronously and moves relay lenses 3 and 8 synchronously. No matter where the relay lenses 3, 8 are located outside the stop zone, the cams 17, 1 at maximum
7' enters the stop zone while it completes a little less than one rotation.

When the relay lenses 3 and 8 enter the stop zone, the comparator 34 outputs the "H" level as described above, lights up the display 35, and the microprocessor 36 turns off the electromagnetic clutch 22 and turns off the electromagnetic brake 21. A command is given to turn on the relay lenses 3 and 8, and the relay lenses 3 and 8 stop in the stop section.

In the latter case, after turning on the power switch 38,
The subject is placed in a predetermined position, the objective lens 1 of the refractometer is aligned with the eye E, and the subject is made to look at a fixation target (not shown).

The light emitted from light source 7 is chiyotsuparetakeru 28
The light is intermittent at high speed and condensed by the condenser lens 6, and subjected to refraction by each of the prisms 5a, 5b, 5c to illuminate the slits 4a, 4b, 4c. The light emitted from each slit is converged by a relay lens 3, passes through a light splitter 2, once forms an image of the slit, is converged by an objective lens 1, and enters the eye to be examined. The light beam incident on the subject's eye passes through slits 4a, 4b, 4c and prisms 5a, 5.
b and 5c, the light beams are separated from each other as appropriate and are incident. When each beam of light is converged by the refractive power of the eye itself, each convergence point is formed on the retina or shifted in front or behind it depending on the refractive power, forming either a clear slit image or a blurred image. These images on the retina are scattered and reflected, go backwards, exit the subject's eye, enter the objective lens 1, converge there, then diverge, reflect at the light splitter 2, and then pass through the relay lens 8.
The light is reconverged by the mask 9 and reaches the photodetectors 10a, 10b, 10c. Since the masks 4 and 9 are maintained conjugate, the image on the retina is formed on the surface of the mask 9, and when the slit image is clearly formed on the retina, the slit image on the surface of the mask 9 and each slit 9a are , 9b, 9c match, and the photodetector 10
output is maximum. When the relay lenses 3 and 8 are moved back and forth from this state, the slit image forms images in front and behind the retina, a blurred image is formed on the retina, and a blurred image is focused on the mask 9 surface for light detection. The output of the device 10 decreases. In other words, relay lens 3
and 8, the device is configured so that it can be moved sufficiently back and forth from the position where a clear slit image is formed on the retina with the emmetropic eye, and the device is configured to move in one direction from one end of the movement range, that is, from the above-mentioned stop section to the other end. If the output of the photodetector 10 is made continuous, the output of the photodetector 10 will reach a maximum value at a position corresponding to the refractive power of the eye to be examined. By detecting the position of the relay lens 3 that emits this maximum value, it is possible to know the refractive power of the eye to be examined by setting a relationship of refractive power corresponding to the position of the relay lens.
If the outputs of each photodetector are temporally consistent, the subject's eye does not have astigmatism; if the outputs of each photodetector are temporally shifted, the eye is refracted by each meridian direction. It means that the power is different, and it is known that it is astigmatism.

If the change in refractive power due to astigmatism changes sinusoidally, the refractive power can be expressed as a function of the angle in the meridian direction, and if at least three measured values in the meridian direction are obtained, the microprocessor By performing functional calculation processing in step 36, the spherical diopter, degree of astigmatism, and astigmatic axis angle can be determined.

When performing a measurement, after the display 35 lights up, the examiner turns on the measurement switch 39, the switch circuit to the electromagnetic brake 21 is turned off and the switch to the electromagnetic clutch 22 is turned off by a command from the microprocessor 36. When the circuit is turned on, the rotation of the motor 25 is transmitted to the cams 17 and 17' and the relay lenses 3 and 8 begin to move.

At the same time, the output of the potentiometer 27 is non-linearly corrected, then A/D converted and input to the microprocessor 36, and the photodetectors 10a, 10b,
Each output of 10c is demodulated and amplified, then A/D converted and input to the microprocessor 36, which detects and stores the diopter that produces the maximum value on each meridian of Ra, Rb, and Rc. I'll keep it. When the diopters of the three meridians are stored at a predetermined address, the microprocessor processes these three data using functional calculations to obtain the spherical diopter,
Calculate the astigmatism degree and astigmatism axis angle.

If the diopter of the eye to be examined is within the measurement range of this eye refractometer, the acquisition of measurement data is completed by the time the relay lenses 3 and 8 move a predetermined amount of movement from the stop section and reach the other end. That is, in the eye refractometer according to this embodiment, after the eye to be examined and the objective lens are aligned, the measurement is completed while the relay lens continuously moves in one direction by a predetermined distance from the stop position and reaches the other end. do. If the rotation speed of the motor 25 is set appropriately, the measurement can be completed in a very short time. or,
In a system where the motor 25 is kept rotating by turning on the power switch and the rotation is transmitted by an electromagnetic clutch, if the torque of the motor and clutch is sufficient for the load, the relay lens is immediately turned on after the measurement switch is turned on. starts moving, which is effective in shortening measurement time. Furthermore, when the power switch is turned on for the first time, the position of the relay lens can be adjusted to the stop zone in a very short time, so it can be completed while the examiner is aligning the optical axis of the eye to be examined and the objective lens. Therefore, it does not require any special time.

In this method, the measurement is completed after the relay lens moves a predetermined distance from the stop section in one direction.
If the cams 17 and 17' are continued to rotate, the relay lens will return toward the stop section. When the relay lens reaches the stop zone, the output of the direct-acting potentiometer 27 becomes lower than the output of the reference voltage generator 33, and the display 35 is turned on to calculate the spherical diopter, astigmatism, and astigmatic axis. The degree is digitally displayed on a display (not shown). Further, the electromagnetic clutch 22 is turned off and the electromagnetic brake 21 is turned on according to a command from the microprocessor, and the movable lens 3 is stopped within the stop interval, making it possible to perform the next measurement immediately. The display 35 lights up to inform the examiner that the device is ready for measurement.
When the examiner turns on the measurement switch, the light goes off a moment later to inform the examiner that the measurement is in progress, and when it turns on again, the measurement is complete. This state is maintained until the next time the measurement switch is turned on or the power switch is turned off.

In this system, in order to prevent malfunctions and protect the machine, the microprocessor accepts the measurement start signal from the measurement switch only when the relay lens is located in the stop zone and the indicator is lit. Configure it to prohibit input.

FIG. 4 shows another embodiment, in which the first
Components that are the same as those in the illustrated embodiment are given the same numbers.
1 to 6 are the same members as in the embodiment of FIG. 1, and 7'
is a light emitting diode as a light source, and this light source has the advantage of being able to perform faster and more stable chopping than a lamp. 101 is a total reflection mirror,
It has the effect of bending the optical axes of the detection systems 8 to 10 by 90 degrees and making them parallel to the optical axes of the projection systems 1 to 7'. 1
Reference numeral 11 denotes a member that supports the relay lens 8, and is inscribed inside a cylinder 112 that guides the relay lens 8 in the optical axis direction so as to be able to slide in the optical axis direction. 113 is a member that supports the relay lens 3, and 114 is fixed in parallel to the support member 111 of the relay lens 8 by a connecting member. Reference numeral 115 denotes a connecting member that protrudes from the support member 111 and has a roller 116 fitted at its tip.
Further, the tube 112 has a groove 112a long in the optical axis direction, and the width of the groove is such that the connecting member 115 is lightly fitted to prevent the supporting members 111 and 113 from rotating. A cam gear 117 has a grooved cam 117a on its end face with a groove width that fits into the rollers 116, and has teeth on its outer periphery that engage with the gear 119, and is fixed to the rotating shaft 118. The rotating shaft 118 is supported by a bearing (not shown). Cam gear 1
When the relay lens 17 is rotated by a member described below, the roller 116 is pushed out in the optical axis direction, and the relay lenses 8 and 3 are moved in the optical axis direction. 22 is an electromagnetic clutch, and a large gear 120 is fixed to a driving shaft 22a, and a gear 119 is fixed to a driven shaft 22b. Reference numeral 121 denotes a small gear fixed to the rotating shaft of the motor 25, and the electromagnetic clutch 22 functions to interrupt and interrupt the transmission of the rotation of the motor to the cam gear 117. The gear trains 117 to 121 have a number of teeth configured to reduce the rotation of the motor so that the cam gear 117 reaches a predetermined rotation speed.

Reference numeral 21 denotes an electromagnetic brake, which acts to stop the rotation of the rotating shaft 118.

122 and 123 are disks having fan-shaped notches on the outer periphery, which are fixed to the rotating shaft 118 and combined with the photoelectric switches 124 and 125, and are connected to the cam gear 11.
The output of the photoelectric switch is applied to the microprocessor 36 at TTL level. The disk 122 and the photoelectric switch 124 are provided to detect the stop section of the relay lens, and detect the state where the relay lens 3 is in the section where it has moved about 0.5 mm in the direction of the arrow from the position closest to the mask 4, and the other state. A fan-shaped notch is provided in the disk 122 to allow identification of the state, and an identification signal is input to the microprocessor. Also, disk 123
The photoelectric switch 125 is provided to detect the effective range for inputting refraction measurement data to the microprocessor, and when the relay lens 3 moves in the direction of the arrow from the position closest to the mask 4 and exceeds the stop range. Approximately 0.5mm from the point closest to the light splitter 2
The area excluding about 0.5 mm from both ends of the forward path of the reciprocating movement up to the front is set as an effective area. A fan-shaped notch is provided on the disk 123 for identification, and the identification signal is input to the microprocessor and the counting circuit 133 Perform a reset. In addition to the present embodiment, the means for detecting the stop zone and the effective zone may be a combination of a cam and a micro switch, a combination of a small magnet and a reed switch, or a combination of a small magnet and a Hall element or a magnetic resistance element.

Further, 127 to 130 constitute a photoelectric linear encoder for detecting the amount of movement of the relay lens, 127 is a light source, 128 is a glass scale having a large number of light transmitting slits, and connecting member 12
6 is fixed to the relay lens support member 113 and moves in the optical axis direction in the same manner as the relay lenses 3 and 8 move. 129 is a glass mask having one light transmitting slit; 130 is a light receiving element, the output of which is applied to an amplifier 131; 132 is a waveform shaping circuit, 133 is a counting circuit, which detects the amount of movement of the relay lens by counting the number of pulses;
input to the microprocessor 36; Reference numeral 134 denotes a light source driving circuit, which has a function of blinking the light source 7' at a much higher speed than the moving speed of the relay lens.

With the above configuration, when the power switch 38 is turned on, the motor 25 and each circuit are energized in a predetermined amount according to a command from the microprocessor 36. Next, the output of the photoelectric switch 124 is checked to detect whether or not the relay lens is in the stop zone. is turned on, and the electromagnetic clutch 22 is kept in the off state.

Next, if the relay lens is located outside the stop zone, the electromagnetic brake 21 is turned on by a command from the microprocessor 36, and the electromagnetic clutch 22 is turned on.
Turn off and move the relay lens. When the relay lens 8 enters the stop zone, the output sign of the photoelectric switch 124 is reversed, and the microprocessor commands to turn off the electromagnetic clutch, turn on the electromagnetic brake, stop the relay lens, and turn on the display. let

In the former case, after turning on the power switch 38, the subject is placed in a predetermined position, the objective lens 1 of the refractometer is aligned with the eye E to be inspected, and the measurement is performed by having the subject look at a fixation target (not shown). Turn on switch 39. Upon receiving the input from the measurement switch, the microprocessor 36 instructs the electromagnetic brake 21 to turn off and the electromagnetic clutch 23 to turn on, and also turns on the light source drive circuit 134.
is operated to turn on the light source 7'. The light emitted from the light source 7' is transmitted to the photodetector 1 in the same manner as in the embodiment shown in FIG.
0, and its output is transmitted to amplifiers 40a, 40b, 4
0c, A/D converters 41a, 41b,
Added to 41c.

When the electromagnetic clutch 23 is turned on, the rotation of the motor is transmitted to the cam gear 117, and the relay lenses 3 and 8
begins to move, passes the stop section, the output sign of the photoelectric switch 124 is inverted, and the output sign of the photoelectric switch 125 for detecting the valid section is inverted and input to the microprocessor 36. This sign reversal causes the microprocessor to set the counting circuit,
The amount of movement of the relay lens is counted and input to the microprocessor.

If the transmission slits of the glass scale 128 of the photoelectric linear encoder are carved to correspond to the diopter scale, the microprocessor can convert the input from the counting circuit into a diopter value.

Further, the microprocessor uses the input from the counting circuit as a clock to operate the A/D converters 41a and 41.
b, 41c are operated, and the optical output corresponding to the diopter scale is stored, read out, and compared repeatedly in the same manner as in the embodiment shown in FIG. When the respective outputs reach maximum values, the respective diopter values are stored, input from the A/D converter is prohibited, and data acquisition is completed.

When the relay lens moves further and passes the effective range, the output sign of the photoelectric switch 125 is reversed, and the microprocessor calls up the stored diopter that produced the maximum value of the three meridian lines, and performs functional calculation processing. and calculate the spherical diopter, degree of astigmatism, and astigmatism axis angle. The relay lens moves further and reaches the end point, and when it moves in the opposite direction and reaches the stop section, the photoelectric switch 12 is activated.
The output sign of 4 is reversed, the microprocessor commands the electromagnetic clutch to turn off and the electromagnetic brake to turn on, and the relay lens stops. And display 3
5 is turned on, and the spherical diopter, degree of astigmatism, and astigmatic axis angle are digitally displayed on a display (not shown).

5 and 6 respectively show modified examples of the relay lens position detection section, in which the stop section detection section, the effective section detection section, and the encoder for detecting the position of the relay lens related to diopter are combined into one. This is an example of combining them into one unit.

In FIG. 5, 201 is a light source, 202 is a collimator lens, 203 is a glass scale fixed to a member that supports a relay lens (not shown),
It has light transmitting parts 203a, 203b and a large number of light transmitting slits 203c, and moves in the direction of the arrow as the relay lens moves. 204 is a fixed glass mask with slits 204a, 204b, 204 corresponding to each light transmitting part of the glass scale 203.
It has c. The light that has passed through the light transmitting section 203a and the slit 204a enters the light receiving element 205a, and the light that has passed through the light transmitting section 203b and the slit 204b enters the light receiving element 205b and enters the slit 2.
The light transmitted through the slit 204c and the slit 204c enters the light receiving element 205c.

Here, the system marked with a is a system for detecting a valid section, the system marked with b is a system for detecting a stop section, and the system marked with c is an encoder system. The outputs of the light receiving elements are transmitted through amplifiers 206a and 206a, respectively.
206b and 206c, and the waveform shaper 20
Waveform shaping is performed at 7a, 207b, and 207c. The outputs of the waveform shapers 207a and 207b are input to a flip-flop circuit 208. The sign of the output of the waveform shaper 207b is reversed depending on whether the relay lens is located in the stop section or not. Assuming that the relay lens is now located in the stop zone, when the examiner turns on a measurement switch (not shown) and the relay lens begins to move, the output sign of the waveform shaping circuit 207b will be reversed a little later. At this point, the flip-flop 208 outputs the start of the effective section, and when the relay lens moves further and the light transmitted through the light transmitting part 203a of the glass scale and the slit 204a of the glass mask is blocked, the waveform shaper is output. The output sign of 207a is inverted and flip-flop 208 outputs the end of the valid period.

When the relay lens moves further and conversely moves toward the stop section, light enters the light receiving element 205a again, but the flip-flop does not operate due to the inversion of the output sign of the waveform shaper 207a. In other words, the flip-flop is operated so as to output an effective section only on the outward journey when the relay lens moves back and forth from the stop position.

Next, the output of the waveform shaper 207c is
9 and outputs the digitized movement amount of the relay lens. The output of the flip-flop 208 is used as a detection signal of the valid section and also as a waveform shaper 2.
The output of 07b is input to the microprocessor as a detection signal for the stop section, and the output of the counting circuit 209 is input to the microprocessor as a relay lens movement amount signal.
The refractometer is controlled as in the embodiment of FIG. If this modification is incorporated into the embodiment shown in FIG. 4, the linear encoder section will be replaced with this modification, and the discs 122, 123 and photoelectric switch 12 for detecting the stop section and effective section of the relay lens will be replaced.
4,125 can be removed.

In FIG. 6, it is assumed that the position detecting section of the relay lens is constituted by a rotary encoder, and 300 is a rotating shaft, and a cam (not shown) for moving the relay lens is fixed at one end. As in FIG. 5, 301 is a light source, and 302 is a collimator lens. 303 is a glass plate fixed to the rotating shaft 300.
The scale has light transmitting parts 303a, 303b and a large number of light transmitting slits 303c, and rotates according to the rotation of the rotation axis. 304 is a fixed glass mask with slits 304a, 304b, 30
4c, and the light receiving elements 305a, 30 are on the back side.
5b and 306c, the outputs of which are each amplified by an amplifier 306, and a waveform shaper 30.
The waveform is shaped in step 7.

Here, the system with the letter a is a system that detects a valid section, the system with a b is a system that detects a stop section, and the system with a letter c is an encoder system. The outputs of the waveform shapers 307a and 307b are input to the microprocessor, and the output of the waveform shaper 307c is counted by a counting circuit 309 and input to the microprocessor. The difference from FIG. 5 is that no flip-flop is required to detect the valid section.

According to the embodiment described above, immediately after the examiner (operator) turns on the measurement switch, the relay lens simply moves from a predetermined end of the movement range toward the other end at high speed in one direction to measure diopter. Because all the data necessary for the test can be obtained, measurements can be completed in a very short time, with less burden on the examinee, and with minimal measurement errors caused by eye accommodation or fixation instability, resulting in highly accurate measurements. Measurement is possible. According to the present invention, the device is precisely prepared and adjusted prior to measurement, which has the effect of enabling accurate and quick measurement.Furthermore, the drive device is powered before measurement. This enables extremely high-speed measurement start-up operations.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a first embodiment of the present invention. FIG. 2 is a plan view showing the slit mask in the embodiment of FIG. 1. FIG. 3 is a plan view showing the detection section in the same embodiment. FIG. 4 is a sectional view showing another embodiment. FIGS. 5 and 6 are diagrams showing modified examples of the relay lens position detection device. In the figure, 3 and 8 are movable relay lenses, 10 is a photodetector, 17 is a cam, 21 is an electromagnetic brake, 22
25 is an electromagnetic clutch, 25 is a motor, 27 is a position detector, 35 is a display, and 36 is a microprocessor.

Claims (1)

[Scope of Claims] 1. An indicator projection system that projects at least three indicators onto the fundus of the eye to be examined, and each indicator image is moved synchronously in the optical axis direction with respect to the fundus of the eye to be examined so that each index image is in a predetermined state. In an automatic eye refractometer that measures the refractive power of the eye to be examined from the amount of movement until An automatic eye refractometer comprising: a driving means for driving the driving means; and a position detecting means for detecting the position of the driving means from a starting end of movement. 2. Outward movement from the movement start end to the other end;
2. The automatic eye refractometer according to claim 1, further comprising cam means for performing return movement from said other end to said movement start end by unidirectional rotation of a drive source. 3. The automatic eye refractometer according to claim 1, further comprising intermittent means for intermittent power from the drive source at the movement start end and stop means for stopping movement of the index projection system.