RU2237425C1 - Device for measuring vision resolution from light flicker frequency - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: device has the first to sixth keys, tumbler switch, the first to eleventh switches, NOT-gate, the first to third monovibrators, trigger, the first and the second mode switches , OR-gate, the first and the second linearly variable voltage oscillators, analog multiplexor, voltage-to-frequency converter, luminous pulses source, second-long pulse oscillator, unit for calculating frequency difference, the first and the second indication units and counter.

EFFECT: high accuracy of measurements.

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Description

The invention relates to medical equipment and is intended to measure the resolution of vision by the frequency of light flicker.

A device for measuring the critical fusion flicker frequency by a is known. S. No. 1007651, characterized in that in order to increase the reliability of determining the degree of human fatigue by measuring the differential threshold of eye sensitivity by flicker frequency, it further comprises an adjustable frequency divider connected to a pulse generator, and sequentially connected to the experimenter button, element And, the second pulse shaper and a second light source, and the second input of the element And is connected to the output of an adjustable frequency divider (A. p. 1333307, class A 61 V 5/16).

In the device in the mode of determining the differential threshold of eye sensitivity by the frequency of light flickers, the test subject compares the flicker frequency of the first light source with the reference flicker frequency of the second light source, changes the frequency of the first source and achieves the equality of the flicker frequencies of both light sources.

A disadvantage of the known device is the inaccuracy of determining the differential threshold of sensitivity of the eye by the frequency of flickering. The device determines the difference between the flicker frequencies of the adjustable and reference light sources with the subjective equality of their frequencies, i.e. not distinguishing between subjects the flicker frequencies of both sources. However, to determine the differential threshold of eye sensitivity by the frequency of light flickers, it is necessary to determine the minimum difference between the presented frequencies, provided that they are distinguished, that is, the threshold for distinguishing the presented frequencies, which is an indicator of the resolution of vision by the frequency of light flickers.

Closest to the technical nature of the present invention is a device for measuring the resolution of vision by the frequency of light flickering, containing a test button, a linearly varying voltage generator, voltage-frequency converter, a light pulse source, a calculator, a block of indicators and a pulse shaper for signal decay, moreover the output of the generator is connected to the input of the voltage-frequency converter, the output of which is connected to the inputs of the light pulse source and the computer, Exit calculator connected to an input of the display unit, the input of the pulse shaper decay signal connected to the output of the test button, and an output - to the input of the calculator, the output of the test button is also connected to the generator input (RF patent №2204933, A 61 B 3/00).

The disadvantage of this device is the low accuracy of measuring the resolution of vision by the frequency of light flickering, since it is determined with a continuous increase or decrease in the initial frequency. Then it is known that the human eye is more sensitive to the perception of a discretely changing frequency (A.S. 1346136 USSR, A 61 V 5/16).

In the present invention, in a device for measuring the resolution of vision by the frequency of light flickers, containing a linearly varying voltage generator, a voltage-frequency converter, a light pulse source, a calculator and a block of indicators, the output of the voltage-frequency converter being connected to the inputs of a light pulse source and a calculator, the output of the calculator is connected to the input of the indicator block, the first to eleventh gates, the element NOT, the first to third one-shots, a trigger, the first and second mode switches, the OR element, the second ramp generator, the analog multiplexer, the second pulse generator, the counter, the second indicator block, the first to sixth keys and the toggle switch, and the outputs of the first and second keys are connected to the inputs of the first and second mode switches, the output of the third key is connected to the first inputs of the first and second valves, the outputs of which are connected respectively to the inputs of the first and second mode switches, the output of the fourth key is connected to the first input the third and fourth gates, the outputs of which are connected respectively to the inputs of the first and second mode switches, the fifth key output is connected to the first inputs of the sixth and seventh valves, the outputs of which are connected respectively to the inputs of the first and second mode switches, the outputs of the first and second mode switches are connected respectively with inputs of the first and second ramp generators, the outputs of which are connected to the information inputs of an analog multiplexer, multipl The analogue expo is connected to the input of the voltage-frequency converter, the output of which is connected to the first input of the eleventh valve, the output of the sixth key is connected to the first input of the fifth valve, the second input of which is connected to the normally open output of the toggle switch, and the output is connected to the trigger enable input, the trigger output is connected with the first inputs of the eighth and ninth gates, the outputs of which are connected to the inputs of the OR element, the output of the OR element is connected to the second input of the calculator, the second output of which is connected to the trigger off input hera, the output of the second pulse generator is connected to the address input of the analog multiplexer, the first input of the tenth valve, the second inputs of the first and third valves, the input of the element NOT and the input of the first one-shot, the second input of the tenth valve is connected to the normally closed output of the toggle switch, and the output to the second input the eleventh valve and with the input of the third one-shot, the output of which is connected to the input of zeroing the counter, the output of the eleventh valve is connected with the counting input of the counter, the output of which is connected to the input of W cerned block indicators output element is coupled to the second inputs of the second and fourth valves and the input of the second monostable, the output of the first monostable multivibrator is connected to the second inputs of the sixth and eighth gates, the output of the second monostable multivibrator is connected to the second inputs of the seventh and ninth valves.

The inventive device due to the introduction of the first to eleventh gates, the element NOT, the first to third one-shots, the trigger, the first and second mode switches, the OR element, the second ramp generator, analog multiplexer, second pulse generator, counter, second indicator block, the first to sixth keys and toggle switch allows you to more accurately measure the resolution of vision by the frequency of light flicker.

Thus, the claimed device differs from the known new properties that determine the receipt of a positive effect.

Figure 1 presents the structural diagram of the inventive device, figure 2 is a timing diagram explaining its operation.

The inventive device contains the first sixth 1-6 keys, toggle switch 7, first to eleventh 8-18 valves, element 19 NOT, first to third 20-22 single vibrators, trigger 23, first 24 and second 25 mode switches, element 26 OR, first 27 and second 28 linearly varying voltage generators, analog 29 multiplexer, voltage-frequency converter 30, light pulse source 31, 32 second pulse generator, calculator 33, first 34 block of indicators, counter 35, second 36 block of indicators.

The first 1 switch is used to set the first 27 and second 28 generators in the mode of linearly increasing voltage generation at a speed corresponding to a change in the frequency at the output of the voltage-frequency converter 30 equal to 1 Hz / s.

The second 2 key is designed to set the first 27 and second 28 generators in the mode of generating a linearly incident voltage at a speed corresponding to a change in frequency at the output of the voltage-frequency converter 30, equal to 1 Hz / s.

The third 3 key is designed to set the first 27 generator in the mode of linearly increasing voltage generation and the second 28 generator in the mode of linearly decreasing voltage generation at a speed corresponding to the change in frequency at the output of the voltage-frequency converter 30 equal to 0.5 Hz / s.

The fourth 4 key is designed to set the first 27 generator in the mode of linearly incident voltage generation and the second 28 generator in the mode of linearly increasing voltage generation at a speed corresponding to a change in frequency at the output of the voltage-frequency converter 30 equal to 0.25 Hz / s.

The fifth 5 key is used to set the first 27 generator to ramp voltage generation mode and the second 28 generator to ramp voltage generation mode at a speed corresponding to a change in frequency at the output of voltage-frequency converter 30 equal to 10 Hz / s.

The sixth 6 key is intended for fixing the measurement results.

The toggle switch 7 is intended for setting the initial frequency setting and measurement modes.

The switches 24-25 modes are designed for switching resistors at the inputs of generators 27-28.

The calculator 33 is designed to calculate the difference AF of the incremental and decrement frequencies of light flickers recorded by the subject.

The purpose of the remaining nodes corresponds to their name.

The mode switches 24-25 are made according to the patent of 2026008 of the Russian Federation, A 61 V 5/16 (node 8).

The linearly varying voltage generator 28 is made similarly to the generator 27. As the linearly varying voltage generators 27-28, a standard integrator is used on the operational amplifier with input resistors switched respectively by switches 24-25 to obtain a different voltage rise rate at the output of the generators 27-28, and by changing the polarity of the input voltage, change the direction of integration (increase or decrease in the output voltage).

The 29 analog multiplexer is made on the K561KP1 microcircuit (S. Biryukov. Use of digital microcircuits of the TTL and CMOS series. - 2nd ed., Eras. - M.: DMK, 2000, Fig. 251. - P.194).

Keys 1-6 are manual switches to two positions for closing and opening electrical control circuits and are made in the form of control buttons.

The remaining nodes are well known.

The device operates as follows. In the initial state, the toggle switch 7 is in the position "Setting the initial frequency", as shown in figure 1. When the power is turned on, the trigger 23 turns off, the counter 35 is reset (chains are not shown), the tenth 17 valve opens, the first 27 and second 28 generators produce the same constant voltage corresponding to a light flicker frequency of 25 Hz, i.e. the average frequency of the accepted visible range of light flickers from 0 to 50 Hz. The same constant voltage from the outputs of the generators 27-28 regardless of the state of the output of the generator 32 second pulses through the multiplexer 29 is supplied to the Converter 30, where it is converted to the frequency that controls the source 31.

The test person closes the keys 1 or 2 and sets the specified initial F _H frequency, relative to which it is necessary to determine the resolution of vision by the frequency of light flicker. When the key 1 is closed, the generators 27-28 through the corresponding switches 24-25 are set to the mode of linearly increasing voltage generation at a given speed, when the key 2 is closed, to the mode of generating linearly incident voltage at the same speed.

The signal of a logical unit with a duration of 1 s from the generator of 32 second pulses through the open tenth 17 valve is fed to the third 22 single vibrator and the eleventh 18 valve. On the leading edge of the pulse from the output of the generator 32, the third 22 single-shot generates a short pulse, which resets the counter 35. The frequency from the output of the converter 30 through the open eleventh 18 valve is supplied to the counter 35, the counting result is output to the second 36 block of indicators. The set predetermined initial F _H frequency controls the source of 31 light pulses (figure 2, the time interval 0-T ₀ ).

The test subject sets the toggle switch 7 to the “Measurement” position, the fifth 12th valve opens, the tenth 17th and eleventh 18th valves close, the status of counter 35 does not change, the value of the set initial F _H frequency is displayed on the second 36 indicator block.

The test person closes the key 3 (figure 2, time T ₀ ). When a logical unit signal at the output of the 32 second pulse generator opens the first 8 valve. The signal from the output of the key 3 through the open first 8 valve and the first 24 switch sets the first 27 generator in the mode of generating a ramp voltage with a given speed. The voltage from the output of the first generator 27 through the multiplexer 29 is supplied to the converter 30, where it is converted to a frequency that controls the source 31. When the logic signal is zero at the output of the 32 second pulse generator, the output of element 19 is NOT set to the signal of the logical unit, the second 9 valve opens. The signal from the output of the key 3 through the open second 9 valve and the second 25 switch sets the second 28 generator in the mode of generating a linearly incident voltage at a given speed. The voltage from the output of the second generator 28 through the multiplexer 29 is supplied to the converter 30, where it is converted to a frequency that controls the source 31 (figure 2, the time interval T ₀ -T ₁ ).

On the time interval T ₀ -T _{1, the} test subject determines the moment when the incremental and decrement frequencies of light flickering presented alternately differ, and opens the key 3 (figure 2, time T ₁ ). The generators 27-28 store at the outputs a constant voltage corresponding to the frequencies F _I1 and F _{D1 of} light flickers, which source 31 is presented to the subject in turn (Fig. 2, the time interval T ₁ -T ₂ ).

The test person closes the key 4 (figure 2, time T ₂ ). When a logical unit signal at the output of the 32 second pulse generator opens, the third 10 valve. The signal from the output of the key 4 through the open third 10 valve and the first 24 switch sets the first 27 generator in the mode of generating a linearly incident voltage with a given speed. The voltage from the output of the first 27 generator through the multiplexer 29 is supplied to the converter 30, where it is converted to a frequency that controls the source 31. When the logic signal is zero at the output of the 32 second pulse generator, the output of element 19 is NOT set to the signal of the logical unit, the fourth 11th valve opens. The signal from the output of the key 4 through the open fourth 11th valve and the second 25th switch sets the second 28 generator in the mode of generating a ramp voltage with a given speed. The voltage from the output of the second generator 28 through the multiplexer 29 is supplied to the converter 30, where it is converted to a frequency that controls the source 31 (figure 2, the time interval T ₂ -T ₃ ).

On the time interval T ₂ -T _{3, the} test subject determines the moment when the incremental and decrement frequencies of light flickering presented alternately do not differ, and opens the key 4 (figure 2, time point T ₃ ). The generators 27-28 store at the outputs a constant voltage corresponding to the frequencies F _I2 and F _{D2 of} light flickers, which source 31 is presented to the subject in turn (figure 2, the time interval T ₃ -T ₄ ).

The test person closes the key 5 (figure 2, time T ₄ ). On the leading edge of the logical unit signal at the output of the 32 second pulse generator, the first 20 one-shot oscillator generates a pulse, during which the signal from the output of the key 5 through the sixth 13th valve and the first 24th switch sets the first 27 generator to the ramp mode. The voltage from the output of the first generator 27 through the multiplexer 29 is supplied to the converter 30, where it is converted to the frequency that controls the source 31. The duration of the pulse generated by the first 20 single-shot corresponds to an increase in the frequency at the output of the converter 30 by 0.1 Hz. When the signal is a logical zero at the output of the 32 second pulse generator, the output of the element 19 is NOT set to a signal of a logical unit. On its leading edge, the second 21 single-shot generates a pulse, during which the signal from the output of the key 5 through the seventh valve 14 and the second 25 switch sets the second 28 generator in the mode of linearly incident voltage generation. The voltage from the output of the second generator 28 through the multiplexer 29 is supplied to the converter 30, where it is converted to a frequency that controls the source 31 (figure 2, the time interval T ₄ -T ₅ ). The duration of the pulse generated by the second 21 single vibrator corresponds to a decrease in the frequency at the output of the converter 30 by 0.1 Hz.

On the time interval T ₄ -T _{5 the} subject determines the moment when the incremental and decrement frequencies of light flickering presented alternately differ, and opens the key 5 (figure 2, time point T ₅ ). The generators 27-28 store at the outputs a constant voltage corresponding to the frequencies F _I3 and F _{D3 of} light flickers, which source 31 is presented to the subject in turn (figure 2, the time interval T ₅ -T ₆ ).

The test subject closes the key 6 for a short time (Fig. 2, point in time T ₆ ), the pulse from the key 6 through the open fifth 12 valve includes a trigger 23, the eighth 15 and the ninth 16 valves open. When a signal of a logical unit at the output of the generator 32, the first 20 one-shot generates a pulse, which through the open eighth gate 15 and the OR element 26 is supplied to the calculator 33, in which the value of the incremental F _FROM the light flicker frequency is written. When a logic zero signal at the output of the generator 32 at the output of the element 19 is NOT set to a signal of a logical unit. On its leading edge, the second 21 single-shot generates a pulse, which through the open ninth 16 gate and the OR element 26 is supplied to the calculator 33, in which the value of the decrement F _F3 frequency of light flickers is recorded.

The calculator 33 determines the difference between the incremental and decrement frequencies ΔF = F _И3 -F _Д3 , equal to the resolution of vision by the frequency of light flickers, and displays the result on the first 34 block of indicators, after which it generates a pulse that turns off trigger 23 and sets the device to its original state (circuit not shown).

Thus, the proposed device allows you to more accurately determine the resolution of vision by the frequency of light flicker.

Claims (1)

A device for measuring the resolution of vision by the frequency of light flickers, containing a linearly varying voltage generator, a voltage-frequency converter, a light pulse source, a computer and an indicator unit, the voltage-frequency converter output being connected to the inputs of a light pulse source and a computer, the output of the computer being connected to the input of the indicator block, characterized in that the first to eleventh gates, the element NOT, the first to third one-shots, a trigger, p first and second mode switches, OR element, second ramp generator, analog multiplexer, second pulse generator, counter, second indicator block, first to sixth switches and toggle switch, the outputs of the first and second switches connected to the inputs of the first and second mode switches, the output of the third key is connected to the first inputs of the first and second valves, the outputs of which are connected respectively to the inputs of the first and second mode switches, the output of the fourth key is connected to the first inputs the third and fourth valves, the outputs of which are connected respectively to the inputs of the first and second mode switches, the output of the fifth key is connected to the first inputs of the sixth and seventh valves, the outputs of which are connected respectively to the inputs of the first and second mode switches, the outputs of the first and second mode switches are connected respectively with the inputs of the first and second generators of linearly varying voltage, the outputs of which are connected to the information inputs of the analog multiplexer, the output is multipl the analog switch is connected to the input of the voltage-frequency converter, the output of which is connected to the first input of the eleventh valve, the output of the sixth key is connected to the first input of the fifth valve, the second input of which is connected to the normally open output of the toggle switch, and the output to the trigger input, the trigger output is connected with the first inputs of the eighth and ninth gates, the outputs of which are connected to the inputs of the OR element, the output of the OR element is connected to the second input of the calculator, the second output of which is connected to the trigger off input Era, the output of the second pulse generator is connected to the address input of the analog multiplexer, the first input of the tenth valve, the second inputs of the first and third valves, the input of the element NOT and the input of the first one-shot, the second input of the tenth valve is connected to the normally closed output of the toggle switch, and the output to the second input the eleventh valve and with the input of the third one-shot, the output of which is connected to the input of zeroing the counter, the output of the eleventh valve is connected with the counting input of the counter, the output of which is connected to the input of the WTO th block indicators output element is coupled to the second inputs of the second and fourth valves and the input of the second monostable, the output of the first monostable multivibrator is connected to the second inputs of the sixth and eighth gates, the output of the second monostable multivibrator is connected to the second inputs of the seventh and ninth valves.

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