RU2026008C1 - Device for testing critical frequency of merging of flickerings - Google Patents

Abstract

FIELD: medical equipment. SUBSTANCE: device for measuring critical frequency of flickering merging has button 1 of tested person, shifting register 2, the third to the first triggers 3-5, the first and the second one-shot multivibrators 6, 7, mode switch 8, linearly changing voltage generator 9, voltage-to-frequency converter 10, light pulse former 11, OR gate 12, calculator 13, indicator unit 14, comparator 15 and error indicator 16. Device permits to calculate changes in frequency during period of time beginning from the moment when critical frequency of light flickerings is achieved till moment when person under test presses the button. This time interval depends on time of reaction of person under test and on his other psychophysiological parameters. EFFECT: improved precision; improved reliability. 2 dwg

Description

 The invention relates to medical equipment, namely to devices for determining the degree of human fatigue and diagnostic studies.

 The aim of the invention is to increase the reliability of the results of the study by determining the change in frequency over a period of time from the moment the critical frequency of the flicker fusion is reached until the button is pressed.

 In FIG. 1 shows a block diagram of a device; in FIG. 2 is a timing diagram of its operation.

 The device contains a test button 1, shift register 2, first 3, second 4 and third 5 triggers, first 6 and second 7 standby multivibrators, 8 mode switch, 9 ramp generator 9, voltage-frequency converter 10, 11 light pulse source , OR element 12, calculator 13, indicator block 14, comparator 15 and failure indicator 16.

 Triggers 3-5 are standard R-S triggers. Only one trigger can be on at a time.

 As the generator 9 of the ramp voltage, a standard integrator is used on the operational amplifier with input resistors switched by switch 8 to obtain a different rate of voltage rise at the output of the generator 9, and by changing the polarity of the input voltage, change the direction of integration (rise or fall of the output voltage).

 The calculator 13 determines the difference between the two frequencies of light flicker recorded by the subject.

 The comparator 15 generates a signal when the input voltage decreases or exceeds relative to the values corresponding to the minimum and maximum critical frequencies of light flicker equal to 20 and 50 Hz, respectively.

The device operates as follows. When the power is turned on, triggers 3-5 are turned off, code 1000 is written to register 2 (circuits not shown), generator 9 outputs a constant voltage to converter 10 corresponding to the initial frequency F _{1 of} light oscillations. The converter 10 converts this voltage to a frequency that controls the source 11 (time interval O - T ₁ ).

The test subject presses button 1 (time point T ₁ ). The pulse from button 1 shifts the state of register 2 by one bit to the right, the signal from the first output of register 2 turns on trigger 3, which, through switch 8, sets generator 9 to the mode of generating a slowly varying ramp voltage with a slope of S ₁ . Converter 10 converts this voltage into a proportionally changing frequency, which source 11 is converted into light pulses presented to the subject (time interval T ₁ - T ₂ ).

On the time interval T ₁ - T _{2 the} subject determines the moment of fusion of light flickers, in which he presses button 1 (time point T ₂ , frequency F ₂ ). In this case, the state of register 2 is again shifted by one bit to the right. The signal from the second output of register 2 turns off trigger 3 and turns on the multivibrator 6. Generator 9 stores at the output a constant voltage corresponding to frequency F ₂ . The output of the multivibrator 6 pulse through the element OR 12 is supplied to the computer 13, which records the frequency value F ₂ . The time interval T ₂ - T ₃ is determined by the duration of the pulse generated by the multivibrator 6. At time T _{3, the} multivibrator 6 is turned off and turns on the multivibrator 7 and trigger 4, the latter through switch 8 sets the generator 9 to the mode of generation of rapidly changing ramp voltage with slope S ₂ , while the frequency increases by a fixed amount equal to, for example, 5 Hz. The time interval T ₃ - T ₄ is determined by the duration of the pulse generated by the multivibrator 7. At time T _{4, the} multivibrator 7 is turned off and the trigger 4 turns off the trigger 4 and turns on the trigger 5, the latter through switch 8 sets the generator 9 to the mode of slowly varying linearly decreasing voltage generation with a slope S ₁ , transformed in a circuit, the generator 9 - the converter 10 - the source 11 into light pulses (time interval T ₄ - T ₅ ).

At the moment of flicker of light flickers (time instant T ₅ , frequency F ₃ ), the test subject presses button 1, the state of register 2 is again shifted by one digit to the right, the signal from its third output turns off trigger 5, generator 9 stores a constant voltage corresponding to frequency F at the output ₃ . At the same time, the signal from the third output of register 2 through the OR element 12 is supplied to the calculator 13, in which the frequency value F _{3 is} written. The calculator 13 determines the frequency difference F ₂ and F ₃ and the result is displayed on the indicator block 14, after which it generates a pulse that sets the device to its original state (circuits not shown).

In the case when the subject misses the moment of merging light flickers at time intervals T ₁ - T ₂ or T ₄ - T ₅ , further research and the comparator 15 set to the minimum and maximum values of the critical frequencies of the merger of light flickers of a person lose their meaning 16 failure and brings the device to its original state (circuit not shown).

 Thus, the device allows to increase the reliability of the research results, to determine the frequency change over a period of time from the moment the critical fusion frequency of light flickers is reached until the button is pressed by the test subject, which is a diagnostic sign that allows him to be identified with the degree of human fatigue.

Claims (1)

 DEVICE FOR STUDYING THE CRITICAL FREQUENCY OF FUSION FUSION, containing a test button, first, second and third triggers, first and second waiting multivibrators, a mode switch, a ramp generator, a voltage-frequency converter, a light pulse source, a comparator and a failure indicator, and the generator output connected to the inputs of the comparator and the voltage-frequency converter, the outputs of which are connected respectively to the inputs of the failure indicator and the source of light pulses, the outputs of the of the second, third and third triggers are connected through the mode switch to the input of the generator, the output of the first standby multivibrator is connected to the first input of the second trigger and the input of the second standby multivibrator, the output of which is connected to the second inputs of the second and third triggers, characterized in that, in order to increase the reliability the results of the study by determining the frequency change over a period of time from the moment the critical flicker fusion frequency is reached until the subjects are pressed the button, a shift is entered register, OR element, calculator and indicator block, the test button output being connected to the shift register input, the first output of which is connected to the first input of the first trigger, the second output to the second input of the second trigger and the input of the first multivibrator, the third output to the first the input of the OR element and the third trigger, the second input of the OR element is connected to the output of the first standby multivibrator, and the output to the first input of the calculator, the second input of which is connected to the output of the voltage-frequency converter, and the output is with the input of the indicator block.

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