RU2301623C1 - Device for investigating parameteres of inertia of human vision system - Google Patents

Abstract

FIELD: medical equipment.

SUBSTANCE: device has second pulse generator, millisecond pulse generator, first to fourth single-pulse vibrators, first OR gate, reversible counter, time interval former, point light source, indication unit, second OR gate, ten pulse series generator, five pulse series generator, first switch for increasing pulse duration for 1 ms and third switch to increase pulse duration for 5 ms. Device allows changing pulse duration with 1 ms pitch.

EFFECT: improved precision of measurement of time of excitation of human vision analyzer.

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Description

The invention relates to medical equipment and is intended to study the parameters of inertia of the human visual system.

A device for experimental determination of the time of inertia of the visual system containing a pendulum that sets the exposure time of the brand and a set of contrast filters [1]. Using this device, the threshold contrast e is measured for an object during stationary observation, then, at different contrasts K _p created by a given set of filters, the effective contrast K _{e is} brought to the threshold of visibility by selecting the exposure time t defined by the swing amplitude of the pendulum. For the time of inertia of the visual system, the effective time for maintaining the visual impression is taken and at an exposure time of t <0.01, it is determined by the formula:

q = K _p t / e.

The disadvantages of this device are its complexity, the use of the mechanical principle of setting the exposure time, which reduces the accuracy of determining the time of inertia.

A device for studying the throughput of a human visual analyzer based on a small PROMIN-M digital computer, including a digital display, its control units, delay device (PP9-2m), analysis units for receiving the accuracy of a digital signal and a memory unit [2]. As test signals use the numbers shown on digital lamps IN-1 on the electronic computer every 7 seconds. The display shows the first number from the digital array with the exposure time set before the experiment, after which an erasing image appears on the display. The test subject recognizes each number and types it on the keyboard. The dispatcher program compares this number with the subject typed on the keyboard. The error and exposure time at which it was made is recorded.

Recognition time, that is, the time required for image recognition, depends on the inertia parameters of the visual system and is determined by the time of perception of visual information [3, 4].

The disadvantage of this device is its complexity and the long duration of the experiment, which leads to fatigue of the visual system and a decrease in the accuracy of measurements.

The closest in technical essence to the present invention is a device for studying the inertia parameters of the human visual system, containing a second pulse generator, a millisecond pulse generator, a first one-shot, a second one-shot with an adjustable pulse duration, a third one-shot, an AND element, an OR element, a counter, a control panel , a light source and an indication unit, wherein the output of the AND element is connected to the first input of the counter, the output of which is connected to the first input of the indication unit , the first output of the control panel is connected to the first input of the light source, the output of the first one-shot is connected to the second input of the counter, the second input of the display unit is connected to the second output of the control panel, the output of the millisecond pulse generator is connected to the first input of the element And, the output of the second pulse generator is connected to the input the first one-shot, the output of which is connected to the first input of the OR element and to the first input of the second one-shot with an adjustable pulse duration, the output of which is connected to the second input ohm of the AND element and with the input of the third one-shot, the output of which is connected to the second input of the OR element, the output of which is connected with the second input of the light source, the third output of the control panel is connected to the second input of the second one-shot with an adjustable pulse duration [5].

It was experimentally established that the disadvantage of this device is the low accuracy of measuring the inertia parameters of the human visual system, due to the impossibility of changing the pulse duration at the output of the second one-shot in 1 ms increments. The minimum step for changing the pulse duration is limited by the resolution of the potentiometer of the control panel, that is, the smallest change in the angle of rotation of the movable system of the potentiometer, at which the change in resistance can be distinguishable [6].

The proposed device allows you to change the pulse duration in increments of 1 ms, thereby increasing the accuracy of determining the time of excitation of the human visual analyzer, eliminating the risk of damage to the retina by the high intensity of the applied light pulses.

In the present invention, in a device for studying the inertia parameters of the human visual system, comprising a second pulse generator, a millisecond pulse generator, a first one-shot, a second one-shot, a third one-shot, OR element, counter, light source and display unit, the output of the counter connected to the input of the display unit , the output of the second pulse generator is connected to the input of the first one-shot, the output of which is connected to the first input of the OR element and to the input of the second one-shot, the output the third one-shot is connected to the second input of the OR element, the output of which is connected to the input of the light source, a time interval shaper, a series of ten pulses, a series of five pulses, a fourth one-shot, a second OR, the first, second and third keys, an output are additionally introduced the first key is connected to the input of the fourth one-shot, the output of which is connected to the first input of the second OR element, the output of the second key is connected to the input of a series of ten pulses, the output of which is connected about the second input of the second OR element, the output of which is connected to the direct counter input of the counter, the output of which is also connected to the parallel load inputs of the time interval shaper, the third key output is connected to the input of a series of five pulses, the output of which is connected to the counter countdown input, the output the second one-shot is connected to the start input of the time interval shaper, the clock input of which is connected to the output of the millisecond pulse generator, and the output to the input of the third one-shot ora, and the counter is made reversible, and the second one-shot - with a fixed pulse duration.

The inventive device due to the introduction of a time interval shaper, generators of five and ten pulses, a second OR element, a fourth one-shot, the first key to increase the pulse duration by 1 ms, the second key to increase the pulse duration by 10 ms and the third key to reduce the pulse duration by 5 ms allows you to:

- increase the accuracy of determining the time of inertia of the human visual system due to the possibility of changing the pulse duration in increments of 1 ms;

- determine the time of inertia of the human visual system, eliminating the risk of damage to the retina by the high intensity of the presented light pulses.

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

Figure 1 presents a structural diagram of the inventive device, figure 2 is a timing chart of its operation, figure 3 is a timing chart of the duration of the inter-pulse interval between light pulses in a pair when determining the time of inertia of the human visual system.

Figure 4 presents the time diagrams of two light pulses of duration τ _and > τ ₁ separated by an interpulse interval, and the visual sensations caused by them, indicating the time of visual sensation τ ₁ and recovery time τ ₂ , where:

- Fig. 4a is a timing diagram of two light pulses separated by an interpulse interval t of the _mission causing a visual sensation of impulse separation;

- figb - time diagram of visual sensation for two light pulses shown in figa;

- figv is a timing diagram of two light pulses separated by a threshold interpulse interval t _then causing visual sensation of one light pulse. With the duration of the inter-pulse interval t _then between two light pulses, a subjective sensation is achieved of the fusion of two light pulses in a pair into one;

- fig.4g - time diagram of visual sensation for two light pulses shown in figv;

- τ ₁ - the time of visual sensation - the time between the moment of exposure of light to the retina and the moment of occurrence of the corresponding visual sensation [7, 8];

- τ ₂ - recovery time - the time between the moment of termination of the effect of light on the retina and the moment the corresponding visual sensation disappears [7, 8].

The inventive device contains a generator of 1 second pulses, a generator of 2 millisecond pulses, the first and fourth 3-6 single vibrators, the first element 7 OR, a counter counter 8, a shaper 9 of the time interval, a point light source 10, an indication unit 11, a second element 12 OR, a generator 13 series of ten pulses, a generator of 14 series of five pulses, the first key 15 to increase the pulse duration by 1 ms, the second key 16 to increase the pulse duration by 10 ms and the third key 17 to reduce the pulse duration by 5 ms.

The generator of 1 second pulses is designed to generate a sequence of pulses with a frequency of 1 Hz, providing a given repetition time of dual test pulses, and can be performed according to the known scheme.

The generator of 2 millisecond pulses is designed to generate a sequence of counting pulses with a frequency of 1 kHz, providing a measurement accuracy of 1 ms, and can be performed according to the known scheme.

The first 3 and third 5 single vibrators are designed to generate dual test pulses with a duration of 50 ms, the second 4 single vibrator is the start pulse of the required duration for the shaper 9 time interval, the fourth 6 single vibrator is used to eliminate the “ringing” of the contacts of the first key 13 and generate a short pulse. Single vibrators 3-6 can be performed, for example, using the K155AG1 microcircuit, which can be triggered both on the leading and trailing edges of the incoming pulses, according to the scheme in Fig.4.20, p.216 [9].

The counter 8 is made reversible.

The time interval shaper 9 is intended for the formation of an inter-pulse interval between two pulses in a pair with an accuracy of 1 ms and can be performed, for example, according to the scheme in Fig. 7.48a, p.265 [10].

The light source 10 is intended for the presentation of light pulses and is made point, for example, on an LED type ALS307EM.

The indicators in the display unit 11 are designed to display the value of the excitation time and can be performed, for example, on indicators of the type ALS333A.

A 13-series generator of ten pulses and a 14-series generator of five pulses can be performed, for example, similarly to generators 7 and 8 (a.s. 1309062 USSR) [11].

The remaining functional units of the structural diagram of the device are well known.

The device operates as follows. When the power is turned on, the counter 8 is reset, the circuit of the shaper 9 of the time interval and the circuit of the generator 13 of a series of ten pulses and the generator 14 of a series of five pulses are set to the initial state (circuits not shown), generator 1 generates second pulses (Fig. 2a), generator 2 - millisecond pulses. The pulses from the output of the generator 1 are fed to the input of the first 3 one-shot, generating on the leading edge of each pulse the first pulse with a duration of 50 ms (Fig.2b), which through the OR element 7 is supplied to the light source 10 (Fig.2e) and triggers the second 4 a single vibrator generating a pulse of duration necessary to start the shaper 9 of the time interval (pigv).

At the first stage (Fig. 3, the time interval T ₀ -T ₁ ), the test subject presses the key 16, the generator 13 generates a pack of ten pulses, which, through the OR circuit 12, arrive at the counter 8, are summed up, the counting result is sent to the time interval shaper 9, and displayed in block 11 of the display. Millisecond pulses are received from the generator 2 to the shaper 9 of the time interval, a pulse of 10 ms duration is generated at the inverse output of the shaper 9 (Fig. through the element 7 OR enters the light source 10 (Fig.2E). As a result, the test subject is presented with a sequence of pair light pulses of duration equal to 50 ms, separated by an interpulse interval of 10 ms, repeated through a time interval of 1 s. Next, the subject presses the key 16 the required number of times until he determines the moment of subjective sensation of the separation of the two light pulses in a pair (figure 3, time point T ₁ ).

In the second stage (figure 3, the time interval T ₁ -T ₂ ), the test subject presses the key 17, the generator 14 generates a pack of five pulses that are received on the counter 8, are subtracted, the counting result is transmitted to the shaper 9 of the time interval and is displayed in block 11 indication. Similarly to the previous one, an impulse shorter by 5 ms is generated at the inverted output of the shaper 9, a third 5 one-shot is launched at its trailing edge, generating a second pulse of 50 ms duration, which is transmitted to the light source 10 through the OR element 7. Next, the subject presses the key 17 the required number of times until he determines the moment of subjective sensation of the merger of two light pulses in a pair into one (Fig.3, time T ₂ ).

At the third stage (Fig. 3, the time interval T ₂ -T ₃ ), the test subject presses the key 15, the one-shot 6 generates a pulse, which, through the OR circuit 12, arrives at the counter 8, is summed up, the counting result is transmitted to the time interval shaper 9 and displayed in the block 11 indications. Similarly to the previous one, an impulse longer than 1 ms in duration is generated at the inverse output of the former 9, a third 5 one-shot is launched at its trailing edge, generating a second impulse of 50 ms in duration, which is transmitted to the light source 10 through the OR element 7. Next, the subject presses the key 15 the required number of times until he determines the moment of subjective sensation of the separation of two light pulses in a pair (figure 3, time point T ₃ ).

The time of inertia of the human visual system is taken equal to the value of the pulse duration at the output of the shaper 9 at the time of the subjective sensation of the separation of two light pulses in a pair, which is displayed on the indicators of the display unit 12 in ms.

When presenting the subject with two light pulses separated by an interpulse interval t _mission > t _then (Fig. 4a), he has a sensation of distinguishing between two light pulses (Fig. 4b). With a decrease in the duration of the interpulse interval t of the _mission between two light pulses to a value of t _mission = t _then (Fig. 4c), there is a subjective sensation of the fusion of two light pulses into one (Fig. 4d). The maximum duration of the interpulse interval t _mission = t _then between two light pulses, at which a subjective sensation of separation of two light pulses in a pair is achieved, is determined by the inertia parameters of the human visual system (figv, d):

t _then = τ ₂ -τ ₁ .

Since τ ₂ ≫τ ₁ [12, 13], the inertia of the human visual system is the recovery time τ ₂ [14]:

It is known that visual information is processed by time quanta with an alpha rhythm frequency of 8–13 Hz [15, 16], which corresponds to a period of 75–125 ms; therefore, the duration of each of the double test pulses was chosen equal to 50 ms.

The repetition period of dual test pulses is selected from the condition of eliminating the influence of the masking effect, which consists in impairing the perception of the first time light pulse due to the presentation of the second pulse in the immediate spatial and temporal proximity to the first. It is shown that there is not only a reverse effect, but also direct masking, in which the first light pulse affects the quality of perception of the second [17]. At an interpulse interval of 500 ms, masking effects are absent or weakly expressed [18]. To eliminate the masking effect, a sequence of pairs of light pulses is presented at a constant time interval of 1 s.

Thus, the proposed device allows to increase the accuracy of determining the time of inertia of the human visual system due to the possibility of changing the pulse duration in 1 ms steps, to determine the time of excitation of the human visual analyzer, eliminating the risk of damage to the retina by the high intensity of the applied light pulses.

Literature

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Claims (1)

A device for studying the inertia parameters of the human visual system, containing a second pulse generator, a millisecond pulse generator, a first one-shot, a second one-shot, a third one-shot, an OR element, a counter, a light source and an indication unit, the output of the counter connected to the input of the display unit, the output of the second generator pulses connected to the input of the first one-shot, the output of which is connected to the first input of the OR element and to the input of the second one-shot, the output of the third one-shot nen with the second input of the OR element, the output of which is connected to the input of the light source, characterized in that it additionally includes a time interval shaper, a series of ten pulses generator, a series of five pulses, a fourth one-shot, a second OR element, the first, second and the third key, the output of the first key is connected to the input of the fourth one-shot, the output of which is connected to the first input of the second OR element, the output of the second key is connected to the input of a generator of a series of ten pulses, the output of which is connected to the second input of the second OR element, the output of which is connected to the input of the direct count of the counter, the output of which is also connected to the inputs of the parallel load of the time interval shaper, the output of the third key is connected to the input of a generator of a series of five pulses, the output of which is connected to the input of the countdown of the counter, the output of the second a single vibrator is connected to the start input of the time interval shaper, the sync pulse input of which is connected to the output of the millisecond pulse generator, and the output to the input of the third one-vibrator RA, and the counter is made reversible, and the second one-shot - with a fixed pulse duration.

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