SU670944A2 - Automatic corrector for graphic information acoustic readout devices - Google Patents

Description

one

The invention relates to automation and computing, is one of the main blocks of devices for inputting graphic information of acoustic type and is used to compensate for errors in coordinate measurement caused by changes in parameters of a sound-conducting medium.

The closest in technical essence to the proposed technical solution is the well-known auto-corrector 1 for acoustic devices for reading graphic information on the author. St. No. 634314, comprising an electroacoustic transducer acoustically connected to a microphone connected through a series-connected amplifier, a high-pass filter, a pulse selector for duration, an amplitude discriminator, the first logic element I, and a trigger, one of the setup inputs of which is connected to the electro-acoustic converter and the generator output correction cycle, and the output through the second logical element I - to the input of the measuring counter, the outputs of the higher bits of which are connected to the control inputs laziness of a reversible counter output connected via a serially connected digital-analog converter and

a clock pulse generator to one of the inputs of the second logic element I, a prohibition element whose output is connected via a delay element to the counting input of a reversible counter, and the inputs are connected respectively to the trigger output and one of the reversible counter control inputs, in series connected to the first one-shot,

connected to the generator of the correction cycle, n the second one-shot, the output associated with one of the inputs of the first logic element I.

However, this auto-corrector provides

operability of devices for reading graphic information only in a limited range of changes and environmental parameters. This is due to the presence of a digital-to-analog converter in the device.

Such transducers operating with high accuracy over a wide range of temperatures are difficult to manufacture by more than 9–10 bits.

Let it be required to build an acoustic

reading device with sound-conducting air with the following parameters: working field 800X800 mm; air temperature 20 ± 10 ° С; accuracy of measurement of coordinates ± 0.1 mm at any point

tablet.

The reference distance is selected from the conditions / this is LGmax, / this / max.

Outcome FROM a given accuracy of measurement of coordinates, the value of the minimum reference should not exceed n 0, l mm. Then the capacity of the meter should not be less than N units. Prip

nayema L 8192 2Ч Thus, / fl 819.2 mm.

The maximum and minimum clock generator clock frequencies are derived from the ratios

f / 1

f

At max - -}

J min -,

Where S. Smip and Smake is the minimum and maximum speed of sound in the air while changing the parameters of the air within the prescribed limits.

Sms (10 ° C) 337.8-103 mm / s.

Relish (30 ° С) 349.6-103 mm / s.

Substituting these values into expression (1), we get

/ ,, „3378.10 Hz, /„ ax 3496 10 Hz, from where

 / max + / m

 3437.10 Hz

/ SP

The frequency deviation of the clock pulse generator A / in the working temperature range is

А / / „aks-L„ „- Н8.10 Hz, Reverse Counter Capacity

t (-min) / avg)

where Tmake and Tmin is the maximum and minimum sound transit time of the reference distance.

Tmake 2,455-10- s.

, 343-10-3 sec.

Substituting in the expression (2), we get Af 385 units.

We rounded the number M to the nearest larger value of the number 2, we have UI 2. Thus, the digital-to-analog converter must be nine-bit. But at the same time, the auto-corrector, which is a system of automatic adjustment of the frequency of the clock generator, is unstable. For stable operation of the auto-corrector, as shown by calculations and practical research, the number M must be taken with a margin of 2-4.

Then the capacity of the reversible counter tf.-Mxl -2 units, i.e. the digital-to-analogue converter should have 10-11) arcs. In this case, the auto-corrector ensures the operability of the device only in the temperature range of ± 10 ° С.

It can be seen from the above calculation that it is not possible to create graphic information reading devices operating in a wider range of temperatures, since 10-11 bits for a digital-to-analog converter is the limit. It should be noted that the calculation did not take into account the effect of other parameters (pressure, humidity, air composition xa) on the speed of sound in air.

The purpose of the invention is to improve the accuracy and expand the temperature range of the device.

This goal is achieved in the auto-corrector by introducing a switch, the inputs of which are connected to the output and control inputs of the reversible counter, and the outputs to the additional inputs of the clock generator.

An additional difference of the proposed auto-corrector is that in it the switch contains serially connected control reversible counter, decoder and keys, the outputs of which are connected to the outputs of the switch, inputs connected to the inputs of the control reversible counter. FIG. 1 shows functional

autocorrector scheme; in fig. 2 is an electronic switch circuit, one embodiment.

The auto-corrector (Fig. 1) contains an electro-acoustic transducer 1, a microphone 2, an amplifier 3, a high-pass filter 4, a pulse selector 5 for duration, an adaptive amplitude discriminator 6, a trigger 7, a correction cycle generator 8, a logical element And 9, a counter

10, the logical element And the prohibition, the element 12 delay, reversible counter 13, digital-to-analog converter 14, the generator 15 clock pulses, one-shot 16, 17, element And 18 and the switch 19.

Switch 19 (FIG. 2) contains a control reversing counter 20, a decoder 21 per ton outputs, and t electronic switches 22.

The electroacoustic transducer 1 is located in the working area of the graphic information reader or in its immediate vicinity. Microphone 2 is fixed at a fixed distance from converter 1, acoustically coupled to it and connected to a conversion channel consisting of a series-connected amplifier 3, a high-pass filter 4, a duration selector 5, an amplitude discriminator 6, a logic element AND 18, the second input through the single vibrators 16, 17 connected to the output of the generator 8, the trigger 7, another installation input connected to the output of the generator 8 and the input of the electro-acoustic transducer 1, logic element 9 and the counter 10. Outputs starschego discharge counter 10 are connected to the control inputs of the reversible counter

13, the bit outputs of which are connected via serially connected digital-to-analog converter 14 and a clock pulse generator 15 to one of the inputs of the AND 9 logic element. The output ban 11 element is connected via a delay element 12 to the counting input of the reversing counter 13, and the inputs are respectively to the trigger output 7 and one of the control inputs of the reversible counter 13. The control reversing counter 20 of the counting input is connected to the output of the reversing counter 13, and the control inputs are connected to the control inputs of this counter . The bit outputs of the counter 20 are connected to the keys 22 through the decoder 21.

The auto-corrector works as follows.

At the moment of switching on the equipment, the oscillator 8 correction cycle starts functioning in the self-oscillating mode, which periodically excites the electroacoustic transducer 1. The repetition cycle of the correction cycle is selected longer than the sound wave travel time from the electroacoustic transducer 1 to the microphone 2 (distance / fl). At the beginning of each cycle, a pulse from the output of the generator 8 is fed to an electro-acoustic transducer 1, a trigger 7 and a one-shot 16. In this case, the transducer 1 emits a short sound pulse, the trigger 7 is set to one and opens a logic element AND 9 that allows the flow of clock pulses from the generator 15 into the counter 10. The single-oscillator 16 generates a pulse, which, after a time close to the time the sound wave travels away / away, with its decay (back front) starts the one-oscillator 17, which forms and pulse, allowing the passage of the information signal on the trigger 7.

At the moment when the acoustic impulse of the transducer 1 reaches the microphone 2 (this occurs before the next cycle begins), a signal is generated at its output, a post-paupia through the amplifier 3, a high-pass filter 4, a selector 5 of pulses in duration, an amplitude discriminator 6 and a logical element 18, which was opened by the one-shot 17, to the input of trigger 7. The trigger 7 returns to the initial state, the flow of clock pulses to the counter 10 through the logic element 9 stops.

Since in the auto-corrector the distance between the electro-acoustic transducer 1 and microphone 2 is chosen equal to 2P minimum units of measurement, where p is the counter size of the counter 10, and the parameters of the medium may differ from the normal.

10, may be greater than 2, less than or equal to him. Accordingly, the transition of the trigger of the higher bit of the counter 10 to the single state occurs earlier than the signal pulse at the output of microphone 2 (the counter overflows), either does not occur at all (the counter is not filled) or occurs simultaneously with the appearance of the signal pulse (the counter

full).

The trigger of the high bit of the counter 10 performs the function of controlling the reversing counter 13, so in the first and third cases the reversing counter 13 is set to the subtract mode in the first and third cases, and to the add mode in the second case. In this case, in the first case, the signal pulse subtracts one from the contents of the reversible counter 13, and in the second case adds it. Since in the third case, the number of pulses arriving at counter 10 is 2, the moment when the high-order trigger switches to one state coincides with the moment of arrival of the signal pulse from microphone 2 and the contents of the reversing counter 13 do not change (the "overflow emulation originating from moment of transition trigger older bit

in one state, prohibits the passage of a signal pulse to the input of the reversible counter).

Thus, if during the passage of sound from the electroacoustic transducer 1 to microphone 2, the number of pulses entering the counter 10 is greater than 2, the code of the reversible counter 13 decreases by one unit, and if the number is less than 2, the code of the reversible counter increases by one unit. A change in the number of the reversible counter 13 leads to a change in the voltage at the output of a digital-analogue converter, 14, connected to one control} input of the generator 15, the frequency of which changes in this case.

This process repeats each correction cycle until then. until the oscillator frequency of 15 clocks is set such that the measured distance will be ravio. Then the impulse generated at the moment of transition of the trigger of the highest bit of the counter 10 to the unit

the state appears simultaneously with the signal pulse at the output of microphone 2 and prohibits its passage through the logic and inhibit elements and the delay element 12 into the reversible counter 13. in which the previous code remains.

Each cycle of checking the correspondence of the measured distance to the number 2P is repeated, and when the parameters of the air medium change, the generator frequency of the 15 clock pulses changes accordingly.

If the environment changes beyond the working range of the auto-corrector, the reversing counter 13 will overflow and a unit will enter the control reversing counter 20 of the electronic switch 19, and one of the outputs of the decoder 21 will have one of the electronic keys 22. at the time of the master circuit of the generator 15 clock pulse. They may, for example, vary (switch) the inductance or capacitance of the oscillator circuit. When one of the keys is turned on, the average frequency of the generator changes by about half the working range of the auto-corrector. The balance in the self-tuning system is temporarily disrupted and the contents of the reversible counter 13 is gradually reduced to about half its capacity. In the system of auto-tuning again comes the balance. The next switching of the operating range of the device will occur only when a change in the environmental parameters will either cause the counter 13 to overflow or to reset it.

Thus, the switch 19 performs the role of an automatic

range switch. It makes the auto-corrector workable for any range of changes in the speed of sound in the environment.

Claims (2)

1. Autocorrector for acoustic devices for reading graphic information on the author. St. No. 634314, characterized in that, in order to increase the accuracy and expand the temperature range of the device, a switch is introduced into it, the inputs of which are connected to the output and control inputs of the reversible counter, and the outputs to the additional inputs of the clock generator. 2. The autocorrector according to claim 1, which is also distinguished by the fact that in it the switchboard contains a series-connected controlling reversible counter, a decoder and keys, the outputs of which are connected to the outputs of the switch, the inputs of which are connected to the inputs of the controlling reversible counter. Sources of information taken into account in the examination 1. Copyright certificate № 63431 cl. G 06K 11/00, 1976. FIG. 2