RU2296946C1 - Device for measuring thickness of transparent material - Google Patents

Abstract

FIELD: measuring equipment engineering.

SUBSTANCE: device contains light source, photo-electric transformer, signals processing block, indicator, which are located in body and connected to direct voltage source. signals processing block is made in form of first, second and third delay elements, first, second, third, fourth, fifth and sixth AND circuit, first, second OR circuits, first, second, third, fourth, fifth, sixth counters, first, second and third triggers, generator, transformer of direct code to auxiliary code, division block, permanent memorizing device and register.

EFFECT: decreased error of measurement.

3 cl, 6 dwg

Description

The inventive device relates to the field of linear measurements performed using optical devices, for example, for measuring transparent materials such as glass.

Known optical measuring devices of the company MSC, are given in the specialized newsletter "Glass containers" No. 5, 2004, pp. 8 ... 11 [1], using the measurement of the difference in the path of laser beams reflected from the outer and inner walls of the product. These are complex and expensive systems.

It is known such a device for measuring the wall thickness of a transparent body, described in A.S. No. 422947, M. Cl. G 01 B 11/06, from 04.09.74 [2], adopted as a prototype. This device contains a light source with an optical system, a scanner, i.e. a developing photoelectric converter, a signal processing unit in the form of a generator, transformer, meter, integrator and measuring indicator device. This device is accompanied by an error due to the fact that when measuring the distance between the reflected rays it is difficult to determine the axis of the rays, since their images are blurred and differ in size for the images from the far and near walls.

The proposed device allows to reduce this error due to the fact that the distances between the axes, which are proportional to the corresponding time intervals during the time sweep, are found as the half-sum of the intervals between the leading and trailing edges of the electrical pulses, which display the image of the beam reflected from the outer and inner walls at the output of the photoelectric converter light source. To do this, in a known device containing a light source, an indicator, a power source, a photoelectric converter and a signal processing unit connected to the converter via direct and inverse outputs of horizontal and frame synchronization, as well as information output, the signal processing unit is made in the form of the first , the second and third delay elements, the first, second, third, fourth, fifth, sixth counters, the first, second, third triggers, the first, second, third, fourth, p and sixth AND circuits coincidence, the first and second OR circuits, the generator, the block division, code converter extra register unit and a read only memory (ROM).

In this case, the inputs of the first and second delay elements are combined with the inputs of the “0” setting of the third and fourth counters and with a direct output of horizontal synchronization, and their outputs are connected respectively to the first and second inputs of the first circuit AND, its third input is connected to the information output of the photoelectric converter , and the output is with the input of the account on the positive front of the first counter and with the input of the account on the negative front of the second counter. Moreover, the resolution enable inputs of the first and second counters are connected respectively to the positive and zero power buses.

The inverse output of horizontal synchronization is connected to the inputs of the installation in "0" of the first and second counters, as well as the first and second triggers.

The outputs of the first bits of the first and second counters are connected to the first inputs of the fourth and fifth AND circuits, respectively, and the outputs of the second bits are connected to the first inputs of the second and third AND circuits, respectively, and the first and second inputs of the first OR circuit. The output of the generator is connected to the second inputs of the second, third, fourth, fifth and sixth circuits I.

The third inputs of the second and third circuits AND are connected respectively with the inverse outputs of the first and second triggers. The fourth input of the third circuit And is connected to the direct output of the first trigger, the first input of the sixth circuit And is combined with the output of the third delay element, the input of which is connected to the direct output of frame synchronization, with the control input of the register, as well as with the inputs of the “0” setting of the fifth and sixth counters. The third input of the sixth circuit AND is connected to the inverse output of the third trigger, its input to “1” is connected to the output of the countdown transfer of the fifth counter, the direct count input of which is connected to the output of the second OR circuit, and the input of the countdown to the output of the sixth circuit AND and with the first input of the division block. The installation input in the "0" of the third trigger and the ROM control input are connected to the inverse frame synchronization output. The output of the first OR circuit is connected to the counting input of the sixth counter, the parallel output of which through the direct code converter to the secondary is connected via a bus to the second input of the division unit, the output of which is connected to the ROM address input, the ROM and register sample inputs are connected to the common bus, and the register input - with the output of the ROM, the output of the register is connected to the output of the signal processing unit.

The third input of the division unit and the second output of the third delay element are combined. The output of the second AND circuit is connected to the input of the countdown of the third counter and to the second input of the second OR circuit, its first input is connected to the output of the third circuit of And and the input of the countdown of the fourth counter, the inputs of the direct count of the third are connected respectively and the fourth counters, the outputs of the reverse transfer which are connected respectively to the inputs of the installation in "1" of the first and second triggers.

At the output of the signal processing unit, an N _δ code is generated proportional to the thickness δ of the material in accordance with the mathematical expression

where F is the sign of the functional dependence of the thickness on the time interval between electrical signals corresponding to images of rays reflected from the outer and inner walls,

- подсчитанные за период кадровой развертки суммы длительностей интервалов времени между соответственно передними и задними фронтами импульсных сигналов на выходе фотоэлектрического преобразователя, отображающих отраженные лучи;

- the sums of the time intervals calculated between the leading and trailing edges of the pulsed signals at the output of the photoelectric transducer displaying the reflected rays, calculated for the frame scanning period;

n _n , n _s - the number of intervals Tn and Tz, respectively, calculated for the period of personnel scanning.

In the proposed device, the division unit can be made in the form of the first and second counters, an OR circuit, and an investor, the input of which is combined with the output of the first and input of the second counters, and the output is connected to the first input of the OR circuit, the second input of which is connected to the third input of the division unit and the inputs of the installation are “0” of both counters, and the output is to the pre-recording permission input of the first counter, the pre-recording input of which is connected to the second input of the division unit, and the counting input to the first input of the unit, the output of the second counter with connected to the output of the division block.

In addition, the proposed device may differ in that a microprocessor is used as a signal processing unit, which allows to reduce the dimensions of the device and expand its application possibilities for changing the wall thickness of objects with a limited flat part, for example glass bottles, cans.

Figure 1 shows the image of the rays H and B reflected from the outer and inner walls, and also shows a sheet of glass, the thickness δ of which is measured.

Figure 2a shows the images of spots from the rays, if they are observed on the screen of a video monitor connected to the output of the photomultiplier, and figure 2b shows the electrical signals generated at the output of the photomultiplier if they are observed by an oscilloscope. Three scan lines with conditional numbers 1s, 2s, 3s are shown, which form images in the frame. In reality, there are several times more such lines.

Figure 3 shows a functional diagram of an example implementation of the device with a more detailed disclosure of the signal processing unit.

Figure 4 shows the waveforms of the signals that are generated during operation of the device.

The device comprises a light source 1, a photoelectric converter (PEC) 2, a signal processing unit 3, an indicator 4, which are located in the housing 5. A voltage U is supplied to all the blocks. As the light source 1, a laser shaper with a sharply directed beam can be used. As a photoelectric converter, you can use a video camera that has an image to electrical signal converter (see, for example, the newsletter Glass Packaging, No. 3, 2005, p. 5, [3] as well as the Farnell in one catalog, 1 Mar 03, P.578 [4], which describes a miniature video camera with an electrical signal at the output in the PAL television format type MO-S308).

сигналами строчной синхронизации, по второму входу: СИ2 - прямым и

- инверсным сигналами кадровой синхронизации и третьему информационному входу.The signal processing unit 3 (Fig. 3) is connected to the outputs of the photomultiplier tubes at the first input with direct SI1 and inverse

signals of horizontal synchronization, on the second input: SI2 - direct and

- inverse signals of frame synchronization and the third information input.

Block 3 contains the first 6, second 7, third 8 delay elements, the first 9, second 10, third 11, fourth 12, fifth 13 and sixth 14 of the AND pattern, the first 15, second 16 of the OR pattern, first 17, second 18, third 19, fourth 20, fifth 21, sixth 22 counters. Moreover, counters 17, 18 of the type КР1554IE23 or НС4520 (reference book “Logical ICs”, part 2, BINOM, 1993, p. 383) [5], counters 19, 20, 21, 22 of the type КР1554IE6 or 74AC193, page 365 of the reference book [5].

There are also triggers: the first 23, the second 24, the third 25, with zero-level setup inputs, a generator 26, a direct code converter 27 into an additional one (see the book by U. Titze, K. Schenk, Semiconductor circuitry, M .: Mir, 1982, p. 353, 354 [6]), ROM 28, register 29, division block 30.

The composition of the division block includes the first 31, second 32 counters, OR circuit 33, inverter 34.

U is supplied with power to all elements of the device, it is applied to the outer surface of the measurement object or placed at a fixed distance from the surface.

A sharply directed beam from the light source 1 falls on the outer surface of the glass sheet and, partially reflected from this surface, the line H, Fig. 1, passes through the lens into the photoelectric converter 2, the other part of the beam is refracted, passes through the glass sheet, and is reflected from its internal surface and gets - line B, also through the lens into the converter. Images H and B of both beams (Fig. 2a) are converted into electrical signals (Fig. 2b).

The video image of FIG. 2a corresponds to a time-consistent set of electrical signals of FIG. 2b, FIG.

Figure 4 shows the waveforms of the signals observed at different points of the device within one scan frame:

;a) - SI2 frame scan pulses (input 2 of block 3), input 2 also has an inverse signal

;

b) - the signal at the output of 1 element 8 delay;

c), e) - line scan pulses at the input "input 1" of block 3 at different scales;

d), e) - a signal at the information input "vkh 3" at different scales.

In the real case, signals a), c), d) can be collected at one output, but for convenience of consideration, separate outputs are taken.

2, rows are shown as horizontal lines 1C, 2C, 3C. Their intersections with the contours of the light spots form the leading and trailing edges of the electrical pulses 1H, 2H, 3H and 1B, 2B, which are shown in the oscillogram 4e) unfolded in the frame.

The distance To between the axes of OH and OB of the spots is proportional to the thickness δ of the material.

и

с взаимно перпендикулярными сторонами равны),Beam H (Fig. 1) falls at an angle α ₁ , onto the outer surface, at the same angle at point O, goes into the PEC 2 lens, its other part is refracted and again reflected at point C, the angles of refraction and subsequent reflection are α ₂ , point A, the second refraction occurs, and the beam B at an angle α ₁ to the surface goes into the lens of the transducer 2. From point A, we restore the perpendicular AK to the beam OH. Rectangular triangles AEK and AKO are similar (angles

and

with mutually perpendicular sides are equal),

We solve (2), (3), (4) with respect to δ, we find

Since the angles α ₁ and α ₂ for a given material are constant, then, by measuring the distance AK between the rays or the time intervals between them when scanning in time, we find δ.

For the electrical display of spots on the waveform, the AK distance corresponds to the duration of the time interval T0 between the midpoints of the pulses (Fig. 2);

where k is the coefficient of proportionality.

Due to the short duration of pulses 1H, 2H, 1B, 2B, it becomes difficult to determine the interval To through the durations directly, easier and more accurately determine the intervals between the same fronts: front Tn and rear Tz and calculate To as follows.

If the spots H and B are symmetric about the axes OH and OB, then Then can be determined (consider line 2C) as follows:

,

,

where t ₁ - half the duration of the pulse from the spot H;

t ₂ - also for spot B;

t ₃ - the time interval between the trailing edge of the pulse 2H and the leading edge of the pulse 2B.

Substituting (8) and (9) into (7), we find

пар интервалов Тп и Тз и делится на удвоенное число пар, равное суммарному количеству интервалов, образованных передними и задними фронтами импульсов в кадре, получаем Т_{o сред} - среднее значение Т_o в кадре.To reduce random error, the total duration is calculated in each frame

pairs of intervals Tn and T3 and is divided by twice the number of pairs equal to the total number of intervals formed by the leading and trailing edges of the pulses in the frame, we obtain T _{o medium} - the average value of T _o in the frame.

, получаемWe solve together (5), (6), (11) and replace

we get

Formula (12) represents an idealized dependence for calculating δ (Fig. 2B, line f). Due to various errors associated with, for example, image distortion by the photovoltaic lens, there is actually a dependence in the form of function F. To reduce the error, a ROM 28 is introduced in block 3, in which the values of F ₁ ... F _i are used as addresses, according to which, when calibrating the device, the correct thickness values δ ₁ ... δ _{i are} previously sewn up.

- триггер 25. Одновременно с СИ2 вырабатывается первый импульс строчной синхронизации СИ1 и инверсный

, которые устанавливают в исходное состояние элементы 19, 20 и 17, 18, 23, 24 соответственно.Then the transfer characteristic of the device can be represented as a mathematical expression (1), the implementation of which occurs cyclically in each frame, i.e. between two adjacent pulses of SI2 (figa). SI2 pulses are installed in the initial state of the counters 21, 22, and a pulse

- trigger 25. Simultaneously with SI2, the first pulse of horizontal synchronization SI1 and inverse are generated

, which establish the initial state of the elements 19, 20 and 17, 18, 23, 24, respectively.

SI2 starts the delay element 8, and SI1 - elements 6, 7, the signals shown in fig.4b, g, and are generated at their outputs. The signals from the output of elements 6, 7 on the circuit And 9 selects the time interval corresponding to the possible thicknesses from minimum to maximum. Against the background of this interval, the signals from the information input (Fig. 4f) pass through the circuit 9 to the counting inputs of the counters 17, 18. The counter 17 counts the positive edges in each line, and the counter 18 - the negative, therefore, pulses are generated at the output of the first discharge of the counter 17, corresponding to the interval Tn (Fig. 4k), and at the output of the first discharge of the counter 18 - Tz (Fig. 4m) in each line, where there are signals at the input 3 of circuit 9 in the form of two consecutive pulses. In the example, the intervals Tn and T3 are formed in lines 1c, 2c. In line 3c there is only one pulse, therefore, differences are formed at the outputs of the first bits, and the second bits of the counters 17, 18 do not change their state, and the counter 22, which forms the sum (n _p + n _s ), counts two pulses in lines 1 s, 2 s in line, and in line 3c does not change state. Schemes I 12, 13 during the intervals Tn and Tz, in each line where they are formed, pass fill pulses from the generator 26 to the direct counting inputs of the counters 19, 20, respectively (Fig. 4o, p).

обратного переноса отрицательный строб, который устанавливает триггер 23 в состояние "1", при этом на его инверсном выходе появляется низкий уровень, поступающий на вход 3 схемы И 10, счетные импульсы на вход счетчика 21 больше не поступают.After the appearance of a positive difference at the output of the second discharge of the counter 17, the I 10 circuit (Fig. 4p) begins to transmit pulses from the generator 26 to the input of the countdown of the counter 19 and through the OR 16 to the direct input of the summing counter 21. In addition, the positive difference from the output the second category of the counter 17 through the OR circuit 15 will write "1" to the counter 22. The counter 21 counts until the counter 19 is reset, at the time of transition through the "0" counter 19 generates output

the negative gate, which sets the trigger 23 to the state "1", while at its inverse output a low level appears, which goes to the input 3 of circuit I 10, the counting pulses to the input of the counter 21 are no longer received.

обратного переноса появляется отрицательный импульс, который устанавливает триггер 24 в "1", на его инверсном выходе появляется низкий уровень и запрещает подачу импульсов на счетчики 20 и 21.Thus, the contents of counter 19 were rewritten to counter 21. At the moment of flip-flop of trigger 23 to “1”, a positive level was formed at its direct input, which goes to input 4 of circuit I 11, a positive level from the output of the second discharge of counter 18 through circuit OR 15 to the input of the counter 22 and adds “1” to it, and also goes to the input 1 of the And 11 circuit, its input 3 receives a positive level from the inverse output of the trigger 24. To the input 2 of the And 11 circuit there are filling pulses from the generator 26, pass to circuit output (Fig. 4c) and then to the input of atnogo counter account 20 and also through an OR gate 16 to the input of the direct count of the counter 21. The counting process continues until the resetting of the counter 20 when its output

the reverse transfer, a negative pulse appears, which sets the trigger 24 to "1", a low level appears on its inverse output and prohibits the supply of pulses to the counters 20 and 21.

Thus, the contents of the counter 20, corresponding to T3, were added to the contents of the counter 21. With the arrival of the line synchronization pulse 2c, the counters 17, 18, 19, 20, the triggers 23, 24 are set to their initial state, the counters 21, 22 store the contents. The signal processing in line 2c is similar to the process in line 1c.

In line 3c from the output of block 2 there is only one pulse. Similar situations occur in the start and end lines of a frame containing measurement information.

счетчика 31 и разрешает параллельную запись по входу D содержимого счетчика 22 в дополнительном по отношению к разрядности М счетчика 31 коде через преобразователь 27. Дополнительный код (см. [6]) равен М-(n_п+n_з) и до конца кадра не изменяется. Сигнал с выхода 1 элемента 8 разрешает работу схемы И 14. Импульсы счета с генератора 26 через схему И 14 поступают на вход обратного счета счетчика 21 и одновременно на счетный вход счетчика 31. Идет счет до переполнения счетчика 31. В момент переполнения вырабатывается сигнал на выходе CR, который через инвертор 34 поступает на вход 1 схемы ИЛИ 33 и далее на вход

счетчика 31, происходит предустановка счетчика 31. Цикл предустановки по входу Д повторяется через каждые (n_п+n_з) импульсов. Счетчик 32 подсчитывает число переполнений. Как только счетчик 21 в обратном счете обнуляется, на его выходе появляется отрицательный импульс

и устанавливает триггер 25 в "1", с его инверсного выхода поступает низкий уровень на вход 3 схемы И 14 и останавливает счетчики 21, 31.Such pulses are ignored, since they only change the state of the first bits of the counters 17, 18, and circuits I 12, 13 do not allow the operation of the counters 19, 20. The following are the lines without pulses. By this time, the number 4 is stored in counter 22, and in the counter 21 is the sum of the duration of two intervals from positive edges and two corresponding intervals from negative edges. The following describes the operation of the division unit in the form in which it is performed in an example implementation of the device. Toward the end of the frame, a negative strobe is generated by the delay element 8 at its output 2, which corresponds to the positive pulse edge τ _s (Fig. 4b) of element 8, and sets the counters 31, 32 to their initial state. The same strobe with a slight delay on the OR element 33 arrives at entrance

the counter 31 and allows parallel recording on the input D of the contents of the counter 22 in an additional code with respect to the bit M of the counter 31 through the converter 27. The additional code (see [6]) is equal to M- (n _p + n _s ) and until the end of the frame is changing. The signal from the output 1 of element 8 allows the operation of circuit I 14. The count pulses from the generator 26 through circuit And 14 are fed to the input of the counting counter of counter 21 and simultaneously to the counting input of counter 31. There is a count until the counter 31 is overflowed. At the time of overflow, a signal is generated at the output CR, which through the inverter 34 enters the input 1 of the circuit OR 33 and then to the input

counter 31, the counter 31 is preset. The preset cycle at the input D is repeated every (n _p + n _s ) pulses. Counter 32 counts the number of overflows. As soon as counter 21 in the countdown is reset, a negative impulse appears at its output

and sets the trigger 25 to "1", from its inverse output a low level is supplied to input 3 of circuit And 14 and stops the counters 21, 31.

в начале следующего кадра содержимое счетчика 32 в параллельном коде воздействует на входы адреса ПЗУ. По выбранному адресу выбирается значение функции F_i по формуле (1), которое отображает толщину δ_i; с выхода ПЗУ по тому же импульсу, но положительной полярности СИ2 значение кода переписывается в регистр 29 и остается там до следующего цикла, т.е. до следующего импульса СИ2. Выход регистра воздействует на индикатор, который отображает результат измерения.The counter 21 will stop in a state of zeros, the counter 31 in a state between 0 and (n _p + n _s ), the counter 32 in a state corresponding to the formula (11). With the arrival of momentum

at the beginning of the next frame, the contents of the counter 32 in the parallel code affect the inputs of the ROM address. At the selected address, the value of the function F _i is selected by the formula (1), which displays the thickness δ _i ; from the ROM output by the same pulse, but with a positive polarity SI2, the code value is written to register 29 and remains there until the next cycle, i.e. until the next impulse SI2. The output of the register acts on the indicator, which displays the measurement result.

As a register, the KR1554IR22 chip or its analog 74AC373 (see the reference [5] p. 389) can be used, as the counter 31 - the KR1554IE18 chip of the p.379 [5], the counter 32 can be performed on the KR1554IE23 chip.

Claims (3)

1. A device for measuring the thickness of a transparent material containing a light source, a photovoltaic converter, a signal processing unit, an indicator that are placed in the housing and connected to a constant voltage source and a power input, and the direct and inverse horizontal sync outputs of the photovoltaic converter are connected respectively to the first direct and inverse inputs of the signal processing unit, direct and inverse outputs of frame synchronization are connected respectively to the second direct and inverse inputs the processing unit, the third input of which is connected to the information output of the converter, the output of the processing unit is connected to the indicator input, characterized in that the signal processing unit is made in the form of the first, second and third delay elements, the first, second, third, fourth, fifth and sixth circuits AND, first, second circuits OR, first, second, third, fourth, fifth, sixth counters, first, second and third triggers, generator, direct code to additional converter, division block, permanent memory about the device (ROM) and the register, while the inputs of the first and second delay elements are connected to the input inputs of the third and fourth counters, as well as to the first direct input of the signal processing unit, and their outputs are connected to the first and second inputs of the first circuit And, its third input is connected to the third input of the unit, the input of the register recording control is connected to the second direct input of the signal processing unit and to the installation inputs at “0” of the fifth and sixth counters, as well as to the input of the third delay element, the first output of which is connected to the first in ohm of the sixth circuit And, the second input of which is combined with the output of the generator and the second inputs of the second, third, fourth and fifth circuits And, the third input of the sixth circuit And is connected to the inverse output of the third trigger, and its output is with the countdown input of the fifth counter and the first input the division unit, the second input of which is connected to the output of the code converter, the input of which is connected to the output of the sixth counter, the second output of the third delay element is connected to the third input of the division unit, and its output is connected to the address input of the ROM, selection inputs P Y and the register are connected to a common bus, and the ROM output is connected to the register input, the counting input of the sixth counter is connected to the output of the first OR circuit, the first input of which is connected to the output of the second discharge of the first counter and the first input of the second AND circuit, the third input of which is connected to the inverse the output of the first trigger, the direct output of which is connected to the fourth input of the third AND circuit, the installation input to "1" of the first trigger is connected to the reverse transfer output of the third counter, and the installation input to "0" to the first inverse input of the signal processing unit, with the installation inputs to "0" of the first and second counters and the installation input to "0" of the second trigger, the installation input to "1" of which is connected to the reverse transfer output of the fourth counter, the inverse trigger output is connected to the third input of the third circuit And, the first input of which is connected with the second input of the first OR circuit and the output of the second discharge of the second counter, the input of the account on the negative edge of which is connected to the input of the account on the positive front of the first counter and with the output of the first circuit And, the same resolution inputs of the account of the first and second counter kV are connected respectively to the positive and common supply buses, the outputs of the first bits of the first and second counters are connected respectively to the first inputs of the fourth and fifth circuits AND, the output of which is connected to the input of the direct count of the fourth counter, the input of the counting of which is connected to the output of the third circuit And with the first input of the second OR circuit, the second input of which is combined with the output of the second circuit And and with the input of the countdown of the third counter, the input of the direct count of which is connected to the output of the fourth circuit And, the second output OR gates are connected to the input of the direct count of the fifth counter, the reverse transfer output of which is connected to the installation input at “1” of the third trigger, the installation input to “0” of which is connected to the second inverse input of the signal processing unit, and to the “read ROM” input, the output the register is connected to the output of the signal processing unit, on which the code is generated in accordance with the mathematical expression

where N _δ is a code representing the thickness of the measured material; F is the sign of the functional dependence of the thickness on the time interval between electrical signals corresponding to images of rays reflected from the outer and inner walls;

- the sums of the time intervals calculated between the leading and trailing edges of the electrical signals that reflect the reflected rays at the output of the photoelectric converter, calculated for the frame scanning period; n _p , n _s - the number of intervals T _p and T _s respectively, calculated for the period of the frame scan. 2. The device according to claim 1, characterized in that the division unit is made in the form of the first and second counters, an OR circuit, and an inventor, the input of which is combined with the output of the first counter and the input of the second, and the output is connected to the first input of the OR circuit, the second input of which connected to the third input of the division unit and the installation inputs to “0” of both counters, and the output to the pre-enable input of the first counter, the preliminary record of which is connected to the second input of the division unit, and the counting input to the first input of the unit, the output of the second counter connected to the output of division unit. 3. The device according to any one of claims 1 and 2, characterized in that the microprocessor is used as a signal processing unit.

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