SU1635203A1 - Device for reading graphic information - Google Patents

Description

(21) 4677732/24

(22) 04/11/89

(46) 03/15/91. Bul Number 10

(71) Research Institute for Applied Physical Problems. A.N.Sevchenko

(72) V.G. Khakirevich and A.M.Mukharsky

(53) 681.327: 12 (088.8)

(56) USSR inventor's certificate 1372343, cl. G 06 K 11/06, 1982.

USSR Author's Certificate No. 1506450, class G 06 K 11/06, 1987.

(54) DEVICE FOR READING GRAPHIC INFORMATION

(57) The invention relates to automation and computing and

It can be used in computer-aided design systems as well as in computer-aided training systems as a device for inputting the coordinates of handwritten graphic information into a computer in the process of writing (drawing) it. The purpose of the invention is to improve the accuracy of the device. This is achieved by replacing the linear amplitude quantization of the subband increments of the read signal with non-linear quantization, which is ensured by introducing multiplexers, memory blocks of the group, And elements of the group, first and second decoders, first and second And elements, and a second counter. 1 hp f-ly, 2 ill.

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The invention relates to automation and computing, in particular to a device for reading graphic information.

The purpose of the invention is to improve the accuracy of the device.

Figure 1 presents the block diagram of the proposed device; Fig. 2 is a diagram of the formation of the coordinates of the exact reference.

The device (Fig. 1) contains a tablet 1 with coordinate tires 2 connected via resistors 3 to power supply 4, block 5 for generating a coarse-count code, including keys 6, decoder 7, counter 8, amplifier shaper 9, amplitude discriminator 10, single-oscillators eleven /

and 12, the element And 13, the trigger 14 phase and the element NOT 15, the amplifier-driver 16, the puller 17 coordinates, block 18 forming the intermediate reference code, which includes amplifiers 19, the threshold elements 20, the elements AND NOT 21, triggers 22 and the converter 23 code, block 24 of forming the code of the exact reference (Fig. 2), including a block of memory 25, made in the form of a permanent memory (ROM), the first digital-to-analog converter (DAC) 26, the first 27 and the second 28 amplifiers, the comparator 29, the second DAC 30, the first element And 31, the first counter 32, multiplexers 33, the first 34th decoder, a group of memory blocks 35, And 36 group elements, the second element

And 37, the second counter 38 and the second decoder 39, the control unit 40, comprising the first one-shot 41, the first element And 42, the counter 43, the decoder 44, the second element And 45, the third element And 46, the element NOT 47, the fourth element And 48, the second 49 and the third 50 one-shot, time-sampling block 51, which includes a signal sensor 52, a signal conditioner 53, a first one-shot 54, a first AND element 55, a second one-shot 56, second And element 57, a third one-shot 58, a decoder 59, a counter 60, the fourth the innovator 61, the third element And 62, the fifth one-shot 63, the sixth HO- vibrator 64 and the generator 65 pulses apparatus operates as follows.

With the closure of the contacts of the sensor 52 at the output of the imaging unit 53, a permit potential appears, which opens the element 55 at its first input. Differential output voltage shaper 53 from zero to high triggers the first 54 and second 56 one-shot ones. Short-term inhibitory (negative) potential from the output of the one-shot 54 closes the element And 57 at its first entrance as a result of this pulse at the output of the elements And 55 and 57 are missing. The time of the regenerative process of the first one-shot 54 is chosen to be significantly longer than the time of the regenerative process of the second one-shot 56, and the time of the regenerative process of the fourth one-shot 61 is chosen to be less than the time of the regenerative process of the second one-shot 56. during which a negative potential exists at the output of the one-shot 54, the one-shot 56 and 61 form a short pulse with a general reset. This pulse from the output of the single-vibrator 61 is fed to the first input of the element I 62 and then both to the input of the zero state of the counter 60, and to the installation inputs of the circuit triggers. After setting the triggers of the circuit to the initial state by the output pulse of the element And 62, the negative potential from the output of the one-shot 54 still exists for some time. After resetting the counter to 60

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the left state at the output of the decoder 59 occurs permitting (positive) potential. A feature of the decoder 59 is that it decrypts only one number (constant) located in the counter 60. The output potential of the decoder 59 opens the element 55 at its third input. At the end of the regenerative process in the one-shot 54, the low potential at its output disappears, as a result of this, the element 55 opens to its second entrance. The presence of enabling (high) levels at the first, second and third inputs of the element And 55 ensures the passage of pulses. From the generator 65 pulses to the output of this element.

From the moment of opening element 55 after general resetting of the circuit triggers, the first cycle of operation of the device starts forming the coarse reference code of the X coordinate. When forming this code, the pulses from the output of element 55 go to the second inputs of elements 46 and 45 of block 40. However, the input pulses pass only at the output of the element 45, since at the first input of this element there is a resolving (high) potential from the third output of the decoder 44. This potential is due to the zero state of the counter 43. The pulses from element output 45 comes to the first output of block 40 and further to the counting input of counter 8 of block 5. Pulses from the output of element 55 also arrive at the input of one-vibrator 50 of block 40. With a single-vibrator 49, a short negative pulse is formed on the falling edge of the output pulse of one-vibrator 50 POLL. This pulse from the output of the one-shot 49 is fed to the second input element And 48. At the first input of this element there is a high potential from the output of the element NOT 47, since at its input there is a low potential from the first output of the decoder 44.

The output pulse of the element 48 is fed to the gated input of the decoder 7 of the block 5. When the counting pulses enter the counter and the POIR pulses through the gated input to the decoder 7 using the polling keys 6, it is performed sequentially in time and space

interrogation of coordinate buses along the X axis. At the same time, the POISON pulses arrive at the input of the NOT 15 element. The POLLE signal performs the function of a reference signal for phase-pulse selection of the readout signal over its negative half-period. With each successive interrogation of the coordinate bus, a double-sided read signal appears at the output of the sense amplifier 16, which is fed to the input of the amplifier-former 9 and then into the amplitude discriminator 10. The task of elements 9 and 10 is to form a negative reading signal from the negative half cycle a carbon pulse whose duration is determined by the duration of the base of the negative half-cycle of the read signal. The rectangular output pulse of the discriminator 10 is fed to the input of the one-oscillator 11, which, together with the single-vibrator 12, forms a short positive pulse STROB. This pulse due to these single vibrators becomes shifted in time relative to the leading edge of the negative half cycle of the read signal. This is necessary for a more reliable phase selection of the readout signal by its negative half-period. The process of interrogating the coordinate buses and the simultaneous formation of a coarse counting code in the counter 8 continue until the interrogated coordinate bus is to the left of the inductance coil of the 17-coordinate remover. When the coordinate tires from the puller 17 are polled to the right, the pulses from the output of the one-shot 12 go to the third input of the element I 13, but do not pass to the output of this element, since the moment of its arrival coincides with the moment when the high potential of the POLL signal from the output of the element NOT 15, i.e. the POLL signal and the STROBE signal do not match in time. The STROBE signal appears later than the POLL signal. As soon as the interrogated coordinate bus is left to the left of the inductance coil of the puller 17 coordinate, the read signal at the output of the amplifier 16 changes phase to 1801.

After the reversal of the phase of the readout signal, the formation of the STROBE signal occurs in the same way as

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as it happened when polling tires lying to the right of the inductance coil of the 17 puller inductance. However, in the case when the interrogated coordinate bus is to the left of the puller coil 17 and the read signal underwent a phase reversal, the moment of the negative half period of the read signal began to almost coincide with the moment of the POLLING signal. As a result, the output positive impulse of the one-shot 12 begins to coincide in time with the moment of the existence of the resolving (high) potential from the output of the element NO 15.

The short-term coincidence of two high potentials at the first and second inputs of the element And 13 causes the appearance of a short-term positive pulse at the output of this element, i.e. in this case, the STROBE signal coincides in time with the reference POLL signal. The fact of coincidence is indicated by the presence of a short positive pulse at the output of the element 13. Thus, when the interrogated coordinate bus is to the right of the coil of the 17 puller 17, the output signal STROB from the output of the one-shot 12 does not coincide with the appearance of the positive potential of the reference signal from the element NOT 15, but as soon as the interrogated coordinate bus appears to the left of the puller coil 17, this coincidence takes place. A positive impulse from the output of the element And 13 enters the single installation input of the trigger 14 and sets this trigger in the single state. The output pulse of the element And 13 also arrives at the first input of the first element And 42 and then to the counting input of the first counter 43.

As a result, the counter 43 switches from the operation of forming the coarse-count code to the operation of forming the exact-count code. In this case, a forbidden potential appears at the third output of the decoder 44, and a resolving potential appears at the second output of the decoder 44. The inhibitory (negative) potential of the third output of the decoder 44 closes the element 45 of the beginning-end of the formation of the coarse-reference code.

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As a result, the arrival of pulses from the output of the element I 45 to the counting input of the counter 8 stops; the information output code of the counter 8 determines the coordinate of the geometric center of the induction coil of the puller 17 coordinates on the plane of the plane relative to its origin of coordinates along the X axis.

The resolving potential of the second output of the decoder 44 opens the element And 46 on the first input. Due to this element, And 46 becomes prepared for the passage of pulses from the output of element And 55 through the second input of element And 46 to the first input of element And 37 and from the output of element And 37 to the counting input of counter 38 and to the first inputs of elements And 36.

The formation of the exact reference code takes place in two stages: at the first stage, the code of the most significant bits of the full code of the exact reference is formed, at the second, the code of the lower bits of the full code of the exact reference coordinate.

The high-order code is fixed on the trigger group of trigger group 22, and the low-order code is generated on the counter 32. The high-order code is generated by parallel digital processing of the positive half-wave (half-cycle) of the read signal and the low-order code by sequential processing of a certain part amplitudes of this half period. The high-order code is generated in block 18, and the low-order code is generated in block 24. With the flip-flop 144 becoming one, these two blocks are prepared to form the corresponding full-count code of the exact count. The resolving (high) potential from the single output of the trigger 14 enters the second inputs of the AND-HE elements 21, thereby preparing this block to form the intermediate reference code (or the high-order code of the full exact reference code of the X axis coordinate). The resolving potential from the single output of the trigger 14 also enters the second input of the element I 31 and thereby prepares the counter 32 for fixing the low-order code of the full exact code of the reference

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Immediately after the trigger 14 is set to the one state, the amplitude quantization of the positive half-cycle of the read signal begins. This half-period immediately follows the negative half-period, from which the trigger 14 has been set to one state. The amplitude of the positive half-cycle depends on the distance between the interrogated X bus and the projection of the geometrical center of the puller of 17 coordinates. Therefore, the intermediate reference can be judged from the value of the intermediate reference code, which is indicative of which coordinate sub-band the projection of the coil's geometric center is located in. The subband number in which the projection of the geometric center of the coil is located is a random value. Suppose the projection is in the third coordinate subband. Then X Pr will be equal to the sum of two coordinate subranges: the first and second. The task of block 18 is to find a digital equivalent of the mechanical quantity Hpr. The intermediate reference code is generated using threshold elements 20, the response thresholds of which are set in correspondence between the sub-band emf. For the case in question, the first and second threshold elements will be triggered. The first threshold element is the element located at the very top of the diagram (Fig. 1).

The output pulses from the two triggered threshold elements 20 of all the threshold elements of group 20 pass through the corresponding elements (top two) of the 21 AND-NOT groups of elements and set the corresponding trigger group 22 triggers to one state. As a result, the number two is fixed on the trigger group in the position code. The positional code converter 23 converts this code into binary code 8-4-2-1. The converted code from the outputs of the converter 23 is fed to the corresponding information outputs of block 18 and then through the corresponding information inputs of block 24 of the exact reference to the address inputs of block 25. The same code goes to

corresponding control inputs. multiplexers 33 groups, as well as to the corresponding information inputs of the decoder 34. Due to the fact that the intermediate reference code is fed to the inputs of three electronic units of block 24, the corresponding three preparatory operations are performed. Firstly, this code is used to read the contents of the second address of block 25. The number of addresses of block 25 is equal to the number of interspecific-range EMF. In each of the addresses of block 25, digital equivalents of the corresponding inter-range EMF are recorded (recorded). From the output of block 25, the code enters the information inputs of the DAC 26. Therefore, a compensating voltage appears at its analog output, the level of which is proportional to the inter-subband EMF. The compensating output voltage of the DAC 26 is fed to the first input of the amplifier 27, which performs an analog subtraction operation from the actual signal (positive half-wave) of the amplifier 16, which is fed to the second input of the amplifier 27, which compensates the voltage of the FAP 26. The difference signal with the output of amplifier 27 through amplifier 28 (read signal increment amplifier) is fed to the first input of amplitude comparator 29. Thus, the first microoperation is an analog subtraction operation from a voltage level read signal nor proportional to the corresponding mezhdupoddiapazonnoy EMF. Upon the completion of the positive half-period of the read signal, the generation of the high-order code (intermediate reference code) of the full exact code ends and, at the bit outputs, the code converter 23 continues to be present at the higher bits of the full exact-code. According to the output code of converter 23, the coordinate of the intermediate reference is measured. The low-order bit of the output code of converter 23 is determined by the value of the coordinate subband.

After the transition of the trigger 14 to the unit state at the third input of the element And 13, the inhibitory potential appears, which closes the element And 13. Therefore, during the formation

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The low-order code of the full exact code at the output of the element And 13 pulses are absent. Before the formation of the low-order code of the full exact-count code, the second and third micro-operations are implemented. The second micro-operation is the preparation (connection) with the help of multi-plexors 33 of the corresponding (third from the bottom according to the diagram of Fig. 2) sub-memory block 35 to the information inputs of the DAC 30. The third micro-operation is the connection of the selected sub- J5 of the range block 35 to the first the input of the corresponding element 36 for performing a cycle of reading the contents of the cells of the block 35 (third) and submitting them to the corresponding information inputs of the multiplexers 33 and then sequentially in time for entering the contents of each cell to the information nnye inputs HPAC. This connection is made by the corresponding (third) output of the decoder 34.

After the subband unit 35 is connected to the DALC, the actual 30 low-order code generation cycle begins. In this cycle, the pulses from the output of the element And 48 continue to flow to the gated input of the decoder 7 and then to the input of that key of group 6 of keys, whose number became known after the cycle of forming the coarse reference code. As a result of the arrival at the control input of the third subband block 35 of the pulses from the output of the element 36, sequential reading of the cells of this memory begins, and as a result, a step-down compensating voltage appears at the analog output of the JO / DAC.

The type of approximation can be chosen by writing to each block 35 corresponding numbers (constants), the number of which depends on the required accuracy of changing the Xr coordinate of the exact reference.

t In the coordinate measurement cycle, an electrical value is measured — a readout signal — by comparing 55 it with a step-compensating voltage. For this, polling pulses continue to be sent to the selected coordinate bus. As a result, the output of the read coil

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A puller with 17 coordinates in the general case appears a burst of pulses. The number of pulses in a pack depends on the magnitude of the coordinate of the exact reference. The maximum number of pulses in a burst is equal to the number of polling pulses fed to the bus in the low-order burst formation cycle of the complete code of the exact count.

Uncompensated input pulses (from the first input) of the comparator 29 pass to its output and are recorded in counter 32. Element I 31 is open at the moment when the low-order bits of the full exact code are started to form on the first input by the output potential from the single output of trigger 14. Uncompensated pulses pass to the output of the comparator 29 and then through the second input of the element I 31 to the counting input of the counter 32 until the moment of compensation of the output difference signal of the amplifier 28 is reached by the output compensating April 30 zheniem DAC.

The polling pulses in the selected coordinate bus continue to arrive after the moment of compensation of the difference signal, and therefore, the difference signal is fed to the first input of the comparator 29 and after compensation. However, this signal does not pass to the output of the comparator. The polling pulses in the low-order code generation cycle are fed with a simultaneous counting of their number by a counter 38. Synchronously, the number of read cycles of the block 35 is counted. The number of clocks is equal to the number of polling pulses. As soon as the counter 38 has a number that is equal to the required number of current pulses, and therefore the number of read cycles (the third subband), the decoder 39 decrypts this number. As a result, a inhibitory potential appears at the output of the decoder 39, which enters the input of the one-shot 41. The output potential of the decoder 39 also enters the second input of the AND 37 element and thereby stops the flow of pulses into the counter 38.

The impulse from the single vibration damper 41, having passed through the element 42, increases the content of the counter 43 by one and the decoder 44 closes with its second output

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element E 46. At the first output of the decoder 44, a resolving (high) potential arises, which is inverted. The element is NOT 47. Therefore, the element AND 48 is closed at the second input. Thus, the supply of pulses to both the selected coordinate bus and to the counter 8 is stopped. At this, the formation of the X coordinate code is completed, the coarse count code is fixed on the counter 8, and the full code of the coordinate of the exact count is fixed at the outputs of the converter 23 and the counter 32.

After forming the full code of the X coordinate in the same way, the full code of the Y coordinate is formed. In the cycle of forming the full code of the Y coordinate, the pulses from the output of the AND 55 element continue to flow to the counting input of the counter 60. The number of pulses (constant) that have passed from the output of the And 55 element, such what their

25 is enough to form the full code of the X coordinate and the Y coordinate. The pulses from the output of the element And 55 counts the counter 60. As soon as the number of pulses fixed by this counter reaches a constant, the output of the decoder 59 causes a inhibitory (low) potential that closes the element 55 through its the third entrance. The arrival of pulses at the output of the element 55 is stopped.

The differential output voltage of the decoder 59 from high to low starts the third single vibrator 58. The formed short output pulse of the single vibrator 58 passes through the second element And 57 and starts the sixth single vibrator 64. The rear edge of the output pulse of the single vibrator 64 starts the fifth one 45 new vibrator 63. The output short pulse of the one-shot 63 passes through the third element I 62 through it. the second input and resets the counter 60 and all circuit triggers to the initial state. At the output of the decoder 59, the resolving potential again appears, which opens the element 55 from its third input. As a result, pulses appear at the output of AND 55. The formation of the X and Y coordinate code begins again, but already at a new point, since during the time of the regeneration process of the one-vibrator 64, the tip of the writing element 30

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This 17-coordinate puller was displaced by some distance along both coordinate axes relative to the origin of the tablet. The delay time (regenerative process time) of the one-shot 64 can be selected based on the speed at which the graphic information is applied by the user of the device. This time defines a pause, after which the next coordinate reading begins.

Thus, while the user applies handwritten graphic information to a sheet of paper (or other non-paper graphic media) and the contacts of the sensor 52 are closed, the coordinate code is generated cyclically and this code is output from the output signal of the AND 62 element in the computer. As soon as the user stops drawing graphic symbols or drawings, the touch sensor 52 opens its contacts. As a result, the element And 55 is closed at the first entrance - the formation of the coordinate code and its issuance to the computer cease.

Claims (2)

1. A device for reading graphic information containing a tablet with an orthogonal coordinate busbar system, the inputs of which are connected to the outputs of the first group of the coarse code generation unit, the counting input of which is connected to the first output of the control unit, and the strobing input is connected to the second output of the control unit Amplifier, the information input of which is connected to the output of the coordinate remover. And the output is connected to the information input of the coarse-count code generation unit and the information input The intermediate-code code generator unit, the control input of which is connected to the first output of the coarse code generation unit, and the outputs are connected to the address inputs of the first memory block, whose outputs are connected to the information inputs of the first digits of the analog converter, the output of which is connected to one information input the first amplifier, the other input of which is connected to the output of the amplifier-former, and you five the stroke is connected to the input of the second amplifier, the output of which is connected to one input of the comparator, another input of which is connected to the output of the second digital-analog converter, and the output is connected to one input of the first element And, the other input of which is connected to the first output of the coarse-count code generating unit, and the output is connected to the counting input of the first counter, a time sampling unit, the output of which is connected to the clock input of the control unit, characterized in that, in order to increase the accuracy of the device, it contains multiplexers, control inputs of which are connected to respective outputs of block forming the intermediate code reference, and outputs connected to the data inputs of second tsifroanalogo- Vågå transducer block group the information inputs of the corresponding multiplexers, the group of elements AND, whose outputs are connected to the read inputs of the corresponding memory blocks of the group, the first decoder, whose information inputs are connected to the outputs of the intermediate reference code generation unit, and the outputs are connected to the same inputs of the corresponding elements AND of the group, the second element AND , one input of which is connected to the third output of the control unit, and the output is connected to other inputs of the corresponding AND elements of the group, the second counter, the counting input of which th connected to the output of the second AND gate and a second decoder, data inputs of which are connected to the outputs of the second counter and an output coupled to another input of the second AND gate and a data input control unit, a clock input which is connected to the second output of the block forming coarse reference code. 2. The device according to claim 1, characterized in that the control unit contains the first one-shot, the input of which is the information input of the control unit, and the output is connected to one input of the first element, AND, the other input of which is the synchronizing input of the block, and output connected to the counter input of the counter, the outputs of which are connected to the information rig.1