SU532866A1 - Character reader - Google Patents

Description

one

The invention relates to automation and computing and can be used in information retrieval systems.

Known reading device

symbols contains a scanning unit connected to a mode switching unit, a photomultiplier tube (PMT connected to a data acquisition unit, a control unit connected to a zone counter and a character code register, an optical information analysis unit and a switching unit

sh.

This device has a complex structure.

The closest to the image is a symbol reading device containing an electron beam tube (CRT) coordinate deviation unit connected to serially connected symbol scanning units, line and frame generation counters, a control unit connected to the character scanning unit and formation counter frames, photomultiplier tube (FZU), connected

unit connected to the operating mode switching unit, the comparison unit, the character code register, the decoder and the AND, OR 23 logic elements.

This device has a low speed in the work when transmitting the connected information via a communication channel.

The purpose of the invention is to increase the speed of the device.

For this, the device contains a memory unit connected to the first input of the comparator unit, the second input of which is connected to the symbol scanner through the delay element, and the third input is connected to the character code register, the encoder connected to the outputs of the comparison unit and to the input of the switching unit, unit forkshirovani characters code, connected to the photomultiplier tube, to the register of the character code and to the character scanning unit, the number of characters counter, connected to the operating mode switching unit and through the decoder with the inputs a memory unit, and fixing unit sravnivayuschihs symbols connected to the comparator and the switching operation modes. The drawing shows a block diagram of a device. The device comprises a control unit 1 consisting of a generator of 2 clock pulses, an element 3 and a frame change trigger 4, a symbol scanning unit 5, a row generation counter 6, a frame formation counter 7, a beam coordinate deflection unit 8 CRT, block 9 of switching modes of operation, consisting of the element And 10, the element 11 delay, the element And 12 and the trigger 13; a counter 14 of the number of symbols of this alphabet, a decoder 15, a photomultiplier 16, a block 17 for generating a character code, a register 18 for a character code; a memory block 19 containing memory cells 20, the number of which is equal to the number of characters of this alphabet, a comparison block 21 containing separate circuits 22, each of which has its own output and the number of which is also equal to the number of characters of this alphabet; a delay element 23, a latch 24 comparing a symbol consisting of the element OR 25 and a trigger 26; the encoder 27 and the switching unit 28, consisting of two elements AND 29, 30 and element OR 31. After setting the read information carrier to the fixed position, the signal arrives at the single input of the trigger 4. The operation of this trigger leads to the appearance of a potential at its output, allowing signals from the generator 2 clock pulses to pass through the element I 3 at the inlet of block 5. The numbers, set at each discrete point in time, are sent to the block 8 of the coordinate deflection of a CRT by the numerical outputs of the latter. As a result, the information character is line by line. Each intersection of the beam with the line of the symbol to be read as it moves across the field of the symbol leads to the appearance of a video signal at the output of the photomultiplier 16. These signals arrive at the input of the symbol code generation unit 17, as well as through the AND element 30 of the commutation block 28, the second input of which allows the potential from the zero output of the operating mode trigger 13 and the OR element 31 to the communication channel. The impulse of the overflow sign of the block 5, characterizing the end of the symbol scan, goes to the row formation counter 6, to the input of the resolution for writing the character code of the register 18, to the reset input of the code generating unit 17, to the input of the delay element 23 and to the mode switching unit 9. As a result, the state of the counter 6 is changed, the generated character code is written to the register 18, and block 17 is ready to form the next character code. The signal delayed by the time of writing the symbol code to the register 18, from the output of the delay elementum 23, goes to the enable inputs of the comparison circuit 22 of block 21. Since no codes initially contain any codes in one of the cells 20 of the memory block 19, none of the outputs Comparison circuits of block 21 are not working. Consequently, there will be no signal on either of the inputs of the encoder 27 and on the output of the OR element 25. As a result, the state of the trigger 26, the fixation block 24 of matching symbols, at the output of which the resolving potential is unchanged. Therefore, the signal delayed by the delay time of the element 23 and the response time of the trigger 26, from the output of the delay element 11 of the operating mode switching unit 9, passes through the element 12 to the input of the counter 14 of the number of characters of this alphabet and through the 31 element of the switching unit 28 to the channel zi A change in the state of the counter 14 causes the appearance at one of the outputs (upper) of the decoder 15 of the enable signal of the character code recording. As a result, the character code from register 18 is written to the top (first) cell 20 of memory block 19. Thus, when scanning the first symbol, signals from each point belonging to the symbol and a signal (from the output of the element 12), indicating the sequence number of the incoming symbol, arrive at the communication channel. The generated character code is recorded in the first cell 20 (meaning that the cell numbers increase from top to bottom according to their location of block 19 .. Therefore, there is a one-to-one correspondence between the sequence number of the cell of this block in which the character code is written and the sequence number of this ( of a symbol received in the communication channel. Obviously, such a correspondence also exists between the outputs of the comparison circuits 22 of the block 21 and the indicated symbol number. A change in the state of the counter 6 causes the readout electron beam to shift CRT one character by X. As a result of the unit 5 is now happening

Scan the next character of the read information.

In the future, the operation of this part of the circuit that controls the mixing of the read beam occurs in a similar way. The impulse to the cause of overflow of counter 6, signifying the end of reading a row, leads to a change in the state of frame formation counter 7, which causes the beam to move to the next line of the storage medium.

The complete filling of block 5, counters 6 and 7 determines the instant of reading this frame of information. In this case, the overflow sign pulse from the output of the counter 7 will be applied to the zero input of the trigger 4. As a result, the output of the trigger 4 shows a potential that prohibits the passage of signals from the generator 2 clock pulses through the element 3 to the input of the block 5.

The end of the scan of each subsequent symbol is also determined by an overflow indication signal from the output of flip-flop 4. In this case, if the read signal is different from the previous ones, the codes in the circuits 22 of block 21 will not compare. In this case, the operation of the device is similar to its work when reading the first character. The difference is that the generated code of this symbol will be recorded in the next cell 2O of the memory block 19.

If upon further scanning a previously read symbol is encountered, then, as a result, a signal is received at one of the outputs of the comparison circuit 22 of the block 21, which is fed to the input of the differentiator 27 and through the OR element 25 to the single input of the trigger 26.

The code defining the number of the excited output of the block 21 will not come from the output of the encoder 27 to the communication channel, because the second input of the element 29 of the switching unit 28 contains the inhibitory potential from the single output of the trigger 13.

Changing the state of flip-flop 26 leads to the prohibition of the signal passing from the output of the delay element 11 through the element 12. As a result, only signals from each point of the symbol are sent to the communication channel, and there is no signal indicating the sequence number of this symbol. Since the state of the counter 14 does not change with, the character code from register 18 will not be recorded in memory block 19. From the output of the delay element 11, the signal will go to the zero input of the trigger 26 to return it to its original state.

In the future, the device will operate in the same way until the last cell 2O of the memory unit 19 is filled, i.e. until the last character of the alphabet is read. In this case, the overflow indication signal from the output of the counter 14 will go to the single input of the trigger 13 of the block 9, the state change of which is caused by the closure of the And 10, 30 elements and the opening of the And 29 element.

Upon subsequent reading of any character of this alphabet, a signal will appear at one of the outputs of the circuits 22 of block 21. The code defining the number of this output, and hence the symbol recorded in the corresponding cell 20 of block 19, will come from the output of the encoder 27 through AND 29, OR 31 elements of the switching block 28 to the communication channel.

The introduction of new units and blocks, as well as new constructive links between them, allows to increase the speed of the device operation by 2-4 times in comparison with the known.

Claims (2)

1. US Patent No. 3629828, Cl. 340146 .3, 12.21.1972. 2. Japanese Patent No. 49-19619, Chl. 97 (7) 862, 05/18/1974. 1t 1t1