SU1615759A1 - Device for reading graphic information off crt screen - Google Patents

Abstract

The invention relates to automation, in particular, to a device for reading graphic information from a CRT screen, and can be used in interactive human-computer interaction systems. The purpose of the invention is to increase the speed of the device. The goal is achieved by realizing the possibility of moving the marker to the point of removal of coordinates during the half frame of the standard interlaced decomposition, which is ensured by the introduction of a key, two inverters and a signal conditioner. 4 il.

Description

 The invention relates to automation, in particular, to a device for reading graphic information from a screen of a cathode ray tube (CRT), and can be used in interactive human-computer systems.

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

Figure 1 presents the block diagram of the device; Fig. 2 is a diagram of a marker formation unit; Fig. 3 is a diagram of a memory block; 4 is a diagram of the ceHCopHoi block. o management.

The device (Fig. 1) contains an amplifier-limiter 1, a comparator 2, the first 3.4 and the second 5, 6 groups of elements I, memory blocks 7 and 8, reversible counters 9 and 10, coincidence blocks 11, trigger 12, block 13 forming a marker, block 14 of the touch control, puller 15 coordinates,

filled in as a pen, synchronization unit 16, containing counter 17, generator 18: i counter 19, mixer 2Q, video control unit 21 and video source 22,

The marker forming unit (Fig. 2) contains pulse shaper 23 and 24, invertors differentiators 25 and 26, pulse shapers 27 and 28, a group of elements OR 29, multiplexers 30 and 3, a group of elements AND 32 and 33,

The pac-TN block (fig.Z) contains differentiators 34 and 35, ftopNMpOBaTenb 36 inverse IC pulses triggers 37, 38 deimefrator 39,

The touch control unit (Fig. 4) contains a 1SOLUT 40, a first 41 and a second 42 inverters, a signal formaker 43.

The device works as follows:

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 After switching on, the signals at the outputs of blocks 7. and 8 are absent, the reversible counters 9 and 10 are in an arbitrary state, and the video signal source 22 begins to generate a full video signal, frame and horizontal sync pulses. The latter are fed to the input of the clock generator 18 and the counter 19 lines. After the clock generator 20 is energized by an input clock pulse, it begins to generate pulses determining the X-axis discretization (within the line) and input to the counter 17 at the moment when the digital codes at the outputs of the reversing counter 9 and the counter of 19 lines, the reversible counter, match. 10 and the counter 17 at the inputs of the blocks 11, signals are generated, determining the beginning of the formation of the marker by corresponding axes and arriving at the inputs of the block 13 of the formation of the marker. To the third input of block 13 a square wave is produced, produced by trigger 12, to the input of which, by connecting to the corresponding output of video signal source 22, frame sync pulses are received. Thus, the positive signal level at the input of block 13 corresponds to the period of the odd field of standard television interlaced decomposition.

The signal from the output of the Y-match block 11, post-entry to the input of the imager 23, determines the beginning of the formation of the marker within the frame (Y-axis), the formers 23 and 26 pulses in Y, connected through the inverter-differentiator 25, form two pulses of duration - type the lines so that the beginning of the first one is determined by the arrival of the signal from the output of the block. 11 matches Y, and its falling edge determines the beginning of the formation of the second pulse at the output of the driver 27.

Thus, the pulse at the output of the former 23 defines the upper half of the marker, and the pulse at the output of the former 27 defines the lower half. Both of these signals are combined by an OR element 29, the output of which determines those lines of a television frame within which a marker is to be formed.

The signal from the output of block 11, coinciding with X is fed to the input

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the body of pulses is 24 along X and determines the beginning of the formation of the marker within the line (along the X axis). Similar to the procedure for forming a marker along the Y axis, the formers 24 and 28 connected via an inverter-differentiator 26,. two pulses with a duration of eight elements are formed so that the trailing edge of the first one determines the beginning of the formation of the second, i.e. The pulse at the output of shaper 24 defines the left half of the marker, the pulse at the output of shaper 27 is the right. The control inputs of the multiplexer 30 and 31 receive a meander that determines the parity of the interlaced television decomposition floor, and the information inputs of the multiplexers 30 and 31 are connected to the outputs of the shapers 24 and 28 pulses in X so that, with an odd field, the output of the multiplexer 30 produces a signal corresponding to the left half of the marker, the output of the multiplexer 31 is the right half of the marker, and with an even field: the output of the multiplexer 30 is the signal of the right half of the marker, the output of the multiplexer 31 is the signal of the left half of the marker, and the procedure of the formation of the marker is completed by the logical-multiplication of the signals determining its position in rows and columns by means of the elements 32 and 33.

When the field is odd, the signal at the output of the AND 32 element determines the right half of the marker, and at the output of the AND 33 element the left half of the marker. With an even field, the signals at the output of the element And 32 determine the left half of the marker, at the output of the element And 33 - the right half of the marker. These signals are fed to the mixer 20, the third input of which is connected to the source of the video signal 22. Through the mixer 20, the signals at the inputs of the elements 32 and 33 are mixed into the video signal in such a way that the signal at the output of the element 32 determines the suppression of the video signal (blackening of the screen) And the signal at the output of the element And 33 - the illumination of the screen. The video signal with the mixed signal of the marker is fed to the input of block 21. At the same time, along with an arbitrary grayscale image determined by the source of the video signal 22 on the screen of the block 21, a dry marker is displayed.

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consisting of left and right halves. Within an odd half-frame, the left half of it is light, the right is dark, and within an even half-frame, the illumination of the half is inverse. Such a marker is clearly visible on any background, and its location on the screen is determined by the state of the reversible counters 9 and 10.

Two contacts are fixed on the puller of 15 coordinates. At the first, a zero potential is applied, and the second is connected to the input of the switch 40 by means of a touch switch. Sen-g weed switch assembled on a field-effect transistor according to the circuit with a common source. A constant negative voltage is applied to the source of this transistor, which also through the resistance of the order of several mega-ohms is applied to the gate. A constant positive voltage is applied to the drain of the transistor, through a resistance of the order of a few kilo. The gate of this transistor is connected to the second contact of the puller of 15 coordinates, in the initial state the transistor is closed and a positive level signal is present on its drain, which is simultaneously the output of the key 40.

The essence of the accelerated movement and removal of coordinates is as follows. When a finger touches two contacts simultaneously, attached to the puller of 15 coordinates, a zero potential is applied to the gate of the transistor on which the key 40 is assembled. The transistor opens and the voltage across its drain, which is the output of switch 40, changes from a positive level to zero. Thus, the switch 40 is switched. The presence of two contacts eliminates the false alarms of the block 14 as a result of accidentally touching one of the indicated contacts, therefore the introduction of a new block practically does not reduce the reliability of the device.

Since, after switching on the device, the reversible counters 9 and 10, determining the position of the marker on the CRT screen, are in an arbitrary state, the marker accordingly occupies an arbitrary position on the CRT screen. To move the marker tv. Point of the beginning of the acquisition of information, you need to bring the puller 15 coordinates to this point and simultaneously touch

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the finger of the contacts fixed on it, the Seal at the exit of the 15 k6-ordinate puller, which appeared at the moment of passing the CRT beam in the region of its aperture, enters the input of the amplifier of the restrictor 1 and by means of the comparator 2 it converts into a binary signal suitable for processing logic blocks. This signal is applied to the second input of the signal driver 43; rewriting to another input which through the inverter 41 gives the key signal 40, and the third through the inverter

5 42 the clock signal 18. The purpose of this signal is to allow the generated rewriting signal to pass at the moment when the counters 9 and 10 are t0 in the steady state. The output signal of the imaging unit 43 allows the countering of the state of the counters by a parallel code to reversible counters 9 and 10, which determine the coordinates of the marc on the CRT screen.

during the next frame, the marker will be displayed on the screen at the location of the puller 15 coordinates. Since the state of the counters 9 and 10 determines the coordinates of the marker, the signals from the outputs of the latter can be used to enter the computer.

The procedure for determining the direction of movement of the marker is simple, because if the puller aperture deviates 15 coordinates from the center of the marker in the horizontal direction, its aperture corresponds to either the right or left half of the marker, and at the output of the comparator 2 there is a signal only in the period of one1 of the fields or odd) through line scan. If the signal is present within an odd field, then the output

The d-element And 5 produces an offset signal to the left, and vice versa, if the signal at the output of the comparator 2 is present during the even-field period, then the output of element 6 also produces an offset signal to the right, since the second inputs of the elements 5 and 6 are connected respectively to the forward and inverse outputs of trigger 12. Block 8 implements the storage of the control signals of the marker offset until the end of the full frame and the excitation of the forward or inverse inputs of the reversible counter 10 within the frame sync pulse of an even field. Signals coming

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The inputs of block 8 are recorded in flip-flops 37 and 38. Differentiator 34 selects the leading edge of the meander field from the output of trigger 12 and starts the inverter 36, which generates a zero potential at the first input of the decoder 39 over 5 television lines within the frame sync pulse. the remaining inputs of which are received from the outputs of the flip-flops 37 and 38. The decoder 39 performs the role of a logic element realizing the operation of exciting one of the inputs of the block 8 during the frame sync pulse, provided that the second exit cannot be excited. More precisely, if a signal is present at only one of the outputs of the trigger 37 or 38, then the corresponding output of block 8 is excited during a vertical clock pulse. If the status of the triggers 37 and 38 are the same (the light pen is outside the marker area or its aperture coincides with the center of the marker), the signals at the outputs of block 8 are absent. The differentiator 35 injects the trailing edge of the inverse pulse from the output of the imaging unit 36, by means of which the triggers 37 and 38 are reset.

Thus, when the puller aperture is shifted 15 coordinates relative to the center of the marker to the left, due to the presence of a signal from the puller 15 coordinates in only one of the fields, the state of the reversible counter 10 decreases by 1 and in the next frame the marker will be formed 1 element to the left.

The procedure for controlling a marker within a frame (along the Y axis) is completely similar to that considered. When the aperture of the puller 15 is displaced relative to the center of the marker vertically, the signal at the output of the comparator 2 is present only during the formation of one of the halves (upper or lower) of the marker, information about which comes in the form of signals from the corresponding outputs of the forming unit 13 marker, Naprimed, if the aperture of the puller 15 coordinates is shifted up relative to the center of the marker, then the signal at the output of the AND 3 mix

there is upwards, - at the output of downstream block 4 - is absent. The state of the outputs of the And 3 and 4 elements is recorded in block 7, the first output

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which, within the frame sync pulse, drives the inverse input of the reversible counter 9, its state is reduced by 1, and in the next frame a marker will be formed above.

Claims (1)

Invention Formula A device for reading graphic information from a cathode ray tube (.RT) screen, containing an amplifier-limiter, the input of which is connected to the first output of the coordinate remover, the input of which is optically connected to the screen of a CRT, and the output of the amplifier-limiter is connected to the comparator information input, the output of which is connected to one input of elements AND of the first group, the other inputs of which are connected to the corresponding outputs of the block of formation of the marker, trigger, the counting input of which is the first clock input device, and the direct output is connected to the control input of the block forming the marker, the second group of elements I, whose inputs are connected to the output of the comparator and with the corresponding outputs of the trigger, blocks of memory, the synchronizing inputs of which are connected to the outputs of the corresponding elements of the first and second groups , the control inputs are connected to the forward trigger output, and the outputs are connected to the summing and subtracting inputs of reversible counters, the outputs of which are connected to one informational inputs of the corresponding blocks The other information inputs of which are connected to the first and second outputs of the synchronization unit, respectively, and the coincidence blocks are connected to the information inputs of the marker generation unit, the outputs of which are the information outputs of the device, and the synchronization input of the synchronization unit is the second synchronization input of the device, differing from The fact that, in order to improve speed, it contains a key, the input of which is connected to the second output of the puller, the first inverter, the input of which o connected. to the exit key ,. the driver of the signals, the first input of the KOTopoi o is connected to the output of the first inverter, the second input is connected to the output of the comparator, and the output is connected to the clock inputs of the reversing device 9161575910 The number of counters, whose information inputs are connected with the third output of which are connected to the first and second synchronization blocks, and the output to the output outputs, the synchronization block, correspond to the third input of the driver, and the second inverter, the input signals. - g eight YU i-j. J- VyhZ Vl.1 25h-h 27 Bx.Z 2 " guv L. 3 20 7 / five shn /five Fiel C.Vyh / j; 29 3} Jj PTJ  yb / x / .g Fig.Z Yal .; AT 2 IN FIG. 3 Lb