SU1259302A1 - Device for reading graphic information from screen of cathode-ray tube - Google Patents

Abstract

The invention relates to the field of automation and anti-extremes technology, in particular to a device for reading graphic information from a CRT screen for its subsequent entry into a computer. The purpose of the invention is to improve the reading accuracy — achieved by forming on the CRT screen two vertical stripes spaced apart in adjacent half-frames and forming a bipolar microraster. The position of the light pen on the screen is monitored programmatically by analyzing the contents of the output register and calculating new coordinates of the left and right lanes. 2 Il. S JV CO & 9 Yu

Description

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The invention relates to automation and computer technology, in particular to devices for reading graphic information from a CRT screen, and can be used to organize the operative communication of a person with a computer.

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

FIG. 1 is a block diagram of the device; Fig. 2 shows a specific constructive implementation of the microraster forming unit.

The device includes a CRT 1

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on the basis of the CRT of the television indicator 5, the shaper 4 of the video signal causes the appearance on the screen of two vertical stripes spaced apart along two adjacent frames. When the aperture of the light pen 2 hits an arbitrary

The 20 position of either of the two bands, the selector 3 generates a pulse arriving at the first inputs of elements AND 8. This pulse records the current state of counter 6 into register 9, which determines the position of the light pen 2 on the screen vertically. At the same time, signals are being recorded from the outputs of the elements I I6 and 17 into register 10, which allow one to determine which of the two bands is captured. The contents of registers 9 and 10 are transferred to a computer. The register 10 at the end of each second frame is reset by the pulse generated by the one-shot 19, while the signal from the corresponding output of the trigger 18 controls the writing to the triggers of the register 0.

block, a 2-coordinate puller, made in the form of a light pen, a selector 3 of read signals, a shaper of 4 video signals, a generator of 5 pulses, the first -6 and second 7 counters, a group of elements AND 8, the first register 9, the output register 10, the forming unit 11 a microraster containing the first 12 and second 13 comparators, the second 14 and third 15 registers, the first 16 and second 17 And elements, trigger 18 and one-shot 19

The device works as follows.

The generator 5 produces pulses

high frequency corresponding to the required horizontal screen rasterization, which are fed to the input of the counter 6, the conversion factor of which corresponds to the television standard of the horizontal scanning time. The first output of the higher bit of counter 6 is connected to the input of counter 7, which recalculates the image lines in the frame and has a recalculation period corresponding to the duration of one television frame.

Shaper 4 forms a television video signal input to the indicator 1. Block 11 forms microrasters on the screen from two vertical bars spaced apart by two frames, with the left bar being formed in the first frame and right in the second frame. The positioning of both bands of the microraster is performed by recording their coordinates in registers 14 and 15 of the computer.

The output of counter 6 is connected to the inputs of comparators 12 and 13, which compare the current values of the X coordinate with the coordinates of the left and right

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0 The X coordinate of a point is calculated as the arithmetic average of the coordinates of the left and right bars by software. The position of the light pen on the screen is also monitored by analyzing the contents of register 10 and calculating the new coordinates of the left and right lanes — by adding or subtracting a unit from the previous coordinate value, which, after transferring them to registers 14 and 15, displaces the microraster bands by ± 1 point. Thus, the proposed device makes it possible to increase the accuracy of reading the coordinates up to the value of il point by introducing a microspace formation unit and registering them at the time of capturing the bands by the pen aperture.

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of bands that keep rmc in registers 14 and 15, respectively. When coordinates coincide, comparators 12 and 13 form pulses equal in duration to the glow of one raster point. These pulses arrive at the inputs of the AND elements 16 and 17, which are controlled by the trigger 18 in such a way that at the output of the AND element 16 a pulse from the comparator I2 appears in the first frame, and at the output of the element 17 the pulse from the comparator 13 in the second frame . The output pulses from the elements And 16 and 17, coming in

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0 The X coordinate of a point is calculated as the arithmetic average of the coordinates of the left and right bars by software. The position of the light pen on the screen is also monitored by analyzing the contents of register 10 and calculating the new coordinates of the left and right lanes — by adding or subtracting a unit from the previous coordinate value, which, after transferring them to registers 14 and 15, displaces the microraster bands by ± 1 point. Thus, the proposed device will improve the accuracy of reading the coordinates up to the value of il point by introducing a micro-shaping unit and registering them at the moment of capturing the bands by the pen aperture.

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Claims (1)

Invention Formula A device for reading graphic information from a cathode-ray tube screen, containing the first counter, the input of which is connected to a pulse generator, and the outputs are connected to the input of the second counter and to the input of the video signal generator, the other input is connected to the output of the second counter, and the output is connected to the input the indicator, a read signal selector, whose input is connected to the output of the coordinate remover, and the output is connected to one input of the elements AND of the group, the other inputs of which are connected to the outputs of the second counter, and one input of the first register, the other inputs of which are connected to the outputs of the corresponding elements of the AND group, and the outputs are the first output of the device, the first comparator, the inputs of which are connected to the outputs of the first counter and the second register, and the output connected to one input of the first And element, s o 5 0 five and the third register, while the inputs of the second and third registers are the first and second inputs of the device, respectively, in order to improve accuracy, it contains a second comparator, the inputs of which are connected with the outputs of the first counter and the third register, the output register, one input of which is connected to the output of the selector signal selector, and the output is the second output of the device, the second element And, one input of which is connected to the output of the second comparator, trigger connected to the output with etchika and outputs connected to respective inputs of the output register and the first and second AND gates, whose outputs are connected to respective inputs of the output register and shaper video signals, and a monostable multivibrator, koto- cerned input connected to an output flip-flop, and an output connected to a corresponding input of the output register. OmSjt.S OmSj) .7 2 Editor N. Yatsola Compiled by A. Romanov. Tehred M. Khodanich Proofreader T. Kolb Order 5124/48 Circulation. 671Subscribe VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Rauschska nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4