SU483667A1 - A device for obtaining graphic images on the screen of a cathode-ray tube (CRT) - Google Patents

Description

one

The invention relates to the field of computing techie and can be used in devices for displaying graphic information when creating a system of interactive graphic interaction between humans and computers.

There are known devices for graphic graphical imaging on a CRT screen, containing a CRT, connected to serially connected deflection coils and summing amplifiers connected to the outputs of digital-to-analog converters and multiplying digital-analog converters, logic unit connected to the inputs of sine-cosine generator , analog keys and sawtooth generator.

A disadvantage of the known devices is the lack of accuracy and, consequently, poor image quality, due to the spread of amplitudes and durations of the generators and digital-to-analog converters.

In order to improve image accuracy, the proposed device contains a reference voltage source connected to digital-to-analog converters and generators, and the outputs of the generators are connected via analog keys to the inputs of multiplying digital-analog converters.

The block diagram of the proposed device is shown in the drawing.

The device includes a logic unit 1 connected to the generator start inputs

a sawtooth voltage 2, a sine-cosine generator 3, and with control inputs of analog switches 4-9. The output of the signals of the positive polarity of the generator 2 through an analog key 4 is connected to the analog

the input of the multiplying digital-to-analog converter 10, and through the key 5 - with the input of the multiplying digital-analog converter 11. The output of the signals of negative polarity

through the key 6 is connected to the input of the converter 10, and through the key 7 to the input of the converter 11. One output of the generator 3 through the key 8 is connected to the input of the converter 10, and the other through the key 9 to the input of the converter 11.

The digital inputs of the converter 10 are supplied with bits of the code AU, Rz, and the digital inputs of the converter I - bits of code A, 1.

The output of the converter 10 is connected to the inputs of the summing amplifier 12, to the second input of which the output of the digital-to-analog converter 13 is connected, to the digital inputs of which the bits of the code of the initial coordinate of the EI are fed. Converter II output

connected to the input of the summing amplifier 14, to the second input of which the output of the digital-to-analog converter 15 is connected, to the digital inputs of which the bits of the initial coordinate coordinate code Xo are connected.

Top) The Clusters of the 12 and 14 are connected to the external coils 16 of the CRT 17.

A source of reference voltage 18 is connected to generators 2 and 3 and converters 13 and 15.

The device works as follows.

The digital inputs of the converters 13 and 15 from the storage device or the digital computer are given the value codes and FO, and the inputs of the converters 10 and 11 are fed to the value codes of linear increments A and DK or the value codes of the semi-axes of the ellipse Ri and (for circumference.

The logical block provides the permit potential for any pair of keys 4, 5, 6, 7, depending on the signs of the increments AX and AF. In the case of drawing an ellipse, the resolving potential is applied to keys 8 and 9. Then the logic block sends a start pulse to generator 2 or 3.

The amplitudes of the signals from generators 2 and 3 are automatically maintained equal to the reference voltage of the source 18 using analogue comparison circuits that are part of the generators. The output signals of the fixed amplitude from generators 2 and 3 pass through open analog switches to the analog inputs of converters 10 and 11, the multiplication factor of which can vary from 0 to 1 depending on the codes and data on the digital inputs. The received signals are summed by the amplifiers 12 and 14 with the signals of the converters 13 and 15, which carry out the operation of multiplying the reference voltage level of the source 18 by a factor varying from 0 to 1 depending on the code values applied to the digital inputs.

The summed signal after gain in power enters the deflection coils of the CRT, causing, in the case of plotting, the direct movement of the beam from the point with coordinates o and FO to the point Xc + AX, Yo + AY (the increment signs are set from a logical blockaj. In the case of an ellipse, the point with coordinates Xo, VO is the center, and the values of i and Rz determine the magnitudes of the semiaxes. Due to the fact that the device uses a single sawtooth generator for channel X to Y, the possibility of breaking or breaking the drawn lines is eliminated. The difference between constant time and integrator amplitudes, which is the case when using individual integrators

for channel X and channel Y.

The use of a single source of reference voltage ensures a strict proportionality of the amplitudes of the signals of the generators and transducers, which allows

drawing, with the required accuracy, images consisting of consecutively connected segments without visible distortions in places of separate segments.

Subject invention

A device for obtaining graphical images on the screen of a cathode ray tube (CRT), containing a CRT, connected with series-connected deflection coils and summing amplifiers, connected to the outputs of digital-analog converters and multiplying digital-analog converters, logic unit connected to the sine inputs cosine generator, analog switches and a sawtooth generator, characterized in that, in order to improve image accuracy, it contains a reference voltage source connected to digital-to-analog converters and generators, and the outputs of the generators are connected via analog switches to the inputs of multiplying digital-analog converters.