SU1179313A1 - Device for displaying information on screen of cathode-ray tube - Google Patents

Abstract

DEVICE FOR INFORMATION DISPLAY ON SCREEN ELEKTGONNOLUCHEVOY tube (CRT), comprising the coordinate scan amplifier X, scan amplifier according koorddiate Y and usili1el current dynamic focusing, the outputs of which are connected to the focusing-deflection CRT system, the first and second register outputs are soedineiy the inputs the first and second digital-to-analog converters, the code switch and the third and fourth digital-to-analog converters, t tS KoZ X, because, with a device speed-boosting circuit, it contains a series-connected code converter and a block squared, the output of which is connected to the information inputs of the first and second registers, the synchronization inputs of which and the control input of the code switch are the first input of the device, the CRT modulator is the second input of the device, the input A code conversion unit is connected to the output of a code switch, the first and second inputs of which are connected to the inputs of the third and fourth digital-to-analog converters and are respectively third and The fourth inputs of the device, the outputs of the third and fourth digital-to-analog converters are connected to the inputs of the sweep amplifiers in the X and H coordinates, respectively, the outputs of the first and second digital-to-analog converters are connected to the first and second inputs of the dynamic focusing current amplifier, respectively.

Description

I The invention relates to electronics and can be used in devices for displaying graphic or alphanumeric information. The aim of the invention is to improve the speed of the device. FIG. 1 is an electrical block diagram of a device for displaying information on a CRT screen; in fig. 2 and 3 are timing diagrams of the main signals of the device when displaying arbitrarily located points and lines (vectors, arcs, respectively. The device contains (FIG. 1) switch 1 codes, first and second registers 2 and 3, first and second digital to analog converters 4 and 5, Code conversion block 6, third and fourth digital-to-analog converters 7 and 8, scanner 9 for X, transmitter O for scanner 10, squaring unit 11 for dynamic focusing current amplifier 12, focusing-deflection system 13 , Uh T 14, inputs 15-18 of the device, outputs 1 and 20 of registers 2 and 3. The device operates as follows: From input 15 and 16 of the device to the inputs of digital-to-analog converters 4 and 5 are received by n-discharge code1l deflection of the beam to the coordinates X and Y. These codes convert digital-to-analog converters 4 and 5 into analog signals, the polarity of which is determined by the value of the sign bit of the input codes. Output signals from digital-analog converters 4 and 5 are amplified by current in amplifiers 9 and 10 sweep, the loads that are deflecting cat focusing-deflecting system flaps 13. The generated magnetic field, acting on the electron beam, causes it not to move to the addressable point of the CRT screen 14. The screen encoding of the ESh screen is such that the zero value of the code along the X (Y) coordinate corresponds to the bottom (left) point of the screen , the unit code value is the top (right) point, and the code value at which there is one in the highest code bit and zero in other bits corresponds to the center of the screen. With this encoding, the most significant bit of the code is significant, i.e. it indicates the direction of the dot’s position relative to the center of the screen, and the remaining bits define the amount of deviation of the beam from the center of the screen, and for 1 in significant bit, the least significant bits determine deviations from 3 centers in the forward code, and for O - in the additional one. The older m bits of the p-bit deviation codes also go to the information inputs of the switch 1 codes, to the control input of which the clock pulses go from the input 17 of the device. The switch skips to its output m higher bits of code X in the presence of 1 at its control input, and in the presence of O - m higher bits of the code Y. These codes alternately arrive at block 6 code conversion, which in the presence of 1 in sign bit the code arriving at its input skips the lower bits of the code to its outputs without changing, and if O is present, in the sign bit it inverts the lower bits of the code, 1. e. forms the reverse code. In order to build a code inverter, it is advisable to use logical elements ORIGINAL OR .. From the output of the code conversion block 6 (t − 1) - the discharge code l X and d Y, carrying information about the deviation of the beam from the screen center, goes to the erection block 11 into a square, which is expedient to perform in the form of a combinational circuit consisting of a matrix of elements And and binary adders. Depending on the logical state of the signal at input 17, at the output of the squaring block 11 and the associated inputs of registers 2 and 3 there is a value LH or L. Since the synchronization inputs of registers 2 and 3 are connected to input 17, at the moments of changing the logical state at this input information is recorded in the registers, and when the signal goes from 1 to O, the value of D X is written to register 2, and when the signal goes from O to G - write the value of register 3. Using digital-to-analog converters 7 and 8, codes and K and 4 Y are converted into unipolar analog signals, which are summed and amplified by amplifier 12 of the dynamic focusing current, the load of which is a coil focusing focusing-deflecting system 13. The current in the dynamic focusing coil is expressed by the dependence,:. where K, K is the constant of the coefficients; yX, Y are the deviations of the beam from the center of the screen along the corresponding coordinate axes.

The coefficients K and K are the transmission coefficients of the following circuit: input of a digital-to-analog converter 7 — output of a current focusing current amplifier 12 and input of a digital-analogue converter 8 an output of a current focusing amplifier 12, respectively. The installation of the necessary K and K coefficients is made by the corresponding variable resistors, the input of the cshmi to the amplifier 12 is the dynamic focusing current and changes its transmission coefficient on the first and second inputs. In the particular case with an ideal magnetic field of catuyli dynamic focusing should be taken

Only the rh most significant bits of the n-bit codes of the deflection are received at the inputs of the switch 1 codes, because for a qualitative display of information, it is sufficient to realize the dependence on dX and d Y with a precision of 1 -2%, which is achieved with m equal to 7 Or 8. The number of digits of the deviation codes n in modern display devices is 1. If accepted, this leads to an unreasonable, complicated device.

Let us consider in more detail the operation of the device in the following other modes: when addressing arbitrary points of the screen to which you need to transfer the beam to start displaying a sign or line, as well as in the process of displaying lines.

In the case of addressing arbitrary points of the screen, the subsequent coordinates of the position of the beam may differ from the previous ones by a sufficiently large value, up to 2 for each coordinate. In this mode, the illumination of the addressable point should be made only after the establishment of the deflection currents and the dynamic focusing current. The establishment time of the indicated currents is generally proportional to the magnitude of their change, and for modern display devices it can be several tens of microseconds.

Assume that, at time t (Fig. 2), such a change in deviation codes occurs at inputs 15 and 16, as a result of which the higher m bits are also used to obtain the dynamic focusing current. Since with logical 1 at output 17, code X passes through switch 1 of codes, then at time t, a clock pulse at input 17 changes state of outputs 19 of register 2 because a new value is written to it

1793134

jd X In the interval from t to t, when there is a logical O at input 17, the Y switch goes through switch 1 of codes. As a result, at time t, a leading state of the output pulse at input 17 causes a change in the state of outputs 20 of register 3, since the new value of Y is written into it. Subsequently, the contents of registers 2 and 3 do not change until the inputs

(About 15 and 16 will not receive a new value of X-codes and y.

As can be seen from FIG. 2, the delay in the formation of codes LH - and exceeds the period of the following clocks

J5 input 17, which must not be less than 2 times the propagation delay of the Sigal through switch 1, code conversion unit 6 and erection unit 11; in square.

2Q After the end of the transient processes in digital-to-analog converters 4.5 and 7.8, amplifiers 9, 10 and 12 current and focusing deviation system 13 in MOMeirr t from input 18 to a CRT modulator 14 nocTjTiaeT

5 pulse of illumination and pa screen CRT

the corresponding point is displayed. The required delay of the illumination of the lush signal relative to the moment of change of the deflection codes is provided by the external device. This delay can be either constant or variable. In the first case, the backlight delay value takes into account the maximum possible transition time in the display device, and in the second case, the required delay value is determined as a function of the current change of the reject codes.

When displaying lines (vectors, arcs), the deflection codes at inputs 15 and 16 change from value to value by the value of the youngest of n bits, and the illumination of the beam is performed continuously throughout the entire line display time.

As can be seen from FIG. 3, in this case, the codes at the inputs 15 and 16 change along the front of the clock pulses at the input 17. Suppose. that at times t and t2, a change in the bit codes does not change

the higher m bits appearing at the inputs of switch 1. In this ciiy4SiC, despite the change of the rejection codes, the codes X and the outputs 19 and 20 of registers 2 and 3 do not change, i.e. the dynamic focusing current will be unchanged. If at the time tj the higher bits of the deviation codes also change, then at the moments t and ty the contents of the registers 2 change

and 3, and a new current value d of focusing is formed. Since during the period of the following pulses at input 17, the X and Y codes change by the value of the lower ha bits, the delay in the formation of the dynamic focusing current by the period of the synchronizing pulses does not affect the focusing quality, since the current in the coil is dynamic

focusing is sufficient to maintain with an accuracy of 1-2%.

The application of the invention allows to create

From a display device on a CRT screen with a good resolution across the entire field of the screen, such devices are characterized by a small amount of equipment, the ability to work in a wide range

10 temperatures, high speed.

gI

II

Claims (1)

DEVICE FOR DISPLAYING INFORMATION ON THE ELECTRON BEAM TUBE (CRT) SCREEN, containing an X-coordinate sweep amplifier, a усилитель coordinate sweep amplifier, and a dynamic focus current amplifier, the outputs of which are connected to a focusing-deflecting CRT system, the first and second registers ^ outputs of which are connected to the inputs the first and second digital-to-analog converters, a code switch and the third and fourth digital-to-analog converters, characterized in that, in order to increase the speed of the device, it contains "The code conversion unit and the unit will be connected in series!" a square whose output is connected to the information inputs of the first and second registers, the synchronization inputs of which and the control input of the code switch are the first input of the device, the CRT modulator is the second input of the device, the input of the code conversion unit is connected to the output of the code switch, the first and second inputs of which are connected with the inputs of the third and fourth digital-to-analog converters and are respectively tre- ^; the fourth and fourth inputs of the device, the outputs of the third and fourth digital-to-analog converters are connected to the inputs of the scanning amplifiers in the coordinates X and Ύ, respectively, the outputs of the first and second digital-to-analog converters are connected respectively to the first and second inputs of the dynamic focus current amplifier. daZ ϊζηλ m S © sa, βνΛ & 9 .3 1179313 2