JPS5822752B2 - Arc signal generation method - Google Patents

Description

[Detailed Description of the Invention] When handling graphic information in a computer etc., the present invention
Deflection signal generation method required when displaying on a graphic display device such as RT or XY recorder % formula % Conventionally, this type of method is known to generate a circular signal using an analog integrator. (For example, see Japanese Patent Publication No. 47-31660.) However, in order to display a circular arc using such a conventional method, it is necessary to detect which position on the circumference the generated circular signal is specifying at a certain point in time. In other words, it is necessary to detect the phase of the sine wave generated as a circular signal.

However, in order to perform this phase detection, means such as detecting the amplitude of the sine wave output signal and determining the phase from the amplitude are required, and accurate phase detection has been difficult in practice.

The present invention has been made in order to solve the above-mentioned problems in the conventional method, and allows phase detection to be easily performed by digitally counting lock signals.
This makes it possible to accurately display any circular arc.

Hereinafter, the contents of the present invention will be explained in detail with reference to illustrated embodiments.

In the figure, 1 and Q2 are registers for holding the starting point coordinate data of the arc given from the outside (for example, a computer), and 3 and 4 are registers for storing the numerical data stored in registers 1 and 2, respectively. Digital-to-analog conversion circuit (DA conversion circuit) for converting into electrical signals
It is.

Reference numeral 5 designates a clock signal generation circuit that generates a number of clock signals corresponding to the central angle of the arc based on the central angle data of the circular arc (or the start point coordinate data and end point coordinate data of the circular arc also given from the outside). be.

6 and 7 sample the input analog electrical signal according to the clock signal output from the clock signal generation circuit 5;
This is a sample and hold circuit that has the function of temporarily holding the value and outputting it as an output signal.

8 and 9 are coefficient multipliers (potentiometers) each having a function of attenuating a human-powered analog electric signal at a preset ratio and outputting it as an output signal, and 10 and 11 each have a function of adding or subtracting a plurality of analog electric signals. This is an addition/subtraction circuit with

12 and 13 are switch circuits each having a function of selecting one of the two analog input signals and guiding it to a deflection circuit (not shown) as an X-white signal and a Y deflection signal, and 14 is a rank signal. This is a data line for guiding central angle data (or starting point coordinate data and ending point coordinate data) of a circular arc to the generating circuit 5.

Now, register 2 contains the starting point coordinates X of each arc.

, YO are set, and the switch circuit 12.
13 are connected to the DA conversion circuits 3 and 4, respectively.

In this state, the X deflection signal X(t), the Y deflection signal Y
(1) are respectively X(o)-X.

, Y(.)=Yo. It is also assumed that central angle data of a circular arc (or starting point coordinate data and ending point coordinate data) is input to the clock signal generation circuit 5 through the data line 14.

Next, a clock signal is generated from the clock signal generation circuit 5, and after this is applied to the sample and hold circuit 6.
Switch to the 0.11 addition/subtraction circuit side.

Here, the sample and hold circuit 6゜7 samples the input analog voltage at the time when the clock signal is applied from the clock signal generation circuit 5, and then keeps the output voltage at that value until the next clock signal is applied. continue to hold.

Therefore, the outputs of the sample and hold circuits 6 and 7 are respectively the starting point coordinates X of the circular arc.

, Yo, and if the coefficient of the coefficient unit 8゜9 is set to 1/, then
The X direction signal X(
1'), Y deflection signal Y(1) is 1 X(1)=X(,--"Y(, Y(1)=Yo+H'X
o(1゜=X(0)−-”Y(0)=Y(0)
+ii'X(Q).

However, it is assumed that the addition/subtraction circuits 10 and 11 are constructed to have the function of realizing the above equation.

Thereafter, when clock signals are sequentially applied to the sample and hold circuits 6 and 7 in the same manner, the deflection signals X(i) and Y(i) after adding the first clock signal become as follows.

This formula represents the coordinates on the circumference centered on the origin and passing through (Xo, Yo).

That is, 1, ΔY ΔX X Y (5) Therefore, equation (5) is nothing but a differential equation of a circle.

Therefore, first, the starting point coordinates of the arc (xo tYo )
When held in registers 1 and 2, both X and switch circuit 12
, 13 are connected to the side of the DA conversion circuits 3 and 4, and then the clock signal generation circuit 5 generates a clock signal.
By switching to the side, the origin is the center and the coordinates (
The coordinates of each approximate point, which are required when a circle or an arc starting from Xo, Yo) is approximately displayed as a sequence of points, can be obtained as analog electrical signals from time to time.

In this case, the clock signal generation circuit 5 is configured to output a number of clock signals corresponding to the central angle of the arc, and then stop its operation.

From this ζ'', a designated arc centered on the origin and starting at the coordinates (Xo, Yo) will be displayed on a graphic display device such as a CRT.

Note that the illustrated configuration merely shows one embodiment of the present invention, and the present invention is not limited thereto.

For example, the X and Y deflection signal outputs may be taken out as the outputs of sample and hold circuits 6 and 7.

As explained above, according to the present invention, a deflection signal required when displaying an arc given from the outside as starting point coordinates and center angle information (or end point coordinates) on a graphic display device such as a CRT can be easily generated. This can be easily obtained with a circuit of this configuration.

Furthermore, since the sequence of approximate points of the arc specified by the deflection signal obtained using the method according to the present invention is approximately aligned on the given arc, it is possible to display a smooth and beautiful arc when displayed on a CRT or the like. In this case, since phase control is performed by counting clock signals, there is an advantage that an accurate arc can be displayed.

BRIEF DESCRIPTION OF THE DRAWINGS The figure is a configuration diagram of an embodiment of the present invention. 1.2...Register, 3,4...DA
Conversion circuit, 5... Clock signal generation circuit, 6,
7...Sample hold circuit, 8,9...
...Coefficient unit, 10, 11... Addition/subtraction circuit, 12, 13... Switch circuit, 14...
...Input data line.

Claims (1)

[Claims] 1. In an arc signal generation method for obtaining a deflection signal for displaying an arc on a graphic display device, a clock signal generation circuit that generates a number of clock signals corresponding to the central angle data of the arc; first and second sample-and-hold circuits that each sample and temporarily hold an analog electrical signal representing the Y deflection signal; first and second coefficient multipliers that attenuate the output of each sample-and-hold circuit at a constant rate; a first addition/subtraction circuit that adds or subtracts the output of the first sample-and-hold circuit and the output of the second coefficient multiplier connected to the second sample-and-hold circuit and feeds it back to the first sample-and-hold path as an analog electrical signal; a second sample-and-hold circuit that adds or subtracts the output of the second sample-and-hold circuit and the output of the first coefficient multiplier connected to the first sample-and-hold circuit, and feeds it back to the second sample-and-hold circuit as an analog electrical signal;
As the X and Y deflection signals, an analog electrical signal corresponding to the starting point XY coordinate data of the arc is first given, and thereafter, the first and second addition and subtraction circuits or the first and second sample hold circuits are provided. An arc signal generation method characterized in that the output of a circuit is given.