JPS648824B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for displaying analog waveforms using an XY matrix display method (a method for displaying a CRT surface as number of vertical raster lines×horizontal dots).

Conventionally, when displaying analog waveforms on a CRT (cathode ray tube) as a memory scope, the following two methods have been used.

(b) A direct method in which an electron beam is deflected electrostatically or electromagnetically using a signal that is directly time-converted in the horizontal and vertical directions.

(b) Assuming a raster on the CRT screen, divide the horizontal and vertical directions into pixels, write "0" and "1" into the memory corresponding to each pixel, and display the analog waveform as the sum of the pixels. Y matrix method.

In method (a), since a deflection signal is directly applied, the movement of the electron beam can be displayed continuously by using an appropriate smoothing means, and because the displayed waveform looks smooth, it is used in many analog waveform display devices (e.g. electrocardiogram waveform, etc.). It is used for various memory scopes such as blood pressure waveforms).

Method (B) is often displayed together with text, graphs, etc., but if analog waveforms can be displayed with the same level of image quality as method (B), method (B) It has the following advantages compared to

Low power consumption.

Large CRTs can be used.

Multicolor CRTs such as R, G, and B can be used.

Characters and graphs can be displayed simultaneously.

However, when displaying analog waveforms using method (b),
As seen in Japanese Patent Application Laid-open No. 159270 (1983), all conventional methods have attempted to display pixels as one dot, but when there is data to be displayed at the boundary between pixels, the following method is used: There is a problem.

FIG. 1 is an explanatory diagram showing this relationship. In the figure, white circles indicate the positions of displayed dots, black circles indicate the positions of dots to be displayed, and triangular marks indicate the positions of dots interpolated as described below. Now, assuming that the resolution in the horizontal X direction is k, the effective screen length in the X direction of the CRT is H, and the number of pixels in the X direction is N, the following equation holds true.

k=Hmm/N [mm/DOT] On the other hand, regarding the time relationship, the horizontal scanning period is h, the retrace period is f, and the readout time of one dot is a.
Then, the following formula holds true.

a=h−f/N [S] Therefore, if the number of pixels N is increased in order to reduce the resolution k, a becomes smaller. That is, the readout time per dot becomes shorter. If a is to be kept constant and k is to be a satisfactory value, h−f must be increased. Here, if the repetition period of one screen is F and the number of raster lines is L, then F=(h-f)・L, so if h-f is large, F will also be large,
This appears as a flicker on the screen.

From the above relationship, it can be seen that in order to improve the resolution k, N must be increased and a must necessarily be decreased. However, in order to reduce a, there are constraints such as a limit to the data read speed of the memory corresponding to the pixel and an increase in the number of memories used in h-f. It is difficult to achieve this goal.

Next, a method for interpolating the discontinuities between the dots shown in FIG. 1 will be described. For example, in Japanese Patent Application Laid-Open No. 152822/1982, interpolation for discontinuous waves is performed in units of dots, as shown in FIGS. 2 and 3. This method places the interpolation dot at the position of the triangle mark, so although it is not so important in the case of Fig. 2, it is not so important in the case of Fig. 3 because the actual position to be displayed is the black circle mark. It has to be a natural display. This is because there is a limit to the resolution in the horizontal direction, and the only way to solve this problem is to improve the resolution as described above.

However, method (b) has the following disadvantages compared to method (b). That is, the amplitude and position of an analog display waveform can be easily adjusted by directly adjusting the waveform to be deflected using the direct deflection method, but the amplitude and position can be adjusted using the input A/D using the XY matrix method. It is necessary to take measures such as changing the data before inputting it into the converter, storing it once in an auxiliary memory, and adding display coefficients and the like when displaying the data and storing it in the display matrix memory (video RAM). In this case, when enlarging or reducing a transient signal, it must be input again from the A/D converter, and these requirements cannot be met. In this case, an auxiliary memory is required in addition to the matrix memory for display, and since processing is performed using coefficients, the configuration becomes complicated and expensive.

Furthermore, in the method (b), when displaying on a color CRT, a coloring memory is required for each pixel in order to color each pixel. For example, if the number of colors to be expressed is 8, 3 bits are required, so an integral multiple of the memory required to display the entire screen is required.

Note that when displaying analog waveforms, it is necessary to sequentially and continuously display new data on the screen, and conventionally the following two methods have been mainly used.

(i) A display method in which waveforms are recorded continuously on recording paper.

(ii) A display method in which discontinuous points are moved on the screen by sweeping them like a monitor oscilloscope.

Method (ii) is easy, as it is sufficient to sequentially replace the corresponding dots with new data when rewriting the screen. However, method (i) requires rewriting the entire screen, so
It requires measures such as alternate display using memory, which is complicated and not easy.

The present invention aims to provide a raster scan CRT analog waveform display device that eliminates all of the above-mentioned problems. A feature of the present invention is that by using a novel video pulsing circuit, an analog signal waveform can be displayed as a smooth shape on a raster scan CRT display device. Hereinafter, the present invention will be specifically explained with reference to the drawings.

FIG. 4 is a block diagram showing an embodiment of the present invention. In the figure, 1 is an analog signal input terminal;
2 is an analog-to-digital converter, 3 is a write control circuit, 4 is a waveform memory, 5 is a read control circuit, and 6 is a digital-to-analog converter, which are the same as the conventional direct method as shown surrounded by broken lines. be. In the figure, only one channel is shown for simplicity. The analog signal read out from the waveform memory 4 during the horizontal period is smoothed by a smoothing circuit 7 using a low-pass filter and applied to a video pulsing circuit 8. The video pulsing circuit 8 converts an analog signal into a video pulse unique to the present invention as described later, and supplies its output to the CRT 9. Reference numeral 10 denotes a sampling pulse generation circuit that generates sampling pulses from the output of the clock pulse generator 11 to control the A/D converter 2 and the write control circuit 3. 12 and 13 are circuits for generating horizontal and vertical synchronizing pulses from the output of the clock pulse generator 11, respectively.

FIG. 5 is a waveform diagram for explaining the operation of FIG. 4.
FIG. 5A shows an analog signal waveform applied to the input terminal 1, and its duration, for example, T seconds, is stored in the waveform memory 4. FIG. 5B shows the output waveform of the D/A converter 6, which is the waveform of FIG. 5A read out at time (hf). FIG. 5C shows a waveform (reproduced waveform) obtained by smoothing the waveform in FIG. 5B.

FIG. 6 shows a video pulsing circuit 8 used in the present invention.
FIG. 2 is a block diagram showing one example. 7 to 9 are waveform diagrams for explaining the operation. A○ to i○ in FIG. 6 indicate locations where waveforms a to i in FIGS. 7 to 9 appear. In FIG. 6, the smoothed output waveform shown in FIG. 5C is applied to the input terminal 14.
This input waveform is compared with different reference signal waveforms in the first comparator 15 and the second comparator 16, respectively. One of the reference signal waveforms is i in FIG.
A staircase wave as shown in FIG. 1 is generated by the counter 20 and the D/A converter 19. The counter 20 counts every horizontal synchronization pulse applied to the count terminal C, and is reset every time the vertical synchronization pulse is applied to the reset terminal R. Since the number of steps of this staircase wave is determined corresponding to the raster line on the screen, the level (0, 1, 2, . . . ) of each step is called a raster level. That is, the reference signal waveform i supplied to the first comparator 15 has a level that changes sequentially one step at a time in horizontal synchronization. The other of the reference signal waveforms is level-shifted by, for example, one step by the level shifter 17 (9th
g) in the figure, is supplied to the second comparator 16. 18
is also a level shifter, but we will discuss this later. Here, the number of level shifts determines the line thickness of the displayed waveform, but it is not necessarily 1.
It doesn't have to be a step.

Now, assuming that the input waveform is a triangular wave, and comparing it with the raster level in FIG. 9, it becomes as shown in FIG. 7A. When the reference raster level input to the first comparator 15 is 0, the peak of the triangular wave does not reach this level, so the output of the first comparator 15 is 0 (a in Figure 7B). . On the other hand, the second comparator 1
6 produces a short pulse because if the number of steps in the level shifter 17 is 1, the raster level is 1 (FIG. 7B, b). This b
The pulses are applied to exclusive OR circuits 21, 22 and delay circuit 23. Here, the delay circuit 23 is a circuit that provides a constant delay time τ to a pulse having a constant pulse width or more. Since the b pulse does not reach its constant pulse width, the delay circuit 23 produces no output (FIG. 7B d). Therefore, the exclusive OR circuits 21 and 22 output the same pulse as the b pulse (c, e in FIG. 7B). Therefore, the output of the OR circuit 24 that modulates the brightness of the CRT9 electron beam will also be as shown in f in FIG. 7B, and the corresponding bright spot will be
It appears on the CRT9 screen (bright spot on line 1' in Figure 7D). Lines 0', 1', 2', 3' in Figure 7D,
. . . indicates raster lines corresponding to raster levels 0, 1, 2, 3, .

Next, when the raster level input to the first comparator 15 becomes 1, the first comparator 15 produces a pulse that is the same as the b pulse of FIG. 7B (FIG. 7C, a).
At this time, since the raster level to the second comparator 16 is 2, a pulse shown at b in FIG. 7C is generated. Therefore, the output of the exclusive OR circuit 21 becomes the pulse shown in c in FIG. 7C. The output of the second comparator 16 is the seventh
It is applied to the exclusive OR circuit 22 together with the pulse shown at d in FIG. 7C, producing the pulse shown at e in FIG. 7C at its output. The c pulse and e pulse in FIG. 7C pass through the OR circuit 24 and become the pulse shown in f in FIG. 7C. This f pulse is the 7th pulse on the CRT screen.
This results in a bright line as shown on line 2' in Figure D. Similarly, a triangular waveform as shown in Fig. 7D is created.
Displayed on CRT screen. In reality, the thickness of the line indicating the waveform will be thinner than in the diagram.

When the input waveform is a square wave, it becomes as shown in FIG. In this case, the output of the exclusive OR circuit 21 becomes 0 as shown in c of FIG.
The second comparator 16, delay circuit 23, and exclusive OR circuit 22 correct the signal as shown in FIG. 8D.
In this case, the waveform component in the raster direction is 1' in D of the same figure.
It should be noted that they are displayed continuously as shown on the line.

Furthermore, as a means to improve the resolution in the vertical direction, an interlacing method is usually adopted. Even in this case, the analog waveform signal that has passed through the D/A converter 6 and the smoothing circuit 7 as described above is
Since it is continuous in the vertical direction, this method can be easily applied. For example, by adding the flip-flop 25 shown in FIG. By adding every other vertical synchronization signal to the reference staircase wave generation circuit (in Fig. 6, it is added to the reference signal of the D/A converter), it is possible to obtain video pulses in an interlaced raster. .

Although the above description has been made regarding the case where the reference signal waveform is level-shifted, the input waveform may also be level-shifted. In this case, level shifter 18 is connected as shown in FIG. However, one more amplifier is required.

Furthermore, if it is desired to display waveforms in multiple channels such as R, G, and B using a color CRT, the configuration is easy because the video signal is already pulsed as described above. In this case, the priority order when waveforms are simultaneously displayed at the same position can be easily determined because the pulses are generated for each channel. For example, an AND gate or an inverter can be used to set the priority order as channel 1 (red)>channel 2 (green)>channel 3 (blue).

As is clear from the above explanation, according to the present invention, the following remarkable effects can be obtained.

(a) Unlike a dot matrix, the displayed analog waveform is continuous, so horizontal resolution is improved.

(b) Due to smoothing, the waveform becomes continuous and no special interpolation is required.

(c) Adjustment of the amplitude and position of the displayed analog waveform:
It is simple and requires only analog circuits.

(d) Since the video pulse waveform is output for each channel, multicolor display is possible with a simple configuration.

(e) The overall circuit configuration is simpler and cheaper.

(f) Waveform display mode can be made equivalent to conventional memory scope.

Note that the present invention is not limited to the above-described embodiments, and can be modified and changed in various ways without departing from the gist of the invention as set forth in the claims.

[Brief explanation of the drawing]

1 to 3 are explanatory diagrams showing a conventional example, FIG. 4 is a block diagram showing an embodiment of the present invention, and FIG.
FIG. 6 is a waveform diagram for explaining the operation; FIG. 6 is a block diagram showing an example of the video pulsing circuit used in the present invention; FIG.
~FIG. 9 is a waveform chart for explaining the operation. 4...Digital memory, 5...Reading control circuit, 6...Digital-to-analog converter, 7...
Smoothing circuit, 19, 20...Reference staircase wave generating means,
17, 18... Level shifter, 15... First comparing means, 16... Second comparing means, 21... First exclusive OR circuit, 22... Second exclusive OR circuit, 2
3...Delay circuit, 24...OR circuit, 9...
CRT.

Claims (1)

[Claims] 1. Digital-to-analog conversion means for converting a signal read from a digital memory into an analog signal, means for generating a reference staircase wave whose level changes sequentially in raster synchronization, and the reference staircase. means for shifting the level of the wave by one step or an integral multiple thereof; first comparison means for comparing the analog signal and the reference staircase wave; and second comparison means for comparing the analog signal and the shifted reference staircase wave. a first exclusive OR circuit which receives the outputs of the first and second comparison means; and a second exclusive OR circuit which receives the output of the second comparison means and the delayed output of the second comparison means. an exclusive OR circuit, an OR circuit receiving the outputs of the first and second exclusive OR circuits as inputs, and means for modulating the brightness of an electron beam of a CRT to be raster scanned based on the output of the OR circuit. scanning
CRT analog waveform display device. 2 Digital-to-analog conversion means for converting the signal read from the digital memory into an analog signal; means for generating a reference staircase wave whose level changes sequentially in raster synchronization; and means for converting the level of the analog signal into the reference staircase wave. means for shifting the level-shifted analog signal by one step or an integer multiple thereof; first comparing means for comparing the analog signal and the reference staircase wave; and second comparing means for comparing the level-shifted analog signal and the reference staircase wave. Comparison means and the first and second
a first exclusive OR circuit whose input is the output of the comparison means; a second exclusive OR circuit whose inputs are the output of the second comparison means and the delayed output of the second comparison means; A raster scanning CRT analog waveform display device comprising: an OR circuit that receives the output of a second exclusive OR circuit; and means for modulating the brightness of an electron beam of a CRT that is raster scanned based on the output of the OR circuit.