JPH073438B2 - Character / cursor display circuit - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a character / cursor display circuit for displaying characters, symbols, cursors, etc. along with a waveform of a signal under measurement in an oscilloscope. With the increasing number of channels, more functions, and higher accuracy of oscilloscopes, not only signal waveforms but also measurement conditions and measurement data, etc.
It is designed to be displayed on the surface of the cathode ray tube by characters, symbols, etc. However, in the case of more precise measurement, it is desirable to move the cursor to an arbitrary position of the signal to be measured for use. The present invention relates to a character / cursor display circuit which is particularly effective when used in such a high-performance oscilloscope.

[Prior Art] When a signal waveform, a character or a symbol, and a cursor are displayed on a cathode ray tube surface, each of them is displayed by time division. Characters such as characters and symbols and a cursor, which is an instruction line, are composed of many dots, and the display of the signal waveform is temporarily interrupted to be displayed.

Such an apparatus is disclosed in Japanese Patent Application No.
Further details are disclosed in 59-191689. Among the known techniques, the part particularly relevant to the present application will be described below with reference to the drawings.

3A and 3B show configuration examples of a D / A conversion unit for receiving data for displaying a character and converting it into an analog signal.

The characters and symbols displayed are 6 dots horizontally and 10 vertically.
It is a dot, and one of the 60 dots on the left shoulder is processed as the origin of the character. Where on the tube surface this character should be displayed is determined by indicating the address on the tube surface of this origin for each of the X and Y coordinates. The column address indicates the X coordinate of the origin, and the row address indicates the Y coordinate.

Here, since the cursor is displayed without connecting the line segments, this line segment is included in the character.

As information regarding the shape of a character such as a character or a symbol formed of many dots, X and Y coordinates based on the origin of each dot forming the character or symbol are applied as horizontal and vertical addresses.

In FIG. 3 (a), the column address, which is the X coordinate on the tube surface of the origin of the character such as characters and symbols, is the D / A converter 5.
In 01, the row address, which is also the Y coordinate, is applied to the D / A converter 504 and D / A converted, respectively, and the analog adder 511 is added.
And 512 to one input terminal.

The X-coordinate and the Y-coordinate with respect to the origin of each dot forming a character such as a character or a symbol are applied to D / A converters 503 and 502 as horizontal and vertical addresses, respectively, and D / A converted, respectively. Applied to the other input terminals of adders 511 and 512.

From the analog adders 511 and 512, a character X signal and a Y signal for displaying each character are respectively output, and both of these signals are applied to the X axis and the Y axis of the cathode ray tube to generate characters such as characters and symbols. Is displayed.

In FIG. 3B, a column address of a character such as a character or a symbol and a predetermined coefficient N _C are applied to a multiplier 521 to be multiplied, and the multiplication result is one of digital adders 531. Is applied to the input terminal of. The row address and the predetermined count N _R are applied to the multiplier 522 and multiplied, and the multiplication result is the digital adder 534.
Is applied to one of the input terminals.

The other input terminal of the adder 531 has the horizontal address
A vertical address is applied to the other input terminal of 34, and is digitally added to the column and row addresses. The outputs of these adders 531 and 534 are the D / A converter 505 respectively.
And 506 and D / A converted, and output as character X signal and Y signal, respectively. Both signals are applied to the X-axis and Y-axis of the CRT to display characters and symbols.

FIG. 4 shows a circuit for displaying a cursor.

An example is shown in which four cursors of a first vertical cursor, a second vertical cursor, a first horizontal cursor, and a second horizontal cursor are displayed. Coordinates on the cathode ray tube surface, which is position data of each cursor, are input as CPU data. The position data of the first vertical cursor is D / A converted by the D / A converter 811 via the I / O port 801 as X coordinate data. Similarly, the position data of the second vertical cursor is D / A converted by the D / A converter 812 via the I / O port 802. The position data of the first horizontal cursor is D / A converted by the D / A converter 813 via the I / O port 803 as Y coordinate data. The position data of the second horizontal cursor is D / A converted by the D / A converter 814 via the I / O port 804 as Y coordinate data.

Switches 821-824 are each switch control
Each switch 821 controlled by X ₁ , X ₂ , Y ₁ , Y ₂
Up to 824 are switched to the A side or the B side, respectively.

While the first vertical cursor should be displayed, switch 821 is set to A
Side, switch 822 is on A side, switch 823 is on A side, switch
824 is on the B side, the character Y signal is output as it is, the X coordinate of the first vertical cursor is D / A converted by the D / A converter 811 through the I / O port 801 as indicated by the CPU data, This is the cursor / character X signal. While the first vertical cursor is displayed, the cursor / character X signal maintains a constant voltage, and the cursor / character Y signal shows a staircase output.

While the second vertical cursor should be displayed, switch 821 is set to B
Side, switch 822 is on A side, switch 823 is on A side, switch
824 is on the B side, the character Y signal is output as it is, and the CPU data is D / A by the I / O port 802 and D / A converter 812.
It is converted into a cursor / character X signal.

While the first horizontal cursor should be displayed, switch 821 is set to A
Side, switch 822 is B side, switch 823 is A side, switch
824 is on the A side, the character X signal is output as it is, and the CPU data is converted by the I / O port 803 and the D / A converter 813 to become the cursor / character X signal.

While the second horizontal cursor should be displayed, switch 821 is set to A
Side, switch 822 is B side, switch 823 is B side, switch
824 is on the A side, the character X signal is output as it is, and the CPU data is D / A by the I / O port 804 and D / A converter 814.
It is converted into a cursor / character Y signal.

During the period in which characters are to be displayed, the switch 821 is on the A side, the switch 822 is on the B side, the switch 823 is on the A side, and the switch 824 is on the B side, and the character X and Y signals are both output as they are.

[Problems to be Solved by the Invention] In order to display characters, in FIG.
Four D / A converters are required, and two D / A converters are required in the example of FIG. 3 (b), and four D / A converters are required to indicate the positions of the four cursors, as shown in FIG. Required a D / A converter. Four
Even if the case shown in FIG. 3 (b) and the case shown in FIG. 4 are combined to display the cursor of the book and characters such as characters and symbols, six D / A converters are required.

The use of many D / A converters in this way has been a factor in increasing costs. Furthermore, as the number of bits configured to improve the character type and quality increases,
You have to use a D / A converter with a large number of bits,
There has been a problem that the circuit scale becomes large and the cost is significantly increased.

[Means for Solving Problems] The present invention has been made to solve such problems.

D / A converters were used for the X signal and Y signal of the data related to the conventional character, respectively, and 4 for 4 cursors.
The D / A converter is used, and after conversion to an analog signal, the switch (821 to 824) was used for processing.

On the other hand, in the present invention, all the data relating to the character and the data relating to the cursor are digitally processed, and finally converted into an analog signal by two D / A converters for the X signal and the Y signal. did.

[Operation] Since all digital processing is performed and finally D / A conversion is performed by the two D / A converters, the circuit scale is remarkably reduced and the price is remarkably reduced. Furthermore, since it is digitally processed, it becomes easy to switch the reference current of the D / A converter, which makes it possible to switch the gain of D / A conversion.

[Embodiment] An embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 illustrates a circuit configuration for obtaining a cursor / character X signal, and FIG. 2 illustrates a circuit configuration for obtaining a cursor / character Y signal. 1 and 2
In the figure, the same symbols are given to those corresponding to the respective elements shown in FIG. 3 and FIG.

In FIG. 1, a column address that is the X coordinate on the tube surface of the origin of a character that is a character and a predetermined count N _C are applied to a multiplier 521 and multiplied, and the multiplication result is a digital addition. Applied to one input terminal of the device 531. The other input terminal of the adder 531 is applied with horizontal and vertical addresses with respect to the origin of each dot forming the character, and the horizontal address is taken in and added to the multiplication result from the multiplier 521. To do.

The X coordinate forming each dot of the character (cursor included in the character as a line segment) is thus obtained from the adder 531 and connected to the terminal C of the switch 911.

The position data of the first vertical cursor (pointing line) is applied to the I / O port 801 as CPU coordinate data by the CPU data, and is applied to the terminal A of the switch 911. Similarly, the position data of the second vertical cursor is applied to the I / O port 802 by the CPU data and connected to the terminal B of the switch 911.

The switch 911 selects any one of the terminals A, B, C according to the characters, cursor, gain, and signals from e and f of the output lines e, f, g of the switch switching circuit 910.

The character, cursor, gain and switch switching circuit 910 outputs signals to the output lines e, f, g according to the input signals of the switch controls X1 and X2. Here, when the switch controls X1 and X2 are at "L" and "L" levels, respectively, the output lines e and f are outputted so that the switch 911 is connected to the terminal A, and the output line g. Outputs a "H" level signal. Therefore, the X-axis data of the first vertical cursor obtained at the terminal A is applied to the multiplication type D / A converter 912 to be D / A converted, and a cursor X signal is output.

The reference voltage 922 is connected to the emitter of the transistor 921, and the signal from the output line g is connected to the base of the reference voltage 922.
It is divided and applied at 925 and 926. Therefore, when the signal level of the output line g becomes "L", the transistor 921 turns on, and when it becomes "H", it turns off. When the transistor 921 is on, the reference current is supplied from the reference voltage 922 to the multiplying D / A converter 912 through the resistors 924 and 923. When the level of the signal on the output line g becomes "H", the transistor 921 is turned off and the reference current is supplied by the resistor 923. The value of this reference current is the multiplication type D /
The value of the output voltage per bit of the data applied to the A converter 912 is determined. Therefore, the larger the reference current, the larger the full-scale value of the output voltage. The output voltage is obtained by multiplying the value of the input data of the multiplication type D / A converter 912 by the value of this reference current.

Switch controls X1 and X2 are “H”,
When it becomes “L”, the switch 911 selects the terminal B, applies the X-axis data of the second vertical cursor from the I / O port 802 to the multiplication type D / A converter 912, and performs D / A conversion. Output the cursor X signal. At this time, the level of the signal on the output line g is “H”, and the transistor 921 is off. Therefore, the reference current supplied to the multiplication D / A converter 912 is supplied from the resistor 923.

Switch controls X1 and X2 are “L”,
When it becomes “H”, the switch 911 selects the terminal C, and the adder 5
The output data of 31, that is, the X-axis data of the character is applied to the multiplication type D / A converter 912 and is D / A converted to output the character X signal. At this time, the level of the signal on the output line g is “L” and the transistor 921 is on, so the reference current supplied to the multiplication type D / A converter 912 is the resistors 923 and 9
Supplied by 24.

In the above operation, when the terminal A or B of the switch 911 is selected, that is, when the X-axis data of the first or second vertical cursor is selected, the reference current of the multiplication D / A converter 912 is the resistance. D / A to be sourced from 923
The conversion gain is small, and the output voltage value per input bit is small. Further, when the terminal C of the switch 911 is selected, that is, when the character X-axis data is applied to the multiplication type D / A converter 912, the reference current is supplied from both the resistors 923 and 924. D / A
The conversion gain is large, and the output voltage value per input bit is large.

In the above description, the circuit configuration for obtaining the cursor X signal and the character X signal has been described.
The circuit configuration for obtaining the signal and the character Y signal is similarly realized. This will be described with reference to FIG.

In FIG. 2, a row address, which is the Y coordinate on the tube surface of the origin of a character, which is a character, and a predetermined coefficient N _R are applied to a multiplier 522 and multiplied, and the multiplication result is a digital addition. Applied to one input terminal of the device 534. Horizontal and vertical addresses are applied to the other input terminal of the adder 534 with respect to the origin of each dot forming the character. The vertical address is taken in and added to the multiplication result from the multiplier 522. To do.

The Y coordinate forming each dot of the character (cursor included in the character as a line segment) is thus obtained from the adder 534 and connected to the terminal C of the switch 931.

The position data of the first horizontal cursor (indication line) is applied to the I / O port 803 by the CPU data and applied to the terminal A of the switch 931 as Y coordinate data. Similarly, the position data of the second horizontal cursor is applied to the I / O port 804 by the CPU data and connected to the terminal B of the switch 931.

The switch 931 selects any one of the terminals A, B, and C according to the characters, cursor, gain, and signals from e and f of the output lines e, f, and g of the switch switching circuit 930.

The character, cursor, gain and switch switching circuit 930 outputs signals to the output lines e, f, g according to the input signals of the switch controls Y1 and Y2. Here, when the switch controls Y1 and Y2 are at "L" and "L" levels, respectively, the output lines e and f are outputted so that the switch 931 is connected to the terminal A, and the output line g. Outputs a "H" level signal. Therefore, the Y-axis data of the first horizontal cursor obtained at the terminal A is applied to the multiplication type D / A converter 932 to be D / A converted and a cursor Y signal is output.

The reference voltage 942 is connected to the emitter of the transistor 941, and the signal from the output line g
It is divided and applied at 945 and 946. Therefore, when the signal level of the output line g becomes "L", the transistor 941 is turned on, and when it becomes "H", it is turned off. When the transistor 941 is on, the reference current is supplied from the reference voltage 942 to the multiplication D / A converter 932 through the resistors 944 and 943. When the level of the signal on the output line g becomes “H”, the transistor 941 is turned off and the reference current is supplied by the resistor 943. The value of this reference current is the multiplication D / A
The value of the output voltage per bit of the data applied to the converter 932 is determined. Therefore, the larger the reference current, the larger the full-scale value of the output voltage. The value obtained by multiplying the value of the input data of the multiplication type D / A converter 932 by the value of this reference current becomes the output voltage.

Switch controls Y1 and Y2 are set to “H”,
According to "L", the switch 931 selects the terminal B, applies the Y-axis data of the second horizontal cursor from the I / O port 804 to the multiplication type D / A converter 932, and performs D / A conversion. Outputs the cursor Y signal. At this time, the level of the signal on the output line g is “H” and the transistor 941 is off. Therefore, the reference current supplied to the multiplication D / A converter 932 is supplied from the resistor 943.

Switch controls Y1 and Y2 are set to “L”,
When it becomes “H”, the switch 931 selects the terminal C, and the adder 5
The output data of 34, that is, the Y-axis data of the character is applied to the multiplication type D / A converter 932 and is D / A converted to output the character Y signal. At this time, the signal level of the output line g is “L” and the transistor 941 is on, so the reference current supplied to the multiplication type D / A converter 932 is the resistances 943 and 9
Powered by 44.

In the above operation, when the terminal A or B of the switch 931 is selected, that is, when the Y-axis data of the first or second horizontal cursor is selected, the reference current of the multiplication D / A converter 932 is the resistance. D / A to be sourced from 943
The conversion gain is small, and the output voltage value per input bit is small. Also, when the terminal C of the switch 931 is selected, that is, when the Y-axis data of the character is applied to the multiplication type D / A converter 932, the reference current is supplied from both the resistors 943 and 944. D / A
The conversion gain is large, and the output voltage value per input bit is large.

When the first vertical cursor is displayed on a cathode ray tube surface not shown, the switch 911 selects the terminal A, and the multiplication D / A converter 912 causes the cursor X, which is a voltage of a constant value with a small gain. It outputs a signal (Fig. 1). On the other hand, the switch 931 selects the terminal C, the multiplication D / A converter 932 has a large gain, and changes in a step-like manner to display a part of the vertical line segment of the first vertical cursor as a series of dots. The cursor Y signal, which is the voltage to be applied, is output (FIG. 2).

When displaying the second vertical cursor on a cathode ray tube surface not shown, the switch 911 selects the terminal B, and the multiplication D / A converter 912 causes the cursor X, which is a voltage of a constant value with a small gain. It outputs a signal (Fig. 1). On the other hand, the switch 931 selects the terminal C, the multiplication D / A converter 932 has a large gain, and changes in a step-like manner in order to display a part of the vertical line segment of the second vertical cursor by a series of dots. A character Y signal, which is a voltage to be applied, is output (FIG. 2).

When the first horizontal cursor is displayed on a cathode ray tube surface not shown, the switch 931 selects the terminal A, and the multiplication D / A converter 932 selects the cursor X which is a voltage of a constant value with a small gain. It outputs a signal (Fig. 2). On the other hand, the switch 911 selects the terminal C, the multiplication D / A converter 912 has a large gain, and changes in a stepwise manner to display a part of the horizontal line segment of the first horizontal cursor as a series of dots. The character X signal, which is the voltage to be applied, is output (FIG. 1).

When the second horizontal cursor is displayed on the cathode ray tube surface not shown, the switch 931 selects the terminal B, and the multiplication D / A converter 932 selects the cursor X which is a voltage of a constant value with a small gain. It outputs a signal (Fig. 2). On the other hand, the switch 911 selects the terminal C, the multiplication D / A converter 912 has a large gain, and changes in a stepwise manner to display a part of the horizontal line segment of the second horizontal cursor as a series of dots. The character X signal, which is the voltage to be applied, is output (FIG. 1).

To summarize the cursor display operation described above, when displaying the first or second vertical cursor, the multiplication D / A converter 912 (FIG. 1) displays X coordinate data indicating the position of the X coordinate of the vertical cursor. D / A conversion is performed to output a voltage of a constant value. In the multiplication type D / A converter 932 (Fig. 2), Y coordinate data of each dot representing a vertical line segment of a part of the vertical cursor. D /
It outputs a voltage that changes in a step-like manner after A conversion. When outputting a stepwise voltage with a large gain, the intervals between the dots become coarse. Similarly, when displaying the first or second horizontal cursor, the multiplying D / A converter 932 (FIG. 2) displays the Y coordinate data indicating the position of the Y coordinate of the horizontal cursor in the D / A.
The converted voltage is output and a constant value voltage is output. In the multiplication type D / A converter 912 (FIG. 1), the X coordinate data of each dot representing a horizontal line part of the horizontal cursor is converted to D / A. The voltage that is converted and changes stepwise is output. When outputting a stepwise voltage with a large gain, the intervals between the dots become coarse.

When displaying characters such as characters and symbols (in this case, the line segment of the cursor is not included) on a cathode ray tube surface not shown, the switch 911 selects the terminal C and performs the multiplication D / A conversion. The device 912 outputs a character X signal, which is a voltage that changes according to the X coordinate of each dot forming a character or the like, with a large gain (FIG. 1). On the other hand, the switch 931 selects the terminal C, and the multiplication type D / A converter 932 outputs a character Y signal which is a voltage with a large gain and which changes according to the Y coordinate of each dot forming a character or the like (first). (Fig. 2).

When the gains of both the multiplying D / A converters 912 (Fig. 1) and 932 (Fig. 2) are increased, characters such as characters and symbols are enlarged and displayed in coarse dots in both the X and Y directions. When only one of the gains is increased, coarse dots are enlarged and displayed in one direction of the X direction or the Y direction. In the vertical cursor display, the X
The case where the gain of the multiplication D / A converter 912 that determines the coordinates is reduced has been described. However, when the gain is increased, the moving speed of the vertical cursor in the X-axis direction can be increased manually. Similarly, in the horizontal cursor display, the case where the gain of the multiplication D / A converter 932 is reduced has been described, but when the gain is increased, the moving speed of the horizontal cursor in the Y-axis direction must be increased manually. You can In this way, the display range of vertical and horizontal cursors and the size of characters can be changed independently. Since the amount of movement of the cursor, the resolution, and the size of the characters can be adjusted independently on the surface of the cathode ray tube, the best display can be made for the distortion around the focus of the cathode ray tube.

The cursor / character X signal and Y signal thus obtained are displayed together with the signal waveform on the cathode ray tube surface by time division.

[Effects of the Invention] As is clear from the above description, according to the present invention,
The number of D / A converters, which was a cause of high cost, can be reduced from 6 to 2, and the gain of D / A conversion can be switched as needed. Therefore, miniaturization, high functionality, and low cost can be realized, and the effect of the present invention is extremely large.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram for obtaining a cursor / character X signal which is one embodiment of the present invention, and FIG. 2 is a circuit configuration diagram for obtaining a cursor / character Y signal which is one embodiment of the present invention. FIG. 3 is a circuit configuration diagram for obtaining a conventional character X signal and Y signal, and FIG. 4 is a circuit configuration diagram for obtaining a conventional cursor / character X signal and Y signal. 501 to 506 …… D / A converter 511,512 …… Adder 521,522 …… Multiplier 531,534 …… Adder 801 to 804 …… I / O port 811-814 …… D / A converter 821 to 824 …… Switch 910,930 …… Character, cursor, gain, switch switching circuit 911,931 …… Switch 912,932 …… Multiplying D / A converter 921,941 …… Transistor 922,942 …… Reference voltage 923 to 926,943 to 946 …… Resistance.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Sakae Degawa 1-7-41 Kugayama, Suginami-ku, Tokyo Iwasaki Tsushinki Co., Ltd. (56) References JP 61-70633 (JP, A)

Claims (2)

[Claims] At the same time as the signal waveform, a character including dot-configured line segments and characters / symbols, and at least first and second vertical cursors connected to the dot-configured line segments included in the character, In a character / cursor display circuit of an oscilloscope for displaying the first and second horizontal cursors in a time division manner, the applied X coordinate data of the first vertical cursor and the X coordinate data of the second vertical cursor, X-coordinate switch means (911) for selecting the X-coordinate data of each dot forming the character according to an instruction of a selection signal, and D / A conversion by receiving a digital signal which is output data of the X-coordinate switch means. X-coordinate D / A conversion means (9) for switching to a gain designated by the gain signal and converting into an analog signal.
12), selecting the applied Y coordinate data of the first horizontal cursor, the Y coordinate data of the second horizontal cursor, and the Y coordinate data of each dot forming the character according to an instruction of a selection signal. Y-coordinate switch means (931) for switching and a Y-coordinate D for receiving the digital signal which is the output data of the Y-coordinate switch means and switching to the gain indicated by the D / A conversion gain signal to convert into the analog signal / A conversion means (9
32), and when displaying the first vertical cursor, the X coordinate data of the first vertical cursor and the Y coordinate data of each dot of the line segment of the dot configuration included in the character are described above. When the X-coordinate switch means and the Y-coordinate switch means are respectively selected to display the second vertical cursor, the X-coordinate data of the second vertical cursor and the line of the dot configuration included in the character. Minute Y-coordinate data of each dot is selected by the X-coordinate switch means and the Y-coordinate switch means respectively, and when the first horizontal cursor is displayed, the Y-coordinate data of the first horizontal cursor and the Y-coordinate data of the first horizontal cursor are displayed. , The Y coordinate switch means and the X coordinate switch means are made to select the X coordinate data of each dot of the line segment of the dot configuration included in the character, respectively. When the second horizontal cursor is displayed, the Y coordinate data of the second horizontal cursor and the X coordinate data of each dot of the line segment of the dot configuration included in the character are transferred to the Y coordinate switch means and the Y coordinate switch means. When the character is displayed by selecting the X coordinate switch means respectively, the X coordinate and Y coordinate of the selection signal instructing to select the X coordinate and Y coordinate data of each dot forming the character. A character / cursor display circuit including switch switching means (910) for outputting to the switch means and outputting the D / A conversion gain signal to the X coordinate and Y coordinate D / A conversion means. 2. The switching of the gain indicated by the D / A conversion gain signal is performed by changing the value of the reference current of the D / A converter included in the X-coordinate and Y-coordinate D / A conversion means. The character / cursor display circuit according to claim 1.