JP2789561B2 - Straight line display method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for displaying a straight line on a characteristic curve displayed on XY coordinates of a display screen. [Related Art] For example, when a characteristic curve of an element to be measured is displayed on a display screen of a curve tracer, measurement can be facilitated by simultaneously displaying straight lines related to the characteristic curve. That is, when the element to be measured is a transistor and the collector voltage / collector current characteristic curve of the transistor is displayed, the early voltage and the on-resistance can be easily obtained by displaying the tangent of the characteristic curve. Displaying a straight line on the characteristic curve displayed on the XY coordinates of the display screen as described above is very effective for obtaining various parameters from the characteristic curve. In the conventional straight line display method, as disclosed in Japanese Patent Application Laid-Open No. 58-100176, two arbitrary points are designated by XY coordinates on a display screen, and a straight line passing through these two points is displayed.
To specify each of the two arbitrary points, four cursor keys in the + X direction, the -X direction, the + Y direction, and the -Y direction were used. Japanese Patent Laying-Open No. 58-100176 discloses another straight line display method in which one point on a displayed characteristic curve is designated by a marker key, and the remaining one point is designated by the above four cursor keys. It also discloses displaying a straight line passing through these two points. [Problems to be Solved by the Invention] In the straight line display method disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 58-100176, at least one of two points defining a straight line is
The setting has to be made in consideration of four directions of + X, -X, + Y and -Y, and setting is not easy. Therefore, an object of the present invention is to provide a straight line display method in which two points for determining a straight line can be easily set in relation to a characteristic curve. [Means for Solving the Problems] According to the present invention, a memory for storing measurement data and XY coordinate axis data, and a characteristic curve and XY coordinate axes are displayed based on the measurement data and XY coordinate axis data. A screen and a first coordinate point on the characteristic curve and a second coordinate point on the coordinate axis corresponding to one measurement data and one XY coordinate axis data read from the memory, respectively, are identified on the screen. A method for displaying a straight line of a characteristic curve display device, comprising: (A) providing an increase key and a decrease key for controlling the positions of the first and second coordinate points; and (b) increasing or decreasing an address designating the measurement data based on control data from the increase key or the decrease key. The first data corresponding to the measured data at this address.
(C) increasing or decreasing an address designating the XY coordinate axis data based on control from the increase key or the decrease key; and calculating the second coordinate corresponding to the coordinate axis data at this address. (D) calculating the first data from the first and second coordinate points;
And calculating data of a straight line passing through the second coordinate point, and (e) displaying a straight line on the screen based on the calculation result. [Operation] According to the present invention, since one of the two points for determining the straight line is on the characteristic curve, the setting is simple and the straight line can be easily associated with the characteristic curve. Also,
The remaining one point is on the X axis or the Y axis, so that the setting is simple. Hereinafter, a preferred embodiment of the present invention will be described with reference to the accompanying drawings. First, referring to FIG.
The tracer will be described. Central processing unit (CPU) 10,
A read only memory (ROM) 12, a random access memory (RAM) 14, and a keyboard 16 are connected to a bus (including control lines, data lines and address lines) 18. CP
The U10 uses the RAM 14 as a temporary storage device and performs various controls including the control of the linear display method of the present invention by a program stored in the ROM 12. The keyboard 16 determines the straight line 2
It operates as an input device for setting points and setting various measurement conditions. The measurement circuit 20 sets various measurement conditions based on signals from the bus 18, and detects, for example, the collector voltage and the collector current of the transistor 22 that is the device to be measured. An analog signal corresponding to the collector voltage and the collector current is converted into digital data by an analog / digital signal (A / D) converter 24, and R
The information is stored in the AM 14 as display information. The display control circuit 26
A digital / analog converter is provided, and under the control of the CPU 10, display information in the RAM 14 is displayed on a display 28 such as a cathode ray tube.
Display on the display screen. FIG. 3 is a display example of the display 28, and shows the collector voltage / collector current characteristics of the transistor to be measured. In this display,
The X axis (horizontal axis: the lower side of the display screen) is the collector voltage, the Y axis (vertical axis: the left side of the display screen) is the collector current, and the origin of the XY coordinates corresponds to the lower left end of the display screen. . Next, the straight line display method of the present invention will be described with reference to the flowchart of FIG. The following operation is controlled by the CPU 10 by the program of the ROM 12. First, the operator has a keyboard 1
Point A (1st point) at any position on the characteristic curve
Point). For this purpose, the keyboard 16 has two keys, an increase key and a decrease key. When the increase key is pressed, the CPU 10 sequentially reads data (coordinate values) of each point of the characteristic curve (display information) stored in the RAM 14 in one direction in the order of addresses. When the decrease key is pressed, the CPU 10 sequentially reads the data of each point of the characteristic curve stored in the RAM 14 in a direction opposite to that of the increase key. The display control circuit 26 modulates the luminance of the point on the display screen corresponding to the data read by the CPU 10 to display the point A. If neither the increase key nor the decrease key is pressed,
The final read data is accumulated, and a point corresponding to this data is continuously displayed as a point A on the display screen. In step 30, the CPU 10 obtains the coordinates of the point A thus set. (The coordinates are represented by the accumulated data described above.) To set the point B (second point) on the X axis or Y axis (including the origin of the XY coordinates), the mode was switched. Later A
Press the increase key or decrease key as in the case of dots. Then
The CPU 10 sequentially specifies coordinates on the X axis and the Y axis,
The display control circuit 26 brightness-modulates the position on the display screen corresponding to the designated coordinates to display the point B. If neither the increase key nor the decrease key is pressed, the final coordinate data is accumulated, and the corresponding point B is continuously displayed on the display screen. In step 32, the CPU 10 obtains the coordinates of the point B thus set. In step 34, the CPU 10 obtains the reciprocal of the inclination of the straight line connecting the points A and B and the value of the point (X intercept) at which the straight line intersects the X axis from the coordinate data of the points A and B. When the straight line connecting the points A and B coincides with the characteristic curve as shown in FIG. 3, the reciprocal of the obtained slope and the value of the X intercept correspond to the on-resistance value and the Early voltage of the transistor 22 to be measured. These values are stored and displayed by the display control circuit 26 in the data display area 40 of the display screen using characters, numerals, and the like. Next, in step 36, the CPU 10 obtains and accumulates data of a straight line passing through the points A and B by the interpolation method and the extrapolation method. Based on the straight line data, the display control circuit 26 displays a straight line passing through the points A and B on the display screen. In step 38, the CPU 10 checks whether the point A or point B has moved. If the point has moved (yes), the process returns to step 30, and if not (no), the process returns to step 38. That is, step 38 until the point A or the point B moves.
Stay in. Therefore, when the point A or the point B moves, the straight line follows immediately, so that it is easy to display the straight line in a specific relationship with the characteristic curve. While the above has described one preferred embodiment of the present invention,
Various modifications and changes can be made without departing from the spirit of the present invention. For example, the displayed straight line may be a dotted line, a one-dot chain line, or the like to distinguish it from the characteristic curve, or may be a color different from the characteristic curve. Further, the points A and B may be displayed by a specific symbol such as X in addition to the display by the luminance modulation. [Effects of the Invention] According to the straight line display method of the present invention, two coordinate points that can be controlled by the operator are displayed limitedly on the characteristic curve and on the XY coordinate axes. Only the increase key and the decrease key are sufficient, and the configuration is simplified. In addition, since it is not necessary to perform a moving operation in four directions of front, rear, left and right as in the related art, the operation is greatly simplified, and a coordinate point that can be quickly identified to a desired point is moved, and these two coordinate points are moved. The passing straight line can be easily moved to a desired position. In particular, it is convenient for measurement in which a straight line is displayed in association with the displayed characteristic curve.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flowchart for explaining a preferred embodiment of the present invention, FIG. 2 is a block diagram of a curve tracer using the present invention, and FIG. 3 is a display example according to the present invention. FIG.

Claims (1)

(57) [Claims] A memory for storing measurement data and XY coordinate axis data, and a screen for displaying a characteristic curve and XY coordinate axes based on the measurement data and XY coordinate axis data;
A first coordinate point corresponding to one measurement data read from the memory is identified and displayed on the screen, and a second coordinate point corresponding to one XY coordinate axis data read from the memory is displayed on the screen. A display control circuit for displaying an identification on a screen, comprising: an increase key and a decrease key for controlling a position of the first coordinate point or the second coordinate point; The increase key increases or decreases an address designating the measurement data based on the control data from the decrease key, obtains data of the first coordinate point corresponding to the measurement data of the address, and determines from the increase key or the decrease key. X based on the control of
Increasing or decreasing the address specifying the Y coordinate axis data, obtaining the data of the second coordinate point corresponding to the coordinate axis data of this address, and calculating the first and second data from the data of the first and second coordinate points.
A straight line display method comprising: calculating data of a straight line passing through a coordinate point; and displaying a straight line passing through the first and second coordinate points on the screen based on the calculation result.