JPS61105467A - Waveform observing device - Google Patents

Abstract

PURPOSE:To prevent a wrong waveform display due to the input of an over input signal by making the number of steps of the output signal of an AD converter larger than the number of longitudinal-axis picture elements, and displaying part of the output signal of the AD converter. CONSTITUTION:An input signal 6 is inputted from an input terminal 1 and converted by the AD converter 2 into, for example, a 7-bit digital signal, which is written in a memory circuit 3. Then, a read circuit 4 reads and decodes the signal and sends the decoded signal to a liquid-crystal display element 5. The display element 5 displays a waveform on a display screen 10 which have 64 picture elements longitudinally on the basis of the decoded signal. Then if the over input signal within a display range arrives, the converter 2 enters an overflow state and the waveform part is displayed as a straight line, so a correction display is not obtained. For the purpose, the number of steps of an output signal 7 is set to, for example, 128 which is larger than 64, i.e. the number of picture elements of the display element 5, and the circuit 4 displays 32-95 of the output signal 7 and on the 64 longitudinal-axis picture elements and does not display other values. Therefore, even if the over input signal is inputted, the straight line which does not correspond to the input signal is not displayed.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a waveform observation device.

2. Description of the Related Art Conventional waveform observation devices that use an AD converter to convert an input signal into a digital signal with a number of steps (N (natural number)) and display the waveform on a waveform display section with a vertical axis number of pixels N, When an excessive input signal is input, the output of the AD converter is either all bits are O or all bits are 1 depending on the polarity of the input, and the waveform part where the excessive input signal is input is at the top or bottom of the display screen. Problem to be Solved by the Invention Therefore, this type of waveform observation device 1h displays a waveform portion on the topmost pixel of the display screen or the bottom pixel of the frame. When the display is J, it has the disadvantage that it is difficult to determine whether the display is correct for the input signal or whether it is a display of a waveform portion containing an excessive input signal.

Means for Solving the Problem The present invention solves the above problem, and its main points are as follows:
Rather than making the number of steps of the output signal of the AD converter larger than the number of pixels on the vertical axis of the waveform display section, it is necessary to avoid displaying the waveform portion when an excessive input signal is input.

Effect: By having the above-mentioned features of the present invention, it is possible to observe a normal waveform without any misunderstandings without displaying the waveform portion containing an excessive input signal.

lol example An embodiment of the present invention will be described with reference to the drawings.

In this device, input signal 6 is input from input terminal 1, and AD
The converter 2 converts it into a 7-bit digital signal (AD converter output signal 7, number of steps 27=128), and writes it into the memory circuit 3.

This 7-bit digital signal is read out and decoded to a readout circuit 4 and sent to a liquid crystal display element 5 (waveform display section) K. liquid°
Based on this signal, the number of pixels on the vertical axis of the crystal display element 5ij is 64.
A 10VC waveform is displayed on the display screen.

Next, countermeasures against fcs@- when an excessive input signal is input will be explained. Here, suppose that the output signal of AD converter 2 is Stellar.
Consider the case where the number of pixels is less than or equal to the number of pixels on the vertical axis of the liquid crystal display element 5. In this case, if an input signal that is too large for the displayable range enters, the AD converter 2rr will overflow, and the waveform portion where the overflow has occurred will be displayed as a straight line, making it impossible to display correctly.

Therefore, in this device, the number of steps of the output signal 7 of the TrJAD converter is set to 128, which is thicker than 64, which is the number of pixels on the vertical axis of the liquid crystal display element 5. Of the 127, 32 to 95 (64 steps) are displayed in 64 pixels on the vertical axis, and values other than n are not displayed. Therefore, even if an excessive input signal enters the display area in this device, a correct waveform is always displayed without displaying a straight line contrary to the input signal.

2. Effect of Light As mentioned above, by making the step number of the output signal of the AD converter larger than the number of pixels on the vertical axis and using a part of the output signal of the AD converter for display, Prevents incorrect waveform display when excessive input signals are input, allowing accurate waveform observation at all times.

[Brief explanation of drawings]

Fi'1 figure shows an example of "8 invention";
1. FIG. 2 is an explanatory diagram showing the relationship among the input signal, the output signal of the AD converter, and the displayed waveform in FIG. 1.

Claims (1)

[Claims] In a waveform observation device that converts an input signal into a digital signal by an AD converter and displays the waveform on a waveform display section, the number of steps of the output signal of the AD converter is made larger than the number of pixels on the vertical axis of the waveform display section, A waveform observation device characterized in that a waveform portion containing an excessive input signal is not displayed.