JPH0143958B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a logic scope that has a function of displaying the timing of digital signals of electronic circuits.

Due to advances in electronics, digital circuits are increasingly being used in electronic devices, and logic scopes are used to check digital signals in the design and repair of these electronic devices, and the necessity of logic scopes has increased. is increasing.

Figure 3 is a conceptual diagram of a logic scope using a conventional CRT. In the figure, 1 is an input circuit. When a signal for checking the digital signal of an electronic device enters the input circuit, when the signal is higher than the already set signal, it is treated as a high signal, and when it is lower, it is treated as a low signal, and is sampled by the sampling signal of the control circuit 4. , are stored in the memory circuit 2. In this specific example, since there are eight channels of input, memory circuits are set for eight circuits, and symbols are time-divisionally controlled and stored for each channel. The stored data is called by the control circuit 4 at the timing that has already been set, and is sent to the vertical amplification circuit 3, the horizontal amplification circuit 5, and the high voltage amplification circuit 6.
It passes through and is supplied to the CRT7. The signals of each channel input here are simultaneously projected onto the CRT.

FIG. 4 shows an example of signal display on a logic scope using a conventional CRT. As in the example, 8 channels of signals are displayed at once to check the timing between each signal and whether the signals are actually as designed. As described above, although the conventional logic scope has a simple structure, it has many drawbacks. One of these is that logic scopes display signals from 8 or 16 channels simultaneously on a narrow CRT, so the intervals between the signals displayed on each channel become narrow, making it difficult to see and causing the signals to indicate high. It becomes difficult to tell whether it is showing the current level or the low level.

Another drawback is that the displayed signal may be checked by stretching the time axis 10 or 20 times using a switch, but in this case the signal line on the CRT becomes thin and thin, making it difficult to measure well. Another drawback is that since it is displayed on a CRT, even if you adjust the brightness with the brightness control knob, it is not sufficient and difficult to see.
Also, if the signal is displayed with the brightness too high, burn-in may occur due to the nature of CRTs.
The lifespan of the CRT will be extremely shortened. Another drawback is that it uses a CRT.
High-voltage circuits are also required, and power consumption increases, making it difficult to downsize the device. In order to eliminate the above-mentioned drawbacks, there are devices that use LCD panels instead of CRTs.

FIG. 5 shows part of the display signals of the display section of a conventional logic scope that uses an LCD display in which a plurality of dots are arranged in a matrix. In the figure, 10 represents a dot that is not lit, and 11 represents a dot that is lit. To display the signal, dots are lit continuously and timing measurements are performed. Traditional
According to a method using an LCD display,
Although it has advantages such as being smaller and lighter because it does not have a CRT, it also has many disadvantages. One of them is that the rising edge (rising from low to high) of the signal waveform and the falling edge (falling from high to low) of the signal waveform, and for both, two sets of vertical dot rows are always required. , which leads to a decrease in resolution on the time axis in the horizontal direction.Another drawback is that high and low signals are represented by a series of dots, so
After all, when using a CRT with multiple channels, it becomes difficult to distinguish between high and low. Another drawback is that when trying to increase the number of channels or increase the resolution of the time axis, the size of the display cannot be increased unnecessarily, and each dot must therefore be made smaller. This makes the displayed signal line thinner, making it difficult to measure.
Display quality becomes poor.

The present invention solves these drawbacks of conventional logic scopes by providing a lighting correction circuit.
This problem is solved by displaying signals on the display, and at the same time, it provides a logic scope that is small, lightweight, and highly portable.

This will be explained below with reference to the drawings.

FIG. 1 is a conceptual diagram of the LCD logic scope of the present invention.

The present invention differs greatly from the conventional one in that a lighting correction circuit is provided and that the lighting correction circuit lights up all the columns in the high part of the signal.

In FIG. 1, 20 is an input terminal, and in this specific example, there are input terminals for eight channels. A digital signal inputted from the electronic circuit through the input terminal 20 is converted as a high signal when the voltage is higher than a preset voltage in the input circuit, and as a low signal when it is lower than the voltage preset by the input circuit, and is sampled by the sampling signal from the clock control circuit 25. and stored in the memory circuit 22 for each channel. The necessary amount of stored signals is controlled by the CPU 26 and sent from the memory circuit 22.
The signal is sent to the display control circuit 23.
At this time, the signal is corrected by the lighting correction circuit 27, and when the signal is high on the LCD display 24, the entire channel from the low part to the high part is lit. FIG. 2 is a diagram showing a display example showing a part of the waveform displayed on the LCD display of the LCD logic oscilloscope of the present invention.

In the figure, 30 represents a non-lit dot, and 31 represents a lit dot. In this specific example, when the input signal is low level, only the bottom row of the 5 vertical dots of each channel lights up, and when the input signal is high level,
All 5 dots will light up. In this way, each channel follows the signal, and when it is low level, the bottom row lights up, and when it is high level, all the channels are lit, and the parts that are all lit are displayed as if they were painted black.

As explained above, since the LCD logic scope according to the present invention completely lights up the high level portion of the signal, it has many advantages as listed below.

(1) When the input signal is low level, only the bottom row of the channel is lit, and when it is high, the entire channel is lit from the bottom to the top, making it easy to distinguish between high and low signals, so there is no misreading.

(2) Furthermore, even if each dot becomes smaller when the number of display channels is increased, by lighting all the high signals, it becomes easier to read and the display quality improves.

(3) Sampled input data remains unchanged
Since it can be displayed on an LCD display, there is no reduction in time axis resolution. Also, set the time axis to 10
Even when magnified by 20x or 20x, it becomes easier to see.

(4) Since the signal is displayed on the LCD display with lighting correction, it is easy to see even in bright places.
Deterioration such as burn-in that occurs with CRTs does not occur.

(5) Since it uses an LCD display, it is small and
Light weight and low power consumption.

In the above description, the LCD logic scope according to the present invention uses a lighting correction circuit to perform lighting correction to achieve full lighting when the signal is at a high level, but the invention is not limited to this.

If the CPU you are using has a margin, you can also correct the lighting by the CPU. In this case,
The aim is to provide an LCD logic scope that is smaller, lighter, and consumes less power while reducing manufacturing costs. Furthermore, the LCD logic scope of the present invention is equipped with an A/D conversion circuit (a circuit that converts an analog signal into a digital signal), measures the level of the input signal, and displays the signal on the LCD display.
It is also possible to display voltage values. This makes it easy to check signal levels and eliminates the need for multimeters, oscilloscopes, etc. that were previously required. Also, A/D converter (an element that converts analog signals to digital signals)
By incorporating a video RAM (memory element) for waveform display, it provides a logic scope that is easy to view, has good display quality, and is multifunctional.

As described above, in the present invention, by lighting up the high part of the signal on the LCD display,
Small and lightweight LCD that is easy to read and has good display quality
It provides a logic scope.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram of the LCD logic scope of the present invention. FIG. 2 is a display example diagram showing a part of the waveform displayed on the LCD display of the LCD logic scope of the present invention. Figure 3 is a conceptual diagram of a logic scope using a conventional CRT. FIG. 4 is an example of signal display on a CRT of a logic scope using a conventional CRT.
FIG. 5 is a display example diagram showing a part of the display signals of the display section of a logic scope using a conventional LCD display. 2...Memory circuit, 7...CRT, 10...
Non-lit dot, 11... Lighted dot, 24...
LCD display, 27...Lighting correction circuit,
30...Non-lit dot, 31...Lighted dot.

Claims (1)

[Claims] 1. In an LCD logic scope that displays the timing waveform of a digital signal of an electronic circuit using an LCD display with multiple dots arranged in a matrix, a high signal of the timing waveform lights up all the dots up to the high part. This LCD logic scope is characterized by displaying the low signal by lighting only the bottom dot.