JPH0124984Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a Schmitt circuit used in a sweep circuit of an oscilloscope.

For oscilloscopes with delayed sweep function,
It has a comparator that determines the start of the delayed sweep, and this comparator operates every sweep. Figure 1 shows a block diagram of the sweep circuit of an oscilloscope with a delayed sweep function. 1 is a main sweep circuit control flip-flop (hereinafter referred to as flip-flop 1); 2 is an integrator for generating a main sweep signal (hereinafter referred to as integrator 2); 3 is a delayed sweep start control comparator (hereinafter referred to as comparator 3);
4 is a Schmitt circuit; 5 is a delay sweep circuit control flip-flop (hereinafter referred to as flip-flop 5);
6 is an integrator (hereinafter referred to as integrator 6) for generating a delayed sweep signal. When not performing a delayed sweep, the flip-flop 5 is reset by other control means,
Even if it receives a trigger signal from the Schmitt circuit 4, it does not operate. However, even in this case, the comparator 3 and the Schmitt circuit 4 perform a comparison operation and drive the trigger terminal of the flip-flop 5 every time the integrator 2 integrates and sweeps the oscilloscope tube surface under the control of the flip-flop 1. This drive signal rises very quickly. FIG. 2 shows an example of a conventional comparator and Schmitt circuit. The part 3 surrounded by the broken line is the comparator 3 in FIG. 1, and the part 4 surrounded by the broken line is the first comparator 3.
This corresponds to the Schmitt circuit 4 shown in the figure. 9 is a transistor, 10 is a logic element and a TTL element inverter,
A resistor 11 forms hysteresis by applying positive feedback. By using a TTL element in the inverter 10, the output rises at a high speed of 10 nS or less. When the integrator 2 operates, the output of the Schmitt circuit 4 changes rapidly, which causes the current at the trigger terminal of the flip-flop 5 to change quickly. If part of this rapidly changing voltage and current flows into the integrator 2, the linearity of the output of the integrator 2 will be impaired, causing distortion in the waveform observed on the oscilloscope tube surface. However, in the conventional circuit, it is difficult to suppress the rapidly changing voltage and current from flowing into the integrator 2 and to reduce waveform distortion.

The present invention is characterized in that an inverting gate element is used in the Schmitt circuit, and the operation of the Schmitt circuit is controlled as necessary, and its purpose is to reduce waveform distortion.

FIG. 3 is a Schmitt circuit diagram according to an embodiment of the present invention, in which 9 is a transistor, 11 is a resistor, 1
2 is a NAND gate, and 13 is a control signal. The output of the comparator 3 shown in FIG.
Even when driven, the output does not change when the control signal 13 of the NAND gate 12 is "0", so the output of the integrator 2 is not affected in any way, and the signal waveform is not distorted. Therefore, by setting the control signal to "0" when the delayed sweep is not performed, a signal without waveform distortion can be displayed on the oscilloscope tube surface.

In addition, in this example, as a logic element
Although a NAND gate was used, it is clear that any device that can control signals, such as a NOR gate or other inverting gate device, can be applied in various ways.

As described above, according to the present invention, by using a gate circuit as a logic element of a Schmitt circuit, a distortion-free waveform can be displayed on the oscilloscope tube surface in a simple manner.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a delay sweep circuit of an oscilloscope, FIG. 2 is a circuit diagram of a conventional comparator and Schmitt, and FIG. 3 is a Schmitt circuit diagram according to an embodiment of the present invention. 1, 5: flip-flop, 2, 6: integrator,
3: Comparator, 4: Schmitt circuit, 9: Transistor, 10: Inverter, 11: Resistor, 12:
NAND gate, 13: control signal.

Claims (1)

[Scope of utility model registration request] In a delayed sweep circuit of an oscilloscope with a delay function, an integrator that generates the main sweep signal, a comparator that compares the output of the integrator with a voltage that determines the starting point of the delayed sweep, and the comparator output is added to the base. an inverting logic gate element having a plurality of input terminals, the collector of which is connected to one of the input terminals, and a resistor connected from the output terminal of the gate element to the base of the transistor. , a Schmitt circuit for a sweep control circuit of the oscilloscope delay sweep circuit, wherein operation and non-operation are controlled by a control signal from another input terminal of the inverting logic gate element.