JPH0431409B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an insulating circuit that transmits an input signal while insulating the circuit.

[Conventional technology]

When processing the measurement signal converted into a digital signal using the central processing unit CPU, the measurement signal and the CPU
An insulating circuit is provided between the two to avoid the influence of noise that may be introduced into the measurement signal.

Figure 3 is a configuration diagram of a signal processing system using such an isolation circuit. In the figure, 1 is a multiplexer that sequentially switches and outputs multiple analog measurement signals input from multiple channels, and 2 is a multiplexer 1. 3 is an A/D conversion circuit that converts the analog measurement signal amplified by amplifier 2 into a digital measurement signal; 4 is an A/D conversion circuit; An isolation circuit 5 circuit-isolated and outputs the digital measurement signal converted into a digital signal by the D conversion circuit 3; 5 processes the digital measurement signal circuit-isolated by the isolation circuit 4; A central processing unit CPU (6) displays the above-mentioned multiplexer 2, amplifier 3,
This is a power source that supplies drive power to the A/D conversion circuit 4 and the insulation circuit 5, respectively.

Next, the operation will be explained.

A plurality of analog measurement signals inputted from a plurality of channels are sequentially switched and output to an amplifier 2, and the amplifier 2 amplifies the analog measurement signal of one channel that is switched and output by a multiplexer 1 and outputs it to an A/D. Output to conversion circuit 3. A/
The D conversion circuit 3 converts the analog measurement signal amplified by the amplifier 2 into a digital measurement signal and outputs it to the isolation circuit 4. is isolated in a circuit and output. Here, the CPU 5 processes the digital measurement signal circuit-isolated by the insulation circuit 4, and displays it on a display device, for example, in the form of a graph.

In this conventional signal processing system, the analog measurement signals are sequentially switched and output by the multiplexer 1, and the switched and output measurement signals are sequentially processed, so there is an advantage that only one isolation circuit is required. When processing measurement signals at high speed, the switching by multiplexer 1 must be done quickly, but if the switching is done too quickly, noise will occur in a signal processing system that cannot accommodate many filters, and the high-speed measurement signal There was a limit to processing.

Therefore, as shown in FIG. 4, for multiple channels, multiple amplifiers 2, multiple A/D conversion circuits 3,
A plurality of isolation circuits 4 may be provided to obtain digital measurement signals from a plurality of isolated channels, and the digital measurement signals may be input to the CPU 5 for high-speed processing.

In this case, there is a problem in that various power supplies 6 for driving the plurality of amplifiers 2, A/D conversion circuits 3, and insulation circuits 4 must be prepared according to their respective drive voltages.

Therefore, as shown in FIG. 5, it is conceivable to directly insulate the input signal with an isolation circuit 4 and input it to the amplifier 2 at the subsequent stage. Such a circuit configuration has the advantage that only one type of power supply 6 is required for each of the subsequent amplifiers 2 and A/D conversion circuits 3.

[Problem to be solved by the invention]

By the way, conventionally used insulation circuits use commercially available circuit elements such as insulation type amplifiers, and are extremely expensive.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an inexpensive isolation circuit that is suitable for a signal processing system that directly isolates input signals and can process input signals at high speed.

[Means for Solving the Problems] Therefore, the insulating circuit according to the present invention includes a pre-stage holding circuit 1F that includes a capacitor _C0 and stores and holds an input signal, and a pre-stage holding circuit 1F that stores and holds an input signal, and A first switching circuit 1A that outputs a signal by repeatedly switching on and off, and a capacitor C ₁
a middle-stage holding circuit 1B that stores and holds a signal output from the first switching circuit when the first switching circuit is in a closed state; and a repeating opening and closing of the signal held in the middle-stage holding circuit. a second switching circuit 1C that outputs an output by;
a second-stage holding circuit _1E that includes a capacitor C2 and stores and holds the signal output from the second switching circuit when the second switching circuit is in a closed state; and an opening/closing circuit for the first and second switching circuits. It is characterized in that it includes a switching drive circuit 1D that alternately switches the state.

[Effect]

The pre-stage holding circuit 1F stores and holds the input signal. This held signal is output to the middle stage holding circuit 1B when the first switching circuit 1A is in the closed state, and the middle stage holding circuit 1B stores and holds the input signal.

Here, when the first switching circuit 1A becomes open and the second switching circuit 1C changes from the open state to the closed state, the signal held in the middle stage holding circuit 1B is transferred to the second stage holding circuit 1C via the second switching circuit 1C. Output to circuit 1E, subsequent holding circuit 1E
stores and holds the input signal. At this time, the opening and closing states of the first and second switching circuits 1A and 1C are alternately performed by the switching drive circuit 1D.

Note that the front-stage holding circuit 1F removes noise and accelerates charging of the middle-stage holding circuit 1B when the measurement input signal changes suddenly.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention. In the figure, 1A is a first switching circuit that outputs an input signal by repeatedly opening and closing;
B is a first signal holding circuit (middle stage holding circuit) including a capacitor _C1 that stores and holds the signal output from the first switching circuit 1A when the first switching circuit 1A is in a closed state; a second switching circuit that outputs the signal output from the first signal holding circuit 1B by repeatedly opening and closing;
1D is the first and second switching circuits 1A and 1C
1E is a second signal holding circuit (later holding circuit) that holds the output of the second switching circuit 1C, which includes a capacitor _C2 , and 1F is an input circuit that includes a capacitor _C0 . The third signal holding circuit (pre-stage holding circuit)
It is.

Here, the first signal holding circuit 1B is configured with a capacitor, and the switching drive circuit 1D receives the output signal _Q1 of the pulse oscillation circuit 2A and the pulse oscillation circuit 2A.
a first trigger pulse circuit 2B that outputs trigger pulse ₂ at the rising point of Q ₁ ;
The first AND which takes the logical product of and trigger pulse ₂
Inverted signal ₁ of circuit 2C and pulse oscillation circuit 2A
Outputs trigger pulse ₃ at the rising point of
Second trigger pulse circuit 2D and the above inverted signal
The second logical AND of Q ₁ and trigger pulse ₃
It is composed of an AND circuit 2E.

Next, the operation will be explained.

As shown in FIG. 2, when the pulse oscillation circuit 2A outputs the output signal _Q1 and its inverted signal ₁ , the first and second AND circuits 2C and 2E output the drive pulses A and B. Drive pulses A, B
The opening/closing states of the first and second switching 1A, 1C are controlled by.

That is, when the drive pulse A is 1, the drive pulse B is 0, so the first switching circuit 1A is closed, the second switching circuit 1C is open, and the third The signal holding circuit 1F is charged and the first switching circuit 1A
The measurement signal input to the first signal holding circuit 1B is inputted to the first signal holding circuit 1B which is composed of a capacitor via the first switching circuit 1A, and is stored in this capacitor. holds the signal.

Here, when the driving pulse A is in the state of 0 and the driving pulse B is in the state of 1, the first switching circuit 1A is in the open state, the second switching circuit 1C is in the closed state, and the first signal holding circuit 1B is in the closed state. The measurement signal held in the second switching circuit 1C
via the second signal holding circuit 1E and output. The second signal holding circuit 1E continues to hold the signal while the second switching circuit 1C is in the closed state, thereby enabling stable output.

Note that when insulating measurement signals from multiple channels using multiple isolation circuits, the drive pulses A,
B is applied to each isolated circuit. Further, the third signal holding circuit 1F has a function of removing noise to some extent and a function of accelerating charging of the first signal holding circuit 1B when the measurement input signal changes suddenly.

〔Effect of the invention〕

As explained above, the insulating circuit according to the present invention includes a capacitor _C0 , a pre-stage holding circuit 1F that stores and holds the input signal, and outputs the signal held in the pre-stage holding circuit by repeatedly opening and closing. A first switching circuit 1A and a capacitor
a middle-stage holding circuit 1B that includes C ₁ and stores and holds a signal output from the first switching circuit when the first switching circuit is in a closed state;
A second switching circuit 1C that outputs the signal held in the intermediate holding circuit by repeating opening and closing.
a second-stage holding circuit 1E that includes a capacitor _C2 and stores and holds a signal output from the second switching circuit when the second switching circuit is in a closed state; and the first and second switching circuits. The configuration includes a switching drive circuit 1D that alternately switches the open/closed state of the switch, and the front-stage holding circuit 1F can remove a certain amount of noise from the input signal, as well as continuously store and hold the input signal. The input signal can be transferred to the intermediate holding circuit 1B via the first switching circuit 1A.
When the measurement input signal suddenly changes when outputting to the intermediate stage holding circuit, charging of the middle stage holding circuit can be accelerated.

In addition, the second-stage holding circuit 1E allows the signal to be stored and held while the second switching circuit 1C is in the closed state, thereby enabling stable output. Furthermore, by closing the second switching circuit 1C while maintaining the power stored by the subsequent holding circuit 1E, the next input can be taken from the interruption holding circuit 1B, thereby speeding up signal processing. be able to.

Further, in the present invention, by combining three holding circuits including capacitors and two switching circuits, it is possible to create an extremely inexpensive and high-speed signal processing system with a simple circuit configuration.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing one embodiment of the present invention, and FIG.
The figure shows the output waveforms of each part of the switching drive circuit.
Figure 3 is a configuration diagram of a signal processing system using a conventional isolation circuit, and Figure 4 is a configuration diagram of another conventional signal processing system.
FIG. 5 is a block diagram of another conventional signal processing system. 1...Multiplexer, 2...Amplifier, 3...
A/D conversion circuit, 4...Insulation circuit, 1A...1st
switching circuit, 1B...first signal holding circuit (middle stage holding circuit), 1C...second switching circuit, 1D...switching drive circuit, 1E...
...Second signal holding circuit (second stage holding circuit), 1F...
...Third signal holding circuit (pre-stage holding circuit).

Claims (1)

[Claims] 1 A pre-stage holding circuit _1F that includes a capacitor C0 and stores and holds the input signal, a first switching circuit 1A that outputs the signal held in the pre-stage holding circuit by repeatedly opening and closing, and a capacitor. an intermediate holding circuit _1B that stores and holds the signal output from the first switching circuit when the first switching circuit is in the closed state;
, a second switching circuit 1C that outputs the signal held in the intermediate holding circuit by repeating opening and closing, and a capacitor C2, and when the second switching circuit is in the closed state, the second switching circuit _1C outputs the signal held in the intermediate holding circuit by repeatedly opening and closing. An insulating circuit characterized in that it comprises a rear-stage holding circuit 1E that stores and holds a signal output from the circuit, and a switching drive circuit 1D that alternately switches the opening and closing states of the first and second switching circuits.