JPH0546351Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Field of Application> The present invention relates to a transformer-insulated multiplexer and aims to increase its speed and simplify its configuration.

<Prior Art> A conventional transformer-insulated multiplexer is shown in FIGS. 1a and 1b and FIGS. 2a and 2b.

In Figure 1 a, CH ₁ to CHn are plural (n pieces)
SW ₁ to SWn are selector switches that select each input signal, T ₁ to Tn are the primary transformer windings for each input signal, Tr is the secondary transformer winding, and 1 is the secondary transformer. 2 is a sample-and-hold circuit that samples and holds the output of the amplifier 1; 3 is an analog-to-digital converter that converts the sample-and-hold value into a digital signal; and OUT is an output terminal.

The conventional transformer-insulated multiplexer shown in FIGS. 1a and 1b operates as follows.

Among multiple input signals, for example, switch SW ₁
When input terminal CH ₁ is selected by turning on, the input signal E ₁ passes through the primary transformer winding T ₁ and
This signal is sent to the next transformer winding Tr, is amplified by the amplifier 1, sampled and held by the sample and hold circuit 2, and is output from the analog-to-digital converter 3 from the output terminal out.

Next, turn off switch SW ₁ and turn off switch SW _2.
Turn on and select input signal E ₂ from input terminal CH ₂ . At this time as well, the output signal is output from the output terminal out, as described above.

Thereafter, similarly, output is performed by sequentially switching up to switch SWn.

However, in such a device, FIG.
As shown in , the transformer does not pass direct current, and a backswing S2 occurs (area S1 = S2) with respect to the transformer magnetic flux (corresponding to S1) corresponding to the input signal _E1 .
However, the next input signal cannot be input until this backswing converges to 0, and the read cycle T
needs to be sufficiently long compared to t, making it difficult to speed up input.

One solution to this problem is shown in FIGS. 2a and 2b.

In FIG. 2a, two switch elements are used to read the input signal as positive or negative. This device is
A signal line is drawn out in the middle of the transformer winding for each input terminal CH ₁ to _{CH o} , and switch elements are provided at both ends of the transformer winding. The rest of the configuration is the same as that in FIG. 1.

In this configuration, for example, when the input terminal CH ₁ is selected, the switch SW ₁ is turned on at a period of t ₁ (=t), and then the switch SW ₁₂ is turned on at a period of t ₂ (=t).

In this way, the positive polarity input and the reverse polarity input of the input signal E1 are read alternately, S ₁ = S ₂ without waiting for the backswing S ₂ to converge with respect to the input signal, and the transformer is reset at a period of 2t. Therefore, the input reading cycle T can be significantly shortened.

However, this device also has the disadvantage that the number of transformer windings and switch elements doubles, making its configuration and control complex.

<Purpose of the invention> In view of the above-mentioned drawbacks, it is an object of the present invention to provide a transformer-insulated multiplexer that has a simple configuration and can read input signals at high speed.

<Configuration of the Invention> In the present invention, a plurality of input signals are supplied to the corresponding primary transformer winding of the isolation transformer when a changeover switch is turned on, and the secondary transformer winding of the isolation transformer is controlled based on the supplied signals. In a transformer-insulated multiplexer that amplifies a signal induced in the transformer winding with an amplifier and outputs the signal through a sample-and-hold circuit and an analog-to-digital converter, a The transformer is turned on when the transformer is turned on, generates a reset magnetic flux by being given a signal corresponding to the output signal sent from the sample and hold circuit, and has a reset winding that resets the transformer magnetic flux generated by the input signal. This is a transformer-insulated multiplexer.

<Example> An embodiment of the present invention is shown in FIGS. 3a and 3b.

The feature of this invention is that the two transformers that receive the signal
This is because the reset winding TR is provided on the next side.

A value obtained by sample-holding a received signal amplified by an amplifier 1 by a sample-and-hold circuit 2 is applied to the reset winding TR via a switch element SWR.

And switch SWR is switch SW ₁ ~
In conjunction with SWn, it is controlled to be off when the switches SW ₁ to SWn are on, and to be on when the switches SW ₁ to SWn are off.

The operation of the embodiment of the present invention configured as described above will be described below.

For example, among multiple input signals, input terminal CH ₁
The operations of selecting a signal, amplifying it with the amplifier 1, sample-holding it, converting it into analog-to-digital data, and outputting it are the same as in the conventional device.

As shown in FIG. 3b, the switch _SW1 is in
When the switch SWR is turned on, the switch SWR is turned on for a period tr, and a signal Er corresponding to the output signal is applied from the sample and hold circuit 2 to the reset winding TR. This signal Er generates a reset magnetic flux in the reset winding TR, and the transformer magnetic flux generated by the input signal _E1 is reset. On the other hand, the sampled and held values are converted by the analog-to-digital converter 3 and output from the output terminal out.

That is, the transformer magnetic flux corresponding to the area S1 is reset by the reset magnetic flux SR corresponding to the area SR.

In this state, the next input signal can be read, input terminal CH2 is selected, and the transformer magnetic flux is reset by the same operation.

Further, if the turn ratio between the number of turns N of the transformer windings T ₁ to _{T o} and the number of turns NR of the reset winding TR is 1, the magnetic flux can be reset in the reset time tr=tE ₁ /Er. In this way, by changing the number of turns of the reset transformer Tr, the reset time tr can be shortened, and the input signal reading period T can be shortened.

<Effects of the invention> As described above, according to the invention, since the reset winding is provided on the secondary side of the transformer, it is possible to obtain a transformer-insulated multiplexer that can read input signals at high speed and has a simple configuration. I can do it.

[Brief explanation of the drawing]

Figure 1a is a diagram of a conventional transformer isolated multiplexer, Figure 1b is a time chart for explaining the operation of a conventional transformer isolated multiplexer, Figure 2a is a diagram of a conventional transformer isolated multiplexer, and Figure 2a is a diagram of a conventional transformer isolated multiplexer. Figure 2b is a time chart for explaining the operation of a conventional transformer isolated multiplexer, Figure 3a is a diagram of a transformer isolated multiplexer according to an embodiment of the present invention, and Figure 3b is a diagram of a transformer according to an embodiment of the present invention. A time chart to explain the operation of an isolated multiplexer. 1...Amplifier, 2...Sample hold circuit,
3...Analog-digital converter, CH ₁ ~ _{CH o} ...
…Input terminal, SW ₁ ~ SW _o , SW ₁₁ ~ SW _o2 , SWR
...Switch element, _T1 to T _o ...Primary side transformer winding, Tr...Secondary side transformer winding, TR...Reset winding, out...Output terminal.

Claims (1)

[Scope of utility model registration request] A plurality of input signals are each supplied to the corresponding primary transformer winding of the isolation transformer when the changeover switch is turned on, and a signal induced in the secondary transformer winding of the isolation transformer is generated based on the supplied signals. In a transformer-isolated multiplexer that amplifies the signal with an amplifier and outputs the signal through a sample-and-hold circuit and an analog-to-digital converter, the switch is connected in parallel to the secondary transformer winding and is turned on after the changeover switch is turned on, and the output is output from the sample-and-hold circuit. A transformer-insulated multiplexer comprising a reset winding that generates a reset magnetic flux when given a signal corresponding to the output signal sent out and resets the transformer magnetic flux generated by the input signal.