JPH035073Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a non-contact type rotary relay used to switch the feedback voltage for zero point calibration of an electric micrometer constructed using an analog multiplexer and an up-down counter.

Conventional rotary relays and stepping relays are relays that sequentially switch a common terminal to a plurality of selection terminals each time a control signal is applied. A rotary relay changes the conduction point by energizing the forward rotation coil and the reverse rotation coil and moving the movable contact.
As shown in the figure, it is used in a circuit that generates a feedback voltage for zero point calibration of an electric micrometer. In the figure, 1 is a rotary relay, 1a is a common terminal, 1b, 1b... are selection terminals arranged in a ring, r, r... are each selection terminal 1b, 1
b... Voltage dividing resistor connected between, 2 is a transformer supplied with AC voltage that is shared with the AC power supply of the electric micrometer, R and R have a resistance value larger than that of the voltage dividing resistors r, r... The voltage dividing resistor, _R0 , is a high resistance for current limiting. This circuit is rotary relay 1
By switching the voltage, the magnitude of the AC voltage taken out from the high resistance _R0 can be varied at minute step intervals. By making the value ten times larger, a highly accurate output voltage can be obtained. Further, in the case of a stepping relay, only normal rotation is possible, but the principle is the same as that of the rotary relay 1 described above.

By the way, when the above-mentioned rotary relay or the like is used, in the circuit shown in FIG. 1, a minute current is passed through the contacts, so an oxide film is generated on the contact surfaces during use, and the contact resistance changes. This results in a disadvantage that the accuracy of the output voltage decreases. In addition, a forward or reverse rotation coil is used to move the movable contact.
During this operation, pulsed current is applied, which generates electromagnetic noise. In particular, when it is used in combination with electronic circuits that handle minute currents, it has the disadvantage of producing noise that cannot be ignored.

The present invention solves these problems by making the relay non-contact, in view of the drawbacks such as fluctuations and changes in impedance due to the opening and closing of minute currents, and noise generation when switching conduction points. That is, up-down counters are used in place of forward and reverse rotation coils, an analog multiplexer is used in place of movable contacts, and depending on the variation in low impedance when conducting the plurality of switch circuits in this analog multiplexer, If the voltage dividing resistor is made sufficiently large so that the voltage ratio does not fluctuate, and if the same voltage as before is supplied to the voltage dividing resistor that has been increased in this way, the current in the voltage dividing circuit becomes small and the S/N ratio deteriorates. In order to prevent the output signal from becoming unstable due to noise, a non-contact system solves these problems by placing an amplifier that amplifies the AC voltage before the voltage divider circuit. The aim is to provide rotary relays.

The switching circuit part of an embodiment of the present invention is shown in FIG. 2. 3 is an up-down counter, 4 is an analog multiplexer, 5u is a forward rotation input terminal, 5d is a reverse rotation input terminal, 6u and 6d are interface circuits,
7 ₀ , 7 ₁ . . . 79 are selection terminals, and Com is a common terminal. In this circuit configuration, when a normal rotation signal is input to the normal rotation input terminal 5u, the interface circuit 6u connects the up terminal UP of the up down counter 3.
A single pulse of an appropriate level and width is applied to increase the count number by one. Also, reverse input terminal 5d
When a reverse signal is input to , the interface circuit 6d similarly applies one pulse to the down terminal down to decrease the count number by one. Binary code outputs A, B, C, D of up-down counter 3
are the control terminals 4a, 4 of the analog multiplexer 4
It is input to b, 4c, and 4d. The analog multiplexer 4 has control terminals 4a, 4b, 4c, 4d.
Any one of the input terminals 4 ₀ , 4 ₁ ...49 determined by the binary code input to the output terminal
Change only the impedance between OUT and OUT to low impedance. Other input terminals 4 ₀ , 4 ₁ ... 4 ₉ ,
The impedance between the output terminals OUT is maintained at high impedance. Incidentally, the low impedance of this kind of analog multiplexer 4 is 0.1~
1.0KΩ, and high impedance is 10-100GΩ. Each input terminal 4 ₀ , 4 ₁ ... 4 ₉ is connected to each selection terminal 7 ₀ , 7 ₁ ... 7 ₉ , respectively, and the output terminal out is connected to the common terminal Com. ,4b,4c,
Only the impedance between one of the selection terminals 7 ₀ , 7 _{1 .} . . 7 ₉ corresponding to the binary code output inputted to 4d and the common terminal Com becomes low impedance,
It becomes connected. The above control terminals 4a, 4b, 4
The output signal of the up-down counter 3 input to terminals c and 4d increases or decreases by 1 each time a forward rotation signal or a reverse rotation signal is input, so that the output signal of the up-down counter 3 inputted to terminals c and 4d increases or decreases by one each time a forward rotation signal or a reverse rotation signal is input. The connected selection terminals 7 ₀ , 7 _{1 .} . . 7 ₉ are sequentially selected one by one and have the same function as a rotary relay.

Next, an embodiment in which the present invention is used in place of the rotary relay 1 of the feedback switching circuit for zero point calibration of an electric micrometer shown in FIG. 1 will be described.

As shown in FIG. 3, like the conventional rotary relay 1 shown in FIG. 1, the non-contact rotary relay 8 of the present invention has voltage dividing resistor holes r',
A voltage dividing circuit in which constant voltages e ₀₁ , e ₀₂ are applied across r'... is connected to the selection terminals 7 ₀ , 7 ₁ , . . . 7 ₉ .
The voltage dividing resistors r', r'... are connected between the selection terminals ₇₀ , ₇₁ ... ₇₉ , and the selection terminals ₇₀ , ₇₁ ... ₇₉ are the input terminals of the analog multiplexer 4, respectively, as described above. 4 ₀ , 4 ₁ ...4 ₉ in a one-to-one correspondence. The above-mentioned constant voltage is provided by an amplifier 9 connected to the transformer 2 via voltage dividing resistors R, R having a large resistance value. The analog multiplexer 4 selectively outputs one of the divided voltages of the voltage dividing circuit from the output terminal out in accordance with the count output of the up-down counter 3. Note that the output voltages e ₀₁ and e ₀₂ of the two output terminals of the amplifier 9
are the input terminal voltages e ₁ , e ₂ and built-in resistance R ₁ , respectively.
For R ₂ , e ₀₁ = (1 + R ₂ / R ₁ ) e ₁ − R ₂ / R ₁ e ₂ , e ₀₂ = (1 + R ₂ / R ₁ ) e ₂ − R ₂ / R ₁ e ₁ , . The amplification factor of this amplifier 9 is set to about 1000 times, and the voltage dividing resistors r', r'... connected to each selection terminal 7 ₀ , 7 ₁ ... 7 ₉ are, for example, the voltage dividing resistors of the conventional rotary relay 1. Compared to the 5.1Ω of r, r..., it is set to 5.1KΩ, which is 1000 times that value. This configuration allows current above a certain level to flow through the voltage divider circuit,
It is possible to maintain stability against the noise of the divided AC voltage and increase the resistance value that can be switched, so that the ON state between each terminal of the analog multiplexer 4 can be increased.
Variations in low impedance resistance can be ignored.

As explained above, the present invention divides the voltage of a rotary relay using a combination of an analog multiplexer, an up-down counter, and a larger voltage dividing resistor, and generates an AC signal that is amplified with an amplification factor commensurate with the increase in resistance. Since it is configured with a voltage divider circuit that divides the voltage and has achieved contactless operation, it eliminates malfunctions caused by changes in contact resistance caused by passing minute currents, which had been a problem with contact type rotary relays, and the zero point of an electric micrometer. It is possible to switch the feedback voltage for calibration while maintaining the necessary high accuracy, and since no electromagnetic coil is used for contact switching, no electromagnetic noise is generated. Furthermore, since no mechanical contacts are used, a rotary relay with a long life can be obtained.

[Brief explanation of drawings]

Figure 1 is a circuit diagram of an example of a device using a conventional rotary relay, Figure 2 is a circuit diagram of an embodiment of the present invention,
FIG. 3 is a circuit diagram of an example of a device using the rotary relay of the present invention. 3... Up-down counter, 4... Analog multiplexer, 5u... Forward rotation input terminal, 5d
...Reverse input terminal, 7 ₀ , 7 ₁ ... 7 ₉ ... selection terminal, Com ... common terminal.

Claims (1)

[Claim for Utility Model Registration] A device used to switch the feedback voltage for zero point calibration of an electric micrometer, which includes an amplifier for amplifying an AC voltage common to the AC power supply of the electric micrometer, and a plurality of voltage dividing resistors. connected in series, and has a voltage divider circuit that receives the output of the above amplifier at both ends, a plurality of input terminals that respectively receive the plurality of divided voltages of the voltage divider circuit, and a common output terminal, and has a common output terminal, and has a common output terminal. An analog multiplexer that changes only between one input terminal selectively determined by the signal and a common output terminal from a non-conducting state of high impedance to a conducting state of low impedance, and a forward rotation signal to the up terminal. an up-down counter that inputs a reverse signal to a down terminal and supplies a count output to the analog multiplexer as a control signal, and the voltage dividing resistor of the voltage dividing circuit maintains continuity between each input terminal and output terminal of the analog multiplexer. The resistance value should be sufficiently large so that the voltage division ratio does not change due to variations in low impedance during operation, and the amplification factor of the amplifier should be set to a large S. /N
A non-contact rotary relay characterized by being sized to allow a current large enough to flow to give a ratio.