JP2013040901A - Voltage signal selection device and multipoint recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a voltage signal selection device which has high noise removal performance and is capable of increasing a voltage signal scanning speed, in consideration of the fact that it has been impossible to increase a time constant of a filter for noise removal and to increase the scanning speed because the filter has been disposed in a succeeding stage of a switch for voltage signal selection.SOLUTION: A voltage signal to be selected is inputted to a filter to remove noise, and the signal from which the noise has been removed is selected by a selection part. Since the input signal of the filter is not varied by switching of the selection part, a time constant of the filter can be increased and a switching speed can be increased.

Description

  The present invention relates to a selection device that selects and outputs one of a plurality of voltage signals, a voltage signal selection device capable of removing noise and increasing the selection frequency, and a multipoint recording device using the voltage signal selection device It is about.

  The voltage signal selection device is a device that selects and outputs one of a plurality of voltage signals. A temperature measuring device using a thermocouple, a voltage measuring device, a multi-point scanner type waveform measuring device, a multi-point recorder, Or it is used for the input part of multipoint recording devices, such as a data logger.

  FIG. 5 shows a configuration of a conventional voltage signal selection device. In FIG. 5, reference numerals 10 to 12 denote input terminals to which voltage signals 1 to 3 are applied, respectively. The input terminals 10 to 12 are composed of two terminals, that is, an H terminal and an L terminal. A high level side signal of a voltage signal is applied to the H terminal, and a low level side signal is applied to the L terminal.

  Reference numeral 13 denotes a switch unit, which includes switches 13a and 13b that are turned on and off. One ends of the switches 13a and 13b are connected to the H terminal and L terminal of the input terminal 10, respectively. The other end of the switch 13b is connected to a common potential point.

  Reference numerals 14 and 15 denote switch units, which are composed of two switches like the switch unit 13. One end of two switches constituting the switch units 14 and 15 is connected to the H terminal and L terminal of the input terminals 11 and 12, respectively, and the other end of the switch corresponding to the switch 13b is connected to a common potential point.

  Reference numeral 16 denotes a low-pass filter, which includes a resistor 16a and a capacitor 16b. One end of the resistor 16a is connected to the switch 13a and the corresponding switch of the switch units 14 and 15. A capacitor 16b is connected between the other end of the resistor 16a and the common potential point.

  Reference numeral 17 denotes an amplifier to which the output signal of the filter 16 is input. In the case of a multi-point recording device, the output signal of the amplifier 17 is converted into a standardized signal using an attenuator (not shown), noise is removed by an analog filter, and converted to a digital value by an analog-digital converter. Is done. As the analog-digital converter, a charge redistribution type, an integration type, a ΔΣ type, or the like is used.

  Next, the operation of this voltage signal selection device will be described. The switch units 13 to 15 are controlled in turn so that only one switch unit is turned on at a time. That is, when the switch unit 13 is on (the switches 13a and 13b are on), the switch units 14 and 15 are turned off.

  When the switch unit 13 is turned on, the voltage signal 1 is input to the filter 16 to remove noise, amplified by the amplifier 17 and output. When the switch units 14 and 15 are on, the voltage signal 2 and the voltage signal 3 are input to the filter 16, respectively. Thus, the voltage signals 1 to 3 are selected in order and output from the amplifier 17.

  A pair of input terminal and switch unit constitutes one channel. This voltage signal selection device has three channels, and voltage signals 1 to 3 are applied to each channel. Note that the number of channels may be four or more.

  Patent Document 1 describes a multipoint recorder having a voltage signal selection device having a configuration similar to that shown in FIG. FIG. 4 of Patent Document 1 describes a configuration in which one of a plurality of voltage signals is selected by the input switching mechanism 2, amplified by the amplifier 3, and converted into a digital value by the A / D converter 4.

JP-A-9-210734

However, such a voltage signal selection device has the following problems.
In FIG. 5, after the voltage signal is selected by the switch units 13 to 15, noise is removed by the filter 16. Immediately after the input signals are switched by the switch units 13 to 15, the voltage level of the signal input to the filter 16 varies greatly.

  In order to improve the noise removal performance of the input voltage signal, the break frequency of the filter 16 must be lowered. However, when the break frequency is lowered, the influence of fluctuation immediately after switching remains long, and the filter 16 An error occurs in the output signal. For this reason, since it has to wait until this fluctuation | variation disappears, there existed a subject that switching speed could not be made quick.

  For example, in order to remove the commercial frequency component, the resistance value of the resistor 16a must be 10 kΩ, the capacitance value of the capacitor 16b must be 1 μF, and the filter must have a break frequency of about 16 Hz. Since the time constant of a filter having a break frequency of 16 Hz is 10 mS, the switching time by the switch units 13 to 15 must be several times that in consideration of signal stability. For this reason, it takes several seconds to sample 16 channels.

  In addition, when trying to increase the switching speed, the break frequency of the filter 16 has to be increased, and there is a problem that noise cannot be sufficiently removed.

  An object of the present invention is to realize a voltage signal selection device capable of reducing the time constant of a filter for removing noise and increasing the switching speed, and a multipoint recording device using the voltage signal selection device.

In order to achieve such a problem, the invention according to claim 1 of the present invention is:
In the voltage signal selection device for selecting and outputting a plurality of voltage signals,
A plurality of filters corresponding to the plurality of voltage signals on a one-to-one basis, the corresponding voltage signal being input, and a signal having a predetermined frequency range passing therethrough;
A selection unit that receives the output signals of the plurality of filters, and selects and outputs one of these signals;
It is equipped with. Noise such as commercial frequency components can be removed and the selection speed can be increased.

The invention according to claim 2 is the invention according to claim 1,
A low bass filter is used as the filter. High frequency noise such as commercial frequency components can be removed.

The invention according to claim 3 is the invention according to claim 1 or 2,
The voltage signal is a differential voltage signal. Can handle differential signals.

The invention according to claim 4
The voltage signal selection device according to any one of claims 1 to 3, wherein a plurality of voltage signals are input;
A value related to the output signal of the voltage selection device is input, and a recording control unit for recording the input value;
Is provided. Noise can be removed and scanning speed can be increased.
Is.

The present invention has the following effects.
According to the first, second, and third aspects of the present invention, the voltage signal is input to the filter to remove noise, and the signal from which the noise has been removed is selected by the selection unit.

  Since the filter is arranged before the selection unit, the input signal of the filter is not affected by the operation of the selection unit. For this reason, the switching speed of the selection unit can be increased and the time constant of the filter can be increased. Therefore, there is an effect that low frequency noise such as noise caused by the commercial frequency can be removed.

  Further, since the input signal of the filter is not affected by the operation of the selection unit, the operation of the selection unit can be speeded up. In particular, an apparatus that repeats the operation of scanning a plurality of voltage signals has an effect that the scanning speed can be increased.

  Furthermore, according to claim 4, by applying this voltage signal selection device to a multi-point recording device, noise can be removed and the scanning speed can be increased, so that a fast-changing signal can be recorded accurately. There is also an effect that can be done.

It is the block diagram which showed one Example of this invention. It is the flowchart which showed operation | movement of the apparatus of FIG. It is the block diagram which showed the other Example of this invention. It is a block diagram of the multipoint recording device which concerns on this invention. It is a block diagram of the conventional voltage signal selection apparatus.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a voltage signal selection device according to the present invention. The same elements as those in FIG. 5 are denoted by the same reference numerals and description thereof is omitted.

  In FIG. 1, voltage signals 1 to 3 are applied to input terminals 10 to 12, respectively. The high voltage side signals of these voltage signals are respectively applied to the H terminals of the input terminals 10 to 12, and the low voltage side signals are respectively applied to the L terminals of the input terminals 10 to 12.

  Reference numeral 20 denotes a filter, which includes a resistor 20a and a capacitor 20b. One end of the resistor 20a and one end of the capacitor 20b are connected. The resistor 20a and the capacitor 20b constitute a primary low-pass filter. The other end of the resistor 20a is connected to the H terminal of the input terminal 10, and the other end of the capacitor 20b is connected to the L terminal.

  Reference numerals 21 and 22 denote filters, which have the same configuration as the filter 20. The other ends of the resistors in the filters 21 and 22 are connected to the H terminals of the input terminals 11 and 12, respectively, and the other ends of the capacitors in the filters 21 and 22 are connected to the L terminals of the input terminals 11 and 12. That is, the filters 20 to 22 correspond to the voltage signals 1 to 3 on a one-to-one basis, and the corresponding voltage signals are input.

  Low-pass filters are used as the filters 20-22. Filters 20 to 22 remove high-frequency noise contained in voltage signals 1 to 3 applied to input terminals 10 to 12, respectively. The filters 20 to 22 pass only the frequency component in the signal region and remove the frequency component in the noise region.

  Reference numeral 23 denotes a selection unit, which includes switch units 13-15. Both ends of the capacitor 20b are connected to one terminal of two switches constituting the switch unit 13, respectively. Similarly, both ends of the capacitors in the filters 21 and 22 are connected to one terminals of two switches constituting the switch units 14 and 15, respectively. The voltage across the capacitor 20b and the capacitors in the filters 21 and 22 are output signals of the filters 20 to 22, respectively. That is, the output signals of the filters 20 to 22 are input to the switch units 13 to 15, respectively.

  Of the two switches constituting the switch units 13 to 15, the other end of the switch connected to the connection point of the resistor and the capacitor is connected to the input terminal of the amplifier 17. The other end of the other switch is connected to a common potential point. The voltage signal selected by the selector 23 is input to the amplifier 17.

  The two switches in the switch units 13 to 15 operate in conjunction with each other. Assume that when these two switches are on, the corresponding switch section is on, and when the two switches are off, the corresponding switch section is off.

  Reference numeral 24 denotes a filter, which includes a resistor 24a and a capacitor 24b. One end of the resistor 24a and the capacitor 24b is connected, the other end of the resistor 24a is connected to the output terminal of the amplifier 17, and the other end of the capacitor 24b is connected to a common potential point. The resistor 24a and the capacitor 24b constitute a primary low-pass filter. The filter 24 removes noise included in the output signal of the amplifier 17.

  The input terminal and the filter and switch unit connected thereto (for example, the input terminal 10, the filter 20, and the switch unit 13) constitute a channel. This voltage signal selection device has three channels, and voltage signals 1 to 3 are applied to the respective channels.

  Next, the operation of this embodiment will be described based on the flowchart of FIG. Note that the number of channels is 3, and voltage signals 1 to 3 are applied to the input terminals 10 to 12, respectively.

  In FIG. 2, first, all the switch parts 13-15 are turned off by a process (P2-1). Next, in step (P2-2), the switch unit 13 is turned on. The voltage signal 1 is input to the amplifier 17 via the switch unit 13 and output via the filter 24. In the step (P2-3), the voltage signal 1 is measured by a measuring device (not shown), and after the measurement, the switch unit 13 is turned off in the step (P2-4), and a predetermined time is waited in the step (2-5) .

  Next, the switch part 14 is turned on by a process (P2-6). The voltage signal 2 is input to the amplifier 17 via the switch unit 14 and output via the filter 24. In the step (P2-7), the voltage signal 2 is measured by a measuring device (not shown). After the measurement is completed, the switch unit 14 is turned off in the step (P2-8), and the process waits for a predetermined time in the step (2-9). .

  Next, the switch unit 15 is turned on in step (P2-10). The voltage signal 3 is input to the amplifier 17 via the switch unit 15 and output via the filter 24. In the step (P2-11), the voltage signal 3 is measured by a measuring device (not shown). After the measurement is completed, the switch unit 15 is turned off in the step (P2-12), and a predetermined time is waited in the step (2-13). .

  Next, in step (P2-14), it is determined whether or not all measurements are finished. If it is determined that all measurements are not finished (NO), the process returns to step (P2-2) and the same steps are repeated. The reason for waiting for a predetermined time in the steps (P2-5), (P2-9), and (P2-13) is to avoid interference with channels that are turned on before and after.

  As is clear from FIG. 1, the filters 20 to 22 are arranged in front of the switch units 13 to 15, respectively. For this reason, even if switch part 13-15 switches, the input signal of filters 20-22 does not change.

  Accordingly, the time constants of the filters 20 to 22 can be set regardless of the operation of the switch units 13 to 15. For example, if the resistor 20a is 10 kΩ and the resistor 20b is 1 μF, the break frequency (frequency at which 3 dB is attenuated) of the filter 20 is 16 Hz, and the commercial frequency component can be sufficiently attenuated.

  As described above, the voltage signal input to the filters 20 to 22 is not affected by the operation of the switch units 13 to 15. Accordingly, the ON / OFF cycle of the switch units 13 to 15 can be set by characteristics such as the operation / recovery time (for example, 1 mS) of the switch unit itself regardless of the time constant of the filters 20 to 22. For example, if the processing time per channel is set to several mS including the standby time, each channel can be measured at a cycle of about 100 mS even if the number of channels is 16.

  Although the number of channels is 3 in FIG. 1, it may be 2 or 4 or more. The number of channels can be arbitrarily determined based on the number of voltage signals to be measured and the required measurement period.

  FIG. 3 shows an embodiment when the voltage signal is a differential signal. In addition, the same code | symbol is attached | subjected to the same element as FIG. 1, and description is abbreviate | omitted.

  In FIG. 3, reference numeral 30 denotes a filter, which includes resistors 30a and 30b and a capacitor 30c. One ends of the resistors 30a and 30b are connected to the H terminal and the L terminal of the input terminal 10, and the other ends are connected to both ends of the capacitor 30c.

  31 and 32 are filters, which are composed of two resistors and one capacitor as in the case of the filter 30. One ends of the resistors in the filters 31 and 32 are connected to the H terminal and the L terminal of the input terminals 11 and 12, respectively. That is, the differential voltage signal 1 to the differential voltage signal 3 are input to the filters 30 to 32, respectively.

  Reference numeral 33 denotes a selection unit, and 34 to 36 denote switch units. The selection unit 33 includes switch units 34 to 36.

  The switch unit 34 is composed of two switches, like the switch unit 13. One ends of these two switches are connected to both ends of the capacitor 30c. The switch units 35 and 36 have the same configuration as the switch unit 34. One ends of the switches in the switch sections 35 and 36 are connected to the output sides of the filters 31 and 32, respectively. That is, the output signals of the filters 30 to 32 are input to the switch units 34 to 36, respectively.

  Reference numeral 39 denotes a differential amplifier. The other ends of one of the switches in the switch units 34 to 36 are connected in common and connected to the non-inverting input terminal of the differential amplifier 39. The other ends of the other switches in the switch units 34 to 36 are connected in common and connected to the inverting input terminal of the differential amplifier 39. The output of the differential amplifier 39 is input to the filter 24. The voltage signal selected by the selector 33 is input to the differential amplifier 39.

  Reference numerals 37 and 38 denote diodes connected in series, the cathode of which is connected to the positive power supply Vcc, and the anode of which is connected to a common potential point. The connection point of the two diodes is connected to the non-inverting and inverting input terminals of the differential amplifier 39, respectively. The diodes 37 and 38 prevent an overvoltage from being applied to the differential amplifier 39.

  Voltage signals 1 to 3 are applied to the input terminals 10 to 12, respectively. These voltage signals are noise-removed by filters 30 to 32, selected by switch units 34 to 36, and input to differential amplifier 39.

  The operation is almost the same as the flowchart in FIG. The switch units 34 to 36 are turned on in order, and the voltage signal 1 to the voltage signal 3 are sequentially input to the differential amplifier 39. Also in this embodiment, since the filters 30 to 32 are respectively arranged in front of the switch units 34 to 36, the time constants of the filters 30 to 32 can be set regardless of the operation of the switch units 34 to 36.

  FIG. 4 shows a configuration of a multipoint recording apparatus using the voltage switching apparatus of FIG. 1 or FIG. In FIG. 4, reference numeral 40 denotes a voltage signal selection device having the configuration shown in FIG. The voltage signal selector 40 receives n input signals 1 to n. As shown in the flowchart of FIG. 2, the voltage signal selection device 40 repeats the operation of selecting and outputting the input signals 1 to n one by one.

  Reference numeral 41 denotes an A / D converter, which receives an output signal from the voltage signal selector 40, converts the input signal into a digital value, and outputs the digital value.

  Reference numeral 42 denotes a calculation unit, to which a digital value converted by the A / D converter 41 is input. The calculation unit 42 stores the input digital value in the temporary storage unit 43, performs calculation processing such as rearranging the order, and outputs the result.

  Reference numeral 44 denotes a recording control unit, to which the result of calculation processing by the calculation unit 42 is input. The recording control unit 44 records the input digital value. For example, a multipoint recorder selects a pen of a color corresponding to an input signal, controls a carriage motor that moves the pen, moves the pen, and hits a dot. In the data logger, information such as measurement time is added to the input digital value and stored, and transmitted to the outside.

  In the flowchart of FIG. 2, the switch unit is operated to select a plurality of voltage signals in order, but the selection is not necessarily performed in order. What is necessary is just to select a several voltage signal according to the determined rule.

  Moreover, although the selection parts 23 and 33 were comprised with the some switch part, it is not necessarily limited to this structure. In short, any configuration that selects and outputs one of a plurality of voltage signals may be used.

  Further, the filters 20 to 22 and 30 to 32 are primary low-pass filters configured by resistors and capacitors, but are not limited to this configuration. Any other configuration may be used as long as it can pass the frequency component of the signal and remove the noise superimposed on the voltage signal, and it may not be a low-pass filter.

  In addition, although the voltage signals selected by the selectors 23 and 33 are input to the amplifiers 17 and 39 and the filter 24, the amplifiers 17 and 39 and the filter 24 can be omitted.

  Further, the A / D converter 41 and the calculation unit 42 in FIG. 4 are not essential elements. The selected voltage signal may be input to the recording control unit 44.

  Furthermore, this voltage signal selection device can be applied not only to the multipoint recorder or data logger shown in FIG. 4 but also to other devices that are required to select a plurality of voltage signals.

10-12 Input terminals 13-15, 34-36 Switch unit 17 Amplifier 20-22, 24, 30-32 Filter 20a, 24a, 30a, 30b Resistor 20b, 24b, 30c Capacitor 23, 33 Selector 39 Differential amplifier 40 Voltage signal selection device 41 A / D converter 42 arithmetic unit 43 temporary storage unit 44 recording control unit

Claims (4)

In the voltage signal selection device for selecting and outputting a plurality of voltage signals,
A plurality of filters corresponding to the plurality of voltage signals on a one-to-one basis, the corresponding voltage signal being input, and a signal having a predetermined frequency range passing therethrough;
A selection unit that receives the output signals of the plurality of filters, and selects and outputs one of these signals;
A voltage signal selection device comprising:   The voltage signal selection device according to claim 1, wherein the filter is a low-pass filter.   3. The voltage signal selection device according to claim 1, wherein the voltage signal is a differential voltage signal. The voltage signal selection device according to any one of claims 1 to 3, wherein a plurality of voltage signals are input;
A value related to the output signal of the voltage selection device is input, and a recording control unit for recording the input value;
A multi-point recording apparatus comprising:

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