JPH02265315A - Method and apparatus for shaping waveform - Google Patents

Abstract

PURPOSE:To convert the period of an AC component into a rectangular wave accurately by making DC levels equal to each other, deviating the phase of an AC component, separating an original signal into two signals to apply comparison processing. CONSTITUTION:A source signal e1 in which an AC component is superimposed on a DC component such as the output of a contactless displacement sensor mainly and an output signal ek of a DC amplifier 6 are inputted to a comparator 1 as a differential input through input resistors 3,4. The same source signal e1 is supplied to signal input terminals of both the input resistors 8, 9 of the DC amplifier 6. An integration circuit comprising an input resistor Rp, 7 and a capacitor Cp,11 is formed to a noninverting input terminal + of the DC amplifier 6. A signal being the result of the phase of the DC signal component with the same polarity as the input source signal e1 shifted till the phase is inverted by 180 deg. is outputted at a point K at the output terminal of the DC amplifier 6.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention is a non-contact speed sensor that detects the number of rotations and rotational speed of a rotating body using a non-contact displacement sensor and a rotating body with gears or irregularities. The present invention relates to a signal waveform shaping method in a detection device and its device.

[Prior Art] A conventional non-contact speed detection device has the following features as shown in FIG.
The distance (d) of the surface unevenness (C) of the rotating body (B) facing the non-contact displacement sensor (A) is detected by an output signal corresponding to the distance (d) in analog form, as shown by the voltage waveform (D). , the voltage waveform (D) of the output signal is compared with an analog comparator, the valley (E) part and the peak (F) part of the unevenness (C) are distinguished, and the moving speed of the valley (E) and peak (F) is determined. A rectangular wave (G) is generated according to the .

[Problem to be solved by the invention] When the rotating body (B) is a gear or the like, the output waveform (D) of the displacement sensor (A) may not necessarily be an electrically uniform waveform depending on the machining accuracy of the gear. There are some changes.

This waveform variation appears as a variation in the DC level of the electrical signal of the output waveform (D).

In addition, as shown in FIG. 7, the output waveform (D) is
), the displacement sensor (A)
The amplitude (X
i) (X, ) and DC level (V 1) (V 1) change. Therefore, the machining state of the rotating body and the displacement sensor (A)
The reference voltage of the comparator must be adjusted to an appropriate value according to the initial setting distance (d 5 ) (ci *>).

Note that the peak (F) portion is a solid line, and the valley (E) portion is a dotted line, indicating their respective output characteristics.

Furthermore, as shown in FIG. 8, the output level also varies depending on the ambient temperature (θ) of the displacement sensor (A).

When these conditions become worse, the conventional analog comparator that sets the DC level as the reference voltage (V,) will malfunction, resulting in one peak error count, as shown in Figure 9. occurs.

[Means for Solving the Problem] According to the present invention, in waveform shaping that generates a rectangular signal that matches the period of the main waveform of an AC signal from a signal in which an AC component is superimposed on a DC component, an AC component is superimposed on a DC component. By comparing signals with different phases of the main waveforms of the AC components of this source signal with the source signal superimposed with generating a rectangular signal that matches the period of a waveform; a comparison amplifier having one of its comparison input terminals inputting a source signal in which an AC component is superimposed on a DC component; and using the source signal as an input signal; The above problem is solved by a DC amplifier that outputs only the AC components of the input signal with different phases, and inputs this output signal to the other comparison input terminal of the comparison circuit.

[Function] By setting the DC level equally and shifting the phase of the AC component, one original signal is separated into two signals and compared, the repetition period of the AC component is accurately converted into a rectangular wave. Convert.

[Example] FIG. 1 shows an embodiment of the present invention.

(1) is an operational amplifier (2) and an input resistor (3) (4)
and a feedback resistor (5).

(6) is the operational amplifier (7) and the input resistors (8) and (9).
This is a differential DC amplifier comprising a feedback resistor (lO), and an integrating capacitor (11).

The comparator (1) receives a source signal (e,) in which an AC component is superimposed on a DC component, such as that output by a non-contact displacement sensor, and an output signal (e,) from a DC amplifier (6). ,
) is input as the differential human power of each of the input resistors (3) and (4).

The same source signal (e,) is applied to the signal input ends of both input resistors (8) and (9) of the DC amplifier (6).

The non-inverting input terminal (+) of the DC amplifier (6) is connected to an input resistor (RP) (7) and a capacitor (CF) (11).
An integral circuit is formed by these.

The time constant of this integrating circuit is appropriately determined by the main frequency of the AC component.

Further, by appropriately selecting the time constant of this integrating circuit, it is possible to provide hysteresis in the inversion operation of the output signal (eo).

Figure 3 shows the frequency characteristics of the gain and phase of the DC amplifier (6), and as is clear from this characteristic, the DC amplifier (6)
At the point at the output end of 6), there is a signal in which the DC signal component has the same polarity and magnitude as the input source signal (el), and the phase of the AC signal component is significantly shifted until the phase is reversed by 180 degrees. can be obtained.

In Figure 2, the output AC component of the DC amplifier (6) is amplified to almost the same level as the AC component of the source signal (el), and the comparator (1) 1
) (e-).

The signal (e,) is the non-inverting input terminal (
+) at the voltage at point M, the integral value of the source signal (el),
That is, it corresponds to a direct current component, and the comparator (1) operates as if the signal (e,) is the reference voltage.

Figure 4 shows the output signal of the non-contact displacement sensor as the source signal (e,
) shows the operating state of the device of the present invention.

As described above, according to the present invention, when the distance (d) between the non-contact displacement sensor and the surface irregularities (teeth) of the rotating body (gear) is small and the signal levels are large for both the DC and AC components,
Furthermore, even if the distance (d) is large and the signal levels of both the DC and AC components are small, the period of the main AC component of the output signal (eo) to be waveform-shaped will definitely be a rectangular wave. has been converted.

Figure 5 shows the operating state when the waveform of the AC component of the source signal (e+) becomes irregular due to the mechanical accuracy of the gear, mechanical vibration, temperature shock, etc. , the output signal (eo) reliably converts the period of the main AC component into a rectangular wave.

[Effect] The DC signal component included in the signal as an offset voltage is
Even if the wave is caused by fluctuations in mechanical, temperature, electrical, etc. elements, it is possible to obtain a rectangular wave that matches the period of the main waveform of the AC signal component superimposed on the DC signal component.

[Brief explanation of drawings]

Fig. 1 is an electric circuit diagram showing an embodiment of the present invention, Fig. 2 is a waveform diagram showing the operating state of the circuit in Fig. 1, and Fig. 3 is a frequency characteristic diagram of gain and phase of a DC amplifier. , Figure 4 shows the output signal of the non-contact displacement sensor as the source signal (eI
), Figure 1 is a conversion characteristic diagram showing the operating state of the circuit, and Figure 5 is a conversion characteristic diagram showing the operating state of the circuit when
, ) when the waveform of the AC component becomes irregular,
Waveform diagrams showing the operating state of the circuit in Figure 1, Figures 6 to 9
The figure is an explanatory diagram of a conventional device, and FIG. 6 is a waveform diagram showing a voltage waveform and an output rectangular wave by a conventional waveform shaping device when measuring surface irregularities of a rotating body facing a non-contact displacement sensor. Figure 7 is an output characteristic diagram of a non-contact displacement sensor showing the relationship between the position of the displacement sensor and the output of the displacement sensor, and Figure 8 is
The temperature characteristic diagram of the output of the non-contact displacement sensor, FIG. 9, is a waveform diagram in an operating situation in which the conventional device causes one mountain of error counting. Figure 1 (1) Analog comparator (comparison amplifier) (2) Operational amplifier (3) (4) Input resistance (5) Feedback resistance (6) Differential DC amplifier (7) Operational amplifier (8) (9
) Input resistance (10) Feedback resistance (11) Integrating capacitor Source signal (e,) Output signal (ek)
Signal (e,) Fig. 2 Fig. 5 Fig. 6 Fig. 8 θ1 θ2 One temperature (e) Fig. 9

Claims (2)

[Claims] (1) In waveform shaping, which generates a rectangular signal that matches the period of the main waveform of an AC signal from a signal in which an AC component is superimposed on a DC component, this Generating a rectangular signal that matches the period of the main waveform of an AC signal by comparing signals with different phases of the main waveforms of the AC components of the source signal, with the levels of the DC components of both signals being almost the same. A waveform shaping method characterized by: (2) A comparator amplifier in which a source signal in which an alternating current component is superimposed on a direct current component is input to one of the comparison input terminals, and the source signal is used as an input signal, and only the phase of the alternating current component of this input signal is different. A waveform shaping device comprising: a DC amplifier that outputs a signal and inputs the output signal to the other comparison input terminal of the comparison circuit.