JPS6132353Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a device for detecting displacement of a viscoelasticity measuring instrument and the phase of stress caused by the displacement.

To measure dynamic viscoelasticity, it was customary to fix one end of the sample, apply displacement vibration to the other end, and measure the viscoelasticity by detecting the magnitude of the stress vibration generated at the fixed end and the phase with respect to the displacement vibration. . Up until now, the phase has been measured by using a synchronous phase detector to measure the resulting stress using the cause of the displacement as a reference, but the amplitude of stress waves varies greatly depending on the material, making it difficult to detect the amplitude. Furthermore, the phase can be detected easily and accurately when the amplitudes of the two waves whose phases are to be compared are approximately equal, and this principle has even been used in direct reading types. However, as a basis for measuring displacement vibrations, it is common to add a nearly constant amplitude, and to obtain the complex viscoelasticity from the amplitude and phase of the stress wave generated by this constant amplitude. It is difficult to detect the phase in a rectifier with a small phase difference and poor rise characteristics, so the magnitude is determined by an amplification factor that makes the stress the same amplitude as the displacement, as in Utility Model Publication No. 41-11515, and the phase difference between two waves of the same amplitude is simply a pull. However, these methods require time and effort to first set the amplitude of the stress wave to a predetermined value in order to determine the phase, making the equipment complex and expensive. Ta. In other words, in order to find the phase difference between two waves, the characteristics of the phase are more important than the amplitude. For example, if the 0 passing point, that is, the position of the zero cross, is clear, phase detection becomes easy regardless of the amplitude, and the zero cross has become easier and more accurate with the recent advances in operational amplifiers, so in order to eliminate the drawbacks of the above-mentioned device, the present invention calculates the phase of stress vibration using the displacement vibration as a reference. This device has been improved so that the phase of displacement can be determined using this as a reference.This device makes it possible to adjust the amplification degree of the amplitude of the highly fluctuating stress wave to bring it closer to the phase of the displacement wave. This makes it possible to simplify and make the device more accurate.

Preferred embodiments will be described below with reference to the drawings.

Figure 1 10 shows the simplest zero-cross detection circuit, in which a circularly connected rectifier circuit 14 is added to a comparator circuit using an ordinary operational amplifier 12 to increase the detectability of the comparison and apply a pulse wave of a predetermined amplitude of a minute AC voltage in the same phase. The zero-crossing point is clarified by converting the pulse wave into The current polarity between the neutral points 0'0'' of the circuit connecting the two diagonal connection points AC and BD is reversed depending on the relative polarity of the voltage applied to the diagonal connection points AC and BD. Then add the reference wave and the phase-measured wave separately to the diagonal coupling points AC and BD, and discriminate the phase of both waves)1
6 as a reference wave, and the phase difference between it and the displacement vibration 18 is displayed on the indicator 20. Therefore, the displacement vibration 18 generated by the vibrator 24 of the viscoelasticity measuring instrument 22 is applied to one end of the sample 26 and the stress generated at the other end is detected by the stress detector 30, and is applied to the amplifier 12 constituting the zero cross detector 10. A pulse whose width is the zero cross that occurs at
In addition to BD, the phase of displacement waves and stress waves is detected to determine dynamic viscoelasticity. In the conventional viscoelasticity measuring instrument, when a constant value of the possible vibrational displacement 18 that is the cause is applied to the sample 26, the magnitude and phase of the resulting stress waves 32 differ significantly depending on the sample 26. When the phase difference is small, the magnitude is determined by the amplification factor that makes the stress the same amplitude as the displacement, as in the above-mentioned Utility Model Publication No. 41-11515, and the phase difference between two waves of the same amplitude is detected by simply subtracting the two, and the result is 1/ The most sensitive method is to take advantage of the fact that it can be found by twice the square angle of the squared value. For this reason, in conventional methods, the stress, which is the result of fluctuations in a wide range caused by the amplitude of vibration displacement, which is the cause of a constant amplitude, is adjusted to a predetermined amplitude by adjusting an amplifier, and then the phase is determined using the displacement vibration as a reference. It has always been necessary to include a delicate circuit such as an AGC automatic gain adjuster in the stress detection circuit.
On the other hand, in recent electronic circuits, comparison circuits are often used in digital or pulse circuits, and diode rectifiers have also developed significantly, and when these are combined, it is extremely difficult to detect the zero-crossing point that corresponds to polarity reversal. It is easy and has become so easy that it can be said that the amplitude of the measured wave is irrelevant, so there is no need to strictly adjust the amplitude to find the phase as described above, which saves time, effort, and measurement costs. It became possible to do so. In other words, the results of the present invention were achieved only by breaking away from the fixed ideas held by conventional practices. In the above, the stress wave is a zero-crossing rectangular wave and the phase difference with the displacement wave is determined, but it is also possible to use the displacement wave as a zero-crossing rectangular wave and determining the phase difference of the stress wave.

[Brief explanation of the drawing]

The attached figure is an example of a circuit diagram close to a block diagram for implementing the present invention. In the figure, 10... zero cross detection circuit, 12...
Operational amplifier comparator, 14... Annular rectifier bridge, 1
6...Synchronized phase detector, 18...Displacement vibration, 20
... Phase indicator, 22 ... Viscoelasticity measuring device, 24 ...
...exciter, 26...sample, 30...stress detector,
32... Stress wave.

Claims (1)

[Scope of utility model registration request] In equipment that measures viscoelasticity by fixing one end of the sample and applying displacement vibration to the other end, the magnitude of the stress vibration generated at the fixed end and the phase with respect to the displacement vibration are detected. A viscoelastic phase detection device that includes a detection circuit and a synchronous phase detector in the displacement vibration detection circuit, uses the rectangular wave of the zero-cross detection circuit as a reference, detects the other phase difference, and calculates the phase difference between displacement and stress. .