JP2002148139A - Instrument and method for measuring natural frequency of tape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measuring instrument and a measuring method for individually finding a natural frequency and an attenuation coefficient only in a tape stuck to a television frame. SOLUTION: This natural frequency measuring for the tape is provided with a mounting means for mounting a member having the tape as a measurement object, an air pulse injection means arranged above the mounting means and adjustably positioned for jetting an air pulse to a predetermined position in the tape, and a vertically movable non-contact displacement gauge arranged above the mounting means for detecting vibration of the measurement object by the air pulse injection means. In this measuring method, an air pulse is applied to the thin tape stuck with a fixed tension for displacing it, a residual vibration in recovery from the displacement is continuously measured, and Fourier transformation of an obtained result of displacement amplitude-time characteristic is carried out for finding the natural frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CRT type display used in a television or a computer, which is generally formed into a fine slit-like metal which is stretched and welded to an iron frame with a constant tension. The present invention relates to an apparatus and a method for measuring the natural frequency of a thin tape made of steel.

[0002]

2. Description of the Related Art Generally, a metal tape used in a CRT of a television or a computer resonates with a vibration including a sound pressure generated from a speaker or a certain specific frequency from the outside. In order to suppress the vibration and prevent the image from being disturbed, the natural frequency and the damping (vibration damping) characteristics are emphasized in the design.

[0003] Regarding the evaluation in a state assembled in a CRT, "SID99DIGEST 62-69" and "Japan Society of Mechanical Engineers (No. 99-
7） Dynamics and Design Conference '99 Lecture Papers ”and“ The 8th Design Engineering and System Division Lecture Papers of the Japan Society of Mechanical Engineers (No98-32) ”(98-11 9-11) The measurement method is explained, but there is no description describing the measurement using the tape alone.

[0004] On the other hand, in the production of a tape, the natural frequency of the tape itself is measured in advance before being formed on a CRT,
It is important to evaluate whether the value satisfies the required characteristics of CRT and to design the shape and material of the tape.

[0005]

In the above-mentioned paper, a method of vibrating the entire assembled CRT while changing the frequency of the vibrator and measuring the frequency of the resonating tape is described. For unique measurement, vibrate only the tape without vibrating the iron frame or CRT body,
It is desirable to perform the measurement without being affected by the components.

[0006] In addition, if the tape alone is evaluated using a dedicated jig as shown in FIG. 1, the resonance frequency due to various tensions applied to the tape can be measured.
The characteristics when formed on the CRT can be estimated.

[0007] In the present invention, the room temperature characteristics by measuring the natural frequency and attenuation of the tape at various tensions using a special jig (measurement results are not displayed), and the room temperature when the tape is welded to the frame. (The measurement result at room temperature is not displayed) and thermal characteristic evaluation by measuring natural frequency and attenuation after heat treatment, and natural frequency measuring device to contribute to product design to manufacture tape necessary for CRT formation and The purpose is to provide a measurement method.

[0008]

In order to achieve the above-mentioned object, the present invention provides a placing means for placing a member provided with a tape of an object to be measured, and a placing means disposed above the placing means. An air pulse ejecting unit that is adjusted to eject an air pulse to a predetermined position on the tape; and an air pulse ejecting unit that is disposed above the mounting unit so as to detect a vibration of the object to be measured by the air pulse ejecting unit. A non-contact type displacement meter that can move up and down,
And a tape natural frequency measuring device characterized by having the following.

The present invention is also obtained by displacing a thin tape with a constant tension by applying an air pulse to a thin tape, and continuously measuring residual vibration when the displacement returns. The method employs a natural frequency measuring method, which is characterized in that the result of the amplitude-time characteristic of the displacement is Fourier-transformed to obtain a natural frequency.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a preferred embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a plan view showing a dedicated jig for setting a tape, and FIG. 2 is a side view showing a tape assembly (tape welded to an iron frame) mounted on an XY stage and a main part of a measuring device therefor. FIG. 3 is a graph showing the result of measuring the tape assembly after the heat treatment with the measuring device of FIG. 2, and FIG. 4 is a frequency analysis of the measurement result of FIG. It is a graph showing a number. Table 1 shows 0.2 to 0.4 in Fig. 3.
It shows the data obtained from the envelope of the measurement results in seconds.

Referring to FIG. 1, a dedicated jig 10 is shown. In the special jig 10, one end of a tape 7 is fixed to a fixed base 6 for fixing a tape attached to a tension jig base 8 by a tape pressing plate 5. The other end of the tape 7 is attached to a movable tape fixing base 3 by a tape pressing plate 4, and the fixing movable base 3 is provided with a load cell 2 for measuring a tensile force. When the tension applying nut 1 is rotated, a tension is applied to the tape 7 through the tension measuring load cell 2, and the tension is measured by the load cell.

When a specific jig is mounted and the natural frequency is measured while replacing the tape assembly shown in FIG. 2 with a constant tension applied, a waveform as shown in FIG. Fourier analysis is obtained for each tension.
Is obtained.

Assuming that the tension is T, the length of the tape is L, and the linear density (mass per unit length) of the tape material is ρ, the natural frequency is
f is represented by the following equation (1). f = (T / ρ) ^1/2 / 2L (1)

In producing the tape, it is necessary to design the material of the tape in relation to L, T, and ρ in the equation (1) in order to obtain the natural frequency f required for the product. By attaching the manufactured tape to the tensioning jig of FIG. 1 and measuring and verifying the tension and the natural frequency, it is possible to feed back to the design.

The details of the measurement method will be described with reference to FIG. In FIG.
A measuring device 20 is shown. In the measuring device 20, the tape 7 welded by applying a constant tension to the tape assembly 17 mounted on the XY stage 18 for which details are not displayed is spaced apart from the non-contact displacement meter 13 mounted on the mounting base 15. facing each other across b.

[0016] In this measuring apparatus, the non-contact displacement meter 13 has a response frequency of 5
The measurement is performed using a laser displacement meter of 0 KHz, and the laser light irradiates the point a on the tape 7. The compressed air injected from the air pulse nozzle 14 attached to the attachment base 15 is adjusted so as to fall on the extension of the point a. The mounting base 15 is attached to a linear moving stage 12, and the linear stage 12 is moved up and down by a vertical moving pulse motor 11.

In the measuring method of the present measuring apparatus, first, the mounting base is moved upward by the vertically moving pulse motor 11,
After the interval b is separated to a sufficient interval that does not hinder the movement of the XY stage 18, the XY stage 18 is adjusted to the desired measurement point a.

When the measuring point a is reached, the vertically moving pulse motor 11 is driven downward to lower the non-contact displacement meter 13 to the measurable range b.

Next, an electromagnetic valve (not shown) is instantaneously opened and closed to generate an air pulse, and the air pulse is ejected from the air pulse nozzle 14 to the tape 7. The vibration of the tape 7 remaining after the injection is measured by the non-contact displacement meter 13 to obtain the measured waveform in FIG.

FIG. 3 is a waveform obtained by measuring one point of the tape after the heat treatment of the tape assembly. The first peak (a) of the waveform represents a state in which the tape has been deformed by the air pulse, and the residual vibration after the peak represents a vibration inherent to the tape.

FIG. 4 shows a result of Fourier transform of the waveform of FIG.
The measured natural frequency of the tape in the tape assembly is 18
It turns out that it is 7Hz.

[0022] Table 1 the envelope of 0 · 2 seconds to 0 · 4 sec vibration waveform between F (t) = Ae-α approximated damping factor ^t alpha = 5.11 in FIG. 3
This shows an example of obtaining the above. The reason for selecting an appropriate time interval of 0.2 to 0.4 seconds is that near the peak (a) of the waveform, the influence of the displacement due to the air pulse is large, and the vibration after a long time has a small amplitude, so external factors and This is because there is a concern that a lot of influences of noise are received. By correlating the damping coefficient α thus obtained with the damping state in the state formed on the CRT and further measuring the natural frequency, the CRT
The tape can be evaluated in advance at the tape manufacturing stage before the tape is formed.

[0023]

As described above, according to the present invention,
For example, a measuring device and a measuring method capable of independently obtaining the natural frequency and the damping coefficient of only the tape applied to the television frame can be obtained.

[Table 1]

[Brief description of the drawings]

FIG. 1 is a plan view showing a dedicated jig for attaching a tape.

FIG. 2 is a side view showing a tape assembly (tape welded to an iron frame) mounted on an XY stage and a main part of a measuring device therefor.

FIG. 3 is a graph showing a result of measuring the tape assembly after the heat treatment by the measuring device of FIG. 2;

FIG. 4 is a graph showing a natural frequency obtained by performing frequency analysis on the measurement result of FIG. 3 by Fourier transform.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Dedicated jig 1 Nut for applying tensile force 2 Load cell for measuring tensile force 3 Movable base for fixing 4 Tape holding plate 5 Tape holding plate 6 Fixed base for fixing tape 7 Tape 8 Tension jig base 20 Measuring device 11 Vertical movement pulse motor 12 Linear stage 13 Non-contact displacement meter 14 Air pulse nozzle 15 Mounting base 17 Tape assembly 18 XY stage

Claims (5)

[Claims] 1. A mounting means for mounting a member provided with a tape of an object to be measured, said positioning means being disposed above said mounting means, and being adjusted so as to jet an air pulse to a predetermined position of said tape. It has an air pulse injection means, and a non-contact type displacement meter which can be moved up and down and arranged above the mounting means so as to detect vibration of the object to be measured by the air pulse injection means. Natural tape frequency measuring device. 2. The measuring apparatus according to claim 1, wherein said non-contact type displacement meter has a frequency response higher than a natural vibration frequency of the object to be measured. 3. The measuring device according to claim 1, wherein said non-contact type displacement meter and said air pulse jetting means are supported by the same vertically movable supporting means, and said placing means is XY. A measuring device characterized by being a stage. An air pulse is applied to a thin tape stretched with a constant tension to displace the tape, and the remaining vibration when the displacement returns is continuously measured, and the amplitude of the obtained displacement is obtained. A natural frequency measuring method characterized by obtaining a natural frequency by performing a Fourier transform on a result of a time characteristic. 5. An air pulse is applied to a thin tape stretched with a constant tension to displace the tape, and the remaining vibration when the displacement returns is continuously measured, and the amplitude of the obtained displacement is obtained. obtains an envelope of a predetermined range of the result of the time characteristic, the envelope is approximated by the equation F (t) = Ae-α t ( where, a is a coefficient, alpha is an attenuation coefficient), A measuring method characterized by calculating an attenuation coefficient α.