JPS58182517A - Amplitude detector of oscillating body - Google Patents

Abstract

PURPOSE:To detect most securely the oscillation amplitude in the oscillation part of a body to be detected by utilizing the dependency of the intensity of a radio wave on distance. CONSTITUTION:A receiving antenna 2 is provided in the proper place in the oscillation part 1 of a body to be detected. A sine wave of a specified frequency and a specified output is supplied from an oscillator 4 to a transmission antenna 3, and a radio wave is radiated toward the antenna 2. The radio wave is received in the antenna 2; the antenna 2 is under oscillation together with the oscillation of the part 1. Since the distance R between the antenna 3 and the antenna 2 is changed by the oscillation, the intensity of the received radio wave changes in inverse proportion with the square of a distance R. The reception signal modulated in such a way is amplified with a high frequency amplifier 6 and is detected with an amplitude detection circuit 7, then the signal indicating the oscillation amplitude of the part 1 is outputted and the signal thereof is projected on a synchroscope 8. The oscillation amplitude in the oscillation part is known from the difference in height between the crest and trough of the envelope thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an amplitude detection device for a vibrating body that detects the vibration amplitude of a vibrating part of a detected object having a vibrating part.

Conventionally, there are various types of means for detecting the vibration amplitude of a vibrating part of a detected object having a vibrating part.

These methods have advantages and disadvantages, and a method suitable for each test subject is of course adopted.

For example, in speakers used in audio products,
By detecting the vibration of the speaker cone and applying feedback to the input of the speaker drive amplifier to incorporate the speaker drive system and vibration system into the feedback loop, various nonlinear distortions and frequencies near or below bass resonance can be detected. Technical means have been developed to try to improve the properties.

However, even with this method, the detection ability of the vibration system's amplitude detection elements such as detection coils, capacitors, piezoelectric elements, etc. is low, and for example, no output can be obtained when the vibration differential value is zero, and when the vibration amplitude is large. However, it is difficult to accurately detect the vibrations, etc.), the wiring between the speaker and the amplifier becomes complicated, and a special dedicated amplifier is required. The current situation is that it has not yet been seen.

The present invention was devised in view of these circumstances, and its purpose is to provide an amplitude detection device for a vibrating body that has high detection ability and whose detection system can be configured with a relatively simple circuit system. be.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows an embodiment of the invention. Reference numeral 1 denotes a vibrating section of the object to be detected, and a receiving antenna 2 is provided at a suitable location on this section.

A transmitting antenna 3 is fixedly installed in close proximity to the receiving antenna 2, and a transmitting circuit such as an oscillator 4 is connected to the antenna 31, while a receiving circuit 5 is connected to the receiving antenna 2. The receiving circuit 5 includes, for example, a high frequency amplifier 6 and a detection circuit 7. A synchroscope 8, which is one way of using the output of the receiving circuit 5, is connected to the detection circuit 7.

The operation of such an apparatus of the present invention will be explained. A sine wave signal with a constant frequency and a constant output is supplied from the oscillator 4 to the transmitting antenna 3. As a result, radio waves are radiated from the transmitting antenna 3 toward the receiving antenna 2.

The radio waves are received by the receiving antenna 3, and the antenna 3 vibrates together with the vibration of the vibrating section 1. Therefore,
Since the distance R between the transmitting antenna 3 and the receiving antenna 2 changes, the intensity of the received radio wave changes in inverse proportion to the square of the distance R.

The received signal modulated in this way is sent to the high frequency amplifier 6.
A signal representing the vibration amplitude of the vibrating section 1 is output from the amplitude detection circuit 7, and the signal is displayed on the synchroscope 8 (see the envelope in FIG. 2). The vibration amplitude of the vibrating part can be determined from the height difference between the peaks and valleys of the envelope line.

Since the device of the present invention utilizes the distance dependence of radio field intensity, it can significantly improve its detection ability and greatly simplify its detection circuit system.

Next, an example in which the above-described invention is incorporated into a speaker system will be described.

FIG. 3 completely includes the main parts of FIG. 11 is the voice coil of the speaker 10, which is connected to the output of the amplifier 12. The input of the amplifier 12 is connected via a subtracter 13 to a regenerator 14 for records, tapes, etc.

Reference numeral 15 denotes a correction circuit for correcting the detection output signal of the amplitude detection circuit 7, which is proportional to the square of the distance R, by a signal l proportional to the distance R.

The output of the correction circuit 15 is connected to one input of a comparison circuit 16, and the output of the amplifier 12 is connected to the other input.

The output of comparator circuit 16 is connected to the input of amplifier 170, and the output of amplifier 17 is connected to the subtraction input of subtracter 13.

In this loudspeaker system, the cone vibration amplitude signal is fed through a correction circuit 15 to one input of a comparator circuit 16, where it is compared with the signal from an amplifier 12, and the signal resulting from the comparison is passed through an amplifier 17. The signal is supplied to the subtraction input of the subtracter 13 and is used for foot check control.

The vibration amplitude signal of the cone 1 of the speaker lO used for this feedback control has a high detection ability (
Even when the cone 1 is at rest, regardless of the magnitude of the vibration amplitude of the cone 1, the vibration amplitude can be detected with high sensitivity)
If this signal is used in the feedback control described above, since it can be detected without distortion and thus obtained without distortion.

It is possible to significantly eliminate distortion caused by the amplifier 12 and the speaker 10 in the signal output from the regenerator 14, and the fidelity of the sound generated from the speaker 10 is also greatly improved.

In the example of the device shown in FIG. 3, a case has been described in which the transmitting antenna 3 is installed in front of the receiving antenna 2.
By appropriately changing the mounting position of the receiving antenna 2, changes such as mounting the transmitting antenna 3 on the frame of a speaker (not shown) can be easily implemented.

The intention of the present invention described above is not limited to the above-mentioned examples, but is equally applicable to various other types of objects to be detected having vibrating parts.

In summary, according to the present invention, it is possible not only to detect the vibration amplitude of a vibrating part of a detected object having a vibrating part with high detection ability, but also to simplify the detection circuit system. It will be done.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the present invention, FIG. 2 is a waveform diagram used to explain the embodiment in FIG. 1, and FIG. 3 is a diagram showing a configuration when the present invention is applied to a speaker system. . In FIG. 1, 1 is a vibrating part of the object to be detected, 2 is a receiving antenna, 3 is a transmitting antenna, and 4 is a transmitting circuit. 5 is a receiving circuit. Patent applicant Tetsuya Imamura

Claims (1)

[Claims] 1) A receiving antenna is attached to the vibrating part of a detected object having a vibrating part, a transmitting antenna is fixedly installed so as to face and approach the receiving antenna, and a transmitting circuit is connected to the transmitting antenna. . An amplitude detection device for a vibrating body, characterized in that it is configured by connecting a receiving circuit to the receiving antenna. 2) The object to be detected is a speaker, the receiving antenna is attached to the front of the cone of the speaker, and a signal is transmitted in front of the receiving antenna. The amplitude detection device for a vibrating body according to claim 1, characterized in that the antenna is fixedly installed.