JPS59138928A - Tuning device - Google Patents

Abstract

PURPOSE:To facilitate tuning by arranging a phase-locked loop circuit whose reference oscillation frequency is set to the reference tone of an instrument or its integral multiple in front of a sample holding circuit. CONSTITUTION:An oscillation tone received by a microphone 1 is passed through an amplifier 2 and a band-pass filter 3 to extract its basic wave or one of higher harmonics, which is supplied to an electronic switch 6 through a rectifying circuit 5. The switch 6 turns on when there is an input tone having a specific amplitude or more. A detection signal, on the other hand, is supplied as an input signal (Wi) to the phase-locked loop circuit 7 and its phase and frequency are compared with those of a voltage-controlled oscillator 74; and the oscillation frequency Wo of the oscillator 74 is adjusted on the basis of an error voltage Ve generated by the phase comparator 71 to enter a locked state when the signal Wi becomes equal to the signal Wo, and the DC component of an output signal of the current oscillation frequency is displayed on an ammeter 10 through an amplifier 8, switch 6, and sample holding circuit 9.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tuner that makes it possible to easily tune a musical instrument in a short period of time.

Currently, there are three methods for tuning musical instruments:

The first method is a method that has been practiced for a long time and is performed by comparing the sound of the instrument with a reference sound source using the ears of a person who has played the instrument. The second method is to convert the sound of an instrument into an electrical signal and draw a resurge on a cathode ray tube using the signal from a reference oscillator. The third method is to change the optical trap of the beat signal that is the difference between the two signals and tune it to zero beat.

This is a method that can only be done by a teacher. Also second. The third method has the disadvantage that it is impossible to tell whether the sound of the instrument is hitting the high end or the low end.Moreover, it is difficult to tell whether the sound of the instrument is hitting the high end or the low end. In cases like the Taishogoto, tuning was difficult.

Therefore, the present invention aims to provide a tuning device that can extremely easily tune even musical instruments such as the Taishogoto, whose sound attenuates rapidly.

That is, the present invention provides a microphone that converts the sound of a musical instrument into an electrical signal, and a filter that extracts one of the fundamental wave or harmonics from the output signal of the microphone.

an electronic switch that is turned on while the output signal of the filter is present; a PI, L circuit that receives the output signal of the filter and whose reference oscillation frequency is set to the reference tone of the musical instrument or a frequency that is an integral multiple thereof; This tuner is characterized by comprising a sample-and-hold circuit that inputs the output of the PLL circuit via the electronic switch, and a display device that displays the output signal of the sample-and-hold circuit.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention, where 1 is a microphone that converts the sound of a musical instrument into an electrical signal. The vibration sound of the musical instrument received by the microphone 1 is converted into an electrical signal, which is then amplified by the amplifier 2.
The fundamental wave or one of the harmonics of the vibration sound is taken out through the entire filter 3.

This detected signal is amplified and then converted into direct current by a rectifier 5 and fed to an electronic switch 6, which then sends it to a microphone.
The electronic switch 6 is turned on during l'-,0.

On the other hand, the above detection signal is a PLL (Phase-Locked) signal.
Loop) t given to the circuit 7.

The PLL circuit 1 of the embodiment includes a phase comparator 71. It consists of a low-pass filter 72, an amplifier T3 for increasing the loop gain, and a voltage controlled oscillator 74, and when the input signal is large, the error voltage Vd becomes equal to O. In this case, the voltage controlled oscillator 74 oscillates at the set frequency (ωO)b, that is, the fundamental frequency.

When the input signal (Wl) is supplied, the phase comparator T1 compares the input frequency with the phase and frequency of the voltage controlled oscillator 74, generates an error voltage Ve proportional to the phase difference and frequency difference, and this Ve It passes through the low-pass filter T2 and the amplifier 73 and becomes the control voltage vd of the voltage controlled oscillator T4, which supplies the oscillation frequency of the voltage controlled oscillator 14 in a direction that reduces the difference from the frequency of the input signal.

Then, the input signal ωi becomes the output signal W from the voltage controlled oscillator γ4. When it becomes equal to , it becomes a locked state, and once it is locked (the phase difference between JJi and ω returns to a certain value or more), the state of ω = ωj continues as long as V′.

When the input signal is changed from the initial lock state (untuned) (when tuned), the input signal enters the capture range of the amplifier 8 and the electronic switch 6. The current is inputted to the Sansol hold circuit 9 through the current i] and displayed on the display device 10 (display device).

Therefore, when used as a tuner for the Taishogoto, for example, the set frequency of the voltage controlled oscillator 74 when the output of the IM flow of the phase comparator 71 is 0 is set to the frequency of the reference tone of the open string (
For example, if you set the frequency corresponding to (784H2),
When tuning, just tighten and strum the 9th string so that the reading on the current meter 10 is 0.

In this case, as shown in the figure, if the ammeter 10 is used for phase comparison when the sound of the inner instrument is higher than the reference sound? By setting the output of the 3T1 to be positive and negative when it is low, you can instantly determine whether to raise or lower the sound of the instrument, so you can quickly complete the tuning.

1. With conventional tuners, it was difficult to judge the rapidly attenuated sound of an instrument because the judgment time was short, but with the present invention,
It has the feature of making the judgment easier due to the following action.

In other words, the sound of the instrument is very loud to microphone 1.
During this time, the electronic switch 6 is turned on and the sample e
Even if the capacitor C of the Hall P circuit 9 is charged with the direct current of the P L L circuit and the electronic switch 6 is turned off when the musical instrument sound disappears, the ammeter 10 will continue to display for a long time until the charge in the capacitor O disappears. Therefore, it is easier to tune the pitch with a constant monthly pitch difference.

At this time, the input sensitivity of the PLL circuit is made sufficiently high so that even if the electronic switch 60 control voltage enters the non-operating region, the PLL circuit
The circuit needs to have a margin to continue synchronous operation.

In the embodiment, the pitch difference is displayed using a meter, but the left, right, and center values may also be displayed using a row of LEDs.

In a stringed instrument that tunes the sound of open strings, the frequency of each open string is an integer multiple, so if you set the frequency of the voltage controlled oscillator 74 to the greatest common divisor, the tuner itself will not make any adjustments. You can do your job without having to do anything.

However, in the case of a tuner that is used to tune something such as a piano whose strings have different lengths, it is preferable to provide the voltage controlled oscillator 74 with a setting frequency changer fif.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the invention. DESCRIPTION OF SYMBOLS 1... Microphone, 2, 4.8 and 73... Amplifier bar, 3... Band-pass filter, 5... Rectifier, 6... Electronic switch, 1... PLL circuit, 11・
...Phase comparator, 72...Low pass filter, 74...
Voltage controlled oscillator, 9...sample/hold circuit, 1
0... Ammeter (light indicator & ) Patent applicant Sofad Co., Ltd.

Claims (1)

[Claims] A microphone that converts the sound of a musical instrument into an electrical signal. A filter that extracts one of the fundamental waves or harmonics from the output signal of the microphone, and the output of the filter! The electronic switch that turns on the switch field and the output signal of the filter are input, and the reference oscillation frequency is set to the reference tone of the instrument or a frequency that is an integral multiple thereof.
A tuning device comprising a cPLL circuit, a sample hole circuit for inputting the output of the PLLM path via the electronic switch, and a display device for displaying the output signal of the sample and hold circuit. .