JPS6224729B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a tuning device for musical instruments, and in particular, to provide a tuning device suitable for keyboard instruments and the like. As a musical instrument tuning device, for example, a musical instrument tuning device as shown in Patent Publication No. 3592 of 1952 is known. The system shown in the announcement is to swing the horizontal axis of the cathode ray tube oscilloscope in synchronization with the standard scale signal, then shape the tuned tone and apply it to the brightness modulation terminal, and then swing the horizontal axis of the CRT oscilloscope in synchronization with the standard scale signal. I try to add a waveform of an appropriate frequency to the axis. Therefore, if the frequencies of the standard scale signal and the tuned signal match, the brightness-modulated figure on the cathode ray tube becomes stationary, and the image changes to the right or left depending on whether the frequency of the tuned tone is higher or lower than the standard tone. It was made to move to. However, when using the above-mentioned device, it works effectively when the difference between the tuned note and the standard scale is small, but as the difference between the tuned note and the standard scale increases, the frequency of the tuned note increases, and the frequency of the tuned note increases. It has the disadvantage that it is impossible to judge whether it is too high or too low. In order to measure the frequency shift, a difficult method was used in which the standard frequency was shifted so as to stop moving on the cathode ray tube, and then the shift of the standard frequency was used for measurement. The present invention proposes a musical instrument tuning device that eliminates the above-mentioned drawbacks, and allows the frequency deviation to be read directly using an analog display device such as an ammeter or a digital display device, and also allows the reference frequency to be measured using a crystal or the like. An object of the present invention is to provide a musical instrument tuning device which uses the present invention to improve the accuracy of frequency deviation. The details of the present invention will be explained below. Figure 1 is a system diagram of a musical instrument tuning device. 1 is a reference signal generating circuit that has a standard crystal oscillator (XTal), and the frequency of this crystal oscillator can be arbitrarily selected. For example, it is used in a color television receiver. A crystal oscillator for subcarrier frequency (3.579545MHz) is available at low cost, so it can be used. This oscillator output is 1/3
In addition to the frequency dividing circuit 2, the oscillator frequency is reduced to 1/3 and applied to the next step down-down circuit 3. The down-down circuit is a scale
For A ₀ , A ₀ #, and B ₀ , give 1/4 frequency division and make the scale
For up to C ₁ , C ₁ #, D ₁ , D ₁ #, E ₁ , ... A ₁ , A ₁ #, B ₁ , divide the frequency by 1/2, and for other scales up to 88 keys, for example. The signals C ₂ to _{C 8} are outputted to the switch S ₁ - ₁ without being frequency divided, and these are appropriately selected and inputted to one input terminal of the gate circuit 4 . The output of the counter circuit 5 is given to the other input terminal of the gate circuit 4, and the output of the gate circuit 4 is applied to the counter circuit 5. On the other hand, the output terminal of the counter circuit 5 is connected to a first comparison gate circuit 7 through an inverter circuit 6, and further, the output terminal of the counter circuit 5 is directly connected to a second comparison gate circuit 8. The gate circuit output end is connected to a meter 10 through a meter drive circuit 9. On the other hand, reference numeral 11 denotes an input terminal into which a tone to be tuned is input, and the input signal is applied to a tuning amplifier 12, which removes harmonic components that cause malfunctions during tuning. Incidentally, _the frequency tuned by the tuning amplifier is made to match the tuned tone by a scale changeover switch _S2-1 and _an octave changeover switch _S1-2 . The output from the tuned amplifier 12 is applied to a detection circuit 14, and is applied to a down-down circuit 13 in order to facilitate comparison between the period of the tuned tone and a reference time to be described later. In the case of this embodiment, the down-down circuit 13 has pitch names A ₀ , A ₀
#, B ₀ , C ₁ , ... A ₂ #, B ₂ are directly added to the differentiating circuit 15 without descending, and pitch names C ₃ , C ₃ #, ... C ₈ are raised by one octave. Switch _S1 so that one stage of 1/2 frequency divider circuit is added for each stage.
- ₃ selects the number of stages of the 1/2 frequency divider circuit of the down-down circuit 13 and adds it to the differentiating circuit 15. As a result, no matter how many octaves higher than the pitch name C ₂ , ... A ₂ #, B ₂ of the pitch to be tuned, the output of the switch S ₁ - ₃ will change the pitch name C 2 , ...A 2 #, B ₂ according to the pitch to be tuned. C ₂ #,…
...Converted to either A ₂ # or B ₂ frequency. The output of the differentiating circuit 15 is connected to the gate circuits 16 and 17.
added to the 1/2 frequency divider circuit 18, and the 1/2 frequency divider circuit 18
The output is applied to the other input terminal of the gate circuit 16, and also applied to the first comparison gate circuit 7 through the inverter 21, and further applied directly to the input terminal of the second comparison gate circuit 8. On the other hand, the output from the detection circuit 14 is applied to the 1/2 frequency divider circuit 19, the output of which is applied to the other input terminal of the gate circuit 17 through the inverter 20, and the output of the gate circuit is applied to the 1/2 frequency divider circuit 19. is input.
The output of the 1/2 frequency divider circuit 19 is directly input to the input terminals of the first and second comparison gate circuits 7 and 8. Further, the output of the gate circuit 16 is configured to be input to the input terminals of the counter circuit 5 and the second comparison gate 8. The operation of the above configuration will be described in detail below.
In Fig. 1, by applying the tuned tone to the input terminal 11, the tuned amplifier 12 removes harmonic components that cause malfunctions, and the octave change
The tones to be tuned are switched to octaves by _{the switches S1--2 ,} and _the scale changeover switch _S2-1 is used to switch according to the scale of the tones to be tuned. The output from the tuned amplifier 12 is frequency-divided by the down-down circuit 13, and the tones from C ₃ to C ₈ are frequency-divided and converted into one of the frequencies of the note names C ₂ , C ₂ #, . . . A ₂ #, B ₂ . (A ₀ , A ₀ #...excluding B ₁ ),
It is added to the differentiation circuit 15. This waveform is shown as FIG. 2 _X1 . The waveform _X1 is differentiated by the differentiating circuit 15,
Differential pulse shown in Figure 2 X ₂ at the falling edge of waveform X ₁
Generates X ₂ . Differential pulse X ₂ is gate circuit 1
6, 17 and the 1/2 frequency divider circuit 18, and the output of the 1/2 frequency divider circuit generates an output waveform _X3 that repeats inversion every time the differential pulse _X2 is issued, as shown in Fig. 2 _X3. . The gate circuit 16 generates a reset pulse _X4 as shown in FIG. ₂ only when the waveforms _X2 and _X3 are simultaneously at high level. On the other hand, the crystal oscillator (XTal) of the reference signal generation circuit 1 oscillates at 3.579545MHz, and
Octave switching is performed by the 3-frequency divider 2 and the down-down circuit 3, and is applied to the gate circuit 4, and by applying the waveform _X4 to the reset terminal 5a of the counter circuit 5, the waveform Y of the counter circuit 5 shown in FIG. Since the output waveform Y ₃ shown by ₃ becomes high level and is applied to the gate circuit 4, the gate circuit 4 is opened, and the reference pulse Y ₁
(not shown) is input to the counter circuit through the gate circuit 4 as shown in FIG. ₂ Y2. Counter circuit 5
The number of counts n is determined depending on the tone to be tuned. To briefly explain the reason for determining this number n, when counting by inputting the accurate frequency of the crystal oscillator (XTal), the counting start time must match the falling point of the measured waveform _X1 , for example. ,
From this time, a predetermined count number n is sent to the counter circuit.
If the time it takes to count and invert is T (reference time), if n is sufficiently large, it will be n times the waveform period △T of the crystal oscillator, and if △T is accurate, the time T will be n△ If n is sufficiently large between T and (n-1)ΔT and the input waveform period is accurate, the reference time T can be maintained with high precision. The present invention uses this configuration to compare the tuned tone with the reference signal generation circuit 1, but in order to make the number n to be counted mentioned above correspond to each note with note names _C2 to _B2 . The following is how to determine the kontone name m.
If the fundamental frequency of is m, then the time T (reference time) from when the counter 5 starts counting until it is inverted can be set to T=1/m, and the period of the reference signal waveform from the crystal oscillator is Assuming △T, △T・(n-1)≦T≦△T・n……(1) △T・(n−0.5)−0.5△T ≦T≦△T(n−0.5)+0. 5△T ……(2) T≒(n-0.5)△T±0.5△T ……(3) So if an error of ±0.5△T is expected, n≒0.5+T/△T ……(4) Here, if the frequency of the crystal oscillator is set to 1/3 of 3.579545MHz, n=0.5+3.579545×10 ⁶ /3m...(5). Here, if we calculate the count number n for each of the frequencies up to pitch name C ₂ . . . B ₂ , we get the following table.

【table】

[Table] Since the number n to be counted is determined by the scale selection switch _S2-2 of the counter circuit ₅ , the waveform added from the gate circuit 4 is
The number of pulses _Y2 is counted, and at the same time when the number becomes equal to the predetermined count number n, the output waveform _Y3 of the counter circuit 5 is inverted and the gate circuit 4 is closed, as shown in FIG. 2 _Y3 . It becomes a positive pulse that rises at the same time as the leading edge of the reset pulse _X4 , starts counting from the trailing edge, and immediately falls after the elapse of a reference time T determined corresponding to the tuned tone. On the other hand, the aforementioned pulse waveform _X3 falls at the same time as the trailing edge of the pulse waveform _X2 of the differentiating circuit 15, and becomes a negative pulse exactly matching the period of the tuned sound waveform _X1 . Therefore, _the waveform Y ₃ is applied to the first and second comparison gate circuits 7 and 8 in order to extract the difference between the trailing edge X' ₃ of the waveform X ₃ and the trailing edge Y' ₃ of the waveform Y 3 . On the other hand, FIG. 3 taken out from the tuned amplifier 12
The attenuated waveform as shown by X ₀ passes through the detection circuit 14 and becomes a detection output as shown in FIG. The 1/2 frequency divider circuit 19
A differential pulse X ₂ is applied to the clock terminal of the JK flip-flop from the gate circuit 17 (see Fig. ₃₎ .
), the output of the 1/2 frequency divider circuit 19 is inverted at the end of the first differential pulse _X2 that is applied while the clear terminal 19a is at a high level due to the detection output Z. Then, the signal becomes high level as shown by waveform W in FIG. It reached this high level
The output waveform of the 1/2 frequency divider circuit 19 is inverted by the inverter 20 and becomes a low level, and the output waveform is output to the gate circuit 17.
Since the differential pulse _X2 is subsequently blocked, the output waveform W remains at a high level. On the other hand, the level of the detected output waveform Z applied to the clear terminal 19a decreases as it gradually attenuates.
Therefore, the output W is configured so that it is inverted again and becomes a low level before the tuned sound wave disappears at a predetermined threshold. The output waveform W is input to the first and second comparison gate circuits 7 and 8 so that they operate only while the output waveform W is at a high level. Therefore, it is possible to prevent malfunctions such as chattering due to the impact of the hammer at the rising edge of the tuned sound and chattering just before the tuned sound decays and disappears. Also, if the tuned sound decays rapidly, the next waveform will not be input after the last waveform is measured, but in this case, it is determined that the tuned waveform has a very long period. However, such malfunctions can be minimized. The first comparison gate circuit 7 operates so that the output becomes a low level when the waveform W is at a high level and the waveforms X ₃ and Y ₃ are at a low level.
Since the comparison gate circuit 8 outputs a low level when the waveforms W, X ₃ and Y ₃ are all high level, the trailing edge X' ₃ of the waveform X ₃ is ahead of the trailing edge Y' ₃ of the waveform Y ₃ . If the trailing edge X 3 ' of waveform X ₃ occurs after the trailing edge Y ₃ ' of waveform Y ₃ , _the output terminal of the second comparison gate circuit 8 At the output end of the circuit 7, a pulse V such as waveform V in FIG. 2 is generated having a width equal to the time difference between the trailing edges X ₃ ' and Y ₃ ' of both waveforms. Also, the output waveform of the gate circuit ₁₆
By adding the above to the second comparison gate circuit 8, it is possible to prevent the generation of unnecessary pulses as shown by dotted lines in the comparison gate circuit output V. In this way, the error output between the reference time T determined by the reference oscillator and the tuned tone, taken out to the outputs of the first and second comparison gate circuits, is output by the meter drive circuit 9.
If a double swing type ammeter is used as the frequency index indicating meter 10, the error output pulse of the second comparison gate 8 is converted into DC, and when a negative pulse occurs, the meter is switched to the positive side according to the value. If the error output pulse of the first comparison gate 7 is similarly converted into DC and the meter is swung to the negative side according to the value, the scale to be tuned can be directly read with the meter. As described above, according to the present invention, it is possible to tune a piano or the like extremely easily, and the error can be displayed on a meter.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of the tuning device of the present invention, and FIGS. 2 and 3 are waveform explanatory diagrams of FIG. 1. 1 is a reference signal generation circuit, 2 is a 1/2 frequency divider circuit,
3 and 13 are step-down circuits, 4, 16, 17, 7 and 8 are gate circuits, 5 is a counter circuit, 9 is a meter drive circuit, 10 is a meter, 12 is a tuned amplifier, 14 is a detection circuit, 18 and 19 are 1/2 frequency divider, 20,2
1 and 6 are inverter circuits, and 15 is a differential circuit.

Claims (1)

[Claims] 1. Means for repeatedly generating a reference time pulse that is generated at each starting time of each of a series of tuned sound waveforms and that ends after continuing for a predetermined reference time; and means for repeatedly generating, for each of the tuned sound waveforms, a comparison pulse having a width that matches the difference between the end time and the end time of each of the tuned sound waveforms;
and a means for driving a meter circuit by the output of the comparison pulse to display the meter, and for the series of to-be-tuned sound waveforms immediately after generation and immediately before extinction, the comparison pulse is generated. A musical instrument tuning device having means for blocking.