JPS5838B2 - Denshigatsuki - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronic musical instrument that obtains a musical tone signal by controlling the opening and closing of a sound source signal using pulses of an audible frequency or higher.

In an electronic musical instrument that is equipped with a sound source that oscillates a frequency corresponding to the pitch of each key on the keyboard, and selects a desired frequency signal from the sound source in response to a key press, each sound source frequency signal oscillated by a sound source circuit is used. The gate circuit that selects the frequency signal must be configured with an analog processing type gate circuit that passes through and outputs the analog input frequency signal as it is, so it has been difficult to convert it into a completely digital IC.

This invention was made in view of the problem of mud, and the purpose is to configure the sound source circuit connected to the keyboard circuit so that it can all be processed digitally, and to easily convert it into an IC. .

In order to achieve the above object, the present invention causes a sound source circuit to oscillate and output a square wave signal (hereinafter simply referred to as the sound source signal) with a frequency corresponding to the pitch of the master key, and sequentially outputs a square wave signal (hereinafter referred to simply as the sound source signal) at a high speed (above the audible frequency) in response to the master key. ) pulses are generated, the sound source signal and the sequential pulses are added to AND circuits provided separately corresponding to the master keys, and the signals output from the AND circuits are combined into one signal by an OR circuit and output in a superimposed manner. , the sound source signals corresponding to the keys pressed simultaneously are obtained by the density of the sequential pulses included in the output signal.

The present invention will be described in detail below based on an embodiment of the accompanying drawings.

In the following explanation, a case will be explained in which the keyboard has 5 octaves and 60 keys.

In FIG. 1, a tone source circuit 1 outputs square wave tone source signals TP1 to TP60 of frequencies corresponding to master keys (not shown), respectively, and is always applied to a gate circuit 2.

The gate circuit 2 is an AND circuit A1 to A60 corresponding to the duplicate key.
The sound source signals TP1 to TP60 are applied to one input side of each AND circuit A1 to A60, respectively.

The sequential pulse generator 3 includes a pulse generator 3a that generates a shift pulse φ with an extremely narrow pulse interval, for example, 1 μs, compared to the sound source signal, and a scanning circuit 3b, for example, a shift generator 3b having a number of stages corresponding to a duplicate key (60 stages in this case). It is composed of a register, and the single signal 1 is sequentially transferred to the next stage by the shift pulse φ and circulated, and the pulses (sequential pulses) P1 to P60 corresponding to the match key are each sent separately for a certain period of time (1μ
S) are sequentially generated and output with a delay.

These pulses P1 to P60 are respectively applied to the other input sides of the AND circuits A1 to A60 of the gate circuit 2 via the key switches KS1 to KS60 of the key switch circuit 4 corresponding to the duplicate keys.

The OR circuit 5 is each AND circuit A1 to A60 of the gate circuit 2.
The output signals Q1 to Q60 of are inputted, respectively, and the output signal P0 is applied to the filter circuit 6.

That is, this OR circuit 5 outputs a signal Po obtained by combining signals Q1 to Q60 into one and superimposing them.

The filter circuit 6 is a bypass filter that removes the pulses P1 to P60 contained in the signal P0 and outputs an audible signal E.

Suppose now that only one key is pressed.

For example, the key switch KS1 corresponding to the press of this key
is closed, and the pulse P is output from the first stage of the shift register 3b.
1 is sequentially applied to the AND circuit A1 every 60 μs (FIG. 2b).

This AND circuit A1 has the sound source signal TP1 (a in the same figure).
Therefore, when the key is pressed in the AND circuit A1, the AND condition is established by the sound source signal TP1 and the pulse P1, and the square wave width T1 of the sound source signal TP1 is
The signal (pulse P1) Ql (C in the same figure) is output only during this period.

In this case, the gate circuit 2 is a group of AND circuits, so the AND condition is not satisfied for other keys that are not pressed, and the output of the gate circuit 2 is only the signal Q1, and the OR circuit 5
The output P0 (d in the figure) is the same as the signal Q1.

The filter circuit 6 receives this signal P.

is filtered and a corresponding audible signal E (e in the figure) is output.

This signal E corresponds to the sound source signal TP1.

Next, a case where a plurality of keys, for example two keys, are pressed at the same time will be described.

For example, key switch KS1. KS2
Suppose that each is closed.

From the first stage of the shift register 3b, the pulse P1 is sequentially outputted every 60 μs as described above, and from the second stage, the pulse P2 is sequentially outputted every 60 μs 1 μs after the pulse P1, and these pulses P1゜P2 is an AND circuit A1 corresponding to each weight. It is added to one input side of A2.

On the other hand, on the other input side of these AND circuits A1 and A2, sound source signals TP1. TP2 (3rd
a, b') are added, and both AND circuits A1. A
2, when each weight is pressed, each sound source signal TP1. T.P.
The AND condition is satisfied only during the time period of square wave width T1°T2 of signal Q1. Q2 (c, d in the same figure) is output.

OR circuit 5 is both AND circuit A1. Signal Q1 from A2.
Q2 are combined into one and two signals P0 (see figure e) are outputted and added to the filter circuit 6.

As shown in the figure, in the signal P0, the pulses included in the signal P0 are denser in the portion where the sound source signals TP1 and TP2 overlap, and the pulses included in the signal P0 are coarser in the case of only one of the signals. .

Therefore, the signal P0 is the sound source signal TP1. It comes to include coarse and dense pulses corresponding to the overlap of Tp2.

Therefore, if this signal P0 is filtered by the filter circuit 6, a signal with a level corresponding to the density of the pulses contained, that is, the sound source signal TP1. A signal E (FIG. f) on which TP2 is superimposed can be obtained.

FIG. 4 shows the sound source signal TP1. shown in FIG. 3 above. This is a scaled-down drawing of TP2 and signal E, and shows the sound source signal TP1. T.P.
This is an easy-to-understand illustration of the state of superimposition of the two.

In the above embodiment, the pulse signal containing the superimposed signal was removed through a filter, but the filter circuit is not necessarily necessary, and the musical tone formed by the density of the pulse signal may be directly heard.

Furthermore, although the above description deals with the case where two keys are pressed at the same time, it goes without saying that even when an appropriate number of keys are pressed at the same time, each sound source signal can be similarly superimposed to form a corresponding musical tone. Nor.

In the above embodiment, the key switch circuit 5 is sequentially connected to the pulse generator 3 and the gate circuit 2 (AND circuits A1 to A1).
60), but it goes without saying that the same implementation can also be achieved by providing it between the tone source circuit 1 and the gate circuit 2, or between the gate circuit 2 and the OR circuit 5. .

As explained above, according to the present invention, it is possible to digitally process all the sound source circuit opening/closing circuits connected to the keyboard circuit, and the advantages are that it is small, lightweight, easy to assemble, and can be constructed at low cost. has.

[Brief explanation of drawings]

FIG. 1 is a block diagram schematically showing an embodiment of an electronic musical instrument according to the present invention, FIG. 2 is a graph showing the signals in each part when one key is pressed, with the timing aligned, and FIG. A graph showing signals at each part when a key is pressed with the same timing. FIG. 4 is a graph drawn by reducing the sound source signal and superimposed output signal shown in the graph of FIG. 3. 1...Sound source circuit, 2...Gate circuit, 3...
... Sequential pulse generation section, 4 ... Key switch circuit, 5 ... OR circuit, 6 ... Filter circuit, A
1~A60...AND circuit, KS1~KS60
...Key switch.

Claims (1)

[Claims] 1. A sound source oscillation unit that generates a sound source signal with a frequency corresponding to the pitch of the duplicate key; a sequential pulse generation unit that sequentially generates high-frequency pulses corresponding to the duplicate keys; and a sequential pulse generation unit that is provided for each duplicate key. A sound source signal corresponding to a pressed key is obtained from a plurality of AND circuits, each of which receives a sound source signal and a corresponding sequential pulse as input, and an OR circuit that receives the output of each AND circuit as an input. electronic musical instrument.