1. Field of the Invention
The present invention relates to an electronic stringed instrument such as an electronic guitar, a guitar synthesizer, and the like and, more particularly, to a tone generation start control technique and a pitch control technique upon plucking of a string
2. Description of the Related Art
In a conventional acoustic guitar or the like, a plurality of frets are provided at a plurality of positions of a body portion called a neck below an extension direction of the strings. A string is depressed against the body portion at any position between these frets, so that an effective string length of the string can be changed in accordance with the depressed position. In an electrical musical instrument called an electric guitar, a string is plucked while changing an effective string length of a string by the fret operation, a string vibration caused by the plucking operation is picked up by an electromagnetic pickup or the like and is amplified by an amplifier, thereby producing a guitar sound.
In recent years, an electronic stringed instrument in which a musical tone generator constituted by an analog or digital circuit and the like is controlled by the fret operation and the plucking operation with respect to the guitar to synthesize and produce a musical tone, has been developed.
As a first prior art of the electronic stringed instrument, mechanical or electrical fret switches or detection elements are embedded inside a neck. A fret switch or detection element at a specific position by the fret operation is operated, and a fret number is then detected and output. A start point of a string plucking operation is detected by another sensor, so that a musical tone generator is caused to generate a musical tone having a pitch corresponding to the fret number.
More specifically, the following articles are known:
(a) U.S. Pat. No. 4,235,141 (issued on Nov. 25, 1980), inventor: Eventoff
(b) U.S. Pat. No. 4,336,734 (issued on Jun. 29, 1982), inventor: Polson
(c) U.S. Pat. No. 4,468,997 (issued on Sep. 4, 1984), inventor: Young, Jr
(d) U.S. Pat. No. 4,570,521 (issued on Feb. 18, 1986), inventor: Fox
(e) U.S. Pat. No 4,658,690 (issued on Apr. 21, 1987), inventor: Aitken et al.
(f) U.S. Pat. No. 4,760,767 (issued on Aug. 2, 1988), inventor: Tsurubuchi
(g) Japanese Utility Model Disclosure (Kokai) No. 58-175596 (disclosed on Nov. 24, 1983), applicant: Kashio Keisanki Kabushiki Kaisha
(h) Japanese Patent Disclosure (Kokai) No. 62-174795 (disclosed on July 31, 1987), applicant: Nippon Gakki Seizo Kabushiki Kaisya
(i) Japanese Patent Disclosure (Kokai) No. 63-2095 (disclosed on Jan. 7, 1988), applicant: De Dianous
(j) W087-00330 (published on Jan. 15, 1987), applicant: Stepp Electronics Limited
There are the following U.S. patent applications assigned to the present assignee in association with this technique:
(i) U.S. Ser. No. 069,612 (filed on July, 1, 1987), inventor: Kashio et al.
(ii) U.S. Ser. No. 094,402 (filed on Sep. 8, 1987), inventor: Murata et al.
(iii) U.S. Ser. No. 171,883 (filed on Mar. 21, 1988), inventor: Matsumoto et al.
In a second prior art, each fret is formed by an electric conductive member, and each string is formed by an electric conductive member having an electrical resistance. A current is rendered to flow through the string, so that an effective length of a string from a support portion of the string on the plucking side to a fret contacting the string upon depressing the string is detected as a voltage corresponding to the resistance of the string, thereby detecting a depressed fret position and performing pitch control of a musical tone.
More specifically, the following articles are known:
(k) U.S. Pat. No. 4,677,419 (issued on Jun. 30, 1987), inventor: Meno
(l) Japanese Patent Disclosure (Kokai) No. 53-32708 (disclosed on Mar. 28, 1978), applicant: Kabushiki Kaisya Kawai Gakki Seisakusyo
In a third prior art, an ultrasonic wave is transmitted from a portion near a support portion of each string at a plucking side to the string, and a time period until the ultrasonic wave is reflected by a fret contacting the string upon depressing the string and is returned is detected, thereby detecting a depressed fret position and performing pitch control of a musical tone.
More specifically, the following articles are known:
(m) U.S. Pat. No. 4,723,468 (issued on Feb. 9, 1988), inventor: Takabayashi et al.
In a fourth prior art, a string vibration itself is detected by an electromagnetic pickup or the like, and a pitch period is extracted from the string vibration waveform in real time so that a musical tone is generated to have a pitch corresponding to the pitch period, unlike in the first to third prior arts.
More specifically, the following articles are known:
(n) U.S. Pat. No. 4,117,757 (issued on Oct. 3, 1978), inventor: Akamatsu
(o) U.S. Pat. No. 4,606,255 (issued on Aug. 19, 1986), inventor: Hayashi et al.
(p) U.S. Pat. No. 4,633,748 (issued on Jan. 6, 1987), inventor: Takashima et al.
(q) U.S. Pat. No. 4,688,464 (issued on Aug. 25, 1987), inventor: Gibson et al.
(r) Japanese Patent Disclosure (Kokai) No. 55-87196 (disclosed on July 1, 1980), applicant: Nippon Gakki Seizo Kabushiki Kaisya
(s) Japanese Patent Disclosure (Kokai) No. 55-159495 (disclosed on Dec. 11, 1980), applicant: Nippon Gakki Seizo Kabushiki Kaisya
(t) Japanese Utility Model Disclosure (Kokai) No. 55-162132 (disclosed on Nov. 20, 1980), applicant: Keio Giken Kougyo Kabushiki Kaisya
(u) Japanese Patent Disclosure (Kokai) No. 61-26090 (disclosed on Feb. 5, 1986), applicant: Seikou Denshi Kougyo Kabushiki Kaisya
(v) Japanese Patent Disclosure (Kokai) No. 62-163099 (disclosed on July 18, 1987), applicant: Fuji Gen Gakki Seizo Kabushiki Kaisya
There are the following U.S. patent applications assigned to the present assignee in association with this technique:
(iv) U.S. Ser. No. 112,780 (filed on Oct. 22, 1987), inventor: Uchiyama et al.
(v) U.S. Ser. No. 184,099 (filed on Apr. 20, 1988), inventor: Iba et al.
(vi) U.S. Ser. No. 256,398 (filed on Oct. 7, 1988), inventor: Iba et al.
(vii) U.S. Ser. No. 252,914 (filed on Oct. 3, 1988), inventor: Uchiyama
(viii) U.S. Ser. No. 256,400 (filed on Oct. 11, 1988), inventor: Matsumoto
(ix) U.S. Ser. No. 282,510 (filed on Dec. 9, 1988), inventor: Obata
(x) U.S. Ser. No. 290,981 (filed on Dec. 28, 1988), invention: Murata et al.
(xi) U.S. Ser. No. 329,418 (filed on Mar. 27, 1989), inventor: Obata
In the above-mentioned prior arts, the following problems are left unsolved.
In the first to third prior arts, the fret position can be detected simultaneously with the fret operation. Since the fret operation is generally performed at an earlier timing than the plucking operation of the string, pitch control corresponding to the fret position can be performed with a short response time. However, since a pitch corresponding to the fret position can only be obtained, even when a choking operation peculiar to a guitar (an operation for increasing a tension of a string by shifting a string in a direction perpendicular to an extension direction of the string while depressing it) is performed, pitch data cannot be changed as long as a depressed fret position is left unchanged. Therefore, a performance effect with poor expression can only be obtained.
In the fourth prior art, since a pitch is controlled on the basis of a pitch period extracted from a string vibration waveform in real time, a choking operation can be faithfully coped with, and a delicate nuance in string vibration can be reflected. Therefore, a performance effect with abundant expressions can be obtained. However, in order to obtain an accurate pitch period from a string vibration waveform, it must be waited until waveform data for at least one period is input from the beginning of inputting of the string vibration waveform, and a musical tone is generated thereafter. Therefore, when a vibration period of a string is short, there is no problem. However, when a vibration period is prolonged like a bass string, a delay time of 10 msec or more is generated from when a string is plucked until tone generation is started. Thus, a response time with respect to the plucking operation is prolonged, resulting in unnatural musical tone generation.