TOUCH-RESPONSIVE KEYING CIRCUIT FOR ELECTRONIC MUSICAL INSTRUMENTS

• US 3,784,718 A
• Filed: 07/20/1972
• Issued: 01/08/1974
• Est. Priority Date: 07/20/1971
• Status: Expired due to Term

• Current Assignee: Yasuji Uchiyama
• Original Assignee: Yasuji Uchiyama
• Inventors: Uchiyama, Yasuji
• Primary Examiner(s): Wilkinson, Richard B.
• Assistant Examiner(s): Witkowski, Stanley J.
• Application Number:
  US05/273,608
• Time in Patent Office: 537 Days
• Field of Search: 84/1.01,1.09,1.1,1.13,1.26,1.27,DIG.23 317/151 307/108,265 320/1
• US Class Current: 84/687
• CPC Class Codes: G10H 1/34 Switch arrangements, e.g. keyboards or mechanical switches specially adapted for electrophonic musical instruments
• CPC Class Codes: Y10S 84/23 Electronic gates for tones

Abstract

In an electronic musical instrument, tone keyer circuits are respectively controlled by touch-responsive keying circuits. The touch-responsive keying circuit comprises: a key switch having a break contact, a make contact and a movable contact; a first charge-discharge circuit having a charging capacitor and a discharging resistor both connected between the movable contact and the ground; an electrical source +B connected to the break contact; a switching transistor with its base connected to the make contact; and a second charge-discharge circuit being provided between the emitter of the transistor and the ground with a second capacitor and with a series circuit of a second resistor and an normally closed switch which is ganged with the key switch, the capacitor being connected to the keyer circuit. While the movable contact of the key switch travels from the break contact to the make contact, the first charge-discharge circuit is discharged with a predetermined time constant. The switching transistor is brought conductive to the extent responsive to a charged voltage remaining in the first chargedischarge circuit at the time the movable contact touches the make contact. The second charge-discharge circuit is charged through the transistor to establish a keying voltage.

Claims

1. A touch-responsive keying circuit comprising:

a circuit ground;

a power source;

a key switch having a break contact connected to said power source, a make contact and a movable contact;

a first charge-discharge circuit having a charging capacitor and a discharging resistor both connected between said movable contact and said ground;

a transistor having a base connected to said make contact, a collector connected to said power source, and an emitter; and

a second charge-discharge circuit including a second capacitor connected between said emitter and said ground, a second resistor and a second switch connected in series between said emitter and said ground, said second switch being of a normally closed type and gang-operated with said key switch.

2. A touch-responsive keying circuit as claimed in claim 1, in which said first charge-discharge circuit is provided with means for applying across said charging capacitor a divided voltage of said power source, whereby when the first charge-discharge circuit is discharged, the resultant voltage of the first charge and discharge circuit is maintained not lower than said divided voltage.

3. A touch-responsive keying circuit as claimed in claim 1 which further comprises a change-over switch having a first stationary contact connected to said charge-discharge circuit, a second stationary switching contact connected to the break contact of said key switch, and a movable contact connected to said power source.

4. A touch-responsive keying circuit as claimed in claim 3 in which a movable contact of said change-over switch is connected to a separately provided adjustable power source.

5. A touch-responsive keying circuit as claimed in claim 3, in which a plurality of touch-responsive keying circuits are provided, and one common change-over switch is provided for these touch-responsive keying circuits.