Title:
ENVELOPE GENERATOR USING DOUBLE ELECTRIC CHARGE PUMP
Document Type and Number:
Japanese Patent JPS582892
Kind Code:
A
Abstract:
An envelope generator for use in an electronic musical instrument, such as an electronic organ, employing a dual charge pump to form the attack and decay portions of the envelope. The envelope generator is adapted to be connected to the envelope control input of the keyer and the other input of the keyer is connected to a tone source. When the appropriate key of the keyboard is depressed, a source of input voltage is connected to the input of the envelope generator and a first charge pump incrementally transfers the input voltage to a capacitor over a first sequence of discrete time frames. The first charge pump circuit comprises a pair of electronic switches clocked 180 DEG out of phase and a capacitor connected between the juncture of the two switches and ground potential. The second mentioned capacitor is much larger than the first mentioned capacitor so that the charge transfer from one to the other takes place in a plurality of discrete steps. A second charge pump connected serially between the first charge pump and the envelope input of the keyer incrementally transfers the voltage on the first mentioned capacitor to another capacitor over a second sequence of discrete time frames. The second charge pump also comprises a pair of electronic switches having a capacitor connected between their juncture and ground potential, and a clock which clocks the electronic switches 180 DEG out of phase at a second frequency higher than the frequency at which the first two electronic switches are clocked. This arrangement has the effect of reducing the magnitude of the discrete steps thereby avoiding the audible distortion associated with prior envelope generators of this type. If desired, the second charge pump can be dual phase so that the effective frequency ratio between the second and first charge pumps is effectively doubled.
Inventors:
SUCHIIBUN ERU HAUERU
RARUFU ENU DEIITORITSUCHI
RARUFU ENU DEIITORITSUCHI
Application Number:
JP10467682A
Publication Date:
January 08, 1983
Filing Date:
June 17, 1982
Export Citation:
Assignee:
KIMBALL INT
International Classes:
G10H1/057; H03K4/02; (IPC1-7): G10H1/057
Domestic Patent References:
| JPS5512901A | 1980-01-29 |
Attorney, Agent or Firm:
Kyozo Yuasa
Next Patent: SURFACE EMITTING SEMICONDUCTOR LASER DEVICE