System for time sharing an audio amplifier

Claim 2

A circuit arrangement for time sharing at least one amplifier and at least two speakers, said arrangement having a first and second low level audio signal being supplied thereto, said circuit arrangement comprising means interposed between said first and second low level signals for supplying a first and second gating signal of opposite phase; means responsive to the first gating signal and first low level signal for gating said low level signal; means responsive to the second low level signal and the second gating signal for gating said second low level signal; means for amplifying said gated signals; means responsive to the amplified signal and said first gating signal for gating a first portion of said amplified signal to the high side of one of said speakers; and means responsive to the amplified signal and said second gating signal for gating a second portion of said amplified signal to the high side of the other of said speakers said means for gating the respective amplified signals including means for providing alternately a low impedance between the low side of one of the speakers and ground during one portion of a switching period and a high impedance between the low side of the other of the speakers and ground during the same portion of said switching period.

Claim 3

A circuit arrangement for time sharing at least one amplifier and at least two speakers, said arrangement having a first and second low level audio signal being supplied thereto, said circuit arrangement comprising means for supplying a first and second gating signal, each having a gating time interval and a blocking time interval, the gating and blocking intervals of said second signal being 180° out of phase with the gating and blocking intervals of said first signal; means interposed between said first and second low level signals and said amplifier responsive to the first low level signal and the first gating signal for gating said low level signal during the gating intervals of said first gating signal and for blocking said low level signal during the blocking intervals of said first gating signal; means responsive to the second low level signal and the second gating signal for gating said second low level signal during the gating intervals of said second gating signal and for blocking said second low level signal during the blocking intervals of said second gating signal; single channel means responsive to the gated portions of said first and second low level signals for amplifying said portions; first and second audio speakers; means responsive to the signal developed by said amplifier and the first gating signal for gating the amplified portion of said first low level signal and for supplying said gated amplified signal to the high side of said first audio speaker; and means responsive to said signal developed by said amplifier and the second gating signal for gating the amplified portion of said second low level and for supplying said amplified gated signal to the high side of said second audio speaker, said means for gating the respective amplified signals including means for providing a low impedance between the low side of the speaker and ground during one portion of a switching period and a high impedance between the low side of the speaker and ground during another portion of said switching period.

Claim 4

A circuit arrangement for time sharing at least one amplifier and at least two speakers, said arrangement having a first and second low level audio signal being supplied thereto, said circuit arrangement comprising means for supplying a first and second gating signal, each having a gating time interval and a blocking time interval, the gating and blocking intervals of said second signal being 180° out of phase with the gating and blocking intervals of said first signal; means interposed between said first and second low level signals and said amplifier responsive to the first low level signal and the first gating signal for gating said low level signal during the gating intervals of said first gating signal and for blocking said low level signal during the blocking intervals of said first gating signal; means responsive to the second low level signal and the second gating signal for gating said second low level signal during the gating intervals of said second gating signal and for blocking said second low level signal during the blocking intervals of said second gating signal; single channel means responsive to the gated portions of said first and second low level signals for amplifying said portions; first and second audio speakers; means responsive to the signal developed by said amplifier and the first gating signal for gating the amplified portion of said first low level signal and for supplying said gated amplified signal to the high side of said first audio speaker; and means responsive to said signal developed by said amplifier and the second gating signal for gating the amplified portion of said second low level and for supplying said amplified gated signal to the high side of said second audio speaker, said means for gating the respective amplified signals including means for providing a low impedance between the low side of the speaker and ground during one portion of a switching period and a high impedance between the low side of the speaker and ground during another portion of said switching period.

Claim 5

The circuit arrangement of claim 2, wherein each of said gating means responsive to said amplified signal also includes means for blocking from one speaker the portion of said amplified signal being supplied to the other speaker.

Claim 6

The circuit arrangement of claim 2, also including means for supplying a D.C. bias current to each speaker coil during a portion of the time sharing period and means for shorting each speaker coil during another portion of the period.

Claim 7

The circuit arrangement of claim 2, wherein said gating signals have a frequency of at least 30 KHZ.

Claim 8

The circuit arrangement of claim 2, including a second means for amplifying a third and fourth audio signal and wherein a third and fourth low level signal is supplied thereto, said arrangement also including means responsive to the third low level signal and the first gating signal for gating the third low level signal during the gating intervals of said first gating signal and for blocking said third low level signal during the blocking intervals of said first gating signal; means responsive to the fourth low level signal and the second gating signal for gating the fourth low level signal during the gating intervals of said second gating signal and for blocking said fourth low level signal during the blocking intervals of said second gating signal; means for summing the outputs of the first and third low level signal gating means and for supplying said summed signal to said first amplifying means; means for summing the outputs of the second and fourth low level signal gating means and for supplying said summed signal to said second amplifying means; wherein said means responsive to the amplified signal also includes means for gating the amplified portions of the sum of the first and third low level signal and for supplying said gated amplified signal to the first and third audio speakers and means for gating the amplified portion of the sum of the second and fourth low level signals and for supplying said gated amplified signals to the second and fourth audio speakers.

Claim 9

The circuit arrangement of claim 6, also including means for supplying a D.C. bias current to each speaker coil during a portion of the time sharing period and means for clamping each speaker coil during another portion of the period.

Claim 10

The circuit arrangement of claim 6, wherein said gating signals have a frequency of at least 30 KHZ.

Claim 11

A circuit arrangement for the suppression of induced noise caused by periodic switching of a speaker having a speaker coil, said circuit arrangement comprising means for supplying a high level signal to the high side of said speaker coil; means for providing a low impedance between the low side of the coil and ground during one portion of a switching period and a high impedance between the low side of the coil and ground during another portion of said switching period; means for providing a biasing current to said speaker coil during the portion of said switching period in which the low side of the coil is grounded through a low impedance; and means for preventing reverse current flow in said speaker coil during the portion of said switching period in which the low side of the coil is grounded through a high impedance.

Claim 12

A circuit arrangement for the suppression of induced noise caused by periodic switching of a speaker having a speaker coil, said circuit arrangement comprising means for supplying a high level signal to the high side of said speaker coil; means for providing a low impedance between the low side of the coil and ground during one portion of a switching period and a high impedance between the low side of the coil and ground during another portion of said switching period; means for providing a biasing current to said speaker coil during the portion of said switching period in which the low side of the coil is grounded through a low impedance; and means for preventing reverse current flow in said speaker coil during the portion of said switching period in which the low side of the coil is grounded through a high impedance.

Claim 13

The circuit arrangement of claim 9, wherein the means for supplying a high and low impedance is a transistor switch, said biasing current being supplied by a D.C. potential in series with the output electrodes of said transistor and said means for preventing reverse current flow through the speaker coil includes a clamping diode connected across the coil.