US 6,919,771 B2 · Digital amplifier

Abstract

An object of the present invention is to provide a digital amplifier which is capable of preventing a reproduction of an analogue audio signal from a loud speaker, when an output sound volume from the loud speaker is set to zero and when inputting of a digital audio signal or an input signal is stopped. In order to achieve the object, in the digital amplifier of the present invention, a silent PWM signal output section 7 outputs a PWM signal having a duty ratio of 50%, instead of a PWM signal generated by the PWM signal generating section 6, in the following cases: the factor detecting section 3 detects that the digital audio signal is multiplied by the factor “0” in the gain regulation section 2, the silent signal determining section 4 determines that the signal input from the reproducing unit 13 is stopped, and the silent signal determining section 4 determines that the digital audio signal is a signal at a silent level.

Claims3

Dependent claims

A digital amplifier comprising,

a gain regulation means which regulates an gain for a digital audio signal,
a PWM signal generating means which generates a PWM signal from said digital audio signal, said gain which has been regulated by said gain regulation means,
a switching means which switches a switching power supply in response to said PWM signal generated by said PWM signal generating means,
a detecting means which detects said gain which has been regulated by said gain regulation means, and
a silent PWM signal outputting means which outputs to said switching means a PWM signal having a duty ratio of 50%, instead of said PWM signal which has been generated by said PWM signal generating means, when said detecting means detects that said gain is zero.

2 more elements

Dependencies are inferred from the claim text.

Digital amplifier

Life of this patent

Digital amplifier

Life of this patent

Abstract

Claims3