Apple Inc.

Dirk Schmelzer

Jue Wang

Jerzy S Guterman

Benjamin A Cousins

Nathan Alan Johanningsmeier

David C Breece, Iii

Tian Shi Li

Jarrett B Lagler

Joel C Yamasaki

Phillip Qian

Rebecca J Russell

Jeyakkrishnan Chengleput Srinivasan

Sebastien D De Rivaz

A charging case for a pair of wireless earphones comprising: a housing having a peripheral wall that defines a shell; a frame insert coupled to the housing and extending into the shell, the frame insert having one or more insert walls that define first and second pockets sized and shaped to accept first and second wireless earphones, respectively, wherein the one or more insert walls cooperate with the housing primary wall to define a sealed chamber within the charging case; a lid coupled to the housing and operable between a closed position in which the lid covers the first and second pockets and an open position in which the first and second pockets are exposed; a speaker module disposed within the sealed chamber, the speaker module comprising an audio driver having a diaphragm that separates a front volume of the audio driver from a back volume of the audio driver and a speaker vent disposed within the back volume; one or more first openings formed through the peripheral wall and opening into the front volume, wherein the audio driver is positioned and aligned to emit sound into the front volume and through the one or more acoustic openings; and one or more second openings formed through the peripheral wall at a location spaced apart from the front volume, wherein at least one of the one or more second openings is an acoustic vent acoustically coupled to the back volume of the audio driver through the speaker vent ear tip.

Charging case for portable wireless listening device

A method for operating an audio system having multiple Class D audio amplifiers is described. An external oscillatory signal is coupled to the amplifiers, such that the switching frequencies of both of the amplifiers align with (e.g., are directly set to) a frequency of the external signal. An input level associated with an audio signal that is being amplified is detected, and the detected input level is compared to a threshold. When the comparison indicates that the input level is below a lower threshold, the frequency of the external oscillatory signal is raised, and when the comparison indicates that the input level is above an upper threshold, the frequency of the external oscillatory signal is lowered. Other embodiments are also described and claimed.

Class D amplifier with variable switching frequency

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Sunnyvale, CA, United States of America

Dirk Schmelzer