Audio output using multiple speakers

#Mobile telephones come in a variety of shapes and sizes, and are used in many different environments. Some mobile telephones provide multiple speakers, for example, to provide a conventional earpiece telephone functionality as well as a speakerphone functionality.

#One suitable industrial design for an earpiece speaker is a cup shape. However, the appropriate industrial design does not fit the sleek look and form factor demanded by consumers of mobile telephones. Some mobile telephones, such as smartphones, have a large touchscreen. The telephony receiver and earpiece are placed above the touchscreen, are becoming smaller, and cannot overhang above the touchscreen. The earpiece speaker in this configuration is leaky compared to the appropriate industrial design.

#Some mobile telephones also use high output impedance receivers to drive the earpiece speaker. These receivers do not adequately drive a low impedance load. Consequently, these mobile telephones have inherently restricted low frequency output and high distortion.

#FIG. 1 is a front view of a mobile computing device, according to an exemplary embodiment;

#FIG. 2 is a back view of a mobile computing device, according to an exemplary embodiment;

#FIG. 3 is a block diagram of the mobile computing device of FIGS. 1 and 2, according to an exemplary embodiment;

#Referring first to FIG. 1, a mobile computing device 10 is shown. Device 10 is a smart phone, which is a combination mobile telephone and handheld computer having personal digital assistant functionality. The teachings herein can be applied to other mobile computing devices (e.g., a laptop computer) or other electronic devices (e.g., a desktop personal computer, home or car audio system, etc.). Personal digital assistant functionality can comprise one or more of personal information management, database functions, word processing, spreadsheets, voice memo recording, etc. and is configured to synchronize personal information from one or more applications with a computer (e.g., desktop, laptop, server, etc.). Device 10 is further configured to receive and operate additional applications provided to device 10 after manufacture, e.g., via wired or wireless download, SecureDigital card, etc.

#Device 10 comprises a display 12 and a user input device 14 (e.g., a QWERTY keyboard, buttons, touch screen, speech recognition engine, etc.). Device 10 also comprises an earpiece speaker 15. Earpiece speaker 15 may be a speaker configured to provide audio output with a volume suitable for a user placing earpiece 15 against or near the ear. Earpiece 15 may be part of an electrodynamic receiver such as part number 419523 manufactured by Foster Electric Co., Ltd., Japan. Earpiece 15 may be positioned above display 12 or in another location on device 10. Device 10 comprises a housing 11 having a front side 13 and a back side 17 (FIG. 2). Earpiece 15 may be positioned on the front side 13 along with display 12 and user input device 14, and a loudspeaker 16 may be positioned on the back side along with a battery compartment 19. In alternative embodiments, display 12, user input device 14, earpiece 15 and loudspeaker 16 may each be positioned anywhere on front side 13, back side 17 or the edges therebetween.

#Loudspeaker 16 is an electro-acoustic transducer that converts electrical signals into sounds loud enough to be heard at a distance. Loudspeaker 16 can be a used for a speakerphone functionality. While loudspeaker 16 may be configured to produce audio output at a plurality of different volumes, it is typically configured to produce audio output at a volume suitable for a user to comfortably hear at some distance from the speaker, such as a few inches to a few feet away. Loudspeaker 16 may be an electrodynamic loudspeaker, such as part number HDR 9164, manufactured by Hosiden Corporation, Osaka, Japan.