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Integrated handsfree design with leak tolerant receifer characteristics

IP.com Disclosure Number: IPCOM000011929D
Original Publication Date: 2003-Apr-25
Included in the Prior Art Database: 2003-Apr-25

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To make a phone with a single loudspeaker, that is leak tolerant in receiving mode and has good handsfree performance. When applying leak tolerant design methods typically used in small handsets (e.g. in Siemens S40) as patented by Kirk Acoustics (WO 0021330), it becomes a problem to fulfil integrated handsfree functionality. In such designs the load hole(s) are used to pull down the bass of a bass boosted receiver by giving acoustical access from the artificial ear coupler volume to the backside of the receiver. However, in integrated handsfree, this is not desirable, since it pulls down the bass drastically in free field leading to unacceptable integrated handsfree performance. The design outlined in this report is used to provide leak tolerant receiving performance, while maintaining an acceptable integrated handsfree performance. By making compromises an the acoustic performance of either the handsfree or receiving mode resulting in either: Poor low frequency performance in handsfree Modest leak-tolerance Very large transducer and air volumes inside handset The idea is the introduction of two outlets from the speaker front volume, where one outlet acts as a load when the handset is held against the ear, because it is outside the ear cavity, is already known technology. The inventive step is to use this type of leak tolerant design in order to support handsfree functionality, where the two outlets work in parallel in free field. See figure 1 for an illustration of the mechanical concept and figure 2 and 3 for measurements an actual prototype. The problem is solved by introducing a load to obtain leak-tolerance in the receiver mode, which works as an parallel outlet in handfree mode. The advantages are: No energy is lost in handfree mode by introducing a load to obtain leak-tolerance in the receiver mode, since the outlet and load work as two parallel outlets in handfree mode. The tuning of the device is simpler, since there is no acoustical feedback involved in this leak tolerant concept Separate tuning of front and backside load of the speaker No acoustical feedback to the backside of the speaker is required