Technical Field

The present invention relates to sockets for headphone sets.

Background

Development of mobile phone and other portable device technology has meant that many of these devices are provided with a 3.5mm (diameter) connector which allows them to connect with a combined headphone and microphone set. Typically these comprise a speaker for each ear and a microphone, usually provided as a medallion. The connectors, or sockets, (of the mobile phone/portable device technology) for such sets are provided with four terminals, as is the set's plug/pin.

An issue arises that different manufacturers configure the contacts of the plug differently. Manufacturer A may have the microphone contact as an inner terminal whereas manufacturer B may have the microphone on the outer terminal. In an aircraft seat with inflight entertainment, passengers often chose to listen to the audio provided using their personal headphones, rather than the ones provided by the airline. Sometimes the passenger will desire to use his/her combined headphone/microphone set which has a four contact plug. Because the audio socket module in the aircraft is normally configured with only three terminals, use of a plug with four contacts creates an incompatibility that results in loss of either left or right audio when a combined headphone/microphone is connected.

We have devised an improved socket for headphone sets. Summary

According to the invention there is provided a socket for headphone sets, comprising: four terminals, arranged to contact with terminal contacts of a plug of audio headphones, the terminals longitudinally spaced within a plug-receiving space of the socket, wherein the two of the adjacent terminals are electrically connected together. The socket may be termed an audio jack, and may generally be thought of as an audio interface.

The interface may be a passenger audio interface for an aircraft, or other passenger transportation. Moreover, the audio interface may be used in any application in which many audio interfaces are provided, which, in addition to passenger transportation (such as planes, trains, waterborne vessels, buses and mass transportation), includes venues such as studios, theatres, conference centres, classrooms etc. The headphone set may comprise one or more features described in the description and/or shown in the drawings.

Brief Description of the Drawings

One embodiment of the invention will now be described, by way of example only, with reference to the following drawings in which:

Figure 1 is a schematic representation of an audio jack with a first type of headset plug inserted therein. Figure 2 is a schematic representation of the audio jack with a variant of the first type of headset plug therein, and

Figure 3 is a schematic representation of the audio jack with a second type of the headset plug therein.

Detailed Description

Reference is made to Figures 1 , 2 and 3, which show a plug 1 of a headphone set inserted into an audio socket, or jack, 2. The jack 2 is provided with a plug-receiving space 3 which comprises an elongate space arranged to receive the plug. When inserted into the jack, the tip and sleeve contacts come into electrical contact with the terminals. As will be described below the jack 2 allows use of both a three and four contact pin to be used.

The jack 2 comprises four electrical terminals 5, 6, 7 and 8. Each contact is resiliently biased towards the plug-receiving space 3 of the jack, thereby ensuring that when a plug is inserted onto the jack that the contacts are deflected outwardly and providing a counter-force to maintain engagement with the contacts of the plug thereby ensuring an electrical conduction between the pin and the terminal. Those portions of the terminals which engage with the pin are spaced along the length of the plug-receiving space 3. The positioning of the terminals within the space 3 is determined so as to be in register with a respective contact of the plug.

Comparing the plugs la and lb, as is reflective of plugs produced by different manufacturers, the plug la has the sleeve contact 1 1a providing a ground return, which could be termed the innermost sleeve, whereas the plug lb provides in innermost sleeve l ib as the microphone signal contact. It will be appreciated that the plugs la and lb are connected to a headphone set which comprises left and right channel speakers, and a microphone . Such headphone sets are typically used with mobile phones, as well as other types of device, to allow the wearer to speak into the microphone, for example whilst making a phone call.

In the example illustrated, the pin la comprises three sleeve contacts 1 1 a, 12a, 13a and a tip contact 14a. Those contacts are arranged to engage with terminals 5, 6, 7 and 8 respectively. Similarly, the sleeve contacts l ib, 12b, 13b and the tip contact 14b are arranged to engage with the terminals 5, 6, 7 and 8 respectively. Finally, the three contact plug lc, comprises two sleeve contacts 1 1c and 12c, and a tip contact 13c, for which the contacts 1 1c and 12c are arranged to engage with the terminals 5 and 6, and the tip contact 13c is arranged to engage with the terminal 8.

In the context of passenger entertainment systems, for which the jack 2 is primarily but not exclusively, intended, the jack 2 allows passengers to use either the headphone sets with microphones having four contacts pin as well as headphone sets without microphones with three pin contacts.

The jack 2 is part of an audio interface of an 'at-seat' passenger entertainment system, with an interface being provided for each passenger, at or adjacent to each passenger' s seat. When the user' s headphone set is connected to the jack 2, passengers may select audio or visual content, such as music or the spoken word. As can be seen in the Figures, the (end of the) terminals 5 and 6 are electrically connected together at 20. This provides a short between the two terminals. Both terminals are connected to a ground electrical potential thus, advantageously, regardless of whether a user inserts a plug of type la or of type lb, the return terminal of either headphone be connected to ground. Further advantageously, if a plug lc, of the 'non-microphone ' headphone set type is inserted into the jack, the return sleeve contact 1 1c will engage with both of the terminals 5 and 6, thus correctly providing a ground connection for the headphone set. The jack is perfectly compatible not only with different contact configurations of four contact headphone set plugs, but is also compatible with three contact plugs.