Abstract: The cooled photosensitive cell (1) according to the invention comprises a table (2), a sensor (3) which is fitted on the table (2) and is connected to electrical connection tracks (30), a screen (10) to prevent parasitic radiation on the sensor (3), and a Joule-Thomson cooler (4) in order to cool the table (2) and the screen (10). The table (2) and the screen (10) are cooled by convection by being subjected directly to the volume of expansion of the cooler (4), the table (2) being provided with apertures (6) for passage of the cooling flow communicating with a cavity (14) for cooling of the screen (10).

Abstract: To reduce the effects of disturbing electromagnetic effects on a loudspeaker of a mobile telephone, the loudspeaker is provided with a compensation coil in addition to an excitation coil. The compensation coil is series-connected with the excitation coil. However, it is dispensed of the need for playing a driving role by being bonded to the permanent magnet of the loudspeaker: It is shown that the harmful effects are reduced without stopping the loudspeaker from working.

Abstract: A mobile telephone is equipped with a smart-card reader to aid in universal payment by smart card. A security checking circuit of the mobile telephone is provided with a complementary function by which the mobile telephone can behave like a secured smart-card reader with a view to payment. Smart-card payments are facilitated by disassociating an act of payment from an act of purchase which can be done by any means, in particular through the internet.