Rotator wheel

#The present invention relates to the field of user interfaces for multimedia devices, and in particular a rotator wheel for a mobile telephone.

#Multimedia devices commonly use a plurality of dome switches that interact cooperatively with keys on the multimedia device. When a key is depressed by the user, the dome switch is activated so as to provide an electrical signal to the circuitry of the multimedia device.

#FIG. 1 of the attached drawings shows an exemplary multimedia device 1 comprising a screen 2, a keypad 3, a navigator key 4 and additional keys 5. The navigator key 4 and the additional keys 5 allow the user to interact with a user interface displayed on the screen 2. The navigator key 4 and the additional keys 5 typically operate so as to interact with dome switches mounted on a printed wiring board.

#Embodiments of the present invention will now be described with reference to the accompanying drawings briefly described below.

#FIG. 1 shows an example of a multimedia device.

#FIGS. 2A and 2B show a cross section of a typical dome switch in a non-actuated and actuated state respectively.

#FIG. 4 shows a navigator key 21 and a rotator wheel 22 mounted on a dome sheet 23 in accordance with a preferred embodiment of the present invention. The navigator key 21 and rotator wheel 22 replace the navigator key 4 of the multimedia device 1 shown in FIG. 1. The navigator key 21 may be a 4-way or 5-way navigator key.

#The function of the rotator wheel 22 will now be described. The rotator wheel 22 may rotate in either a clockwise or an anticlockwise direction about its centre on an axis perpendicular to the plane of the dome sheet 23. The direction of rotation of the rotator wheel 22 is shown by arrow 24, this arrow is not an essential feature of the present invention. The rotator wheel 22 is mounted on a lower track section that does not rotate. The lower track section comprises a means for facilitating the monitoring of the rotational position of the upper wheel by the multimedia device 1, in order that a user may interact with the multimedia device by rotating the rotator wheel 22.

#The monitoring means may comprise two concentric substantially annular conductive tracks, and a bridge contact arranged to rotate in conjunction with the rotator wheel 22. The bridge contact may slide along both of the concentric substantially annular conductive tracks, and provide an electrical contact between the two concentric substantially annular conductive tracks. The two concentric substantially annular conductive tracks both contain a relatively small non-conductive sector. Circuitry of the multimedia device 1 may thus apply pulses to one of the two concentric substantially annular conductive tracks and monitor the amount of time required for the pulse to return along the other concentric substantially annular conductive track. The length of time the pulse takes to return gives an indication of the position of the conducting bridge and hence the position of the rotator wheel 22. Thus, by monitoring the position of the rotator wheel over time, the circuitry of the multimedia device may measure the motion of the rotator wheel.