| 摘要 |
A control device (1) for transmitting an item of control information to at least one lamp unit, which has at least one light-emitting means and can be operated on alternating current, has a switchable output stage (18), a power supply (20), a zero crossing identification device (13) and a modulator for generating a modulation voltage for applying the item of control information to the AC voltage supplied to the lamp unit via the control device (1). Part of the control device (1) is also a logic unit (14). The control device (1) has a switchable parallel branch (21), via which, when switched, an impedance can be connected which is greater than the impedance of the output stage (18). In this case, provision is made for the parallel branch (21), when switched, to form a shunt via the power supply (20) in such a way that the internal resistance of the power supply (20) or, in the event of the presence of a plurality of internal resistances in the power supply (20), said internal resistances represent, overall or partially, the usable impedance. The invention also describes a method for determining the time of the beginning of a modulation phase following an operating phase by means of a control device (1), with a shunt being switched once said operating phase has ended in the lamp unit. Prior to the beginning of the shunt circuit flow connected on the lamp side, the output stage (18) is deactivated and the parallel branch (21) is activated in the control device (1). Upon detection of the shunt circuit flow, the output stage (18) is then activated and the parallel branch (21) deactivated before the data transmission begins. |
