RADIATION SOURCE DRIVING DEVICE AND METHOD FOR DRIVING A RADIATION SOURCE

摘要

The invention pertains to a radiation source driving device for controlling a voltage fed to a radiation source in an information reproducing system comprising a radiation source controller for controlling the voltage fed to the radiation source, and a power supply for providing a working voltage to the radiation source controller. In prior art systems the working voltage fed to the radiation source controller must be high enough to be able to give enough power to the radiation source in all situations. Thus the working voltage must be equal to a worst case situation wherein the radiation source is fed with a maximum voltage in order to achieve maximum power. In situations wherein the radiation source does not need maximum voltage the working voltage over the control circuit is higher than needs to be for that situation. This extra voltage drop results in power dissipation thereby increasing the temperature of the control circuit and its environment. As increasing speeds require higher radiation powers and the radiation source performance diminishes rapidly with temperature, the temperature control at the radiation source becomes of increasing importance. According to the invention the power supply comprises a control input for controlling the working voltage to the radiation source controller and in that the radiation source driving device further comprises power supply control means for generating a control signal which is fed to the control input of the power supply wherein the control signal is dependent on the voltage fed to the radiation source. If the voltage fed to the radiation source is relatively high, then the radiation source driving device needs a relatively high working voltage to be able to feed the relatively high voltage to the radiation source without the driver output saturating due to the voltage generated across the radiation device. If however the voltage fed to the radiation source is relatively low, then it suffices to feed the radiation source driving device with a relatively low working voltage. By supplying the radiation source driving device with a relatively low working voltage when it does not require a relatively high working voltage, the result is that the average voltage drop over the radiation source driving device is reduced. This has the effect that power dissipation by the radiation source driving device is reduced and therefore the heat generation of the device is reduced.