Patent ID: 7161334

Claim:
A module configured for plug in electrical connection to a device having a processor, said module comprising: a high voltage power supply including a DC—DC converter, a voltage controlled resistor and a feedback circuit, said DC—DC converter having a low voltage input to which an input current is applied and a high voltage output at which an output current and an output voltage are developed, said voltage controlled resistor being electrically coupled to said high voltage output in parallel with said DC—DC converter and having an input wherein a resistance of said voltage controlled resistor is determined by an input voltage applied to said input of said voltage controlled resistor, said feedback circuit being operatively connected between said high voltage output of said DC—DC converter and said input of said voltage controlled resistor and developing said input voltage as a function of a reference voltage and said output voltage and further applying said input voltage to said input of said voltage controlled resistor such that a variation of said input voltage in response to a variation of said output voltage causes a variation of said resistance in opposition to said variation of said output voltage to maintain said output voltage constant; a memory in which information relating to voltage conversion curves of said DC—DC converter is stored and readable by said processor when said module is connected to said device; an operation detection unit that develops a voltage proportional to said output voltage; and a current sensor that develops a voltage proportional to said output current; said microprocessor being operative when said module is connected to said device to develop said reference voltage in response to each of said voltage developed by said operation detection unit and said voltage developed by said current sensor in accordance with said information to maintain said output current constant.