Capacitor charging device for a flash
AssigneePremier Image Technology Corporation
InventorsWen-Hwa Lin, Chien-Kuo Hsu
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Abstract
A capacitor charging device for a flash, finishes charging the flash capacitor in a gradual manner. It has a flash capacitor, a voltage transforming circuit, a voltage mode pulse width modulation (PWM) control circuit and a charging control circuit. The charging control circuit has a time control capacitor to make the pulse width of the pulse voltage output from the voltage mode PWM control circuit increase gradually. The voltage transforming circuit is driven to provide a gradually increasing induced current to the flash capacitor to reduce the damage of the external circuit, flash capacitor and rechargeable battery.
Claims8
A charging device, comprising:
- a flash capacitor;
- a voltage transforming circuit, electrically connected to the flash capacitor and providing an induced current to charge the flash capacitor;
- and
- a voltage mode pulse width modulation (PWM) control circuit, electrically connected to the voltage transforming circuit and providing a pulse voltage to drive the voltage transforming circuit to provide the induced current;
- wherein the voltage mode PWM control circuit increases a pulse width of the pulse voltage in a gradual way to prevent the induced current from increasing abruptly.
A capacitor charging device, comprising:
- a flash capacitor;
- a voltage transforming circuit, electrically connected to the flash capacitor and providing an induced current to charge the flash capacitor;
- a voltage mode PWM control circuit, electrically connected to the voltage transforming circuit and providing a pulse voltage to drive the voltage transforming circuit to provide the induced current;
- and
- a charging control circuit, electrically connected to the voltage mode PWM control circuit to control a pulse width of the pulse voltage;
- wherein the charging control circuit has a time control capacitor and the pulse width of the pulse voltage increases when the voltage across the time control capacitor increases, the time control capacitor having a predetermined capacitance to make the flash capacitor be charged completely within a soft start period.
Dependencies are inferred from the claim text.