Electronic flash control device
AssigneeMinolta Camera Kabushiki Kaisha
InventorHiroshi Hosomizu
Life of this patent
Estimating the term…
Abstract
A control circuit controls the amount of light emitted from an electronic flash tube in accordance with the voltage of a main capacitor, which energizes the flash tube, and a set guide number so that the amount of light may be constant irrespective of changes in the voltage of the main capacitor due to consumption of a power source battery from which electric energy is supplied to the main capacitor. The control circuit may include a storing or memorizing capacitor for storing a signal corresponding to the voltage of the main capacitor and further include a transistor which generates a current commensurate with the stored signal, the current being integrated to actuate a flash emission stopping circuit when the integration reaches a given level.
Claims6
An electronic flash device which is equipped with an electronic flash tube capable of emitting light due to discharge of a main capacitor, comprising:
- means for storing a signal corresponding to a potential in said main capacitor at a time before the emission of light from said electronic flash tube;
- a current supply circuit for supplying a current commensurate with the stored signal, simultaneously with the starting of emission of light from said electronic flash tube, the current level being proportional to the potential of said main capacitor but substantially independent of the emitted light;
- an integrating capacitor for integrating the current from said current supply circuit;
- and
- a control circuit for interrupting the emission of light from said electronic flash tube when the charge potential on said integrating capacitor reaches a given level to maintain the total amount of light emitted from said flash tube constant with different potentials of said main capacitor.
Dependencies are inferred from the claim text.