Charging control device for flash device

• US 5,587,644 A
• Filed: 06/12/1995
• Issued: 12/24/1996
• Est. Priority Date: 06/15/1994
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Masaki, Junya
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): SHIN, KYUNG E
• Application Number:
  US08/490,000
• Time in Patent Office: 561 Days
• Field of Search: 320/1, 320/35, 354/416, 354/418, 354/428
• US Class Current: 396/205
• CPC Class Codes: H05B 41/325 by measuring the incident light

Abstract

A charging control device for a flash device is arranged to detect ambient temperature in controlling a flash device charging voltage and to perform the charging control up to a level corresponding to the temperature detected, so that the flash device can be allowed to flash at a constant guide number irrespective of any changes in temperature.

Claims

1. A charging control device for a flash device, comprising:

a) temperature detecting means for detecting a temperature condition; and

b) charging regulating means for regulating a charging action on a main capacitor of the flash device on the basis of the temperature condition detected by said temperature detecting means, said charging regulating means including memory means for storing charging action data corresponding to diverse temperatures.

2. A device according to claim 1, wherein said charging regulating means is arranged to control a charging voltage for the main capacitor of the flash device to obtain a voltage corresponding to the charging action data stored in said memory means.

3. A device according to claim 2, wherein said stored charging action data corresponds to a plurality of different charging voltages, said charging regulating means further including reading means for reading out from said memory means, stored charging action data corresponding to the temperature condition detected, and controls the charging voltage for the main capacitor on the basis of the data read out by said reading means.

4. A charging control device for a flash device of a camera, comprising:

a) detecting means for detecting a charging voltage for a main capacitor of the flash device;

b) a writable and erasable memory circuit in which data corresponding to a charging voltage related to a guide number for the camera is written;

c) an A/D conversion circuit for converting the charging voltage detected by said detecting means into a digital value; and

d) a charging circuit for making a comparison between the digital value obtained by said A/D conversion circuit and the data read out from said memory circuit and stopping a charging action performed on the main capacitor when the comparison provides a predetermined result.

5. A method for setting a charging voltage for a flash device, comprising:

a) a step of setting, in a memory, charging data corresponding to a reference guide number;

b) a step of causing the flash device to perform flash emission in a state of having a main capacitor of the flash device to perform flash emission charged up to a charging voltage corresponding to the charging data;

c) a step of measuring a guide number which is obtained by the flash emission; and

d) a step of writing new charging data in said memory according to a difference between the measured guide number and the reference guide number.