发明名称 |
Method and apparatus for determining line frequency and detecting light sources of various frequencies. |
摘要 |
<p>The method involves determining the presence of a line frequency from a group of possible line frequencies, including a first line frequency having an associated first flicker frequency period and a second higher line frequency having an associated second flicker frequency period. The method involves sampling the ambient light to obtain a first analogue voltage sample representative of ambient light level for a first sample group and digitally converting it. The first sample group corresponds to the first line frequency and consecutive analogue voltage samples for the first sample group are taken at a first sample rate. The ambient light is then sampled to obtain a first analogue voltage sample for a second sample group after a predetermined time from the first sample, and A/D converts it, the second sample group corresp. to the second line frequency. The two sample rates are defined by the following: sample rate = 1/(ffX n), where ff = flicker frequency in Hertz, and n = number of samples per flicker frequency period. The preset time interval is at least equal to a time required for the conversion and less than a shortest time such that a future sample for the first sample group would coincide with a future sample for the second sample group. The sampling and converting of both sample groups are repeated until a predetermined number of samples are taken, and the converted samples in at least one group are compared to determine if a presence of the line frequency is indicated.</p> |
申请公布号 |
EP0645612(A1) |
申请公布日期 |
1995.03.29 |
申请号 |
EP19940114913 |
申请日期 |
1994.09.22 |
申请人 |
EASTMAN KODAK COMPANY |
发明人 |
GABOURY, MICHAEL JOSEPH, C/O EASTMAN KODAK CO.;COCCA, J. DAVID, C/O EASTMAN KODAK CO. |
分类号 |
G01R23/02;G01J1/42;G01J1/44;G03B7/08;(IPC1-7):G01J1/42;G03B7/091;G03B7/24 |
主分类号 |
G01R23/02 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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