发明名称 |
Video lighthead with dimmer control and stabilized intensity |
摘要 |
A video lighthead mountable to a video camera and having a dimmer control that varies the intensity of the light output from the lighthead using pulse width modulation techniques. A photo sensor measures the intensity of light reflected from a subject in front of the lighthead. The intensity of light output from the lighthead is adjusted by control circuitry in response to changes in measured reflected light intensity to maintain a constant level of illumination. The adjustment is carried out by modifying the duty cycle of a pulse width modulation circuit. The duty cycle adjustment of the pulse width modulation is also used to compensate for supply voltage variations in order to maintain constant light output.
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申请公布号 |
US5994844(A) |
申请公布日期 |
1999.11.30 |
申请号 |
US19970989923 |
申请日期 |
1997.12.12 |
申请人 |
FREZZOLINI ELECTRONICS, INC. |
发明人 |
CRAWFORD, JAMES J.;CRAWFORD, KEVIN J. |
分类号 |
G03B15/02;H05B39/04;(IPC1-7):G03B15/02;G01J1/32 |
主分类号 |
G03B15/02 |
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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