Illumination – Photographic lighting – Light responsive
Patent
1989-02-13
1990-09-25
Hart, Douglas
Illumination
Photographic lighting
Light responsive
250205, 315151, 315153, 315158, 315241S, 315291, 315307, 354413, 362 5, 362276, G03B 1502, G01J 132, G05F 100, H05B 3904
Patent
active
049597558
ABSTRACT:
An automatic battery powered video light (10) is supplied power by a d.c. battery (16). A light (20) is connected between a first terminal of the battery (16) and a MOSFET switch (46), which is connected to a second terminal of the battery (16). A control circuit (24) controls the opening and closing of the MOSFET (46) to supply power to the light (20) and disconnect power from the light (20). The control circuit (24) includes a light sensor (36) for sensing ambient light and reflected radiant light from a scene (14) and a pulse width modulator (40) for controlling the MOSFET switch (46). The modulator (40) increases pulse width and therefore closing time of the switch (46) when the sensor (36) senses time low light levels, and vice versa. Also provided is a dual filament light (20') wherein each filament (52, 54) is independently controlled to enhance color balance.
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patent: 4634933 (1987-01-01), Kamon et al.
patent: 4682084 (1987-07-01), Kuhnel
patent: 4808809 (1989-02-01), Hayakawa
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