Manually operable electric curtain

Claim 1

A manually operable electric curtain provided with a curtain rail, a multiplicity of runners movably mounted in said rail, a curtain cloth suspended by said runners, a cord pulley provided on one end or in the vicinity of said curtain rail, a tension pulley provided on the other end or in the vicinity of said curtain rail, a cord looped between said cord pulley and said tension pulley to move along said curtain rail and attached to one of said runners, an electric motor adapted to rotate said cord pulley, open, close and stop switches, a main motor-driving circuit for supplying an electric current to rotate said motor in either direction when said open or close switch is activated and interrupting the current when said stop switch is activated, said curtain comprising a sun gear fixed to the output axis of said motor, an arm rotatably mounted on the output axis of said motor, a planet gear rotatably mounted on said arm to engage said sun gear, a driven gear integrally fixed to said cord pulley and selectively engageable with said planet gear, said arm being arranged to have a less rotational resistance than that of said planet gear, said planet gear being engaged with one side of said driven gear when said open switch is activated and with the other side of said driven gear when said close switch is activated, a pulse-generating circuit for transmitting pulses for a predetermined short time as a result of said stop switch being activated, and an auxiliary motor-driving circuit for supplying an inverse electric current to the current supplied by said main motor-driving circuit while said auxiliary motor-driving circuit is receiving the pulses from said pulse-generating circuit, whereby, when said stop switch is activated, said planet gear disengages from said driven gear and allows said curtain cloth to be easily drawn by hand without receiving the rotational resistance of said motor.