Ambient-light-regulated night cut-off power control unit

Claim 2

An ambient-light-regulated night cut-off power system comprising: a continually operating clock, a light-responsive device the condition of which changes at dawn and at dusk, an electric load, a source of electric power, a control unit regulating the energy of said electric load from said source of electric power, means controlled by the light-responsive device to energize said load at dusk, means controlled by the condition of the light-responsive device for daily determining the span of time measured by the clock between dawn and dusk, means for determining a fraction of said span as a function of the time between dawn and dusk for each day, the fraction varying with the day of the year in such manner that a period of time is selected for each day which period is longer when the daytime is shorter and the nighttime longer and is shorter when the daytime is longer and the nighttime shorter, and means for de-energizing the electric load at a time beyond dusk equal to said pEriod of time so that de-energizing of the load takes place at approximately the same time each day for the geographical location of the unit regardless of the length of day and so that the true time of deenergizing is re-established on the day following a deenergization when a power failure occurs.

Claim 3

A system as set forth in claim 1 wherein the means controlled by the condition of the light-responsive device for daily determining the span of time measured by the clock between dawn and dusk determines the span of time measured by the clock from dawn to dusk.

Claim 4

A system as set forth in claim 1 wherein the time beyond dusk is true midnight for the geographical location of the unit.

Claim 5

A system as set forth in claim 1 wherein circuit means is included to actuate the energizing means under the regulation of the light-responsive device.

Claim 6

A system as set forth in claim 1 wherein the means for determining the fraction of said span of time constitutes a pair of rotary elements driven by the clock at different rates of speed between dawn and dusk, said rotary elements experiencing a relative angular change due to their different rates of speed of travel, said fraction being a function of such relative angular change.

Claim 7

A system as set forth in claim 1 wherein the clock is a 24-hour clock.

Claim 8

A system as set forth in claim 1 wherein the control means, the determining means and the de-energizing means constitute two shafts, means continually driving one of said shafts from the clock at one revolution per day, means driving the other shaft from the clock at a fraction of one revolution per day, said last-named driving means including means for rendering the same ineffective, said one shaft driving a first contact, the other of said shafts driving at least two angularly spaced second contacts, one or another of the second contacts being in the path of travel of the first contact when the de-energizing means is effective to prevent the other shaft from being driven by the clock, the second contacts being out of the path of travel of the first contact when the de-energizing means permits driving of the other shaft by the clock.

Claim 9

A system as set forth in claim 7 wherein circuit means is included for actuation and de-actuation of the energizing means under the control of the light-responsive device, the circuit means being effective to prevent turning of the second shaft by the clock from dusk to dawn.

Claim 10

A system as set forth in claim 8 wherein the means energizing the electric load from the source of electric power includes switches, of which one is under the control of the light-responsive device and the other is under the control of said contacts, the load being de-energized when the first contact engages a second contact and the time of day is the period from dusk to dawn.

Claim 11

A system as set forth in claim 1 wherein the control means, the determining means and the de-energizing means constitute a first shaft, means for constantly driving the first shaft from the motor at one revolution per day, a sleeve on the shaft, said sleeve being rotatable and axially shiftable with respect to the shaft, said sleeve having a gear thereon, said output shaft having a gear thereon engageable with the gear on the sleeve, the ratio of said gears being such that the sleeve turns slower than the shaft, a solenoid having an armature, means connecting the armature to the sleeve in such manner that when the solenoid is de-energized the gears are in mesh, means for shifting the sleeve and disengaging the gears when the soleonid is energized, the sleeve being stationary, unless driven, when the gears are disengaged, a first contact carried by the shaft, at least two second contacts carried by the sleeve, said first contact and said second contacts having common paths of travel when the solenoid is energized and having paths of travel which are mutually spaced in a direction longitudinally of the shaft when the solenoid is de-energized, and circuit means energizIng the solenoid under the control of the light-responsive device during the night, said circuit means energizing said electric load from said source of electric power, said circuit means including a switch which is closed when the solenoid is energized and open in the daytime, and a second switch which is open when the contact on the first shaft engages a contact on the sleeve and is closed when the contact on the first shaft is spaced from the contacts on the sleeve.

Claim 12

A system as set forth in claim 10 wherein there are two contacts carried by the sleeve which contacts are spaced 180* apart.