Abstract: An environmental control system for use in a greenhouse or another structure which requires the control of an ambient condition regulating element in response to a plurality of sensed parameters. The system includes a plurality of sensor elements and actuator elements, which communicate with a central control through communication interface units. In an illustrated embodiment the interface units communicate over previously installed AC power lines by frequency shift keyed signals. The interface units communicate to the peripheral control elements and the central control unit through serial digital signals. The central control maintains a protocol where, in response to operator inputs, time slots are assigned to different peripheral control elements to configure the system. Each peripheral control element is thereby addressed during its time slot and a sensor responds with data corresponding to a sensed parameter and an actuator executes a command.

Abstract: An environmental control system for use in greenhouses or other structures requiring the control of a temperature regulating element in response to sensed temperatures. The environmental control system includes a plurality of sensor elements and actuator elements comprising peripheral control elements each of which communicate bidirectionally with individual communication interface units. A central control processor bidirectionally communicates with another communication interface unit. All of the interface units bidirectionally communicate with each other over fixed AC power lines by frequency shift keying the information onto and from the lines. The control processor receives operator inputs which cause it to assign time slots to different peripheral control elements to configure the system whereby each peripheral control element can be interrogated by addressing it during its time slot.

Abstract: A pool cover sheet has beaded edges guided in side edge guides along the pool. The cover sheet is wound onto and pulled from a spool mounted on a motor driven shaft. The cover sheet is pulled by the spool by cords traveling along the side edge guides with cords being wound onto and from cord drums.The velocity of the cover sheet travel is attempted to be matched to the cover sheet velocity by means frustoconical drums having tapered surfaces onto which the cords are wound and unwound. To attempt to equalize the tension in the cords as well as in the cover sheet, the spools and drums are driven through opposed torsion springs from a common main shaft. The tension in the respective sides of the sheet or in the respective cords may be adjusted to take up any slack found to occur.

Abstract: A skylight system is formed of preglazed modules which are arranged side-by-side in a grid-like array which is supported on an underlying beam structure. The preglazed modules have slideably interfitting edges for joining to adjacent modules along all four sides of each module. The preferred modules are attached and are supported on corners thereof to the underlying beam structure. The interfitted edges allow slight relative shifting to accommodate expansion or contraction due to thermal conditions. Preferably, the modules may be supported and arrayed to define a flat surface or a predetermined curvature for the skylight. Broken glazing panels may be replaced in a given preglazed module. Gutters on adjacent modules are joined to provide a continuous moisture removal system.

Abstract: A greenhouse structure is formed with a substantially flat and horizontal roof formed of a plurality of roof sections each pivoted about a pivot or hinge end to swing upwardly from a closed position to an open position to admit ambient air to flow into or from the interior of the structure to cool the same. The roof sections are lifted by a lift means which becomes part of the roof supporting structure, and, to this end, the lift means is associated with the vertical support columns. Preferrably, the lift means comprises elongated straight lift members each carried by and stabilized by an associated support column for traveling along vertical and rectilinear paths of travel. The preferred means for shifting the lift members and thereby the roof sections comprises a rotatable nut in threaded engagement with the lift member to shift the same vertically as the nut is turned by a worm gear means.