Abstract: The door insert of the present invention balances air pressure in a closed environment. It includes a frame that defines a slot. A pair of tabs emanates from opposing sides of the frame to attach the frame to a door. Media, which has a plurality of apertures therethrough, resides in the slot. The frame, with media installed therein resides within a notch in an edge of a door. Air is permitted to flow through the door insert to balance the air pressure within an environment divided by the door. The frame is preferably ABS plastic and the media is preferably paper. The appearance of the frame and media may be modified to aesthetically match the decor of the door, door hardware and surrounding environment.

Abstract: The door insert of the present invention balances air pressure in a closed environment. It includes a frame that defines a slot. A pair of tabs emanates from opposing sides of the frame to attach the frame to a door. Media, which has a plurality of apertures therethrough, resides in the slot. The frame, with media installed therein resides within a notch in an edge of a door. Air is permitted to flow through the door insert to balance the air pressure within an environment divided by the door. The frame is preferably ABS plastic and the media is preferably paper. The appearance of the frame and media may be modified to aesthetically match the decor of the door, door hardware and surrounding environment.

Abstract: The fan speed control circuit and system of the present invention includes a capacitor or internally triggered triac to enable current to flow across the terminals of an electrical switch for a fan motor when the switch is in the open and OFF position to permit continued operation of a fan so that the system complies with the ASHRAE 62.2 standard. The capacitor may be of a fixed value so that the speed of the fan motor is reduced to a fixed level when the switch is open and OFF. Alternatively, a potentiometer and internally triggered triac arrangement may be used to permit adjustment of the level to which the speed of the fan drops to when the switch is actuated to the open and OFF position. The present invention is a viable less expensive option to prior art microprocessor based fan speed control circuits.

Abstract: A scanner providing the function of an automatic document feeder type scanner and the function of a platform type scanner which includes a platform housing, a lift cover pivoted to the platform housing, an automatic document feeder pivoted to the lift cover and having a feeding slot covered with a dust cover, and a selector switch turned between a platform scan mode and an automatic document feeder scan mode, wherein when the selector switch is switched to the automatic document feeder scan mode, the lift cover is disengaged from the automatic document feeder and the automatic document feeder is retained to the platform housing, permitting the dust cover to be lifted with the lift cover for feeding paper; when the selector switch is switched to the platform scan mode, the automatic document feeder is engaged with the lift cover and disengaged from the platform housing and can be lifted with the lift cover from the platform housing.

Abstract: A pivoting joint connected between a first part and a second part of an instrument, permitting the first part to be turned relative to the second part and retained at one of a series of angular positions, including a first coupling member with a ratchet fastened to the first part of the instrument, a shaft mounted in an axle hole in the second part of the instrument, a sleeve and a spring holder mounted around the shaft within the axle hole of the second part of the instrument and forced by spring means to hold down the shaft, and a second coupling member fixedly mounted on the shaft and having a ratchet meshed with the ratchet of the first coupling member.

Abstract: An automatic programmed ventilation control system for operating a fan includes a fan drive circuit; a duty, cycle control circuit including means for selecting a duty cycle and means for setting the selected duty cycle; a timing circuit including means for selecting the time of day and means for setting the selected time of day; a fan speed control circuit including means for selecting a fan speed and means for setting the selected fan speed; and a manual override switch circuit for overriding the set duty cycle and fan speed for operating the fan at a predetermined speed for a preselected period of time.