Abstract: The three-legged folding chair has a primary frame with two legs and an apex, a secondary frame with two arms and an apex, and a third leg. The secondary frame is pivotally attached to the primary frame by two pivot pins. A back rest is secured to the primary frame adjacent to the primary frame apex. A support seat is attached to the arms of the secondary frame and are spaced from the secondary frame apex. The third leg is connected to the backrest adjacent to the primary frame apex. The apex of the secondary frame is held in a use position by the third leg. The secondary frame intersects the primary frame at an angle of about 66.degree. when held by the third leg. Both pivot pins are held out of axial alignment with each other when in the use position. The ground contact ends of the primary frame legs are under the forward edge of the support seat, the third leg is relatively short and weight is transferred to the third leg. The backrest is spaced forwardly from the primary frame apex.

Abstract: A pressure sensitive pointing device or pen is described for use with an electronic tablet that determines the position of the pointing device on the surface of the tablet. The pointing device incorporates a variable reluctance circuit responsive to the force exerted on the pen point for modulating a radiating frequency, emanating from the pen, in proportion to the force.

Abstract: The selective bird feeder (10) has a bird feed container (12) and a bird feed container cover (70). The bird feed container (12) has an open top (24 ) and bird feed access openings ( 32 ) . The bird feed container cover has a roof (72) and outer walls (76, 79, 80, and 82). Bird perch assemblies (84, 86) are attached to the outer walls (78, 82). A spring follower (74) with a vertical bore (94) is integral with the bird feed container cover (70). A vertical tube (48) is secured to the bird feed container (12) and extends upward through the vertical bore (94). A cap (108) is attached to the vertical tube (48) by a pin (110). A coil compression spring (68), inside the vertical tube (48), exerts a force on an adjustable lower spring abutment (50) and spring abutment surfaces (104) and (106) on radial projections (96, 98) that are integral with the spring follower (74) and extend through vertical slots (100, 102) in the vertical tube.

Abstract: The folding chair (10) includes V-shaped main support frame (12) with an apex (28) and two legs (22 and 24) with free ends. A V-shaped seat support frame (14) has an apex (40) and two arms (34 and 36) with free ends. The V-shaped seat support frame (14) is pivotally attached to the main support frame (12) by pivot pins (48 and 50) which allow pivotal movement between a position in which both V-shaped frames (12 and 14) are in a common plane and a position in which the seat support frame (14) is in a plane that is generally perpendicular to the plane through the main support frame (12). A third leg (16) is pivotally attached to the V-shaped main support frame (12) near its apex. The third leg (16) is connected to the apex portion (40) of the V-shaped seat support frame (14) by a pin member (66) and holds the seat support frame in a fixed position relative to the V-shaped main support frame.

Abstract: A position resolving system is described incorporating a cordless pointing instrument such as a pen having an oscillator and battery supply therein. Electromagnetic radiations from the pen are directed onto a tablet grid having a plurality of grid loops therein. When the pen is in contact with the tablet, signals of maximum amplitude are radiated; when the pen is raised out of contact with the tablet, signal radiation is maintained but at a decreased amplitude for a predetermined time and then reduced to zero. Each loop is formed of parallel conductors joined at one end thereof by an end conductor; each loop is placed adjacent corresponding loops in the X and in the Y directions. The electromagnetic radiations are non-coherently amplitude detected to select the grid loop in the X direction and the grid loop in the Y direction having the maximum amplitudes thereon.

Abstract: A digitizing system includes a tablet and a cordless pointing device including a plurality of data grid conductors in the tablet and a plurality of clock grid conductors in the tablet, all receiving a magnetic field signal transmitted by the pointing device. A data channel circuit includes a differential amplifier and demodulating and filtering circuitry coupled to an output of the differential amplifier, having a clock input. An A/D converter has an input coupled to an output of the demodulating and filtering circuitry. Multiplexing circuitry selectively couples various grid conductor signals to the data channel circuit. A clock recovery circuit responsive to the clock grid conductors includes a phase-locked-loop circuit that generates a recovered clock signal which is synchronous with the magnetic field signal and is used as a reference for demodulating the phase and amplitude of signals multiplexed from the data grid conductors to the data channel circuit.