摘要:
A system for controlling a roller shade having a roller tube windingly receiving a shade fabric varies roller tube rotational speed for constant linear shade speed. The desired linear shade speed, roller tube diameter and shade fabric thickness and length are stored in a memory for use by a microprocessor. Preferably, the roller tube rotational speed is varied by the microprocessor depending on shade position determined by signals from Hall effect sensors. The microprocessor maintains a counter number that is increased or decreased depending on direction of rotation. Based on the counter number, the microprocessor determines shade position and a corrected rotational speed for the desired linear shade speed. Preferably, the microprocessor controls roller tube rotational speed using a pulse width modulated signal. The system may be used to control first and second roller shades having roller tubes of differing diameters or shade fabrics of varying thicknesses.
摘要:
A system for controlling a roller shade having a roller tube windingly receiving a shade fabric varies roller tube rotational speed for constant linear shade speed. The desired linear shade speed, roller tube diameter and shade fabric thickness and length are stored in a memory for use by a microprocessor. Preferably, the roller tube rotational speed is varied by the microprocessor depending on shade position determined by signals from Hall effect sensors. The microprocessor maintains a counter number that is increased or decreased depending on direction of rotation. Based on the counter number, the microprocessor determines shade position and a corrected rotational speed for the desired linear shade speed. Preferably, the microprocessor controls roller tube rotational speed using a pulse width modulated signal. The system may be used to control first and second roller shades having roller tubes of differing diameters or shade fabrics of varying thicknesses.
摘要:
A system for controlling a roller shade having a roller tube windingly receiving a shade fabric varies roller tube rotational speed for constant linear shade speed. The desired linear shade speed, roller tube diameter and shade fabric thickness and length are stored in a memory for use by a microprocessor. Preferably, the roller tube rotational speed is varied by the microprocessor depending on shade position determined by signals from Hall effect sensors. The microprocessor maintains a counter number that is increased or decreased depending on direction of rotation. Based on the counter number, the microprocessor determines shade position and a corrected rotational speed for the desired linear shade speed. Preferably, the microprocessor controls roller tube rotational speed using a pulse width modulated signal. The system may be used to control first and second roller shades having roller tubes of differing diameters or shade fabrics of varying thicknesses.
摘要:
An insert having a peripheral contact surface is received by a roller tube channel to engage a shade fabric. The insert is adjustable to compress the shade fabric within the channel. The insert may include a body having opposite side edges and at least one elongated slot. The insert member may include pivotable prongs or deflectable slot walls adjacent the slots. Pivoting of the prongs or deflection of the slot walls urges the body toward a channel side wall to compress the shade fabric. The insert may, alternatively, include a body having diametrically opposite portions respectively defining a curved outer periphery and a planar outer periphery, the body being wider between the curved portions. The insert is pivotable about an axis to grip the shade fabric between a channel side wall and one of the curved portions of the body.
摘要:
A diffuser adapted to regulate air flow from an underfloor air distribution system. A grille sits on a dust receptacle or basket-shaped housing that is supported by a mounting assembly in the floor. A flow regulator or damper nests inside the housing. Both the housing and the flow regulator have air slots extending through their side walls. Air from the underfloor air plenum passes through these slots into the diffuser and is forced through helical slots in the grille into the room above the diffuser. The air flow rate can be adjusted by rotating the flow regulator within the housing so that the slots in the flow regulator are either in or out of registry with the slots in the housing. The flow regulator can be rotated by turning the grille. The grille and mounting assembly have indicators that give a visual indication of the position of the flow regulator with respect to the housing, the opening of the slots, and the flow rate through the diffuser.
摘要:
A biasing circuit for a power amplifier, for use in a transmitter, that substantially reduces distortion during key-up and thereby reduces key-up time. The power amplifier includes an output transistor and a bias circuit. The bias circuit is applied to all the class AB stages of the power amplifier. The bias circuit provides to the output transistor a first bias level during the preheat period and a second bias level during the transmit period. This first bias level is predetermined to cause the output transistor to reach the steady-state junction temperature achieved by the output transistor during the transmit period (i.e., when transmitting output signals biased with the second bias level). The preheat period ends when this steady-state temperature is reached. Thus, the power amplifier can then transition to a transmit period having already reached the steady-state junction temperature. Because the output transistor is already heated to the steady-state junction temperature, "thermal" distortion (i.e., the distortion incurred when the output transistor's junction temperature changes while transmitting) is avoided and the key-up time is reduced.
摘要:
A load bearing apparatus is configured to simulate a payload. The load bearing apparatus includes a load member configured to simulate the mass of a payload, a frame having frame members, a plurality of retainers configured to support the load member, and first and second outer guides coupled to the load member. The plurality of retainers includes a first retainer positioned at a first height and configured to support the load member at the first height, and a second retainer positioned at a second height different from the first height and configured to support the load member at the second height. The first and second outer guides are coupled to the load member and are configured to receive therebetween at least one lifting member of a lifting device. By using load members of different weights and positioning them at varying heights, different centers of gravity can be achieved.
摘要:
A coupling assembly for a multiple-tube roller shade includes a support assembly for rotatably supporting and connecting adjacently located tube-end portions and a clutch mechanism providing relative rotation therebetween. The support assembly includes a tube-end fitting and a torque-transferring drive transfer member contacting the tube. The clutch mechanism includes first and second clutch members respectively engaged and separated in closed and opened positions. A pull bar is translatable within one of the shafts and is moved by a draw pin received in aligned openings of the second clutch member, the shaft and the pull bar. The shaft openings are elongated for movement of the second clutch member between the closed and opened positions. An adjustment member threadedly engages the tube-end fitting for vertical adjustment of the fitting with respect to a support panel. The tube-end fitting is secured to a bracket having elongated openings for horizontal adjustment.
摘要:
An input radio frequency signal to be amplified is fed to the gate terminals of parallel field effect power transistors through impedance matching networks that comprise parallel resistor-capacitor combinations. The capacitor is selected so that it is self-resonant at the frequency of operation, thereby preventing attenuation of the input signal at that frequency. A shunt resistor is coupled between the gates of the parallel transistors to eliminate odd mode oscillations.