Abstract: This magnetic voice-coil shutter drive actuation system for an optical shutter having an aperture with at least one shutter blade includes an actuator operating to open/close the shutter blade when moved in opposing directions, and a moveable element that operates said actuator and can be a moveable voice coil or a moveable permanent magnet. The voice coil is activatable to generate an electromagnetic flux in opposing polar orientations to react against the magnetic flux produced by the permanent magnet. The moveable element can be located in a position peripheral of the aperture and not surrounding the aperture, or in a position peripheral of the aperture and surrounding the aperture. The magnetic flux produced by the permanent magnet and the electromagnetic flux produced by the voice coil define magnetic axes that are parallel to each other and to a central axis for the aperture.

Abstract: This magnetic voice-coil shutter drive actuation system for an optical shutter having an aperture with at least one shutter blade includes an actuator operating to open/close the shutter blade when moved in opposing directions, and a moveable element that operates said actuator and can be a moveable voice coil or a moveable permanent magnet. The voice coil is activatable to generate an electromagnetic flux in opposing polar orientations to react against the magnetic flux produced by the permanent magnet. The moveable element can be located in a position peripheral of the aperture and not surrounding the aperture, or in a position peripheral of the aperture and surrounding the aperture. The magnetic flux produced by the permanent magnet and the electromagnetic flux produced by the voice coil define magnetic axes that are parallel to each other and to a central axis for the aperture.

Abstract: In order to stress relieve exposed portions of plastic welds, and thereby reduce susceptibility of such welds to solvent-induced crazing and cracking, the welded parts are formed with flanges extending outwardly therefrom. These flanges are at least partially joined during welding, their adjoining surfaces providing at least a portion of the welded joint. After welding, the flanges are compressed in a direction transverse to their adjoining welded surfaces, the compression being of sufficient magnitude to exceed the yield strength of the flanges, thereby relieving stresses in the exposed portion of the welds. The flanges may be sheared, as by a blade which provides both transverse compressive forces and compressive forces in the direction of the adjoining welded surfaces. The flanges may be sheared through, so as to enable the sheared off end to be removed, or the shearing may penetrate only through the weld zone, providing a notch, but leaving the flanges in place.

Abstract: In order to stress relieve exposed portions of plastic welds, and thereby reduce susceptability of such welds to solvent-induced crazing and cracking, the welded parts are formed with flanges extending outwardly therefrom. These flanges are at least partially joined during welding, their adjoining surfaces providing at least a portion of the welded joint. After welding, the flanges are compressed in a direction transverse to their adjoining welded surfaces, the compression being of sufficient magnitude to exceed the yield strength of the flanges, thereby relieving stresses in the exposed portion of the welds. The flanges may be sheared, as by a blade which provides both transverse compressive forces and compressive forces in the direction of the adjoining welded surfaces. The flanges may be sheared through, so as to enable the sheared off end to be removed, or the shearing may penetrate only through the weld zone, providing a notch, but leaving the flanges in place.

Abstract: To relieve stresses in a plastic weld which may weaken the weld and increase its susceptibility to solvent-induced crazing or cracking, forces are applied to the weld zone (the interface between welded parts) after it has cooled to solid condition, but preferably when it is at a higher temperature than the regions of the parts adjacent thereto, which forces are higher than the yield strength of the material at the weld zone and lower than the yield strength of the material in the regions of the parts adjacent to the weld zone. The forces thereby cause yielding or plastic deformation which effectively relieves certain thermally induced stresses in the weld. Tensile stresses in the weld are thereby relieved, to reduce susceptibility of the weld to solvent-induced crazing or cracking.

Abstract: Joints between thermoplastic parts are friction welded (e.g., as by vibration welding) or otherwise thermally welded in such a manner that a non-uniform temperature distribution results during welding which effectively blocks flash flow from the edge of the joint, and upon cooling, produces a joint that is at least partially stress relieved and is resistant to solvent-induced crazing and cracking. Joints may employ nonparallel adjoining surfaces and/or flexural lips, which bend slightly under pressure applied during welding so as to produce a non-uniform pressure distribution and nonparallel welding surface over at least a portion of the resulting weld near the outside edge. In addition, one or more axial grooves may be used to isolate the nonparallel or lipped area of the weld from the remainder of the weld area so as to increase the lip compliance and reduce the effective pressure of molten material acting on the lip during welding.