Abstract: An injection molding process for molding an assembly of a frontcurve molds in a plurality of unitary solid piece of polymer in which plurality of frontcurve molds are arranged symmetrically around a single center polymer injection gate. In this arrangement the molten polymer flows radially outwardly therefrom uniformly in all directions to the four frontcurves to form one common molded piece of polymer. In a compression injection molding process, the pressure on the molten polymer is maintained relatively constant, and the mold is mechanically collapsed during the molding operation. The present invention molds an assembly of frontcurve molds in a manner in which there is a significant reduction of residual stress locked into the resultant assembly of frontcurve molds. This results in a significant reduction in warpage and shrinkage of each frontcurve mold, which is not optically stressed, and results in a subsequent casting of an ophthalmic lens which is not optically stressed.

Abstract: An electric motor controller comprises a circuit for selecting between driving and braking an electric motor in accordance with the health or otherwise of a pair of main electric motor control switches (14 and 16). In a preferred embodiment the health of the switch is determined by the voltage (A) between the switches. The controller also comprises apparatus for detecting the sense of movement of the motor. In the event that the motor is moving in a sense opposite to that selected, the apparatus increase field current to reduce the armature current thereby increasing the braking effect of the motor. Also in the controller are apparatus for changing from armature to field current control and vice versa, in response to a given magnitude of control signal. In order to provide an unambiguous change-over, a lockout circuit is provided to inhibit change-over in a transition region. The lockout circuit maintains the mode of control to above/beneath the change-over level when changing from one level to another.

Abstract: An electric motor controller comprises a circuit for selecting between driving and braking an electric motor in accordance with the health or otherwise of a pair of main electric motor control switches (14 and 16). In a preferred embodiment the health of the switch is determined by the voltage (A) between the switches. The controller also comprises apparatus for detecting the sense of movement of the motor. In the event that the motor is moving in a sense opposite to that selected, the apparatus increase field current to reduce the armature current thereby increasing the braking effect of the motor. Also in the controller are apparatus for changing from armature to field current control and vice versa, in response to a given magnitude of control signal. In order to provide an unambiguous change-over, a lockout circuit is provided to inhibit change-over in a transition region. The lockout circuit maintains the mode of control to above/beneath the change-over level when changing from one level to another.