A switch having two apertured plates one of which is movable relative to the other to occupy spaced switch positions, the apertures being arranged in the plates so that in each switch position two or more pairs of apertures are aligned and all others are masked, wherein light transmitted through a selected one of the two or more aligned aperture pairs in a particular switch position is visible through an external switch position indicating window to thereby provide an unambiguous indication that the movable plate is positively registered in the particular switch position.

FIELD OF THE INVENTION

The present invention relates to a trustworthy optomechanical switch.

BACKGROUND OF THE INVENTION

A “trustworthy switch” is one which is capable of providing an unambiguous indication that it is in a particular switch position. Based on its unambiguous indication of switch position, the trustworthy switch can be used to selectively switch between nodes of a system with a high degree of confidence that spurious switching or crosstalk will be prevented. Trustworthy switches are critical in information, communication and control systems where positive, unambiguous switching is required for efficacy, security and safety.

A need exists for a simple, generic optomechanical switch capable of providing unambiguous indications of its switch positions.

SUMMARY OF THE INVENTION

According to the present invention, there is provided a switch having two apertured plates one of which is movable relative to the other to occupy spaced switch positions, the apertures being arranged in the plates so that in each switch position two or more pairs of apertures are aligned and all others are masked, wherein light transmitted through a selected one of the two or more aligned aperture pairs in a particular switch position is visible through an external switch position indicating window to thereby provide an unambiguous indication that the movable plate is positively registered in the particular switch position.

Light can be transmitted to and from aligned aperture pairs via optical fibres.

The other aligned aperture pairs in the particular switch position can respectively transmit light among optically-interfaced nodes of a system. The switch can be enclosed in a cabinet having a frame with a stack of drawers each housing a node of the system. The drawers can be electromagnetically shielded from one another to prevent or minimise crosstalk between the nodes. The system can be selected from an information system, a communication system, a control system, and combinations thereof. The system can include more than one switch.

The switch can further include a manual position selector operatively connected to a servo motor to electromechanically actuate the movable plate to selectively occupy the switch positions. The manual position selector can have manually selectable positions corresponding to the internal switch positions and the external switch position indicating windows.

Three or more pairs of apertures can be aligned in each switch position, wherein light transmitted through a second selected aligned aperture pair in a particular switch position provides a feedback control signal to the servo motor that the movable plate is positively registered in the particular switch position.

Four or more pairs of apertures can be aligned in each switch position, wherein light transmitted through a third selected aligned aperture pair in a particular switch position allows monitoring or logging of the particular switch position.

The apertured plates can be rectilinear or circular, and the movement of one relative to the other can be linear movement or rotary movement.

The apertured plates can be disposed closely adjacent each other whereby their close adjacency prevents optical leakage from aligned aperture pairs. The switch can be enclosed in a security housing which prevents or resists tampering with its optomechanical components.

DETAILED DESCRIPTION

FIG. 1illustrates an optomechanical switch100having two closely, adjacent apertured plates102,104. Plate104is slidably movable relative to the other plate102to occupy four spaced switch positions A, B, C, D. Light is transmitted to and from the apertures of the plates102,104via optical fibres106. The switch100further includes a manual position selector108operatively connected to a servo motor (not shown) to electromechanically actuate the movable plate104to selectively occupy the switch positions A, B, C, D. The movable plate is positively guided between the switch positions A, B, C, D by guide rails110. The manual position selector108has four manually selectable positions corresponding to the four internal switch positions A, B, C, D and four external switch position indicating windows112.

Referring toFIGS. 2 to 4, the apertures are arranged in the plates102,104so that in each switch position A, B, C, D eight pairs of apertures are aligned and all others are masked. As illustrated inFIG. 2, each switch position A, B, C, D is defined by four staggered, repeating pairs of upper and lower apertures in the fixed plate102. In a particular switch position, for example switch position A illustrated inFIG. 4, light from a light source (not shown) is transmitted through a selected pair of the eight aligned aperture pairs and to the corresponding switch position indicating window112via an optical fibre106to thereby provide an unambiguous visible indication that the movable plate104is positively registered in the particular switch position. Light is respectively transmitted through another two aligned aperture pairs to provide feedback to the servo motor that the movable plate104is positively registered in the particular switch position, and to allow monitoring or logging of the particular switch position. The remaining five of the eight aligned aperture pairs in the particular switch position respectively transmit light among optically-interfaced nodes of a system (not shown) via optical fibres106. The apertured plates102,104can be disposed closely adjacent each other inside a security housing (not shown). The close adjacency of the apertured plates102,104prevents optical leakage from aligned aperture pairs, while the security housing prevents or resists tampering with the optomechanical components of the switch100.

Referring toFIGS. 5 and 6, the switch100can be enclosed in a cabinet200having a frame202with a stack of drawers204each housing a node of the system. The drawers204can be electromagnetically shielded from one another to prevent or minimise crosstalk between the nodes. The switch100is optically interfaced to the nodes via optical fibres106received in the shielded drawers204without causing appreciable electromagnetic leakage therefrom. The optical fibres106are reticulated via a vertical space at the back of the cabinet200along with the power supply (not shown) for the components. The frame202is enclosed by a front panel206and a cover208having top and side walls.

The switch100and the cabinet200can be implemented in a system where positive, unambiguous switching between system nodes is critical for efficacy, security or safety. The system can be selected from an information system, a communication system, a control system, and combinations thereof. The system can include more than one switch100or more than one cabinet200. For example, the switch100and the cabinet200can be implemented in a multi-processor information system to positively and unambiguously switch between processor-level nodes having mutually different permission levels or security classifications.

Embodiments of the present invention provide a simple, generic trustworthy optomechanical switch that is capable of providing an unambiguous indication of its switching position. Such a switch can be advantageously used in any and all conventional information, communication and control systems where positive, unambiguous switching is critical for efficacy, security and safety.

Obviously, many other modifications and variations of the present invention are possible in light of the above description. For example, the apertured plates are not limited to rectilinear plates having linear relative movement, but can be alternatively implemented as circular plates wherein the movement of one relative to the other is rotary movement. It is to be understood, therefore, that the invention is not limited in its application to the details of construction and arrangement of parts specifically described or illustrated, and that within the scope of the appended claims, it may be practised otherwise than as specifically described or illustrated.