An input system for an electrical machine including a mechanism for connection between each key and a shutter therefor in the keyboard of the console of the machine. The shutter interrupts light from one or more sources to one or more photocells to provide a coded input for the machine. The shutter of each key is moved by the mechanism by a snap action to avoid the need for interlocked keys. Simultaneous inputs from two keys are avoided because the shutter is moved by the mechanism at a substantially greater rate than it is possible to actuate a key manually.
The invention relates to a novel hinge arrangement, which is particularly useful in shelving units, and to shelving units employing such a hinging arrangement. The shelving unit includes a fixed wall and a shelf part, and the top edge of the fixed wall is contiguous to the bottom edge of the shelf. The right and left hand edges of the fixed wall and the shelf are respectively pivotally connected by right and left hand hinge arrangements. Each of the hinge arrangements includes a base member, connected to a respective edge of the fixed wall, and a swivelling member, connected to a respective edge of the shelf. Connecting members are provided to pivotally connect each base member with its respective swivelling member, so that the shelf is pivotable relative to the fixed wall.
An optically coded keyboard arrangement has a plurality of key units arranged to be individually actuated; an actuation sensing arrangement that includes a plurality of light emitters generating light beams and a plurality of detectors each placed in the path of a respective light beam. Each key unit includes a key arranged to be depressed and a coded mask coupled to the key for movement with the key in unison upon displacement of the key and for movement relative to the key in a direction transverse to the path of motion of the key. Each key unit further has a switching spring which, in the position of rest of the associated key has an arcuate shape bulging in one direction and engages at one end a countersupport. As the key is depressed, the switching spring is deformed into a more bulging shape, carrying the mask into a position where it is ready to interrupt the light beams. Upon continuing movement of the key by virtue of the depressing force, a cam causes the tensioned switching spring to jump off the countersupport, whereupon the spring, as it assumes a released state, rapidly moves the mask into the light beam paths.
In a key-operated machine in which actuation of a key moves code elements of an associated code card into the path of a photoelectric sensing system, each code card is moved by a drive mechanism so as to cause the code elements to traverse the sensing system path only once, and at a speed which is independent of the speed of key movement, in response to each key actuation.
