Abstract: The invention provides a display matrix system using display elements of the electromagnetic type. The system differs from others in that the currents applied to the display elements are unidirectional as there are no electrical switching components per element. This reduces the drive circuitry needed for the matrix. Selection of the display elements relies on current pulses of variable width.In accordance with an aspect of the invention each one of a row or column of coils are connected together by N conductors, such that it is only necessary to drive 1/N of the coils in a row or column at a time:In accordance with a further aspect of the invention means are provided which enable variation in the electrical pulse width applied to a display element in response to variation of one of ambient temperature and supply voltage.

Abstract: A matrix display of the back-illiminated electromechanical type has enhanced picture display features by including display elements whose brightness is individually adjustable.In one arrangement, each display element has an aperture and an opaque shutter selectively settable to each one of at least three stable positions. In one position, the shutter covers the aperture completely, and in the other positions, it uncovers the aperture to a differing extent so as to pass light of differing intensity depending on the position.The activating mechanism for the matrix display is a moving head having two magnetic actuators arranged side-by-side for each row of display elements. One magnetic actuator serves to accelerate the shutter of a selected display element, and the other applies a braking force to halt the shutter in the desired position so as to control the brightness of the display element.By providing a group (e.g.

Abstract: A matrix display device includes an array of display elements each comprising a member (12) rotatable between two states and an array of bearing elements (13) associated with said rotatable members manufactured as a single piece, such as a frame (11).This allows an improved method of manufacture of such display devices in that a matrix sheet (1) having display apertures (2) and bearing members (3) is produced with spacing such that the frame (11) of display element members (12) aligns with the matrix sheet and the respective bearing elements (13) and members (3) can interengage simultaneously, resulting in saving of time and simplification of the assembly procedure. Once interengaged, the residual parts of the frame (11) are severed and discarded. Matrix sheet (1) is also made as a single piece, enabling a whole matrix of hinged display elements to be made from only two or three parts.

Abstract: A stationary matrix panel has magnetic display elements arranged in vertical and horizontal rows, each element having two stable states of contrasting appearance. Electromagnetic actuator heads are mechanically coupled together by resilient couplings so as to move in unison and actuate selected display elements. The couplings are arranged to allow limited movement in a direction normal to that of the travel of the actuator heads across the matrix panel, thereby allowing for slight misalignment in the panel. Each actuator head contains a number of individual electromagnets and is responsive to a respective indexing track which provides signals indicative of the actual position of the actuation of the electromagnets in the head. The matrix panel has a plurality of guide rails arranged to provide accurate vertical registration of the heads, each guide rail being slotted to provide the indexing.

Abstract: A tooth cleaning instrument mounted at one end of a handle comprising a tapered blade of plastics material having a blunt apex folded about a base to apex line and inclined to the axis of the handle, the arrangement allowing all outer surfaces of the teeth as well as the spaces between them to be scraped to remove plaque and tartar. The other end of the handle can include a brush.

Abstract: An improved matrix display device is disclosed which includes a display matrix assembly having electromechanical display elements in horizontal rows and vertical columns. The assembly has two support portions extending the width of the assembly, one portion being at the top and the other being at the bottom. A rail member extends along the width of the matrix and is arranged to guide a movable electromagnetic head device. A series of hooks attach the rail member to one of the support portions at locations in the portion having a defined distance relative to each row of the matrix, thereby ensuring that the electromagnetic head device moves in registration with the rows of the matrix. A degree of resilience is included in the display device so as to apply tension between the support portions thereby maintaining the matrix assembly substantially flat. It is therefore unnecessary for the assembly to be made completely rigid, e.g. by including a sheet of glass, and the assembly may be left relatively flexible.

Abstract: A matrix display comprises an array of display elements arranged in vertical and horizontal rows. Each element comprises a vane pivotally mounted for movement between stable positions in one of which the vane covers a light-transmissive area contained in an opaque member arranged to be illuminated from behind by a first light source and displays a low-reflectance face to an observer. In a second stable position the vane exposes the illuminated area to the observer and also reflects light from a second source towards the observer, for which purpose the vane may be supported at an acute angle to the opaque member. Each vane is fastened to a permanent magnet arranged to cooperate with a reversibly polarizable electromagnet to be moved from one stable position to the other. In one embodiment an array of electromagnets, one for each horizontal or vertical row of shutters, is traversed across the array and the electromagnets are individually selectively energized to produce a required display.