Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
2001-05-22
2003-08-05
Lao, Lun-Yi (Department: 2673)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S903000, C040S449000, C340S815620
Reexamination Certificate
active
06603458
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The invention relates to an electromagnetic display device, comprising a panel which consists of a number of substantially square pixels which are divided into two parts. Each pixel is provided with a rotatably mounted bistable tilting flap, which is asymmetrical in relation to its rotational axis. Said tilting flap covers one of the two portions of the panel surface in the pixel zone when the flap lies in each of its two stable positions. The side of the tilting flap facing the front side of the panel and the portion of the panel in the pixel zone which is covered by the tilting flap in this position has a first colour and the other side of the tilting flap and the other portion of the panel in the pixel zone has a second colour. A permanent magnet is fitted to the tilting flap in close proximity to the rotational axis. The tilting flap is displaced from a first position into a second position by an electromagnet which is located on the reverse side of the panel and is allocated to the pixels, and which has a coil body, with coil head and coil base, and core.
2. Description of the Prior Art
Electromagnetic display devices of this kind are used for the construction of display boards, in which tie displayed information can be changed, that is to say exchanged or adapted, in a simple manner. To this end, the display board comprises a multiplicity of individual picture elements, the pixels, which are arranged in the form of a matrix and can be switched back and forth between two different states, such that they appear, for example, in a light or dark colour. These pixels may be used to compose any appropriate letters, numerals or other characters, a matrix comprising seven cells of five pixels each being sufficient for the display of most characters.
Patent specifications DE 35 01 912 C2 and DE 36 01 018 C2 disclose an electromagnetic display device of this generic type which consists of a matrix of square pixels arranged on a panel, each pixel being equipped with a bistable tilting flap which is rotatably mounted in two bearing brackets and is in the form of a right-angled triangle, the rotational axis being congruent with the hypotenuse of the triangle. In both of its stable positions, the tilting flap covers one half in each case of that portion of the panel associated with the square pixel, the respective visible portions of the panel and tilting flap being coloured uniformly, and differently for the two positions of the tilting flap, for example black and white. The changeover between the two display states of the pixel is carried out by means of an electromagnet arranged below the pixel, which comprises a coil body and pin-shaped core, and the tilting flap equipped with a permanent magnet tilting back and forth between the two positions on the application of a corresponding voltage. This construction of the individual pixel allows almost complete utilization of the display surface, with virtually no interspaces, by the picture elements, which are only somewhat impaired by the recesses required in the vicinity of the bearing brackets. The result of this good area filling is good legibility of the letters, numerals and other characters represented by means of the display device, provided that they are sufficiently illuminated by daylight or artificial light. At poorly illuminated places or in darkness, on the other hand, this type of display can only be used in conjunction with an additional light source, which lights up its front surface.
Patent specification EP 0 401 980 B1 describes a display device that can also be read in darkness and whose individual pixels each consists of a circular disc, which has a radially extending slit and is rotatably mounted on the rotational axis extending perpendicular to the slit on the diameter of the circular disc. The circular disc can be rotated through an angle of about 180° between two stops by means of a permanent magnet located next to said circular disc on the rotational axis and an electromagnet arranged behind said permanent magnet. As a consequence, in one position the light-coloured front side of the circular disc is directed towards the observer and the end of a fibre-optic light guide in the slit becomes visible, whereas in the other position the dark side of the circular disc faces forwards and covers the fibre-optic light guide. Patent specification EP 0 463 725 B1 discloses a similarly constructed display device, in which the circular disc is only rotated through 90°, so that, in one position, the light-coloured front side and, in the other position, the dark edge of the circular disc, faces forwards. The light sources used to illuminate the pixel, in particular light-emitting diodes, are, in the first position of the pixel, visible through a circular opening in the circular disc and, with the changeover of the pixel, are disconnected by means of a reed contact.
The last-mentioned display devices possess, by virtue of the light-coloured sources integrated into the pixel, the advantage that they can also be operated and read in darkness. However, this is countered by the disadvantage that the portions of the pixel used for the display are circular and, because of the electromagnetic display device arranged next to the circular disc, are spaced from one another. This results in a comparatively small area density and therefore an impairment of the legibility of these display devices. In addition, in the case of circular pixels, the discs, at least in one of their switching states, are not disposed parallel to the display plane, so that the pixel has a different appearance when observed from different directions. A particular disadvantage of pixels formed as circular discs can be seen in the fact that the light source is usually arranged behind the disc, which leads to partial attenuation of the emitted light and significantly impairs the legibility of the corresponding display device from the side.
SUMMARY OF THE INVENTION
On this basis, it is the object of the present invention to provide an electromagnetic display device that ensures good legibility of the information presented both under light conditions and in darkness.
This object is achieved according to the present invention in that the display device has a base plate, the coil base of the electromagnet is inserted in the base plate, the coil head is attached to the panel, each pixel is provided with an opening in the panel and a pin, which is located on said base plate and is directed towards said opening, and on which a light-emitting diode is mounted, is allocated to each pixel.
The present invention is based on the idea of forming the electromagnetic display device with pixels that are readily legible in daylight and are switchable back and forth by means of bistable tilting flaps between two colours, for example a light colour such as white or yellow, which may be embodied as a reflective film, and a dark colour such as black, and by providing each pixel with at least one light-emitting diode (LED), which is preferably arranged in the light-coloured region and promotes the legibility of the display device in failing light and ensures good legibility even in darkness. To this end the electromagnetic display device is to be provided with square pixels, which are switchable between two colours, preferably a light and a dark colour, by means of bistable tilting flaps, which assume one of two possible positions on the pixel depending on the switching state. For their movement, the tilting flaps are fitted, in close proximity to their rotational axis, with a permanent magnet which, depending on the position of the tilting flap, is arranged with either its north or south pole in the direction of the electromagnet, which is arranged on the reverse side of the panel, is allocated to the respective pixel and comprises a coil body and a pin-shaped core, which is introduced into said coil body and composed of electromagnetically soft or retentive material. The use of a retentive material here has the advantage th
Fischer Helmut
Kögler Wolfgang
Pongratz Rudolf
Annex Anzeignsysteme GmbH
Lao Lun-Yi
Schindler Edwin D.
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