DE3031179A1 - Fluorescent activated segment display - has display plate of transparent carrier with suspended fluorescing particles - Google Patents

Abstract

A fluorescent activated display element is designed without the use of liquid or gaseous components. A seven segment numerical display element has a fluorescent plate (1) that is formed from a transparent material with a refractive index that is greater than unity, e.g polymethylmethacrylate. The plate contains particles of a fluorescent substance. The outer edges (3) are covered with a reflective coating. Within the element are segment electrodes (4) in contact with a polymer layer (6), back electrodes (7), a reflecting layer (8) and a carrier plate (9). Contact elements (11) are located between the display segment electrodes (4) and the fluorescent plate (1).

Description

Display device

Addendum to patent .... (patent application P 29 10952.2) of the main patent includes a display device according to the preamble of the claim 1.

Such a device provides bright, high-contrast images because the The display works without polarizers and the fluorescent body has a large collecting surface Has. The good optical qualities must, however, involve a certain amount of manufacturing effort to be bought; For example, one cannot avoid a complete in itself Use liquid crystal display. It would be ideal if the display device would only consist of fixed parts, because then it could be designed and rationalized would in particular no longer require any sealing or distancing work.

The invention is based on the object of the display device Type mentioned at the beginning within the scope of the principle of solution specified in the main patent to be further developed in such a way that it is free of liquid or gaseous components. For this purpose, a display device with the features of claim 1 suggested.

Liquid-crystalline polymers are already known per se; compare to this for example Makromol. Chem.

180 (1979) 803, in which homo- or copolymers with electrically switchable, mesogenic side groups are investigated, or Polym. Prep. At the. Chem.

Soc. Div. Polym. Chem. 19 (1978) 190. So far were these Compounds mainly because they have the liquid crystal structure retained ("freeze") and due to Due to their good deformability, they can easily be processed into layers, films or fibers let (DE-OS 27 22 589 or DE-OS 28 31 909). On the idea of using the polymer enrich with a dichroic dye and act as a light valve of a so-called.

To use fluorescence-activated displays (FLAD) "is not yet possible came.

Advantageous refinements and developments of the proposed solution are characterized in the claims.

The invention will now be based on a preferred embodiment will be explained in more detail in connection with the accompanying figure.

The figure shows a schematic side section Display device for seven-segment numbers. The device contains a fluorescent plate 1 and, in the viewing direction behind it, a display 2. The fluorescent plate consists of polymethyl methacrylate in which the fluorescent dye Cumn6 is dissolved is. The four narrow sides of the plate carry a specular or diffuse reflective Layer 3. The display includes one of several independent segment electrodes 4 existing front electrode, one enriched with a pleochroic dye Polymer layer 6, a continuous back electrode 7, a diffusely scattering reflection layer 8 and a carrier plate 9. Between the segment electrodes and the Fluorescent plate are each inserted transparent Kontitschichten 11, which due to Their suitably chosen refractive index ensures optical contact between the polymer layer and prepare the fluorescent plate.

The polymer layer is designed as follows.

The matrix for the dye usually consists of either main chains, to which mesogenic units are coupled via flexible bridges, or from components the form -flexible bridge mesogenic unit which is formed by polymerizing the bridges with each other are linked. A copolymerization of the bridges with others would also be conceivable olefinically unsaturated compounds.

The dye molecules can be in the polymer matrix in different Wisely introduced - in one extreme, they are mesogenic instead of some Units are chemically bound to the flexible bridges and in the other extreme case are they are physically dissolved, i.e. embedded between the mesogenic units. as In principle, dyes are all compounds that have already been considered Liquid crystal additive had provided, for example anthraquinones or azo dyes.

If the polymer consists of main and side chains, the individual ones are They usually share with one another via chemical functions capable of addition or condensation tied together. If the polymer was created by linking the bridges, it runs the polymerization of the bridges over polymerizable, preferably olefinic unsaturated chemical functions at the bridge ends.

Further details on the structure and manufacture of the polymer layer can of the patent application filed on July 21, 1980 and entitled "Liquid Crystal Display with an orienting and polarizing layer.

The switchable PolymXer components are as follows in the illustrated embodiment oriented: in the field-free state they have a uniform preferred direction parallel to the layer plane, and when a sufficiently high voltage is applied to the electrodes they rotate perpendicular to the layer plane. The initial texture is obtained, for example in that the polymer layer is rubbed or directed in the same way before it solidifies - for example in a dipping technique - applies.

The display device works as follows: The fluorescent plate collects part of the ambient light incident on its front Fluorescence scattering and subsequent (total) reflections at their interfaces and conducts the fluorescent light inside until it passes through one of the contact layers is decoupled to the rear. Is the one behind the contact layer Polymer in its off-state, so is only affected by the incident fluorescent light a small amount returned to the fluorescent plate; because the fluorescent ones Particles emit unpolarized light and a diffuse reflector scatters linearly polarized light largely unpolarized back, so that the fluorescence radiation on their way there and back through the linearly polarizing polymer layer 3 each time is weakened by about half. If, on the other hand, the polymer is activated, it will Fluorescent light is reflected into the plate with almost no loss. In both switching states Incidentally, the scattered light returning to the fluorescent plate can affect the display device forward leave because a diffuse reflector prefers in directions backscatters perpendicular to its plane of extension. This scattering characteristic is it is even more pronounced when one sees the reflector from the layers in front of it optically decoupled.

The result is a brightly shining one in the fluorescent color Image against a dark background toned in the fluorescent color; can the background area outside of the display elements still has nuances from the straight ones display elements that are not switched on differ. This little bug bothers me generally not and, moreover, could easily be eliminated if necessary. So For example, if you had the option already mentioned in the main patent, the remaining area to be deposited with a colored foil; or you could leave the polymer layer at rest orient it so that it absorbs even more strongly (cf. Makromol. Chem. Rapid.

Commun. 1 (1980), where also polymers with a cholesteric texture to be discribed).

The invention is not limited to the exemplary embodiment shown. In this way, the polymer layer could also be switched between other states of order will; useful results can be expected with a polymer that is produced by a homeotropic switched to a (uniformly) homogeneous or cholesteric state and contains dye molecules that parallel light with a direction of propagation let pass without weakening to its longitudinal axis and perpendicular to its longitudinal axis absorb progressive light. That being said, there is also constructive Considerable leeway.

For example, the person skilled in the art is free to use the polymer layer only to cover the display elements and between the display and the fluorescent body large area make optical contact; in the latter case However, care must be taken to ensure that the fluorescent light is only applied to the areas intended for it Places can escape from the device.

Claims (5)

Claims 1 display device with a preferably plate-like Body ("fluorescent body"), which consists of a transparent carrier material with a Refractive index greater than 1 and contains fluorescent particles, and with a in the direction of view behind the liquid crystal display, which has a front electrode, a back electrode, a liquid crystal layer located between the two electrodes with a pleochroic dye and one behind the liquid crystal layer arranged reflector, the liquid crystal layer at least those Covers areas in which the front electrode and the rear electrode are opposite each other, (Display elements) and the front electrode the fluorescent body at least in the area of the display elements optically contacted, according to patent ....... ........... (patent application P 29 10 952.2), d a d u r c h g e k It is noted that the reflector (8) scatters diffusely and the liquid crystal layer is a solid state polymer (polymer layer 6). 2. Apparatus according to claim 1, d a d u r c h g e k e n n z e i c n e t that the polymer layer (6) consists of main chains with mesogenic side chains, which are linked to the main chain via flexible bridges. 3. Apparatus according to claim 1 or 2, d a d u r c h g e k e n n z e i c h n e t that the dye is dissolved in the polymer layer (6), the Dye molecules are embedded between the mesogenic side chains. 4. Apparatus according to claim 1 or 2, d a d u r c h g e k e n n z e i c h n e t that the dye is chemically bound in the polymer layer (6), some of the meso gene side chains are replaced by dye molecules. 5. Device according to one of claims 2 to 4, d a d u r c h g e it does not indicate that the measured side chains are in the two switching states are uniformly homogeneously or homeotropically oriented.