SI21767A - Illumination of the electromagnetic display panels - Google Patents

Abstract

A new concept of illumination of the electromagnetic display panels is described using invisible UV light illumination of the display panels into low ambient light conditions. Such a solution is possible, if one uses UV fluorescent dyes in the paints or plastic material for the reflective surface of the selected pixel element instead of the regular reflective ones. The said dyes absorb the invisible near UV light and upon absorbing it reemit the light in the visible range. The described display panel illumination concept results in excellent contrast, as there is no visible light scattering from the background or protective display panel top covers, which in turn result in haze and glare. Furthermore unlike with electromagnetic display panels, using built-in light sources imbedded in ich pixel element (i.e.: LED,...), the appearance/perception of the display characters (shape, geometry) as well as angular visibility remain unchanged in the hihh as well as in low or "dark" ambient light conditions.

Description

Illumination of electromagnetic display panels

SUBJECT MATTER OF THE INVENTION

The object of the invention is the concept of illumination of the electromagnetic display panel, which greatly reduces / eliminates both the reflection of light from a dark background and the reflection of the display housing and emphasizes only light reflected from a bright luminescent surface on active display elements. The proposed illumination of the display panel is based on the use of a luminescent dye that absorbs light in the near UV part of the light spectrum and then emits it in the visible part. The advantage of the new concept is that the light used to illuminate the billboard is barely visible / invisible to human eyes, and therefore the reflection from inactive display elements, display housing and background surface is extremely low. This makes the display contrast extremely low in low light conditions. Since the light from the display elements is reflected in all directions, the lateral visibility of such display is excellent.

TECHNICAL FIELD OF THE INVENTION

The technical field of the invention is the illumination of large bistable electromagnetic display panels, which are used as displays on trains and buses or as large displays at airports, bus and train stations and sporting events in low light conditions. According to the International Patent Classification, this claim belongs to groups G09F 3/4 and G09F 9/37. Because the visibility and appearance of such display panels is of paramount importance, excellent lateral visibility, visual impression and high contrast of the display panel are essential.

TECHNICAL PROBLEM SOLVED BY THE INVENTION

A technical problem solved by the invention is the creation of a new, less expensive concept of illumination of the electromagnetic display, which provides excellent lateral visibility in poor light conditions and reduces the scattering of light on the housing and background, all of which increase the contrast of the display.

TECHNICAL SOLUTIONS Known So far

Electromagnetic display panels have been known for over two decades and play an important role in applications where a relatively large display with very contrasting inscription and excellent visibility under good light conditions is required. The bistable electromagnetic display panels (US 3,871,945, US 4,577,427, US 4,860,470, EP 0 084 959, EP 0 731 435 Al, ...) meet the above requirements. They are used to show bus and train distances, information display panels at airports, bus and train stations and at sports fields. In good light conditions, these displays have good contrast and excellent lateral visibility. This is achieved by using a light reflective color on the selected display elements (“ON” state) and a black matte color on the non-selected (“OFF” state) display elements.

Due to their excellent performance in the above-mentioned applications, their use becomes even more important in situations where lighting conditions are poor (poor outdoor lighting, night conditions, ...). However, the existing solutions in this area are not very good:

- Lighting the entire display panel with additional standard light sources, such as a fluorescent light, is a cost-effective, efficient and massively used solution. The main disadvantage of this is that it illuminates the entire display panel. In fact, the light coming from such a light source reflects off the housing, background, unselected display elements and transparent display protection (on trains and buses), which together results in poor contrast of the displayed content of the caption.

- In most cases, lighting solutions are based on the use of additional light sources in each display panel display element. So far, several technical solutions of this kind have been developed. Most use LEDs (US 5,050,325, WO 00/62274, DE 189 02 218 Al, EP 0 731 435 Al, ...) or other light sources (US 4,914,427, GB 2,297,185 A, US 5,642,130, ...) incorporated in display element directly or through optical fibers (US 5,055,832).

The general problem with all of these solutions is that the light sources must be integrated into the individual display elements so that the switch flap of one (US 6,603,458) or other (US 5,771,616) type can rotate and show a reflective color once (selected element - "ON" ) and second, a black matte finish (unselected "OFF"). The visibility of such a display panel using its own illumination source is significantly reduced when viewed at low light conditions when compared to normal light conditions. Another problem is that a light source embedded in each display element illuminates only a limited portion of the active surface. As a result, the visibility of individual characters in poor light conditions is greatly impaired.

Finally, it should be noted that the use of additional LEDs or other light sources in individual display elements is an expensive and energy-consuming solution.

The object of the invention solves the technical problem described above by using an external source of UV light instead of standard illumination. To take advantage of UV illumination, dyes with additives are used to absorb light in the near UV spectrum and then emit it in the visible part of the spectrum. These can be UV luminescent additives that can be used as a coating or are directly embedded in the plastic materials from which the active surfaces of the display elements are made.

Such colorants are already known and are used for various lighting effects (advertising, performances, ...). The use of such a concept in electromagnetic display panels, which are intended to eliminate the problem of glare and blur and thus improve display contrast, is unknown to date.

DESCRIPTION OF THE INVENTION

Electromagnetic displays are typically constructed from large arrays of predominantly square display elements with rotary flaps and integrated coils. The “ON” and “OFF” states of the display elements are highlighted in high contrast colors. By rotating the flap around a rotary axis with a magnetic field, any patterns can be formed. Magnetic control of the display elements provides memory properties that are critical to reducing power consumption to the required level.

The object of the invention is achieved by using illumination with a UV light source in the invisible part of the spectrum and the use of suitable UV fluorescent additives (in colors or in plastic material to produce reflective surfaces of selected display elements) instead of dyes that shine only visible light. These dyes absorb invisible light in the near UV part of the spectrum and emit light in the visible part of the spectrum (Fig. 1). Such a concept of illumination provides excellent contrast because there are no visible reflections from the background, inactive surfaces and display housing. Furthermore, unlike the displays with built-in light sources (eg LEDs), the visibility of the signs (shape, geometry) is unchanged in both very good and poor light conditions.

The main advantage of using a light source in the near UV part of the spectrum ("black light") is not only the very intense color of the active surfaces (-all bright, primitively illuminated color has a similar effect), but that there is none the reflection of light from the background, the unselected display elements and the housing, which otherwise significantly impair the contrast of the standard electromagnetic display panel. This effect is noticeable even under normal light conditions (additional UV light increases the color intensity), and is especially noticeable in low light conditions, where the electromagnetic display of the invention has extremely high contrast without any unwanted reflections.

The proposed technical solution simultaneously solves the problem of poor visibility of active display elements due to diffused light, as well as the angular dependence and visual perception of illuminated display elements, and is at the same time a simple, inexpensive and effective solution to the general problem of visibility of electromagnetic display panels in poor light conditions.

The use of the proposed illumination concept is not limited to a particular construction and can be used in conjunction with any known electromagnetic display concept solution.

As previously emphasized, to take advantage of UV illumination (near UV), the use of dyes that absorb light in the near UV spectrum and emit visible light on the surface of selected "ON" display elements or in the form of UV luminescent colors on active of display elements, or by incorporating UV luminescent additives into the plastic material of which the display element flap is made. In order to avoid the need for additional UV illumination, even in good light conditions, the selected “ON” of the display element must also reflect visible light. This can be achieved in several ways, and the implementation itself depends to some extent on the principle of operation of the display elements (Fig. 2a, 2b and the like - a more detailed description of the trace).

Under normal light conditions, a display panel manufactured according to the concept described above behaves in the same way as existing electromagnetic display panels, but in any case improves the color intensity of the display with additional UV illumination. In low light conditions, the use of illumination with near UV light brings the most benefit, since the electromagnetic display of the invention provides extremely high contrast without reflection and glare of scattered light in contrast to existing illumination solutions with standard fluorescent light sources.

The embodiment of the active illumination of the electromagnetic display, as an object of the invention, is very similar to the concept of standard illumination with conventional fluorescent lights. Replacing them with UV light sources in the near UV light spectrum (“black lights”) used in advertising, various shows, etc. (Fig. 4) or other light sources in the near UV range (UV LED ...), a significantly better contrast of the display is achieved, since there are no more reflections than the background and the housing, which significantly reduces the contrast of the standard electromagnetic display screen.

DESCRIPTION OF THE IMAGES

Hereinafter, the invention is exemplified and illustrated by way of figures showing:

FIG. 1 - Light spectrum UV luminescent colors: curve a - light absorbed spectrum; curve b - spectrum of light emitted

FIG. 2 - Standard concepts of electromagnetic display element implementation:

a - Concept # 1 - Rotary flap represents the entire display element b - Concept # 2 - The display element consists of a static part and a rotary flap covering half of the surface of the display element.

FIG. 3 - Cross section through the "ON" portion of the display element showing the relative positions of layers containing UV luminescent dye for various manufacturing concepts: a - Layers of color containing UV luminescent pigments (7uv) and pigments for reflecting visible light (7vis) covering the "ON side" of the display element flap according to embodiment # 1 b - UV luminescent pigments incorporated / dissolved in the base plastic material 7 to produce the flap flap according to embodiment # 1, which are covered with layers on the "OFF" side the first reflecting visible light (7vis) and the second generally dark (typically matte black) (7 _b ), c - Color layers containing UV luminescent pigments (7yv) and visible light reflecting pigments (7vis) ) and cover the “ON” side of the display element flap and the “ON” half of the surface of the display element (implementation concept # 2), d - UV luminescent pigments incorporated / dissolved in the base plastic material (7) for flap fabrication p display elements and surface layers of the display element according to implementation concept # 2 - the display element flap, as well as the corresponding display element surface, are covered with additional layers containing either visible light reflecting pigments (7vis) or light absorbing pigments (7¾) (typically black matte): For flaps, on the "OFF" side, the supporting plastic (7) is first covered with a layer that reflects visible light (7 _V is), and then with a layer that absorbs light (7¾) and is typically matte black; on segments, the "OFF" part of the segment is covered with a layer containing light-absorbing pigments (7b), and the "ON" part of the segment is covered with a layer containing light-reflecting pigments (7vis) ·

FIG. 4 - UV illumination principle - The “ON” side of the display element is covered with UV reflectance; The display panel is illuminated by a "black" light source (near UV spectrum) with the possibility of adding correction filters to equalize the illumination intensity of the entire display panel.

FIG. 5 - The principle of UV illumination of large electromagnetic display panels.

DETAILED DESCRIPTION OF THE INVENTION

As previously discussed, the proposed technical solution for illumination of the electromagnetic display panel with light in the near UV spectrum instead of visible light enables the operation of electromagnetic display panels even in very poor light conditions in a simple, inexpensive and yet very efficient manner. This solution greatly reduces the light scattering and reflections, thus increasing the contrast.

The proposed concept of illumination is generally applicable regardless of the principle of operation of electromagnetic display elements, and the details of implementation vary to some extent. There are basically two fundamentally different concepts for the operation of the electromagnetic display element, as shown in FIG. 2a and 2b:

1. Solutions (described in EP 0327250, US 6,272,778, US 6,025,825, US 5,898,418, ...) based on rotatable flap 2 rotating about axis 5 in the center of flap 2 for typically <180 ° within mechanical limiters 9 and having an overall size of the display element (Fig. 2a):

The flap 2 is painted in high contrast colors on the front 2a and rear 2b. To switch between the "ON" and "OFF" states of the display element, this solution typically uses a permanent magnet embedded in the center of gravity of the rotary 2 display element and is oriented perpendicularly to the rotary axis 5, as well as a solenoid (3 + 8) with a U-shaped magnetic core 8 built into the housing of the display element 6 and oriented perpendicularly to the rotary axis 5 of the rotatable flap 2 of the display element. The magnetic poles of the U-shaped magnetic core 8 are positioned on the sides of the flap 2 as close as possible to the pole of the permanent magnet embedded in the rotary flap 2 of the display element. A short intense electrical impulse determines the direction of magnetization of the magnetic core 8 made of semi-solid material, which retains magnetization even when the electrical impulse disappears. The residual magnetism of the magnetic core represents a memory element. The magnetic force exerted by the semi-rigid magnetic core of the drive electromagnet determines the orientation of the permanent magnet embedded in the display element flap 2 and frames it to display either a high contrast light "ON" page 2a or a dark (typically black mat) "OFF" page 2b display element .

2. Solutions (described in U.S. Pat. No. 6,603,458, DE 3501912C2, DE 3601018A1, ...) based on display elements divided into two parts - static surface of display element la, lb or movable / rotatable 2 covering only one half of the display element (FIG. 2b):

Each display element incorporates a rotatable bistable rotatable flap 2 that is asymmetrical with respect to its rotary axis 5. The rotatable flap 2 covers one of the two halves of the display element surface when it is in one of the stable positions. The side of the rotatable flap 2a and the front surface of the display element 1a toward which it is facing are painted on one side and the other of flap 2b, and the remaining surface of display element 1b is painted with a second high contrast color relative to the first color. To switch between the "ON" and "OFF" states of the display element, these solutions use a permanent magnet inserted into each rotary damper near the rotary axis. The permanent magnet is oriented perpendicularly to the surface of the display element flap. The rotary damper 2 is driven from one bistable position to another by a flat magnetic core electromagnet located at the rear of each display element. The mechanism for switching between the “ON and“ OFF ”state of the display element is very similar to the concept # 1. However, such an implementation has some advantages over other solutions because the whole structure is significantly thinner (only half of the display element rotates about the rotary axis) than with the technical solutions described in concept # 1.

To take advantage of the (invisible eye) illumination with near UV light, it is necessary to use dyes that absorb this light and emit visible light in the upper layer of the selected "ON" surface of the display element. The surface may either be covered with UV luminescent paint or the UV luminescent additive may be embedded / dissolved in the plastic material used to produce a static surface and a rotating flap of the display element. In order to avoid the need for UV illumination in good light conditions, the surface of the selected ("ON") display element must also reflect visible light. This can be achieved in several ways, but to some extent they differ from one another depending on the principle of operation of the display element:

• Display element flap is made of dark (typically black matte) plastic that is the same as that used for the body of the display element 6. The “ON” side of the display element is covered with a color that contains both UV absorbing and emitting accessories. visible light) as well as accessories for reflecting visible light.

• The display element flap is made of dark (typically black matte) plastic, the same as that used for the body of the display element 6. The “ON” side of the display element is first covered with a layer that reflects visible light 7vis and then a layer of 7uv color. , which absorbs UV and is typically transmitted to the visible part of the light spectrum.

• The display element is made of transparent plastic 7 containing UV absorbing accessories. The "OFF" and "ON" states of the display element are then achieved with additional layers of paint containing additives for reflecting or absorbing visible light (typically black matte) - see examples.

The embodiment of the active illumination of the electromagnetic display panel 13 (Figs. 4, 5) of the invention is similar to the standard concept of illumination with conventional fluorescent lights. Replacing them with "black light" (near UV) light 11 used in advertising, various shows, ... etc. (Fig. 4) or other UV light source (UV LED, ....) significant contrast enhancement is achieved. In order to direct as much light as possible to the display panel 13, an additional reflector 10 is typically used. Regardless of the optimization of the shape of such a reflector, the illumination (light in the near UV spectral range) is "ON" of the portions of the display elements 13p covered with UV luminescent dye (Fig. 4), strongly dependent on the distance between the fluorescent source of "black light" 11 and the surface of the individual elements of the display panel 13. Therefore, the intensity of visible light emitted by the UV luminescent dye varies accordingly. Increasing the distance between the "black light" source 11 and the display panel 13 is usually limited by the dimensions of the display panel 13, so that the uniformity of UV illumination is achieved with a corresponding variable gray filter 12 (Fig 4).

In the case of large display panels 13, the solution described above, which uses standard fluorescent "black" light sources, is not very practical because large areas cannot be illuminated from the side only. Much more suitable for this are reflector lamps, which are the source of "black" UV light 16 (Fig. 5). In case of even greater illumination than is possible with standard reflector lamps 16 which emit "black light", standard low pressure light sources (mercury lamps) such as e.g. Philips HPR 150 spotlight bulb. The visible light emitted by these sources is removed with an additional filter 14 (eg Schott EG3 glass). To reduce the thermal radiation of this filter, optimize the spectral range of light radiation with the area of light absorption in fluorescent additives (Fig. 1), and finally to effectively remove unwanted deeper UV light, a thin Fabri-Perot reflective filter 15 (Fig. 5) is added.

The application of the proposed technical solution can best be demonstrated by the use of a medium-sized display panel, typically used to show the relation on buses and trains.

In this case, the electromagnetic display is made of an NxM array (N-number of rows; Number of columns) of display elements, where the number of columns is typically significantly greater than the number of rows (a few rows of α-numeric characters). As noted above, the implementation of the present invention depends on the choice or method of incorporating the UV reflective layers into the surface of the display element 13p when in the "ON" state, as well as on the principle of operation of the electromagnetic display panel used in a particular application. Typical embodiments are described in four examples and illustrated in FIGS. 3a, b, c and d as follows:

EXAMPLE 1

The basic principle of operation of the display element used in said display panel on buses or trains is based on a rotatable flap 2 rotating about an axis 5 and passing through the center of the flap 2 - manufacturing concept # 1 as described above (page 6 , Fig. 2a). To display either the "ON" or "OFF" state of the display element, flap 2 rotates ~ 180 ° around its rotary axis, and both sides of the flap are covered in high contrast colors.

Additional illumination is required to be able to use the display panel in good and poor light conditions. When using the "invisible" illumination principle of the near UV spectrum of the invention, the flap of this embodiment is made of black matte material (typically black pigmented ABS), preferably the same as that used for the body 6 of the display element. Thus, the "OFF" side 2b of the flap is black matte without further processing. To give a high contrast display, the "ON" side 2a of flap 2 is first painted with a layer (typically 10 gm thick) of color 7yis containing visible light reflection additives and then covered with a layer of color 7uv containing a high concentration of additives that reflect UV light (for example: VOC Y3G). This layer absorbs the light of the near UV spectrum and then emits light in the visible part of the spectrum (Fig. 1), which is preferably equal to the reflectance spectrum of the first layer of color 7yis - Fig. 3a.

For the active illumination of the electromagnetic display panel 13 (Figs. 4, 5) of the present invention, use fluorescent lights 11 which emit "black light" and are arranged along one or both of the longer sides of the electromagnetic display panel 13 (Fig. 4). To focus as much light on the surface of the display panel 13, a reflective reflector 10 is added, designed to illuminate the display panel surface as evenly as possible. Notwithstanding the optimization of the shape of this reflection, the illumination of the UV is a reflective color covering the display elements 13p as shown in FIG. 4, with a "black" UV source, strongly depends on the distance between the "black" fluorescent lamp 11 and the selected portion of the display panel 13, and therefore the intensity of the visible light emitted varies accordingly. The illumination uniformity of the electromagnetic display panel 13 can in principle be improved by moving the light source away from the display panel surface, but the variation of the distance between the "black light" source 11 and the display panel 13 is usually very limited by the display panel size 13 and attachment options. Due to this uniformity of illumination, it is not possible to achieve only by optimizing the shape of the reflectance 10. This is achieved by the installation of a suitable variable gray filter 12 (Fig. 4).

EXAMPLE 2

Unlike the electromagnetic display panel described in Example 1, said display panel can be constructed in such a way that the rotating display flaps are made of plastic material 7 which already contains UV reflective additives instead of the material of which the body 6 of the display element is made. In order for the plastic body of the flap 2 made of said material 7 to reflect light in the visible region, if illuminated by a source of visible light or in the near UV spectrum, the plastic material 7 must be more or less transparent for visible light and the "OFF" surface of the flap with the 7yis layer completely reflecting light in the visible spectrum, while the UV luminescent additives included in the material 7 emit absorbed light in preferably the same visible spectral range as the 7yi _S layer. If the "OFF" side of the flap is eventually covered with a layer of black matte color 7b (which completely absorbs the incoming light), rotation of the flap by ~ 180 ° means a switch between "ON" (light) and "OFF" (dark) display state. of the element (Fig. 3b).

The performance of the active illumination of said electromagnetic display panel 13, as well as other features related to the visibility of such an embodiment, remain the same as in Example 1.

EXAMPLE 3

The basic principle of operation of the display element used in this embodiment of said electromagnetic display panel for displaying a bus or train relation is based on display elements divided into two parts - the static part of the display element la, lb and the rotary flap 2, which covers half of the display element - manufacturing concept # 2 as described above (page 6, Fig. 2b). To display either the "ON" or "OFF" state of the display element, the asymmetric flap 2 is rotated about ~ 180 ° around its rotary axis so that both surfaces of the flap 2a and 2b, as well as the portions of the display element la and lb that are covered by flap 2 shows highly contrasting colors in both bistable positions.

Additional illumination is required for the display panel to be usable in good and poor light conditions. When illuminated by an invisible light in the near UV spectrum of the invention, in this embodiment, the flap is made of black matte material, which is preferably the same as the material from which the body of the display element 6 is made. Both the “OFF” side of flap 2b and the “OFF” portion of the static display surface of display element lb show a black matte color without further processing. To display a high contrast color in the "ON" position of the display element, the "ON" side of the flap 2a and the "ON" side of the static surface of the display element 1a are first covered with a layer (typically 10 gm thick) of color 7vis which contains visible light reflecting accessories , then with a 7uv layer containing a high concentration of UV luminescent additives that absorb light in the near UV spectrum and emit light in the visible portion of the spectrum (Fig. 1). The light spectrum emitted by UV luminescent additives is preferably equal to the reflected light spectrum of the first layer of color 7 _V is - FIG. 3c. Rotation of flap 2 from one bistable position to another switches between "ON" and "OFF" status of the display element.

The performance of the active illumination of said electromagnetic display panel 13, as well as other features related to the visibility of such an embodiment, remain the same as in Example 1.

EXAMPLE 4

Alternatively, the embodiment of the display panel described in Example 3 may be such that both the rotatable flaps 2 of the display element and the static portion of the surface of display element 1 (Fig. 2b and Fig. 3d) are made of plastic material 7 with UV luminescent accessories, which is the object of the invention instead of the material from which the body 6 of the display element is made.

In order to ensure the operation of said electromagnetic display panel illuminated by either visible or UV light in the near UV spectrum, the plastic body of the flap 2 (page 2a in Fig. 2b) and the surface la of the static surface of the display element 1 must be made of said material 7 which reflects strongly visible light when display element 13p (Fig. 5) is in the "ON" position. Therefore, the material 7 must be transparent to visible light and the surface of the flap 2b must be covered with a layer of color 7vis that completely reflects the light of the visible spectrum. Since this embodiment of the display element consists of the surface of the flap 2a and the static surface la of the display element 1, this surface la also on the "OFF" side must contain a layer 7vis which completely reflects light in the visible spectrum. When the UV reflective additives in the material 7 emit absorbed UV light preferably in the same visible spectral range as the 7vis layer, such a display shows an intense light ("ON" state) color in illumination with visible or UV light. If side 2b of flap 2 and part of static surface lb of display element 1 is covered by a layer of black matte color 7b (which completely absorbs visible light), then rotation of flap by ~ 180 ° means a switch between “ON” (“bright”) and “OFF” ( dark) state of the display (Fig. 3b).

The performance of the active illumination of said electromagnetic display panel 13, as well as other features related to the visibility of such an embodiment, remain the same as in Example 1.

It should be appreciated that the embodiments described herein represent only four embodiments of the present invention of the electromagnetic display panel, but of course many modifications and variations are possible in accordance with the particular design of the electromagnetic display panel and the principle of operation thereof. A typical modification of the above examples is associated with the use of colors that contain both UV reflective and visible light reflectors, instead of two completely different color layers, each containing one additive, as described in the above examples. Another typical example of variation of the above examples is large display panels (for example, an information display panel at an airport), where the technical solution described above using standard fluorescent "black lights" is not very practical because large areas cannot be illuminated from the outside only. In this case, UV reflector lamps that have the same spectrum as standard "black lights" (Fig. 5) are more appropriate.

If stronger UV illumination is required than standard "black light" reflector lamps 16, standard low-pressure light sources (mercury lamps) such as e.g. Philips HPR 150 spotlight bulb. As these sources also emit in the visible spectrum, a glass filter 14 is added which absorbs visible light (eg Schott EG3 glass). To reduce the thermal radiation of this filter and optimize the spectral range of light radiation with the area of light absorption in fluorescent additives (Fig. 1) and finally to efficiently eliminate unwanted deeper UV light, a thin Fabri-Perot reflective filter 15 (Fig. 5) is added.

Claims (7)

PATENT REQUIREMENTS An electromagnetic display panel consisting of a matrix of typically square display elements with an electromagnetically movable flap (2) having two bistable positions and light sources (11,16) allowing operation in low light conditions, "ON" and "OFF" "The state of the display elements (13p) determined by two bistable positions of the movable flap (2) and each side of the flap adequately covered with different, visibly high contrast colors on the surfaces of the display elements (13p), each flap (2) having a permanent magnet and each of the display elements having a coil (3) with a plasto-ferrite magnetic core (8) which allows the flap (2) to be moved from one bistable position to another by an electric current pulse, characterized in that the light sources (11 , 16) emit light in the near UV spectrum and that the surface of the display element (13p) in either of the two bistable positions indicates either an "ON" or "OFF" state of the display element containing fluores cent additives that absorb light in the near UV range and emit visible light. Electromagnetic display according to claim 1, characterized in that the fluorescent additives, which absorb light in the near UV spectral range and then emit visible light, are embedded in the surface of the display element (13p) corresponding to either "ON" or "OFF" the position of the display element in one of the two bistable positions of the movable flap (2) and said UV fluorescent accessories are incorporated by coloring said surface of the display element (13p) with a layer of color (7vis) containing color additives to reflect light in the visible part of the spectrum , and covered with a layer (7uv) of color containing UV fluorescent additives. Electromagnetic display according to claim 1, characterized in that the fluorescent additives, which absorb light near the UV spectrum and emit visible light, are included in the surface of the display element (13p) in one of the two bistable positions of the movable flap (2), which is either the "ON" or "OFF" position of the display element and That said UV fluorescent pigments are incorporated by painting said surface of the display element (13p) with a layer of paint containing both pigments for reflecting visible light and UV fluorescent pigments. Electromagnetic display according to claim 1, characterized in that the fluorescent additives, which absorb light in the near UV spectrum and emit it in the visible part of the spectrum, are incorporated into the surface of the display element (13p) by being added to a plastic material of which the said surface of the display element (13p) is made. Electromagnetic display according to claims 1 and 2 or 3 or 4, characterized in that the illumination (11, 16) of the display is carried out by standard fluorescent "black" light sources which emit light in the near UV range. Electromagnetic display according to claims 1 and 2 or 3 or 4 and 5, characterized in that a gray filter (12) is added to equalize the illumination intensity of the display panel as well as a properly designed reflector reflector (10). Electromagnetic illumination illuminated in the near UV spectral range according to claims 1 and 2 or 3 or 4, characterized in that the illumination of the display is provided by a standard reflector lamp which emits light in the UV A spectral range (16) and additional a filter (14) for absorbing visible light, which is preferably combined with a selective thin-film mirror (15) whose spectral dependence is optimized such that the effective spectral dependence of both filters coincides with the absorption peak of the UV-fluorescent pigment.