FI117453B - The display module - Google Patents

Description

, 117453 I

Display Module

This invention relates to illuminating devices. More precisely, this invention has to do with monitors (displays) for low degree of information. The display consists of a light source that is connected to a guide, which has a surface consisting of elements, which can bend light coming from the light source.

Displays with low degree of information consist in round tai of about ten segments, or even

10 fewer. In the display arrangement, each element is usually completely independent of the other elements. On the other hand, high information displays are usually based on a matrix structure or a sweeping electron beam in cathode ray tubes (CRTs). In high information displays, the pixels light up at the intersection of the columns and the lines f depending on the signals in the perpendicular electrodes. There are usually hundreds of thousands of 15 pixels or even even more. Typical applications are television sets and monitors f for laptops and monitors. The LCD, cathode ray tube and now later plasma displays (PDP's, plasma display panels) with active and passive arrays are the established technology

Typical location information displays are liquid crystal displays (LCDs) used in radios and in tape recorders, in toys, in measuring instruments and in various alphanumeric displays.

• I * * »*: Also LEDs (LEDs) are used in position information displays, especially in alphanumeric • * · * ·: applications. A third established display technology for position information displays is • * · • f: vacuum fluorescence displays (VFD), which are often used in measuring instruments, cash registers ”* * j'.J and also in car dashboards, especially in the United States. A new technology that pays to come • * *: ***; 25 in this field is organic electroluminescence (OLED).

* * * ': * · [: A special category of location information displays consists of indicators that display only one * · i. "In message, as is the case in" exit "signs and light indicators, where the information either in * is displayed continuously or is displayed in an on / off mode.

30 • · · # ··. # LCDs are the most widely used display technology in location information displays. They are> * · * t * relatively cheap and the power consumption is relatively low. Since the LCD panel mte * · emits light by itself, a backlight, or in some cases, foreground light, must be used to make the display visible in low light. The backlight consumes power.

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Light panels based on powder electroluminescence were previously widely used in the background lights. These light panels have now increasingly been replaced by a separate background light source and a diffusing light guide, which spreads the light across the screen surface. Light sources can be either light-emitting diodes (LEDs) or fluorescent lamps, also called CCFL (cold 5 cathode fluorescent light), depending on the size of the display. The backlight and; the diffusing supervisor often represents a significant portion of the cost of a location information display. There are limitations to the LCD because the response time of the LCD material and the ignition of the CCFL light cause problems at very low temperatures. The polarization filters are a limitation at high temperatures.

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LEDs are usually more expensive than LCDs. On the other hand, the LEDs are self-emitting and are therefore visible in different types of lighting conditions. Smooth luminance is achieved only by using light-leveling optics, which increases costs.

The VFDs are limited to small displays, which are also relatively expensive. Like the LEDs, the VFD emits light.

OLED technology has not penetrated the market yet, mainly due to problems with stuck images and the need for encapsulation that increases costs.

20 • · * ··. Light emitting surfaces with uniform luminance have been developed for backlighting in the LCD.

• * ·. ·. · Usually they are based on light guide boards provided with such a surface that • * · • ·; switching off the light gives a uniform luminance. That is, the switch-off elements are thus • * * • ·: designed to increase the switch-off with increasing distance from the light source. The light source can * ·. ** ·. May be either a CCFL or an LED. Various technologies are available to achieve the desired cut-out profile, such as painting with different density of white dots on the back of the disc, or by forming irregularities with a technique used by e.g.

* *

Global Lighting Technologies or by shaping a monster of dangers that shape microprisms (eg Brite View, see SID International Symposium, Application Digest • ·. * ··. 30 PI 1 (1994) or P3 (1995)). Also other patterns for forming elements for the switching off of the * · # A. light can be constructed. These technical solutions, which are essentially based on the light • light nature, are well known to those who are familiar with LCD background technologies. The horizontal dimensions are typically 10 µm or more and the vertical dimensions are usually a few microns. *

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A recent technology for producing backlight for LCDs and for producing displays displaying a static message is based on the use of diffractive elements, as described in U.S. Patent 5,703,667 and in FI Patents 106,323, * 106 992 and 107 085.1 of these technical solutions, the diffractive elements 5 are designed so that the light is switched off from the guide so that a light-emitting disc with uniform luminance is created. The LEDs are the most appropriate light sources for these light emitting guides with diffractive elements and the number of LEDs depends essentially on the surface of the illuminating disk, the efficiency of the light switching on, the desired luminance and the luminance efficiency of the LEDs.

It is of the utmost importance to construct the diffractive pattern so that the luminance does not depend on the distance from the light source (or light sources). Ie the pattern is a function of the distance to the light source (s). The pattern typically consists of dangers, stripes, possibly in pixel format, or by points, and the periodicity is usually between 1.5 µm and 10 µm. The height of the pattern is usually 0.5 µm in round tai.

An advantage associated with guide discs where LEDs are used is the very thin structure where a thickness of less than 1 mm can be achieved. Other advantages are a • * cost-effective manufacturing technology in high volume production using • 9 ·, **: 20 injection molding, a high efficiency of the light switch-off and a shock-resistant structure, which works in both very high and very high positions. temperatures.

• · * · · ··· .. · • * • · · • · * ··. * The shining guide plate with the switch-off elements can be divided into sections, so that LEDs with different sizes illuminate different sections, as stated in Fl patents 106992 and • · · \.

Referring to light plates with diffractive elements, this makes it possible to use the light panels and light plates in said patents as location information displays.

* · • · • * · * · * ... · In all guides with diffractive elements, described in the prior art, only one * in "l message, consisting of a given character, symbols, numbers or letters, or" * ·: 30 combinations of these, shown on the same surface as depicted in Fig. 1. Fig. 1 shows the light disk (Fig. 1a), an enlarged view of the diffraction pattern seen from above (Fig. 1b), alternative cut-throughs for the diffraction pattern (Fig. 1c). and how the light progresses forward in the guide (fig. id).

4 117453 In order to be able to display more than one message, known technical solutions require that other messages must be placed side by side. This is a serious limitation. This assumes that the display area is large, which becomes a clear disadvantage, since larger area increases costs and viewers are accustomed to seeing displays, where different messages can be displayed on true surface.

The object of the present invention is to remedy the problems associated with the prior art and to provide a new type of location information display.

The present invention is based on the idea of stacking several guide discs with elements that switch off the light on each other. The elements that switch off the light can consist of diffractive elements, microlenses or microprisms. The boards consist of guides with disconnecting elements, e.g. diffractive seeds, which have the ability to bend light rays from the light source towards the guide surface. There are light sources connected to each guide.

The guide layers are substantially translucent and in accordance with the invention, each of them may display its own message, as illustrated in Fig. 2a. The number of messages li · * · ,, which can be displayed completely independently of each other, therefore, corresponds to the number of guidance layers in the: * ·.

Specifically, the invention is characterized by what is set forth in the characterizing part of claim 1.

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The invention provides considerable advantages. Accordingly, with the present display module, it is possible to display several, typically 2 to 6, different characters in the same range.

The invention utilizes the compactness and advantage of the guide elements with diffractive elements described above to make a new type of display to replace more expensive and more space-consuming LCD and LED panels in some applications for. ***; läginformationsdisplayer.

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Further features and advantages of the invention will be apparent from the following detailed description of the invention.

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Fig. 1 schematically shows a prior art light indicator based on a single guide layer with diffractive elements, Fig. 1 shows the light panel, Fig. 1b shows the pattern of the diffractive elements seen from above and Figures 1c and 1d show the intersection of alternative diffraction patterns. and how the light progresses in the guide.

Figure 2 shows in a corresponding way a display module consisting of two waveguide layers with a = disengagement pattern on the surface according to a preferred embodiment of the invention, with figures 2a and 2b showing the invention seen from above, fig. 2c shows a section through the module and fig. 2d an enlarged view of the intersection.

Figure 3 shows a simplified construction of the display comprising three waveguide layers (Figures 3a, 3b and 3c) with diffractive patterns on the lower surfaces.

Figure 4 shows schematically the composition of a four-waveguide layer display module (Figures 4a through 4d) with diffractive patterns on the lower surfaces.

Figures 5a and 5b show how the light sources can be placed in the corners of the three guides in one embodiment according to Figure 3 to reduce light being lost through the edges of the guides.

As mentioned above, the basic idea behind this invention is to stack translucent, semi-transparent or colored guide discs with disconnecting elements on each other, so that each guide displays its own message. as illustrated in Figure 2.

Transparent guides are preferred. Typically, the loss in light intensity in such discs should be; not be greater than 5% / cm, heist less than 1% / cm, as the light progresses in the disc. When ·. *: The guide is colored, it absorbs in some part of the light spectral range. This feature can be used to increase the contrast of lighting in the lighting environment in question by using a light source where the absorption is low. Figure 2a shows a display module with patterns in two layers on top of each other (Figure 2b). Figure 2c shows a section through the display module and Figure 2d shows in some of the section through magnification how the light progresses from the light source. In the embodiment of Figure 2b, the light sources 11,12 are positioned on opposite sides of the display module. The number of completely different, in all respects: **] in mutually independent messages, which can be displayed, adds up to the number of supervisor layers in the *; **: 30 display.

It is necessary to emphasize that the switching elements (eg a diffractive grating) may be on either side of the guide, ie. on the upper or lower side, or even on both sides.

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The messages usually consist of light patterns such as symbols, characters, letters, numbers and the like.

Different colors can be used in different layers and each layer can in principle consist of several guide boards, which are illuminated when needed with different colors. The most appropriate light source is an LED, but other light sources can also be used. The light source, in particular a light-emitting diode, can be connected directly to the guide with the switch-off elements. Alternatively, the light source can be connected to the guide using optical fibers.

The switch-off elements can be any kind of hoist, only they meet the requirements of the display in the current application. That is, the performance of the display in terms of image quality, efficiency and cost factors dictates the type of switch-off technology to be selected. The technologies applied to the backlight and as mentioned above can be used in the practice of the present invention. In particular, the disclosure of U.S. Patent No. 6,014,192 is hereby incorporated by reference. An advantageous switch-off approach is based on diffractive elements, especially when a point-shaped light source is used (eg light-emitting diode, LED). The diffractive elements may e.g. include grid structures! * .. with dangers and stripes. It is also possible to use beam optical elements including:, * ·· (micro) lenses and prism.

0! In a preferred embodiment, the diffractive elements can bend the light from the light source "in a direction substantially perpendicular to the surface of the guide. As will be stated below, this property eliminates the need for light scattering films in the device.

The guides are essentially made of transparent material as described in the prior art.

• ·: * · Injection molding is the most expedient manufacturing method, since this invention aims to provide high-volume production of humanized displays.

The basic principle can also be applied to other manufacturing methods such as e.g. UV - casting. If diffractive cutout elements are used, they are similar to those used to achieve a uniform light emission, but not identical to those described in FI 106323, FI 106992, FI 107085. In addition, the diffractive pattern should is designed so that a sufficiently uniform light emission is achieved taking into account the extremely different types of symbols or letters to be displayed.In many cases, there is no need to construct the switching elements so that they depend on the distance to the light source. in other words, often enough.

Thus, the disengagement pattern can be constant. However, it is possible to construct the switch-off elements in the manner proposed in the prior art so that the switch-off pattern varies with the distance from the light source to give rise to uniform light emission. in

Particularly where a diffractive pattern is used as the cut-off element, the guide discs or plates should heistly be designed so that the light advances in two adjacent layers perpendicularly, or at an angle of at least 60 °, in relation to each other so as not to create shadow images.

In addition, the switch-off elements should be designed so that the switch-off is high in the direction the light propagates in the current layer, low, heist below 10%, for light propagating in the adjacent layers.

It is important that the layers are in close contact with each other. Usually the layers in direct contact with each other or the distance between them is less than 1 mm, typically less than 0.5 mm, usually less than 0.2 mm. It is equally important to avoid parallel hazards or stripes in adjacent layers of the diffractive pattern since such tend to be -s; image blurred. To increase the luminance of the display, one can place light scattering = • t · Ά • <: semi-transparent films under the guides as shown in Figure 2, Figure 3 and Figure 4. It is * *: preferable that the transparency of the light scattering films increases against the lower bearing! ; \ t and that the light-scattering film, later also referred to as '' diffusing foil '', under the lower guide plate should be opaque to achieve a maximum | • · light scattering or reflection.

• · * · As mentioned above, there is no need to use semi-transparent light scattering * · · foils when the diffractive elements are constructed so that the switched off light is essentially; * · *; 30 is deflected from the guide plate at an angle close to 90 degrees (almost perpendicular to the surface).

Usually, the light is deflected at an angle of 60 to 90 degrees, preferably between 75 and 90. degrees to the plane of the disc. In this case, part of the light is bent towards the viewer and another * · • · ·: part in the other direction (from which it can be reflected by means of a mirror-like background disc in case higher luminance is sought). In bright lighting from the surroundings, 8 117453 '

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however, it is advantageous to use a light-absorbing background disc to increase the contrast. Typically, about 60% of the light from the diffractive elements is deflected back through the guide and 40% is deflected into the environment from the diffractive elements. When the diffractive elements are arranged on the back of the disc, about 60% of the light is deflected towards the viewer by the guide disc and 40% is deflected on the back. When the diffractive elements are placed on the top of the disc, the situation becomes inverted. To further enhance the contrast, it is advantageous to place a neutral filter (filter whose absorption of light does not depend on the path length) or a circular polarizing filter in front of the display. In particular, such filters can be placed on top of the top guide.

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Usually, the switch-off elements (both spreading and diffractive grids) are designed so that the light is switched off at a wide emission angle. A diffusely reflective film - which reflects over a wide angle - is then placed behind the guide. Consequently, light emission on the front is also observed within a wide angular range.

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By constructing the diffractive elements (the grating) so that the light is essentially switched off perpendicular to the guide surface, sharper edges and lower absorption in the switching elements in the upper layers are achieved. This embodiment is particularly interesting when a lower light intensity (luminance) is acceptable considering the display at a wide angle measured against the normal surface.

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• tl • ·; Accordingly, and in summary, a display module in accordance with this invention may comprise a light-absorbing background located behind the lower end. * j the guide or a reflective surface behind the bottom guide.

:: * in 25 • · · Compared to backlight guides, where most of the surface is lit, only one: * · *: part of the surface is usually lit in this display module. This places greater demands on it in avoiding losses in the supervisor, especially through the edges. It is advantageous to place r, lie blur in a corner to reduce the light transmission through the edges as depicted in * ·: * * *. Figure 5. This approach can generally be applied to illuminating display disks that * ·· # ·· ^ are based on guide disks with diffractive elements on the surface. Thus, it can be used * * for constructions based on only one disc as described e.g. in U.S. Patents 5,703,667 and FI patents 106,323,106,992 and 107,085.

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With regard to the accompanying images, it should first be noted that the drawings - as well as the accompanying descriptions - have been simplified to illustrate the constituents which are important for clearly understanding this invention, while for the sake of simplicity constituents found in typical guide elements based on disconnecting elements, including the detail of the cut-off elements and the diffractive pattern on the surface, have been omitted. So should I

it is clarified that the guide parts can be manufactured by various well-known methods, e.g. from the manufacture of corresponding guide discs for backlit LCD devices and that higher luminance levels can be achieved with LEDs with optimized light connection to the guide discs.

In the embodiment shown in Figure 2, a 1 mm thick guide is made of plastic (e.g. polycarbonate, polymethyl acrylate (PMMA)) and provided with a pattern of small bumps which in turn form a pattern of a pii. 2b, placed 0.2 mm below another similar guide, but with a pii showing eat left. The guide members with the tuber pattern are made by injection molding by e.g. use technology developed by Global Lighting *

Technologies as described in Wireless Design Online, July 12, 2000. A semi-transparent light-scattering film (made, for example, of 3M) is placed between the guide boards. An opaque light-scattering film is placed behind the lower disc.

; ·. Each arrow has a surface of 2.5 cm and each arrow is illuminated with two yellow LEDs, 2c • ·· • 2 .: and 2d, respectively. These give the arrows a luminance of about 200 cd / m since the LEDs are used under normal conditions (near 20 mA). It is preferred that the light from the LEDs progress in the opposite direction in the two guide layers as illustrated in »·: * ·, · Figures 2b and 2d.

In a further preferred embodiment there are three guide elements on each other, Figures 3a, 3b and 3c. Each is 1.2 mm thick and made of polycarbonate • * (polycarbonate, PC) using relief printing or injection molding. A diffractive pattern · * · *: which forms the words ON, OFF and READY on the respective guides. The area of the respective words • *: ***: 30 is 1.4 cm2.1.7 cm2 and 1.0 cm2, and the guides are bright with two green, two red and two * ··. ···. yellow LEDs, 21, 22, 23, in respective layers. The LEDs are positioned so that the light progresses in a different direction in each direction in each layer, as shown in Figures 3a, 3b and 3c. In order to improve the sharpness of the words, thin, commercially available semi-transparent light-scattering films are placed between the two top guide lines without a deliberate air gap in between. The light-spreading film under the bottom layer is opaque. The luminance is typically 100-150 cd / m2 when the surface mounted LEDs are powered by a current close to 20 mA.

The embodiment of Figure 3 can also be done in the following way: three guide elements are placed on each other, Each is 0.8 mm thick and made of polycarbonate (polycarbonate, PC) by means of relief printing and injection molding. A diffractive pattern forming the words ON, OFF and READY is found on the respective guides. The diffractive patterns are designed so that about 60% of the light is reflected back through the guide plate in the direction of the viewer, while about 40% is switched off in the opposite direction. The surface of each word is 1.4 cm2, 1.7 cm2 and 1.0 cm2, and the guides are illuminated with four green, four white and four yellow LEDs in each layer. The LEDs are positioned so that the light progresses perpendicular to the light in the adjacent layers. There is a narrow (~ 0.1 mm) air gap between the guide discs and behind the lower guide disc (OFF) there is a black light absorbing layer of plastic to enhance the liner; 15 contrast in bright lighting. To further improve the contrast, there is a neutral filter with 12.5% transmission in front of the bar with the three guides. The luminance is typically 50-150 cd / m2 when the surface mounted LEDs are powered by a current close to 25 mA.

As shown in Figures 5a and 5b, LEDs, 31-33, can be placed in the corner of the rectangular ♦ / · 20 (square included) structures. Heist, they are placed in nearby homes in V ·· adjacent guide boards so that the light advances at a 90 degree angle at the relative tili ·. * ·: The light in the adjacent guide boards. The boards need not be exactly rectangular · ♦ · ·… · (square), although this is the most preferred embodiment. The placement of the light source in the hay somewhat reduces the switch-off of the light through the edges of the light guide (guide) by maximizing the total reflection at the edges. This because the Large ··· 1 σ • a * · "* angle of incidence (measured against the normal to the surface).

In another preferred embodiment (Figures 4A and 4B), four guide discs, 4a - a ϊ * ”ϊ 4d, are placed on each other. Each guide is made using UV casting of an epoxy film applied to a 0.7 mm thick glass substrate. A diffractive pattern is formed, forming different symbols, on the lower surface of each layer, and semi-transparent light-scattering films are placed between the top three layers. The light-spreading film under the lowest layer is opaque. The light from the LEDs is connected to the guide discs by means of optical fibers.

Claims (18)

1. Location information display, characterized in that - it comprises at least two guide discs on each other, each disc 5 being coupled to a light source and each disc being provided with a cut-out pattern on at least one of its surface to extract the light from the light source. forming a luminous pattern comprising symbols, signs, letters, numbers, and the like, and - at least one guide consists essentially of rectangular disks, the light source being coupled to a hem of the board and adapted to emit light substantially parallel to the surface. of the disk for achieving total reflection at the opposing edges of the disk. Display module according to claim 1, characterized in that the light pattern is formed by light beams in a direction substantially perpendicular to the surface of the guide. 3. Display module according to claim 1, characterized in that the light pattern is v shaped by light rays, which are switched off at a wide angle and - optionally - reflected back by means of a light diffusing foil, which is placed in the display module below ··. 20 guide discs. • 99 9 • 9 9 9φ • * • *: 4. Display module according to any of claims 1 to 3, which can be adjusted by • · · • t. ·: The switch-off pattern is constant. • 9 • 9 9 9 9 '9 · 9 9 9. · **. 25 Display module according to any of claims 1 to 3, characterized in that the switch-off pattern varies with the distance to the light source to achieve a uniform: light emission. * · · • * · • • • • • * * ' Display module according to any of claims 1 to 5, characterized in that ··· «. · * ·. The light switching pattern comprises beam optic and / or diffractive elements at least * ··. J. one of the surfaces for switching off the light. 9 9 · 9 9 9 9 Display module according to claim 6, characterized in that the light switching pattern comprises beam optical elements on at least one of the surfaces for switching off the light to form illuminating symbols, signs, letters, numbers and the corresponding, and at least one light source is coupled to each guide. - 8. A display module according to claim 6, characterized in that the light switch-off pattern comprises diffractive elements on at least one surface for switching off the light to form illuminating symbols, signs, letters, numbers and the corresponding, and at least one light source is connected to each guide. Display module according to any preceding claim, consisting of a first guide disk, a second guide disk adjacent to the first, characterized in that each disk has a switch-off element which can bend the light substantially perpendicularly, the first and second guide disk being located close to each other. Display module according to any of the claims 1 to 8, characterized in that it contains a first layer formed of a first guide disk, a second layer formed of a second guide disk separate from the first guide disk, and a semi-transparent light diffusing sheet between it. the first and second layers. · *. 20 11. A display module according to claim 10, characterized in that there are at least three layers consisting of guide sheets and each layer is separated from the following by means of a semi-transparent light diffusing foil. • · * • * i * ·. * 12. A display module according to any of the preceding claims, characterized in that all of the guides consist essentially of rectangular discs and the light source is coupled to a home of the disc and adapted to emit light which is substantially in the # j ': parallel to the surface of the disk for achieved total reflection at the opposing edges of the disk. ··· ·· * ****. ** ·, 30 Display module according to some of the preceding claims, characterized by • · · that the light source consists of a light-emitting diode, which is optionally connected to the guide plate by means of * · i. optical fiber «···« '• · Display module according to any of the preceding claims, characterized in that each of the above layers in the module is placed in contact with adjacent layers. 15. Display module in accordance with some of the preceding claims, characterized in that a light-absorbing background is placed behind the bottom plate. 5 Display module according to any of the preceding claims, characterized in that it comprises a reflective surface behind the lower disc. Display module according to any of the preceding claims, characterized in that it comprises a neutral filter on top of the top guide plate. 18. Display module according to any of the preceding claims, characterized in that each of the guide discs is transparent. ·· • «• · · · · · · · · · · · · · · · · · · · · · · · · t · • ** * ·: · k • · · • · * * ··· • · · * · «··· • ·» · *** * • · ·. • * · · ·· * * «·· .'- * · · • · P • * · • · · * ··« * · • ·, 4 1 1 7453