EP2196982B1 - Segment display with a light guide - Google Patents

Description

The invention is in the field of segment displays and discloses a segment display with improved readability and feel, as well as simplified mountability.

Segment displays are used to represent numbers, letters or characters by electronically or electromechanically driving one or more of their segments. The prior art form a variety of differently structured segment displays, which differ in the number and arrangement of their segments. One of the most important segment displays is the seven-segment display, which combines all digits from 0-9 up to seven individual segments.

The segments of conventional segment displays are often formed by bar or bar-shaped LEDs. In these segment displays, the light is therefore generated directly in the segments themselves. Other conventional segment displays spatially separate light generation and light exit points. For this purpose, the light sources are driven, usually also LEDs, which are, for example, on the circuit board of a device, and the generated light is guided out by means of light-conducting elements through the housing of the device. This design has prevailed especially in devices in the field of telecommunications.

Such segment displays are usually made in one piece by means of a plastic injection molding process, wherein the light-conducting elements on the side, which later faces the LEDs on the circuit board, are connected to one another by connecting webs. Accordingly, when these segment displays are installed in a device, the light generated by the LEDs on the printed circuit board is fed through the segment display interface by means of connecting webs and led out through the housing of the device via the individual photoconductive elements.

A disadvantage of this arrangement proves, on the one hand, that the scattered light generated by the scattering in the connecting webs leads to an over-blasting in the individual light-conducting elements. As a result, it may come to light up uncontrolled segments and thus to a poor readability of the segment display.

Another disadvantage of such an arrangement proves that for the lead-out of the light-conducting elements from the device, openings must be present in the housing of the device. However, these can not be made arbitrarily close to each other, since the housing would become unstable. Accordingly, such segment displays, especially in housings made of plastics, usually have large distances between the individual segments. This can lead to poor readability. Furthermore, such large distances to be maintained may also require additional assembly steps in the manufacture of the equipment, resulting in increased production times.

Another disadvantage of such an arrangement proves that the device housing provides poor shielding against over-radiation of the led out light-conducting elements, resulting in poor readability of the segment display. This is the case in particular with plastic housings.

US 3,723,961 describes a segment display for displaying, for example, letters and / or numbers. The segment display uses a series of cylindrical light guides having a light entry point and a light exit point. The light entry point is connected to a first surface and the light exit point is connected to a second surface.

The object of the present invention is to provide a segment display with low scattered light development, good readability and easy mountability.

This object is achieved by a segment display comprising a light guide having at least two light-conducting elements, each having a light entry point and a light exit point, wherein the light guide on the side of the light exit point has a closed surface, and the segment display comprises at least one segment, and at least a segment is designed as a recess in the closed surface.

Accordingly, the idea underlying the invention is basically to connect the light-conducting elements of the light guide to the side facing away from the light source. The light leaving the light source is thus guided directly through the light-guiding elements bundled by the light source to the light exit point on the device surface. Since the light-conducting elements of the side of the segment display facing the light source are preferably not connected by connecting webs, disadvantageous light scattering and / or blooming effects are thereby minimized or completely prevented.

A further advantage of the present invention is that only a single opening needs to be introduced into the housing of the device through the connection of the light-conducting elements through a closed surface at the light exit point. As a result, the segments of the segment display can be arranged closer to each other, resulting in a more compact design of the segment display and thus shortened production times when installing the segment display in the final product. Furthermore, triggering of the segment display is increased by closer arranged segments.

A further advantage is that the execution of the segments as a depression in the closed surface reduces or prevents an over-radiation of adjacent segments, thus increasing the readability of the segment display. An increased readability of the segment display allows the reduction of the distances of the segments to each other, whereby a smaller design of the segment display is made possible.

The segments are at the end of the path of light through the photoconductive elements, i. the recessed segments coincide with the light exit point.

A further advantage of the present invention is that a simplified shielding of the individual light-conducting elements from one another is achieved by the connection of the light-conducting elements through a closed surface at the light exit point can, what prevents over-radiance. This aspect of the invention will be explained in more detail below.

In one embodiment of the invention, the segment display is a segment display with ≥ I, ≥ 7 or ≥ 14 segments. In a preferred embodiment, the segment display has 2, 7, 14, 38, 88 or 111 segments. Segment displays with 7 segments are particularly suitable for displaying numbers; Segment displays with 14 segments are particularly suitable for displaying numbers and / or letters. In a further preferred embodiment, the segment display has a multiple of the 2, 7, 14, 38, 88 or 111 segments, accordingly the segment display comprises ≥ 2 × 2, ≥ 2 × 7, ≥ 2 × 14, 2 × 38, ≥ 2 × 88 or ≥ 2 × 111 segments; ≥ 3 x 2, ≥ 3 x 7, ≥ 3 x 14, ≥ 3 x 38, ≥ 3 x 88 or ≥ 3 x 111 segments; or ≥ 5 x 2, ≥ 5 x 7, ≥ 5 x 14, ≥ 5 x 38, ≥ 5 x 88 or ≥ 5 x 111 segments. More preferably, the segment display has 2 x 7 or 2 x 4 segments.

The segment display comprises a light guide which may be made of any suitable, light-conducting material. In a further embodiment, the light guide consists of a polyethene (PE), a polypropene (PP), a polybutadiene, a polystyrene (PS), a polyvinyl chloride (PVC), a polyacrylonitrile (PAN), a polycarbonate or a polyacrylate. In a preferred embodiment, the material is PAN; this has the advantage that such a material is hard and stiff, as well as resistant to most chemicals and solvents and to sunlight and heat. In a further preferred embodiment, the material is PP; this has the advantage that such a thermoplastic material has high stability and chemical resistance and is relatively hard and heat resistant. In a further, particularly preferred embodiment, the material is a polyacrylate; this has the advantage of being translucent as glass, but much more stable due to its elasticity. In a more preferred embodiment, the material is a polycarbonate, eg Makrolon.

The light guide comprises at least two light-conducting elements, in which light is conducted from the light entry point to the light exit point. The light conduction preferably takes place in the individual light-guiding elements by total reflection. In this case, the light is focused in the light-conducting element. On the side of the light exit point, the light guides unite to form a closed surface.

In a further embodiment, the light guide comprises ≥ 1, ≥ 2, or ≥ 5 light-conducting elements per segment. The segment display 1 preferably comprises a light-conducting element per segment.

The light-conducting elements may have any shape, as long as it allows a light pipe from the light entry point to the light exit point. In particular embodiments, the cross-section of the photoconductive elements is substantially circular, oval, polygonal, quadrangular, pentagonal, hexagonal, or octagonal. Preferably, the cross section of the photoconductive elements is smaller at the side of the light entry point than at the side of the light exit point. In an even more preferred embodiment, the light-conducting elements are substantially cylindrical, preferably of circular cross-section, with the side facing the light entry point having the smallest diameter which increases toward the closed surface at the light exit point.

The closed surface can be made in any shape. In a preferred embodiment, the closed surface has a substantially circular, oval, rectangular, polygonal, quadrangular, pentagonal, hexagonal, or octagonal shape. In the most preferred embodiment, the shape of the closed surface is rectangular.

In a further embodiment, the closed surface has a thickness of ≥ 0.1 mm and ≦ 5 cm, preferably ≥ 1 mm and ≦ 1 cm, more preferably ≥ 1 mm and ≥ 5 mm, most preferably ≥ 2 mm and ≦ 4 mm ,

In a further embodiment, the closed surface has a flat surface. This planar formation can be interrupted by the recessed segments.

In a further embodiment, the segment display further comprises a connection element for fastening the segment display to the device housing. In a further embodiment, the segment display further comprises a connector for attaching the segment display to a cover.

In a further embodiment of the invention, the segment display is produced by means of a plastic injection molding process. Preferably, the segment display is in one piece. This has the advantage that the segment display can be installed as a single component and thus with reduced working time and uncomplicated in one device. Furthermore, such a slight separation of the individual light-conducting elements can be achieved by, for example, plugging the segment display (in a single operation) into a receptacle, wherein the light-conducting elements are optically separated from one another by intervening material.

In a further preferred embodiment, the segments are designed as line or rod-shaped depressions; more preferably, the segments are depressions of trapezoidal shape.

In a further preferred embodiment of the invention, the top surface of the closed surface is blackened. This also has the advantage that an over-radiation of adjacent segments is reduced or prevented. In addition, the contrast to the luminous segments is increased, thus increasing the readability of the segment display. An increased readability of the segment display allows the reduction of the distances of the segments to each other, whereby a smaller design of the segment display is made possible.

In a further preferred embodiment, the segment display further comprises a cover. More preferably, the cover is a lens, aperture, or filter disk. In the most preferred embodiment, the cover is made of smoked glass or a tinted transparent material. Such a cover on the one hand has the advantage that a better readability of the segment display is achieved. Furthermore, a further reduction in the design of the segment display is possible, in particular when using a lens. Another advantage of the cover according to the invention is that the feel of the device in which the segment display is installed is improved. In particular, this achieves a smooth surface without protruding edges or depressions. In a further embodiment, the cover of the segment display is tinted, executed in a dark shade or in device color or a color similar to the device. This has the advantage that the segment display per se is not or less clearly visible and only the luminous segments are perceived by the user.

In a further embodiment, the cover is connectable via a connecting element with the segment display. In another embodiment, the connecting elements of cover and segment display engage each other. In a preferred embodiment, connecting element is a clip or latching connection.

In a further aspect, the present invention relates to a segment module comprising at least one segment display according to the invention, and means for separating the light-conducting elements.

In preferred embodiments, the segment module comprises ≥ 1, ≥ 2, ≥ 5, ≥ 10, or ≥ 100 segment displays. The segment module preferably comprises 1 or 2 segment displays.

By the means for separating the photoconductive elements, an over-radiation between the individual photoconductive elements is reduced or prevented. Thus, a better readability of the segment display is achieved, and allows a more compact design.

As mentioned above, the connection of the light-conducting elements through a closed surface at the light exit point has the further advantage that a simplified shielding of the individual light-conducting elements from each other can be achieved. This can be done for example by simply plugging the segment display on / the means for separating the photoconductive elements.

In a preferred embodiment, the means for separating the photoconductive elements are means for optically separating the photoconductive elements. Such means may be made of any suitable material which reflects or absorbs light or has a low transmission coefficient for the light emitted by the light source. In a further preferred embodiment, the means for optically separating the light-conducting elements is opaque. In a preferred embodiment, the means for separating the individual light-guiding elements consists of plastic, rubber, metal or metal alloys.

The means for separating the light-conducting elements can separate the light-conducting elements from one another in partial regions or over the entire length from the light entry point to the light exit point. Preferably, a separation is about one third, about half, about two thirds, or about three quarters of the total length. Even more preferred is a separation over the entire length of the light-conducting elements, or over the entire length from the light entry point to the transition into the closed surface.

In a further preferred embodiment, the means for separating the light-conducting elements are designed as receptacles for the segment display and serve to secure them. This has the advantage of easy and time-saving assembly of the device. In a further preferred embodiment, the means for separating the light-conducting elements are firmly connected to a printed circuit board. In a more preferred embodiment, the means for separating the photoconductive elements and the segment display form a plug connection.

In a further embodiment of the invention, the segment module further comprises at least two light sources. In a further preferred embodiment, the light sources are LEDs. More preferably, the LEDs are fixedly connected to a circuit board of the device into which the segment module is to be installed. In a further preferred embodiment, the light-conducting elements of the segment module contact the light sources. In a further preferred embodiment, the light source lies in the plane of the light path from the light entry point to the light exit point of a light-conducting element. In a further preferred embodiment, there is a distance between the light entry points of the light-conducting elements and the light sources.

The segment module preferably comprises one light source per light-conducting element of the segment display. More preferably, the segment module comprises 7 or 14 LEDs.

In another preferred embodiment, the circuit board of the device in which the segment module is to be installed comprises one light source per light-conducting element of the segment display. More preferably, this circuit board comprises 7 or 14 LEDs. After installation of the segment module in the device, each light source preferably lies in the plane of the light path from the light entry point to the light exit point of a respective light-conducting element of the segment module.

In a further embodiment, the segment module further comprises a printed circuit board with light sources arranged thereon. More preferably, the segment module comprises a printed circuit board and a keyboard. In a further preferred embodiment, the segment module comprises a plug-in connection for installation in a device, e.g. a telephone. In a particularly preferred embodiment, the segment module is designed as a modular plug-in module for an electrical appliance, preferably a telecommunication appliance, that can be plugged into the appliance via plug connections.

The light sources can be arranged on the printed circuit board of the segment module or, more preferably, on the printed circuit board of the device into which the segment module is inserted. In both cases, the light guides are arranged relative to the light sources such that light emitted by a respective light source can be coupled in via the light entry point into a respective light guide.

• Fig. 1 zeigt die schematische Darstellung einer Segmentanzeige gemäß einer bevorzugten Ausführungsform der Erfindung.
• Fig. 2 zeigt einen Querschnitt durch ein Segmentmoduls gemäß einer bevorzugten Ausführungsform der Erfindung.
• Fig. 3 zeigt eine weitere bevorzugte Ausführungsform des erfindungsgemäßen Segmentmoduls als Explosionszeichnung.
• Fig. 4 zeigt eine weitere Explosionszeichnung einer bevorzugten Ausführungsform des erfindungsgemäßen Segmentmoduls.

In a further aspect, the present invention relates to a device comprising a segment display or a segment module according to the present invention. In a preferred embodiment, the device is a telecommunications device, a telephone, an answering machine or a telephone system.

• Fig. 1 shows the schematic representation of a segment display according to a preferred embodiment of the invention.
• Fig. 2 shows a cross section through a segment module according to a preferred embodiment of the invention.
• Fig. 3 shows a further preferred embodiment of the segment module according to the invention as an exploded view.
• Fig. 4 shows a further exploded view of a preferred embodiment of the segment module according to the invention.

Fig. 1 shows a schematic representation of a segment display (1) according to a preferred embodiment of the invention. The segment display is a segment display with 2 x 7 segments (10) and comprises a one-piece plastic light guide (2) with 2 x 7 light-conducting elements (3) and a closed surface (7). The closed surface (7) has a rectangular shape with a flat top and has a thickness (8) of about 2 to 4 mm. The segments (10) are designed as trapezoidal depressions in the surface. The top surface (11) of the surface is blackened.

The light-conducting elements (3) are substantially cylindrical in shape and have a circular cross section at the light entry point (4). Toward the light exit point, which is located on the side segments (10), the cross section of the light-conducting elements increases. The light-conducting elements go on the side of the light exit point in the closed surface (7). Furthermore, the segment display comprises a connecting element (9) which enters into a latching connection with the connecting element (13) of the cover (12).

Fig. 2 shows the schematic representation of a segment module (14) according to a preferred embodiment of the invention. The segment module comprises a segment display (1) according to Fig. 1 consisting of a light guide (2), which is composed of light-conducting elements (3) and a closed surface (7). Furthermore, a made of smoked glass cover (12) can be seen, which is attached to the side of the light exit point (5) on the segment display. The attachment is achieved via the connecting elements (9) and (12) of the segment display or the cover.

The segment module further comprises a printed circuit board (17) on which the means for optically separating (15) the individual light-conducting elements (3) are arranged. The means for separating consist of an opaque plastic and separate the light-conducting elements over partial areas as well as the entire length from the light entry point to the transition into the closed surface (7).

Furthermore, light sources (16) are shown, which are designed as 2 x 7 LEDs as. The LEDs are arranged on the circuit board of the device in which the segment module is installed. The segment display (1) with cover (12) and the means for optically separating the light elements (15) mounted on the circuit board (17) form a plug-in connection as shown, in which the light entry points of the light-conducting elements sit directly on the LEDs (16). In addition, a keyboard (18) is mounted on the circuit board of the segment module.

The light generated by the LEDs thus enters the light guide (2) via the light entry points of the light-conducting elements (3) and is along the light paths (6) by means of total reflection in the light-conducting elements from the light entry point to the light exit point (5), with the recessed Segments (10) merges. Here, therefore, those segments under which along their light path (6) a controlled LED is on. At the same time, the means for optical separation (15) prevent blooming effects between the individual light-guiding elements.

Fig. 3 shows a further preferred embodiment of the segment module (14) according to the invention as an exploded view. The segment module is designed as a modular plug-in module for an electrical device that can be plugged into the device via plug-in connections (21). It includes a segment display (1) after Fig. 1 with a cover made of smoked glass (12). The modular plug-in module further comprises a spacer (19), as well as an electrically insulating film (20), which have suitable openings to allow the passage of light from the LEDs.

Fig. 4 shows a further exploded view of a preferred embodiment of the segment module according to the invention. Again, the segment module (14) is designed as a modular plug-in module for an electrical appliance. It includes a segment display (1) after Fig. 1 with a cover made of smoked glass (12). The means for optical separation (15) are mounted on a printed circuit board (17) of the segment module. In addition, a keyboard (18) is mounted on the circuit board. On the circuit board (22) of the electrical device 2 x 7 LEDs (16) are further arranged. Each of these LEDs is located after the mating segment module and circuit board (22) in the plane of the light path from the light entry point to the light exit point in each case a light-conducting element of the light guide.

Claims (14)

1. A segment display (1), comprising a light guide (2) having at least two light-guiding elements (3), which each have a light entry point (4) and a light emission point (5), wherein the light guide (2) has a closed surface (7) on the side of the light emission point (5), wherein the segment display (1) has at least one segment (10),
   characterised in that
   the at least one segment (10) is embodied as an indentation in the closed surface (7).
2. The segment display according to claim 1, comprising 2 x 7 or 2 x 14 segments (10), wherein each segment (10) comprises a light-guiding element (3).
3. The segment display according to claim 1, wherein the light guide (2) consists of a polycarbonate.
4. The segment display according to claim 1, wherein the top face (11) of the closed surface (7) is blackened.
5. The segment display according to claim 1, also comprising a cover (12).
6. The segment display according to claim 5, wherein the cover (12) consists of smoked glass.
7. The segment display according to claim 5, wherein the cover (12) and the segment display (1) can be connected by means of at least one connection element (9, 13).
8. A segment module, comprising at least one segment display (1) according to claim 1, and means for separating the light-guiding elements (15).
9. The segment module according to claim 8, wherein the means for separating the light-guiding elements (15) are impermeable to light.
10. The segment module according to claim 8, wherein the means for separating the light-guiding elements (15) are embodied as a holder for the segment display (1).
11. The segment module according to claim 8, wherein the segment module is embodied as a plug-in module for an electrical device.
12. The segment module according to claim 8, also comprising at least two light sources (16), wherein the light guides (2) are arranged relative to the light sources in such a way that light emitted from one of the light sources can be coupled into one of the light guides (2) and light emitted from the other of the light sources can be coupled into the other of the light guides (2), via the light entry point.
13. An apparatus, in particular a telecommunications apparatus, comprising a segment display (1) according to any one of claims 1 to 7 and/or a segment module according to claims 8 to 12.
14. An apparatus, in particular a telecommunications apparatus, comprising a segment display (1) according to any one of claims 1 to 7, a segment module according to claims 8 to 11 and/or at least two light sources (16), wherein the light guides (2) are arranged relative to the light sources in such a way that light emitted from one of the light sources can be coupled into one of the light guides (2) and light emitted from the other of the light sources can be coupled into the other of the light guides (2), via the light entry point.

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