EP1505560A2 - Light guide member for multisegment displays - Google Patents

Abstract

The light conducting component has a mask into which a light conductor (3) per segment is fed with a cross-section with the shape of the segment and that is manufactured using 2k injection molding technology. A continuous air gap (20) is formed between the mask and the light conductor. The dimension of the air gap is in the micrometer range. Independent claims are also included for the following: (a) an optical assembly with an inventive device (b) a domestic machine with an inventive optical assembly (c) and a method of manufacturing an inventive light conducting component.

Description

The present invention relates to an optical fiber device having a light entrance side and a Light exit side for multi-segment optical displays, comprising a mask in which Each segment is guided by a light guide in the form of the segment, using 2K injection molding technology is manufactured, and a corresponding optical assembly, which is for a multi-segment display is set up a home appliance with such an optical assembly and a method for manufacturing the optical fiber device in 2K injection molding.

It is known for number displays in household appliances 7-segment displays with LED display to use. These LED displays are available with different digit heights, Display colors and number of digits with and without decimal point available. The LED displays have on their underside connection pins, which are for electrical connection of the LED display plugged into connection holes of a printed circuit board and soldered there become. For household appliances, the 7-segment displays are generally behind one Window positioned in a panel of the household appliance. The disadvantage here is that the fixed height of the LED displays the installation depth of the PCB behind the panel sets. Due to requirements of the glare design or the mechanical construction of the Aperture may be necessary, the installation depth of the circuit board behind the panel too change. An increase in the height of the LED displays is by extending the Connection pins or by an additional display socket only limited possible, so that the display quality deteriorates with larger installation depths. A reduction the height is usually not possible at all.

From DE 101 12 640 C1 is a display device for household appliances with AnzeigeSegmenten known in the juxtaposed light guide in the form of light fingers pass through guide channels in guide bodies. The display device is composed along the Lichtleitweges of several guide bodies, wherein the juxtaposed light fingers due to production by a photoconductive plate are connected. This has the disadvantage of having this connection Light is coupled into neighboring segments, causing light disturbances in the individual Segments arise that degrade the display quality. That's why it's necessary Cover the display area with a contour shutter to avoid the light interference cover and thus achieve sharper contours.

From the control of a washing machine of the company AEG is a light guide component for optical Multi-segment displays known, consisting of two plastic components (2K) in 2K injection molding is made. It is first made of a first plastic component made a mask, then injected into the second plastic component as a light guide becomes. The material selection is subject to the condition that the mask during injection of the optical fiber material may not deform significantly to the light guiding property of the light guide does not deteriorate. The known optical fiber component has a Mask made of glass fiber filled polyamide and a light guide made of polymethylmethacrylate on. The disadvantage of this combination of materials that the light guide with the Mask connects at least partially adhesive, whereby the light-guiding property of the light guide and thus the display quality is reduced. In addition, due to the processing characteristics of the high glass fiber filled polyamide the fine structuring and the length of the fiber optic device severely limited. Consequently, and also because of relatively high light losses in the optical fiber component only a short Lichtleitlänge is possible and thus limited the installation depth of the circuit board behind the panel.

The invention has the object of providing a cost-effective optical fiber component for optical Multi-segment displays to provide, with the installation depth of the circuit board designed variably behind a display surface with simultaneously high display quality can be.

This object is achieved in a light guide component of the type mentioned, characterized that between the mask and the light guide throughout an air gap, in particular is formed in the micrometer range. Through this air gap, light that is in propagates the optical fiber, totally reflected at the interface to the air gap, whereby the Light continues to be guided in the light guide and is not absorbed by the mask material. To this It is possible to keep the light losses low for light guides of great length, so that on the display surface, a high luminance and thus a high display quality is reached.

According to a preferred embodiment it is provided that the mask material a light-tight, easy-flowing material with a low volume shrinkage during the cooling process is. In particular, the mask material is a liquid crystalline polymer (LCP), such as Vectra. Due to the processing properties of this mask material is a production of long and filigree masks possible. This has the advantage that Fiber optic components can be manufactured with a large length, so that at large Mounting depths of the circuit board behind a display area, the light using the light guide component can be led to the display surface, creating a high quality display is achieved. Furthermore, despite the great length of the mask and thus the optical fiber component realized in this mask material a small width of the individual segments and thus in addition to an improved visual appearance of the multi-segment display also a high display quality can be achieved.

According to a preferred embodiment, it is provided that the optical waveguide material a transparent amorphous plastic, in particular polymethyl methacrylate (PMMA) is. This optical fiber material has the advantage that it with the mask material LCP no Connects and shrinks strongly when cooled. Thus, during the cooling process can the finished sprayed fiber optic device between a continuous air gap Forming light guide and mask. That the air gap is due to a higher volume shrinkage of the optical fiber material relative to the mask material during the cooling process formed and is thus largely independent of the manufacturing process, resulting in a high process reliability leads.

Furthermore, PMMA has the advantage that it has a much lower melting point than the mask material LCP has. Thus, in the method of manufacturing the optical fiber device in 2K injection molding the production parameters to the melting temperature the mask material are adapted such that a melting of the mask material upon injection of the optical fiber material into the forming mask to a minimum is reduced. This has the advantage that the light guide exactly in the predetermined by the mask Optical fiber geometry is formed, since the optical fiber material, the mask material during the manufacturing process does not melt and thus deformed, creating a high Quality of the light pipe and thus a high display quality can be achieved.

Advantageously, in the process for manufacturing the optical fiber component in 2K injection molding the optical fiber material via a ground pad at the light exit side in the mask injected. In this way, it is possible closely adjacent segments with Fill fiber optic material. In addition, this has indirect injection of the optical fiber material in the segment of the mask has the advantage that the light guide streaks and made bubble-free and thus a high quality of the light guide can be achieved. Through this mass cushion forms the light guide material on the light exit side of the Lichtleiterbauteils a photoconductive plate, with the particular light guide each Segments is connected. This has the advantage that through the plate of the light guide each Segment is fixed. In particular, the photoconductive plate can be manufactured in such a way that it has a rough and / or a textured surface. Through the rough surface the leaking light is scattered so that the light distribution of each segment becomes even. Due to the structured surface, the structure of each Segments are highlighted, which makes the display even from oblique angles is clearly visible.

Preferably, at least one injection point of the optical waveguide material is between the Segments arranged. In this way, the Lichtleitmaterial evenly in the individual segments are injected. Another advantage is that the injection point the light emission from the individual segments does not bother, creating a homogeneous Light distribution for each segment can be achieved.

According to a preferred embodiment it is provided that the photoconductive plate protrudes laterally over the mask. In particular, it is provided that the shape of the plate adapted to a panel. This has the advantage that the optical fiber component form fit mounted in the panel and thus dispensed with a glass cover can. Advantageously, locking elements for fastening the optical fiber component are on the plate formed on a housing part and / or on a diaphragm part, so that a optical assembly, which is set up with the optical fiber component for a multi-segment display is, by means of these locking elements of the optical fiber component to the housing or on the aperture can be locked, for example, a household appliance. In this way is an assembly of the optical fiber component and thus the optical assembly on special easy way possible.

Preferably, the optical fiber is polished at the light entrance side. This way a can Scattering of the incoming light can be reduced, producing more light in the light guide arrives. This has the advantage that even with long light guides a display with high Luminance can be achieved.

In a preferred embodiment it is provided that the optical fiber component at the Light entry side for each segment a recess for enclosing a light-emitting Component, in particular for enclosing a SMD LED has. In this way may be in an optical assembly that contains SMD LEDs and in which such a fiber optic device is used, on the one hand a lot of light in the respective light guide On the other hand can be a coupling of the light in the light guide of another Segments are avoided. This has the advantage that for each segment only the light the associated light-emitting component passes into the light guide, whereby a particularly good optical separation of the individual segments is achieved from each other. A Particularly good coupling of the light from the SMD LED into the light guide can thereby be achieved that the recess of the optical fiber component containing the SMD LED, filled with a transparent potting compound and / or with diffuser material. On in this way the number of optical transitions is reduced and thus the light loss minimized. When using diffuser material, the light may be from the light source due to the scattering in the diffuser material particularly evenly distributed in the light guide of the respective segment are coupled.

Advantageously, the mask is cuboid and has locking elements for attachment the optical waveguide component on a printed circuit board and / or on a housing part, in particular on the light entry side. In this way, the optical fiber device can be particularly simple be mounted on the circuit board. In particular, in the optical assembly, the Optical fiber component at the light entry side are locked with an electronic circuit board on the SMD LEDs are arranged. Advantageously, at two diagonally opposite Corners one of the light entrance side associated square surface each one Locking element arranged so that it starts from one to the assigned, in parallel directed to the light guides cuboid edge is directed freely movable on the circuit board, and the two remaining, parallel to the light guides edges each have a linear, formed in a negative mold to the locking element recess on, which can be positively connected with the latching element of an adjacent light guide component is. This has the advantage that a plurality of optical fiber components form fit mounted side by side on the printed circuit board and thus with several of the same optical fiber components multi-digit displays can be realized.

Preferably, the optical fiber material and / or the mask material is colored in itself. In particular, it is provided that for the use of the optical fiber component in a Household appliance of the light guide and / or the mask according to the housing or the Aperture is colored in itself. This has the advantage that the optical fiber component and thus the optical assembly with the optical fiber component optically to the housing or the aperture can be adjusted so that only the display on the display surface visible is.

The optical fiber device is preferably used in optical assemblies that are suitable for multi-segment displays, especially for 7-segment displays. advantageously, Such assemblies are used as display devices in the housing or the Panel of household appliances used, as in this way modifications of the housing or Blend designs are feasible without the circuit board or the electronics must be changed.

The invention and its developments are described below with reference to drawings explained in more detail:

Fig.1

eine schematische perspektivische Ansicht auf die Lichtaustrittseite eines Lichtleiterbauteils für eine optische 7-Segmentanzeige mit Dezimalpunkt,

Fig.2

eine schematische perspektivische Ansicht auf die Lichteintrittseite des Lichtleiterbauteils gemäß Figur 1,

Fig.3

einen Längsschnitt entlang einem Lichtleiter durch eine optische Baugruppe, die für eine optische 7-Segmentanzeige eingerichtet ist, und

Fig.4

einen Längsschnitt entlang einem Lichtleiter einer optischen Baugruppe für eine optische Mehrsegmentanzeige mit einem Blendenteil an der Lichtaustrittseite.

Show it

Fig.1

a schematic perspective view of the light exit side of a light guide device for a 7-segment optical display with decimal point,

Fig.2

3 is a schematic perspective view of the light entry side of the optical waveguide component according to FIG. 1,

Figure 3

a longitudinal section along an optical fiber through an optical assembly, which is adapted for a 7-segment optical display, and

Figure 4

a longitudinal section along an optical fiber of an optical assembly for a multi-segment optical display with a shutter member on the light exit side.

According to Figure 1 and Figure 2 is an exemplary embodiment, an optical fiber device 1 for a optical 7-segment display with decimal point shown schematically. The fiber optic device 1 consists of a cuboid base body 2, which has a mask M with parallel Channels K, wherein the mask M in cross section of a 7-segment display with Decimal point corresponds. In the channels K of the main body 2 is for each of the seven Segments of the 7-segment display depending on a light guide 3 with a segment-shaped cross-sectional area and for the decimal point, a light guide 4 having a circular cross-sectional area from a light entrance side 5 to one of the light entrance side 5 opposite Light exit side 6 out. At the light exit side 6, the light guides 3, 4 open in a photoconductive plate 7, which is arranged on the base body 2 and a planar Surface 8 has. The light guides 3, 4 are shown in FIG. 1 by dashed lines, since they are under the light-conducting plate 7. Each of the segmental light guides 3 has a width B and the circular light guide 4 has a diameter D, both especially less than or equal to one millimeter. The individual segmental Light guides 3 are separated from each other by webs S of the mask M of the Light entrance side 5 is separated up to the light exit side 6. At the light entry side 5 points the light guide component 1 in the region of each of the light guides 3, 4 recesses 9 for receiving of light-emitting components. These recesses 9 are from each other so far removed that the webs S of the mask M are in between.

On the main body 2, which is in particular cuboid, is at two diagonally opposite corners of the light entrance side 5 associated square surface each latching element 11 is arranged such that, starting from one at the associated, Parallel to the light guides 3, 4 lying cuboid edge 10 on the light entrance side 5 of the optical fiber component 1 protrudes and is free to move. At the two remaining, to the light guides 3, 4 parallel edges 12, the base body 2 each one line-shaped recess 13 which is formed positively to the locking elements 11 is. The curvature 14 of the locking elements 11 corresponds in its negative shape of the curvature 15 of the recesses 13. In addition to the light guide component 1 can thus another identical Fiber optic component 1 are arranged without gaps (not shown), since the locking element 11 positively fits into the recess 13.

FIG. 3 shows a section along the light guides 3, 4 through an optical assembly 16, which is set up for the optical 7-segment display. The optical assembly 16 includes the optical fiber device 1 and a printed circuit board 17 with SMD LEDs 18 as light-emitting Components. The light guide component 1 is with its locking elements 11 in holes 19 of Printed circuit board 17 locked. The SMD LEDs 18 are from the recesses 9 of the optical fiber device 1, so that emitted by the SMD LEDs light only in through Arrows marked direction along the light guide 3, 4 can propagate. An overcoupling of Light of the SMD LED in adjacent light guide 3, 4 is avoided by that on the Light entry side 5, the optical fiber component 1 between the recesses 9 positively with the circuit board 17 closes. These recesses 9 can be used in particular of SMD LED chips 18 without LED housing with a transparent potting compound filled on the one hand protects the SMD LED chips 18 from damage and on the other hand improves the light coupling of the emitted light in the light guide 3, 4, because the number of optical transitions is reduced and the transparent potting compound can be chosen such that their optical refractive index to that of the optical waveguide 3, 4th is adjusted. The recesses 9 can also be filled with diffuser material, by which light emitted from the SMD LEDs is scattered, so that the light with a uniform distribution in the light guides 3, 4 occurs. In general, others can light-emitting components are used, such as LEDs or incandescent lamps, the dimensions of the optical fiber component can be adjusted accordingly.

Between each of the light guides 3, 4 and the main body 2 is continuous in the channels K. over the entire length L of the light guide 3, 4 from the light entrance side 5 to the Light exit side 6, an air gap 20 is formed, in particular of an order of magnitude of micrometers. Through this air gap is emitted from the SMD LED 18 and on the light entrance side 5 in the light guide 3, 4 coupled light, located in the Light guide 3, 4 propagates and which is incident on the air gap 20 in the light guide 3, 4 back reflected. In this way, the light is guided in the light guide 3, 4 and not of the main body 2 absorbed. Thus, it is possible with optical fibers 3, 4 with great length L to keep the light losses low. At the light exit side 6, the photoconductive plate 7 shows a structured surface 21 in FIG. 3, in which the individual segments 22 of the 7-segment display are highlighted in plastic. The light leaves the individual segments 22 at the light exit side 6 thus at different angles to the longitudinal direction the light guide 3, 4, whereby it is well visible even at these angles.

FIG. 4 schematically shows a section along the optical waveguide 3 through a diaphragm part 23 an optical assembly 16, which according to another embodiment the invention is adapted for a multi-segment optical display. The light-conducting Plate 7 extends in its planar extension beyond the base body 2 and has a curved shape, which is adapted to the curvature of the diaphragm part 23. The Outer contour can, as shown, a rectangular shape or any other desired shape exhibit. Furthermore, 7 locking elements 24 are integrally formed on the photoconductive plate formed, which are bounded at the light exit side 6 of the plate 7 and parallel to Point light guide component 1 to the light entry side 5. At the diaphragm part 23 are counter-locking elements 25 formed with which the locking elements 25 for mounting the optical Assembly 16 are latched to the panel part 23.

The optical fiber component 1 is made in 2K injection molding of two plastic components (2K) made. First, the base body 2 with the mask M is made of an opaque, easy-flowing material with a low volume shrinkage during the cooling process made according to the invention, a liquid crystalline polymer (LCP), such. Vectra® is. Due to the processing properties of this liquid crystalline polymer is the production of long and filigree masks M possible. In this mask M will be then the optical fibers 3, 4 injected from a second translucent plastic, the does not connect with the plastic of the mask M and according to the invention a transparent amorphous plastic, in particular polymethyl methacrylate (PMMA) is. The PMMA has a lower melting point than LCP, allowing the temperature of the PMMA melt during the manufacturing process can be chosen so that the mask M If possible, do not melt when injecting the PMMA. The PMMA is over a mass cushion P injected at the light exit side 6 in the mask M, which is the photoconductive Plate 7 forms. In Figure 1 are centrally between the individual light guides 3 two injection points A shown in dotted lines through which the ground pad P filled with PMMA becomes. Starting from this mass cushion P PMMA is in channels K of the mask M pressed. During the cooling process of the finished sprayed optical fiber device 1, a volume shrinkage occurs on. This is at an LCP, such as Vectra® very low, while the Volume shrinkage of PMMA in the order of 0.6%. Thus, the volume shrinkage of the optical fiber material relative to the mask material during the cooling process significantly higher, resulting in a over the entire length L of the light guide 3, 4 continuous air gap 20 between light guide 3, 4 and mask M is formed. On In this way, the formation of the air gap 20 is largely of the manufacturing process independent, resulting in a high process reliability for the production of optical fiber components 1 results.

According to the invention, the optical fiber component 1 with a ratio of length L to width B or diameter D of the optical fibers 3, 4 are made, which is greater than 13 or in of the order of 30 lies. In particular, the width B or the diameter D the light guide 3, 4 is less than or equal to 1 millimeter and the length L of the light guides is 35 millimeters be. In particular, a digit height of the 7-segment display of 10 millimeters realized with a segment width of 1 millimeter and a fiber optic length of 35 millimeters become. However, other dimensions of the optical waveguide component 1 are also possible.

According to the invention, the plastic for forming the light guides 3, 4 or the light-conducting Plate 7 and / or the plastic to form the body 2 dyed in it be. In particular, the light guides 3, 4 and the photoconductive plate 7 in color be adapted to the diaphragm part 23 or to a housing part such that segments of the Multi-segment display only visible when illuminated. In particular, the light-emitting Components are chosen such that they emit colored light, so that a contrast in color between illuminated and unlit segments of the Multi-segment display results.

Claims (36)

Optical waveguide component having a light entry side (5) and a light exit side (6) for multi-segment optical displays, which has a mask (M) in which for each segment a light guide (3, 4) with a cross section in the form of the segment is guided 2K injection molding is made, characterized in that between the mask (M) and the light guide (3, 4) is formed throughout an air gap (20). Optical fiber component according to claim 1, characterized in that the air gap (20) has an extension in the micrometer range. Optical waveguide component according to claim 1 or 2, characterized in that the air gap (20) is formed by a higher volume shrinkage of the optical waveguide material relative to the mask material during the cooling process. Optical fiber component according to one of claims 1 to 3, characterized in that the mask material and the optical fiber material do not connect to each other in the manufacturing process. Optical fiber component according to one of the preceding claims, characterized in that the optical fiber material does not melt the mask material during the manufacturing process. Optical fiber component according to one of the preceding claims, characterized in that the mask material is a light-tight, easily flowing material with a small volume shrinkage during the cooling process. Optical fiber component according to claim 6, characterized in that the mask material is a liquid crystalline polymer. Optical fiber component according to one of the preceding claims, characterized in that the optical fiber material is a transparent amorphous plastic. Optical fiber component according to claim 8, characterized in that the optical fiber material is a polymethylmethacrylate. Optical waveguide component according to one of the preceding claims, characterized in that the ratio of length (L) to width (B) or diameter (D) of the optical waveguide (3, 4) is greater than 13 or on the order of 30. Optical waveguide component according to one of the preceding claims, characterized in that the width (B) or the diameter (D) of the optical waveguide (3, 4) is at most 1 mm and / or the length (L) of the optical waveguide (3, 4) is 35 mm , Optical waveguide component according to one of the preceding claims, characterized in that the optical waveguide material forms a light-conducting plate (7) on the light exit side (6). Optical fiber component according to claim 12, characterized in that the light guide (3, 4) of each segment is connected to the plate (7). Optical fiber component according to claim 12 or 13, characterized in that the plate (7) has a rough and / or a structured surface (8, 21). Optical fiber component according to one of Claims 12 to 14, characterized in that the plate (7) projects laterally beyond the mask (2, M). Optical fiber component according to one of claims 12 to 15, characterized in that the plate (7) is curved cylindrically or spherically. Optical fiber component according to claim 16, characterized in that the shape of the plate (7) is adapted to a diaphragm (23). Optical waveguide component according to one of claims 12 to 17, characterized in that latching elements (24) for fastening the optical waveguide component (1) to a housing part and / or to a diaphragm part (23) are formed on the plate (7). Optical waveguide component according to one of the preceding claims, characterized in that the optical waveguide (3, 4) is polished on the light entry side (5). Optical waveguide component according to one of the preceding claims, characterized in that the optical waveguide component (1) has on the light entry side (5) a recess (9) for enclosing a light-emitting component (18) for each segment. Optical fiber component according to claim 20, characterized in that the recess (9) is designed to surround an SMD LED (18). Optical fiber component according to one of the preceding claims, characterized in that the mask (2, M) is parallelepiped-shaped and has latching elements (11) for fastening the optical fiber component (1) to a printed circuit board (17) and / or to a housing part. Optical fiber component according to claim 22, characterized in that the latching elements (11) are arranged on the light entry side (5). Optical waveguide component according to claim 22 or 23, characterized in that arranged at two diagonally opposite corners of one of the light entrance side (5) square surface per catch element (11) so that it starting from one of the associated, parallel to the light guides (3 , 4) lying parallelepiped (10) is directed freely movable on the circuit board (17), and that the two remaining, to the light guides (3, 4) parallel edges (12) each have a linear, in a negative form to the latching element ( 11) formed recess (13) which is positively connected with the latching element (11) of an adjacent light guide component (1). Optical fiber component according to one of the preceding claims, characterized in that the optical fiber material and / or the mask material is colored in itself. Optical assembly comprising an optical fiber component according to one of claims 1 to 25, which is set up for a multi-segment display. Optical assembly according to claim 26, characterized in that the multi-segment display is a 7-segment display. Optical assembly according to claim 26 or 27, characterized in that it contains SMD LEDs (18). Optical assembly according to claim 28, characterized in that the recess (9) of the optical waveguide component (1) comprising the SMD LED (18) is filled with a transparent potting compound and / or with diffuser material. Optical assembly according to claim 28 or 29, characterized in that the optical fiber component (1) is latched on the light entry side (5) with a printed circuit board (17) on which the SMD LEDs (18) are arranged. Domestic appliance comprising a housing or bezel (23) with an optical assembly (16) according to any one of claims 26 to 30. Domestic appliance according to claim 31, characterized in that the coloring of the light guides (3, 4) and / or the mask (2, M) is adapted to the housing or the panel (23). Domestic appliance according to claim 31 or 32, characterized in that the optical assembly (16) by means of latching elements (24) of the optical fiber component (1) on the housing or on the diaphragm (23) is latched. A method for producing a fiber optic device according to any one of claims 1 to 25 in 2K injection molding, characterized in that the manufacturing parameters are adapted to the melting temperature of the mask material such that a melting of the mask material upon injection of the optical fiber material into the mask (M) to a minimum is reduced. A method according to claim 34, characterized in that the optical fiber material is injected via a ground pad at the light exit side in the mask (M). A method according to claim 35, characterized in that at least one injection point (A) of the optical waveguide material is arranged between the segments.

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