Illumination – Illuminated scale or dial
Reexamination Certificate
1999-03-12
2002-04-30
O'Shea, Sandra (Department: 2875)
Illumination
Illuminated scale or dial
C362S028000, C362S029000, C362S030000, C116S284000, C116S285000, C116S288000, C040S205000
Reexamination Certificate
active
06379015
ABSTRACT:
FIELD AND BACKGROUND OF THE INVENTION
The invention relates to an indicating instrument, in particular for a vehicle, having a pointer which is connected fixed in terms of rotation to a pointer shaft and can be driven by a pointer shaft, a pointer illumination and a dial, the dial having a scale for representing a value of a variable which is indicated by the pointer.
Indicating instruments of the above type are used, for example, as speedometers or rev counters in contemporary motor vehicles and are generally known. The dial of such a pointer instrument has markings for numbers, symbols or scale graduation markings which contrast with the other regions by their optical transparency or their coloring. Such a blade is composed, for example, of a colored, predominantly translucent film which is applied to a light guide. Arranged behind the light guide is a lamp as light source. Using the lamp, light is introduced into the light guide and passes through the dial to a viewer. The pointer here has a pointer shaft which is designed as a light guide and a pointer vane which can be illuminated and is arranged so as to be capable of rotating with this pointer shaft. Therefore, the viewer perceives a pointer, which can be illuminated by means of a light guide, in front of a completely illuminated dial.
A disadvantage with such a pointer instrument is that, for protection against damage and harmful environmental influences, the rotatably arranged pointer has to be arranged behind a cover plate in order to protect it. This plate should be both totally transparent and essentially free of reflections in order to ensure that the dial can be read reliably. These requirements can be fulfilled only by shaping the plate in a relatively complicated way, which at the same time restricts the design possibilities of the dashboard. Furthermore, it is disadvantageous that the cover plate scratches easily, as a result of which it is more difficult to read the dial and a less satisfactory impression is produced. Moreover, it is disadvantageous that the known pointer instrument has a large physical depth.
SUMMARY OF THE INVENTION
The invention is based on the problem of designing an indicating instrument of the type mentioned at the beginning such that is particularly simple and can be read satisfactorily. At the same time, the installation space for the indicating instrument is to be reduced.
This problem is solved according to the invention with an indicating instrument of the type mentioned at the beginning by virtue of the fact that the dial is translucent and the pointer is arranged on the rear of the dial, on the opposite side from a viewer. The cover plate which is necessary according to the prior art can therefore be dispensed with owing to the arrangement of the pointer in a protected position behind the dial. As a result, the outlay on materials and the weight of the display instrument are considerably reduced. In addition, the indicating instrument has a very small installation depth, which is a great advantage in particular in the case of indicating instruments which are provided for installation in dashboards of motor vehicles—as is the reduction in weight. At the same time, the indicating instrument according to the invention provide design possibilities of shape which permit the ergonomic and stylistic desires of the customer to be fulfilled. In addition, the fabrication of the indicating instrument is simplified since it requires fewer components than known indicating instruments.
A particularly advantageous development of the invention is obtained if the dial is diffusely translucent. As a result, the viewer is prevented from seeing the components of the pointer instrument lying behind the pointer, whereas the illuminated pointer itself—at any rate at least its contour—remains visible. It is therefore unnecessary to provide additional means of covering the rear components.
The dial can be read significantly more easily if the surface of the outer side and/or of the inner side of the dial is designed in a reflection-reducing way. As a result, the contour of the pointer can still be recognized even in unfavorable light conditions, obliquely incident light, for example sunlight, having virtually no negative effect on the ease of reading. Reflection-reducing qualities of the surface of the inner side of the dial ensure that light from the illumination of the pointer is not reflected on the dial. A weakening of the luminosity of the pointer is thus avoided.
It is possible to imagine providing the surface of the outer side of the blade with a reflection-reducing film. However, it is particularly cost-effective and simple if, according to one advantageous development of the invention, the surface of the outer side of the dial is dull, which is an effective means of reducing reflections caused by incident light. During the fabrication of the indicating instrument, the dull surface can advantageously be produced in a simple way if the surface of the outer side of the dial has a surface coating which cures with a dull finish, or has a roughened finish.
A favorable embodiment of the indicating instrument is obtained if the dial is an opal plate. As a result shaded areas caused by components at the rear are reliably avoided and a dial with a homogenous appearance is provided. The material of the opal plate for which milk glass is also a colloquial expression, may be a plastic or glass, for example.
The scale could be arranged, as in conventional pointer instruments, on the side facing the viewer. However, in an indicating instrument of the present invention it is advantageous if the dial has a scale which is arranged on the rear side of the dial which is on the opposite side from the viewer. As a result, in the first instance the scale is arranged protected against damage, and secondly the visual impression of the pointer instrument is not affected by labelings on the outside.
In this context, a development of the invention in which the scaling is engraved into the dial is particularly favorable. This design is, in the first instance well protected against damage and, secondly provides the possibility of allowing the scale to have a brightly lit-up appearance by means of an appropriately arranged light source.
According to another advantageous development of the invention, the pointer illumination has a light source which is connected fixed in terms of rotation to the pointer. As a result, the light transmission path in the pointer may be particularly short, which minimizes the light losses.
The indicating instrument is of particularly bright, and thus also at the same time particularly easily readable design if the light source is arranged on a pointer vane of the pointer. In this design, the pointer vane which is designed in this way contrasts in an easily readable way and also makes it possible, for example, to make the dial colored. The light source here may itself be rotatable about an axis of rotation and preferably be designed in the form of a pointer vane, and thus replace the pointer vane.
The pointer can advantageously be designed in a particularly lightweight way if the pointer illumination has a fixed light source and if light which is emitted by the light source can be injected into the pointer. In this way, a pointer drive which drives the pointer, for example a measuring mechanism, can be designed to generate only a small amount of torque. It is possible here for light which is emitted by the light source to be injected into a pointer shaft which is designed as a light guide, and to be passed on from there into the pointer vane; however, there may also be provision to inject the light directly into a pointer head and direct it from there into the pointer vane.
According to another advantageous development of the invention, a light guide is arranged in the transmission path of the light which is emitted by the light source, between the light source and the pointer, so that the light source does not have to be spatially assigned to the pointer, but rather may be arranged freely in the
Bauer Benoit
Döbler Michael
Pöhlmann Frank
Turck Heinz
Wilhelm Heinz Günther
Farber Martin A.
Negron Ismael
O'Shea Sandra
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