Illuminated Serrated Wheel

1. Field of the Invention

The present invention relates to a control knurl for actuating an appliance, in particular for the rotary adjustment of a potentiometer in automotive vehicles.

2. Description of the Art

A knurl of this type is disclosed in the applicant's German patent application No. 38 08 770. Control knurls of this type must permit being manipulated even if the passenger compartment is dark. Therefore, the dial setting of the potentiometer is illuminated from the inside. Such illumination permits not only recognizing the positioning of the control knurl in the dark but also its respective setting. If needed, adjustment changes can be made.

Because the number of operable adjustment elements on the control panel is constantly rising, it is desired to minimize the energy needed for the dial illumination, while sufficient visibility is ensured in addition. Therefore, one requirement is to minimize, to the extent possible, any light loss which the beams of light suffer on their way to the dial indicating instrument.

The present invention is a control knurl. The principle of the present invention is directed to minimizing light loss of the light guide inside the knurl by largely coating the outside surfaces of the light guide with a reflecting (white) plastic coating. In this arrangement, that surface is left blank which is used to introduce the light into the light guide. Under certain circumstances, other surfaces are also left blank, in case this is considered appropriate for the mode of operation of the control knurl.

To minimize the loss surfaces of the light guide where the light might leak inadvertently, the light guide should have a shape which is as uncomplicated as possible. In the present case, light beams which enter axially into the light guide are emitted at a radially circumferential surface. The light beams are then introduced into the cross-sectional surface of a first portion of the light guide and redirected radially outwardly through a second portion until the light beams extend radially outwardly within a third portion. It is preferred that the individual portions are spatially circumferential, with the result that a large number of light-scattering surfaces are eliminated, which would prevail, for example, if the second portion consisted of generally radially extending struts.

Further, the outwardly circumferential surface permits the provision of an inwardly illuminated circumferential strip on the peripheral contour of the knurl on which appropriate markings can be made at any location desired.

Accordingly, the second portion has a circumferential surface which is inclined by 45 degrees with respect to the axis of light beam entry. The inside peripheral surface is configured so that the light beams which are introduced into the light guide in parallel to the axis of rotation of the control knurl are reflected on the inside peripheral surface of the truncated cone. Thus, the angular position of the wall is chosen so that it acts like a mirror for the beams which are impinged within the light guide. This is important, as will still be explained hereinbelow, inasfar as there is no need to apply a (white) protective coating at this point.

To prevent disturbing beams of light from being directed into the light guide from the outside, a second, preferably black, coating covers the first coating. However, it is important that the dark, second coating is not in direct contact with the light guide, because it would not reflect the beams of light which emit from the light guide, but rather take them up and become warm or heated as a result. On the other hand, the advantage of the dark, second coating is that soiling of the control knurl, due to its usage, is not visible on its surface. Still another special advantage of the second coating is that the coating can additionally be configured as an operating surface. It is preferred that this operating surface is a knurl which is adjacent to the illuminated dial and mechanically connected to it. By turning the knurl surface, which has the shape of a cylinder jacket, the dial is also turned so that the setting of the electrical appliance, for example, a potentiometer, is visible from the illuminated value set.

Preferably, the knurl surface is cast to the second coating and made of the same material. Through a ring knob, it is prevented that the operating surface, when worn off, changes its color in points. Such a risk could be imminent if the operating surface were made of the first, light plastic material and the operating surface were only overcoated with a dark color.

Black-ink viscous plastics may be used as a material for the knurl and the second coating. The choice of a highly resistant material is also important. According to these features, a toothed wheel which can be used to drive a gearing is still machined into the second plastic coating. This permits adapting the rotary movement of the control knurl to any desired rotary movement for the operation of an electrical unit. This increases the versatility of the control knurl.

To provide a durable connection between the second coating and the first coating or the light guide, at least one web is used as a preferred aspect of the present invention.

The rigidity of the second plastics may further be utilized for shaping a support element for the mounting support of the control knurl in addition. The inside surface or the outside surface of the bearing ring can be used for the mounting support.

Tests have shown that the setting dial on the control knurl is best visible in the dark if the markings include illuminated symbols or figures. Accordingly, the dial display which encompasses the peripheral surface of the light guide is coated with black varnish, and the symbols and marks desired as illuminated markings are made visible by removing the varnish or leaving parts blank. This may, e.g., be carried out by laser exposure. To increase the visibility, the circumferential peripheral surface of the light guide is coated with a thin coating of the white, first plastics, and black varnish is only then applied. The white, first coating illuminated from the inside will radiate outwardly by way of markings where the varnish coating was removed from the first, white plastic coating.

One important solution involves improving the mirror effect on the specular limit boundary which is used to redirect the beams that are introduced in an axial direction into radially extending beams. In this way, a largest possible portion of the introduced beams is transported to the circumferential surface of the control knurl. The improved mirror effect of the boundary surface contributes greatly to avoiding light loss in the deflection area.

The loss of light energy can be further reduced when the light guide is kept free of the protective coating on the boundary surfaces used for mirroring. This should be done in particular in the area of the boundary surface where the light beams which enter in the vicinity of the longitudinal axis of the light guide are redirected in a radial direction.

One embodiment of the present invention will be explained hereinbelow making reference to the accompanying drawing. In the drawing:

FIG. 1 is a cross-sectional view of a control knurl according to the present invention; and

FIG. 2 is a side view of the control knurl of FIG. 1.

The FIG. 1 embodiment shows a control knurl 1 in a cross-section. The core of the control knurl 1 is a light guide 2 that is composed of three portions. The first portion 3 has the shape of a circular cylinder with the diameter D1. The first portion is succeeded by a second portion 4 which generally has the shape of a hollow truncated cone. Adjacent to the truncated cone is a third portion 5 which generally has the shape of a circular ring. It is important to the present invention that the outside surface of the light guide 2 is largely coated by a protective coating of white plastic which reflects the light beams directed to the boundary coating of the light guide, thereby preventing any inadvertent escape of light from the light guide. The light guide 2 can be made highly transparent from Makrolon, and Makrolon White can be used for protective coating 7. Protective coating 7, in turn, is covered by a second coating 8 which can consist of dark or black dyed Pocan. The second coating 8 prevents the entry of extraneous light into the light guide 2 where it is not desired. Second coating 8 includes a circumferential projection 10 which has the shape of a ring knob and is provided with a milled edge 11. The outside circumferential surface of the ring knob with the milled edge 11 is used as an actuating surface for the control knurl which is rotatable (not shown) about an axis of rotation 12. The plastic material used for making the ring knob 10 or the second coating 8 may be Pocan Black. An associated electrical appliance is adjusted in an appropriate manner by actuating the control knurl 1. Such adjustment is effected by way of a gearing in the present embodiment. A gear wheel 13 machined into the second coating 8 interacts with the gearing. The tooth configuration 14 to be seen in the FIG. 2 embodiment can extend around a full circle, or only about part of a circular arc. To rigidly connect the second coating 8 to the protective coating 7 and the light guide 2, one or more webs 15 are provided which project through the protective coating 7 or the light guide 2.

One important feature of the present invention includes the production of the inside peripheral surface 17 of the second portion 4 which extends in an axial direction over the diameter D1 so that the total light beams which enter into the diameter D1 are reflected from the inside peripheral surface 17 of the second portion 4. This boundary surface acts like a mirror. Therefore, it is not suitable to cover the peripheral surface with protective coating 7. The inside peripheral surface 17 of a conical recess in the second portion 4, thus, acts as a reflecting boundary surface by which the beams of light which enter into the portion 3 in the direction of the longitudinal axis 12 are reflected in a radial direction to the annular portion 5. Thus, the mirror effect of the conical recess in the second portion 4, the boundary surface 17 of which acts as a mirror of the beams of light, may be greatly improved because a boundary surface between the air and the material of the air guide is produced. The great reflecting ability of the boundary surface 17 is especially important in the area close to the longitudinal axis 12 because here is the center of the beams of light introduced into the first portion 3.

In this way it is possible to provide a bore surface 18 with respect to the two coatings 7, 8 which can be used as a pivot bearing for the control knurl 1. A bearing ring 19, shaped to the second coating permits increasing the bore surface still further and, thus, reduces the bearing surface or the load on the bearing surface.

It can be seen in FIG. 1 that the outside peripheral surface 20 of the protective coating 7 is not covered by another coating. This outside peripheral surface is the base surface of a dial. In order that it is as dark as the ring knob 10 with its milled edge 11, the peripheral surface 20 is entirely covered by a black varnish (not shown). The desired dial symbols or letters or figures are provided in the varnish by way of laser exposure. The symbols will appear the brighter, the deeper they are worked out from the varnish and the underlying protective coating. However, part of the protective coating 7 will normally be maintained to make the desired symbols appear bright and glare-free. In this sense, the protective coating acts as a diffusing lens which is conventional in optical systems and evenly distributes the illuminating power.

In total, it makes sense to keep the entry surface into the light guide as large as possible. This entry surface is defined by the diameter D1 which, in the present embodiment, is in the range of half the diameter of the outside peripheral surface 20, yet somewhat smaller in the present case. Further, it is appropriate to position the webs 15 in areas where no dial symbol will appear because the light guide is impaired in these areas, as can be seen in the drawing.