1. Field of the Invention
The invention relates to a roll tape measure, consisting of a housing upper part and housing lower part, a perforation in the housing upper part for a release button, a spring drum with tension spring placed in the housing, whose end is connected with the housing lower part, a back stop for the tension spring, a flexible tape measure rolled up on the spring drum, and a release catch that can be actuated by the release button.
2. Related Technology
A roll tape measure of this type can be seen, for example, in DE utility model 69 25 460. In these structural shapes, the release button is connected or integrated with an actuating pin which, on its end in the housing, acts on a release element with a pawl. In this case, the release button must exhibit a smoothly and cleanly finished surface, so that it is guided freely movable in the axis in its lengthwise direction. To achieve this, the release button is designed integral with its end-side stop device as a mushroom-shaped control element. But the release button projects in this case from the housing surface, so that malfunctions may still occur.
A second roll tape measure of this type can be seen in DE-PS 25 45 203, in which both the housing upper part and the housing lower part exhibits surface parts which are cut out from the housing surfaces and connected by remaining crosspieces with the respective housing part. The surface parts are connected with one another by a pin centrally placed in the housing axis, so that the restoring forces of the crosspieces act in opposite directions. The centrally placed surface part cut out in the housing upper part is designed as a release button, while the surface cut out in the housing lower parts acts as a release catch, which is covered toward the outside by a plate. Relative to the above-indicated known roll tape measure, the release button no longer projects from the housing surface, but forms a relatively smooth surface. The number of individual parts used is relatively small, but it is necessary to provide both housing parts with indentations and to design the connecting crosspieces elastically. To achieve the elasticity of the connecting crosspieces, which are an integral component of the housing, a special selection of the plastics to be used is necessary, so that here only a relatively limited leeway relative to the plastic materials to be used is provided. Further, the cut-out surface parts exhibit relatively long gaps, by which dust and dirt particles can penetrate the interior of the housing.
In practice, it has further been shown that a user of such a roll tape measure does not immediately recognize the central arrangement of the release button as such and incorrectly considers the latter to be the axis of the system.