Optics: image projectors – Light shield – mask – hood – or diaphragm
Patent
1991-02-01
1993-03-23
Cuchlinski, Jr., William A.
Optics: image projectors
Light shield, mask, hood, or diaphragm
353122, 353 46, 359221, G02B 2608
Patent
active
051968754
DESCRIPTION:
BRIEF SUMMARY
The invention is directed to a projection head for a light point on a surface, particularly an assembly surface of an assembly table, for indicating the outfitting location, comprising illuminated from the rear, carrier so as to be movable, and source as light point on the surface with at least one optical element, which is attached to the carrier part so as to be movable, for shifting the light point on the surface, as desired.
A projection head of this type is known from DE-C-27 16 548. The entire lens system or objective 26 is movable linearly in two directions X and Y perpendicular to one another and to the optical axis for the corresponding light point movement on the surface. A holder 16 for the punctiform light source in the form of a pin diaphragm 24, as well as for the rear pin diaphragm illumination 20, is supported at the projection head in the manner of a ball joint, the swivel point of the joint being situated in the aperture of the pin diaphragm. The tubular holder is carried along by the objective via a drag coupling. A sufficient illumination of the pin diaphragm, as well as of the entrance pupil of the objective, is obtained by means of these steps in order to obtain sufficient brightness of the imaged light point also in the corner areas of the projection surface or assembly surface. This known arrangement has proven successful. However, the cost on construction is rather high. Thus, in order to achieve a sufficiently accurate indication of location, imaging optics must be used which are extensively corrected for distortion and therefore relatively expensive. Simple objectives vary among one another with respect to distortion characteristics, which results in inexact imaging. The described steps for illuminating the pin diaphragm and the objective makes the construction more complicated. Further, the construction cost for the operating mechanism for moving the entire, relatively heavy objective in the two cartesian coordinate directions is relatively high due to the required precision and agility of movement.
The object of the invention consists in providing a projection head of the type named in the beginning which has a sharp light point imaging also in the edge areas of the assembly surface and whose construction is simplified.
This object is met in that to the carrier part so as to be stationary, at the carrier part so as to be swivelable, and constructed in such a way that it can be deflected relative to the imaging lens or lens group in the direction of the optical axis as a function of the respective swivel angle of the optical element, of which there is at least one.
The imaging lens or lens group is thus arranged at the carrier part so as to be stationary, so that the illumination of the pin diaphragm and objective requires no particular costly measures. A simple imaging lens or imaging lens group can be used, since the point light source to be imaged remains constantly at the same location on the optical axis. The "image field curvature" is the surface in which are located the image points of the point light source, which are conjugated to form the point light source (substantially stationary object point) and are accordingly sharp-edged, when the beam is deflected by the optical element. The occurrence of this "image field curvature" is unavoidable when using a swivelably supported optical element, of which there is at least one, and would lead to blurred imaging by areas with the usual planar projection surface or assembly surface. The "image field curvature" is at least approximately eliminated by means of the deflection of the point light source in the direction of the optical axis as a function of the respective swivel angle, so that a sharp light point imaging is further ensured.
It has already been suggested to use a laser as a light source and two swivelable mirrors as optical elements which deflect the light beam of the laser and project it onto the assembly surface as a light point (DE-C-27 51 651). The laser ensures a sufficient sharpness of the light point also in th
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patent: 4941739 (1990-07-01), Grudic et al.
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Cuchlinski Jr. William A.
Dowling William C.
RoyoCad Gesellschaft fur Hard-und Software mbH
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