Scanning unit of an optical position measuring device and optical position measuring device
AssigneeDr. Johannes Heidenhain GmbH
InventorsBarbara Martin, Oliver Schenk, Robert Siegel
Life of this patent
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Abstract
A scanning unit including a light source for illuminating a scale by a light beam and a detector for detecting the light beam which has been modulated by the scale as a function of a relative position between two objects. An inner chamber of the scanning unit in which the light beam extends is closed off in a dust-proof manner against an outer chamber, and the inner chamber is closed off by a transparent body, through which the light beam passes. The inner chamber is connected with the outer chamber via a filter which is dust-proof, but permeable to gas and vapor.
Claims20
A scanning unit, comprising:
- a light source for illuminating a scale by a light beam;
- a detector for detecting said light beam which has been modulated by said scale as a function of a relative position between two objects,
- an inner chamber in which said light beam extends is closed off in a dust-proof manner against an outer chamber of said scanning unit, and said inner chamber is closed off by a transparent body, through which said light beam passes,
- wherein said inner chamber is connected with said outer chamber via a filter which is dust-proof, but permeable to gas and vapor.
A scanning unit, by which a scale, which can be moved relative to the scanning unit in a measuring direction, can be optically scanned, the scanning unit comprising:
- a scanning plate with a first surface facing said scale and a second surface facing away from said scale;
- an electrically conductive opaque layer, which delimits a window, is applied to said first surface, which is electrically connected by a contact element to an electrically conducting body having a reference potential,
- wherein said scanning plate comprises a surface area, which is set back with respect to said first surface and comprises an electrically conducting coating and is in contact with said opaque layer, and said contact element contacts said electrically conducting coating at said set-back surface area.
A position measuring device for measuring a relative position of two objects, the position measuring device comprising:
- a scale;
- a scanning unit which is movable in a measuring direction relative to said scale, said scanning unit comprising:
- a light source for illuminating said scale by a light beam;
- and
- a detector for detecting said light beam which has been modulated by said scale as a function of said relative position between said two objects;
- an inner chamber in which said light beam extends is closed off in a dust-proof manner against an outer chamber;
- an outer chamber that closes off said inner chamber via a transparent body, through which said light beam passes, wherein said inner chamber is connected with said outer chamber via a filter which is dust-proof, but permeable to gas and vapor.
Dependencies are inferred from the claim text.