Geometrical instruments – Distance measuring – By flexible tape
Reexamination Certificate
1999-07-15
2002-01-08
Fulton, Christopher W. (Department: 2859)
Geometrical instruments
Distance measuring
By flexible tape
C033S492000, C033S809000, C033S465000
Reexamination Certificate
active
06336277
ABSTRACT:
The invention relates to a measuring stop device for a distance-measuring apparatus which can be held in the hand, according to the features described herein.
GB-A-499819 discloses a meter measure having a steel tape which can be rolled up, the extensive rear measuring stop of which measure can be swivelled out upwards by rotation about an axis parallel to the measuring direction. With a measuring stop swivelled out upwards and with the meter measure placed on the floor, it is possible to make contact with a bowling ball at the height of its radius and to carry out a distance measurement.
The optoelectronic distance measuring apparatus disclosed in WO 94/27164 or described in the “Distol” instructions for use from Leica AG, 9435 Heerbrugg, Switzerland, in 1994 is a hand-held measuring apparatus with which distances to an object point can be measured optically. The distance to the object point is measured either from a front or from a rear measuring stop of the distance-measuring apparatus. The measuring stops used are in general the front and rear housing surfaces of the distance-measuring apparatus, which make a right angle with the measuring direction. The two measuring stops are each coordinated with a separate measuring key on the key panel of the measuring apparatus, the pressing of which initiates a corresponding distance measurement and shows the measured distance value on a display.
Such optoelectronic distance measuring apparatuses are predominantly used in surveying in the building industry. A semiconductor laser diode emitting in the visible red wavelength range produces a light spot on the object so that it is possible to sight exactly that point of the object to which the distance is to be determined.
In addition, in the case of right-angled rooms, individual areas or the volume of the room can also be automatically determined by the distance measuring apparatus by measurement of the length, width and height and can be shown on the display. Often it is also intended to measure the diagonals of the area, for checking purposes. Since, however, the extensive rear measuring stop of the distance-measuring apparatus cannot be positioned in the corner line of two adjacent wall surfaces, the distance-measuring apparatus additionally has a corner-measuring bracket which can be swivelled out. When swivelled out, the corner-measuring bracket thus serves as a measuring stop for the corner line. With the aid of the visible laser spot, the diagonally opposite corner line can be sighted and the distance to it, i.e. the length of the diagonal of the associated area, can be determined.
However, the actual distance measurement is still effected only from the rear, regular measuring stop. The user must therefore add the depth of the corner-measuring bracket itself to the measured result displayed. The depth of the swivelled-out corner-measuring bracket, i.e. the distance between the rear measuring stop of the distance-measuring apparatus and the corner line, is known. In such a distance determination, there is the danger that a user who is not concentrating will obtain an incorrect measurement through an incorrectly performed addition or by forgetting the addition. Moreover, there is the danger that the corner-measuring bracket will become detached from its locked position perpendicular to the measuring stop, so that the predetermined addition constant does not correspond to the actual conditions.
It is the object of the invention to provide a simple, reliable and economical mechanical device which permits a distance measurement with a distance-measuring apparatus both from a corner line and from a flat surface with, in each case, the same measuring stop, the same measuring procedure and an immediate correct distance indication on the display.
This object is achieved, according to the invention, by the features stated described herein. Advantageous embodiments and further developments of the invention are also described herein.
On the one hand, the rear measuring stop of the distance-measuring apparatus is, according to the invention, linear. The linear measuring stop should preferably run parallel to the width of the apparatus. The linear form of the measuring stop can be achieved, for example, by tapering the housing of the apparatus towards the back. Two flat surfaces can taper to an acute angle and form a sharp edge as a contact line. The distance to an object point is measured perpendicularly from this edge.
Such a sharp edge is ideal for a corner measurement. The edge lies directly on the corner line which is formed by two adjacent wall surfaces. The contact with the corner line is retained even when the measuring apparatus is swivelled. For example, especially in the case of the measurement of the diagonals of a square base area in a room, the angle between the measuring apparatus and the side walls forming the corner line is 45°. In the general case of a rectangular base area, this angle deviates from 45° and does so all the more the narrower the shape of the rectangle. A sharp edge as a measuring stop can always be brought into direct contact with the corner line.
As an alternative to an edge, the rear measuring stop can also be designed with a more appealing shape. For example, it can be rounded to give a cylindrical shape. With a cylindrical measuring stop, too, a single contact line with the corner line of two walls is possible provided that the radius of curvature of said stop is smaller than that of the corner line. It is for this reason that an appropriate radius of curvature is chosen since the distance is in fact measured from the rearmost line of the measuring stop. If, owing to a larger radius of curvature, the measuring stop is to rest against both wall sides and hence form two contact lines, this leads only to unimportant deviations in the measurement which are well within the measuring tolerances usual in practice. The same also applies in the case of the diagonal measurement in very narrow rectangular rooms in which the measuring stop can likewise form two contact lines with the walls.
With such a linear measuring stop, a distance measurement perpendicular to a corner line is thus first possible as regular measurement. If, on the other hand, it is also intended to measure from a flat surface therewith, the linear shape of the measuring stop gives a stable right angle to the surface along the line but not transverse thereto. The measuring apparatus would roll on the cylindrical surface. To avoid the instability of this transverse direction, according to the invention the linear measuring stop is divided into at least two stop regions, one measuring stop region being rotatable about an axis running parallel to the measuring direction. Consequently, the rotatable measuring stop region moves on rotation in a plane perpendicular to the measuring direction. Owing to the rotation, the linear measuring stop regions run in different directions and thus spread over a plane. They therefore give the distance-measuring apparatus stability on a flat support surface and result in perpendicular alignment of the measuring direction relative to the support surface.
Thus, by a small manipulation, namely the rotation of part of the measuring stop, it is possible to carry out a measurement perpendicularly from a flat surface, such as, for example, from a wall surface or floor surface, to an opposite surface or to a specific point. Alternatively, it is possible to measure perpendicularly from a corner line. In both types of measurement, the linear rear measuring stop serves as a baseline for the distance measurement. Accordingly, the user can also read the measured distance value directly from the display of the apparatus in both types of measurement. Owing to the unstable position of the rear stop line on a surface, the user will inevitably be reminded to actuate the rotatable part in order to achieve a stable support.
REFERENCES:
patent: 1186853 (1916-06-01), Smith
patent: 1567602 (1925-12-01), Keuffel
patent: 2270355 (1942-01-01), Swanson
patent: 2570430 (1951-10-01), Cramer
Fulton Christopher W.
Leica Geosystems AG
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