Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Patent
1996-04-01
1998-07-14
Westin, Edward P.
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
25023114, 33773, 33780, G01B 312
Patent
active
057808465
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a device or instrument for measuring lengths, according to the preamble of claim 1.
BACKGROUND OF THE INVENTION
At present there are no effective, precise, inexpensive and easily used instruments for the measurement of lengths or distances to be determined on objects of small dimensions, for example a road map or similar. Furthermore, there are no instruments with the aforesaid characteristics of efficiency, simplicity of use and economy which can be used to rapidly determine the lengths of winding lines or paths, for example the routes of roads shown on a map, profiles of objects of complex form, or other items.
SUMMARY AND OBJECTS OF THE INVENTION
From WO-A-8505175 a device is known, wherein a tracking wheel is arranges at the top of a pen-shaped measuring instrument. The revolutions of the wheel are trasmitted, via a mechanical transmission--and a rotating shaft, to an, interruptor for the generation of a modulated signal. The mechanical transmission is cumbersome and scarcely reliable, because the friction losses negativity affect the measurement. In a different embodiment disclosed in the same document permanent magnets are arranged in the wheel and cooperate with a Hall generator. This embodiment is not effective from a point of view of the costs. Moreover measurements are inaccurate due to possible presence of magnetic fields in the environnement where the device operates.
The invention proposes a new measuring instrument which meets the aforesaid requirements and overcomes the draw backs of the known devices. These objects are achieved with the features of claim 1.
In a first embodiment of the device according to the invention, the movable body is a solid of revolution supported so that it can be rotated about its axis of symmetry; in this case, the detected signal contains data relating to the rotation of the said body. In this embodiment, the device may be used like an ordinary ball-point pen, resting the point on the surface on which the determination or measurement is to be executed. For example, in a typical case of application, the device may be used to determine the length of a path shown on a plan or on a road map. In this case, the point containing the rotating body is rested on the paper, at the start of the path, and is displaced along the path to its end. During the displacement, the body rotates and the markings generate, in the detected signal, a set of pulses which, when sent to a counter, indicate the length of travel.
In a particularly advantageous embodiment, the rotating movable body has an elongated profile in a section containing the axis of rotation. This may be achieved, for example, by the rotation of an ellipse about its minor axis. This shape reduces the contact between the body and the surface on which the measurement is to be made and impedes incorrect use of the device. Moreover, with this configuration an area of the external surface of the rotating body, not coming into contact with the surface where the measurement is being made, is defined. The markings are preferably provided in this area, and are consequently not subject to damage.
In an improved embodiment of the device, the movable body is carried by an angularly movable portion of the head, the said angularly movable portion being rotatable about an axis orthogonal to the axis of rotation of the movable body. In this way a greater ease of following a winding path with the rotating body is obtained. If the angularly movable portion of the head is linked to a detection system to detect the angular movement of the said angularly movable portion about its own axis of rotation, the device becomes a determining instrument which can be used to measure two-dimensional objects, and which may if necessary be interfaced with a computer to replace the conventional graphics tablets.
If the rotating movable body is disposed on an element which is movable linearly and orthogonally with respect to the axis of rotation of the rotating body, the device may be used for a set
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Anonymous, Optical Pen Mouse, Xerox Disclosure Journal, vol. 10, No. 3, May 1985.
Angilella Bruno
Bocci Sandro
Gallorini Massimo
A.B.G. S.r.l.
Lee John R.
Westin Edward P.
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