Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Reexamination Certificate
2002-03-12
2004-06-22
Porta, David (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
C250S231100, C356S621000, C073S862042
Reexamination Certificate
active
06753519
ABSTRACT:
BACKGROUND OF THE INVENTION
Optoelectronic arrangement for the detection of relative movements or relative positions of two objects, which comprises at least three light emitting means as optoelectronic components. In addition, the invention relates to a force and/or moment sensor which utilises such an arrangement. Finally, the invention relates to a PC keyboard which comprises the inventive force and/or moment sensor.
1. State of the Art
As arrangements for the detection of relative movements or relative positions of two objects in force and/or moment sensors, arrangements with optoelectronic measuring cells have widely been accepted. The reason is the simple construction together with high precision and reliability.
DE 36 11 337 A1 discloses an optoelectronic arrangement accommodated in a plastic ball which can simultaneously detect six components, i.e. displacements along three axes and angular rotations about three axes. For this purpose, six light emitting means are arranged in a plane at essentially equal angular distances. In front of each light emitting means a stationary slit diaphragm is provided. The relative movements or relative positions are sensed by photosensitive detectors which are movably arranged relative to the arrangement of light emitting means and slit diaphragms, and whose detector axes extend essentially perpendicular to the direction of the slits. The arrangement requires relatively low construction efforts because the light emitting means and the diaphragms as well as any other electronic means for controlling and evaluating can be arranged on a single printed board by means of a conventional soldering technique, which can be securely connected with a first object. The position sensitive detectors are connected with the second object. It is, however, disadvantageous that the arrangement requires a relatively large area. This is caused by the relatively large spatial extent of the diaphragms and detectors which are arranged in an annular pattern around the light emitting means. This imposes a constraint on the miniaturisation of the arrangement.
Further documents which do not claim to be exhaustive and which show the technical background of the invention are:
DE27 27 704 C3; DE36 11 336 C2; DE32 40 251 A1; US3,921,445 U.S. Pat. No. 3,628,394.
DE 27 27 704 C3; DE 36 11 336 C2; DE 32 40 241 A1; U.S. Pat. No. 3,921,445; U.S. Pat. No. 3,628,394.
2. Problem on which the Invention is Based
Optoelectronic arrangements for measuring relative movements or relative positions as well as force and/or moment sensors which utilise such arrangements have gained increased importance in the past, primarily in industrial applications. Examples are the control of robots and the measurement of forces in automotive test and measuring benches. In general, commercially most interesting applications, however, are also offered for the arrangements and sensors in the office field and in the field of entertainment electronics. Here, they have the function of an input device by means of which up to six components can be input, in contrast to a joystick, a mouse, or a trackball which generally allow the input of only two components. A simple and convenient input of six components as it is provided for by a force and/or moment sensor with an optoelectronic arrangement is desirable for example in the control of 3D design software or sophisticated computer games. Due to their surface requirement, the present input devices are, however, definitely awkward to handle, which opposed any wider distribution. A miniaturisation would permit the installation e.g. into game consoles, PC keyboards, or notebook computers and thus enable a wide market penetration.
On the basis of the state of the art, the present invention is based on the object to create an arrangement for the detection of relative movements or relative positions of two objects, which compared to the known arrangements has a reduced surface requirement. The invention is further based on the object to create a force and/or moment sensor which compared to the known sensors also has a reduced surface requirement. The invention is finally based on the object to create an input device for the application in an office environment which permits an uncomplicated input of up to six force or torque components, respectively.
Inventive Solution
For the solution of this object, the invention teaches an optoelectronic arrangement for the detection of relative movements or relative positions of two objects, which comprises at least three light emitting means as optoelectronic components, and which is defined by the characteristics of claim
1
. Furthermore, it teaches a force and/or moment sensor which is defined by the characteristics of claim
15
. Finally, it teaches a personal computer keyboard which is defined by the characteristics of claim
21
.
Construction and Development of the Inventive Solution
In an embodiment of the invention the light emitting means, preferably infrared light emitting diodes (ILED) are arranged on a closed, imaginary first surface which is plane or convex at each site, that their respective emission directions extend into a first inner space which is defined by the first surface.
As further optoelectronic elements the preferred embodiment comprises position sensitive detectors, preferably position sensitive infrared detectors. Moreover, each position sensitive detector is illuminated by a light emitting means in order to form a measuring cell.
Furthermore, in a possible development of the invention all light emitting means and position sensitive detectors are arranged in a common first plane. In another possible development the arrangement comprises at least four optoelectronic elements which are arranged on at least one first plane and one second plane in such a manner that at least three optoelectronic elements are arranged on the first plane and at least one optoelectronic element is arranged on only the second one of the two planes. Preferably, the first and the second plane are arranged parallel to each other.
In a development of the invention, a light emitting device illuminates exactly one position sensitive detector in order to form a measuring cell. In an alternative development of the invention, however, two position sensitive detectors are illuminated by a light emitting means in order to form two measuring cells with a common light emitting means. Thereby, preferably at each time only the one or the other of the two position sensitive detectors is read out so that the light emitting means always forms a measuring cell with only one each of the position sensitive detectors.
Due to the fact that in each moment a light emitting means is associated with only one position sensitive detector, the output signal of the position sensitive detectors can be used for controlling the currents of the respectively associated light emitting means in such a manner that each position sensitive detector is subjected to the same constant light quantity. This is advantageous in that all measuring cells are widely unaffected by temperature and aging influences as well as contamination and component tolerances. The output signals of the position sensitive infrared detectors (
42
,
62
) are also transmitted to an analog/digital converter for further processing and from there to a microprocessor.
Besides the light emitting means, the position sensitive detectors are preferably also arranged on a closed imaginary second surface which is plane or convex in each site and in such a manner that their respective photosensitive sides face towards a second inner space which is defined by the second surface. The first and the second inner space preferably partially or even completely coincide so that a common inner space is generated about which the light emitting means and the position sensitive detectors are arranged. In a preferred embodiment of the invention, the light of a measuring cell from the light emitting means to the opposite position sensitive detector consequently always traverses the common inner space.
In order t
3DConnexion GmbH
Meyer David C.
Porta David
Wood Herron & Evans LLP
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