US 2006/0214121 A1Published application

Distance sensor and method for detecting a distance

AssigneeFraunhofer-Gesellschaft zur Foerderung der angewandton Forschung e.V

InventorsOlaf Schrey, Werner Brockherde, Bedrich Hosticka

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Abstract

An indirect detection of the reflected radiation pulses, when measuring a distance by means of the photoeffect, allows considerably expanding the usability of the distance sensor and the distance measuring method, wherein the adaption to a new field of application only requires little design changes. Since in the external photoeffect the photoelectrons are ejected from the material irradiated photon by photon or quantum by quantum and the photons, when being ejected, only require a certain minimum energy and correspondingly the radiation used for irradiation only requires a sufficiently small wavelength, the external photoeffect allows detecting radiation over a large spectral range. When interferences occur in a certain wavelength range in a certain field of application, the operating wavelength range of the distance sensor technology may at first simply be set to another spectral range by using such an irradiation source having a spectrum outside the spectral range containing the interferences.

Claims12

Dependent claims

A distance sensor for detecting a distance to an object point, comprising:

an electromagnetic radiation source for irradiating the object point by a radiation pulse in an irradiation time window;
a detector for detecting electromagnetic radiation reflected from the object point in a detection time window which is in a predetermined temporal relation to the irradiation time window, wherein the detector comprises:
a photoelectrode for, in accordance with the external photoeffect, emitting photoelectrons responsive to the reflected electromagnetic radiation;
and
an electron detector for transforming the photoelectrons emitted to a detection signal indicating a quantity of the electromagnetic radiation reflected from the object point;
and
an evaluator for determining the distance to the object point from the detection signal, the detector further comprising:
a counterelectrode which, together with the photoelectrode, forms a capacity;
a connector for connecting the counterelectrode to a predetermined potential before the detection time window and for separating same from the predetermined potential during the detection time window such that the capacity is discharged during the detection time window;
a connector for connecting the photoelectrode to ground during the detection time window and to the predetermined potential after the detection time window;
and
a reader for reading out a voltage across the capacity after the detection time window to obtain the detection signal.

9 more elements

Dependencies are inferred from the claim text.

Facts

Application: 11/410,720Filed 25 Apr 2006
Priority: 29 Oct 2003
Published: 28 Sep 2006
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

G01S 7/481
Of systems according to group G01S17/00: constructional features, e.g. arrangements of optical elements
G01S 7/4863
Circuits for detection, sampling, integration or read-out: detector arrays, e.g. charge-transfer gates
G01S 17/894
For mapping or imaging: three-dimensional [3D] imaging with simultaneous measurement of time-of-flight at a two-dimensional [2D] array of receiver…
G01S 17/931
For anti-collision purposes: of land vehicles