An infrared radiation-burglary detector comprising radiation-focusing means and a radiation receiver. A bunch of radiation-conducting elements is provided, the radiation inlet openings of which are arranged at the focal surface of the radiation-focusing means and the radiation outlets of which are arranged in front of the radiation receiver.

BACKGROUND OF THE INVENTION 
The present invention relates to a new and improved construction of an 
infrared radiation-burglary detector -- also referred to in the art as an 
infrared intrusion detector -- of the type comprising radiation-bundling 
or focusing means and a radiation receiver. 
Such detectors serve to detect objects or the entry of intruders or 
unauthorized individuals, for instance a burglar, into a protected area or 
room by detecting the infrared radiation emitted by the object or 
individual. Such radiation can be constituted by the inherent thermal 
radiation of the object or the individual, for instance in a range between 
4 .mu. and 20 .mu., preferably between 7 .mu. and 14 .mu., or there can be 
provided a radiation source, the radiation of which is reflected by the 
object or individual to be detected. In the latter case there also can be 
utilized radiation in the near infrared region, so that there also may be 
employed components, such as lenses, filters and so forth, which at the 
far infrared region already exhibit an appreciable radiation absorption. 
In order to be able to detect even the slightest movements it has been 
found to be advantageous to divide the protected room or area into a 
number of separate receiving regions or fields of view, which are 
separated from one another by dark zones or fields. If an intruder moves 
within an area or room protected in this manner, then, it will unavoidably 
happen that such individual will pass through one or a number of 
boundaries of the receiving region. At the outlet of the radiation 
receiver there appear pulse-shaped signals or a signal of varying 
amplitude. By means of a conventional evaluation circuit these output 
signals of the radiation receiver can be evaluated for the purpose of 
delivering an alarm signal. 
In the case of prior art infrared radiation-burglary detectors employing a 
number of separate receiving regions there is generally provided a 
predetermined pattern of receiving directions, receiving cones or 
receiving strips. While such detectors can be adjusted into given 
directions by means of a pivot device or the like, however, there is not 
possible any individual accommodation and adjustment to individual 
receiving directions or regions. Therefore, such detectors, generally 
cannot be accommodated individually to given fields of application. 
According to a heretofore known infrared radiation-burglary detector of 
this type, the different receiving regions are produced by a multiplicity 
of reflectors which take-up the radiation emanating in each case from one 
receiving direction and focus the same upon a common radiation receiver. 
It is conceivable to construct the individual reflectors to be adjustable, 
however this would require an exceedingly complicated and expensive 
construction. Additionally, it is necessary to optically correct the 
individual reflector surfaces depending upon the angle of incidence and 
angle of reflection, so as to obtain good bundling or focusing, and thus, 
cleanly separated receiving regions having relatively sharply defined 
boundaries. The spherical mirrors used with state-of-the-art detectors, at 
best, are only poorly suitable for this purpose, especially when working 
with a flat reflection angle. To this end it would be necessary to choose 
an eccentric section from a paraboloid of revolution, and such section 
must be chosen with increasingly greater eccentricity the flatter the 
reflection angle, i.e. for each individual receiving direction there must 
be selected a different paraboloid-section. With heretofore known 
detectors employing spherical mirrors or reflectors or centric 
paraboloid-reflectors the lateral receiving regions, in the case of more 
pronounced reflection inclination, indistinctively merge with one another 
at the boundaries. Such prior art detectors, even if the reflectors are 
constructed to be adjustable, only would be poorly suitable for positively 
detecting an intruder within a large spatial angular region of a room due 
to the inadequate optical structure. 
SUMMARY OF THE INVENTION 
Hence, it is a primary object of the present invention to provide a new and 
improved construction of infrared radiation-burglary detector or infrared 
intrusion detector which is not associated with the aforementioned 
drawbacks and limitations of the prior art constructions. 
Another and more specific object of the present invention aims at 
overcoming the aforementioned drawbacks and providing an infrared 
radiation-burglary detector having a number of separate receiving regions 
while using only a single reflector, the individual receiving regions are 
optionally adjustable and can be easily accommodated to desired fields of 
application, and wherein, the quality of the optical bundling or focusing 
is independent of the irradiation- or receiving direction. 
Now in order to implement these and still further objects of the invention, 
which will become more readily apparent as the description proceeds, the 
invention is manifested by the features that there are provided a bundle 
or bunch of radiation-conducting elements, the radiation inlet openings of 
which are located at the focal surface of the radiation-focusing means and 
the radiation outlets of which are arranged in front of the radiation 
receiver. 
It is particularly advantageous if the radiation-focusing means are 
constructed as internally reflecting spherical surfaces, and the focal 
surface is constituted by a sphere of half-radius, the radiation receiver 
is arranged approximately at the center of the sphere and the length of 
the radiation-conducting elements chosen such that they correspond to half 
the reflector-sphere radius. Consequently, the inlet openings of such 
radiation-conducting elements, during bending, always automatically come 
to lie in each position at the focal surface. 
In order to obtain a burglary or intrusion detector having good panoramic 
sensitivity, and which can absorb radiation approximately from an entire 
half room, it is advantageous to construct the reflector as an internally 
reflectively coated hemisphere. Such type detector can be employed, for 
instance, as a ceiling alarm arranged at the center of the ceiling of a 
protected room or area. The optical correction and the quality of the 
image are independent of the irradiation direction. 
According to one embodiment of the invention it is possible, by providing a 
flexible construction of the radiation-conducting elements to insure that 
each random receiving region pattern can be individually adjusted, 
depending upon requirements encountered in practice. The number of 
receiving regions is determined by the number of radiation-conducting 
elements contained in the bunch or bundle. In practice it is possible in 
this manner to produce a considerably greater number of receiving regions 
than with a number of different reflectors which require a considerable 
amount of space and the number of which therefore is limited. In this way, 
the protected room or area can be considerably better covered by radiation 
receiving regions.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to the drawings, with the exemplary embodiment illustrated in 
FIGS. 1 to 4 a reflector surface R is arranged in a housing G constructed 
as part of a spherical surface. The selected part of the sphere governs 
the detectable spatial angle. In the event there is desired a sensitivity 
which falls within as large as possible spatial region, it is advantageous 
to employ a hemisphere. The spherical surface R can be constructed as a 
metallic reflector or as an internally reflectively coated plastic- or 
glass portion with a substantially spherical-shaped cavity 10. The 
reflective coating 11 may be found, for instance, of silver or aluminum. 
At the center of the sphere there is arranged a radiation receiver S by 
means of a holding bracket or web H which only screens very little 
radiation. The spectral sensitivity of the radiation receiver S is matched 
to the employed wavelength range. A selective sensitivity for a certain 
spectral range also can be achieved by forwardly arranging a filter F, 
constructed for instance as a cover disk for the device at the housing 
front wall and/or the radiation receiver. 
At the front of the radiation receiver S, confronting the reflecting 
spherical surface R, there is mounted a radiation-conducting bundle 
consisting of a multiplicity or bunch of individual radiation-conducting 
elements, for instance there being shown by way of example five such 
elements L.sub.1, L.sub.2, L.sub.3, L.sub.4 and L.sub.5. The length of 
each of the individual elements L.sub.1 to L.sub.5 is chosen such that it 
approximately corresponds to one-half of the sphere radius. In this 
instance, the radiation inlets 20 of the individual elements L.sub.1, 
L.sub.2, L.sub.3 . . . lie along a sphere of half radius (half the radius 
of spherical surface R), which approximately constitutes the focal surface 
B of the reflector sphere R. 
The individual radiation-conducting elements L.sub.1 to L.sub.5 are 
constructed, for instance, to be flexible or bendable, so that they can be 
easily bent and their radiation inlets can be optionally adjusted to come 
to lie at such spherical-shaped focal surface. The individual 
radiation-conducting elements can be constructed as fibers or rods formed 
of glass or plastic possessing adequate radiation permeability, depending 
upon the employed wavelength, and within which there is propagated the 
radiation, by total reflection at the surface or by reflection at an 
additionally provided reflecting layer. The individual 
radiation-conducting elements also can consist of a multiplicity of such 
rods or fibers of the aforementioned type. One such construction, for 
instance in the form of glass fiber bundles, is already used in practice 
as light conductors. Depending upon the wavelength it can be advantageous, 
instead of using solid and therefore possibly markedly absorbing 
radiation-conducting elements, to construct such as internally reflecting 
or coated hollow bodies, for instance tubes, or as waveguides for 
electromagnetic waves, in the manner as such are useful in microwave 
technology, with walls formed of good conductive metal and/or dielectric 
material, typically for instance glass or plastic. The cross-section of 
such radiation-conducting elements, at the end located at the focal plane, 
corresponds to the requirements placed upon the size of the focal point, 
for instance extremely small and round, and at the other side exhibits the 
same cross-section or a cross-section, for instance rectangular, 
accommodated to the size of the radiation receiver. The 
radiation-conducting elements in the extended or stretched condition, in 
the simplest case, therefore exhibit a prismatic construction, for 
instance in the form of circular or round rods, with an accommodation to 
the size of the focal point and that of the radiation receiver a conical 
or pyramid construction or, in the general case, the form of a body having 
an inlet surface and an outlet surface, wherein the jacket or shell is 
constructed simply such that incident radiation must in some manner reach 
the outlet. It therefore also can be advantageous to design the 
cross-section of the radiation-conducting elements from the standpoint of 
optimum permeability or optimum bending, for instance band-shape, and to 
only provide at the ends transition elements to the desired cross-section. 
Instead of the five elements L.sub.1 . . . L.sub.5, shown in the drawings 
for the sake of improving the illustration, there can be used a light 
conductor bundle consisting of a large number of fibers, for instance more 
than 100. 
By means of each of the individual elements L.sub.1 . . . L.sub.5 there is 
fixed a radiation receiving direction E.sub.1 . . . E.sub.5 corresponding 
to the connection lines between the inlets 20 of the light conductors 
L.sub.1 . . . L.sub.5 and the sphere center point i.e. the location of the 
radiation receiver S. At this location there are disposed the radiation 
outlets 30 of the radiation-conducting elements. Due to the described 
arrangement there is achieved the result that only radiation emanating 
from such mutually separate receiving directions is focused by means of 
the spherical reflector R upon one of the radiation-conducting elements 
L.sub.1 . . . L.sub.5 and thus delivered to the radiation receiver S, not 
however radiation from other receiving directions. There is thus formed a 
receiving direction pattern which corresponds to the distribution of the 
radiation inlets 20 of the individual elements at the focal surface B. 
This pattern can be easily and comfortably adjusted and accommodated to 
the desired fields of application. 
Additionally, due to this arrangement there is achieved the result that the 
optical correction is completely independent of the receiving direction. 
The section of the reflector which is effective for each receiving 
direction and thus the quality of the optical image is determined by the 
spatial angle .beta. at which the radiation-conducting element can absorb 
and further propogate radiation from the direction of the reflector R. 
This spatial angle .beta. and thus the image errors caused by the 
spherical aberration can be limited by means of an aperture or diaphragm 
LB, or by constructing the radiation inlets of the radiation-conducting 
elements L.sub.1 . . . L.sub.5 so as to have an appropriate directional 
characteristic. In this way there also can be achieved the result that not 
only does the central receiving region possess a defined boundary, but all 
receiving directions, even those with pronounced inclined radiation 
incidence. In this way there is insured that the evaluation circuit A 
mounted at the base responds with extreme sensitivity and triggers an 
alarm, even when passing through a markedly laterally aligned receiving 
direction. A sensitivity loss externally of the central region is thus 
practically completely eliminated. 
Instead of constructing the radiation-conducting elements to be flexible or 
bendable, so that they can be bent in the detector itself and aligned with 
the desired receiving directions, there also could be chosen for this 
purpose a material which only after undergoing a certain treatment, for 
instance by increasing its temperature, becomes bendable, thereafter 
however again solidifies, so that the receiving directions are fixed. 
There also can be used rigid radiation-conducting elements which, upon 
mounting at the radiation receiver by any suitable means, can be aligned 
with the desired receiving directions and thereafter, for instance by 
casting, fixed in this position. The alignment of the elements can be 
undertaken in all of the mentioned cases both in the finished mounted 
detector as well as before or during assembly. Thus, for instance, there 
can be mounted in the housing or the reflector a previously finished 
aligned element bundle, if desired, together with the radiation receiver. 
It is remarked that instead of a reflector sphere there also can be 
provided other radiation-bundling means with equivalent effect, for 
instance a collecting lens which also can be constructed as an echelon 
lens or Fresnel lens, or a number of lenses assembled together in a 
honeycombed configuration, at the focal surface of focal plane of which 
there are located the individual radiation conducting openings. In FIGS. 3 
and 4 there are illustrated such detectors with an echelon lens SL and a 
number or facet-shaped individual lenses SL.sub.1, SL.sub.2 . . . , 
respectively, arranged at a sphere. The remaining components correspond to 
those shown in FIG. 1. The inlet ends of the respective radiation 
conductors L.sub.1, L.sub.2 . . . L.sub.i again are located at the focal 
plane B (FIG. 3), and the sphere B (FIG. 4) assembled together from the 
focal surfaces of the individual facets. The outlet ends of such 
respective radiation-conducting elements or conductors are here also 
located adjacent the associated radiation detector S. 
While there are shown and described present preferred embodiments of the 
invention, it is to be distinctly understood that the invention is not 
limited thereto, but may be otherwise variously embodied and practiced 
within the scope of the following claims. ACCORDINGLY,