Amusement devices: games – Aerial projectile game; game element or accessory therefor... – Target
Reexamination Certificate
2000-03-09
2001-11-13
Graham, Mark S. (Department: 3711)
Amusement devices: games
Aerial projectile game; game element or accessory therefor...
Target
C273S407000
Reexamination Certificate
active
06315294
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the field of targets, and in particular, a heat target for creating a thermal image composed of several bands and having at least one layer of electrically conducting material connected to two electrodes connected to means able to generate a potential difference between them, said layer being attached to a support.
Optronic devices for daytime and nighttime vision associated with weapons or weapon systems for land, sea, and air forces require a checking means for their validation. Targets enable the performance of these optronic devices to be quantified relative to contrasts in the visible or thermal infrared ranges, and relative to the detection, recognition, and identification ranges of systems at actual distances.
The STANAG 4347 and STANAG 4349 documents define procedures for optronic device testing. The former relates to the definition of normal static range performances of thermal imaging systems and the latter, to measuring the minimum resolvable temperature difference of thermal imaging systems.
The minimum resolvable temperature difference of thermal imaging systems is a function that, at an angular frequency, recognizes the smallest temperature detection &Dgr;&thgr; such that the target bars are placed:
normal to the axis of the observation system
in the center of the field
at a distance such that the successive bars, corresponding to a certain frequency, can be discerned by the optronic device tested.
The thermal imaging system links the thermal resolution and angular resolution of all the elements involved in the signal path within the system. Thus it depends on:
the objective
the detector
the electronics
the display system
the observer (normal visual acuity, good ability to evaluate colors, and good experience in this type of measurement)
the atmospheric transmission.
The function of the optronic is to supply visual information to the observer. The information has to be qualified and quantified.
For this purpose, the following three types of tests are generally performed: Detection, Recognition, and Identification.
Detection is the act of detecting a hot spot in a scene.
Recognition is finding out the type of object in a scene (tank, light vehicle, infantryman, etc.).
Identification is the precise determination of object (AMX30, T72, etc.).
For an object to be detected, recognized, or identified with some probability of success, the system must resolve a number of points on the object when placed at a far distance, and this number is a function of the type of test considered (Detection, Recognition, or Identification).
In fact, instead of points, spatial frequencies expressed in pairs of lines (or bars or bands) are considered.
There are empirical criteria that gives the probability of success probability value. The most widely used are the Johnson criteria.
The targets used for the visible mode correspond to the same spatial frequency as those of the thermal infrared mode.
Each type of test (Detection, Recognition, or Identification) and each mode (visible or thermal infrared) requires a specific target calculated by criteria relating to resolving power as a function of a 50% success probability.
In the thermal infrared mode, the targets used are the following:
Nighttime Detection:
uniform objective
bar width: 2.30 m
Nighttime Recognition:
3.5 line pairs per objective
bar width: 0.32 m
Nighttime Identification:
7 line pairs per objective
bar width: 0.16 m
In the visible mode, the targets used are the following:
Daytime Detection:
uniform objective
bar width: 2.30 m
Daytime Recognition:
3.5 line pairs per objective
bar width: 0.32 m
Daytime Identification:
7 line pairs per objective
bar width: 0.16 m
Since the pitch of the detector matrix may be different in the two directions (horizontal and vertical) the number of targets must be doubled to obtain both positions.
These types of targets are presented in
FIGS. 1
a
to
1
f.
In the visible mode, bands
5
are in one color shade and bands are in another shade of the same color, for example two shades of grey with a contrast of for example, 20%, contrast between black and white being considered at 100%.
In the infrared mode, the bands correspond to infrared radiation transmitting surfaces. Bands
5
correspond to a surface at a first temperature T
1
, and bands
6
correspond to a surface with a second temperature T
2
.
Targets
1
a
to If are used respectively for:
vertical detection,
horizontal detection,
vertical recognition,
horizontal recognition,
vertical identification,
horizontal identification.
Thus, detection, recognition, and identification measures in the two modes, visible and thermal infrared, require 12 targets.
This multiplicity of targets has a number of disadvantages. Substantial logistics are required, and the time taken to change over the test type (detection, recognition, or identification), the position, (horizontal or vertical), and the mode (visible or infrared), require the target to be replaced each time, and considerably increasing the total testing time to evaluate the performance of an optronic device at an actual distance.
The goal of the invention is to overcome these disadvantages by providing a target that is very simple to manufacture, equally simple to maintain, and limits the time lost when the type of test is changed.
SUMMARY OF THE INVENTION
The proposed solution is a heat target for creating in particular, a thermal image composed of several bands and having at least one layer of electrically conducting material connected to two electrodes connected to means able to generate a potential difference between them. The target being characterized as having at least one module resting on a support and forming all or part of a band, and having a supporting structure where all or part of which rests at least one layer of electrically conducting material connected to two electrodes connected to means able to generate a potential difference between them. The heat target comprising a shaft-plus-bearing assemblies, with the bearings being integral with the support and the shafts being integral with the module for allowing all or part of the module to rotate.
The heat target may also comprise a motor of the stepper type for example, with two directions of rotation, or an asynchronous motor at a safe voltage with an end-of-travel stop.
According to one particular characteristic, the heat target comprises at least two independent modules each forming all or part of a band and each having at least two longitudinal faces and a supporting structure on all or part of which rests at least one layer of electrically conducting material connected to two electrodes connected to means able to generate a potential difference between them, and having means allowing all or part of each module to rotate.
According to an additional characteristic, the at least two longitudinal faces of each of the modules are painted, the color of the paint or the shade of the first longitudinal face being different from that of the second longitudinal face.
According to an additional characteristic, the heat target has at least part of the support common to all the modules and the modules can be disposed in the same plane and all said first longitudinal faces of each of the modules can be positioned in the same plane with the aid of means for allowing rotation of all or part of the module.
In addition, the heat target may comprise means for allowing the modules to rotate about itself, particularly in the plane that it defines, and means for rotating heat target in the plane that it defines.
According to an additional characteristic, at least one of the modules has a first and a second face covered by a layer of electrically conducting material connected to two electrodes connected to means that can generate a potential difference between them, said layer being attached to the supporting structure.
According to another characteristic, at least one of the modules has a second longitudinal face made of a material not connected to electrodes, the material being ele
Etat Francais represente par le Delegue General pour l'Arme
Graham Mark S.
Oliff & Berridg,e PLC
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