EP1079351B1 - Space surveillance device - Google Patents

Abstract

A device has an image sensor (5), one or more presence or movement sensors (6) and an electronic controller-analyzer coupled to these sensors. Devices for detecting sabotage (DDS) to any sensor have encased illumination devices (7) to transmit light into a room being monitored through a lens window in the image sensor and/or an approach window in the presence or movement sensors. The DDS store and check stable features for images picked up by the image sensor.

Description

The present invention relates to a device for room surveillance, with a housing, at least one image sensor having an objective window, at least one an entrance window presence or motion sensor and with a control and Evaluation electronics to which said sensors are connected.

For such facilities, also known as intrusion detectors, it is very important that they Sabotageversuche can detect, whereby the sabotage the whole detector or only one can affect the two sensors or sensor types. With motion sensors, as those today almost exclusively passive infrared sensors, ultrasonic or microwave sensors or off Dual sensors used in these two sensor types are such Anti-tamper devices generally referred to as anti-sabot devices known. It should be noted in this connection EP-A-0 186 226, EP-A-0 499 177, which is incorporated herein by reference EP-A-0 556 898 and European Patent Application No. 99110848.1 assigned to the Applicant referenced in this patent application.

The known antimass devices of passive infrared sensors have an infrared transmitter and an infrared receiver and serve to detect the two types of coverage of the detector, these are the cover of the detector in a particular, possibly only small, distance from the detector window, and the immediate coverage of the detector window for example by covering with a foil or spraying with an infrared-opaque Spray, such as paint spray. The first type of cover will be referred to as a remote cover and the second is referred to as a spray cover, wherein with Femabdeckung a cover at a distance of a few millimeters up to a maximum of about 15 cm from the detector window is meant.

Operations or visual changes immediately in front of the detector, such as the remote cover effect in most cases, a reflection from the infrared transmitter of the antimasca device Radiation emitted to the infrared receiver, resulting in a change of the infrared receiver received radiation manifests. To detect changes in the optical Properties of the detector window, this is subjected to infrared radiation and it the radiation passing through the detector window or the radiation reflected by it is measured. To evaluate the signals of the antimasca device, the signals of the infrared receiver compared with threshold or reference or generally voltage values that are over or below and must be maintained for a certain period of time.

With ultrasonic or microwave sensors, the sabotage monitoring takes place in that the ultrasonic or microwave transmitter by briefly switching on / off or off / on emits a short pulse, creating a wide frequency spectrum, which then evaluated in terms of amplitude and time course in a certain frequency range becomes. The mentioned parameters are set for changes in the room in front of the detector typical deviations from mean values or previous measurement results are investigated, in particular on such deviations necessary for the attachment of a shield or cover are characteristic of the detector.

On the other hand, image sensors or video detectors are not protected against sabotage, although of course also with these sensors the danger of sabotage exists. By the invention will now be given a device of the type mentioned, in which the at least An image sensor is protected against sabotage.

This object is achieved according to the invention in that means for detecting sabotage the at least one image sensor provided, and that this by arranged in the housing Illuminant formed for the emission of light in the monitored space are.

A first preferred embodiment of the device according to the invention is characterized in that that the illumination means are arranged so that the light emission in the monitored space through the lens window and / or the entrance window or by a additional remote is done.

A second preferred embodiment of the device according to the invention is characterized in that that when light emission through an additional window, the lighting means are formed by a light source provided for displaying alarms.

The inventive use of a lighting means allows a clear Whether it is a dark room or whether the lens window or the whole device is covered, because with the lighting switched on, even in a dark Room still has a certain minimum brightness. Will, however, this minimum brightness is not reached when the lighting is switched on, then the lens window or the entire facility is covered and there is a sabotage attempt.

A third preferred embodiment is characterized in that in the monitored Space reflectors are provided, whose arrangement is chosen so that the at least an image sensor receives a clear signal when the lighting means are switched on.

The reliability and sabotage safety of the device according to the invention continues improved when said means for detecting sabotage means for storage and checking stable characteristics of the image taken by the image sensor.

Preferably, the checking of the stable features is carried out in that the image of the monitored Space is examined for stable characteristics, and the stable found Features are compared with methods of image processing with the stored.

The inventive storage and verification of stable features allows detection partial coverage of the detector or the pretense of false scenes by a photo held in front of the image sensor or by changing the field of view of the detector. The stable features are stored immediately after installation of the device; while the operation is then a periodic examination of the respective image after stable Characteristics and a comparison of the found with the stored stable features.

The illumination means are preferably activated only when the at least one Image sensor receives a dark image. The check of the stable features is preferred then performed when the device is not armed, or when in the monitored There are no activities in the room because the processor is underutilized during this time is. The decision as to whether or not activities take place in the monitored room takes place preferably based on the signal of the presence or movement sensor.

The inventive device with at least one image sensor and at least one Presence or motion sensor has both over known dual detectors as well compared to pure image sensors significant advantages. Compared with the dual detectors, at which no or only a very rough spatial resolution is possible, so that a distinction between human and animal often can not be done, is the inventive Detector much more robust. In addition, the image sensor offers the possibility of classification objects based on their geometry and motion, and therefore intelligent monitoring as well as the verification and storage of events and the later retrievability of these.

Compared with a pure image sensor, the device according to the invention has the advantage that they still the performance of a presence or even in poor lighting conditions Motion detector provides and thus fully functional. In addition, the presence or Motion detector, the image processing algorithms in the interpretation more difficult Support situations.

Fig. 1

ein Blockschema einer erfindungsgemässen Einrichtung zur Raumüberwachung; und

Fig. 2a-2d

schematische Darstellungen der möglichen Anordnung der Beleuchtungsmittel.

In the following the invention with reference to an embodiment and the drawings will be explained in more detail; it shows:

Fig. 1

a block diagram of an inventive device for room monitoring; and

Fig. 2a-2d

schematic representations of the possible arrangement of the illumination means.

According to Fig. 1, the device for room monitoring consists essentially of a hereinafter referred to as a detector multi-criteria motion detector 1 and one of the following as electronics control and evaluation 2 with a control stage 3 and a processing stage 4 for local evaluation of the signals of the detector 1. Of course This representation gives only the individual function blocks and not the concrete one apparatus construction of the device again. For example, as a rule, certain Parts of the electronics in the detector 1 be present. The latter is especially true when in Detector 1 is a processing or pre-evaluation of the detector signals.

The detector 1 consists of at least one image sensor 5 and at least one below presence or motion sensor 6 referred to as P / B sensor. In addition, the detector indicates Means 7 for emitting light in the visible or infrared range in the monitored Clean up. Both the image sensor 5 and the P / B sensor 6 can each have a pre-processing stage (not shown) downstream, but also in the detector 1 or optionally may be included in the processing stage 4. Get from the preprocessing stages the signals in the processing stage 4th

The processing level 4 is autonomous and allows local decisions and / or display the images taken by the image sensor 5; preferably, it is also for transmission the images formed at a remote center 8, where then, for example, an additional Verification can be done.

The P / B sensor 6 is a motion or presence detector according to one of the known detection principles Passive infrared, active infrared, microwaves, ultrasound or any Combination of it. The image sensor 5 is in the range of visible light, in the near infrared, sensitive in long-wave infrared (heat radiation) or in the UV range; he can on one conventional imaging techniques (CCD [CCD: charge-coupled device], CID [CID: charge injection device] or CMOS [CMOS: complementary metal oxide semiconductor = complementary Metal oxide semiconductor structure]).

Preferably, a special CMOS Biid9ensor, a so-called APS [APS: Active Pixel Sensor], which is characterized by a very low power consumption and by the possibility of access to individual pixels. Moreover, in such an APS additional application-specific analog or digital functions, for example simple ones Image processing algorithms such as filters or exposure control, are easily integrated.

Regarding APS will refer to the article "A 128 x 128 CMOS Active Pixel Image Sensor for Highly Integrated Imaging Systems "by Sunetra K. Mendis, Sabrina E. Kennedy and Eric R. Fossum, IEDM 93-538 and 128X128 CMOS Photodiode-Type Active Pixel Sensor With On Chip Timing, Control and Signal Chain Electronics "by R. H. Nixon, S. E. Kemeny, C. O. Staller and E. R. Fossum in SPIE Vol. 2415/117.

The image sensor 5 is directed to the space to be monitored, records this imagewise, digitizes the image and saves it as a reference image in a memory. If the the image sensor 5 forming APS for example consists of 128 by 128 pixels, then would be in use a wide-angle lens at a distance of 15 m in front of the image sensor 5 one pixel a surface of about 12 by 12 cm. Such a screening is suitable, human and animal figures relatively reliably distinguish from each other.

The possibility of detecting a person at a distance of 15 m is very beneficial, and is the area of the monitored space at this detection distance of about 15 by 15 meters quite realistic. In the active state of the device then makes the image sensor 5 at intervals fractions of a second each one image of the monitored space, stores them Pictures for a specific time and compares them to the reference image and / or each other. The storage of the images is preferably controlled so that the images taken by the detector 1 immediately preceded and / or immediately follow this event, until saved on further and that the remaining pictures automatically after the said time to be deleted.

To make a usable picture even in poor lighting conditions can, the image sensor 5 on large photosensitivity and a large dynamic range (sufficient visibility of details in strong light / dark contrast) optimized. The functions integrated on the APS chip allow an automatic electronic Integrate the shutter with a dynamic of 1: 1000.

The P / B sensor 6 essentially serves the potential weaknesses of the image sensor 5 compensate. This includes in particular that the image sensor 5 below a critical Lighting does not provide any picture information, and that too a sharp change in picture information against the reference image is often not caused by an intruder. you For example, think of abrupt lighting changes in this context by turning on / off the street lighting, passing vehicles with flashing Headlamps, thunderstorms or the like may be caused. In these and similar Cases, by taking into account the signal of the P / B sensor 6, the robustness of the detector 1 significantly increased. The latter is achieved by a combined evaluation of the signals of the image sensor 5 and the P / B sensor 6 in the processing stage 4.

It has been shown that it is advantageous to use the signals of the image sensor 5 and the P / B sensor 6 before the combined evaluation of a separate pre-evaluation, in which the signals of the P / B sensor 6 in a for combined evaluation with the signal of Image Sensor 5 suitable format converted and classified according to their strength. If the detector 1 contains a distance meter (not shown), then this is in the presence a signal of the P / B sensor 6 of corresponding magnitude from the processing stage 4 activated via the control stage 3 and provides to the processing stage information about the Removal of the just detected event or object from the detector 1. Using this Distance information can from the signal of the image sensor 5 clear conclusions on the Size of a detected object and thus on its nature, such as human or animal, be drawn.

In image sensor 5, the pre-evaluation is hardware and / or in the form of a processor core preferably integrated on the APS chip. In the pre-evaluation of the signals are the number the pixels changed from the reference image, their clustering and features the pixel cluster determines. In the process, the reference image is constantly tracked, whereby detected Changes only after checking their stability in the reference image adopted become. The reference image tracking can be done by including the signals of the P / B sensor 6 stable.

At the input of the processing stage 4 is thus classified by strength signal of the P / B Sensor 6, an image signal of the image sensor 5 with information about the number of changed Pixels and the features of the pixel clusters and optionally a signal of the distance meter, this is the removal of the signal triggering the P / B detector 6 triggering event indicates.

The combined evaluation of the signals gives a decision at the output of the processing stage 4 Alarm or non-alarm, this decision being essentially the image content, the overall lighting, the information from the P / B sensor 6 and the change and / or history this parameter, referred to below as global criteria, is taken into account. Plausibility connections are very helpful here: if, for example, lighting and image content change rapidly and sharply, but the signal of the P / B sensor 6 is weak, then no alarm is given, but the stability of the new image is checked and in this looking for movements. If the P / B sensor 6 reports no movement and only one Lighting and / or image change has taken place, then was certainly a lighting switched on or off so that there is no alarm.

The illustrated device for room monitoring corresponds largely to that in the European Patent Application No. 99103260.8 of the Applicant of the present patent application described two- or Mehrkriterienmelder with an image sensor. That's why Here the signal processing is not described in detail, but it is referred to the European Referenced patent application.

As already stated in the introduction to the description, the detector 1 is a device equipped for sabotage monitoring, both for sabotage of the P / B sensor 6 as well as the image sensor 5. The device for monitoring sabotage of the P / B sensor is an anti-masking device of the known type, the concrete training according to the in the P / B sensor 6 implemented detection principle. For a detailed description known Antimaskeinrichtungen is on the cited in the introduction patent applications directed. Below is now the device for monitoring sabotage of the image sensor 5 will be described.

This device, which is used to detect full coverage of the detector 1 or the Image sensor 5 is formed, consists essentially of the illumination means 7 and the these associated components of the electronics 2. The illumination means 7 then send When the image sensor 5 receives a dark image of the monitored space, light enters it. The wavelength of this light depends on the wavelength to which the image sensor 5 sensitive is, and the intensity is preferably selected so that the image sensor 5 also at Dark room registers a certain brightness. Due to the brightness conditions at On and off lighting, a cover can be detected. Preferably the intensity of the light emitted by the illumination means 7 light selected so that the forming or 5 can recognize certain stable features of the monitored space (see below).

FIGS. 2a to 2d each show a detector 1 with an image sensor 5 and a lens window 9, a P / B sensor 6 and an entrance window 10 for infrared radiation and a lighting means 7 is shown. The P / B sensor is preferably a passive infrared detector. The lighting means 7 can be light through either the lens window 9 in the monitored 2a), or through the entrance window 10 for the infrared radiation (FIG. 2b), or through an additional window 11 (Figure 2c). In the latter case, the lighting means 7 may be formed by the or one of the already present for alarm display LEDs. It is also possible to provide two illumination means 7 and 7 '(FIG. 2d), of which the one through the lens window 9 and the other through the entrance window 10 lights.

The suitable location for the arrangement of the illumination means 7 depends on the possible illuminance in relation to the room size, wherein the visibility of a cover depends substantially on the reflection factor R _{M of} the covering material and the mean reflection factor R _{R of} the monitored space. In the arrangement according to FIG. 2 a, when the objective window 9 is stretched, the covering material will reflect a part of the radiation emitted by the illumination means 7, which the image sensor 5 recognizes as a cover. The reliability of the arrangement according to FIG. 2a can be improved by comparing the signal of the reflected light with a nominal value measured in darkness, which includes both the reflection of the space and that of the objective window 9, or by checking stable features of the image (see below).

The arrangements according to FIGS. 2 b and 2 c are in principle the same, since in both cases the light of the illumination means 7 is emitted by a separate window separated from the objective window 9. In these cases, the reflection factor R _{M of} the covering material is irrelevant, and a cover of the lens window 9 can be recognized only at R _R ≠ 0. This means that the room just has to reflect so much light that it can be measured by the image sensor 5. Then, a cover of the lens window 9 can be recognized well.

The arrangement according to FIG. 2d with two locally separated illumination means 7 and 7 ', the are preferably behind the lens window 9 and the entrance window 10 is for increased Claims thought. As with the arrangement of FIG. 2a, the objective window is also here be chosen so that it reflects as little light of the illumination means 7 to the image sensor 5. If an infrared LED is used for lighting, then this can both for the antimissive system of the passive infrared detector 6 as well as for the cover monitoring of the image sensor 5 are used. By the two illumination means 7 and 7 ', the can be switched on independently, it is possible a larger number to recognize possible Abdeckversuche. In particular, with the illumination means 7 a cover of the image sensor 5 and the illumination means 7 'a cover of the Passive infrared sensors 6 are detected, it being sufficient if either the room or the Covering material reflects light.

Another way to increase the reliability of sabotage detection is the Use of reflectors in the monitored room. These reflectors are arranged that the image sensor 5 receives a clear signal even in poor lighting. Preferably The position of the reflector or reflectors is measured by measuring the coordinates determined and stored as a setpoint. During operation of the detector 1 then the measured Position values compared with the setpoints. If a deviation occurs here or if no reflector signal is received, it is clearly a cover of the Image sensor 5 or the respective reflector, both covers in less than be recognized at a great distance.

If only a part of the room is covered, so that the image sensor 5 or the reflector still sees, then the partial coverage by analyzing the stable features (see below) detected. The nominal position of the reflectors can either be measured during installation or it will become automatic in the first dark period after installation certainly.

For highest demands on sabotage monitoring, the detector 1 with an outside the detector housing arranged additional lighting or to an external auxiliary lighting be connected below a certain minimum brightness level is turned on, for example, by an intrusion signal of the passive infrared detector 6, so that at any time, so even in complete darkness, a picture can be taken and whose stable characteristics (see the following) can be determined.

It has already been mentioned that the image sensor 5 contains a memory in which the digitized Image of the monitored room is stored as a reference image. For sabotage monitoring Now follows in addition a storage of stable features in the reference image, a periodic Examination of the image taken by the image sensor 5 for stable characteristics and a review of the found stable characteristics by means of a check with the stored. Stable features are to be understood as those features of the image which Do not change with a certain probability, so in particular boundary lines and edges of the room and of doors and windows, straight edges and generally curves larger pieces of furniture, and the like. There will be a number of such stable features digitized and stored in memory.

At periodic intervals, preferably when there is no activity in the monitored area is present or in the fuzzy state of the detector, the recorded image examined for stable characteristics and the stable features found are with compared to the saved ones. The presence or absence of activity in the monitored Space is detected with the P / B sensor. If no stable features found or the found stable features do not match the ones stored, sabotage alarm is triggered. The former is an indication that the image sensor 5 or the detector 1 was incompletely covered (for example, with a cloth or the like), the latter may indicate that the image sensor 5, for example by attaching a photo in front of the lens, a fake scene is faked.

When checking the stable characteristics, one can also proceed in such a way that one can obtain a larger one Number of, for example, ten stable features stores and for the number of necessary ones Matches between stored and found stable features sets a threshold. If this threshold is undershot, sabotage alert will occur and if the minimum threshold matches the matches is present, newly found stable characteristics are stored in the set of Stable features added. This makes it possible for the spatial model to change such as. to constantly update when moving furniture.

• Vollständige Abdeckung des gesamten Melders, entweder mit reflektierendem oder stark absorbierendem Material,
• Abdecken des Bildsensors oder.des P/B-Sensors,
• Vortäuschung einer falschen Szene z.B. durch ein Foto,
• Verdrehen des Melders in seiner Halterung (Veränderung des Blickfelds des Melders),
• Abreissen des Melders von der Wand.

With a device of the type described, the following types of sabotage can be detected:

• Full coverage of the entire detector, either with reflective or highly absorbent material,
• Covering the image sensor or the P / B sensor,
• Imagination of a wrong scene eg by a photo,
• Turning the detector in its holder (changing the field of vision of the detector),
• Tear off the detector from the wall.

Claims (11)

1. Space surveillance device, having a housing, at least one image sensor (5) having an objective window (9), at least one presence or motion sensor (6) having an entry window (10), and having control and evaluation electronics (2), to which the aforementioned sensors (5, 6) are connected, characterized in that means for identifying sabotage of the at least one image sensor (5) are provided, and in that the said means are formed by illumination means (7, 7') arranged in the housing and serving for the emission of light into the monitored space.
2. Device according to Claim 1, characterized in that the illumination means (7, 7') are arranged such that light is emitted into the monitored space through the objective window (9) and/or the entry window (10) or through an additional window (11).
3. Device according to Claim 2, characterized in that, in the case where light is emitted through an additional window (11), the illumination means (7) are formed by a light source provided for the indication of alarms.
4. Device according to Claim 2, characterized in that two illumination means (7, 7') are provided, of which one (7) transmits its radiation through the objective window (9) and the other (7') transmits its radiation through the entry window (10).
5. Device according to one of Claims 1 to 4, characterized in that the illumination means (7, 7') are formed by infrared light-emitting diodes.
6. Device according to Claim 2 or 4, characterized in that, in the case where the illumination means (7) are arranged for emitting light through the objective window (9), the light reflected from the space is compared with a desired value measured in darkness, which includes both the reflection of the room and that of the objective window (9).
7. Device according to one of Claims 1 to 6, characterized in that reflectors are provided in the monitored space, the arrangement of which reflectors is chosen in such a way that the at least one image sensor (5) receives an unambiguous signal in the case where illumination means (7, 7') are switched on.
8. Device according to Claim 2, characterized in that the aforementioned means for identifying sabotage have means for storing and checking stable features of the image recorded by the at least one image sensor (5).
9. Device according to Claim 8, characterized in that the stable features are checked by virtue of the fact that the image of the monitored space is examined for stable features, and the stable features found in this case are compared with the stored features by image processing methods.
10. Device according to one of Claims 1 to 9, characterized in that the device is equipped with an additional illumination arranged outside the housing or is connected to an external illumination.
11. Device according to Claim 10, characterized in that the additional illumination or the external illumination is triggered by the presence or motion sensor (6).

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