WO1999013443A1

WO1999013443A1 - Video surveillance system and method for monitoring a target area

Info

Publication number: WO1999013443A1
Application number: PCT/EP1998/005676
Authority: WO
Inventors: Hans-Peter Hellemann; Albert Schweitzer
Original assignee: Videocon Aktiengesellschaft Für Sicherheitssysteme
Priority date: 1997-09-09
Filing date: 1998-09-08
Publication date: 1999-03-18
Also published as: AU9623398A; DE19739482A1; DE19881308D2

Abstract

The invention relates to a video surveillance system comprising a video camera (10) with a light-sensitive area (16). A diaphragm (14) which can move in relation to said light-sensitive area (16) enables illumination of the light-sensitive area (16) via a target area in a first position. In a second position, said diaphragm prevents illumination of the light sensitive area via the target area whereby it can be clearly detected from the target area that no illumination occurs. A device (20) to move said diaphragm (14) into the first position responds to an activation signal so that the diaphragm between the video camera (10) and the target area can move away in the case of alarm or another state of activation to enable surveillance of the target area. Due to the fact that people in the target area can clearly recognise that no monitoring is taking place or that monitoring is occurring, undesired surveillance of personal privacy inside the target area is excluded.

Description

Video surveillance system and method for monitoring one

Target area

description

The present invention relates to surveillance systems

«Systems and in particular on alarm systems with video surveillance.

In the case of alarm systems with video surveillance, the subjective feeling of a monitored person regarding the threat to privacy is a considerable obstacle to the spread of this technology. Known devices for protecting the privacy of a monitored person in a target area of the surveillance consist, for example, in the lighting up of a red lamp which is attached to the video camera in order to signal to the target area that surveillance is taking place at this moment.

Further options, which are also carried out to ensure the legitimate protection of the privacy of people in the target area, consist in switching off or disarming a video camera, e.g. B. at the time of the lunch break in a company. The employees in a company have a legitimate interest, e.g. B. not to be monitored during their lunch break. The situation is similar for a house owner who wants to have his house monitored using video surveillance systems and has a direct line to a security service or the police, for example. The house owner may wish that, for example, the house is constantly monitored in its absence. There is also a need for surveillance when the home owner is present, for example to detect a thief who could otherwise break in unnoticed by the home owner. However, the homeowner will certainly have a great interest in that at the time or in situations where he certainly will not want surveillance, the surveillance definitely does not take place. To do this, he previously had to rely on the function of the red light addressed or on another visual display, for example of disarming.

However, situations are conceivable in which the interests of the people in the target area of the surveillance and of those who evaluate the surveillance will diverge greatly. In these situations, the people in the target area of the surveillance may no longer have the above-mentioned trust in the correct function of the red light, for example, or in the timeout for the lunch break mentioned. The people in the target area of the surveillance will therefore generally reject video surveillance, since protecting their privacy means more to them than, for example, investigating a break-in or theft, which under certain circumstances will be impossible without video material.

The object of the present invention is to provide a video surveillance system and a method for visually monitoring a target area, which ensure safe protection of people in the target area and therefore lead to a higher acceptance of video surveillance systems at all.

This object is achieved by a video surveillance system according to claim 1 and by a method for monitoring a target area according to claim 6.

The present invention is based on the knowledge that a real acceptance of video surveillance by people in the target area can only be achieved if the people in the target area can convince themselves whether video surveillance is taking place or not. It is obvious to everyone that, for example, a red light on a video camera indicates that they are filming is too easy to manipulate.

Preferred embodiments of the present invention are explained in more detail below with reference to the accompanying drawings. Show it:

Fig. La shows a situation in which the monitoring of a target area is carried out;

FIG. 1b shows a situation in which the monitoring of a target area is clearly prevented;

2 shows a first exemplary embodiment of the video surveillance system according to the invention; and

3 shows a second preferred exemplary embodiment of the video surveillance system according to the invention.

FIG. 1 a shows a video camera 10 which is intended to visually monitor a target area 12. Between the video camera 10 and the target area 12 there is an aperture 14 which, in the situation shown in FIG. 1 a, is in a first position, as a result of which the light-sensitive area can be exposed to light from the target area 12. In the situation shown in FIG. 1b, the diaphragm 14 is located between the video camera 10 and the target area 12 in such a way that exposure of the light-sensitive area through the diaphragm 14 is prevented, it being clearly recognizable from the target area that there is no such exposure takes place.

2 shows a spatial view of the video surveillance system according to the present invention. 2 also shows the light-sensitive area 16 of the video capture device, which can be a video camera, a camera or the like, the light-sensitive area depending on the capture device being, for example, a CCD array, an exposable film or similar devices. leads can be. In the situation shown in FIG. 2, the target area is located in the viewer of the figure, who is arranged in the vicinity of an axis 18. 2 shows the situation in which the diaphragm 14 is located between the light-sensitive area 16 of the video camera and the target area 18 in such a way that the light-sensitive area 16 of the video camera 10 cannot be exposed to light from the target area 18. Of course, when the video camera is switched on, for example, the aperture 14 is filmed by the same. However, no process is recorded in the target area, which is why the privacy of persons arranged in the target area is protected.

FIG. 2 also shows a device for moving the diaphragm into the first position, which is designed as an electromagnet 20, for example. The electromagnet is connected to a power source (not shown) via a cable connection 22, and a relay 24 is also arranged between the power source and the cable connection 22 in order to interrupt the power supply to the electromagnet 20 so that the electromagnet 20 no longer holds the diaphragm 14 , whereby it folds down due to gravity or due to a suitably mounted spring device so that the video camera can film the target area. The relay 24, which can of course also be implemented as a transistor switch or as a mechanical switch, is activated by means of an activation signal, the activation signal indicating that video monitoring of the target area 12 is desired from the moment the activation signal is triggered. A person in the target area, who can be, for example, a cash register, can trigger the activation signal, for example by means of a switch under the counter, in the event of impending danger. Of course, the person could interrupt the power supply for the electromagnet 20 directly in the event of an alarm. In this case, the action of the person who cuts the power supply to the electromagnet 20 is interpreted as an activation signal. For the purposes of this application, all signals are referred to as activation signals, which lead to the aperture 14 being brought from the second position into the first position. Deactivation of the electromagnet 20 could, for example, also by an acoustic signal, for. B. a cry of a person in danger, which must be received and recognized, triggered. In this case, therefore, it is equivalent to refer to the scream as an activation signal, or to refer to the electrical signal present after a microphone that represents the scream or that was triggered by the scream as an activation signal or alarm signal. Further options for triggering an activation signal could be motion detectors or optical sensors, for example.

In continuation of the example of the home owner described at the beginning, an activation signal could also be triggered if the home owner shuts off the front door, the activation signal being triggered by actuating the door lock in order to enable monitoring in the absence of the home owner. Similarly, unlocking the door lock when the house owner returns could trigger a release signal in order to move the cover 14 again in front of the light-sensitive area in order to prevent monitoring in a clearly recognizable manner.

The video camera 10 is thus covered by the cover 14 which can be folded up in front of the lens in such a way that even in the event of a faulty connection or deliberate circumvention of all protective mechanisms of the video camera, no video image can be imaged on the optically sensitive part 16 behind the lens of the video camera. If the video surveillance system is now armed, or if the panic trigger of the system is actuated, ie if an activation signal is received, the electromagnet 20 is deactivated by opening the relay 24, which means that the electromagnet 20 no longer holds the diaphragm 14 in place. why the same after swings away below. Of course, the folding away of the diaphragm can also be triggered by any other locking mechanism, but what is decisive here is the reliability, which is given by the fact that the movement of the diaphragm from the second to the first position is brought about solely by gravity. At this point it should be noted that the reliability of the device for moving the diaphragm in the form of the electromagnet 20 and the movement of the diaphragm 14 are essential per se, since it must be ensured under practically all circumstances that when the activation signal is received the video camera reaches the target area 12 films.

3 shows a second preferred embodiment of the video surveillance system according to the present invention. The target area is again at the observer, which is arranged approximately in the vicinity of the axis 18. In Fig. 3, the aperture 14 is shown in its first position, i. H. in the position in which exposure of the photosensitive region 16 through the target region 12 is possible. In a departure from the first exemplary embodiment, the device for moving the diaphragm in FIG. 3 is designed as a servomotor 26, which can be connected to a diaphragm holder 30 by means of a shaft 28, which can be designed as a screw, which, like the diaphragm holder on which the Electromagnet 20 in Fig. 2 is attached, can be performed. The embodiment shown in FIG. 3 does not require gravity to move the diaphragm 14 from the first to the second position or from the second to the first position, which is why this embodiment is suitable for areas of application in which, due to the positioning of the camera, gravity is not can be exploited.

Upon receipt of an activation signal, the servomotor 26 will move the aperture 14 via the shaft 28 from the second position into the first position shown in FIG. 3, while the actuator 26 upon receipt of an all-clear signal which indicates the end of a dangerous situation, the aperture 14 again between the video camera 16 and the target area 12 bring to protect the privacy of people in the target area 12. Just as in FIG. 2, the diaphragm 14 could also be manually brought into the second position in FIG. 3, which will be particularly useful in FIG. 2, since the attraction force of the electromagnet 20 could not be sufficient to move the diaphragm back into the second Position. With a manual movement of the diaphragm 14 back into the second position, the servomotor 26 could be made cheaper since it only has to rotate in one direction. The servomotor 26 can also be connected to the general control of the video camera in order, for example, to also move the diaphragm 14 into the second position when the camera is disarmed or the camera is deactivated.

The video surveillance system of the present invention thus enables easily controllable surveillance, in which persons in the target area of the surveillance are unequivocally informed as to whether they are being monitored or not.

Claims

claims

1. Video surveillance system for monitoring a target area (12) with:

a video capture device (10) having a photosensitive area (16);

an aperture (14) movable with respect to the photosensitive area (16), which enables the photosensitive area (16) to be exposed by the target area (12) in a first position and, in a second position, to expose the photosensitive area (16) prevents the target area (12), it being clearly recognizable from the target area (12) that no exposure takes place; and

means (20; 26) for moving the diaphragm (14) to the first position in response to an activation signal.

2. Video surveillance system according to claim 1, in which the device (20; 26) for moving the diaphragm (14) releases the diaphragm upon receipt of the activation signal, whereby the diaphragm moves into the first position solely due to gravity and / or spring force.

3. Video surveillance system according to claim 1 or 2, further comprising:

means (26) for moving the diaphragm (14) to the second position in response to an all-clear signal.

4. Video surveillance system according to claim 2 or 3, wherein the means for moving comprises an electromagnet (20), which is activated and holds the diaphragm when there is no activation signal, and which at Em- pfang of the activation signal is deactivated to release the panel (14).

5. Video surveillance system according to one of the preceding claims, wherein the means for moving comprises a motor (26) which is connected via a shaft (28) to the diaphragm (14), the motor (26) being activated upon receipt of the activation signal to bring the diaphragm (14) into the first position and the motor (26) is activated upon receipt of an all-clear signal to move the diaphragm (14) into the second position.

6. A method for monitoring a target area (12) with the following steps:

Detecting whether an activation signal is present;

if an activation signal is present, monitoring the target area (12); and

if no activation signal is present, preventing the monitoring of the target area (12) in such a way that from the target area (12) it is clearly recognizable that the monitoring is prevented.

7. The method according to claim 6, wherein the visual monitoring is carried out by means of a video camera (10) aimed at the target area (12), the step of preventing the monitoring comprising the following step:

Moving an aperture (14) movable with respect to a photosensitive area (16) of the video camera (10) from a first position, which enables exposure of the photosensitive area (16) through the target area (12), to a second position, in which an exposure of the photosensitive area (16) - lü ¬

the target area (12) is prevented by the same, the position of the diaphragm (14) from the target area clearly showing that no exposure takes place.