DE102007038421B3 - Safety device for monitoring automatic door, particularly automatic rotary double door, has transmission unit, fixed at door leaf for transmission of light into monitoring area in surrounding area of door leaf for monitoring door - Google Patents

Abstract

The safety device has a transmission unit (20), fixed at a door leaf for light transmission (51,52,53) into a monitoring area (54) in a surrounding area of the door leaf for monitoring a door. A receiver unit (30) is provided, for receiving of reflected and scattered light from the monitoring area. An acceleration sensor is arranged at the door leaf (12) for determining the acceleration of the door leaf, which is operationally connected with a control unit and evaluation unit (80). The control unit and evaluation unit can change the monitoring area depending on the position information. An independent claim is also included for a method for monitoring an automatic door, particularly an automatic rotary double door.

Description

The The present invention relates in a first aspect to a security device for monitoring an automatic Door, in particular an automatic swing door, after the preamble of claim 1.

In In another aspect, the invention relates to a method of monitoring an automatic door, in particular an automatic swing door, according to the preamble of Claim 14.

Such a security device is for example off DE 102 28 930 A1 and comprises the following components: a transmission unit mounted on a door leaf of the door to be monitored for emitting light into a surveillance area in an environment of the door panel, a receiver unit for receiving reflected and / or scattered light from the surveillance area and one with the transmission unit and the control unit operatively connected control and evaluation unit for controlling the transmitting unit, for evaluating measuring signals of the receiver unit and for outputting control signals to a door control of the door to be protected.

In a generic method, which also aus DE 102 28 930 A1 a transmitting unit emits light into a surveillance area in an environment of the door, reflected and / or scattered light from the surveillance area is detected by a receiver unit and depending on measuring signals of the receiver unit control signals are delivered to a door control of the door to be protected.

at the described safety devices, as well as moving or driving presence sensors are called, the light falls the transmitting unit, depending on the position of the door, on different areas, for example, a floor. This is not a problem as long as in the swept areas the Reflective or scattering properties do not change or only negligible. It however, it becomes common come to situations where this is not the case, for example when an adjacent wall gets into the field of view of the sensor. in this connection generally results in the task, the detection or monitoring field dependent on a position of the monitored Door in to adapt the appropriate way.

In the prior art, it is generally known to use acceleration sensors to determine a door position. For example, in DE 600 14 278 T2 an elevator door control in which an acceleration sensor is used. However, previous sensors receive the relevant information about a door position via a bus system from a door control or the sensors do not use any information about the state of motion of the door leaf.

If Accordingly, the state of motion of the door leaf of the control and evaluation is to be used, has always been a direct connection to the door control necessary and The software in the sensor and in the door control unit must be logically linked be matched. Such sensors are therefore not universal used. In particular, for small quantities is a software adaptation not rentable.

task The invention is a safety device of the above To provide a kind and to provide a method of the above kind, in which a consideration the door position uncomplicated possible is.

These Task is in a first aspect of the invention by the Safety device solved with the features of claim 1.

In In another aspect, the object is achieved by the method with the Characteristics of claim 14 solved.

advantageous embodiments the safety device according to the invention and preferred variants of the method according to the invention are the subject the dependent Claims.

The Safety device of the above type according to the invention thereby further developed that on the door leaf an acceleration sensor for determining acceleration of Door leaf arranged is operatively connected to the control and evaluation unit in that means for determining position information from the measurement signals of the acceleration sensor are present and that the control and Evaluation unit depending on the position information the surveillance area change can.

The Method of the above type is according to the invention by further developed that with one on the door leaf at the monitored Door arranged Accelerometer is determined a position of the door leaf, and that dependent from the position of the door leaf the surveillance area is adjusted.

As a core idea of the invention can be considered not to install the accelerometer sensor in contrast to the prior art in the door control, but directly on the door leaf of the door to be monitored. In the inventive According to the safety device and the method according to the invention, the acceleration sensor is therefore part of the safety device on the door leaf.

Thereby there is no direct connection between the door control and the control and evaluation unit necessary. Accordingly, an adjustment the respective software and the protocols are omitted.

From this There are significant practical advantages as the safety devices and the door controls often supplied by different manufacturers and therefore only on each other need to be adjusted. This is in the safety device according to the invention considerably easier than in the prior art.

at the invention is therefore the angular position of a door regardless of Any information of a door control unit is available. This can cause deviations from a normal door movement, for example, directly determined by personal contact become. Because such safety devices or optical sensors can be attached to a variety of automatic doors, is the independence achieved by the present invention from the existing door controls a significant advantage.

The information about the movement of the door wings become determined with an acceleration sensor, in particular in the optical Sensor itself can be integrated.

Basically an acceleration sensor that measures acceleration in one direction only, be enough. This would be for example, with only a linear movement of a door, such as a door Sliding door, the case.

Especially however, preferred embodiments are where the acceleration sensor is a two-quadrant sensor, so analyze in at least two directions of movement simultaneously can.

at Accordingly, a two-quadrant sensor has two independent acceleration signals to disposal and these measurement signals can appropriate one plausibility test be subjected. The reliability the location for the door is thus increased.

Out The acceleration signals then become position information calculated. From the calculated door positions successively different sized and differently shaped monitoring fields generated when the sensor is first installed can be.

By This arrangement can be prevented, for example, a large monitoring field in front of the opening Door Outputs false signal when this monitoring field, for example, a Wall approaching.

on the other hand should the monitoring field always in its maximum possible Size spanned, with it as far as possible no unsupervised Areas arise which could lead to a hazard.

If the door opening speed and the start time are known, the learned monitoring fields be adapted even after a temporal rigid program.

Of the Acceleration sensor can be used in the inventive use described here accordingly also as Position sensor or as opening sensor be considered.

There a spin all the better on the acceleration sensor acts, the farther the acceleration sensor is arranged from the fulcrum, the acceleration sensor is preferably attached to the outside of the door leaf in the region of the main closing edge.

Appropriately while the acceleration sensor in the same housing as the transmitting unit or the receiver unit be integrated. This is particularly beneficial as the customers are often no additional Device on the door want to mount. The entire security device can accordingly in a single case be integrated or, for example, in end cover of already existing devices be housed. This is possible, because the acceleration sensors in small designs, for example available as SMD design are.

Of the Using an accelerometer provides a number of others Advantages. For example, in addition to the position signal and the actual acceleration signal for the door control considered become. For example, an acceleration sensor may detect if a door goes through Persons, about with their hands or your feet are blocked is, and the acceleration signal can then expediently from the door control unit in a force-limited crawl be implemented.

Since changes in the monitoring field as a function of the door position can result in a special way when monitoring a secondary closing edge of a swing door, the safety device and the inventive method can be used particularly advantageous if the door is a swing door and a side closing edge of this swing door is monitored.

The surveillance area In particular, a surrounding area of the secondary closing edge can then be present the floor be.

at a particularly preferred variant of the safety device according to the invention the transmitting unit and the receiver unit form a triangulation sensor and the transmitting unit and the receiving unit are for provision one compared to the dimensions of the transmitting unit and the receiver unit much larger base width in an upper area on the door leaf the door to be secured spaced apart.

From The inventors were recognized in this context that a in an upper area on the door leaf above the Secondary closing edge attached triangulation sensor is not sufficiently good sensitivity having. Furthermore, it was recognized that the reason for this is too low Sensitivity is that the distance between transmitter and receiver in the Comparison to the height the door is too low if transmitter and receiver in one compared to the dimensions of the door small case are housed. Triangulation sensors need one for safe operation preferably large base width, So one possible huge Distance between transmitter and receiver.

essential Thought of the invention described here is, the sensor in two parts, namely a transmitting unit and a receiving unit, to separate and these at the top of the door leaf spaced from each other to install. This can basically the entire width of the door leaf be exploited, so that a particularly large base width and thus a excellent triangulation sensitivity can be achieved.

The use of a triangulation sensor, for example, compared to DE 102 28 930 A1 It also ensures that changes in the color of the floor, for example due to soiling, are irrelevant, since a height measurement is carried out. The development of the invention described here therefore enables a particularly reliable non-contact monitoring, in particular a secondary closing edge of a swing door.

For example can the transmitting unit and the receiver unit at a distance greater than 1/3, preferably greater than 1/2, and more preferably greater than 3/4 of a width of the door leaf be spaced from each other. With the thus provided huge Base distance between transmitting unit and receiver unit can be excellent Triangulation sensitivities are achieved.

at a particularly preferred embodiment The invention relates to the transmitting unit and / or the receiver unit in end housing parts one on the door leaf the door to be secured arranged in the upper area of existing belay device. In such a Accommodating the secondary closing edge sensor in the two-sided end covers of an existing device the assembly effort is reduced to a minimum and the customer must no additional Device on the door assemble. In a preferred variant of the safety device according to the invention if only the transmitter unit is accommodated in the end cover in the area of the secondary closing edge and the receiver unit is in the main body of the backup device about in the middle of the door leaf arranged.

at a further particularly preferred embodiment of the security device according to the invention the transmitting unit generates a light pattern in the monitoring area and depending on the position of the door leaf parts of the light pattern are not taken into account in the detection. For example, the light pattern may include a plurality of light spots, especially light points, and depending on the position of the door leaf then individual light spots are not taken into account in the evaluation.

The Light pattern can basically be provided in any way. In a simple Variant, for example, the transmitting unit has a plurality of Light sources on, over a optical system can be imaged on the ground. As light sources can For example, light-emitting diodes or semiconductor lasers, in particular in Infrared range, to be used.

With This plurality of light sources may then have a plurality of light spots as a light pattern blasted on the surrounding area of the minor closing edge become.

The light pattern is desirably chosen and formed so that it is virtually impossible to get into the area of the minor closing edge without somehow influencing and disturbing the pattern of light on the floor. In principle, the light pattern can also be movable. For example, a plurality of light strokes can be moved over the relevant surrounding area of the minor closing edge on the floor. For such embodiments, then the evaluation of the measurement signals of the receiver unit is time-dependent, that is, a certain point of light is expected at different times on different De tektorelementen. In such variants, one can basically manage with a smaller number of light sources.

at a further preferred embodiment the transmitting unit has a luminous surface, which has a partially opaque mask depicts a light pattern on the floor. With such a structure can Different light patterns can be easily realized.

at In a further preferred variant, the transmitting unit has a diffractive device, in particular a diffractive optic, and at least parts of the light pattern are transmitted through a diffraction pattern educated. This can basically a single light source, such as a laser sufficient. The diffractive optics example, from an embossed film consist. For example, a single intense laser with a power of about 20 to 30 mW are used. By the Use of narrowband optical filters on the receiver side then a good signal-to-noise ratio can be achieved.

Basically, behind a single lens and several transmitters are arranged.

at an alternative arrangement for providing multiple points of light is in front of a big light-emitting Chip a mask with a specific transmission characteristic arranged. According to this transmission characteristic results after passage of the radiation through the mask a desired Light pattern.

The Signal / noise ratio becomes basic better if one and the same point of light is repeated several times is measured. For this purpose, correspondingly fast detectors are necessary. The Speed of the measurement altogether can be increased, if one at the Evaluation, for example, in a CCD line, only those points considered on the detector, where to actually after learning Measuring points expected.

There in the safety device according to the invention the transmitting unit and the receiver unit generally in separate housing parts are housed, it will be virtually impossible to use the device in front of the Assembly final einzujustieren.

There furthermore in preferred variants of the safety device according to the invention the light pattern on the floor is not visible, it therefore requires appropriate means to a viewing area of the receiver unit or a beam region of the transmitting unit for adjustment purposes to make visible.

For this are in preferred embodiments the safety device according to the invention, where the light pattern is formed of IR light at the transmitting unit further radiation sources for visible light, in particular colored light-emitting diodes, provided for adjusting a transmitting optics and / or at the receiver unit are other sources of radiation for visible light, especially colored light emitting diodes, for adjusting a receiving optics. With the help of such additional Radiation sources can the transmitting unit and the receiver unit simply adjusted relative to each other.

One Invisible light pattern can also be seen as such Light source can be provided by the fact that the light source operated pulsed and the light pulses are chosen so short, that they are not perceived by the human eye. To that Light pattern then for To make adjustment purposes visible, the pulse duration can be adjusted accordingly elevated or the pulse break can shortened become.

Essential for the Invention is the big distance between transmitting unit and receiver unit. On the concrete arrangement on the door leaf but it is only secondary. But the light pattern can be simpler formed in the required surrounding area of the minor closing edge be when the transmitting unit on the door leaf inside in the area of the minor closing edge and the receiver unit outside in Area of the main closing edge is arranged. For For some purposes, it may be sufficient if the receiving unit approximately at the top in the middle of the door leaf is arranged.

The Receiving unit has expediently for use in the triangulation sensor Detector with a plurality of receiving elements or a PSD. For example, the detector may essentially consist of a CCD array, a CMOS array or a photodiode array. With help such, in principle known detectors can Detection signals of certain detector areas or receiving elements certain parts of the light pattern, for example, certain spots of light or points of light.

If used as a detector, an array with multiple receiving elements is, the light pattern can be irradiated and evaluated simultaneously. This is generally not possible if a PSD, so a spatially resolving Photodiode, is used. The light pattern, for example, a plurality of light spots or points of light, must then be in multiplex mode be irradiated and evaluated accordingly.

An evaluation can be done in a simple way by comparing the measurement signals with a uniform threshold. In a particularly preferred variant of the method, the control and evaluation unit compares the measuring signals of the receiver with nominal values stored individually for individual structures of the light pattern, and in the case of qualified deviations of the measuring signals from these set values, control signals are delivered to a door control of the door to be protected.

A particularly reliable Function of the safety device according to the invention and the method of the invention is reached when the measurement signals appear on the monitor area blasted light patterns go back, at free door be taught as setpoints.

Very slow changes The taught-in transmitter positions can on the sensor side through various effects, such as temperature change, aging, moisture absorption Plastics, occur. These slow changes of the measuring signals can be found in the continuous operation are taught in continuously. This will be reduced demands on the mechanics.

One embodiments The invention will be explained in more detail below with reference to the drawing. Here in shows:

1 a schematic representation of a first embodiment of the safety device according to the invention;

2 in a partial view of the transmitting unit of the security device 1 ; and

3 in a partial view of the receiver unit of the safety device 1 ,

The safety device according to the invention shown in the figures 100 to secure an automatic door 10 contains as essential components a transmitting unit 20 , a receiver unit 30 , a transmitting and evaluating unit 80 and a schematically illustrated acceleration sensor 90 , The schematically represented door 10 consists essentially of a door leaf 12 which is in the area of a secondary closing edge 14 about hinges 18 suspended in a door frame. Opposite the secondary closing edge 14 is in the range of a main closing edge 16 a door handle 19 for manually opening the door 10 available.

The transmitting unit 20 is together with the control and evaluation unit 80 in a housing cover 28 accommodated. The housing cover 28 forms a frontal conclusion of a belay device 60 which is in an upper area 13 of the door leaf 12 is arranged. The belay device 60 serves to visually monitor the area in front of the door leaf 12 ,

Opposite the transmitting unit 20 is the receiver unit 30 in an end housing cover 38 , and thus at a great distance from the transmitting unit 20 , housed. Transmitter and receiver of the safety device according to the invention are therefore installed in separate end covers. The belay device 60 For example, may have an aluminum profile, in which the essential components are included.

The inventively provided acceleration sensor 90 is in the illustrated embodiment in the housing cover 38 housed, in which also the receiver unit 30 is included. The safety device described here is intended to monitor a secondary closing edge, that is to say a hinge edge of a swing door. This safety device or this sensor is mounted on the door moving, the monitoring field can be continuously adjusted to an opening angle of the door leaf. This opening angle is calculated from the data of the acceleration sensor mounted on the door leaf according to the invention 90 directly in the control and evaluation unit 80 the security device calculated without a connection to a door control is necessary.

The Safety device described here is therefore universal can be used and easily assembled by untrained personnel and be used.

The evaluation unit 80 is with a door control 70 operatively connected, for example via a radio link. Via an operating lever 72 on the door leaf 12 in the upper area 13 fixed, the door control can 70 the door 10 open, hold open, close or keep closed, depending on which signals from the control and evaluation unit 80 to the door control 70 be delivered.

As in 2 shown, the transmitting unit 20 a plurality of light sources 21 . 22 . 23 on, for example, IR semiconductor lasers on a printed circuit board 26 are arranged. The light sources 21 . 22 . 23 send along schematically indicated light paths 41 . 42 . 43 In general, infrared light with noisy pulse / pause ratio off. This transmitted light is via an optic 24 on the floor 50 in a surrounding area 54 the minor closing edge 14 imaged and forms a light pattern there. In the example shown, this light pattern includes a plurality of separate spots of light 51 . 52 . 53 , Through the points of light or Lichtfle bridge 51 . 52 . 53 a safe light curtain is formed.

The transmitting unit 20 and the receiver unit 30 are via the control and evaluation unit 80 effectively linked together. transmission unit 20 and receiver unit 30 can therefore exchange data via a communication connection, so that the activities of the transmitting unit 20 and the receiver unit 30 each other, in particular temporally, can be tuned.

From the surrounding area 54 on the floor 50 reflected and / or scattered light passes through a receiving optics 34 on a detector 36 the receiver unit 30 , The corresponding beam paths are schematically indicated by the reference numerals 31 . 32 . 33 characterized. The main optical component of the receiver unit 30 consists of a detector 36 comprising an array of photosensitive receiving elements, for example a CCD line, a CMOS array or a photodiode array. The detector 36 may also be a position sensitive detector, PSD.

Because the surveillance area 54 when opening the door 10 With structural conditions, such as a wall, collide, this monitoring area must 54 make it smaller during opening of the door according to a given function. This can be achieved, for example, by virtue of the software removing learned light points from the evaluation on the receiver side.

Typical acceleration sensors have a sensitivity of 1 V / G, where 1 G = 9.81 m / s ² . With an assumed door speed of 0.5 m / s, which reaches the door within 1 second, this results in an acceleration of 0.5 m / s ² . At a sensitivity of 1 V / G, this provides an output voltage of 50 mV, which is easy to handle electronically.

For an external Wiring required An accelerometer only has two extra capacities. The analog output voltage can over an analog-to-digital converter integrated in the processor digitized become. Alternatively, a duty cycle modulated output or a digital output of the acceleration sensor can be used directly for communication with a microcontroller.

About an adjusting device, not shown in detail, the detector 36 be aligned so that the on the floor 50 pictured light spots 51 . 52 . 53 be seen. The positions of these points of light on the detector 36 be after mounting the safety device 100 on the door leaf 12 learned. As Schaltkrite rium is used during operation, a rapid or sudden change in the individual light spots 51 . 52 . 53 learned measuring signals. This can be both a rapid change in position and a rapid change in the number of detectors 36 acted light points or light spots act.

The safety device is preferably operated in the operating mode "background evaluation." In this case, the safety device switches 100 on "object detected", when the learned signals suddenly change from the background.

For easy alignment of the transmitting unit 20 and the receiver unit 30 through the customer, are behind the transmitting optics 24 as well as behind the receiver optics 34 next to the IR transmitters and next to the detector 36 visible marker transmitters, such as colored light emitting diodes, positioned. By the picture of these visible marker transmitters on the floor 50 can the orientation of the transmitting unit 20 and the receiver unit 30 be made visible. For reasons of clarity, these additional radiation sources or marker transmitters are not shown in the figures.

In safety-relevant applications, the components used, ie transmitting unit, are tested 20 , Receiver unit 30 and control and evaluation unit 80 , each other so that the security device 100 in a safety-relevant component failure goes into the safe state, that indicates detection.

As you with a moving door from both sides of the door fingers in the Nebenschließkante 14 can pinch, provides the safety device according to the invention 100 optionally the possibility of two safety devices being arranged and coupled on both sides of the door. For example, then the monitoring can be set so that the monitoring result of both security devices can be queried in the evaluation of the security device of a door page.

The present invention provides a novel safety device for securing automatic doors. The safety device according to the invention can be used in particular as a moving or moving presence sensor, which can automatically adapt its Dektetionsfeld shape and size as a function of speed, position or acceleration. Such Sicherheitsvor devices can be used in particular in systems that can move relatively freely, z. B. in automatic transport systems. In the specific application described above, the sensor is mounted on a door leaf, ie the degrees of freedom of movement of the sensor are limited to a circular movement, for example in a swing door or on a linear movement, such as a sliding door. In a particularly preferred embodiment of the invention, a triangulation sensor with a particularly large base width, ie a particularly high triangulation sensitivity, is additionally provided. Triangulation sensors allow interference-free and reliable object recognition, especially when the vehicle is moving along. A surrounding area of a secondary closing edge can be protected by a light grid irradiated from above. By further features of the invention structural conditions can be hidden in a simple manner.

Claims (20)

Safety device for monitoring an automatic door, in particular an automatic swing door ( 10 ), in particular for carrying out the method according to one of Claims 14 to 20, with a transmitting unit attached to a door leaf of the door to be monitored ( 20 ) for emitting light ( 51 . 52 . 53 ) into a surveillance area ( 54 ) in an environment of the door panel, with a receiver unit ( 30 ) for receiving reflected and / or scattered light from the surveillance area ( 54 ) and one with the transmitting unit ( 20 ) and the receiver unit ( 30 ) operatively connected control and evaluation unit ( 80 ) for driving the transmitting unit ( 20 ), for evaluating measuring signals of the receiver unit ( 30 ) and for outputting control signals to a door controller ( 70 ) of the door to be secured, characterized in that on the door leaf ( 12 ) an acceleration sensor ( 90 ) for determining an acceleration of the door leaf ( 12 ) arranged with the control and evaluation unit ( 80 ) is operatively connected, that means for determining a position information from the measurement signals of the acceleration sensor are present and that the control and evaluation unit ( 80 ) depending on the position information the monitoring area ( 54 ) can change. Safety device according to claim 1, characterized in that the acceleration sensor ( 90 ) is a 2-quadrant sensor. Safety device according to one of claims 1 or 2, characterized in that the acceleration sensor ( 90 ) is attached to the outside of the door leaf in the area of the main closing edge. Safety device according to one of claims 1 to 3, characterized in that the acceleration sensor ( 90 ) in the same housing ( 28 . 38 ) like the transmitting unit ( 20 ) or the receiver unit ( 30 ) is integrated. Safety device according to one of claims 1 to 4, characterized in that the transmitting unit ( 20 ) a light pattern in the surveillance area ( 54 ) and that depending on the position of the door leaf ( 12 ) Parts of the light pattern are not taken into account in the detection. Safety device according to claim 5, characterized in that the light pattern comprises a plurality of light spots ( 51 . 52 . 53 ), in particular points of light, and that, depending on the position of the door leaf ( 12 ) individual light spots are not taken into account in the evaluation. Safety device according to one of claims 1 to 6, characterized in that the transmitting unit ( 20 ) and the receiver unit ( 30 ) form a triangulation sensor and that the transmitting unit ( 20 ) and the receiver unit ( 30 ) to provide a comparison with the dimensions of the transmitting unit ( 20 ) and the receiver unit ( 30 ) much larger base width in an upper area ( 13 ) on the door leaf ( 12 ) of the door to be secured are spaced from each other. Safety device according to one of claims 1 to 7, characterized in that the transmitting unit ( 20 ) and / or the receiver unit ( 30 ) in end housing parts ( 28 . 38 ) one on the door leaf ( 12 ) of the door to be protected ( 10 ) in the upper area ( 13 ) existing backup device ( 60 ) are arranged. Safety device according to one of claims 1 to 8, characterized in that the transmitting unit ( 20 ) a plurality of light sources ( 21 . 22 . 23 ), in particular semiconductor transmitter. Safety device according to one of claims 1 to 9, characterized in that the transmitting unit ( 20 ) has a luminous surface which images a light pattern on the floor via a partially opaque mask. Safety device according to one of claims 1 to 10, characterized in that the transmitting unit ( 20 ) a laser and a light-diffractive device, in particular a diffractive optic ( 24 ), and at least parts of the light pattern are formed by a diffraction pattern. Safety device according to one of claims 1 to 11, characterized in that the transmitting unit ( 20 ) on the door leaf ( 12 ) inside in the area of the secondary closing edge ( 14 ) and the receiver unit ( 30 ) outside in the area of the main closing edge ( 16 ) is arranged. Safety device according to one of claims 1 to 12, characterized in that the receiver unit ( 30 ) a detector ( 36 ) having a plurality of receiving elements or a PSD (Position Sensitive Device). Method for monitoring an automatic door, in particular an automatic revolving door, in particular using the safety device according to one of Claims 1 to 13, in which a transmitting unit ( 20 ) Light in a surveillance area ( 54 ) in an environment of the door ( 10 ), in which reflected and / or scattered light from the surveillance area ( 54 ) with a receiver unit ( 30 ) and in which, depending on measuring signals of the receiver unit ( 30 ) Control signals to a door control ( 70 ) of the door to be protected ( 10 ), characterized in that with one on the door leaf ( 12 ) on the door to be monitored ( 10 ) arranged acceleration sensor ( 90 ) a position of the door leaf ( 12 ) and that, depending on the position of the door leaf ( 12 ) the surveillance area ( 54 ) is adjusted. A method according to claim 14, characterized in that as acceleration sensor ( 90 ) a 2-quadrant sensor is used and that the measuring signals of the acceleration sensor ( 90 ) are subjected to a plausibility test. Method according to one of claims 14 or 15, characterized that in addition to the position signal and the actual acceleration signal is evaluated. Method according to one of claims 14 to 16, characterized in that the door ( 10 ) is a swing door and that a secondary closing edge ( 14 ) of this swing door ( 10 ) is monitored. Method according to one of claims 14 to 17, characterized in that a control and evaluation unit ( 80 ) the measuring signals of the receiver unit ( 30 ) with stored setpoint values and, in the event of qualified deviations of the measured signals from the setpoint values, control signals to a door control ( 70 ) of the door to be secured. Method according to one of Claims 14 to 18, characterized in that the measurement signals which are transmitted to the monitoring area ( 54 ) radiated light pattern go back, with free door as target values are learned. Method according to one of claims 14 to 19, characterized that very slow changes the measuring signals are continuously taught during operation.