DEVICE AND METHOD FOR DOOR AREA MONITORING

Abstract

The invention relates to a device for monitoring the door area of an at least partially glazed door. The device comprises a transmitter, an image recorder, a control unit, and an evaluation unit. The transmitter is used to emit at least one transmission pulse of electromagnetic radiation. The image recorder comprises a receiver matrix having at least one first receiver block, which has a plurality of first receivers. The first receivers of the first receiver block are designed and arranged in such a way that they receive reflected signal components of the transmission pulse in a second predetermined distance range of an outer region of the door area, the distance range being determined in relation to the door. Each first receiver has a memory unit which is designed to integrate and store the reflected signal components received. The control unit is configured to trigger a transmission pulse of the transmitter and to activate the first receivers of the first receiver block for a predetermined first receiving period after a predetermined first idle period which is longer than a period in which a signal of the transmission pulse reflected by the glazed door reaches the first receivers of the first receiver block. The evaluation unit is configured to read the stored signal components of the respective receiver and to process them into topography image data and to compare the topography image data with stored reference image data for a free door area, or is configured to read the stored signal components of the respective receiver and to determine a distance value on that basis and to compare the respective distance value with a stored reference value for a free door area.

Claims

1. A device for monitoring the door area of an at least partially glazed door, comprising at least one transmitter for emitting at least one transmission pulse of electromagnetic radiation, an image recorder comprising a receiver matrix with at least one first receiver block, which has a plurality of first receivers, wherein the first receivers of the first receiver block are configured and arranged in such a way that they receive reflected signal components of the transmission pulse in a second predetermined distance range of an outer region of the door area, the distance range being determined in relation to the door, wherein each first receiver has a memory unit which is configured to integrate and store the reflected signal components received, a control unit connected to the image recorder and the transmitter, which is configured: to trigger a transmission pulse of the transmitter, and to activate the first receivers of the first receiver block for a predetermined first receiving period after a predetermined first idle period which is longer than a period in which a signal of the transmission pulse reflected by the glazed door reaches the first receivers of the first receiver block, an evaluation unit, which is configured: to read the stored signal components of the respective receiver and to process topography image data, to compare the topography image data with stored reference image data for a free door area, or which is configured: to read the stored signal components of the respective receiver and to determine a distance value on that basis, and to compare the respective distance value with a stored reference value for a free door area.

2. A device according to claim 1, wherein the first receiver matrix comprises in addition at least one inner block, which has a plurality of first receivers, wherein the first receivers of the inner block are configured and arranged to receive signal components of the transmission pulse reflected in an inner region of the door area, wherein each first receiver has a memory unit that is configured to integrate and store the reflected signal components received, and where the control unit is configured to activate the first receivers of the inner block for a predetermined first inner receiving period immediately after the transmission pulse has been triggered.

3. A device according to claim 1, wherein the receiver matrix comprises a second receiver block, which has a plurality of first receivers, wherein the first receivers of the second receiver block are configured and arranged in such a way that they receive reflected signal components of the transmission pulse in a second predetermined distance range of an outer region of the door area, the distance range being determined in relation to the door, wherein each receiver has a memory unit in which the reflected signal components received are integrated and stored, and wherein the first predetermined distance range is closer to the door than the second predetermined distance range, and the control unit is configured to activate the first receivers of the second receiver block for a predetermined second receiving period after a predetermined second idle period which is longer than a period in which a signal of the transmission pulse reflected by the glazed door reaches the first receivers of the second receiver block.

4. A device according to claim 1, wherein an additional second receiver that is configured and arranged in the same way as the first receiver of the respective node is arranged immediately adjacent to each first receiver, wherein the second receiver has a memory unit which is configured to integrate and store the reflected signal components received, and wherein the control unit is configured to activate the second receiver for a predetermined delayed receiving period immediately after the respective receiving period of the respective first receiver.

5. A device according to claim 1, wherein the receiver matrix comprises at least one row and at least one column, in particular 320 rows and 240 columns.

6. A device according to claim 1, wherein the control unit is configured to trigger a transmission pulse of the transmitter and to activate the respective receivers multiple times, the memory unit of each receiver is configured to integrate and store the reflected signal components received of the respective receiver over multiple receiving periods of the receiver, and the control unit is configured to activate the evaluation unit only after integration over multiple receiving periods.

7. A device according to claim 6, wherein the control unit is configured to trigger transmission pulses of the transmitter and to activate the receivers until a predetermined signal level is reached in all memory units through integration, and to only activate the evaluation unit at that point in time.

8. A device according to claim 1, where the transmitter is a pulsed laser diode with a wavelength in the infrared range.

9. A device according to claim 1, wherein the door is a vehicle door, in particular a bus, tram or train door.

10. A device according to claim 1, wherein the door is an automatic door.

11. A device according to claim 1, wherein the evaluation unit is configured. to emit a warning signal, and/or to emit a signal for opening the door or a signal for keeping the door open to a door control unit of the door, if there are significant differences between the image data and the reference image data or if the distance value is smaller than a stored reference value.

12. A method for monitoring the door area of an at least partially glazed door, comprising the steps of emitting a transmission pulse of electromagnetic radiation, receiving reflected signal components of the transmission pulse in a predetermined first distance range of an outer region of the door area for a receiving period after a predetermined first idle period which is longer than a period in which a signal of the transmission pulse reflected by the glazed door reaches the first receivers of the first receiver block, integrating and storing the reflected signal components received, and reading the stored signal components, and processing the stored signal components into topography image data and comparing the topography image data with stored reference image data for a free door area, determining a distance value based on the stored signal components and comparing the respective distance value with a stored reference value for a free door area.

13. A method for monitoring the door area of an at least partially glazed door, comprising the steps of, emitting a plurality of transmission pulses of electromagnetic radiation at predetermined time intervals, determining a delay time for each emission of a transmission pulse, wherein the delay time increases incrementally with each transmission pulse, receiving a reflected signal component of the transmission pulse after the respective delay time, integrating and storing the reflected signal components received for each transmission pulse, determining a first and a second maximum value of the integrated signal components, wherein the first maximum value was reached at a shorter delay time than the second maximum value, determining a distance value based on the second maximum value, and comparing the respective distance value with a stored reference value for a free door area.

14. A method according to claim 13, wherein topography image data is generated from the specific distances and where said topography image data is compared with stored reference image data for a free door area.

15. A method according to claim 12, wherein the stored reference image data was recorded at a point in time at which it was known that the door area was free.

16. A method according to claim 12, wherein the stored reference image data are generated statically by generating and comparing a plurality of topography image data and by defining such topography image data as reference image data that remains unchanged over a predefined period of time.

17. A method according to claim 12, wherin the reference image data or the reference values are stored centrally.

Description

[0055] Exemplary embodiments of the invention are described below based on figures, wherein the figures show the following:

[0056] FIG. 1 shows schematically an exemplary embodiment of a device for door area monitoring according to the first aspect of the invention,

[0057] FIG. 2 shows schematically a receiver matrix with a plurality of first and second sensors,

[0058] FIGS. 3a and 3b show schematically the method principle of an exemplary embodiment of the method according to the second aspect of the invention,

[0059] FIG. 4 shows schematically the method principle of an exemplary embodiment of the method according to the third aspect of the invention; and

[0060] FIG. 5 shows a schematic diagram to explain the transit time measurement when the transmission pulses are sinusoidally modulated light signals.

[0061] FIG. 1 shows schematically an exemplary embodiment of a device for door area monitoring 100 according to the first aspect of the invention and the door area of a partially glazed door 200 monitored by means of said device. The device 100 comprises a transmitter 110 for transmitting at least one transmission pulse of electromagnetic radiation, and an image recorder 120. Furthermore, in the embodiment shown, the device 100 comprises a control unit 130 connected to the image recorder 120 and the transmitter 110 as well as an evaluation unit 140.

[0062] The image recorder 120 comprises a receiver matrix 150 with an inner block 1 and three receiver blocks 2, 3 and 4. The distance ranges respectively covered by the blocks are marked in FIG. 1. Accordingly, the receiver matrix is composed of: the inner block 1 with ml rows and n1 columns, the first receiver block 2 with m2 rows and n2 columns, the second receiver block 3 with m3 rows and n3 columns and the third receiver block 4 with m4 rows and n4 columns. In the specific example, the image recorder has the format of 320240 (QVGA). While it is expediently defined that n1=n2=n3=n4=240i.e. that the columns extend over the entire width of the sensor, the rows are distributed as follows: m1=160, m2=100, m3=40, m4=20. Each receiver block 2, 3, 4 has a plurality of first receivers A2, A3 and A4 in accordance with the columns and rows, and, respectively, a second receiver B2, B3 and B4 immediately adjacent to the first receiver A2, A3 and A4. The inner block 1 also has a plurality of first receivers A1 and associated second receivers.

[0063] It should be noted that a different choice regarding the size and orientation of the receiver matrix 150 of the image recorder 120 is possible as well, for example such that, in case of a QVGA image recorder, 320 columns are oriented transversely to the expected direction of movement, i.e. for example in the direction of a door width, while 240 rows are lined up in the direction of movement and are allocated to the receiver blocks m.sub.i. A simple structure of a receiver matrix 150 with 4 receiver blocks I, II, III, IV with respectively one row and 5 columns is shown in FIG. 2.

[0064] The first and second receivers of each receiver block 2, 3, 4 are configured to receive signal components of the transmission pulse reflected from certain distance ranges of the door area. The first and second receivers of the inner block 1 are configured and arranged to receive signal components of the transmission pulse that are reflected in an inner region of the door area. Subsequently, the reflected signal components received are integrated and stored in a memory unit of the respective receiver.

[0065] The control unit 130 is configured to trigger a transmission pulse of the transmitter 110 and to then activate the various receivers of the different blocks for predetermined periods based on a corresponding time regime, which is explained below based on FIG. 2. For each receiver block, the control unit 130 takes into account the orientation of the receiver block and therefore the transit time of a signal component reflected by the glass panels of the door 200, and activates the respective receiver only after an idle period that is longer than said transit time.

[0066] In the illustrated embodiment, the evaluation unit 140 is configured to read the stored signal components of the respective receiver and to process them into topography image data and to compare said topography image data with stored reference image data for a free door area. Alternatively, the evaluation unit 140 may be configured to read the stored signal components of the respective receiver, to determine a distance value from it and to compare the respective distance value with a stored reference value for a free door area.

[0067] FIG. 3a shows schematically the method principle of an exemplary embodiment of the method according to the second aspect of the invention and thus the time regime according to which the control unit 130 activates the different receivers An, Bn and triggers the transmitter 110. At the point in time 0, the transmission pulse 10, that in this example has the form of a square pulse of a pulsed laser diode, is triggered. In this example, the transmission pulse 10 has a duration of 30 ns.

[0068] After a third idle period of t4=660 ps, the first receivers A4 of the receiver block 4 are activated, and, after their first receiving period of 30 ns, the second receivers B4 of the receiver block 4 will be activated. The reflected signal components that are at a height distance of 10 cm from the receiver to the ground are stored in the memory units of the receivers A4 and B4. The first reflection at the glass panel at a distance of approximately 10 cm from the image recorder is not received due to the delay of 660 ps.

[0069] After a second idle period of t3=1.3 ns, the first receivers A3 of the receiver block 3 are activated, and, after their first receiving period of 30 ns, the second receivers B3 of the receiver block 3 will be activated. The reflected signal components that are at a height distance of 20 cm from the receiver to the ground are stored in the memory units of the receivers A3 and B3. The first reflection at the glass panel 200 at a distance of approximately 10 cm from the image recorder is not received due to the delay of 1.3 ns.

[0070] After a first idle period of t2=6.6 ps, the first receivers A2 of the receiver block 2 are activated, and, after their first receiving period of 30 ns, the second receivers B2 of the receiver block 2 will be activated. The reflected signal components that are at a height distance of 100 cm from the receiver to the ground are stored in the memory units of the receivers A2 and B2. The first reflection at the glass panel at a distance of approximately 100 cm from the image recorder is not received due to the delay of 6.6 ns.

[0071] The short idle periods require delay times in the ps (picosecond) range. Since the propagation speed of electrical pulses on a printed circuit board with copper is in the range of 67% of the speed of light in a vacuum, i.e. at approximately 5 ps/mm, the delay times are generated by a delay unit (not shown) integrated in the image recorder 120.

[0072] The image recording in the inner block 1 is carried out without delay, immediately after the transmission pulse has been triggered. There is no glass panel in the monitoring field of the inner block 1.

[0073] An image recording in accordance with the time regime described above may be repeated several times, until the amount of signal electrons obtained in the memory units of the receivers A and B reaches a sufficiently high signal level in all blocks. At that point, the evaluation unit reads the stored signal components of the respective receiver, processes it into topography image data and then evaluates them. To this end, the topography image data are stored in an image memory.

[0074] FIG. 3b shows by way of example the reception of reflected signal components and their integration in the receivers A3, B3, A2 and B2. Depending on the arrival of the reflected signal component Srelf in relation to the respective receiving time period, different components are attributed to the first receiver and the second receiver, where they are integrated and stored. Subsequently, it can be determined by means of the comparison between the two integrated signal components SiA3 and SiB3or, in case of the second receiver block, SiA2 and SiB2in which height range how large a component was reflected, which makes it possible to determine the precise height of the object that has caused the reflection.

[0075] FIG. 4 shows schematically the method principle of an exemplary embodiment of the method according to the third aspect of the invention. In this example, a plurality of transmission pulses SP of electromagnetic radiation are emitted at predetermined time intervals. Upon each transmission pulse M1 . . . Mi . . . Mj, a delay time for a receiving period EZ is determined, wherein said delay time increases from transmission pulse to transmission pulse. After the respective delay time Tvi . . . Tvj, the reflected signal components Sprefl are received and integrated (SPint) for each transmission pulse. In case of the first transmission pulse M1 in the illustration, only a small portion of the reflected signal component is integrated due to the delay between the reflected signal component SPref1 and the receiving period. If the delay time corresponds to the transit time of the signal component reflected by the door, as, in this example, in case of the transmission pulse Mi and the delay time Tvi, the integrated signal components reach a first maximum Max1. If, in a further measurement, in this example the one with transmission pulse Mj, correspondence is once again reached between the delay time Tvj and the transit time of signal components reflected by an object in the monitored outer region, a second maximum Max2 is reached. The first maximum value Maxi is discarded and a distance is determined based on the second maximum value, which was reached at a delay time Tvj that is longer than the delay time Tvi in case of the first maximum value Maxi. Subsequently, this distance value is compared with a stored reference value for a free door area.

[0076] If a sinusoidally modulated light signal is used for the transmission pulses, the signal transit time and, therefore, the distance value can be determined as shown in FIG. 5.

LIST OF REFERENCE NUMBERS

[0077] 100 device [0078] 110 transmitter [0079] 120 image recorder [0080] 130 control unit [0081] 140 evaluation unit [0082] 150 receiver matrix [0083] 200 door