Photoelectric barrier with distance measurement

Abstract

The invention relates to a light grid for determining the distance between a transmitting and a receiving strip, comprising a transmitting strip with one or more transmitting elements that emit radiation of a specific intensity, a receiving strip with one or more receiving elements that receive radiation from a paired transmitting element, and a controller for actuating the transmitting and / or receiving elements and for analyzing them.Each transmitting element and each receiving element, or at least one of them, is designed as a qualified transmitting and receiving element, wherein the qualified transmitting element or elements are designed to emit different intensities and / or the qualified receiving element or elements are designed to apply different degrees of amplification and to generate an intensity value for the received and amplified radiation, and the controller is designed to actuate different combinations of intensities and degrees of amplification of the qualified transmitting and / or receiving elements and to determine a distance value based on the sum of the intensity values ​​resulting from the actuated combinations.

Description

[0001] The invention relates to a light grid for object detection.

[0002] Light grids are known from the prior art, which have a transmitter strip and a receiver strip and form a grid of light beams between them for object detection. In particular, one or both strips of the light grid can be attached to the sliding door or doors of an elevator car to detect the passage of an object through the open door area.

[0003] From CN 111 273 371 A, a light curtain is known in which the transmitter and receiver can each be controlled by a control unit such that the transmitters emit at different intensities and the receivers amplify at different levels. In addition, the number of scanned time intervals during reception can be adjusted. This improves the installation of the light curtain, especially at greater distances, in order to reduce or eliminate inaccuracies during installation and inaccuracies caused by ambient light.

[0004] The object of the invention is to provide a light grid that enables more differentiated monitoring at low cost.

[0005] This problem is solved, starting from a light grating of the type mentioned above, by a light grating according to claim 1. Advantageous embodiments are specified in the further dependent claims.

[0006] The light grid according to the invention is a light grid for determining the distance between a transmitter and receiver strip, comprising a transmitter strip with one or more transmitter elements which emit radiation with a specific intensity, a receiver strip with one or more receiver elements which receive the radiation from an associated transmitter element, and a control device for controlling the transmitter elements and / or the receiver elements and for evaluating the receiver elements, wherein the transmitter element and the receiver element, or at least one of the transmitter elements and / or at least one of the receiver elements, are configured as qualified transmitter and receiver elements, wherein the qualified transmitter element or elements are configured to emit different intensities and / or the qualified receiver element or elements are configured toto apply different amplifications and output an intensity value for the received and amplified radiation, and the control device is designed to control different combinations of intensities and amplifications of the qualified transmitter and / or receiver elements and to determine a distance value depending on the sum of the resulting intensity values ​​of the controlled combinations.

[0007] This offers the advantage of determining the distance between the transmitter and receiver strips. At the same time, dynamic processes can be effectively tracked and analyzed. The grid, in turn, retains all its safety features.

[0008] The light grid, in particular the transmitter and receiver strip, has at least one or more further transmitter and receiver elements, each designed as a simple transmitter element and simple receiver element, each designed as a light barrier, and which preferably do not contribute to the combinations and / or from which the distance value is not determined, and / or which are used for object detection, and / or whose simple transmitter elements emit at least an intensity as the qualified transmitter elements and whose receiver elements have at least an amplification as the qualified receiver elements.

[0009] This can offer the advantage that the light grid can be used for object detection. This can also offer the advantage that not all transmitter and receiver elements need to be highly sophisticated, thus reducing the complexity of the light grid and saving costs. However, such an embodiment of the invention also allows for a compromise between accurate object detection and cost savings, which arises from the fact that not all transmitter and receiver elements need to be equipped with the same functions; individual elements can be equipped with fewer functions, making them more cost-effective.

[0010] According to the invention, the control device is configured to control the combinations successively in a sequence and, in particular, to repeat the sequence periodically and, in particular, to determine the sum of the controlled combinations of a sequence and, in particular, to determine a distance value for each sequence. Preferably, the control device is configured to control all different combinations of intensities and gains of the qualified transmitter and / or receiver elements, but in particular, without using the highest intensity of the qualified transmitter elements for the combinations, and / or to use those intensities and gains of the qualified transmitter and receiver elements for object detection which correspond to the intensities and gains of simple (non-qualified) transmitter and / or receiver elements.

[0011] This can offer the following advantages: a fixed time period after which the distance value is available; the distance value is determined quasi-continuously; and the distance value is dynamically available over time. This can offer the advantage that the distance value can be calculated quickly and easily. This can offer the advantage of achieving maximum resolution or accuracy for the distance value. This can offer the advantage that the number of transmitter and receiver elements required for object detection does not need to be increased by using qualified transmitter and receiver elements.

[0012] Preferably, the one or more qualified transmitter elements are designed to each individually emit several different intensities, and / or to emit intensities that differ from each other, and / or to each emit the same intensity, which is in particular the highest intensity and corresponds in particular to the intensity of the non-qualified transmitter elements.

[0013] This can offer the advantage of providing optimized intensities for different distance ranges, increasing the resolution of the distance value, and ensuring that the resolution of the distance value remains consistently high across the entire distance range. This can also allow the qualified transmitter elements to be used for object detection.

[0014] Preferably, the one or more qualified receiver elements are configured to apply several different gains individually, and / or to apply the same different gains, and / or to apply one identical gain, which is in particular the highest, and in particular corresponds to the gain of the non-qualified, i.e. simple, receiver elements.

[0015] This can offer the advantage that optimized gains are available for different distance ranges, that the resolution of the distance value is increased, and that the resolution of the distance value remains consistently high across the entire distance range. This can also offer the advantage that the qualified receiver elements can be used for object detection.

[0016] Preferably, the light grid comprises three qualified transmitter and receiver elements, as well as additional simple transmitter and receiver elements that do not contribute to the combinations and / or from which the distance value is not determined. Preferably, the one or more qualified transmitter elements are configured to emit three intensities each, one of which is equal to the intensity of the unqualified, i.e., simple, transmitter elements used for object detection, and two of which are lower than the one equal intensity and each differ from all other intensities. Preferably, the one or more qualified receiver elements are configured to apply the same two different gains, the higher gain corresponding to the gain of the unqualified, i.e., simple, receiver elements used for object detection.Preferably, the control device is configured to form twelve combinations of the three qualified transmitter and receiver elements, the two overall different, lower intensities of the qualified transmitter elements, and the two different, but identical, gains of the receiver elements. Preferably, the control device is configured to use those intensities and gains of the qualified transmitter and receiver elements for object detection which correspond to the intensities and gains of unqualified, i.e., simple, transmitter and / or receiver elements.

[0017] This can offer the advantage of providing a very fine resolution for the distance value.

[0018] Preferably, the light grid has a transmitting device designed to wirelessly transmit the distance value.

[0019] This can offer the advantage that the behavior of the cabin door can be transmitted and evaluated without interfering with the elevator's control and electronics.

[0020] Further features of the invention are shown in the drawings.

[0021] The advantages mentioned can also materialize for combinations of features in which they are not explicitly mentioned. Overview of the drawings:

[0022] Exemplary embodiments of the invention are shown in the drawings and are explained in more detail below. Identical reference numerals in the individual figures denote corresponding elements. The figures show: Fig. 1 Light grid Fig. 2a Open double sliding door of an elevator car with light grid Fig. 2b Half-open double sliding door as Fig. 2a Fig. 2c Closed double sliding door as Fig. 2a Fig. 3 Diagram of a measurement curve Fig. 4 Diagram with all measurement curves Fig. 5 Diagram of the distance value Detailed description of the drawings:

[0023] Fig. 1 Figure 1 shows a light grid 20 according to the invention, comprising a transmitter strip 21 and a receiver strip 22. The transmitter strip 21 has three qualified transmitter elements 31 and further non-qualified transmitter elements 33, which can emit IR radiation with a specific intensity. The receiver strip 22 has three qualified receiver elements 32 and further non-qualified receiver elements 34. The transmitter strip and receiver strip are arranged perpendicularly and parallel to each other at the same height. Each qualified transmitter element 31 is assigned a qualified receiver element 32 at the same height, and together these form a horizontal transmitter beam 30. The light grid 20 also includes a control device 35.

[0024] Fig. 2a bis 2c The light grid 20 of the Fig. 1 on a double sliding door 10 of an elevator car. The transmitter strip 31 is attached to one leaf of the double sliding door and the receiver strip 32 is attached to the opposite leaf of the double sliding door. The remaining arrangement is as shown in Fig. 1 Transmitter strip 31 and receiver strip move with the double sliding doors, remaining parallel and at the same height, so that the light beams remain horizontal and aligned with the corresponding qualified transmitter and receiver elements. They decrease their distance along with the doors when they close and increase their distance along with the doors when they open. The distance between the transmitter and receiver strips corresponds to the distance between the two leaves of the double sliding door, up to a constant factor. Fig. 2a shows the open door. Fig. 2b shows the half-closed door. Fig. 2c shows the closed door.

[0025] The unqualified transmitting elements transmit with an intensity of Tx:High, and the unqualified receiving elements exhibit two gains: Rx:High and Rx:Low. Rx:Low is lower than Rx:High. The gains are applied simultaneously and evaluated separately.

[0026] The first qualified transmitter element T1 can transmit at the intensity T1:Low1, T1:Mid1, or T1:High; the second qualified transmitter element T2 can transmit at the intensity T2:Low2, T2:Mid2, or T3:High; and the third qualified transmitter element T3 can transmit at the intensity T3:Low3, T3:Mid3, or T3:High. The intensities Tx:High, T1:High, T2:High, and T3:High are equal. All other intensities are lower. The sequence of intensities is ascending: T1:Low1 < T2:Low2 < T3:Low3 < Mid1 < Mid2 < Mid3 < Tx:High. The three qualified receiver elements R1, R2, and R3 can each apply the gains Rx:Low or Rx:High.

[0027] The control unit controls the unqualified transmitter and receiver elements in such a way that Rx:High is applied for distances over 1 m and Rx:Low is applied for distances under 1 m, the latter to avoid reflections.

[0028] The control unit manages a sequence of combinations of different intensities and gains and evaluates them to obtain a distance value. The highest intensity, Tx:High, is not used for this purpose. The combinations are each controlled and evaluated separately. The combinations are: T 1 : Low 1 + R 1 : Low , T 1 : Mid 1 + R 1 : Low , T 1 : Low 1 + R 1 : High , T 1 : Mid 1 + R 1 : High T 2 : Low 2 + R 2 : Low , T 2 : Mid 2 + R 2 : Low , T 2 : Low 2 + R 2 : High , T 2 : Mid 1 + R 2 : High T 3 : Low 3 + R 3 : Low , T 3 : Mid 3 + R 3 : Low , T 3 : Low 3 + R 3 : High , T 3 : Mid 1 + R 2 : High

[0029] These are 12 combinations.

[0030] Fig. 3 Diagram 40 shows the intensity as a function of distance and displays the measurement profile of a combination. The x-axis (41) shows the distance between the transmitter strip and the receiver strip. Point 42 indicates the minimum distance, and point 43 indicates the maximum evaluable distance. The y-axis (44) shows the intensity value output by a qualified receiver element for a specific combination.

[0031] Measurement curve 51 shows an example of a combination with medium intensity of the qualifying transmitter element and medium gain of the qualifying receiver element. Measurement curve 51 exhibits a very steep curve at medium distances, saturates at shorter distances, and shows no signal at longer distances. Therefore, the measurement curve only represents a small distance range with good resolution.

[0032] Fig. 4 is a diagram 40 according to Fig. 3 and shows a superposition of all twelve measurement curves 52 for the twelve combinations.

[0033] The different intensities and the gain Rx:Low are chosen to achieve a largely uniform sequence of the steep curves over the distance.

[0034] Fig. 5 The graph shows the sum of the intensity values ​​of all twelve combinations. The x-axis is analogous to the... Fig. 3 The y-axis shows the sum of 71 of the intensity values ​​of all twelve combinations of Fig. 4 The sum shows a largely linear progression over the entire distance.

[0035] The control unit adds the measured and amplified intensity values ​​of the twelve combinations of a sequence and outputs a distance value as a function of the sum. The control unit repeats the sequence periodically and outputs the distance value periodically.

[0036] The light curtain according to the invention can be used to measure the opening movement of the cabin door of an elevator. Likewise, the distance between movable boundaries of a passage monitored by a light curtain and the light curtain itself can be measured.

[0037] The light grid according to the invention can include a transmitter that wirelessly transmits the distance value, and in particular to a web cloud. This makes the data available for analysis or allows it to be stored for extended periods, acting like a black box to provide information about process flows. In particular, this allows an elevator door to be monitored independently of the elevator control system. Reference symbol list:

[0038] 10 cabin doors 20 Light grid 21 Transmitter strip 22 Receiver strip 30 Light beams 31 Qualified transmitter elements 32 Qualified receiver elements 33 Simple transmitter elements 34 Simple receiver elements 35 Control device 40 Diagram of intensity as a function of distance 41 X-axis: Distance between transmitter and receiver strip 42 Minimum distance 43 Maximum distance 44 Y-axis: Received and amplified intensity 45 No detection 46 Saturation 51 Measurement curve for one intensity and one gain 5212 Measurement curves from 6 intensities and 2 gains 60Diagram of the sum of the 12 received measurement curves 64Y-axis: Sum of the amplified intensities 71 Sum of the 12 measurement curves of 6 intensities and 2 gains

Claims

1. Light grid for determining the distance between transmitter and receiver strips, having a transmitter strip with one or more transmitter elements that emit radiation at a specific intensity, having a receiver strip with one or more receiver elements that receive the radiation from an associated transmitter element, and having a control device for controlling the transmitter elements and / or the receiver elements and for evaluating the receiver elements, wherein in each case the transmitter element and the receiver element or in each case at least one of the transmitter elements and / or at least one of the receiver elements are designed as qualified transmitter and receiver elements, wherein the qualified transmitter element or the qualified transmitter elements are designed to emit different intensities, and / or the qualified receiver element or the qualified receiver elements are designed to apply different gains and output an intensity value for the received and amplified radiation, wherein the light grid furthermore comprises at least one or more further transmitter and receiver elements, which are each designed as simple transmitter elements and simple receiver elements and which are each designed as a light curtain, characterized in that the control device is designed to set different combinations of intensities and gains of the qualified transmitter and / or receiver elements and to ascertain a distance value on the basis of the sum of the resultant intensity values of the set combinations, wherein the control device is designed to set the combinations successively in a sequence and repeat the sequence periodically and to ascertain the sum of the set combinations of a sequence and to ascertain a distance value for each sequence.

2. Light grid according to Claim 1, characterized in that the one or more further transmitter and receiver elements, which are each designed as simple transmitter elements and simple receiver elements and which are each designed as a light curtain, preferably do not contribute to the combinations and / or in that the distance value is not ascertained therefrom, and / or in that they are used for object detection, and / or in that their simple transmitter elements emit at least one intensity like the qualified transmitter elements and their receiver elements have at least one gain like the qualified receiver elements.

3. Light grid according to Claim 1 or 2, characterized in that the control device is designed to set all different combinations of intensities and gains of the qualified transmitter and / or receiver elements.

4. Light grid according to Claim 3, characterized in that the control device is designed to set all different combinations of intensities and gains of the qualified transmitter and / or receiver elements without using the highest intensity of the qualified transmitter elements for the combinations, or to use those intensities and gains of the qualified transmitter and receiver elements for object detection that correspond to the intensities and gains of simple transmitter and / or receiver elements.

5. Light grid according to any of Claims 1 to 4, characterized in that the one or more qualified transmitter elements are designed to each emit a plurality of different intensities on an individual basis or to emit mutually different intensities or to each emit an identical intensity.

6. Light grid according to Claim 5, characterized in that the one or more qualified transmitter elements are designed to emit an intensity which is the highest intensity and corresponds to the intensity of the simple transmitter elements.

7. Light grid according to any of Claims 1 to 6, characterized in that the one or more qualified receiver elements are designed to each apply a plurality of different gains on an individual basis or to apply the same different gains or to each apply an identical gain.

8. Light grid according to Claim 7, characterized in that the one or more qualified receiver elements are designed to apply a gain which is the highest gain and corresponds to the gain of the simple receiver elements.

9. Light grid according to any of Claims 1 to 8, characterized in that the light grid in each case comprises three qualified transmitter and receiver elements and furthermore comprises simple transmitter and receiver elements that do not contribute to the combinations and / or from which the distance value is not ascertained, the one or more qualified transmitter elements are designed to emit three intensities in each case, wherein one intensity is equal to the intensity of the simple transmitter elements that are provided for object detection, and wherein two intensities are lower than the identical intensity and in each case differ from all other intensities, and the one or more qualified receiver elements are designed to apply the same two different gains in each case, wherein the higher gain corresponds to the gain of the simple receiver elements that are provided for object detection, and the control device is designed to form twelve combinations from the three qualified transmitter and receiver elements, the two altogether different, lower intensities of the qualified transmitter elements and the two different, in each case identical gains of the receiver elements and to use those intensities and gains of the qualified transmitter and receiver elements that correspond to the intensities and gains of simple transmitter and / or receiver elements for object detection.

10. Light grid according to any of Claims 1 to 9, characterized in that the light grid comprises a transmission device that is designed to send the distance value wirelessly.

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