Security system for conversion machines
The security system in converting machines uses multiple sensors and geometric analysis to enhance detection of prohibited objects, ensuring accurate identification and preventing unauthorized access during light barrier muting, thus improving safety.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- ボブストリヨン
- Filing Date
- 2022-10-26
- Publication Date
- 2026-06-25
AI Technical Summary
Existing security systems in converting machines, such as rotary punching and folding-gluing machines, fail to accurately detect prohibited objects during the muting time of light barriers, posing a risk of unauthorized access and operator injury.
A security system utilizing multiple sensors with vertical detection directions and an evaluation unit to analyze the arrival and departure times of objects, along with geometric analysis of control signals, to detect prohibited objects independently of distance, combined with a light barrier muting mechanism to enhance detection accuracy.
The system effectively prevents unauthorized access by accurately distinguishing between permitted and prohibited objects, even during light barrier muting, thereby enhancing safety and reducing operator risks.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to a security system and method for preventing unauthorized access in a converting machine.
Background Art
[0002] Converting machines, such as rotary punching machines and folding-gluing machines, are used in the manufacture of paperboard and cardboard boxes, such as flat box packages and folding boxes.
[0003] These machines include a plurality of workstations capable of printing, cutting, and creasing a sheet substrate. Overall, it is desirable to prevent human access to moving machine parts during operation of the converting machine. Auxiliary modules, such as a palletizer and a breaker module, may be located in the downstream section of the rotary punching machine. It is particularly desirable to protect the palletizer module and the breaker module to prevent operator injury.
[0004] It is known to use a light barrier or a scanning device that forms an invisible barrier closure in a restricted access area of a machine workstation, such as a palletizer module. When a human passes through the light barrier, the light barrier will generate a stop signal for the machine. However, such a light barrier is muted for a specific time to allow stacked boxes to pass through.
[0005] During the muting time, there remains a risk that an operator or other prohibited object will pass through the light barrier together with other conveyed objects.
Summary of the Invention
Problems to be Solved by the Invention
[0006] In view of the above problems, an object of the present invention is to provide an improved security system having the ability to detect prohibited objects even when the light barrier is muted. [Means for solving the problem]
[0007] This objective is achieved by the security system described in claim 1 and the method described in claim 11.
[0008] According to a first aspect of the present invention, a security system for a conversion machine is provided, and the security system is A detection unit comprising multiple sensors arranged side by side, each sensor having a separate control area, the detection unit configured to detect the arrival time of an object being transported through the control areas and the departure time from each control area, the arrival time and departure time of the object being determined from control signals from each sensor, the control signals from each sensor including rising and falling signals, and each sensor having a vertical detection direction, An evaluation unit is configured to receive control signals from each sensor of a detection unit, determine the arrival time from the rising edge signal and the departure time from the falling edge signal, and supply an error signal when an error condition is determined. The evaluation unit includes a memory containing a program that causes an error state indicating the presence of a prohibited object based on the arrival time and / or departure time in each control area, It is equipped with.
[0009] The present invention is based on the recognition that additional safety systems can be used alone or in combination with a light barrier to analyze the geometry of objects being transported in more detail. In this way, prohibited objects such as people can be detected regardless of the muting time of the light barrier.
[0010] Since the evaluation is based on the analysis of individual control signals, a more accurate detection mechanism can be realized.
[0011] Conveniently, detection does not depend on distance-dependent detection mechanisms. Rather, the presence of an object within each control region is sufficient. Therefore, the sensor does not need to be able to detect any precise distance in order to determine the height of the object being transported.
[0012] In one embodiment, the security system further comprises an optical barrier system comprising an optical barrier and a muting device, the muting device comprising an upstream muting detector and a downstream muting detector located on the opposite side of the optical barrier, The security system includes a control unit configured to activate a muting device to mute the light barrier when an object being transported is detected by an upstream muting detector, and to activate the light barrier when an object is detected by a downstream muting detector. The sensors in the detection unit are configured to be activated when the upstream muting detector generates a muting signal and the light barrier is muted. The control unit is configured to receive an error signal from the evaluation unit and generate a stop signal when an error condition is detected.
[0013] In one embodiment, the sensors are positioned in a line at equal distances from each other. The sensors may include photoelectric cells, laser scanners, or capacitive sensors.
[0014] In one embodiment, the evaluation unit is further configured to calculate the duration between the rising and falling edges of the signals from each sensor, and the evaluation unit is configured to determine an error state if the durations for each sensor are different.
[0015] In one embodiment, the evaluation unit is further configured to calculate the phase shift between the rising edge signals of directly adjacent sensors, and an error condition is determined if a phase shift exists.
[0016] The evaluation unit can be configured to determine a first ordered sequence of transition events from a first state to a second state of the received control signal, and a second ordered sequence of transition events from a second state to a first state of the received control signal, and the error state is determined based on the difference between the first ordered sequence and the second ordered sequence.
[0017] In one embodiment, the evaluation unit is configured to determine an interpolated first timeline defined by a switching event from a first state to a second state of the received control signal, and to determine an interpolated second timeline defined by a switching event from a second state to a first state of the received control signal, and the error state is determined based on the non-parallel first and second timelines.
[0018] The security system may further include a control unit configured to generate a stop signal to deactivate the workstation of the converter machine or the entire converter machine when it receives an error signal from the evaluation unit.
[0019] According to a second aspect of the present invention, a conversion machine is provided which comprises a security system as described in any of the above aspects or embodiments, wherein the sensor is positioned horizontally on the travel path of the conversion machine and above an access opening to a restricted access area of the conversion machine.
[0020] A third aspect of the present invention provides a method for protecting a restricted access area of a conversion machine, the method being: A step of detecting the arrival time and departure time of an object within the control area of multiple sensors, wherein the sensors have a vertical detection direction, The step of receiving control signals from each sensor to the evaluation unit, wherein the control signals define the arrival time from the rising edge signal and the departure time from the falling edge signal. A step of determining the presence of a prohibited object based on the arrival and departure times of each control signal, including.
[0021] In one embodiment, before detecting the arrival time and departure time of an object, the method receives information from an upstream muting detector and generates a muting signal that mutes an optical barrier when an allowable object to be transported is detected; activating a plurality of sensors of the detection unit when the optical barrier is turned off; further including.
[0022] In one embodiment, the presence of a prohibited object the difference in the duration for each control signal from the first state to the second state from each sensor, and / or the phase shift between subsequent switching points of different individual control signals from different sensors, and / or the difference between the first ordered sequence of switching events of the control signal from the first state to the second state and the second ordered sequence of switching events of the control signal from the second state to the first state, and / or non-parallel interpolated first and second timelines, wherein the interpolated first timeline is defined by a switching event of the control signal from the first state to the second state, and the interpolated second timeline is defined by a switching event of the control signal from the second state to the first state, the first and second timelines is determined by an evaluation unit based on at least one of the steps.
[0023] Hereinafter, the present invention will be described with reference to the accompanying drawings in which like reference numerals denote like features.
Brief Description of the Drawings
[0024] <^ [Figure 1] is a schematic diagram of a conversion machine. <^ [Figure 2] is a schematic perspective view of a security system around a restricted access area. [Figure 3] is a schematic diagram showing the electrical configuration of a safety device. [Figure 4a] This is a schematic top view of an intrusion scenario in the access area to the restricted region. [Figure 4b] This is a diagram of the generated detection signal. [Figure 5a] This is a schematic diagram of another intrusion scenario. [Figure 5b] This is a schematic diagram of another intrusion scenario. [Figure 6a] Here is a schematic diagram of yet another intrusion scenario. [Figure 6b] Here is a schematic diagram of yet another intrusion scenario. [Figure 7a] This is a schematic diagram of further intrusion scenarios. [Figure 7b] This is a schematic diagram of further intrusion scenarios. [Figure 8a] This is a schematic diagram of further intrusion scenarios. [Figure 8b] This is a schematic diagram of further intrusion scenarios. [Figure 9a] This is a schematic diagram of further intrusion scenarios. [Figure 9b] This is a schematic diagram of further intrusion scenarios. [Figure 10] This is a schematic diagram of a method for protecting the restricted area of a conversion machine. [Modes for carrying out the invention]
[0025] Figure 1 shows a converter machine 1 in the form of a rotary punching machine 1. The converter machine 1 comprises multiple workstations in the form of modules. Although several configurations are possible, an exemplary converter machine 1 may include a pre-feeder module 2, a feeder module 3, a printing module 4 with multiple printing units 5, a punching module 6, a stacker module 7, and at least one auxiliary workstation such as a breaker module 8 or a palletizer module 9. The main operator interface 11 may also be located near the converter machine 1.
[0026] The feeder module 3 is configured to supply sheet substrate to the conversion machine 1. The sheet substrate is converted into blanks and transported through the conversion machine 1 along the transport path P in the transport direction T. Before reaching the breaker module 8, the blanks may consist of multiple juxtaposed box blanks that need to be separated.
[0027] The security system 10 is located in the workstation of the conversion machine 1. Conveniently, the security system can be located in the breaker module 8 or the palletizer module 9, which is further shown in Figure 2. However, the security system can be located around any of the aforementioned modules 2, 3, 4, 5, 6, or 7. For simplicity, the following description will describe the security system 10 located in the breaker module 8 or the palletizer module 9.
[0028] As shown in Figure 2, restricted access area A is located within enclosure 15. Workstations 8 and 9 are located within restricted access area A. Preferably, a portion of enclosure 15 is formed by physical side barriers 16, such as a fence. Workstations 8 and 9 are configured to receive permissible objects 24 in the form of blanks or stacks of multiple stacked blanks. The permissible objects 24 can be transported into the restricted area by a conveyor 19, such as a belt conveyor 19.
[0029] The enclosure 15 prevents unauthorized access of prohibited objects 32 to workstations 8 and 9. Prohibited objects 32 can be people such as machine operators, or physical objects such as tools. Therefore, prohibited objects 32 are different from permitted objects 24.
[0030] Therefore, in the context of this application, the terms “objects 24, 32” refer to either an independent permissible object 24, or a combination of permissible objects 24 and prohibited objects 32 arranged in close proximity to each other.
[0031] The enclosure 15 has an access opening 12, which can be protected by an optical barrier system 13 comprising an optical barrier 14, and a muting device 20 comprising an upstream muting detector 20a and a downstream muting detector 20b. Thus, the upstream muting detector 20a is located upstream in the transport direction T or in front of the optical barrier 14, and the downstream muting detector 20b is located downstream in the transport direction T or behind the optical barrier. The optical barrier 14 may have a plurality of optical transmitters and optical receivers that will detect an error condition if the transmitted optical signal is not received by the associated receiver.
[0032] The upstream muting detector 20a and the downstream muting detector 20b are positioned on the opposite side of the optical barrier 14. The upstream muting detector 20a is configured to send a control signal 21a to mute, or turn off, the optical barrier 14 when the permitted object 24 is within the detection area of the upstream muting detector 20a. Similarly, the downstream muting detector 20b is configured to send a control signal 21b to reactivate the optical barrier 14 when the object 24 is within the detection area of the second muting detector 20b. Thus, the optical barrier 14 is muted to allow the permitted object 24 to enter restricted area A.
[0033] A problem arises when the prohibited object 32 is positioned in close proximity to the permitted object 24 being transported. In such a scenario, during the muting time of the light barrier 14, the prohibited object 32 may be able to pass through the light barrier 14 together with the permitted object 24.
[0034] To prevent this possibility, restricted access area A is equipped with a security system 10 according to the present invention. As shown in Figures 2 and 3, the security system 10 may further include an optical barrier system 13 and a detection unit 20, an evaluation unit 26, and a memory 25. The security system 10 may also include a control unit 28.
[0035] The detection unit 20 is positioned horizontally on the movement path P of the transforming machine, above the access opening 12, and comprises a plurality of sensors 22a to 22f arranged side by side. Each of the sensors 22a to 22f comprises a sensing element 22' having a separate control region Z, and a control circuit configured to send control signals 23a to 23f to the evaluation unit 26. Each sensor has a vertical sensing direction. Different sensors are referred to using a common number 22 and letters a through f, the letters used to distinguish a particular sensor from the plurality. A reference number 22 without a letter indicates any sensor or the plurality of sensors. The sensors 22 can be positioned in a line at equidistant distances d1 from each other. The distance d1 can be selected, for example, such that the distance between each control region Z is less than a predetermined width of a person or part of a person's body.
[0036] Each sensor 22a to 22f is configured to detect when its control region Z is occupied by an object 24, 32. Sensors 22a to 22f can be in the form of a photoelectric cell, a laser scanner, or a capacitive sensor. In some configurations, a combination of these sensor types can be used.
[0037] Each sensor 22 is configured to supply a control signal 23 having a first state when its respective control region Z is not occupied, and a second state when its respective control region Z is occupied by objects 24 and 32.
[0038] Control signals are referenced using a common number 23 and letters from a through f, where the letters are used to distinguish a particular signal from a group. Reference number 23 without a letter indicates one or more signals from a group.
[0039] The control signals 23 can be generated independently of the shapes of objects 24 and 32. Therefore, each sensor 22 is configured to detect the presence of objects 24 and 32 in its respective control region Z. Occupying each control region Z is sufficient to activate the respective control signals 23. Changes in state can be characterized by a rising edge signal 36a when objects 24 and 32 enter the control region Z of sensor 22, and by a falling edge signal 36b when objects 24 and 32 leave the control region Z.
[0040] Muting detectors 20a and 20b are configured to individually supply control signals 21a and 21b to mute or activate the optical barrier 14. Muting signal 21a is generated when each muting region is occupied by an object 24 or 32. Muting signal 21 can be generated independently of the shape of objects 24 or 32. Alternatively, muting signal 21a can be transmitted based on an analysis of the characteristics of objects 24 or 32, such as the time it takes for objects 24 or 32 to reach the upstream muting detector 20a.
[0041] In an embodiment, the security system 10 may optionally include a second detection unit (not shown), which is vertically positioned and includes a sensor with a horizontal detection direction. This can further improve the detection of prohibited objects 32 that are positioned above the permissible objects 24 being transported.
[0042] The evaluation unit 26 is preferably connected to the muting detectors 20a and 20b and the sensor 22. The evaluation unit 26 is configured to receive muting signals 21a and 21b from the respective muting detectors 20a and 20b, and control signals 23 from the respective sensor 22. Based on the received signals 21 and 23, the evaluation unit 26 can determine an error state and supply an error signal 27.
[0043] The control unit 28 is configured to receive an error signal 27 from the evaluation unit 26 and to control the operation of the conversion machine 1. Upon receiving the error signal 27 from the evaluation unit 26, the control unit 28 can generate a stop signal 29 to deactivate the workstations 8 and 9 located within the restricted access area A, or to deactivate the entire conversion machine 1.
[0044] The control unit 28 may be further configured to mute the light barrier 14 when the transported permissible object 24 is detected by the upstream muting detector 20a. Similarly, the control unit 28 may be further configured to activate the light barrier 14 when the permissible object 24 is detected by the downstream muting detector 20b.
[0045] In this embodiment, the evaluation unit 26 and the control unit 28 can be combined into a single device. Alternatively, as described above, the control unit 28 and the evaluation unit 26 can be two different components.
[0046] When the light barrier 14 is activated, the intrusion of any prohibited object 32 will generate an error signal 27, and the control unit 28 will generate a stop signal 29 for the conversion machine 1.
[0047] When the upstream muting detector 20a is activated, for example, by the transported permissible object 24, a corresponding muting signal 21a is supplied. Subsequently, the optical barrier 14 is muted (turned off) at the start of the muting signal 21a transmitted by the upstream muting detector 20a. The muting of the optical barrier 14 stops when the muting signal 21b of the downstream muting detector 20b detects that the object 24 has completed its passage. Since the optical barrier 14 is muted, the permissible object 24 can pass through without causing an error (i.e., an intrusion signal) from the optical barrier 14. Thus, the safety system is configured to operate only when the optical barrier 14 is muted.
[0048] In this case, further prohibited objects 32, such as parts of the operator's body, may pass through the access opening 12. For this reason, the sensor 22 is configured to detect the occupancy of each respective control region Z.
[0049] Based on the evaluation of individual control signals 23a to 23f, the evaluation unit 26 is configured to determine the shape of objects 24, 32 passing through the access opening 12. If the determined shape is not rectangular, or alternatively, does not conform to a predetermined shape, the evaluation unit 26 may consider this an error condition. As a result, based on the error signal 27, the entire conversion machine 1 or the workstations 8, 9 in restricted access area A may be turned off.
[0050] As shown in Figure 2, the permitted object 24 moves along the transport direction T toward the restricted access area A. The object 24 will first activate the upstream muting detector 20a to mute the light barrier 14. Sensors 22a to 22f of the detection unit can be activated when the upstream muting detector 20a generates a muting signal 21. Therefore, the control unit 28 can be configured to activate sensors 22a to 22f when the upstream muting detector 20a generates a muting signal 21.
[0051] Multiple sensors 22a to 22f are configured to detect the passage of objects 24 and 32 by detecting their leading edge E1 and trailing edge E2. The detection of the leading edge E1 is characterized by a rising edge signal 36a, and the detection of the trailing edge is characterized by a falling edge signal 36b. Sensors 22a to 22f generate individual control signals 23a to 23f related to the detection of the leading edge E1 and trailing edge E2 of objects 24 and 32.
[0052] When the individual control regions Z of sensors 22a to 22f are occupied by objects 24 and 32, the respective control signals 23a to 23f change from a first state 34 to a second state 36. This is schematically represented, for example, in Figure 4b, which shows the individual control signals 23a to 23f related to time t.
[0053] The security system 10 detects an error state by analyzing a first time t1 in which sensors 22a to 22f detect a switch from a first state to a second state, and a second time t2 in which a switch occurs between the second state and the first state. The first time t1 and the second time t2 are determined by the evaluation unit 26. The switch between the first state 34 and the second state 36 occurs when the leading edge E1 and trailing edge E2 of objects 24 and 32 are detected within their respective control regions Z. Therefore, the first time t1 occurs with the rising edge signal 36a, and the second time t2 occurs with the falling edge signal 36b.
[0054] Therefore, the first time t1 corresponds to the arrival time t1 of the leading edge E1 to each control region, and the second time t2 corresponds to the departure time t2 of the trailing edge E2 of the objects 24 and 32 being transported through each control region Z. In other words, the detection unit 20 is configured to detect the arrival time t1 of the objects 24 and 32 to each control region Z and the departure time t2 of the objects being transported through each control region Z.
[0055] As shown in Figures 4a to 9b, the security system 10 is configured to detect prohibited objects 32 located at various positions near permitted objects 24. These illustrated scenarios represent only some of the possible error scenarios.
[0056] In the first scenario, as shown in Figure 4a, the additional prohibited object 32 is positioned in front of the permitted object 24 and partially overlaps with the permitted object 24 in the lateral direction L (Figure 2).
[0057] As shown in Figure 4b, the evaluation unit 6 is configured to calculate the duration Σt between the rising and falling signals from each sensor. The evaluation unit 26 is further configured to determine the presence of an error state based on the difference in duration Σt between the individual control signals 23a to 23f relating to the switching between the first state 34 and the second state 36. For example, since the duration Σt_23b of control signal 23b is different from the durations of the other activated control signals 23c to 23e, the evaluation unit 26 can determine that an error state exists.
[0058] In the second scenario, as shown in Figures 5a and 5b, the prohibited object 32 is positioned behind the permitted object 24 in the transport direction T. Similar to the first scenario, the duration Σt_23b of the control signal 23b is also different in this case from the duration Σt of the other activated control signals 23c through 23e. Therefore, the evaluation unit 26 can determine that an error condition exists.
[0059] In the third scenario, as shown in Figures 6a and 6b, the prohibited object 32 is positioned laterally to object 24. This error condition can also be determined based on the difference in duration Σt between control signals 23a to 23f. The durations Σt_23a and Σt_23b of control signals 23a and 23b are different from the durations Σt_23c, Σt_23d, and Σt_23e of other activated control signals 23c to 23e.
[0060] In the fourth scenario, as shown in Figures 7a and 7b, the prohibited object 32 is positioned diagonally in front of the permitted object 24.
[0061] This error condition can be determined based on several different evaluation approaches. Firstly, the durations of control signals 23b, 23c and control signals 23d, 23e are different.
[0062] Secondly, the evaluation unit 26 can determine a first ordered sequence 46 (here, 23c-23b-23e-23d) of the switching events of the control signal from the first state 34 to the second state 36, and a second ordered sequence 47 of the switching events of the control signal from the second state 36 to the first state 34. An error state can be determined if the first ordered sequence 46 does not match the second ordered sequence 47.
[0063] Thirdly, the evaluation unit 26 can determine the phase of each switching event for each sensor, and then determine the phase difference (also called phase shift Δt) between switching events of the same form for different control signals 23 (from the first state 34 to the second state 36, or from the second state 36 to the first state 34). The phase shift between control signals 23a to 23f from adjacent sensors can be analyzed to determine the phase shift between adjacent sensors. Thus, the evaluation unit can calculate the phase shift Δt between the rising edge signals 36a of directly adjacent sensors 22. Similarly, the evaluation unit can calculate the phase shift Δt between the falling edge signals 36b of directly adjacent sensors 22. Subsequently, an error condition is determined if a phase shift exists between the rising edge signals and / or falling edge signals.
[0064] In the fifth scenario, as shown in Figures 8a and 8b, the error condition can be determined based on the control signals 23a to 23f, the duration of the first ordered sequence 46 and the second ordered sequence 47, and a comparison of the phase difference. Any combination of these approaches can also be used to determine the presence or absence of an error condition.
[0065] In the sixth scenario, as shown in Figures 9a and 9b, the prohibited object 32 is positioned laterally to the permitted object 24 that is to be loaded. The prohibited object 32 and the permitted object 24 are positioned diagonally with respect to the transport direction T.
[0066] The evaluation unit 26 can determine this error state based on the approach described above. Furthermore, the evaluation unit 26 can determine an interpolated first timeline 48 defined by the transition event from the first state 34 to the second state 36. In other words, the point in time at which the transition event from the first state 34 to the second state 36 occurs is used to determine the interpolated first timeline 48 of the transition event of the control signal 23 with respect to time t. For example, linear regression can be used in this regard. Furthermore, the evaluation unit 26 can determine an interpolated second timeline 50 for the time of the transition event from the second state 36 to the first state 34 for each control signal 23a to 23e. Because the interpolated first timeline 48 and the second timeline 50 are not parallel to each other, the evaluation unit 26 can determine that an error state exists.
[0067] The interpolated timelines 48 and 50 may be advantageous when sensor 22 is not functioning and the evaluation unit does not receive the respective control signals.
[0068] In one embodiment, the pre-set order may be determined differently (non-linearly) with respect to stacks that do not have straight edges. Thus, the evaluation unit 26 can retrieve information about the shape of the acceptable object 24 being transported, which is connected to the memory 25.
[0069] Furthermore, the evaluation unit 26 can be supplied with information regarding predetermined thresholds in light of the determined differences. Such information can be stored, for example, in a memory 25 connected to the evaluation unit 26. The memory 25 includes a program that causes the evaluation unit 26 to determine an error state indicating the presence of prohibited access based on the arrival time t1 and / or departure time t2 to each control region Z. An error state can be determined to exist only if the difference in the inspected characteristics is greater than each predetermined threshold. In addition, the shape of the mounted object 24 can be supplied to the evaluation unit 26, and the determination of the error state can include such information.
[0070] Figure 10 is a schematic diagram of a method 60 for preventing unauthorized access while an object is being transported through a transformer. In the first step 62, the presence of objects 24, 32 within the control region Z of a plurality of sensors 22 is detected. Each sensor 22 has a detection range that covers an individual control region Z.
[0071] In the second step 64, the control signal 23 of the sensor 22 is supplied to the evaluation unit 26. In this regard, the control signal 23 changes between a first state 34 and a second state 36 when the leading edge E1 and trailing edge E2 of objects 24 and 32 within their respective control regions Z are detected. The control signal 23 is supplied to the evaluation unit 26 when a change in the sensor state is detected. The first and second times t1 and t2, also called the detection times t1 and t2 of the rising and falling edges of the rising and falling edges of the rise and falling edges of each sensor 22, are determined and analyzed.
[0072] In the third step 66, the control signal 23 is analyzed according to at least one criterion. The selected criterion is: a) Duration Σt of each sensor signal, b) Phase shift Δt between adjacent sensor signals, c) The ordered order of the multiple control signals 23, d) Interpolated timelines of the first and second transition events 48, 50, This is the difference in [location].
[0073] Preferably, all criteria are analyzed to determine the error condition.
Claims
1. A safety system (10) for a sheet substrate conversion machine (1) for the manufacture of paperboard and corrugated cardboard boxes, A detection unit comprising a plurality of sensors (22) arranged side by side, each of the sensors having a separate control region (Z), the detection unit being configured to detect the arrival time (t1) of an object (24, 23) being transported through the control region (Z) to each of the control regions (Z) and the departure time from each of the control regions, the arrival time and departure time of the object being determined from a control signal (23) from each of the sensors (22), the control signal from each of the sensors including a rising edge signal (36a) and a falling edge signal (36b), and each of the sensors having a vertical detection direction, An evaluation unit (26) is configured to receive the control signal (23) from each of the sensors of the detection unit, determine the arrival time (t1) from the rising edge signal and the departure time (t2) from the falling edge signal, and to supply an error signal (27) when an error state is determined. The evaluation unit includes a memory (25) containing a program that causes the evaluation unit to determine an error state indicating the presence of a prohibited object (32) based on the arrival time (t1) and / or departure time (t2) in each of the control region (Z), The system comprises an optical barrier system (13) including an optical barrier (14) and a muting device (20), The muting device includes an upstream muting detector (20a) and a downstream muting detector (20b) located on the opposite side of the light barrier (14). The safety system includes a control unit (28) configured to activate the muting device (20) to mute the light barrier (14) when a transported permissible object (24) is detected by the upstream muting detector (20a), and to activate the light barrier (14) when the permissible object (24) is detected by the downstream muting detector (20b), wherein the sensors (22a to 22f) of the detection unit (20) are configured to be activated when the upstream muting detector (20a) generates a muting signal (21) and the light barrier is muted, and the control unit (28) is configured to receive the error signal (27) from the evaluation unit (26) and generate a stop signal (29) when an error condition is detected.
2. The security system according to claim 1, wherein the sensors are positioned in a line at an equal distance (d1) from each other.
3. The security system according to claim 1, wherein the sensor (22) includes a photoelectric cell, a laser scanner, or a capacitive sensor.
4. The safety system according to claim 1, wherein the evaluation unit (26) is further configured to calculate the duration (Σt) between the rising and falling signals from each of the sensors, and the evaluation unit is configured to determine an error state if the durations for each of the sensors are different.
5. The safety system according to claim 1, wherein the evaluation unit is further configured to calculate a phase shift (Δt) between the rising edge signals (36a) of directly adjacent sensors (22), and the error state is determined when a phase shift is present.
6. The safety system according to claim 5, wherein the evaluation unit is configured to determine a first ordered order of switching events from a first state to a second state of the received control signal (23) and a second ordered order of switching events from a second state to a first state of the received control signal (23), and the error state is determined based on the difference between the first ordered order and the second ordered order.
7. The safety system according to claim 6, wherein the evaluation unit (26) is configured to determine an interpolated first timeline (48) defined by a switching event from a first state to a second state of the received control signal (23), and to determine an interpolated second timeline (50) defined by a switching event from a second state to a first state of the received control signal (23), and the error state is determined based on the non-parallel first and second timelines (48, 50).
8. The security system (10) according to claim 1, wherein the control unit (28) is configured to generate a stop signal (29) in order to deactivate the workstations (8, 9) of the converter (1) or deactivate the entire converter (1) when it receives an error signal (27) from the evaluation unit.
9. A sheet substrate conversion machine for the manufacture of cardboard and corrugated cardboard boxes, comprising the safety system according to any one of claims 1 to 8, wherein the sensor (22) is positioned horizontally on the travel path (P) of the conversion machine and above an access opening (12) of a restricted access area (A) of the conversion machine.
10. A method for protecting a restricted access area (A) of a sheet substrate conversion machine (1) for the manufacture of paperboard and corrugated cardboard boxes, A step of detecting the arrival time (t1) and departure time (t2) of an object (24, 32) within a control region (Z) of a plurality of sensors (22), wherein the sensors (22) have a vertical detection direction, The step of receiving a control signal (23) from each of the sensors (22) to the evaluation unit (26), wherein the control signal defines the arrival time (t1) from the rising edge signal (34) and the departure time (t2) from the falling edge signal (36), A step of determining the presence of a prohibited object (32) based on the arrival time (t1) and departure time (t2) of each of the control signals (23), Before detecting the arrival and departure times of objects (24, 32), The process involves receiving information from an upstream muting detector (20a) and generating a muting signal that turns off the light barrier (14) when an object to be transported (24) is detected, The steps include: activating the plurality of sensors (22a to 22f) when the light barrier (14) is turned off; Methods that include...
11. The presence of the prohibited object (32) is, The difference in duration (Σt) for each of the control signals (23) from each of the sensors (22) from the first state to the second state (36), and / or Phase shift (Δt) between subsequent switching times of different individual control signals (23) from different sensors (22), and / or The difference between the first ordered sequence of switching events of the control signal (23) from the first state to the second state and the second ordered sequence of switching events of the control signal (23) from the second state to the first state, and / or Non-parallel interpolated first and second timelines (48, 50), wherein the interpolated first timeline (48) is defined by a switching event of the control signal (23) from a first state to a second state, and the interpolated second timeline (50) is defined by a switching event of the control signal (23) from a second state to a first state, the first and second timelines (48, 50), The method according to claim 10, determined by the evaluation unit (26) based on at least one of the steps.