US20040145464A1 - Safety device - Google Patents

Safety device Download PDF

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Publication number
US20040145464A1
US20040145464A1 US10475670 US47567004A US2004145464A1 US 20040145464 A1 US20040145464 A1 US 20040145464A1 US 10475670 US10475670 US 10475670 US 47567004 A US47567004 A US 47567004A US 2004145464 A1 US2004145464 A1 US 2004145464A1
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US
Grant status
Application
Patent type
Prior art keywords
safety
device
transmitters
characterised
pulse train
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US10475670
Inventor
Mats Linger
Torgny Olsson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Jokab Safety AB
Original Assignee
Jokab Safety AB
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date

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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/02Testing of electric apparatus, lines or components, for short-circuits, discontinuities, leakage of current, or incorrect line connection
    • G01R31/024Arrangements for indicating continuity or short-circuits in electric apparatus or lines, leakage or ground faults
    • G01R31/026Testing continuity
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/28Testing of electronic circuits, e.g. by signal tracer
    • G01R31/282Testing of electronic circuits specially adapted for particular applications not provided for elsewhere
    • G01R31/2829Testing of circuits in sensor or actuator systems

Abstract

The present invention relates to a safety device comprising a safety module (11), a data bus (12) and on a or several transmitters (15, 16, 17, 18, 19, 20). The safety module transmits a pulse train (one dynamic signal) over said bus (12) constituting a loop, whereby the pulse train is connected to each of said transmitters, wherein the pulse is phase inverted.

Description

    BACKGROUND OF THE INVENTION
  • Electronic monitoring systems of a similar type have previously been described. In U.S. Pat. No. 4,543,566 an electronic monitoring system comprising a contact less movement detector is described. The movement detector comprises an oscillator with a sensing coil, having an output connected to an input of a first gate with another input connected to a square wave generator, the pulses of which appear at the output of the first gate, with or without phase inversion depending on the output voltage of the movement detector. These pulses are fed, via an amplifier, to an input of a second gate, the input of which directly receives the output pulses from the square wave generator, but having a delay. If a fault occurs, disturbing the pulse transmission to any of the inputs to this second gate, its output becomes a pulsating voltage. Further, an integrator being parallel coupled with the second gate to the amplifier output can introduce such a fault.[0001]
  • BRIEF DESCRIPTION OF THE DRAWINGS
  • FIG. 1 shows a safety loop according to the invention, [0002]
  • FIG. 2 shows a first arrangement in the safety loop according to the invention, [0003]
  • FIG. 3 shows a second arrangement in the safety loop according to the invention, [0004]
  • FIG. 4 shows a third arrangement in the safety loop according to the invention, [0005]
  • FIG. 5 shows a detailed schedule of the loop.[0006]
  • DETAILED DESCRIPTION OF EMBODIMENTS
  • FIG. 1 shows a safety loop [0007] 10 according to the invention, which is described in the following.
  • A safety module [0008] 11 is the main part of the system according to the invention, sending out a pulse train (a dynamic signal) over a bus 12 constituting the loop. The pulse train leading to each transmitter wherein the pulse is phase inverted. Different modules can be connected to the loop. A sensor 13, an inverse switch 14, terminal strips/sensor mats/bumpers 15, light transmitters/-receivers 16/17/18, light curtains 19 and an emergency stop 20 are examples of these modules. Obviously, other modules can occur. The safety module permits installation of several safety means to the same safety modules simultaneously as a safety of category 4 according to EN 954-1 is obtained. Moreover, the safety module can also be provided with an automatically or manually monitored resewing, double safety outputs, information output for restoration indication and output for status information to a PLC (Programmable Logic Controller).
  • From a safety point of view, faults, e.g. a short circuit or interruption, may not lead to a dangerous situation. According to the present solution, interruption and short circuit at each sensor leads to a stop signal directly to dangerous machines or processes, since the signal must be turned at each transmitter. The safety module [0009] 11 also controls that the signal is time shifted, i.e. the signal being sent from the safety module must also be time shifted in relation to the signal coming back. This implies that the safety module may receive pulses being inverted and not inverted, respectively, with respect to the signal being sent, without the risk for short circuit could imply a dangerous situation.
  • The time shift may also be varied with the number of transmitters mounted. Thereby additional control of the number of transmitters is correct is obtained. [0010]
  • The pulse train being sent is compared to the pulse train coming back. The safety module achieves the controls amongst others the time shift and the frequency. If the signal is correct the safety outputs are kept dosed. When an error signal or a stop signal from one or several transmitters is received, the safety outputs are opened. [0011]
  • The transmitters being coupled to the dynamic safety loop can be electronic and mechanical having an electronic adjustment. An emergency shutdown has one or two switching contacts being compulsively opened when the emergency shutdown button [0012] 20 is pushed. For adjusting the emergency shutdown to the dynamic safety loop, an electronic unit is mounted comprising the pulse inversion function. As long as the conductors are closed, the electronic unit pulse inverts the incoming signal and sends the pulse inverted signal further to the next transmitter or back to the safety module. In the same way, all types of mechanical transmitters can be coupled to the loop. For a high security level, its switching contacts need to be force controlled, i.e. they are pushed apart by the actuating force. Terminal strips, sensor mats and bumpers can be connected to the dynamic safety loop. It is also possible to connect the terminal strips, sensor mats and bumpers working with closing function for stop signal and the ones working with switching function for stop signal, since both switch and short circuit lead to that the safety module gives a stop signal. For facilitating the possibilities for interconnecting, there are junction boxes 21, being shown in FIG. 2, with an output for a great number of transmitters and provided with pulse inverters. This junction box also contains a pulse inverter ensuring that the output signal is always phase inverted compared to the input signal. The junction box is coupled to a safety module via the bus, which contains the information of each sensor. This facilitates the delivery of the machines prepared for rapid coupling with the safety sensors. The sensors may also be coupled to the safety module via the regular contacts.
  • With reference to FIG. 5, the function of the loop is described closer. The safety module has a transmitter generating a square wave internally, being sent to the first sensor via the connection T[0013] 1. This internal square wave is internally connected to the Block: the detection of the time shift and short circuit control of T1 and R1, and to the Block: the signal control, comparator and driving,
  • The signal received in R[0014] 1, coming from the last sensor in the serial chain, then will pass a voltage level detector (block) for comparing phase and delay time to the internal signal of the transmitter. Every sensor, etc, gives a signal being delayed (and phase inverted) in relation to its input signal. If a short circuit occurs between T1 and R1 (and/or between the conductors which is connected to them) the detecting block will discover that (due to no delay between T1 and R1) and not allow the output relays of the safety module to pull and risk a dangerous position. This is particularly relevant when the connection is according to alternative 1 since T1 and R1 is in the same phase (but delayed). Depending on the original installation of the system, alt. 1 or alt. 2 (see below and in the table of the block diagram) and if everything works normally, the signal will be allowed to go further to the Signal control block, comparator and driving, which controls if the “shape” of the signal (frequency, dissymmetry and total delay) is approved (with a certain tolerance). If approved, it will go further to the next block for enabling a start of the output relays.
  • Alt. [0015] 1; Even number of sensors (phase inversions) in series between T1 and R1. T1 and R1 are in the same phase (but delayed) if the sensors give transmission (e.g. locked doors, etc.). Condition: S1 must be connected to A1 (+supply voltage).
  • Alt. [0016] 2: Odd number of sensors (phase inversions) in series between T1 and R1. T1 and R1 are phase inverted (and delayed) if the sensors give transmission (e.g. locked doors, etc). Condition: S1 should not be connected.
  • The great advantage with this system is that several different sensors/transmitters can be coupled in the same loop at the same time as the loop keeps a high security level. The dynamic safety loop is simple; it connected to one transmitter and back out of the transmitter. Since it is dynamic, short circuit always results in immediate stop signal from the safety module. For e.g. two-channel solutions short circuits are only monitored at every stop occurrence, which implies that short-circuits can be accumulated, which are not discovered gradually. Finally, the protection may not work at all. This does not occur with dynamic monitoring since short circuit in the safety loop immediately results in a stop. Moreover, a contact-free switch [0017] 13 or contact breaker can be connected to the loop, which is shown in detail in FIG. 3. The switch can be used for e.g. block switches, interlock disc covers, etc. The switch comprises two parts 131 and 132. The first part 131 receives a coded signal from the safety module, which is sent to the second part 132, which modifies the signal and sends it back to the first part. The switch can be connected in series with light barriers and emergency shutdowns and give the same high confident coefficient in the safety module.
  • FIG. 4 shows the connection to the loop of the light transmitters [0018] 161 a, 161 b and 161 b and the optic receivers 171 a, 171 b and 171 c. The signal is sent to the transmitters from the safety module 11 on one side of the loop and received from the receivers.
  • The invention is not limited to the shown embodiments but can be varied in a number of ways without departing from the scope of the appended claims and the arrangement and the method can be implemented in various ways depending on application, functional units, needs and requirements, etc. [0019]

Claims (8)

  1. 1. A safety device comprising a safety module (11), a data bus (12) and a number of transmitters (15, 16, 17, 18, 19, 20),
    characterised in
    that said safety module is arranged to. transmit a pulse train (a dynamic signal) over said bus (12) forming a loop, whereby the pulse train is connected to each of said sensors, in which the pulse is phase inverted and that the safety module (11) controls that said pulse from the detectors is time delayed.
  2. 2. Device as claimed in claim 1,
    characterised in
    that said transmitters comprise one or several of a sensor (13), an inversed switch (14), terminal strips, sensor mats, bumpers (15), light transmitters/-receivers (16/17/18), light curtains (19) and emergency shutdown button (20).
  3. 3. Device as claimed in any of the claims 1 or 2,
    characterised in
    that the device may further be provided with one or several of automatically or manually monitored resetting, double safety outputs, information output for restoration indication, and output for status information to a PLC (Programmable Logic Controller).
  4. 4. Device as claimed in claim 1,
    characterised in
    that the signal sent out from the safety module is time delayed in relation to the signal coming back.
  5. 5. Device as claimed in claim 4,
    characterised in
    that the time delay varies with the number of transmitters coupled, whereby further control of that the correct number of transmitters is obtained.
  6. 6. Device as claimed in claim 1,
    characterised in
    that said transmitted pulse train is compared to the received pulse train, whereby a control of the time delay and the frequency is made by the safety module.
  7. 7. Device as claimed in claim 6,
    characterised in
    that if the signal is correct the safety outputs are kept closed, and the safety outputs are opened when a error or stop signal is received from one or several of the transmitters.
  8. 8. A method at a safety device comprising a safety module (11), a data bus (12) and a number of sensors (15, 16, 17, 18, 19, 20),
    characterised In
    that said safety module sends a pulse train (a dynamic signal) over said bus (12) constituting a loop, whereby the pulse train is connected to each of said transmitters, in which the pulse phase is inverted, and that the transmitted pulse train is compared to a received pulse train, whereby the control of a time delay and the frequency is done by the safety module.
US10475670 2001-04-23 2002-04-23 Safety device Abandoned US20040145464A1 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
SE0101450-5 2001-04-23
SE0101450 2001-04-23
PCT/SE2002/000796 WO2002086838A1 (en) 2001-04-23 2002-04-23 Safety device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US11449836 US7429929B2 (en) 2001-04-23 2006-06-09 Safety device

Publications (1)

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US20040145464A1 true true US20040145464A1 (en) 2004-07-29

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US10475670 Abandoned US20040145464A1 (en) 2001-04-23 2002-04-23 Safety device
US11449836 Active US7429929B2 (en) 2001-04-23 2006-06-09 Safety device

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US11449836 Active US7429929B2 (en) 2001-04-23 2006-06-09 Safety device

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US (2) US20040145464A1 (en)
EP (1) EP1393280B1 (en)
DE (2) DE60201989T2 (en)
WO (1) WO2002086838A1 (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102004017951A1 (en) * 2004-04-14 2005-11-10 Fraba Vitector Gmbh Diagnosing device for optoelectronic safety connection block, has processing unit producing diagnosing signal indicating condition of block in response to dynamic signals and supply current and voltage of optical transmitter and receiver
DE102011086060A1 (en) * 2011-11-10 2013-05-16 Sb Limotive Company Ltd. Process for safety-related shutdown of an electrical network and security device
EP2720098A1 (en) 2012-10-10 2014-04-16 Sick Ag Safety system for a plant comprising a test signal path with return path
EP2720051B1 (en) 2012-10-10 2015-01-21 Sick Ag Safety system
EP2720094B1 (en) 2012-10-10 2015-05-20 Sick Ag Safety system
EP2720414B1 (en) 2012-10-10 2014-12-10 Sick Ag Bus system
US9148796B2 (en) 2012-12-13 2015-09-29 Ninve Jr. Inc. Resilient antenna disturbance detector

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3611361A (en) * 1969-11-03 1971-10-05 American Standard Inc Alarm-monitoring system
US3634824A (en) * 1969-11-05 1972-01-11 Afa Protective Systems Inc Signaling system utilizing frequency and frequency duration for signaling and control functions
US4356475A (en) * 1980-09-12 1982-10-26 Siemens Aktiengesellschaft System containing a predetermined number of monitoring devices and at least one central station
US4543566A (en) * 1981-09-22 1985-09-24 Robert Buck Electronic monitoring system with malfunction indicator
US4906979A (en) * 1987-03-18 1990-03-06 Sharp Kabushiki Kaisha Monitoring system with microprocessor and watchdog circuit monitoring each other

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB8912945D0 (en) * 1989-06-06 1989-07-26 De La Rue Co Plc Electronic sensing system
DE19506385C2 (en) * 1995-02-23 2002-03-07 Peter John Goddard Wireless hazard signaling system and reporting procedures

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3611361A (en) * 1969-11-03 1971-10-05 American Standard Inc Alarm-monitoring system
US3634824A (en) * 1969-11-05 1972-01-11 Afa Protective Systems Inc Signaling system utilizing frequency and frequency duration for signaling and control functions
US4356475A (en) * 1980-09-12 1982-10-26 Siemens Aktiengesellschaft System containing a predetermined number of monitoring devices and at least one central station
US4543566A (en) * 1981-09-22 1985-09-24 Robert Buck Electronic monitoring system with malfunction indicator
US4906979A (en) * 1987-03-18 1990-03-06 Sharp Kabushiki Kaisha Monitoring system with microprocessor and watchdog circuit monitoring each other

Also Published As

Publication number Publication date Type
WO2002086838A1 (en) 2002-10-31 application
EP1393280B1 (en) 2004-11-17 grant
US7429929B2 (en) 2008-09-30 grant
EP1393280A1 (en) 2004-03-03 application
US20060279417A1 (en) 2006-12-14 application
DE60201989D1 (en) 2004-12-23 grant
DE60201989T2 (en) 2006-03-02 grant

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Date Code Title Description
AS Assignment

Owner name: JOKAB SAFETY AB, SWEDEN

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:LINGER, MATS;OLSSON, TORGNY;REEL/FRAME:014439/0394

Effective date: 20031105