Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B61—RAILWAYS
  • B61L—GUIDING RAILWAY TRAFFIC; ENSURING THE SAFETY OF RAILWAY TRAFFIC
  • B61L5/00—Local operating mechanisms for points or track-mounted scotch-blocks; Visible or audible signals; Local operating mechanisms for visible or audible signals
  • B61L5/12—Visible signals
  • B61L5/18—Light signals; Mechanisms associated therewith, e.g. blinders
  • B61L5/1809—Daylight signals
  • B61L5/1881—Wiring diagrams for power supply, control or testing
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
  • H05B45/10—Controlling the intensity of the light
  • H05B45/12—Controlling the intensity of the light using optical feedback
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
  • H05B45/50—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B61—RAILWAYS
  • B61L—GUIDING RAILWAY TRAFFIC; ENSURING THE SAFETY OF RAILWAY TRAFFIC
  • B61L2207/00—Features of light signals
  • B61L2207/02—Features of light signals using light-emitting diodes [LEDs]

Definitions

• the present invention relates to a circuit arrangement according to the preamble of patent claim 1 or 2.
• railway light signal systems require an extraordinarily high level of operational safety.
• the systems which are generally exposed to high environmental pollution, should function without problems over a long period of time and report any defects that may arise to a control body immediately.
• CH 675 922 a railway light signal system is known, which is provided with two light bulbs.
• This circuit arrangement which consists of only a few, non-critical components, has a simple structure and is therefore largely immune to external influences (in particular temperature fluctuations).
• a disadvantage of these known railway light signal systems is that the service life of the incandescent lamps used is relatively short. The maintenance required for these systems is therefore still quite high.
• the light intensity of the lamps is difficult to adapt to the lighting conditions of the plant location, since incandescent lamps have a non-linear behavior. For the sake of simplicity, the lamps are therefore always operated with one or two power levels. Furthermore, the overall function of known railway light signal systems is significantly influenced by the failure of a single lamp.
• the present invention is therefore based on the object of creating a circuit arrangement which has increased operational reliability compared to known systems and which is compatible with the unit to be replaced.
• the circuit arrangement according to the invention allows the use of light-emitting diodes, such as those e.g. in
• FIG. 1 shows a circuit arrangement according to the invention.
• FIG. 2 shows a circuit arrangement according to the invention with optimized light intensity adjustment
• Fig. 3 shows a circuit arrangement according to the invention with a decision logic
• FIG. 4 shows a circuit arrangement according to the invention realized without a transformer
• FIG. 1 shows a circuit arrangement according to the invention which has a transformer XFMR connected on the primary side to an AC voltage input INP and on the secondary side via a rectifier circuit GS to n lighting units BE1Bn.
• the input INP of the circuit arrangement is connected via a line to the supply circuit of a main station or a railway signal box.
• An AC voltage is emitted by this supply circuit, the amplitude of which is switched between two values for day and night operation.
• the change in amplitude is adapted to the circuit arrangements provided with incandescent lamps, as are known from the aforementioned patent specification CH 675 922.
• the rectifier circuit GS shown in FIG. 1 which is known to the person skilled in the art, consists of a bridge rectifier formed from four diodes D1, D2, D3 and D4 as well as a charging and a filter capacitor C1 and C2.
• a protective element Rs e.g. a resistor or varistor, etc.
• the connections of the primary winding of the transformer XFMR or the connections of the input INP are also connected to one another by a resistor Rg (base load resistor).
• Each lighting unit BE1, .... BEn has a current source ICV connected to the rectifier circuit GS, which is connected in series with a winding of a relay RLS11, with a series resistor Rv and a group CL1 of light-emitting diodes LD1, .... LDx.
• a Zener diode (see FIG. 3, diode ZD) connected in parallel to the relay winding can also be used, by means of which the voltage across the relay RLS11 is limited.
• the relay RLS11 has a switch contact K11, through which a further relay RLS2 can be connected to the connections of the primary winding of the transformer XFMR. It is of course assumed that the contacts K12, ....
• the circuit arrangement shown in FIG. 1 functions as follows:
• An AC voltage is supplied to the input INP of the circuit arrangement by the main station, which is transformed in the transformer XFMR and output to the rectifier circuit GS.
• the current source ICV connected to the rectifier circuit GS leads a current through the winding of the relay RLS11 and the diodes LD1 LDx.
• the relays RLS11, ..., RLS1n provided on the lighting units BE11, ..., BE1n therefore close the contacts K11, ..., K1n, after which a current is passed through the winding of the relay RLS2. This causes the contact K21 to close and the contact K22 to open. A current is therefore passed through the resistor Rr via the first contact K21.
• a current is therefore also conducted through the resistor Rr in the fault-free operating state of the circuit arrangement.
• This operating current which is reached with the assistance of the resistors Rg and Rr, corresponds to the operating current of circuit arrangements which are equipped with incandescent lamps.
• the second contact K22 is opened, thereby eliminating the short circuit of the line FML. In the main station it can therefore also be determined by means of the line FML that the circuit arrangement has changed into the trouble-free operating state. If a serious problem occurs, e.g.
• the second relay RLS2 is preferably provided with positively driven contacts due to the requirements.
• Such safety relays are described in Hans Sauer, Relay Lexicon, Wegig Verlag, Heidelberg 1985, 2nd edition, pages 199-201.
• the contacts K21 and K22 therefore exist each from two serially connected contacts, one of which can always be removed, even if the second contact is welded. In practice, it can be assumed that one and the same fault, such as contact welding or spring breakage, only occurs on one contact. Errors that occur within the safety relay are detected by an evaluation circuit (not shown in FIGS. 1 and 2), which also prevents a next switch-on process when an error is evaluated.
• the circuit arrangement shown in FIG. 2 is supplemented by a module TN, which is used for day / night switching of the light intensity emitted by the diodes LD1 LDx. Furthermore, a measuring and amplifier circuit is provided which consists of a light-sensitive element PSD (photoresistor, element, diode or transistor, as described in Klaus Beuth, Bauemia, Vogel Verlag, Würzburg 1991, 13th edition, chapter 12) and at least one amplifier OP2, the output of which is connected to a control input of the current source ICV.
• PSD photoresistor, element, diode or transistor
• the module TN consists of a differential amplifier OP1, the first input of which has a voltage divider formed by two resistors R1, R2, the second input of which has the output of a constant voltage source UC and the output of which has the control input of a switching unit SW, e.g. a switching transistor is connected, by means of which a shunt resistor Rn can be connected in parallel with the group CL1 of light-emitting diodes LD1,... LDx provided with the series resistor Rv.
• the voltage source UC connected to the input of the lighting unit BE1 is connected in parallel to the resistors R1 and R2 connected in series.
• the TN module works as follows:
• the main station delivers the maximum voltage provided to the INP input of the circuit arrangement.
• a sufficiently high difference in luminance between the maximum expected ambient brightness and the optical signals emitted by the diode groups CL1,... CLn is guaranteed.
• the voltage emitted by the main station is, however, calculated for the operation of incandescent lamps.
• the diode groups CL1 CLn provided in the circuit arrangement according to the invention and that from the transformer XFMR and the
• Rectifier circuit GS existing power supply part must therefore be designed in such a way that at least approximately the same luminance is present as when operating with incandescent lamps.
• the voltage applied by the main station to the INP input is reduced in order to adapt the luminance of the optical signals to the changed ambient conditions and to achieve a reduction in the energy output.
• the lowering of the voltage emitted by the main station is in turn adapted to the circuit arrangements provided with incandescent lamps, to which the circuit arrangement according to the invention should be compatible.
• the shunt resistor Rn is switched on, so that only a fraction of the original current is conducted through the series-connected diodes LD1, ..., LDx, which is sufficient to achieve a luminance comparable to that of incandescent lamps.
• the shunt resistance Rn it must be taken into account that light-emitting diodes and incandescent lamps have different characteristics. In the case of light-emitting diodes, in contrast to incandescent lamps, the light intensity emitted changes proportionally to the current supplied.
• the differential amplifier OP1 compares the (variable) voltage taken from the voltage divider with the constant voltage delivered by the voltage source UC.
• the voltage divider formed by the resistors R1 and R2 is designed in such a way that no voltage difference arises at the input of the differential amplifier OP1 during daytime operation. It is only by lowering the input voltage when switching to night mode that a voltage difference arises, by means of which a control signal arises at the output of the differential amplifier, which leads to the activation of the switching unit SWb.
• the switching unit SWb e.g. a switching transistor, then switches the shunt resistor Rn in parallel with the diode group CL1 provided with the series resistor Rv. When switching to day mode, the switching unit SWb is reset.
• a switch SWa connected to the current source ICV and actuated by the differential amplifier OP1 can also be provided, through which a lower constant current is applied for daytime operation ⁇ can be put as for night operation.
• the light-sensitive element PSD shown in FIG. 2 and the downstream amplifier OP2 are provided to better adapt the light intensity emitted by the diodes to the ambient brightness. These units supply an electrical control signal to the control input of the current source ICV, which depends on the luminance of the surroundings measured by the element PSD (preferably in the direction of view of the light signal). If the ambient brightness drops, the current carried by the diode groups CL1, .... CLn is therefore reduced.
• the characteristic curve of the amplifier OP2 is selected in such a way that the desired difference in luminance is always present. It is envisaged that the holding current for the relays RLS11-RLS1n is never undercut when the current is reduced.
• a symbol to be signaled is formed by preferably at least two diode groups CL1, CL2.
• the light-emitting diodes LD of these groups CL1, CL2 are arranged in such a way that if a group CL1 or CL2 fails, which is caused, for example, by the interruption of a diode LD, the symbol still remains recognizable.
• the symbol is displayed by both groups CL1, CL2, so that if one group CL1 or CL2 fails, there is only a drop in luminance.
• the light signal system therefore remains in operation until the error reported to the main station is eliminated.
• the resistors Rg and Rr base and residual load resistance
• these load resistors can also be arranged on the secondary side, taking into account the transformation ratio of the transformer XFMR.
• the relay RLS2 can also be provided on the secondary side of the transformer XFMR, before or after the rectifier circuit GS.
• Some of the measuring and switching processes could also be controlled by a microprocessor.
• Fig. 3 the state of the lighting units BE1, ..., BEn or the state (attracted / released) of the relays RLS11, .... RLS1n is reported to a logic circuit LC, which is a function of the state of the lighting units BE1,. ... BEn the relays RLS2 and RLS3 actuated.
• the contacts K21 and / or K22 are actuated by the relay RLS2.
• Relay RLS3 actuates a contact K31, through which a resistor Ra or Rb can be short-circuited, which connects lines a and b or a and c, which are connected to a control station.
• the position of the contact K31 can therefore be easily determined in the main station or in the signal box.
• the logic circuit LC is constructed such that the relay RLS3 is actuated in the event of a number (1 to m) of error messages and the relay RLS2 is actuated in the event of a number (m + 1 to n) of error messages.
• the construction of such a circuit in analog or digital technology is known to the person skilled in the art.
• the relay RLS3 When the relay RLS3 is actuated, an error is reported via lines a, b and c, which should be handled with less urgency.
• the single fault case corresponds to the failure of the main turning ice of an incandescent lamp.
• the multiple error case corresponds to the failure of the reserve turning ice.
• the logic circuit LC can of course also be connected directly to a control station.
• FIG. 4 shows lighting units WBE1 WBEn which are provided with a module TN for day / night switching already described above and are supplied with alternating current.
• Rectifier diodes DG1, DG2 and a rectifier circuit are provided for the power supply of the module TN.
• the LEDs LD1 LDx are in series with an adjustable
• Resistor or a transistor TR which is controlled by the module TN.
• the light-emitting diodes LD1,..., LDx can also be connected directly to AC voltage.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Optical Communication System (AREA)
• Train Traffic Observation, Control, And Security (AREA)
• Semiconductor Lasers (AREA)
• Mechanical Light Control Or Optical Switches (AREA)
• Circuit Arrangement For Electric Light Sources In General (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=4253660

Family Applications (1)

Country Status (6)

Cited By (1)

Families Citing this family (24)

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• 1994
  • 1994-10-17 DE DE59406833T patent/DE59406833D1/de not_active Expired - Fee Related
  • 1994-10-17 EP EP94929449A patent/EP0678078B1/fr not_active Expired - Lifetime
  • 1994-10-17 WO PCT/CH1994/000205 patent/WO1995012512A1/fr active IP Right Grant
  • 1994-10-17 DK DK94929449T patent/DK0678078T3/da active
  • 1994-10-17 AT AT94929449T patent/ATE170472T1/de not_active IP Right Cessation
• 1995
  • 1995-05-04 NO NO951743A patent/NO951743L/no not_active Application Discontinuation

Non-Patent Citations (1)

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