EP0678078B1 - Switching circuit for railway light signal installation - Google Patents

Abstract

The circuit for emitting optical signals adapted to the ambient light consists of a transformer (XFMR) connected on the primary side to an a.c. input (INP) and on the secondary side via a rectifier circuit (GS) to the input of at least one lighting unit (BE1) fitted with electroluminescent diodes (LD1, ..., LDx). The circuit is compatible with circuits using incandescent lamps, but has a much lower error probability.

Description

The present invention relates to a circuit arrangement according to the preamble of the claim 1.

For well-known reasons, railway light signaling systems are extremely reliable required. The plants, which are generally exposed to high environmental pollution, should function without problems over a long period of time and any defects that may occur immediately report to a control body. One is from the Swiss patent specification CH 675 922 Railway light signal system known, which is provided with two light bulbs. This from just a few, Circuitry existing for non-critical components is simple in construction and therefore largely immune to external influences (especially temperature fluctuations). A disadvantage of This well-known railroad light signal system is that the life of the light bulbs used is relatively short. The maintenance required for these systems is therefore still fair high. Furthermore, the light intensity of the lamps is difficult to match the lighting conditions at the plant location adjust because 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 Known railroad traffic signal systems essential due to the failure of a single lamp influenced.

However, replacing the incandescent lamp with a light body that does not have these disadvantages leads to further disadvantages. Controls are usually required for the improved light bodies, which is increased due to the larger number of components and under the given environmental influences May have error probability. Furthermore, these circuits are difficult to in adapt the existing infrastructure. For the modernization of the traffic signal systems would therefore have to extensive investments are made.

The present invention is therefore based on the object of providing a circuit arrangement which has increased operational reliability compared to known systems and which to unit to be replaced is compatible.

This object is achieved by those specified in the characterizing part of patent claim 1 Measures solved. Advantageous embodiments of the invention are specified in further claims.

The circuit arrangement according to the invention allows the use of light-emitting diodes, such as those e.g. in Klaus Beuth, Bauelemente, Vogel Verlag, Würzburg 1991, 13th edition, page 292-294 are. It is known from this that light-emitting diodes react almost without inertia and one to forward direct current give proportional light intensity. LEDs are also for different wavelength ranges (including infrared) available and have a good (but depending on the wavelength) Efficiency. It is also known that LEDs compared to incandescent lamps have a much higher life expectancy. The circuit arrangement according to the invention can be used instead of the circuit arrangement to be improved without changes in the existing infrastructure or in the course of operations.

Fig. 1

eine erfindungsgemässe Schaltungsanordnung

Fig. 2

eine erfindungsgemässe Schaltungsanordnung mit optimierter Lichtstärkeanpassung

Fig. 3

eine erfindungsgemässe Schaltungsanordnung mit einer Entscheidungslogik

The invention is explained in more detail below using a drawing, for example. It shows:

Fig. 1

a circuit arrangement according to the invention

Fig. 2

a circuit arrangement according to the invention with optimized light intensity adjustment

Fig. 3

a circuit arrangement according to the invention with a decision logic

1 shows a circuit arrangement according to the invention, which has a primary side with an AC voltage input INP and on the secondary side via a rectifier circuit GS with n lighting units BE1, ..., Bn connected transformer XFMR. The input INP of the circuit arrangement is installed via a line with the supply circuit of a main station or a railway signal box. An AC voltage is generated from this supply circuit given, the amplitude for day and night operation between two values is switched. The change in amplitude is the circuit arrangements provided with incandescent lamps adapted as they 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 or C2. Of course, instead of this circuit, others can do that Rectifier circuits (switching power supplies, etc.) known to those skilled in the art can be used. For protection the connections of the primary or secondary winding of the transformer are against overvoltages XFMR each connected to 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 each other by a resistor Rg (base load resistor).

Each lighting unit BE1, ..., BEn has one connected to the rectifier circuit GS Current source ICV1 on, in series with a winding of a relay RLS11, with a series resistor Rv and a group CL1 of LEDs LD1, ..., LDx is connected. For current limitation through the winding of the relay RLS11 can also be connected in the reverse direction parallel to the relay winding Zener diode (see Fig. 3, diode ZD) are used by the voltage across the relay RLS11 is limited. The relay RLS11 has a switch contact K11 through which another Relay RLS2 can be connected to the connections of the primary winding of the transformer XFMR. Provided it is natural that the ones controlled by the lighting units BE2, ..., BEn Contacts K12, ..., K1n, which are connected in series to contact K11, are closed. By the Relay RLS2 two different contacts K21 and K22 are actuated. Through the first contact K21, another resistor Rr (residual load resistor) can be connected to the connections of the input INP. Through the second contact K22, the two wires of a line FML, which to one Control station e.g. leads in the main station, interconnectable.

The circuit arrangement shown in FIG. 1 functions as follows:

An AC voltage is applied to the input INP of the circuit arrangement by the main station supplied, which is transformed in the transformer XFMR and delivered to the rectifier circuit GS becomes. A current is generated by the current source ICV1 connected to the rectifier circuit GS through the winding of the relay RLS11 and the diodes LD1, ..., LDx. By on the lighting units BE11, ..., BE1n provided relays RLS11, ..., RLS1n therefore become the contacts K11, ..., K1n closed, 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. over A current is therefore passed through the resistor Rr to the first contact K21. Besides the current through the primary winding of the transformer XFMR and through the resistor Rg in the trouble-free Operating state of the circuit arrangement therefore also a current through the resistor Rr guided. By the flow of the operating current composed of these three components the main station is informed that the light body has been activated. This operating current, the resistance Rg and Rr achieved with the assistance corresponds to the operating current of circuit arrangements that are equipped with incandescent lamps. Furthermore, the second contact K22 opened, which eliminates the short circuit of the line FML. In the main station can therefore also be determined by means of the line FML that the circuit arrangement has gone into the trouble-free operating state. If a serious disorder occurs, e.g. if an interruption occurs in one of the diodes LD1, ..., LDx, the current is omitted by winding the first relay RLS11, after which the contact K11 opens and the second relay RLS2 is reset. As a result, the FML line is short-circuited by the contact K22, with which an error message is transmitted to the main station. The error that has occurred becomes the main station further by the interruption of the current through the resistor caused by the contact K21 Rr displayed. Through the resistor Rg, which continues with the terminals of the input INP remains connected, a permanent base current continues to flow. The shutdown of a Part of the current flowing through the resistors Rr and Rg causes little or no transient Operations. Switching off the entire current flowing through the resistors Rg and Rr, which (together with the current through the primary winding) is approximately the simulated incandescent lamp current corresponds, however, could lead to undesired transient processes.

The second relay RLS2 is preferably with forced guidance due to the requirements Contacts. Such safety relays are in Hans Sauer, Relay Lexicon, Hüthig 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 disconnected, even if the second contact is welded. In practice, it can be assumed that a and the same error, such as Contact welding or spring breakage, only on one contact at a time occurs. Errors that occur within the safety relay are detected by a (in FIGS. 1 and 2 (not shown) evaluation circuit that also detects an error when evaluating next switch-on prevented.

Fig. 2 shows a lighting unit BEc, which is supplemented by a module TN, which for day / night switching the light intensity emitted by the diodes LD1, ..., LDx. Furthermore, a measurement and Amplifier circuit provided, which consists of a photosensitive element PSD (Photo resistor, element, diode or transistor, as described in Klaus Beuth, components, Vogel Verlag, Würzburg 1991, 13th edition, chapter 12) and at least one amplifier OP2, whose output is connected to a control input of the current source ICV1.

The module TN consists of a differential amplifier OP1 whose first input is connected to a through two resistors R1, R2 formed voltage divider, the second input with the output a constant voltage source UC and its output with the control input of a switching unit SWb, e.g. a switching transistor is connected through which a shunt resistor Rn in parallel can be connected to the group CL1 of light-emitting diodes LD1, ..., LDx provided with the series resistor Rv is. The voltage source UC connected to the input of the lighting unit BEc is connected in parallel to the series connected resistors R1 and R2.

The TN module works as follows:

During the day, the main station outputs the maximum voltage provided to the INP input the circuit arrangement. A sufficiently high difference in luminance between the maximum expected ambient brightness and that emitted by the diode groups CL1, ..., CLn optical signals guaranteed. However, the voltage delivered by the main station is calculated for the operation of incandescent lamps. The in the circuit arrangement according to the invention provided diode groups CL1, ..., CLn and that from the transformer XFMR and the Rectifier circuit GS existing power supply part must therefore be designed such that at least approximately the same luminance as when operating with incandescent lamps. For the At night, the voltage applied by the main station to the INP input is lowered to adapt the luminance of the optical signals to the changed environmental conditions and to achieve a reduction in the energy output. The lowering of those delivered by the main station Voltage is in turn adapted to the circuit arrangements provided with incandescent lamps, to which the circuit arrangement according to the invention is to be compatible. Since the in the Lighting unit BEc provided current source ICV1 the current despite the lowering of the Keeping the voltage constant (e.g. so that the RLS11 is not reset) is used for night operation the shunt resistor Rn switched on, so that the series connected diodes LD1, ..., LDx only a fraction of the original current is carried, which is sufficient to operate a light bulb to achieve comparable luminance. When calculating the shunt resistance Rn must be taken into account that light-emitting diodes and incandescent lamps have different characteristics exhibit. In the case of light-emitting diodes, the emitted light intensity changes proportionally in contrast to incandescent lamps to the supplied electricity.

The differential amplifier OP1 detects the (variable) voltage taken from the voltage divider compared with the constant voltage output by the voltage source UC. The through The resistors R1 and R2 formed voltage divider is designed so that during daytime operation there is no voltage difference at the input of the differential amplifier OP1. Only through that Lowering the input voltage when switching to night mode creates a voltage difference, through which a control signal arises at the output of the differential amplifier, which for Activation of the switching unit SWb leads. The switching unit SWb, e.g. a switching transistor, switches then the shunt resistor Rn parallel to the diode group provided with the series resistor Rv CL1. When switching to day mode, the switching unit SWb is reset.

Instead of the day / night switchover with switching on or off the shunt resistor shown in FIG. 2 Rn can also be connected to the current source ICV1 and from the differential amplifier OP1 actuated switch SWa can be provided, through which a lower constant current is set for day operation can be used as for night operation.

For better adaptation of the light intensity emitted by the diodes to the ambient brightness is the photosensitive element PSD shown in Fig. 2 and the downstream amplifier OP2 intended. These units provide an electrical control signal to the control input of the power source ICV1 supplied by the through the element PSD (preferably looking towards the Light signal) depends on the measured luminance of the environment. When the ambient brightness drops the current carried by the diode groups CL1, ..., CLn is therefore reduced. The characteristic of the Amplifier OP2 is chosen such that the desired difference in luminance is always present is. It is also provided that the holding current for the relays RLS11-RLS1n is never undercut.

A symbol to be signaled is preferably formed by at least two diode groups CL1, CL2 educated. The light-emitting diodes LD of these groups CL1, CL2 are arranged in such a way that if a group CL1 or CL2 fails, e.g. caused by the interruption of a diode LD the symbol remains recognizable. For example, the symbol is used by both Groups CL1, CL2 are displayed, which means that if a group CL1 or CL2 fails, only one Luminance drop occurs. The traffic light system therefore remains in operation until that of the main station reported bugs is fixed.

1 and 2, the resistors Rg and Rr (base and residual load resistance) on the primary side of the XFMR transformer, these load resistances can be taken into account the transformation ratio of the transformer XFMR can also be arranged on the secondary side. The relay RLS2 on the secondary side of the transformer XFMR can also be used before or after the rectifier circuit GS may be provided.

Some of the measuring and switching processes could also be controlled by a microprocessor.

In Fig. 3, the state of lighting units BEg1, ..., BEgn provided with rectifier units GS or the state (tightened / released) of the relays RLS11, ..., RLS1n is reported to a logic circuit LC, which is a function of the state of the Lighting units BEg1, ..., BEgn actuated the relays RLS2 and RLS3. 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 in such a way that the relay RLS3 is actuated in the event of a number (1 to m) of error messages and the relay RLS2 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 number m is usually chosen to be significantly smaller than n (for example: 10 * m = n ). When the number (m + 1) to n error messages occurs, several lighting units BEg1, ..., BEgn have failed, which indicates a serious defect that must be remedied as quickly as possible. If only one or two lighting units BEg1, ..., BEgn have failed, the optical signals are still legible. 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 filament of an incandescent lamp. The multiple error case corresponds to the failure of the reserve coil. The logic circuit LC can of course also be connected directly to a control station.

Claims (6)

1. Circuit arrangement for railway light signal systems, having a transformer (XFMR) which can be connected on the primary side by way of an alternating voltage input (INP) to a current supply line and is connected on the secondary side to at least one lighting unit (BE1, ..., BEn), characterized in that the lighting units (BE1, ..., BEn) in each case have a first relay (RLS11;...;RLS1n), a series resistance (Rv) and light-emitting diodes (LD1, ...,LDx), in that the secondary winding of the transformer (XFMR) is connected by way of a rectifier circuit (GS), the winding of the first relay (RLS11;...;RLS1n) and the series resistance (Rv) to the light-emitting diodes (LD1, ...,LDx), in that by means of a contact (K11;...;K1n) actuated by the first relay (RLS11;...;RLS1n) the winding of a second relay (RLS2) can be connected on the primary or secondary side of the transformer to a direct or alternating voltage, and in that the second relay (RLS2) has a first contact (K21), by means of which a residual load resistance (Rr) can be connected parallel to a base load resistance (Rg) which is permanently connected to both terminals of the primary or secondary winding of the transformer (XFMR), wherein the base load resistance (Rg) is provided for conducting a permanent base current and the residual load resistance (Rr) is provided for conducting a residual current, by means of which the operating state of the lighting units (BE1, ...,BEn) is displayed by way of the current supply line.
2. Circuit arrangement according to claim 1, characterized in that the second relay (RLS2) has a second contact (K22), by means of which a fault signalling line (FML) can be short-circuited.
3. Circuit arrangement according to claim 1 or 2, characterized in that the contacts (K11;...;K1n) actuated by the first relays (RLS11;...;RLS1n) of the lighting units (BEg1, ..., BEgn) are part of a logic circuit (LC) which actuates the second relay (RLS2) upon the occurrence of more than m fault signals displayed by the contacts (K11;...;K1n), and which, upon the occurrence of 1 to m fault signals displayed by the contacts (K11;...;K1n), actuates a third relay (RLS3), wherein by means of the contact (K31) actuated by the third relay (RLS3) a load applied to signalling lines (a, b, c) can be changed.
4. Circuit arrangement according to claim 1, 2 or 3, characterized in that the rectifier circuit (GS) is connected by way of a controllable current source (ICV1) to the winding of the first relay (RLS11), in that a light-sensitive element (PSD) is provided which can measure the luminance present in the environment of the light signal system and which emits an electric signal, depending on the measured luminance, to the input of an amplifier (OP2), the output of which is connected to a control input of the current source (ICV1).
5. Circuit arrangement according to claim 1, 2, 3 or 4, characterized in that the input of the lighting unit (BEc) is connected by way of a voltage divider, formed by two resistances (R1, R2), to the first input of a difference amplifier (OP1), the second input of which is connected to a voltage source (UC) which delivers a constant voltage, and in that the output of the difference amplifier (OP1) is connected to a switching unit (SWb), by means of which a shunt resistance (Rn) can be connected parallel to the series resistance (Rv) and the light-emitting diodes (LD1, ...,LDx) or in that the output of the difference amplifier (OP1) is connected to a transistor (TR) which is connected in series with the light-emitting diodes (LD1, ...,LDx).
6. Circuit arrangement according to one of claims 1 to 5, characterized in that each of the lighting units (BEg1, ..., BEgn) has a rectifier circuit (GS).

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