Patent Publication Number: US-11383743-B2

Title: Rail signal arrangement for a rail signaling system

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application claims priority to United Kingdom Patent Application No. 1714832.1, filed Sep. 14, 2017, which is incorporated herein by reference in its entirety. 
     FIELD OF THE INVENTION 
     The present invention relates to a rail signal control system and a method of controlling the rail signal system. 
     SUMMARY OF THE INVENTION 
     According to a first aspect of the invention, a rail signal arrangement is provided for a rail signaling system comprising: a rail signal having a rail signal lamp comprising a plurality of light emitter sub-arrays each comprising a light emitter, wherein the light emitter sub-arrays are electrically connected in parallel, and a control circuit, wherein the control circuit is configured to: operate the rail signal lamp in response to operating instructions from a remote operations management system, detect the proportion of light emitter sub-arrays that are in an operable condition with a monitoring system, and provide a condition status signal to the remote operations management system in accordance with whether the proportion of light emitter sub-arrays in an operable condition meets a minimum threshold level. 
     According to a second aspect, a rail signaling system is provided having a rail signal arrangement according to the first aspect. 
     According to a third aspect, a method of controlling a rail signal is provided comprising: operating a rail signal lamp with a control circuit in response to operating instructions from a remote operations management system, the rail signal lamp comprising a plurality of light emitter sub-arrays each comprising a light emitter, wherein the light emitter sub-arrays are electrically connected in parallel, detecting the proportion of light emitter sub-arrays that are in an operable condition with a monitoring system, and providing a condition status signal to the remote operations management system in accordance with whether the proportion of light emitter sub-arrays in an operable condition meets a minimum threshold level. 
     According to a further aspect, a rail signal arrangement is provided for a rail signaling system comprising: a rail signal having a plurality of rail signal lamps each comprising a plurality of light emitter sub-arrays that each comprise a light emitter, wherein the light emitter sub-arrays of each rail signal lamp are electrically connected in parallel, and a control circuit, wherein the control circuit is configured to: operate the rail signal lamp in response to operating instructions from a remote operations management system, detect the proportion of light emitter sub-arrays that are operable with a monitoring system in each rail signal lamp, and provide a condition status signal to the remote operations management system in accordance with whether the proportion of operable light emitter sub-arrays in each rail signal lamp meets a respective minimum threshold level, wherein a plurality of the rail signal lamps have different respective minimum threshold levels. 
     According to a further aspect, a method of controlling a rail signal is provided comprising: operating a rail signal having a plurality of rail signal lamps with a control circuit in response to operating instructions from a remote operations management system, each of the rail signal lamps comprising a plurality of light emitter sub-arrays that each comprise a light emitter, wherein the light emitter sub-arrays of each rail signal lamp are electrically connected in parallel, detecting the proportion of light emitter sub-arrays that are operable with a monitoring system in each rail signal lamp, and providing a condition status signal to the remote operations management system in accordance with whether the proportion of operable light emitter sub-arrays in each rail signal lamp meets a respective minimum threshold level, wherein a plurality of rail signal lamps have different respective minimum threshold levels. 
     Each light emitter sub-array may comprise a plurality of light emitters that are electrically connected in series. The light emitters may be light emitting diodes. 
     The monitoring system may comprise a light sensor configured to detect light emitted from one or more light emitter sub-arrays when the one or more light emitter sub-arrays are supplied with a drive signal. Each light emitter sub-array may be provided with a light sensor optically coupled to receive light from a light emitter in the respective light emitter sub-array. 
     The monitor system may be configured to detect the condition of the light emitter sub-arrays by detecting current flowing through the light emitter sub-arrays when supplied with a drive signal. 
     The control circuit may be configured to provide rail signal lamp proving functionality, i.e., to store a condition status of each rail signal lamp and to return the condition status in response to an enquiry signal from a remote operations managements system. 
     The or each minimum threshold level may be at least 75%. The or each minimum threshold level may be a fixed minimum threshold level. The rail signal may comprise a plurality of rail signal lamps having different respective minimum threshold levels. 
     The rail signal may comprise a rail signal lamp for emitting red light with a threshold level that is higher than a rail signal lamp threshold level for a further rail signal lamp for emitting a non-red light. 
     The control circuit may be provided within a housing of the rail signal. 
     The light emitters may be LEDs and the control circuit may comprise a dummy load for dissipating current to emulate the current through incandescent light emitters. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Examples are further described hereinafter with reference to the accompanying drawings, in which: 
         FIG. 1  illustrates part of a rail signaling system; and 
         FIG. 2  schematically illustrates a part of a rail signaling system. 
     
    
    
     DETAILED DESCRIPTION 
     Like reference numerals refer to like elements throughout the drawings. 
       FIG. 1  illustrates part of a rail signaling system  100  having a rail signal  102  with an arrangement of one or more separate rail signal lamps  112 A- 112 C for visually communicating with the drivers of trains travelling on a rail track  190 .  FIG. 2  schematically illustrates part of the rail signaling system  100  for controlling one of the rail signal lamps  112 A. 
     The rail signal  102  has an arrangement of one or more signal lamps, and is also known within the rail industry as an “aspect”. The illustrated rail signal  102  has three rail signal lamps  112 A- 112 C for emitting red, yellow and green light respectively. 
     The rail signal  102  is controlled by a control circuit  110  that receives operating instructions from a remote operations management system  150 , and the control circuit returns a binary condition status signal to the remote operations management system. 
     In the illustrated rail signaling system  100 , the control circuit  110  is provided within the housing of the rail signal  102 . Alternatively, the control circuit  110  may be provided separately and in electrical communication with the rail signal  102 . 
     Power may be supplied to the control circuit  110  by the remote operations management system  150 , along cabling with the operating instructions, or may be provided separately, e.g. supplied locally. 
     The control circuit  110  comprises the signal lamps  112 A- 112 C, an aspect controller  114 , and a monitoring system, discussed below. 
     Each of the rail signal lamps  112 A- 112 C houses a plurality of light emitters  104 , which are operated with a driving signal (e.g. an operating bias) supplied by the aspect controller  114 . In the illustrated signal lamps  112 A- 112 C, each of the light emitters  104  is a light emitting diode (LED). However, alternative light emitters may be used, e.g. incandescent lights. 
     The plurality of light emitters  104  in each rail signal lamp  112 A- 112 C comprises a plurality of light emitter sub-arrays  116  that are electrically connected in parallel. In the illustrated signal lamps  112 A- 112 C, each light emitter sub-array  116  is a string of light emitters  104  that are electrically connected in series. 
     Each signal lamp  112 A- 112 C is provided with a monitoring system comprising a light sensor  118  that detects output from all or part of the signal lamp and a lamp health monitor  120  to determine how many of the light emitter sub-arrays  116  are emitting light. Although shown separately from the aspect controller  114  in  FIG. 2 , the lamp health monitor  120  may alternatively be a part of the aspect controller. 
     Each light emitter sub-array  116  may be provided with a respective light sensor (e.g. photodetector)  118  that is optically coupled to received light emitted by the light emitter sub-array. For example, in the illustrated signal lamps  112 A- 112 C, each light emitter sub-array  116  is a string of serially connected LEDs  104 , and each LED string is provided with a light sensor  118  that is optically coupled to receive light emitted by an LED in the respective LED string. Alternatively, a light sensor  118  may be provided that senses light emission from a light emitter  104  in each or a plurality of the sub-arrays  116 . The or each light sensor  118  may be a photodetector, as shown in the illustrated signal lamps  112 A- 112 C. Alternatively, the or each light sensor  118  may be a photosensitive transistor. 
     The lamp health monitor  120  receives a signal from the or each light sensor  118  and determines what proportion of the light emitter sub-arrays  116  in each rail signal lamp  112 A- 112 C operate (e.g. emit light) when driven (e.g. powered with a drive signal) and/or what proportion of the light emitter sub-arrays do not operate when driven. If one light emitter  104  in a string of serially connected light emitters fails, then current will not pass through that light emitter string, and no corresponding light output will be received by the emission monitoring system  120 , even if the light sensor(s) are optically coupled to receive light from a different light emitter of the string that has not failed. The lamp health monitor  120  provides a feedback signal to the aspect controller  114  corresponding to the proportion of light emitter sub-arrays  116  that operate when driven (e.g. in each rail signal lamp  112 A,  112 B,  112 C). 
     The aspect controller  114  compares the feedback signal for the (or each) rail signal lamp  112 A,  112 B,  112 C against a minimum threshold level (e.g. a level that is less than 100%) to produce a condition status signal (e.g. a binary signal). For example, the minimum threshold level may be that 75% of light emitter sub-arrays  116  in a rail signal lamp  112 A,  112 B,  112 C of light emitter sub-arrays are operable (i.e. illuminate when driven by a drive signal). If the operation of the lamp  112 A meets the satisfactory minimum threshold level, the aspect controller  114  returns a positive condition status signal to the remote operations management system  150 . However, if the operation of the lamp  112 A does not meet the satisfactory minimum threshold level, the aspect controller  114  returns a negative condition status signal (known as a “lamp out” signal) to the remote operations management system  150 , informing the operator of the rail signaling system  100  that it is necessary for a service engineer to visit the rail signal  102  to replace or repair the respective rail signal lamp  112 A,  112 B,  112 C (e.g. replace one or more light emitter sub-arrays  116 ). 
     Assessing the proportion of light emitter sub-arrays  116  that operate (e.g. illuminate when powered by a drive signal), when driven, against a minimum threshold level enables the rail signal lamps  112 A- 112 C to provide an improved operational lifetime for the rail signal lamp, and enables the rail signaling system  100  to operate with increased operational efficiency. Where the emission intensity of a rail signal lamp  112 A- 112 C is permitted to operate within a range, then following any reduction in the emission intensity of the rail signal lamp following the failure of a light emitter, assessing the reduced emission intensity against the minimum threshold level permits the continued use of the rail signal lamp, where it continues to fall within the permitted operating range. This avoids the transmission of a “lamp out” signal to the remote operations management system  150 , and the unnecessary (or premature) cost and waste from the replacement of the corresponding rail signal lamp  112 A- 112 C. In the case of a remotely located signal lamp  112 A- 1112 C, the difficultly in accessing and replacing a rail signal lamp may be particularly significant. 
     The minimum threshold level for each rail signal lamp may be a fixed minimum threshold level that is pre-set in the rail signal (e.g. pre-set in the rail signal lamp) during manufacture. The fixed minimum threshold level may be pre-set in firmware of the aspect controller  114 , or may be manually pre-set by a suitable configuration of an electro-mechanical input (e.g. during manufacture, selecting a resistance level of a variable resistor that is inaccessible to a subsequent user). The use of a fixed minimum threshold level enhances security by reducing the risk of an incorrectly set minimum threshold level. However, alternatively, the minimum threshold level may be settable by a respective level setting signal from the remote operations management system  150 . 
     The minimum threshold level for each lamp  112 A- 112 C may be the same. Alternatively, the rail signal lamps  112 A- 112 C in each rail signal  102  may have different minimum threshold levels. For example, different minimum threshold levels may be appropriate for different lamp colours. For example, a range of permitted light emission intensities may be narrower for a lamp that emits red light than for a lamp that emits yellow or green, for the purposes of enhanced safety, and the minimum threshold level for red may accordingly be higher. Alternatively, it may be beneficial to apply different minimum threshold levels for different colours of emitted light in correspondence with the different human perceptions of differently coloured light. The use of different minimum threshold levels may further enhance operation lifetime for the rail signal and enable the rail signaling system  100  to operate with increased operational efficiency, in particular where failure of one or more light emitter sub-arrays  116  occurs in rail signal lamp  112 A- 112 C with a lower minimum threshold level. 
     To provide backwards-compatibility, where the light emitters are light emitting diodes (which typically have a much lower drive current than an incandescent lamp providing a corresponding illumination) the driving currents to each rail signal lamp  112 A- 112 C may be the same as for corresponding, legacy filament (incandescent) lamp systems, with excess current being dissipated through a dummy load (not shown). 
     The operation of a rail signaling system  100  has been described above in relation to assessing the illumination intensity of rail signal lamps  112 A- 112 C in their on-states by detecting light emitted by a light emitter  104 , with the lamp health monitor  120  receiving signals from light sensors  118  that detect emitted light. However, alternatively, the lamp health monitor may receive signals corresponding to current flowing through the sub-array, for example by detecting the voltage across a resistor serially connected with each sub-array, e.g. with a comparator circuit that provides an output to the lamp health monitor. 
     The rail signaling system  100  may additionally comprise proving functionality, in which the remote operations management system  150  sends repeated enquiry signals to the aspect controller  114  of the control circuit  110  in relation to each of the signal lamps  112 A- 112 C, seeking return of the last stored condition status of each signal lamp. For hot-proving functionality, in which a signal lamp  112 A- 112 C is in the on-state (being driven to emit light), the condition status determined when the lamp was last turned on will be returned, or alternatively a fresh determination of condition status may be prompted and the current condition status returned. For cold-proving functionality, in which a signal lamp  112 A- 112 C is in the off-state (not being driven to emit light), the stored condition status will be the condition status that was determined by the lamp health monitor  120  when the last on-state (being driven to emit light) of the signal lamp was commenced, or the most recent condition status determination whilst the signal lamp was in the on-state. 
     The enquiry signals sent by the remote operations management system  150  may be short voltage pulses (positive or negative pulses) and the aspect controller  114  may present an electrical load corresponding to the condition status of a signal lamp  112 A- 112 C (e.g. there may be a dedicated wire between the remote operations management system and the aspect controller for each signal lamp), and the remote operations management system may detect the condition status of a signal lamp by detecting the current flowing through the presented electrical load. Alternatively, the enquiry signals sent by the remote operations management system  150  may be digital codes that prompt the aspect controller  114  to return a further digital code corresponding to the last stored condition status of each signal lamp  112 A- 112 C. 
     The figures provided herein are schematic and not to scale. 
     Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of them mean “including but not limited to”, and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise. 
     Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed. 
     The reader&#39;s attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.