Abstract:
A combination model train sensor and signal includes a train proximity sensor, a signal such as red yellow and green signal lights, semaphores, wig-wag signals and the like together with a controller connected to the proximity sensor and the signal and the controller activates the signal appropriately when the proximity sensor indicates the absence of a train, and when the train proximity sensor indicates the presence of a train. A light source, preferably an infrared light source, and a light detector, preferably an infrared light detector, are arranged to reflect and detect from a passing train to indicate its presence. An output connected to the train proximity sensor for producing an output signal when the sensor indicates the presence of a train, which output can be used for controlling a remote signal. An input, responsive to a signal received from a remote sensor, controls the signal and synchronizes two signals.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a continuation-in-part of U.S. Ser. No. 09/826,654 filed Apr. 5, 2001(now U.S. Pat. No. 6,600,429). 
   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   Not Applicable 
   REFERENCE TO A “SEQUENCE LISTING” 
   Not Applicable 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates generally to accessories for toy or model railroad layouts and more particularly to an improved combination signal and train detector for such layouts. 
   There is a demand for model railroad accessories that simulate signals used on full sized railroads. Such accessories include block signals, semaphores, wig-wag signals and others. A block signal controls the passage of trains by providing a red or green signal to the engineer indicating whether it is safe to pass the block signal. 
   In full size trains, signals such as block signals semaphores and the like (collectively referred to herein for convenience as block signals) are controlled by a variety of complex mechanisms the precise duplication of which is not practical in model train layouts. This invention may be applied to signals that control the passage of trains, and to signals that control the passage of vehicular traffic at grade crossings. Accordingly, it has become common to provide block signals in model train layouts that turn red when a train approaches and turn green after the train has passed. Previously known block signals have been relatively simple devices that include a red light and a green light that can be selectively illuminated by applying appropriate activating signals to inputs of the block signal. The inputs to the block signals have come from a variety of sources generally referred to as train detectors. Known train detectors include detectors that use a section of isolated track that is responsive to a train passing over it and light or magnetic sensors to detect the presence of a passing train. 
   2. Background Art 
   Heretofore, providing block signals responsive to the passage of trains has required the use of multiple devices and sometimes complex wiring connections between them. 
   It is an object of this invention to provide a combination of a block signal and train detector that greatly simplifies installation compared with known approaches. 
   It is another object if this invention to provide a combination block signal and train detector that can be easily synchronized with similar devices positioned at remote locations on a model train layout. 
   It is another object of the invention to provide a combination block signal and train detector that uses simple inexpensive circuitry that allows the device to be manufactured and sold at reasonable prices 
   BRIEF SUMMARY OF THE INVENTION 
   Briefly stated, and in accordance with one embodiment of the invention, a combination model train sensor and block signal includes a train proximity sensor, a red signal light, a green signal light, and a controller connected to the proximity sensor and the red and green signal lights. The controller turns on the green signal light and turns off the red signal light when the proximity sensor indicates the absence of a train, and turns on the red signal light and turning off the green signal light when the train proximity sensor indicates the presence of a train. 
   In accordance with another aspect of the invention, a combination model train sensor and signal includes a train proximity sensor, a safe to proceed signal and a stop signal connected to a controller as just described in which the controller activates the safe to proceed signal and deactivates the stop signal when the proximity sensor indicates the absence of a train and activates the stop signal and deactivates the safe to proceed signal when the train proximity sensor indicates the presence of a train. 
   In accordance with another aspect of the invention, the signal is a wigwag or swinging banjo signal. 
   In accordance with another aspect of the invention, the signal is a semaphore signal. 
   In accordance with another aspect of the invention, the signal is a target signal. 
   In accordance with another aspect of the invention, the train proximity sensor of the model train sensor and signal includes a light source, preferably an infrared light source, and a light detector, preferably an infrared light detector, arranged to reflect and detect from a passing train to indicate its presence. 
   In accordance with another aspect of the invention, the combination model train sensor and signal includes an output connected to the train proximity sensor for producing an output signal when the sensor indicates the presence of a train, which output can be used for controlling a remote block signal. 
   In accordance with another aspect of the invention, the combination model train sensor and signal includes an input, responsive to a signal received from a remote sensor, for controlling the illumination of the red and green lights and synchronizing two block signals. 
   In accordance with another aspect of the invention, the combination model train sensor and signal includes a combination input/output connected to the controller, the input/output producing a train present signal when the train proximity sensor indicates the presence of a train and being responsive to an externally applied train present signal for turning the red light on and the green light off even when the local train proximity sensor indicates the absence of a train. 
   In accordance with another aspect of the invention, the combination model train sensor and signal includes a first transistor switch for turning on the green light, the first transistor switch preferably connected to be normally on and a second transistor switch having an input connected to the train proximity sensor and an output connected to the red signal light and to an input of the first transistor switch to turn the red signal light on and apply an off signal to the input of the first transistor switch to turn the green signal off. The second transistor switch is preferably connected to be normally off. 
   In accordance with another aspect of the invention, the input/output is connected to the second transistor switch. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
     The novel aspects of the invention are set forth with particularity in the appended claims. The invention itself together with further objects and advantages thereof may be more readily understood by reference to the following detailed description of a presently preferred embodiment of the invention taken in conjunction with the accompanying drawing in which: 
       FIG. 1  is a diagrammatic view of a combination model train sensor and block signal disposed at a track side location. 
       FIG. 2  is a schematic diagram of a combination model train detector and block signal in accordance with this invention; 
       FIG. 3  is a diagrammatic view showing two combination model train detectors and block signals connected together for synchronized operation in accordance with the invention; 
       FIG. 4  is a diagrammatic view of a combination model train sensor and a block signal having three signal lights in accordance with another embodiment of the invention; 
       FIG. 5  is a rear prospective view of a model train sensor and semaphore signal in accordance with the invention; 
       FIG. 6  is a front perspective view of the semaphore signal of  FIG. 5  in accordance with the invention; 
       FIG. 7  is an enlarged partial view of the signal portion of the semaphore signal of  FIGS. 5 and 6  shown in a safe to proceed position; 
       FIG. 8  is an enlarged partial view of the semaphore signal of  FIG. 7  shown in a caution position; 
       FIG. 9  is an enlarged partial view of the semaphore signal of  FIGS. 5 and 6  in a stop position; 
       FIG. 10  is a front prospective view of a model train sensor and target signal having two signal lights in accordance with the invention; 
       FIG. 11  is a front elevation of a model train sensor and wigwag or banjo signal in accordance with this invention; 
       FIG. 12  is a rear prospective view of the wigwag signal of  FIG. 11 ; 
       FIG. 13  is a front elevation of the wigwag signal of  FIG. 11  showing the signal in the stop configuration; 
       FIG. 14  is an enlarged view of an enlarged rear prospective view of an operating mechanism for the movable portion of the wigwag signal of  FIG. 13 ; and 
       FIG. 15  is a block diagram schematic of controller for the three state signals of the invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring now to  FIG. 1 , a combination model railroad detector and block signal in accordance with this invention is illustrated in a diagrammatic form. For convenience, we will refer to the combination model train sensor and block signal as a block signal detector even though that language is slightly incongruous. The block signal detector indicated generally at  10  is positioned closely adjacent a section of a model railroad track  12 . Preferably, the signal is positioned within in about ½″ of the track to ensure reliable train detection. 
   The block signal detector  10  includes a red signal light  14  and a green signal light  16  arranged in the upper portion of a housing  20  that is configured to look like an actual block signal, of the type used on a full sized railroad. To that end, a simulated access door  22  is provided in the lower portion of the signal and the signal lights  14  and  16  are arranged in a conventional top and bottom configuration. Preferably, light hoods  24  and  26  surround the lights to make the signal lights visible in bright sun. Preferably, the block signal detector is formed of relatively high impact plastic to provide a durable but low cost construction. The plastic housing can be injection molded to produce a pleasing appearance at low cost. The internal components of the housing are mounted on a printed circuit board that is actually accessed through a rear cover plate  30  rather than simulated access door  22 . 
   Preferably, an infrared light source  32  is mounted on the printed circuit board (not visible in this figure) and extends through an opening in housing  20 . A preferably infrared sensor  34  is mounted in relatively close proximity to infrared source  32  but the source and detector are arranged so that the detector is not responsive to light emitted directly from the source but is responsive only to a light reflected from a passing model train. An internal light barrier between the source and the detector may also be used. 
   The operation of the block signal detector will now be described in conjunction with the schematic diagram of a presently preferred embodiment of a controller therefor shown in  FIG. 2 . 
   The block signal detector circuitry is designed to be powered from a 12–14 volt AC source sometimes referred to as a transformer, of the type used to provide power to the engines and accessories of model trains. Power input terminal  50  is adapted to be connected to the AC power source and a common terminal  52  which for convenience may be referred occasionally herein as a ground terminal even though is it is not in fact grounded, is adapted to be connected to the opposite side of the power source. A rectifier diode  54  is connected between the power input terminal  50  and a light emitting diode  56  which is preferably an infrared light emitting diode. Current limiting resistors  58  set the current through infrared emitting diode  56  to a level that balances long diode life with sufficient light output to reliably detect the presence of model trains. 
   The arrangement just described produces a stream of light pulses having a repetition rate of approximately 60 hertz from infrared emitting diode  56 , rather than a constant beam. An infrared detector  60  is connected to an inverting input  66  of an operational amplifier  68 . Operational amplifier  68  is preferably ½ of an LM393M dual operation amplifier. A high pass filter, including a capacitor  62  and a resistor  64  is connected between the output of infrared detector  60  and an input  66  of an amplifier  68  to substantially eliminate false triggering caused by constant ambient light. This permits the sensitivity of operational amplifier  68  to be set relatively high for reliable train detection without increasing false triggering from ambient light. The sensitivity of the operational amplifier  68  is set by a variable resistor  70 . The remaining components associated with operational amplifier  68  are conventional and will be readily understood by those skilled in the art. 
   An output  72  of an amplifier  68  is connected to an inverting input  74  of a second operational amplifier  76  configured as an inverter to correct the sense of the output signal for operating the controller of the block signal detector. The output terminal  80  of the amplifier  76  is connected through a resistor  82  to the base  84  of a transistor  86 . Base  84  is normally held high by resistors  88  and  82  so that the transistor is normally on. Output  80  pulls base  84  essentially to ground through resistor  82  when a train is present as indicated by the presence of reflected infrared light at detector  60 . The portion of the block signal detector just described is indicated in phantom lines in  FIG. 2  as train proximity detector  90 . The remaining portion of the circuit, indicated in phantom as  92 , is referred to as the controller. A second rectifier diode  94  provides power to controller  92  and proximitor sensor  90 . A filter capacitor  96  smoothes the output of rectifier diode  94  to provide relatively steady DC output for the red and green signal lights. 
   Referring back to  FIG. 2 , a red signal light  100 , preferably a red light emitting diode, is connected in series with a collector load resistor  102  between a collector  104  of transistor  86  and the positive voltage source. An emitter  106  of transistor  86  is connected to common. Normally, transistor  86  is held off by inverter amplifier  76  and red light emitting diode  100  is extinguished. As long as transistor  86  is off, base  110  of transistor  112  is held high by resistor  102  thereby turning transistor  112  on and allowing current to flow through the green signal light  114  which is preferably a green light emitting diode, and then through a collector resistor  116  which sets the current through a light emitting diode  114 . The collector  118  of transistor  112  is connected to the positive voltage source. 
   When a train is detected, the signal applied to the base  84  of transistor  86  goes high turning transistor  86  on. The voltage at base  110  of transistor  112  is pulled low to a voltage of approximately equal to the saturation voltage of transistor  86  plus the voltage drop of light emitting diode  100 , the sum of which is approximately 1.7 volt which turns transistor  112  off and extinguishes light emitting diode  114 . 
   In accordance with a presently preferred embodiment of the invention a time delay is provided so that the red signal lamp remains illuminated and the green signal lamp remains extinguished for a pre-selected time after the proximity detector has detected the passage of a train. Time delay capacitor  126  is connected the output  72  of amplifier  68  and ground. The time constant of capacitor  126  and resistor  128  connected in series therewith, sets the predetermined time. Preferably, a time of about 2 seconds is provided. 
   In accordance with the preferred embodiment of the invention, an input/output terminal  20  is provided. Input/output terminal  120  is connected to collector  104  of transistor  86  through a small isolation resistor  122 . It will be appreciated that when a train is detected by the proximity detector  90  and transistor  86  is turned on, the input/output terminal  120  is pulled low through resistor  122 . When no train is present and transistor  86  is off, the input/output terminal  120  is high. 
   If a low or ground remote signal is connected to input/output terminal  120  it will be appreciated that the collector  104  of transistor  86  will be pulled low whether transistor  86  is turned on or off by proximity detector  90 . Since transistor  86  is normally off in the absence of a train, it will be seen that a remote train present signal applied to input/output terminal  120  will turn red signal light  100  on and turn green signal light  114  off. This allows two block signal detectors in accordance with the invention to be synchronized so that when one detects the presence of a train, the light in the other will also turn from green to red. The synchronization is bidirectional and the wiring is exceeding simple as will be seen by reference to  FIG. 3 . 
     FIG. 3  shows a pair of block signal detectors  10  and  10 ′ interconnected for synchronized operation. Terminals  50 ,  52  and  120  of first block signal detector  10  are connected to the like numbered terminals of the second block signal detector  10 ′. A power source of 12–14 volts AC is connected between terminals  50  and  52  of the two block signal detectors respectively as shown at  130 . It will appreciated that if for example a train approaches from the left as the Figure would normally be viewed, block signal detector  10 ′ will detect the proximity of the train and the red signal lamp will be illuminated and the green signal lamp extinguished. Simultaneously, input/output  120  of block signal  10  will be driven low thereby illuminating the red signal lamp and extinguishing the green signal lamp of block signal detector  10  even though no train is detected by the proximity detector of block signal detector  10 . Similarly, if a train approaches from the right, the detectors in block signal detector  10  will sense the proximity of the train and illuminate the red signal light and extinguish the green signal light of both of the block signal detectors  10  and  10 ′. 
     FIG. 4  is a diagrammatic view of a combination model railroad detector and block signal in accordance with another aspect of this invention. The block signal detector  200  includes a red signal light  204 , a yellow signal light  208 , and a green signal light  212 . A simulated access door  214  is provided in the lower portion of the signal and the signal lights  204 ,  208  and  212  are arranged in conventional top to bottom configuration in the upper portion. Preferably, light hoods  202 ,  206  and  210  surround or cover the top portions of the lights to make the light signals visible in bright sun. Preferably, like the block signal shown in  FIG. 1 , the block signal detector shown in  FIG. 4  is formed of a relatively high-impact plastic to provide a durable but low cost construction. The internal components of the block signal and sensor are preferably mounted on a printed circuit board that is accessed through a rear cover plate  216 , rather than the simulated access door  20 . 
   Preferably, an infrared light source  218  is mounted on the printed circuit board (not shown) and extends through an opening in a housing  222 . A preferably infrared sensor  220  is mounted in relatively close proximity to infrared source  218 , but the source and detector are arranged so that the detector is not responsive to light emitted directly from the source but is responsive only to light reflected from a passing model train. An internal light barrier between the source and the detector may be used if desired. 
   A controller for the combination model train sensor and simulated block detector of  FIG. 4  is shown in  15  and will be described after describing a number of other signals in accordance with the invention, all of which may be controlled by the same or a similar controller. 
     FIG. 5  shows a combination model railroad detector and a semaphore signal in accordance with the invention. The semaphore signal  300  includes a base on which an infrared light source  318  and an infrared detector  320  are mounted. In each of the signals shown in the following figures, the light source and detector are mounted and isolated as described in connection with  FIGS. 1 and 4 . The semaphore signal itself is mounted on the upper portion of supporting pole  304 . A movable semaphore signal blade  310  is mounted on a shaft  308  of an actuator  324 . Semaphore blade  310  is movable among safe to proceed, caution, and stop positions, as shown and described in more detail in connection with  FIGS. 7–9 . Actuator  324  may be a small motor, a rotary solenoid actuator or the like capable of positioning the semaphore signal blade at the three principal positions. 
   A light source  322  is mounted on support  304  and projects a light beam through light filters  312 ,  314  and  316 , respectively, in the three positions of the semaphore signal. Preferably, light filter  316  produces a green light, light filter  314  produces a yellow light, and light filter  312  produces a red light. In this way, only a single light source  322  is required to provide three different colored simulated signals. 
     FIG. 7  shows the semaphore signal in the safe to proceed position. The semaphore blade  310  is vertical and green filter  316  is positioned in front of light source  322 . 
     FIG. 8  shows the semaphore signal in the caution position. Blade  310  is positioned at approximately a 45 degree angle and yellow light filter  314  is positioned in front of light switch  322 . 
     FIG. 9  shows the semaphore signal in the stop configuration. Semaphore blade  310  is oriented horizontally and the red light filter  312  is positioned in front of light source  322 . Preferably, the semaphore blade  310  and the filter holder portion  306  extending from the blade on the opposite side of the pivot from the blade are fabricated from a high impact plastic or the like which may be molded to provide a durable but low cost construction. 
     FIG. 10  shows a two-light, target signal in accordance with this invention. The target signal includes a base  400  that is quite similar to the base of the semaphore signal shown in  FIGS. 5 and 6 . A light source  422  and a light detector, preferably an infra red detector  424 , are positioned in the base and arranged to be oriented facing a track along which a model train moves. A simulated access door  402  may be provided and an actual access door is preferably provided for gaining access to the internal components of the combination sensor/signal much in the manner of  FIGS. 1 and 5 . 
   An elongated vertical column  404  supports one or more target signals of which two, signals  410  and  416 , are shown in  FIG. 10 . Preferably, target signal  416  is a red stop signal and target signal  410  is a green safe to proceed signal. 
   Stop signal  416  includes a preferably red light  412  and a light hood  414 . Safe to proceed signal  410  includes a preferably green light  406  and a light hood  408 . Housings  418  and  420  contain the light sources, which may be a conventional incandescent or LED lamp. The electrical connections to which are entrained through support  404  into base  400 . 
     FIGS. 11 through 14  show a wigwag or, banjo signal in accordance with this invention. Banjo signal  400  includes a base  402  and a simulated equipment cabinet  404 . An electrical circuit board, preferably a printed circuit board, that includes the electrical components of the signal and sensor may be mounted in cabinet  404  or in base  402 . As will be described in more detail below, an electrical motor for actuating the wigwag signal may also be mounted in base  402 . The wigwag signal includes a vertical support  406  having simulated signage thereon extending to an upper portion  408  on which a conventional railroad crossbuck is mounted. The wigwag signal is attached to the supporting column between the signage and the crossbuck and includes a cantilevered arm with a diagonally arranged supporting arm carrying an actuator  414  and a movable banjo signal  410 . Preferably, a selectively illuminated red signal light  412  is mounted in the middle of the banjo signal. 
   As shown in  FIG. 12 , the simulated equipment housing includes an opening through which an infrared light source  416  can be seen. Light source  416  is arranged to project light such as infrared light down the track in a direction toward the vertical support from the simulated equipment cabinet. An infrared detector  406  is mounted on the base of the wigwag detector to sense light reflected from an approaching train. Housing  414  includes a bushing through which a pivoted support rod for the wigwag signal is mounted. An actuating arm extends downwardly from the housing as will be shown in more detail in  FIG. 14 . An actuating string or the like is attached to the lower end of the actuating arm an entrained through various direction changing pulleys or openings into the base  402  of the wigwag signal where it is actuated by a motor, not shown. 
     FIG. 13  shows the wigwag signal in operation. The signal  410  moves left and right repeatedly and the light  412  is illuminated to simulate a stop or unsafe to proceed condition. The light source is extinguished and the wigwag signal stops in a more or less vertical position to signal a safe to proceed condition. 
   As shown in  FIG. 14 , the pivotal support rod  422  extends through a mounting block on the top of the cantilever arm of the wigwag signal. A spring  420  biases the wigwag signal to the extreme left (right as shown in this figure) position from which it may be moved by string  426 . When the wigwag signal is in the safe to proceed configuration, the string is tensioned to position the signal essentially vertically. The string is repeatedly tensioned and released to move the signal back and forth in the stop configuration. 
   A generalized controller for the combination model railroad sensors and signals in accordance with this invention is shown in  FIG. 15 . The controller  516  will be understood to be substantially similar to the controller shown in  FIG. 2  except that three states are enabled for controlling three state and two state signals. An infrared source  504  is connected through a current limiting resistor  502  to a voltage supply such as a five-volt supply  500 . The cathode of the infrared source, which is preferably an infrared light admitting diode is connected to terminal  2  of controller  516  for turning the infrared source on and off. Preferably, the source is pulsed as described above. 
   The light from the infrared source is reflected from a passing model railroad engine or car  510  and detected by infrared detector  506 . Detector  506  is connected between the five-volt source  500  and ground  528  through a current limiting resistor  508 . A low pass filter comprised of capacitor  512  and resistor  514  conditions the output of detector  506 , which is applied to input  3  of controller  516 . Terminal  8  of the controller is connected to ground in terminal  1  to the five-volt source. The controller has four outputs for selectively enabling thee visual output devices illustrated as a light emitting diodes  520 ,  522  and  524  which are preferably red, yellow, and green, respectively, all connected to the five-volt source  500  through a current limiting resistor  518 . An actuator, indicated generally at  526 , is connected to output  7  and to the five-volt source. The actuator  526  may be actuator  322  of the semaphore signal or the actuator for the wigwag signal shown in  FIG. 13 . The exact signal applied to the actuator  526  depends on the nature of the actuator and a programming of controller  516  to provide those signals is a matter of conventional design once guided by the disclosure of the signals as set forth herein. 
   While the invention has been described in connection with the presently preferred embodiment thereof, those skilled in the art will recognize that a number of modifications and changes may be made therein without departing from the true spirit and scope of the invention which accordingly is intended to be defined solely by the appended claims: