Abstract:
An apparatus for a model toy train includes a circuit configured to supply an output signal to energize at least one stationary light to simulate a light having movement like a mars unit light display.

Description:
PRIOR APPLICATIONS 
   This application claims the benefit of U.S. Provisional Application No. 60/430,893 filed Dec. 4, 2002. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates driver for one or more lights mounted on a train engine and, more particularly, to a driver capable of simulating behavior of a Mars Unit of a train engine. 
   2. Description of the Related Art 
   In addition to its normal headlight, some train engines also have a Mars Unit mounted thereto. The Mars Unit comprises a white, or emergency red, lamp, or light, and the apparatus that causes the light to oscillate. Sometimes, a portable Mars Unit is equipped at the rear of a train. The white light of the Mars Unit can be a bright white; light or a dim white light. 
   The Mars Unit is used for a variety of purposes. For example, it can be used as a protection light during the day or night to indicate that the train is disabled. As a protection light, it can also be used when the engine is likely to be overtaken by another engine or when the engine is traveling in adverse weather. Oftentimes, a Mars Unit is set to operate automatically when train speed drops below 18 miles per hour (MPH) and during stops, shutting off automatically when train speed goes above 18 MPH. 
   The Mars Unit can also be used, with or without the oscillating apparatus, as an emergency headlight in the event the headlight of the train engine fails. If the oscillating apparatus of the Mars Unit is disabled, the light can also be used as a focus light, directing attention to possible fallen rock, etc. 
   The use of a Mars Unit in a model toy train as implemented in an actual train is impractical due to the cost, size and energy required by the oscillating apparatus. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
       FIG. 1  is a circuit diagram of a lamp driver for one light according to one embodiment of the present invention; 
       FIG. 2  is a schematic diagram of a partial train set up incorporating a lamp driver for a plurality of lights according to a second embodiment of the present invention; 
       FIG. 3A  is a schematic diagram of a fiber optic bundle arranged in a figure eight pattern and connected to a plurality of light-emitting diodes driven by a lamp driver according to the second embodiment of the present invention; 
       FIG. 3B  is a partial cross-sectional view of the circuit board of  FIG. 3A ; 
       FIG. 4  is a diagram of an embodiment of a fiber optic bundle arranged in a figure-eight pattern with a first set of lights simultaneously illuminated; 
       FIG. 5  is a diagram of an embodiment of a fiber optic bundle arranged in a figure-eight pattern with a second set of lights simultaneously illuminated; and 
       FIG. 6  is a diagram of an embodiment of a fiber optic bundle arranged in a figure-eight pattern with a third set of lights simultaneously illuminated. 
   

   DETAILED DESCRIPTION 
   The present invention is a lamp driver for a model toy train car, particularly a train engine, that can simulate the functionality of a Mars Unit of an actual train without the need for an oscillating apparatus.  FIG. 1  shows a simple circuit diagram of one lamp driver  10  than can be used with one or more light-emitting diodes. The lamp driver  10  is mounted on a train car, preferably on a train engine  30  seatingly engaged on a train track  32  as shown in  FIG. 2 . Although the remainder of the description describes the lamp driver  10  as being mounted on the train engine  30 , the lamp driver  10  can, of course, be added to other cars of the train setup. The train engine  30  conventionally receives inputs from the track  32  through a connector, here a three-pin connector  12 . For example, where the train engine  30  is equipped to receive serial communications, such as those sent according to Lionel® TrainMaster® command control (TMCC), the three-pin connector  12  supplies both the track voltage from the “third rail” and the serial communications for one or more controllers mounted in the train engine  30 . A train engine  30  incorporating a lamp driver  10  that is not equipped for serial communications is discussed in more detail below. 
   Alternating current (AC) track voltage is fed to a voltage regulator  14 , which produces a stable direct current (DC) voltage-Vs. The voltage regulator.  14  is a standard voltage regulator, which typically includes filtering. A diode  14   a  taps the connector  12  at the input of the AC track voltage. The cathode of the diode  14   a  is connected to a grounded capacitor  14   b  and to the input of any standard three-terminal integrated circuit (IC) regulator  14   c . The output of the regulator  14   c  is a stable DC voltage-Vs. One typical voltage Vs used in these applications is five volts. Therefore, the voltage regulator  14  of  FIG. 1  can be a 5-volt voltage regulator. 
   The DC voltage Vs supplies a processor  16 , here a standard eight-pin microcontroller. Of course, a microcontroller is used as the processor  16  by example only. A microprocessor connected to non-volatile memory can also be used as the processor  16 . The physical requirements for the processor  16  are best described with reference to its functionality. The processor  16  is supplied by −Vs at its VCC input, which is connected to a grounded filtering capacitor  18 . A constant current is supplied to an input of the processor  16  by a resistor  20  connected in series with −Vs. The processor  16  is operable to receive serial communications from the connector  12  through a series resistor  22 . The output of the processor  16  is a pulse-width modulated (PWM) signal. 
   The signal from the processor  16  is fed through a lamp controller  24  prior to being input to one pin of a two-pin connector  26  into which a standard light-emitting diode (LED), or other source of light, can be inserted. The other pin of the two-pin connector  26  is connected to −Vs. The lamp controller  24  performs the function of converting the signal from the processor  16  to a current sufficient to energize the light connected to the two-pin connector  26 . In the lamp controller  24  shown in  FIG. 1 , the output of the processor  16  is connected to base of a standard npn transistor  24   a  through a series resistor  24   b . The emitter of the transistor  24   a  is grounded, and the collector of the transistor  24   a  is connected to one pin of the connector  26  through a second series resistor  24   c.    
   The processor  16  can be programmed according to known methods so that the duty cycle of the PWM signal changes. For example, varying the duty cycle of the signal supplied to an LED from approximately 10% to 90% and then back down to approximately 10% at a predetermined rate, such as once every second, makes the LED resemble an incandescent bulb moving from side-to-side. Using signals from the serial communications, the processor  16  can also be programmed to change the PWM signal output from the processor  16  based upon certain conditions of the train engine  30 . Thus, the processor  16  can be remotely controlled using TMCC to operate the light or lights at all times, to operate the light(s) only when the train engine  30  is moving forward, to operate the light(s) only when the train engine  30  is moving in reverse, or to shut off the light(s). 
   The pulse width modulation signal can be indicative of a signal of varying shape. According to various embodiments, a PWM can be indicative of a saw tooth, triangular, sinusoidal, square, exponential, or other wave form or combination of wave form patterns. Thus the PWM output signal can be used to energize at least one light with varying brightness over time according to the desired pattern. According to one embodiment, the output signal can be supplied to a single light to vary the brightness to simulate a light having movement. According to one embodiment, the output signal can be supplied to a group of lights to energize any one or more within the group with visably varying brightness to simulate a light having movement. According to one embodiment, the output signal can be supplied to sequentially energize a first set of lights followed by a second set of lights wherein the first set includes one or more lights and the second set includes one or more lights to simulate a light having movement. Either the first set or the second set or both can be controlled to include lights having varying brightness to simulate a light having movement. 
   Many existing and new train cars and engines are unable to respond to serial communications, such as those signals sent using TMCC.  FIG. 2  shows a partial train setup where serial communications are not sent, so cannot be received by the train engine  30 , even if equipped to receive serial communications. The lamp driver  10  is placed inside the train engine  30 . As mentioned, the train engine  30  is seatingly engaged upon the train track  32 . The train track  32  is electrically connected, via wires  34 , to a user control box  36 . The user control box  36  is, in turn, electrically connected to a plug  38 , which can be connected to a standard electrical wall socket (not shown). Generally, the user control box  36  converts the AC signal from the wall socket to a lower operating voltage for the train track  32  through the use of a transformer and related circuitry. The user control box  36  may also have buttons  38  that can be pressed to provide a positive or negative DC offset to the AC track voltage to activate a bell or horn (not shown) on the train engine  30 . This user control box  36  is merely exemplary; many other means of providing input power to the train track  32  are known in the art. For example, some control boxes known in the art are operable to receive signals from a remote control to control the input power to the train track  32 . 
   In the embodiment of  FIG. 2  a plurality of closely-spaced lights  40 , LEDs by example, are arranged in a circle surrounding the headlight of the train engine  30 . Each of the lights  40  is sequentially energized and de-energized such that the lights  40  simulate the movement of a single Mars lamp of a Mars Unit. The circuit of  FIG. 1 , of course, can be duplicated so that each of the lights has its own lamp driver  10  controlling a connector  26 . However, this is relatively expensive and space-consuming, in addition to requiring more complicated coordination between lamp drivers  10 . More desirable is the use of a single lamp driver  100  modified from the lamp driver  10  of  FIG. 1 . Several modifications to the lamp driver  10  can be incorporated into the lamp driver  100  in order for the lamp driver  100  to control the plurality of lights  40 . For example, a multiplexed signal can be sent from the processor  16  to a multiplexer (not shown), and the multiplexer can energize and de-energize each of the lights  40  through a separate lamp controller  24  and connector  26 . Alternatively, a processor with a larger number of separately controlled outputs can be used in place of the processor  16 . Other possible modifications to the lamp driver  10  are contemplated as being within the level of skill of one in the art. For example, an speed sensor can be connected to an input of the processor  16  such that the output of the processor  16  controls the lights  40  when the train engine  30  falls below a certain speed. 
   The illustration of  FIG. 2  includes a user control box  36  providing only the traditional amplitude-controlled AC voltage and imposed DC offset. However, if any trains cars engaged with the train track  32  are operable to receive and interpret other signals, such as TMCC signals, for example, the user control box  32  can be one that includes such capabilities, or one or more additional boxes can be connected to the train track  32  to provide serial communications.  FIG. 2  also highlights another feature of the lamp driver  10 / 100 . The non-volatile memory of the processor  16  can be programmed using serial communications prior to installation in a train, such as train engine  30 , to be always on, always off, or to react to a DC offset with the horn or the bell. In this way, the same circuit used with a train engine operable to receive serial communications can also be used in a train engine without such ability. In the production of such items, this flexibility is a definite benefit. 
     FIG. 2  shows lights  40 , LEDs by example, mounted in the front of the train engine  30 . Because of the size of some lights  40  commonly available, this is not a completely satisfactory design. The larger the lights  40 , the less likely the optical illusion attempted, that is, the impression that only one lamp is moving from position to position, will be successful.  FIGS. 3A and 3B  show how a lamp driver  100  controlling multiple lights  40  can be connected to those lights  40  and provide a better optical illusion with currently available components. The lights  40  are LEDs conventionally mounted on a circuit board  46  (not shown in  FIG. 3A ). Each of the lights  40  is connected to a fiber optic conductor  42 , and the fiber optic conductors are arranged in a pattern, such as a figure-eight shown in  FIG. 3A . The fiber optic conductors  42  are potted in an epoxy or acrylic  44  and surrounded by a conductor housing  46  from the figure-eight to a point where the fiber optic conductors  42  separate to surround, at least in part, the lights  40 . The epoxy or acrylic  44  can be any color such that it blends in with the housing of the train car, such as train engine  30 , supporting the figure-eight. Alternatively, smaller lights, small LEDs by example, directly mounted in the front of the model toy car also provide improved optical illusion. 
   The lights  40 , with their fiber optic conductors  42 , are also potted in an epoxy or acrylic  48 . Preferably, although not necessary depending upon the configuration, the epoxy or acrylic  48  is optically-tinted such that light from adjacent lights  40  do not affect the light received at each fiber optic conductor  42 . Such an epoxy or acrylic  48  would also provide a sturdy connection for each light  40  and its corresponding fiber optic conductor  42 .  FIG. 313  shows a partial cross-section of the lights  40  and circuit board  46 . The well-known cross-sectional details of LEDs, which are used as the lights  40 , have been left out. The circuit board  46  is preferably a printed circuit board with connections from each of the lights  40  to the multi-conductor connector  50  from the lamp driver  100 . According to the previous teachings, the lamp driver  100  generates sequential, and, in some cases, slightly overlapping, signals to each of the lights  40  through the connector  50  such that the fiber optic conductors  42  output light that mimics the appearance of one lamp moving in a figure-eight pattern. As shown by the sequence in  FIG. 4 ,  FIG. 5  and  FIG. 6 , groups of 2, 3 or more lights could be activated at a time. The next group of lights to be activated could be adjacent to the first group to be activated, or could overlap the first group. Other patterns are possible, such as the circle described with reference to  FIG. 2 . Although the description has included the lights  40  as being LEDs, any light is possible keeping in mind the space requirements of the train cars. Another design is possible, for example, using just the chips of the LEDs, without the reflectors and housings, or just with the reflectors.