Abstract:
An illumination system according to the invention includes a controller with a plurality of actuatable switches and a light board having multiple colored light emitting diodes (LEDs) which the user can control with the switches. A microcontroller is operatively connected to the switches. The microcontroller generates a modulated control signal in response to actuation of the switches. A high side driver is connected to and responsive to the modulated control signal to generate a light drive signal and the colored LEDs are selectively driven by the light drive signal.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention is related to illumination systems and more particularly to an illumination apparatus having the capability of illuminating an instrument in multiple colors. 
       BACKGROUND 
       [0002]    In the current state-of-the-art, illumination systems exist for illuminating instruments. These instruments are typically backlit with an incandescent or light emitting diode (LED) source. Such light sources have been developed for illuminating the instruments in a variety of colors. Typically, a light source of a desired color is installed into the instrument or a colored lens is utilized for achieving illumination in the desired color. Systems have also been developed in which a consumer may select between a plurality of colors using a single compound controllable light source. Such light selectable systems have been developed for new lines of instruments so that a consumer desiring a controllable selectable light source may purchase new instruments having this feature. These systems provide the consumer with the desirable feature of light color selectivity by providing a number of illumination colors, which the consumer may select. These systems however, are limited to a preset number of colors that the consumer may select between. Also, consumers are required to purchase new instruments having these features in order to achieve color selectability in illumination. It is desirable to give the consumer greater flexibility by providing a greater number of colors for illumination and it is also desirable to allow a retrofit color selectable illumination system for existing instruments eliminating the need to replace the instruments in order to achieve color selectability. 
       SUMMARY OF THE INVENTION 
       [0003]    In view of the need in the state-of-the-art, the invention provides an illumination system which includes a controller with a plurality of actuatable switches and a light board having multiple colored light emitting diodes (LEDs) which the user can control with the switches. A microcontroller is operatively connected to the switches. The microcontroller generates a modulated control signal in response to actuation of the switches. A high side driver is connected to and responsive to the modulated control signal to generate a light drive signal and the colored LEDs are selectively driven by the light drive signal. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]    The invention will now be described by way of example with reference to the accompanying figures of which: 
           [0005]      FIG. 1  is a block diagram of a multicolor illumination system according to the present invention; 
           [0006]      FIG. 2  is a diagram of a controller and light assembly according to the present invention; 
           [0007]      FIG. 3  is a schematic of a light board utilized in the system of  FIG. 1 ; 
           [0008]      FIG. 4  is a schematic of a controller utilized in the system of  FIG. 1 ; 
           [0009]      FIG. 5  is a partial timing chart showing bit timing encoding utilized in the system of  FIG. 1 ; and, 
           [0010]      FIG. 6  is a diagrammatic view of a data frame utilized in the system of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0011]    Referring first in  FIGS. 1 and 2 , the major components of the multicolor illumination system  1  will now be described. The multicolor illumination system  1  includes a controller  10 , at least one light board  20 , and a light board socket  28 . A conductor  27  connects the controller  10  to the light board socket  28 . A plurality of control buttons is included on the controller  10 . A red control button  12 , a blue control button  14  and an green control button  16  allow a user to control the light board  20  to achieve multicolor illumination as will be described below. It should be understood by those reasonably skilled in the art that while the controller  10  is shown here with three buttons, other types of control switches such as momentary or toggle switches may be utilized to achieve these functions. Similarly, while red, blue and green control buttons are shown here, it should be understood by those reasonably skilled in the art that other control schemes having different buttons such as a color up, a color down or a dimmer button, may be utilized to offer the user control over the light board  20 . 
         [0012]    The conductor  27  connects the controller  10  to the light board socket  28  and ultimately to the light board  20 . The light board socket  20  is configured to fit into an opening of an instrument which receives a standard incandescent or LED light socket, therefore making the light board  20  socket  28  a direct replacement retrofit part which may be utilized to illuminate an existing instrument. A plurality of mounting lugs  25  is provided on the light board socket  28 . It should be understood by those reasonably skilled in the art that the mounting lug arrangement and light board socket configuration may be varied to achieve a direct replacement for other socket styles. It should also be understood that the multicolor illumination system  1  is not limited to use with a socket but could be alternatively implemented without the socket utilizing any other suitable electrical interface between the controller  10  and the light board  20 . The light board  20  contains the illumination circuit  30  and the controller  10  houses the control circuit  40  shown in  FIG. 4 , which will be described below, in greater detail. 
         [0013]    The light board  20  being formed of a printed circuit board or other suitable substrate is mounted and electrically connected to the light board socket  28 . The major components mounted on the light board  20  include a microcontroller  24  and a plurality of multicolor light emitting diodes (LEDs)  22  being surface mounted thereon. A pair of contacts  21  are optionally positioned on the light board  20  to supply an electrical connection to an existing light socket which was designed for a standard incandescent bulb. This configuration advantageously allows the light board  20  to be a direct replacement for an incandescent bulb. It should be understood by those reasonably skilled in the art that while these major components are shown here as being surface mounted on to the light board  20  they can be mounted or otherwise integrated using well-known techniques. It should also be understood that other electrical interfaces are anticipated which would allow the light board  20  to fit in other socket arrangements. 
         [0014]    An exemplary embodiment of the illumination circuit  30  which includes the major components  24 ,  22  mounted on the light board  20  will now be described in greater detail with reference to  FIG. 3 . Major sections of the illumination circuit  30  include an input section  32 , a regulator section  34 , a microcontroller  24 , and a light section  36 . The input section  32  receives the output of the microcontroller U 2  from pin  2  and includes a diode D 5  connected in series with a resistor R 1 . A capacitor C 1  is connected between the diode D 5  and ground and a zener diode D 6  is connected between the resistor R 1  and ground. The resistor R 1  is connected to the VDD input of the microcontroller  24  at pin  5 . The regulator section  34  also receives the output of the controller  10  at J 1  and consists of resistors R 7  and R 8  connected in series with a zener diode D 4  which is connected between the resistors R 7 , R 8  and ground. The regulator section  34  is connected to a Vpp input of the microcontroller  24  at pin  6 . In the light section  36 , a plurality of red LEDs D 7 - 1 , D 8 - 1 , D 9 - 1 , and D 10 - 1  are connected in the red light section  36 R between the rectified output of the input section  32  and ground through resistors R 3 , R 4  and an active switch transistor Q 1 A. Similarly, a plurality of green LEDs D 7 - 2 , D 8 - 2 , D 9 - 2 , and D 10 - 2  are connected in the green light section  36 G between the rectified output of the input section  32  and ground through resistors R 2 A, R 2 B, R 1 C, R 1 D and an active switch transistor Q 1 B. Similarly, a plurality of blue LEDs D 7 - 3 , D 8 - 3 , D 9 - 3 , and D 10 - 3  are connected in the blue light section  36 B between the rectified output of the input section  32  and ground through resistors R 2 D, R 2 C, R 1 A, R 1 B and an active switch transistor Q 2 A. Each of the switch transistors Q 1 A, Q 1 B, and Q 2 A is controlled by respective outputs from pins  1 ,  3  and  4  of the microcontroller  24 . It should be understood by those reasonably skilled in the art that while each light section  36  is shown with a plurality of LEDs in this embodiment, other numbers of LEDs connected either in series or in parallel may be utilized to achieve the desired light output intensity level for each color. 
         [0015]    An exemplary control circuit  40  will now be described in greater detail with reference to  FIG. 3 . Major sections of the control circuit  40  include an input filter  42 , a power supply  44 , an illumination voltage section  46 , a microcontroller U 2 , a high side driver  48 , and the plurality of control switches SW 1 - 3 . The input filter  42  includes a 12 V input from the vehicle&#39;s ignition system fed through diode D 21  to a 12V output VBB which drives the high side driver  48  as will be described below. The filter includes an inductor L 1  connected in series with a diode D 25  for supplying input (pin  8 ) to a linear supply U 1  of the power supply  44 . Capacitor C 22  is connected to ground at a junction between the inductor L 1  and the diode D 25 . Overvoltage detection is provided through resistor R 24 , capacitor C 26 , resistor R 25  and zener diode D 24 . The power supply  44  receives the 12 V input at pin  8  and outputs a voltage, Vdd at pin  1  of approximately 5 V. The illumination voltage section  46  receives a voltage from the vehicle which is controlled through a dimmer and passes that voltage through a series parallel circuit of R 22 , R 23  and C 21  into pin  3  of the microcontroller U 2 . The high side driver  48  receives a control output in the form of a pulse width modulated signal from pin  2  of the microcontroller U 2  which is fed into pin  2  of an integrated circuit U 3 . The high side driver  48  is supplied with the voltage VBB of approximate 12 V. A 12 V pulse width modulated light drive signal is output from the high side driver  48  at pin  3  of the integrated circuit used  3  and fed through PTH 2  to J 1  of the illumination circuit  30 . The control output of the microcontroller U 2  at pin  2  is controlled by a user depressing one or more of the control switches SW 1 - 3  on the controller  10 . Switch SW 1  is actuated by the red control button  12 . Switch SW 2  is actuated by the blue control button  14 . Switch SW 3  is actuated by the green control button  16 . In an alternate embodiment, SW 1  is actuated by color up button, SW 2  is actuated by a color down button and SW 3  is actuated by a dimmer button. In this alternate embodiment a user may sweep through the color spectrum by depressing the color up (SW 1 ) or color down (SW 2 ) buttons and then adjust the light intensity of the selected color by depressing the dimmer button (SW 3 ). These control switches SW 1 - 3  shown schematically in  FIG. 3  supply momentary power to inputs DIO 1 , DIO 2  and DIO 3  of the microcontroller U 2  when depressed. In response to these inputs, the microcontroller U 2  is programmed to alter the pulse width modulated signal output at pin  2  as will be described in greater detail below. 
         [0016]    Operation of the multicolor illumination system  1  will now be described in greater detail. The system  1  receives power from the vehicle&#39;s ignition systems through the input filter  42  of the control circuit  40 . An illumination voltage section  46  provides a voltage signal from a dimmer circuit of the vehicle which is indicative of desired light output. The microcontroller U 2  receives these power and control inputs along with control inputs from control switches SW 1 - 3  which allow the user to control the amount of red, blue and green light output desired. The user is able to change or sweep through colors by depressing one or more of the red, blue or green buttons  12 ,  14 ,  16  on the controller  10 . In the alternate embodiment, the user may select colors by depressing the color up/color down buttons and then selecting intensity by depressing the dimmer button. In either case, the microcontroller U 2  generates a control signal output at pin  2 , which in this embodiment is a pulse width modulated signal having a series of data frames. The data frames are generated by the microcontroller U 2  in response to actuation of the control switches SW 1 - 3 . 
         [0017]    An exemplary data frame is shown in  FIG. 6 . Each data frame begins with a start bit followed by an 8-bit blue code, then an 8-bit red code, then an 8-bit green code, and finally an 8-bit checksum code. In this exemplary embodiment, the data frame of  FIG. 6  is encoded with a pulse width modulated signal, a portion of which is shown in  FIG. 5 . It should be understood by those reasonably skilled in the art that while the data frame is shown here as being encoded by a pulse width modulated signal, other modulation techniques are possible and within the scope of the invention. Referring to  FIG. 4 , the start bit is an approximately 1.16 ms low signal followed by the first two bits of a blue code wherein a digital 1 is represented by an 870 μs high signal followed by a 290 μs low signal and a digital 0 is represented by a 290 μs high signal followed by an 870 μs low signal. It should be understood by those recently skilled in the art that the timing of this pulse width modulated signal is merely exemplary and other timings schemes maybe used to achieve digital control. The 8-bit codes allow 256 levels for each of the blue, red and green colors. Depressing the dimmer button (SW 3 ) in the alternate embodiment, through the microcontroller U 2 , applies a multiplier to each 8-bit code therefore limiting the number of levels to some number less than 256 when the dimmer is depressed. This multiplier effectively limits the duty cycle of each code therefore driving the LEDs at a lower level. 
         [0018]    The control output signal including these data frames is then passed through the high side driver  48 , boosting the pulse width modulated signal from 0-5V to 0-12V, for driving the illumination circuit  30 . In the illumination circuit  30 , the boosted pulse width modulated light drive signal drives the active switch transistors Q 1 A, Q 1 B, Q 2 A illuminating the LEDs in the light section  36  at the desired blue, red and green levels. In this way, a user may sweep through varying shades of red, blue, green and combinations thereof by depressing the control buttons  12 ,  14 ,  16  and then stop at the desired shade upon release of the control buttons  12 ,  14 ,  16 . The pulse width modulated signal which drives the light section  36  remains unchanged in the absence of any control switch SW 1 - 3  actuation keeping the light output color constant until the user depresses one of the control buttons  12 ,  14 ,  16 . Alternatively, microcontroller U 2  can be programmed such than upon receipt of a certain control input from the control switches SW 1 - 3 , for example, simultaneously actuating SW 1  and SW 2 , it goes into a sweep mode wherein the continuously sweeps through colors by continuously altering the pulse width modulated control signal to the light section  36 . 
         [0019]    Advantageously, the system  1  allows the user to sweep through varying shades of each color using the buttons on the controller  10  until a desired color is displayed. The number of possible colors is therefore greatly increased over the currently available products. The socket and light board assembly may also be designed to be a replacement or retrofit part to replace a single color incandescent bulb on an instrument. 
         [0020]    The foregoing illustrates some of the possibilities for practicing the invention. Many other embodiments are possible within the scope and spirit of the invention. It is, therefore, intended that the foregoing description be regarded as illustrative rather than limiting, and that the scope of the invention is given by the appended claims together with their full range of equivalents.