Abstract:
A lamp that produces an infinitely variable range of time, space, and color patterns. The lamp includes a plurality of colored light sources that produce light in at least two different visual spectrums, a single modulation device that generates a modulation scheme for each of the plurality of light sources, a display screen, and a mask that masks off at least a portion of light illuminating the display screen. The generated modulation scheme is produced at a predefined intensity level. A controller selectively alters delivery of the modulation scheme to each of the plurality of light sources. A first switch allows a user to select one of a plurality of modulation schemes. A second switch allows a user to alter the predefined intensity level. A third switch allows a user to select one of a plurality of modulation rates.

Description:
PRIORITY CLAIM 
       [0001]    This application claims priority to U.S. Provisional Patent Application 61/325,220 filed Apr. 16, 2010 and is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The background and history of the use of light emitting diodes (LEDs) in color displays and lamps is extremely rich. Nonetheless, the prior art can be placed into two categories—displays and color illuminators. LED displays are typified by U.S. Pat. Nos. 4,780,621; 5,708,452; 5,836,676; 5,990,802; and 6,639,574. The inventions in these patents use individual or red-green-blue groupings of LEDs that are used as pixels to form a visual pattern of varying intensity and color. The pattern can be as simple as blinking Christmas tree lights (U.S. Pat. No. 4,780,621) or in the form of arrays that produce images as in a standard computer screen or television display. In all cases, direct viewing of the LED pixels is assumed. 
         [0003]    LED based lamps are typified by U.S. Pat. Nos. 4,777,408; 4,922,154; 5,036,248; 5,575,459; 5,752,766; 6,016,038; 6,150,774; 6,166,496; 6,567,009; 6,577,080; 6,956,338; 7,038,398; 7,064,498; 7,186,003; 7,427,840. All of these patents seek to use multiple colored LEDs to produce illumination of a specified color. That is to say they move completely away from direct viewing of individual pixels to viewing an aggregate of the combined LED outputs. Basically a color controlled version of an incandescent or fluorescent lamp. The illumination color is controlled through a variety of techniques; all are simply variations on adjusting the average current flowing through the LEDs. The most sophisticated techniques use computer control and time variations to produce pleasing visual effects. 
         [0004]    U.S. Pat. No. 7,427,840 describes the ability to produce apparent motion or spatial effects through uniformly illuminating a colored image. For example they note that the red section of an image will appear black when illuminated with green light and red under white illumination. Note that the illumination is uniform and the apparent color variations are due to the colors of the item being illuminated. Also, this inventor points out that their analysis is somewhat flawed in that inks, dyes, and paint are typically composite colors where as LED&#39;s are single colors. For example the human eye sees a dye with the combination of red and green as yellow. However, when this dye is illuminated with a yellow LED it will appear black (the dye has no actual yellow component). 
         [0005]    The LED patents to date therefore are either in the form of pixels for direct viewing or in the form of uniform color illumination. The current invention rejects both approaches in order to produce a pleasing and artistic projection lamp that produces an infinitely variable range of time, space, and color patterns. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention provides a pleasing and artistic projection lamp that produces an infinitely variable range of time, space, and color patterns. An exemplary lamp includes a plurality of colored light sources that produce light in at least two different visual spectrums, a single modulation device that generates a modulation scheme for each of the plurality of light sources, a display screen, and a mask that masks off at least a portion of light illuminating the display screen. The generated modulation scheme is produced at a predefined intensity level. 
         [0007]    In one aspect of the invention, the mask includes a pattern of light blocking material and is a diffusive, refractive or reflective surface. 
         [0008]    In another aspect of the invention, the screen is at least one of a diffusive, refractive or reflective surface. In one embodiment, the screen is cylindrical. 
         [0009]    In still another aspect of the invention, a controller selectively alters delivery of the modulation scheme to each of the plurality of light sources. 
         [0010]    In yet another aspect of the invention, a switch allows a user to select one of a plurality of modulation schemes. Another switch allows a user to alter the predefined intensity level. A third switch allows a user to select one of a plurality of modulation rates. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    Preferred and alternative examples of the present invention are described in detail below with reference to the following drawings: 
           [0012]      FIG. 1  is a diagram of an exemplary system formed in accordance with an embodiment of the present invention; 
           [0013]      FIG. 2  is an exemplary timing diagram used by the components of the system of  FIG. 1 ; and 
           [0014]      FIG. 3  is a flowchart of an exemplary process performed by the system of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0015]    A basic block diagram of the current invention is shown in  FIG. 1 . The invention includes an illuminator array  2  having a spatial array of individual LEDs with four LEDs  201 ,  202 ,  203 , and  204  being shown in this example. Said LEDs,  201 ,  202 ,  203 , and  204 , being of differing colors. Each LED  201 ,  202 ,  203 , and  204  is independently driven by a pulse width modulator (PWM)  402  with a PWM output  403  so as to adjust the LED intensity. 
         [0016]    In one embodiment the PWM  402  is contained within a microcontroller  4  such as a PIC18F4550 from Microchip Corporation. The microcontroller  4  of this sort is a combination of a general purpose microprocessor  404  and a set of peripherals, which typically includes a pulse width modulator  402  and digital input/output (DIO)  406 . Although an independent PWM could be used to drive each LED, there is an advantage to using a single PWM  402  and time-multiplexing its output through a set of AND gates  101 ,  102 ,  103 , and  104  with drive outputs  901 ,  902 ,  903 , and  904  respectively. This approach reduces the parts count and overall cost (a typical inexpensive microcontroller  4  has only one PWM  402  built in). 
         [0017]    The desired LED brightness is achieved with the single PWM  402  by overdriving the peak current from the amplifiers (AMPs)  301 ,  302 ,  303 , and  304  for the individual LEDs  201 ,  202 ,  203 , and  204  to produce a desired average current. Digital outputs (DO)  501 ,  502 ,  503 , and  504  from the microcontroller  4  are used to select which LED  201 ,  202 ,  203 , and  204  is turned on in a cyclic fashion. Selection is through use of AND gates  101 ,  102 ,  103 , and  104 . The cycle rate is chosen to be faster than the eye response rate (˜30 Hz) so that the illumination appears to be steady, without noticeable flickering. 
         [0018]    An exemplary timing diagram for a single cycle of this time multiplexing process is shown in  FIG. 2 . The on-off (logic high-logic low) state versus time for each of the corresponding digital outputs is shown in this diagram. As seen, each LED  201 ,  202 ,  203 , and  204  is selectively activated by driving one input of the corresponding AND logic gate  101 ,  102 ,  103 , and  104  high, which allows the PWM output  403  to drive the LED  201 ,  202 ,  203 , and  204  for which the corresponding AND gate  101 ,  102 ,  103 , and  104  input is high. As shown in the diagram, the duty cycle of the PWM output  403  is independently set for each LED  201 ,  202 ,  203 , and  204  being driven. 
         [0019]    The purpose of the above described circuit is to allow the intensity of each LED  201 ,  202 ,  203 , and  204  to be varied in time by an algorithm operating within the microcontroller  4 . Any equivalent circuit (e.g. one using linear drives and a digital-to-analog conversion) will suffice. Additionally, hardwired digital and analog circuits could be used to produce the desired time variations (e.g. each LED  201 ,  202 ,  203 , and  204  could be directly wired to an oscillator). However, use of a microcontroller allows new algorithms to be introduced without redesign and fabrication of new circuitry. 
         [0020]    Switches  701 ,  702 , and  703  are used to adjust the overall intensity, time variation process (algorithm) and rate of the LEDs  201 ,  202 ,  203 , and  204  as described in the flow chart description to follow. 
         [0021]    The key to the current invention is that the LED illumination ( 802  for LED  102  and  803  for LED  103  show) passes through a mask  6  and then onto a projection (display) screen  8  where it is viewed by an observer  10 . The projection screen  8  would typically be a diffusive surface (to allow viewing at all angles). The screen can be viewed in either a transmission mode (as shown) or a reflection mode (i.e. projection onto a wall). 
         [0022]    The mask  6  includes a set of mask elements  601 . The mask elements  601  may include patterns of opaque and transmissive components as exemplified in  FIG. 1 . The mask elements  601  could also include a transparent material (e.g. plastic or glass) with a light blocking material (e.g. paint) placed in a pleasing pattern on the surface. The mask elements  601  could also include refractive or reflective elements or elements (e.g. dyes) that preferentially transmit certain colors. The mask  6  could also have many layers along the optical axis or be fully three dimensional (e.g. objects embed in a clear matrix such as plastic or glass). 
         [0023]    The spacing between the individual LEDs  201 ,  202 ,  203 , and  204  in the illuminator array  2 , along with the spacing between the illuminator array  2 , mask  6 , mask elements  601  and projection screen  8  are selected such that each LED  201 ,  202 ,  203 , and  204  only illuminates limited portions or areas of the screen  8  with other portions being blocked. Two such illumination portions  12  and  13  are shown in  FIG. 1 . The spacing between the mask elements  601  is further constructed that the illuminated portions  12  and  13  will overlap  15  to a desired degree. 
         [0024]    An example for two illuminated portions  12  and  13  from LED  202  and LED  203  respectively is shown in  FIG. 1 . The areas of illuminated portions  12  and  13  that do not overlap will appear as the base color of the LED  202  and  203  respectively, in this example red from LED  202  and blue from LED  203 . The area in which illuminated portions  12  and  13  overlap  15  will appear to the eye as a combined color, purple, even though purple is not one of the LED colors. Changing the relative intensities for LED  202  and LED 3   203  will shift the combined color from pure red through purple to pure blue. In addition an apparent motion of the illuminated portion will occur as one LED is dimmed and another made brighter. Use of multiple LEDs (e.g.  201 ,  202 ,  203 , and  204  shown) and multiple mask elements  601  will produce multiple areas of overlap of differing colors. Modulation of the LED intensities with a time varying sequence will cause all the colors to shift and apparent motion to occur. 
         [0025]    Examples of time sequences include:
       Each LED  201 ,  202 ,  203 , and  204  having a sine wave modulation with different phases   Each LED  201 ,  202 ,  203 , and  204  have a sine wave modulation, each with different frequency   A pseudo-random modulation sequence   Triangle modulation with different phases and frequencies   Response to an audio or video signal   Basically any set of time varying electrical signals that produce relative variations of the illumination intensity from the LEDs  4 .       
 
         [0032]    Note that the illuminator array  2 , mask  6  and screen  8  are shown as planar in  FIG. 1  in order to simplify the drawing. All of these components can be formed into any desirable geometric shape and all can be  3  dimensional. Example images may be produced with a cylindrically shaped mask  6  and screen  8 . Variations can include shapes such as Christmas trees, stars, space shuttles, etc. 
         [0033]      FIG. 3  is a software flow diagram for the basic firmware in the microprocessor  404 . The firmware flows through an endless loop where-in for each of the N LEDs
       1. An overall intensity (average intensity) for all the LEDs is set   2. An updated individual modulation intensity for the current modulation process for the ith LED is calculated   3. The PWM duty cycle for the i th  LED is set as the product of the average and individual modulation intensities   4. DIO for the i th  LED is selected to turn it ON   5. The i th  LED remains ON for a time T   6. During this time the switches are polled to determine if any have been switched   7. Loop through all N LEDs   8. Loop back through endless While loop       
 
         [0042]    As a specific example, let the time variation process be a sine wave with unique frequency F(i) for the i th  LED
       1. The average intensity is set at 75% of full scale   2. The next individual modulation intensity for the i th  LED based on the next step in a sine wave at F(i) is calculated from the previous steps via standard numerical methods.   3. The PWM(i) is scaled and set as the product of the average and individual modulation intensities   4. The i th  LED is then turned on via DIO   5. The state is held stationary (LED(i) is on) for a time T during which the state of the switches is polled.   6. All LEDs are looped through   7. Process is repeated       
 
         [0050]    Pressing switch  701  causes the average intensity to change. In this simple arrangement it is assumed that the microprocessor  404  is preprogrammed with a set of average intensity levels (e.g. 100%, 75%, 50%, 25%) and pressing switch  701  cycles through these levels. 
         [0051]    Pressing switch  702  causes a new modulation sequence (as described in above) to be selected for step two. For example a sine wave sequence may be changed to a triangle wave sequence. In this arrangement it is assume that the microprocessor  404  is preprogrammed with a set of modulation sequences and pressing switch  702  cycles through the sequences. 
         [0052]    Pressing switch  703  causes the timing rate to change by changing the While loop time period, T. The time period T sets the modulation speed. In this simple arrangement it is assume that the microprocessor  404  is preprogrammed with set of values of T and pressing switch  703  cycles through those values. 
         [0053]    It can be appreciated that more complex control of these three variables is possible. 
         [0054]    In one embodiment, the mask  6  includes a rectangular array of holes that are located behind the display screen  8  that is curved. In another embodiment, the mask  6  includes a ‘crazy quilt’ array of holes. In another embodiment, the mask  6  includes artistically painted mask. 
         [0055]    While the preferred embodiment of the invention has been illustrated and described, as noted above, many changes can be made without departing from the spirit and scope of the invention. For example, light sources other than LEDs may be used, such as incandescent lamps and colored filters may be used on a larger scale device. Accordingly, the scope of the invention is not limited by the disclosure of the preferred embodiment. Instead, the invention should be determined entirely by reference to the claims that follow.