Patent Publication Number: US-2005134529-A1

Title: Color changing segmented display

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The invention relates to segmented displays wherein displayed letters, numbers, etc. are composed of illuminated segments. The invention also relates to digital clock devices and digital timer devices that often employ these segmented displays.  
      2. Background Art  
      The use of segmented displays has become widespread. A typical segmented display includes a plurality of segments. The segments are controlled on an individual basis to allow selective illumination of segments on the display to provide any desired illumination pattern composed of illuminated segments.  
      These segmented displays are often used in digital clocks and timers to display time. Digital clocks sometimes use additional segments for displaying other information such as month, date, day of week, humidity and temperature, etc.  
      Traditionally, the illuminated segments produce a simple display that indicates the current time or other information. In some existing applications, a manual dimming switch has been provided to provide a bright mode and a dim mode for the display. In a typical approach, each illuminated segment is illuminated by one or more light emitting diodes (LEDs).  
      Background information may be found in U.S. Pat. Nos. 5,008,595; 3,481,062; 6,628,249; 6,431,719; 6,639,574; 6,588,132; 6,599,033; 4,870,325; 6,097,367; 4,724,629; and 6,288,696.  
     SUMMARY OF THE INVENTION  
      It is an object of the invention to provide an improved segmented display wherein the illuminated segments provide a dynamic display that creates a color changing effect in various segments when displaying the current time or other information.  
      In carrying out the invention, a segmented display is provided. The segmented display comprises a display including a plurality of segments, and a controller that drives the segments. The controller drives the segments on an individual basis to allow selective illumination of segments on the display to provide the desired illumination pattern with the illuminated segments. Each segment includes a light emitting device arrangement operative to produce a plurality of colors. The segments are driven to produce a dynamic display that creates a color changing effect in various segments when displaying the desired illumination pattern.  
      The segmented display may be used in a digital clock or timer to display time. Additional segments may be used for displaying other information such as month, date, day of week, humidity, and temperature, etc. The light emitting device arrangements are preferably made up of light emitting diodes (LEDs).  
      At a more detailed level, the invention comprehends a light emitting diode (LED) type segmented display. The display includes clusters of LEDs. Each cluster includes LEDs with different colors. Each segment of the LED display includes one or more clusters of LEDs. LEDs may be arranged into different channels. Each channel contains a group of LEDs with one or more colors depending on the application. A microcontroller controls the mixing of different color LEDs at each cluster when driving the segments to generate hundreds of colors and dynamic color change effects in various segments. The microcontroller drives the segments on an individual basis to allow selective illumination of segments on the display to provide the desired illumination pattern with the illuminated segments, while the segments are driven in a manner to produce a dynamic display that creates a color changing effect when displaying the desired illumination pattern.  
      It is appreciated that mixing of different color LEDs at each cluster may be achieved in a variety of ways. Several embodiments are contemplated. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is an LED display for a simple LED alarm clock of the invention;  
       FIG. 2  is an LED display for a multi-feature LED alarm clock of the invention;  
       FIG. 3  illustrates a direct drive LED display circuit;  
       FIG. 4  illustrates a duplex LED display circuit;  
       FIG. 5  illustrates a multiplex LED display circuit;  
       FIG. 6  illustrates a seven segment display and an associated direct drive display circuit as well as the connection to the microcontroller for driving the segments;  
       FIG. 7  illustrates a seven segment display and an associated duplex display circuit as well as the connection to the microcontroller for driving the segments;  
       FIG. 8  is a block diagram illustrating the implementation of the direct drive LED display circuit with an LED display; and  
       FIG. 9  is a block diagram illustrating the implementation of the multiplex LED display circuit with an LED display. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      In  FIG. 1 , an LED display  10  for a simple LED alarm clock includes a plurality of segments  12 . A microcontroller drives the segments  12  on an individual basis. With each segment  12  driven on an individual basis, selective illumination of segments  12  on display  10  provides any desired illumination pattern with the illuminated segments. Each segment  12  includes a light emitting device arrangement that is driven when the segment is driven by the microcontroller. The microcontroller drives the light emitting device arrangements within the segment to be illuminated in such a way to produce a dynamic display that creates a color changing effect in each illuminated segment. The light emitting arrangements are preferably made up of LEDs. In this way, each segment  12  of the LED display  10  includes one or more clusters of LEDs to illuminate that segment. Each LED cluster includes LEDs of different colors. Driving LEDs of different colors in the same segment  12  with varying signals creates the color changing effect.  
      More particularly, when the controller drives a particular segment, the controller drives each cluster in that segment by varying the brightness of each LED gradually from dim to bright and from bright to dim. When the LEDs are different colors, this can be performed to create a color changing effect for the segment. It is appreciated that the mixing of different color LEDs at a cluster to produce the color changing effect may be achieved in a variety of ways. For example, the LED display may include one or more channels depending on the application. Each segment may include one or more separate connections to the microcontroller depending on the application. The brightness of any particular LED may be controlled in any suitable way such as by varying an analog signal or using a digital timing pulse.  
      In  FIG. 2 , an LED display  14  for a multi-feature LED alarm clock is illustrated. Of course, clocks and timers are suitable implementations of the invention but the invention may be applied to any segmented display.  
      The LEDs inside the displays  10  and  12  may be arranged into one channel, two channels, or any other number of channels depending on the driving method. Each channel contains a group of LEDs. The group of LEDs for a channel may be connected in a common anode arrangement or a common cathode arrangement depending on the application. A channel may contain a single color of LEDs or may contain LEDs of multiple colors depending on the application.  
       FIG. 3  illustrates a direct drive LED display circuit  20 . Circuit  20  contains a group of LEDs  22  in a single channel. The single channel contains LEDs of multiple colors. In this way, the channel group of LEDs may include various clusters  24  of LEDs. Each cluster  24  may contain two or more LEDs with each cluster  24  including LEDs of multiple colors. In this way, one or more clusters  24  are associated with each segment  12  such that each segment  12  is associated with LEDs of multiple colors to allow driving of the segment  12  in a way that produces the desired color changing effect.  
       FIG. 4  illustrates a duplex LED display circuit  30 . Circuit  30  contains LEDs  32  and  34  arranged in two channels. As shown, each channel contains LEDs of a single color or multiple colors. The first channel includes LEDs  32  while the second channel includes LEDs  34 . In this way, the LEDs may compose various clusters  36  of LEDs. Each cluster  36  may contain two or more LEDs with each cluster  36  including LEDs of multiple colors. In this way, one or more clusters  36  are associated with each segment  12  such that each segment  12  is associated with LEDs of multiple colors to allow driving of the segment  12  in a way that produces the desired color changing effect.  
       FIG. 5  illustrates a multiplex LED display circuit  40 . Circuit  40  contains LEDs  42  arranged in four channels. As shown, each channel contains LEDs of a single color or multiple colors. In this way, the LEDs may compose various clusters  44  of LEDs. Each cluster  44  may contain two or more LEDs with each cluster  44  including LEDs of multiple colors. In this way, one or more clusters  44  are associated with each segment  12  such that each segment  12  is associated with LEDs of multiple colors to allow driving of the segment  12  in a way that produces the desired color changing effect.  
       FIG. 6  illustrates a seven segment display with seven segments  50  and an associated direct drive display circuit with all diodes on a single channel  52 . Each segment  50  includes a first diode  54  of a first color and a second diode  56  of a second color. The first and second diodes  54  and  56 , respectively, connect to the microcontroller (MCU/DRIVER) as indicated.  
      In this direct drive LED display of  FIG. 6 , two LEDs with different colors are placed within each segment  50 . Alternatively, more than two LEDs can be placed within one segment. There are two methods to make each segment change its color. In a first approach, a digital timing pulse is utilized. The single channel is connected to the positive supply voltage and each LED is connected to the MCU/DRIVER, the MCU/DRIVER will output a chain of timing pulses to control the brightness and also the on/off of each LED. In this way, a color changing effect is realized. In the second approach, analog control is utilized. The single channel is connected to the positive supply voltage and each LED is connected to the MCU/DRIVER, the MCU/DRIVER will output an analog signal to control the brightness and also the on/off of each LED to perform the color mixing function.  
       FIG. 7  illustrates a seven segment display with seven segments  70  and an associated duplex display circuit with the diodes on two channels  72  and  74 . First channel  72  includes diodes  76 , while second channel  74  includes diodes  78 . Each segment  70  includes a first diode  76  of a first color and a second diode  78  of a second color. The first and second diodes  76  and  78 , respectively, connect to the microcontroller (MCU/DRIVER) as indicated.  
      In this duplex drive arrangement two LEDs with different colors are placed within each segment  70 . Also, there are two methods to make each segment change its color. In the first approach, a digital timing pulse is utilized. The first and second channels of the display are connected to the MCU/DRIVER channel control port, and then the two LEDs of each segment  70  are grouped together (or each LED) and connected to the MCU/DRIVER segment control port. The MCU/DRIVER will output different timing signals to both ports to control the brightness and on/off of each LED. In the second approach, analog control is utilized. The channels of the LED display are connected to the MCU/DRIVER channel control port, then the two LEDs are grouped together (or each LED) and connected to the MCU/DRIVER segment control port. The MCU/DRIVER will output an analog signal to each channel and output a timing signal to the segments of the LED display to control the brightness and on/off of each LED to perform the color mixing function.  
       FIG. 8  is a block diagram illustrating the implementation of the direct drive LED display circuit with an LED display. Input device  86  controls the run/stop of the color mixing of the LEDs and enters the required information for display. The display itself is indicated at  80 . The microcontroller unit (MCU)  82  outputs signals through the segment control port to generate timing patterns and control the brightness of the LEDs to achieve color mixing. Driver circuit  84  actually drives the LEDs although if the driving capability of the MCU is sufficient then the driver circuit  84  may be omitted. Either of the two approaches (digital timing pulse or analog) may be taken to make each segment change its color.  
       FIG. 9  is a block diagram illustrating the implementation of the multiplex LED display circuit with an LED display. Input device  96  controls the run/stop of the color mixing of the LEDs and enters the required information for display. The display itself is indicated at  90 . The microcontroller unit (MCU)  92  outputs signals through the segment control port and channel control port to generate timing patterns and control the brightness of the LEDs to achieve color mixing. Driver circuit  94  actually drives the LEDs although if the driving capability of the MCU is sufficient then the driver circuit  94  may be omitted. Either of the two approaches (digital timing pulse or analog) may be taken to make each segment change its color.  
      While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention.