Abstract:
The thermostat includes a housing having at least a portion thereof illuminated by a light that changes color via a manual input. The light illuminates the display for easy readability while the variable color of the light allows a user to match the appearance of the thermostat to best complement the surrounding décor. User input elements provide for the manual adjustment of one or more characteristics of the light, such as visible color of the light. The light source comprises at least one LED for displaying a plurality of colors. In this case, to change the color of the light illuminating the translucent portion of the housing or backlighting the display, electronics within the thermostat control the drive signals to the LED in order to operate the LED to provide the desired color. The invention also contemplates filtering the light and manually adjusting the filtering to provide the desired aesthetics.

Description:
RELATED APPLICATIONS 
       [0001]    This application is related to U.S. application Ser. No. 10/897,909, filed Jul. 23, 2004, which is hereby incorporated by reference in its entirety for everything that it teaches. 
     
     FIELD OF THE INVENTION 
       [0002]    This invention relates to heating, ventilation and air conditioning (HVAC) systems, and more particularly to a thermostatic control unit, such as a wall mounted thermostat, or a temperature indicating device such as a thermometer, or other types of temperature responsive devices of the type used in HVAC systems. 
       BACKGROUND OF THE INVENTION 
       [0003]    Most HVAC systems that provide temperature control of architectural spaces (e.g., a room) include thermostatic controllers or thermostats mounted on the walls of the spaces for sensing and controlling the temperatures of the spaces. Such thermostatic controllers typically include an internal temperature sensitive element for sensing the temperature of the space, an input element for receiving an input designating a desired temperature, and a dial or digital display of the thermostat&#39;s operating conditions. Usually the temperature sensing element is housed in the thermostat but it may also be external to the housing and remotely located. A typical controller or thermostat also includes output elements such as relays, switches, or electronic drive circuits for sending control signals to the HVAC system. 
         [0004]    Sometimes, the mechanical or digital display of the thermostatic controller is illuminated so that the display is more easily read. Although illuminating the display facilitates operation of the thermostat, the relatively small size of the thermostat dictates correspondingly small text in the display, which often requires users to stand very close to the thermostat in order to read the displayed information. 
         [0005]    Prior approaches to make the information in the displays more easily readable have often been at the expense of aesthetics. Permanently illuminated displays are distracting and are generally totally utilitarian in appearance. Moreover, having a lighted display with numerals and/or text big enough to be easily viewed by those with impaired vision is generally neither practical nor aesthetically pleasing. For example, large numerals and/or text require a large display, which requires a large housing. Since a thermostat is typically mounted to a wall in a room, the large housing compromises the aesthetics of the room&#39;s decorations. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    The invention provides a thermostat that both provides an easily readable display while at the same time presents an appearance that is aesthetically pleasing and complements the décor of the architectural space it controls. To accomplish this goal, the thermostat includes a housing having at least a portion thereof illuminated by a light that changes color via a manual input. The light illuminates the display for easy readability while at the same time the variable color of the light allows for a user to match the appearance of the thermostat to best complement the décor of the space whose temperature it controls. 
         [0007]    In one embodiment, visual characteristics of light radiating outwardly from within a thermostat&#39;s housing are manually adjusted. Preferably, at least a portion of the housing is translucent to the light. User input elements provide for the manual adjustment of one or more characteristics of the light. Among the manually adjustable characteristics of the light radiating from the light source is visible color of the light. 
         [0008]    Preferably, the light source comprises at least one light emitting diode (LED) for displaying a plurality of colors. In this case, to change the color of the light illuminating the translucent portion of the housing or backlighting the display, electronics within the thermostat control the drive signals to the LED in order to operate the LED to provide the desired color. In this regard, most LEDs today provide limited variable color and offer only a simple selection among red, green, and blue. However, in order to expand the available colors, the electronics of the thermostat can drive the LEDs differently to change the hue, brightness, and saturation of each of the red, green, and blue so as to provide virtually a full spectrum of possible colors. In addition to individually changing the hue, brightness, and saturation of each of the red, green, and blue LED elements, the electronics can simultaneously activate more than one color element in order to further expand the reproducible spectrum of colors. 
         [0009]    Instead of controlling light emitted from light sources electronically, the invention also contemplates filtering the light and manually adjusting the filtering to provide the desired aesthetics. For example, a manually adjustable color wheel filter may cooperate with a light source of unchanging spectrum. Or a variable polarizing filter may cooperate with the light source. 
         [0010]    Other aspects, objectives and advantages of the invention will be apparent from the following detailed description and the accompanying drawings. 
     
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
         [0011]      FIG. 1  illustrates an exemplary environment for a thermostat according to the invention; 
           [0012]      FIG. 2  is an exemplary embodiment of a thermostat having the features of the invention, where a partially translucent housing and a display are colored by variable lighting sourcing from a location internal to the thermostat; 
           [0013]      FIG. 3  is a schematic diagram of the internal space of an embodiment of the thermostat shown in  FIG. 2 , illustrating separate variable light sources illuminating the housing and backlighting the display; 
           [0014]      FIG. 4  is a schematic diagram of the internal space of an embodiment of the thermostat shown in  FIG. 2 , illustrating separate variable light sources illuminating the housing and backlighting the display as in  FIG. 3  but where the light sources include banks of discrete color LEDs; 
           [0015]      FIG. 5  is a schematic diagram of the internal space of another embodiment of the thermostat shown in  FIG. 2 , illustrating a common variable light source illuminating both the display and the housing; 
           [0016]      FIG. 6  is a schematic diagram of the internal space of an embodiment of the thermostat shown in  FIG. 2 , illustrating a common variable light source illuminating both the display and the housing as in  FIG. 5  but where the light source includes a bank of discrete color LEDs; 
           [0017]      FIG. 7  is schematic diagram of the internal space of yet another embodiment of the thermostat shown in  FIG. 2 , illustrating a variable color filter for varying the characteristics of a light source in the thermostat and a light pipe for distributing the light from the source of light throughout at least a portion of the housing; 
           [0018]      FIG. 8  is schematic diagram of the internal space of still another embodiment of the thermostat shown in  FIG. 2 , illustrating a variable color filter and a light pipe as in  FIG. 7  but with the color filter adjusting only the color of the light emitted from the light pipe; 
           [0019]      FIG. 9  is a schematic diagram of the internal space of a further embodiment of the thermostat shown in  FIG. 2 , illustrating a polarizing filter for adjusting the visible color of the light emitted by the source of light; and 
           [0020]      FIG. 10  is a schematic diagram of the internal space of another embodiment of the thermostat shown in  FIG. 2  where the light source includes a plurality of electroluminescent tubes for displaying multiple colors. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0021]      FIGS. 1-3  show a first embodiment of a thermostat, according to the invention, in a form of a wall mounted thermostat  50 . Referring to  FIG. 2 , the thermostat,  50  includes a variable source of light  76  ( FIG. 3 ) within a housing  54  with at least a portion  62  of the housing  54  being translucent to the light radiating outwardly from the light source  76  and illuminating at least the portion  62  of the housing  54 . Alternatively, the entire housing  54  is translucent to the light emitted from its interior. As shown in  FIG. 2 , the thermostat  50  further includes user input elements  56  for manually adjusting one or more characteristics of the light. The user input elements  56  are disposed within a housing  54  and, in this embodiment, comprise a plurality of buttons  56   a ,  56   b ,  56   c ,  56   d , and  56   e . In other embodiments, user input elements  56  include a touchpad, a touch screen, or other conventional user input devices and combinations thereof. The thermostat  50  further includes a display  60  for displaying the present and desired temperatures and graphic user interface options. Additionally, the thermostat  50  includes a plurality of status light emitting diodes (LEDs)  64  for displaying the active thermostat operating mode. 
         [0022]    Referring to  FIG. 3 , to control the operation of the HVAC system, the processor  68  receives a desired temperature input Td from the user input elements  56 . The temperature sensor  58 , in turn, senses the present room temperature of the space and provides a signal Tp, indicative of the present room temperature, to the processor  68 . The processor  68  compares the present room temperature to the desired room temperature, and causes the output driver circuit  70  to generate an output signal  72  for controlling a heating, ventilating and air conditioning system in a conventional manner. A suitable example of processor  68  is model ATMEGA 16 from Atmel. In further embodiments, a different processor may be used, such as one capable of receiving inputs indicative of the desired and present temperatures for controlling an HVAC system and having the capability of controlling the characteristics of at least one source of light via a manually adjustable user input. 
         [0023]    Preferably, visible color of the light is among the manually adjustable characteristics of the light radiating from the light source  76 . As illustrated in  FIG. 1 , when a thermostat is visible from a location which contains items of a user&#39;s décor, a user may wish to adjust the thermostat color in order to complement the colors within the room  52 , such as those of a wall  53  or furniture  51 , for example. Other manually adjustable characteristics of the light radiating from the light source  76  include duration of the light, such as whether the light is activated permanently or only temporarily, as well as the overall intensity of the light to accommodate for various ambient lighting conditions. 
         [0024]    As further shown in  FIG. 3 , the thermostat  50  comprises a source of light  76  for generating a light inside the thermostat  50 . Preferably, the light source  76  comprises at least one light emitting diode for displaying a plurality of colors. In this embodiment, the light source  76  includes two separate variable light sources comprising LEDs  76   a  and  76   b  that, respectively, illuminate the housing  54  and backlight the display  60 . Referring again to  FIG. 3 , the thermostat  50  also includes a light pipe  66  connected to the light source  76   a  for distributing the light emitted by the LED  76   a  throughout the housing  54  and thus illuminating the translucent portion  62 . 
         [0025]    The LEDs  76   a  and  76   b  are tri-color LEDs capable of emitting multiple colors, such as red, blue, and green from a single enclosure. Suitable examples of tri-color LEDs are models M500RGB4D from Lighting Components LED Corporation and RL5-RGB from Super Bright LEDs, Inc. However, it should be recognized by a person skilled in the art that other embodiments may include different tri-color, bi-color, or other multi-color LEDs having the capability of emitting multiple colors from a single LED enclosure. Alternatively, in another embodiment, shown in  FIG. 4 , the light source  86  includes two separate light sources  86   a  and  86   b , wherein each light source  86   a ,  86   b  is comprised of a bank of discrete color LEDs selected for their opposing hues, such as red, green, and blue. Suitable examples of discrete color LEDs are models RL5-R3545, RL5-G8045, and RL5-B2545 from Super Bright LEDs, Inc. 
         [0026]    To adjust the characteristics of the light emitted by the light sources  76   a ,  76   b  ( FIG. 3) and 86   a ,  86   b  ( FIG. 4 ), a user preferably provides the desired characteristic to the processor  68  through the user input elements  56  by choosing the corresponding option within the processor&#39;s  68  graphic user interface presented on the display  60 . When the desired characteristic is color of the light illuminating the translucent portion  62  or backlighting the display  60 , the processor  68  activates the appropriate color within the multi-color LEDs  76   a ,  76   b  or discrete LED banks  86   a ,  86   b . In order to expand the color choices from the basic red, green, and blue, the processor  68  is capable of providing a virtually full spectrum of colors by simultaneously activating more than one color element, while individually changing the hue, brightness, and saturation of the activated color elements within each tri-color LED  76   a ,  76   b  or discrete LED banks  86   a ,  86   b.    
         [0027]    In the embodiments illustrated in  FIGS. 3 ,  4 , a user has separate control over the color of the backlighting and illumination of the translucent portion  62  of the housing  54  because the thermostat  50  includes separate variable light sources  76   a ,  76   b  ( FIG. 3) and 86   a ,  86   b  ( FIG. 4 ). Other embodiments, as illustrated by  FIGS. 5 and 6 , for example, include a single light source providing the source of light for both backlighting the display  60  and illuminating the housing  54  through connection to the light pipe  66 . As illustrated in  FIG. 5 , the light source  96  includes a single multi-color LED capable of emitting a plurality of colors from a single enclosure. Alternatively, as shown in  FIG. 6 , the light source  106  includes a bank of three discrete LEDs selected for their opposing hues and connected in parallel to the light pipe  66 . Thus, in  FIGS. 5 and 6 , a user&#39;s selection of the desired characteristic of the light via user input elements  56  adjusts the corresponding characteristic of both the backlight for the display  60  and the light passing through the housing  54 . 
         [0028]    Additional embodiments depicted in  FIGS. 7-10  illustrate alternate ways of providing the desired aesthetics by manually adjusting the color of the light emitted by the light sources  116  ( FIG. 7 ),  126  ( FIG. 8 ),  136  ( FIG. 9 ), and  146  ( FIG. 10 ). For example, in  FIGS. 7 and 8 , light sources  116 ,  126  comprise a bank of single color, or monochromatic, LEDs which do not have color changing capability. Hence, a color wheel is used to filter the light from the light sources  116 ,  126  in order to manually adjust the color of the light illuminating the housing  54  ( FIG. 8 ) and, optionally, the color of the light backlighting the display  60  ( FIG. 7 ). The color wheel filters of  FIGS. 7 ,  8  include a plastic translucent material divided into a plurality of segments comprised of multiple colors. When it is desired to adjust the color of the observed light, a user manually turns the portion of the color wheel  118 ,  128 , which is accessible from an external surface of the housing  54 , until the desired colored segment of the color wheel  118 ,  128  covers the light source  116 ,  126 . 
         [0029]    In yet another embodiment, illustrated in  FIG. 9 , the color of the light emitted by a monochromatic light source  136  is changed by passing through a variable polarizing filter  138 . The polarizing filter  138  includes material, such as calcite, exhibiting birefringence qualities and being disposed between two polarizing elements to produce a color shift of the light originating from the light source  136 . The user adjusts the color of the light by manually varying the relative positions of the polarizing elements via a lever  139 . The lever  139  is accessible from an external surface of the housing  54 . 
         [0030]    In a further embodiment, shown in  FIG. 10 , the light source  146  includes a plurality of electroluminescent light sources, such as electroluminescent tubes  146 R,  146 G,  146 B, for example, wherein the colors of sources  146 R,  146 G,  146 B are selected for their opposing hues. In this embodiment, as in  FIGS. 3-6 , the user adjusts the color of the light emitted by the light source  146  by providing the desired color characteristic to the processor  68  through the user input elements  56 . The processor  68 , in turn, activates the appropriate light source  146 R,  146 G, and  146 B, either individually or simultaneously, while individually changing the hue, brightness, and saturation of each activated light source  146 R,  146 G, and  146 B. 
         [0031]    The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) is to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention. 
         [0032]    Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.