Abstract:
A power supply switch for a dual powered thermostat switches the power supply to a dual-powered thermostat with a touch-screen display when a change in primary power supply is detected. The switch switches to an auxiliary power supply. The auxiliary power supply can be a battery.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/943,223, filed Jun. 11, 2007. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not Applicable 
       THE NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT 
       [0003]    Not Applicable 
       INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC 
       [0004]    Not Applicable 
       BACKGROUND OF THE INVENTION 
       [0005]    1. Field of the Invention 
         [0006]    The invention relates to power supplies for digital thermostats. 
         [0007]    2. Description of the Related Art 
         [0008]    Thermostats for controlling climate control systems generally fall into two broad categories: (1) mechanical thermostats and (2) electronic digital thermostats. A typical mechanical thermostat, such as for a multi-stage thermostat application, is connected to an alternating current (AC) power supply, normally a transformer. However, mechanical thermostats do not require continuous electrical power. On the other hand, a typical digital thermostat, such as one that is multi-stage, requires continuous power for thermostat components such as a microcomputer and thermostat control circuit. These component parts require power at all times. Therefore, digital thermostats need additional connections to a power supply, such as a transformer, to satisfy these power requirements. 
         [0009]    Thus, when replacing a mechanical multi-stage thermostat with a digital multi-stage thermostat, an additional wire is usually required to power and maintain operation of the digital thermostat. When replacing a first digital thermostat with another digital thermostat, the additional power connection wire is normally present. 
         [0010]    When installing a digital thermostat for a new application, such as when building a new house, providing continuous power for the digital thermostat by adding the necessary extra power wire is relatively easy. However, in retrofit applications, and specifically, when replacing a mechanical thermostat with a digital thermostat, providing an additional wire for electrical power can be difficult, time consuming and costly. 
         [0011]    Therefore, what is needed is a digital thermostat having multiple power capabilities that is adapted for both new installations and for retrofit installations (when an external power supply is not available, because all necessary connections are not present). 
         [0012]    Power supplies with switches to supply backup power to digital thermometers exist. In prior-art circuits, the switch always produces a “seam” because of the lack of voltage detecting. This seam can lead to instability or reset of the system. 
         [0013]    Prior-art switches are not able to switch to an internal power supply when a drop in an overhigh supply voltage occurs. 
         [0014]    Prior-art switches without voltage detection decrease battery performance and lifespan. 
         [0015]    Another problem with prior-art thermostats is that programming them can be complicated and time consuming. 
       BRIEF SUMMARY OF THE INVENTION 
       [0016]    It is accordingly an object of the invention to provide a power supply used in the dual powered thermostat controller that overcomes the above-mentioned disadvantages of the heretofore-know devices and methods of this general type. 
         [0017]    With the foregoing and other objects in view there is provided, in accordance with the invention, a switch assembly for switching a digital thermostat from a primary power supply to an auxiliary power supply. The switch assembly includes a switch and voltage detector. The switch connects to a digital thermostat and alternatively to a primary power supply having a voltage and an auxiliary power supply. The auxiliary power supply can be a battery, generator, solar panel, separate electrical line, or other backup power source. 
         [0018]    The voltage detector signals the switch to connect the digital thermostat to the auxiliary power supply when a change in the voltage of the primary power supply is detected. By detecting a change in voltage, the voltage detector can make the switch before the power is actually interrupted. Likewise, changes in voltage will cause a switch to occur to protect the system even when the primary power source has an overhigh supply voltage. 
         [0019]    In accordance with a further object of the invention, a power supply for preventing a power interruption in a primary power supply from affecting a digital thermostat is encompassed by the invention. The power supply includes the switch assembly discussed previously as well as the auxiliary power supply. 
         [0020]    In accordance with a further object of the invention, a digital thermostat assembly with backup power supply is taught. The digital thermostat is similar to the power supply and switch assembly discussed previous but also includes a digital thermostat. 
         [0021]    The invention further encompasses a programmable thermostat with a touch screen interface. The programmable thermostat is designed to control building air conditioning, heating, or ventilation equipment for home or building. The touch screen interface displays equipment sunning status and allows users to review the setting, monitor the system running status, and program the thermostat. 
         [0022]    To ease programming, the invention includes a user-friendly designed touch-screen thermostat. The touch-screen thermostat comes with a menu-driven interface that allows the user or the installer to easily configure the system and program the running sequence for air-conditioning, heating, and ventilation equipment for home or commercial building. The thermostat displays previous settings and running status of all the connecting equipments. The installer or user can easily monitor the system and change system setting through a menu-driven touch screen interface. 
         [0023]    Other features which are considered as characteristic for the invention are set forth in the appended claims. 
         [0024]    Although the invention is illustrated and described herein as embodied in a power supply switch for dual powered thermostat, a power supply for dual powered thermostat, and a dual powered thermostat, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. 
         [0025]    The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0026]      FIG. 1  is a schematic view of a block diagram of the power supply and switch for a digital thermostat. 
           [0027]      FIG. 2  is a circuit diagram of the voltage detector and the switch. 
           [0028]      FIG. 3  is a front side view of a digital thermostat according to the invention with the display activated. 
           [0029]      FIG. 4  is a front side view of a mounting plate of the digital thermostat. 
           [0030]      FIG. 5  is a rear side view of the digital thermostat. 
           [0031]      FIG. 6  is a front side view of the digital thermostat with the screen deactivated. 
           [0032]      FIG. 7  is a right side view of the second embodiment of the digital thermostat, which is a mirror image of the left side of the thermostat. 
           [0033]      FIGS. 8-9  are front side views of a display for a digital thermostat. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0034]    Referring now to the figures of the drawing in detail and first, particularly, to  FIG. 1  thereof, a circuit for automatic switching a digital thermostat from external power to internal power is shown. A voltage detecting unit is included in the circuit. The voltage detector is connected to a switch for switching the thermostat to internal power when the external power&#39;s voltage begins to drop. In a preferred embodiment, the internal power supply is a battery. 
         [0035]    The switch changes to the internal power supply when the switch detects a that the voltage has fallen below a preselected threshold. By checking the decrease, as opposed to the absence of voltage, seams are avoided. Switching voltage sources upon detecting a voltage drop decreases system instability and avoids system resets. 
         [0036]    The switch also solves the problem of overhigh voltage drop by including a diode such as a Zener diode. 
         [0037]    The switch by avoiding resets and overhigh voltage drops can improve the battery performance and battery life span. 
         [0038]    Referring now to the figures of the drawing in detail and first, particularly, to  FIG. 1  thereof, a circuit  30  for automatically switching a digital thermostat  35  from an external power source  31  to an internal power source  34  is shown. The external power source is preferably a twenty-four Volt Alternating Current (24Vac) source. The internal power source  34  is preferably two AA batteries connected in series. A voltage detector  32  is disposed between the external power source  31  and the power supply switch  33 . The voltage detector  32  is connected to a switch  33  for switching the thermostat  35  to the internal power source  34  when the voltage of the external power supply  31  drops too quickly. 
         [0039]    The switch  33  changes to the internal power supply  34  when the voltage detector  32  detects that a voltage of the external power source  31  has fallen below a preselected voltage. By switching when there is still a voltage, albeit a decreased voltage, as opposed to after an absence of voltage, seams are avoided. The system is switched to the internal power source  34  before there is no voltage. Accordingly, system instabilities and resets are avoided. 
         [0040]      FIG. 2  shows an electrical circuit diagram of the circuit  30 . A diode D 18  prevents overhigh voltage. 
         [0041]      FIG. 2  shows the circuit operating in a normal state. Incoming AC24 voltage is transformed to three-volt direct-current (3V DC) voltage. The 3V DC voltage is distributed to the system. 
         [0042]    When AC24 voltage drops, the fourth foot of U3 chip produces a lower voltage. Thus, the first foot of U3 will produce a voltage to open the CMOS, and the battery can supply power to the whole system accordingly. 
         [0043]    When AC24 voltage resumes at a normal value, the forth foot will have a higher voltage. Thus, the first foot will produce a voltage to disconnect the CMOS Q 1 . The AC24, not the battery, supplies power to the system. 
         [0044]      FIG. 3  shows a digital thermostat  1 . The thermostat  1  includes a touch screen  2 , which is detailed below. A frame  3  surrounds the touch screen  2  and forms the rear thereof. 
         [0045]      FIG. 4  shows a mounting plate  4 . The mounting pate  4  is affixed on a wall. The mounting plate  4  has a connector  5  for connecting to a HVAC system (not shown). 
         [0046]      FIG. 5-7  show the digital thermostat  1 .  FIG. 5  shows the rear of the digital thermostat  1 . Disposed on the rear of the digital thermostat  1  is a connector  6 . The connector  6  of the digital thermostat  1  couples with the connector  5  of the mounting plate. The digital thermostat  1  can be separated from the mounting plate  4  for easier handling during programming. A battery slot  7  is formed in the rear for holding two AA batteries. 
         [0047]      FIGS. 8-9  shows detailed views of the touch screen  2 , which is also a display. The touch screen includes a system select  10 . By touching the system select  10 , a user can select a mode for the thermostat (i.e. heat, off, cool, emergency, or automatic). When not selecting, the system select  10  shows the current mode. 
         [0048]    A current time is set by using the clock button  11 . 
         [0049]    A hold button  12  programs a constant set temperature and bypasses the timer. The hold button  12  is used, for example, to set a temperature when the occupants are on vacation. 
         [0050]    A schedule button  13  is used to enter scheduling mode. 
         [0051]    A screen button  14  locks the screen for cleaning. When pressed, other regions of the touch screen  2  can be pressed without affecting the controls. The screen button  14  is pressed again to resume normal operation of the screen  2 . 
         [0052]    An up arrow  15  and down arrow  16  are used to raise and lower, respectively, the temperature setting. 
         [0053]    A fan button  17  set the fan mode and switches the fan from on to off to automatic. When not being used to select the fan mode, the fan button  17  displays the selected mode. 
         [0054]    A day icon  18  indicates the day of the week. The unit may be programmed for different settings based on the time and day of the week. 
         [0055]    A schedule icon  19  indicates that the system is running as scheduled and that the program is not being overridden. 
         [0056]    A time icon  20  displays the current time, hold time remaining, or number of vacation days remaining. 
         [0057]    A temperature icon  21  displays the inside temperature. 
         [0058]    A set temperature icon  22  displays the set temperature.