Patent Publication Number: US-2009236433-A1

Title: Thermostat control system providing power saving transmissions

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. patent application Ser. No. 10/990,897 filed on Nov. 17, 2004, which is to be an issued U.S. Pat. No. 7,537,171 on May 26, 2009. The entire disclosure of the above application is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to climate control systems, and more particularly to a thermostat control system for controlling transmission power between thermostat control system devices, including remote units. 
     BACKGROUND OF THE INVENTION 
     Thermostat control systems typically include a thermostat unit for sensing climate conditions (e.g., temperature) and controlling an associated Heating Ventilating and Air Conditioning (HVAC) system. Multiple thermostat units may be provided with each controlling a separate climate zone using a single HVAC system or separate HVAC systems. For example, a separate thermostat unit may be provided on each floor of a home for separately controlling (i.e., monitoring and activating) the heating and cooling on each floor (usually, but not necessarily) using separate heating and air conditioning units. 
     Even with multiple thermostat units or separate climate zones, maintaining a comfortable temperature level in different portions of a building during different times of day is very difficult. A programmable thermostat unit may be used to provide additional climate control (e.g., different set point temperatures during different time periods). However, it is still difficult to achieve comfortable climate levels in different rooms throughout the day because of changes in internal home environment conditions that are typically hard to predict and control (e.g., opening and closing blinds in different rooms and/or opening and closing various external doors). 
     Oftentimes the thermostat unit is installed in a location (e.g., kitchen hallway) that is not desirable for temperature measurements relative to other rooms in a building (e.g., a house). Also, individuals in a house usually occupy different rooms at different times of the day. Thus, the thermostat unit fails to accommodate the climate control needs of occupants at various times of the day. Further, outdoor conditions, including for example, the angle of the sun, may affect internal house temperature in different rooms. This further increases the problem of maintaining comfortable climate levels in different rooms of a house throughout the day. 
     Attempts to address these problems and maintain better climate control within a building include providing wired and remote temperature sensor devices in rooms separate from the main thermostat unit. These sensors typically provide temperature and other climate information to the thermostat unit for use in controlling an associated HVAC system based upon transmitted climate condition information from the sensors in specific rooms. Thus, depending upon which room of the house is most often used during a particular time period, the thermostat may be programmed to use the transmitted sensed temperature information from the sensor in that particular room to activate cooling and/or heating. The thermostat unit may be configured for processing sensed transmitted climate conditions from more than one remote sensor to thereby control an HVAC system to heat and/or cool a building. Such a thermostat unit is the 1F95-479 model thermostat, manufactured and sold by the White-Rodgers Division of Emerson Electric Co. 
     Remote sensors are usually more desirable than wired sensors because of the ease of installation (i.e., no hard wiring required). However, remote sensors are typically powered by replaceable internal power supplies (e.g., batteries), making power conservation (i.e., reducing power consumption and usage) a larger concern. Conserving power is also a concern in battery powered thermostat units. For example, if a climate control system is replaced, with the associated thermostat unit also replaced, additional sources of power (e.g., an internal power supply) for the thermostat unit may be required to control the new system, such as when replacing a single stage system with a multi-stage system. 
     Systems and devices are known that attempt to conserve or save power in order to extend the life of the replaceable power supplies within specific devices of a thermostat control system. Some of these systems transmit only at lower power levels, which may result in a failure to provide reliable transmissions depending upon the distance between the thermostat unit and sensors, as well as other interference. In other known systems, the number of transmissions from a remote sensor may be reduced, for example, by transmitting temperature information only after a predetermined time period. Although this may conserve power, unnecessary transmissions can occur during extended periods in which temperature variations do not exceed a fraction of a degree in temperature. For example, if the temperature in a house remains relatively constant at 70 degrees for a two hour period, a sensor that transmits on a periodic basis would waste power transmitting the same temperature value to the thermostat, which would accordingly hold the heating and cooling systems in an off state. 
     Still other systems include devices having different types of low-power transmitters, which are typically costly, and again may fail to provide reliable transmissions. With such a system, multiple sensors or transmitting units may be required to transmit sensed temperature information from the remote sensing unit to the main thermostat unit located a distance from the remote sensor (i.e., transmit from one unit to the next). 
     Therefore, these known systems and devices fail to provide power saving transmissions (i.e., reduction in power consumption) while ensuring reliable and timely sensed climate information, This can result in unacceptable temperature levels. Further, these systems and devices are generally costly to manufacture. 
     SUMMARY OF THE INVENTION 
     The present invention provides a low-cost system and method for reducing power consumption in climate control systems having remote and/or other internally powered components, while maintaining reliability in transmissions. Generally, transmissions are provided at one of two power levels, with climate control data or information transmitted at one of two different data transfer rates (i.e., data transmission speeds). 
     Specifically, a transmitting device (e.g. a transmitter or transceiver) and corresponding receiving device (e.g., receiver or transceiver) are configured for communicating at different power levels and data transfer rates. A thermostat control system is provided that transmits and receives climate information preferably using radio frequency (RF) signals at the different power levels and data transfer rates. The transmitter and receiver may be provided separately in different system components. For example, a transmitter constructed according to the present invention may be provided in a remote sensor, with a receiver constructed according to the present invention adapted to receive transmissions from the transmitter provided in a thermostat unit, or vice versa. However, a transmitter and receiver may be provided in both the thermostat unit and each remote sensor, and may be implemented either as separate component parts or as a single unit (e.g., a transceiver). A transceiver allows for bi-directional communication between the thermostat unit and the remote sensors. 
     Specifically, a transmitting device of the present invention within, for example, a thermostat unit or remote sensor powered by an internal replaceable power supply (e.g., batteries), preferably transmits a lower power signal more frequently than a higher power signal. For example, if the remote sensor transmits only on a sensed temperature change of more than a predetermined amount, the remote sensor may transmit multiple times at the lower power level followed by a single higher power level transmission. Preferably, a higher power level transmission may occur at a predetermined time interval to ensure that a corresponding receiving device receives at least this higher power transmission (e.g., every thirty minutes if no higher power level transmission occurs). Thus, if multiple lower power level transmissions occur between higher power transmissions, but are not received by a corresponding receiving device because of interference (e.g., electrical noise), the periodic higher power transmissions ensure that, for example, the thermostat unit receives climate control information at least once during a predetermined time period. Reliability of climate information is thereby maintained during normal operation of the thermostat control system. 
     To further ensure the reliability of transmissions and extend power supply life, the higher power level transmission is preferably provided at a lower data transfer rate and the lower power transmission is preferably provided at higher data transfer rate. If lower power level transmissions are not reliably received by a receiving device of the present invention, a transmitting device of the present invention may be configured to transmit only at a higher power level. This provides the user with time to select a new location for the transmitting device while maintaining reliable transmissions until a new location is selected. 
     In operation in connection with a thermostat control system, a setup or learn mode and a normal operating mode are preferably provided. During the setup or learn mode, remote sensors may be adjusted (i.e., relocated) depending upon the thermostat unit requirements. For example, the placement of remote sensor units may be changed to maximize or optimize transmission signal reception strength (ensure low power level transmissions are received). The signal reception strength may be displayed on the thermostat unit as a signal strength indicator for each remote sensor. Each sensor comprises a device serial number unique to the particular sensor. During the setup or learn mode, each sensor is prompted to transmit a “flag” within the transmission signal that provides a unique identification of the serial number of the sensor, which is used by the thermostat&#39;s transceiver unit later to recognize a signal from that sensor. Therefore, during the normal operating mode, the transceiver unit will only recognize signals that include the serial numbers of the sensors that were identified and saved during the set-up mode, and will ignore any signals from other nearby sensors in neighboring households. The thermostat can also distinguish between transmissions from multiple remote sensors in the same household. During the set-up mode, the user may assign each sensor with a designation, such as the letters A, B, C etc. that is included in the transmission signal, so that the user can relate the temperature displayed on the thermostat for sensor “A” with the room that sensor “A” is in, and likewise for sensors B, C, etc. 
     Thus, the present invention provides a system and method for use with climate control systems having remote components and other internally powered devices, to extend the power supply life of these components, white ensuring reliability in transmission. Control of transmissions between system components is provided using different power levels in combination with different data transfer rates. 
     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiments of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
         FIG. 1  is a building floor plan showing a preferred embodiment of a climate control system in which a transmitter and receiver constructed according to the principles of the present invention may be implemented; 
         FIG. 2  is a perspective view of a preferred embodiment of a thermostat unit having a receiving device constructed according to the principles of the present invention therein; 
         FIG. 3  is a perspective view of a preferred embodiment of a remote sensor having a transmitting device constructed according to the principles of the present invention therein; and 
         FIG. 4  is a flow chart showing a preferred embodiment of a process for controlling transmission power according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. Thus, although the application of the transmitting and receiving devices of the present invention as disclosed herein is generally discussed in relation to a particular climate control system, having specific component parts (e.g., remote sensors), it is not so limited, and any type of climate control system wherein remote transmissions are provided and/or that have components using replaceable power supplies may incorporate the transmitting and receiving devices according to the principles of the present invention. 
     The present invention provides for conserving power in a thermostat control system using power saving transmissions. However, before further describing the invention, it is useful to understand a system within which the present invention may be implemented. In particular, this may be further understood with respect to the climate control system shown by example in  FIGS. 1 and 2 , and the thermostat unit and remote sensor shown by example in  FIGS. 3 and 4 . 
     A preferred embodiment of a climate control system including a thermostat control system having remote internally powered components is shown generally in  FIG. 1 . The thermostat control system having remote components typically includes a thermostat unit  20  that may be in communication with a plurality of sensors, such as remote sensors  22 . As shown therein, the remote sensors  22  may be provided in different rooms of a building  24  (e.g., a residential house) for sensing climate conditions in those rooms and transmitting information relating to the climate conditions to the thermostat unit  20 . The climate information may include, for example, the sensed temperature or temperature change, the measured humidity and identification information (e.g., device type ID, unique sensor ID and/or channel number) uniquely identifying the particular remote sensor  22 . Bi-directional communication may also be provided, such that the remote sensors  22  may be configured for receiving control information from the thermostat unit  20 . One particular remote climate control system for use with the present invention includes the 1F95-479 thermostat and F0148-1328 remote sensor, both manufactured and sold by the White-Rodgers Division of Emerson Electric Co. 
     It should be noted that more than one thermostat unit  20  may be provided within the building  24  and/or a plurality of remote sensors  22  may be provided on different floors or levels of the building  24 . Each remote sensor  22  is preferably configured for use with a specific thermostat unit  20 , with the thermostat unit  20  recognizing transmissions from each remote sensor  22  associated therewith as described herein. Also, information may be transmitted from the remote sensors  22  to the thermostat unit  20  or from the thermostat unit  20  to the remote sensors  22 , depending upon climate control system requirements. 
     With respect generally to a climate control system  26 , and more particularly to one having remote components with internal power sources in which the present invention may be implemented, a thermostat unit  20  communicates wirelessly with a plurality of remote sensors  22  to determine climate conditions, as shown in  FIG. 1 . The thermostat unit  20  processes the climate condition information and controls (e.g., starts heating or cooling cycle) an HVAC system  28  based upon predetermined system settings (e.g., user programmed set-point temperatures stored in a digital programmable thermostat unit  20 ). It should be noted that the thermostat unit  20  may be provided with a local sensor (not shown) for sensing climate conditions near the thermostat unit  20 . The thermostat unit  20  may also process information from the local sensor, in addition to the sensors  22  to control the HVAC system  28 . 
     As shown in  FIG. 2 , a thermostat unit  20  in which the present invention may be implemented includes a base  32  and a removable face or cover  34  adapted for connection to the base  32 . The removable face or cover  34  may include an opening  36  for viewing a liquid crystal display used for programming the thermostat unit  20  and obtaining climate control information (e.g., current temperature, set-point temperature, etc.). Buttons  38  provide for programming the thermostat unit  20  (e.g., selecting the set-point temperature). 
     The thermostat unit  20  may be provided with an internal compartment (not shown) or similar member having a replaceable power supply (i.e., depletable), which preferably comprises a plurality of batteries (e.g., two M batteries) for powering components within the thermostat unit  20 . The internal replaceable power supply may be utilized when power is temporarily unavailable from an external power source (e.g., main power to thermostat unit  20  fails) to preserve the system or programmed settings of the thermostat unit  20 . An example of such a thermostat unit  20  in which the present invention may be implemented is the 1F95 Series thermostat manufactured and sold by the White-Rodgers Division of Emerson Electric Co. 
     The internal replaceable power supply may also be used when external power to the thermostat unit  20  is permanently unavailable, such as in a retrofit installation with power to internal components provided by the internal replaceable power supply (e.g., when replacing a single stage system with a multi-stage system having a multi-stage thermostat requiring more than one power source). An example of such a thermostat unit  20  in which the present invention may be implemented is the 1F95 Series thermostat manufactured and sold by the White-Rodgers Division of Emerson Electric Co. 
     With respect to powering the thermostat unit  20 , power may be needed for a microprocessor  44  or a receiver  46  provided in accordance with the present invention. It should be noted that power for the microprocessor  44  and receiver  46  may be provided from an external source connected directly to the thermostat unit  20 . Further, the thermostat unit  20  preferably includes a controller as part of the microprocessor  44  for controlling operation of the thermostat unit  20  (e.g., activating cooling and/or heating). 
     As shown in  FIG. 3 , a remote sensor  22  in which the present invention may be implemented includes a removable face or cover  48  adapted for connection to a base  50 . An opening  58  may be provided in the face or cover  48  for viewing a liquid crystal display. The liquid crystal display may provide system and/or climate control information (e.g., current sensed temperature). Buttons  59  are preferably provided for use in obtaining information from and programming the remote sensor  22 . 
     The remote sensor  22  is powered by an internal replaceable power supply  56  (i.e., depletable), shown as replaceable batteries (e.g., two AAA batteries), which are provided within an internal compartment  54 . Components within the remote sensor  22  preferably include a temperature sensor  60  (eg. temperature sensor circuit), which may be provided in any known manner, and a transmitter  62  adapted for communication with the receiver  46  in accordance with the present invention, and as described herein. It should be noted that the remote sensor  22  alternately may be powered by an external power supply. An example of such a remote sensor  22  in which the present invention may be implemented is the F0145-1328 remote temperature sensor. 
     In addition to the receiver  46  in the thermostat unit  20 , a transmitter  62  may be provided therewith. Further, in addition to the transmitter  62  in the remote sensor  22 , a receiver  46  may be provided therewith. The transmitter  62  and receiver  46  may be provided as a single unit (e.g., a transceiver). The transceiver unit  70  of the thermostat  20  comprises an antenna  64 , a transceiver chip  66 , and a processor  68 . The transceiver chip  66  receives signals from the antenna, and compares the signal to a reference signal. For example, in the preferred embodiment, the signal is compared to a local oscillator having a frequency of 418 Mhz, and is demodulated into a digital data stream. This data is output through a communication link to the processor  68 , which loads the data into a software buffer for protocol verification. The processor  68  strips the data and analyzes the synchronization bit at the beginning of the signal to synchronize the transmitted signal and the transceiver chip  66 , and also analyzes the unique serial number within the transmission to verify the signal protocol with stored sensor serial numbers. When protocol verification of the transmitted signal is completed and the signal verified to be valid, the received data stream is transferred from the processor  68  to the thermostat&#39;s microprocessor  44  using synchronized serial communication. The transmitted information is not identified or stored by the processor  68 , but rather by the thermostat&#39;s microprocessor  44 . The microprocessor  44  of the thermostat receives the transmitted data and identifies the sensor letter designation A, B, C etc., to uniquely identify and store the data pertaining to the appropriate sensor unit. 
     Having described one type of climate control system  26  with a thermostat control system including various component devices (i.e., thermostat unit  20  and remote sensors  22 ) in which the present invention may be implemented, in accordance with a preferred embodiment of a transceiver unit  70  of the present invention, communication is provided at different transmission levels. Specifically, the transmitter in the temperature sensor  22  is adapted to transmit climate and control information to the transceiver  66  at a plurality of power levels, and preferably at one of two power levels as follows: (1) a lower power level or (2) a higher power level. Preferably, during normal operation as described herein, the temperature sensor transmitter transmits at a lower power level more frequently than at a higher power level. The transmitted signal is preferably configured as a carrier present/carrier absent continuous Surface Acoustic Wave (SAW) type of transmission. 
     The temperature sensor transmitter is preferably also adapted for transmitting the climate and control information to the transceiver  70  at a plurality of data transfer rates, and more preferably at one of two transfer rates as follows: (1) a lower transfer rate of preferably about 2000 bits per second (bps); or (2) a higher transfer rate of preferably about 4000 bps. More preferably, the lower power transmission is provided at the higher data transfer rate and the higher power transmission is provided at the lower data transfer rate. However, in some embodiments this can also be reversed so that at the lower power the transmission is at the lower data transfer rate, and at higher power the transmission is at the higher data transfer rate. The base frequency of the transmitter may be configured as required, and for residential uses, may be provided at about 418 MHz. 
     The transmitter in the temperature sensor for transmitting climate or control information at one of two power levels and one of two data transfer rates may be provided by a programmable transmitter chip, such as, for example, a Chipcon Chip #CC1070 manufactured and sold by Chipcon. The transceiver chip  66  for receiving climate or control information at one of two power levels and one of two data transfer rates from the transmitter may be provided, for example, by a Chipcon #CC1020 sold and manufactured by Chipcon. It should be noted that if the transmitter is adapted for transmitting at a frequency at which the transceiver is not adapted to receive, the received signal is preferably frequency shifted in a known manner. Further, depending upon the transmission requirements of the particular thermostat control system, a different transmitter or receiver may be provided having different power levels and data transfer rates. 
     In a more preferred operation, a remote sensor  22  is activated in a setup or learn mode upon installation. In this mode of operation, the transmitter  62  preferably transmits at predetermined time intervals (e.g., every eleven seconds) a lower power/higher data transfer rate test signal for reception by a receiver  46  or transceiver  70  in a thermostat unit  20  that is also activated in a setup or learn mode. The test signal preferably includes a leader to indicate the transfer rate of the signal, which will be included with transmissions during the normal operating mode, and also includes a “flag” or a serial number identification of the particular sensor unit, for use by the thermostat&#39;s transceiver unit  46 ′ in identifying future transmissions from the specific remote sensor  22  during the normal operating mode. The sensor  22  also prompts the user to assign each sensor with a designation letter A, B, C etc. that is included in the transmission signal, so that the user can relate the temperature displayed on the thermostat for sensor “A” with the room that sensor “A” is in, and likewise for sensors B, C, etc. 
     The thermostat unit  20  may be provided with a visual indicator to show the strength of the signal received from the remote sensor  22  in the setup or learn mode in order to determine whether the remote sensor  22  should be installed in a different location to provide better signal transmission strength. An example of such a thermostat unit  20  in which the present invention may be implemented is the 1F95-479 Series thermostat manufactured and sold by the White-Rodgers Division of Emerson Electric Co. Alternately, if the remote sensor  22  is installed in a location providing weak transmissions to the thermostat unit  20 , and the user does not desire to move the remote sensor  22 , the transmitter  62  is adapted to transmit once at a higher power/lower data transfer rate after a predetermined number of transmissions. This will ensure at least one transmission is reliably received in a given number of successive transmissions. It should be noted that the frequency of higher power/lower data rate transmissions may alternatively be based on a time period, and is preferably any suitable means for providing a frequency of reliable higher power transmissions. 
     With respect to determining signal strength, and for example, one or more light emitting diodes (LEDs)  70  (e.g., a tricolored LED of three single colored LEDs) may be provided in connection with the thermostat unit  20  to preferably indicate signal strength as follows: (1) green indicates strong signal strength; (2) yellow indicates adequate signal strength and the user should consider moving the remote sensor  22  or setting the transmitter  62  to a higher power level only mode; or (3) red indicates unacceptable signal strength requiring moving the remote sensor  22  or setting the transmitter  62  to a higher power level only mode. It should be noted that the setup or learn mode is activated for each remote sensor  22  that will transmit data to the thermostat unit  20  during the normal operating mode. 
     After completion of the setup or learn mode the remote sensor  22  and thermostat unit  20  are returned to a normal operating mode. If in the normal operating mode a user determines that the thermostat unit  20  is not properly controlling climate conditions, such as, for example, if a room having a remote sensor  22  therein becomes too warm, this may indicate that signal strength has become weak. The weak signal strength may result from, for example, an electronic device that may have been moved in close proximity to the remote sensor  22  and is causing interference. In such a case, the remote sensor  22  and thermostat unit  20  may again be placed in the setup or learn mode in order to identify a better location for the remote sensor  22  or to select a higher power level only transmission mode for operation. 
     In the normal operating mode (i.e., remote sensor  22  set to transmit at lower power/higher transfer rate more frequently), the transmitter preferably periodically transmits climate and control information to the receiver or transceiver of the thermostat  20 . In this mode, the temperature sensor transmitter preferably transmits only on a sensed temperature change of a predetermined amount. 
     With respect specifically to controlling transmission levels and providing power saving transmissions according to the present invention, and as shown in  FIG. 4 , in a more preferred normal operating mode, the remote sensors  22  sense climate conditions at step  100  at predetermined time intervals. For example, sensing may occur every 30 seconds. Upon sensing a change in climate conditions (e.g., temperature change) that exceeds a predetermined amount (e.g., 3/16° F. temperature change in the normal transmission mode or 6/16° F. temperature change in the higher power level only transmission mode) at steps  102  and  104 , the transmitter transmits a lower power/higher data transfer rate signal to the thermostat transceiver or receiver at  108 , unless a predetermined number of transmissions (e.g.,  10  transmissions) since the last higher power/lower data transfer rate transmission has been exceeded at step  106 . If the predetermined number of transmissions has occurred, a higher power/lower data transfer rate signal is transmitted at  110 . If the sensed temperature does not exceed the predetermined temperature change amount, the sensors  22  continue to sense climate conditions at  100  to obtain climate information for use in the next transmission. 
     It should be noted that the sensors  22  may be configured to sense temperature conditions at, for example, random time intervals, fixed time intervals, or a time intervals dependent upon a variable number or value (e.g., last sensed temperature value) at  100 . 
     Although the present invention has been described in connection with specific devices in a thermostat control system as part of a climate control system  26 , including a thermostat unit  20  and remote sensors  22 , it should be appreciated that different or additional components may be provided as part of the climate control system  26 . This may include different thermostat units and sensing devices. Further, a different transmitter may be provided for transmitting a Surface Acoustic Wave carrier present/carrier absent signal, a different type of signal or a different type of carrier wave. Further, more than two power levels and two data transfer rates may be provided in connection with the present invention. Also, transmissions between the various devices of the thermostat control system may be modified, including the time periods and conditions for transmitting information. 
     The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention as claimed.