Thermostat with touch-screen display

[0001] This patent application is being concurrently filed with U.S. patent application Ser. No. 10/453,840 entitled THERMOSTAT OPERABLE FROM VARIOUS POWER SOURCES by Blaine M. Smith, the disclosure of which is hereby incorporated in its entirety for all purposes.

[0002] Not applicable.

[0003] Not applicable.

[0004] The present invention relates generally to thermostats used for heating and cooling systems, such as domestic gas or electric furnaces, and more particularly to large-format touch-screen thermostats with multiple operating levels displaying several icons on each level.

[0005] Digital set-back programmable thermostats typically use a small screen, such as a liquid-crystal display (“LCD”) to display both operational functions and programming values. The user enters commands into the thermostat, such as for setting the current time and date and programming the thermostat, by pressing keys. The keys are often fairly small and are labeled with small type. In many cases a set of instructions explaining the steps that must be taken to operate the thermostat is printed on the thermostat or separately documented, as programming such a thermostat can be quite confusing and tedious. Although programmable thermostats hold out the promise of reducing the energy used by heating systems, the U.S. Environmental Protection Agency, which provides the ENERGY STAR certification for appliances and other devices, has expressed concern that potential energy savings are not being realized because of the difficulties consumers face trying to program conventional digital thermostats.

[0006] It is desirable to provide a digital programmable thermostat with a more convenient and intuitive programming and control interface that facilitates use of the thermostat features, particularly features that can result in energy conservation.

[0007] A thermostat according to embodiments of the present invention has a memory that stores a thermostat operating program and a touch-screen display that is capable of displaying several different sets of icons. The touch-screen display initially displays a first set of icons known as the “HOME” screen. A second set of icons is displayed in response to a user touching a touch icon in the first set of icons. In an alternative embodiment, the user can touch an electo-mechanical key. The second set of icons include display and touch icons for temporary operation of the thermostat, such as when the user wants to maintain a particular temperature or will be away from home for an extended period of time.

[0008] In one embodiment, the second set of icons includes a target temperature icon, a first temporary mode touch-icon, a second temporary mode touch-icon, and target temperature adjustment touch-icons. Touching the first temporary mode touch icon a first time sets the thermostat to maintain a target temperature, and touching the first temporary mode touch icon a second time sets the thermostat to operate according to the thermostat operating program stored in memory. The memory can also store upper and lower set-points. Touching the second temporary mode touch icon a first time sets the thermostat to maintain a temperature between the upper set point and the lower set point, and touching the second temporary mode touch icon a second time sets the thermostat to operate according to the program.

[0009] In another embodiment, a third set of icons includes display and touch icons for programming the thermostat. The third set of icons is displayed in response to a user entry, such as pressing a button. The user can program multiple start- and stop-times and temperatures for various periods of each day, and can copy one day's program to the next. In a further embodiment, a fourth set of icons includes display and touch icons for entering data into the thermostat, such as the current time and day. The fourth set of icons includes a lock touch icon. Touching the lock touch icon locks the program. Touching an icon in the third set of icons does not affect the stored operating program. The program must be unlocked by touching the lock touch icon in the fourth set of icons a second time. Hence, locking and unlocking the program is done on a different level, i.e. through a different set of icons, rather than entering the thermostat operating program.

I. Exemplary Thermostat Operable from Various Power Sources

[0021] FIG. 1 is a simplified circuit diagram of thermostat 10 according to an embodiment of the present invention. Thermostat 10 includes thermostat controller 12, MODE switch 14 (see also FIG. 3), latching relay 16, power supply 20, diode bridge converter 22, triac converter 24, and power source selector 26. Thermostat controller 12 is generally an electronic device that includes a digital central processing unit (“CPU”) 13, a programmable memory 15, a read-only memory 17, and analog circuitry (not separately shown), and draws an average of about 50 micro-Amps. Latching relay 16, and hence thermostat controller 12, draw about 50 mA when latching relay 16 is being switched ON or OFF, but only needs this higher current for a short period because latching relay 16 is magnetically latching.

[0022] In some embodiments, thermostat 10 includes a display 19. If the display 19 is a touch-screen display (see FIG. 3, ref. num. 100), information can be entered from the display 19 to CPU 13 and stored in programmable memory 15.

[0023] Thermostat 10 can be used with gas, oil, or electric heating and air conditioning systems, single-stage heat pumps, 2-wire and 3-wire zoned hot water systems, or gas millivolt heating systems. Thermostat 10 turns a heating system on by shorting heating load terminal 28 (commonly called the “W” terminal in heating, venting, and air-conditioning “HVAC” systems) to heating transformer power terminal 30 (commonly called the “Rh” terminal in HVAC systems) through latching relay 16. When heating load terminal 28 is disconnected from heating transformer power terminal 30 (by opening latching relay 16), the heating system turns off.

[0024] One feature of thermostat 10 is that it can be installed as a replacement thermostat on many different heating systems. For example, a gas millivolt system does not typically have twenty-four volts supplied to the thermostat. Thermostat 10 can operate off of battery 31 for these systems. Some gas and electric heating systems provide a common wire (commonly called the “C-wire” in HVAC systems) to the thermostat, and thermostat 10 can operate off the 24 VAC between the common terminal 56 and heating transformer power terminal 30. The diode bridge converter 22 converts the 24 VAC to direct-current voltage and provides it to power supply 20 in these systems. In an electric heating system that does not provide a C-wire but does have 24 VAC between the heating transformer power terminal 30 and heating load terminal 28, thermostat 10 can operate off power provided from triac converter 24 to diode bridge converter 22. If 24 VAC power is lost, thermostat controller 12 can maintain its settings (operating program) by operating off of battery 31.

[0025] Thermostat controller 12 has a low battery detector 38 that senses the voltage of battery 31. Capacitor 40 across battery 31 provides a low-impedance path for transients that might otherwise appear at 3 VDC power input 42, and stores charge to provide additional current for operating latching relay 16 when the voltage of battery 31 drops due to aging or other causes. If battery 31 is removed, capacitor 40 holds sufficient charge to maintain the program settings in memory 15 for at least one minute. When battery 31 is new, current from capacitor 40 is not usually required to operate latching relay 16.

[0026] Low-battery detectors that sense voltage often use a battery that produces a relatively high over-voltage, such as providing a third AA alkaline battery in series to produce 4.5 VDC. However, such high over-voltages can cause thermostat controller 12 to malfunction, and in a particular instance causes all fields of the LCD (see FIG. 3) to turn on. Reducing the over-voltage to the operating voltage also wastes battery power. With low battery detector 38 of thermostat 10, thermostat 10 can operate off of power from diode bridge converter 22 and/or triac converter 24 even if battery 31 is omitted. However, battery 31 must be installed for proper operation of low battery detector 38.

[0027] With power from diode bridge converter and/or triac, thermostat controller 12 continues to operate when the battery voltage drops to 2.5 V. Low battery detector 38 turns ON when the battery voltage drops to about 2.6 V, and basically measures the voltage of battery 31 to ground. The internal impedance of the battery increases as the battery voltage decreases. The source impedance of power supply 20 is essentially constant. The low battery detector 38 will follow the battery voltage down until the batteries' internal impedance is higher than the source impedance of power supply 20, which occurs at a battery voltage of about 2.6 V. Then the power supply 20 will keep the voltage from dropping any lower, and the low battery detector 38 turns on a “LOW BAT” field on a liquid-crystal display (“LCD”) (see FIG. 3, ref. num. 111) of thermostat 10. Thus, the user is alerted to a low-battery condition even when thermostat 10 is operating off of AC power. If AC power is not available, thermostat 10 continues to operate off of battery 31 after low battery detector 38 indicates a low-battery condition until the battery voltage drops to about 2.5 V.

II. Use of Thermostat with Exemplary Heating Systems

[0028] FIG. 2A is a simplified circuit diagram of thermostat 10 of FIG. 1 using battery power to control a gas millivolt heating system. A millivolt unit 32 of a gas millivolt furnace 34 is connected to heating load terminal 28 and heating transformer power terminal 30 of thermostat 10. Millivolt unit 32 is a thermoelectric device that generates a small electric signal (about 750 mV) from the heat of the pilot light of the gas furnace for operating gas valve 35 of gas millivolt furnace 34. Shorting heating load terminal 28 to heating transformer power terminal 30 of millivolt unit 32 through latching relay 16, which is controlled by thermostat controller 12, and MODE switch 14 turns on gas millivolt furnace 34. Dual jumper 36 of power source selector 26 is set to a first position (as shown) when thermostat 10 is installed for operating thermostat controller 12 off of battery 31. Dual jumper 36 connects heating transformer power terminal 30 directly to heating load terminal 28 when latching relay 16 is ON, bypassing triac converter 24. Two AA alkaline batteries in series provide about 3 VDC, and can typically power thermostat 10 for over one year. When battery 31 runs down, thermostat 10 will stop working; however, thermostat 10 will indicate when battery 31 is low before the battery voltage drops too low to operate thermostat 10.

[0029] FIG. 2B is a simplified circuit diagram of thermostat 10 of FIG. 1 using diode bridge converter 22 to control a gas or electric heating system 48 that has a common wire (“C-wire”) 50. Heating system 48 includes a transformer 54 that steps down 115 V, 60 Hz electrical power to provide 24 VAC between heating load terminal 28 and heating transformer power terminal 30 to operate furnace relay 55. Twenty-four VAC is also present between Common terminal 56 and heating transformer power terminal 30. Transformer 54 typically provides about one Amp of current. Dual jumper 36 is in the first position (as shown) when operating off of power from C-wire 50, as it is when operating a gas millivolt system off of battery 31 (see FIG. 2A).

[0030] Twenty-four VAC power from C-wire 50 is supplied through capacitor 52, dual jumper 36, and capacitor 53 to diode bridge converter 22. Capacitor 52 limits the current available at diode bridge converter 22 without generating the heat that would be generated with a current-limiting resistor. Using capacitor 52, rather than a resistor, as a current-limiting device in thermostat 10 is particularly desirable because capacitor 52 and other components are within a housing of thermostat 10, and it is estimated that an equivalent current-limiting resistor would raise the temperature inside the housing 20° F. in twenty minutes at an ambient temperature of 70° F. In a particular embodiment, capacitor 52 is a 0.47 micro-Farad non-polar capacitor. Capacitor 53 is a 2.2 micro-Farad non-polar capacitor.

[0031] Diode bridge converter 22 draws about 13 mA from the 24 VAC. Zener diode 58 clamps the voltage at collector 60 of transistor Q1 at about 5 Volts. A voltage divider includes resistor 62, which is 24 kOhms, in series with resistor 64, which is 68 kOhms, thus the voltage at base 66 of transistor Q1 is 3.6 V, and the voltage at emitter 68 of transistor Q1 is 3.1±0.1 VDC. The voltage at emitter 68 is usually slightly higher than the voltage from battery 31 when operating off of C-wire 50 power and the output impedance of transistor Q1 is higher than the internal impedance of battery 31. When thermostat 10 operates off of power from C-wire 50, battery 31 lasts much longer than if thermostat 10 operated only off of battery power. If power from C-wire 50 is lost, thermostat 10 automatically runs off of battery 31, if available. Conversely, thermostat 10 will continue to work if C-wire power is available and battery 31 is dead or missing.

[0032] Thermostat 10 can “borrow” operating power from the relay current if the operating current is a small portion (typically under 10%) of the total relay current. For example, if the operating current is about 13 mA and the relay current is 200 mA, the operating current used for the power supply is only about 7% of the relay current. If the relay current is less than about 130 mA, borrowing operating power from relay current might affect system performance. For example, the relay might not open, or the relay might chatter or hum. Older furnaces often draw more than 200 mA for the relay current, thus borrowing operating power from the relay current in these older furnaces does not adversely affect their operation. Some newer furnaces draw less than 100 mA for the relay current, and the C-wire, if available, is used to power thermostat 10, as discussed above in reference to FIG. 2B.

[0033] FIG. 2C is a simplified circuit diagram of thermostat 10 of FIG. 1 using power from triac converter 24 to control a gas or electric heating system 48′ that does not have a C-wire, but that does have transformer 54 to operate furnace relay 55. With dual jumper 36 in a second position (as shown), latching relay 16 ON, and mode switch 14 in HEAT, there are essentially zero volts across heating load terminal 28 and heating transformer power terminal 30. However, triac converter 24 is in series between heating load terminal 28 and heating transformer power terminal 30.

[0034] Back-to-back Zener diodes 70, 72 and resistor 74 allow AC-voltage to appear across triac 76 for a short portion of the phase without turning on triac 76. Both Zener diodes 70, 72 are fifteen-volt Zener diodes, and resistor 74 is a 4.7 kOhm resistor. About 10° of phase delay is produced. After this phase delay, triac 76 conducts current to operate furnace relay 55. Control of furnace relay 55 by thermostat 10 is not significantly affected by the short phase delay of triac 76. Turning triac 76 on after the phase delay creates small voltage spikes across triac 76 at 120 Hz. These 120 Hz voltage spikes are coupled through capacitor 53 to diode bridge converter 22. Diode bridge converter 22 converts the voltage spikes to DC, which is provided to power supply 20. About 5 mA of current is provided to power supply 20, which provides regulated 3 VDC to thermostat controller 12.

[0035] When latching relay 16 is OFF, or with mode switch 14 OFF or in COOL, there is no current flowing between heating transformer power terminal 30 and heating load terminal 28 for triac converter 24 to use. However, there is 24 VAC across heating transformer power terminal 30 and heating load terminal 28, which is coupled to diode bridge converter 22 through capacitor 78. Capacitor 78 is a 0.47 micro-Farad non-polar capacitor, which limits the current supplied to diode bridge converter 22, as discussed in conjunction with capacitor 52 in FIG. 2B. The 24 VAC is rectified to DC and provided to power supply 20. Thus, power is supplied to theromostat controller 12 even when latching relay 16 is OFF or mode switch 14 is OFF or in COOL.

III. Exemplary Touch Screen Display and User Interface

[0036] FIG. 3 is a simplified front view of thermostat 10. Thermostat 10 has a touch-screen LCD 100 measuring about 51 mm×95 mm (2 inches×3.75 inches), although this size is merely exemplary and touch screens having other dimensions have been fabricated for use in thermostats according to other embodiments of the present invention. All icons (also known as fields) of touch-screen LCD 100 are shown, which looks cluttered; however, only certain subsets of the icons appear on touch-screen LCD 100 at each level (mode) of operation of thermostat 10. Some of the icons simply display information, and touching these icons has no effect. Other icons are touch icons, and touching a touch icon enters user input to the CPU (see FIG. 1, ref. num. 11).

[0037] Displaying only subsets of the icons reduces the amount of information presented to the user at each level, i.e. at any one time. The relatively large format of touch-screen LCD 100 enables large, easily readable text and large touch icons. The text the user needs to read is displayed on the touch-screen LCD at one of the levels, and the large touch icons facilitate accurate data entry. The touch icons are generally square or rectangular, and in one embodiment each touch icon has a minimum dimension greater than or equal to about 0.25 inches. In a particular embodiment the smallest touch icon is about 0.38×0.25 inches.

[0038] Conventional thermostats often have a much smaller LCD screen and use relatively small pressure-sensitive keys to operate and/or program the thermostat. Conventional LCD screens are typically used to display both operational functions and programming states and data. Such LCD screens are called “shared” displays. In many cases a set of instructions explaining the steps that must be taken to operate the thermostat is printed on the thermostat or separately documented, as programming such a thermostat can be quite confusing and tedious. Although programmable thermostats hold out the promise of reducing the energy used by heating systems, the U.S. Environmental Protection Agency, which provides the ENERGY STAR certification for appliances and other devices, has expressed concern that potential energy savings are not being realized because of the difficulties consumers face trying to program conventional thermostats.

[0039] Thermostat 10 is unique in display and operation. Instead of having one small shared screen for all the information and programming, touch-screen LCD 100 changes as the user enters different levels of operation, each level being intuitive from the previous level and displaying much more information at each level than is typically provided on a conventional shared display. Some icons indicate which mode of operation the thermostat is in. For example, AWAY indicator icon 102 flashes if thermostat 10 is in AWAY mode, and HOLD indicator icon 104 flashes if thermostat 10 is in HOLD mode (discussed below in conjunction with FIG. 4B). Similarly, HEAT indicator icon 106 is activated if MODE switch 14 is set to HEAT 106′, and COOL indicator icon 108 is activated if MODE switch 14 is set to COOL 108′.

[0040] MODE switch 14 is provided as a slider switch at the bottom of thermostat 10, as is FAN switch 110. Thermostat 10 is programmed by pressing PROGRAM button 112, and then entering the desired programming information through touch-screen LCD 100 (discussed below in conjunction with FIG. 4C). Similarly, MENU mode is accessed by pressing MENU button 114 (discussed below in conjunction with FIG. 4D). Reset button 116 is recessed and resets thermostat 10 to factory default settings when depressed. A sharpened pencil or the end of a straightened paper clip is used to depress reset button 116.

[0041] FIG. 4A is a screen shot of HOME SCREEN 120 of touch-screen LCD 100 when thermostat 10 is in HOME level. HOME level is the level from which other levels are accessed. Thermostat 10 reverts to HOME level from other levels after a default period (e.g. about 60 seconds), or when the HOME icon is touched (see FIG. 4B, ref. num. 22).

[0042] In HOME level, touch-screen LCD 100 displays one of the current day icons 124 (“Mo”), current time icon 126 (“AM 8:15”), one of the period of day icons 128 (“MORN”), room temperature icon 130 (“67° F.”), which is a touch icon, current set-point temperature icon 132 (“70° F.”), a HEAT indicator icon 106 (when MODE switch 14 is set to HEAT), tone indicator icon 134, and filter indicator icon 136.

[0043] Filter indicator icon 136 measures the on-time of latching relay 16, which indicates that the HVAC system has operated a pre-selected number of hours, and that it is time to change the air filter of the HVAC system. Measuring the on-time of latching relay 16 enables the filter indicator feature even for gas heating systems in which the furnace turns on the system fan independently of the thermostat. When tone indicator icon 134 is solid it means that thermostat 10 will beep each time a touch icon is activated (touched), and when tone indicator icon is crossed out or outlined (see FIG. 3, ref. num. 113), the beep will not sound. There are three ways to leave HOME level and enter a lower level. Touching room temperature icon 130 in HOME SCREEN 120 changes the touch-screen LCD 100 to TEMPORARY SCREEN.

[0044] FIG. 4B is a screen shot of TEMPORARY SCREEN 140 of touch-screen LCD 100 when thermostat 10 is in TEMPORARY level. TEMPORARY level is accessed from the HOME level when the user touches the room temperature icon (see FIG. 4A, ref. num. 130). TEMPORARY SCREEN 140 allows the user to change the target temperature without affecting the operating program of thermostat 10, which is stored in memory. TEMPORARY SCREEN 140 displays the target temperature 142, temperature UP 144 and DOWN 146 arrows, HOLD touch icon 150, and AWAY touch icon 152 all at the same time. After the user enters a change by touching the appropriate icon on TEMPORARY SCREEN 140, the user can return to HOME SCREEN by touching HOME touch icon 154. If the temperature is changed in the TEMPORARY level (without using HOLD or AWAY), the change will immediately take effect, but be cancelled at the start of the next programmed period. Thus the entered change is only temporary.

[0045] Touching HOLD touch icon 150 puts thermostat 10 in HOLD mode. HOLD mode maintains the target temperature 142 indicated on TEMPORARY SCREEN 140. For example, if the user was going away for the weekend and wanted to maintain a temperature of 65° F., he would touch HOLD touch icon 150 and use the UP 144 or DOWN 146 arrow key to set target temperature 142 to “65”. The user might want to maintain the target temperature so that his home is at a comfortable temperature when he returns, or to maintain an appropriate temperature in the home for pets or plants, for example.

[0046] Touch-screen LCD 100 will automatically revert to HOME SCREEN 120 after a few seconds or the user can touch HOME touch icon 154 to return to HOME SCREEN 120. HOLD indicator icon (see FIG. 3, ref. num. 104) will flash on HOME SCREEN 120 when thermostat 10 is in HOLD mode. To take thermostat 10 out of HOLD mode, the user simply touches the current temperature 130 on HOME SCREEN 120 to enter TEMPORARY SCREEN 140 and touches HOLD touch icon 150 a second time.

[0047] Touching AWAY touch icon 152 on TEMPORARY SCREEN 140 puts thermostat 10 in AWAY mode. AWAY mode is used when the user will be away for an extended period of time and maintains upper and lower temperature set-points that are stored in memory. In other words, the heater will turn on if the temperature drops below the lower set-point and the cooling system will turn on if the temperature rises above the upper set-point. AWAY mode is convenient for second homes, such as ski cabins. The upper and lower temperature set-points are often set outside the normal comfort range, and provide heating or cooling to avoid damage to the home or for other reasons. For example, a lower set-point of 45° F. will turn on the heating system and avoid water freezing in the home, while an upper set-point of 85° F. will turn the cooling system on to avoid scorching plants. The set-points for AWAY mode are pre-set at the factory, but may be overridden by touching the temperature set arrows 144, 146. After a few seconds, or after touching HOME touch icon 154, touch-screen LCD 100 returns to HOME SCREEN 120. AWAY indicator icon (see FIG. 3, ref. num. 102) flashes on HOME SCREEN 120 when thermostat 10 is in AWAY mode. Upon returning, the user would simply touch the current temperature 130 on HOME SCREEN 120 to enter TEMPORARY SCREEN 140 and touches AWAY touch icon 152 a second time to take thermostat 10 out of AWAY mode.

[0048] While conventional thermostats provide features similar to AWAY mode and HOLD mode, they typically require a relatively involved and complicated sequence of serial key strokes, often with small keys that are labeled in difficult-to-read small type. It is believed that users do not use these modes because of the complexity, time, and difficulty of changing to such modes and back again. This causes the user to either leave the thermostat programmed for normal operation, or to turn the system off entirely. The former wastes energy and the latter can result in damage to the home or its contents.

[0049] The present invention provides a large-format, intuitive user interface, and provides access to both temporary modes from a single screen that is only one level from HOME SCREEN 120. About the only thing a user needs to remember is how to get to TEMPORARY SCREEN 140, and that is by touching the largest displayed field (i.e. the current temperature) on HOME SCREEN 120, which in a particular embodiment has a touch area of about 1.5 inches×0.75 inches. The remainder of the process is essentially self-documented on the large-format touch-screen LCD by the icons, and a user typically does not need to reference collateral documentation, such as a user's manual, to change from normal operation to a temporary mode and back again. In particular, activation to or from any temporary mode is achievable from TEMPORARY SCREEN 140, which is only a single level (touch entry) from HOME SCREEN 120.

[0050] FIG. 4C is a screen shot of PROGRAM SCREEN 160 of touch-screen LCD 100 when thermostat 10 is in PROGRAM mode. PROGRAM SCREEN 160 shows all the programming functions for a single day, and COPY icon 162 and REVIEW icon 164 on one screen. The PROGRAM SCREEN enables programming of thermostat 10 that is so intuitive that it is believed most users would not need additional programming instructions. HEAT indicator icon 106 (when MODE switch 14 is set to HEAT 106′) indicates that the user is programming the heating mode. The user can program the cooling mode by switching MODE switch 14 to COOL 108′.

[0051] Values for the thermostat operating program stored in the programmable memory (see FIG. 1, ref num. 15) are entered through touch icons displayed on PROGRAM SCREEN 160. Touch icon areas are indicated on PROGRAM SCREEN 160 by sets of corner brackets 166, 166′. Touching day touch icon 168 within corner brackets 166, 166′ steps (increments) the current day icon to the next day to select the day that the user is programming. Similarly, touching period of day touch icon 170 within the corner brackets increments the period of day icon to select the period of day the user is programming. Four periods of day are available, morning (“MORN”), day (“DAY”), evening (“EVEN”), and night (“NITE”) (see FIG. 3), thus thermostat 10 can be programmed to maintain four different temperatures, one for each period of day for each day of the week. Alternatively, there are more or fewer periods per day, such as two periods or six periods.

[0052] Each day of the week can have the four periods start at different times, and each period of each day can be programmed for a different temperature. Time touch icon 172 has arrows 124, 124′ that increase or decrease the time in fifteen-minute intervals to program the time the heating program begins for the selected day and period. Set temperature touch icon 178 also has arrows 180, 180′ that increase or decrease the set-point temperature for the day and period of day selected. Incrementing the day or period of day automatically enters the time and temperature for the previously selected day or period of day. The user can program four different target temperatures each day, one for each period of day, and the user can program each period of day to start at a different time each day of the week.

[0053] Touching COPY touch icon 162 copies the selected times and temperatures from one day to another. For example, if the user programs thermostat 10 for Sunday (“Su”), touching COPY touch icon 162 once will cause the Monday day icon (“Mo”) to flash. Touching COPY touch icon 162 again will increment day icon 168 to “Mo” and copy the program values for Sunday into Monday. From there, the user can select another day or period of day, or can copy the program to Tuesday (“Tu”). Thus, a user can quickly, easily, and intuitively program thermostat 10 for different times and temperatures for each day of the week.

[0054] Touching REVIEW touch icon 164 automatically steps through the programmed values every five seconds so that the user can see how thermostat 10 is programmed. Touching REVIEW while the programmed values are being reviewed stops the review sequence. Touch-screen LCD 100 will return to the HOME SCREEN 120 a few seconds after the last touch entry, or the user can return to the HOME SCREEN 120 by touching HOME touch icon 154. Entered values are stored in a programmable memory (see FIG. 1, ref. num. 15) in thermostat 10.

[0055] FIG. 4D is a screen shot of MENU SCREEN 190 of touch-screen LCD 100 when thermostat 10 is in MENU mode. MENU mode is entered from HOME SCREEN 120 by pressing MENU button 14. MENU SCREEN 190 shows several set-up touch icons at one time. The set-up touch icons include touch icons for setting the current day and current time using day touch icon 168 and arrows 174, 174′, respectively, setting the temperature to ° C. or ° F. by touching temperature scale touch icon 192, setting the temperature swing (hysteresis) by touching SWING touch icon 194, and then incrementing the swing using arrows 174, 174′. The filter running time is reset by touching FILTER icon 196 and then left arrow 174 on the filter time. The filter set time is set by touching and holding FILTER icon 196 for three seconds, and then changing the set time using the arrows 174, 174′. The tone is turned on or off by touching TONE touch icon 198. Touching LOCK touch icon 200 locks the thermostat operating program stored in memory. When thermostat 10 is locked, a user cannot change the thermostat operating program from PROGRAM SCREEN 160 without first unlocking thermostat operating program from MENU SCREEN 190. On most conventional thermostats, including thermostats with LCD displays, each function, if available, is displayed separately, requiring the user to step though a long sequence of screens to get to the final desired menu level.

IV. Exemplary Methods

[0056] FIG. 5A is a simplified flow chart of a method 500 of operating a thermostat with a touch-screen display and a memory according to an embodiment of the present invention. The thermostat initially operates according to a thermostat operating program stored in the memory (step 502), and the touch-screen display displays a first set of icons (e.g. the HOME screen of FIG. 4A) (step 504). The thermostat optionally stores high and low temperature limits for a temporary operating mode. When operating according to the thermostat operating program, the thermostat is intended to control a heater to maintain a room temperature at or above a current program temperature, for example. It is understood that the heater is not part of the thermostat, but some heaters provide operating power to the thermostat.

[0057] Upon receiving a first user entry (step 506) the touch screen displays a second set of icons (step 508) including at least a first temporary mode touch icon (e.g. FIG. 4B, ref. num. 150), a second temporary mode touch icon (e.g. FIG. 4B, ref. num. 152), and a target temperature icon (e.g. FIG. 4B, ref. num. 142). In one embodiment, the first user input is indicative of touching a first touch icon (e.g. room temperature icon 130 shown in FIG. 4A). In another embodiment, the first user input is indicative of touching a button.

[0058] In a further embodiment, upon receiving a second user entry indicative of touching the first temporary mode icon (step 510), the thermostat operates to maintain a target temperature according to the target temperature icon (step 512). That is, the thermostat controls the heating system to maintain the room temperature within a preseleted range above and below the target temperature. Upon receiving a third user entry indicative of touching the first temporary mode icon a second time (step 514), the thermostat reverts to operating according to the thermostat operating program (step 516).

[0059] In an alternative embodiment, upon receiving a second user entry indicative of touching the second temporary mode icon (step 518), the thermostat operates to maintain a temperature between the high and low temperature limits stored in memory (step 520). When the thermostat receives a third user entry indicative of touching the second temporary mode icon a second time (step 522), the thermostat reverts to operating according to the thermostat operating program (step 524).

[0060] FIG. 5B is a simplified flow chart of a method 550 of operating a thermostat with a touch-screen display and a programmable memory according to another embodiment of the present invention. The thermostat initially operates according to a thermostat operating program stored in the programmable memory (step 502), and the touch-screen display displays a first set of icons (e.g. HOME screen 120 shown in FIG. 4A) (step 504).

[0061] Upon receiving a first user entry (step 506), the touch-screen displays a second set of icons (e.g. TEMPORARY screen 140 shown in FIG. 4B) (step 508) including at least a first temporary mode touch icon (e.g. FIG. 4B, ref. num. 150), a target temperature icon (e.g. FIG. 4B, ref. num. 142), and a second temporary mode touch icon (e.g. FIG. 4B, ref. num. 152). In one embodiment, the first user input is indicative of touching a first touch icon (e.g. room temperature icon 130 shown in FIG. 4A).

[0062] Upon receiving a second user entry (step 552), the touch screen display displays a third set of icons (e.g. PROGRAM screen 160 shown in FIG. 4C) (step 554) that includes a plurality of touch icons for entering thermostat operating program values into the programmable memory. Touching one of the plurality of touch icons (step 556) changes a program value of the thermostat operating program (step 558)

[0063] In a further embodiment, upon receiving a third user entry (step 560), a fourth set of icons is displayed on the touch-screen display (step 562). The fourth set of icons includes a lock touch icon. The thermostat operating program is locked from being changed (step 564) by touching the lock touch icon. The thermostat operating program is unlocked by touching the lock touch icon a second time (step 566).

[0064] Modification and variation can be made to be disclosed embodiments without departing from the subject of the invention as described herein. Any and all patents, patent applications, and printed publications referred to above are incorporated by reference.