Advantages of digital thermostat
Advantages of digital thermostat
Advantages of digital thermostat
An important advantage of the digital thermostat is the simplificity with which the temperature and time settings are stored and retrieved. A minimum number of keys are used, together with a "slew entry" type of system in which the keys are held untilthe desired time or temperature setting is displayed. The keys or switches must be held for a certain predetermined time, such as six seconds, before any alteration of the contents of the registers are effected. As a result, an accidental contacting ofthe keys will not result in accidental alteration of stored time and temperature settings.
Another important advantage is that microcomputer 57 automatically sorts the time settings within the registers H1 through H4. The user may enter times and temperatures in any order, and need not place the earliest time in register H1. This isan important advantage, particularly where the user wishes to add an additional time and temperature (where at least one of the registers had not been previously used), or wishes to alter the time and/or temperature setting stored in one of theregisters. Unlike prior art digital clock thermostats, the thermostat of the present invention does not require that the user reprogram all of the temperature and time settings in order to place the times and temperatures in sequential order. Rather,microcomputer 57 automatically sorts the times within registers H1-H4 to place them in sequential order for use in controlling the heating system.
In normal operation, microcomputer 57 causes display 16 to display room temperature, as sensed by thermistor 94. On a periodic basis, which in one preferred embodiment is every minute, microcomputer 57 performs an "update" routine in which itdetermines whether the furnace should be turned on or off, and whether the air conditioning should be turned on or off. Unlike prior art digital thermostats, the preferred embodiment of the present invention automatically decides whether to turn on heator air conditioning, and does not require the user to select heating only or air conditioning only.
When microcomputer 57 begins the update routine, it first determines the room temperature from the room temperature register, and then determines the time of day from the time-of-day register. Microcomputer 57 then compares the time of day fromthe time-of-day register with the times stored in registers H1, H2, H3 and H4, in order to determine which of the four registers is applicable.
After the proper heat register (H1-H4) has been selected, microcomputer 57 compares the sensed room temperature with the control temperature in the selected heat register. Depending upon this comparison, microcomputer 57 may provide a signal tocontrol circuit 82 to (a) turn on the furnace if it is presently off; (b) turn off the furnace if it is presently on; (c) leave the furnace on; or (d) leave the furnace off. If the furnace is to be turned on, turned off, or left on, microcomputer 57takes the appropriate action and discontinues the update routine. If, however, the furnace was already off and the decision was made that it should remain off, microcomputer 57 then checks the contents of the AO and AC registers to determine whether airconditioning is appropriate.
If the content of the AO register is "OF", no air conditioning is permitted and microcomputer 57 discontinues the "update" routine. If, on the other hand, the content of the AO register is a number between "00" and "23", microcomputer 57 thenchecks the time stored in the AC register against the time of day. If this comparison indicates that air conditioning should be on, microcomputer 57 then compares the room temperature to the control temperature stored in register AC and provides theappropriate signal to control circuit 94 to control the air conditioning system. Microcomputer 57 may (e) turn air conditioning on, (f) turn air conditioning off, (g) leave air conditioning on, or (h) leave air conditioning off.
If the time of day does not fall within a time period in which the air conditioning is to be operating, as indicated by the times stored in the AO and AC registers, microcomputer 57 normally will not turn on the air conditioning. If, however,the room temperature exceeds a predetermined level, such as 85 F., and the AO and AC registers indicate that air conditioning is desired during some hours of the day, then microcomputer 57 will provide signals to control circuit 94 in order tooperate the air conditioning system to maintain room temperature at 85 F. In this way, room temperature is not permitted to rise to such a high level that the air conditioning would be unable to effectively reduce the room temperature to thedesired control temperature during the time period when air conditioning is desired.
The digital thermostat of the present invention also prevents undue switching back and forth between heating and air conditioning by giving first priority to heating. Microcomputer 57 always checks the contents of registers H1-H4 first, and controls thefurnace before any determination of the need for air conditioning is made. In addition, the need for air conditioning is checked by microcomputer 57 only if the furnace is already off and the decision (by comparing the room temperature with the controltemperature in one of the heat registers (H1-H4) is that the furnace should remain off. As a result, a time delay of at least one minute (the period between successive "update" routines) occurs between the turning off of the furnace and the turning onof the air conditioner. If microcomputer 57 turns off the furnace during one update routine, it must wait until the next update routine before it can determine the need for air conditioning.
The thermostat of the present invention, therefore, provides automatic control of both heating and air conditioning and an automatic switch-over between heating and air conditioning without requiring the user to change the position of a switch. This is particularly advantageous in climates where there is a wide variation between daytime and nighttime outdoor temperatures. In these climates, it is often necessary to provide air conditioning during the day and heating during the night.
In addition, the information stored in registers H1-H4 is independent of the information stored in registers AO and AC. The programming of heat control information in registers H1-H4 is independent of and does not affect the information inregisters AO and AC, and vice versa. When the thermostat automatically switches between heating and air conditioning, the contents of regisers H1-H4, AO and AC remain intact. This is unlike the prior art digital thermostats in which switching betweenheating and air conditioning requires reprogramming and/or results in a loss of the time/temperature program for either heating or air conditioning.
In conclusion, the present invention is an easy-to-use, low cost, digital clock thermostat. Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may bemade in form and detail without departing from the spirit and scope of the invention.
Xml Format In Integrated Shipping Why Isn't The Uk Manufacturing Tesla Generators? - Generating Free Electricity With Tesla Secrets Select Tailor "personality" Air Conditioning - Air Conditioning, Purchase, White - Hc How To Speed Up An EZ-GO Electric Golf Cart - News Eia Class 2 Dielectric - Digital Photo Frame 2.4-3.5 Inch - China Small Digital Photo Frame How to Lowering Your Gas and Electricity Bills How to Recover Lost Photos From Mobile and Digital Camera Memory Card WDBACX0010BSL-NESN Western Digital 1 TB USB 3.0 and USB 2.0 - Read This Real Review Tampon - Analog Wrist Watch Manufacturer - China Bracelet Style Watch Inner City Hardware Electrical Electrical Gather Potential Industrial Advantages - Inner Mongolia, Electric Assistance For Any Type Of Wiring What Are Electricians For? Familiarizing Yourself With Electricians