Patent Application
20050244014
1. Field of the Invention
The present invention relates to a communication device having temperature sensing capabilities.
2. Description of the Related Art
Communication devices such as mobile phones, Personal Digital Assistants (PDAs), and stationary phones typically do not have temperature sensing capabilities. Users of these communication devices will rely on external conventional temperature sensing devices such as thermometers and temperature probes to determine ambient temperatures. These conventional temperature sensing devices are installed in various locations for monitoring ambient temperatures and/or for monitoring temperatures indicative of a fire. Instead of relying on these fixed external temperature sensing devices, it is desirable in some cases for a user to determine the ambient temperature of an immediate area. Using conventional thermometers and/or temperature sensing devices to measure all immediate areas in which a user could be located would require the installation of many temperature sensing devices and is cost intensive, especially if many areas are to be measured.
If conventional temperature sensing devices such as thermometers and temperature probes are added to existing mobile communication devices to provide a temperature measurement function for measuring the temperature of the environment in which the communication device is located, an additional cost to the device is incurred. Furthermore, the thermometer or temperature probe must be arranged on the communication device so that user interaction with the device does not affect the temperature reading. Accordingly, the incorporation of a temperature measurement device may incur an additional design cost.
If centralized monitoring of temperature is desired, conventional temperature sensing devices must be connected to a separate communication network or a costly integration module must be added to the temperature sensors so that the temperature information detected by the temperature sensing devices may be communicated to a central monitoring area using existing communication networks.
An object of the present invention is to provide temperature monitoring capabilities to a communication device without requiring the addition of a dedicated temperature sensor to the communication device.
A communication device according to the present invention includes a speaker, a microphone, and a processor operatively arranged for calculating ambient temperature by playing a test sound on the speaker, measuring a transit time of the test sound from the speaker to the microphone, and calculating the ambient temperature from the measured transit time.
A method according to the present invention for calculating ambient temperature of a communication device having a speaker and a microphone, includes the steps of playing a test sound on the speaker, measuring a transit time of the test sound from the speaker to the microphone, and calculating an ambient temperature based on the measured transit time.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.
The communication device 10 also includes a display 20 for displaying information to a user of the communication device 10, a memory 18, and an input device 30 such as the numerical keyboard and/or other input keys on a typical mobile phone. The input keys may be hard wired to have specific functions such as the numerical keys on a keypad, or the input keys may be soft keys having different functions in different operating states of the communication device.
The communication device 10 includes the ability to determine ambient temperature using the method illustrated in the flow diagram of
The present invention relies on the principle that as air temperature varies, its density varies. The change in air density causes the speed of sound to vary according to the formula: v=331{square root}{square root over (T/273°)} m/sec., where T is the temperature in ° K. The time required for sound to travel a known distance varies as a function of the air temperature according to the formula
where x is the distance between the speaker and the microphone and v is the speed of sound. Accordingly, the velocity v, and thus the temperature T, may be calculated from the above formulas using the transit time measured in step S210 and the known distance. If two microphones located at different distances from the source of sound are used, each microphone will detect the sound at a different time based on the time required for the sound to travel to each microphone. As described below, the difference between the times of detection at the two microphones may be used to determine the velocity.
The speaker 12 may have an associated delay inherent in a transducer of the speaker 12. This delay may be mitigated in devices having more than one microphone such as, for example, desk phones having a handset with a first microphone 14 and first speaker 12 and a second microphone 14a and speaker 12a on the phone console for hand-free or “speaker-phone” operation.
wherein x1 is the distance between the first microphone 14 and the speaker 12 or 12a, x2 is the distance between the second microphone 14a and the speaker 12 or 12a, and t2-t1 is the difference in time between the time of reception of the test signal at the first and second microphones 14 and 14a. Instead of measuring the transit times from initiation of the test sound to reception at each microphone, the time between detection by each of the microphones may be measured in step S210. The time between detection by each microphone may be determined by direct measurement of the time between the detection occurrences. Alternatively, the time between detection may be determined based on a transfer function between the two microphones, i.e., based on phase versus frequency. Since the above calculation is based on the time difference between reception at each microphone, any static or variable time delay introduced by the speaker is avoided by this calculation.
The distance between the speaker 12 and microphone 14 (and/or microphone 14a) of the communication device 10 is a fixed quantity and may be saved into the memory 18. Alternatively, the distance between the speaker and microphone may be derived when a reference temperature is known. For deriving the distance between the speaker and the microphone, the speed of sound is known at a known temperature and the distance can be determined using the transit time of the test sound between the speaker and microphone.
The temperature calculation feature can be performed periodically by the processor, e.g., every five minutes, etc. Alternatively, the temperature can be calculated in response to a specific user command input by the user via the input device 30 of the communication device.
Once the temperature calculation is desired, it can be transmitted by the communication device to a recipient device system. For example, the temperature measurement can be communicated automatically by the communication device to one or more other devices in communication with the communication device 10. In the case of a communication device comprising a mobile phone, the temperature calculation by a first mobile phone (phone A) can be transmitted to a second mobile phone (phone B), either at the time a call is connected or upon selecting an appropriate function key on phone A.
Furthermore, some communication devices such as PDAs or mobile phones include infrared (IR) sensors 32 (see
As shown in
Instead of determining whether the ambient temperature is within an operating range, a threshold level may be set on the communication device 10 to indicate a possible fire condition. If the communication device 10 is a mobile device normally carried by the user, or is any device which is normally attended by a person, a request for a confirmation that there is an actual fire may be visually displayed or audibly transmitted to the user, step S310. Once the confirmation by the user is received, the communication device 10 may transmit a report to emergency services 28 through the network 24 (see
Service providers of wireless communications networks typically provide location services for their customers which determine a location of the customer's wireless device so that information related to the immediate surroundings of the customer may be provided to the customer. If the communication device is a mobile phone, PDA or other mobile device which uses location services, the report transmitted to the emergency service in step S320 may include a location of the communication device which is derived from the location services of the communication device.
The communication device 10 according to the present invention may be used as a supplement or a replacement of environment monitoring devices such as thermostats, fire control sensors, and desktop thermometers. A plurality of essentially stationary ones of the communication devices 10 may be arranged throughout a building or other area and used for mapping temperatures throughout the building or other area. Such maps may be used for verifying proper operation of HVAC systems.
Thus, while there have been shown and described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.
