Abstract:
A portable telephone with a speakerphone with a safety mechanism. This portable telephone is prevented from entering speakerphone mode unless the device is within a predetermined amount of horizontal. Otherwise, speakerphone mode cannot be entered.

Description:
BACKGROUND 
     Telephones can often operate in two modes: a normal mode where the earpiece of the telephone is brought up to the user&#39;s ear, and a speakerphone mode in which the telephone becomes more sensitive to sounds, and produces its output volume at a higher level output volume. In the speakerphone mode, the telephone speaker produces much higher volume so the sounds can be heard at a distance. 
     In a desktop telephone, the speakerphone often uses a different speaker than the one normally used for the handset. 
     On a portable phone, however, the same speaker may be used for both the speakerphone mode and for the handset mode. Since the speaker produces much more volume during the speaker mode, an unintentional attempt for the user to put the speakerphone-mode-telephone up to ones ear could cause hearing discomfort or permanent hearing damage. 
     SUMMARY 
     The present system enables using a speakerphone in a portable phone by a safety mechanism that only allows the speakerphone mode to be entered when the portable phone is in the specified position. 
     According to a disclosed mode, that specified position is either at horizontal or within 10° of horizontal. Once the phone is maintained in this position for 1-3 seconds, speakerphone mode is enabled. The inventor recognizes that it is unlikely that a user would use a non-speakerphone in horizontal or close to horizontal position. Therefore, it is unlikely that this position would be used during normal speaking. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a block diagram of an exemplary phone; and 
     FIG. 2 shows a flowchart of operation of the phone. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An embodiment is shown in FIG. 1. A portable phone  100  includes a user interface  102  which among other things has a speakerphone control indication  104 . This can be a dedicated actuation button, or can be selected from the menu. The user interface is controlled by a processor  106  within phone  100 . A tilt sensor  108  detects the position of orientation of the phone. These tilt sensors are commonly used in joysticks and computer equipment. 
     The processor also controls certain operations of the cellular transceiver using cellular electronics  110  to transmit and receive. The cellular electronics  110  can operate in an IS-95 mode. 
     The processor runs the routine shown in FIG. 2 to enter speakerphone mode. Step  200  shows entering the routine by selection of the speakerphone mode. This selection can be from a menu, or from a dedicated speakerphone key. 
     If speakerphone mode is not selected, then the operation continues with the rest of the main loop that is conventionally executed by the processor. 
     If speakerphone mode is selected, the system first checks the tilt sensor  108 . The phone is taken to be in the proper tilt orientation when the phone is in the specified position, here within 10° of horizontal. If properly tilted at step  202 , then the processor is commanded to enter speakerphone mode at step  204 . 
     If tilt is not found to be active at step  202 , the first step determines if the phone is in the desktop charger. The presence on the desktop charger is detected by detecting a specified current through a specified contact  119  on the telephone which is reserved only for desktop chargers. If so, then it is unlikely the user&#39;s ear is placed up to the phone, and the speakerphone mode is enabled. 
     The speakerphone mode is effected by commanding the audio amplifier to produce a higher output mode to the speaker. In this way, more volume is produced by the speaker and presented,to the user. Optionally, the microphone can also be amplified by a higher gain, to facilitate speakerphone mode. 
     If the phone is not in the desktop charger or properly tilted, then a test is made at step  208  to determine if the phone is already in speakerphone mode. If so, speakerphone mode is disabled e.g. by an interrupt at step  210 . If the phone is not in speakerphone mode  208 , no action is taken. An optional step shown in FIG. 2 sets the speakerphone flag after step  212  to indicate that the phone was in speakerphone mode. Once the speakerphone flag is set, a later detection of the proper tilt or presence in the desk charger will automatically cause the phone to enter the speakerphone mode. 
     If the system is found to be in speakerphone mode at step  208 , step  209  tests to see if tilt has been inactive for more than x seconds where x is preferably between 1 and 3. If so, then the speakerphone is disabled via interrupt. If not, control returns so that no action is taken. This prevents bounce operations for example, when the speakerphone is on the table and the table is shaken. This could otherwise cause bouncing in the contact of the tilt sensor. 
     In addition, picking up the phone to look at the display, for example, could end the speakerphone mode. According to this system, a certain amount of time is provided for actions such as these. In this way, the speakerphone mode persists even when the phone is moved. 
     Although only a few embodiments have been disclosed in detail above, those with ordinary skill in the art certainly understand that modifications are possible in the preferred embodiment. All predictable modifications are intended to be encompassed within the following claims.