Abstract:
The present invention relates to a portable telephone, which can be switched on/off by using the touch screen ( 20 ) of the portable telephone ( 10 )

Description:
BACKGROUND 
     The present invention relates to controlling the supply of power to a portable communication device of the type mentioned in the preamble of the independent claims. 
     Many portable communication devices, such as mobile telephones, personal communicators etc, normally require a “hardware power on system” for powering on. A “hardware power on system” is referred to as a system, which comprises a physical switch, controlling the power on of the portable communication device. 
     Other portable communication devices have a hinged front panel, a so-called a flip, which can be opened when the device is used for certain functions and which can be closed in order to reduce the bulk of the device when these functions are not required. 
     One example of such a device is the mobile telephone known from the patent GB-A-2 297 661 which has a flip which can be folded down to expose a touch screen display. When the flip is folded up against the touch screen display the screen can be operated by means of a keypad consisting of a plurality of buttons which extend through the flip and which can be pressed by a user into contact with the touch sensitive parts of the touch screen display. There is a flip position-indicating switch in the main body of the unit which can be operated by a switch activation device disposed in the flip. The flip position indicating switch and switch activation device co-operate to produce a mode change signal which is sent to the processor of the mobile phone and which indicates if the flip is open or closed. If the flip is closed a first set of functions is available to the user and if the flip is open a second set of functions is available to the user. Cellular telephones of this type can be switched on and off by a hardware switch which disconnects tie processor from the logic voltage supply in order to minimise unnecessary battery drainage caused by the logic voltage supply leakage current. 
     Thus a separate hardware switch is required which increases the manufacturing costs and, as it introduces a potential failure path, and also lowers the reliability of the mobile telephone. 
     It is also known to use “soft power control” for instance in personal computer systems, to be able to save power and extend battery lifetime. This is ordinarily done by the operator of the computer system powering on not using a “hard power on switch”. “Soft power control” in such a computer system normally comprise several power control modes, such as a “full power mode” and a sleep mode. In the “full power mode”, the main parts of the computer system are supplied with power and are active. In the “sleep mode”, one or more parts of the computer system are not supplied with power and are said to be inactive. In the “sleep mode”, the operator depresses a key on the keyboard to power on the main parts of the computer system. 
     It is known from U.S. Pat. No. 5,553,296 to use a touch screen for a power control function in a computer system, whereby the touch screen is employed to control a number of power modes, such as “full power mode” and “sleep mode” in the computer system. The touch screen detects a touch input by the operator from the touch screen. If the computer system is in a power down mode, a so-called “sleep mode”, the touch screen provides a main power on signal after the touch is detected. 
     U.S. Pat. No. 4,825,209 describes a remote control apparatus, which puts a transmitting portion, a receiving portion and an image display control portion thereof in an enabled state for a predetermined period of time after a touch panel is pressed to reduce power consumption. The press detection is done with push button switches in the corners of a remote control. 
     JP-A-8-212 006 describes switching on a flat panel indicator if any touch input is sensed. When there is no touch input for a predetermined time period, the flat panel is switched off. 
     One problem is that prior art portable communication devices, such as a mobile phone comprising a touch screen display, such as a touch screen LCD (Liquid Crystal Display), require additional mechanical on-off switches positioned at different locations, whereby the way to power up differs from device to device, even for similar devices of the same family. 
     Another problem is that these switches require space to be implemented in the portable communication devices. 
     Yet another problem is that today&#39;s portable communication devices, in particular portable telephones comprising a flip hang, must be provided with wires through the flip hinge if a hardware power on-off switch is provided thereon. 
     SUMMARY 
     The object of the invention is to solve the described problems and provide an improved portable telephone, in which the use of a separate hardware switch to switch on the device is unnecessary. Herein, portable telephones means: mobile telephones, cordless telephones and personal communicators. 
     Another object of the present invention is to improve the reliability of such a portable telephone and to reduce their manufacturing costs. 
     This is attained according to the present invention by means of a portable telephone in which the touch screen display is used for switching on the device, wherein a hardware switch is unnecessary. The touch screen display comprises at least one inner and one outer essentially transparent conducting plate which are movable in relation to each other between a first position, in which the plates are spaced apart and a second position, in which the plates are contacted to each other by the outer plate being depressed by a user of the portable telephone by means of an input means, such as a key pad or direct activation providing a pressure against the touch screen display, wherein a voltage controlled switch connected to said plates is adapted to turn on the power of the portable telephone upon receipt of a signal indicating that a power-on key has been depressed by the user. 
     An advantage of the present invention is that the invention simplifies the use of a portable telephone, compared to known technique. 
     Another advantage of the present invention is that no additional switch must be incorporated in the portable telephone. It is possible to use the image display of a portable telephone, independent on model for powering on. 
     The invention will now be described in more detail with reference to preferred embodiments and to the appended drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a perspective view of a portable telephone, according to the invention, comprising a touch screen display for controlling the supply of power to the portable telephone. 
     FIG. 2 shows a schematically block diagram of the touch screen display and the voltage controlled switch in a portable telephone according to the invention. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 shows a perspective view of a portable telephone  10 , provided with a touch screen display  20  for displaying information such as telephone number, signal strength, battery level, roaming information etc, and intended for receiving commands from the user, in a conventional way as well as the power-on function. The portable telephone  10  has a main body  3 , comprising a loudspeaker  13 , an antenna  15 , a microphone  16 , and a flip  4  movable in relation to the main body, which can be folded up against the main body  3 . The flip  4  has input means  70  for example a keypad with a plurality of keys  9 , which each correspond to a desired function. The function of each key  9  is determined by the software of the portable telephone  10 . The touch screen display  20  detects which key  9  has been pushed and carries out the desired function. Activating the power-on key  9 ′ causes the touch screen display  20  to register that the key  9 ′ has been pushed and causes a voltage controlled switch  2 ′ (see FIG. 2) to connect the power supply  50  (not shown). 
     FIG. 2 is a schematically block diagram of an embodiment of the touch screen display  20  connected to the voltage controlled switch  2  for connecting and disconnecting the power supply  50  such as a battery to the portable telephone  10 . The power supply  50  is connected to the input terminal IN reg  of a first voltage regulator  60   a , which can provide a fixed logic voltage supply Von on an output terminal OUT reg . The voltage regulator  60   a  is always enabled to provide the high input voltage Von to the control means  5  on its input terminal IN Von . The power supply  50  is also connected to the input terminal IN reg  of a second voltage regulator  60   b , which can provide a logic voltage supply Vcc on its output terminal OUT reg . The voltage regulator  60   b  is enabled to provide the logic voltage supply Vcc to the control means  5  on its input terminal IN Vcc , when it receives a high input voltage on its ENABLE terminal. This causes the control means  5  to start its logic, which controls the power-on function. The logic is of conventional type for controlling a touch screen display also of conventional type and the function thereof will not be described in more detail The logic comprises at least a main microprocessor, as well as other control circuits of known technologies. 
     The way of applying a high input voltage to the ENABLE terminal of regulator  60   b , which thereby allows the power supply to be connected to the input terminal IN Vcc  of the control means  5 , to power-on the device will now be described in more detail. 
     The touch screen display  20  comprises at least two plates, one inner plate  30  and one outer plate  40  spaced apart, which are connected via four signal lines  31 ,  32 ,  41 ,  42  to the terminals of the control means  5  in a conventional way. The outer plate  40 , intended to be depressed by a user, is preferably connected via signal line  41  provided with a pull-up resistor  19  and the inner plate  30  is connected to ground when the mobile is powered down. When the portable telephone is powered. down, Vcc is OV (low) and Von, for instance 5 V (high), All signals on the output terminals  11 - 16  and  18  of the control means  5  are then low. Thus, in this mode one of the plates  40  has high potential and the other plate  30  has low potential. 
     Now referring to FIG. 1, when the user depresses a power-on key on the input means  70  provided on the touch screen display  20 , the plate  40  that is connected via the pull up resistor  19  will be forced to ground, whereby the signal in signal line  41  will go low. A signal will be sent via signal line  17  to the ENABLE terminal of regulator  60   b , which will provide an enabling current, or in other words, a high potential, to the terminal IN Vcc . of the control means  5 , thereby starting its logic to obtain a power-on function. The control means  5  will after it has set “hold_Vcc” on its terminal  14 , start to interpret the meaning of the activation, starting with detecting the touch position in a conventional way. 
     One or more keys  9  of the keypad  70  can be assigned a power-on function by the software of the control means  5 . 
     If it were not on the “on button position”, “hold_Vcc” on signal line  14  is released again and the portable telephone will power down again, provided that the pressure on touch screen display  20  is released, otherwise the portable telephone will stay on. 
     In this way switching on of the portable telephone is obtained without requiring any special on hardware switch. 
     For one embodiment the touch screen display comprises a resistive type of touch screen display, but is not limited thereto. The resistive touch screen display comprises two sheets of clear material, which is conducting. 
     The time period between performing the power-on function will vary depending on application. Thus, the touch screen display must be depressed for a predetermined period of time before performing. the power on command This prevents accidental power on from an inadvertent touching of the screen. 
     In alternative embodiments, a plurality of power on modes may exist between the fill power up and the full power down mode. 
     Shutting down the portable telephone is performed in a conventional way. One of the keys in the input means  70  can be assigned an “off” function by the software of the control means. 
     The input means is for instance a movable housing element, such as a flip, comprising a push-through keyboard. It is also possible to use direct activation providing a pressure against the touch screen display  20 , whereby the touch screen display can comprise a user data area ( 20 ′) divided into multiple sub-areas corresponding to the keys of the keypad. 
     While the invention has been illustrated by a portable telephone with a flip, it is also possible to use other arrangements of keypads, for instance of sliding type. 
     The voltage regulator  60   a  which is always enabled to provide a high input voltage to the control means  5  can be substituted by any other connection means, provided that the components in the control means  5  are not destroyed. 
     The voltage regulator  60   b  can be substituted by any other voltage-controlled switch. 
     A “pull down” solution is also possible. 
     While the advantages of the invention are most fully realised when no separate hardware switch is used to switch the processor on and off, it is also possible to provide the portable telephone with a separate hardware switch if so desired in order to control the power supply to some other component of the portable telephone, as well as the processor.