Abstract:
A portable radio terminal with an infrared communication function prevents consumption power from increasing when a radio communication function and an infrared communication function are used at a same time. A radio communication function section is judged whether in radio communication or not, and a driving current of an light emitting element in an infrared communication function section. The driving current of the light emitting element for an infrared communication is controlled in accordance with an operation of the radio communication function section, therefore, it is possible to loosen a condition for enabling infrared communication. As to restrictions for outputs from light emitting elements, a driving current of a light emitting element is controlled or plural light emitting elements having respective outputs are selectively driven.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a portable radio terminal with an infrared communication function and a communication method for the portable radio terminal with the infrared communication function and more particularly to the portable radio terminal with the infrared communication function and the communication method for the portable radio-terminal with the infrared communication function for power control when infrared communication and radio communication are executed simultaneously. 
   2. Description of the Related Art 
   A radio communication function transmits radio waves in order to carry out radio communications. Transmission power to transmit radio waves generally requires a large consumption of electric current (for example, an RCR STD-27 digital radiophone system, such as a PDC (Personal Digital Cellular) system, is used as a radio communication system). 
   An infrared communication function also requires a large consumption of electric current in order to make an emitting element emit. 
   Therefore, in a case that an infrared communication function is provided in a radio portable information terminal using a battery as a power source, when the battery voltage drops, it becomes impossible to use the radio communication function and the infrared communication function simultaneously. 
   A terminal is known, in which irrespective of the battery voltage, it is restricted to use the radio communication function and the infrared communication function simultaneously from the beginning in order to give a longer lifetime of the battery for the radio portable information terminal, and a battery capacity and a power source circuit are minimized. 
   In these known techniques, there are the following problems. 
   A first problem is that the radio communication function and the infrared communication function can not be used simultaneously. As its causes, the infrared communication function requires a large consumption electric current and a communicable distance of the infrared communication function is required to be kept at a constant distance or more. 
   A second problem is that a large battery capacity is required to use the radio communication function and the infrared communication function simultaneously and a battery becomes large in size. As its cause, both of the radio communication function and the infrared communication function require large consumption of electric current. 
   Therefore, it is desirable to control an increase of consumption electric of current when the radio communication function and the infrared communication function are executed simultaneously. 
   SUMMARY OF THE INVENTION 
   In view of the above, it is an object of the present invention to provide a portable radio terminal with an infrared communication function and a communication method therefore, capable of controlling an increase of electric current consumption when a radio communication function and the infrared communication function are executed simultaneously. 
   According to a first aspect of the present invention, there is provided a communication method for a portable radio terminal with an infrared communication function, the communication method including: a step of judging whether a radio communication function section is in radio communication or not; and a step of controlling a driving current of a light emitting element in an infrared communication function section in accordance with a judgment. 
   Also, a preferable mode is one wherein the driving current of the light emitting element in the infrared communication function section is controlled in accordance with a transmission power value of the radio communication function section. 
   According to a second aspect of the present invention, there is provided a communication method for a portable radio terminal with an infrared communication function, the communication method including: a step of judging whether a radio communication function section is in radio communication or not; and a step of selecting the infrared communication function among a plurality of infrared communication functions in accordance with a judgement. 
   In the foregoing second aspect, a preferable mode is one wherein the infrared communication function is selected among the plurality of infrared communication functions in accordance a transmission power value of the radio communication function section. 
   Also, a preferable mode is one wherein it is notified that a communicable distance of the infrared communication function is restricted. 
   According to a third aspect of the present invention, there is provided a portable radio terminal with an infrared communication function including: a radio communication function section; an infrared communication function section; and an information processing section for detecting a function state of the radio communication function section and for controlling an infrared output from the infrared communication function section. 
   Also, a preferable mode is one wherein the function state is a radio output of the radio communication function section, and the infrared output is controlled to be small when the radio output is larger. 
   Also, a preferable mode is one wherein the small infrared output corresponds to restricting a communicable distance of the infrared communication function. 
   As described above, the portable radio terminal with the infrared communication function and the communication method for the portable radio terminal of the invention provide four effects. 
   First, it is possible to use the infrared communication function though the radio communication function is in radio communication; because it is judged while in infrared communication whether it is in radio communication or not. When it is in radio communication, the driving current of the light emitting element is controlled and the driving current value is restricted. 
   Second, it is possible to extend battery lifetime because it is possible to select a driving current of the light emitting element in accordance with a transmission power value of the radio communication function section. 
   Third, it is possible to make necessary battery capacity and power circuits small because, when the infrared communication function and the radio communication function are operated at the same time, the driving current of the light emitting element in the infrared communication function section and the driving current value is restricted. 
   Fourth, a person having this terminal can know whether a communicable distance of the infrared communication is restricted or not because the restriction is notified to the person having the terminal while the driving current of the light emitting value is restricted. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects, advantages, and features of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings in which: 
       FIG. 1  is a block diagram showing a portable radio terminal with an infrared communication function according to a first embodiment of the present invention; 
       FIG. 2  is a circuit block diagram showing details of a part of  FIG. 1 ; 
       FIG. 3  is an operational flowchart showing a communication method of the portable radio terminal with the infrared communication function according to a first embodiment of the present invention; 
       FIG. 4  is a circuit diagram showing further details of the portable radio-terminal with the infrared communication function according to a first embodiment of the present invention; 
       FIG. 5  is a block diagram showing a portable radio terminal with an infrared communication function according to a second embodiment of the present invention; and 
       FIG. 6  is an operational flowchart showing a communication method of the portable radio terminal with the infrared communication function according to a second embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Best modes for carrying out the present invention will be described in further detail using various embodiments with reference to the accompanying drawings. 
   First Embodiment 
     FIG. 1  is a block diagram showing a portable radio terminal with an infrared communication function according a first embodiment. As shown in  FIG. 1 , the portable radio terminal is provided with an information processing section  101 , an infrared communication function section  102 , a driving current control section  103 , a radio communication function section  104 , a battery  105 , a power source section  106 , an input device  107  and an output device  108 . 
   The information processing section  101  operates by program control and is connected to the infrared communication function section  102  bidirectionally. 
   The infrared communication function section  102  is capable of infrared-communicating with another apparatus (not shown) with the infrared communication function. 
   The information processing section  101  is connected to the driving current control section  103 . 
   The radio communication function section  104  capable of radio-communicating is connected to the infrared communication function section  102  bidirectionally. 
   The power source section  106  stabilizes a voltage of the battery  105  and distributes stabilized voltage to each section. 
   The input device  107  such as a keyboard is connected to the information processing section  101 . 
   The information processing section  101  is connected to the output device  108  such as an LCD (Liquid Crystal Display). 
   The infrared communication function section  102 , as shown in  FIG. 2 , is a light emitting element  201  such as an infrared LED (Light Emitting Diode) for emitting infrared signals, a light receiving element  202  such as a phototransistor for receiving infrared signals and a first signal conversion section  203  for coordinating a signal level between the light emitting element  201  and the information processing section  101  and a signal level between the light receiving element  202  and the information processing section  101 . 
   The driving current control section  103 , as shown in FIG.  2 , is provided with a current control section  204  changing a driving current of the light emitting element  201  in the infrared communication function section  102 . The current control section  204  can set a driving current value to a first current value, a second current value and a third current value. 
   The radio communication function section  104  is provided with a transmission power amplification section  205  and a transmission power control section  206 . The transmission power control section  206  controls and optimizes a transmission power in accordance with a distance from a base station and an usage situation. 
   The information processing section  101  is provided with a first control section (not shown) for outputting a control signal  211  controlling a driving current of the light emitting element  201  to the driving current control section  103  when the radio communication function section  104  is in radio communication, and a second control section (not shown) for outputting a switching signal  212  switching control levels of the driving current of the light emitting element  201 . 
     FIG. 4  shows a concrete circuit diagram of the block diagrams shown in  FIGS. 1 and 2 . 
   The light emitting element  201  is an infrared LED (Light Emitting Diode)  412 , and the light receiving element  202  is a photodiode  413 . 
   The first signal conversion section  203  is provided with a driver  414  for driving the infrared LED  412  and an amplifier  415  for amplifying electric signals from the photodiode  413 . 
   Analog electric signals amplified by the amplifier  415  are converted into digital signals by a comparator  416 . 
   A driver  417  coincides the digital signals with signals of the information processing section  101  as to a signal level. 
   The current control section  204  in the driving current control section  103  is provided with a current restriction resistor A  405 , a current restriction resistor B  406  and a current restriction resistor C  407  for restricting the driving current of the infrared LED  412 , a first FET (Field Effect Transistor)  401  to short-circuit the current restriction resistor A  405 , a second FET  402  for driving the first FET  401 , a third FET  403  to short-circuit the current restriction resistor A  405  and the current restriction resistor B  406 , a fourth FET  404  for driving the third FET  403 , a pull-up resistor A  408  and a pull-up resistor B  409 . 
     FIG. 3  shows an operation according to the first embodiment of the present invention. 
   When starting the infrared communication function is requested to the information processing section  101  by the input device  107  (Step S 301 ), the information processing section  101  judges whether the radio communication function section  104  is in radio communication or not before executing an infrared communication operation (Step S 302 ). When the radio communication function section  104  is not in radio communication, the information processing section  101  sets a driving current value of the light emitting element  201  in the infrared communication function section  102  to a first current value I- 1  for the current control section  204  in the driving current control section  103  (Step S 307 ). The first current value I- 1  gives no restriction to the driving current of the light emitting element  201 . 
   When the radio communication function section  104  is in radio communication, the information processing section  101  also judges a transmission power value of the radio communication function section  104  in accordance with information from the transmission power control section  206 . When the transmission power value is lower than a predetermined first threshold (Step S 304 : No), the information processing section  101  sets a driving current value of the light emitting element  201  in the infrared communication function section  102  to a second current value I- 2  for the current control section  204  in the driving current control section  103  (Step S 306 ). The second current value I- 2  restricts the driving current of the light emitting element  201 . When the transmission power value is higher than the predetermined first threshold (Step S 304 : YES), the information processing section  101  sets a driving current value of the light emitting element  201  in the infrared communication function section  102  to a third current value I- 3  for the current control section  204  in the driving current control section  103  (Step S 305 ). The third current value I- 3  further restricts the driving current of the light emitting element  201  more than the second current value I- 2 . 
   With these current restrictions, a consumption power of the light emitting element  201  is deduced and an arrival distance of infrared emitted from the light emitting element  201  is restricted. The output device  108  indicates that a communicable distance of the infrared communication is restricted in this way (Step S 308 ). As above described, after the driving current of the light emitting element  201  is determined based on battery voltage, the infrared communication operation is executed (Step S 309 ), and the infrared communication operation is finished (Step S 310 ). 
   Next, concrete descriptions will be given of the operation with the circuit diagrams ( FIGS. 1 ,  2  and  4 ) and the operational flowchart ( FIG. 3 ). 
   When not in radio communication (Step S 302 : No), the information processing section  101  outputs a signal of a HI (high) level to a control line  411  and outputs a signal of a LOW level to a control line  410  for the current control section  204  in the driving current control  103 . With these outputs, the fourth FET  404  is turned ON and the third FET  403  is also turned ON. Both sides of the current restriction resistor A  405  and the current restriction resistor B  406  are short-circuited, the driving current of the infrared LED  412  is restricted by the resistance value of the current restriction resistor C  407 , and the first current value I- 1  can be set. 
   In radio communication (Step S 302 : Yes), when a transmission power value is lower than a predetermined first threshold (Step S 304 : No), the information processing section  101  outputs a signal of a HI (high) level to the control line  410  and outputs a signal of a LOW level to the control line  411  for the current control section  204  in the driving current control  103 . The second FET  402  is turned ON and the first FET  401  is also turned ON. Therefore, both sides of only the current restriction resistor A  405  are short-circuited, the driving current of the infrared LED  412  is restricted by the total resistance value of the current restriction resistor B  406  and the current restriction resistor C  407 , and the second current value I- 2  can be set. 
   In radio communication (Step S 302 : Yes), when a transmission power value is higher than a first predetermined threshold (Step S 304 : Yes), the information processing section  101  outputs signals of LOW levels to a control line  410  and to a control line  411  for the current control section  204  in the driving current control section  103 . All of FETs are turned OFF, the driving current of the infrared LED  412  is restricted by the total resistance value of the current restriction resistor A  405 , the current restriction resistor B  406  and the current restriction resistor C  407 , and the second-current value I- 3  can be set. 
   In the first embodiment, the explanations are given in a case that one threshold is used for judgment of the transmission power value of the radio communication section and two restricted driving current values of the light emitting element are used. However, two and more thresholds may be used to judge detected results of transmission power values and three and more driving current values of light emitting elements may be used in accordance with the number of thresholds. 
   In the first embodiment, a case is described in that the radio communication function section has a function to control a transmission power, however, though there is no function controlling the transmission power, the driving current of the light emitting element is restricted only whether in radio communication or not, and thereby similar effects can be obtained. 
   Second Embodiment 
   A second embodiment according to the present invention will be described.  FIG. 5  shows a portable radio terminal with an infrared communication function according to the second embodiment of the present invention. 
   The portable radio terminal with the infrared communication function according to the second embodiment is different from that of the first embodiment in being provided with a second infrared communication function section  501  and a third infrared communication function section  502  instead of a driving current control section  103 . 
   A driving current of a light emitting element (not shown) in the second infrared communication function section  501  is set to a value lower than a driving current of a light emitting element in the first infrared communication function section  102 . 
   Further, a driving current of a light emitting element (not shown) in the third infrared communication function section  502  is set to a value lower than the driving current of the light emitting element in the second infrared communication function section  501 . 
     FIG. 6  shows an operation of the second embodiment. 
   When starting the infrared communication function is requested to an information processing section  101  by an input device  107  (Step S 601 ), the information processing section  101  judges whether a radio communication function section  104  is in radio communication or not before executing an infrared communication operation (Step S 602 ). 
   When the radio communication function section  104  is not in radio communication (Step S 602 : No), the information processing section  101  executes the infrared communication function by the first infrared communication function section  102  (Step S 606 ). No restriction is given to the driving current of the light emitting element in the first infrared communication function section  102 . 
   When the radio communication function section  104  is in radio communication (Step S 602 : Yes), the information processing section  101  judges the transmission power value of the radio communication function section  104  based on information from a transmission power control section  206 . 
   When the transmission power value is lower than a predetermined first threshold (Step S 603 : No), the information processing section  101  executes infrared communications using the second infrared communication function section  501  (Step S 605 ) and, at a same time, an output device  108  notifies to a person having the portable radio terminal that a communicable distance of the infrared communications is restricted (Step S 607 ). A restriction is given to the driving current of the light emitting element in the second infrared communication function section  501 . 
   When the transmission power value is higher than the predetermined first threshold (Step S 603 : Yes), the information processing section  101  executes infrared communications using the third infrared communication function section  502  (Step S 604 ) and, at a same time, the output device  108  notifies to the person having the portable radio terminal that a communicable distance of the infrared communications is restricted (Step S 607 ). A further restriction is given to the driving current of the light emitting element in the third infrared communication function section  502  rather than the second infrared communication function section  501 . 
   In this way, the infrared communication function is selected, the selected infrared communication operation is executed and the infrared communication operation is finished (Step S 608 ). 
   It is thus apparent that the present invention is not limited to the above embodiments but may be changed and modified without departing from the scope and spirit of the invention. 
   Finally, the present application claims the priority based on Japanese Patent Application No. Heill-235009 filed on Aug. 23, 1999, which is herein incorporated by reference.