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Background of the Invention
1. Field of the Invention
The present invention relates to a method for controlling a back light in a portable radio communication terminal, and in particular, to a method for controlling the back light by using a clock function in a portable radio communication terminal.
2. Description of the Related Art
A portable radio communication terminal generally has a back light function to offer convenience to the user, when used in a dark condition.
Referring to Fig. 1, a portable radio communication terminal having the back light function includes a display 10, a keypad 20, and a back light composed of a plurality of light emitting diodes (LED) 30.
Fig. 2 illustrates a known schematic block diagram of a back light control device. With reference to the drawing, a controller 100 controls an overall operation of the portable radio communication terminal. The controller 100 is a one-chip microprocessor having a ROM (read only memory) into which a control program is stored, and a RAM (random access memory) into which data generated in the course of executing the control program is temporarily stored. A timer
600 for performing a clock function displays current time on the display 10 under the control of the controller 100. A keypad 200 is composed of a number of numeric keys and function keys to generate key data according to a key depression of the user. The key data generated is provided to the controller 100. A counter 300 begins counting the time under the control of the controller 100, and provides the controller 100 with a control signal after a lapse of a predetermined time. A power controller 400 connected to the controller 100 provides a back light 8 00 with a supply voltage under the control of the controller 100. The back light 800 is composed of a plurality of LEDs.
Fig. 3 illustrates a flow chart for controlling the back light control device shown in Fig. 2 according to the prior art.
Now, referring to Figs. 2 and 3, if the user operates the keypad 200, the controller 100 checks at a step 510 whether key data is received from the keypad 200. If the key data is received, the power controller 400 provides the back light 800 with the supply voltage under the control of the controller 100 at a step 520, so as to turn on the back light 800. Thereafter, the controller 100 enables the counter 3 0 0 at a step 53 0. The counter 300 provides the controller 100 with a counting completion signal after a lapse of a predetermined time. If the counter 300 generates the counting completion signal at a step 540, the power
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controller 400 will cut off the supply voltage being supplied to the back light 800 under the control of the controller 10 0 at a step 55 0, so as to turn off the back light 800. However, if the counter 300 has not generated the counting completion signal at the step 540, the procedure will return to the step 520 to repeat the foregoing steps 520 to 540.
Further, the portable radio communication terminal uses a battery to supply the power. Thus, it is very important to reduce a power consumption of the portable radio communication terminal so as to extend an operating time of the battery.
Table 1 expresses current consumptions of the portable
radio communication terminal according to operating modes, in which one LED consumes about 20mA in a back light mode. It can be noted from Table 1 that the power consumption in the back light mode is much higher than that in the stand-by mode. Further, it is general that the portable radio communication terminal is commonly used in a bright condition rather than in a dark condition.
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However, upon receiving any key data, the conventional back light control device turns on the back light unconditionally, thereby wasting the power unnecessarily in the daytime. Thus, the operating time of the battery may be reduced undesirably. In particular, in case the portable radio communication terminal is installed in a hands-free kit, the back light is always turned on even if the user does not operate the keypad, which causes an unnecessary power consumption and a heat radiation during the daytime.
Summary of the Invention
It is therefore an object of the present invention to provide a method for turning off a back light during the daytime by using a clock function in a portable radio communication terminal.
To achieve the above and other objects, a method for controlling a back light by using a clock function in a portable radio communication terminal having a keypad and a timer for performing the clock function, includes the steps of checking whether current time of the timer is within a predetermined time period; setting a back light-off mode, if the current time is within the predetermined time period; and upon receiving key data, managing the key data without turning on the back light.
Brief Description of the Accompanying Drawings
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The above and other objects, features and advantages of the present invention will become more apparent in the light of the following detailed description of an exemplary embodiment thereof taken with the attached drawings in which:
Fig. 1 is a front view of a portable radio communication terminal having a back light function;
Fig. 2 is a schematic block diagram of a known back light control device;
Fig. 3 is a flow chart for controlling a back light according to the prior art; and
Fig. 4 is a flow chart for controlling a back light by-using a clock function according to a preferred embodiment of the present invention.
Detailed Description of the Preferred Embodiment
A preferred embodiment of the present invention will be described in detail referring to the attached drawings, in which the like reference numerals denote the same elements in the drawings, for understanding. Though the specific embodiment such as the detailed flow chart will be exemplarily defined and described in detail to clarify the subject matter of the present invention, the present invention may be implemented with the description of the present invention by those skilled in the art even without the details. In addition, an unnecessary detailed
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description of widely known functions and constructions may be avoided here.
Now, referring to Figs. 2 and 4, descriptions will be made on a procedure for controlling a back light by using a clock function according to a preferred embodiment of the present invention. At a step 700, the timer 600 provides the controller 100 with current time T. The controller 100 checks at a step 710 whether the current time T is within a time period of daytime (for example, a time period between 8 a.m. and 6 p.m.) . Of course, the user may freely change a definition of the daytime, at discretion. If the current time is not within the time period between 8 a.m. and 6 p.m., the controller 100 sets an back light-on mode at a step 720. In the meantime, if the user operates the keypad 200, the controller 100 checks at a step 73 0 whether key data is received from the keypad 200. If the key data is received, the power controller 400 provides at a step 750 the back light 800 with the supply voltage under the control of the controller 100, to turn on the back light 800. If the key data is not received at the step 730, the controller 100 checks at a step 740 whether the portable radio communication terminal is installed in the hands-free kit. If the portable radio communication terminal is installed in the hands-free kit, the controller 100 turns on the back light 800 at the step 750.
However, if the current time is within the time period
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between 8 a.m. and 6 p.m. at the step 710, the controller 100 sets a back light-off mode at a step 760. In the interim, if the user operates the keypad 200, the controller 100 manages the key data input without turning on the back light at a step 780. Further, even if the portable radio communication terminal is installed in the hands-free kit at a step 770, the controller 100 will not turn on the back light 800.
As can be clearly appreciated from the foregoing descriptions, the portable radio communication terminal of the invention turns off the back light during the daytime to reduce the power consumptions. Therefore, it it; possible not only to extend an operating time of the battery but also to prevent an increase of the temperature due to the heat radiation of the portable radio communication terminal.
Although a preferred embodiment of the present invention has been described in detail hereinabove, it should be clearly understood that many variations and/or modifications of the basic inventive concepts herein taught which may appear to those skilled in the art will still fall within the spirit and scope of the present invention as defined in the appended claims.
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We Claim:
1. A method for controlling a back light in a portable radio communication terminal having a keypad with a plurality of keys, and a timer for performing a clock function, comprising the steps of:
-determining whether current time of the timer is within a predetermined time period;
-automatically determining whether the portable radio terminal is operating in a hands-free mode:
-setting a back light-off mode when the current time is within said predetermined time period;
-managing input key data which is generated by depressing any one of the plurality of keys on the keypad, without turning on the back light during the back light-off mode and/or during the hands-free mode;
-setting a back light-on mode when the current time is not within said predetermined time period;
-turning on the back light upon receiving the input key data during the back light-on mode; and
-turning on the back light when the portable radio terminal is operating in the hands-free mode during the back light-on mode.
2. The method as claimed in claim I, wherein said predetermined time period is a time
period of daytime.
3. The method as claimed in claim 1, comprising the additional step of setting a back
light-off mode when the current time is within said predetermined time period and the
portable radio terminal is operating in the hands-free mode.
This invention relates to a method for reducing power consumption in a portable radio communication terminal by selectively preventing back light operation using daylight hours. The portable radio communication terminal checks whether current time of the timer is within a predetermined period of daytime. If the current time is within the period of daytime, the portable radio communication terminal is set to a back light-off mode. In this condition, if key data is received, the portable radio communication terminal manages the key data without turning on the back light. Therefore, it is possible not only to extend an operating time of the battery but also to prevent an increase of the temperature due to the heat radiation of the portable radio communication terminal.
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