Abstract:
A system for controlling volume includes: a key input unit ( 1 ) for receiving user operations, and generating a corresponding controlling signal according to each operation; an MCU (Microprogrammed Control Unit) ( 2 ) for comparing an elapsed time of the user continuously operating the key input unit with a preset time, and generating PWM (Pulse-Width Modulation) pulses according to the comparison result; and a volume effect IC (Integrated Circuit) ( 3 ) for adjusting volume by 1 unit according to the PWM pulses if the elapsed time is less than or equal to the preset time, and setting volume as mute or adjusting volume by 10 units if the elapsed time is greater than the preset time according to a predefined system status during which the user presses the key input unit. The MCU includes a CPU (Central Processing Unit)( 20 ), a timer ( 22 ), and a memory ( 23 ). A related method is also disclosed.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to electronic systems and methods for controlling volume of audio output devices, and particularly to a system and method for controlling sound volume according to an elapsed time of operation of a manual input unit.  
         [0003]     2. Background of the invention  
         [0004]     Presently, there are many kinds of audio output apparatuses used for amplifying audio signals of devices such as loudhailers, TVs and MP3 (Moving Picture Experts Group, audio layer  3 ) players. These audio output apparatuses are known as “audio frequency amplifier apparatus,” and are used to adjust the output voltage of the device according to manual adjustment operations and corresponding adjustment commands.  
         [0005]     A conventional audio output apparatus provides a single key for adjusting volume, and a separate muting key for muting the volume. The apparatus cannot simultaneously adjust volume and perform muting by operation of a single key. Additionally, the apparatus generally adjusts volume from a minimum amount to a maximum amount level by level. This takes much time, which often inconveniences users.  
         [0006]     Accordingly, what is needed is a system and method for quickly and conveniently adjusting volume according to user need.  
       SUMMARY OF THE INVENTION  
       [0007]     A main objective of the present invention is to provide a system and method for efficiently and quickly adjusting sound volume and setting volume as mute according to an elapsed time that a user continuously operates a key input unit.  
         [0008]     To accomplish the above objective, a system for controlling sound volume in accordance with a preferred embodiment of the present invention comprises: an key input unit for receiving a user operation, generating a controlling signal according to each operation, and transmitting the controlling signal; an MCU (Microprogrammed Control Unit) for determining a mode of adjusting volume according to the controlling signal and an elapsed time of the user continuously operating the key input unit; and a volume effect IC (Integrated Circuit) for setting volume as mute or adjusting volume according to the PWM pulses. The key input unit comprises an “increase” key and a “decrease” key. The MCU comprises a timer for recording the elapsed time of the user continuously operating the key input unit, a memory for storing controlling programs, a PWM (Pulse-Width Modulation) pin; and a CPU (Central Processing Unit) for receiving the controlling signal, comparing the elapsed time with a preset time, generating PWM pulses with a corresponding duty ratio according to the comparison result, and transmitting the PWM pulses via the PWM pin. The volume effect IC adjusts volume by 1 unit if the elapsed time is less than or equal to the preset time, sets volume as mute if the elapsed time is greater than the preset time during a preliminary status of the system, and adjusts volume by 10 units if the elapsed time is greater than the preset time during a volume adjusting status of the system.  
         [0009]     In addition, the present invention provides a method for controlling sound volume using the above-described system, the method comprising the steps of: (a) providing a key input unit comprising an “increase” key and a “decrease” key, for receiving a user operation and generating a corresponding controlling signal according to the operation; (b) providing an MCU to determine whether an elapsed time of the user continuously operating the key input unit is greater than a preset time; (c) adjusting volume by a first amount if the elapsed time is less than or equal to the preset time; (d) adjusting volume by a second amount if the elapsed time of the user pressing the “increase” key is greater than the preset time; and (e) setting mute if the elapsed time of the user pressing the “decrease” key is greater than the preset time.  
         [0010]     Further, the present invention provides another method for controlling sound volume using the above-described system, the method comprising the steps of: (a) providing a key input unit for receiving a user operation, and generating a controlling signal according to the operation; (b) providing an MCU to determine whether an elapsed time of the user continuously operating the key input unit is greater than a preset time; (c) adjusting volume by a first amount if the elapsed time is less than or equal to the preset time; and (d) adjusting volume by a second amount if the elapsed time is greater than the preset time.  
         [0011]     In summary, the system and method for controlling volume are quick and efficient, without the need for adjusting volume level by level. 
     
    
       [0012]     Other objects, advantages and novel features of the present invention will be drawn from the following detailed description with reference to the attached drawings, in which:  
       BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  is a block diagram of hardware infrastructure of a system for controlling sound volume in accordance with the preferred embodiment of the present invention, the system comprising a key input unit;  
         [0014]      FIG. 2  is a schematic diagram showing different modes of adjusting volume when a user operates the key input unit during a preliminary status of the system;  
         [0015]      FIG. 3  is a schematic diagram showing different modes of adjusting volume when the user operates the key input unit during a volume adjusting status of the system;  
         [0016]      FIG. 4  is a flowchart of operating the key input unit to adjust volume during the preliminary status; and  
         [0017]      FIG. 5  is a flowchart of operating the key input unit to adjust volume during the volume adjusting status. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0018]      FIG. 1  is a block diagram of hardware infrastructure of the system for controlling sound volume (hereinafter, “the system”) in accordance with the preferred embodiment of the present invention. The system comprises a key input unit  1 , an MCU (Microprogrammed Control Unit)  2 , and a volume effect IC (Integrated Circuit)  3 . A user performs press operations on the key input unit  1 . The key input unit  1  then generates a controlling signal according to each operation, and transmits the controlling signal to the MCU  2 . The key input unit  1  comprises an “increase” key (symbolically depicted as a “+” key) and a “decrease” key (symbolically depicted as a “−” key). The MCU  2  controls the volume effect IC  3  to adjust volume according to the controlling signal and an elapsed time of a user continuously operating the key input unit  1 . The MCU  2  comprises a CPU (Central Processing Unit)  20 , a PWM (Pulse-Width Modulation) pin  21 , a timer  22 , and a memory  23 . The CPU  20  receives the controlling signal from the key input unit  1 , compares the elapsed time with a preset time T 1 , generates PWM pulses with a corresponding duty ratio according to the comparison results, and transmits the PWM pulses to the volume effect IC  3  via the PWM pin  21 . The elapsed time equals a time of the user continuously pressing the key input unit  1 , and is recorded by the timer  22 . The memory  23  stores controlling programs. The memory  23  may be a ROM (Read-only Memory), a RAM (Random Access Memory), a volatile memory (such as DRAM, SRAM), or a non-volatile memory (such as EPROM, Flash memory). The volume effect IC  3  sets volume as mute or adjusts volume according to the PWM pulses from the CPU  20 . In the preferred embodiment, the total volume is set as 100 units, thereby the changeable volume of each unit is set as 1. When the elapsed time is less than or equal to the preset time T 1 , the volume effect IC  3  adjusts volume by 1 unit. When the elapsed time is greater than the preset time T 1 , the volume effect IC  3  sets volume as mute or adjusts volume by 10 units according to a system status during which the user presses the key input unit  1 . The status is either a preliminary status or a volume adjusting status. The preliminary status is also called “normal working status.” The preliminary status means that nobody operates the key input unit  1 ; and in the case where the system is used in a device such as a TV, an OSD (On-Screen Display) is not shown. The volume adjusting status means that the user operates the key input unit  1 , and the OSD is shown.  
         [0019]      FIG. 2  is a schematic diagram showing different modes of adjusting volume when the user operates the key input unit  1  during the preliminary status. When the user presses the “increase” key on the key input unit  1 , the system enters the volume adjusting status, and the volume effect IC  3  increases volume by 1 unit if an elapsed time of pressing the key is less than or equal to the preset time T 1 . Then the system returns to the volume adjusting status as soon as the user releases the “increase” key. Alternatively, the volume effect IC  3  increases volume by 10 units if the elapsed time is greater than the preset time T 1 . Then the system returns to the volume adjusting status as soon as the user releases the “increase” key. In contrast, when the user presses the “decrease” key in the key input unit  1 , the system enters the volume adjusting status, the volume effect IC  3  decreases volume by 1 unit if the elapsed time is less than or equal to the preset time T 1 . Then the system returns to the volume adjusting status as soon as the user releases the “decrease” key. Alternatively, the volume effect IC  3  sets volume as mute if the elapsed time is greater than the preset time T 1 . If the user presses the “increase” key while the system is mute, the system is recovered to a former volume, and returns to the volume adjusting status. In contrast, if the user presses the “decrease” key while the system is mute, the system maintains mute. The system returns to the preliminary status from the volume adjusting status when an elapsed time of no press input is greater than a preset time T 2 .  
         [0020]      FIG. 3  is a schematic diagram showing different modes of adjusting volume when the user operates the key input unit  1  during the volume adjusting status. When the user presses the “increase” key on the key input unit  1 , the volume effect IC  3  increases volume by 1 unit if an elapsed time of pressing the key is less than or equal to the preset time T 1 . Then the system returns to the volume adjusting status as soon as the user releases the “increase” key. Alternatively, the volume effect IC  3  increases volume by 10 units if the elapsed time is greater than the preset time T 1 . Then the system returns to the volume adjusting status as soon as the user releases the “increase” key. In contrast, when the user presses the “decrease” key on the key input unit  1 , the volume effect IC  3  decreases volume by 1 unit if the elapsed time of pressing the key is less than or equal to the preset time T 1 . Then the system returns to the volume adjusting status as soon as the user releases the “decrease” key. Alternatively, the volume effect IC  3  decreases volume by 10 units if the elapsed time is greater than the preset time T 1 . Then the system returns to the volume adjusting status as soon as the user releases the “decrease” key. The system enters the preliminary status from the volume adjusting status when an elapsed time of no press input is greater than the preset time T 2 .  
         [0021]      FIG. 4  is a flowchart of operating the key input unit  1  to adjust volume during the preliminary status. In step S 400 , the key input unit  1  receives a user operation, and transmits a corresponding controlling signal to the CPU  2 . In step S 401 , the CPU  20  receives the controlling signal, and the system enters the volume adjusting status. In step S 402 , the timer  22  records an elapsed time of the user continuously operating the key input unit  1 . In step S 403 , the CPU  20  determines whether the user has pressed the “decrease” key, according to the controlling signal. If the user has pressed the “decrease” key, the procedure goes directly to step S 407  described below. Otherwise, if the user has pressed the “increase” key, in step S 404 , the CPU  20  determines whether the elapsed time is greater than the preset time T 1 . If the elapsed time is less than or equal to the preset time T 1 , in step S 405 , the CPU  2  generates PWM pulses with a corresponding duty ratio, and transmits the PWM pulses to the volume effect IC  3  via the PWM pin  21 . Then, the volume effect IC  3  increases volume by 1 unit according to the PWM pulses, whereupon the procedure goes to step S 413  described below. If the elapsed time is greater than the preset time T 1 , in step S 406 , the volume effect IC  3  increases volume by 10 units, whereupon the procedure goes to step S 413  described below.  
         [0022]     In step S 407 , the CPU  20  determines whether the elapsed time of the user continuously pressing the “decrease” key is greater than the preset time T 1 . If the elapsed time is less than or equal to the preset time T 1 , in step S 408 , the volume effect IC  3  decreases volume by 1 unit, whereupon the procedure goes to step S 413  described below. If the elapsed time is greater than the preset time T 1 , in step S 409 , the volume effect IC  3  sets volume as mute. In step S 410 , the key input unit  1  receives a next user operation, and transmits a corresponding controlling signal to the CPU  2 . In step S 411 , the CPU  20  receives the controlling signal, and determines whether the user has pressed the “increase” key, according to the controlling signal. If the user has pressed the “decrease” key, the procedure returns to step S 409  described above, and the system maintains mute. If the user has pressed the “increase” key, in step S 412 , the volume effect IC  3  sets volume as un-mute, and the system is recovered to a former volume, whereupon the procedure goes to step S 413 .  
         [0023]     In step S 413 , the system enters the volume adjusting status. In step S 414 , the CPU  20  determines whether an elapsed time of no press input is greater than the preset time T 2 . If the elapsed time is less than or equal to the preset time T 2 , the procedure returns to step S 413 . If the elapsed time is greater than the preset time T 2 , in step S 415 , the system returns to the preliminary status.  
         [0024]      FIG. 5  is a flowchart of operating the key input unit  1  to adjust volume during the volume adjusting status. In step S 500 , the key input unit  1  receives a user operation, and transmits a corresponding controlling signal to the CPU  20 . In step S 501 , the timer  22  records an elapsed time of the user continuously operating the key input unit  1 . In step S 502 , the CPU  20  determines whether the user has pressed the “decrease” key, according to the controlling signal. If the user has pressed the “decrease” key, the procedure goes to step S 506  described below. Otherwise, if the user has pressed the “increase” key, in step S 503 , the CPU  20  determines whether the elapsed time is greater than the preset time T 1 . If the elapsed is less than or equal to the preset time T 1 , in step S 504 , the CPU  2  generates PWM pulses with a corresponding duty ratio, and transmits the PWM pulses to the volume effect IC  3  via the PWM pin  21 . Then the volume effect IC  3  increases volume by 1 unit according to the PWM pulses, whereupon the procedure goes directly to step S 509  described below. If the elapsed time is greater than the preset time T 1 , in step S 505 , the volume effect IC  3  increases volume by 10 units, whereupon the procedure goes directly to step S 509  described below.  
         [0025]     In step S 506 , the CPU  20  determines whether the elapsed time of the user pressing the “decrease” key is greater than the preset time T 1 . If the elapsed time is less than or equal to the preset time T 1 , in step S 507 , the volume effect IC  3  decreases volume by 1 unit, whereupon the procedure goes directly to step S 509  described below. If the elapsed time is greater than the preset time T 1 , in step S 508 , the volume effect IC  3  decreases volume by 10 units, whereupon the procedure goes to step S 509 .  
         [0026]     In step S 509 , the system returns to the volume adjusting status. In step S 510 , the CPU  20  determines whether an elapsed time of no press input is greater than the preset time T 2 . If the elapsed time is less than or equal to the preset time T 2 , the procedure returns to step S 509 . If the elapsed time is greater than the preset time T 2 , in step S 511 , the system enters the preliminary status.  
         [0027]     Although the present invention has been specifically described on the basis of a preferred embodiment and preferred methods, the invention is not to be construed as being limited thereto. Various changes or modifications may be made to the embodiment and methods without departing from the scope and spirit of the invention.