Abstract:
An apparatus ( 10 ) for adjusting sound volume for an audio system includes a controller ( 101 ) connected to an amplifier ( 40 ) of the audio system for controlling amplification of the amplifier, and a first circuit ( 102 ) for adjusting the sound volume. The controller includes a microprogrammed control unit ( 1010 ), a random-access memory ( 1012 ), and an electrically erasable programmable read-only memory ( 1014 ). The first circuit includes an attenuation circuit ( 1022 ) connected to a tuner ( 20 ) of the audio system for attenuating input audio signals, and a switch ( 1024 ). An input end of the switch is connected to the tuner, an output end of the attenuation circuit and the microprogrammed control unit; and an output end of the switch is connected to an audio processor ( 30 ). The apparatus enables a user to freely adjust an average level of sound produced by the audio system, and simultaneously avoid being bothered by loud transmissions.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is related to a copending U.S. patent application entitled “APPARATUS AND METHOD FOR ADJUSTING SOUND VOLUME FOR TELEVISIONS AND OTHER AUDIO SYSTEMS”, filed on the same day with the same applicant and assignee as the invention. The disclosure of the above identified application is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to apparatuses and methods for adjusting sound volume for televisions and other audio systems.  
         [0004]     2. Description of Prior Art  
         [0005]     At times, a television or radio may broadcast an unexpected, noisy transmission to a user due to a programming change or when there are problems with reception. For example, a television or radio program provider may intentionally broadcast an advertisement at an abruptly high volume so as to attract the user&#39;s attention. On other occasions, signals received by the television or radio may be interfered with by signals transmitted by other electronic devices, thereby generating static or other unwanted transmissions. Loud advertisements or unexpected noises are perhaps least likely to bother the user during the daytime or in an environment that is otherwise relatively noisy. However, the user is likely to be easily bothered late at night or in a relatively quiet environment.  
         [0006]     In order to overcome the above-mentioned problem, U.S. Pat. No. 5,130,665, issued on Jul. 14, 1992, discloses an audio volume controller. When the audio volume controller is in a control mode, the audio volume controller outputs audio signals whose volumes are between a predefined minimum volume and a predefined maximum volume. Therefore, the audio volume controller cannot output any audio signal whose volume is higher than the predefined maximum volume. This enables the user to avoid being bothered by loud noises. However, the user cannot freely adjust the average level of the sound produced by the audio volume controller in the control mode unless he/she switches the audio volume controller to exit the control mode. Thus, it is not convenient for the user to use the audio volume controller.  
       SUMMARY OF THE INVENTION  
       [0007]     Accordingly, a primary object of the present invention is to provide an apparatus for facilitating a user to not only freely adjust an average level of sound produced by an audio system according to his/her particular requirements, but also simultaneously avoid being bothered by loud transmissions.  
         [0008]     A second object of the present invention is to provide a method for facilitating a user to not only freely adjust an average level of sound produced by an audio system according to his/her particular requirements, but also simultaneously avoid being bothered by loud transmissions.  
         [0009]     In order to fulfill the above-mentioned primary object, the present invention provides an apparatus for adjusting sound volume for an audio system. The apparatus comprises a controller connected to an amplifier of the audio system for controlling amplification of the amplifier, and a first circuit for adjusting the sound volume. The controller comprises a microprogrammed control unit (MCU), a Random-Access Memory (RAM) connected to the MCU, and a nonvolatile memory connected to the MCU. The first circuit comprises an attenuation circuit for attenuating input audio signals, and a switch. An input end of the switch is connected to a tuner of the audio system, an output end of the attenuation circuit and the MCU, and an output end of the switch is connected to an audio processor of the audio system.  
         [0010]     The attenuation circuit comprises: a first resistor, a first end of the first resistor being connected to the tuner of the audio system; a second resistor, a first end of the second resistor being connected to a second end of the first resistor; a first diode, the anode of the first diode being connected to the second end of the first resistor; a second diode, the cathode of the second diode being connected to the cathode of the first diode; a third diode, the cathode of the third diode and the anode of the second diode being connected to a second end of the second resistor in parallel; a fourth diode, the anode of the fourth diode being connected to the anode of the third diode, the cathode of the fourth diode being connected to the second end of the first resistor; a third resistor, a first end of the third resistor being connected to the cathode of the first diode; a fourth resistor, a first end of the fourth resistor being connected to a second end of the third resistor, and a second end of the fourth resistor being connected to the anode of the fourth diode; a transistor, the base of the transistor being connected to the second end of the third resistor, the emitter of the transistor being connected to the first end of the third resistor, and the collector of the transistor being connected to the second end of the fourth resistor; and an integrated operational amplifier, the inverting input end of the integrated operational amplifier being connected to the second end of the first resistor, the non-inverting input end of the integrated operational amplifier being grounded, and the output end of the integrated operational amplifier being connected to the second end of the second resistor.  
         [0011]     In order to fulfill the above-mentioned second object, the present invention provides a method for adjusting sound volume for an audio system. The method comprises the following steps: (a) determining whether an apparatus for adjusting sound volume is in an attenuation mode; (b) controlling a switch to switch a circuit for adjusting sound volume to an attenuation mode, if the apparatus for adjusting sound volume is in the attenuation mode; (c) attenuating an input audio signal, the input audio signal being attenuated slightly if it is relatively “weak,” and the input audio signal being attenuated significantly if it is relatively “strong;” and (d) repeating steps (a) through (c) until the audio system is turned off.  
         [0012]     Other objects, advantages and novel features of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which: 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  is a simplified block diagram of part of a television having an apparatus for adjusting sound volume according to the present invention;  
         [0014]      FIG. 2  is a circuit diagram of an attenuation circuit of  FIG. 1 ;  
         [0015]      FIG. 3  is a graph of operation performance of the apparatus of  FIG. 1 ; and  
         [0016]      FIG. 4  is a flow chart of an exemplary method for adjusting sound volume according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0017]      FIG. 1  is a simplified block diagram of part of a television having an apparatus  10  for adjusting sound volume according to the present invention. The apparatus  10  can run in either of two operating modes: a normal mode and an attenuation mode. A viewer switches the apparatus  10  to either of the above-mentioned operating modes by use of an infrared remote control device  50  or a functional key (not shown) on the television itself. The apparatus  10  comprises a controller  101 , and a circuit  102  for adjusting the sound volume. The controller  101  comprises a microprogrammed control unit (MCU)  1010 , a Random-Access Memory (RAM)  1012 , and an Electrically Erasable Programmable Read-Only Memory (EEPROM)  1014 . The RAM  1012  and the EEPROM  1014  are both connected to the MCU  1010 . The controller  101  controls amplification of an amplifier  40  of the television. In other exemplary embodiments, the EEPROM  1014  may be replaced by any other suitable nonvolatile memory, such as a Read-Only Memory (ROM), an Erasable and Programmable Read-only Memory (EPROM), a flash memory, or the like.  
         [0018]     The operating mode of the circuit  102  corresponds to the operating mode of the apparatus  10 . That is, when the apparatus  10  is in the normal mode, the circuit  102  is also in a normal mode; similarly, when the apparatus  10  is in the attenuation mode, the circuit  102  is also in an attenuation mode. The circuit  102  comprises an attenuation circuit  1022 , and a switch  1024  for switching the operating mode of the circuit  102 . The input ends of the attenuation circuit  1022  and the switch  1024  are connected to a tuner  20  of the television. An output end of the attenuation circuit  1022  is connected the input end of the switch  1024 . The MCU  1010  is connected to the switch  1024 , for controlling the switch  1024  to switch the operating modes of the circuit  102  according to the operating mode of the apparatus  10 . The switch  1024  is connected to an audio processor  30 , for outputting thereto unadjusted audio signals or audio signals attenuated by the attenuation circuit  1022 .  
         [0019]      FIG. 2  is a circuit diagram of the attenuation circuit  1022 . In the present embodiment, the attenuation circuit  1022  comprises an integrated operational amplifier A, four resistors R, R 2 , R 3 , R 4 , four diodes D 1 , D 2 , D 3 , D 4 , and a transistor T. A first end of the resistor R 1  is connected to the tuner  20  of the television, and a second end of the resistor R 1  is connected to a first end of the resistor R 2 . The resistors R 3 , R 4 , the diodes D 1 , D 2 , D 3 , D 4 , and the transistor T together form a bridge circuit. The anode of the diode D 1  and the cathode of the diode D 4  are commonly connected to the second end of the resistor R 1 . The cathode of the diode D 1  is connected to the cathode of the diode D 2 , and the anode of the diode D 4  is connected to the anode of the diode D 3 . The anode of the diode D 2 , the cathode of the diode D 3  and the second end of the resistor R 2  are commonly connected to an output end of the integrated operational amplifier A. A first end of the resistor R 3  is connected to the cathode of the diode D 1 , and a second end of the resistor R 3  is connected to a first end of the resistor R 4 . A second end of the resistor R 4  is connected to the anode of the diode D 4 . The base of the transistor T is connected to the second end of the resistor R 3 . The emitter of the transistor T is connected to the first end of the resistor R 3 , and the collector of the transistor T is connected to the second end of the resistor R 4 . The inverting (−) input end of the integrated operational amplifier A is connected to the first end of the resistor R 2 . The non-inverting (+) input end of the integrated operational amplifier A is grounded, and the output end of the integrated operational amplifier A is connected to the input end of the switch  1024 .  
         [0020]     According to the above-described connections of the components of the attenuation circuit  1022 , the audio signal output by the integrated operational amplifier A is fed back to the inverting input end thereof by way of the resistor R 2  and the bridge circuit that is formed by the resistors R 3 , R 4 , the diodes D 1 , D 2 , D 3 , D 4  and the transistor T. That is, the resistor R 2  and the bridge circuit serve as a negative feedback circuit of the integrated operational amplifier A.  
         [0021]      FIG. 3  is a graph of operation performance of the apparatus  10 . The horizontal abscissa represents an audio signal Vi input to the apparatus  10 , and the vertical ordinate represents an audio signal Vo output from the apparatus  10 . A value Vim of the horizontal abscissa is a maximum possible audio signal input to the apparatus  10 . Values Voi and Vom of the vertical ordinate correspond to the value Vim, and respectively represent a maximum possible unadjusted audio signal and a maximum possible attenuated audio signal output by the apparatus  10 . The input audio signal Vi may correspond to a television program, an advertisement, or an unexpected noise such as interference. When the viewer selects the normal mode of the apparatus  10  through the infrared remote control device  50  or the functional key on the television itself, the MCU  1010  controls the switch  1024  to switch the circuit  102  to the normal mode. In such case, the audio signal transmitted by the tuner  20  of the television is input to the switch  1024 , and then is transmitted to the audio processor  30  of the television. The broken line of  FIG. 3  shows a relationship between the input audio signal Vi and the output audio signal Vo of the apparatus  10  in the normal mode. In short, the audio signal Vo output by the apparatus  10  in the normal mode is same as the audio signal Vi input to the apparatus  10 .  
         [0022]     When the viewer selects the attenuation mode of the apparatus  10  through the infrared remote control device  50  or the functional key on the television itself, the MCU  1010  controls the switch  1024  to switch the circuit  102  to the attenuation mode. In such case, the audio signal transmitted by the tuner  20  of the television is input to the attenuation circuit  1022 . The audio signal is input to the inverting input end of the integrated operational amplifier A via the resistor R 1 , and then is amplified and output by the integrated operational amplifier A. The audio signal amplified and output by the integrated operational amplifier A is fed back to the inverting input end thereof by way of the above-described negative feedback circuit. Because of the characteristics of the negative feedback circuit, when the audio signal input to the integrated operational amplifier A is relatively “weak,” such as an audio signal lower than a value Vi 1 , the audio signal fed back by the negative feedback circuit is relatively “weak” and has few effect on the audio signal input to the integrated operational amplifier A. As a result, according to connections of the components of the attenuation circuit  1022 , there is a linear attenuation relationship between the output audio signal and the input audio signal of the attenuation circuit  1022 .  
         [0023]     When the audio signal input to the attenuation circuit  1022  is relatively “strong,” such as an audio signal higher than the value Vi 1 , the audio signal fed back by the negative feedback circuit is relatively “strong” and has a great effect on the audio signal input to the integrated operational amplifier A. In such case, the audio signal input to the integrated operational amplifier A is attenuated significantly. As a result, according to the connections of the components of the attenuation circuit  1022 , there is a nonlinear attenuation relationship between the output audio signal and the input audio signal.  
         [0024]     The solid line of  FIG. 3  shows the linear and nonlinear attenuation relationships between the output audio signal Vo and the input audio signal Vi of the apparatus  10  in the attenuation mode. In short, when the audio signal Vi input to the apparatus  10  is relatively “weak,” the attenuation circuit  1022  attenuates the audio signal Vi slightly; and when the audio signal Vi input to the apparatus  10  is relatively “strong,” the attenuation circuit  1022  attenuates the audio signal Vi significantly. The output attenuated audio signal travels through the switch  1024  and the audio processor  30  of the television, and then is broadcast by a speaker of the television after being amplified by the amplifier  40 . In this way, the viewer avoids being bothered by loud advertisements or unexpected noises.  
         [0025]     The resistance values of the resistors R 1 , R 2 , R 3 , R 4  are predefined by a manufacturer of the television. When the apparatus  10  is in the attenuation mode, the viewer can simultaneously adjust the sound volume via the infrared remote control device  50  or a functional key on the television itself according to his/her particular requirements. In order to realize the above-described function of adjusting the sound volume, the MCU  1010  controls the degree to which the amplifier  40  amplifies the audio signal. The apparatus  10  of the present invention is also applicable to other audio systems besides televisions, such as radios, CD disc players and personal stereos.  
         [0026]      FIG. 4  is a flow chart of an exemplary method for adjusting sound volume according to the present invention. A viewer selects an operating mode of the apparatus  10  via the infrared remote control device  50  or a functional key on the television itself. At step S 510 , the MCU  1010  determines whether the apparatus  10  is in the attenuation mode. If so, the procedure goes to step S 512  described below. Otherwise, the procedure goes to step S 522 . At step S 522 , the MCU  1010  controls the switch  1024  to switch the circuit  102  to the normal mode. At step S 524 , the switch  1024  transmits an unadjusted audio signal to the audio processor  30 , whereupon the procedure is ended. At step S 512 , the MCU  1010  controls the switch  1024  to switch the circuit  102  to the attenuation mode. At step S 514 , the attenuation circuit  1022  receives the input audio signal. At step S 516 , the attenuation circuit  1022  attenuates the input audio signal, and outputs an attenuated audio signal to the switch  1024 . The attenuation circuit  1022  outputs a linearly-attenuated audio signal to the switch  1024  if the input audio signal is relatively “weak;” or the attenuation circuit  1022  outputs a nonlinearly-attenuated audio signal to the switch  1024  if the input audio signal is relatively “strong.” At step S 518 , the switch  1024  obtains the attenuated audio signal from the attenuation circuit  1022 , and then transmits it to the audio processor  30 , whereupon the procedure is ended.  
         [0027]     The above-described procedure is repeated continually from the time the viewer turns on the television until the time the viewer turns off the television.  
         [0028]     While a preferred embodiment and preferred method of the present invention have been described above, it should be understood that they have been presented by way of example only and not by way of limitation. Thus the breadth and scope of the present invention should not be limited by the above-described exemplary embodiment and method, but should be defined only in accordance with the following claims and their equivalents.