Abstract:
In TV broadcasting environment, due to different settings in different TV stations, the sound level from each station may vary in a wide range. For general users, it may cause annoying experience since the TV sound level may change a lot when user switches the channel from one to the other. In addition, switching among TV reception and AV inputs may have similar problem. The present invention relates to a method and apparatus which can be easily integrated into a single IC to achieve a low cost TV sound level control solution.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The invention relates in general to an audio system circuitry and a television therewith, and more particularly, to an audio system circuitry for automatically sound level control and a television therewith.  
         [0003]     2. Related Art of the Invention  
         [0004]     In a television (TV) broadcasting environment, due to different settings in different TV stations, a sound level from each of the TV stations may vary in a wide range. For general users, it may cause annoying experience since the sound level in the TV stations may change a lot when a user switches channels from one to the other. In addition, switching among a TV reception and AV inputs may have similar problem.  
         [0005]     For solving the problem, an “apparatus for automatically adapting the mean sound level of a television receiver” is proposed in the U.S. Pat. No. 5,631,714, assigned to Serge Saadoun on May 20, 1997. The apparatus for automatically adapting the sound level of the television receiver includes a video adapting circuit including at least one additional input high-pass filter and a fixed-gain video amplifier connected in series and interposed in the video image processing circuits at circuitry for providing video image signals, and secondly an audio adapting circuit interposed in the sound path at circuitry for taking audio signals to detect the input mean level of sound, to compare said mean level of sound with a pre-established reference mean level, and automatically to adapt the mean level of output sound to maintain it at the pro-established reference mean level.  
         [0006]     However, the proposed apparatus for automatically adapting the sound level of the television receiver is implemented purely by analog circuits. It needs manufactures to preset a preferred sound level for users in manufacturing process. However, such preset level may be not an expected level for some end-users. In addition, the sound level detection is implemented at the audio signal input, instead of the audio signal output. At the audio signal input, the signal level is much smaller than signal at output. It is difficult to get accurate adjustment and some small difference remains at such stage. Since the actual audio output is generated after a volume control processing, the final output level may be varied in a wider range due to different volume control settings and the small signal difference at the input after such adjustment. Finally, since the proposed apparatus for automatically adapting the sound level is a pure analog design, it is not easy to be applied to the new digitalized TV designs, which becomes a main trend for future TV.  
         [0007]     Another “method and apparatus for maintaining uniform sound volume for televisions and other systems” is proposed in the U.S. Pat. No. 6,552,753, assigned to Ilya Zhurbinskiy, et al. on Apr. 22, 2003. The proposed apparatus includes an eight-bit DSP having a CPU, RAM and ROM memory, an analog digital convertor, a voltmeter, a timer, a switch, and a “SAVE” button. When the user begins listening to a first channel, the user experiments with the volume desired and once the user has it the user pushes the “SAVE” button on the TV set which activates the voltmeter to measure the volume of the tension on the output of the sound amplifier, and correspondingly the loudness level, at a number of intervals to capture variations occurring during the show. The DSP calculates a mean volume of the tension which is then transmitted to the RAM and retained in memory. Then the DSP switches off the apparatus. When the user subsequently switches to a second channel the apparatus switches on and the voltmeter measures the volume of the tension of the second channel at a number of intervals, the digital signal processor calculates the mean level and once again transmits that mean volume of the tension level to the RAM. The DSP calculates the difference between the mean volume of the tension of the saved tension and that of the second channel. If there is a difference in volumes of the tension level, the DSP sends a signal to the apparatus to adjust the volume of the tension until the difference becomes zero.  
         [0008]     However, the proposed method and apparatus for maintaining uniform sound volume for televisions uses a DSP after the audio signal multiplexer unit to calculate the sound level and performs adjustment. The proposed architecture needs a higher cost since a dedicated DSP is needed in the system. Furthermore, since some running time is needed for the DSP firmware to do calculation, the proposed architecture measures approximately 5 to 10 times of the volume levels with large interval for adjustment judgment. It may cause erroneous result because sometimes all these data are sampled at higher than average points or are sampled at lower than average points.  
       SUMMARY OF THE INVENTION  
       [0009]     Accordingly, one object of the present invention is to provide an architecture which can be easily integrated into a single integrated circuit (IC) to achieve a low cost sound level control solution in audio system circuitry applications or electrical devices with an audio system circuitry, for example, in a television (TV) or a car audio system.  
         [0010]     To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention provides an audio system circuitry for sound level control. The audio system circuitry includes an analog to digital converter, a data processing digital circuit, and a storage unit. The analog to digital converter is used for sensing a volume level in the audio system circuitry and output sensing results. The data processing digital circuit is used for performing a calculation upon the sensing results and sending calculation results to the storage unit, whereby the sound level of the audio system circuitry is controlled in according to the calculation results.  
         [0011]     In the audio system circuitry above, the audio system circuitry is installed in a television (TV) set and is connected to a TV microcontroller (TV MCU) of the TV set, or a processing unit of the electrical device.  
         [0012]     In the audio system circuitry above, the calculation performed by the digital circuit is a mean value calculation. The mean value calculation is done with a sampling rate higher than 1 KHz.  
         [0013]     In the audio system circuitry above, the calculation performed by the digital circuit is a peak value memorizing calculation.  
         [0014]     In the audio system circuitry above, the calculation performed by the digital circuit comprising two sets of calculation circuits with different programmable periods, wherein one is used for quick adjust and the other is used for fine tune.  
         [0015]     In the audio system circuitry above, the audio system circuitry for sound level control is integrated with audio multiplexer, volume control, tone control into a single integrated circuit (IC).  
         [0016]     In the audio system circuitry above, the audio system circuitry for sound level control is integrated with audio multiplexer, volume control, tone control into a single integrated circuit (IC).  
         [0017]     In the audio system circuitry above, the audio system circuitry for sound level control is integrated with audio multiplexer, volume control, tone control, system processor, and other audio effect processing into a single integrated circuit (IC). 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]     These, as well as other features of the present invention will become more apparent upon reference to the drawings.  
         [0019]      FIG. 1  shows a preferred embodiment of a digital television (TV) set capable of automatically controlling a sound level.  
         [0020]      FIG. 2  shows a preferred embodiment of architecture to achieve a low cost sound level control solution in a television (TV).  
         [0021]      FIG. 3  shows a preferred embodiment of the data processing unit shown in  FIG. 2 , which is implemented by an average calculation circuit.  
         [0022]      FIG. 4  shows a preferred embodiment of the data processing unit shown in  FIG. 2 , which is implemented by a 2-stage average calculation circuit. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0023]     The invention provides an architecture which can be easily integrated into a single integrated circuit (IC) to achieve a low cost sound level control solution in audio system circuitry applications or electrical devices with an audio system circuitry, for example, in a television (TV) or a car audio system. The proposed architecture converter for sensing an output volume level in the audio system circuitry application, and a storage unit for storing user settings and calculation results from the digital circuit.  
         [0024]     In an embodiment of the invention, the data processing digital circuit performs the calculation including, for example, either a peak value memorizing calculation or a mean value calculation during a user-programmable period, or both. In an embodiment of the invention, the mean value calculation of the proposed architecture is done with a sampling rate higher than 1K Hertz for a more accurate result of the mean value. In an embodiment of the invention, the digital circuit for sound level sense and control includes two sets of calculation circuits with different programmable period, one of which is used for quick adjustment and the other of which is used for fine tune.  
         [0025]     In an embodiment of the invention, the proposed architecture for sound level control includes a digital circuit together with an analog to digital converter and a storage unit to constitute a simple and low cost audio sound level sense and control mechanism can be implemented with the audio multiplexer, volume control, tone control in a single integrated circuit.  
         [0026]     With the help of data processing digital circuit, system processor (e.g. a TV MCU) can be released from the heavy-duty averaging calculation but only read calculation results and performs suitable adjustment. Since almost all modern audio system circuitries include processor unit and this proposed architecture requests very limited extra processing power to the processor, the processor in the original design does not have to be upgraded to a higher performance. And thus additional cost for achieve such sound level control is minimized. In addition, very efficient application-specific hardware design can be used in the data processing digital circuit. A high sampling rate, for example, 20 KHz, for average calculation or peak value memorizing can be easily achieved to greatly reduce the judgment error from low sampled data number with low sampling rate and large interval, which is a common drawback if calculation is done by firmware of a DSP or processor.  
         [0027]     Refer to  FIG. 1 , which shows a preferred embodiment of a digital television (TV) set  100  capable of automatically controlling a sound level. In the embodiment of the invention, the proposed architecture for sound level control includes a digital circuit together with an analog to digital converter and a storage unit to constitute a simple and low cost audio sound level sense and control mechanism are implemented with the audio multiplexer, volume control, tone control in a single integrated circuit, as shown in the audio processor  110  in  FIG. 1 . The audio processor  110  selectively receives input data from external sources, for example, receiving an audio signal from a tuner or several AV plug audio in terminals, which depends on the TV set. A TV MCU  120  is connected to a video decoder  130  and a video processor  140 . In an embodiment of the invention, the TV MCU  120  is further connected to the audio processor  110  for performing adjustment decision upon the data stored in the audio processor  110 . The output of the audio processor  110  is transmitted to a power amplifier  150 . The output of the power amplifier  150  is transmitted to a speaker of the TV set  100 . The output of the video processor  140  which is connected to a memory unit  160  is transmitted to a display module  170  of the TV set  100 .  
         [0028]     The proposed system can be easily applied to other similar system applications, for example, a car audio system. It is dangerous for a driver to adjust the volume very often during channel change. With the same structure such situation can be reduced.  
         [0029]     Refer to  FIG. 2 , which shows a preferred embodiment of architecture to achieve a low cost sound level control solution in a television (TV). The exemplary architecture of the embodiment is used for explaining the invention, but not used to restrict to the scope of the invention. As described above, the architecture to achieve a low cost sound level control solution can also be applied to other application systems, for example, in audio system circuitry applications or electrical devices with an audio system circuitry, or a car audio system, etc.  
         [0030]     As shown in  FIG. 2 , the architecture for sound level control solution  200  includes an analog to digital converter (ADC)  210  for sensing an output volume level in the audio system circuitry application, a data processing digital circuit  220  for performing calculation on the sensing data, and a storage unit  230 , for storing user settings and calculation results from the data processing digital circuit  220 . The storage unit  230 , for example, is a register set in an embodiment. As explained above, for reducing the cost, the calculations includes either a peak value memorizing calculation or a mean value calculation, or both, performed by the digital circuit. A TV microcontroller (MCU)  240  in the TV set can simply read the results and decide the adjustment. In the embodiment, a MCU interface  245  is interposed between the TV MCU  240  and the storage unit  230 .  
         [0031]     The architecture  200  further includes a receiving interface multiplexer  250  for selectively receiving input data from external sources, for example, receiving an audio signal from a tuner or several AV plug audio in terminals, which depends on the TV set. The source audio signals received from the external sources are transmitted to the volume and tone control unit  260 . After performing volume and tone controlling upon the received source audio signals, these controlled audio signals are transmitted to a power amplifier  270  and also fed back to the analog to digital converter (ADC)  210 . In an embodiment, these controlled audio signals are alternatively fed back to the analog to digital converter (ADC)  210  through an A-weighting filter  205 . The A-weighting filter  205  compensates the human psychoacoustic filter effect to let measurement result close to the sound level felt by TV set users. The ADC  210  senses an output volume level of the controlled audio signals from the volume and tone control unit  260  and sends the sensing results to the data processing digital circuit  220 .  
         [0032]     In an embodiment, as shown in  FIG. 2 , the source audio signals received from the external sources are measured by the ADC  210  before being transmitted to the volume and tone control unit  260 . In another embodiment, the source audio signals received from the external sources are transmitted to a volume control unit  261  of the volume and tone control unit  260 . After performing a volume control function upon the received source audio signals, the volume-control source audio signals are transmitted to a tone control unit  263  of the volume and tone control unit  260  for tone controlling. The audio signals output from volume-control unit  261  are transmitted to the ADC  210  for signal sensing. The designs are dependent on the implementation requirements for the architecture for sound level control solution  200 .  
         [0033]     The source audio signals received from the external sources are transmitted to the volume and tone control unit  260 . After performing volume and tone controlling upon the received source audio signals, these controlled audio signals are transmitted to a power amplifier  
         [0034]     The data processing digital circuit  220  performs calculations upon the sensing result; for example, perform either a peak value memorizing calculation or a mean value calculation during a user-programmable period, or both. The calculation results are stored in the storage unit  230 . The TV MCU  240  reads the result stored in the storage unit  230  through the MCU interface  245  and adjusts the sound level of the TV. In an embodiment, the calculation performed by the data processing unit  220  in the architecture  200  includes two sets of calculation circuits with different programmable periods, wherein one is used for quick adjust and the other is used for fine tune. In an embodiment, an interrupt signal is sent to the TV MCU  240  when the peak signal exceeds a user preset upper bound value. It can release the TV MCU  240  from continuously checking the peak value for the situation when user wants to control the sound level under a certain level.  
         [0035]     In the embodiment, since the control decision is left to TV MCU  240 , there is flexibility for TV sound level control mechanism. For example, even playback in the same channel, the sound level in a program session and the sound level in an advertisement session are sometimes very different. To maintain a same sound level in different sessions of the same TV channel, this sound level control device can be enabled in such situation even there is no channel switch.  
         [0036]     Refer to  FIG. 3 , which shows a preferred embodiment of the data processing unit  220  shown in  FIG. 2 . The data processing unit  220  in the embodiment can be implemented by an average calculation circuit  300 . A programmable counter, for example, a 12-bit programmable counter  310 , stores the length of user programmed calculation length up to 4096. For each data  320  sent from an 8-bit analog to digital converter, an adder  330  performs one add computation and stores the result therefrom in a register, for example, a 20-bit register  340 . When the number of add computation reaches the count number in the 12 bit programmable counter  310 , the computation result is sent to a divider, for example, a 20-bit to 12-bit divider  350 , to divide the addition result by the value in programmable counter. After performing 20-bit to 12-bit dividing, the division computation result is then stored in a register, for example, a 8-bit register  360 . Then the computation circuit stopped.  
         [0037]     Refer to  FIG. 4 , which shows another preferred embodiment of the data processing unit  220  shown in  FIG. 2 . The data processing unit  220  in the embodiment can be implemented by a 2-stage average calculation circuit  400 . To have a longer period of averaging calculation, the embodiment in  FIG. 3  needs a very large divider circuit since the dividend bit number will be very long. To overcome this problem, a 2-stage circuit can be used. In the first stage circuit for each data  410  sent from an 8-bit analog to digital converter, an adder  420  performs one add computation and stores the result therefrom in a register, for example, a 14-bit register  430 . After 64 input data have been calculated, the most significant bits (MSB) 8 bits are sent to the second stage circuit. In the second stage circuit, an adder  440  performs one add computation upon the MSB 8 bits sent from  430  and the data stored in a register, for example, a 20-bit register  450 , and then the computation result therefrom is stored in the 20-bit register  450 . When the number of add computation in adder  440  reaches the count number in the 12 bit programmable counter  460 , the computation result is sent to a divider, for example, a 20-bit to 12-bit divider  470 . After performing 20-bit to 12-bit dividing, the division computation result is then stored in a register, for example, a 8-bit register  480 . Then the computation circuit stopped.  
         [0038]     For the embodiment of  FIG. 4 , the first stage is a fixed  64  data average calculation circuit. And its calculation result is sent to the second average calculation circuit. A user programmable counter sets the calculation count for the second average calculation. Therefore, user programmable period has a unit step of  64  data. For the embodiment of  FIG. 4 , an average calculation capability for up to 262144 data can be reached, which can extend to 13.1 second for a high speed 20 KHz data sampling.  
         [0039]     In an embodiment of the invention, control of the average calculation period is not by user programmable counter, but from the start and stop command of a system processor (e.g. a TV MCU).  
         [0040]     Other embodiments of the invention will appear to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.