Electrical audio signal processing systems and devices – Including amplitude or volume control – With manual volume control
Reexamination Certificate
1997-10-31
2001-05-29
Isen, Forester W. (Department: 2644)
Electrical audio signal processing systems and devices
Including amplitude or volume control
With manual volume control
C381S104000
Reexamination Certificate
active
06240191
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
This invention relates generally to an audio volume control process and circuit using a pulse width modulation (PWM) signal that is generated with a variable duty ratio according to the users operation, and regulates the output level of the audio signal.
2. Related Art
Audio output appliances, like television sets and audio systems, usually amplify and output the audio signal with an amplifier. The audio output appliances have built-in volume controllers, and the audio signal level is regulated and put out according to the volume controller operated by the user.
Recently, with the development of computer technology, multi-media technology has employed such a technique so that various audio signals are put out with an audio card in the computer system. An example of this is found in various computer games, wherein audio signals are produced according to the process of the game with audio cards. Exemplars of recent efforts in the art are found among the designs and processes described, for example, in U.S. Pat. No. 5,666,431 to Gillespie et al, entitled volume Control For A Personal Computer Internal Speaker, U.S. Pat. No. 5,150,415 to Jaffee et al, entitled Volume Control Circuit Using Pulse Modulation, U.S. Pat. No. 4,724,396 to Taylor Jr., et al., entitled Digital Audio Amplifier, U.S. Pat. No. 4,433,416 to Kojima, entitled PCM Signal Processor, U.S. Pat. No. 4,390,834 to Ohshima, entitled Digital Volume Control, U.S. Pat. No. 4,371,840 to Yokoyama, entitled Gain Control Circuit For Pulse Width Modulation Amplifier, U.S. Pat. No. Re. 30,482 to Whitlock, entitled Pulse Code Modulated Digital Audio system, entitled Pulse Code Modulated Digital Audio System, and U.S. Pat. No. 4,030,129 to Whitlock, entitled Pulse Code Modulated Digital Audio system.
While playing compact disks (CDS) or audio or video compact disks (VCDs) in the compact disk-read only memory (CD-ROM) drive attached to a computer system, the audio signal from the CDS or VCDs will be put out from the audio card. As the audio cards putting out the audio signal have been attached to the computer system, the monitor, which has been used only as the output screen or display of the computer system, not only expresses a certain image, but also amplifies the audio signal provided by the computer system and puts it out through a speaker. The monitor also has a built-in volume controller regulating the volume output, and the level of the audio signal will be varied and be put out as a user regulates the volume controller. Thus, a variable resistor has conventionally been used as a volume controller in order to control the level of the audio signal put out by the audio output appliances and the computer system.
I have found that such conventional variable resistors having been burdened by disadvantages when used as a volume controller. For example, as explained in more detail below, such variable resistors are such that is difficult to regulate the signal level of audio signals passing through such variable resistors. In addition, due to errors associated with the variable resistors, a uniform signal-to-noise ratio is difficult to obtain. Furthermore, as such variable resistors are used over a period of time, they can become attenuated or can cause noise due to dust or humidity. Finally, in such conventional arrangements, the user can be disturbed due to the occurrence of a popping noise when the speakers are muted.
SUMMARY OF THE INVENTION
It is therefore, one object of the present invention to supply an improved audio level control process and circuit.
It is another object to provide and audio level control process and circuit able to regulate the output level of the audio signal by using pulse width modulated signals that have a variable duty ratio according to the operation of the user.
It is still another object to provide a volume control process and controller to regulate the level of the audio signal produced by the audio card of a computer system.
It is yet another object to provide a volume control process and controller to regulate the level of the audio signal produced by the audio card of a computer system with a micro-computer implemented in a monitor, and pulse width modulated signals exhibiting a variable duty ratio according to the operation of the user.
These and other objects may be attained with a micro-computer implemented in a monitor, using pulse width modulated signals having a variable duty ratio established according to the operation of the user. The pulse width modulated signal generator creates pulse width modulated signals with a variable duty ratio, and a rectifier transforms the pulse width modulated signals into DC level signals and puts them out as the user operates an up key or a down key.
The pulse width modulation signal generator creates pulse width modulated signals with a variable duty ratio with the help of a separate pulse width modulation signal generator as the up or down key is operated, or as the micro-computer governing the operation of a monitor functions in accordance with the up or the down key.
The audio signal level regulating integrated circuit comparatively amplifies the DC level put out by the rectifier, and controls the audio signal level, and the audio signal put out by the integrated circuit with a regulated level is put out through an audio output means after having been processed in an audio signal processor. Therefore, noise will not arise during use of the appliance for a long time, even though the output level of the audio signal is varied electrically. Moreover, in muting the audio signal, pop noises will not arise since the duty ratio of the pulse width modulated signal put out by the pulse width modulation signal generator is regulated.
REFERENCES:
patent: Re. 30482 (1981-01-01), Whitlock
patent: 4030129 (1977-06-01), Whitlock
patent: 4371840 (1983-02-01), Yokoyama
patent: 4390834 (1983-06-01), Ohshita
patent: 4433416 (1984-02-01), Kojima
patent: 4724396 (1988-02-01), Taylor et al.
patent: 5054071 (1991-10-01), Bacon
patent: 5150415 (1992-09-01), Jaffee et al.
patent: 5191620 (1993-03-01), Lee
patent: 5444783 (1995-08-01), Na
patent: 5613010 (1997-03-01), Heyl et al.
patent: 5666431 (1997-09-01), Gillespie et al.
patent: 5751816 (1998-05-01), Howard
patent: 5771301 (1998-06-01), Fuller et al.
patent: 5802187 (1998-09-01), Hsu
Bushnell , Esq. Robert E.
Isen Forester W.
Pendleton Brian Tyrone
Samsung Electronics Co,. Ltd.
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