Method and apparatus for automatically setting speaker mode in audio/video system

A method and apparatus for automatically determining a characteristic of a speaker and automatically setting a speaker mode in an audio/video system. The method includes: detecting a current for operating the speaker by inputting a predetermined signal; measuring an impedance characteristic of the speaker in accordance with a frequency change based on the detected current; determining a speaker type based on the measured impedance characteristic; and setting a speaker mode based on an impedance characteristic curve of the discriminated speaker type.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application claims the benefit of Korean Patent Application No. 10-2004-0093543, filed on Nov. 16, 2004, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a home theater system, and more particularly, to a method and apparatus for automatically determining a characteristic of a speaker and automatically setting a speaker mode in an audio/video system.

2. Description of the Related Art

Commonly, a home theater system includes a 5.1 channel amplifier, a digital versatile disc (DVD) playback device, and a tuner, and is used with a large screen digital TV. Also, the home theater system can not only realize high image quality by adopting a progressive scanning function, which is an up-to-date image technology, but can also reproduce 2-channel stereo sound signals from, for example, a video cassette recorder (VCR) or a TV broadcastast, as 5.1 channel sound, using Dolby pro-logic decoding technology.

In such a home theater system, a user should manually set speaker modes based on the number of speakers and reproducing frequency bands of the speakers.

FIG. 1is a signaling diagram of a conventional digital signal processor for setting speaker modes in a conventional 5.1 channel speaker system.

Referring toFIG. 1, input audio signals of 5.1 channels, such as front, center, surround, surround back, and low frequency effect (LFE) channels, are output to corresponding speakers, respectively. Here, the user sets speaker modes by selecting keys mounted on a remote control or a front panel. The speaker modes are “large”, “small”, and “none”, and the user directly selects one of these speaker modes based on types of the speakers and the number of the speakers. In the “large” speaker mode, all of audio signals in an acoustic frequency band (20 Hz to 20 KHz) are output. In the “small” speaker mode, signals in a mid-to-high frequency band are output, and signals in a low frequency band are output separately to a subwoofer or another speaker. In the “none” speaker mode, no signal is output.

Thus, when speaker modes are set according to user selection, the digital signal processor first determines whether to pass signals through low pass filters (LPFs) or through high pass filters (HPFs) and how to combine the signals, based on the set speaker modes, then processes sound output from a sound reproducer to correspond with each speaker mode, and outputs the processed sound to corresponding speakers.

However, since the user is responsible for setting speaker modes in this conventional speaker mode setting method, it is difficult to operate a plurality of speakers, and it is troublesome to separately determine the settings of the plurality of speakers. Also, since the setting of speaker modes is dependent upon a user's familiarity with the characteristics of the speakers, there is a high possibility of inaccurately setting the reproducible frequency range of speakers. Accordingly, it is difficult to obtain an optimal sound effect. Also, if the speaker mode of large or small includes an unconnected speaker, the listener will not be able to hear sounds that are designated to be played by the unconnected speaker.

SUMMARY OF THE INVENTION

The present invention provides a method of automatically determining characteristics of speakers and automatically setting speaker modes in a system.

The present invention also provides an apparatus for automatically determining characteristics of speakers and automatically setting speaker modes in a system.

According to an aspect of the present invention, there is provided a method of automatically setting a speaker mode by which a pattern of a signal output to a speaker is determined, the method comprising: detecting a current for operating the speaker by inputting a predetermined signal; measuring an impedance characteristic of the speaker in accordance with a frequency change based on the detected current; discriminating a speaker type based on the measured impedance characteristic; and setting a speaker mode based on an impedance characteristic curve of the discriminated speaker type.

According to another aspect of the present invention, there is provided an apparatus for automatically setting a speaker mode in a multi-channel speaker system, the apparatus comprising: a speaker; a power supply supplying power; an amplifier amplifying a signal; a current detector detecting a current output from the amplifier to the speaker or from the power supply to the amplifier; and a digital signal processor outputting a broadband signal including a low frequency to the amplifier, measuring an impedance characteristic of the speaker based on the current detected by the current detector, discriminating a speaker type based on the measured impedance characteristic, and setting a speaker mode based on an impedance characteristic curve of the discriminated speaker type.

According to another aspect of the present invention, there is provided a multi-channel audio/video system comprising: a digital signal processor generating a predetermined signal, detecting a current value in accordance with a frequency change of the signal, measuring an impedance characteristic of a speaker in accordance with the frequency change based on the detected current value, discriminating a speaker type based on the measured impedance characteristic, and setting a speaker mode based on an impedance characteristic curve of the discriminated speaker type; and a microprocessor receiving the set speaker mode data from the digital signal processor and controlling whether to pass a signal through a filter and a combination of channels based on the set speaker mode data.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described more fully with reference to the accompanying drawings, in which embodiments of the invention are shown.

FIG. 2is a block diagram of a system for automatically setting speaker modes according to a first embodiment of the present invention.

Referring toFIG. 2, the system includes a microprocessor200, a power supply210, an amplifier220, a current detector230, a digital signal processor (DSP)240, and a speaker250.

The microprocessor200generates a speaker mode setting command. The power supply210supplies power to the amplifier220and the other blocks.

The current detector230detects the amount of current output from the amplifier220to the speaker250. The current detector230can sense the current for operating the speaker250by using a current sensing component such as a resistor R.

The DSP240receives the speaker mode setting command from the microprocessor200, outputs a broadband test signal including a low frequency to the amplifier220, measures an impedance characteristic of the speaker250based on the current detected by the current detector230, discriminates a speaker type (a duct-type speaker or a sealed-type speaker) based on the measured impedance characteristic, and sets a speaker mode (large, small, or none) for determining a signal pattern output to a corresponding speaker based on an impedance characteristic curve of the discriminated speaker type. Also, the DSP240controls passage of a signal through a low pass filter (LPF) or a high pass filter (HPF) and combination of multi-channel signals, based on the set speaker mode.

The amplifier220amplifies the test signal output from the DSP240and outputs the amplified signal to the speaker250.

In another embodiment, the microprocessor200receives speaker mode setting data from the DSP240and controls whether to pass a signal through a LPF or a HPF and how to combine multi-channel signals, based on the received speaker mode setting data.

FIG. 3is a block diagram of a system for automatically setting a speaker mode according to a second exemplary embodiment of the present invention.

Referring toFIG. 3, a current detector230-1detects a current supplied from the power supply210to the amplifier220. Here, the microprocessor200, the power supply210, the amplifier220, the DSP240and the speaker250are the same as inFIG. 2; only the current detector230-1is different.

Referring toFIGS. 4 through 7, for the duct-type speaker, two peak components are generated in a low frequency band, and a dip component is generated between the two peak components. An adjacent frequency of the dip component represents −3 dB corresponding to a low threshold frequency of the duct-type speaker. For the sealed-type speaker, one peak component is generated in the low frequency band. An adjacent frequency of the peak component represents −3 dB corresponding to a low threshold frequency of the sealed-type speaker.

Referring toFIG. 4, since two peak components and a dip component are generated in the low frequency band, it can be determined that it is the waveform diagram of a duct-type speaker. Also, since the frequency of the dip component is around 40 Hz, it can be determined that the duct-type speaker can reproduce frequencies in the low band. In this case, the speaker mode is set to large.

Referring toFIG. 5, since only one peak component is generated in the low frequency band, it can be determined that it is the waveform diagram of sealed-type speaker. Also, since the frequency of the peak component is around 80 Hz, it can be determined that the sealed-type speaker can reproduce frequencies in the low band. In this case, the speaker mode is set to large.

Referring toFIG. 6, since two peak components and a dip component are generated in the low frequency band, it can be determined that it is the waveform diagram of a duct-type speaker. Also, since the frequency of the dip component is around 150 Hz, it can be determined that it is difficult for the duct-type speaker to reproduce frequencies in the low band. In this case, the speaker mode is set to small.

Referring toFIG. 7, since only one peak component is generated in the low frequency band, it can be determined that it is the waveform diagram of a sealed-type speaker. Also, since the frequency of the peak component is around 200 Hz, it can be determined that it is difficult for the sealed-type speaker to reproduce frequencies in the low band. In this case, the speaker mode is set to small.

FIG. 8is a flowchart illustrating a method of automatically setting speaker modes according to an exemplary embodiment of the present invention.

In operation810, when a speaker mode setting command is received from the microprocessor200, the DSP240generates a broadband test signal including low frequencies, such as white noise or impulse noise.

In operation820, the current detector230detects a current I flowing from the amplifier220to the speaker250or the power supply210to the amplifier220based on a frequency change of the test signal of operation810.

In operation830, the DSP240determines through the current detector230whether the current I flowing from the amplifier220to the speaker250or the power supply210to the amplifier220changed. If the current detector230cannot detect a current change, in operation896, the DSP240determines that there is no corresponding speaker and sets the speaker mode to none.

If the current detector230detects a current change, in operation840, the DSP240measures an impedance characteristic in accordance with a frequency based on the current. For example, an impedance Z is measured using the voltage V and current I of the low frequency.

In operation850, the DSP240discriminates a corresponding speaker type, either as a duct-type or a sealed-type, based on the measured impedance characteristic. That is, since two peak components and a dip component are detected in the low frequency band according to the impedance characteristics ofFIGS. 4 and 6, the DSP240determines that the speaker is a duct-type speaker, and since one peak component is detected in the low frequency band according to the impedance characteristics ofFIGS. 5 and 7, the DSP240determines that the speaker is a sealed-type speaker.

Thus, if the DSP240determines that the measured impedance characteristic corresponds to the duct-type speaker, in operation860, the DSP240detects a frequency of a dip between peak points of an impedance characteristic curve. If the detected dip frequency is lower than a reference frequency, it is determined that low band reproduction is possible, and in operation884, the speaker mode is set to large. If the detected dip frequency is higher than the reference frequency, it is determined that low band reproduction is difficult, and in operation886, the speaker mode is set to small. For example, inFIG. 4, since the dip frequency (40 Hz) is lower than the reference frequency (100 Hz), the speaker mode is set to large, and low band reproduction is possible. Also, inFIG. 6, the dip frequency (150 Hz) is higher than the reference frequency (100 Hz), and the speaker mode is set to small and low band reproduction is difficult.

If the DSP240determines that the measured impedance characteristic corresponds to the sealed-type speaker, in operation870, the DSP240detects the frequency of a first peak of an impedance characteristic curve. Here, if the detected peak frequency is lower than the reference frequency, since low band reproduction is possible, in operation892, the speaker mode is set to large. If the detected peak frequency is higher than the reference frequency, since low band reproduction is difficult, in operation894, the speaker mode is set to small. For example, inFIG. 5, since the peak frequency (80 Hz) is lower than the reference frequency (100 Hz), the speaker mode is set to large and low band reproduction is possible. Also, inFIG. 7, the peak frequency (200 Hz) is higher than the reference frequency (100 Hz), and the speaker mode is set to small since low band reproduction is difficult.

Finally, the DSP240outputs sound to each corresponding speaker by controlling whether to pass signals through an LPF or through an HPF and how to combine multi-channel signals, based on a speaker mode automatically set for each of multi-channel speakers.

The exemplary embodiments of the present invention can be written as computer programs and stored on computer-readable recording media. Examples of the computer-readable recording media include magnetic storage media (e.g., ROM, floppy disks, hard disks, etc.), optical recording media (e.g., CD-ROMs, DVDs, etc.), and storage media such as carrier waves (e.g., transmission over the Internet). The computer readable recording media can also be distributed over a network of coupled computer systems so that the computer-readable code is stored and executed in a decentralized fashion.

As described above, according to exemplary embodiments of the present invention, by automatically setting a speaker mode using a change in current flowing to a speaker in a multi-channel speaker system, convenience is provided to a user who is not familiar with setting speaker modes, and optimal sound can be reproduced by preventing the user from making mistakes in setting speaker modes.