Audio/video device having a volume control function for an external audio reproduction unit by using volume control buttons of a remote controller and volume control method therefor

An audio/video (A/V) apparatus comprising:

• a video signal processor which processes video data from an audio and video signal;
• a display which displays the processed video data from the video signal processor;
• an audio signal processor which processes audio data from the audio and video signal;
• an audio output port which outputs the processed audio data to a set of earphones;
• a speaker which outputs sound from the processed audio data;
• at least one volume control button which controls a volume level of the speaker and a volume level of the set of earphones;
• a memory which stores a speaker volume level value, which corresponds to a volume level set by a user for the speaker, and an earphone volume level value, which corresponds to a volume level set by a user for the set of earphones;
• and
• a processor which produces a speaker volume On-screen Display (OSD) and an earphone volume OSD, wherein the speaker volume OSD and the earphone volume OSD are visibly responsive to manipulation of the at least one volume control button, and
• which controls the display to display the speaker volume OSD on at least a part of a display screen of the processed video data for a period of time while the set of earphones is unplugged from the audio output port, and controls the display to display the earphone volume OSD, in place of the speaker volume OSD, on at least a part of the display screen of the processed video data for a period of time while the set of earphones is plugged into the audio output port, wherein the speaker volume OSD and the earphone volume OSD show items only in relation to a volume level change operation such that the speaker volume OSD and the earphone volume OSD are not used for any other operation of the A/V apparatus.