Image display apparatus, number of horizontal valid pixels detecting apparatus, and image display method

A horizontal valid pixels detecting apparatus comprising:

• a dot clock counting circuit for starting counting of a number of dot clocks for an inputted image signal synchronously with a horizontal synchronizing signal of the image signal;
• a level detecting circuit for detecting whether or not there is a valid image signal in the image signal;
• a horizontal image start-position latching circuit for latching a minimum counted number of the dot clocks until the valid image signal is detected for each horizontal scanning period of the image signal;
• and
• a horizontal image end-position latching circuit for latching a maximum counted number of the dot clocks until the valid image signal is not detected for each horizontal scanning period of the image signal.

A method for displaying an image on a dot- matrix type image display unit on the basis of an input image signal of an arbitrary standard, said method comprising the steps of:

• reproducing an input dot clock on the basis of an input horizontal synchronizing signal of the input image signal;
• converting the input image signal into a digital signal in response to the reproduced input dot clock;
• converting the digital signal into a display signal which is suitable for display by the image display unit and generating a drive timing signal for the display;
• detecting the number of horizontal valid pixels of the display signal on the basis of the display signal and the drive timing signal;
• and
• controlling a frequency of the input dot clock so that the number of horizontal valid pixels is equal to a desired value.