private static function getPhpEncoding( $html_charset )
    {
        $php_encoding = null;

        switch( strtolower($html_charset) ){
            case 'sjis':
            case 'sjis-win':
            case 'shift_jis':
            case 'shift-jis':
            case 'ms_kanji':
            case 'csshiftjis':
            case 'x-sjis':
                $php_encoding = 'sjis-win';
                break;
            case 'euc-jp':
            case 'cseucpkdfmtjapanese':
                $php_encoding = 'EUC-JP';
                break;
            case 'jis':
                $php_encoding = 'jis';
                break;
            case 'iso-2022-jp':
            case 'csiso2022jp':
                $php_encoding = 'ISO-2022-JP';
                break;
            case 'iso-2022-jp-2':
            case 'csiso2022jp2':
                $php_encoding = 'ISO-2022-JP-2';
                break;
            case 'utf-8':
            case 'csutf8':
                $php_encoding = 'UTF-8';
                break;
            case 'utf-16':
            case 'csutf16':
                $php_encoding = 'UTF-16';
                break;
            default:
                if ( strpos($html_charset,'sjis') ){
                    $php_encoding = 'SJIS';
                }
                break;
        }

        return $php_encoding;
    }