private String toHtmlTd(Object obj) {
		String result = null;
		if (obj == null) {
			result = "<td x:str></td>";
		} else if (obj instanceof StdStyledCell) {
			StdStyledCell cell = (StdStyledCell)obj;
			StringBuilder sb = new StringBuilder();
			StringBuilder style = new StringBuilder();
			// スタイルの作成
			if (cell.getForeground() != null) {
				style.append("color:");
				style.append(StringUtil.colorToHex(cell.getForeground()));
				style.append("; ");
			}
			if (cell.getBackground() != null) {
				style.append("background-color:");
				style.append(StringUtil.colorToHex(cell.getBackground()));
				style.append("; ");
			}
			if (cell.getBorderThickness() > 0 && cell.getBorderColor() != null) {
				style.append("border-style: solid; ");
				style.append("border-width: "+ cell.getBorderThickness() +"pt; ");
				style.append("border-color: ");
				style.append(StringUtil.colorToHex(cell.getBorderColor()));
				style.append("; ");
			}
			// TDタグの作成
			if (style.length() > 0) {
				sb.append("<td x:str style=\"");
				sb.append(style.toString());
				sb.append("\">");
			} else {
				sb.append("<td x:str>");
			}
			if (cell.getValue() != null) {
				sb.append(StringUtil.escapeHtmlString(cell.getValue()));
			}
			sb.append("</td>");
			result = sb.toString();
		} else {
			result = "<td x:str>" + String.valueOf(obj)+ "</td>";
		}
		return result;
	}