One of this should help you:
DWG2ImageX - convert DWG/DXF file into GIF, JPEG, BMP, PNG directly, without need of AutoCAD. Support R9 to AutoCAD 2011 format.
http://www.videoconverterplus.com/activex/dwg2imagex.html
AutoDWG DWG to Image Converter Pro (batch converter) - converts DWG or DXF files to BMP, JPG, TIF, GIF, PNG without need of AutoCAD,Support AutoCAD 2011
http://www.videoconverterplus.com/authoring-tools/autodwg-dwg-to-image-converter-pro.html
AutoDWG DWG2Image (batch converter) - converts DWG or DXF files to BMP, JPG, TIF, GIF, PNG without need of AutoCAD,Support AutoCAD 2011
http://www.videoconverterplus.com/multimedia-design/autodwg-dwg2image.html