HP has added four more charges against its rival PC manufacturer Acer claiming still more infringements of its technology.

This brings the total charges against Acer to nine.  Last month  HP claimed that Acer was infringing patents covering technologies such as read/write optical drives, power management in notebooks and digital bus arrangement.

The new lawsuits want to stop Acer from importing and selling its PCs in the United States. Patent number 6,691,236 relates to "portable computer systems that conserve power by altering the performance of the video graphics controller depending on the system's power source or battery condition". Patent number 6,029,119 covers the management of multiple cooling options in a personal computer. 

Patent 5,535,415 covers the ability to allow "concurrent bus operations to increase computer efficiency". Lastly, 6,894,706 covers "various methods and apparatuses for determining the resolution of graphics received from a computer and scaling it to match the fixed resolution of a display device".

More here.