How is US6292685 different from Exergen's previously filed patent?

Question

Exergen has recently and successfully won legal battles with two other companies marketing products using a similar technology, American Diagnostic Corp. & SDI Diagnostic Corp..

Firstly, it seems strange that Exergen can sue these companies considering their product isn't even non-contact, whereas the other companies' products were.

Secondly, there seems to be quite a few other companies, namely Veratemp and Veridian, that are currently marketing similar devices using technology that "might" infringe on this same patent, yet Exergen doesn't seem to be suing them.

To conclude, I have three questions I'm hoping someone could help to answer.

1. Why would Exergen not be suing these other companies too?

2. If Exergen terminated their previous patent US6292685, would this make the technology "prior art" or does it continue to be protected through their new patent?

3. If other patents were filed more than 20 years ago, which described measuring core body temperature as a function of surface temperature over an artery against ambient temperature, would their patent become invalid and technology be considered "prior art"?

Answer 1

This is a partial answer. The VeraTemp brand seems to be made/sold by Brooklands. Apparently they were also sued just last month The patent in suit is US 7,787,938.

It's claim 1 is:

1. A method of detecting human body temperature comprising moving a radiation detector to scan across skin over an artery and measure radiation as target skin surface over the artery is viewed, and electronically determining a body temperature approximation, distinct from skin surface temperature, from the radiation detector as the target skin surface over the artery is viewed.

There are several applications and patents in this chain

09/923,240 filed on 08-03-2001 which is Abandoned claims the benefit of 09/151,482 10/684,818 filed on 10-14-2003 which is Patented claims the benefit of 09/151,482 12/011,467 filed on 01-25-2008 which is Patented claims the benefit of 09/151,482 12/857,252 filed on 08-16-2010 which is Pending claims the benefit of 09/151,482 PCT/US99/20855 filed on 09-10-1999 which is Published claims the benefit of 09/151,482

The three issued patents are the one you mentioned, the one in the suit and 7,346,386. There is still one application pending. Different patents for the same original application will have differently worded claims.

The patent status of the other patent has nothing to do with its applicability as prior art. For one thing they are both descended from the same original application. More fundamentally something is prior art for when it became public (sort of) and for what it teaches.

In infringement is not a comparison between product X and product Y. It is a comparison of the claims of patent Z to product Y.