Understanding the Scope of Patents andIdentifying Potential Infringement Issues


by Clark Jablon, Esq.

Editor's Note: This column is the third in a four-part series examining the latest developments in the vital area of patents, particularly those that relate to the display industry. The final installment will run in the next issue and will discuss how to establish an effective patent program in a company that does not currently seek patents.

Patents are often misunderstood documents, mainly due to their highly technical nature and liberal use of legal-technical language. Despite their complex appearance, with a little bit of guidance from a patent practitioner, the scope of most patents can be understood by someone who works in the field in which the patent pertains. In this column, we will examine a sample patent and touch upon its most important elements; namely, the claims, the life of the patent, and ownership issues. Due to space limitations, it is not possible to reproduce the sample patent. Thus, the following instructions are provided to retrieve the sample patent:

1. Go to: http://www.google.com/advanced_patent_search (note two underscores).
2. Enter 4769292 in the "Patent Number" search box and hit the enter key or click on "Google Search."
3. Click on the one search result, and then click on either "Read this patent" or "Download PDF."

These steps will bring up a 1988 organic light-emitting-diode (OLED) patent issued to a group of Kodak inventors headed by Ching W. Tang, considered to be the inventor of the OLED. It will be referred to as "the '292 patent," which is typical industry jargon for referencing patents.

Patents consist of two main parts: a written description and claims. The written description (which typically includes drawings) is supposed to provide sufficient detail so that a person of ordinary skill in the art to which the invention pertains can make and use the invention without undue experimentation.

The claims define the legal bounds of the patent owner's rights, much like a property deed that defines the boundary lines of the property. The patent owner has the right to exclude others from making, using, or selling the invention defined by the claims. The claims appear as numbered paragraphs at the end of the patent. There are 19 claims in the '292 patent spanning columns 48–52, and thus there are 19 separate legally enforceable rights in the '292 patent. Some of the 19 claims are written in shorthand format by first referring to the text of previous claims and then adding additional text. Infringement of any one of the 19 claims constitutes infringement of the patent.

The first claim in a patent is often the broadest one. The first claim in the '292 patent reads as follows:

"1. An organic electroluminescent device comprising in sequence, an anode, an organic hole injecting and transporting zone, a luminescent zone, and a cathode, characterized in that the luminescent zone is formed of a thin film of less than 1 μm in thickness comprised of an organic host material forming a layer capable of sustaining both hole and electron injection and located in the layer as a fluorescent material a dye capable of emitting light in response to hole–electron recombination, the dye having a bandgap no greater than that of the host material and a reduction potential less negative than that of the host material." (The word "said" was replaced by the equivalent word "the" for easier readability.)

To infringe this claim, one must practice each and every structural limitation. For example, there would be no infringement if thin film is used that has a thickness significantly greater than 1 μm, or if an organic host material is used that has a layer that cannot sustain both hole and electron injection, or if a dye is used that has a bandgap significantly greater than that of the host material. Accordingly, the skilled patent practitioner tries to put in as few limitations as possible into a claim, while still defining an invention that is novel and unobvious over the prior art (prior technology).

The most valuable patents are those for which there is high commercial demand for the claimed invention, but no practical or cost-effective way of designing around the patent by not practicing one or more claim limita-tions. If a competitor improves upon a patented invention by adding additional fea-tures to its product, but does not delete any claim limitations in the patented invention, then the competitor's improved invention will still infringe the patent, even if the competitor receives their own patent on the improvement.

Patent Life

A patent has a limited life. Once it expires, anyone is free to make, use, or sell the patented invention, but not necessarily any improvements to it since there may be addi-tional unexpired patents that cover the improvements. All U.S. utility patents filed on or after June 8, 1995 have a life of 20 years from its earliest effective filing date, whereas patents filed before June 8, 1995 have a life of 20 years from the filing date or 17 years from the issue date, whichever is greater. Patent term extensions may be granted for a variety of reasons, such as regulatory delays by the Food & Drug Administration (FDA) or delays caused by selected U.S. Patent & Trademark Office (USPTO) procedures. The term exten-sions are typically printed on the front page of the patent. The '292 patent has an earliest effective date of March 2, 1987 and an issue date of September 6, 1988, and thus it expired on March 2, 2007.

To maintain a utility patent, three mainte-nance fees must be paid by the 4th, 8th, and 12th year anniversary of the Issue Date. Otherwise, the patent automatically expires. The USPTO Web site provides expiration status information. More than two-thirds of patents expire before their full life. The first step to take when a potential infringement issue arises is to determine if the patent has expired.


The front page of the patent will often include an Assignee. The '292 patent lists the assignee as being "Eastman Kodak Com-pany." The USPTO maintains a publicly accessible database that lists patent chain of titles. The current owner is the last owner in the chain. The Web site is http://assignments.uspto.gov/assignments/?db=pat.

Most companies who buy patents from another company record the ownership change, although there is no legal requirement to do so. The current owner of the patent can usually be confirmed by making a few phone calls to either the last listed owner of record, or to the patent practitioner who obtained the patent. If there is no assignee field and no post-issuance recordation of an assignment at the Web site noted above, then it is likely that the patent is owned by the inventors. Patent licenses are typically not available in the public records, and there is no mechanism for publicly locating patent licenses, such as any licenses that Kodak may have granted for the '292 patent.

The discussion above should provide a good starting point in understanding how to review key portions of a patent when or if infringement issues arise. In the next column, we will discuss how to establish an effective patent program in a company that does not currently seek patents. •

Clark A. Jablon is a Registered Patent Attorney in the Philadelphia, Pennsylvania, office of the law firm of Akin Gump Strauss Hauer & Feld LLP. He is also a degreed electrical engineer who has worked as a patent practitioner in high-tech industries for more than 23 years. The opinions expressed herein are those of the author and not necessarily those of Akin Gump Strauss Hauer & Feld LLP; e-mail: cjablon@akingump.com.