Changtsi representes Midea to file an Invalidation against Invention of a Two-stage Dust and Gas Separation Structure



Authors:Joseph Zhang, Vickie Wang





This is a typical patent invalidation case associated with patent infringement litigation. We, on behalf of Jiangsu Midea Cleaning Appliance Co., Ltd, submitted a request for invalidation against invention patent ZL201510044589.X owned by patentee KingClean Electric Co., Ltd. Patent 589 relates to a crucial structure within portable cleaner. Before that request, KingClean initiated a series of patent infringement litigations against Midea, asserting that a portable cleaner manufactured and sold by Midea falls within the protection scope of Patent '589 and claiming millions of RMB. This invalidation case is associated with one of that series of litigations. Both Midea and KingClean are big cleaner manufacturers in Jiangsu Province. After assessment of this case, Midea started the patent invalidation immediately.


Being entrusted by the Midea, we conducted a deep and comprehensive prior art search, especially on those detailed technical features recited in dependent claims; utilized various combinations of the prior art references; and prepared and discussed with the technicians in Midea sufficiently for the oral hearing. Finally, the claims related to the litigation were invalidated by the Patent Reexamination Board (PRB), releasing Midea from the infringement litigation.


Ⅰ. Case backgroud:


On February 12, 2018, we, on behalf of Midea, filed a request for invalidation against patent '589 with preliminary evidences, indicating that Claims 1-11 lack inventiveness.


On February 26, 2018, we completed the prior art research, and then submitted additional combinations of evidences along with supplementary statement, indicating that Claims 1-11 lack inventiveness and some claims lack support by the specification.


On April 17, 2018, the oral hearing was held at China (Changzhou) Intellectual Property Protection Center. We arrived Midea in Suzhou two days before the hearing, and discussed with the technicians and attorneys for the related litigation there.

On June 14, 2018, the PRB issued a decision, in which all the claims that are related to the litigation were invalidated.


Ⅱ. Case difficulties:

First, patent '589 is an invention patent which was substantively examined by the CNIPA and got granted. The key to success in this case is the independent Claim 1 in patent '589; however, it seems that Claim 1 defines a relatively specific and narrow protection scope. This fact builds a challenge for our prior art search, which means that we have to locate highly convincing evidences to invalidate patent '589.

Second, the patentee submitted a bunch of models manufactured according to the prior art references cited in our petition, attempting to show their profession in the art to convince the panel.


Ⅲ. Case strategies:

Upon our analysis, we think the focus issue in this case is how to locate good prior art evidences to prove that patent '589 is obvious to persons skilled in the art; at the same time, enough space for Midea to defense during the related patent infringement litigation is also very important. In view of this, we proposed the following strategies:

First, we conducted a prior art search before filing the request for invalidation but didn't locate proper evidences. Considering the time limit in the litigation, we submitted a preliminary petition on February 12, 2018. Within a month after that, we adjusted search strategy immediately and finally got several convincing evidences, and then submitted supplementary statement and reasons.

Second, we studied patent '589 carefully and communicated with the technicians from Midea in terms of all the technical details. The technicians from Midea are expert in the related art so that they could explain a lot of confusing sentences in patent '589, letting us understand the technical solution deeply. Plus, during our prior art search, Midea provided us with many non-patent literatures and textbooks, which remedy the defect of our search results and thus promote this invalidation petition.

Third, to make sure everything especially the technical stuff and avoid negative statement for the related litigation, we got to Suzhou to meet and discuss with the technicians and attorneys for the related litigation two days before the oral hearing. During discussion, we asked one senior technician from Midea to attend the hearing so that he could explain some technical details during the hearing. In addition, upon our review of the products from Midea and KingClean, we noticed the differences between the product of KingClean and patent '589. Based on our discussion with the technicians, we suggested to show the product of KingClean during the oral hearing, to prove that some technical solutions defined in the claims of patent '589 are impossible to achieve.

Lastly, during the oral hearing, we clearly and briefly stated our opinions, responded the questions from the panel, and argued with KingClean on the protection scope of patent '589. In contrast, the patentee submitted a bunch of models related to almost every prior art reference, trying to mislead the panel to understand patent '589 in a wrong way with those models; further, the patentee only focused on the technical effect brought by patent '589 without talking anything about the technical features recited in the claims. We indicated this defect of the patentee and the panel completely supported us in this aspect.


Ⅳ. Case significances:

First, initiating a request for invalidation in time is a common and effective way for a defendant involved in a patent infringement litigation. In turn, sufficient prior art search is of great concern for the defendant, i.e., the petitioner in the invalidation case. Beside work experience and attitude, it is advantageous, even necessary, for patent attorneys to work with the technicians to complete the prior art search together.

Second, due to the related infringement litigation and the competition between Midea and KingClean, this Invalidation Decision is quite important to both parties. With our efforts, all the claimed raised by KingClean in the related litigation were invalided. Under this Decision, Midea got an advantage in the litigation, because its products do not include any features recited in the remaining claims.

Third, the oral hearing was held on April 17, 2018, which is close to the World Intellectual Property Day (April 26); also, it is the first patent invalidation hearing held at China (Changzhou) Intellectual Property Protection Center. Therefore, a lot of entrepreneurs were present at the hearing and this hearing was reported through several media. From the procedure of this case, the PRB showed its increasingly improved expertise regarding invalidation against invention patents. It is our honor to attend this oral hearing, communicate with professionals there, and contribute our share for promoting the popularization and development of intellectual property in Changzhou as well as eastern China.

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