Ningbo Dianai Plastic Co Ltd v. Individuals Corps Ltd

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Ningbo Dianai Plastic Co., Ltd. (People's Republic of China)
  • Defendant: The Individuals, Corporations, Limited Liability Companies, Partnerships, and Unincorporated Associations Identified on Schedule "A" (People's Republic of China, Hong Kong, France, or other foreign jurisdictions)
  • Plaintiff's Counsel: Carlson IP Law, LLC
• Case Identification: 1:26-cv-25411, S.D. Fla., 08/11/2026
• Venue Allegations: Venue is asserted on the basis that Defendants are aliens not resident in the United States and may therefore be sued in any judicial district. The complaint also alleges that a substantial part of the events, including offers to sell and sales of the accused products to consumers in the district, occurred in the Southern District of Florida.
• Core Dispute: Plaintiff alleges that Defendants' anal/enema cleaning devices infringe a patent related to a dual check-valve structure designed to prevent fluid backflow.
• Technical Context: The technology resides in the field of personal hygiene medical devices, where preventing cross-contamination and ensuring the cleanliness of administered fluids is a key functional objective.
• Key Procedural History: This case is initiated as a "Schedule A" action against numerous, currently unidentified online sellers. The complaint notes that Plaintiff is concurrently moving for a temporary restraining order, expedited discovery, and alternative service, a common strategy in e-commerce enforcement to quickly identify foreign defendants and freeze allegedly infringing assets.

Case Timeline

Date	Event
2020-09-23	'791 Patent Priority Date (German Application)
2021-07-14	'791 Patent U.S. Application Filing Date
2024-02-13	'791 Patent Issue Date
2026-08-11	Complaint Filing Date

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 11,896,791 - "Anus Cleaner"

• Patent Identification: U.S. Patent No. 11,896,791, titled "Anus Cleaner," issued February 13, 2024 (hereinafter "the '791 Patent").

The Invention Explained

• Problem Addressed: The patent's background section identifies a deficiency in traditional enema devices, which may "not have enough check valves to avoid the backflow of dirty water inside the anus" '791 Patent, col. 1:19-22 This backflow risks contaminating the unused fluid within the device, affecting cleanliness and potentially causing "secondary infections to patients" '791 Patent, col. 2:57-58
• The Patented Solution: The '791 Patent discloses an "anus cleaner" featuring a "double check-valve structure" to solve the backflow problem Compl. ¶16 The solution consists of two distinct one-way valves: a "steel ball check valve" installed in a through-hole at the curved bottom of the bottle body, and a "spring check valve" located at the center of the mounting table where the cleaning head attaches '791 Patent, col. 2:36-51 This dual-valve system is designed to maintain internal pressure during use while preventing contaminated liquid from being drawn back into the bottle when it re-expands '791 Patent, col. 4:1-10
• Technical Importance: The invention purports to improve hygiene and safety in personal care devices by creating a robust barrier against contamination, which is particularly important for medical or quasi-medical applications '791 Patent, col. 2:56-59

Key Claims at a Glance

• The complaint asserts infringement of "one or more claims of the '791 Patent, including at least claim 1" Compl. ¶17
• Independent Claim 1 recites the following essential elements:
  • A hollow bottle body with a curved bottom.
  • A steel ball check valve installed in a through-hole at the center of the bottle bottom.
  • A threaded bottleneck at the opposite end of the bottle.
  • A cleaning head with a threaded mounting table that connects to the bottleneck.
  • A cleaning neck atop the mounting table, containing a flow channel and a liquid outlet.
  • A spring check valve at the center of the mounting table's bottom, which "communicates with the flow channel."
  • A detailed structure for the steel ball check valve, including a "limiting seat," an "inlet," a "cavity," two "limiting round tables," a "ball locking notch," and a "plugging steel ball."
• The complaint reserves the right to assert other claims, including dependent claims Compl. ¶17

III. The Accused Instrumentality

Product Identification

• The "Accused Products" are identified as anal/enema cleaning devices sold by multiple, unnamed defendants operating under "Seller Aliases" on e-commerce platforms such as Amazon and Walmart Compl. ¶3 Compl. ¶6 Compl. ¶18

Functionality and Market Context

• The complaint alleges these products are marketed using terms such as "anti-backflow," "enema," and "anal douche" Compl. ¶18
• Crucially, the products are advertised as "reusable anti-backflow cleaning devices that incorporate the same dual check-valve, anti-regurgitation structure claimed in the '791 Patent" Compl. ¶18 This allegation suggests the plaintiff's infringement theory is based on the presence of a structure identical to the one patented.
• The complaint asserts these products are manufactured abroad and imported for sale to consumers throughout the United States, including within the Southern District of Florida Compl. ¶19

IV. Analysis of Infringement Allegations

The complaint alleges that the Accused Products embody every limitation of at least Claim 1 of the '791 Patent Compl. ¶25 It does not contain a detailed claim chart, but asserts that the accused devices incorporate the "same dual check-valve, anti-regurgitation structure" claimed in the patent Compl. ¶18

No probative visual evidence provided in complaint.

'791 Patent Infringement Allegations

Claim Element (from Independent Claim 1)	Alleged Infringing Functionality	Complaint Citation	Patent Citation
An anus cleaner, comprising: a bottle body (1), wherein an inside of the bottle body (1) is a hollow structure; a bottom of the bottle body (1) is provided with a bottle bottom (2), and the bottle bottom (2) is curved…	The Accused Products are anus cleaners comprising a hollow bottle body with a curved bottom.	¶18; ¶25	col. 3:10-14
…a center of the bottle bottom (2) is provided with a through hole, and a steel ball check valve (3) is installed in the through hole…	The Accused Products allegedly incorporate a dual check-valve structure, including a first valve at the bottom of the bottle.	¶18; ¶25	col. 3:14-16
…an end of the bottle body (1) away from the bottle bottom (2) is provided with a bottleneck (4)…equipped with a cleaning head (5); a bottom of the cleaning head (5) is provided with threads…on a mounting table (6)…	The Accused Products include a cleaning head assembly that attaches to the bottle body.	¶25	col. 3:16-22
…a center of a bottom of the mounting table (6) is provided with a spring check valve (9), and the spring check valve (9) communicates with the flow channel…	The Accused Products allegedly incorporate a second check valve within the cleaning head assembly, which forms part of the dual check-valve anti-regurgitation structure.	¶18; ¶25	col. 3:27-29
…a bottom of the steel ball check valve (3) is provided with a limiting seat (10)…a top of the limiting seat (10) is fixed with two limiting round tables (11)…a top of each limiting round table (11) is fixed with a ball locking notch (12)…	The complaint alleges the Accused Products have the "same" structure as claimed, implying the presence of the specific internal components of the steel ball check valve.	¶18; ¶25	col. 5:25-6:4
…the cavity inside the steel ball check valve (3) is placed with a plugging steel ball (13); the cavity is oval shaped…	The complaint's allegation of the "same" structure suggests the internal cavity and ball mechanism of the accused valve matches the claim.	¶18; ¶25	col. 6:4-7

Identified Points of Contention

• Technical Question: The central factual question will be whether the Accused Products, upon physical inspection, actually contain the specific two-valve structure recited in Claim 1. The complaint's assertion of an identical structure Compl. ¶18 sets a high bar for literal infringement.
• Scope Question: A potential point of dispute concerns the highly detailed limitations of the "steel ball check valve" in Claim 1. The claim requires not just a generic ball valve, but one with a specific "limiting seat," two "limiting round tables," and a "ball locking notch" '791 Patent, col. 5:25-6:4 The infringement analysis will turn on whether the accused devices contain this exact, complex structure or merely a functionally similar one, which would raise questions about the doctrine of equivalents.

V. Key Claim Terms for Construction

• Term: "steel ball check valve"

  • Context and Importance: This term, along with "spring check valve," defines the core "double check-valve structure" that is central to the invention and the infringement allegations Compl. ¶16 Practitioners may focus on this term because Claim 1 recites a very specific set of internal components for this valve, and any deviation in an accused product could be dispositive of literal infringement.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: A party could argue the term should be understood functionally as any ball-based valve at the bottle's base that prevents backflow, pointing to the patent's overall goal to "effectively prevent the backflow of the liquid" '791 Patent, col. 2:52-54
    • Evidence for a Narrower Interpretation: Claim 1 itself acts as a lexicographer by defining the "steel ball check valve" as possessing a "limiting seat (10)," "limiting round tables (11)," and a "ball locking notch (12)" '791 Patent, col. 5:25-6:4 This explicit recitation strongly suggests that the term is limited to a valve incorporating these specific structural features.

• Term: "communicates with"

  • Context and Importance: This term defines the required fluidic connection between the "spring check valve" and the "flow channel" '791 Patent, col. 5:23-24 Its construction will determine whether an indirect or intermediated connection is sufficient for infringement.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The patent specification provides its own guidance, stating that terms like "communicated" and "connected" should be "interpreted broadly" and can include "an indirect connection through an intermediate medium" or "an internal communication between two elements" '791 Patent, col. 4:26-34
    • Evidence for a Narrower Interpretation: A party seeking a narrower scope might argue that in the context of the specific embodiment shown, the communication is direct and unobstructed. However, the patent's explicit instruction to interpret the term broadly may present a significant hurdle to such an argument.

VI. Other Allegations

• Willful Infringement: The complaint alleges that Defendants' infringement "is and has been willful, deliberate, and in knowing disregard of Plaintiff's patent rights" Compl. ¶27 This allegation is made "upon information and belief" and does not specify whether it is based on pre-suit or post-suit knowledge, making it a conclusory pleading that may be developed during discovery.

VII. Analyst's Conclusion: Key Questions for the Case

The resolution of this dispute will likely depend on the answers to two primary questions:

1. A key evidentiary question will be one of structural correspondence: does the physical construction of the accused products, once examined, map to every element of the detailed "steel ball check valve" and "spring check valve" as recited in Claim 1, or are there structural differences that would necessitate an argument under the doctrine of equivalents?

2. A central question of claim construction will be whether the term "steel ball check valve" is limited to the specific structure disclosed with a "limiting seat," "limiting round tables," and "ball locking notch," or if it can be interpreted more broadly to cover other one-way ball valve designs that prevent backflow from the bottle's base.