Adjustable Mask Ear Strap with Internal Worm-Gear Tensioner

Patent & Production

At a glance

What the claims cover, in plain language

Claim 1 - a mask ear strap comprising a wire adjustment plate with an internal cavity. Inside, a rotating body consists of two shafts connected by a transmission worm that meshes with gears on each shaft. Ear straps are fixed to these shafts and pass through the plate walls. An external control switch includes a locking rod that slides into the cavity. The rod has a lock hole capturing the worm shaft and internal locking teeth that engage a second gear on the worm to prevent rotation. The strap ends feature fixing plates with pins and detachable buckles.

Claim 2 - specifies two straps per side arranged around the first gears, with sliding earmuff covers positioned outside the adjustment plate for comfort.

Claim 3 - details the buckle mechanism: the pin has a conical head larger than its shaft diameter. The buckle body contains a slide groove with a matching through hole and conical groove, plus a movable slide plate with an open slot narrower than the conical head base.

Claim 4 - adds a switch inside the buckle cavity connected to the slide plate via a through-hole slide groove, allowing manual release.

Claim 5 - specifies a guide column and spring inside the buckle cavity to bias the switch toward the locked position.

This is a simplified reading for orientation only. The legal scope is defined by the exact claim wording in the official Chinese document.

What this means for US production

This patent was filed in China and is currently in force there. The public record shows no US or other foreign counterpart. Therefore, making or selling this specific configuration in China requires the owner’s permission. In the United States, the absence of a US patent means this particular design is not restricted by this document alone.

Two points to settle early:

• Other patents may exist. Personal protective equipment accessories and mechanical fasteners are heavily patented fields globally. A freedom-to-operate (FTO) review is essential before tooling, particularly regarding worm-gear tensioners and quick-release buckle mechanisms used in eyewear, helmets, and medical devices.
• Material compatibility. Straps contacting skin must meet biocompatibility standards depending on final application (medical vs. consumer), affecting material selection and processing methods.

Customization and manufacturing

What can be customized

Things to plan for (US market)

• FDA 21 CFR 800/801 - if marketed as a medical device accessory, labeling and registration requirements apply.
• ASTM F963 - toy safety standard applies if sold alongside children’s masks or play sets.
• CPSC lead/phthalates - surface coatings and plastics must comply with limits for consumer products.
• California Prop 65 - warning required if certain chemicals in adhesives or dyes exceed thresholds.

How a project runs

1. Inquiry - specify target cost, volume, and intended use case.
2. Design - finalize gear pitch, strap width, and buckle interface geometry.
3. Prototype - CNC machined or 3D printed housings with functional gears.
4. Pilot run - injection molded parts assembled with sewn straps for durability testing.
5. Production - mass molding, stitching, sub-assembly, and packaging.

Quantities & timeline

Injection molds for the adjustment plate and buckle components are the primary upfront cost driver. Sewn strap assemblies require automated feeding lines for high-volume consistency. Cycle life testing for the worm mechanism takes significant development time. Send us your estimated quantity, target retail price, and usage scenario and we will reply with options.

Production notes

Tooling and process

Likely requires multi-cavity steel molds for the adjustment plate and buckle components. TPU injection molding is typical for flexible strain-relief areas near strap exits. Fabric cutting and sewing operations integrate the webbing with the rigid hardware. Heat pressing may bond synthetic layers to prevent fraying.

Cost drivers

Fabric grade typically affects tactile feel and durability. Stitch density influences tensile strength at anchor points. Sole mold analogy does not apply here, but gear precision impacts noise and backlash. Number of sizes reduces if adjustable range covers all heads. Packaging complexity rises if instructions for use are mandatory.

Prototyping path

We would typically start with a sewn first sample using off-the-shelf buckles to validate ergonomics. Then produce 3D-printed or cast components for the worm mechanism to test torque ratios. Wear trial assesses comfort of earmuff covers under sustained tension. Fit grading confirms adjustment range sufficiency.

What we would change before tooling

We might simplify the locking rod guide tube if tolerances prove difficult to hold in plastic. Consider replacing the torsion spring with a detent ball for lower part count. Verify whether the conical pin buckle withstands repeated lateral loads without deformation.

Common failure points

Seam slippage is a likely issue if strap attachment to shafts lacks reinforcement. Hardware corrosion affects metal pins in humid environments. Shaft and bearing alignment issues cause binding in the worm drive. Spring fatigue leads to premature unlocking. Wall thickness variations create weak spots in the adjustment plate cavity.

Patent drawings

Drawings reproduced from the public patent document for reference.

Frequently asked questions

How does the adjustment work?

You pull the external locking rod away from the plate to disengage the internal brake. Then you rotate the rod (or the exposed worm end) to wind both straps simultaneously. Pushing the rod back in locks the worm gear, holding the tension securely.

Will it loosen over time?

No, provided the locking rod remains engaged. The worm gear mechanism resists back-driving under load, unlike elastic bands that creep. The spring-loaded rod maintains constant pressure on the locking teeth.

Is it compatible with all masks?

It attaches via detachable buckles at the strap ends. These connect to standard mask ear loops, hook-and-loop tabs, or dedicated anchor points. Universal adapters may be needed for some proprietary designs.

What materials are used?

The adjustment plate is typically injection-molded plastic (ABS or nylon). Straps are woven elastic or polyester webbing. Gears and shafts may be plastic or metal depending on load requirements. Earmuff covers are soft foam or silicone.

Can I wash it?

Yes, generally. Remove the mask body first. Hand-wash the strap assembly with mild soap and air dry. Avoid machine washing, which can tangle straps or damage the delicate gear alignment.

Does it hurt behind the ears?

The sliding earmuff covers distribute pressure over a wider area. However, excessive tightening can still cause discomfort. Use the adjustment to achieve a snug seal, not maximum compression.

Can this design be made and sold in the US?

The patent is in force in China, but the public record shows no US counterpart. Therefore, this specific design is not restricted by this patent in the US. Other patents may cover similar mechanisms, so a freedom-to-operate check is recommended before mass production.

Are you affiliated with the patent owner?

No. IP2M is an independent design and manufacturing service working from the public patent document.

Request a quote

Click Request a Quote below to see our email address - copy it, or open your email app with a ready-made message. Please mention patent CN112535333B in the subject.

Helpful details to include:

• Your company and channel (PPE distributor, medical brand, consumer electronics, sports gear)
• Target quantity and annual volume
• Intended use (medical, industrial, consumer) to determine compliance needs
• Strap material preference (elastic, silicone, fabric)
• Color and finish requirements
• Timeline - when you would like samples and the first shipment

You can also reach us at (332) 203-9997.