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Patent CN105667120B

Updated October 23, 2026

Expanding Clipboard Folder with Spring-Mounted Hinge and Catch

A clipboard or hard folder grips one thickness well: a few sheets slide around, a thick stack will not close. In this folder both edges of the cover float. The hinge is mounted on springs in the spine, and the snap catch on the opposite edge sits on a spring too, so the cover lifts evenly over a thick stack and is pulled down onto a thin one. Inside, a front lip springs up against the cover and an elastic strap with a stiff middle section holds the back edge - and takes a pen.

  • China invention patent - lapsed
  • No filings outside China
  • Office & school filing
  • Molded boards, springs, elastic strap
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Expanding Clipboard Folder with Spring-Mounted Hinge and Catch - patent drawing

📚

Grows with the stack

Springs under the hinge and the catch let the cover rise evenly over thick papers and press down on thin ones.

🔒

Spring snap catch

A hook on the cover snaps between two spring-loaded jaws on the base - closes at any thickness.

⬆️

Pop-up front lip

A spring pushes a lip up against the cover so papers cannot slide out of the front.

🖊️

Strap and pen holder

An elastic strap with a stiff middle holds the back edge and takes a pen.

🔥 Popularity – views

Bring this product to market

  1. ✓ Patent vetted China-only family and legal status checked
  2. 2 Product brief · now How it works, uses and options written up
  3. 3 Prototype First samples for buyers to review
  4. 4 Pilot run Small first batch for launch customers
  5. 5 Volume production Repeat orders at scale

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The problem

Clipboards and hard folders use a fixed clip or a fixed cover gap. Put in a few sheets and they slide; put in a thick exam bundle or a textbook-sized set of notes and the folder will not close. The patent describes the result: teachers and students need several folders for documents of different thickness, which costs more and makes filing messier.

The solution

The patent lets the cover float at both edges and holds the papers on all sides:

  1. A flat base board (1) has a spine (3) along its left edge.
  2. The cover (2) is attached to the spine by a hinge (4) whose fixed leaf sits on springs (5) set into holes in the spine - so the hinge edge can lift.
  3. On the right edge, a hook (6) on the cover snaps into a catch (9) on the base. The catch is mounted on a spring too, and holds the hook between two spring-loaded jaws - so that edge can lift as well.
  4. With a thick stack, the cover rises and the springs pull it down onto the papers; with a thin stack, the springs pull it lower.
  5. At the front, a lip (17) slides up out of a slot in a rail (16) under spring force and presses against the cover.
  6. At the back, an elastic strap (14) with a stiff middle section (15) presses the papers and holds a pen.
Expanding Clipboard Folder with Spring-Mounted Hinge and Catch - Patent drawing - folder open
Patent figure 1 - folder open: base (1), cover (2), spine (3), hinge springs (5), hook (6), catch (7-12), rear strap (13-15) and front lip (16, 17).

Who it is for

  • Office and school-supply brands wanting a folder that solves the “too thick to close” problem.
  • Teachers’ and education suppliers - lesson plans, exam papers and student work vary hugely in thickness.
  • Field-work and inspection users - a hard writing surface that holds forms tightly outdoors.
  • Promotional suppliers - a sturdy branded folder for conferences and trade shows.

How it works

The main parts

Expanding Clipboard Folder with Spring-Mounted Hinge and Catch - Patent drawing - folder from another angle
Patent figure 2 - another view: hinge (4) and springs (5) on the spine (3), hook (6) on the cover, catch (9), front rail (16) and lip (17).
No.PartWhat it does
1Base boardFlat board the papers lie on.
2CoverHinged lid that clamps the papers.
3SpineRail on the left edge with holes for the springs.
4, 5Hinge and first springsHinge leaf on springs, so the hinge edge can rise.
6HookOn the inside of the cover, with a barb at the tip.
7-12CatchSupport (7), second spring (8), catch block (9) with two sliding jaws (10) on third springs (11) and a retaining rim (12).
13-15Rear strapAnchor (13), elastic sections (14) and stiff middle (15) that holds a pen.
16-18Front lipRail (16) with a slot, lip (17) pushed up by a fourth spring (18).

Filing papers

  1. Open the cover - the front lip springs up.
  2. Lay the papers on the base and tuck the back edge under the elastic strap.
  3. Close the cover and press the hook into the catch - the jaws open, snap shut on the barb and hold it.
  4. The cover settles at the height of the stack, pulled down by the hinge and catch springs; the lip stays pressed against it.

Taking papers out

Pull the cover up and the hook out of the catch jaws, lift the cover on the hinge, and slide the papers out from under the strap.

Expanding Clipboard Folder with Spring-Mounted Hinge and Catch - Patent drawing - plan and side views
Patent figures 3-5 - side view with the cover open, top view, and front view showing the hinge springs and catch along the edges.

Applications

Teachers and lecturers

One folder for a slim handout or a thick set of exam papers.

Students

Notes, worksheets and printouts that grow during a term.

Inspectors, surveyors and delivery staff

A hard clipboard-style surface that holds forms tight in wind.

Meetings and conferences

A sturdy folder that closes on agendas of any size, with a pen always at hand.

Healthcare and hospitality desks

Charts, menus and check-in sheets that change in thickness through the day.

Where it is less suitable

  • Long-term archiving - ring binders and box files are better for permanent storage.
  • Lowest-cost promotional folders - springs and a catch cost more than a plain card folder.

Frequently asked questions

How thick a stack does it hold?

The patent gives no capacity figure; it describes a cover gap that adjusts to the stack through springs at the hinge and the catch. Maximum capacity is set by the spring travel and the spine height chosen in design.

Will a single sheet stay in place?

According to the patent, the springs pull the cover down onto thin stacks, and the front lip and rear strap stop papers sliding out of the front and back.

How does the catch work?

A barbed hook on the cover pushes between two spring-loaded jaws on the base; they spread, then close behind the barb. The whole catch sits on a spring so it can rise with the stack.

Which paper sizes can it be made for?

Any - letter, legal and A4 are the usual choices for the US and export markets.

Can it double as a clipboard?

Yes. The closed folder is a hard, flat surface, and a flat outer face can be used for writing.

Can the mechanism be simplified to reduce cost?

Yes. We can review which spring functions matter most for your market and design a lower-cost version.

Can this design be made and sold in the US?

The patent was filed only in China and has lapsed, so it does not restrict the design in the US or in China. Folders and clipboards are a crowded category - see Patent & Production - so we recommend a freedom-to-operate check before volume production.

Are you affiliated with the patent owner?

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

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  • Paper size and target capacity
  • Material and colors
  • Extras (pocket, pen strap, branding)
  • Estimated quantity and target price
  • Timeline - when you would like samples and the first shipment

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Patent CN105667120B: bibliographic data, legal status, family, a plain-language reading of the claims, plus customization, US compliance points and how a manufacturing project runs.

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This page is based on the public patent document CN105667120B, assigned to Xue Zhiyuan (individual). IP2M is an independent manufacturing service and is not affiliated with, endorsed by or licensed by the patent owner. Images marked as concept renderings are illustrations, not photos of an existing product. Patent status information is provided for reference only and is not legal advice; confirm freedom to operate for your market before production. Full disclaimer.