You can freely build on How Car Windows Use Special Coatings to Balance Privacy and Visibility

What this patent covers

The invention describes a vehicle window that combines a tinted glass plate with a specific multi-layered film coating. The film consists of at least one light-absorbent layer and one non-light-absorbent layer. By carefully controlling the light transmittance (how much light gets through) and the reflectance (how much light bounces off) of both the inner and outer surfaces, the glass ensures that passengers inside have privacy while maintaining clear outward visibility. For example, by keeping the inner surface reflectance low (up to 15%), the glass prevents distracting reflections of the vehicle's interior from appearing on the window at night.

What is now free to use

All 0 claims of US 6033785 are in the public domain. Specifically:

The 0 dependent claims add narrowing limitations and are also free.

What is NOT covered

Patent expiry frees this specific invention. Separately-patented improvements made after expiry may still be protected.

• Does not cover glass panes that do not incorporate a multi-layered film with both light-absorbent and non-light-absorbent layers.

• Does not cover glass configurations where the visible light transmittance falls outside the specific 25% to 55% range.

• Does not cover smart glass technologies that use electrical currents to change opacity (electrochromic glass).

• Does not cover simple tinted glass that lacks the specified multi-layered film structure.

Who is building on this today

The technology is utilized by major automotive glass manufacturers and suppliers like AGC (formerly Asahi Glass Co., the parent of Central Glass), Saint-Gobain, and NSG Group. These companies continue to refine thin-film deposition techniques to improve thermal insulation and optical clarity in modern vehicles.

Products built on expired version of this technology

How to cite this patent in your documentation

Central Glass Co Ltd. US Patent 6033785. Vehicular colored glass pane with light transmittance and reflectance adjustment. Granted 2000, expired 2017. Now in the public domain.

Note: This is a convenience citation. Consult a patent attorney for formal freedom-to-operate analysis.

PatentBrief is an educational resource and does not provide legal advice. Patent expiration information is derived from USPTO records and may not reflect continuation patents, divisional filings, or separately-patented improvements. For commercial use or production decisions, obtain a formal freedom-to-operate (FTO) opinion from a registered patent attorney.