Asobinet, who spotted the patent, says [google translated]:
Looking at the lens configuration, it is very similar to the 18-50mm f/2.8 DC DN (not 100% match). Perhaps F2 zoom was one of the options during the examination stage of practical use lenses. However, now that F2.8 zoom has appeared, it seems unlikely that F2 zoom will see the light of day.
- [Public number] P2022038820
- [Name of invention] Large aperture zoom lens
- [Dapplication date] 2020-08-27
- [Applicant] [Identification number] 000131326
[Name or name] Sigma Corporation
- [Issue] We provide a small large aperture zoom lens that is suitable for digital cameras and video lenses, with good aberrations and can be used for quick focus operation.
-  This invention is based on a positive lead zoom lens for the above challenges, suitable for digital cameras and video lenses, with good aberrations, and quick focus movement, small large apertures. The purpose is to provide a lens.
- Focal length: 18.50-48.50
- F value: 1.94-2.10
- Angle of view: 77.86-31.58
- Statue height: 14.20
- Total length: 115.36-137.89