Invalidity dossier
US 3833297
Automatic brightness control for photographic projectors
Current assignee: Sears Roebuck and Co
Added 9/24/2026, 1:41:53 AM
Active provider: DeepSeek · deepseek-flash
Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview — US 3,833,297
Title: Automatic brightness control for photographic projectors
Source: https://patents.google.com/patent/US3833297/en
Bibliographic data (per supplied text):
- Patent number: US 3,833,297 A
- Application number: US00234281A (US23428172A)
- Inventor: J. Swartz
- Original assignee: Sears Roebuck and Co (listed current assignee: Sears Roebuck and Co)
- Priority/filing date: 1972-03-13
- Publication/grant date: 1974-09-03
- Legal status (as stated, an assumption and not a legal conclusion): Expired – Lifetime; anticipated expiration 1991-09-03
- Classifications include G03B23/00, G03B21/14, G03B21/20, G03B21/202 (incandescent light sources), G03B21/2053 (intensity control of illuminating light)
Purpose and plain-language scope (from the supplied text):
The patent describes a photographic projector that automatically controls the illumination produced by a projection lamp according to the intensity of the light image of a transparency projected onto the projection lens. The projector includes projecting means with light source means and projection lens means along an optical projection path, light intensity sensing means mounted adjacent that path for sensing the intensity of the light image projected upon at least a portion of the projection lens surface facing the transparency, and potential control means operably connected to the sensing means to control the potential applied to the light source. The sensing means is preferably a photoconductive cell such as a Cadmium-Selenium cell, and a solid-state circuit is provided as the potential control means.
The stated advantage is compensation based on the density of the transparency as a whole, sensed within the projector rather than off the viewing screen, avoiding ambient-light and screen-texture effects and eliminating a previewing station and second optical path. The abstract also states the light intensity sensing means and potential control means. Figures 1 and 2 are a schematic projector diagram and a schematic circuit diagram, respectively.
What the excerpt does not establish:
The supplied text is a partial excerpt. It does not include the full claim set (claim 1 is not reproduced), the complete description, the full reference numerals, or the omitted Cadmium-Selenium passage tail. Full claim scope, claim count, and dependent-claim details cannot be verified from it.
Generated 10/1/2026, 9:31:13 PM
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Litigation summary
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Proceedings on file (0)
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PTAB challenges
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Assignment history
Inventors, original assignee, and the chain of ownership recorded with the USPTO — including the correspondent attorney who recorded each assignment, since shell-LLC chains often share one repeat-player attorney even when the entity names look unrelated. Surfaces NPE / patent-troll patterns: shell-entity transfers, known asserters in the chain, repeat correspondent fingerprints, pre-litigation assignments, and bankruptcy fire-sales.
Prior art
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Obviousness
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Extensions
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Derivative works
Defensive disclosure: derivative variations of each claim designed to render future incremental improvements obvious or non-novel.