Patent TRIVIA CONTEST: Fluid-Filled Lens

One of our loyal readers sent in a TRIVIA question about camera lens technology.  Before going to law school, I spent some time as a consultant for a major lens manufacturer, so this topic is also of interest to me.

Both Philips Electronics and Varioptic have patents on fluid-filled camera lenses. The IP dispute between these two companies will likely become quite hot in the near future. [link, link].

However, neither company has made any public reference to a seminal U.S. Patent that teaches a fluid lens that was patented before World War II (WWII).  This patent has no prior art cited against it, has 14 independent claims and no dependent claims. 

Contest: Can you find that seminal patent? A quite small non-monetary prize for the first correct answer.

9 thoughts on “Patent TRIVIA CONTEST: Fluid-Filled Lens

  1. 9

    In fact fluid-filled lenses go back to at least the 18th century in the literature and there was a rather nice one patented by Cusco in Paris in 1879…

    If you read the refs in my research papers you should find these which predate all the 20th century stuff…

    Joshua Silver

  2. 8

    The patent has been found — Thanks for everyone who participated!!! I’ll post a note on it later today or tomorrow. (I want to hear from the winning searcher whether he/she want to be publicly revealed as the search contest winner.)

  3. 7

    I searched Google to find references (not in the technical sense) to candidate patents. I took the numbers and ran them through the EPO to get the pdfs (whose database is faster than the PTO’s).

    link to

  4. 4

    This one is pretty hard, so maybe we ought to work together.

    I figure that the World War II comment isn’t a red herring, and thus the patent came out in 1930-1939.

    With Google, you can search for patents that would have been issued then.
    [numrange:1700000..2400000 patent]

    Having used this with “camera,” “lens,” “~fluid,” “~liquid,” “filled” and various combinations thereof, it seems that there is a reasonably good chance that the patent is not on more than a few sites on Google. Searching for numbers between 1930 and 1939 also seems useful.

    I then spent some time going through patents between 1930 and 1939 by classification. I tried a few in 359 (optics), in particular 359/832 (fluid-filled).

    Generally, once I have a lead, I just check the number of claims. If there aren’t 14, I move on.


  5. 3

    How about:

    504,890 – Ohmart “Device for reflecting and refracting radiant energy” – 1893 (Gas or liquid introduced to change shape of lens)
    1,269,422 – Gordon “Lens” – 1918 (eyeglasses)
    1,378,011 – Cregier “Telegraph Register Receiving Apparatus” (Fluid lens to enlarge ticker tape)

  6. 2

    no, don’t think so, Kevin. No. 1’515’389 uses liquids for shading, not for refraction. No. 2’051’791, inventor Leonhard E. Luce, filed April 16, 1935, however, uses liquid for refractioning.

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