US 3761703

I'll verify the patent details against available sources before summarizing.

Search verification note

I searched for US 3,761,703 specifically. The results confirm the bibliographic record below (Google Patents and uspto.report both return the same document). Two caveats on identifiers, per your strict-interpretation rule:

• Search hits also surfaced unrelated documents containing the string "3761703" as part of a different identifier — e.g. "DE 3761703 T" (a German publication number) and an "EP … (11) 3761703" European validation number. These are not US 3,761,703 and I have not treated them as such.
• No CAFC 2026 docket entry for US 3,761,703 appeared in the results. That is expected: per the Google Patents legal-status field, this patent is "Expired – Lifetime," with an anticipated expiration date of 1990-09-25.

Bibliographic data (US 3,761,703)

Prior art cited: US 3,154,251 (Airmark Plastics Corp., "Panel light"); US 3,610,914 (Dana J. Blackwell, "Illuminated indicating instrument with front replaceable lamps"); US 3,638,009 (Ackerman Engravers Inc., "Miniature lighting device"); US 3,639,745 (Omron Tateisi Electronics Co., "Mounting arrangement for electrical device").

Abstract (as printed)

"A lamp cartridge for insertion in the edge of a light conductive block for distributing light to an instrument or instrument panel. The cartridge includes spring clip contacts along opposite sides thereof for making resiliently biased contact with bus bars in the light block, guides for orienting the clips in relation to an opening in the light block for receiving the cartridge, and an exposed portion facilitating manual insertion or withdrawal of the cartridge with respect to the opening."

Plain-language overview of the independent claims

Claim 1 — Plug-in lamp cartridge with self-camming spring contacts

A lighting system for an instrument face made of four cooperating parts:

1. A transparent light block mounted directly behind the dial — edge-lit, so light injected at one edge propagates through the block and escapes only at the dial indicia.
2. A lamp-receiving recess formed into the block.
3. Two spaced bus conductors (bus bars) carried by the block, with portions left exposed so they run across the recess.
4. A removable lamp assembly that slides into the recess, consisting of a lamp holder, an electric lamp carried by the holder, and exposed contact members on the outside of the holder wired to the lamp.

The inventive core is the last element: the contact members are resiliently mounted and have cam surfaces. Pushing the assembly linearly into the recess makes those cams ride over the exposed bus bars, so the same motion simultaneously (a) makes the electrical connection and (b) mechanically detains the assembly in place. In other words, no soldering, no separate fastener, and no tool are needed to install or energize the lamp — grip, push, and the spring force both powers and retains the cartridge.

Claim 5 — Same system, focused on the wiring/retention architecture of the cartridge

This independent claim covers the same four-part combination but recites the cartridge's internal construction in more detail:

• The lamp holder has a forward end (inserted first) and a rearward end, with the lamp at the forward end.
• A recess is formed in the rearward end of the holder.
• Spring contacts sit on the outside of the holder, contact the exposed bus conductors, and have their ends bent into that rearward recess.
• The lamp's wire leads also run into that rearward recess and are pressed against the spring-contact ends.
• A cap closes the assembly: its first section is force-fitted into the rearward recess, clamping the leads against the contact ends so the electrical joints stay secure; its second section projects out of the light block and is shaped to be gripped by hand (the specification describes grasping it between thumb and forefinger, thumbnail in a groove) for tool-free insertion and withdrawal.

Net effect of claim 5: a single press-fit cap both seals the electrical terminations and provides the pull-handle, making the lamp (or the whole cartridge) field-replaceable without disturbing the instrument pointer, dial, or light block.

Dependent claims 2–4 (context for the independent claims)

• Claim 2 adds the manually grippable cap feature (projecting section) to claim 1.
• Claim 3 adds the orientation features: cylindrical recess, a longitudinal groove in the recess wall, and a spline on the lamp holder that mates with it — aligning the spring contacts with the bus bars and preventing rotation from vibration.
• Claim 4 defines the contact geometry: a first section diverging outwardly (front-to-back), a second section converging inwardly, and a rounded end section, with the bus bar riding along these sections into a seated position at the juncture of the second and rounded sections.

Uncertainty / caveats

• The Google Patents page renders a "Claims (12)" heading, but the printed patent text and the claims body both show 5 claims; the "12" appears to be an artifact of how nested sub-paragraphs (1./2./3. and 1.–6.) were parsed. I am treating 5 claims as authoritative.
• I could not independently open a live USPTO Patent Center or CAFC docket record in this session; the legal-status and docket conclusions above rest on the Google Patents record and the absence of any 2026 CAFC hit in search. Given the 1990 anticipated expiration, live enforcement litigation over this patent would be implausible.
• As noted, unrelated documents sharing the "3761703" string exist; none were folded into this summary.