US 5971559

Patent Overview — US 5,971,559 A

Title: Surface light source device
Assignee: Enplas Corp (original and current assignee as listed)
Inventor(s): Tsuyoshi Ishikawa; Kayoko Watai; Kazuaki Yokoyama
Application No.: US 09/084,008 | Filed: 1998-05-26
Published/Granted: 1999-10-26
Priority date (as listed): 1994-08-12
Anticipated expiration: 2014-08-12 | Status: Expired – Fee Related
Source: https://patents.google.com/patent/US5971559/en

Purpose and plain-language scope (per the excerpt): The patent concerns a surface light source device that uses a light conducting member. As described, the device includes a light conducting member (11); a linear light source (12) near one edge surface (11a, the light incident surface); a diffusion plate (13) on or adjacent the light emitting surface (11b); and a reflective surface (14) on or adjacent the opposite side surface (11c). Light enters the incident surface, travels within the conducting member toward the opposite edge, and is emitted from the light emitting surface; the emitted light passes through the diffusion plate to provide a diffused surface light. To improve light-emitting efficiency and obtain a uniform brightness distribution on the diffusion plate, a pattern of fine diffusing portions (20) is formed on the opposite side surface (11c), e.g., by printing with a light-diffusing paint material. The excerpt notes such devices are used, for example, as a backlight for a liquid crystal display.

What the excerpt does not establish:

• The full text of the claims, and therefore the precise legal scope of coverage.
• The complete specification, drawings, or all described embodiments.
• The specific prior-art references cited or relied upon during examination.
• Any litigation, ownership transfers, or validity determinations (also excluded by instruction).
• Whether the listed dates, assignee, and legal status are accurate, as the source itself characterizes these as assumptions or non-legal conclusions.