Vehicle lamp
AssigneeKoito Manufacturing Co., Ltd.
InventorsTakahiro Kohata, Toshimasa Ikeda
Life of this patent
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Abstract
In a vehicle lamp of the present disclosure, a lamp body is made of an acrylonitrile styrene acrylate (ASA) resin, which has a glass transition temperature lower than that of a poly(methyl methacrylate) PMMA resin constituting a light transmissive cover. That is, with respect to the glass transition temperature Tg1 of the PMMA resin constituting the light transmissive cover, the glass transition temperature of the ASA resin constituting the lamp body is set to Tg1>Tg2. Thus, it is possible to generate not a tensile residual stress but a compressive residual stress in a welding portion between the lamp body and the light transmissive cover, thereby enhancing the solvent resistance of the light transmissive cover. And, thus, an annealing process after the welding is unnecessary, or simply performed.
Claims9
A vehicle lamp comprising:
- a lamp chamber formed by welding a resin lamp body and a resin light transmissive cover;
- and
- a light source disposed in the lamp chamber,
- wherein the light transmissive cover is made of a poly(methyl methacrylate) (PMMA) resin,
- the lamp body is made of an acrylonitrile styrene acrylate (ASA) resin, and
- a glass transition temperature of the ASA resin is set to a value lower than that of the PMMA resin constituting the light transmissive cover such that a compressive residual stress is generated at a side of the light transmissive cover in a welding portion of the lamp body and the light transmissive cover.
Dependencies are inferred from the claim text.