| 摘要 |
Safety lamp apparatus, suitable for use as a miner's cap lamp, includes a housing body closed at one side by a plastic light transmitting member. A bulb member is yieldably received in the housing body and is operable, when energized, to provide a filament in a state of incandescence for emitting visible radiation. During use of the apparatus in an explosive atmosphere conditions may arise where deformation of the light transmitting member from external impact forces directed thereagainst may drive deformed portions of the light transmitting member against the bulb member with sufficient force to cause bulb breakage and resulting explosion of the atmosphere. In the present invention protective means is provided comprising an arrangement of parts defining an oblique angular relationship between the central longitudinal axis of the bulb member and the impacting surface of the deformed portion of the light transmitting member. The protective means may, in one desirable form, include a cylindrical projection from the inner surface of the light transmitting member truncated such that the plane of truncation lies at an oblique angle to the central longitudinal axis of the bulb member. With this arrangement impact against the bulb, arising from deformation of the light transmitting member, causes angular displacement of the bulb and thus breakage is avoided. The oblique angular relationship may also be realized with other arrangements of parts as hereinafter disclosed.
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