1. Field of the Invention
The present invention relates to reflective warning devices which are useful for alerting motorists to the presence of other vehicles and road hazards.
2. Description of the Prior Art
The prior art has previously provided warning devices of both an active and passive nature which act to warn of the presence of a dangerous condition, particularly a road hazard associated with moving or stationary vehicles. Active visual devices particularly include lights disposed on a vehicle or on a stationary object intended to warn of a dangerous condition, it having been previously appreciated that a flashing light is more effective in alerting observers to the presence of potential dangers. However, active visual devices must be operated by a source of power such as a battery or the like which causes the light to repetitively flash on and off. As is obvious, such active devices require a substantial amount of energy for operation and are also costly. Passive visual warning devices, particularly reflective devices wherein light from vehicle headlights or other sources are reflected to observers, are also known in the art. Such reflective devices have even been caused to provide a flashing effect by intermittently obscuring at least portions of a reflective surface. For example, LaLonde, in U.S. Pat. No. 3,528,721, causes a flashing effect of a reflective device by mounting the device against the wheel of a bicycle so that rotation of the wheel causes the reflective device to oscillate. Priest, in U.S. Pat. No. 3,551,024, discloses a flashing retroreflective reflector in which a convex lens focuses incoming light on a retroreflective medium, the device being oscillated such that retroreflection is obtained only when incoming light is incident along the axis of the lens. Hammer, in U.S. Pat. No. 2,869,424, provides a passive warning signal device wherein portions of a reflective surface are intermittently obscured by spring mounted masking plates, the masking plates being oscillative due to motion of the vehicle carrying the reflective device. Klaenhammer, et al., in U.S. Pat. No. 4,023,888, provides a reflective structure having portions thereof intermittently obscured by a swinging masking member, the swinging member being driven by a motor. However, the prior art has not provided a passive visual warning reflector device capable of producing a "flashing" visual signal on mounting of the device to either a stationary or potentially movable object. A free-swinging portion of the present device has means formed thereon which are actuable by air currents to be operable both when the structure on which the device is mounted is moving and also when the structure is stationary, as long as air is circulating about the device when the structure is stationary.