1. Field of the Invention
This invention relates to windshield wipers and more particularly to a windshield wiper system including a service life indicator for showing when the wiper blades should be replaced.
2. Description of Prior Art
Automotive users and installers find it difficult to know when it is time to change wiper blades. Normally the user does not notice the gradual reduction in wipe quality. Unless it is raining the user has no way of knowing that the wiper blades may not perform properly next time they are used.
Ozone in the atmosphere is one of the major contributors leading to the failure of a wiper blade. Prolonged exposure to ozone will degrade most rubber compounds. This causes chatter as the blade does not flip from side to side during the wipe. It also weakens the rubber resulting in attrition of the rubber and cracks occurring on the wiping edge. These cracks leave streaks on the windshield when it rains.
Because of the ozone affect most manufacturers recommend that the wiper blades are replaced every six months. However since the amount of ozone exposure varies geographically, the wiper blade real service life varies. The wiper blade life can be as low as 3 months in areas of high ozone concentration to as much as 2 years in other areas.
Since the deterioration of the wiper blades is a gradual process, user will often continue to use the wiper blades long past their useful life. When the wiper blades are used beyond their useful life the vehicle operators vision may be obscured. Therefore, it is desirable to provide a compact, economical indicator for showing the vehicle operator when the windshield wiper blades should be replaced.
U.S. Pat. No. 5,349,718 discloses a wiper blade having an indicator painted on the wiper blade which changes color after being exposed to UV light for a period of time. The indicator paint is a silicone resin paint and would be applied to a wiper blade made of a resilient elastomeric material which is degraded with exposure to UV light in the atmosphere.