Rain Sensor Description and Operation

Description

1. Wiper Control System: When the "AUTO" switch signal is received from the multifunction switch on the right, the integrated rain sensor detects the amount of rainfall. The sensor is installed inside the upper part of the front windshield. This system automatically controls the operating duration and speed of the wiper based on the measured amount of rainfall, even if the driver does not operate the wiper switch.

   

Functions and Operating Principle

1. 1
   Rain Amount Detection: Light (beam) emitted by the light-emitting diodes (LEDs) is totally reflected on the outer surface of the windshield and returns to the photodiodes. When water is present on the outer surface of the windshield, the light is optically separated and partially reflected, and the remaining brightness is measured by the photodiodes. Water remaining on the windshield prevents total reflection of the light. The loss of brightness caused by this indicates how wet the glass surface is.
2. 2
   Dust on the measuring surface and other surfaces in the light path (surface of the LEDs and photodiodes, optical fiber, bracket, and glass surface near the windshield contact area) weakens the received light.
3. 3
   Movement of the windshield and bracket
4. 4
   Movement of the bracket due to vibration
5. 5
   Damaged wiper blade

If the built-in rain sensor is not operating or is malfunctioning, the driver must turn on the wiper switch manually.

1. 1
   Rain Sensor Operating Condition

   Operation Mode	Operation
   Direct Mode	This is the normal operating condition of the built-in rain sensor when the wiper switch is in the "AUTO" position and the sensor detects a dry windshield. Based on this condition, the built-in rain sensor determines the wiper operating mode according to the amount and duration of precipitation.
   Intermittent Mode	The built-in rain sensor activates intermittent mode when wiper operation is performed consecutively more than two times with an interval of 0.5 to 5 seconds.
   Low speed	Wipers operate continuously at low speed
   High speed	Wipers operate continuously at high speed

2. 2
   When ice or foreign objects are present in the detection area, the built-in rain sensor cannot correctly recognize the operating conditions.
3. 3
   Rain sensor

   Special Condition	Operation Based on Special Condition Detection
   Hesitation	When the built-in rain sensor detects a high level of water (splash) in Direct or Intermittent mode, the system switches from park mode to High speed. Then wiping is performed once in High speed mode and once more in Low speed mode. If the precipitation condition does not change after wiping, it returns to the original state (Direct or Intermittent).
   Smearing	Smearing is a thin oil film that dries quickly and occurs when a small amount of precipitation is smeared by a dirty or worn wiper blade. The operating signal must not be output when smearing occurs in Direct or Intermittent mode.
   Mud	If no change is detected after wiping, the built-in rain sensor determines that the windshield is contaminated. In this condition, the operating signal must not be output. If the windshield becomes clean (for example, by washer fluid), the built-in rain sensor returns to the normal condition.
   Washer Fluid	The built-in rain sensor does not respond to washer fluid in washing mode. In other words, the wiping speed does not change even when washer fluid is sprayed (automatic operation of the washer pump does not affect the operation of the built-in rain sensor).