Electrically foldable rearview mirrors

• US 5,315,442 A
• Filed: 12/28/1992
• Issued: 05/24/1994
• Est. Priority Date: 12/26/1991
• Status: Expired due to Fees

• Current Assignee: Murakami Kaimeido Co Ltd (Murakami Corporation)
• Original Assignee: Murakami Kaimeido Co Ltd (Murakami Corporation)
• Inventors: Sato, Hidenori, Iwanabe, Naoto
• Primary Examiner(s): Ben, Loha
• Assistant Examiner(s): Robbins, Thomas
• Application Number:
  US07/997,245
• Time in Patent Office: 512 Days
• Field of Search: 359/841, 359/877, 318/469, 318/286, 73/1 D, 361/23, 361/54
• US Class Current: 359/877
• CPC Class Codes: B60R 1/074 for retracting the mirror arrangements to a non-use position alongside the vehicle

Abstract

The electrical control system for an electrically powered foldable rearview mirror having a mirror body mounted on a hollow supporting shaft extending from a supporting base so as to be movable between a folded state and an erected state, comprises a reversible motor and reduction gear drive contained in the mirror body; a motor drive circuit connected to the reversible motor to drive the mirror body between the folded state and the errected state; a mechanical stop device to stop rotation of the mirror body when the mirror body reaches the erected state or the folded state including convex and concave portions on the a root portion of the shaft and mirror body respectively; a noncontacting sensor for detecting a halt to motor rotation as a result of a halt of mirror body rotation; and a control circuit for interrruption of the motor drive circuit when the noncontacting sensor detects the halt of the motor rotation.

Claims

1. An electrical control system for an electrically powered foldable rearview mirror having a mirror body movable between a folded state and an erected state, said electrical control system comprising:

a reversible motor contained in a mirror body movable between a folded state and an erected state;

motor drive circuit means connected to the reversible motor to drive the motor body between the folded state and the erected state;

mechanical stop means to stop rotation of said mirror body when said mirror body reaches the erected state and also when said mirror body reaches the folded state;

noncontacting sensor means for detecting a halt to motor rotation as a result of a halt of mirror body rotation;

control circuit means for interruption of said motor drive circuit means when said noncontacting sensor means detects the halt of motor rotation, said control circuit means including power circuit means;

switching means for switching the motor drive circuit means on and off, said switching means including a switching transistor having a base;

sensor circuit means connected to said noncontacting sensor means to generate a plurality of pulses according to a rotation frequency of said motor; and

sensor pulse processing means including a differentiation circuit having a capacitor and resistor, and wherein said differentiation circuit is connected electrically to the sensor circuit mean, the capacitor of the differentiation circuit is charged and discharged by said pulses and is connected to the base of the switching transistor to turn said switching transistor off and on.

2. An electrical control system for an electrically powered foldable rearview mirror as defined in claim 1, further comprising a supporting base and a supporting shaft having a root portion connected to the supporting base, said mirror body being rotatably mounted on said supporting shaft so as to be movable between the erected state and the folded state, and wherein said mechanical stop means is provided in the vicinity of said root portion of said supporting shaft, and said mechanical stop means comprises convex and concave portions positioned on said root portion and said mirror body respectively and structure to stop said mirror body in the erected state and the folded state and said motor is structured so as to be unable to generate sufficient torque to overcome said mechanical stop means.

3. An electrical control system for an electrically powered foldable rearview mirror as defined in claim 1, wherein said motor has a motor drive shaft and said noncontacting sensor means comprises a reflected light photodetector and light source mounted on a printed circuit board not rotating with the motor drive shaft and a reflecting plate attached nonrotatably to the motor drive shaft and structured and positioned so as to reflect light from the light source to the reflected light photodetector when said reflecting plate rotates with said motor drive shaft.

4. An electrical control system for an electrically powered foldable rearview mirror as defined in claim 1, wherein the motor has a motor drive shaft and said noncontacting sensor means comprises a magnet attached nonrotatably to the motor drive shaft and a magnetic sensitive element not rotating with the motor drive shaft and structured and positioned so as to produce a signal indicative of motor drive shaft rotation frequency.

5. An electrical control system as defined in claim 1, wherein said sensor pulse processing means also includes a second differentiation circuit comprising a second capacitor and a second resistor and a second switching transistor having a base and a collector, said second differentiation circuit being directly connected to said sensor circuit means to receive said pulses from said sensor circuit means and also to the base of said second switching transistor, and said collector of said second switching transistor being connected to said first capacitor of said first differention circuit to control a charge state of said first capacitor and said first switching transistor.

6. An electrical control system as defined in claim 1, further comprising a supporting base and a supporting shaft having a root portion connected to the supporting base, said mirror body being rotatably mounted on said supporting shaft so as to be movable between the erected state and the folded state.