Entrapment detection and prevention device for opening/closing mechanism

• US 7,984,655 B2
• Filed: 05/18/2009
• Issued: 07/26/2011
• Est. Priority Date: 06/19/2008
• Status: Active Grant

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Inventors: Ogawa, Shunichi
• Primary Examiner(s): NOORI, MASOUD H
• Application Number:
  US12/467,306
• Publication Number:
  US 20090314098A1
• Time in Patent Office: 799 Days
• Field of Search: 737/80, 738/626.26
• US Class Current: 73/780
• CPC Class Codes: E05F 15/46 responsive to changes in electrical capacitance
• CPC Class Codes: E05Y 2900/55 Windows
• CPC Class Codes: H03K 17/955 using a capacitive detector
• CPC Class Codes: H03K 2017/9604 characterised by the number of electrodes

Abstract

An entrapment prevention and detection device for an opening/closing mechanism detects entrapment with a simple structure and does not occupy much space. When a foreign object, such as a human body part approaches a window glass, such as an automobile window, the capacitance of a capacitive sensor increases. A control circuit compares a most recent capacitance obtained by a capacitance detection circuit with a previous value and if the most recent capacitance value is greater than the previous value, when the glass is being raised (closed), the control circuit determines that a foreign object has approached the glass and then stops or lowers (opens) the glass.

Claims

1. An entrapment prevention device for an opening/closing mechanism including a capacitive sensor arranged on at least one of a movable body, which opens or closes a space when an actuator is driven, and a receiving position, at which the movable body is received at a fully closed position, wherein the entrapment prevention device detects a foreign object between the movable body and the receiving position with the capacitive sensor during a closing movement and avoids entrapment of the foreign object between the movable body and the receiving position, the entrapment prevention device comprising:

an actuator drive means for driving the actuator to perform an opening/closing movement with the movable body;

a capacitance calculation means for receiving a detection signal from the capacitive sensor and calculating a present capacitance;

a memory for storing the capacitance calculated by the capacitance calculation means;

a comparison circuit for comparing a most recent capacitance calculated by the capacitance calculation means with a previous capacitance stored in the memory;

a determination means for determining whether a foreign object is located between the movable body and the receiving position based on the comparison of the comparison means; and

an actuator drive control means, connected to the determination means, for outputting a drive control signal to the actuator drive means to stop the movable body or perform an opening movement of the movable body by the actuator when the determination means determines that a foreign object is located between the movable body and the receiving position, and

wherein the capacitive sensor comprises a plurality of paired sheet or film electrodes disposed proximate to an outer perimeter of the one of the movable body and the receiving position.

2. The entrapment prevention device of claim 1, wherein

the determination means determines that a foreign object is located between the movable body and the receiving position when, in the comparison means, the most recent capacitance calculated by the capacitance calculation means is greater than a previous capacitance stored in the memory.

3. The entrapment prevention device of claim 1, further comprising:

a position calculation means for calculating the position of the movable body based on a detection signal from a position sensor that detects the position of the movable body, and

wherein the capacitance calculation means calculates the most recent capacitance whenever the movable body is moved by a predetermined distance in a closing direction.

4. The entrapment prevention device of claim 3, wherein the previous capacitance compared with the most recent capacitance was the most recent capacitance calculated at the time when the movable body was located at a previous position before the capacitance calculation means calculated the most recent capacitance.

5. The entrapment prevention device of claim 3, wherein the previous capacitance compared with the most recent capacitance is an average value of most recent capacitances calculated when the movable body was located at a plurality of predetermined positions before the capacitance calculation means calculated the most recent capacitance.

6. The entrapment prevention device of claim 5, wherein the movable body is a window glass arranged in a door of a vehicle.

7. An entrapment prevention device for an automobile window, wherein a glass of the window moves within a frame between an open position and a closed position, the entrapment prevention device comprising:

a capacitive sensor comprising a plurality of paired sheet or film electrodes that generates a detection signal, wherein the paired electrodes are arranged proximate to a first edge of the glass, and wherein the first edge of the glass is received within the frame when the window is in the closed position;

an actuator that moves the glass between the open position and the closed position;

a capacitance calculation means coupled to the capacitive sensor that receives the detection signal from the capacitive sensor and calculates a current capacitancae;

a memory coupled to the capacitance calculation means for storing the current capacitance;

a comparison circuit for comparing a most recent capacitance calculated by the capacitance calculation means with a previous capacitance stored in the memory means;

a determination means for determining whether a foreign object is located between the glass and the window frame based on the comparison by the comparison means; and

an actuator drive controller that outputs a drive control signal to the actuator to stop the glass from moving towards the frame when the determination means determines that a foreign object is located between the window and the frame.

8. The entrapment prevention device of claim 7, wherein the drive control signal output by the actuator drive controller stops the glass from moving towards the frame and reverses the direction of movement so that the glass moves away from the frame.