Capacitive Sensors

InsCaps product for Capacitive sensor (click on Sensor type to view full explanation)

S-CATS (Segment Capacitive Anti-finger-Trap Sensor) a capacitance proximity sensor to detect objects in power closing panels

CPS (Capacitive Proximity Sensor) a capacitance proximity sensing to detect objects

S-CATS (Segment Capacitive Anti-finger-Trap Sensor),
a capacitance proximity sensing to detect objects in power closing panels

sensor position in Sliding power doors

sensor position in elevator doors

The capacitance "anti-squeeze sensor" for power closing doors (including elevator doors) consists of the electronics and a sensor probe. The sensors elements are embedded or attached to the leading edge of the door. The sensor is sensitive to objects of high dialectric value (i.e. human body part) at a user selectable distance of 0 to 10 cm from the sensor probe. When the object is detected (i.e. a body part) the power closing door can be made to reverse and thus prevent the trapping of a body part. The sensor's unique design and placement of the sensor elements enable it to distinguish between the opposing power closing door and the body part. In addition, the patented design enables the sensor to detect object that have low dialectric properties.

The sensor can be designed so that:
The sensor electronics would fit in the door frame
The sensor would transmit a signal to a receiver incorporated in the door controller, which would reverse the door if an object were trapped in path of the closing door.
The sensor would be battery powered (lasting up to 7 years) and require no hard wiring to the existing door.

The power doors close normally when there is no object present.


When an object ( Lady Lara) is detected between the closing doors, the sensor triggers to open the power closing door before the door compresses her

Theoretical Functioning of Sensor

working prototype of the S-CATS
preventing a hand from being trapped
in power closing sliding door


(Segment Capacitive Anti-finger-Trap Sensor)
for power closing doors

The S-CATS (Segment Capacitive Anti-finger-trap Sensor), is a capacitance proximity sensor used to detect objects in powered closing panels. The capacitive sensor system prevents the pinching or trapping of a human body part or foreign object by a power-closing panel. The body part or object is sensed either before contact or at the time of contact with the sensor electrode by a change in capacitance. When the object or body part is detected, the power closing panels is reversed or stopped to prevent the trapping of the object.
The sensing probe consist of multiple segments. Each segment detects the capacitance of the sensed object and the adjacent environment. The capacitance value for each of the segments are analyzed in real time and compared against the average of the highest value obtained for a certain number of segments. When the capacitance of one or more segments is less than the average of the capacitance of all or some of the segments minus a predetermined constant, the sensor system is triggered.

Metal Bar (representing a power closing panel) approaching segmented capacitor probe

A Finger (i.e. trapped body part) touching a metal bar (i.e. power closing panel) approaching segmented capacitor probe

computer screen in background indicates capacitance values

Click here to view Abacus Optical Mechanics Capacitor sensors

Click here to view Capacitive proximity sensor
To contact us:
Anthony Bledin
612 Meadow Grove Lane
Westlake Village, CA 91362
Phone: 805-494-4490
Fax: 805-494-9948
updated October 31, 2003