The four sensor types of ultrasonic sensors

Ultrasonic proximity sensors

  • Design and operation

    A special sonic transducer is used for the ultrasonic proximity sensors, which allows for alternate transmission and reception of sound waves. The transducer emits a number of sonic waves which are reflected by an object, back to the transducer. After emission of the sound waves, the ultrasonic sensor will switch to receive mode. The time elapsed between emitting and receiving is proportional to the distance of the object from the sensor.

     

    Digital output

    Sensing is only possible within the detection area. The required sensing range can be adjusted with the sensor's potentiometer. If an object is detected within the set area, the output changes its state. The built-in LED indicates this change.

    Ultrasonic proximity sensors with Teach-in procedures

    All adjustments are carried out via the internal Teach-in button or the external Teach-in wire. Adjustment switching point Sde

    1. Adjustment mode: Press the Teach-in button or connect the white Teach-in wire to +Vs for approx. 2 secs until the LED flashes green. Release the button or disconnect Teach-in wire.

    2. LED flashes green. Place the target at the required scanning range and press the Teach-in button or connect the external white Teach-in wire shortly to +Vs.

    3. Successful completion of Teach-in procedure is confirmed by LED being „on“ for approx. 2 secs.

    Teach-in lock

    The Teach-in function is locked five minutes after power up or five minutes after the end of the last Teach-in process.

    Resetting to original factory settings

    Holding the button down or connecting the white Teach-in wire to +Vs for > 6 secs, will automatically restore the original factory setting. Fast flashing of the LED indicates successful completion of the resetting.

Ultrasonic 2 point proximity switches

  • The button that thinks

    Ultrasonic sensors with the "Teach-in" function are similar to the standard range of products but have the added versatility of a simple touch key set up. The switching points (Sde 1 and Sde 2) may be easily programmed within the sensing range by means of the built-in Teach-in button.


    Simple operation:

    • Adjustment switching point Sde 1

    1. Adjustment mode: Press the Teach-in button for approximately 2 secs until the LED flashes green. Release button.

    2. LED flashes green. Place the target at the required scanning range and press the Teach-in button.

    3. Successful completion of Teach-in procedure is confirmed by LED „on“ for approximately 2 secs.

    • Adjustment switching point Sde 2

    1. Adjustment mode: Press the Teach-in button for approximately 4 secs until the LED flashes yellow. Release button.

    2. LED flashes yellow. Place the target at the required scanning range and
    press the Teach-in button.

    3. Successful completion of Teach-in procedure is confirmed by LED „on“ for approximately 2 secs.

     

    Resetting to original factory settings

    Holding the button down for > 6 secs, will automatically restore the original factory setting. Fast flashing of the green/yellow LED indicates successful completion of the resetting.


    Functional diagram

    Options

    • Remote Teach-in input
    • Synchronisation-/Multiplex output

     

    Advantages

    • Set up configuration is saved on an internal EEPROM ensuring long term stability.
    • Simple one button set up, no tools required
    • Teach-in lock; the Teach-in function is locked five minutes after power up or five minutes after the end of the last Teach-in process.

Ultrasonic retro-reflective sensors

  • Description

    The retro-reflective ultrasonic sensor is similar in operation to the ultrasonic proximity sensor. The distance from the sensor to the reflector or to an object within the sensing distance is determined by measuring the propagation time. Any sound reflecting, stationary object can be used as a reflector. The sensing distance Sd (distance sensor-reflector) can be adjusted to the set up conditions with the sensor's potentiometer. As long as the measured propagation time of the ultrasonic signal corresponds to the distance from the sensor to the reflector, the device is in the non-active state. When an object comes within the sensing distance, the propagation time changes and the sensor changes to the active state. This also allows detection of sound absorbent and sound deflecting objects.

     

    Setting Sde reflector distance

    The sensor's potentiometer allows the user to adjust the set up conditions for a specific reflector position (Sde). The output LED is also an adjustment aid as follows:

    1. Reflector in operating range

    If the setting of Sde deviates from the actual reflector position by less than ±2,5 %, the reflector is in the operating range. The LED lights steadily, the output is inactive.

    2. Reflector in the boundary range

    Up to a deviation of ±5 % the output remains inactive but the LED flashes. This indicates that the setting of Sde is not optimal and needs to be corrected.


    Retro-reflective sensor with Teach-in

    All adjustments are made using the single built-in Teach-in button.

    Teach-in of reflector’s position

    To enter the adjustment mode, push the Teach-in button for more than two seconds. You will know you have pushed it long enough by the indicating LED flashing green. When the button is released, the LED continues to flash. Any subsequent push of the button will teach the position of the reflector.

    Resetting to original factory settings

    Connecting the white Teach-in wire to +Vs for > 6 sec, will automatically restore the original factory settings. Fast flashing of the LED indicates successful completion of the resetting.


    Object detection

    • Standard object/reflector

    The standard target is defined as a square, level object with an edge length of 30 mm (Sde > 1000 mm: 100 mm edge length, Sde ≥ 2500 mm: 300 mm edge length) which is perpendicular to the sensor reference axis. The reflector must be made of a material with good sound reflection properties and be at least the same size as the target.

    • Object at close range

    For reliable detection, the sound cone must be covered completely so that no echo is returned from the reflector. The object diameter necessary for this is at least 30 mm in URDK 30 and at least 100 mm in URAM 50.

    • Object in the rest of the operating range

    To ensure reliable object detection, the reflected signal must be strong enough. The strength of the reflected signal is dependent on the size of the object. For a standard object, or larger, the full sensing distance Sd is available.


    Advantages

    • Easy detection even for 100 % sound absorbent materials
    • Reliable detection of sound deflecting objects
    • No blind region in front of the sensor for objects ≥ Standard object

Ultrasonic through beam sensors

  • Description

    The emitter and the receiver are in two separate housings. The continuous signal by the emitter is picked up by the receiver. An object interrupting the sonic beam will make the receiver react by giving an output signal. The user may adjust the amplification of the input signal where required. When an object interrupts the sonic beam, the receiver will react and give an output signal. With the help of the built in potentiometer, the user can adjust the amplification of the input signal, as necessary. The state of the output stage as well as the signal intensity are indicated by an LED.

     

    Hysteresis

    Hysteresis is the difference between the operating point (S1) and the release point (S2). If an object interrupts the sonic beam, the signal level must be increased by about 75 % in order to reset the output signal. Objects which follow one another in quick succession can therefore be easily detected.

    Sonic beam angle α

    The sonic beam angle α defines the boundaries of the emitted conical beam of the ultra sonic through beam sensor.

    Repeatability

    Due to the narrow angle of the sonic beam the repeatability of the switching point of two successive targets, under identical conditions, is better than 3 mm.

     

    Teach-in procedure

    All adjustments can be made with the internal Teach-in key.

    • Sensitivity Adjustment

    The LEDs on the display indicate the receiver’s sensitivity. The sensitivity can be called up at any time by pressing the Teach-in key, even with locked teaching functionality. Move the emitter and receiver to the desired position. Switch the emitter to its adjustment mode by pressing and holding the Teach-in key for approx. two seconds until the green LED begins flashing. Release the Teach-in key. The green LED now indicates the switching state. Press the Teach-in key repeatedly until the desired sensitivity is achieved and the green LED is continuously on. Sensitivity is indicated by the yellow LEDs on the display. To complete the Teach-in process, press and hold the Teach-in key for approx. two seconds until the green LED begins flashing rapidly. Release the Teach-in key. The LED is off!

    • Response Time

    Switch the sensor to teach mode by pressing and holding the Teach-in key for approx. four seconds until the red LED begins flashing. Release the Teach-in key. The red LED lights up continuously. Press the Teach-in key repeatedly until the desired response time is achieved.

    LED-Display:

    no LED on; approximately 5 ms response time delay
    1. LED on; approximately 10 ms response time delay
    2. LED on; approximately 20 ms response time delay
    3. LED on; approximately 40 ms response time delay
    4. LED on; approximately 80 ms response time delay
    5. LED on; approximately 160 ms response time delay
    6. LED on; approximately 320 ms response time delay

    To complete the Teach-in process, press and hold the Teach-in key for approx. two seconds until the red LED begins flashing rapidly. Release the Teach-in key. The response time is now set. 

     

    Resetting the receiver to its original factory settings

    Pressing and holding the Teach-in key for longer than six seconds will return the sensor to its factory settings. This is indicated on the receiver by the rapid flashing of the green/red LED.

     

    Teach-in lock

    The Teach-in function is locked five minutes after power up or five minutes after the end of the last Teach-in process.