Label Positioning | Label Detection | Label Sensor Detection Principles

With the rise of industrial automation and higher automation requirements, label applicators must move from manual or semi-automatic labeling to fully automatic high-speed labeling. Market surveys show many label machine manufacturers face challenges such as difficulty detecting special labels, label accuracy and speed.

The key to solving these issues is the label sensor. Sensors serve as the "eyes" of automated labeling systems. Due to varying production processes and complex label formats, modern labels place higher demands on label sensors in terms of accuracy and speed, which in turn challenge sensor and servo positioning performance. Different detection principles have led to a variety of sensor types. Commonly, slot-type housing sensors are widely used. According to detection principle, label sensors can be divided into photoelectric, bipolar capacitive, single-electrode capacitive, and ultrasonic types.

Photoelectric label sensors: built with a slotted sensor housing, an LED light modulator, a light receiver, demodulator, a PIC controller and output circuitry. When the gap between labels passes through the slot and transmittance exceeds a set threshold, a switching output is generated to control the host. Atonm photoelectric label sensors have fast response suitable for standard paper label detection. Representative product: LS1-NM12C All-Metal Label Sensor.

Atonm All-Metal Label Sensor LS1 series advantages:

(1) A 3 mm slot width and 60 mm sensing length provide precise label detection on the machine

(2) High switching frequency and very short response time ensure excellent repeatability

(3) Long slot design makes it easy to place labels at the slot edge for direct detection

(4) Adaptive logic circuitry (auto level control): automatically optimizes switching thresholds for best performance

(5) Warning output, calibration display and error indicators

(6) Simple adjustment via calibration button or calibrated outputs

2. Bipolar capacitive label sensors: consist of a slotted housing, dual detection electrodes, an ADC chip and a PIC controller to form a differential capacitive detection circuit. The differential design cancels capacitance changes caused by distance variation between label and electrode.

3. Single-electrode capacitive label sensors: consist of a slotted housing, a single detection electrode, ADC and PIC chips to form a capacitance detection circuit. Collected signals are amplified, compared and output as a switching signal. Capacitive detection provides stable results and is suitable for high-speed label detection.

4. Ultrasonic label sensors: built with a slotted housing, ultrasonic transducers, a driver and a PIC controller to form a through-beam detection system. Outputs switch based on a threshold. Acoustic detection requires some time and is suitable for medium-speed label applicators.

When a label reaches the label sensor, it sends an electrical signal to the label applicator controller or PLC, confirming label position and preparing the drive for the next labeling event. Choose the sensor type according to label material, but Atonm label sensors can detect standard and transparent labels without replacement.