Top 10 Photoelectric Sensor Problems in TIJ Inkjet Printers and How to Fix Them

Problem The transmitter, receiver, or reflector position is incorrect, causing unstable detection.

Symptoms

• Product passes but no printing occurs
• Trigger signal is unstable
• Printer works manually but fails during automatic production

Solution: Adjust the optical path and confirm the product passes through the correct detection area. If the issue remains, contact the manufacturer to confirm sensor compatibility.

Problem Dust, water vapor, and ink mist reduce sensor detection accuracy.

Symptoms

• Sometimes printing works, sometimes it stops
• Random missing codes
• More failures during long production runs

Solution: Clean the sensor lens regularly and avoid installing the sensor close to contamination sources.

Problem The product is outside the effective detection distance.

Symptoms

• Some products trigger successfully while others do not
• Detection changes when product position moves slightly

Solution: Perform Photoelectric Sensor Adjustment by setting the correct distance between the sensor and the product.

Problem The distance between sensor and printhead creates incorrect printing timing.

Symptoms

• Date code prints too far forward
• Date code prints too far backward
• Printing position changes with different conveyor speeds

Solution: Adjust trigger delay according to conveyor speed and installation distance.

Problem Too high sensitivity may cause false triggering. Too low sensitivity may cause missed detection.

Symptoms

Sensitivity too high:

• Empty printing without products
• Continuous spraying caused by reflections

Sensitivity too low:

• Products are not detected
• Missing codes occur

Solution: Adjust sensitivity according to product material and factory environment.

Problem Highly reflective materials such as glossy plastic bottles, metal containers, and transparent packaging can confuse photoelectric sensors. Strong factory lighting may also interfere with detection.

Symptoms

• Printer triggers without products
• Products pass but are not detected

Solution: Changing sensor installation angle, Blocking direct light interference, Selecting a sensor suitable for reflective materials.
If the problem continues, the sensor type may need to be reviewed with the equipment supplier.

Problem Production line vibration can create unstable sensor signals.
If filtering time is too short, the system may detect multiple triggers. If filtering time is too long, fast-moving products may be missed.

Symptoms

• Double printing
• Overlapping codes
• Missing prints at high speed

Solution: Optimize Trigger filter time, Anti-jitter settings, Minimum trigger interval. Test the settings under actual production conditions.

Problem When products are placed too closely together, the sensor may continuously detect them as one object. This is common in high-speed bottle or carton production lines.

Symptoms

• Two products receive only one code
• Continuous printing occurs

Solution: Increasing product spacing, Adjusting minimum trigger intervals, Improving product positioning on the conveyor.

Problem Unstable power supply or electromagnetic interference can interrupt sensor signals. Common causes: Long sensor cables, Sensor cables installed near motor power lines, Voltage instability.

Symptoms

• Works normally at low speed
• Random missing codes at higher production speeds

Solution: Check: Power supply stability, Cable connections, Signal cable routing. If electrical interference cannot be eliminated, professional technical support may be required.

ProblemNot every photoelectric sensor can directly work with every Tij Printer system. Differences may include:NPN or PNP output, Normally open or normally closed signal, Different voltage requirements.

Symptoms

• Sensor indicator works normally
• Printer receives no trigger signal

Solution: Confirm the sensor specifications before replacement.
Check: Output type, Voltage requirements, Wiring definition. If unsure, contact the printer supplier to avoid incorrect connection.

Besides the Top 10 problems above, manufacturers may also experience:

Loose Sensor Wiring or Cable Damage

Vibration from production lines can loosen connectors or damage cables.

Solution: Check connectors, Secure wiring, Replace damaged cables if necessary.

Unstable Product Position

If products move randomly on the conveyor, the sensor may not detect them consistently.

Solution: Add product guides, Improve conveyor positioning.