Piezoelectric digital print heads are the most stable and finest printheads in the world, and their internal structure is more precise than previous printheads. In order to do "high temperature protection", this type of nozzle will have a built-in thermistor for detecting the temperature of the print head.
Obviously, the temperature changes drastically caused by the external environment or long-term work will be instantaneously captured by the thermistor, and the temperature change causes the resistance voltage to change, and is converted into a digital signal to be transmitted to the CPU, thereby adjusting the printing progress.
When the thermistor in the digital print head senses a high temperature of 100℃, its voltage increases to 0.82 V. When it continues to rise, the inkjet operation will be suspended, but the car will still maintain the back and forth motion to accelerate the heat dissipation of the print head. Meanwhile, the "Online" indicator flashes. After a period of time, the temperature is down, and when it is lower than 90℃, it will come back to nomarl work.
The main reasons for the excessive temperature of the print head are as follows:
1. Long-time printing, if it is summer, "heat wave" and printhead’s own heat increase the difficulty of heat dissipation, in this case, the temperature will rise quickly to above 90 ℃;
2. The ribbon is stuck or the pinhole is blocked by grease, which often causes the load on the print head drive coil to increase, causing the nozzle to heat up;
3. The thermistor is damaged. The thermistor inside the digital printer nozzle is connected to the main board through a flat cable. The damage of the resistance wire will distort the transmitted signal, causing the CPU to mistake the print head temperature too high, thus slowing down the printing speed and even suspending.