Help me with thermal head interface

[Abu Zafar]

thermal head signals

I found a thermal printing mechanism from junk. There is no marking on the thermal head. It is 57mm wide. The controller PCB (out of order) has following 14 pin connection designations at thermal head connector.

1. GND
2. TM
3. STB1
4. LAT
5. CLK
6. 24V
7. 24V
8. 24V
9. DI
10. STB4
11. STB3
12. 5V
13. GND
14. GND

I didn't interfaced a thermal head earlier and I want to make a thermal printer as a test. I have searched the internet for information but I didn't find enough technical information to answer all my queries. I have experience in hardware/software development using MCS51 controller.

I understood all the signals but I don't have their timing etc. I have following queries:

1. What are the active states/edges for data/clock/latch & strobe signals?
2. What should be the length of strobe signals?
3. Is thermistor signal digital or analog?
4. Is it necessary to provide 24V to thermal head when required? or we should switch it on whenever required?

I shall be greatly thankful if anyone kindly reply to my queries.

 

[eltonjohn]

strobe thermal head

Hi Abu ZAFAR ..

I have designed lots of printers in the past . Most of them are similar
The 24 volts are required .. It has to do with the dots resistance ..
So nothing to do there ,But the electronics shpuld be 5 volts ..

basically you shift in all the data for every one od the dots then you strobe it . To hold in memory .. The clock usually is less than 5 MHZ

then you strobe the number of dots that your power supply allows .

If it was a battery operated printer . you couldn't hit all the dota at the same time because it will require in excess of 10 amps ..so you hit first
odd dots then even .. while syncrhonizing with the mouvement of the motor..

Take a look at the seiko site they sell printers mechanisms thar are pretty much standard , That will give you an idea on the timings!

 

[silvio]

Re: Thermal head interface

Hi Abu Zafar,

Something it's telling me it's a KYOCERA type thermal print head. It must has some code printed in copper layer.
Take a look at https://global.kyocera.com/prdct/ios/tph/index_lineup.html and choose one with 5x mm width.

However don't be too excited. The printhead could easily get burned if not proper handled or driven in the circuit. Read this : **broken link removed**

You can find more about thermistor here:
https://global.kyocera.com/prdct/ios/tph/information02_e.html#18