This patent seems to describe this cartridge. It expires in June 2018 in case there was ever any issue due to reading it.
HP 15 is a thermo cartridge. It has a matrix of nozzles, each consisting of a heat resistor. When current is allowed into a resistor, the resistor heats up, making some of the ink in its nozzle evaporate—as a gas the ink expands its volume, creating overpressure and ejecting a drop of the remaining liquid ink.
Now, the first ink cartridges had only a small number of nozzles (e.g., 14) and each resistor was connected to a contact pad. To keep the number of contact pads low while taking the number of nozzles one order of magnitude higher, cartridges organise nozzles in a matrix. A current needs to be applied to a ``column pad'' and a ``row pad'' to actually activate a nozzle.
Source: the patent above.
(Please note: what I call here ``pins'' are actually contact pads on the cartridge.)
| 47 | 49 | 51 | 52 | 50 | 48 | |
| 41 | 43 | 45 | 46 | 44 | 42 | |
| 35 | 37 | 39 | 40 | 38 | 36 | |
| 29 | 31 | 33 | 34 | 32 | 30 | |
| 25 | 27 | 28 | 26 | |||
| 21 | 23 | 24 | 22 | |||
| 17 | 19 | 20 | 18 | |||
| 13 | 15 | 16 | 14 | |||
| 9 | 11 | 12 | 10 | |||
| 5 | 7 | 8 | 6 | |||
| 1 | 3 | 4 | 2 |
| Pin | Code | Meaning |
|---|---|---|
| 1 | A9 | Address Select 9 |
| 2 | G6 | Common 6 |
| 3 | PS7 | Primitive Select 7 |
| 4 | PS6 | Primitive Select 6 |
| 5 | G7 | Common 7 |
| 6 | A11 | Address Select 11 |
| 7 | PS5 | Primitive Select 5 |
| 8 | A13 | Address Select 13 |
| 9 | G5 | Common 5 |
| 10 | G4 | Common 4 |
| 11 | G3 | Common 3 |
| 12 | PS4 | Primitive Select 4 |
| 13 | PS3 | Primitive Select 3 |
| 14 | A15 | Address Select 15 |
| 15 | A7 | Address Select 7 |
| 16 | A17 | Address Select 17 |
| 17 | A5 | Address Select 5 |
| 18 | G2 | Common 2 |
| 19 | G1 | Common 1 |
| 20 | PS2 | Primitive Select 2 |
| 21 | PS1 | Primitive Select 1 |
| 22 | A19 | Address Select 19 |
| 23 | A3 | Address Select 3 |
| 24 | A21 | Address Select 21 |
| 25 | A1 | Address Select 1 |
| 26 | A22 | Address Select 22 |
| 27 | TSR | Thermal Sense* |
| 28 | R10X | 10X Resistor* |
| 29 | A2 | Address Select 2 |
| 30 | A20 | Address Select 20 |
| 31 | A4 | Address Select 4 |
| 32 | PS14 | Primitive Select 14 |
| 33 | PS13 | Primitive Select 13 |
| 34 | G14 | Common 14 |
| 35 | G13 | Common 13 |
| 36 | A18 | Address Select 18 |
| 37 | A6 | Address Select 6 |
| 38 | A16 | Address Select 16 |
| 39 | A8 | Address Select 8 |
| 40 | PS12 | Primitive Select 12 |
| 41 | PS11 | Primitive Select 11 |
| 42 | G12 | Common 12 |
| 43 | G11 | Common 11 |
| 44 | G10 | Common 10 |
| 45 | A10 | Address Select 10 |
| 46 | PS10 | Primitive Select 10 |
| 47 | A12 | Address Select 12 |
| 48 | G8 | Common 8 |
| 49 | PS9 | Primitive Select 9 |
| 50 | PS8 | Primitive Select 8 |
| 51 | G9 | Common 9 |
| 52 | A14 | Address Select 14 |
*) I suppose these two pins take care of the ink temperature (both measuring and heating), but I have not found any (patent-) documentation to back this up. What I have found out, on the other hand, is that the HP printer is very sensitive to any outer interference on them. For instance it may think that the ink is not yet heated to the target temperature so it waits and waits and waits… and prints each pass of the printing head with long intervals as a result.
Note: not every combination of an address select and a primitive select is connected to a nozzle. I actually don’t know yet, but I’ve read elsewhere that there still might be resistors present – those would be used for maintaining ink temperature. But that was a general idea on thermal cartridges, not HP 15-specific information. Another theory is that they can be used to encode cartridge identification bits. (To do: investigate this.)
To do: manually transcribe it here from the PDF.
To do: create a schema of the measurement circuit and type up my notes here.
Last updated: 2018-03-03