The Doctor Blade is an important component of a laser printer's toner cartridge. It helps evenly distribute the toner powder on the photoconductor drum, ensuring a smooth print output. The model numbers you mentioned, 17A, 18A, and 30A, are associated with different toner cartridges used in various HP LaserJet printers, including the HP LaserJet Pro M102, M104, M130, and M132.

Here’s how they relate to each other:

1. HP 17A Toner Cartridge:

   • Compatible Printers: HP LaserJet Pro M102, M104, M130, M132.
   • Cartridge Number: CF217A.
   • This cartridge is typically used for monochrome printing, providing standard yields.

2. HP 18A Toner Cartridge:

   • Compatible Printers: This is another toner model that is compatible with the HP LaserJet Pro series, but it might be slightly different in terms of yield or cost compared to the 17A.
   • Cartridge Number: CF218A.
   • It can be used in printers like the HP LaserJet Pro M102, M104, M130, M132 as well, and generally offers a similar yield to the 17A, though it may vary.

3. HP 30A Toner Cartridge:

   • Compatible Printers: This is used in other HP LaserJet printers but not directly in the M102, M104, M130, M132. However, it’s often linked with other models in the same series for more advanced configurations.
   • Cartridge Number: CF230A.
   • It is part of a different toner family, offering a higher yield compared to 17A or 18A, typically used in slightly different HP printer models.

The Doctor Blade in these cartridges is essential for their proper functioning. It ensures that the toner is evenly spread over the drum surface to create high-quality text and images. If you're looking to replace or maintain the Doctor Blade in your toner cartridges for these models, you can typically do so by purchasing a new replacement toner cartridge, as these components are usually built into the cartridge design.

If you're experiencing print quality issues like streaking or uneven toner application, it could indicate that the Doctor Blade needs attention or replacement, and using a genuine toner cartridge is the best way to resolve such issues.