Hi
Welcome to the HP Support Community. I'd be happy to assist you with the print quality issue.
To better assist you -
1) Are you using genuine HP inks?
2) Are you experiencing this issue while making a copy as well?
Check the inks levels -
1) On the printer control panel, press the Home button to open the Home screen.
2) Press the Down Arrow to select Ink Levels, and then press OK. The control panel displays the estimated ink levels.
Replace if the ink is low.
Try these steps - HP Officejet 4630, Deskjet 4640 Printers - Fixing Poor Print Quality
Also, try updating the printer's firmware - HP Printers - Updating or Upgrading Printer Firmware
Hope this helps! Keep me posted.
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Have a great day!