What Is the Exact Invention Date of the PSP?

There is no single "invention date" for the PlayStation Portable. Hardware development is a multi-year process with several key milestones:

• Conceptualization: The idea emerged years before any public announcement.
• Prototype Development: Early engineering prototypes were created well in advance of reveal.
• Public Announcement: May 11, 2004 at E3 (Sony's press conference).
• Release Dates: Japan – December 12, 2004; North America – March 24, 2005; PAL regions – September 1, 2005.

It's more accurate to say the PSP was developed over several years rather than invented on a specific day.