Sony has sold 6.4 million PlayStation 4 consoles during Q3 2014, a period that encompasses October 1st through December 31st, 2014, the company revealed in a financial results briefing this week.

The PS4 accounted for the majority of Sony's 7.5 million console sales last quarter. The company cited the increase in PS4 hardware unit sales as having a positive financial impact, while a decrease in PlayStation 3 hardware and software sales had a negative impact.

In the same quarter of the prior year, 2013, Sony sold 4.5 million units of its latest console. The PS4 was released during that quarter, in November 2013. As of January 2015, Sony said PS4 sales reached 18.5 million worldwide.

Sales in Sony's Game & Network Services Segment, where its PlayStation business lives, increased 16.8 percent year-over-year to 531.5 billion yen ($4.3 billion). According to Sony, the increase "was primarily due to an increase in PS4 hardware unit sales, the favourable impact of foreign exchange rates and a significant increase in network services revenue, partially offset by a decrease in PlayStation 3 ('PS3') hardware and PS3 software sales."

The same slide that revealed console sales also showed that the segment's operating income increased by 15.2 billion yen to 27.6 billion yen ($228 million). Previously mentioned in last year's Q3 statement, Sony recorded a 6.2 billion yen write-off for "certain PC software titles of Sony Online Entertainment LLC in Q3 FY13," a move the company now cites has having a positive impact. The slide also revealed an 11.2 billion yen ($93 million) "write-down of PS Vita and PS TV components."