Inflation and deflation pertain only to currency not products.

Inflation is when your currency buys you less stuff tomorrow than today. Deflation is when it buys you more. Falling prices due to efficiency gains caused some deflation during the industrial revolution, and technology making products cheaper is definitely a kind of deflation. From Wikipedia:

    Growth deflation: an enduring decrease in the real cost of
    goods and services as the result of technological progress,
    accompanied by competitive price cuts, resulting in an
    increase in aggregate demand.  A structural deflation existed
    from 1870s until the cycle upswing that started in 1895. The
    deflation was caused by the decrease in the production and
    distribution costs of goods. It resulted in competitive price
    cuts when markets were oversupplied. The mild inflation after
    1895 was attributed to the increase in gold supply that had
    been occurring for decades.