  It is shown that all the known uncertainty relations are the secondary
consequences of Robertson's relation. The basic idea is to use the Heisenberg
picture so that the time development of quantum mechanical operators
incorporate the effects of the measurement interaction. A suitable use of
triangle inequalities then gives rise to various forms of uncertainty
relations. The assumptions of unbiased measurement and unbiased disturbance are
important to simplify the resulting uncertainty relations and to give the
familiar uncertainty relations such as a naive Heisenberg error-disturbance
relation. These simplified uncertainty relations are however valid only
conditionally. Quite independently of uncertainty relations, it is shown that
the notion of precise measurement is incompatible with the assumptions of
unbiased measurement and unbiased disturbance. We can thus naturally understand
the failure of the naive Heisenberg's error-disturbance relation, as was
demonstrated by the recent spin-measurement by J. Erhart, et al..
