Patent ID: 7242278

Claim:
A portable transmitter comprising: a transponder that transmits an ID code to operate a device; a battery that supplies electric power to the transponder; an electronic circuit board connected to the transponder; and a case that contains the transponder, the battery and the electric circuit board therein, and the case includes a front case member and a rear case member, wherein: the front and rear case members are firmly engaged with each other such that the front case member cannot be separated from the rear case member without breaking the case; the front case member includes a front hook having a first engaging surface that extends in a longitudinal direction of the case; the rear case member includes a rear hook having a second engaging surface that extends in a longitudinal direction of the case; the first and second engaging surfaces closely contact each other; the rear case member includes a separating wall and an opening that allows the battery to be loaded or unloaded; and the transponder is completely confined in a space separated by the electronic circuit board and the separating wall.