In a cleaner, it is determined whether or not a remaining volume of a battery is equal to or more than a sum of a battery volume required for returning to a position of a battery charger and a predetermined allowance value. The device provides improved resolution of electron images from electron microscopes while not reducing the sensitivity of the apparatus. An acoustic radiation generator can be positioned in acoustic coupling relationship to each of the reservoirs. The charger for the remote control device is disposed with a charging plug which is adapted to engage with the charging socket of the remote control device and to charge the chargeable battery in the remote control device. Such change-over toothing permits the gear to roll, without jamming, from one of the toothed racks to the other one, with its axis following a trajectory having a salient point. The evaporation of the second layer causes the first layer to reflow and bind to the structure.