Abstract: A method for recording and erasing a visible image on a card having a recording area with a smooth surface of a synthetic resin, which includes a step of subjecting the smooth surface in the recording area to frosting treatment at a temperature within a range of from the glass transition temperature to the melting point of the synthetic resin, to form a frosted surface having a strain, and step of defrosting the frosted surface by heating it at a temperature higher than the temperature for the frosting treatment, to return it to a smooth surface, whereby a visible image is formed in the recording area by the contrast between the frosted surface and the smooth surface.

Abstract: A battery pack containing a rechargeable battery is detachable to a charger unit for charging under the control of a charging circuit in the charger unit. The battery pack includes a sensor output circuit which comprises a temperature sensor for sensing the temperature of the battery being charged. A voltage dividing resistor network is formed in the sensor output circuit and receives a constant current from the charging circuit upon attachment of the battery pack to the charger unit such that it provides an enable signal of a first voltage level to the charging circuit for allowing the charging of the battery at a first charge rate so long as the sensed battery temperature is below a predetermined reference level. When the sensed battery temperature exceeds the reference level, the voltage dividing resistor network responds to provide a stop signal of a second voltage level for inhibiting the charging at the first charge rate.

Abstract: A reduced thickness trimmer unit for electric shavers is mounted within and partly on a head casing. The unit has a frame, a stationary cutter on one end and a movable cutter which cooperates with the stationary cutter. The frame contains a resilient leg which extends interiorly thereof and within the plane thereof so as to resiliently support at its free end a coupling element for connection with the movable cutter. The coupling element engages with an eccentric cam carried on the driving shaft of the motor so that it is driven by the driving shaft to reciprocate relative to the frame within the plane of the frame as the resilient leg limits the coupling element to move in the reciprocating direction within the plane of the frame. The resilient leg and the coupling element combine to convert rotary motion of the driving shaft into reciprocatory motion of the movable cutter in the trimmer unit and are received within the thickness of the frame.

Abstract: Chargeable electric instrument of watertight housing capable of still discharging abnormally generated gas or liquid from built-in storage battery. The instrument includes a gas discharging valve means provided at an open end of a storage-battery casing, a cap means fixed to the casing for liquid-tightly enclosing the open end and valve means, a charge current feeding means provided in an end part of the housing, and a gas or liquid flow-path means made through the cap means and housing while preventing an entry of any fluid from the exterior, whereby any explosive gas internally generated can be effectively discharged through the valve, cap and flow-path means to the exterior.

Abstract: An electric shaver incorporating an elastomeric, unitary, diaphragm suction pump driven from an eccentric off the cutting blade driving motor. A channel is formed about the cutting head in communication with the suction pump. During shaving, the suction pump creates a partial vacuum in the channel about the cutting head whereby the skin is drawn into the channel and, thereby, stretched across and against the cutting head. Axial sliding of the cutting head and/or a collar surrounding the channel can be employed in addition to provide self-adjustability.