Note: Descriptions are shown in the official language in which they were submitted.
2128~53
Battery charger for cylindrical batteries
The present utility model relates to a battery charger
of the household type with built in mains transformer and
cord with a plug in connector which is capable of holding
and receiving a plurality of cylindrical batteries mainly of
the "AA" and "AAA", "C" and "D" types.
With increasing number of household electric and elect-
ronic appliances more and more battery cells are used. Re-
chargeable cells are often preferred to primary cells, since
they can be used through a large number of cycles, and they
are therefore substantially cheaper compared to the use of a
corresponding number of primary cells and constitute smaller
load to the environment as well. In a household where a plu-
rality of rechargeable cells is used, a battery charger is
also required.
Battery chargers are generally arranged in a plastic
housing provided with a compartment for the cells to be
charged, and the electrical components of the charger comp-
rise a mains transformer, a rectifier, one or more charging
circuits and preferably display means e.g. light emitting
diodes (LEDs) which give optical information on the status
of the charging process. Smaller battery chargers can be
plugged in the mains receptacle, while larger ones consti-
tute self supporting units connected to the line voltage by
means of a cord.
During the operation of the charger heat is generated,
and the design of the charger should provide appropriate
cooling so that the temperature of the electrical components
and of the cells must remain within acceptable limits.
Further requirements imposed on a battery charger are easy
handling, mechanical stability and pleasing appearance.
The primary object of the present utility model is to
provide a battery charger which can well meet all these re-
quirements.
This objective has been achieved by providing a battery
2128853
charger that comprises a substantially cylindrical housing
with respective bottom and upper parts separated by a pair
of opposing recesses. In operation the housing is arranged
in upright position, the recesses have planar rear faces
which extend in parallel with each other and with the axis
of symmetry of the housing. Spaced guiding ribs are provided
at upper and lower end zones of the faces to laterally guide
cells to be inserted, furthermore contact members are ar-
ranged at upper and lower end walls of the recesses between
the ribs to spring-bias the cells inserted. The bottom part
is capable of locating a mains transformer and slots are de-
fined in the housing to define an airflow cooling channel.
In a preferable embodiment the slots are provided at the
upper zone of the rear planar surfaces of the recesses and
at the bottom surface of the bottom part which comprises
short legs for keeping a distance between the slots at the
bottom surface and any support surface on which the battery
charger is standing.
It is preferable if the upper part has a pair of paral-
lel planar faces above the recesses and at least one of the
planar faces comprise display means indicating charge state
of cells charged.
The available space can be utilized in such a way that
one of the recesses serves as holder of cells only, i.e.
these cells cannot be charged but only stored.
In a still preferable embodiment at one end wall of the
recess spring-guiding slots are provided between the ribs,
and arched biasing springs that serve as contact members are
lead through the associated guiding slots.
It is preferable from the point of view of utilizing
available space and increasing stability if the bottom part
of the housing is formed to locate a toroidal transformer.
The battery charger will now be described in connection
with a preferable embodiment, in which reference will be
made to the accompanying drawings. In the drawing:
212X853
FIG. 1 is the perspective view of the battery charger;
FIG. 2 shows the battery charger in side view;
FIG. 3 shows the battery charger in elevation view; and
FIG. 4 shows the battery charger in top view.
The battery charger 10 has a substantially cylindrical
housing which stands in upright position on four short legs
11. Respective recesses 12, 13 are formed at two opposing
sides of the housing which have profiles best shown in FIG.
2. Each recess has a planar rear surface 14, 15. Short sepa-
ration ribs 16, 17 project from upper and lower end zones of
the planar surfaces spaced to guide insertion of cylindrical
AA size cells. Four cells can be inserted at each side of
the housing. The separation ribs 16, 17 have wedge-shaped
lateral surfaces narrowing in forward direction, and the
outer surfaces of the outermost ribs are constituted by the
cylindrical surface of the housing. The recesses 12, 13 have
narrow horizontal upper and lower walls 18, 19. The lower
walls 19 have small slots at locations that correspond to
the middle zones of the spacings defined between the ribs 17
and arched contact springs 20 extend through each slot. Flat
contact members 21 with slightly projecting spherical tips
are mounted on the upper walls 18 between the upper ribs 16.
The contact members 21 are arranged in respective recesses
which are only slightly wider than the tip representing the
positive pole of a cell, whereby there will be no contact
when a cell is inserted with incorrect polarity.
If a cell is inserted in a slot with correct polarity,
the two end contacts thereof will be spring biased between
the upper contact member 21 and the lower contact spring 20,
and the biasing force is provided by the fact that the cell
pushes the contact spring 20 in downward direction. The four
ribs ensures lateral support for the inserted cell.
Horizontal cooling slots 22 are provided at the upper
zones of the planar surfaces 12, 13 which together with
slots at the bottom of the housing (not shown in the draw-
ing) form inlets and outlets of an airflow cooling channel
2 i28853
defined in the housing. The legs 11 provide a spacing
between the slots at the bottom part and any support surface
on which the battery charger is standing, so that air can
freely flow therethrough.
The battery charger is capable of receiving and charging
eight AA cells. In embodiments designed for charging four
cells only, the recess for the other four cells can well be
used to store already charged cells. The recesses designed
for cell storage only are not provided with upper contacts
21 and the contact springs 21 serve as biasing members.
The housing has respective rectangular planar faces 23,
24 above the recesses 12, 13 in which, at the charger side,
light emitting diodes (LEDs) 25, 26 can be arranged which
indicate the charging state of the cells inserted. When the
left LED 25 lights, the charging process goes on, and when
the right LED 26 lights, the cells are fully charged.
The housing comprises respective inclined planar sur-
faces 27, 28 starting at the outer edges of the horizontal
walls 19, 20 which has no other specific function than of-
fering a more pleasing appearance.
The wide circular bottom portion of the housing spaced
from the support surface by the legs 11 locates the heaviest
and largest component of the battery charger, the mains
transformer, and such a form facilitates the use of a toro-
idal transformer. The transformer arranged in the lower part
of the housing increases mechanical stability and it is
thereby far away from other electronic components which can
well be located in the head portion above the recesses. The
heat and magnetic field of the transformer is well separated
from any sensitive component.
The housing offers several places for the arrangement of
labels and inscriptions. Favorable locations for this pur-
pose are the mantle surface 29 of the lower part of the
housing, the two planar faces 23, 24, the top surface 30 and
for warnings and other messages the planar rear surfaces 14,
15 of the recesses which will be visible when no cell is in-
serted.
