SP262657
DESCRIPTION
TITLE OF INVENTION: BATTERY PACK AND METHOD OF MONITORING
REMOVAL OF SECONDARY BATTERY IN BATTERY PACK
TECHNICAL FIELD
[0001] The present invention relates to a battery pack, and to a method of
monitoring removal of a secondary battery in the battery pack.
BACKGROUND ART
[0002] A battery pack has been heretofore used for various portable apparatuses
such as a mobile phone, a digital still camera, a portable game machine, a notebook
personal computer, and an electric power tool. Currently, applications thereof are not
limited thereto, and the battery pack has been increasingly used in the fields
necessitating a higher output and a higher capacity such as an electric assist bicycle, an
electric vehicle, and a home electric storage device.
[0003] Examples of secondary batteries built into a battery pack include a lithium
ion secondary battery, which is currently one of the most-mainly-used secondary
batteries therefor. The lithium ion secondary battery has multiple characteristics as
follows. That is, the lithium ion secondary battery is repeatedly usable by charging,
has a high voltage output, has high energy density, has little self-discharge, and has a
long life. Therefore, the lithium ion secondary battery is used in an extremely-broad
range. However, since the lithium ion secondary contains a combustible material,
adequate care needs to be exercised in handling thereof. Further, for addressing needs
of apparatuses such as a higher output and a higher capacity, the number of cases in
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which secondary batteries (single ceils) are multiply-series-connected or
multiply-parallel-connected, and are used in a state of a battery pack (assembled
battery), and therefore, more proper handling thereof is desired. Furthermore, in order
to determine whether or not a battery pack mounted on an apparatus is safely usable for
the apparatus, many battery certification systems for acting certification between an
apparatus and a battery pack have been introduced. Accordingly, usage of an
inappropriate battery pack is allowed to be restricted by various certification methods
including whether or not an appropriate battery pack is used and whether or not an
appropriate protection circuit is included.
[0004] There is concern that what we call an altered battery pack is manufactured
and distributed by disassembling a spent battery pack, taking out a secondary battery,
and building the secondary battery into other battery pack. In such an altered battery
pack, undesired over-charge, undesired over-discharge, and/or the like may occur by
building in an inappropriate secondary battery, and therefore, a safety issue easily
occurs. Therefore, it is strongly desired to appropriately suppress manufacture and
distribution of the altered battery pack by disqualifying such an altered battery pack
from certification and/or substantially disabling a function of the altered battery pack.
[0005] As such a battery pack aimed at preventing alteration, a battery pack
provided with an IC tag in which predetermined information is recorded is known from,
for example, Japanese Unexamined Patent Application Publication No. 2006-324075.
Further, a battery pack in which a detachment recognition tape having a detachment
recognition function with which a fact that a battery has been separated from a package
case is certified is adhered to a region from the battery to a member adjacent thereto is
known from Japanese Unexamined Patent Application Publication No. 2005-353518.
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[Citation List]
[Patent Literature]
[0006] [PLT 1]: Japanese Unexamined Patent Application Publication No.
2006-324075
[PLT 2]: Japanese Unexamined Patent Application Publication No. 2005-353518
SUMMARY OF INVENTION
[0007] However, in the technology disclosed in Japanese Unexamined Patent
Application Publication No. 2006-324075, since the IC tag is used, there is a
disadvantage that the manufacturing cost of the battery pack is increased. In addition
thereto, in the case where the battery pack is disassembled so that the IC tag is not
broken, such technology becomes ineffective for preventing alternation. Further, in the
technology disclosed in Japanese Unexamined Patent Application Publication No.
2006-324075, it may be not possible to prevent taking a battery out of the battery pack
and manufacturing an altered battery pack.
[0008] Therefore, it is an object of the present invention to provide a battery pack
capable of preventing an altered battery pack from being manufactured by a simple
structure and a simple construction, and to a method of monitoring removal of a
secondary battery from the battery pack.
[0009] A battery pack of the present invention to achieve the foregoing object
includes a plurality of secondary batteries, a housing storing the plurality of secondary
batteries, and an inspection circuit stored in the housing. The housing includes a main
body section and a closing member to close an opening for taking the plurality of
secondary batteries in and out of the main body section, and includes a plurality of
fixing members for fixing the closing member on the main body section, the plurality of
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fixing members being made of a conductive material. An attachment state of the
fixing members with respect to the closing member and the main body section is
monitored by the inspection circuit, and an attachment order of the fixing members with
respect to the closing member and the main body section is memorized by the
inspection circuit.
[0010] A method of monitoring removal of a secondary battery in a battery pack of
the present invention to achieve the foregoing object (hereinafter simply referred to as
"monitoring method of the present invention" in some cases) is a method of monitoring
removal of a secondary battery in the foregoing battery pack of the present invention,
wherein when an order of removing the fixing members from the closing member and
the main body section is different from a removal order based on the attachment order, a
function of the battery pack is stopped.
[0011] In the battery pack of the present invention, the attachment state of the
fixing members with respect to the closing member and the main body section is
monitored by the inspection circuit, and the attachment order of the fixing members
with respect to the closing member and the main body section is memorized by the
inspection circuit. Therefore, when the order of removing the fixing members from
the closing member and the main body section is different from the removal order based
on the attachment order, the function of the battery pack is allowed to be stopped.
Further, in the monitoring method of the present invention, when the order of removing
the fixing members from the closing member and the main body section is different
from the removal order based on the attachment order, the function of the battery pack
is stopped. Therefore, although the battery pack has a simple structure and a simple
configuration, it is possible to prevent a secondary battery from being taken out
inappropriately. Consequently, alteration of a battery pack such as illegal replacement
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of a secondary battery is allowed to be securely prevented. Furthermore, an existing
secondary battery is allowed to be used.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] [FIG 1] FIG. 1 is a schematic view illustrating a state in which a closing
member of a battery pack according to a first embodiment is removed.
[FIG 2] FIGs. 2(A) and 2(B) are respectively a schematic perspective view of
the battery pack and a schematic view of a state in which the closing member of the
battery pack 1 according to the first embodiment is removed and a printed-wiring board
is further removed to expose secondary batteries.
[FIG. 3] FIGs. 3(A) and 3(B) are schematic and partial cross sectional views of
an enlarged main body section and an enlarged closing member configuring a housing.
DESCRIPTION OF EMBODIMENT
[0013] The present invention will be hereinafter described based on an embodiment
with reference to the drawings. However, the present invention is not limited to the
embodiment, and various numerical values and various materials in the embodiment are
merely exemplifications. It is to be noted that the description will be given in the
following order.
1. General Description of Battery Pack of Present Invention and Method of Monitoring
Removal of Secondary Battery of Present Invention
2. First Embodiment (Battery Pack of Present Invention and Method of Monitoring
Removal of Secondary Battery of Present Invention) and Others
[0014] [General Description of Battery Pack of Present Invention and Method of
Monitoring Removal of Secondary Battery of Present Invention]
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In the battery pack of the present invention, when the order of removing the
fixing members from the closing member and the main body section is different from
the removal order based on the attachment order memorized by the inspection circuit,
the function of the battery pack is allowed to be stopped.
[0015] In the battery pack of the present invention including the foregoing preferred
form and the monitoring method of the present invention, each of the fixing members
may be formed of a screw, specifically, may be formed of a screw made of a metal or an
alloy. However, the configuration thereof is not limited thereto, and as the fixing
members, a draw latch, a catch clip, a T-shaped zipper, and a cicada-shaped cover latch
may be exemplified.
[0016] In the battery pack of the present invention and the monitoring method of
the present invention including the foregoing preferred form and the foregoing preferred
configuration, a bush may be attached to a section of the main body section to which
each of the fixing members is attached, the bush being made of a conductive material,
specifically being made of a metal or an alloy, being connected to the inspection circuit
through a first wiring, and being engaged with each of the fixing members. The fixing
members attached to the closing member may be connected to the inspection circuit
through a second wiring.
[0017] Further, in the battery pack of the present invention and the monitoring
method of the present invention including the foregoing preferred form and the
foregoing preferred configuration, the battery pack may be given an identification (a
serial ID such as a barcode). The identification may have a predetermined relation
with the attachment order. Specifically, by analyzing (deciphering) the identification,
the attachment order may be ascertained.
[0018] Further, in the battery pack of the present invention and the monitoring
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method of the present invention including the foregoing preferred form and the
foregoing preferred configuration, the attachment order may be encrypted. It is to be
noted that encryption itself may be performed by a known method.
[0019] In the battery pack of the present invention and the monitoring method of
the present invention including the foregoing preferred form and the foregoing preferred
configuration (hereinafter simply and collectively referred to as "the present invention"
in some cases), examples of secondary batteries include a lithium ion secondary battery.
However, the secondary battery type is not limited thereto, and the secondary battery
type to be used may be selected as appropriate depending on desired characteristics.
The configuration and the structure of the secondary battery may be a known
configuration and a known structure. The shape of the secondary battery may be a
known cylindrical type and a known square type. The number of secondary batteries
configuring the battery pack may be determined as appropriate depending on desired
characteristics.
[0020] The main body section and the closing member configuring the housing may
be made of a non-conductive material (insulating material) such as a plastic material,
but the material thereof is not limited thereto. The main body section and the closing
member may be made of a metal or an alloy, as long as electric insulation with respect
to the fixing members and/or the like is allowed to be secured thereby. In the case
where the main body section is made of various plastic materials, the main body section
and the bush are allowed to be integrally formed. In the case where the closing
member is made of various plastic materials, the closing member and part of the second
wiring are allowed to be integrally formed. One of the first wiring and the second
wiring may be grounded. Although the shape of the main body section is substantially
arbitrary, a cube, a rectangular solid, a cylinder column, and a rectangular column may
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be exemplified. Examples of the position relation of the closing member with respect
to the main body section include a form in which an opening provided on the top
surface of the main body section is covered with the closing member, a form in which
an opening provided on a side surface of the main body section is covered with the
closing member, and a form in which an opening provided on the bottom surface of the
main body section is covered with the closing member.
[0021] The closing member may be fixed on the main body section only by the
plurality of fixing members. Alternatively, the main body section may be linked with
the closing member with the use of a hinge, and further the closing member may be
fixed on the main body section by the plurality of fixing members. The fixing
members may be made of a metal or an alloy. Although the number of the fixing
members is not limited, six or more may be exemplified as the number thereof.
[0022] The inspection circuit itself may be configured of a knovm circuit including
an MPU and a memory means (for example, configured of an EEPROM). An electric
source of the inspection circuit may be the secondary batteries configuring the battery
pack. The battery pack includes a battery protection circuit. To stop a function of the
battery pack, the battery protection circuit may be activated. Monitoring of attachment
state of the fixing members with respect to the closing member and the main body
section by the inspection circuit may be constantly performed, or may be performed at
predetermined time intervals.
[0023] In the fixing members with respect to the closing member and the main
body section, any of the following methods may be adopted, though not limited thereto:
(1) a method in which an attachment order of the fixing members is arbitrary (random),
and the attachment order of the fixing members is monitored and memorized by the
inspection circuit,
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(2) a method in which an attachment order of the fixing members is arbitrary (random),
and the attachment order of the fixing members is memorized in the inspection circuit
from outside,
(3) a method in which an attachment order of the fixing members is previously
determined, and the attachment .order of the fixing members is monitored and
memorized by the inspection circuit,
(4) a method in which an attachment order of the fixing members is previously
determined, and the attachment order of the fixing members is memorized in the
inspection circuit from outside, and
(5) a method in which an attachment order of the fixing members is previously
determined, and the attachment order of the fixing members is previously memorized in
the inspection circuit.
Further, the order of removing the fixing members from the closing member and the
main body section based on the attachment order may be inverted with respect to the
attachment order, or may be a removal order obtained based on a predetermined
arithmetic rule from the attachment order.
[0024] The battery pack in the present invention may be applied to, for example, an
electric vehicle (EV), an electric motorcycle, an electric assist bicycle, an electric power
tool, a home energy server (home electric storage device), a personal computer, a
mobile phone, a PDA, a digital still camera, a video camcoder, a camcoder, a music
player, a medical device, a toy, and the like.
First Embodiment
[0025] A first embodiment relates to the battery pack of the present invention and
the method of monitoring removal of a secondary battery 20 in a battery pack of the
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present invention. FIG 1 illustrates a schematic view showing a state in which a
closing member of a battery pack according to the first embodiment is removed.
Further, FIGs. 2(A) and 2(B) are respectively a schematic perspective view of the
battery pack and a schematic view of a state in which the closing member of the battery
pack 1 according to the first embodiment is removed and a printed-wiring board is
further removed to expose secondary batteries. Further, FIGs. 3(A) and 3(B) illustrate
schematic and partial cross sectional views of an enlarged main body section and an
enlarged closing member configuring a housing. FIG 3(A) illustrates a state before
the closing member is fixed on the main body section, and FIG 3(B) illustrates a state
after the closing member is fixed on the main body section by a fixing member.
[0026] A battery pack 10 of the first embodiment includes (A) a plurality of
secondary batteries 20, (B) a housing (a case) 30 storing therein the plurality of
secondary batteries 20, and (C) an inspection circuit (an inspection means or an
inspection apparatus) 70 stored in the housing 30.
[0027] The housing 30 includes a main body section 40 and a closing member 50 to
close an opening 44 for taking the plurality of secondary batteries 20 in and out of the
main body section 40. Further, the housing 30 includes a plurality of fixing members
60 made of a conductive material, for fixing the closing member 50 on the main body
section 40. An attachment state of the fixing members 60 with respect to the closing
member 50 and the main body section 40 is monitored by the inspection circuit 70.
Further, attachment order of the fixing members 60 with respect to the closing member
50 and the main body section 40 is memorized by the inspection circuit 70.
[0028] Further, a bush 42 that is made of a conductive material, specifically, a metal
or an alloy (more specifically, stainless steel), is connected to the inspection circuit 70
through a first wiring 41, and is engaged with the fixing member 60 is attached to a
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section of the main body section 40 to which each of the fixing members 60 is attached.
It is to be noted that the first wiring 41 is attached to the bush 42 by an appropriate
method. Further, the fixing members 60 attached to the closing member 50 are
connected to the inspection circuit 70 through second wirings 51 A, 5 IB, and 51C.
Specifically, the fixing members 60 are grounded through the second wirings 51 A, 5IB,
and 51C. A part of the second wiring 5 IB is provided with a through-hole 53 for the
passage of the fixing member 60. Further, the second wiring 51C connected to the
inspection circuit 70 through a connector 74 is electrically connected to the first wiring
51A through a fixing screw 52 made of stainless steel.
[0029] The secondary battery 20 is formed of a known cylindrical-type lithium ion
secondary battery. In the battery pack 10, three secondary batteries 20 are
parallel-connected by a metal connection plate 21, and seven secondary battery groups
each configured of such parallel-connected secondary batteries 20 are series-connected
by the metal connection plate 21. The main body section 40 and the closing member
50 configuring the housing 30 are made of a non-conductive material (insulating
material) such as a plastic material, and more specifically, are made of, for example, an
ABS resin, a PS resin, or a POM resin. Such a configuration is obtainable through
integral formation of the second wirings 51A and 5IB and the closing member 50.
Further, such a configuration is obtainable through integral formation of the bush 42 and
the main body section 40. Although the shape of the main body section 40 is
inherently arbitrary, the shape thereof is a rectangular solid in the first embodiment.
The closing member 50 seals the opening 44 provided on the top surface of the main
body section 40. The fixing member 60 is formed of a screw, specifically, is formed of
a screw made of a stainless steel. Incidentally, in the first embodiment, the closing
member 50 is fixed on the main body section 40 only by the eight fixing members
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(screws) 60. It is to be noted that a referential number 11 represents an identification
(a serial ID or a barcode) adhered to a side wall of the main body section 40, and a
referential number 12 represents an output section.
[0030] The inspection circuit 70 itself is configured of a known circuit including an
MPU 71 and a memory means (for example, configured of an EEPROM) 72. An
electric source of the inspection circuit 70 is the secondary batteries 20 configuring the
battery pack 10. The battery pack 10 includes a known battery protection circuit 73.
To stop a function of the battery pack 10, the battery protection circuit 73 is activated.
The MPU 71, the memory means 72, the battery protection circuit 73, and a connector
74 are attached to a printed-wiring board 75. Specifically, the battery protection circuit
73 is formed of a fuse. To stop the function of the battery pack 10, the battery
protection circuit 73 is activated. In other words, the fuse is melted and cut under
control of the MPU 71. Alternatively, a function of an over-discharge preventive
switch and/or a function of an over-charge preventive switch included in the battery
protection circuit 73 may be stopped. However, the configuration of the battery
protection circuit 73 is not limited to the foregoing configuration. It is to be noted that
although the battery pack 10 includes a known control circuit for controlling charge and
discharge of the secondary batteries, the control circuit is not illustrated.
[0031] In assembling the battery pack 10, first, the secondary batteries 20 that are
parallel-connected and series-connected by the metal connection plate 21 are contained
in the main body section 40. Next, thereover, the printed-wiring board 75 to which the
MPU 71 and the like are attached is attached to the main body section 40 by an
appropriate method (see the upper part of FIG. I). The main body section 40 is then
covered with a closing member (specifically, a cover) 60, and each of the fixing
members (screws) 60 is threadably mounted on the fixing section (the bush 42 provided
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with a tap section 43) provided in ttie main body section 40.
[0032] At this time, attachment order of the fixing members (screws) 60 is arbitrary
(random). The attachment order of the fixing members 60 is monitored by the
inspection circuit 70 (specifically, the MPU 71) operating based on a predetermined
program, and memorized in the memory means 72. Alternatively, the following
method may be adopted. In the method, the attachment order of the fixing members
(screws) 60 is arbitrary (random). The attachment order of the fixing members 60 is
memorized from outside (specifically, for example, through an unillustrated USB by
using a personal computer) into the memory means 72 included in the inspection circuit
70. Alternatively, the following methods may be adopted. In one method, the
attachment order of the fixing members 60 is previously determined. The attachment
order of the fixing member 60 is monitored by the inspection circuit 70 (specifically, the
MPU 71) operating based on a predetermined program, and memorized in the memory
means 72. In another method, the attachment order of the fixing members 60 is
previously determined. The attachment order of the fixing member 60 is memorized
from outside (specifically, for example, through an unillustrated USB by using a
personal computer) into the memory means 72 included in the inspection circuit 70. In
still another method, the attachment order of the fixing members 60 is previously
determined. The attachment order of the fixing members 60 is previously memorized
in the memory means 72 included in the inspection circuit 70. It is to be noted that
the attachment order may be encrypted based on a known method, and the resultant may
be memorized in the memory means 72.
[0033] In the battery pack 10 of the first embodiment and the monitoring method of
the first embodiment, in the case where removal order of the fixing members 60 from
the closing member 50 and the main body section 40 is different from removal order
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based on the attachment order memorized by the inspection circuit 70, the function of
the battery pack 10 is stopped.
[0034] Specifically, at the time of using the battery pack 10, the attachment state of
the fixing members 60 with respect to the closing member 50 and the main body section
40 is monitored by the inspection circuit 70. Such monitoring may be constantly
performed, or may be performed at predetermined time intervals, specifically, whether
or not a current flows between the first wiring 41 and the second wirings 51 A, 5IB, and
51C is examined. In the case where a current flows therebetween, it is allowed to be
determined that the fixing members 60 are attached to the closing member 50 and the
main body section 40.
[0035] In the case where the secondary battery 20 is to be taken out from the
battery pack 10, the fixing members 60 are removed from the closing member 50 and
the main body section 40. At this time, the inspection circuit 50 examines order of
removing the fixing members 60 from the closing member 50 and the main body
section 40, and memorizes the removal order. Specifically, in the case where the
fixing members 60 are removed from the closing member 50 and the main body section
40, a current stops flowing between the first wiring 41 and the second wirings 51A, 5 IB,
and 51C. Therefore, the inspection circuit 50 examines and memorizes order of stop
of current flow. Further, whether or not the finally obtained order of removing the
fixing members 60 from the closing member 50 and the main body section 40 is
different from the removal order based on the attachment order memorized by the
inspection circuit 70 is examined. Alternatively, whether or not the finally obtained
order of removing the fixing members 60 from the closing member 50 and the main
body section 40 is different from the removal order based on the attachment order
memorized by the inspection circuit 70 is examined every time when one of fixing
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members 60 is removed. If the finally obtained order of removing the fixing members
60 from the closing member 50 and the main body section 40 is different from the
removal order based on the attachment order memorized by the inspection circuit 70,
the function of the battery pack 10 is stopped. Accordingly, improper removal of the
secondary battery 20 is allowed to be prevented, and alteration of the battery pack 10
that is an attempt to illegally replace the secondary battery 20 is allowed to be securely
prevented.
[0036] The battery pack 10 is given the identification (a serial ID such as a barcode)
11. The identification 11 has a predetermined relation (unique relation) with
attachment order. In other words, by analyzing (deciphering) the identification 11, the
attachment order is ascertained. Therefore, in the case where replacement of the
secondary battery 20 in the battery pack 10, repair of the battery pack 10, and/or the like
is made by a manufacturer and/or the like, the fixing members 60 may be removed from
the closing member 50 and the main body section 40 according to removal order based
on attachment order obtained by analyzing (deciphering) the identification 11.
Alternatively, the following method may be adopted. In the method, a manufacturer
and/or the like records and archives attachment order, and informs the attachment order
to a repair section or the like according to an inquiry from the repair section or the like.
Alternatively, the following method may be adopted. In the method, an encrypted
attachment order is downloaded from the memory means 72 to a personal computer
through a USB, a decoding process is performed by the personal computer, and removal
order is displayed on a display.
[0037] The present invention has been described with reference to the preferred
embodiment. However, the present invention is not limited to the foregoing
embodiment. The configurations and the structures of the battery pack, the secondary
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battery, the housing, the inspection circuit, and/or the like are merely exemplifications,
and may be changed as appropriate. For example, in the embodiment, the
cylindrical-type secondary battery is used. However, the secondary battery may be
formed of a known square-type lithium ion secondary battery.
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CLAIMS
1. A battery pack comprising:
a plurality of secondary batteries;
a housing storing the plurality of secondary batteries; and
an inspection circuit stored in the housing, wherein
the housing includes a main body section and a closing member to close an
opening for taking the plurality of secondary batteries in and out of the main body
section, and includes a plurality of fixing members for fixing the closing member on the
main body section, the plurality of fixing members being made of a conductive material,
and
an attachment state of the fixing members with respect to the closing member
and the main body section is monitored by the inspection circuit, and an attachment
order of the fixing members with respect to the closing member and the main body
section is memorized by the inspection circuit.
2. The battery pack according to claim 1, wherein
when an order of removing the fixing members from the closing member and
the main body section is different from a removal order based on the attachment order
memorized by the inspection circuit, a function of the battery pack is stopped.
3. The battery pack according to claim 1, wherein each of the fixing members is
formed of a screw.
4. The battery pack according to claim 1, wherein
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a bush is attached to a section of the main body section to which each of the
fixing members is attached, the bush being made of a conductive material, being
connected to the inspection circuit through a first wiring, and being engaged with each
of the fixing members, and
the fixing members attached to the closing member are connected to the
inspection circuit through a second wiring.
5. The battery pack according to claim 1, wherein
the battery pack is given an identification, and
the identification has a predetermined relation with the attachment order.
6. The battery pack according to claim 1, wherein
the attachment order is encrypted.
7. A method of monitoring removal of a secondary battery in a battery pack, the
battery pack including
a plurality of secondary batteries,
a housing storing the plurality of secondary batteries, and
an inspection circuit stored in the housing,
the housing including a main body section and a closing member to close an
opening for taking the plurality of secondary batteries in and out of the main body
section, and including a plurality of fixing members for fixing the closing member on
the main body section, the plurality of fixing members being made of a conductive
material,
an attachment state of the fixing members with respect to the closing member
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and the main body section being monitored by the inspection circuit, and an attachment
order of the fixing members with respect to the closing member and the main body
section being memorized by the inspection circuit,
the method comprising: stopping a function of the battery pack when an order
of removing the fixing members from the closing member and the main body section is
different from a removal order based on the attachment order.
8. The method of monitoring removal of a secondary battery in a battery pack
according to claim 7, wherein each of the fixing members is formed of a screw.
9. The method of monitoring removal of a secondary battery in a battery pack
according to claim 7, wherein
a bush is attached to a section of the main body section to which each of the
fixing members is attached, the bush being made of a conductive material, being
connected to the inspection circuit through a first wiring, and being engaged with each
of the fixing members, and
the fixing members attached to the closing member are connected to the
inspection circuit through a second wiring.
10. The method of monitoring removal of a secondary battery in a battery pack
according to claim 7, wherein
the battery pack is given an identification, and
the identification has a predetermined relation with the attachment order.
it). The method of monitoring removal of a secondary battery in a battery pack
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according to claim 7, wherein
the attachment order is encrypted.