Battery discriminating system for charging a battery of a mobile terminal

The present invention relates to a battery discrimination system which provides for charging a battery of a mobile terminal where the battery may be any one of a plurality of types of batteries each having different charge characteristics. The system includes a mobile terminal, the mobile terminal including a battery pack housing for storing at least one of a plurality of batteries. The plurality of batteries including batteries of a first battery type and batteries of a second battery type, the batteries of the first battery type having charge characteristics different from the batteries of the second battery type. The system further includes a docking cradle for receiving and storing the mobile terminal. The cradle includes a battery charger for charging the at least one of a plurality of batteries. The battery charger includes a battery discriminator for identifying whether the at least one of a plurality of batteries is of the first battery type or of the second battery type, wherein the battery charger charges the one of a plurality of batteries in accordance with the identification of the battery type determined by the battery discriminator.

TECHNICAL FIELD 
The present invention relates to a battery discrimination system, device 
and method for mobile units. 
BACKGROUND OF THE INVENTION 
In recent years, the use of wireless mobile terminals has become 
increasingly popular to help automate and expedite processes in retail, 
manufacturing, warehousing and other industries. For instance, in a retail 
environment the wireless mobile terminal may take the form of a wireless 
bar code reading device for use in tracking inventory and checking prices. 
In the warehousing industry, the same device may be used to keep accurate 
accounts of incoming and outgoing shipments. In the healthcare, 
transportation and other industries, the mobile terminal may take the form 
of a wireless pen based computer to aid in on-site document control 
procedures. The mobile terminals may operate independently by storing all 
information until later downloaded or may include a radio which allows it 
to communicate in real time to a host computer connected to a LAN, for 
example. 
In order to allow for wireless operations of each mobile terminal, an 
independent power source or battery is provided within each. The batteries 
will typically provide the mobile terminal with several hours of operation 
before needing recharging. Once a battery is drained, however, it must be 
connected to a recharging unit in order to re-obtain its full power 
capacity. Recharging units or stations which are typically configured to 
hold a mobile terminal are known as a cradle. Cradles today come in 
varying degrees of sophistication. A basic function of many cradles is to 
provide some sort of interface with the mobile terminal through which 
information stored in the mobile terminal can be downloaded to a central 
computer or other device. Another main purpose of a basic cradle is to 
supply recharging power to a battery pack attached to the mobile terminal 
so that the batteries can be fully recharged. As battery packs can be 
composed of a variety of different battery types, the cradle must be 
pre-set to supply recharge current at a level appropriate for the battery 
type expected. Typical battery types used today include Nickel-Cadmium 
(Ni--Cd), Lithium-Ion (Li--Ion), Nickel-Metal-Hydride (Ni--MH), etc. The 
benefit of using one type of battery over the other varies with the 
application at hand. For example, Ni--Cd cells are preferred in 
applications requiring relatively high discharge rates. Chargers are 
presently available to charge Ni--Cd batteries, however, Ni--Cd batteries 
are toxic and their use is being restricted by law. Ni--MH are often 
selected where capacity per unit weight or volume, rather than peak power 
or safety disposal are critical. These cells can also be charged by 
presently available battery chargers. Li--Ion batteries generally have a 
capacity equivalent to at least an Ni--MH batteries, but have significant 
reduction in weight. 
Although electronic devices such as portable terminals can use different 
types of batteries (i.e., Ni--Cd, Ni--MH, Li--Ion, etc.) these batteries 
have charge characteristics greatly different from each other. Thus, one 
battery charger (i.e., a cradle) generally cannot charge more than one 
type of battery. Furthermore, if one of the batteries is charged according 
to the charge conditions for another type battery, the battery may be 
damaged or even explode, and could cause damage to the portable terminal. 
Therefore, what is needed is a method and apparatus for allowing mobile 
terminals which use interchangeable battery types to be charged by a 
single cradle which can sense the battery type and charge the battery 
according to its specific charging characteristics. 
SUMMARY OF THE INVENTION 
The present invention relates to a battery discrimination system which 
provides for charging a battery of a mobile unit where the battery may be 
any one of a plurality of types of batteries each having different charge 
characteristics. The battery discrimination system is particularly useful 
in that is can be easily applied to existing mobile units to provide for 
universal charging of mobile units that may use batteries from among a 
plurality of types having different charge characteristics. Hence, the 
present invention affords for increased versatility in the use of various 
types of batteries in a mobile unit since one battery charger may be 
employed to charge the various types of batteries that may be used, 
respectively, by the mobile unit. 
More particularly, the present invention introduces a mobile terminal 
circuit which provides for varying degrees of voltage levels in accordance 
with the type of battery currently being used by the mobile terminal and 
the status (i.e., docked, undocked, on or off) of the mobile terminal. The 
voltage levels are varied on an output status line going to a cradle 
receiving the mobile terminal. Based on the degree of voltage level on the 
status line, the cradle can determine the type of battery (e.g., Li--Ion, 
Ni--Cd, etc.) in the PTC as well as the status of the mobile terminal. The 
cradle can then deliver an appropriate amount of power to the mobile 
terminal so that it may operate and also charge the battery in accordance 
with the particular charging characteristics of that battery. 
In accordance with one particular aspect of the invention, a battery 
charging system is provided, including: a mobile terminal, the mobile 
terminal including a battery pack housing for storing at least one of a 
plurality of batteries; the plurality of batteries including batteries of 
a first battery type and batteries of a second battery type, the batteries 
of the first battery type having charge characteristics different from the 
batteries of the second battery type; and a docking cradle for receiving 
and storing the mobile terminal, the cradle including a battery charger 
for charging the at least one of a plurality of batteries, the battery 
charger including a battery discriminator for identifying whether the at 
least one of a plurality of batteries is of the first battery type or of 
the second battery type, wherein the battery charger charges the one of a 
plurality of batteries in accordance with the identification of the 
battery type determined by the battery discriminator. 
According to another aspect of the invention, a docking cradle for a mobile 
terminal is provided, including: a housing, the housing being adapted to 
receive and store the mobile terminal; a battery charger for charging at 
least one battery of the mobile terminal; and a battery discriminator for 
discriminating whether the at least one battery is of a first battery type 
or of a second battery type, the first battery type having charge 
characteristics different from the second battery type; wherein the 
battery charger charges the at least one battery in accordance with the 
battery type of the at least one battery determined by the battery 
discriminator. 
In accordance with still another aspect of the invention, a method for 
charging a mobile terminal is provided, including the steps of: coupling 
the mobile terminal to a battery charger, the battery charger being 
adapted to charge at least one battery of the mobile terminal, the at 
least one battery being any one of a plurality of battery types having 
different charge characteristics, the at least one battery being housed in 
a battery pack, the battery pack being any one of a plurality of types of 
battery packs corresponding to the plurality of battery types; using the 
battery charger to discriminate the type of the at least one battery from 
the plurality of battery types, wherein the battery charger discriminates 
the type of the at least one battery based on a signal received from the 
mobile terminal, the signal being representative of the type of the at 
least one battery; and charging the at least one battery according to the 
thus determined type of the at least one battery. 
According to yet another aspect of the invention, a method of determining a 
charge current to supply a mobile terminal is provided, including the 
steps of: receiving the mobile terminal by a cradle, the mobile terminal 
including a rechargeable battery; providing a signal on a status contact 
associated with the mobile terminal indicative of a type of rechargeable 
battery included in the mobile terminal; sensing the signal on the status 
contact of the mobile terminal with a battery discriminator of the cradle; 
and providing from the cradle an appropriate charge current to the 
rechargeable battery based on the signal sensed on the status contact. 
In accordance with another aspect of the invention, a mobile terminal is 
provided, including: a housing shaped to be received by a cradle; a 
rechargeable battery; battery charging status circuitry disposed in the 
housing and interfacing with the rechargeable battery; the status 
circuitry providing an output signal to be sensed by circuitry associated 
with the docking cradle when the mobile terminal is received in the 
docking cradle, the output signal being of a first signal level if the 
rechargeable battery is of a first battery type and a second signal level 
if the rechargeable battery is of a second battery type. 
To the accomplishment of the foregoing and related ends, the invention, 
then, comprises the features hereinafter described and particularly 
pointed out in the claims. The following description and the annexed 
drawings set forth in detail certain illustrative embodiments of the 
invention. These embodiments are indicative, however, of but a few of the 
various ways in which the principles of the invention may be employed. 
Other objects, advantages and novel features of the invention will become 
apparent from the following detailed description of the invention when 
considered in conjunction with the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The present invention will now be described with reference to the drawings, 
wherein like reference numerals are used to refer to like elements 
throughout. 
Referring initially to FIGS. 1A and 1B there is shown pictorial 
representations of front and back views, respectively, of a portable 
electronic device in accordance with the present invention and is 
generally designated 10. In the exemplary embodiment, the portable device 
is a mobile terminal 10 used in a wireless communication network for 
tracking inventory, storing data, etc. The user may input and/or process 
data via a keypad, bar code scanner, etc. independent of the mobile 
terminal 10 being connected to a LAN, for example. When the mobile 
terminal 10 does not include a radio to provide for real time 
communications of data to a LAN, the data is stored in memory within the 
mobile terminal 10. In such circumstances, when the mobile terminal 10 is 
eventually connected to a LAN, the data can be transmitted to a host 
computer (not shown). It will be appreciated that the portable device 
could also be any other device that is portable in nature and having 
electronic circuitry therein in accordance with the present invention. For 
example, the portable device could be a laptop computer or notebook 
computer, a PDA, or even a cellular telephone or pager, which employs 
rechargeable batteries. 
In this particular embodiment, the mobile terminal 10 includes a housing 
16, a display 20 for displaying information to a user, a set of user 
interface keys 24 for allowing the user to input information and/or 
operational commands and a bar code scanner 26. The described components 
20, 24 and 26 are located in the housing 16 which is an elongated 
enclosure of a size and including such contours as to conveniently fit 
into the open palm of the user. The housing 16 may be comprised of a 
number of shell portions such as for example front and rear shells 30 and 
32 as well as a battery pack lid 34. The user interface keys 24 may 
include a full alpha-numeric keypad, function keys, enter keys, etc. The 
mobile terminal 10 also includes a window through which a bar code reader 
26 is able to read a bar code label presented to the mobile terminal 10. 
Also included in the mobile terminal 10 is an ON/OFF power switch 40 for 
turning the device on and off. Furthermore, the mobile terminal 10 
includes status lights 42 for indicating to the user such things as 
operation of a memory hard drive, low battery power, low power 
consumption, etc. The mobile terminal 10 also includes an antenna 50 which 
allows the mobile terminal 10 to transmit and receive data via an RF link 
to a network backbone such as a LAN (not shown). 
The mobile terminal 10 further includes three electrical contacts 60, 62 
and 64 exposed at the back side of the housing 16. Contacts 60 and 62 are 
employed to provide power from an external source (i.e., a cradle) to the 
mobile terminal and status contact 64 is used to provide a status signal 
to the external power source so that the status (i.e., docked, undocked, 
on or off) of the mobile terminal 10 can be determined. Furthermore, the 
status signal provided via status contact 64 affords for determining the 
type of battery being used by the mobile terminal 10 so that the battery 
can be charged according to its particular charge characteristics. 
Referring now to FIG. 1C, the mobile terminal 10 also includes a set of 
four electrical contacts 65. The four electrical contacts 65 are used for 
communications between the electronic circuitry within the portable 
terminal 10 and a LAN system backbone (not shown). Preferably, all the 
contacts 60, 62 and 64 and 65 are made of a highly conductive metal that 
is resistant to corrosion such as for example Nickel Plated Beryllium 
Copper. 
Turning back to FIGS. 1A and 1B, a battery pack 66 is located on the back 
side of the mobile terminal 10. The battery pack 66 is dimensioned to 
receive and hold rechargeable batteries which in series combination 
provide a total nominal voltage of about 7.2 volts. This voltage 
corresponds to the preferred supply voltage of the mobile terminal 10. The 
battery pack 66 is adapted to be easily removable and installable. 
Accordingly, the user can carry a spare battery pack preloaded with 
batteries to replace a battery pack with dead batteries. The battery pack 
66 is designed to prevent being inserted in the mobile terminal 10 in the 
wrong direction so as to avoid possible damage to the mobile terminal 10. 
FIG. 2 illustrates a cradle 90 for use in conjunction with the mobile 
terminal 10. The cradle 90 includes side walls 94 and 96 extending 
vertically from a base member 100. The side walls 94 and 96 are spaced 
apart by a distance D which is slightly longer that a width W of the 
mobile terminal 10. Accordingly, the cradle 90 is adapted to receive and 
store the mobile terminal 10 as a result of the mobile terminal 10 being 
turned on its back and slid into recess 104 of the cradle 90. 
The base member 100 includes a contacts 110, 112 and 114 designed to 
correspond to the contacts 60, 62 and 64, respectively, located at the 
back side of the mobile terminal 10. The cradle 90 determines the status 
of the mobile terminal 10 and the battery type being used via the status 
signal received from the mobile terminal 10 via contacts 64 and 114. The 
cradle 90 supplies power (including battery recharging power) to the 
mobile terminal 10 via contacts 110, 112 and corresponding contacts 60, 
62. The cradle 90 also includes a set of four electrical contacts 118 
which correspond to the set of contacts 65 of the mobile terminal 10. The 
contacts 118 of the cradle are positioned so as to align with the contacts 
65 of the mobile terminal 10 when the mobile terminal 10 is received by or 
"docked" in the cradle 90. The contacts 118 and 65 are used, for example, 
for communications between the cradle 90 and the mobile terminal 10. 
Accordingly, when the mobile terminal 10 is docked to the cradle 90, the 
mobile terminal 10 can connect to the LAN, for example, via the cradle 90. 
In addition, each of the contacts 60, 62, 64, 65, 110, 112, 114 and 11 8 
are preferably spring loaded to urge the contacts into secure physical and 
electrical contact with the corresponding contacts. The weight of the 
portable terminal 10 standing on its back helps to further ensure 
satisfactory contact between the contacts 60, 62, 64 and 110, 112, 114, 
respectively. It is to be understood that any type of contact suitable for 
carrying out the present invention could be used without departing from 
the scope of the invention. Such contacts may be of the type which also 
provide a mechanical type connection as well as an electrical connection 
as will be appreciated. 
The cradle 90 also includes a LAN connector 120 attached to an exterior of 
side wall 96. According to the preferred embodiment, the LAN system 
backbone to which the connector 120 is coupled is either an Ethernet or 
Token Ring configuration, and permits communications according to 
corresponding protocols. However, it will be appreciated that the scope of 
the present invention is intended to include any suitable system backbone. 
The cradle 90 further includes a power supply apparatus 124, the apparatus 
124 includes a power converter 126 for providing power to the cradle 90 
via a cord 128. The apparatus 124 receives power via a conventional power 
cord 130 which plugs into a standard 110 VAC outlet, for example. The AC 
power which is provided to the cradle 90 via the power cord 130 is input 
to the converter 126 which converts the AC power received via the power 
cord 130 to a suitable DC voltage which is provided to power and ground 
lines (not shown). As a result, when the mobile terminal 10 is docked in 
the cradle 90, the mobile terminal 10 will receive external power from 
cradle 90 via contacts 60, 62, 110 and 112 for operation and/or charging 
of the batteries. 
FIG. 3 is a block diagram representing the basic structure of the mobile 
terminal 10 in accordance with an exemplary embodiment of the present 
invention. The mobile terminal 10 includes a processor 150 which can be 
programmed to control and to operate the various components within the 
mobile terminal 10 in order to carry out the various functions described 
herein. The processor 150 is coupled to a user input device 24 which 
allows an operator to input data to be communicated to a Local Area 
Network (LAN) such as inventory data, patient information, etc. This 
information may be sent to a host computer (not shown) which serves as a 
central data location, for example, or to a cash register connected to a 
system backbone, etc. The input device 24 can include such items as a 
keypad, touch sensitive display, etc. The mobile terminal 10 also may 
include a bar code reader 26 coupled to the processor 150 for providing 
another form of data input. The bar code reader 26 and the aforementioned 
input device 24 may be coupled to the processor via a user input interface 
circuitry (not shown). The user input interface circuitry could perform 
any conventional conditioning of the output signals from the bar code 
reader 26 and input device 24 as may be appropriate so that they may be 
received by the processor 150. 
The display 20 is also connected to and controlled by the processor 150 via 
a display driver circuit 162. The display 20 serves as a means for 
displaying information stored within the mobile terminal 10 and/or 
received over a system backbone, for example. The display 20 can be a flat 
panel liquid crystal display with alphanumeric capabilities, for example, 
or any type of display suitable for the present invention as will be 
appreciated. 
A memory 164 is included in the mobile terminal 10 for storing information 
such as program code executed by the processor 150 for carrying out the 
functions described herein. The actual code for performing such functions 
could be easily programmed by a person having ordinary skill in the art 
for computer programming in any of a number of conventional programming 
languages based on the disclosure herein. Consequently, further detail as 
to the particular code has been omitted for sake of brevity. The memory 
164 also serves as a storage medium for storing information input by the 
user and/or received from or transmitted by a transceiver such as RF 
section 166. The memory 164 may include both volatile and non-volatile 
memory, and may include a hard drive or other high density storage medium. 
The RF section 166 is also connected to the processor 150. The RF section 
166 includes an RF receiver 170 which receives RF transmissions from a 
base station (not shown), for example, via the antenna 50 and demodulates 
the signal to obtain digital information modulated therein. 
The RF section 166 also includes an RF transmitter 172. In the event the 
mobile terminal 10 is to transmit information in response to an operator 
input at the input device 24, for example, the processor 150 forms within 
the memory 164 an information packet (not shown) including data together 
with a source address (i.e.,the address of the particular mobile terminal 
10 sending the information) and a destination address (e.g., a host 
computer (not shown)). The information packet is then delivered to the RF 
transmitter 172 which transmits an RF signal with the information packet 
modulated thereon via the antenna 50 to the destination device. An example 
of a suitable RF section 166 for use in the mobile terminal 10 is the 
Model 025 Direct Sequence Spread Spectrum Radio Module, which is 
commercially available from Aironet Wireless Communications, Inc. of 
Akron, Ohio. 
The mobile terminal 10 further includes a unit power supply 178 which 
provides power to the mobile terminal 10. The unit power supply 178 is 
coupled to the contacts 60 and 62 and also to a detachable battery pack 
180. Thus, when the mobile terminal 10 is in a mobile state, the unit 
power supply provides power to the mobile terminal 10 via the battery pack 
180. When the mobile terminal 10 is docked, the unit power supply 178 can 
receive power externally via contacts 60 and 62 in order to operate the 
mobile terminal 10 as well as charge the batteries in the battery pack 
180. The battery pack 180 in this embodiment includes batteries which can 
be interchanged between a Ni--Cd and Li--Ion battery. However, it is to be 
appreciated that the scope of the present invention is intended to include 
any suitable battery types for use in the mobile terminal 10 according to 
the present invention. The circuitry of the present invention is 
illustrated handling differentiating between two battery types (i.e., 
Ni--Cd and Li--Ion) for ease of understanding, but the scope of the 
present invention intends to include differentiating between a plurality 
of battery types. The batteries of the battery pack 180 are connected via 
the unit power supply 178 to positive and negative contacts 60 and 62, 
respectively. The battery pack 180 is also tied to a battery charging 
status circuit 184 which feeds a status line 186a which provides the 
cradle 90 via contacts 64 and 114 with an appropriate voltage level 
representative of the type of battery being used by the mobile terminal 
10. The status circuit 184 is shown in greater detail in FIG. 5. 
Referring now to FIG. 4, a block diagram of the cradle 90 is shown. The 
cradle 90 includes a processor 200 with a built in memory 202. 
Furthermore, the processor 200 includes an Analog to Digital (A/D) 
converter 204. The status line 186a from the mobile terminal 10 is 
connected to the cradle 90 via contacts 64 and 114 to sense line 186b 
which ties into the A/D converter 204. The sense line 186b leading to the 
A/D converter 204 is tied high (e.g., .+-.5V) by a pull up resistor 210 
tied to line 207. The line 207 receives its .+-.5V from a cradle power 
supply 208. As is discussed in greater detail below, when the mobile 
terminal 10 is docked to the cradle 90, the sense line 186b leading to the 
A/D converter 204 will be pulled down in voltage (e.g., the voltage will 
drop below .+-.4.7V) indicating to the cradle 90 that the mobile terminal 
10 has docked. A charging circuit 220 provides power (including battery 
recharging power) to the mobile terminal 10. The processor 200 controls 
the charging circuit 220 in the cradle 90 based on the level of voltage 
received from the sense line 186b to the A/D 204. Thus, the processor 200 
is able to discriminate among different battery types being used in the 
mobile terminal 10 with the aid of the signal on the sense line 186b. The 
processor 200 determines the status of the mobile terminal 10 as well as 
the type of battery being used from the voltage applied to the A/D 204. 
Accordingly, the processor 200 controls the charging circuit 220 so that 
an appropriate amount of power (i.e., suitable for the charge 
characteristics of the battery type being used) is delivered to the mobile 
terminal 10. Of course, digital circuit components of other processors 
could be used to receive the signal on the sense line 186b and control the 
charge current supplied to the mobile terminal 10 through contacts 110 and 
111. 
The cradle power supply 208 provides all circuits in the cradle 90 with 
.+-.5V. The cradle power supply 208 is fed via the power supply apparatus 
124. The power supply apparatus 124 is also tied to the charging circuit 
220 so that operational power as well as charging power can be provided to 
the mobile terminal 10. An Application Specific Integrated Circuit (ASIC) 
230 is also in the cradle 90 to control COM port and optical 
communication. The mobile terminal 10 can download information optically 
via optics 232 which can be converted and sent via a COM port to a host 
computer (not shown). Therefore, the purpose of the optics 232 is for 
transmitting and receiving information from the mobile terminal 10. 
The status circuit 184 is depicted in greater detail in FIG. 5. The status 
circuit 184 is employed to vary the voltage that is ultimately applied to 
the A/D 204 of the cradle 90. As will be discussed in greater detail 
below, the processor 200 can determine whether or not the mobile terminal 
10 is docked to the cradle 90, whether the mobile terminal 10 is on or off 
while docked in the cradle 90, and what type of batteries the mobile 
terminal 10 is using. The status circuit 184 accomplishes the varying of 
the voltage applied to the A/D 204 via a plurality of pull down resistors 
which are engaged or not engaged alone and/or in combination to effect 
voltage dividers which pull down the voltage applied to A/D 204 based on 
the status of the mobile terminal and the type of batteries being used. 
A first pull down resistor 240 (preferably of 1 Meg resistance) is 
connected to the status line 186a so that when the mobile terminal 10 is 
placed in the cradle 90, the voltage on the sense line 186b in the cradle 
90 is pulled down to indicate to the processor 200 of the cradle 90 that a 
mobile terminal 10 is docked. When the mobile terminal 10 is not docked to 
the cradle 90, the voltage on sense line 186b is not pulled down and 
therefore the voltage applied to the A/D 204 via line 206 is 5 volts. 
The status circuit 184 includes an On/Off switch portion 190. The On/Off 
switch portion 190 is tied to a voltage source 192 (e.g., 5 volts) The 
other end of the On/Off switch portion is coupled to the base of a 
transistor 250. When the mobile terminal 10 is "ON", the on/off switch 190 
is closed, thus causing the transistor 250 to conduct. An emitter of the 
transistor 250 is tied to ground, and the collector of the transistor 250 
is tied to a second pull down resistor 252. The other end of the second 
pull down resistor 252 is tied to the status line 186a. When the 
transistor 250 conducts, the second pull down resistor 252 is tied to 
ground via the conducting transistor 250. Thus, the voltage level on the 
status line 186a is further reduced as a result of the addition of the 
second pull down resistor 252 to the voltage divider. 
The voltage varying line 260 is connected via a resistor 264 to a battery 
type circuit 270 shown by dotted line which is also included in the status 
circuit 184. One or more rechargeable batteries 266 inside of battery pack 
180 are coupled to the battery type circuit 270 via a switch 272. As will 
be discussed in greater detail below, the switch 272 opens and closes 
depending on the type of battery pack 180 being used by the mobile 
terminal 10. For example, when a Li--Ion type battery pack 180a (see FIG. 
6A) is inserted in the mobile terminal 10, the switch 272 remains open. On 
the other hand, when a Ni--Cd type battery pack 180b (see FIG. 6B) is 
inserted in the mobile terminal 10, the switch 272 closes. The other end 
of the switch 272 is tied to a line 274 and resistor 276. By maintaining 
the switch 272 open, the battery type signal on line 274 stays in a float 
state. The line 274 and a voltage source V.sub.BATT via a resistor 280 are 
tied to the base of a transistor 290. The collector of the transistor 290 
is also tied to V.sub.BATT and the emitter is tied to the base of a Field 
Effect Transistor (FET) 292 and a third pull down resistor 294 which is 
tied to ground. When the battery type signal on line 274 is in a float 
state (i.e., the switch 272 is open), the transistor 290 does not conduct. 
When the transistor 290 does not conduct, the FET 292 also does not 
conduct. When the FET 292 is not conducting, the third pull down resistor 
294 is not introduced to the status line 186a. 
When the switch 272 is closed, the battery type signal on line 274 is 
grounded causing the transistor 290 to conduct and in turn causing the FET 
292 to conduct. Current then flows from V.sub.BATT down through the third 
pull down resistor 294 thereby activating the FET 292 and causing the 
voltage on status line 186a to drop. The drop in voltage on status line 
186a is sensed by the processor 200 of the cradle 90 via sense line 186b 
and contacts 64 and 114. The processor 200 differentiates the battery type 
based on the sensed voltage level and thus charges the battery 266 in the 
mobile terminal 10 in accordance with the battery's particular charge 
characteristics. 
The various circuit component values and types (i.e., resistance values, 
capacitance values, transistor types, etc.) and the construction of the 
other circuit elements illustrated will depend on the particular 
application of the present invention. These details are within the 
abilities of those skilled in the art and therefore are not more 
particularly described herein. It should also be appreciated that many of 
the components included in the mobile terminal 10 and the cradle 90 can be 
integrated onto one or more integrated circuits. 
FIGS. 6A and 6B shows one exemplary embodiment of how different battery 
packs inserted in the mobile terminal 10 can cause the switch 272 to open 
or close. The battery pack 180a is for batteries of the Li--Ion type. The 
battery pack 180a includes a housing 302. The housing 302 is designed to 
provide for easy installation and removal of the battery pack 180a into 
and from the mobile terminal 10. The battery pack 180a houses the 
batteries therein and provides for secure, watertight housing of the 
batteries. The battery pack 180a includes a recess 306. The recess 306 is 
provided to ensure that the battery pack 180a does not engage the switch 
272 when the battery pack 180a is placed in the mobile terminal 10. Thus, 
when the Li--Ion battery pack is inserted in the mobile terminal 10, the 
switch 272 remains open thereby causing the voltage on status line 186a to 
remain in a state which indicates to the processor 200 that a Li--Ion 
battery is being used by the mobile terminal 10. 
FIG. 6B shows a Ni--Cd battery pack 180b which also includes a housing 308. 
The Ni--Cd battery pack 180b is essentially the same as that of the 
Li--Ion battery pack 180a and therefore further detail is omitted for sake 
of brevity. However, a difference does exist in that the Ni--Cd battery 
pack 180b does not have a recess like the recess 306 of the Li--Ion 
battery pack 180a. As a result, when the Ni--Cd battery pack 180b is 
inserted in the mobile terminal 10, the battery pack 180b comes into 
contact with switch 272 to close it. Thus, when the Ni--Cd battery pack 
180b is inserted in the mobile terminal 10, the switch 272 closes thereby 
causing the voltage on status line 186a to drop in the manner described 
above, which indicates to the processor 200 that a Ni--Cd battery is being 
used by the mobile terminal 10. 
It should be appreciated that there are numerous ways to effect such 
closing and opening of the switch 272 whether it be mechanical or 
electrical, all of which are intended to fall within the scope of the 
present invention. 
FIG. 7 shows a table 310 which is stored in the memory 202 of the processor 
200 of the cradle 90. The table 310 is used by the processor 200 to 
determine whether or not the mobile terminal 10 is docked to the cradle 
90, whether the mobile terminal 10 is on or off while docked in the cradle 
90, and what type of batteries the mobile terminal 10 is using. Such 
determination is made via the voltage levels applied to the A/D 204 via 
the status circuit 184. 
When the mobile terminal 10 is not docked to the cradle 90, as mentioned 
above, the voltage applied to the A/D 204 is 5 volts. The processor 200 
thus determines from table 310 that the voltage level of 5 volts applied 
to the A/D 204 indicates that the mobile terminal 10 is not docked to the 
cradle 90. When the mobile terminal 10 is docked to the cradle 90, the 
first pull down resistor 240 pulls down the voltage applied to the A/D 204 
below 5 volts thus indicating to the processor 200 that the mobile 
terminal 10 is docked to the cradle. If the mobile terminal 10 is on while 
docked in the cradle 90, the switch 190 is closed thereby engaging the 
first pull down resistor 252 further causing a drop in voltage applied to 
the A/D 204. Depending on the type of battery pack being used by the 
mobile terminal 10, the third pull down resistor 294 is engaged or 
disengaged as discussed above. 
Thus, based on the different voltage levels applied to the A/D 204, the 
processor 100 can determine whether the mobile terminal 10 is docked to 
the cradle 90 or not, whether the mobile terminal 10 while docked to the 
cradle 90 is on or off, and what type of batteries the mobile terminal 10 
is using. Referring more specifically to table 310, if the voltage level 
applied to the A/D is 5 volts, the processor 200 determines that no mobile 
terminal 10 is docked to the cradle 90. If the voltage level applied to 
the A/D 204 is in the range of 4.3-4.7 volts, the processor 200 determines 
that the mobile terminal 10 is docked to the cradle 90, is turned off, and 
is using Li--Ion batteries. If the voltage applied to the A/D is in the 
range of 2.9-3.3 volts, the processor 200 determines that the mobile 
terminal 10 is docked to the cradle 90, is turned on, and is using Li--Ion 
batteries. If the voltage applied to the A/D is in the range of 2.25-2.6 
volts, the processor 200 determines that the mobile terminal 10 is docked 
to the cradle 90, is turned off, and is using Ni--Cd batteries. If the 
voltage applied to the A/D is in the range of 1.82-2.1 volts, the 
processor 200 determines that the mobile terminal 10 is docked to the 
cradle 90, is turned on, and is using Ni--Cd batteries. 
Once the processor 200 determines the status of the mobile terminal 10 
(i.e., docked, not docked, on or off) and the type of battery being used, 
the processor 200 can apply an appropriate amount of power to the mobile 
terminal via the charging circuit 220, contacts 110, 112 and corresponding 
contacts 60 and 62 of the mobile terminal 10. The amount of recharging 
current to be applied to the battery pack 180a or 180b from the cradle 
charging circuitry 220 is well known in the art for the various charging 
characteristics of the battery types, and will vary depending on the 
particular application. Therefore, further detail as to such is not 
presented. 
Turning now to FIG. 8, a flow chart is provided which represents the 
general methodology of the present invention. In overview, the cradle 90 
determines the status of the mobile terminal 10 and the type of batteries 
the mobile terminal 10 is using based on the voltage level applied to the 
A/D 204. More specifically, in step 314 the cradle 90 is powered up to 
begin carrying out the functions described above. For sake of brevity, a 
discussion as to the powering up of either the cradle 90 and mobile 
terminal 10 is not provided. In step 316, the cradle 90 is in an active 
state awaiting the mobile terminal 10 to dock to it. In step 320, the 
processor 200 of the cradle determines if the voltage applied to the A/D 
204 (VA/D) is greater than or equal to 5 volts. If yes, the processor 200 
proceeds to step 326 where it determines that the mobile terminal 10 is 
not docked to the cradle 90. The processor 200 then returns to step 316. 
If in step 320, V.sub.A/D is not greater than or equal to 5 volts, the 
processor proceeds to step 330. In step 330, the processor 200 determines 
via table 310 that the mobile terminal 10 is docked to the cradle 90 based 
on V.sub.A/D being lower than 5 volts. As is mentioned above, the drop in 
voltage is the result of the first pull down resistor 240 engaging with 
the sense line 186b as a result of the mobile terminal 10 docking to the 
cradle 90. The engagement of the first pull down resistor 240 results in a 
voltage divider that pulls down V.sub.A/D below 5 volts. 
After step 330, the processor proceeds to step 340 where it determines if 
V.sub.A/D is within the range of 4.3-4.7 volts. If yes, the processor 200 
proceeds to step 344 where it determines via table 310 that the mobile 
terminal is off and is using a Li--Ion type battery. The Li--Ion battery 
pack 180a includes the recess 306 which maintains switch 272 open. 
Furthermore, since the mobile terminal 10 is off, switch 190 remains open. 
As a result, only the first pull down resistor 240 is engaged, which 
results in V.sub.A/D falling within the range of 4.3-4.7 volts. In step 
348, the processor 200 applies an appropriate level of power via the 
charging circuit 220 and contacts 110, 112 and corresponding contacts 60 
and 62 of the mobile terminal 10. The processor 200 then returns to step 
316. 
If in step 340, V.sub.A/D is not within the range of 4.3-4.7 volts, the 
processor 200 proceeds to step 350. In step 350, the processor 200 
determines if V.sub.A/D is within the range of 2.9-3.3 volts. If yes, the 
processor 200 proceeds to step 354 where it determines from table 310 that 
the mobile terminal 10 is on and is using a Li--Ion type battery. As 
mentioned above, the Li--Ion battery pack 180a includes the recess 306 
which maintains switch 272 open. However, since the mobile terminal 10 is 
on, switch 190 is now closed. As a result, the first pull down resistor 
240 and the second pull down resistor 252 are engaged, which results in 
V.sub.A/D falling within the range of 2.9-3.3 volts. In step 358, the 
processor 200 applies an appropriate level of power via the charging 
circuit 220 and contacts 110, 112 and corresponding contacts 60 and 62 of 
the mobile terminal 10. The processor 200 then returns to step 316. 
If in step 350, the processor 200 determines if V.sub.A/D is not within the 
range of 4.3-4.7 volts it proceeds to step 360. In step 360, the processor 
200 determines if V.sub.A/D is within the range of 2.25-2.6 volts. If yes, 
the processor 200 proceeds to step 364 where it determines via table 310 
that the mobile terminal is off and is using a Ni--Cd type battery. The 
Ni--Cd battery pack 180b does not include the recess 306 and thus closes 
switch 272. The closing of switch 272 results in the engagement of the 
third pull down resistor 294. Since the mobile terminal 10 is off, switch 
190 remains open. As a result, only the first and third pull down 
resistors 240 and 294 are engaged, which results in V.sub.A/D falling 
within the range of 2.25-2.6 volts. In step 368, the processor 200 applies 
an appropriate level of power via the charging circuit 220 and contacts 
110, 112 and corresponding contacts 60 and 62 of the mobile terminal 10. 
The processor 200 then returns to step 316. 
If in step 360, V.sub.A/D is not within the range of 2.25-2.6 volts, the 
processor 200 proceeds to step 370. In step 370, the processor 200 
determines if V.sub.A/D is within the range of 1.8-2.1 volts. If yes, the 
processor 200 proceeds to step 374 where it determines from table 310 that 
the mobile terminal 10 is on and is using a Ni--Cd type battery. As 
mentioned above, the Ni--Cd battery pack 180b does not includes the recess 
306 and thus switch 272 is closed. Furthermore, since the mobile terminal 
10 is on, switch 190 is now closed. As a result, the first, second and 
third pull down resistors 240, 252 and 294, respectively, are engaged, 
which results in V.sub.A/D falling within the range of 1.8-2.1 volts. In 
step 378, the processor 200 applies an appropriate level of power via the 
charging circuit 220 and contacts 110, 112 and corresponding contacts 60 
and 62 of the mobile terminal 10. The processor 200 then returns to step 
316. 
If in step 370, the processor 200 determines that V.sub.A/D is not within 
the range of 1.8-2.1 volts, the processor 200 proceeds to step 380. In 
step 380, the processor 200 generates an error message which is forwarded 
to processor 150 in the mobile terminal 10. The processor 150 then 
generates an error message which is provided to the user via the display 
20. After step 380, the processor 200 proceeds back to step 316. 
Although, the present invention has been described with respect to the 
battery packs 180a or 180b closing or opening a switch 272 which in turn 
alters the voltage applied to the A/D 204, it will be appreciated that 
other techniques can be employed to accomplish such sensing by the cradle 
90. For instance, it will be appreciated that the user himself could input 
the status of the mobile terminal 10 including battery type via the user 
input device so that the cradle 90 can determine what level of power to 
apply to the mobile terminal 10. 
Furthermore, it should be understood that other means for closing the 
switch 272 can be employed besides the use or lack of use of a recess 306 
in the battery pack. For example, the battery pack could have a bar code 
label attached thereto which could be scanned by an internal bar code 
reader (not shown). The bar code label could indicate the type of 
batteries associated with the battery pack. The bar code reader could send 
this information directly to the processor 200 which in turn would provide 
an appropriate level of power to the mobile terminal 10. Alternatively, 
internal circuitry to the battery pack 180 could be configured to place 
the status circuit 184 into the appropriate state depending on the battery 
type involved. In yet another embodiment, a program could be loaded that 
allows a user to input the battery type from a keypad or other user input 
device 24. 
It will be appreciated that the scope of the present invention is intended 
to include any mobile terminal 10 that indicates to the cradle 90 either 
actively or passively whether its docked or not docked to the cradle 90, 
whether its on or off, and the type of battery its employing. The cradle 
90 sensing the status of the mobile terminal 10 and the battery type 
applies an appropriate level of power to the mobile terminal 10 so that 
the mobile terminal 10 may operate while docked to the cradle 90 and/or so 
as to recharge the batteries currently being used by the mobile terminal. 
What has been described above are preferred embodiments of the present 
invention. It is, of course, not possible to describe every conceivable 
combination of components or methodologies for purposes of describing the 
present invention, but one of ordinary skill in the art will recognize 
that many further combinations and permutations of the present invention 
are possible. Accordingly, the present invention is intended to embrace 
all such alterations, modifications and variations that fall within the 
spirit and scope of the appended claims.