HK1023000B - An apparatus for switching between a main battery and a removable auxiliary battery in an electronic device - Google Patents

Description

Device for switching between a main battery and a detachable auxiliary battery in an electronic device

Technical Field

The present invention relates generally to a device for extending the battery life of a portable electronic device, such as a cellular telephone, and more particularly to a switch capable of detecting the presence of an auxiliary battery and switching the power supply circuitry of the electronic device to the auxiliary battery.

Background

The battery pack is the primary power source for portable electronic devices such as cellular telephones. The portable nature of cellular telephones is limited by the inability of their battery power to permanently and continuously supply power. After the battery has been discharged for a period of time, the cellular phone must be plugged into a charger in order to recharge the battery. To obtain more battery power (longer battery life), the size of the battery element must generally be increased. This presents a problem for cellular phone designers due to the conflict between the desire for phones with longer talk and standby times (i.e., longer battery life) and the desire for smaller and lighter phones.

Existing solutions for short talk and standby times have been limited to developing large capacity batteries for cellular telephone devices. These batteries are limited by the size and weight described above. The contradiction between size and power is increasingly prominent due to the development of the next generation of smaller and smaller telephone devices. Other solutions involve the use of improved battery technology to increase the ratio of charge per volume to charge per weight of existing battery systems. However, these improvements are not sufficient to synchronize with the smaller size of cellular telephone devices that can use existing components and technologies. Thus, in order to meet the current market demand, there is a need for an apparatus for increasing the battery life of a cellular telephone while keeping the size and weight of the cellular telephone unchanged.

Disclosure of Invention

It is an object of the present invention to provide a means for switching between a main battery and an auxiliary battery in response to the connection of the auxiliary battery to an electronic device such as a portable communication device.

According to one aspect of the present invention, there is provided an apparatus for switching between a main battery and a detachable auxiliary battery in an electronic device, characterized by first and second switches connected to said main battery and said auxiliary battery, respectively, for interconnecting said main battery and said auxiliary battery with a power system of the electronic device; a voltage detector connected to said auxiliary battery for detecting a voltage drop across the connection of said removable auxiliary battery to the electronic device and for generating a voltage signal indicative of the presence of said removable auxiliary battery; and a processor connected to said voltage detector and said first and second switches, responsive to voltage signals generated by said power detector, for commanding the means for interconnecting to connect said auxiliary battery to the system power source and to disconnect said main battery from the system power source.

According to another aspect of the present invention there is provided apparatus for switching between a main battery and a detachable auxiliary battery associated with an electronic device, characterised by first and second switches connected to said main battery and said auxiliary electronic respectively, for interconnecting said main battery and said auxiliary battery to a power supply circuit of the electronic device; a current detector for detecting a current generated from the auxiliary battery by connecting the auxiliary battery to the power supply circuit, and for generating a current signal indicating a result of the detection; a voltage detector for determining whether said auxiliary battery provides a predetermined voltage value and for generating a voltage signal indicative of a result of said determination; and a processor connected to the first and second switches for controlling the first and second switches to connect and disconnect the main battery and the auxiliary battery in response to the voltage signal and the current signal.

According to a further aspect of the present invention there is provided an apparatus for switching between a main battery and a removable auxiliary battery associated with an electronic device, characterised by a first connection means for said main battery; a second connecting means for said removable auxiliary battery; first and second switches connected to the main battery and the auxiliary electronic, respectively, for interconnecting the main battery and the auxiliary battery with a power circuit of an electronic device; a resistor connected to said electronic device, a voltage drop being generated across said resistor in response to the connection of said auxiliary battery to said second connecting means; a voltage detector for generating a first voltage signal in response to said voltage drop across said resistor, said voltage detector further determining whether said auxiliary battery provides a predetermined voltage value and for generating a second voltage signal indicative of said determination; and a processor for controlling the first and second switches in response to the first and second voltage signals to connect and disconnect the main battery and the auxiliary battery.

According to the present invention, the main battery and the auxiliary battery are connected to the system power source through the first and second switches, respectively. The main battery is located within the cellular telephone unit, but it is connected to the system power supply only when the auxiliary battery is not connected or the voltage of the auxiliary battery drops below a certain value. The auxiliary battery is connected to a belt holder for the cellular phone. The first and second switches are controlled by control signals from the microprocessor.

In a first embodiment, the connection of the auxiliary battery generates a current through the switching circuit that is detected by the current detector. The current detector generates a current signal in response to the current flowing therethrough and provides the signal to the microprocessor. The voltage detector measures a voltage level present in the auxiliary battery and determines whether the voltage level satisfies a predetermined threshold voltage. The voltage detector then generates a voltage signal indicating whether the voltage value satisfies the desired threshold and provides the signal to the microprocessor.

In another embodiment, the connection of the auxiliary battery produces a voltage across a resistor in the switching circuit that is detected by a voltage detector that generates a signal in response to the voltage across the resistor and provides the signal to the microprocessor. In response to the detection of the voltage, the voltage detector also measures a voltage level present within the auxiliary battery to help determine whether the voltage level meets a predetermined threshold.

The microprocessor uses the current signal and/or the voltage signal to determine which battery is to be connected to the system power supply. If the signal indicates that the auxiliary battery is not connected, the main battery is connected. If the signal indicates that the auxiliary battery is connected but the auxiliary battery does not have sufficient voltage, the main battery is connected and the auxiliary battery is disconnected. However, if the auxiliary battery is connected and has a sufficient voltage, the auxiliary battery is connected and the main battery is disconnected. In this manner, the effective battery life of the main battery may be extended without a corresponding increase in the size of the battery power supply associated with the cellular telephone device.

Drawings

For a more complete understanding of the present invention, reference is made to the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a side view of a cellular telephone and a telephone holder including an auxiliary battery;

FIG. 2 is another embodiment of the invention shown in FIG. 1, wherein the retainer includes an opening for attachment of an accessory;

FIG. 3 is a block diagram illustrating circuitry for converting battery power between an auxiliary battery and a main battery when the cellular telephone is in the telephone holder;

FIG. 4 is a circuit diagram of the current detector block of FIG. 3;

FIG. 5 is a block diagram illustrating the control flow of the microprocessor of FIG. 4;

FIG. 6 is another embodiment of the circuit shown in FIG. 3 for converting power between an auxiliary battery and a main battery; and

fig. 7 is a control flow chart for explaining the microprocessor shown in fig. 6.

Detailed Description

Referring now to the drawings, and in particular to FIG. 1, there is shown a side view of a cellular telephone holder 15 including an auxiliary battery and associated cellular telephone device 10. Cellular telephone device 10 includes a main housing 20, a battery 25 and an antenna 30. Contacts 35 at the bottom of the cellular telephone provide connections to the power circuitry of the cellular telephone device 10. The circuitry associated with contact 35 will be discussed in more detail later. Although the present invention is described with the contact point provided at the bottom of the cellular phone device 10 as an example, the contact point may be provided at any position that enables the cellular phone device 10 and the auxiliary battery 40 of the phone holder 15 to be connected.

The cellular phone holder 15 includes the auxiliary battery 40 integrally connected to the housing 55. The holder case 55 is designed such that the case 55 and the auxiliary battery 40 are integrally formed as one piece, or such that the auxiliary battery can be detachably attached to the holder case by sliding, snapping, or other attachment methods. The cellular telephone holder 15 may also include charger contacts 49 for connection to a battery recharger.

The housing 55 defines a cradle 53 for holding the cellular telephone device 10. The location of the retaining protrusion 56 in the housing 55 is such that the protrusion may lockably engage with a corresponding slot 60 in the housing 20 of the cellular telephone device 10. The combination of the protrusions 56 and the slots 60 allows the telephone device 10 to be secured within the cradle 53 while still being removable from the telephone holder 15. A clip 45 is attached to the back of the holder housing 55 which enables the user to hold the cellular phone holder 10 in a position on his clothing, typically a belt. This enables the weight of the auxiliary battery 40 to be carried more conveniently at a location outside the telephone apparatus 15.

Cradle 53 of cellular telephone device 10 also includes contacts 70 for connecting contacts 35 of portable telephone device 10. The contacts 70 interconnect the positive and negative terminals of the auxiliary battery 40 and the portable telephone device 10.

Inside the portable telephone device 10 is an auxiliary battery detection circuit 80 for switching the system power between the main battery 25 and the auxiliary battery 40. The conversion between batteries corresponds to the conversion between currents sent by means of putting or taking the telephone device 10 in or out of the housing 55. The detector 80 also switches power back to the main battery 25 when the auxiliary battery 40 is depleted. Preferred embodiments of the detector circuit 80 will be discussed more fully with reference to fig. 3-5.

Referring now to fig. 2, there is shown a side view of another embodiment of a cellular telephone holder 55 including an opening 85 in the cradle that enables peripheral devices to be connected to the telephone device 10. Through the opening 85, data accessories, chargers, and/or other telephone connections may be connected to the telephone unit 10.

It should be understood that while fig. 1-2 are described in terms of using a cellular telephone and a cellular telephone holder, the electronic holding device with an integrated auxiliary battery is equally applicable to any electronic device having a back-up mode and an internal battery or device requiring increased battery life.

Referring now to fig. 3, an auxiliary battery detector circuit 80 for detecting the connection of the auxiliary battery 40 to the cellular telephone device 10 is shown. The detector circuit 80 includes a pair of contacts 100 for interconnecting the main battery 25 and the auxiliary battery 40 with the power circuitry of the telephone device 10. A pair of switches 115 and 120 are used to interconnect the main battery 25 and auxiliary battery 40 with the rest of the phone power circuitry 118. Switches 120 and 115 are controlled by microprocessor 125 in response to control signals received from current detector 130 and voltage detector 135.

The current detector 130 detects a current passing through the resistor 150. The current through the resistor 150 is sent by connecting the auxiliary battery 40 to the portable telephone device 10. Referring now to fig. 4, the circuit of the current detector 130 is shown. Voltage readings (V1 and V2) are taken from each end of resistor 150 and provided to a pair of inputs of a pair of operational amplifiers 155. The voltage V1 is connected to the positive input of the operational amplifier 155a, while the voltage V2 is connected to the negative input. The input of the operational amplifier 155b is connected to these voltages in the opposite way. The operational amplifier 155 amplifies the voltage difference across the resistor 155. Since a negative power supply voltage is not used in the portable telephone device 10, each operational amplifier 155 has its negative power supply terminal 162 grounded, and thus cannot supply a negative voltage. Thus, two operational amplifiers 155 are required to amplify the voltage difference in each direction of the current.

The voltage differential output of each operational amplifier 155 is provided to the inputs of an or gate 170. If either of the first or second operational amplifiers generates a high voltage, indicating that current is flowing through sense resistor 150, or gate 170 outputs a logic high voltage signal. This is interpreted by the microprocessor 125 as an auxiliary battery being connected, so switch 120 is closed and switch 115 is open to maintain power from the main battery 25. When the outputs of the first and second operational amplifiers 155 are low, then the or gate 170 signals a logic low voltage and the switch 115 is closed to provide power from the main power supply 25. Switch 120 also remains closed to pass current through resistor 150 once auxiliary battery 40 is connected.

Referring again to fig. 3, the voltage detector 135 determines the voltage output of the connected auxiliary battery 40 and issues a voltage signal indicating whether there is sufficient voltage to power the cellular telephone device 10. The basis for sufficient voltage is whether the auxiliary battery 40 can supply a preselected threshold voltage. When the auxiliary battery voltage falls below a predetermined threshold, a signal is sent to the microprocessor 125 indicating such a condition. The switch 120 is then opened, disconnecting the auxiliary battery 40 from the power circuit 118, and the switch 115 is closed to connect the main battery 25. Since the switch 120 is open, the resistor 150 can no longer detect the connection to the auxiliary battery 40. Thus, the resistor 200 enables detection of the physical connection of the auxiliary battery and the contact 100. When the auxiliary battery 40 and the contact 100 are engaged, the voltage across the resistor 200 is positive. Once the auxiliary battery 40 is disconnected, the voltage across the resistor 200 becomes 0. The voltage across resistor 200 is monitored by voltage detector 135.

Referring now to fig. 5, there is shown a flow chart illustrating an algorithm used by the microprocessor 125 to control the switches 115 and 120. The algorithm schematically illustrates the decision process performed by the microprocessor 125. Initially, both switches 115 and 120 are closed. Query step 210 determines whether the auxiliary battery 40 has been connected to the cellular telephone device 10 by measuring the current through resistor 150. The microprocessor 125 continues to monitor the connection of the auxiliary battery 40 in step 210 until a connection is detected. Once connection of the auxiliary battery 40 is detected, query 215 determines whether the auxiliary battery voltage is too low. When the voltage level is too low, the switch 120 is opened in step 220. Query 221 determines whether the voltage across resistor 200 is greater than 0. As previously mentioned, a voltage across resistor 200 greater than 0 indicates that the auxiliary battery remains connected. If the auxiliary battery is connected, control returns to step 215 to determine if the battery voltage is too low. If the auxiliary battery 40 is not connected, the switch 120 is closed in step 222 and control returns to step 210 to monitor for reconnection of the auxiliary battery.

If sufficient voltage is present within the auxiliary battery 40, the switch 115 is opened in step 225. Query 230 determines whether the auxiliary battery 40 is still connected by sensing the current through resistor 200. If the auxiliary battery 40 is still connected, query 235 determines if sufficient auxiliary battery voltage is still maintained. As long as the auxiliary battery 40 remains connected and provides sufficient voltage, control continues to loop through query steps 230 and 235 to monitor for disconnection and low voltage of the auxiliary battery 40. If the voltage in the auxiliary battery 40 drops below an acceptable value, the switch 120 is opened in step 240 while the switch 115 is closed in step 245, thereby connecting the telephone unit to the main battery 25.

Once the main battery 25 is reconnected, query 246 determines whether the auxiliary battery 40 is still connected by determining whether the voltage across resistor 100 is greater than 0. If so, control returns to step 235 to determine if the auxiliary battery voltage is still low. If the auxiliary battery has been disconnected, control resets switches 120 and 115, via steps 250 and 255, to await reconnection of the auxiliary battery 40.

Once the auxiliary battery 40 is disconnected, the switch 115 is closed in step 250, while the switch 120 is closed in step 255. The power control of the system is thus switched to the main battery 25 and control returns to step 210 to await reconnection of the auxiliary battery 40.

Using the circuits and algorithms described above, the device will operate in the following manner. In normal operation, the auxiliary battery 40 is not connected. The power source for the telephone device 10 is thus the main battery 25. The switch 115 is closed so that the phone draws current from the main battery 25. The switch 120 is also kept closed so that the connection of the auxiliary battery 40 can be detected. When the user connects the auxiliary battery 40, current flows through the sense resistor 150 and the voltage across the resistor 200 is made greater than 0. This current is detected by the current detector 130 and a current signal is sent to inform the microprocessor 125.

The voltage detector 135 and microprocessor 125 then determine if there is sufficient voltage to operate the telephone unit 10. If the voltage of the auxiliary battery 40 is too low, the microprocessor 125 keeps the switch 115 closed and opens the switch 120. This prevents the auxiliary battery 40 from drawing current from the main battery 25. If the voltage is high enough, the microprocessor 125 opens the switch 115 to prevent current from being drawn from the main battery 25.

Switch 115 remains open and switch 120 remains closed for a period of time until the voltage of auxiliary battery 40 drops below a predetermined threshold or telephone device 10 is disconnected from the auxiliary battery. In each case, the switch 115 is closed so that the telephone device 10 is now powered by the main battery 25. If switch 115 is closed due to a low voltage value, switch 120 is opened for the reasons described above. If the auxiliary battery 40 has been opened, as indicated by the voltage across resistor 200, switch 120 remains closed, enabling detection of the current flowing through the sense resistor 150.

The above circuit is explained in terms of a cellular telephone device. It should be understood, however, that such circuitry may be applied to other electronic devices requiring increased battery life without a corresponding increase in device size.

Referring now to fig. 6, another embodiment of the present invention is illustrated in which only the voltage detector 135 monitors the connection of the auxiliary battery 40. The same reference numerals are used for the same components as those shown in fig. 3. The detection circuit 80 includes a pair of contacts 100 for interconnecting the main battery 25 and the auxiliary battery 40 with the power circuitry 118 of the telephone unit 10. A pair of switches 115 and 120 interconnect the main battery 25, the auxiliary battery 40 and the rest of the phone power circuitry 118. Switches 120 and 115 are controlled by microprocessor 125 in response to signals received from voltage detector 135.

The voltage detector 135 monitors the voltage across the resistor 200, and the voltage across the resistor 200 changes in response to the connection of the auxiliary battery 40 to the junction 100 of the detection circuit 80. When the auxiliary battery 40 and the contact 100 are engaged, the voltage across the resistor 200 is positive, and once the auxiliary battery 40 is disconnected, if the switch 120 is opened, the voltage across the resistor 200 becomes 0.

The voltage detector 135 also monitors the voltage output of the connected auxiliary battery 40 and generates a signal indicating whether there is sufficient voltage to power the cellular telephone device 10. The basis for the sufficient voltage is whether the auxiliary battery 40 can supply a predetermined threshold voltage. When the auxiliary battery voltage drops below a predetermined threshold, a signal is sent to the microprocessor 125 indicating such a condition. The auxiliary battery is then disconnected from the circuit.

Referring now to FIG. 7, a flowchart of an algorithm executed by the microprocessor 125 for controlling the switches 115 and 120 is illustrated for the embodiment of FIG. 6. The algorithm schematically illustrates the decision process performed by the microprocessor 125. Initially, switch 115 is closed and switch 120 is open. This connects the main battery 25 to the phone power circuit 118. Query 300 monitors the voltage across resistor 200 to determine if the voltage is greater than 0. A voltage value equal to 0 indicates that the auxiliary battery 40 has not been connected, and control continues to loop through step 300. When connection of the auxiliary battery 40 is detected, query 305 determines whether the auxiliary battery voltage is too low. If so, control transfers to query 310 to again determine whether the voltage across resistor 200 is greater than 0. If so, control continues back to step 305. Once the voltage across resistor 200 indicates that auxiliary battery 40 has been disconnected, control returns to step 300.

If query 305 determines that the auxiliary battery voltage is not too low, then switch 120 is closed in step 315 and switch 115 is opened in step 320. This disconnects the main battery 25 from the power circuit 118 and connects to the auxiliary battery 40. The voltage detector 135 continues to monitor the connection of the auxiliary battery 40 and the power circuit 118 at query step 325. If resistor 200 is held at a positive voltage, query 330 again checks if the auxiliary battery voltage is too low. If so, the switch 115 is closed in step 335 and the switch 120 is opened in step 340 to disconnect the auxiliary battery 40 from the power circuit 118 and control returns to step 325. If the voltage is not too low, the processor 125 simply continues to monitor for continued connection by returning to step 325.

Once the interrogation step 325 determines that the voltage across the resistor 200 is no longer greater than 0, the switch 115 is closed in step 345 and the switch 120 is opened in step 350, thereby reconnecting the main battery 25. Control then returns to step 300 to monitor for reconnection of the auxiliary battery 40. Using the circuits and algorithms discussed above, this embodiment will operate as follows. In the normal operating mode, the auxiliary battery 40 is not connected and the power source for the cellular phone device 10 is the main battery 25. Thus, in the normal operating mode, the switch 115 is closed and the cellular telephone device 10 can draw current from the main battery 25. During normal operation, the switch 120 is opened. The microprocessor 125 of the cellular telephone device continues to monitor the voltage detector 135 to determine the voltage across the resistor 200.

When the auxiliary battery 40 is connected, a voltage drop occurs across the resistor 200, and the voltage of the auxiliary battery 40 can be read out by the voltage detector 135. The microprocessor 125 then determines whether the auxiliary battery 40 has a voltage sufficient to operate the cellular telephone device 10. If the voltage of the auxiliary battery 40 is too low to operate the cellular telephone device 10, the microprocessor 125 does not operate and the telephone continues to be powered by the main battery 25. If the voltage of the auxiliary battery 40 is high enough, the microprocessor 125 causes the switch 120 to close, enabling the cellular telephone device 10 to draw current from the auxiliary battery 40. The cellular telephone unit 10 will then open the switch 115 thereby preventing further current draw from the main battery 25.

The cellular telephone device 10 will hold switch 115 open and switch 120 closed until the microprocessor 125 detects that the voltage of the auxiliary battery 40 has dropped below a minimum threshold value, or detects that the cellular telephone device 10 has been disconnected from the auxiliary battery 40. In each case, once this is detected, the switch 115 is closed so that the phone can be powered by the main battery 25. The switch 120 is opened to facilitate further detection as to whether the auxiliary battery 40 has a voltage sufficient to power the phone.

Although preferred embodiments of the apparatus and method of the present invention have been described in detail with reference to the accompanying drawings, it is to be understood that the invention is not limited to the embodiments described, but is capable of numerous modifications without departing from the scope and spirit of the invention as defined by the following appended claims.

Claims (6)

1. An apparatus for switching between a main battery and a detachable auxiliary battery in an electronic device,

first and second switches connected to the main battery and the auxiliary battery, respectively, for interconnecting the main battery and the auxiliary battery with a power system of an electronic device;

a voltage detector connected to said auxiliary battery for detecting a voltage drop across the connection of said removable auxiliary battery to the electronic device and for generating a voltage signal indicative of the presence of said removable auxiliary battery; and

a processor connected to said voltage detector and said first and second switches, responsive to voltage signals generated by said power detector, for commanding the means for interconnecting to connect said auxiliary battery to the system power source and to disconnect said main battery from the system power source.

2. The apparatus of claim 1, wherein the voltage detector comprises:

a resistor; and

means connected to said resistor for detecting a voltage change across said resistor caused by connecting said removable auxiliary battery to electronic means and for generating a voltage signal indicating the presence of said voltage change.

3. An apparatus for switching between a main battery and a detachable auxiliary battery associated with an electronic device,

first and second switches connected to the main battery and the auxiliary electronic, respectively, for interconnecting the main battery and the auxiliary battery with a power circuit of an electronic device;

a current detector for detecting a current generated from the auxiliary battery by connecting the auxiliary battery to the power supply circuit, and for generating a current signal indicating a result of the detection;

a voltage detector for determining whether said auxiliary battery provides a predetermined voltage value and for generating a voltage signal indicative of a result of said determination; and

a processor coupled to the first and second switches for controlling the first and second switches to connect and disconnect the main battery and the auxiliary battery in response to the voltage signal and the current signal.

4. The apparatus of claim 3, further comprising:

a resistor connected to the electronic device through which current flows in response to the connection of the auxiliary battery.

5. The apparatus of claim 4, wherein the current detector comprises:

first and second operational amplifiers for measuring a difference voltage across the resistors; and

an OR gate responsive to the outputs of said first and second operational amplifiers for generating a current signal indicative of the current flow in said resistor.

6. An apparatus for switching between a main battery and a detachable auxiliary battery associated with an electronic device,

a first connection means for said main battery;

a second connecting means for said removable auxiliary battery;

first and second switches connected to the main battery and the auxiliary electronic, respectively, for interconnecting the main battery and the auxiliary battery with a power circuit of an electronic device;

a resistor connected to said electronic device, a voltage drop being generated across said resistor in response to the connection of said auxiliary battery to said second connecting means;

a voltage detector for generating a first voltage signal in response to said voltage drop across said resistor, said voltage detector further determining whether said auxiliary battery provides a predetermined voltage value and for generating a second voltage signal indicative of said determination; and

a processor for controlling the first and second switches to connect and disconnect the main battery and the auxiliary battery in response to the first and second voltage signals.