Battery connecting device for a computer system and a method of switching batteries

• US 5,784,626 A
• Filed: 07/26/1995
• Issued: 07/21/1998
• Est. Priority Date: 07/26/1994
• Status: Expired due to Fees

• Current Assignee: Lenovo Singapore Pte Limited (Lenovo Group Ltd.)
• Original Assignee: International Business Machines SA (International Business Machines Corporation)
• Inventors: Odaohara, Shigefumi
• Primary Examiner(s): Sheikh, Ayaz R.
• Assistant Examiner(s): DHARIA, RUPAL
• Application Number:
  US08/507,694
• Time in Patent Office: 1,091 Days
• Field of Search: 395/750, 395/750.01, 395/750.08, 307/66, 320/14, 320/15, 320/2, 320/22, 320/31, 320/48
• US Class Current: 713/300
• CPC Class Codes: H02J 1/10 Parallel operation of dc sources
• CPC Class Codes: H02J 7/0024 Parallel/serial switching of connection of batteries to charge or load circuit
• CPC Class Codes: H02J 9/061 for DC powered loads

Abstract

Two batteries can be selectively coupled to a computer, each through a separate pair of serially coupled transistors. Each of the four transistors is shunted by a diode, and each transistor can be individually controlled by a control circuit. To couple one of the batteries to the computer, the control circuit activates one pair of transistors, such that the battery current flows through the transistors and not through the diodes, thereby avoiding any power loss that would occur in the diodes. When switching from one battery to the other, the control circuit enters an intermediate mode in which one transistor in each of the two pairs of transistors is switched OFF, such that both batteries are momentarily "OR" coupled to the computer through two of the diodes, thereby preventing a momentary loss of power during the switching operation. A door covers both batteries such that neither battery can be removed except when the door is open. A door switch sends a signal to the control circuit that indicates door position. When the door is open, the control circuit "OR" couples both batteries to the computer through two of the diodes, thereby permitting either battery to be removed without interrupting power to the computer.

Claims

1. A battery powered electrical appliance, comprising:

an electrical apparatus;

first and second batteries for powering said electrical apparatus;

first and second switching devices, each of said first and second switching devices having at least three terminals, a first terminal of said first switching device being coupled to said first battery, a second terminal of said first switching device being coupled to a first terminal of said second switching device, a second terminal of said second switching device being coupled to said electrical apparatus;

first and second diodes, each one of said first and second diodes being coupled between said first and second terminals of a unique one of said first and second switching devices;

third and fourth switching devices, each of said third and fourth switching devices having at least three terminals, a first terminal of said third switching device being coupled to said second battery, a second terminal of said third switching device being coupled to a first terminal of said fourth switching device, a second terminal of said fourth switching device being coupled to said electrical apparatus;

third and fourth diodes, each one of said third and fourth diodes being coupled between said first and second terminals of a unique one of said third and fourth switching devices; and

a control circuit having four outputs for individually controlling each of said switching devices, each of said outputs being coupled to a third terminal of a unique one of said switching devices, said control circuit for selectively coupling said first and second batteries to said electrical apparatus, said control circuit having a first mode of operation wherein said first battery is coupled to said electrical apparatus through said first and second switching devices, said control circuit having a second mode of operation wherein said second battery is coupled to said electrical apparatus through said third and fourth switching devices, said control circuit having an intermediate mode of operation wherein both said first and second batteries are "OR" coupled to said electrical apparatus through said first and third diodes.

2. The battery powered electrical appliance of claim 1, wherein said intermediate mode of operation is momentarily selected when said control circuit switches from said first to said second modes of operation, thereby preventing any momentary loss of power to said electrical apparatus.

3. A battery powered electrical appliance, comprising:

an electrical apparatus;

first and second batteries for powering said electrical apparatus, said batteries being removably attached to said electrical appliance;

a door covering said batteries, said door having open and closed positions, said door preventing the removal of said batteries when said door is in said closed position;

a door switch coupled to said door, said door switch having first and second positions, said door switch being in said first position when said door is closed, said door switch being in said second position when said door is open;

first and second switching devices, each of said first and second switching devices having at least three terminals, a first terminal of said first switching device being coupled to said first battery, a second terminal of said first switching device being coupled to a first terminal of said second switching device, a second terminal of said second switching device being coupled to said electrical apparatus;

first and second diodes, each one of said first and second diodes being coupled between said first and second terminals of a unique one of said first and second switching devices;

third and fourth switching devices, each of said third and fourth switching devices having at least three terminals, a first terminal of said third switching device being coupled to said second battery, a second terminal of said third switching device being coupled to a first terminal of said fourth switching device, a second terminal of said fourth switching device being coupled to said electrical apparatus;

third and fourth diodes, each one of said third and fourth diodes being coupled between said first and second terminals of a unique one of said third and fourth switching devices; and

a control circuit having four outputs for individually controlling each of said switching devices, each of said outputs being coupled to a third terminal of a unique one of said switching devices, said control circuit for selectively coupling said first and second batteries to said electrical apparatus, said control circuit having an intermediate mode whereupon both said first and second batteries are "OR" coupled to said electrical apparatus through said first and third diodes, said control circuit having an input coupled to said door switch, said intermediate mode being selected when said door is open and said door switch is in said second position, such that either one of said first and second batteries can be removed from said electrical appliance without interrupting the flow of power into said electrical apparatus.