Abstract:
An apparatus comprising a chassis and a cassette. The chassis includes a first electronic circuit board with a first connector, chassis flex circuitry with a disengageable contacts, a controller in communication with the chassis flex circuitry, and a power supply in communication with the controller and the first electronic circuit board. The cassette is selectively securable to the chassis, the cassette including a second electronic circuit board with a second connector, and a cassette handle with cassette flex circuitry that includes a switch and disengageable contacts, wherein securing the cassette to the chassis positions the disengageable contacts of the cassette flex circuitry in engagement with the disengageable contacts of the chassis flex circuitry to form a circuit and positions the first connector in electronic communication with the second connector, and wherein the circuit allows the controller to detect the condition of the switch. A switch trigger is disposed on the cassette handle to actuate the switch, wherein the switch trigger selectively locks or unlocks the cassette to the chassis.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to computer hardware components. More specifically, the present invention provides an apparatus for directing power to a hot-swappable computer component when inserted, and safely powering down the component prior to removal. 
   2. Description of the Related Art 
   Hot swappable components have become commonplace in computer systems. Server systems often use hot swappable memory, hard drives, and various pieces of hardware commonly referred to as Peripheral Component Interconnect (PCI) cards. Hot swapping may involve the removal of a piece of hardware, or the insertion of a piece of hardware, or both while the computer is on and functioning. While the following discussion refers to PCI cards, the problems presented are equally applicable to any other hot swappable electronic circuit board. 
   Computer systems that support hot swapping need some ability to detect that a component has been removed or inserted and to determine what resources are available for use. Notifying the system that a component has been inserted or removed allows for efficient allocation of resources and the use of computing power. 
   In addition, all connections need to be designed such that neither the component nor the user can be damaged or injured by removing or installing it. Most, if not all, computer components require power to be operational. The electronic connections between components must be designed to ensure that connecting the components will not result in a power surge to either component, which may result in damage to sensitive electronics. 
   The components of the computer system must be designed to accommodate removal or installation of other components. When a component is removed, the computer system must reallocate tasks to other components. When a component is inserted, the system must be able to allocate tasks to that component in order to make the most efficient use of the system resources. 
   One method of inserting a PCI card is to utilize a cassette system in which the PCI card with a connector is secured. The cassette may then be inserted into a chassis wherein a connection is made between the PCI card within the cassette, and other pieces of hardware with receiving connectors. 
   Many PCI cards receive power from the connector in which they are inserted. In order to avoid power surges and damage to the PCI card or the user, it is preferable that no power is being provided to a receiving connector during insertion or removal of a PCI card. Future implementations of operating system software may require that no power is provided to the receiving connector during insertion or removal of a PCI card. 
   Therefore, there is a need for an apparatus and method to ensure that no power is provided during removal of a PCI card, as well as preventing power to the PCI card during insertion. When a cassette system is employed to insert and remove electronics, it is desirable to incorporate this feature into the cassette. 
   SUMMARY OF THE INVENTION 
   The present invention provides a chassis to receive a cassette. The cassette is used to insert or remove a second electronic circuit board with a second connector, into the chassis housing a first electronic circuit board with a first connector that receives the second connector. The second electronic circuit board with the second connector is secured by the cassette. The cassette further comprises an activation switch. When the cassette is properly received by the chassis and the switch is activated, the activation of the switch indicates to a controller that the second connector of the second electronic circuit board has been received in the first connector of the first electronic circuit board. The controller instructs a power source to provide power to the second connector of the second circuit board through the first connector. The invention preferably locates the switch on a cassette handle, where the switch is activated or deactivated by a user manually toggling a switch trigger on the cassette handle. 
   When the switch associated with a powered second electronic circuit board is deactivated, the controller instructs the second electronic circuit board to complete any operations underway and enter a quiescent state where no data transmission is occurring. The controller also prevents further operations from being assigned to the second electronic circuit board, such as by instructing the first electronic circuit board not to assign further operations. Upon completion by the second electronic circuit board of any ongoing operations (i.e., reaching a quiescent state), the controller instructs the power source to halt the power supplied to the second connector of the second circuit board through the first connector. In one embodiment, an indicator light, such as an LED on the cassette, informs the user that the second electronic circuit board is quiescent and that the second connector of the second electronic circuit board may be safely disengaged from the first connector without any loss of date over the PCI bus by lifting the cassette handle. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side view of a cassette pivotally secured to a chassis in the up position. 
       FIG. 2  is a side view of a cassette pivotally secured to a chassis in the down position. 
       FIG. 3  is a perspective view of a plurality of cassettes received within a chassis. 
       FIG. 4  is a detailed view of a plurality of cassettes with handles received in a chassis. 
       FIG. 5  is a detailed view of a plurality of cassettes with handles received in a chassis. The switch trigger is not shown. 
       FIG. 6  is a rear view of the first flex circuit pathway. 
       FIG. 7  is a schematic showing one potential operation of the present invention. 
   

   DETAILED DESCRIPTION 
   The present invention provides a chassis that receives a cassette, supplies power to the cassette, and communicates with electronic components on the cassette, such as an electronic circuit board. The chassis comprises a first electronic circuit board with a first connector to receive a second electronic circuit board with a second connector. The cassette and the chassis selectively cooperate in a predetermined manner to align the second connector with the first connector. The first electronic circuit board has a first connector that receives a second electronic circuit board and supplies power to the second electronic circuit board. A typical example of a first electronic circuit board is a motherboard. 
   The chassis further comprises chassis flex circuitry including a pair of contacts arranged to contact cassette flex circuitry when the cassette is received by the chassis. The cassette flex circuitry and the chassis flex circuitry complete a circuit when there is contact therebetween. The chassis flex circuitry includes an electrically conducting material, such as a conducting metal. Portions of the conducting metal that are exposed to air, such as a set of contacts, are preferably made of a non-corroding metal, such as gold. 
   The chassis flex circuitry is coupled to a controller and the controller is in communication with a power supply. The controller regulates the provision of power to the first connector of the chassis, and therefore to the electronic components of the cassette, based upon the state of a switch in the cassette flex circuitry. 
   The cassette includes a second electronic circuit board having a second connector to be received by the first connector. The second electronic circuit board may be any hardware that is commonly inserted and/or removed “on-the-fly”, while the computer system is in operation (hot swapped). Daughter cards, PCI cards, and USB drives are some examples of hardware that may be hot swapped. Many, if not all, of these devices receive power from the connector into which they are plugged. 
   The cassette further comprises a cassette handle with the cassette flex circuitry. The cassette handle is preferably comprised of a non-conducting material, to insulate the user from any potential electrical shock. The cassette flex circuitry is electrically conductive and includes a switch between two terminal contacts configured to make contact with an opposing pair of contacts on the chassis. While the cassette flex circuitry may be made of any conductive metal, those portions exposed to air are preferably comprised of a non-corroding metal, such as gold. The switch selectively opens or closes the cassette flex circuitry. In one embodiment, the switch closes to complete the cassette flex circuitry between the two contacts of the cassette flex circuitry and opens to break the cassette flex circuitry so that no current may be conducted through the cassette flex circuitry. 
   The cassette handle may further comprise a spring and a switch trigger to actuate the switch, and maintain the switch trigger in a desired rest position. Preferably, the switch is in a closed condition unless a user has actuated the switch trigger. The switch trigger is preferably made of a non-conducting material to insulate the user from any potential electrical shock. The switch trigger preferably extends along the underneath side of the handle so that the trigger is moved to actuate the switch by a user&#39;s natural grasp of the handle. 
   Optionally, the chassis may further comprise an access cover. The access cover, when closed, prevents the cassette from being removed from the chassis. In one embodiment, the access cover may activate a switch that is physically adjacent the access cover and electronically in series within the chassis flex circuitry. Alternatively, the access cover may activate a switch that communicates directly with the controller. Accordingly, the controller may implement logic that ignores changes in the flex circuit when the access door is indicated as being closed, since no cassette may be either installed or removed if the access door is closed. This logic or circuit may prevent faulty wiring or false signals related to the flex circuit from inadvertently causing a cassette to shut down. 
   The apparatus operates to safely power down a second electronic circuit board during insertion or removal of the cassette including the board. The flex circuit, which includes the chassis flex circuitry and the cassette flex circuitry, is closed only when the cassette is properly secured to the chassis and the handle is not being grasped. Therefore, a closed flex circuit indicates that power should be provided to the one or more circuit boards associated with the cassette. It should be recognized that the chassis may be configured with multiple bays to receive multiple cassettes, in which case the chassis will preferably include separate chassis flex circuitry for each bay in order to independently control power from each bay to each cassette. 
   An open flex circuit indicates either that a cassette has not been fully received or, if the cassette has in fact been fully received and operational, that the user intends to remove the cassette. Therefore, an open flex circuit indicated that any data processing and transmission should be completed and halted. To do complete processing and transmissions, the second electronic circuit board (i.e., a PCI card) requests access to the data bus. Once the PCI card is granted permission by the bus, the PCI card completes its data transmissions so that no data is lost when the card loses power and it removed. When the controller identifies that the PCI card is quiescent, the card may be safely removed. Preferably, the system includes a fail safe warning feature by which a user is informed of the quiescent condition, such as through the use of a visual indicator light, indicating that the user may safely remove the card without data loss. 
   The following figures illustrate the apparatus in one embodiment of the invention as potentially implemented in the IBM Sundance D11 product. 
     FIG. 1  is a side view of a chassis  14  with a cassette  10  received and pivotally secured at a first end  12 . The chassis  14  houses a first electronic circuit board  17  with a first connector  18  to receive a second connector  16 . A second electronic circuit board (not shown) is secured by the cassette  10  and includes a second connector  16  having contacts for receiving power and handling communications. The cassette and chassis are selectively secured in a predetermined configuration to align the second connector  16  with the first connector  18 . The cassette comprises a handle  20  to lift or lower the cassette  10 . In  FIG. 1 , the cassette  10  is in an open or disconnected position, with the second connector  16  not yet received in the first connector  18 . 
     FIG. 2  is a side view of the chassis and cassette of  FIG. 1  with the cassette  10  in a closed or connected position. When the cassette  10  is properly closed as shown, the second connector  16  is received by the first connector  18  for electronic communication there between. The chassis  14  is also shown including a sliding access cover  21 . When the sliding access cover  21  is closed, the cassette  10  may not be raised into the open position by lifting the handle  20 . The sliding access cover  21  may have a pair of contacts (not shown) to selectively complete a circuit (not shown) within the chassis, optionally within the chassis flex circuitry, to indicate the position of the access door. 
     FIG. 3  is a perspective view of two cassettes  10  on a chassis  14  having six bays. Each cassette  10  has a second electronic circuit board  15  secured to the cassette. As shown, the second connector (see  FIG. 1 ) on each second electronic circuit board  15  has already been received into a first connector  18  (see  FIG. 1 ) on a first electronic circuit board of the chassis  14 . Each cassette  10  comprises a handle  20  having a switch trigger  22  that must be depressed prior to raising the cassette  10  into the open position (shown in  FIG. 1 ). The switch trigger  22  may also control a lock (now shown) that selectively secures the cassette  10  to the chassis  14 . 
     FIG. 4  is a lower perspective view of the two cassettes  10  received by the chassis  14 , in accordance with  FIG. 3 . Each handle  20  comprises a switch trigger  22  that must be depressed (upwardly in  FIG. 4 ) during installation and removal of the cassette  10  relative to the chassis. Each handle  20  further comprises cassette flex circuitry  30 . The cassette flex circuitry  30  has contacts  32  forming contacts that align with and engage opposing contacts  34  on the chassis. Depressing the switch trigger  22  activates a switch (not shown) that opens the circuit comprising the cassette flex circuitry  30 . 
     FIG. 5  is a lower perspective view in accordance with  FIG. 4 , but having the switch trigger (shown in  FIG. 4  as  22 ) removed to reveal further components. The handle  20  secures the cassette flex circuitry  30  that further comprises a switch  40 . The switch  40  selectively completes a circuit comprising the cassette flex circuitry  30  based upon whether the switch is actuated. In this embodiment, the switch  40  completes a circuit comprising the cassette flex circuitry  30  when depressed. A spring  42  in the handle  20  biases the switch trigger toward the switch  40  to normally maintain the switch  40  in the depressed position. Accordingly, the user upwardly depresses the switch trigger to release the switch  40  and break the circuit. The handle  20  also comprises a strut  44  to pivotally mount the switch trigger. 
     FIG. 6  is a lower rear perspective view of the cassette flex circuitry  30  in contact with the chassis flex circuitry  31  to form the completed flex circuit. The contacts  32  of the cassette flex circuitry  30  align with openings  34  on the chassis  14 . The chassis  14  comprises chassis flex circuitry  31  with contacts  33  that similarly align with the openings  34  so that contacts  33  make electrical contact with the contacts  32  of the cassette flex circuitry  30  to form a circuit. 
     FIG. 7  is a schematic diagram of one potential embodiment of the present invention. The switch trigger  22  is shown in the depressed position (depressed upward), with the switch  40  open to interrupt or break the circuit that includes the cassette flex circuitry  30 . The cassette flex circuitry  30  is in contact (at interface  34 ) with the chassis flex circuitry  31  via the contacts shown in  FIG. 6 . The chassis flex circuitry  31  is in electronic communication with a controller  50  having a first connection  56  to a power supply  52 , and a second connection  54  to the first connector  18 . The power supply  52  also has a third connection  58  to the first connector  18  for supplying electrical power. 
   When the cassette is fully received by the chassis and the user releases the switch trigger  22 , the switch  40  is depressed in the closed position. This completes a circuit comprising the cassette flex circuitry  30 , and the chassis flex circuitry  31 . The completed flex circuit indicates to the controller  50  that the second electronic circuit board (not shown) in the cassette has been received by the first connector  18 . In response to detecting the completed flex circuit, the controller  50  sends a signal to the power supply  52  to provide power to the first connector  18  through the third connection  58 . The second electronic circuit board with a second connector in the cassette then receives power through the first connector  18 . The controller may also send a signal to the first electronic circuit board or other components in order to initiate communications with the second electronic circuit board, such as the assignment of digital operations. 
   When the switch trigger  22  is again depressed or actuated by the user, the switch  40  is opened, breaking the circuit comprising the cassette flex circuitry  30  and the chassis flex circuitry  31 . The controller  50  may then take several actions. The controller  50  may instruct the first electronic circuit board  17 , via communication over the second connection  54  and through the first connector  18 , that the second electronic circuit board (not shown) will be removed, and that no further operations are to be assigned to the second electronic circuit board. The controller  50  or the first electronic circuit board  17  may also instruct the second electronic circuit board to complete any operations that are currently underway. Upon receiving a signal through the first connector  18  that the second electronic circuit board is quiescent, the controller  50  may instruct the power supply  52  via a first connection  56  to remove power from the first connector  18  via the third connection  58 . The user may be given an indication that the second electronic circuit board is quiescent through a signal sent from the controller  50  to a light emitting diode (LED)  60  on the handle  20 . Since the cassette will lose power after becoming quiescent, it might be that the user indication will be the LED going out. Alternatively, the LED could be disposed on the chassis, since the chassis will presumably continue to have power. The user may then lift the handle  20  to disconnect the cassette from the chassis, thereby removing the second connector (not shown) from the first connector  18 . 
   In this embodiment, completing the flex circuit comprising the cassette flex circuitry  30  and the chassis flex circuitry  31  by properly closing the cassette  10  and depressing the switch  40  indicates to the controller  50  that power may be supplied to the first connector  18  and processing operations may be assigned to components on the first electronic circuit board. When the flex circuit comprising the cassette flex circuitry  30  and the chassis flex circuitry  31  is broken, the controller  50  may undertake the operations described above to reach a quiescent state in the first electronic circuit board and halt power to the first connector  18 . 
   The terms “comprising,” “including,” and “having,” as used in the claims and specification herein, shall be considered as indicating an open group that may include other elements not specified. The terms “a,” “an,” and the singular forms of words shall be taken to include the plural form of the same words, such that the terms mean that one or more of something is provided. The term “one” or “single” may be used to indicate that one and only one of something is intended. Similarly, other specific integer values, such as “two,” may be used when a specific number of things is intended. The terms “preferably,” “preferred,” “prefer,” “optionally,” “may,” and similar terms are used to indicate that an item, condition or step being referred to is an optional (not required) feature of the invention. 
   While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims.