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REMOVABLE MEDIA EJECTION SYSTEM
CROSS-REFERENCE TO RELATED
This application is a divisional application of prior U.S. patent application Ser. No. 08/367,065 filed on Dec. 30, 1994, now U.S. Pat. No. 5,818,182, which is a continuationin-part (CIP) of U.S. patent application Ser. No. 08/107,185 filed Aug. 13, 1993, now U.S. Pat. No. 5,466,166, the 1Q disclosures of which are hereby incorporated by reference, entitled "PCMCIA Card Ejection Mechanism", and assigned to the assignee of the present invention, said patent application being incorporated herein by reference in its entirety for all purposes.
BACKGROUND OF THE INVENTION
This invention relates generally to computer peripherals, and more particularly to digital mass storage devices having removable storage media. 20
Computer systems and other digital processing systems often include digital memory "peripherals" used for the mass storage of data, Examples of such digital memory peripherals include hard disk drives, floppy disk drives, optical disk drives, and Personal Computer Memory Card 25 International Association (PCMCIA) cards or devices (also referred to as PC Cards) or other types "flash" memory cards. With some of these peripherals, the storage medium is permanently housed within and forms a part of the peripheral. An example of digital storage peripheral which 30 does not allow the removal of its storage medium is a standard Winchester-type hard disk drive. Other memory peripherals allow the removal and replacement of the digital media. Examples of such peripherals include floppy disk drives and PCMCIA peripheral units.
For most types of storage peripherals with removable media, the media is manually inserted into a slot against spring pressure until a latching mechanism is engaged. In many types of such peripheral units, the media is disengaged from the unit by manually depressing a release button or lever to release the latch and thereby allow the compressed spring to partially eject the storage medium. A protruding end of the medium is then removed from the peripheral unit by hand.
In some computer systems, notably the Macintosh® computer system made by Apple Computer, Inc. of Cupertino, Calif., removable storage media can be automatically ejected by the computer system. More particularly, the Macintosh operating system can cause motors or electrical 50 solenoids of the floppy drive unit to automatically eject a floppy disk.
Such automatic ejection of storage media has several advantages. For one, the computer can prevent the ejection of a floppy disk from the floppy disk drive if the system still 55 needs or is processing data in conjunction with the floppy disk drive. Another advantage is that the floppy disk can be ejected automatically under certain conditions, such as during a power-down or power-up of the computer system. However, such automatic ejection systems have the disad- go vantage of increasing the cost of the floppy disk drive in that motors or solenoids must be provided, along with their attendant control circuitry.
An increasingly popular form of removable media is the PCMCIA memory card, which is typically a form of "flash" 65 memory. As is well known to those skilled in the art, flash memory is form of non-volatile, solid-state, read-write
memory, and PCMCIA cards are flash memory which conform to certain industry standards. Since PCMCIAcards are, themselves, quite small, and since they do not require drive motors or the like (as the case with disk drives) the PCMCIA peripheral unit can be made quite small and lightweight. This makes PCMCIA peripheral units quite attractive for small computers, such as laptop computers, Personal Digital Assistants (PDAs) such at the Newton® PDA, and other small, portable devices utilizing digital processors.
PCMCIA cards can be of other types than the aforementioned flash memory type. For example, there are PCMCIA cards which employ Static Random Access Memory (SRAM) and PCMCIA cards that are miniature hard disk drives. In addition, PCMCIA cards can include modem, cellular pager, and networking capabilities. The PCMCIA format is therefore quite flexible and is rapidly growing in popularity.
For a variety of reasons, in the past, PCMCIA peripheral units only permitted the manual ejection of the PCMCIA cards . For one, the addition of motors or solenoids to eject the PCMCIA card would substantially increase the size of the PCMCIA peripheral unit, which is considered very undesirable. For another, the motor or solenoid would add a significant cost to the PCMCIA peripheral unit.
SUMMARY OF THE INVENTION
The present invention includes a system and method for the automatic ejection of media. More particularly, the present invention includes a system and method for the automatic ejection of PCMCIAcards from PCMCIA peripheral units. This is accomplished using an electricallycontrolled "memory wire" to eject a PCMCIA card without the use of motors or solenoids.
A memory wire control system in accordance with the present invention includes elongated memory wire and a pulse width modulator for controlling the electric current flowing through the wire. The electric current heats the wire, causing a dimensional change in the wire that can be used, for example, to release a catch on a PCMCIA peripheral unit to eject a PCMCIA card. The memory wire is preferably a bimetallic alloy comprising nickel and titanium, commonly known by the generic tradename Nitinol. The pulse width modulator is preferably computer controlled so that dimensional changes in the memory wire can be under software control.
A media ejection system of the present invention includes a peripheral unit having a housing receptive to removable medium, an ejection mechanism for ejecting the medium, and a memory wire coupled to the ejection mechanism. The system also includes a digital processor operative to issue a ejection command, and a controller responsive to the ejection command for controlling current flow in the memory wire of the peripheral unit. When the ejection command is received, current flows through the memory wire, causing it to contract, and thereby activating the ejection mechanism of the peripheral unit.
A method for ejecting a removable medium in accordance with the present invention includes the steps of: a) receiving a ejection request; b) issuing a ejection command in response to the ejection request, where the ejection command includes control parameters for a current that is to flow through a memory alloy; and c) passing an electrical current through the memory alloy in accordance with the control parameters so that the memory alloy undergoes a dimensional change to activate a removable medium ejection mechanism. Preferably, the method is computer
implemented, and the step of energizing the memory alloy includes applying a pulse width modulated signal to the metal alloy in accordance with the parameters. Also preferably, the parameters included at least one of a duty cycle and a frequency for the pulse width modulated signal. 5
Since a memory wire or other memory or bimetallic alloy is used to activate the ejection mechanism of the peripheral, the need for motors, solenoids, or other electromagnetic actuators has been eliminated. This greatly reduces the cost of a peripheral unit having an automatic ejection mecha- 1° nism. Furthermore, the memory wire does not increase the size of the peripheral unit, which is very desirable in view of the increasing miniaturization of computer systems.
These and other advantages of the present invention will become apparent to those skilled in the art upon a reading of 15 the following descriptions of the invention and a study of the several figures of the drawing.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a housing for a PCMCIA peripheral unit in accordance with the present invention;
FIG. 2 is a block diagram of a computer system with a digital storage peripheral unit in accordance with the present invention; 25
FIG. 3 is a schematic of the ejection controller 50 of FIG.
FIG. 3A is a diagram of a pulse width modulated (PWM) signal that can be applied to the memory wire of the present invention; 30
FIG. 4 is a flow diagram of the computer implemented process of the present invention;
FIG. 5 is a flow diagram of the illustrating the "performed eject sequence" step of FIG. 4 in greater detail; and ^
FIG. 5A is an illustration of various programmable registers used by the present invention.
DETAILED DESCRIPTION OF THE
In FIG. 1, a PCMCIA peripheral unit 10 in accordance with the present invention includes a housing 12, an ejection mechanism indicated generally at 14, and memory wires 16Aand 16B. The peripheral unit 10 also include other parts well known to those skilled in the art, such as a male 45 connector (not shown) which engages a female connector provided at one end of a PCMCIA card (not shown). A complete description of the housing 12 and ejection mechanism 14 for the peripheral unit 10 can be found in copending U.S. patent application Ser. No. 08/107,185, the disclosure 50 of which has been incorporated herein by reference.
The housing 12 is elongated, rectangular, box-like structure which is capable of simultaneously receiving two PCMCIA cards. A first card may be engaged with a slot 18 of housing 12, and a second card may be engaged with a slot 55 20 of housing 12. The two PCMCIA cards (not shown) can be inserted and ejected from the housing 12 separately or simultaneously by the ejection mechanism 14. To eject a PCMCIA card from slot 18, an eject button 22 is pressed, and to eject PCMCIA card from slot 20 a button 24 is 60 pressed. Both of the PCMCIA cards can ejected simultaneously by pressing the buttons 22 and 24 at the same time. The buttons 22 and 24 are coupled to the ejection mechanism 14 by unlatch bars 26 and 28, respectively, which slide longitudinally within the housing 12. 65
Memory wires 16A and 16B of the peripheral unit 10 allow for an automated, software-controlled ejection of
PCMCIA cards from slots 18 and 20, respectively. Memory wires 16A and 16B are made from a material exhibiting "shape memory effect", which was first noted over 50 years ago. Preferably, the memory wires 16A and 16b are made from an essentially bi-metallic alloy comprising nickel and titanium, under such trademarks as FlexinolTM by Dynalloy, Inc. of Irvine Calif, or under the generic tradename Nitinol by a number of vendors. The memory wires 16A or 16B of the present invention are approximately 8.4 centimeters long, and have an intrinsic, end-to-end resistance of 1.4 ohms.
Because the memory wires have an intrinsic resistance, a dimensional change in the memory wires 16A and 16B can be made by passing a current though the wires, thereby causing them to heat to degree sufficient to cause a significant contraction of the wire. In other words, the intrinsic resistances of the memory wires 16A and 16B are used as resistance heaters to cause the wires to shrink and to thereby selectively activate the ejection mechanism 14.
Preferably, the memory wires 16A and 16B are anchored at one end to flanges (such as flange 30) of the unlatched bars 26 and 28, respectively, by anchors 32 and 34, respectively, the other end of the memory wire 16 are anchored to a fixed portion of the housing 12. In the present invention, the anchors 32 and 34 are conductive and couple ends of the memory wires 16A and 16B to ground. The anchors going to the fixed portion of the housing should electrically insulate the other ends of the memory wires, such that they are not grounded.
When currents are passed through the memory wires 16A and 16B, their contraction pulls unlatch bars 26 and 28, respectively, towards the ejection mechanism 14, thereby activating the ejection mechanism 14 in the same manner as if the button 22 or 24 respectively, had been pressed. The wires can also be provided in other releasing configurations, such as in a configuration where it pulls directly on a latch plate of the ejection mechanism 14, or where it pulls a wedge between a pair of latch plates of the ejection mechanism 14.
Preferably, first end portions of the wires 16A and 16B are electrically coupled to ground by means of the grounded, metal unlatch bars 26 and 28, respectively, and the other end portions of the wires 16A and 16B (which are not grounded) are connected to control circuitry by wires 36 and 38, respectively. It should be noted that the point of electrical contact between the wires 16A and 16B are preferably at, or approximate to, its two ends. However, alternate embodiments of the present invention may have coupling points located at some distance from the two ends such that only a more central portion of the wire is electrically heated.
In FIG. 2, a digital computer system 40 is shown attached the PCMCIA peripheral unit 10. The digital computer system 40 includes a microprocessor 42, Random Access Memory (RAM) 44, Read Only Memory (ROM) 46, an Application Specific Integrated Circuit (ASIC) 48, and an ejection controller 50. The majority of the components of the computer system 40 communicate with each other, either directly or indirectly, by means of a system bus 52, as is well known to those skilled in the art.
The microprocessor 42, RAM 44, and RAM 46 operate in a conventional manner which need not be described herein. The ASIC 48 (which is often referred to as "chip set") provides much of the functionality of the computer 40 as far as providing control signals for RAM 44 and ROM 46, peripheral control signals for the peripheral unit 10, etc. In the present invention the ASIC 48 includes four registers 54 that store parameters used to control the current flowing