Abstract:
A method of improving readability in an optical drive is disclosed. In one aspect, the present disclosure teaches a method of improving readability in an optical drive including monitoring a compact disc (CD) media for tracking errors using a differential push-pull (DPP) method during an input/output (I/O) operation in an optical drive. The method further includes determining whether the first a tracking error is above a predetermined error threshold, or if a read error has occurred. The occurrence of a read error or tracking error, the method further includes switching from the DPP method to a three-beam tracking method based on the determination.

Description:
TECHNICAL FIELD  
       [0001]     The present disclosure relates generally to information handling systems and, more particularly, to a method of improving readability in an optical drive.  
       BACKGROUND  
       [0002]     As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.  
         [0003]     A computer system is one type of information handling system. Examples of computer systems include servers, personal computers, notebook and laptop computers, workstations and personal digital assistants. Typically, the computer system includes a processor, memory, a display, a keyboard, hard disk storage and one or more input/output (“I/O”) devices, such as a floppy drive or an optical drive. Examples of optical drives include compact disc (CD), CD-read only media (CD-ROM), CD-read (CD-R), CD-read write (CD-RW), digital versatile disc (DVD), DVD-ROM, DVD-R, DVD-RW and combinations there of (e.g., CD-RW/DVD drive).  
         [0004]     Generally, these optical drives read and may write information to/from compact disc (CD) media. During read operations, the CD media is usually placed inside the drive such that a focused light or laser reflects off pits formed in a groove on the CD media as the CD revolves around a spindle in the drive. These reflected light beams are then translated into an electrical signal to form computer-readable information. Because the computer-readable information depends on the reflections from the pits on the CD media, the drive must be able to track the groove on the media in order to read the media.  
         [0005]     To track the groove, optical drives typically employ different tracking methods such as a differential push-pull (DPP) method, differential phase detection or a three-beam tracking method. Of these methods, it is preferable to use the DPP method for recordable CD media. However, the DPP method does not perform well with stamped CD media that has a low reflectivity and pit depths deeper than allowed by a CD media specification. As such the stamped CD media has a lower signal-to-noise ratio and a weak contrast that causes the drive to move off track. When the drive moves off-track, an error typically occurs that causes the read of the CD media to fail.  
       SUMMARY  
       [0006]     Thus, a need has arisen for a method of improving readability in an optical drive.  
         [0007]     In accordance with teachings of the present disclosure, in one embodiment, a method of improving readability in an optical drive including monitoring a compact disc (CD) media for tracking errors using a differential push-pull (DPP) method during an input/output (I/O) operation in an optical drive. The method further includes determining whether the first tracking error is above a predetermined error threshold, upon the occurrence of a first tracking error. The method further includes switching from the DPP method to a three-beam tracking method based on the determination.  
         [0008]     In other embodiments, an information handling system including a processor and memory operably coupled to the processor. The information handling system further includes an optical drive communicatively coupled to the processor. The optical drive operable to perform input/output operations. The information handling system further includes an optical tracking system forming a part of the I/O operations. The optical tracking system operable to follow a track on a compact disc (CD) placed in the optical drive. The optical tracking system including a center beam operable to read information on the track. The optical tracking system further including tracking beams operably set between a centerline of adjacent tracks and an edge of the track.  
         [0009]     In further embodiments, a system for improving readability in an optical drive including an optical drive operable to perform input/output operations. The optical drive including an optical tracking system. The optical tracking system operable to follow a track on a compact disc (CD) placed in the optical drive. The optical tracking system including a center beam operable to read information on the track. The optical tracking system further includes tracking beams having modified beam angles that are operably set between a centerline of adjacent tracks and an edge of the track, wherein the tracking beams are operably set to switch between a differential push-pull (DPP) tracking method and a three-beam tracking method.  
         [0010]     In one aspect, teachings of the present disclosure provide the technical advantage of selectively switching between two different tracking methods. Because the tracking beams are at modified angles, photo detectors are able to track the CD using either method. Therefore, if a default method is unable to read a certain part of the CD media, the optical drive may selectively switch to an alternative tracking method.  
         [0011]     All, some, or none of these technical advantages may be present in various embodiments of the present invention. Other technical advantages will be apparent to one skilled in the art from the following figures, descriptions, and claims.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     A more complete understanding of the present embodiments and advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings, in which like reference numbers indicate like features, and wherein:  
         [0013]      FIG. 1  is a block diagram showing an information handling system, according to teachings of the present disclosure;  
         [0014]      FIG. 2  illustrates an example embodiment of an optical drive that forms a part of an information handling system, according to teachings of the present disclosure;  
         [0015]      FIG. 3  illustrates an example embodiment of an optical tracking system using tracking beams with modified beam angles, according to teachings of the present disclosure; and  
         [0016]      FIG. 4  is a flowchart for a method of improving readability in an optical drive, according to teachings of the present disclosure.  
     
    
     DETAILED DESCRIPTION  
       [0017]     Preferred embodiments and their advantages are best understood by reference to  FIGS. 1 through 4 , wherein like numbers are used to indicate like and corresponding parts.  
         [0018]     For purposes of this disclosure, an information handling system may include any instrumentality or aggregate of instrumentalities operable to compute, classify, process, transmit, receive, retrieve, originate, switch, store, display, manifest, detect, record, reproduce, handle, or utilize any form of information, intelligence, or data for business, scientific, control, or other purposes. For example, an information handling system may be a personal computer, a network storage device, or any other suitable device and may vary in size, shape, performance, functionality, and price. The information handling system may include random access memory (RAM), one or more processing resources such as a central processing unit (CPU) or hardware or software control logic, ROM, and/or other types of nonvolatile memory. Additional components of the information handling system may include one or more disk drives, one or more network ports for communicating with external devices as well as various input and output (I/O) devices, such as a keyboard, a mouse, and a video display. The information handling system may also include one or more buses operable to transmit communications between the various hardware components.  
         [0019]     Referring first to  FIG. 1 , a block diagram of information handling system  10  is shown, according to teachings of the present disclosure. Information handling system  10  or computer system preferably includes at least one microprocessor or central processing unit (CPU)  12 . CPU  12  may include processor  14  for handling integer operations and coprocessor  16  for handling floating point operations. CPU  12  is preferably coupled to cache  18  and memory controller  20  via CPU bus  22 . System controller I/O trap  24  preferably couples CPU bus  22  to local bus  26  and may be generally characterized as part of a system controller.  
         [0020]     Main memory  28  of dynamic random access memory (DRAM) modules is preferably coupled to CPU bus  22  by a memory controller  20 . Main memory  28  may be divided into one or more areas such as system management mode (SMM) memory area (not expressly shown).  
         [0021]     Basic input/output system (BIOS) memory  30  is also preferably coupled to local bus  26 . FLASH memory or other nonvolatile memory may be used as BIOS memory  30 . A BIOS program (not expressly shown) is typically stored in BIOS memory  30 . The BIOS program preferably includes software which facilitates interaction with and between information handling system  10  devices such as a keyboard (not expressly shown), a mouse (not expressly shown), or one or more I/O devices. BIOS memory  30  may also store system code (note expressly shown) operable to control a plurality of basic information handling system  10  operations.  
         [0022]     Graphics controller  32  is preferably coupled to local bus  26  and to video memory  34 . Video memory  34  is preferably operable to store information to be displayed on one or more display panels  36 . Display panel  36  may be an active matrix or passive matrix liquid crystal display (LCD), a cathode ray tube (CRT) display or other display technology. In selected applications, uses or instances, graphics controller  32  may also be coupled to an integrated display, such as in a portable information handling system implementation.  
         [0023]     Bus interface controller or expansion bus controller  38  preferably couples local bus  26  to expansion bus  40 . In one embodiment, expansion bus  40  may be configured as an Industry Standard Architecture (“ISA”) bus. Other buses, for example, a Peripheral Component Interconnect (“PCI”) bus, may also be used.  
         [0024]     In certain information handling system embodiments, expansion card controller  42  may also be included and is preferably coupled to expansion bus  40  as shown. Expansion card controller  42  is preferably coupled to a plurality of information handling system expansion slots  44 . Expansion slots  44  may be configured to receive one or more computer components  80  (shown below in more detail) such as an expansion card (e.g., modems, fax cards, communications cards, and other input/output (I/O) devices).  
         [0025]     Interrupt request generator  46  is also preferably coupled to expansion bus  40 . Interrupt request generator  46  is preferably operable to issue an interrupt service request over a predetermined interrupt request line in response to receipt of a request to issue interrupt instruction from CPU  12 .  
         [0026]     I/O controller  48 , often referred to as a super I/O controller, is also preferably coupled to expansion bus  40 . I/O controller  48  preferably interfaces to an integrated drive electronics (IDE) hard drive device (HDD)  50 , CD-ROM (compact disk-read only memory) drive  52  and/or a floppy disk drive (FDD)  54 . Other disk drive devices (not expressly shown) which may be interfaced to the I/O controller include a removable hard drive, a zip drive, a CD-RW (compact disk-read/write) drive, and a CD-DVD (compact disk-digital versatile disk) drive.  
         [0027]     Communication controller  56  is preferably provided and enables information handling system  10  to communicate with communication network  58 , e.g., an Ethernet network. Communication network  58  may include a local area network (LAN), wide area network (WAN), Internet, Intranet, wireless broadband or the like. Communication controller  56  may be employed to form a network interface for communicating with other information handling systems (not expressly shown) coupled to communication network  58 .  
         [0028]     As illustrated, information handling system  10  preferably includes power supply  60 , which provides power to the many components and/or devices that form information handling system  10 . Power supply  60  may be a rechargeable battery, such as a nickel metal hydride (“NiMH”) or lithium ion battery, when information handling system  10  is embodied as a portable or notebook computer, an A/C (alternating current) power source, an uninterruptible power supply (UPS) or other power source.  
         [0029]     Power supply  60  is preferably coupled to power management microcontroller  62 . Power management microcontroller  62  preferably controls the distribution of power from power supply  60 . More specifically, power management microcontroller  62  preferably includes power output  64  coupled to main power plane  66  which may supply power to CPU  12  as well as other information handling system components. Power management microcontroller  62  may also be coupled to a power plane (not expressly shown) operable to supply power to an integrated panel display (not expressly shown), as well as to additional power delivery planes preferably included in information handling system  10 .  
         [0030]     Power management microcontroller  62  preferably monitors a charge level of an attached battery or UPS to determine when and when not to charge the battery or UPS. Power management microcontroller  62  is preferably also coupled to main power switch  68 , which the user may actuate to turn information handling system  10  on and off. While power management microcontroller  62  powers down one or more portions or components of information handling system  10 , e.g., CPU  12 , display  36 , or HDD  50 , etc., when not in use to conserve power, power management microcontroller  62  itself is preferably substantially always coupled to a source of power, preferably power supply  60 .  
         [0031]     Computer system, a type of information handling system  10 , may also include power management chip set  72 . Power management chip set  72  is preferably coupled to CPU  12  via local bus  26  so that power management chip set  72  may receive power management and control commands from CPU  12 . Power management chip set  72  is preferably connected to a plurality of individual power planes operable to supply power to respective components of information handling system  10 , e.g., HDD  50 , FDD  54 , etc. In this manner, power management chip set  72  preferably acts under the direction of CPU  12  to control the power supplied to the various power planes and components of a system.  
         [0032]     Real-time clock (RTC)  74  may also be coupled to I/O controller  48  and power management chip set  72 . Inclusion of RTC  74  permits timed events or alarms to be transmitted to power management chip set  72 . Real-time clock  74  may be programmed to generate an alarm signal at a predetermined time as well as to perform other operations.  
         [0033]     Information handling system  10  is typically includes chassis  70 . Generally, chassis  70  is referred to as the computer case or case that encloses the components of information handling system  10 . However, some components such as CD  52 , floppy  54  and HDD  50 , may be separately connected to information handling system  10  and may be referred to as an external component. Generally, CD  52  refers to a variety of optical drives that may be used for I/O access to information handling system  10 . By improving the readability of the optical drives, information handling system  10  may be able to access additional information stored on CD media  94 .  
         [0034]     Referring to  FIG. 2 , optical drive  100  may form a part of information handling system  10 . Optical drive  100  may vary depending on the type of optical media  94  that is used with the drive. For example, a compact disk (“CD”) drive may only read data from optical media  24  such as a CD-ROM (CD-read only memory). However, if a user desires to have both read and write capabilities, another type of optical drive  100  may be used such as a CD-RW drive that has the capabilities to read from and write to certain optical media such as a CD-R or a CD-RW. Other types of optical drive  100  may use different types of optical media  94 . Examples of optical media  94  include a digital video disk (“DVD”), DVD-R, DVD-RW, and any other media suitable for use in optical drive  100 .  
         [0035]     Optical drive  100  may include chipset  80  that may form part or all of the control circuitry for the operation of optical drive  100 . As such, chipset  80  may contain a variety of electrical components such as controls for a laser lens system, disk drive mechanism controls, signal processing modules (not expressly shown) and optical tracking system  82 .  
         [0036]     Chipset  80  may also control and provide electrical power to light source  86  using light source connection  84  via optical tracking system  82 . For example, light source  86  may be a laser diode such as a low power laser diode that emits a laser able to focus on optical media  94  via mirror  90  in order to read/write data from optical media  94  during an I/O operation. Generally, light source  86  emits the light along light path  88  towards mirror  90 .  
         [0037]     Mirror  90  typically forms a part of a lens system within optical drive  100  that enables the light to focus on optical media  94 . Generally, the lens system includes objective lens  91  that focuses the reflected light onto CD media  94 . Additionally, the lens system may include collimator lens  92  operable to gather light from light source  86  and convert the light into parallel light that can focus on CD media  94 .  
         [0038]     Generally, mirror  90  includes a polarized mirrored surface that is able to reflect a large percentage of the light toward optical media  94 . The light reflected off of optical media  94  may be reflected back reflected path  88  such that the light passes through the polarized mirrored surface and is detected by photodiode  96 .  
         [0039]     Photo detector such as photodiode  96  typically forms a part of an optical pick-up mechanism in optical drive  100 . Examples of photodiode  96  include any type of photodiode, photoelectric semiconductor device, or light detecting and/or measuring device that is able to convert radiant energy, such as light, into electrical energy. For instance, the light that is detected by photodiode  96  may be converted into an electrical signal that is proportional to the amount of detected light. Generally, the amount of detected light may be measured using the amplitude or the electrical signal.  
         [0040]     Photodiode  96  may be used to detect the light from light source  16  and may be used to detect light reflected off of optical media  94 , which may be used to read data from optical media  94 . Typically, the reflected light, which may be reflected from the pits  113  and lands  112  (described below in more detail) present on optical media  94 , may be received as pulses of light. After photodiode  96  detects this light, photodiode  96  may generate a signal proportional to the light that may be sent to chipset  80  via signal path  95 . At chipset  80 , the signal may be decoded and redirected to information handling system  10  or any other type of output such as an audio or video output.  
         [0041]      FIG. 3  illustrates an example embodiment of an optical tracking system  100  using tracking beams  122  with modified beam angles on a section of CD media  94 . Focusing light  88  from light source  86  onto CD media  94  typically includes center beam  120  and one or more tracking beams  122 . Center beam  120  is used to focus on pits  113  and lands  112  of a track on CD media  94 .  
         [0042]     In the example embodiment, the section of CD media  94  has five tracks, namely tracks  101 ,  102 ,  103 ,  104  and  105 . Typically, tracks  101 - 105  spiral around CD media such that track  101  ends at the beginning of track  102 . However, in alternate embodiments, tracks  101 - 105  are separate tracks that are not spiral around CD media  94 .  
         [0043]     As illustrated, center beam  120  is focused on track  103 . Track  103  may be viewed as having a groove  110  that includes pits  113  and lands  112  bordered by lanes  114 . Center beam  120  is set over groove  110  on track  103  such that the reflected light may be read by photodiode  96 . Side beams or tracking beams  122  are set at modified beam angles that permit optical tracking system  80  to use either a differential push-pull (DPP) tracking method or a three-beam tracking method.  
         [0044]     Generally, when using the DPP tracking method, DPP tracking beams are set over grooves  110  of adjacent tracks such as track  102  and  104 . Alternatively, when using the three-beam tracking method, three-beam tracking beams are set over lanes  114  of the adjacent tracks, namely tracks  102  and  104 . Because each method has set their respective tracking beams at different locations, optical drive  100  generally selects one of the tracking methods and sets the beams accordingly.  
         [0045]     Setting tracking beams  122  at modified angles between lanes  114  and groove  110  of the adjacent tracks, optical tracking system  100  may use either tracking method. As illustrated, tracking beams  122  are set outside of track  103 , where center beam  120  is reading pits  113  and lands  112 , and into adjacent tracks (e.g., tracks  102  and  104 ). In one embodiment, tracking beams  122  are placed approximately halfway between lane  114  and groove  110  of the respective track, which allow either method to track CD media  94 .  
         [0046]      FIG. 4  is a flowchart for a method of improving readability in optical drive  100 . At block  130 , tracking system  80  monitors CD media  94  for tracking errors using a DPP tracking method. In some embodiments, the DPP tracking method is set as the default tracking method. Upon the occurrence of a tracking error at block  132 , tracking system  80  measures the level of error.  
         [0047]     Typically, the level of error is measured as compared to a predefined error threshold. The predefined error threshold may be selected based on a minimal level of electrical signal required to read the tracking signal. In one instance, the tracking error is based an amplitude of the electrical signal measured at the occurrence of the tracking error.  
         [0048]     At block  134 , the amplitude or other measured level of tracking error is compared to the predefined error threshold. If the measured tracking error is greater than the predetermined error threshold, optical drive  100  may return to block  130  and continue reading CD media  94  such as re-reading the particular location where the error occurred. However, if the measured tracking error falls below the predefined error threshold, optical tracking system  80  may switch to a three-beam tracking method at block  136 .  
         [0049]     For example, if the measured tracking error is based on measured amplitude of the electrical signal, the amplitude must be less than the predetermined error threshold to switch to the three-beam method. To that end, tracking system  80  may continue use the DPP tracking method if the amplitude is sufficiently high compared to the predetermined error threshold. However, tracking system  80  may switch to the three-beam tracking system if the amplitude is relatively low.  
         [0050]     Based on using the three-beam tracking method, tracking system  80  monitors CD media  94  for tracking errors at block  138 . If the tracking system  80  determines that additional tracking errors have occurred using the three-beam tracking method at block  140 , tracking system  80  may cause the I/O operation to fail (e.g., the read operation stops), at block  142 . Typically, when an I/O operation is stopped, a notification is sent to a user to inform that the error has occurred and that the I/O operation has failed. In some instances, the failure of the I/O operation is based on a first and second tracking error occurring at approximately the same particular location on CD media  94 .  
         [0051]     Although the disclosed embodiments have been described in detail, it should be understood that various changes, substitutions and alterations can be made to the embodiments without departing from their spirit and scope.