Abstract:
A method and apparatus for modifying scheduled recordings when a scheduled recording entered by a user overlaps in time with one or more pre-stored scheduled recordings is disclosed. If a channel and recording duration for a new scheduled recording is entered by a user, it is determined if the duration of the new scheduled recording overlaps with one or more pre-stored scheduled recordings. If it is determined that there is a conflict, the user is automatically notified of the scheduled recording that overlaps in time with the newly entered scheduled recording, the overlapping scheduled recording is modified based on user input responsive to the notification, and the newly entered scheduled recording is added to the list of scheduled recordings, or if the user chooses to keep the pre-stored scheduled recording, the newly entered scheduled recording is modified or deleted.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     This application claims priority to Korean Patent Application No. 10-2004-0104826 filed Dec. 13, 2004. The disclosures of the previous applications are incorporated by reference herein.  
         [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a method and apparatus for a recording, a recording device, and more particularly, a method and apparatus for modifying scheduled recordings by a recording device.  
         [0004]     2. Description of the Related Art  
         [0005]     As the number of available TV channels increases, viewers use the scheduled recording capability of their recording apparatus frequently. Scheduled recording allows a program to be recorded between start and stop times on defined date and time so that the viewer can later watch the recorded program. In many cases, the mode of a scheduled recording, and a recording session begins automatically each time the specified time on the day of week set by the viewer is reached so that the program broadcast on a selected channel is recorded.  
         [0006]     In some cases, the program that is broadcast regularly is replaced by a special program, e.g., a sport event, and instead of the user-set scheduled recording entries of the recording apparatus, the user may want to record the special program on another channel. When the user enters a one-time scheduled recording entry for recording a program on another channel, the one-time scheduled recording session may partly overlap in time with one or more pre-stored scheduled recording sessions. Once such a conflict occurs, the user is prevented from storing the new scheduled recording without modifying the pre-stored scheduled recording. The process for modifying previous entries and entering new entries is complicated, inconvenient and time consuming.  
       SUMMARY OF THE INVENTION  
       [0007]     An object of the invention is to solve at least the above problems and/or disadvantages and to provide at least the advantages described hereinafter.  
         [0008]     In view of the shortcomings stated above, it is an object of the present invention to provide a method and apparatus for allowing users to easily resolve a recording schedule conflict caused when a new scheduled recording entry, which overlaps in time with some of pre-stored scheduled recordings, is entered.  
         [0009]     The method for modifying scheduled recordings in accordance with the present invention determines if the recording duration of a scheduled recording that has been just entered by a user overlaps with the recording duration of a preset scheduled recording, accepts the just entered scheduled recording even if there is an overlap, and modified the preset scheduled recording based on input information received after storing the just entered scheduled recording.  
         [0010]     In one embodiment, the preset scheduled recording is modified based on user input while the just entered scheduled recording is stored as valid information.  
         [0011]     In another embodiment, the preset scheduled recording is modified automatically while the just entered scheduled recording is stored as valid information.  
         [0012]     The objects and/or advantages can be achieved in a whole or in parts by a method for modifying scheduled recordings, comprising (a) determining if a recording duration of an entered scheduled recording overlaps with a recording duration of a preset scheduled recording, and (b) modifying the present scheduled recording based on input information while setting up the entered scheduled recording, if it is determined that there is an overlap in the step (a). If it is determined that there is an overlap in the step (a), the step (b) outputs a screen for receiving user input to modify the present scheduled recording and receives information through the screen, the screen being outputted automatically with no extra user input. Step (b) does not accept the entered scheduled recording as valid information if no modification is made to the present scheduled recording through the screen.  
         [0013]     The objects and/or advantages can be achieved in a whole or in parts by a method for modifying scheduled recordings, comprising determining if a recording duration of an entered scheduled recording overlaps with a recording duration of a present scheduled recording, and modifying the present scheduled recording automatically while setting up the entered scheduled recording, if it is determined that there is an overlap in the step (a). If it is determined that there is an overlap in the step (a), the step (b) outputs a screen for querying whether to accept the entered scheduled recording with the present scheduled recording and modifies the preset scheduled recording automatically while setting up the entered scheduled recording if a request for accepting the entered scheduled recording is received, the screen being outputted automatically with no extra user input. Step (b) does not accept the entered scheduled recording as valid information if a request for canceling the entered scheduled recording is received. Step (b) modifies recording date of the present scheduled recording automatically. Step (b) automatically changes the recording date of the present scheduled recording to the next day if recording mode of the preset scheduled recording is set to daily recording. Step (b) automatically changes the recording date of the preset scheduled recording to the date of 7 days later if recording mode of the preset scheduled recording is set to weekly recording.  
         [0014]     The objects and/or advantages can be achieved in a whole or in parts by an apparatus for recording/reproducing video signals, comprising a storage unit for storing scheduled recordings set by a user, and a control unit for determining if a recording duration of an entered scheduled recording overlaps with a recording duration of a preset scheduled recording stored in the storage unit and modifying the preset scheduled recording based on input information while storing the entered scheduled recording in the storage unit, if it is determined that there is an overlap. If it is determined that there is an overlap, the control unit outputs a screen for receiving user input to modify the preset scheduled recording and receives information through the screen, the screen being outputted automatically with no extra user input.  
         [0015]     The objects and/or advantages can be achieved in a whole or in parts by an apparatus for recording/reproducing video signals, comprising a storage unit for storing scheduled recordings set by a user, and a control unit for determining if a recording duration of an entered scheduled recording overlaps with a recording duration of a present scheduled recording stored in the storage unit and modifying the preset scheduled recording automatically while storing the entered scheduled recording in the storage unit, if it is determined that there is an overlap.  
         [0016]     If it is determined that there is an overlap, the control unit outputs a screen for querying whether to accept the entered scheduled recording with the preset scheduled recordings and modifies the preset scheduled recordings automatically while storing the entered scheduled recording in the storage unit, the screen being outputted automatically with no extra user input. The control unit automatically changes the recording date of the preset scheduled recording to the next day if a recording mode of the preset scheduled recording is set to daily recording. The control unit automatically changes the recording date of the preset scheduled recording to the date of 7 days later if a recording mode of the preset scheduled recording is set to weekly recording.  
         [0017]     The objects and/or advantages can be achieved in a whole or in parts by a method for modifying scheduled recordings by a recording device, comprising, determining if a recording duration of new scheduled recording conflicts with a recording duration of preset scheduled recording, accepting the new scheduled recording by the recording device even if a conflict exists with the recording duration of at least one preset scheduling recording, and allowing at least one modification to at least one conflicting scheduled recording based on input information after the recording device stores the new scheduled recording.  
         [0018]     The objects and/or advantages can be achieved in a whole or in parts by a method for modifying scheduled recordings by a recording device, comprising determining if a recording duration of a new scheduled recording conflicts with a recording duration of a preset scheduled recording, and if the conflicting new scheduled recording has a higher priority, automatically modifying the preset scheduled recording by the recording device to resolve the conflict.  
         [0019]     The objects and/or advantages can be achieved in a whole or in parts by a recording/reproducing device, comprising a storage device to store information, a controller that controls the storage of information in the storage device, and performs at least one of the following control operation: (a) determining if a recording duration of new scheduled recording conflicts with a recording duration of preset scheduled recording, and accepting the new scheduled recording by the recording device even if a conflict exists with the recording duration of at least one preset scheduling recording, and allowing at least one modification to the at least one conflicting preset scheduled recording based on input information after the recording device stores the new scheduled recording, or (b) determining if a recording duration of anew scheduled recording conflicts with a recording duration of a preset scheduled recording, and if the conflicting new scheduled recording has a higher priority, automatically modifying the preset scheduled recording by the recording device to resolve the conflict.  
         [0020]     Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objects and advantages of the invention may be realized and attained as particularly pointed out in the appended claims. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]     The invention will be described in detail with reference to the following drawings in which like reference numerals refer to like elements wherein:  
         [0022]      FIGS. 1A and 1B  illustrate block diagrams of optical disk recording/reproducing apparatus  
         [0023]      FIG. 2  illustrates a flowchart of a method for modifying scheduled recordings that overlap in time with each other in accordance with the present invention;  
         [0024]      FIG. 3  illustrates an exemplary menu screen for editing scheduled recordings;  
         [0025]      FIG. 4  illustrates an exemplary menu screen for resolving the problem of recording schedule conflicts in accordance with one embodiment of the present invention;  
         [0026]      FIG. 5  illustrates a diagram of a method in accordance with the embodiment shown in  FIG. 4 ;  
         [0027]      FIG. 6  illustrates an exemplary menu screen for automatically resolving the problem of recording schedule conflicts in accordance with another embodiment of the present invention;  
         [0028]      FIG. 7  illustrates a diagram of a method in accordance with the embodiment shown in  FIG. 6 ;  
         [0029]      FIG. 8  illustrates an exemplary menu screen for automatically resolving the problem of recording schedule conflicts in accordance with another embodiment of the present invention; and  
         [0030]      FIG. 9  illustrates a diagram of a method in accordance with the embodiment shown in  FIG. 8 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0031]      FIGS. 1A , and  1 B illustrate block diagrams of various optical disk recording/reproducing apparatus embodying the present invention. The apparatus comprises a tuner  10 , a PES encoder  12 , a recording DSP  13 , an optical driver  14 , an optical pickup  2 , an RF unit  20 , a reproduction DSP  21 , a PES decoder  22 , an OSD unit  33 , a mixer  24 , a servo control unit  31 , a memory  32 , a clock unit  34 , a microcomputer  30 , and optionally a hard disk  40 . The tuner  10  tunes to a requested TV channel. The PES encoder  12  digitizes the audio/video signals from the tuned channel, encodes the digitized signals in the MPEG format, converts the MPEG encoded data into PES (packetized elementary stream) packets, and multiplexes the audio and video PES packets. The recording DSP  13  organizes the sequence of PES packets into the ECC block format and modulates the data for recording.  
         [0032]     The optical driver  14  provides electrical current to the optical pickup  2  according to the signal from the recording DSP  13 . The optical pickup  2  reads signals recorded on an optical recording medium  1 , e.g., a DVD+/−R disk, and records signals from the optical driver  14  on the recording medium  1 . The RF unit  20  generates binary signals and focusing and tracking error signals from the signal from the optical pickup  2 . The reproduction DSP  21  retrieves digital data from the binary signals and extracts management information and navigation information from the retrieved digital data. The PES decoder  22  demultiplexes data from the reproduction DSP  21  into audio and video PES packets and decodes each of the PES packets to generate audio and video signals.  
         [0033]     The OSD unit  33  generates character and graphic signals to be overlaid on the main video image. The mixer  24  mixes the video signal from the decoder  22  with the character and graphic signals from the OSD unit  33 . The servo control unit  31  controls the optical pickup  22  using the focusing and tracking error signals, controls the laser beams, and controls a spindle motor for rotating the optical recording medium  1 . The memory  32  stores data such as the list of scheduled recordings. The clock unit  34  keeps track of the current date and time. The microcomputer  30  deals with user input and supervises the operation of the apparatus.  
         [0034]     Optionally, if the hard disk  40  is present, the signal from the recording DSP  13  may be recorded to the hard disk  40 . Once recorded on the hard disk  40 , the signals may be retrieved by the reproduction DSP  21 . The recording of the signal to the hard disk  40  may occur simultaneously or sequentially with the recording of the signal to the recording medium  1  dependent upon settings of the recording/reproducing apparatus. If signals are first recorded to the hard disk  40 , the signals may then be rerecorded to the recording medium  1  after completion of the scheduled program based on settings or user input. Alternatively, the recording onto the hard disk  40  may be by-passed to record directly onto the recording medium  1 , which may be an optical recording medium.  
         [0035]      FIG. 1B  shows an alternative embodiment. The new components of  FIG. 1B , which are different from the apparatus of  FIG. 1A , are: a digital demodulator  11  for demodulating digital data streams, for example, transport streams from the tuned signal and examining header information of transport packets in the transport stream; a demux  50  for demuxing transport streams from the digital data into encoded audio/video streams and extracting management and navigation information from the digital data; and an A/V decoder  51  for decoding the encoded audio/video streams and generating audio/video signals.  
         [0036]      FIG. 2  shows an exemplary flowchart of an exemplary method for resolving recording schedule conflicts. As shown in  FIG. 2 , a user may enter at least one first scheduled recording into a recording apparatus (S 10 ). Thereafter, at a later time, another schedule recording is entered (S 11 ). Upon entry of the later (e.g. second) scheduled recording, it is determined if there is an overlap in time between any pre-existing (e.g., first) scheduled recording with the later scheduled recording being entered (S 12 ).  
         [0037]     If there is no overlap in time, the operation proceeds to have the apparatus enter a stand-by mode to wait for the recording start time and later record the scheduled recording (S 17 ). Otherwise, if there is an overlap in time (in S 12 ), an indication is displayed indicating the overlap in scheduled recordings and a request for modification is made and modification input is received (S 13 ). Thereafter, the requested modification input is requested to be confirmed. If the input is confirmed, the second schedule recording and the modified first scheduled recording are stored (S 15 ). Otherwise, if the input is not confirmed (in S 14 ), the second schedule recording is ignored and the first schedule recording is maintained without changes (S 16 ). Thereafter, the apparatus enters the stand-by mode to wait for the recording start time to record the program as scheduled (S 17 ).  
         [0038]      FIG. 3  shows a schedule recording menu screen according to an exemplary embodiment. The schedule recording menu screen preferably includes the recording item number (No.), a channel (Ch.), a date, including the day, a start time, an end time, and the record mode to indicate whether the scheduled recording is a once, daily, weekly, or any other type of recording. The menu screen also includes a button for canceling the add/edit operation or confirming completion of the operation.  
         [0039]      FIG. 4  shows an exemplary schedule recording menu screen showing a pre-stored scheduled recording  501  that conflicts with an added new scheduled recording. As shown in  FIG. 4 , the types of information displayed are similar to those of  FIG. 3 . However, a display message is shown requesting modification of the pre-stored scheduled recording  501  that conflicts. Additionally, a user may choose to press the cancel button to not proceed with the modification or choose to press the confirm button to proceed with the modification.  
         [0040]      FIG. 5  shows an exemplary embodiment for modifying the pre-stored scheduled recording usable with the menu screen of  FIG. 4 . As shown in  FIG. 5 , when an added new scheduled recording is entered ( 601 ), a modification request appears as shown in  FIG. 4 . The user may then modify the pre-stored scheduled recording that overlap in time ( 602 ). Thereafter, the user completes the editing of the scheduled recording by either canceling or confirming the modification.  
         [0041]      FIG. 6  shows another exemplary embodiment of a menu screen according to the invention. Instead of modifying the pre-stored schedule recording, a user may choose to give precedence to the pre-stored schedule recording or to the newly entered schedule recording.  FIG. 6  shows the new scheduled recording. As shown, the menu has a button to cancel or confirm the precedence choice.  
         [0042]      FIG. 7  discloses an exemplary method usable with the menu of  FIG. 6 . As shown in  FIG. 7 , when a user enters a new scheduled recording ( 801 ), a warning may be displayed ( 802 ) the new scheduled recording is displayed as shown in the menu of  FIG. 6 . The user may decide to give precedence to the new scheduled recording. The editing of the scheduled recording is completed ( 803 ) by either canceling or confirming the choice.  
         [0043]      FIG. 8  shows another exemplary embodiment of a menu screen, which shows all the conflicting scheduled recording, including the pre-stored scheduled recording and the new scheduled recording. However, instead of merely giving precedence to either the pre-stored scheduled recording or the new scheduled recording, a user is able to choose the exact scheduled recording, whether pre-stored or new, that will be given precedence.  
         [0044]      FIG. 9  shows an exemplary method usable with the menu of  FIG. 8 . As shown in  FIG. 9 , when a user enters a new scheduled recording ( 1001 ), a warning and all conflicting scheduled recordings are displayed ( 1002 ), as shown in  FIG. 8 . Once a user selects which of the schedule recording to give precedence, the edit is complete ( 1003 ).  
         [0045]     The method for resolving scheduled recording conflicts will now be described in detail with reference to the flowchart shown in  FIG. 2 , the block diagram shown in  FIG. 1 , the menus shown in  FIGS. 3, 4 ,  6  and  8 , and the flow diagrams shown in  FIGS. 5, 7  and  9 .  
         [0046]     If a user uses an input means, such as a remote controller, and selects a button for a scheduled recording menu, the microcomputer  30  controls the OSD unit  33  to output a scheduled recording menu screen, as shown in  FIG. 3 . The signal from the remote controller, which is typically an infrared signal, is received by an infrared receiving means and processed by the microcomputer  30 . The user then enters information required for a scheduled recording such as, the channel, time (start and end times including date), recording mode (e.g., one-time, daily, weekly, etc) using the keys on the remote controller. The user completes the setting for the scheduled recording by selecting “done”, whereupon the microcomputer  30  registers the newly entered scheduled recording in the list of scheduled recordings stored in the memory  32  (S 10 ).  
         [0047]     Information about a scheduled recording marked one-time recording will be removed from the memory  32  after the associated program is recorded. However, information about a scheduled recording marked daily recording or weekly recording will remain in the memory  32  after the associated program is recorded because the recording operation will be performed repeatedly at the scheduled time of the next day or the next week. In such cases, the date to perform the next scheduled recording session is updated after every scheduled recording session.  
         [0048]     When a scheduled recording marked weekly recording is added, the day of week as well as the date to perform the scheduled recording is stored in the memory  32 . After completing the settings for scheduled recording, the optical disk recording/reproducing apparatus is placed in a standby mode, wherein every component except for the components needed for checking the time and receiving the power on/off requests is inactive, and thus, power consumption thereof is reduced significantly.  
         [0049]     If the user wants to add a daily or weekly scheduled recording to the list of scheduled recordings at some time after the setting of the previous or first scheduled recording, the user turns on the disk recording/reproducing apparatus and selects again the scheduled recording menu. The microcomputer  30  then provides the menu screen as shown in  FIG. 3  through the OSD unit  33 . Using the menu screen, the user enters a new or second scheduled recording, such as a desired channel, scheduled recording time including date, and recording mode, and selects “done” (S 11 ). It is assumed that the recording time includes the date and/or other information hereinafter.  
         [0050]     Receiving the information, the microcomputer  30  determines if the new scheduled recording overlaps in time with some of the scheduled recordings in the list of pre-stored scheduled recordings stored in the memory  32 . If it is determined that the new scheduled recording partly overlaps in time with one of daily, weekly, or other pre-stored scheduled recordings stored in the memory  32  (S 12 ), the microcomputer  30  temporarily stores information of the new scheduled recording in the memory  32 , displays a message indicative of the schedule conflict, and displays the pre-stored scheduled recording  501  that partly overlaps in time with the new scheduled recording, as shown in  FIG. 4 , thereby allowing the user to modify the setting of the pre-stored scheduled recording (S 13 ).  
         [0051]     For example, if the recording mode of the pre-stored scheduled recording is a daily recording and the recently entered recording is a one time occurrence, the user can change the recording date to the next day. If the recording mode is a weekly recording, the user changes the recording date to the next week, i.e., seven days later, and so on. If the recently entered recording is to permanently replace the pre-stored scheduled recording, this entry can be deleted.  
         [0052]     When the user selects “done” (S 14 ), the microcomputer  30  updates the list of scheduled recordings in such a way that the modification made by the user to the pre-stored schedule recording is reflected and the new scheduled recording stored temporarily in the memory  32  is included in the list of scheduled recordings (S 15 ). As a result, the problem of overlapped scheduled recordings is simply resolved by modifying the pre-stored scheduled recording through a single step  602  using a single menu screen without performing the complicated steps. On the other hand, if the user selects “cancel” in the menu screen shown in  FIG. 4  (S 14 ), the microcomputer  30  ignores the temporarily stored information and maintains the list of scheduled recordings unchanged (S 16 ).  
         [0053]     In another exemplary embodiment, the modification can be made in a way different from the method using the menu screen shown in  FIG. 4 . For example, instead of automatically displaying the conflicting pre-stored scheduled recording to be modified, if a new scheduled recording partly overlaps in time with some of pre-stored scheduled recordings, the guide menu of  FIG. 6  is displayed. The menu screen displays a message asking whether the user intends to give precedence to the new scheduled recording. If the user selects “confirm” from the guide screen shown in  FIG. 6 , it indicates that the user intends to ignore the pre-stored scheduled recording that conflicts and give precedence to the new scheduled recording. The microcomputer  30 , therefore, adds the new scheduled recording to the list of scheduled recordings stored in the memory  32 , and automatically modifies the pre-stored scheduled recording that overlaps in time in view of the new scheduled recording.  
         [0054]     For example, if the pre-stored scheduled recording is a one-time recording, the pre-stored scheduled recording is deleted. If the recording mode of the pre-stored scheduled recording is a daily recording, the recording date is changed to the next day. If the recording mode thereof is a weekly recording, the recording date is changed to the next week, i.e., seven days later, and so on. In case of the one-time recording, it is also possible to record only the part of the pre-stored scheduled recording that does not overlap with the new scheduled recording session instead of deleting the pre-stored scheduled recording. In such a case, the pre-stored scheduled recording will be modified by having its start or end time, or other information, changed to not conflict with the new scheduled recording.  FIG. 6  indicates the mode to be “Once”, but if the mode is “Daily” or “Weekly”, the user may instead replace the pre-stored scheduled recording with similar mode, and hence, the precedence to the new entry deletes such pre-stored scheduled recording. In the embodiment shown in  FIG. 6 , the user easily resolves the schedule conflict simply by selecting “confirm”  802  after entering information for the new scheduled recording  801 , as shown in  FIG. 7 . On the other hand, if the user selects “cancel” in the menu screen shown in  FIG. 6 , the microcomputer  30  ignores the new information that has been temporarily stored show deletion and maintains the list of scheduled recordings unchanged. In an alternative embodiment, the new entry can be modified to avoid the conflict.  
         [0055]     In another exemplary embodiment, all scheduled recordings that overlap, including the new schedule recording, are displayed and a choice is given to the user to choose from any of the pre-stored scheduled recordings or the new scheduled recording for precedence. For example, as shown in  FIG. 8 , the new scheduled recording (No.  13 ) overlaps with both the pre-stored scheduled recordings No.  1  and No.  4  for a weekly recording, although pre-stored scheduled recordings No.  1  and No.  4  themselves do not overlap. The user then uses the remote to mark or choose by number the desired schedule recording to give precedence to. If the new scheduled program is chosen, then the pre-stored scheduled recordings will be appropriately modified as discussed above. Otherwise, if the pre-stored scheduled recording is chosen, then the new scheduled recording is deleted.  FIG. 9  shows the process graphically.  
         [0056]     After completing the scheduling, the recording/reproducing apparatus is placed in the standby mode (S 17 ). In the standby mode, the microcomputer  30  keeps examining if the current date and time falls within the time period of one of the scheduled recordings. If so, the microcomputer  30  puts the apparatus in normal mode and instructs the tuner  10  to tune to the channel to be recorded. At this point, a program time table of the tuned channel may be obtained. The microcomputer  30  controls the servo control unit  31  so that the optical recording medium  1  rotates at a desired rotational speed and the optical pickup  2  moves to a location when the scheduled recording session begins.  
         [0057]     The video signal received from the tuned channel is MPEG encoded by the PES encoder  12  and then organized into PES packets. The PES packets are constructed into the ECC block format for error correction by the recording DSP  13  and recorded on the recording medium  1  by the optical driver  14  and optical pickup  2  after being modulated into signals for recording (S 17 ). Alternatively, the signals may be recorded to the hard disk  40 , when the scheduled recording session begins. Recording to the hard disk  40  may occur simultaneously, or alternately. If recorded to the hard disk  40  first, the program may be later re-recorded to the recording medium  1 . The recording medium is preferably an optical disk.  
         [0058]     The present invention provides a method and apparatus that allows a user to easily resolve recording schedule conflicts caused when the user enters a new scheduled recording that overlaps in time with at least one of pre-stored scheduled recordings. The recording schedule conflicts can be easily resolved without complicated and inconvenient modification steps.  
         [0059]     As can be appreciated, the present invention is applicable to cable, satellite, internet or other wired or wireless transmission and reception.  
         [0060]     The foregoing embodiments and advantages are merely exemplary and are not to be construed as limiting the present invention. The present teaching can be readily applied to other types of apparatuses. The description of the present invention is intended to be illustrative, and not to limit the scope of the claims. Many alternatives, modifications, and variations will be apparent to those skilled in the art. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures.