Abstract:
A carrier locking apparatus of an inkjet printer having: a latch groove on a moving carrier carrying an ink cartridge; a locking lever, installed at a home position of the carrier, with a first end having a latch, and a second end having a pivoting lever; and a toggle spring joined to the locking lever&#39;s second end selectively applying elastic force to the locking lever to maintain each of two pivoted states. When the carrier moves to the home position, the carrier pushes the pivoting lever to pivot the locking lever in a first direction, inserting the latch into the latch groove to lock the carrier. When the carrier moves from the home position, the locking lever pivots in a second direction opposite the first direction, the latch disengages from the latch groove to unlock the carrier, and the locking lever pivots in the second direction.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
         [0001]    This application claims the benefit of Korean Patent Application No. 2002-71970, filed Nov. 19, 2002, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.  
         BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to an inkjet printer, and more particularly, to a carrier locking apparatus for an inkjet printer, to lock a carrier in which at least one ink cartridge is mounted in a home position, to withstand external impact or vibration.  
           [0004]    2. Description of the Related Art  
           [0005]    In general, an inkjet printer is a printer in which an image is formed on a recording medium by jetting ink droplets onto the recording medium from at least one ink cartridge mounted in a carrier that reciprocates perpendicularly to the transfer direction of the recording medium. In particular, in a color inkjet printer, a mono-cartridge containing a black ink, and color cartridges containing various color inks, for example, cyan, magenta, and yellow, are mounted in a carrier, and a color image can be printed by combining these color inks.  
           [0006]    [0006]FIG. 1 is a perspective view illustrating a conventional carrier of an inkjet printer, a carrier moving apparatus, and a carrier parking apparatus, and FIG. 2 is an enlarged perspective view illustrating the carrier parking apparatus of FIG. 1.  
           [0007]    Referring to FIGS. 1 and 2, an inkjet printer has a carrier  10  for reciprocating ink cartridges  12  mounted therein. The carrier  10  is moved by a carrier belt  40 , and guided by a guide shaft  30 . The carrier belt  40  is wound around a driving pulley  42  and a driven pulley  46 , and a portion of the carrier belt  40  is held by a belt holder (not shown) provided at the rear side of the carrier  10 . The driving pulley  42  is connected to and driven by a rotation shaft of a driving motor  44  to circulate the carrier belt  40 . The circulation direction of the carrier belt  40  is changed according to the rotation direction of the driving pulley  42 . When the carrier belt  40  circulates, the carrier  10  moves linearly along the guide shaft  30 . Reference numeral  48  denotes a spring that applies a predetermined tensional force to the carrier belt  40 .  
           [0008]    When the printer is not in operation, the carrier  10  is parked at a home position provided at one end portion of the inkjet printer. A parking apparatus  50  is provided at the home position, and caps  55  are installed at the parking apparatus  50  to cover respective head chips  14  (FIG. 3A) provided at the lower surfaces of the ink cartridges  12 . Each head chip  14  has a plurality of nozzles for jetting ink, and when the carrier  10  is parked at the home position, the caps  55  cover the respective head chips  14 . Once the cap  55  covers the head chip  14 , ink leakage from the nozzles of the head chip  14  is prevented since the internal pressure of the cap  55  is regulated to be the same as or higher than the internal pressure of the ink cartridge  12 . Additionally, the cap  55  seals the head chip  14  from external air to prevent ink from clotting due to the evaporation of a volatile constituent of ink.  
           [0009]    The parking apparatus  50  has an external frame  51  installed at a main frame  20  of the printer, and an internal frame  54  joined to the external frame  51  to move up and down along a predetermined path. Wipers  56  are installed at upper portions of the internal frame  54  to clean the respective surfaces of the head chips  14 . Guide grooves  53  serving as the predetermined path are located on the external frame  51 , and guide pins  57 , installed at the internal frame  54 , are inserted into the guide grooves  53 . In addition, a parking lever  58  and an un-parking lever  59  are provided at opposing ends of the internal frame  54 .  
           [0010]    The operation of the conventional parking apparatus having the above-described structure is now described with reference to FIGS. 3A and 3B.  
           [0011]    Referring to FIG. 3A, when the printer is operating, the carrier  10  is out of the home position, and the internal frame  54  of the parking apparatus  50  is maintained in a lowered state due to an elastic force of a spring  60 . Additionally, the guide pins  57  of the internal frame  54  are positioned at lower end portions of the guide grooves  53  of the external frame  51 .  
           [0012]    When a printing job is completed, the carrier  10  moves in the direction of arrow R and pushes the parking lever  58 .. Accordingly, the guide pins  57  move upward along the paths of the respective guide grooves  53 , and the internal frame  54  and the caps  55  move upward simultaneously. As shown in FIG. 3B, when the carrier  10  reaches the home position, the caps  55  are raised completely, and cover the respective head chips  14  of the ink cartridges  12 . Further, the guide pins  57  of the internal frame  54  are positioned at upper end portions of the respective guide grooves  53  of the external frame  51 .  
           [0013]    When a printing operation is requested when the carrier  10  is parked at the home position, the carrier belt  40  is circulated by the operation of the driving motor  44 , and the carrier  10  moves in the direction of arrow F along the guide shaft  30 . Accordingly, the internal frame  54  is moved downward by the elastic force of the spring  60 , the guide pins  57  move downward along the paths of the respective guide grooves  53 , and the caps  55  move downward and separate from the head chips  14 . The surfaces of the head chips  14  are cleaned by the wipers  56  when the guide pins  57  are positioned at middle portions of the guide grooves  53 . Thereafter, as shown in FIG. 3A, when the carrier  10  is completely out of the home position while pushing the un-parking lever  59 , the internal frame  54  is completely lowered due to the elastic force of the spring  60 . Further, the guide pins  57  of the internal frame  54  are positioned at the lower end portion of the respective guide grooves  53  of the external frame  51 .  
           [0014]    In the conventional parking apparatus  50  described above, however, when an external impact or vibration is applied to the carrier  10 , the carrier  10  may be easily separated from the parking apparatus  50 . Further, the head chips  14  may separate from the respective caps  55 , and accordingly ink may leak from the nozzles of the head chips  14 . The leaked ink may cause the transfer path of a recording medium to be contaminated, and reduce the quality of printing. In addition leaked ink reduces a useful life of the ink cartridge  12 . Further, when the head chips  14  are exposed, the head chips  14  may be contaminated by dust or the like, and ink may clot in the nozzles due to the evaporation of the volatile constituent of ink and block the nozzles. Further still, if the nozzles are blocked, ink will not jet through the nozzles properly, and the quality of printing deteriorates further. Also, when the carrier  10  is separated from the home position and allowed to rattle freely, the carrier  10  and the head chips  14  may be easily damaged.  
         SUMMARY OF THE INVENTION  
         [0015]    To solve the above-described problems, it is an aspect of the present invention to provide a carrier locking apparatus for an inkjet printer to lock a carrier parked at a home position, and prevent the carrier from separating from a parking apparatus provided at the home position despite external impacts or vibrations of a predetermined magnitude.  
           [0016]    Accordingly, to achieve the above and/or other aspects, there is provided a carrier locking apparatus of an inkjet printer, including a reciprocally moving carrier carrying an ink cartridge, and a parking apparatus provided at the home position, the carrier locking apparatus having: a latch groove provided at a predetermined location on the carrier; a locking lever, which is installed at the parking apparatus and has a first end provided with a latch, and a second end provided with a pivoting lever; and a toggle spring joined to the second end of the locking lever to apply an elastic force to the locking lever to selectively maintain each of two pivoted states of the locking lever, wherein when the carrier moves to the home position, the carrier pushes the pivoting lever and pivots the locking lever in a first direction to insert the latch into the latch groove to lock the carrier, and when the carrier moves from the home position, the locking lever pivots in the direction opposite the first direction, and disengages the latch from the latch groove to unlock the carrier.  
           [0017]    According to one aspect, a metal plate is provided at the second end of the locking lever, and an electromagnet is provided to selectively attract the metal plate and pivot the locking lever in the first direction to lock the carrier.  
           [0018]    According to one aspect, the second end of the locking lever has two prongs, each end of the toggle spring is connected to one of the two prongs, and a middle portion of the toggle spring contacts and is supported by a bracket installed at the main frame of the printer.  
           [0019]    According to another aspect, there is provided a carrier locking apparatus of an inkjet printer including a reciprocally moving carrier carrying an ink cartridge, and a main frame, the carrier apparatus having: a hook provided at a first end of the carrier; a locking lever pivotably installed on the main frame, and provided with a metal plate at a first end; an electromagnet to selectively attract the metal plate to pivot the locking lever in a first direction; and an elastic member to bias the locking lever in a second direction opposite the first direction, wherein when the carrier moves to a home position, the metal plate is attracted to and contacts the electromagnet, the locking lever pivots in the first direction, and the hook engages a second end of the locking lever to lock the carrier, and when the carrier moves from the home position, the electromagnet disconnects from an electric power source, the locking lever is pivoted in the second direction by the elastic force of the elastic member, and the hook disengages from the second end of the locking lever to unlock the carrier.  
           [0020]    According to one aspect, the electromagnet has two cores, a permanent magnet installed between the two cores, two bobbins surrounding the two cores, respectively, and two coils wound around circumferential surfaces of the bobbins.  
           [0021]    According to one aspect, the electromagnet is configured so that when the electromagnet is not connected to an electric power source, a magnetic field of the permanent magnet around the leading ends of the cores attracts the metal plate to the leading ends of the cores, and when the electromagnet is connected to an electric power source, the magnetic field is offset.  
           [0022]    According to one aspect, the electromagnet is fixedly installed at an outer side surface of the main frame, and the leading ends of the cores face the metal plate.  
           [0023]    With the present invention, when the carrier is parked at the home position, the carrier is locked by the locking apparatus, and the carrier is prevented from moving from the home position despite external impacts or vibrations of predetermined magnitude applied to the carrier.  
           [0024]    Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0025]    These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the preferred embodiments, taken in conjunction with the accompanying drawings of which:  
         [0026]    [0026]FIG. 1 is a perspective view illustrating a conventional carrier for ink cartridges of an inkjet printer, a carrier moving apparatus, and a carrier parking apparatus;  
         [0027]    [0027]FIG. 2 is an enlarged perspective view illustrating the carrier parking apparatus of FIG. 1;  
         [0028]    [0028]FIGS. 3A and 3B are front views of the parking apparatus of FIG. 1;  
         [0029]    [0029]FIGS. 4 and 5 are perspective views illustrating a carrier locking apparatus of an inkjet printer according to a first embodiment of the present invention, FIG. 4 shows a carrier positioned out of a home position, and FIG. 5 shows the carrier parked at the home position;  
         [0030]    [0030]FIGS. 6A and 6B are an enlarged perspective view and a section view, respectively, of an electromagnet of FIG. 4; and  
         [0031]    [0031]FIGS. 7 and 8 are perspective views illustrating a carrier locking apparatus of an inkjet printer according to a second embodiment of the present invention, FIG. 7 shows a carrier parked at a home position, and FIG. 8 shows a carrier positioned out of the home position. 
     
    
     DETAILED DESCRIPTION  
       [0032]    Reference will now be made in detail to the present preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures.  
         [0033]    [0033]FIGS. 4 and 5 are perspective views illustrating a carrier locking apparatus of an inkjet printer according to a first embodiment of the present invention. FIG. 4 shows a carrier positioned out of a home position, and FIG. 5 shows the carrier parked at the home position.  
         [0034]    Referring to FIG. 4, an inkjet printer has a carrier  110  for ink cartridges. According to one aspect, there are two cartridges: one of the two ink cartridges  112  is a mono-cartridge containing black ink, and the other is a color cartridge containing cyan, magenta, and yellow inks. According to another aspect however, each of color inks, i.e., cyan, magenta, or yellow ink is contained in a separate ink cartridge, thus, four ink cartridges would be mounted in the carrier  110 .  
         [0035]    To form an image on a recording medium by jetting ink onto a recording medium from the ink cartridges, a carrier moving apparatus is provided in the inkjet printer for reciprocating the carrier  110  in a direction perpendicular to a transfer direction of the recording medium. The carrier moving apparatus has a carrier belt  140  wound and circulating around a driving pulley  142 , and a driven pulley (not shown) to move the carrier  110 , a guide shaft  130  to guide the reciprocating movement of the carrier  110 , and a driving motor  144  to rotate the driving pulley  142 .  
         [0036]    When the printer is not in operation, the carrier  110  is parked at a parking apparatus  150  provided at a home position. The structure of the parking apparatus  150  is similar to a conventional parking apparatus. That is, the parking apparatus  150  has an external frame  151  fixedly installed at a main frame  120  of the printer, and an internal frame  154  joined to the external frame  151  that moves up and down along a predetermined path, and has caps  155  and wipers  156  installed at upper portions thereof. Guide grooves  153  having a predetermined path located on the external frame  151 , and guide pins  157  installed at the internal frame  154  are inserted into the guide grooves  153 . In addition, a parking lever  158  and an un-parking lever  159  are located at opposing ends of the internal frame  154 .  
         [0037]    In addition, a carrier locking apparatus for locking the carrier  110  is provided to prevent the carrier  110  from being separated from the parking apparatus  150  when the carrier  110  is parked at the home position. The carrier locking apparatus has a locking lever  160  that pivots, installed on the external frame  151 , a latch groove  172  provided at the carrier  110 , and a toggle spring  180  joined to the rear end of the locking lever  160 . According to one aspect, the carrier locking apparatus further comprises an electromagnet  190  to restrain the pivoting motion of the locking lever  160 .  
         [0038]    The locking lever  160  is assembled to a pivot pin  161  installed at the front surface of the external frame  151  at about the middle thereof. And a latch  162  having a sharp bevelled shape is provided at one end, i.e., a leading end of the locking lever  160 . When the carrier  110  is parked at the home position, the latch  162  is inserted into the latch groove  172  so that the carrier  110  cannot be separated from the parking apparatus  150 . The latch groove  172  is located at a predetermined position, for example, the front left edge of the carrier  110 , and has a shape that complements the latch  162 . According to one aspect, the latch groove  172  is located on the carrier  110  itself. According to another aspect, as shown in FIG. 4, the latch groove  172  is located on a latch groove member  170  that is attached to the carrier  110 . According to yet another aspect, the latch groove member  170  is an integrated part of the carrier  110 .  
         [0039]    A pivoting lever  166  projects upward at an other end, i.e., a rear end, of the locking lever  160 . When the carrier  110  moves toward the home position, the pivoting lever  166  is pushed in the direction of arrow R by the carrier  110 . Accordingly, the locking lever  160  pivots around the pivot pin  161  by a predetermined angle.  
         [0040]    In addition, the rear end of the locking lever  160  has two prongs  164 , and two ends of the toggle spring  180  are joined to the two prongs  164 . An intermediate portion of the toggle spring  180  is joined to and supported by a bracket  182 , which is attached to an external side surface of the main frame  120 . When the rear end of the locking lever  160  is in the raised state, as shown in FIG. 4, the toggle spring  180  applies an elastic force to the rear end of the locking lever  160  to maintain the raised state. And when the rear end of the locking lever  160  is in the lowered state, as shown in FIG. 5, the toggle spring  180  applies elastic force to the rear end of the locking lever  160  to maintain the lowered state. Thus, the rear end of the locking lever  160  is maintained in the raised and lowered states by the toggle spring  180 , and therefore, free pivoting of the locking lever  160  is restrained by the toggle spring  180 .  
         [0041]    As noted above, according to one aspect, the carrier locking apparatus has the electromagnet  190 . Further, a paramagnetic metal plate  168  is provided between the two prongs  164  of the rear end of the locking lever  160 . The metal plate  168  projects outside of the main frame  120  through a hole  122  formed at the main frame  120 . According to one aspect, the metal plate  168  is attached to the locking lever  160  as a separate member. According to another aspect, the locking lever  160  is made of paramagnetic metal, and the metal plate  168  and the locking lever  160  are constructed as an integrated member.  
         [0042]    The electromagnet  190  is shown in detail in FIGS. 6A and 6B. The electromagnet  190  shown in FIGS. 6A and 6B is disclosed in Korean Laid-Open Patent Application Publication No. 2000-13010 published on Mar. 6, 2000, filed by the applicant of the present invention.  
         [0043]    Referring to FIGS. 6A and 6B, the electromagnet  190  has two cores  191  fixedly installed at a base  199 , a permanent magnet  192  installed between the two cores  191 , bobbins  193  surrounding the two cores  191  separately, and coils  194  wound around the circumferences of the bobbins  193 . In addition, leading ends of the cores  191  project slightly from ends of the bobbins  193 . Reference numeral  196  denotes DC input terminals, and reference numeral  197  denotes screw insertion holes.  
         [0044]    In the electromagnet  190  configured as described above, when electric power is not applied to the electromagnet  190 , a magnetic field is set up around the leading ends of the cores  191  by the magnetic force of the permanent magnet  192 . Accordingly, the metal plate  168  is attracted to and contacts the leading ends of the cores  191 , and pivoting of the locking lever  160  is restrained. But when electric power is applied to the electromagnet  190 , the magnetic field induced by the coils  194  offsets the magnetic field of the permanent magnet  192 . Accordingly, the metal plate  168  separates from the leading ends of the cores  191 , and the locking lever  160  is allowed to pivot.  
         [0045]    Again referring to FIG. 4, the electromagnet  190  is fixedly installed at the external side surface of the main frame  120  with screws  124 , and the leading ends of the cores  191  are positioned at the lower end of a vertical movement path of the metal plate  168 . Therefore, when the locking lever  160  pivots in the clockwise direction, and the metal plate  168  moves downward, the metal plate  168  contacts the leading ends of the cores  191 .  
         [0046]    The operation of the carrier locking apparatus having the structure described above will be described with reference to FIGS. 4 and 5.  
         [0047]    As shown in FIG. 4, the carrier  110  is out of the home position during the printing operation. The internal frame  154  of the parking apparatus  150  is maintained in the lowered state as described above, and the guide pins  157  of the internal frame  154  are positioned at the lower ends of the guide grooves  153  of the external frame  151 . In addition, the locking lever  160  is fully pivoted counter-clockwise, and, accordingly, the latch  162  of the leading end of the locking lever  160  is not in the latch groove  172  of the carrier  110 . This state is maintained as it is by the elastic force of the toggle spring  180 , as described above.  
         [0048]    When the printing operation is completed, the carrier  110  moves in the direction of arrow R, and pushes the parking lever  158 . Accordingly, the guide pins  157  move upward along the paths of the respective guide grooves  153 , and the internal frame  154  and the caps  155  also move upward.  
         [0049]    Subsequently, the carrier  110  pushes the pivoting lever  166  of the locking lever  160 , and, the locking lever  160  pivots clockwise around the pivot pin  161 . Correspondingly, the latch  162  provided at the leading end of the locking lever  160  begins to move upward, and the two prongs  164  provided at the rear end of the locking lever  160  turn the toggle spring  180  downward while moving downward.  
         [0050]    As shown in FIG. 5, when the carrier  110  reaches the home position, the caps  155  are fully raised, and cover the head chips of the ink cartridges  112 . Further, the latch  162  of the leading end of the locking lever  160  is inserted into the latch groove  172 , and, the carrier  110  is locked in the home position. In addition, the toggle spring  180  is fully turned downward and the elastic force of the toggle spring  180 , that is applied to the locking lever  160  as described above, prevents the locking lever  160  from pivoting freely. Further, the engagement of the latch  162  in the latch groove  172  resists external impacts and vibrations applied to the carrier  110 , to maintain the carrier  110  in the home position.  
         [0051]    At this time, electric power is not applied to the electromagnet  190 . A magnetic field, set up by the permanent magnet  192  around the leading ends of the cores  191 , attracts the metal plate  168  which contacts the leading ends of the cores  191 . Thus, the elastic force of the toggle spring  180  and the magnetic force of the electromagnet  190  are applied to the locking lever  160  to maintain the locking state of the carrier  110 .  
         [0052]    When a printing operation is requested when the carrier  110  is parked at the home position, the carrier belt  140  is circulated by the driving force of the driving motor  144 , and the carrier  110  moves in the direction of arrow F along the guide shaft  130 . The carrier  110  moves forward and pushes the un-parking lever  159 , and the guide pins  157  move downward along the paths of the guide grooves  153 . At the same time, the internal frame  154  and the caps  155  move downward, and the caps  155  separate from the head chips provided at the lower surfaces of the ink cartridges  112 .  
         [0053]    The driving force of the driving motor  144  causes the carrier  110  to move forward, and also causes the latch  162  of the leading end of the locking lever  160  to escape from the latch groove  172  and to move downward, and thus, the locking lever  160  pivots counter-clockwise. At this time, electric power is applied to the electromagnet  190 . Since the magnetic field induced by the coils  194  offsets the magnetic field set up by the permanent magnet  192  around the leading ends of the cores  191 , the metal plate  168  separates from the leading ends of the cores  191 . Accordingly, the rear end of the locking lever  160  moves upward to cause the toggle spring  180  to turn upward, as shown in FIG. 4. When the counter-clockwise pivoting of the locking lever  160  is completed, the electromagnet  190  is disconnected from the electric power source.  
         [0054]    [0054]FIGS. 7 and 8 are perspective views illustrating a carrier locking apparatus of an inkjet printer according to a second embodiment of the present invention: FIG. 7 shows a carrier parked at a home position, and FIG. 8 shows a carrier positioned out of the home position. The same reference numerals as in FIGS. 4 and 5 are used to denote those elements performing the same or similar function, and detailed descriptions thereof are omitted.  
         [0055]    Referring to FIG. 7, a carrier locking apparatus includes a locking lever  260  pivotably installed at a main frame  120  of a printer, a paramagnetic metal plate  268  provided at a rear end  264  of the locking lever  260 , a hook  270  provided at the carrier  110 , an elastic member  280  to apply an elastic force to the locking lever  260 , and an electromagnet  290  to restrain pivoting movement of the locking lever  260 .  
         [0056]    A pivot pin  261  is installed at an external side surface of the main frame  120 , and the locking lever  260  is assembled to the pivot pin  261  at about the middle of the locking lever  260 . When the carrier  110  is parked at the home position, the hook  270  is engaged by a leading end  262  of the locking lever  260 . According to one aspect, the metal plate  268  is provided at the rear end  264  of the locking lever  260 . According to another aspect, the metal plate  268  is attached to the rear end  264  of the locking lever  260  as a separate member. According to yet another aspect, the locking lever  260  is made of paramagnetic metal and, the metal plate  268  is unnecessary, since the rear end  264  of the locking lever  260  is attracted to and connects to the leading ends of cores  291  of an electromagnet  290  as described below.  
         [0057]    According to one aspect, the hook  270  is provided at a front right edge portion of the carrier  110 . A hooking projection  272  that engages the leading end of the locking lever  260  projects upward at an end of the hook  270 . According to one aspect, the upper surface of the hooking projection  272  is an inclined surface.  
         [0058]    The elastic member  280  is connected to the locking lever  260  at a predetermined position, and applies an elastic force to the locking lever  260  in one direction, i.e., in a direction in which the locking lever  260  is disengaged from the hook  270 . According to one aspect, when the elastic member  280  is installed at an upper side of the locking lever  260 , as shown in FIG. 7, a tension spring is used as the elastic member  280 . According to another aspect, when the elastic member  280  is installed at a lower side of the locking lever  260 , a compression spring is used as the elastic member  280 . The elastic member  280  serves to move the leading end  262  of the locking lever  260  upward, and various types of springs can perform such a job and be used as the elastic member  280 , for example, a leaf spring.  
         [0059]    The electromagnet  290  has the structure shown in FIGS. 6A and 6B, as in the first embodiment. The electromagnet  290  is fixedly installed on an outer side surface of the main frame  120  with screws  224 , and the leading ends of the cores  291  are positioned at the upper end of the vertical movement path of the metal plate  268 . Thus, when the locking lever  260  pivots counter-clockwise, and the metal plate  268  is raised, the metal plate  268  contacts the leading ends of the cores  291 .  
         [0060]    According to one aspect, the carrier locking apparatus is disposed in another direction. That is, the hooking projection projects downward, and in this case, the pivoting direction of the locking lever  260  is changed. Accordingly, the direction of disposing the elastic member  280  and the electromagnet  290  are changed to a direction opposite to that shown in FIG. 7.  
         [0061]    Now, the operation of the carrier locking apparatus having the above-described structure according to the second embodiment of the present invention will be described below with reference to FIGS. 7 and 8.  
         [0062]    As shown in FIG. 7, when the carrier  110  is parked at the home position, the metal plate  268  attached to the rear end  264  of the locking lever  260  is attracted and attached to the leading ends of the cores  291  of the electromagnet  290 , and the hooking projection  272  of the hook  270  is engaged by the leading end  262  of the locking lever  260 . At this time, the electromagnet  290  is not connected to the electric power source, and, accordingly, since a magnetic field is set up by the permanent magnet  292  around the leading ends of the cores  291 , the metal plate  268  is attracted to and contacts the leading ends of the cores  291 . Thus, since the pivoting movement of the locking lever  260  is restrained by the magnetic force of the permanent magnet  292 , the hook  270  remains engaged with the locking lever  260 , and resists external impacts or vibrations applied to the carrier  110 . Accordingly, the carrier  110  remains in the home position.  
         [0063]    Next, when the carrier  110  is moved forward (in the direction of arrow F) from the home position to perform a printing job, as shown in FIG. 8, the electromagnet  290  is connected to an electric power source, and the magnetic field induced by the coils  294  offsets the magnetic field set up by the permanent magnet  292  around the leading ends of the cores  291 . Accordingly, the metal plate  268  detaches from the leading ends of the cores  291 , and the locking lever  260  pivots clockwise due to the elastic force of the elastic member  280 . Further, the leading end  262  of the locking lever  260  moves upward, and the hook  270  disengages from the leading end  262  of the locking lever  260  and moves forward in the direction of arrow F together with the carrier  110 . When the hook  270  is completely disengaged from the leading end  262  of the locking lever  260 , the electromagnet  290  is disconnected from the electric power source. Accordingly, the magnetic field set up by the permanent magnet  292  around the leading ends of the cores  291  of the electromagnet  290  attracts the metal plate  268 , which moves upward, and pivots the locking lever  260  counter-clockwise.  
         [0064]    When the printing job is completed, the carrier  110  moves backward in the direction of arrow R. According to one aspect, the hook  270  then elastically deforms slightly as the hook  270  pushes the leading end  262  of the locking lever  260 . According to another aspect, the leading end  262  of the locking lever  260  then elastically deforms slightly as the hook  270  pushes the lead end  262  of the locking lever  260 . Then, the hooking projection  272  of the hook  270  engages the leading end  262  of the locking lever  260  and thus, the carrier  110  returns to the locking state shown in FIG. 7.  
         [0065]    As described above, with the locking apparatus of an inkjet printer according to the present invention, since the carrier is not easily separated from the home position although external impact or vibration is applied to the carrier, a stable parking state can be maintained.  
         [0066]    Therefore, leakage of ink occurring when the caps are separated from the head chips can be prevented to ensure desirable quality of printing, and shortening of the useful life of the ink cartridge due to unnecessary consumption of ink can be prevented.  
         [0067]    In addition, since the caps always cover the head chips while the carrier is parked at the home position, contamination of the head chips and clotting of ink can be prevented and ink jet performance of the head chips can be maintained appropriately for an increased time.  
         [0068]    Further, since the carrier is not easily separated from the home position during parking, the carrier and the head chips are less likely to be damaged.  
         [0069]    While this invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that changes may be made in this embodiment without departing from the principles, spirit of the invention, the scope of which is defined in the claims and their equivalents.