Carrier locking apparatus for inkjet printer

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'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.

CROSS-REFERENCE TO RELATED APPLICATIONS

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

1. Field of the Invention

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.

2. Description of the Related Art

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.

FIG. 1is a perspective view illustrating a conventional carrier of an inkjet printer, a carrier moving apparatus, and a carrier parking apparatus, andFIG. 2is an enlarged perspective view illustrating the carrier parking apparatus of FIG.1.

Referring toFIGS. 1 and 2, an inkjet printer has a carrier10for reciprocating ink cartridges12mounted therein. The carrier10is moved by a carrier belt40, and guided by a guide shaft30. The carrier belt40is wound around a driving pulley42and a driven pulley46, and a portion of the carrier belt40is held by a belt holder (not shown) provided at the rear side of the carrier10. The driving pulley42is connected to and driven by a rotation shaft of a driving motor44to circulate the carrier belt40. The circulation direction of the carrier belt40is changed according to the rotation direction of the driving pulley42. When the carrier belt40circulates, the carrier10moves linearly along the guide shaft30. Reference numeral48denotes a spring that applies a predetermined tensional force to the carrier belt40.

When the printer is not in operation, the carrier10is parked at a home position provided at one end portion of the inkjet printer. A parking apparatus50is provided at the home position, and caps55are installed at the parking apparatus50to cover respective head chips14(FIG. 3A) provided at the lower surfaces of the ink cartridges12. Each head chip14has a plurality of nozzles for jetting ink, and when the carrier10is parked at the home position, the caps55cover the respective head chips14. Once the cap55covers the head chip14, ink leakage from the nozzles of the head chip14is prevented since the internal pressure of the cap55is regulated to be the same as or higher than the internal pressure of the ink cartridge12. Additionally, the cap55seals the head chip14from external air to prevent ink from clotting due to the evaporation of a volatile constituent of ink.

The parking apparatus50has an external frame51installed at a main frame20of the printer, and an internal frame54joined to the external frame51to move up and down along a predetermined path. Wipers56are installed at upper portions of the internal frame54to clean the respective surfaces of the head chips14. Guide grooves53serving as the predetermined path are located on the external frame51, and guide pins57, installed at the internal frame54, are inserted into the guide grooves53. In addition, a parking lever58and an un-parking lever59are provided at opposing ends of the internal frame54.

The operation of the conventional parking apparatus having the above-described structure is now described with reference toFIGS. 3A and 3B.

Referring toFIG. 3A, when the printer is operating, the carrier10is out of the home position, and the internal frame54of the parking apparatus50is maintained in a lowered state due to an elastic force of a spring60. Additionally, the guide pins57of the internal frame54are positioned at lower end portions of the guide grooves53of the external frame51.

When a printing job is completed, the carrier10moves in the direction of arrow R and pushes the parking lever58. Accordingly, the guide pins57move upward along the paths of the respective guide grooves53, and the internal frame54and the caps55move upward simultaneously. As shown inFIG. 3B, when the carrier10reaches the home position, the caps55are raised completely, and cover the respective head chips14of the ink cartridges12. Further, the guide pins57of the internal frame54are positioned at upper end portions of the respective guide grooves53of the external frame51.

When a printing operation is requested when the carrier10is parked at the home position, the carrier belt40is circulated by the operation of the driving motor44, and the carrier10moves in the direction of arrow F along the guide shaft30. Accordingly, the internal frame54is moved downward by the elastic force of the spring60, the guide pins57move downward along the paths of the respective guide grooves53, and the caps55move downward and separate from the head chips14. The surfaces of the head chips14are cleaned by the wipers56when the guide pins57are positioned at middle portions of the guide grooves53. Thereafter, as shown inFIG. 3A, when the carrier10is completely out of the home position while pushing the un-parking lever59, the internal frame54is completely lowered due to the elastic force of the spring60. Further, the guide pins57of the internal frame54are positioned at the lower end portion of the respective guide grooves53of the external frame51.

In the conventional parking apparatus50described above, however, when an external impact or vibration is applied to the carrier10, the carrier10may be easily separated from the parking apparatus50. Further, the head chips14may separate from the respective caps55, and accordingly ink may leak from the nozzles of the head chips14. 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 cartridge12. Further, when the head chips14are exposed, the head chips14may 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 carrier10is separated from the home position and allowed to rattle freely, the carrier10and the head chips14may be easily damaged.

SUMMARY OF THE INVENTION

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.

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.

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.

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.

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.

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.

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.

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.

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.

DETAILED DESCRIPTION

FIGS. 4 and 5are perspective views illustrating a carrier locking apparatus of an inkjet printer according to a first embodiment of the present invention.FIG. 4shows a carrier positioned out of a home position, andFIG. 5shows the carrier parked at the home position.

Referring toFIG. 4, an inkjet printer has a carrier110for ink cartridges. According to one aspect, there are two cartridges: one of the two ink cartridges112is 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 carrier110.

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 carrier110in a direction perpendicular to a transfer direction of the recording medium. The carrier moving apparatus has a carrier belt140wound and circulating around a driving pulley142, and a driven pulley (not shown) to move the carrier110, a guide shaft130to guide the reciprocating movement of the carrier110, and a driving motor144to rotate the driving pulley142.

When the printer is not in operation, the carrier110is parked at a parking apparatus150provided at a home position. The structure of the parking apparatus150is similar to a conventional parking apparatus. That is, the parking apparatus150has an external frame151fixedly installed at a main frame120of the printer, and an internal frame154joined to the external frame151that moves up and down along a predetermined path, and has caps155and wipers156installed at upper portions thereof. Guide grooves153having a predetermined path located on the external frame151, and guide pins157installed at the internal frame154are inserted into the guide grooves153. In addition, a parking lever158and an un-parking lever159are located at opposing ends of the internal frame154.

In addition, a carrier locking apparatus for locking the carrier110is provided to prevent the carrier110from being separated from the parking apparatus150when the carrier110is parked at the home position. The carrier locking apparatus has a locking lever160that pivots, installed on the external frame151, a latch groove172provided at the carrier110, and a toggle spring180joined to the rear end of the locking lever160. According to one aspect, the carrier locking apparatus further comprises an electromagnet190to restrain the pivoting motion of the locking lever160.

The locking lever160is assembled to a pivot pin161installed at the front surface of the external frame151at about the middle thereof. And a latch162having a sharp bevelled shape is provided at one end, i.e., a leading end of the locking lever160. When the carrier110is parked at the home position, the latch162is inserted into the latch groove172so that the carrier110cannot be separated from the parking apparatus150. The latch groove172is located at a predetermined position, for example, the front left edge of the carrier110, and has a shape that complements the latch162. According to one aspect, the latch groove172is located on the carrier110itself. According to another aspect, as shown inFIG. 4, the latch groove172is located on a latch groove member170that is attached to the carrier110. According to yet another aspect, the latch groove member170is an integrated part of the carrier110.

A pivoting lever166projects upward at an other end, i.e., a rear end, of the locking lever160. When the carrier110moves toward the home position, the pivoting lever166is pushed in the direction of arrow R by the carrier110. Accordingly, the locking lever160pivots around the pivot pin161by a predetermined angle.

In addition, the rear end of the locking lever160has two prongs164, and two ends of the toggle spring180are joined to the two prongs164. An intermediate portion of the toggle spring180is joined to and supported by a bracket182, which is attached to an external side surface of the main frame120. When the rear end of the locking lever160is in the raised state, as shown inFIG. 4, the toggle spring180applies an elastic force to the rear end of the locking lever160to maintain the raised state. And when the rear end of the locking lever160is in the lowered state, as shown inFIG. 5, the toggle spring180applies elastic force to the rear end of the locking lever160to maintain the lowered state. Thus, the rear end of the locking lever160is maintained in the raised and lowered states by the toggle spring180, and therefore, free pivoting of the locking lever160is restrained by the toggle spring180.

As noted above, according to one aspect, the carrier locking apparatus has the electromagnet190. Further, a paramagnetic metal plate168is provided between the two prongs164of the rear end of the locking lever160. The metal plate168projects outside of the main frame120through a hole122formed at the main frame120. According to one aspect, the metal plate168is attached to the locking lever160as a separate member. According to another aspect, the locking lever160is made of paramagnetic metal, and the metal plate168and the locking lever160are constructed as an integrated member.

The electromagnet190is shown in detail inFIGS. 6A and 6B. The electromagnet190shown inFIGS. 6A and 6Bis disclosed in Korean Laid-Open Patent Application Publication No. 2000-13010 published on Mar. 6, 2000, filed by the applicant of the present invention.

Referring toFIGS. 6A and 6B, the electromagnet190has two cores191fixedly installed at a base199, a permanent magnet192installed between the two cores191, bobbins193surrounding the two cores191separately, and coils194wound around the circumferences of the bobbins193. In addition, leading ends of the cores191project slightly from ends of the bobbins193. Reference numeral196denotes DC input terminals, and reference numeral197denotes screw insertion holes.

In the electromagnet190configured as described above, when electric power is not applied to the electromagnet190, a magnetic field is set up around the leading ends of the cores191by the magnetic force of the permanent magnet192. Accordingly, the metal plate168is attracted to and contacts the leading ends of the cores191, and pivoting of the locking lever160is restrained. But when electric power is applied to the electromagnet190, the magnetic field induced by the coils194offsets the magnetic field of the permanent magnet192. Accordingly, the metal plate168separates from the leading ends of the cores191, and the locking lever160is allowed to pivot.

Again referring toFIG. 4, the electromagnet190is fixedly installed at the external side surface of the main frame120with screws124, and the leading ends of the cores191are positioned at the lower end of a vertical movement path of the metal plate168. Therefore, when the locking lever160pivots in the clockwise direction, and the metal plate168moves downward, the metal plate168contacts the leading ends of the cores191.

The operation of the carrier locking apparatus having the structure described above will be described with reference toFIGS. 4 and 5.

As shown inFIG. 4, the carrier110is out of the home position during the printing operation. The internal frame154of the parking apparatus150is maintained in the lowered state as described above, and the guide pins157of the internal frame154are positioned at the lower ends of the guide grooves153of the external frame151. In addition, the locking lever160is fully pivoted counter-clockwise, and, accordingly, the latch162of the leading end of the locking lever160is not in the latch groove172of the carrier110. This state is maintained as it is by the elastic force of the toggle spring180, as described above.

When the printing operation is completed, the carrier110moves in the direction of arrow R, and pushes the parking lever158. Accordingly, the guide pins157move upward along the paths of the respective guide grooves153, and the internal frame154and the caps155also move upward.

Subsequently, the carrier110pushes the pivoting lever166of the locking lever160, and, the locking lever160pivots clockwise around the pivot pin161. Correspondingly, the latch162provided at the leading end of the locking lever160begins to move upward, and the two prongs164provided at the rear end of the locking lever160turn the toggle spring180downward while moving downward.

As shown inFIG. 5, when the carrier110reaches the home position, the caps155are fully raised, and cover the head chips of the ink cartridges112. Further, the latch162of the leading end of the locking lever160is inserted into the latch groove172, and, the carrier110is locked in the home position. In addition, the toggle spring180is fully turned downward and the elastic force of the toggle spring180, that is applied to the locking lever160as described above, prevents the locking lever160from pivoting freely. Further, the engagement of the latch162in the latch groove172resists external impacts and vibrations applied to the carrier110, to maintain the carrier110in the home position.

At this time, electric power is not applied to the electromagnet190. A magnetic field, set up by the permanent magnet192around the leading ends of the cores191, attracts the metal plate168which contacts the leading ends of the cores191. Thus, the elastic force of the toggle spring180and the magnetic force of the electromagnet190are applied to the locking lever160to maintain the locking state of the carrier110.

When a printing operation is requested when the carrier110is parked at the home position, the carrier belt140is circulated by the driving force of the driving motor144, and the carrier110moves in the direction of arrow F along the guide shaft130. The carrier110moves forward and pushes the un-parking lever159, and the guide pins157move downward along the paths of the guide grooves153. At the same time, the internal frame154and the caps155move downward, and the caps155separate from the head chips provided at the lower surfaces of the ink cartridges112.

The driving force of the driving motor144causes the carrier110to move forward, and also causes the latch162of the leading end of the locking lever160to escape from the latch groove172and to move downward, and thus, the locking lever160pivots counter-clockwise. At this time, electric power is applied to the electromagnet190. Since the magnetic field induced by the coils194offsets the magnetic field set up by the permanent magnet192around the leading ends of the cores191, the metal plate168separates from the leading ends of the cores191. Accordingly, the rear end of the locking lever160moves upward to cause the toggle spring180to turn upward, as shown in FIG.4. When the counter-clockwise pivoting of the locking lever160is completed, the electromagnet190is disconnected from the electric power source.

FIGS. 7 and 8are perspective views illustrating a carrier locking apparatus of an inkjet printer according to a second embodiment of the present invention:FIG. 7shows a carrier parked at a home position, andFIG. 8shows a carrier positioned out of the home position. The same reference numerals as inFIGS. 4 and 5are used to denote those elements performing the same or similar function, and detailed descriptions thereof are omitted.

Referring toFIG. 7, a carrier locking apparatus includes a locking lever260pivotably installed at a main frame120of a printer, a paramagnetic metal plate268provided at a rear end264of the locking lever260, a hook270provided at the carrier110, an elastic member280to apply an elastic force to the locking lever260, and an electromagnet290to restrain pivoting movement of the locking lever260.

A pivot pin261is installed at an external side surface of the main frame120, and the locking lever260is assembled to the pivot pin261at about the middle of the locking lever260. When the carrier110is parked at the home position, the hook270is engaged by a leading end262of the locking lever260. According to one aspect, the metal plate268is provided at the rear end264of the locking lever260. According to another aspect, the metal plate268is attached to the rear end264of the locking lever260as a separate member. According to yet another aspect, the locking lever260is made of paramagnetic metal and, the metal plate268is unnecessary, since the rear end264of the locking lever260is attracted to and connects to the leading ends of cores291of an electromagnet290as described below.

According to one aspect, the hook270is provided at a front right edge portion of the carrier110. A hooking projection272that engages the leading end of the locking lever260projects upward at an end of the hook270. According to one aspect, the upper surface of the hooking projection272is an inclined surface.

The elastic member280is connected to the locking lever260at a predetermined position, and applies an elastic force to the locking lever260in one direction, i.e., in a direction in which the locking lever260is disengaged from the hook270. According to one aspect, when the elastic member280is installed at an upper side of the locking lever260, as shown inFIG. 7, a tension spring is used as the elastic member280. According to another aspect, when the elastic member280is installed at a lower side of the locking lever260, a compression spring is used as the elastic member280. The elastic member280serves to move the leading end262of the locking lever260upward, and various types of springs can perform such a job and be used as the elastic member280, for example, a leaf spring.

The electromagnet290has the structure shown inFIGS. 6A and 6B, as in the first embodiment. The electromagnet290is fixedly installed on an outer side surface of the main frame120with screws224, and the leading ends of the cores291are positioned at the upper end of the vertical movement path of the metal plate268. Thus, when the locking lever260pivots counter-clockwise, and the metal plate268is raised, the metal plate268contacts the leading ends of the cores291.

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 lever260is changed. Accordingly, the direction of disposing the elastic member280and the electromagnet290are changed to a direction opposite to that shown in FIG.7.

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 toFIGS. 7 and 8.

As shown inFIG. 7, when the carrier110is parked at the home position, the metal plate268attached to the rear end264of the locking lever260is attracted and attached to the leading ends of the cores291of the electromagnet290, and the hooking projection272of the hook270is engaged by the leading end262of the locking lever260. At this time, the electromagnet290is not connected to the electric power source, and, accordingly, since a magnetic field is set up by the permanent magnet292around the leading ends of the cores291, the metal plate268is attracted to and contacts the leading ends of the cores291. Thus, since the pivoting movement of the locking lever260is restrained by the magnetic force of the permanent magnet292, the hook270remains engaged with the locking lever260, and resists external impacts or vibrations applied to the carrier110. Accordingly, the carrier110remains in the home position.

Next, when the carrier110is moved forward (in the direction of arrow F) from the home position to perform a printing job, as shown inFIG. 8, the electromagnet290is connected to an electric power source, and the magnetic field induced by the coils294offsets the magnetic field set up by the permanent magnet292around the leading ends of the cores291. Accordingly, the metal plate268detaches from the leading ends of the cores291, and the locking lever260pivots clockwise due to the elastic force of the elastic member280. Further, the leading end262of the locking lever260moves upward, and the hook270disengages from the leading end262of the locking lever260and moves forward in the direction of arrow F together with the carrier110. When the hook270is completely disengaged from the leading end262of the locking lever260, the electromagnet290is disconnected from the electric power source. Accordingly, the magnetic field set up by the permanent magnet292around the leading ends of the cores291of the electromagnet290attracts the metal plate268, which moves upward, and pivots the locking lever260counter-clockwise.

When the printing job is completed, the carrier110moves backward in the direction of arrow R. According to one aspect, the hook270then elastically deforms slightly as the hook270pushes the leading end262of the locking lever260. According to another aspect, the leading end262of the locking lever260then elastically deforms slightly as the hook270pushes the lead end262of the locking lever260. Then, the hooking projection272of the hook270engages the leading end262of the locking lever260and thus, the carrier110returns to the locking state shown in FIG.7.

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.

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.

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.

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.

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.