Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1999-11-02
2001-06-05
Le, N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S029000
Reexamination Certificate
active
06241336
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an ink-jet printer which has a purge unit for preventing ink-discharge failure or defective ink-discharge.
DESCRIPTION OF THE RELATED ART
An ink-jet printer is generally used for performing dot-matrix recording on a sheet of printing paper supplied and fed from a paper feeder by discharging ink droplets. However, the ink-jet printer sometimes undergo ink-discharge failure or defective ink-discharge. Such ink-discharge failure or defective ink-discharge is caused by various reasons including, for example, adhesion of dust to a nozzle tip for discharging ink droplets, immixture of bubbles in an ink supplied from an ink source, drying of the ink in a nozzle, and adhesion of paper dust from a recording medium to the nozzle during printing.
Accordingly, in order to provide a restoring unit for dissolving the ink-discharge failure or the defective ink-discharge so that a normal state is restored, it has been hitherto known to provide a purge unit having a suction cap which covers a nozzle surface of a printing head so that an ink is sucked from the printing head by the aid of a suction pump (see Japanese Patent Laid-Open No. 61-118255). Specifically, a cap slider for holding the suction cap is slidably engaged into a cap holder. The cap slider is allowed to make sliding movement with respect to the cap holder. Thus the suction cap is allowed to abut against the nozzle surface of the printing head.
However, in the case of the restoring unit or the purge unit as described above, the cap slider is slidably engaged into the cap holder with practically no play allowed to exist therebetween, in order to allow the suction cap to abut against the nozzle surface of the printing head with a high degree of positional accuracy. Therefore, if the cap surface of the suction cap has a low degree of parallelism with respect to the nozzle surface of the printing head, tight contact is poorly achieved when the suction cap is allowed to abut against the printing head, making it impossible to satisfactorily suck the ink from the nozzle.
An ink-jet printer is known, which is installed with a protective cap for covering a printing head in order to prevent a nozzle surface from drying when recording or printing is not performed. Such an ink-jet printer has had a problem in that the ink is dried if tight contact is poorly achieved between the protective cap and the printing head.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an ink-jet printer which makes it possible to allow a suction cap to make tight contact with a nozzle surface of a printing head when the suction cap is pressed against the printing head regardless of an inclination of a surface of the suction cap with respect to the nozzle surface of the printing head.
Another object of the present invention is to provide an ink-jet printer which makes it possible to allow a protective cap to make tight contact with a nozzle surface of a printing head when the protective cap is pressed against the printing head regardless of an inclination of a surface of the protective cap with respect to the nozzle surface of the printing head.
According to a first aspect of the present invention, there is provided an ink-jet printer comprising:
a printing head having a nozzle discharging ink droplets and printing an image on a printing medium at a printing area with the ink droplets;
a carriage holding the printing head, which is reciprocatively movable along a surface of a sheet subjected to printing; and
a cap unit comprising a cap covering the printing head, a cap-moving mechanism moving the cap frontward or rearward with respect to the printing head, and a swinging mechanism swinging a cap surface in response to an inclination of a printing head surface so that the cap surface makes tight contact with the printing head surface when the cap is pressed against the printing head surface.
The ink-jet printer of the present invention has the swinging mechanism swinging the cap surface of the cap unit in response to the inclination of the printing head surface. Therefore, the condition of tight contact between the cap and the printing head is remarkably improved when the cap covers the nozzle surface of the printing head after the cap is moved by the cap-moving mechanism from a waiting position at which the cap is retracted from a passage for movement of the printing head to a protruding position at which the cap protrudes into the passage for movement of the printing head.
The ink-jet printer of the present invention may further comprise a purge unit connected to the cap, for sucking the ink remaining in the nozzle of the printing head through the cap. The purge unit can suck the ink in the printing head through the cap while the cap makes tight contact with the printing head to cover the nozzle surface. In a preferred embodiment, the swinging mechanism may comprise a cap holder supporting the cap at the front end of the cap holder, a casing accommodating the cap holder with a play allowed to exist between the cap holder and the casing, and a resilient member connected to the cap holder so that the cap holder is urged toward the printing head. The cap holder is urged toward the printing head by the aid of the resilient member, and the casing accommodates the cap holder with the play allowed to exist between the cap holder and the casing. Accordingly, when the cap holder is non-uniformly pressed against the printing head, the front surface of the cap holder can swing depending on the inclination of the surface of the printing head so as to make tight contact with the surface of the printing head.
The cap holder may have an engaging projection at its front end and a fastening section avoiding disengagement from the casing at its back end respectively, and the casing may have a regulating projection disengageably engaging the engaging projection of the cap holder to regulate a relative positional relationship between the cap holder and the casing. By adopting such a structure, the cap holder is integrated with the casing by the aid of the urging force exerted by the resilient member when the cap is not pressed against the printing head. Accordingly, the cap held by the cap holder can be positioned with respect to the nozzle surface of the printing head with high positional accuracy when the casing makes sliding movement with respect to a frame member and the cap abuts against the nozzle surface.
The cap-moving mechanism may comprise an eccentric cam and an eccentric cam-engaging section connected to the casing. In this embodiment, the casing accommodating the cap is movable frontward or rearward with respect to the printing head in accordance with rotation of the eccentric cam.
The cap of the cap unit to be used in the ink-jet printer of the present invention may be a protective cap covering the nozzle of the printing head to avoid evaporation of the ink. Because the protective cap can swing in response to an inclination of the surface of the printing head, the printing head can be reliably covered to avoid evaporation of the ink. In a preferred embodiment, the swinging mechanism may comprise a holding frame supporting the protective cap at the front end of the holding frame, a movable housing accommodating the holding frame with a play allowed to exist between the holding frame and the movable housing, and a resilient member connected to the holding frame so that the holding frame is urged toward the printing head. The holding frame is urged toward the printing head by the aid of the resilient member, and the movable housing accommodates the holding frame with the play allowed to exist between the holding frame and the movable housing. Accordingly, when the protective cap is non-uniformly pressed against the printing head, the front surface of the protective cap can swing to make tight contact with the surface of the printing head.
The holding frame may have an engaging projection at its front end and a fastening section avoiding disengagement from the movable housing at its back end
Brother Kogyo Kabushiki Kaisha
Le N.
Oliff & Berridg,e PLC
Pham Hai C.
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