Ink passages, platens for an inkjet recording device, and inkjet recording devices

According to an embodiment of the present invention, an ink passage comprises an ink passage comprising a first surface; and a second surface; wherein ink flows in an ink flow direction from the first surface to the second surface, and wherein a downstream edge of the first surface and an upstream edge of the second surface intersect each other.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority from Japanese Patent Application No. 2007-282132, which was filed on Oct. 30, 2007, the disclosure of which is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to an ink passage having a first surface and a second surface which are adjacent to each other in an ink flow direction. In particular, the present invention is directed toward a platen for an inkjet recording device and an inkjet recording device in which ink droplets selectively ejected from a recording head smoothly are guided from the first surface to the second surface.

2. Description of Related Art

A known inkjet image recording device records an image on a recording sheet, e.g., a recording medium, by ejecting ink onto the recording sheet. The known inkjet recording device includes an inkjet recording head, and selectively ejects ink droplets from nozzles of the recording head. The ink droplet reaches the recording sheet, and a desired image is recorded on the recording sheet. In the known inkjet recording device, a plurality of recording sheets are stored in a feed cassette or a feed tray, and when printing is to be performed, a recording sheet is fed to a position directly below the recording head. A platen for an inkjet recording device is positioned directly below the recording head to support the recording sheet, such that the recording sheet faces the recording head.

As the accuracy of printing increases, a size of an ink droplet to be ejected from the recording head decreases, which may cause a small ink droplet that has not reached the recording sheet to float above the recording sheet. This floating ink droplet may be known as an ink mist. The ink mist may adhere to peripheral members of the recording head, such as the platen. Some of ink droplets ejected from the recording head may not reach the recording sheet, but may reach the platen, which is especially noticeable when printing is performed without a margin provided at an edge of the recording sheet. When the ink droplets adhere to the platen, the adhered ink droplets may be transferred to a subsequently fed recording sheet, and thus, the subsequent recording sheet may be contaminated, or an image formed on the subsequent recording sheet may be deteriorated, or both.

In another known inkjet image recording device, such as the inkjet image recording device described in Japanese Unexamined Patent Application Publication No. 2007-175971, an ink passage, such as a groove, is formed in an upper surface and a sidewall of a platen, and ink adhering to the upper surface of the platen is guided to a back surface of the platen by the ink passage. Because ink is removed from the upper surface of the platen, the ink may be prevented from adhering to the subsequently fed recording sheet. The ink guided to the back surface of the platen is further guided to an ink absorber, and is absorbed thereby.

A known platen may have a flat-plate shape and may include a synthetic resin, such as polystyrene or ABS. The known platen may be formed using by injection molding. A synthetic resin molded product is made by molding synthetic resin in a mold. For example, in two-plate molding, a mold is divided into two fixed and movable molds, and these molds are clamped with a predetermined amount of pressure to form a cavity. Heated and melted synthetic resin is injected into the cavity to make a synthetic resin molded product, the molded product is cooled, then the two molds are opened, and the synthetic resin molded product is removed. A mating surface of the two molds is known as a parting surface. A step-like mark is left on the synthetic resin molded product at an edge of the parting surface due to a minute displacement of the two molds from each other. For example, when a flat-plate platen is made by injection molding using a two-plate mold, a step-like mark generally is left at a side wall of the flat-plate platen. If a step-like mark is generated across the above-described ink passage, the flow of ink is interrupted by the step-like mark, and the ink accumulates at the edge of the parting surface.

For example, as shown inFIG. 9A, when a step-like mark102is formed substantially at a center portion of a side wall101of a platen100, such that an upper side wall104horizontally protrudes beyond a lower side wall105, the contact angle with respect to the side wall101of the ink droplet103, which moves downward along the upper side wall104by a gravitational force, changes at the step-like mark102, and a surface tension acting on the ink droplet103, which acts to move the ink droplet103back to the upper side, increases. As a result, the ink droplet103remains at the step-like mark102. Thus, in order to move the ink droplet103beyond the step-like mark102toward the lower side wall105, an amount of drive force applied to the ink droplet103may need to be increased.

Similarly, as shown inFIG. 9B, when a step-like mark102is formed substantially at the center portion of the side wall101of the platen100, such that the lower side wall105horizontally protrudes beyond the upper side wall104, the ink droplet103, which moves downward along the wall surface of the upper side wall104by a gravitational force, is supported by and remains on a horizontal surface of the step-like mark102. When the size of the ink droplet103increases, the ink droplet attempts to move to the lower side wall105from the horizontal surface. At this time, the contact angle of the ink droplet103with respect to the side wall101changes, and the surface tension acting on the ink droplet103, which acts to move the ink droplet103back to the horizontal surface, increases. As a result, the ink droplet103remains at the step-like mark102. Thus, in order to move the ink droplet103beyond the step-like mark102toward the lower side wall105, an amount of drive force applied to the ink droplet103may need to be increased.

As described above, when the ink accumulates at the step-like mark102on the side wall101of the platen100, the flow of the ink from a front surface to a back surface of the platen100may be interrupted, and consequently, a recording sheet may be contaminated, or an image formed on the recording media may be deteriorated, or both.

SUMMARY OF THE INVENTION

Therefore a need has arisen for ink passages, platens and inkjet recording devices which overcome these and other shortcomings of the related art. A technical advantage of the present invention is that a recording sheet may not be contaminated and an image formed on the recording sheet may not be deteriorated from ink adhering to the platen.

According to an embodiment of the present invention, an ink passage comprises an ink passage comprising a first surface; and a second surface; wherein ink flows in an ink flow direction from the first surface to the second surface, and wherein a downstream edge of the first surface and an upstream edge of the second surface intersect each other.

According to another embodiment of the present invention, a platen comprises a front surface configured to support thereon a recording medium; and a plurality of ink passages each comprising a first surface; and a second surface; wherein ink flows in an ink flow direction from the first surface to the second surface, and wherein a downstream edge of the first surface and an upstream edge of the second surface intersect each other.

According to yet another embodiment of the present invention, an inkjet recording device comprises a recording head configured to eject ink; and a platen comprising a front surface configured to support thereon a recording medium; and a plurality of ink passages each comprising a first surface; and second surface; wherein ink flows in an ink flow direction from the first surface to the second surface, and wherein a downstream edge of the first surface and an upstream edge of the second surface intersect each other.

Other advantages of the present invention will be apparent to persons of ordinary skill in the art in view of the following detailed description of the invention and the accompanying drawings.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention may be understood by referring toFIGS. 1-8, like numerals being used for like corresponding parts in the various drawings.

Referring toFIG. 1, a multi-function device10may comprise a printer11and a scanner12, and may be configured to perform a print function, a scan function, a copy function, or a facsimile function, or any combination thereof. The printer11may be an inkjet recording device, according an embodiment of to the present invention.

The printer11may be connected to an external information device, such as a computer or a digital camera. The printer11may be configured to record an image e.g., text, on a recording sheet, e.g., a recording medium, in accordance with print data transmitted from the external information device. A storage medium, such as a memory card, may be inserted into the multi-function device10. The printer11may record an image on a recording sheet in accordance with print data stored in the storage medium.

The multifunction device10may be a substantially rectangular parallelepiped, and may have a larger width and depth than a height. A lower portion of the multi-function device10may be the printer11. The multi-function device10may have an opening13formed in a front surface thereof. A feed tray20and a discharge tray21may be positioned vertically in the opening13at two stages.

An upper portion of the multi-function device10may be a scanner12. The scanner12may be a flatbed scanner.

An operation panel15may be positioned at an upper portion of the front surface of the multi-function device10. A user may use the operation panel15to operate the printer11and the scanner12, and may comprise a plurality of operation buttons and a liquid crystal display. The multi-function device10may be operated in accordance with an operation instruction from the operation panel15. When the multifunction device10is connected to the external information device, the multi-function device10also may be operated in accordance with an instruction transmitted from the external information device through a printer driver or a scanner driver. In addition, a slot unit16may be positioned at an upper left portion of the front surface of the multifunction device10. The memory card may be inserted to the slot unit16, and data in the memory card may be read or data may be written in the memory card.

Referring toFIG. 2, the feed tray20may be positioned adjacent to a bottom of the multi-function device10. The feed tray20may hold recording sheets of various sizes, including A4 size or sizes which are smaller than A4 size.

Referring toFIG. 3, a feed roller25may be positioned above the feed tray20. The feed roller25may feed recording sheets positioned on the feed tray20to the sheet conveying path23. The feed roller25may be supported at a tip end of an arm26. The feed roller25is rotationally driven by a motor (not shown) via a drive force transmission mechanism27provided along the arm26. The drive force transmission mechanism27may comprise a plurality of gears which mesh with each other.

The arm26may be supported by a shaft28at a base end of the arm26, and may be pivotable around the shaft28. With pivot of the arm26, the feed roller25may be vertically moved relative to the feed tray20to selectively be in contact with and separated from the feed tray20. The arm26may be pivoted downward by a weight of the arm26or a biasing force of a spring or the like. When the arm26is pivoted downward, the feed roller25may apply a force to the recording sheets on the feed tray20. When the feed roller25is rotated in this state, the uppermost recording sheet may be fed to a separation plate22positioned in a deep portion of the feed tray20.

The sheet conveying path23may extend from the upper side of the separation plate22upward and make U-turn to a discharge tray21arranged above the fed tray20. An arcuate portion17of the sheet conveying path23may be defined by an outer guide member18and an inner guide member19which face each other and are fixed to a device frame. A recording sheet may be conveyed from the feed tray20toward a print unit24, and the recording sheet with a desired image recorded thereon may be discharged to the discharge tray21.

The print unit24may be arranged downstream of the arcuate portion17in a sheet conveying direction in the sheet conveying path23. The print unit24may comprise a carriage38and an inkjet recording head39. The recording head39may be mounted on the carriage38. The carriage38may be reciprocated in a horizontal direction orthogonal to the sheet conveying direction. Though not shown inFIG. 3, ink cartridges may be arranged in the multi-function device10separately from the recording head39. The recording head39may be supplied with color inks of cyan (C), magenta (M), yellow (Y), and black (Bk) from the ink cartridges through ink tubes.

Though not shown, the recording head39may comprise a plurality of nozzles in a lower surface thereof. The nozzles may be arranged in a line in the sheet conveying direction, e.g., a left-right direction inFIG. 3, for each of the color inks of C, M, Y, and Bk. A piezoelectric element provided in each nozzle may vibrate and an ink droplet of a color ink may be ejected from each nozzle. While the carriage38is reciprocated, the color inks may be selectively ejected from the recording head39as relatively small ink droplets. Accordingly, an image may be recorded on a recording sheet being conveyed onto a platen42.

A pair of guide rails43and44may be arranged above the sheet conveying path23, separated from each other by a predetermined distance in the sheet conveying direction.

The carriage38may be arranged to bridge over the guide rails43and44, and may be slidable in the longitudinal direction of the guide rails43and44, e.g., in the direction orthogonal to the sheet conveying direction. The carriage38may be reciprocated on the guide rails43and44by a belt drive mechanism46disposed on an upper surface of the guide rail44.

The platen42may be positioned below the guide rails43and44and may face the recording bead39and may overlap a center portion of the carriage reciprocating range, where a recording sheet passes. The platen42may have a width sufficiently larger than a maximum width of a recording sheet to be conveyed by the printer11. Thus, both edges in a width direction of the recording sheet to be conveyed pass over the platen42.

A conveying mechanism for conveying a recording sheet may comprise a convey roller60, a pinch roller, a discharge roller62, a spur roller63, and the feed roller25.

The convey roller60and the pinch roller may be positioned upstream of the print unit24in the sheet conveying direction. The convey roller60and the pinch roller may convey a recording sheet conveyed through the sheet conveying path23onto the platen42.

The discharge roller62and the spur roller63may be positioned downstream of the print unit24in the sheet conveying direction. The discharge roller62and the spur roller63may convey a recording sheet with an image recorded thereon to the discharge tray21. The convey roller60and the discharge roller62may be rotated synchronously and intermittently, such that a recording sheet may be intermittently conveyed by a predetermined linefeed width.

Referring toFIG. 4, the platen42may have a substantially flat-plate shape, and may be arranged, such that a front surface70thereof faces a lower surface of the recording head39. A longitudinal direction of the platen42may be parallel to a sheet width direction, e.g., the direction indicated by arrow50. InFIG. 4, the sheet conveying direction is indicated by arrow51.

Referring toFIGS. 4 and 5, the platen42may comprise a frame71, ribs72and73positioned at the frame71, and movable ribs74slidably positioned at the frame71. The frame71may be a molded product comprising a synthetic resin by injection molding. The frame71may have a substantially C-shaped cross section and may open downward. A drive mechanism for driving the movable ribs74may be positioned within the frame71.

The ribs72and73may be positioned at the front surface70of the frame71. The front surface70may face the recording head39. The ribs72may be arranged at a predetermined interval in a longitudinal direction of the platen42, adjacent to an upstream edge of the front surface70in the sheet conveying direction. The ribs72may protrude upward toward the recording head39. The ribs73may be arranged at predetermined intervals in the longitudinal direction50of the platen42adjacent to a downstream edge of the front surface70in the sheet conveying direction. The ribs73may protrude upward toward the recording head39.

A plurality of slits75may be formed in the front surface70of the frame71, and may extend in the sheet conveying direction. The slits75may be arranged at a predetermined interval in the longitudinal direction of the platen42. The slits75may extend in the sheet conveying direction. The movable ribs74may protrude upward from the front surface70toward the recording head39through the slits75. The movable ribs74may be configured to slide in the sheet conveying direction within the slits75.

A recording sheet conveyed onto the platen42may be supported by the ribs72and73and the movable ribs74to face the recording head39. The ribs72and73and the movable ribs74may have substantially the same protruding heights. The recording sheet may be supported, such that a recording surface thereof is parallel to the lower surface of the recording head39in a lifted manner from the front surface70.

Referring toFIGS. 5-8, ink passages80may be provided in the platen42from the front surface70to a back surface77via side walls76. The ink passages80may be defined by a surface groove78, a first groove81, a second surface48, and a second groove82. The first groove81may be defined by a first surface83and a third surface85. In the ink passage80, a gravitational force and/or a capillary force may be a drive force for ink to flow. The ink that has received the drive force may be guided from the front surface70to the back surface77of the platen42via the ink passage80.

Referring toFIG. 5, the surface grooves78may be formed in the front surface70of the platen42. The surface grooves78may extend between adjacent two slits75and may have a substantially V-shaped vertical cross section. The surface groove78may be recessed from the front surface70toward the back surface77(seeFIG. 7), and may extend in the direction orthogonal to the sheet conveying direction. The surface grooves78may be arranged side by side in the sheet conveying direction. Both ends of the surface grooves78may be open toward the corresponding slits75, and define the first grooves81.

Two side walls76may face each other in the direction orthogonal to the sheet conveying direction, with the slit75interposed therebetween. The side walls76may extend from the front surface70to the back surface77, and may be orthogonal to the front surface70and the back surface77. Referring toFIGS. 6 and 7, the first grooves81may be formed in the side wall76adjacent to the front surface70, and the second surfaces84and the second grooves82may be formed in the side wall76adjacent to the back surface77. Each of the first grooves81and the corresponding second surface48and second groove82may define a portion of the ink passage80extending from the front surface70to the back surface77.

The first grooves81may be arranged in the side wall76side by side along the front surface70. The first grooves81are respectively provided for the surface grooves78. An end of each surface groove78may be connected to a corresponding one of the first grooves81. The first groove81may have a substantially V-shaped horizontal cross section, and may be recessed from the side wall76in an extending direction of the surface groove78. The first groove81may extend from the front surface70toward the back surface77substantially vertically, and reach a substantially center portion of the side wall76, i.e., a boundary87between the first and third surfaces83and85, and the second surface84.

Referring toFIG. 8, the first groove81may be defined by the first surface83and the third surface85which intersect each other to form a substantially V-shaped groove. The first and third surfaces83and85may be flat surfaces, and may be connected to respective surfaces of the substantially V-shaped surface groove78. A deep portion79of the surface groove78may be connected to a deep portion86of the first groove81, such that the ink may be guided from the surface groove78to the first groove81substantially horizontally along the respective surfaces of the surface groove78, and substantially vertically along the first and third surfaces83and85.

Referring toFIGS. 6 and 7, the second surfaces84may be provided in the side wall76adjacent to the back surface77. Each of the second surfaces84may be a flat surface intersecting the first and third surfaces83and85of the corresponding first groove81, and extending from a downstream edge of the first groove81to the back surface77. The second surface84also may be a surface defining a portion of the ink passage80. The ink flowing from the first and third surfaces83and85may be guided substantially vertically along the second surface84. The first and third surfaces83and85may be located upstream and the second surface84may be located downstream in the ink flow direction.

Referring toFIG. 8, an upstream edge of the second surface84obliquely may intersect downstream edges of the first and third surfaces83and85(the intersection points are hereinafter referred to as ink guide portions90). Thus, connecting surfaces and ink guide portions90may be formed at the boundary87between the first and third surfaces83and85and the second surface84. As the connecting surfaces, a horizontal surface88may be formed adjacent to the deep portion86of the first groove81, and two horizontal surfaces89may be formed adjacent to two portions of the first groove81that protrude beyond the second surface84. The horizontal surface88may face an upstream side in the ink flow direction. The horizontal surfaces89may face a downstream side in the ink flow direction. The downstream edge of the first surface83may comprise an edge of the horizontal surface88and an edge of one of the horizontal surfaces89. The upstream edge of the second surface84may comprise another edge of the horizontal surface88and another edge of the one of the horizontal surface89. Other than at the ink guide portions90, the second surface84may be indirectly connected to the first surface83via the horizontal surface88and one of the two horizontal surfaces89, and may be indirectly connected to the third surface85via the horizontal surface88and the other of the two horizontal surfaces89. One ink guide portion90may be formed at an intersection point between the first surface83and the second surface84and shared by the horizontal surface88and one of the two horizontal surfaces89. Another ink guide portion90may be formed at an intersection point between the third surface85and the second surface84and shared by the horizontal surface88and the other of the two horizontal surfaces89.

The boundary87may correspond to a parting surface when the platen42is made by injection molding. For example, when a two-plate mold is used, a portion comprising the front surface70of the platen42corresponds to a movable mold and a portion comprising the back surface77corresponds to a fixed mold. The movable mold and the fixed mold meet along a mating surface, i.e., a parting surface. Surfaces for forming the first and third surfaces83and85, which are provided at the movable mold, intersect, on the parting surface, a surface for forming the second surface84, which is provided at the fixed mold. The ink guide portions90may be formed at the intersection points on the border87.

Referring toFIGS. 6 and 7, the second grooves82may be formed in the side wall76adjacent to the back surface77. The second grooves82may extend straight from a corresponding one of the horizontal surfaces89formed at the boundary87to the back surface77. The second groove82may be connected to the horizontal surface89at a portion other than the ink guide portions90. The second groove82may have a substantially V-shaped horizontal cross section, and may be recessed in the same direction as that of the first groove81. The second surfaces84may be arranged in the side wall76alternatively with the second grooves82.

Next, the flow of ink in the ink passage80is described. The ink passage80may be defined by the surface groove78, the first groove81, the second surface84, and the second groove82, in that order from the front surface70of the platen42. Ink adhering to the front surface70of the platen42may accumulate in the surface groove78, and may begin flowing along the ink passage80by a gravitational force and/or a capillary force as a drive force acting on the ink. The drive force may be, for example, a capillary force at the surface groove78, a capillary force and a gravitational force at the first and second grooves81and82, or a gravitational force at the second surface84, or any combination thereof. Nevertheless, the drive force does not have to be generated in the entire area of the ink passage80.

Referring toFIG. 8, in the side wall76, the first and third surfaces83and85defining the first groove81and the second surface84may be arranged adjacent to each other in the ink flow direction. The first and third surfaces83and85may be located upstream from the second surface84in the ink flow direction, to define a portion of the ink passage80. In the side wall76, the ink flows from the first and third surfaces83and85onto the second surface84by a drive force, such as a gravitational force. In the first groove81, the ink may flow mainly along the deep portion86of the first groove81. Because the horizontal surface88, which faces upstream of the ink flow direction, is provided at the boundary87, the ink flowing down along the deep portion86temporarily may remain on the horizontal surface88. When the volume of the ink remaining on the horizontal surface88increases, the ink on the horizontal surface88reaches the ink guide portions90. Because the first and third surfaces83and85directly may be connected, at the ink guide portions90, to the second surface84, the contact angle of the ink remains unchanged with respect to the first and third surfaces83and85and with respect to the second surface84. Consequently, the surface tension acting on the ink remaining on the horizontal surface88may not increase, such that the ink may not require a larger drive force to move beyond the ink guide portion90than a drive force required when the ink moves on the horizontal surface88. Accordingly, the ink on the horizontal surface88may move to the second surface84via the ink guide portions90.

The ink may move to the second surface84from the ink guide portions90, and move along the boundary87and along corner portions of the second surface84and the two horizontal surfaces89while receiving a gravitational force that drives the ink to move along the second surface84. If the gravitational force acting on the ink is relatively large, the ink may move along the second surface84and reach the back surface77. Even when the gravitational force acting on the ink is not relatively large, the ink may move along the corner portions of the second surface84and the horizontal surfaces89, and reach the second grooves82on either side of the second surface84. When the ink flows into the second grooves82, a gravitational force and a capillary force may act on the ink, and thus, the ink may reach the back surface77along the second grooves82. As described above, the ink adhering to the front surface70of the platen42may flow along the ink passage80to the back surface77. Though not shown in the drawings, an ink absorber, such as felt, may be positioned adjacent to a downstream edge of the ink passage80to absorb the ink guided by the ink passage80.

As described above, the first and third surfaces83and85, and the second surface84partially define the ink passage80, and the ink guide portions90may be provided at the boundary between the first and third surfaces83and85, and the second surface84, such that the first and third surfaces83and85directly are connected to the second surface84at the ink guide portions90. Accordingly, the ink remaining on the horizontal surface88may move smoothly onto the second surface84via the ink guide portions90. Consequently, ink droplets having not reached a recording sheet and adhering to the front surface70of the platen42may be guided through the ink passage80to the back surface77, thereby preventing a subsequently fed recording sheet from being contaminated, or preventing an image recorded on the subsequently fed recording sheet from being deteriorated, or both.

In addition, because the boundary87corresponds to a parting surface when the platen42comprises a synthetic resin formed by injection molding, the ink passage80may be formed in the platen42, such that the ink flows across an edge of the parting surface.

In particular, when the flat-plate platen42is formed by injection molding, an edge of a parting surface generally is located at the side wall76. Thus, the ink passage80may be formed at the side wall76, such that the ink flows across the edge of the parting surface through the ink guide portions90even when the positions of the ink guide portions90vary slightly due to a minute displacement of two molds from each other.

The first and third surfaces83and85define the first groove81. A plurality of the first grooves81may be arranged side by side in the side wall76. The second surface84may be formed as a flat surface intersecting the first and third surfaces83and85of a corresponding one of the first grooves81. Accordingly, two ink guide portions90readily may be provided in each of the first grooves81.

In addition, in the side wall76, a plurality of the second grooves82may be formed to extend downstream from the boundary87in the ink flow direction. The ink flowing through the ink guide portions90may be guided smoothly to the back surface77along the second grooves82.

In another embodiment, the third surface85may not be provided in the ink passage80, and at least a single ink guide portion90may be provided at the second surface84.

In another embodiment, the first surface83and the second surface84may be circumferential surfaces of cylinders having the same diameter, and the cylinders may be arranged adjacently in an axial direction while their axes are unaligned with each other.

In yet another embodiment, the ink passage80may be formed in a member other than the platen, e.g., to have an ink passage across a parting surface.

While the invention has been described in connection with preferred embodiments, it will be understood by those of ordinary skill in the art that other variations and modifications of the preferred embodiments described above may be made without departing from the scope of the invention. Other embodiments will be apparent to those skilled in the art from a consideration of the specification or practice of the invention disclosed herein. It is intended that the specification and the described examples only are considered as exemplary of the invention, with the true scope of the invention being defined by the following claims.