Pulley holder and a drive transmission mechanism and an image recording apparatus using the pulley holder

A pulley holder for rotatably supporting a pulley around which a belt is wound, in which the pulley holder includes a shaft having a shaft body for supporting the pulley and a projection at least one end of the shaft body in its axial direction, and a holder body having a bearing for supporting the shaft body, and a fitting part for fitting the projection. Since the projection is biased from an axis of the shaft body, once the projection is fit into the fitting part, the shaft body would not rotate around the axis. Accordingly, a friction wear of the bearing of the holder body is prevented and thus a shift in conveying a carriage is prevented.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Nonprovisional application claims priority under 35 U.S.C. §119(a) on Patent Application No. 2005-380674 filed in Japan on Dec. 29, 2005, the entire contents of which are hereby incorporated by reference.

BACKGROUND

The present invention relates to a pulley holder for supporting rotatably a pulley around which a belt is to be wound, and a drive transmission mechanism and an image recording apparatus using this pulley holder.

In an ink jet type image recording apparatus, the drive transmission mechanism that transmits a driving force to a carriage which is supported in a slidable manner in a predetermined direction has been conventionally known (see Japanese Patent Application Laid-Open No. 2005-313492).FIG. 1Aillustrates a plan view of a known drive transmission mechanism220.FIG. 1Billustrates a front view ofFIG. 1A. The drive transmission mechanism220has such a structure that a driving pulley unit233and a driven pulley unit223are provided on a frame221such that the driving pulley unit233and the driven pulley unit223are positioned apart by a predetermined distance and an endless belt222is stretched between the units.

The driving pulley unit233includes a motor236arranged on a lower surface221bof the frame221, a motor shaft235that pierces through the frame221from the lower surface221bto an upper surface221aof the frame221, and a driving pulley234coupled to the motor shaft235. Further, the driven pulley unit223includes a pulley holder225secured to the frame221and a driven pulley224. The belt222is stretched between the driving pulley234and the driven pulley224. A rotatable force of the driving pulley234allows the belt222to circle around the pulleys. The belt222circling around the pulleys is coupled to the carriage and thus the carriage moves in association with the circular movement of the belt222in a predetermined direction.

FIGS. 2A and 2Billustrate enlarged detailed views of the driven pulley unit223.FIG. 3illustrates a cross sectional view ofFIG. 2Btaken along a line III-III. The pulley holder225generally includes a supporting arm229that supports the driven pulley224in a rotatable manner, an inserted part238that is inserted into an insertion hole241provided in the frame221(seeFIG. 4), and a restricting part226that restricts a downward movement of the inserted part238. InFIGS. 2A and 2B, a lower part of a lower surface226aof the restricting part226in the drawing sheet is the inserted part238. The inserted part238is provided with a stop part227projecting perpendicularly to the drawing sheet surface ofFIGS. 2A and 2B. Further, a groove228is provided between the stop part227and the restricting part226to receive a corresponding fitting edge242(seeFIG. 4) that is formed at an edge part of the insertion hole241. Bottom surfaces230of the grooves228are angled with a predetermined draft angle φ.

In the pulley holder225having the above described structure, the inserted part238is inserted into the insertion hole241and the pulley holder225slides in a leftward direction in the drawing sheet ofFIG. 4(a direction as indicated by an outlined arrow), resulting in that the fitting edges242are fit into the grooves228while the fitting edges242contacts the grooves228, respectively. As such, the pulley holder225is secured to the frame221in a vertical direction. Further, a fixture, which is not shown here, fixes the pulley holder225so as not to slide in a horizontal direction inFIGS. 2A and 2B.

SUMMARY

There are cases where a pulley body224ais formed of a synthetic resin and a shaft224bthereof is formed of a metal, and those independent members are finally formed into the driven pulley224. In such a case, there occurs a friction wear in two areas due to a sliding movement between the pulley body224aand the shaft224band between the shaft224band the pulley holder225. Specifically, a problem of the friction wear between the shaft224band the pulley holder225causes a fluctuation of a tension of the belt222and a distance between the pulleys, thereby hampering a smooth driving of the belt. Further, the problem causes a shift in conveying the carriage, resulting in a possible lowering of an image quality of the image recording apparatus.

The present invention has been made in view of the above circumstances, and therefore an object of the present invention is to provide a pulley holder that prevents a friction wear of a bearing of a holder body having a shaft for supporting a pulley, and a drive transmission mechanism and an image recording apparatus using this pulley holder.

The pulley holder according to the present invention is the one that supports a pulley in a rotatable manner, with a belt being wound around the pulley. The pulley holder according to the present invention includes a shaft having a shaft body for supporting the pulley and having a projection at least one end of the shaft body in an axial direction thereof, the projection being biased from an axis of the shaft body and projecting in the axial direction of the shaft body, a holder body having a bearing for supporting the shaft body and having a fitting part for fitting the projection.

In this pulley holder, the shaft is held by the holder body. The shaft body that supports the pulley is supported by the bearing of the holder body and the projection that is biased from the axis of the shaft body and projects from at least one end of the shaft body is fit into the fitting part of the holder body. Since the projection is biased from the axis of the shaft body, the shaft body does not rotate around the axis when the projection is fit into the fitting part. Accordingly, the friction wear of the bearing of the holder body can be prevented to thereby prevent a deviation in conveying the carriage and the lowering of the image quality.

In addition, the projection may have an axis in parallel with the axis of the cylindrical shaft body, and may be a cylindrical member having a diameter smaller than that of the shaft body. Further, the projection may be formed into one piece with the shaft body.

The pulley holder having the above stated structure is suitable to be employed in a drive transmission mechanism in which a belt is stretched between a first pulley (driving pulley) connected to a driving source and a second pulley (driven pulley) and the pulley holder is used for supporting the second pulley (driven pulley) in a freely rotatable manner.

Further, the pulley holder having the above stated structure is suitable to be employed in an ink jet type image recording apparatus in which a belt is stretched between a first pulley (driving pulley) for supplying a driving force to a carriage on which an ink jet recording head is mounted and a second pulley (driven pulley) and the pulley holder is used for supporting the second pulley (driven pulley) in a freely rotatable manner.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

The present invention will be described below with reference to drawings illustrating embodiments of the present invention. In addition, it should be appreciated that the following embodiments are mere examples, and thus modifications of the embodiments are possible without departing from the purpose of the present invention.

FIG. 5illustrates an outer appearance of a multi-function apparatus1.FIG. 6is a longitudinal cross sectional view illustrating an inner structure of the multi-function apparatus1. The multi-function apparatus1is a MFD (Multi Function Device) including a printer unit2at a lower part and a scanner unit3at an upper part thereof in an integral manner, and has a printer function, a scanner function, a copying machine function, and a facsimile machine function. The printer unit2of the multi-function apparatus1corresponds to an image recording apparatus. Therefore, the functions other than the printer function are optional, namely, the present invention can be a single function printer as the image recording apparatus without the scanner unit3which does not have the scanner function or the copying function.

The printer unit2of the multi-function apparatus1is connected to an external information device such as a computer and thereby records an image and a document on a recording paper (record medium) on the basis of a recording data containing an image data and a document data received from the computer or the like. In addition, the multi-function apparatus1may be connected to a digital camera or the like in order to record the image data output from a digital camera or the like on the recording paper, or may be provided with a storage media such as a memory card in order to record the image data stored in the storage media on the recording paper.

As illustrated inFIG. 5, the multi-function apparatus1has a generally rectangular shape of a wide-and-thin type, namely, an appearance having a width and a depth larger than a height thereof, and further has the printer unit2at the lower part thereof. The printer unit2is provided with a rectangular opening2aat a front surface. A paper feeding tray20and a paper discharging tray21are provided inside the opening2asuch that they are in tiers in an up-and-down direction. The paper feeding tray20stores a stack of paper, namely, a stack of recording paper of various sizes such as a paper size of B5 which is smaller than a paper size of A4 and a postcard size. The paper feeding tray20, as illustrated inFIG. 6, can be enlarged of its tray surface by withdrawing a sliding tray20aas required, and therefore the record medium, for example, of a legal size, can be stored therein. The recording paper stored in the paper feeding tray20is fed into the printer unit2to be recorded thereon with a predetermined image and is finally discharged to the paper discharge tray21.

The upper part of the multi-function apparatus1is the scanner unit3, which is so-called as a flat bed scanner. As illustrated inFIGS. 5 and 6, a platen glass31and an image sensor32are provided below a draft cover30as a top board of multi-function apparatus1in an opening/closing manner. A sheet of draft to be read of an image thereon is placed on the platen glass31. There is the image sensor32of which main scanning direction is a depth direction (a horizontal direction inFIG. 6) of the multi-function apparatus1below the platen glass31such that the image sensor32is movable in a to and fro direction with regard to a width direction of the multi-function apparatus1(in a perpendicular direction to the drawing sheet surface ofFIG. 6).

An upper part on the front surface of the multi-function apparatus1is provided with an operation panel4for operating the printer unit2and the scanner unit3. The operation panel4has various operation buttons and a liquid crystal display. The multi-function apparatus1is operated on the basis of an operation command from the operation panel4. When the multi-function apparatus1is connected to an external computer, the multi-function apparatus1is also operated on the basis of commands sent from a computer through a printer driver or a scanner driver. A slot unit5is provided on an upper left part of the front surface of the multi-function apparatus1. The slot unit5can receive therein various kinds of compact size memory cards as memory devices. A predetermined operation at the operation panel4enables a reading of an image data stored in a compact size memory card inserted into the slot unit5. Thus read information as to the image data is displayed on the liquid crystal display of the operation panel4and a predetermined image can be recorded on the recording paper by the printer unit2on the basis of this displayed information.

An internal structure of the multi-function apparatus1will be explained hereinafter with reference toFIGS. 5 to 14. More specifically, a structure of the printer unit2will be explained. As illustrated inFIG. 6, the paper feeding tray20is provided in the bottom of the multi-function apparatus1and an inclined separation plate22is provided in an innermost position of the paper feeding tray20. The inclined separation plate22serves to separate multi-fed recording papers from the paper feeding tray20to guide only the recording paper of the uppermost position to an upstream of a paper conveying path23. The paper conveying path23advances upwardly from the inclined separation plate22, turns toward the front side of the multi-function apparatus1and further toward the front side from a rear side of the multi-function apparatus1, and finally reaches the paper discharging tray21through an image recording unit24. Therefore, the recording paper contained in the paper feeding tray20is guided along the paper conveying path23from a lower position to an upper position in such a manner that the recording paper turns around in U-letter shape to reach the image recording unit24. Then, the recording paper is provided with an image recording by the image recording unit24and is discharged to the paper discharging tray21.

FIG. 7is a partially enlarged cross sectional view illustrating a main structure of the printer unit2.FIG. 8is a plan view illustrating a main structure of the printer unit2, in which a structure around an area from about a center of the printer unit2to a rear side of the apparatus. As illustrated inFIG. 7, a paper supplying roller25that supplies the recording paper piled in the paper feeding tray20to the paper conveying path23is provided above the paper feeding tray20. The paper supplying roller25is pivotably supported at a top end of a paper feeding arm26. The paper supplying roller25receives a driving force of a LF motor71(seeFIG. 14) to be rotated via a drive transmission mechanism27in which a plurality of gears are engaged to each other.

The paper feeding arm26is so arranged that a base shaft26aserves as a rotation axis and moves in an up-and-down direction in such a manner that the paper feeding arm26is accessible to the paper feeding tray20. The paper feeding arm26, as illustrated inFIG. 7, is rotated into a lower part of the apparatus so as to be brought into contact with the paper feeding tray20by its own weight, a spring or the like. As such, when the paper feeding tray20is inserted into or withdrawn from the apparatus, the paper feeding arm26can escape to an upper side of the apparatus. Since the paper feeding arm26is rotated into the lower part of the apparatus, the paper supplying roller25pivotably supported at a top end thereof is brought into contact with the recording paper on the paper feeding tray20. Under such condition, the paper supplying roller25is rotated, resulting in that the recording paper of the uppermost position is sent to the inclined separation plate22due to a friction force caused between a roller surface of the paper supplying roller25and the recording paper. The recording paper is guided upwardly, while a top end of the recording paper contacts the inclined separation plate22, and is finally sent to the paper conveying path23. When the recording paper of the uppermost position is sent by the paper supplying roller25, there may be a case where a recording paper immediately below the recording paper of the uppermost position is simultaneously sent due to a friction and an electrostatic therebetween; however, such a recording paper will be stopped due to a contact with the inclined separation plate22.

The paper conveying path23, at an area other than areas where the image recording unit24or the like is arranged, is composed of an outer guiding surface and an inner guiding surface which face each other and spaced apart by a predetermined distance. For example, a curving part17of the paper conveying path23at a rear side of the multi-function apparatus1is so structured that an outer guiding member18and an inner guiding member19are secured to a frame of the apparatus. In the paper conveying path23, more specifically, in an area where the paper conveying path23is curved, rotation rollers16are provided therewith in a freely rotatable manner in an axial direction that is the width direction of the paper conveying path23, with the rotation rollers16being provided such that roller surfaces of the rollers are exposed to the outer guiding surface. The rotation rollers16which are freely rotatable enables a smooth conveying of the recording paper at the curved area of the paper conveying path23where the recording paper slide contacts the guiding surface.

The paper conveying path23is provided with the image recording unit24(seeFIG. 6). The image recording unit24, as illustrated inFIG. 7, includes a carriage38on which an ink jet recording head39(seeFIG. 9) is mounted and which reciprocately moves in a main scanning direction. The ink jet recording head39is supplied with each color of inks of cyan (C), magenta (M), yellow (Y), and black (Bk) through ink tubes41(seeFIG. 8) from ink cartridges arranged in the multi-function apparatus1but independently from the ink jet recording head39. While the carriage38moves in a to and fro direction, minute ink droplets of color inks are selectively ejected from the ink jet recording head39, respectively, to record an image on a recording paper that is conveyed over a platen42. In addition,FIGS. 7 and 8do not show ink cartridges containing individual color inks.

FIG. 9is a perspective view illustrating a mechanism around the image recording unit24, in which ink tubes41and flat cables85are omitted. As illustrated inFIGS. 8 and 9, a pair of guide rails43,44extend in a direction orthogonal to a direction in which the recording paper is conveyed, with the guide rails being arranged above the paper conveying path23and spaced apart by a predetermined distance in the direction in which the recording paper is conveyed (in an up-to-down direction inFIG. 8). The guide rails43,44are provided within a housing of the printer unit2to compose a part of the frame that supports members of recorder unit2. The carriage38is placed such that it bridges over the guide rails43,44in a slidable manner in a direction orthogonal to the direction in which the recording paper is conveyed. Since the guide rails43,44are arranged in a direction generally horizontal to the direction in which the recording paper is conveyed, a height of the printer unit2can be lowered to thereby realize a thinner apparatus.

The guide rail43arranged upstream in the direction in which the recording paper is conveyed has a plate shape in which a length in the width direction of the paper conveying path23(in the horizontal direction inFIG. 8) is longer than that of the reciprocate movement area by the carriage38. The guide rail44arranged downstream of the direction in which the recording paper is conveyed has a plate shape in which a length in the width direction of the paper conveying path23is generally equal to that of the guide rail43. An end part of the carriage38upstream in a paper conveying direction is placed on the guide rail43, an end part of the carriage38downstream in the paper conveying direction is placed on the guide rail44, and thereby the carriage38is slidable in a longitudinal direction of the guide rails43,44. An edge part45of the guide rail44upstream of the paper conveying direction is bent upwardly by approximately a right angle, as illustrated inFIG. 7. The carriage38carried by the guide rails43,44holds the edge part45of the guide rail44in a slidable manner through a holding member such as a pair of rollers. Accordingly, the carriage38is positioned with regard to the direction in which the recording paper is conveyed, and is slidable in a direction orthogonal to the direction in which the recording paper is conveyed. In other words, the carriage38is slidably carried on the guide rails43,44and moves reciprocately in a direction orthogonal to the direction in which the recording paper is conveyed along the edge part45of the guide rail44. In addition, it is not illustrated inFIG. 7or8; however, the edge part45is applied with lubricant such as grease in order to help a smooth sliding of the carriage38.

A belt driving mechanism46is provided on an upper surface of the guide rail44. The belt driving mechanism46includes a driving pulley47and a driven pulley48which are provided around both ends of the recording paper conveying path23in the width direction, respectively, and an endless circular timing belt49which is provided with teeth inside thereof and is tensioned between the driving pulley47and the driven pulley48. A driving force is applied from a CR motor73(seeFIG. 9) to a shaft of the driving pulley47to allow the timing belt49for a circle movement in association with a rotation of the driving pulley47. In addition, such a belt that both ends thereof are fixed to the carriage38may be employed instead of the endless timing belt49.

FIG. 10is an enlarged view illustrating an area in the vicinity of the driven pulley48. The driven pulley48is rotatably supported by a pulley holder125that is attached to the guide rail44. The guide rail44is provided with a hole128formed therein, as illustrated inFIGS. 10 and 11. The hole128is used in order to secure the pulley holder125onto the guide rail44. A standup plate127extends in a vertical direction from an upper surface44aof the guide rail44. This standup plate127is a bracket to be used when the pulley holder125that moves in such a direction that the timing belt49is wound (a direction as illustrated by an arrow P1inFIG. 10) is elastically pressed toward such a direction that the timing belt49is tensioned by means of a coil spring126. The hole128of the guide rail44serves to slidably support the pulley holder125in the arrow P1direction. When a lower part131of the pulley holder125(seeFIG. 15B) is inserted into the hole128and is slidably moved in such a direction that the timing belt49is tensioned, namely, in a left direction on the paper inFIG. 10(in a direction of an arrow P0inFIG. 10), first fitting parts161and second fitting parts162provided on the pulley holder125, which will be explained below, (seeFIG. 15B) are fit into the first edge parts151and the second edge parts152(seeFIG. 11) of the hole128. Under this condition, the coil spring126is attached between a spring receiving part129and the standup plate127provided in the pulley holder125, with the coil spring126being pressed, and therefore, the pulley holder125is secured to the guide rail44. In addition, a shape of the hole128formed in the guide rail44and a supporting structure of the pulley holder125in the guide rail44will be explained in detail later.

The carriage38is secured at the bottom surface thereof to the timing belt49. Therefore, the carriage38is reciprocately moved on the guide rails43,44along the edge part45thereof in association with the circular movement of the timing belt49. The ink jet recording head39carried by such carriage38moves in the to and fro direction along a width direction of the recording paper conveying path23as the main scanning direction.

The guide rail44is provided with an encoder strip50of a linear encoder77(seeFIG. 14). The encoder strip50is a strip shaped one formed of a transparent resin. At both ends of the guide rail44in the width direction (in the to and fro direction of the carriage38), a pair of supporting parts33,34are formed thereon in such a manner that the supporting parts33,34stand up from an upper surface of the ends of the guide rail44. The both ends of the encoder strip50are retained by the supporting parts33,34to be tensioned along the edge part45. In addition, it is not illustrated in the drawings; however, one of the supporting parts33,34is provided with a leaf spring, which retains an end part of the encoder strip50. Owing to this leaf spring, a looseness of the encoder strip50due to an affect of the tension in a longitudinal direction can be prevented and, if an outer force is applied to the encoder strip50, this leaf spring is elastically deformed to allow the encoder strip50to be flexed.

The encoder strip50is provided with such a pattern formed thereon that a transparent part which allows light to pass therethrough and a shielding part which blocks the light are arranged alternatively in a longitudinal direction by predetermined pitches. An optical sensor35as a translucent type sensor is provided at a position on an upper surface of the carriage38corresponding to the encoder strip50. The optical sensor35moves in the to and fro direction along the longitudinal direction of the encoder strip50together with the carriage38, and the pattern of the encoder strip50is detected upon the movement in the to and fro direction. The ink jet recording head39is provided with a head controlling substrate that controls an ink ejection. The head controlling substrate outputs a pulse signal based on a detected signal of the optical sensor35, thereby judging a position and a speed of the carriage38on the basis of this pulse signal. As such, the movement in the to and fro direction of the carriage38can be controlled. In addition, since the head controlling substrate is covered by a head cover of the carriage38, the head controlling substrate is not illustrated inFIGS. 8 and 9.

As illustrated inFIGS. 8 and 9, a platen42is arranged below the recording paper conveying path23in such a manner that the platen42faces the ink jet recording head39. The platen42is arranged throughout a central part where the recording paper passes over in an area where the carriage38moves in the to and fro direction. A width of the platen42is sufficiently larger than a maximum width of the conveyable recording paper in a direction orthogonal to the recording paper conveying direction, and thus both ends of the recording paper always pass over the platen42.

As illustrated inFIGS. 8 and 9, an area where the recording paper does not pass through, namely, an image unrecordable area by the ink jet recording head39, includes a maintenance unit such as a purge mechanism51and a waste ink tray84. The purge mechanism51serves to absorb and remove bubbles and foreign materials from nozzles53(seeFIG. 12) of the ink jet recording head39. The purge mechanism51includes a cap52that covers the nozzles53of the ink jet recording head39, a pump mechanism connected to the ink jet recording head39through the cap52, and a moving mechanism that allows the cap52to be attached to/detached from the nozzles53of the ink jet recording head39. In addition, inFIGS. 8 and 9, the pump mechanism and the moving mechanism are arranged below the guide rail44, and therefore are not shown in the drawings. When the bubbles and the like are absorbed and removed from the ink jet recording head39, the carriage38is moved such that the ink jet recording head39is positioned over the cap52. Under the condition, the cap52is moved upwardly to be attached to a lower surface of the ink jet recording head39in such a manner that the cap52seals the nozzles53. Because of a creation of negative pressure within the cap52by means of the pump mechanism, ink is absorbed from the nozzles53of the ink jet recording head39. The bubbles and foreign materials within the nozzles53are absorbed together with the ink.

The waste ink tray84receives an idle ejection, which is so-called as a flushing, of ink from the ink jet recording head39. The waste ink tray84is formed on an upper surface of the platen42, and within an area where the carriage38moves in the to and fro direction and the image unrecordable area. In addition, an inside of the waste ink tray84is covered with a sheet of felt, and therefore the flushed ink is absorbed by the felt to be held therein. Maintenance is performed by the maintenance unit as to removal of the bubbles and mixed inks, and prevention of dried condition within the ink jet recording head39.

As illustrated inFIG. 5, a front surface of the housing of the printer unit2is provided with a freely openable door7. In addition,FIG. 5illustrates the door7in a closed condition. When the door7is opened, a cartridge mounting unit is exposed at a front side of the apparatus, and thus the ink cartridge can be inserted into/withdrawn from the apparatus. The cartridge mounting unit, which, however, is not illustrated in the drawings, is divided into four rooms corresponding to the number of the ink cartridges and the rooms receive ink cartridges containing inks of cyan, magenta, yellow and black, respectively. Four ink tubes41corresponding to each color of inks are arranged between the cartridge mounting unit and the carriage38, as illustrated inFIG. 8. The ink jet recording head39carried by the carriage38is supplied with each color of inks from the ink cartridges mounted to the cartridge mounting unit through each of ink tubes41.

The ink tubes41are made of synthetic resin and therefore have a flexibility according to the movement of the carriage38in the to and fro direction. Each ink tube41led out from the cartridge mounting unit is extended along the width direction of the apparatus to about a center thereof and is temporarily secured to a securing clip36of the apparatus body. Each ink tube41at its area between the securing clip36and the carriage38is not secured to the apparatus body or the like, and thus such area changes its position in accordance with the movement of the carriage38in the to and fro direction. In addition, inFIG. 8, the ink tubes41extending from the securing clip36to the cartridge mounting unit, not shown here, are omitted.

As illustrated inFIG. 8, the ink tube41of its area between the securing clip36and the carriage38extends so as to form a curved line that reverses its course in the to and fro direction of the carriage38. In other words, the ink tube41extends so as to form a generally U-letter shape in a plan view. The four ink tubes41are arranged in a horizontal direction along the recording paper conveying direction in the carriage38to extend in the to and fro direction of the carriage38. On the other hand, the four ink tubes41at the securing clip36are arranged and secured in a condition that the tubes41are piled up in a vertical direction. The securing clip36has an opening that opens upwardly and has a U-letter shape in its cross part. Each ink tube41is inserted into the opening to be piled up in the vertical direction, resulting in being held all together by the securing clip36. Accordingly, the four ink tubes41are twisted so as to convert the arrangement in the horizontal direction into the arrangement in the vertical direction from the carriage38to the securing clip36, resulting in being curved into generally U-letter shape viewing the entirety of four tubes.

Recording signals or the like are sent from a main substrate composing a controlling unit64(seeFIG. 14) to a head controlling substrate of the ink jet recording head39through a flat cable85. In addition, the main substrate is arranged at a front side of the apparatus (front side ofFIG. 8), and thus is not shown inFIG. 8. The flat cable85of thin strip-shape is so formed that a plurality of conductive wires for transmitting electric signals are covered by a synthetic resin film such as a polyester film for an insulation thereof. The flat cable85serves to electrically connect the main substrate with the head controlling substrate, which are not shown here.

The flat cable85has a flexibility and thus is flexible in accordance with the reciprocate movement of the carriage38. As illustrated inFIG. 8, the flat cable85at its area between the carriage38and the securing clip36extends so as to form a curved line, that traverses in the to and fro direction of the carriage38. In other words, the flat cable85extends in such a manner that the flat cable85forms a generally U-letter shape in a plan view, provided that two sides of the thin strip-shaped flat cable is in a vertical direction. A direction in which the flat cable85extends from the carriage38and a direction in which the ink tubes41extend are the same directions with regard to the movement of the carriage38in the to and fro direction.

One end of the flat cable85secured to the carriage38is electrically connected to the head controlling substrate, which is not shown here, mounted on the carriage38. The other end of the flat cable85secured to the securing clip86extends to the main substrate, which is not shown here, and is electrically connected thereto. The area of the flat cable85generally curved into U-letter shape is not secured to any member and changes its position in accordance with the reciprocate movement of the carriage38in a similar manner as the ink tubes41. As stated above, the ink tubes41and the flat cable85that change their positions in accordance with the reciprocate movement of the carriage38are supported by a rotatable supporting member100. The rotatable supporting member100is rotated in a generally horizontal direction in association with the change of the positions of the ink tubes41and the flat cables85to support them.

A restricting wall37extends in the width direction of the apparatus (in the horizontal direction inFIG. 8) at the front side of the apparatus viewing from the ink tubes41and the flat cable85. The restricting wall37has a vertical wall that contacts the ink tubes41, with the wall linearly standing up along the movement of the carriage38in the to and fro direction. The restricting wall37is provided in a direction in which the ink tubes41extend from the securing clip36that secures the ink tubes41, and has a sufficient height so that all the four ink tubes41that are arranged in the vertical direction by the securing clip36can contact the restricting wall37. The ink tubes41extend along the restricting wall37from the securing clip36to finally contact a surface of restricting wall37at a rear side of the apparatus, thereby preventing a projection of the ink tubes41toward the front side of the apparatus, namely, in a direction away from the carriage38.

The securing clip36is provided around the central position of the apparatus in the width direction and secures the ink tubes41so as to allow the ink tubes41to extend toward the restricting wall37. That is, an angle between the vertical wall surface of the restricting wall37and the direction in which the securing clip36allows the ink tubes41to extend takes a blunt angle smaller than 180 degrees in a plan view. The ink tubes41have a flexibility as well as a suitable bending rigidity, such that the extension with the angle of the ink tubes41by the securing clip36with regard to the restricting wall37urges the ink tubes41onto the wall surface of the restricting wall37. Accordingly, in the area where the carriage38moves in the to and fro direction, an area where the ink tubes41are urged along the restricting wall37becomes larger, such that an area between the curved area of the ink tubes41and the carriage38that projects toward the rear side of the apparatus, namely, toward the carriage38can be reduced.

The securing clip86is arranged at a position in the vicinity of the center of the apparatus in the width direction and inside the curved area of the secured clip36, and secures the flat cable85so as to allow the flat cable85to extend toward the restricting wall37. That is, the vertical wall of the restricting wall37and the direction in which the securing clip36allows the flat cable85to extend takes a blunt angle smaller than 180 degrees in a plan view. The flat cable85has the flexibility as well as the suitable bending rigidity, such that the extension with the angle of the flat cable85by the securing clip86with regard to the restricting wall37urges the flat cable85onto the wall surface of the restricting wall37. Accordingly, in the area where the carriage38moves in the to and fro direction, an area where the flat cable85is urged along the restricting wall37becomes larger, such that an area between the curved area of the flat cable85and the carriage38that projects toward the rear side of the apparatus, namely, toward the carriage38can be reduced.

FIG. 12is a bottom surface view illustrating a nozzle forming surface of the ink jet recording head39. The ink jet recording head39includes nozzles53on a lower surface thereof for cyan (C), magenta (M), yellow (Y), and black (Bk), respectively, with the nozzles53being aligned by color in the recording paper conveying direction. In addition, inFIG. 12, an up and down direction is the recording paper conveying direction and a horizontal direction is the reciprocating movement direction of the carriage38. The nozzles53of the inks C, M, Y, Bk are aligned in the recording paper conveying direction, and the each nozzle53line of each of the color inks aligns in the reciprocating movement direction of the carriage38. Pitches between the nozzles53and the number of nozzles53in the conveying direction can be set as required considering a resolution or the like of the recording image. Further, the number of the lines of the nozzles53can be changed in accordance with the number of kinds of the color inks.

FIG. 13is a partially enlarged schematic cross sectional view illustrating an inner structure of the ink jet recording head39. An upstream of the nozzles53formed on the lower surface of the ink jet recording head39is provided with a cavity55formed thereon with a piezo-electric element54. The piezo-electric element54is deformed by being applied with a predetermined voltage to reduce a volume of the cavity55. According to this change of volume of the cavity55, the ink within the cavity55is ejected from the nozzles53in the form of ink droplets.

The cavity55is provided for each of the nozzles53, and a manifold56is formed over a plurality of cavities55. The manifold56is provided for each of the color inks C, M, Y, Bk. An upstream of the manifold56is provided with a buffer tank57. The buffer tank57is provided for each of the color inks C, M, Y, Bk. Each buffer tank57is supplied through an ink supplying opening58with the ink distributing through the ink tube41. Since the ink is once reserved in the buffer tank57, the bubbles generated in the ink within the ink tube41or the like are trapped therein to prevent the bubbles to go into the cavity55and the manifold56. The bubbles trapped within the buffer tank57are absorbed and removed by the pump mechanism through a bubble discharging opening59. The ink supplied from the buffer tank57to the manifold56is divided to each cavity55by the manifold56.

As stated above, an ink flow path is so structured that each color ink supplied from the ink cartridge through the ink tube41flows into the cavity55through the buffer tank57and the manifold56. Each color ink C, M, Y, Bk supplied through such an ink flow path is ejected in the form of the ink droplet from the nozzles53onto the recording paper owing to the deformation of the piezo-electric element54.

As illustrated inFIG. 7, an upstream of the image recording unit24is provided with a pair of transport roller60and a pinch roller. InFIG. 7, the pinch roller is not viewed since it is hidden by other members; however, the pinch roller is arranged in a pressurized manner below the transport roller60. The transport roller60and the pinch roller pinch the recording paper therebetween while the recording paper is conveyed on the recording paper conveying path23finally to the platen42. A downstream of the image recording unit24is provided with a pair of eject roller62and a spur roller63. The eject roller62and the spur roller63nip the recording paper after being recorded to transport it to the paper discharging tray21. The transport roller60and the eject roller62receive a driving force from the LF motor71(seeFIG. 14) to perform an intermittent drive by a predetermined line feed width. The transport roller60rotates synchronized with the eject roller62. A rotary encoder76(seeFIG. 14) provided on the transport roller60detects by the optical sensor a pattern of an encoder disk61that rotates in association with the transport roller60. On the basis of this detected signal, rotations of the transport roller60and the eject roller62are controlled.

The spur roller63contacts with the recording paper after it is recorded, such that a surface of the spur roller63is formed into irregularity of a spur shape so as not to have the image on the recording paper be deteriorated. The spur roller63is provided in a direction away from the eject roller62so as to be slidable, and urged by a coil spring so as to fit with the eject roller62. When the recording paper enters into a gap between the eject roller62and the spur roller63, the spur roller63retracts against the urging force by a thickness of the recording paper to hold the recording paper in such a manner that the recording paper is urged onto the eject roller62. As such, the rotation force of the eject roller62can be reliably transmitted to the recording paper. The pinch roller is also provided in a similar manner with regard to the transport roller60, such that the recording paper is held in press so as to contact with the transport roller60, thereby transmitting the rotation force of the transport roller60to the recording paper in a reliable manner.

FIG. 14is a block diagram illustrating a structure of the controlling unit64of the multi-function apparatus1. The controlling unit64controls not only the printer unit2but also the entire behavior of the multi-function apparatus1including the scanner unit3, and includes the main substrate to which the flat cable85is connected. In addition, since a structure of the scanner unit3is not a main structure of the present invention, a detailed explanation thereof is omitted here. The controlling unit64is structured as a micro computer that mainly includes CPU (Central Processing Unit)65, ROM (Read Only Memory)66, RAM (Random Access Memory)67, and EEPROM (Electrically Erasable and Programmable ROM)68and is connected to the ASIC (Application Specific Integrated Circuit)70through a bus69.

The ROM66stores a program or the like for controlling various behaviors of the multi-function apparatus1. The RAM67is used as a memory area or a working area where various data, that are used when the CPU65executes the above stated program, are temporarily stored. Further, the EEPROM68stores settings and flags or the like to be saved even after the power is off.

The ASIC70generates an excitation signal or the like to be input to the LF (transmitting) motor71in response to a command from the CPU65, the signal is applied to a driving circuit72of the LF motor71, and the driving signal is input to the LF motor71through the driving circuit72, thereby controlling the rotation of the LF motor71. The driving circuit72causes the paper supplying roller25, the transport roller60, the eject roller62, and the LF motor71connected to the purge mechanism51to drive and generates an electric signal for rotating the LF motor71upon receiving the output signal from the ASIC70. The LF motor71rotates upon receiving this electric signal to transmit the rotation force of the LF motor71to the paper supplying roller25, the transport roller60, the eject roller62and the purge mechanism51through a known driving mechanism including gears, driving shafts or the like.

The ASIC70generates an excitation signal or the like to be output to the CR (carriage) motor73in response to the command from the CPU65, this signal is applied to a driving circuit74of the CR motor73, and the driving signal is output to the CR motor73through the driving circuit74, thereby controlling the rotation of the CR motor73. The driving circuit74causes the CR motor73to drive and generates the electric signal for rotating the CR motor73upon receiving the output signal from the ASIC70. The CR motor73rotates upon receiving this electric signal, and the rotation force of the CR motor73is transmitted to the carriage38through the belt driving mechanism46to cause the carriage38to move in the to and fro direction. As such, the reciprocating movement of the carriage38is controlled by the controlling unit64.

A driving circuit75selectively ejects each of the color inks onto the recording paper from the ink jet recording head39at a predetermined timing, receives the output signal generated in the ASIC70on the basis of a drive control step output from the CPU65, and controls the ink jet recording head39. This driving circuit75is mounted on the head controlling substrate. The flat cable85transmits the signal from the main substrate composing the controlling unit64to the head controlling substrate.

ASIC70is connected to the rotary encoder76for detecting a rotation amount of a driving roller87and the linear encoder77for detecting a position of the carriage38. The carriage38is moved to one end of the guide rails43,44when the power of the multi-function apparatus1is switched on, at which the position detected by the linear encoder77is initialized. When the carriage38moves on the guide rails43,44from this initialized position, the optical sensor35provided on the carriage38detects a pattern of the encoder strip50, and the number of pulse signals detected by the sensor is learned by the controlling unit64as a moving distance of the carriage38. The controlling unit64controls the rotation of the CR Motor73in order to control the reciprocating movement of the carriage38on the basis of this moving distance.

ASIC70is connected to the scanner unit3, the operation panel4for sending operation command of the multi-function apparatus1, the slot unit5to which various compact size memory cards are inserted, a parallel interface78and a USB interface79for performing a send and receive of data with the external information equipment such as a personal computer through a parallel cable and a USB cable, and so on. Further, the ASIC70is connected to a NCU (Network Control Unit)80and a modem (MODEM)81in order to realize the facsimile function.

Detailed explanation will be given hereinafter as to a supporting structure of the driven pulley48and a supporting structure of the pulley holder125with reference toFIGS. 15 to 22. Here,FIGS. 15A and 15Bare cross sectional views of the essential parts viewing from XV-XV direction onFIG. 10.FIGS. 16A,16B and16C are outer appearances illustrating a front shape and side shapes of a holder body124, respectively.FIG. 17is a perspective view of the holder body124viewing obliquely from a lower direction.FIGS. 18A,18B and18C are views of outer appearance of a shaft138of the pulley holder125viewing from three different directions.FIG. 19is an enlarged perspective view of the shaft138.FIGS. 20A and 20Bare exploded perspective views explaining an assembly structure of the driven pulley48.FIG. 21is a cross sectional view ofFIG. 15taken along a line XXI-XXI.FIG. 22is a cross sectional view ofFIG. 15Btaken along a line XXII-XXII.

The pulley holder125includes the holder body124and the shaft138. The holder body124is formed of a synthetic resin such as ABS resin, acrylic resin (methylmethacrylate), polypropylene (PP), polycarbonate (PC), polyacetal (POM), and polybutylene terephthalate (PBT) by using a die. In addition, a general die molding is exemplified by an injection molding; however, other molding method is also available here. Further, a metal die is generally used; however, any die is available as far as it is suitable for molding the pulley holder125, namely, a glass die, a resin die, a ceramic die and others. In the die molding of the holder body124, a predetermined draft angle is taken for the sake of an easy releasing of the holder body124from the die. According to the present embodiment, the holder body124is formed, with an approximate right end portion ofFIG. 15Bbeing as a parting line. Therefore, the holder body124is withdrawn toward a right side ofFIG. 15B(toward a direction of an arrow P2inFIG. 15B), and therefore, draft angles of about ½-2 degrees are formed into a tapered shape from the right to the left of the holder body124inFIG. 15B.

As illustrated inFIGS. 15B,16A,16B and16C, the holder body124generally includes an upper part130which appears upward from an upper surface44aof the guide rail44and a lower part131which is inserted into the hole128provided in the guide rail44(seeFIG. 11). Here,FIG. 16Ais a left side view of the holder body124as illustrated inFIGS. 15A and 15B.FIG. 16Bis a front view of the holder body124.FIG. 16Cis a right side view of the holder body124.

The upper part130of the holder body124includes a base133with which contacts the upper surface44aof the guide rail44when the lower part131of the holder body124is inserted into the hole128, and a support arm132which stands up in the upward vertical direction from the base133. The support arm132has a channel shape when viewing it from a front. More specifically, the support arm132is formed continuously with the base133to finally form the channel shape in a combination of an arm lower part137which extends in parallel with an upper surface of the base133, an arm base136extending upward from one end of the arm lower part137, and an arm upper part135extending from the upper end of the arm base136in a direction in which the arm lower part137extends. An inner space134enclosed by the arm upper part135, the arm base136, and the arm lower part137, namely, the inner space134of the support arm132having a channel shape includes therein the driven pulley48(seeFIG. 15A).

As illustrated inFIG. 16A, a bearing140that supports one end141aof the shaft138is formed from an upper surface137aof a distal end (left end inFIG. 15B) of the arm lower part137to the lower part131. Further, a bearing139is formed at a distal end (left end inFIG. 15B) of the lower surface135bof the arm upper part135in order to support the other end141bof the shaft138(seeFIG. 18). Both of the bearings139,140have groove shapes which are elongated in an extending direction of the arm upper part135and the arm lower part137and which include at their inner end a curved surface generally identical to the outer circumference of the shaft138to be supported.

The shaft138, as illustrated inFIGS. 18A,18B,18C and19, includes a shaft body141(projection) of a cylindrical shape having a predetermined diameter D1, and a different diameter shaft142of a cylindrical shape having a diameter D2(<D1) smaller than that of the shaft body141. The most part of the shaft138is the shaft body141, and supports the driven pulley48in a rotation free manner. The different diameter shaft142is formed into one piece with the shaft body141and projects in the axial direction from one end of the shaft body141. The shaft body141and the different diameter shaft142are integrally formed from metal such as steel. This different diameter shaft142is provided for preventing an undesirable rotation of the shaft body141. An axis G2of the different diameter shaft142(a dashed line G2inFIG. 18A) is in parallel with an axis G1of the shaft body141(a dashed line G1inFIG. 18A). The axis G2is not aligned with the axis G1but is spaced (biased) from the axis G1by a predetermined distance Δd.

For example, when the diameter D1of the shaft body141is set to be 2.48 mm, and the diameter D2of the different diameter shaft142is set to be 1.5 mm, the distance Δd is set to be 0.3 mm. The shaft138may be formed from a steel wire by cold forging. In this case, the circumference of the different diameter shaft142is formed within the circumference of the shaft body141.

The bearing140supports the shaft138at the side of the different diameter shaft142. More specifically, the bearing140supports one end141aof the shaft body141at the side of the different diameter shaft142. The different diameter shaft142is fit into a fitting groove143(FIG. 16A) formed, as a fitting part for the different diameter shaft142, at a position lower from the bearing140. Accordingly, the different diameter shaft142is held by the fitting groove143. The bearing140is formed to have a groove width that corresponds to the diameter of the shaft body141. That is, the groove width of the bearing140(the horizontal direction inFIG. 16A) has such a dimension that a predetermined tolerance is added to the diameter of the shaft body141. The bearing139supports the other end141bof the shaft body141. Therefore, the bearing139has a groove width identical to that of the bearing140. The groove width of the fitting groove143is generally the same dimension as the diameter of the different diameter shaft142.

More specifically, as shown inFIGS. 20A and 20B, the shaft body141around which the pulley48is attached is fitted into the bearings139,140from one end of the holder body124(from a left end inFIG. 20A), while the different diameter shaft142is fitted into the fitting groove143. The bearings139,140and the fitting groove143are formed to be open at the one end (left end inFIG. 20A) of the holder body124so as to allow the shaft138to be slidably inserted thereinto. The fitting groove143has a narrow portion143a(FIG. 17) that is formed at an open end of the fitting groove143and has a smaller groove width than the groove width of the rest of the fitting groove143. The narrow portion143afunctions as a stopper that prevents the different diameter shaft142from being removed from the fitting groove143to thereby prevent the shaft138from being removed from the holder body124. For example, when the diameter D2of the different diameter shaft142is set to be 1.5 mm, the groove width of the fitting groove143is set to be 1.42 mm, and the groove width of the narrow portion143ais set to be 1.3 mm.

As stated above, the axis G2of the different diameter shaft142is spaced (biased) from the axis G1of the shaft body141by a predetermined distance Δd. Therefore, when the bearing140receives the shaft body141of the shaft138as well as the fitting groove143receives the different diameter shaft142, the axis G1of the shaft body141and the axis G2of the different diameter shaft142are positioned spaced from each other in a longitudinal direction of the bearing140and the fitting groove143, namely, in the horizontal direction inFIG. 15A. Accordingly, in order to allow the shaft body141to rotate with regard to the bearing140, the different diameter shaft142is required to rotate around the axis G1of the shaft body141. However, since the different diameter shaft142is fit into the fitting groove143, the rotation of the different diameter shaft142around the axis G1is restricted. Consequently, the shaft body141is not allowed to rotate with regard to the bearing140.

The lower part131of the holder body124is formed with first fitting parts161and second fitting parts162. The first fitting parts161are fit into first edge parts151, which will be described later, formed on a peripheral edge of the hole128(seeFIG. 11). Further, the second fitting parts162are fit into second edge parts152, which will be described later, formed on the peripheral edge of the hole128(seeFIG. 11).FIGS. 15A and 15Billustrate the first fitting part161and the second fitting part162which appear in the front side; however, these fitting parts161and162are also formed at the rear side of the apparatus in a symmetrical manner. As such, the first fitting parts161and the second fitting parts162are paired to be formed on the front side and the rear side.

The first fitting parts161include the base133, first ribs163provided at positions spaced from and lower than the lower surface133aof the base133by a predetermined distance, and grooves165formed between the base133and the first ribs163. Further, the second fitting parts162include the base133, second ribs164provided at positions spaced from and lower than the lower surface133aby a predetermined distance, and grooves166formed between the base133and the second ribs164. In addition, the grooves165and166are so formed that the groove widths are approximately same as the thickness of the guide rail44.

As illustrated inFIG. 22, a distance between the bottom surfaces165aof a pair of grooves165formed at the front side and the rear side is set to t1. Since the pair of grooves165receive the pair of first edge parts151, this distance t1is set to generally the same distance as the distance h1of the first edge parts151(seeFIG. 11). Further, a distance between bottom surfaces166aof a pair of grooves166formed at the front side and the rear side is set to t2that is shorter than the above stated distance t1. Since the pair of grooves166receive the pair of second edge parts152, this distance t2is set to generally the same distance as the distance h2of the second edge parts152(seeFIG. 11). Accordingly, steps are provided between the grooves165and the grooves166such that the distance between the bottom surfaces165a,166abecomes shorter toward the grooves166.

As illustrated inFIG. 22, a predetermined draft angle φ with regard to a releasing direction from the die (arrow P2inFIG. 15B) is formed on the bottom surfaces165aof the grooves165and the bottom surfaces166aof the grooves166. As stated above, each first fitting part161having the groove165and each second fitting part162having the groove166are divided in the releasing direction via a step formed therebetween. In the distance t1of the paired bottom surfaces165aand the distance t2of the paired bottom surfaces166a, a difference of dimension in the releasing direction according to the draft angle is smaller than a case where the first fitting parts and the second fitting parts are not divided.

As illustrated inFIG. 11, the hole128includes the first edge parts151to be fit into the first fitting parts161and the second edge parts152to be fit into the second fitting parts162. The first edge parts151are formed to be opposed to each other in the paper conveying direction (in the up and down direction inFIG. 11). The second edge parts152are formed likewise. The first edge parts151are formed so as to correspond to the paired grooves165of the first fitting parts161, and the distance h1thereof is set to a size in which the bottom surfaces165aof the grooves165can be fit thereinto. Further, the second edge parts152are formed so as to correspond to the paired grooves166of the second fitting parts162, and the distance h2thereof is set to a size in which the bottom surfaces166aof the grooves166can be fit thereinto. Therefore, the first edge parts151and the second edge parts152become narrower as going to the second edge parts152. At an opposite side of the second edge parts152beyond the first edge parts151, namely, at a right side inFIG. 11, an inserting part153which is wider than the distance h1of the first edge parts151is formed. A width h3of the inserting part153is larger than the distance t3(seeFIG. 22) between the bottom surfaces165aat the ends of the first ribs163.

The lower part131of the pulley holder125is inserted from the upper side to the lower side of the guide rail44in such a manner that the first ribs163are aligned with the inserting part153of the hole128and the second ribs164are aligned between the paired first edge parts151. Then, the first edge parts151are fit into the grooves165and the second edge parts152are fit into the grooves166, respectively, to slide the pulley holder125in a left direction (in the direction of arrow P0) inFIG. 11. As illustrated inFIG. 15A, the timing belt49is wound around the driven pulley48supported by the pulley holder125, and the coil spring126is inserted between the spring receiving part129and the standup plate127to allow the pulley holder125to be elastically urged in the belt tension direction (FIG. 15A).

As stated above, each first fitting part161and each second fitting part162of the pulley holder125that are formed along the belt tension direction are divided via the step in the belt tension direction. Since the dimension difference in the releasing direction according to the draft angle is relatively small, plays between the first edge parts151and the grooves165and between the second edge parts152and the grooves166become small in the distance t1between the bottom surfaces165aof the grooves165of the first fitting parts161and the distance t2between the bottom surfaces166aof the grooves166of the second fitting parts162. Accordingly, the scanning shift of the carriage38due to the play of the pulley holder125can be reduced, resulting in an enhancement of the image quality to be recorded on the recording paper by the ink jet recording head39.

Further, a set of the first fitting part151and the second fitting part152are provided at both sides of the driven pulley48in parallel with the belt tension direction, such that the pulley holder125can be supported with a good balance with regard to the tension force of the timing belt49. Accordingly, a supporting strength with regard to the belt tension direction of the driven pulley48becomes large and thus becomes stable.

In the pulley holder125, the holder body124supports the shaft138. The shaft body141is supported by the bearings139,140of the holder body124, and the different diameter shaft142is fit into the fitting groove143. Since the axis G2of the different diameter shaft142is biased from the axis G1of the shaft body141, the shaft body141would not rotate around the axis G1. As such, even if the rotation of the driving pulley47causes the timing belt49to have the driven pulley48rotate, the shaft body141would not rotate with regard to the bearings139,140, such that the friction wear of the bearing139,140can be prevented. Therefore, the shift in conveying the carriage38and the degrading of the quality of the recorded image by the ink jet recording head39can also be prevented.

In addition, the different diameter shaft142is formed at one end of the shaft body141of the shaft138according to the present embodiment; however, the different diameter shaft142may be formed at both ends of the shaft body141. In such a case, the fitting groove143is formed also at the side of the bearing139and the different diameter shafts142at the both ends of the shaft body141are to be fitted into the pair of fitting grooves143, respectively.