Abstract:
A recording apparatus comprises a first gear, a second gear meshable with the first gear, a third gear meshable with the first gear and the second gear. The third gear has a peripheral surface on which a toothed portion meshable with the first gear and an untoothed portion not meshable with a toothed portion of the first gear are disposed opposable to the first gear, and a peripheral surface on which a toothed portion meshable with the second gear is disposed opposable to said second gear, a gear drive switching control unit controls switching such that when the toothed portion adjacent the untoothed portion of the third gear comes into contact with the first gear, the second gear and the third gear are meshed to rotate the third gear to oppose the untoothed portion of the third gear to the first gear, thereby releasing the contact between the first gear and the third gear.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a recording apparatus having recording means for outputting input information such as character, image and so on onto the recording medium, a recording system as an information processing system, such as a copying machine, a facsimile machine, a printer, a word processor, or a personal computer, comprising said recording apparatus as output means, and a drive switching method for use with said recording apparatus. 
     2. Related Background Art 
     The recording apparatus performs the recording by driving recording means having a plurality of recording elements for outputting the input information such as character, image and so on onto the recording medium (such as a paper, a cloth, a plastic sheet, etc.) under control of control means. The recording apparatuses can be classified into an ink jet system, a wire dot system, a thermal system, a thermal transfer system, and a laser beam system, depending on the recording system of recording means to be used. Among these recording apparatuses, in a serial type recording apparatus which takes a recording method of effecting recording by causing recording means to scan in a direction crosswise to the conveying direction (sub-scan direction) of recording medium, the image recording over the entire area of recording medium is accomplished in such a way that after setting the recording medium at a predetermined recording position, the image recording (main scanning) operation by recording means (recording head) mounted on a carriage moving along the recording medium is carried out by repeatedly performing paper feeding (sub-scanning) by a predetermined amount after one line of recording, and then recording (main scanning) of image at the next line. 
     Typically, in the serial type recording apparatus, a step motor is mostly used as a carriage drive motor for driving a carriage useful for the main scanning (scanning for recording) of a recording head. Also, as a drive motor for feeding the recording medium in a direction perpendicular to a movement direction of carriage, a step motor is also mostly used. Further, an apparatus has been developed in which only one drive source is used to perform plural operations to reduce the motors for the purposes of lower costs and saved space. 
     One such serial type recording apparatus is known in which the drive transmission path for paper feed driving is switched by the use of the movement of carriage outside the recording area, as described in Japanese Laid-Open Patent Application No. 59-145175, for example. Also, one way of switching such drive path is known in which the disconnecting/switching of drive transmission path is effected by the use of a missing teeth portion of a gear in a drive transmission system, as described in Japanese Laid-Open Patent Application No. 4-288264, for example. 
     By applying such technologies, an ink jet recording apparatus was manufactured having a drive transmission path for transmitting the drive which is switched by selecting a paper feeding and a recovery pump by means of a gear with an untoothed portion by the use of the movement of carriage outside the recording area, but there was observed a phenomenon that the unnatural sound occurred from near the gear with the untoothed portion. Analyzing its cause, it has been found that the sound was produced by the contact between the untoothed end portion of the gear with untoothed portion and the tooth of a gear opposite the gear with untoothed portion, without regard to the drive transmission. 
     Also, because such abnormal contact condition between gears caused a defect in the gear, there was a risk that normal drive transmission might be hampered. 
     SUMMARY OF THE INVENTION 
     In light of the aforementioned problems with he conventional arts, it is an object of the present invention to provide a recording apparatus with the reduced occurrence of noise. 
     It is another object of the invention to provide a recording apparatus with less occurrence of noise In which an untoothed portion of a gear of a drive transmission system and a toothed portion of a gear opposite said untoothed portion is made out of contact in non-rotating transmission state. 
     It is another object of the invention to provide a recording apparatus comprising, 
     a first gear, 
     a second gear meshable with said first gear, 
     a third gear meshable with both said first gear and said second gear, said third gear having a peripheral surface on which a toothed portion meshable with said first gear and an untoothed portion not meshable with a toothed portion of said first gear are disposed opposable to said first gear, and a peripheral surface on which a toothed portion meshable with said second gear is disposed opposable to said second gear, and 
     a gear drive switching control unit in which when the toothed portion adjacent the untoothed portion of said third gear comes into contact with said first gear, said second gear and said third gear are meshed to rotate said third gear to oppose the untoothed portion of said third gear to said first gear, thereby releasing the contact between the first gear and said third gear. 
     It is another object of the invention to provide a recording apparatus for switching transmission of a driving force from a single driving source to different driven mechanisms, comprising, 
     a recording medium conveying mechanism as a driven mechanism to convey a recording medium, 
     a gear for transmitting the driving force from said single driving source to said recording medium conveying mechanism, 
     a pump mechanism as a driven mechanism to effect an ink discharge recovery, 
     a toothed wheel for receiving the driving force driving said pump mechanism, and 
     a switching auxiliary member for receiving the driving force of said gear to drive said toothed wheel to enable transmission of the driving force from said gear to said toothed wheel, when switching the transmission of the driving force from said gear to said toothed wheel, 
     wherein said switching auxiliary member drives said toothed wheel to bring said toothed wheel out of contact with said gear, when releasing the driving transmission to said pump mechanism; 
     It is another object of the invention to provide a drive switching method for a recording apparatus comprising a first gear, a second gear engageable with said first gear, a third gear engageable with said first gear and being brought out of engagement with said first gear due to an untoothed portion formed on a peripheral edge thereof, wherein said second gear and said third gear are engaged at least when said first gear and said third gear are out of engagement, including, 
     a first step of bringing said first gear out of engagement with said third gear by means of the untoothed portion of said third gear by rotating said first gear in a fixed direction, 
     a second step of bringing said first gear in engagement with said second gear after said first step, and 
     a third step of rotating said first gear in the same direction to rotate said third gear engaged with said second gear to bring said first gear out of contact with the untoothed portion of said third gear after said second step. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 is a view for explaining the configuration of a carriage shaft near one end thereof and a transmission switching mechanism in a recording apparatus. 
     FIG. 2 is a view for explaining the configuration of the carriage shaft near one end thereof and the transmission switching mechanism in the recording apparatus, as viewed from the direction of the arrow A indicated in FIG.  1 . 
     FIG. 3 is a view for explaining the configuration of the carriage shaft near one end thereof in the recording apparatus, as viewed from the direction of the arrow B indicated in FIG.  1 . 
     FIG. 4 is a view for explaining the configuration of the carriage shaft near one end thereof in the recording apparatus, as viewed from the direction of the arrow C indicated in FIG.  1 . 
     FIG. 5 is a view for explaining the schematic configuration of the transmission switching mechanism in the recording apparatus. 
     FIG. 6 is a view for explaining the relation between an untoothed portion of a pump gear and a feed gear provided in the transmission switching mechanism in the recording apparatus. 
     FIG. 7 is a gear state view for explaining the switching control. 
     FIG. 8 is a gear state view for explaining the switching control. 
     FIG. 9 is a gear state view for explaining the switching control. 
     FIG. 10 is a flowchart showing the switching control. 
     FIGS. 11 to  14  are perspective views of the gear states shown in FIGS. 6 to  9 , respectively. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The embodiments of the present invention will be described below with reference to the drawings. Note that recording apparatus for use in this embodiment is an ink jet recording apparatus. 
     FIG. 1 is a front view showing a part of the recording apparatus as previously described, in which recording means is located at one end of the recording apparatus. FIG. 2 is a view of the recording apparatus as viewed from a direction of the arrow A in FIG. 1, and FIG. 3 is a view of the recording apparatus as viewed from a direction of the arrow B in FIG.  1 . Further, FIG. 4 is a view of the recording apparatus, particularly a feed roller, as viewed from a direction of the arrow C in FIG.  1 . In these figures, the arrow D indicates a conveying direction of the recording medium  4 . 
     In FIG. 1, recording means  1  is an ink jet cartridge mounted on a carriage  2 , wherein a recording head  1   a  and an ink tank  1   b  are detachably coupled. Of course, the recording means  1  may be an ink jet cartridge wherein the recording head  1   a  and the ink tank  1   b  integrated is mounted on the carriage  2 , or an ink jet recording head portion may be only mounted on the carriage  2 , and an ink tank portion equipped within an apparatus housing. Also, this recording head  1   a  may be in the form of recording only black ink, or in the form of full-color recording using the inks of yellow, cyan, and magenta (including black in some cases). 
     In FIG. 1, the ink discharge ports (not shown) of the recording head  1   a  are located opposite a cap  17  (at a position for recording head suction recovery processing). 
     The recording head  1   a  of the ink jet system effects recording by discharging the ink from the ink discharge ports onto the recording medium  4 , and has the advantages that recording means can be compact, a high definition image can be recorded at high speed, plain paper is usable for recording without needs of any special treatment, the running cost is lower, the noise is less owing to the non-impact method, and the color image is easy to record by using a plurality of color inks. 
     Particularly, recording means (recording head) of the ink jet system of discharging the ink by the use of heat energy can be easily fabricated with an arrangement of liquid channels (discharge ports) at high density by forming electrothermal converters  1   c , electrodes, liquid channel walls, and a ceiling plate as the film on a substrate through a semiconductor fabrication process including etching, vapor deposition and sputtering, and thus the apparatus can be more compact. 
     In the ink jet recording apparatus, because the recording head  1   a  has typically an array of fine discharge ports, a discharge recovery processing is performed to remove the discharge failure factors by discharging the ink when not in recording, or sucking the ink through ink discharge ports by negative pressure, even when the bubble or duct is mixed inside into discharge ports or the ink becomes unsuitable for discharging or recording owing to thickening caused by evaporation of ink solvent. Note that the ink jet recording apparatus in this embodiment allows the ink discharge ports of the recording head  1   a  to be placed opposite the cap  17  by moving the carriage  2  outside the recording area when not recording. And after performing the recovery processing by discharging the ink from the ink discharge ports into the cap  17 , the ink discharged within the cap  17  is evacuated from the cap  17  into a waste ink tank (not shown), using a suction pump (cylinder  21 ). 
     If the recording operation is started, recording means  1  is moved together with the carriage  2  moving along a carriage shaft  3 , while recording an image on the recording medium. The carriage  2  is driven via a belt  19  by a carriage motor  18 . If the recording by one line is ended, the recording operation is interrupted. 
     Next, a drive transmission path where the recording medium  4  is conveyed will be described. 
     The recording medium is conveyed (fed) by a feed roller  5 , its conveyance direction being a direction orthogonal (sub-scan direction) to a moving direction (main scan direction) of the recording means  1 . If a predetermined amount of paper feed is ended, the recording means  1  performs the recording again while moving in the main scan direction. 
     The rotation of the feed roller  5  is effected by the driving of a paper feed motor  6 . That is, as shown in FIG. 2, the rotation of a rotational shaft of the paper feed motor  6  is transmitted from an idler gear  22  and an idler gear  23  to a feed gear  14 . And a feed roller shaft  5   a  which is coupled coaxially with this feed gear  14  is rotated to convey the recording medium a predetermined amount. 
     Next, a drive transmission path where the recovery processing for recovering the ink discharge function of the recording head  1   a  is performed will be described. 
     The driving of piston within the cylinder  21  to obtain a suction force for recovering the ink discharge function is obtained from the paper feed motor  6 . And the transmission of a driving force from the paper feed motor  6  to a pump gear  16  is controlled by the movement of the pump gear  16 , the feed gear  14 , a slide gear  24 , a slide spring  25  and the carriage  2  which constitute a transmission switching mechanism. In the following, more detailed explanation is given with reference to FIGS. 5 and 6. 
     First, the carriage  2  is moved to the end portion of the carriage shaft to allow the slide gear  24  to move along the feed roller shaft  5   a  in a direction toward the feed gear  14  by the abutment between a projection portion formed on the carriage  2  and the slide gear  24  (coaxial with the feed roller shaft  5   a  and slidable and rotatable with respect to the feed roller shaft  5   a ). 
     While the discharge recovery processing is not performed such as when recording, the slide gear  24  is separated from the feed gear  14  by a biasing force of the slide spring  25  as an elastic member disposed between the slide gear  24  and the feed gear  14 . Therefore, the meshing between the slide gear  24  and the pump gear  16  is released. However, with the movement of the carriage  2  to the end portion of the carriage shaft  3 , the slide gear  24  and the pump gear  16  (coaxially coupled with the pump gear shaft  15  which is a shaft disposed parallel with the feed roller shaft) are meshed. 
     In FIG. 5, the slide gear  24  is provided coaxially and slidably with the feed roller shaft  5   a,  as previously described, and separated from the feed gear  14  by a biasing force of the slide spring  25 , thus subjected to no driving force, but is mesh ed with the pump gear  16 . However, since the pump gear  16  has lacking (missing) teeth in a portion to be meshed with the feed gear  14 , it is subjected to no driving force from the feed gear  14 . 
     If the carriage  2  is further moved to the feed gear  14 , the slide gear  24  is caused to move closer to the feed gear  14  against a biasing force of the slide spring, so that the slide gear  24  and the feed gear  14  are contacted. At this time, the contact faces (opposed faces) with each other are provided with the tooth portions  14   a,    24   a  which mesh with each other, whereby the meshing thereof allows the slide gear  24  to be rotated with the rotation of the feed gear  14 . And the pump gear  16  is rotated by the rotation of the slide gear  24 . 
     While In the previous embodiment, the slide spring  25  was used to separate the slide gear  24  from the feed gear  14 , it will be appreciated that the slide spring  25  may be omitted owing to the use of a force in a separating direction occurring between the tooth portion  14   a  and the tooth portion  24   a  which mesh with each other. 
     However, the driving of the pump gear  16  via the slide gear  24  by the feed gear  14  is an indirect driving in which a driving force is transmitted by the meshing between the tooth portions  14   a,    24   a  interposed between both, wherein with a larger driving force from the feed gear  14  to the slide gear  24 , there will occur a force in a separating direction between the tooth portions  14   a,    24   a  which mesh, as previously described, which imposes a limit on the magnitude of driving force to be transmitted. Thus, to realize the direct driving of the pump gear  16  by the feed gear  14 , the following configuration is taken. 
     As shown in FIGS. 6 and 11, a wide untoothed portion  16   a  extending radially is formed around the periphery of the pump gear  16 . That is, the pump gear  16  is formed thicker than the slide gear  24  and the feed gear  14 , and further the peripheral edge of the pump gear  16  has an untoothed portion in which one portion of the notched teeth is cut out from substantially a central portion axially toward one end portion (arrow E, in FIG.  5 ). Also, the width of this untoothed portion (arrow F, in the FIG. 6) is so large that at least this untoothed portion and the tooth portion of the feed gear  14  are out of contact, when the pump gear  16  and the feed gear  14  are meshed in place with each other. However, if the slide gear  24  is rotated slightly, the pump gear  14  is rotated to cause the untoothed portion to move, so that the pump gear  16  and the feed gear  14  are directly meshed, thereby producing a great driving force. 
     In this state, even if the meshing between the slide gear  24  and the feed gear  14  (the meshing between the tooth portions  14   a,    24   a ) is released by moving the carriage  2  in a direction away from the feed gear  14 , the driving force can be transmitted because the pump gear  16  and the feed gear  14  are directly meshed. Also, at this time, the slide gear  24  will be caused to move in a direction away from the feed gear  14 , while being meshed with the pump gear  16 , by a biasing force of the slide spring  25  or by a force in a separating direction occurring between the tooth portions  14   a,    24   a  which mesh with each other, as previously described, so that the meshing between the slide gear  24  and the feed gear  14  is released. 
     And by a driving force from the paper feed motor  6  which is transmitted via the direct meshing between the feed gear  14  and the pump gear  16 , the cap  17  is brought closer to or into contact with the discharge port face having the ink discharge ports of the recording head  1   a  arranged thereon to cover the ink discharge ports, so that the pump gear  16  which has received the transmission of the driving force from the paper feed motor  6  will move a piston (not shown) within the cylinder  21  via a cylinder gear  20 . Concurrently with this, the ink is sucked from the ink discharge ports of the recording head  1   a  into the cylinder  21  via the cap to recover the ink discharge function of the recording head  1   a.    
     In this embodiment, by controlling the paper feed motor  6  and the carriage motor  18  from this state in accordance with a flowchart as shown in FIG. 10, the meshing/release and rotation of the slide gear  24  and the feed gear  14  via the movement of the carriage  2  are controlled. 
     The operation when the feed gear  14  and the pump gear  16  are directly meshed to transmit a rotational driving force of high torque from the paper feed motor  6  to the pump gear  16  as previously described is shown in FIGS. 7 and 12. In the state as shown in FIG. 7, the feed gear  14  meshes with a gear portion of the pump gear  16  other than the untoothed portion  16   a  thereof, so that the rotational force of the feed gear  14  is transmitted to the pump gear  16  by the direct meshing between both gears. 
     In the control operation of this embodiment, the feed gear  14  is first rotated in an S direction from the state as shown in FIG. 7 (step S 1 ). With the rotation of the feed gear  14  in the S direction, the untoothed portion  16   a  of the pump gear  16  comes closer to an opposed portion of the feed gear  14 . And the untoothed portion  16   a  is opposed to the feed gear  14 , so that a contact portion  16   b  of the pump gear comes into contact with the feed gear  14 , as shown in FIG.  8 . Thereby, if the feed gear  14  is further rotated in the S direction, no rotation will be transmitted due to the untoothed portion  16   a,  so that the pump gear  16  is held in the state as shown in FIGS. 8 and 13, which causes the phase state of the pump gear  16  to be initialized. 
     In this way, since no rotation transmission to the pump gear  16  occurs if the meshing between the feed gear  14  and the pump gear  16  is released, the rotation of the feed gear  14  does not cause any rotation of the pump gear  16 . Also, with a smaller pump mechanism, the extent of closeness between the pump inside and the cylinder to produce a fixed suction force is higher, and therefore the pump gear  16  interlocked with the cylinder driving will not be rotated by a slight force from the outside. 
     That is, while the teeth of the feed gear  14  intermittently contacts the contact portion  16   b  of the pump gear  16 , the noise is produced by the contact of both gears (the contact portion  14   b  of the feed gear  14  and the contact portion  16   b  of the pump gear  16 ). With the pump gear  16  in the state as shown in FIG. 8, if other operation, e.g., paper feed operation, is performed, the gear tooth of the feed gear  14  makes contact with the contact portion  16   b  of the pump gear at every rotation of the feed gear  14 , causing noise. 
     To prevent occurrence of such noise, in the control of this embodiment, the carriage is moved in an X direction (see FIG. 1) to force the slide gear  24  to mesh with the feed gear  14  (step S 2 ). Thereby, the rotation of the feed gear  14  can be transmitted via the slide gear  24  to the pump gear  16 , as previously described. Then, the feed gear  14  is rotated by a few pulses in the S direction from this state (step S 3 ). In accordance with this, the pump gear  16  is also rotated slightly, so that the contact portion  16   b  of the pump gear leaves apart from the feed gear  14 , as shown in FIGS. 9 and 14. 
     Thereafter, the carriage is returned in a Y direction (see FIG. 1) to cause the slide gear  23  to leave from the feed gear  14  (step S 4 ). Thereby, the rotation transmission between the feed gear  14  and the pump gear  16  is released. 
     After the above control has been made, the contact portion  16   b  of the pump gear  16  is securely separated from the feed gear  14 , as shown in FIG. 9, even if the feed gear  14  is rotated for other operations, without occurrence of the noise. 
     It should be noted that the ink jet recording apparatus in this embodiment may be in the form of an image output terminal of information processing equipment such as a computer, a copying machine in combination with the reader, and a facsimile apparatus having a transmission and reception function. 
     As above described, according to the present embodiment, since the untoothed portion of the gear in the drive transmission system and the tooth portion of the gear opposed to the untoothed portion are brought out of contact when in the state of no rotation transmission, the noise problem can be resolved.