A recording apparatus and a drive switching method for use with said recording apparatus

Abstract: A recording apparatus comprising a first gear, a second gear meshable with said first gear, a third gear meshable with 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.

Description: BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a recording apparatus having recording means for outputting the 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, a printer, a word processor, a personal computer, comprising said recording apparatus as output means, and a drive switching method for use with said recording apparatus. 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. Such one 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. 2-23356, 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 (or EP-A2-0 505 143), for example. In particular, EP-A2 0 505 143 shows a recording apparatus which uses a motor with a single rotating direction for reciprocally driving a carriage over a recording medium in a scanning manner. For this, the rotational direction of a screw member for driving the carriage can be switched between two rotational directions by alternatively driving a forward gear with a main gear and locking a reverse gear by engagement of a cam portion of the main gear with a cam portion of the main gear and vice versa. 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 the light of the aforementioned problems with the conventional arts, it is an object of the present invention to provide a recording apparatus and a drive switching method therefor with the reduced occurrence of noise. This object is, with respect to the apparatus, solved with an apparatus according to claim 1, and, with respect to the method, solved with a method according to claim 11. 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 looked 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 looked 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 looked 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 toothed 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. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below with reference to the drawings. Note that an 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 looked from a direction of the arrow A in Fig. 1, and Fig. 3 is a view of the recording apparatus as looked 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 looked 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, recbrding means 1 is an ink jet cartridge mounted on a carriage 2, wherein a recording head 1a and an ink tank 1b are detachably coupled. Of course, the recording means 1 may be an ink jet cartridge wherein the recording head 1a and the ink tank 1b 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 1a 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 1a are located opposite a cap 17 (at a position for recording head suction recovery processing). The recording head 1a of the ink jet system effects recording by discharging the ink from the ink discharge ports onto the recording medium, and has the advantages that recording means can be compact, the high definition image can be recorded at high speed, the 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, 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 1a 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 1a to be placed opposite the cap 17 by moving the carriage 2 outside the recording area when not in 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 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 which is a first gear. And a feed roller shaft 5a which is a first shaft 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 1a 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 which is a second gear 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 3 to allow the slide gear 24 to move along the feed roller shaft 5a in a direction toward the feed gear 14 by the abutment between a projection portion 2a formed on the carriage 2 and the slide gear 24 which is a third gear (coaxial with the feed roller shaft 5a and slidable and rotatable with respect to the feed roller shaft 5a). 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 14 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 which is a second gear (coaxially coupled with the pump gear shaft 15 which is a second shaft disposed parallel with the feed roller shaft which is a first shaft) are meshed. In Fig. 5, the slide gear 24 is provided coaxially and slidably with the feed roller shaft 5a, 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 meshed 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 14a, 24a 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 14a and the tooth portion 24a 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 14a, 24a 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 14a, 24a 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 Fig. 6, a wide untoothed portion 16a 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 the figure). Also, the width of this untoothed portion (arrow F, in the figure) 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 14a, 24a) 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 14a, 24a 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 1a 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 1a into the cylinder 21 via the cap to recovery the ink discharge function of the recording head 1a. 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 Fig. 7. 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 16a 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 S1). With the rotation of the feed gear 14 in the S direction, the untoothed portion 16a of the pump gear 16 comes closer to an opposed portion of the feed gear 14. And the untoothed portion 16a is opposed to the feed gear 14, so that a contact portion 16b 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 16a, so that the pump gear 16 is held in the state as shown in Fig. 8, 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 makes intermittently into contact with the contact portion 16b of the pump gear 16, the noise is produced by the contact of both gears (the contact portion 14b of the feed gear 14 and the contact portion 16b 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 16b 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 S2). 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 S3). In accordance with this, the pump gear 16 is also rotated slightly, so that the contact portion 16b of the pump gear leaves apart from the feed gear 14, as shown in Fig. 9. Thereafter, the carriage is returned in a Y direction (see Fig. 1) to cause the slide gear 24 to leave from the feed gear 14 (step S4). 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 16b 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 the information processing equipment such as a computer, a copying machine in combination with the reader, and a facsimile apparatus having the 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.

Claims: A recording apparatus comprising: a first gear (14) driven by a driving source (6); a third gear (24); a second gear (16) meshable with said first gear (14) and said third gear (24), said second gear (16) having a peripheral surface on which a toothed portion meshable with said first gear (14) and an untoothed portion (16a) not meshable with a toothed portion of said first gear (14) are disposed opposable to said first gear (14), and a peripheral surface on which a toothed portion meshable with said third gear (24) is disposed opposable to said third gear (24); and a gear drive switching control unit in which when the toothed portion adjacent the untoothed portion (16a) of said second gear (16) comes into contact with said first gear (14), said third gear (24) is meshed with said first gear (14) and said second gear (16) to rotate said second gear (16) slightly until the untoothed portion (16a) of said second gear (16) is opposed to said first gear (14), thereby releasing any contact between the first gear (14) and said second gear (16), and in which said first gear (14) is rotatable without rotation of said third gear (24) in a state of release between said first gear (14) and said third gear (24). A recording apparatus according to claim 1, wherein said first gear (14) and said third gear (24) are supported coaxially around a shaft member (5a), said first gear (14) being secured to said shaft member (5a), said third gear (24) being supported slideably and rotatably around said shaft member (5a). A recording apparatus according to claim 2, wherein said third gear (24) slides with respect to said shaft member (5a) to move closer to or away from said first gear (14) to effect meshing (14a, 24a) or release of meshing (14a, 24a) with said first gear (14). A recording apparatus according to claim 1, wherein said first gear (14), transmits a driving force from a motor (6) to said shaft (5a) supporting said first gear (14) to drive a recording medium conveying mechanism (5) for conveying the recording medium. A recording apparatus according to claim 3, wherein said third gear (24) is forced by a carriage (2) having a head member (1a, 1b) mounted thereon and reciprocating in a recording area along the recording medium to slide on the shaft member and mesh with said first gear. A recording apparatus according to claim 1, wherein a pump mechanism (20, 21) is driven by the meshing between said first gear (14) and said second gear (16). A recording apparatus according to claim 5, wherein said head member (1a, 1b) is an ink jet recording head for forming an ink image on a recording medium by discharging ink droplets onto said recording medium. A recording apparatus according to claim 7, wherein ink jet recording head, (1a, 1b) comprises electrothermal converting elements for discharging ink droplets onto said recording medium by using heat energy generated by said electrothermal converting elements. A recording apparatus according to claims 1 to 8, adapted for switching transmission of a driving force from a single driving source to different driven mechanisms, further comprising: a recording medium conveying mechanism (5) as a driven mechanism to convey a recording medium; gears (22, 23, 14) including said first gear (14) for transmitting the driving force from said single driving source (6) to said recording medium conveying mechanism; a pump mechanism (20, 21) as a driven mechanism to effect an ink discharge recovery; said second gear (16) for receiving the driving force driving said pump mechanism; and a switching auxiliary member (24, 24a, 14a) including said third gear (24) for receiving the driving force of said gear (14) to drive said second gear (16) to enable transmission of the driving force from said first gear (14) to said second gear (16), when switching the transmission of the driving force from said first gear to said second gear; wherein said switching auxiliary member (24, 24a, 14a) drives said second gear (16) to bring said second gear (16) out of contact with said first gear (14), when releasing the driving transmission to said pump mechanism (20, 21). A recording apparatus according to claim 9, wherein said switching auxiliary member (24) is forced and moved by said carriage (2), so as to be meshable with said first gear (14) and said second gear (16). A drive switching method for a recording apparatus comprising a first gear (14), a third gear (24) engageable with said first gear (14), a second gear (16) engageable with said first gear (14) and being brought out of engagement with said first gear (14) due to an untoothed portion (16a) formed on a peripheral edge thereof, wherein said third gear (24) and said second gear (16) are engaged at least when said first gear (14) and said second gear (16) is out of engagement, including: a first step (S1) of bringing said first gear (14) out of engagement with said second gear (16) by means of the untoothed portion (16a) of said second gear (16) by rotating said first gear (14) in a fixed direction; a second step (S2) of bringing said first gear (14) in engagement with said third gear (24) after said first step; and a third step (S3) of rotating said first gear (14) in the same direction to rotate said second gear (16) engaged with said third gear (24) to bring said first gear (14) in opposed relation with the untoothed portion (16a) and out of contact with said second gear (16) after said second step (S2). A method according to claim 11, wherein said first gear (14) is a feed gear for conveying the recording medium, said third gear (24) is a slide gear which is forced against a projection (2a) formed on a movable carriage (2) mounting a recording head (1a, 1b) for discharging ink, and said second gear (16) is a pump gear for driving a pump (21) for sucking the ink on the discharge face of said recording head (1a, 1b) by its rotation. A method according to claim 12, wherein said recording head is an ink jet recording head for discharging ink droplets. A method according to claim 13, wherein said recording head comprises electrothermal converting elements, for discharging ink droplets by using heat energy generated by said electrothermal converting elements.

Inventors: HIRAMATSU SOICHI, INOUE HIROYUKI, IWASAKI TAKESHI, KAWAKAMI HIDEAKI, KIDA AKIRA, NAKAMURA HITOSHI, NOJIMA TAKASHI, YAMAGUCHI HIDEKI, HIRAMATSU, SOICHI, INOUE, HIROYUKI, IWASAKI, TAKESHI, KAWAKAMI, HIDEAKI, KIDA, AKIRA, NAKAMURA, HITOSHI, NOJIMA, TAKASHI, YAMAGUCHI, HIDEKI, HIRAMATSU, SOICHI, C/O CANON K.K., INOUE, HIROYUKI, C/O CANON K.K., IWASAKI, TAKESHI, C/O CANON K.K., KAWAKAMI, HIDEAKI, C/O CANON K.K., KIDA, AKIRA, C/O CANON K.K., NAKAMURA, HITOSHI, C/O CANON K.K., NOJIMA, TAKASHI, C/O CANON K.K., YAMAGUCHI, HIDEKI, C/O CANON K.K.
Applicants: CANON KK, CANON KABUSHIKI KAISHA
Application year: 1995
Main classification: B41J23
IPC codes: B41J2, B41J23, F16H27