Patent Publication Number: US-2005117011-A1

Title: Image-recording device

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to an image-recording device, and more particularly to an image-recording device that conveys an image recording sheet and performs image recording on a surface of the sheet.  
      2. Description of the Related Art  
      Conventionally, in an image-recording device such as, for example, an inkjet recording device, image recording has been carried out by conveying paper for recording (a recording sheet) in a certain direction while discharging ink drops onto the recording paper in accordance with image information. That is, an inkjet recording head is operated to move in a direction intersecting the conveyance direction of the recording paper while discharging the ink drops (main scanning), and is repeatedly reciprocated as the recording paper is conveyed (sub-scanning). Thus, an image is recorded on the recording paper. Accordingly, in order to record images at higher image quality, improvements in accuracy of conveyance of the recording paper are required.  
      Many ordinary inkjet recording devices and the like have structures in which the recording paper is conveyed by supply rollers, which are disposed at an upstream side of an image recording region, and ejection rollers, which are disposed at a downstream side. In an inkjet recording device having such a structure, in order that the recording paper can be conveyed with high accuracy throughout the entire conveyance direction range of the recording paper, a speed of rotation of the supply rollers is set to a prescribed value corresponding to a conveyance speed of the recording paper. A speed of rotation of the ejection rollers may be set to be slightly faster than the speed of rotation of the supply rollers. In such a constitution, the recording paper is conveyed at a certain conveyance speed by the supply rollers. The ejection rollers rotate so as to slip a little with respect to the recording paper, and the recording paper is stretched between the ejection rollers and the supply rollers while being conveyed. Consequently, a separation between the inkjet recording head and the recording paper is kept stable. Hence, a reduction in image quality that could be caused by variations in this separation can be avoided.  
      However, in an inkjet recording device having the structure described above, when a back end vicinity portion of the recording paper is released from the supply rollers during the conveyance of the recording paper, the recording paper is subsequently conveyed only by the ejection rollers. Here, because the ejection rollers rotate more quickly than the supply rollers, the conveyance speed of the recording paper becomes larger. Thus, for example, the intervals between the recording lines may become larger and “white ground” portions may result.  
      As a solution to this kind of problem, Japanese Patent No. 2,810,476, for example, describes a control method for transporting paper in a recording device. A sheet transport speed of a pair of rotating bodies at a recording sheet feed-in side of a printing section is set to V 1 , a sheet transport speed of a pair of rotating bodies at a recording sheet feed-out side of the printing section is set to V 2 , and V 2 &gt;V 1 . While the sheet is nipped by the rotating body pairs at both the feed-in side and the feed-out side or by only the rotating body pair at the feed-in side, the sheet is transported at the speed V 1 . But when a rear end of the paper has separated from the rotating body pair at the feed-in side, the sheet transport speed of the rotating body pair at the recording sheet feed-out side is (immediately) adjusted from V 2  to V 1 .  
      However, to implement this control method, it is necessary to provide, for example, a sensor for detecting when the recording sheet has passed through the rotating body pair at the feed-in side and a pulse generator or the like for efficiently applying input pulses to motors that drive each of the rotating body pairs. Hence, the number of components increases, and this leads to increased costs.  
      Accordingly, Japanese Patent Application Laid-Open (JP-A) No. 11-91177 describes an image-recording device constituted so as to alter control of image recording when a recording sheet is being conveyed by only one of an upstream side conveying means and a downstream side conveying means. For example, when the recording sheet is being conveyed by only the downstream side conveying means, a recording interval may be reduced. Also, conveyance amounts by the downstream side conveying means are correspondingly reduced. In such a device, control is performed suitably for a front end and a back end of the recording sheet, and thus printing quality is improved.  
      However, in this structure, when the conveyance amounts of the recording sheet are decreased to such an extent that a deterioration of print quality does not occur, a number of scanning passes by a carriage, to which an inkhead is mounted, is relatively increased by the same proportion. Consequently, when image recording is to be applied to the whole of the recording sheet, recording duration is lengthened.  
     SUMMARY OF THE INVENTION  
      In consideration of the above-described situation, an object of the present invention is to provide an image-recording device that can record an image of high image quality by keeping conveyance amounts consistent for the whole of a recording sheet, without causing an increase in costs.  
      In a first aspect of the present invention, an image-recording device includes: image-recording means capable of recording an image on a recording sheet at an image recording region of the device; a supply roller which supplies the recording sheet to the image recording region; an ejection roller which ejects the recording sheet from the image recording region; a common drive source which applies rotary driving force to the supply roller and the ejection roller; a supply side transmission member for transmitting driving force from the drive source to the supply roller; and an ejection side transmission member for transmitting driving force from the drive source to the ejection roller, wherein the supply side transmission member and the ejection side transmission member each include the same structure.  
      That is, in this image-recording device, the image-recording means records an image on the recording sheet that has been supplied to the image recording region by the supply roller. Thereafter, the ejection roller ejects the recording sheet from the image recording region.  
      The supply roller and the ejection roller receive rotary driving force from the shared drive source and are rotated. The supply side transmission member, which transmits driving force from the drive source to the supply roller, and the ejection side transmission member, which transmits driving force from the drive source to the ejection roller, have the same constitution. Consequently, the supply roller and the ejection roller rotate in the same manner, and can convey the recording sheet at the same conveyance speed. Therefore, the recording sheet is conveyed at a constant speed whether being conveyed by both or by just one of the supply roller and the ejection roller, throughout the entire region of the recording sheet. Thus, images can be recorded at high image quality without the occurrence of “white ground” and the like. Because there is no need to adjust the conveyance speed of the recording sheet, parts and the like for such adjustment are not required. A single drive source can be used and, because the supply side transmission member and the ejection side transmission member have the same constitution, the number of components is not greatly increased, so an increase in costs will not be caused.  
      Moreover, because the recording sheet is always being conveyed at a constant speed during image recording, the recording duration is not increased when the image is recorded over the whole of the recording sheet. Thus, an image can be recorded onto the whole of the recording sheet in a short time.  
      Further, because a single drive source can be used, structure can be further simplified.  
      In a second aspect of the present invention, the supply side transmission member and the ejection side transmission member are respectively structured with gears of the same numbers and same shapes.  
      The specific constitution of the supply side transmission member and the ejection side transmission member is not particularly limited. However, if the two members are constituted of gears having the same numbers and the same shapes, driving force can be transmitted from the drive source to the supply roller and the ejection roller with high accuracy.  
      In a third aspect of the present invention, the drive source is disposed such that, viewed from a direction normal to the recording sheet at the image recording region (i.e., in plan view), either the drive source is adjacent to the image recording region or the drive source at least partially overlaps the image recording region.  
      Accordingly, as viewed from the normal direction of the recording sheet, an amount by which the drive source protrudes relative to the image recording region can be made small (and is preferably eliminated). Therefore, the image recording device can as a whole be made more compact. In view thereof, it is preferable if the drive source is disposed so as to partly overlap with the image recording area, and more preferable if the drive source is disposed so as to completely overlap with the image recording area.  
      In a fourth aspect of the present invention, the supply roller and the ejection roller are disposed adjacent to the image recording region.  
      As a result, the image recording device can as a whole be made more compact.  
      A fifth aspect of the present invention includes a limiting member which is disposed at both of width direction ends of the recording sheet and which limits displacement in a thickness direction of the recording sheet to a certain range.  
      That is, displacement in the thickness direction of the recording sheet (for example, lifting of the recording sheet or the like) is limited to within the prescribed range by the limiting member. Therefore, a separation distance between the recording sheet and the image recording means can also be limited to a certain range. Consequently, high image quality image recording can be performed.  
      In the first to fourth aspects described above, the size of the image-recording device and the size of the recording sheet, which is an object of image recording by the image-recording device, are not particularly limited. For example, a relatively compact image-recording device can be provided for “A6” and “postcard size” recording sheets and the like. Also, the kinds of recording sheet on which images can be recorded are not particularly limited. For example, papers such as “high quality paper”, resin films such as “OHP sheets”, and the like can be used as recording sheets.  
      In a sixth aspect of the present invention, an image-recording device for recording an image on a recording sheet that is conveyed at an image-recording region includes: a supply roller which supplies the recording sheet to the image recording region; an ejection roller which ejects the recording sheet from the image recording region; a drive source common to the supply roller and the ejection roller, provided between the supply roller and the ejection roller; a first gear provided between the supply roller and the drive source, the first gear transmitting driving force from the drive source to the supply roller; and a second gear provided between the ejection roller and the drive source, the second gear transmitting driving force from the drive source to the ejection roller.  
      According to a structure based on the sixth aspect, the first and second gears, which are driven by the shared drive source, drive the supply roller and the ejection roller. Therefore, the supply roller and the ejection roller can be reliably rotated at the same angular velocity. Thus, the conveyance speed of the recording sheet is the same at each of the supply roller and the ejection roller. Hence, images can be recorded at high image quality, and the image-recording device can be made significantly compact.  
      In a seventh aspect of the present invention, the first gear and the second gear each includes a single idle gear, the respective idle gears having the same shape as one another. According to this aspect, the supply roller and the ejection roller can be more reliably driven at the same speed. In particular, control of conveyance of a back end of the recording sheet can be performed simply and reliably.  
      In an eighth aspect of the present invention, the image-recording device further includes: a platen provided between the supply roller and the ejection roller in correspondence with the image recording region, the recording sheet being conveyed on a platen surface; a carriage which is movable in a main scanning direction which intersects a direction of conveyance of the recording sheet; and a recording head which records images, and is provided at the carriage and facing the image recording region.  
      In a ninth aspect of the present invention, the first and second gears and the drive source are provided adjacent to the platen at a rear surface side of the platen, which rear surface is an opposite side of the platen from the platen surface.  
      In a tenth aspect of the present invention, a guide which prevents lifting in a thickness direction of the recording sheet is provided at both of recording sheet width direction ends of the platen. In a structure based on this aspect, conveyance of the recording sheet can be controlled more reliably.  
      In an eleventh aspect of the present invention, the guide has a shape which not only controls lifting of the recording sheet in the thickness direction thereof but also limits movement of the recording sheet in a width direction thereof. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a perspective view showing an image-recording device of a first aspect of the present invention.  
       FIG. 2  is a perspective view showing the image-recording device of the first aspect of the present invention.  
       FIG. 3  is a sectional view showing the image-recording device of the first aspect of the present invention.  
       FIG. 4  is a plan view showing the image-recording device of the first aspect of the present invention.  
       FIG. 5  is an enlarged, explanatory view of a supply side transmission member and an ejection side transmission member of the image-recording device of the first aspect of the present invention.  
       FIG. 6  is a schematic sectional view showing a recording region of the image-recording device of the first aspect of the present invention, cut along a transverse direction.  
       FIG. 7  is an enlarged, explanatory view of a supply side transmission member and an ejection side transmission member of an image-recording device of a second aspect of the present invention.  
       FIG. 8  is an enlarged, explanatory view of a supply side transmission member and an ejection side transmission member of an image-recording device of a third aspect of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      FIGS.  1  to  4  show an inkjet recording device  12 , which is an image-recording device of a first embodiment of the present invention.  
      The inkjet recording device  12  includes an image-recording main body  14 , a recording sheet supply apparatus  16  and a recording sheet ejection apparatus  18 . The image-recording main body  14  is capable of recording images on sheets for recording  20  (see  FIGS. 3, 5  and  6 ), at a predetermined recording region  22  (shown in  FIG. 4 ). The recording sheet supply apparatus  16  supplies the recording sheets  20  to the recording region  22 , and the recording sheet ejection apparatus  18  discharges the recording sheets  20  from the recording region  22 .  
      The inkjet recording device  12  further includes a supply tray  24 , at which the recording sheets  20  can be stacked in a thickness direction thereof. A topmost one of the recording sheets  20  stacked at the supply tray  24  is conveyed in the direction of arrow A by a pickup roller  26  and moved toward the recording region  22 . Hereinafter, the term “conveyance direction” represents the conveyance direction of the recording sheet  20 , as shown by the arrow A in the drawings. Further, the term “width direction” represents a width direction of the recording sheet  20  intersecting the conveyance direction, as shown by arrow W in the drawings.  
      The image-recording main body  14  includes a frame member  28 , which is shaped substantially like a frame. A carriage  30  is attached to the frame member  28  so as to be movable in the width direction. An inkjet recording head  32  is mounted to the carriage  30  and fixed at a predetermined attachment position. An ink discharge port of the inkjet recording head  32  opposes a surface of the recording sheet  20  in the recording region  22 . The inkjet recording head  32  discharges ink drops in accordance with image information while moving in the width direction of the recording sheet  20  (the direction of the arrow W) integrally with the carriage  30 . Thus, “main scanning” is carried out.  
      A platen  34  is fixed at a position corresponding to the recording region  22  (a region through which an ink discharge area moves, which depends on a main scanning range of the inkjet recording head  32 ). The recording sheet  20  is disposed on the platen  34 , and thus a lower surface (rear surface) of the recording sheet  20  is supported.  
      As shown in detail in  FIG. 6 , lifting prevention guides  36  are attached to the frame member  28  via attachment members  38 . The lifting prevention guides  36  encompass both of width direction sides of the platen  34 , and oppose an upper side and both of width direction end portion sides of the recording sheet  20 . Consequently, movement in the thickness direction of the recording sheet  20  (a vertical direction) is limited by the platen  34  and the lifting prevention guides  36 , and flatness of the recording sheet  20  during image recording is assured. Also, movement in the width direction of the recording sheet  20  is limited by the lifting prevention guides  36 . Consequently, it is to be expected that the attitude of the recording sheet  20  in the recording region  22  will be stable.  
      In particular, in an inkjet-type image-recording device, such as that of the present embodiment, which performs image recording by adhering ink drops to the recording sheet  20 , there is a possibility that lifting of the recording sheet  20  at the platen  34  could become significant, causing a deterioration of image quality. This can be caused due to such factors as the type of the recording sheet  20 , the environment during printing, and the amounts of ink being adhered. Therefore, it is preferable that the attitude of the recording sheet  20  be stabilized as in the present embodiment, at least at the recording region  22 .  
      A supply roller  40  is disposed at an upstream side of the platen  34 , adjacent to the recording region  22  and suspended along the frame member  28 . An unillustrated shaft is disposed upward of the supply roller  40 , and a facing supply roller  42  is attached at this shaft.  
      The supply roller  40  is formed to be longer than the width of the recording sheet  20 . The supply roller  40  contacts the recording sheet  20  from the lower surface side thereof. A plurality of the facing supply roller  42  (four in the present embodiment) are disposed along the supply roller  40  in the width direction. The facing supply rollers  42  contact the recording sheet  20  from the upper surface side thereof. The recording sheet  20  is nipped by the supply roller  40  and the facing supply rollers  42 . Thus, in this nipped state, when the supply roller  40  rotates, the recording sheet  20  is conveyed and is supplied to the recording region  22 .  
      An ejection roller  44  is disposed at a downstream side of the platen  34 , adjacent to the recording region  22  and suspended along the frame member  28 . An unillustrated shaft is disposed upward of the ejection roller  44 , and facing ejection rollers  46  are attached at this shaft.  
      Similarly to the supply roller  40 , the ejection roller  44  is formed to be longer than the width of the recording sheet  20 . The ejection roller  44  contacts the recording sheet  20  from the lower surface side thereof. The facing ejection rollers  46  are disposed at each of width direction end portions of the recording sheet  20 . The facing ejection rollers  46  contact the recording sheet  20  from the upper surface side thereof. The recording sheet  20  is nipped by the ejection roller  44  and the facing ejection rollers  46 . In this nipped state, when the ejection roller  44  rotates, the recording sheet  20  is conveyed and is ejected from the recording region  22 . The facing ejection rollers  46  contact both of end vicinity portions, in the width direction, of the recording sheet  20 , that is, portions for which it has been specified in advance that ink will not be adhered by the inkjet recording head  32  during image recording. Accordingly, the transfer of ink which has not been dried to the facing ejection rollers  46  and re-transfer of this ink back to the recording sheet  20 , which would cause a reduction in image quality, does not occur.  
      As shown in detail in  FIG. 5 , a driving motor  48  is disposed between the supply roller  40  and the ejection roller  44 . Driving force of the driving motor  48  is transmitted from an output gear  50  of the driving motor  48  to two idle gears  52  and  54 . Input gears  56  and  58  are coaxially fixed with the supply roller  40  and the ejection roller  44 , respectively. The driving force is transmitted from the idle gears  52  and  54  to the input gears  56  and  58 . Thus, the supply roller  40  and the ejection roller  44  are rotated.  
      The idle gears  52  and  54  have the same shapes as one another, and are disposed at positions which are symmetrical about a center line C, which passes through the center of the output gear  50  of the driving motor  48 . Moreover, because the input gear  56  of the supply roller  40  and the input gear  58  of the ejection roller  44  have the same shapes as one another and are disposed at positions which are symmetrical about the center line C, a supply side driving force transmission system  62 , from the driving motor  48  to the supply roller  40 , and an ejection side driving force transmission system  64 , from the driving motor  48  to the ejection roller  44 , are structured by the same number of gears, with the same shapes at the corresponding positions. Thus the supply side driving force transmission system  62  and the ejection side driving force transmission system  64  have completely the same structure as one another.  
      As can be seen in  FIG. 4 , when the inkjet recording device  12  is observed in plan view, the driving motor  48  is seen to be disposed at a position adjacent to the recording region  22  (or, more strictly, at a partly overlapping position). Therefore, it can be expected that the inkjet recording device  12  will as a whole be more compact than in a case of the driving motor  48  being disposed at a position apart from the recording region  22 . In view of this point, it is preferable that the driving motor  48  is disposed so as to partially overlap the recording region  22  in plan view, rather than simply being disposed adjacent to the recording region  22 , and it is more preferable that the driving motor  48  is disposed so as to completely overlap the recording region  22 .  
      In the inkjet recording device  12  of the present embodiment, the supply roller  40  and the ejection roller  44  each includes a stiff outer peripheral surface formed as a column or hollow cylinder. Surface treatment is applied thereto such that the outer peripheral surface can exhibit a predetermined frictional force with respect to the recording sheet  20 . Thus, the supply roller  40  and the ejection roller  44  are surface-machined rigid rollers. As a result, because a rigid body can be used as a base material of the roller, diametric accuracy and a run-out tolerance dimension are excellent compared to rubber rollers made of EPDM materials and the like, which are commonly used for conveyance of recording sheets. Also, environmental variations of the diameter are extremely small and dimensional stability is excellent.  
      Further, because, due to the surface treatment, the surface exhibits a predetermined frictional force with respect to the recording sheet  20 , the supply roller  40  and the ejection roller  44  will not slip with respect to the recording sheet  20  during conveyance of the recording sheet  20 , and conveyance can be performed with high accuracy.  
      As long as the above conditions are satisfied, the specific constitutions of the supply roller  40  and the ejection roller  44  are not particularly limited. For example, a metal may be used as the rigid body, and the surface of this metallic base material may be coated with ceramic or urethane. Such a roller is preferable, in that it has precise dimensions, diametric stability with respect to environmental changes, and stability in coefficient of friction.  
      The facing supply roller  42  and the facing ejection rollers  46  should nip the recording sheet  20  against the supply roller  40  and the ejection roller  44 , respectively, with nipping forces that are suitable for reliably conveying the recording sheet  20 . Also, the facing supply roller  42  and the facing ejection rollers  46  should not cause damage or the like to the surfaces of the supply roller  40  and the ejection roller  44  by local concentrations of pressure. Thus, the facing supply roller  42  and the facing ejection rollers  46  should have appropriate resiliency. As long as these conditions are satisfied, materials of the facing supply roller  42  and the facing ejection rollers  46  are not particularly limited. In the present embodiment the facing supply roller  42  and the facing ejection rollers  46  are formed of fluorine-containing elastomers, in view of assuring high reliability.  
      A discharge tray  60  is attached at a conveyance direction downstream side of the image-recording main body  14 . Recording sheets  20  on which images have been recorded are ejected to the discharge tray  60 .  
      Parameters of the above-described members for conveying the recording sheet  20  are decided in accordance with various conditions such as the number of recording sheets  20  in a stack as determined by specifications of the inkjet recording device  12 , types of the recording sheets  20 , anticipated environments (temperature and humidity) and the like, so that the conveyance performance of the members is affected as least as possible by change/variations of such conditions.  
      Now, operation of the inkjet recording device  12  of the present embodiment will be described.  
      The topmost of the recording sheets  20  stacked on the supply tray  24  is conveyed in the direction of the arrow A by the pickup roller  26 . Then, the recording sheet  20  is nipped by the supply roller  40  and the facing supply roller  42 , from the front end side of the recording sheet  20 , and the recording sheet  20  is conveyed further by rotation of the supply roller  40 .  
      When the recording sheet  20  reaches the recording region  22 , conveyance of the recording sheet  20  is temporarily halted. Then, the carriage  30  moves in the width direction (the direction of the arrow W) and, at the same time, the inkjet recording head  32  discharges ink drops to the upper surface of the recording sheet  20  from the unillustrated ink discharge port in accordance with image information. Thus, main scanning is carried out. When main scanning has been completed for one line, the supply roller  40  rotates such that the recording sheet  20  is conveyed by an amount of precisely one line width (a distance in the conveyance direction). Hence, the recording sheet  20  is conveyed and sub-scanning is carried out.  
      In this manner, main scanning and sub-scanning are alternately repeated, and a desired image is recorded on the upper surface of the recording sheet  20 .  
      During image recording (or, depending on the relation between the size of the image and the size of the recording sheet  20 , after image recording has finished), the recording sheet  20  is nipped by the ejection roller  44  and the facing ejection rollers  46 , from the front end side of the recording sheet  20 , and the recording sheet  20  is conveyed further by rotation of the ejection roller  44 . That is, the recording sheet  20  will be nipped at both the front end side and rear end side thereof, as shown in  FIG. 5 , until a portion nipped by the supply roller  40  and the facing supply roller  42  at the rear end of the recording sheet  20  is released.  
      Then, when the portion nipped by the supply roller  40  and the facing supply roller  42  at the rear end of the recording sheet  20  has been released, the recording sheet  20  is nipped and conveyed only by the ejection roller  44  and the facing ejection rollers  46 . While the image is being recorded on the recording sheet  20 , the ejection roller  44  repeatedly halts and rotates in accordance with single line widths (the distance in the conveyance direction), in the same manner as the supply roller  40 . When image recording has finished, the ejection roller  44  rotates continuously and the recording sheet  20  is ejected in a short time.  
      Here, in the inkjet recording device  12  of the present embodiment, the supply side driving force transmission system  62 , from the driving motor  48  to the supply roller  40 , and the ejection side driving force transmission system  64 , from the driving motor  48  to the ejection roller  44 , have the same structure as one another. Resultantly, the supply roller  40  and the ejection roller  44  rotate at the same angular velocity as one another, and have the same conveyance speed with respect to the recording sheet  20 . Therefore, the recording sheet  20  is stably conveyed at the same speed regardless of whether the recording sheet  20  is being conveyed by conveyance force from one of the supply roller  40  and the ejection roller  44  or from both of the supply roller  40  and the ejection roller  44 , for the whole area of the recording sheet  20 . Thus, a high quality image can be recorded without the occurrence of “white ground” or the like. There is no need, as in the conventional art, for ejection side rollers to have a higher rotation speed or for the rotation speed of these rollers to be controlled in accordance with position of the recording sheet  20 . Moreover, because the single driving motor  48  is used and the supply side driving force transmission system  62  and the ejection side driving force transmission system  64  have structures in common, the inkjet recording device  12  can be structured at low cost.  
      Further, in the inkjet recording device  12  of the present embodiment, movement in the thickness direction (a vertical direction) of the recording sheet  20  is limited by the lifting prevention guides  36 . Thus, flatness of the recording sheet  20  during image recording is assured. As a result, because the separation between the ink discharge port of the inkjet recording head  32  and the recording sheet  20  can be kept constant, high quality images can be recorded.  
      A structure for the supply roller  40  and the ejection roller  44  to be rotated at the same speed by driving force from the driving motor  48  is not limited to the structure described above. For example, a structure shown in  FIG. 7 , a structure shown in  FIG. 8 , or the like can be used. With these structures, the overall constitution of the inkjet recording device is the same as above, so descriptions thereof can be omitted. Structural elements, components and the like that are the same as for the first embodiment are given the same reference numbers and need not be described further.  
      An inkjet recording device of a second embodiment, shown in  FIG. 7  (the whole body is not shown), uses endless-type toothed belts  66  and  68  instead of the idle gears  52  and  54 . The endless toothed belts  66  and  68  structure a supply side driving force transmission system  70  and an ejection side driving force transmission system  72 , respectively. Specifically, the endless toothed belt  66  winds around the output gear  50  and the input gear  56 , and the endless toothed belt  68  winds around the output gear  50  and the input gear  58 .  
      Accordingly, in the inkjet recording device of the second embodiment, the supply roller  40  and the ejection roller  44  rotate at the same angular velocity as one another and have the same conveyance speed with respect to the recording sheet  20 . As above, the recording sheet  20  can be stably conveyed at the same speed regardless of whether the recording sheet  20  is being conveyed by conveyance force from the supply roller  40  or the ejection roller  44 , and a high quality image can be recorded. Also, because the supply side driving force transmission system  70  and the ejection side driving force transmission system  72  have structures in common, the inkjet recording device can be structured at low cost.  
      It is preferable that tension rollers  74  are provided so as to constantly apply a predetermined tension to the endless toothed belts  66  and  68 . However, the tension rollers  74  may be omitted, and the structure thus simplified, as long as the predetermined tension is applied to the endless toothed belts  66  and  68 .  
      In an inkjet recording device of a third embodiment, shown in  FIG. 8 , an endless driving belt  76  is wound around three gears, the output gear  50 , the input gear  56  and the input gear  58 . This embodiment is substantially a case in which the endless toothed belts  66  and  68  of the second embodiment are combined to one belt and the single belt is used for both the supply side and the ejection side. Consequently, the number of components can be further decreased, and the inkjet recording device can be constructed at even lower cost.  
      Thus, various structures can be employed for transmitting driving force of the driving motor  48  to the supply roller  40  and the ejection roller  44 . Because the second embodiment and the third embodiment do not use the idle gears  52  and  54  of the first embodiment, members that support the idle gears  52  and  54  can be omitted, and the structure made simpler. On the other hand, if the idle gears  52  and  54  are used, as in the first embodiment, driving force can be transmitted with a higher accuracy than when endless toothed belts are used as in the second embodiment and third embodiment.  
      Also, although the positions of the supply roller  40  and the ejection roller  44  are not particularly limited as long as the recording sheet  20  is reliably conveyed, by disposing the supply roller  40  and the ejection roller  44  adjacent to the recording region  22 , it can be expected that the inkjet recording device  12  will as a whole be more compact.  
      Size and the like of the recording sheet  20 , which is the object of image recording, are not particularly limited for any of the inkjet recording devices of these embodiments. However, bearing in mind that the facing ejection rollers  46  nip the recording sheet  20  only at both end vicinity portions in the width direction thereof, if the object of recording is, for example, A6 size or postcard size, the object of recording is preferably conveyed with a short side direction thereof set along the width direction. This is preferable because lifting of the recording sheet at a width direction central portion thereof can be more reliably prevented.  
      The embodiments described above are examples of image-recording devices of the present invention. Examples of inkjet recording devices that record images on recording sheets (recording paper) by inkjet methods have been explained. Image-recording devices of the present invention are not limited to devices that use such inkjet methods. For example, the present invention may also be applied to devices that use electrophotographic methods. In such a case, a structure applicable to electrophotography may be employed for the main body of the recording device.  
      To summarize, with the present invention, conveyance amounts are consistently maintained throughout the whole area of a recording sheet by the constitutions described above. Thus, images of high image quality can be recorded without incurring an increase in costs.