JP2007254122A - Conveying roller pair and recording apparatus using the conveying roller pair - Google Patents

Abstract

Provided are a transport roller pair and a recording apparatus capable of improving the transport accuracy of a recording sheet with a simple and inexpensive configuration, and capable of eliminating the deterioration in image quality of a recorded image due to the decrease in transport accuracy.
In a conveying roller pair including a driving roller 10 and a driven roller 21 that convey a recording sheet through a recording unit of a recording apparatus, 10% of a fine particle resin material is applied to a urethane elastomer as a base material as a material of a surface layer of the driven roller. The one containing 20 to 20% is used. As the fine particle resin material, an acrylic resin or polyethylene resin particle material having a particle diameter of 10 μm to 20 μm is used. The surface friction coefficient of the surface layer of the driven roller is 0.2 or less, and the surface roughness (Rz) of the surface layer is 20 μm or less.
[Selection] Figure 1

Description

  The present invention relates to a conveying roller pair including a driving roller and a driven roller that convey a recording sheet through a recording unit of a recording apparatus, and a recording apparatus using the conveying roller pair.

  Generally, a recording apparatus having a function such as a printer, a copying machine, or a facsimile uses an image (characters, symbols, etc.) on a sheet-like recording medium such as paper, cloth, a plastic sheet, and an OHP sheet by a recording head based on image information. Configured to form). In the present application, a sheet-like recording medium is referred to as a recording sheet. There are a serial type and a line type as a scanning method in the recording apparatus. The serial type is a system in which an image is recorded while alternately repeating main scanning for moving the recording head along the recording sheet and sub-scanning for feeding the recording sheet at a predetermined pitch. The line type is a system in which an image is recorded only by feeding a recording sheet (sub-scan) while recording one line at a time. The recording apparatus can be classified into an ink jet type, a thermal transfer type, a laser beam type, a thermal type, a wire dot type, and the like depending on the type of the recording head.

  In general, a recording apparatus uses a pair of conveying rollers including a driving roller and a driven roller that convey a recording sheet through a recording unit. In recent years, image quality has been improved in recording apparatuses, and high accuracy is also required in the configuration and operation of recording sheet conveying means. Therefore, in order to realize high-accuracy conveyance, a pair of conveyance rollers including a driving roller in which ceramic powder having a center particle diameter of 20 μm to 70 μm is adhered to a metal surface and a driven roller that is driven to rotate while being pressed against the driving roller. The structure of the transport mechanism using the is widely used. Such a transport mechanism is disclosed in Patent Document 1 and Patent Document 2, for example.

On the other hand, there are a wide variety of recording sheets, especially from high-rigidity sheets such as cardboard to flexible sheets such as film-based paper, and their uses are diversified. For this reason, a pair of conveyance rollers including a driving roller and a driven roller in the recording apparatus is also required to have a high conveyance force (high sheet grip force). Therefore, an elastic roller made of a material that can obtain a large conveying force by expanding the nip area of the recording sheet clamping portion even when the pressure contact force with respect to the driving roller is relatively small is used as the driven roller. Such an elastic roller is disclosed in Patent Document 3 and Patent Document 4, for example.
JP 2004-010994 A JP-A-10-120234 Japanese Patent No. 3339628 Japanese Patent Laid-Open No. 11-314789

  However, the recording apparatus using the pair of conveyance rollers as described above has the following problems. That is, EPDM (ethylene / propylene / diene copolymer), chlorinated polyethylene, or the like that can provide high deformation recovery performance and low rubber hardness (40 degrees Hs to 60 degrees Hs) is used for paper feed rollers and the like. However, these materials contain an oil and fat component which is a plastic material. Therefore, when these materials are used for the driven roller (elastic roller), the oil and fat component oozes out on the roller surface, and the oil and fat component is transferred to the driven roller passing surface which is the printing surface of the recording sheet. As a result, it becomes difficult for ink to permeate through the transfer portion of the recording sheet, resulting in unevenness in the recorded image and image quality degradation.

  In the case of a cut recording sheet (cut sheet), the leading end of the recording sheet is brought into contact with the nip portion of the driving roller and the driven roller to perform leading edge alignment (referred to as resist removal). At this time, if the friction coefficient of the surface of the driven roller (pinch roller) is high, the leading edge of the recording sheet is not guided to the nip, leading to leading edge breakage or jamming. As materials of the driven roller for preventing this, for example, Patent Document 3 and Patent Document 4 disclose fluorine-containing elastomers and those having a surface coated with a fluorine resin. However, the fluororesin itself is expensive, and in addition to this, the coating process further increases the cost. Further, when the coating treatment is performed, the hardness of the surface layer is increased, and therefore, a paper type having a low surface strength (for example, Clear Film, made by Sakurai Co., Ltd., Starjet 400CL) causes surface scratches.

  The present invention has been made in view of such technical problems. SUMMARY OF THE INVENTION An object of the present invention is to provide a pair of conveying rollers and a recording apparatus that can improve the conveyance accuracy of a recording sheet with a simple and inexpensive configuration and can eliminate the deterioration in the image quality of a recorded image due to the decrease in the conveyance accuracy. It is to be.

  The present invention relates to a pair of conveying rollers including a driving roller and a driven roller that convey a recording sheet through a recording unit of a recording apparatus. As the material for the surface layer of the driven roller, a urethane elastomer that is a base material containing 10% to 20% of a fine particle resin material is used.

  According to the present invention, a conveyance roller pair and a recording apparatus that can improve the conveyance accuracy of a recording sheet with a simple and inexpensive configuration and can eliminate the deterioration in the image quality of a recorded image due to the decrease in the conveyance accuracy are provided. Is done.

  Embodiments of the present invention will be specifically described below with reference to the drawings. Note that the same reference numerals denote the same or corresponding parts throughout the drawings. FIG. 6 is a longitudinal sectional view of a recording apparatus suitable for applying the present invention. FIG. 6 illustrates the case where the recording apparatus is an inkjet recording apparatus. 6, the recording apparatus includes a paper feeding unit 200, a transport mechanism 300, a recording unit 500, a paper discharge unit 600, a recovery processing unit (not shown), and a U-turn transport mechanism 800. The recording unit 500 records an image while scanning a recording sheet, which is a recording medium, by a recording head 52 mounted on a carriage 51 that can reciprocate.

  The paper feed unit 200 is configured by attaching a pressure plate 53, a paper feed roller 54, a separation roller 55, a paper feed tray (not shown), and the like to a base (not shown). A recording sheet is stacked on the pressure plate 53. The paper feed roller 54 feeds the recording sheet to the transport mechanism and the recording unit. The separation roller 55 separates so as to feed only one recording sheet. The paper feed tray is for holding the latter half of the recording sheets stacked on the pressure plate 53. The paper feed roller 54 is an arc-shaped roller with a circular part cut out. A side guide for regulating the recording sheet stacking position is slidably attached to the pressure plate 53. The pressure plate 53 is swingable and is urged against the paper feed roller 54 by a pressure plate spring (not shown). A separation sheet (not shown) having a large friction coefficient is provided at a portion of the pressure plate 53 facing the sheet feeding roller to prevent double feeding of recording sheets. The pressure plate 53 is brought into contact with and separated from the paper feed roller 54 at a predetermined timing by a cam (not shown).

  The transport mechanism 300 is provided with transport roller pairs 10 and 21 for transporting the recording sheet. The pair of conveying rollers is composed of a driving roller 10 and a driven roller (pinch roller) 21 that applies a conveying force to the recording sheet by being driven and pressed against the driving roller 10. The driving roller 10 is pivotally supported by bearings provided on the chassis at both ends. The recording sheet conveyance amount is detected by a code wheel provided on the shaft of the driving roller 10 and an encoder sensor attached to an adjacent portion thereof. The recording sheet can be accurately conveyed through the recording unit 500 by such a conveyance mechanism having the conveyance roller pairs 10 and 21. An image is recorded on the entire recording sheet by alternately repeating image recording by the recording head 52 and conveyance of the recording sheet.

  The recording unit 500 is configured on the downstream side in the transport direction of the pair of transport rollers 10 and 21. The recording unit 500 is provided with a recording head 52 that records an image on a recording sheet based on image information. The recording head 52 is mounted on a carriage 51 that can reciprocate in the left-right direction. The recording head of this embodiment is an ink jet recording head. An ink discharge portion (discharge surface) is provided at a portion of the recording head 52 facing the recording sheet. On the ejection surface, an ejection port array including a plurality of ejection ports that eject ink droplets based on image information is provided. In the case of color recording, a plurality of ejection port arrays are provided for different ink colors. As the ink discharge unit, for example, electric heat is applied to the ink inside the discharge port by applying heat energy by a heater to cause film boiling, and ink droplets are discharged from the discharge port by pressure change caused by the growth or contraction of bubbles due to the film boiling. A conversion formula is used.

  At a position facing the recording head 52, a platen 58 is provided for guiding and supporting the recording sheet while maintaining an appropriate distance between the conveyed recording sheet and the ink discharge portion of the recording head 52. The carriage 51 on which the recording head is mounted is guided and supported so as to reciprocate in the left-right direction along a guide shaft 57 and a guide rail (not shown). The carriage 51 is driven by a carriage motor (not shown) via a timing belt (not shown). The position and speed of the carriage are detected by reading with an encoder sensor mounted on a code strip carriage 51 arranged in parallel with the guide shaft 57. In addition, a flexible substrate for transmitting a head signal to the recording head is connected to the carriage. The recording sheet is set at the recording start position by the conveying roller pair 10 and 21 and is conveyed through the image forming position. By moving the carriage 51 with respect to the recording sheet, the recording head 52 performs recording for one line based on the image information. An image is recorded on the entire recording sheet by alternately repeating the conveying operation and recording for one line.

  The paper discharge unit 600 includes two paper discharge rollers 61 and 62. These paper discharge rollers are connected to the driving roller 10 of the pair of conveying rollers via a gear train or the like, and are driven in synchronization with the driving roller. A spur 63 is urged to each paper discharge roller so as to be driven to rotate. The drive of the driving roller 10 is transmitted to the paper discharge roller 61, and the drive of the paper discharge roller 61 is transmitted to the paper discharge roller 62 via an idle gear. Each spur 63 is supported by a shaft made of a coil spring so as to be rotatable to the spur holder 65 and pressed against the paper discharge rollers 61 and 62. The recording sheet recorded by the recording head 52 is conveyed between the discharge rollers 61 and 62 and the nip portions of the respective spurs 63, and is discharged from the apparatus main body.

  The recovery processing unit (not shown) is for preventing clogging of the ejection port of the recording head 52 and maintaining and recovering the ink ejection performance in the ink jet recording apparatus. The recovery processing unit includes a suction pump, a cap, and a wiper. The cap is in close contact with the ejection surface of the recording head 52 and covers the ejection port, thereby reducing ink drying of the recording head. The suction pump is connected to the cap, and sucks ink from the ejection port in a state where the ejection port is sealed with the cap, thereby refreshing the ink in the ejection port. The wiper wipes and cleans the ejection surface of the recording head.

  The U-turn conveyance mechanism 800 is to reverse the recording sheet and convey it to the recording unit 500 when performing double-sided recording on the recording sheet. The U-turn conveyance mechanism 800 is provided with a U-turn conveyance path for enabling backside printing. A paper feed cassette 81 that stores recording sheets is mounted at a position near the front of the lower part of the apparatus main body. The leading end portion of the recording sheets stacked on the paper feed cassette 81 is pressed against the paper feed roller 83 by the pressure plate 82. When the paper feed roller 83 is driven, the uppermost sheet is separated in cooperation with the separation roller 84 and fed to the U-turn conveyance path. The recording sheet fed by the sheet feeding roller 83 is aforesaid by the first and second intermediate rollers 86 and 87 provided at two places of the U-turn conveyance path and the pinch rollers 88 and 89 biased by them. It is conveyed toward the conveying roller pair 10, 21.

  A switching flapper 91 is disposed at the junction of the conveyance path from the paper supply unit 200 and the conveyance path of the U-turn conveyance mechanism 800. The recording sheet from the U-turn conveyance mechanism 800 is turned upside down and then fed between the driving roller 10 and the driven roller 21 through the switching flapper 91. The subsequent steps are the same as those of the recording sheet fed from the sheet feeding unit 200. That is, the recording sheet is recorded by the recording unit 500 while being transported by the transport mechanism 300, and is discharged from the paper discharge unit 600.

  Next, a case where double-sided recording is performed on a recording sheet fed from the paper feeding unit 200 or the U-turn paper feeding unit will be described. In the case of duplex recording, after recording on the surface of the recording sheet fed from the paper feeding unit, the recording sheet is introduced into the U-turn conveyance mechanism 800 by rotating the conveyance roller pair 10 and 21 in reverse. The recording sheet reversely conveyed by the conveying roller pair 10 and 21 is sandwiched between the U-turn conveying roller pair 93 and 94 through the switching flapper 91 switched to the upper side in the figure, and the U-turn conveying roller pair is connected to the feeding roller 83. It is conveyed between the separation rollers 84. Thereafter, the recording sheet is conveyed along the U-turn conveyance path as in the case of the recording sheet picked up from the sheet feeding cassette 81. Then, after being reversed by the U-turn conveyance, the recording is performed on the back surface while being conveyed by the pair of conveyance rollers 10 and 21 described above. The recording sheet thus recorded on both sides is discharged from the apparatus main body by the paper discharge unit 600.

  FIG. 1 is a perspective view showing a schematic configuration of a conveyance mechanism using a conveyance roller pair according to the present invention. In FIG. 1, the conveyance mechanism in the present embodiment includes a driving roller 10 and a driven roller unit 20 for conveying a recording sheet during image formation. The driven roller unit 20 includes a plurality of driven rollers 21 that are driven to rotate by being pressed against the driving roller 10 with a predetermined pressure F by a spring biasing force. The driving roller 10 is rotationally driven by a predetermined amount during each main scanning of the recording head, and conveys (paper feeds) the recording sheet by a predetermined pitch in cooperation with the driven roller 20. Since the conveyance accuracy at this time greatly affects the quality of the recorded image, both the driving roller 10 and the driven roller 20 are manufactured with high accuracy.

  The driving roller 10 is finished with high accuracy in a state where the outer diameter is accurate and there is no runout, and the friction coefficient of the roller surface is obtained by sandblasting the roller surface or applying alumina powder to the roller surface. Has been enhanced. As a result, slipping of the recording sheet being conveyed is prevented as much as possible. The driving roller 10 is rotationally driven by a conveyance motor (not shown) connected to one end portion. On the other hand, a plurality of driven rollers (pinch rollers) 21 constituting the driven roller unit 20 are rotatably supported around a roller shaft 22. The roller shaft 22 is fixed to the tip of an arm 23 that is pivotally supported by the arm shaft 24. In the present embodiment, three driven rollers 21 are pivotally supported at the tip of one arm 23, and a plurality of arms 23 are arranged in the length direction of the driving roller 10. Each arm 23 is pivotally supported by a driven roller holder 26 via an arm shaft 24 at an intermediate portion thereof.

  A tension spring 25 is stretched between a rear portion (a portion opposite to the driven roller 21) of each arm 23 and the driven roller holder 26. The driven roller 21 pivotally supported at the tip of each arm 23 is pressed against the driving roller 10 with a predetermined pressing force F by the urging force of each tension spring 25. The driven roller holder 26 is supported by a cam shaft 31 having a cam 30 that abuts against the rear upper surface of each of the plurality of arms 23. The cam shaft 31 is connected to an operation lever (not shown) and can be rotated by the operation lever. Each cam 30 is detachably fastened to the cam shaft 31 with screws. That is, the rear end portion of the arm 23 can be pushed down by the cam 31 by rotating the cam shaft 31 by rotating the operation lever. By the movement of the arm 23, the driven roller 21 pivotally supported at the tip of the arm can be separated from the driving roller 10 and the nip can be released. The recording sheet can be set with the nip released.

  With the configuration described above with reference to FIG. 1, the plurality of arms 23 can swing independently about the arm shaft 24. For this reason, each driven roller 21 can be uniformly and efficiently pressed against the driving roller 10 while preventing each driven roller 21 from being touched. In this embodiment, the pressure contact force 600 gf to 700 gf per driven roller 21 by the tension spring 25 is set.

  FIG. 2 is a longitudinal sectional view showing a configuration of one arbitrary driven roller 21 in FIG. Next, the configuration of the driven roller 21 will be described with reference to FIG. The driven roller 21 is configured by press-fitting roller rubber 21b into a roller collar 21a. The roller collar 21a is a molded product (molded product) made of a material having excellent slidability such as POM. The driven roller 21 may be configured such that roller rubber is pressed into the roller shaft and both ends of the roller shaft are supported by bearings.

  Next, characteristics required for the required conveyance performance of the driven roller 21 in the present embodiment will be described. First, the elasticity and deformation recovery of the driven roller 21 will be described. In order to convey a variety of recording sheets including a highly rigid sheet material and a flexible film, the driven roller 21 is an elastic body that can secure a sufficient nip width even with a small pressure, and recovers deformation. It is necessary to have excellent properties (no compression set). For this purpose, the roller rubber 21b preferably has a JIS-A hardness of 60 to 90 degrees. The roller rubber 21b in this embodiment is a urethane elastomer, and its rubber hardness (JIS-A hardness) is 80 degrees to 90 degrees. When the rubber hardness is high, the nip width can be increased by increasing the rubber thickness. In the roller rubber 21b of this embodiment, the rubber thickness is about 2 mm and the outer diameter is 7 mm.

Second, the wear resistance of the driven roller 21 will be described. In particular, in a production material recording apparatus such as a large-format ink jet printer, the durability of the driven roller 21 becomes more important. The wear resistance of the driven roller 21 used in the present embodiment is 10 μm or less in terms of the amount of wear when a sheet of 50,000 m is passed.
Thirdly, the low plastic material content of the driven roller 21 will be described. The rubber roller rubber 21b contains a compound such as an oil component peculiar to rubber as a plasticizer. When the recording sheet is conveyed by the driving roller 10 and the driven roller 21, the roller rubber 21b is pressed with a predetermined pressure. For this reason, if the roller rubber 21b contains a plastic material such as oil, it may ooze out onto the roller surface and be transferred to the surface of the recording sheet. When the plastic material is transferred to the surface of the recording sheet, the ink permeability when an image is recorded deteriorates. As a result, the dot diameter of the landing ink in the image recording becomes small and image unevenness occurs, causing deterioration in image quality. Therefore, in this embodiment, the rubber material used for the roller rubber is subjected to an extraction test in which the plastic material is extracted into a solvent (toluene or the like), and a rubber material having an extraction amount of 1% or less is used.

  Fourthly, the low adhesiveness of the driven roller 21 will be described. When a recording sheet coated with a base material such as coated paper or glossy paper is used, if the roller rubber surface layer has a high degree of adhesion, the coated layer as shown in FIG. 3 when the recording sheet is left in a nipped state. Peeling of the (coated layer) can occur. So, in this embodiment, the adhesiveness of a surface layer is reduced by containing an acrylic resin with respect to said base material. This acrylic resin has advantages such as low cost and excellent moldability as compared with a fluororesin.

  Fifth, the low friction coefficient and surface smoothness (low surface roughness) of the driven roller 21 will be described. FIG. 4 is a longitudinal sectional view showing a state when the cut sheet Pr is fed as a recording sheet to the nip portion of the pair of conveying rollers 10 and 21 arranged on the upstream side in the conveying direction of the recording head. First, the operation when feeding the cut sheet to the pair of conveying rollers 10 and 21 will be described with reference to FIG. In FIG. 4, many cut sheet feeding mechanisms are configured to feed a cut sheet Pr cut to a certain size to a pair of conveying rollers 10 and 21 by a sheet feeding roller on the upstream side in the conveying direction. In this case, the conveyance roller pair 10 and 21 is stopped or rotated in the reverse direction. In this state, the leading edge of the cut paper Pr hits the nip portion of the pair of transport rollers 10 and 21 by a paper feed roller (not shown) disposed on the upstream side in the transport direction, and further forms a constant loop (dotted line portion). To feed. Then, when a certain loop is formed, the paper feed roller is stopped.

  Next, the driving roller 10 is driven in the forward rotation direction, and the recording sheet Pr is conveyed to the image forming unit in cooperation with the driven roller 21. The reason for starting the conveyance after forming the loop at the leading end of the recording sheet as described above is to absorb the leading end deviation of the recording sheet by this loop and align the leading end (also referred to as resist removal). In this case, when the friction coefficient of the surface layer of the driven roller 21 is high or the surface roughness is high, the leading edge of the recording sheet is caught on the surface of the driven roller 21 and cannot be smoothly guided to the nip portion with the driving roller 10. It may become. Such a state causes the leading edge of the recording sheet Pr and jamming. Therefore, in the present embodiment, the roller surface of the driven roller 21 is formed of a material having a low friction coefficient (for example, the surface friction coefficient is 0.2 or less). The surface of the roller rubber 21b of the driven roller 21 has a surface roughness (Rz) of 20 μm or less.

In view of the necessary characteristics of the driven roller 21 as described above, the surface layer material of the driven roller 21 was verified by various prescriptions. FIG. 5 is a table showing the composition, physical properties, and test results for various formulations of the surface layer material of the driven roller. In FIG. 5, prescription 1 is a case where the material of the roller rubber 21 b that is the surface layer of the driven roller 21 is only a urethane elastomer as a base material and no contained material. Formulation 2 contains 3% of an acrylic resin particle material (acrylic beads) as a fine particle resin material having a particle diameter of about 30 μm in a urethane elastomer as a base material constituting the roller rubber 21b which is a surface layer of the driven roller 21 It is.
Formulation 3 contains 10% of acrylic beads (acrylic resin particle material) having a particle size of about 30 μm in the urethane elastomer as the base material.

Formulation 4 contains 10% of polyethylene powder as a fine particle resin material having a particle diameter of about 10 μm in the urethane elastomer as the base material.
Formulation 5 contains 10% of the acrylic beads (acrylic resin particle material) having a particle size of about 10 μm in the urethane elastomer as the base material.
Formulation 6 contains 15% of the acrylic beads having a particle size of about 10 μm in the urethane elastomer as the base material.
Formulation 7 contains 20% of the acrylic beads having a particle size of about 10 μm in the urethane elastomer as the base material.
Formulation 8 contains 15% of the acrylic beads (acrylic resin particle material) having a particle size of about 15 μm in the urethane elastomer as the base material.

  The result of verifying the conveyance performance of the driven roller 21 having the rubber roller 21b according to each of the above formulations will be described below. That is, in Formula 1 and Formula 2, the friction coefficient was high and the tackiness was high, and when the glossy paper was left in the nipped state, peeling occurred as shown in FIG. Moreover, in the prescription 3 and the prescription 4, in addition to the prescription 1 and the prescription 2, since the surface roughness is rough, the leading edge of the cut paper is caught by the driven roller 21, and the inconveniences such as the leading edge bending and the creaking occurred. In the prescription 5, prescription 6, prescription 7 and prescription 8, all had a level with no problem in the conveyance performance of the driven roller 21. From the above verification results, as the driven roller of the transport mechanism having the resist removal (tip alignment) means as shown in FIG. 4, the surface roughness (Rz) is 10 μm or less and the friction coefficient is 0.2 or less. It is desirable that

  According to the embodiment described above, as the material of the base material of the surface layer (the portion of the roller rubber 21b) of the driven roller 21 of the conveying roller pair, a fine particle material (particulate resin) such as an acrylic resin or a polyethylene resin is applied to the urethane elastomer as the base material. Material) is used. For this reason, without applying coating or the like on the surface layer, elasticity and deformation recovery, abrasion resistance, low plastic content, low adhesion, low friction coefficient and surface smoothness (low surface roughness) as described above ) And the like can be provided at low cost with the required characteristics in all aspects. Further, according to the driven roller according to the present embodiment, since the plastic component (oil component) contained in the roller rubber 21b is very small, the recording sheet is sandwiched and conveyed with the driving roller 10. At this time, the oil component does not ooze out from the roller surface. For this reason, even when an image is formed by attaching ink to the contact surface with the driven roller as in the ink jet recording apparatus, the transfer stain on the surface of the recording sheet can be eliminated, and a high-quality image without unevenness can be recorded. Can do.

  Further, since the surface layer of the driven roller 21 is formed with a surface having a low friction coefficient, the surface layer of the recording sheet is damaged even in the case of a recording sheet having a glossy layer on a paper-based substrate such as glossy paper. Never give. That is, when such a driven roller is left in a pressurized state for a long time, the surface layer is likely to be damaged such as peeling of the coating layer. However, according to the driven roller of this embodiment, such inconvenience is eliminated. be able to. In addition to the low friction coefficient described above, a driven roller that can easily and accurately perform leading edge alignment (registration removal) with a pair of conveying rollers when feeding cut paper by setting the surface roughness small. Is obtained. In the driven roller 21 according to the above-described embodiment, the prescription is determined based on the correlation between the necessary function and the physical properties. Therefore, the driven roller 21 is similarly applicable and movable regardless of the type and size of the recording sheet. The effect of can be produced.

  Therefore, according to the above-described embodiment, the conveyance roller pair capable of improving the conveyance accuracy of the recording sheet with a simple and inexpensive configuration and eliminating the deterioration in the image quality of the recorded image due to the decrease in the conveyance accuracy, and A recording device is provided. Note that the necessary functions and physical properties of the driven roller 21 of the conveying roller pair according to the present invention are not limited to the conditions shown in the above-described embodiments, and are implemented according to various applications within the technical scope of the present invention. can do. Incidentally, in the case of a recording apparatus that does not perform the resist removal described above, all of prescription 3 to prescription 8 can be selected, and there is no problem even if the surface roughness (Rz) is 20 μm or less. Thereby, it becomes possible to widen the tolerance | permissible_range of each physical-property value, and a variation can be increased also as a mixing | blending.

  Further, the above embodiment shows an example of the conveyance mechanism of the recording apparatus, which is appropriately determined depending on the configuration and various conditions of the recording apparatus to which the invention is applied, such as the dimensions, materials, shapes, and relative arrangements of the components described. It should be changed and does not limit the technical scope of the present invention. In the above embodiment, a serial type recording apparatus that records images while alternately repeating main scanning for moving the recording head along the recording sheet and sub-scanning for feeding the recording sheet at a predetermined pitch. Explained with an example. The present invention can be similarly applied to a line type recording apparatus that records an image only by paper feeding (sub-scanning) of a recording sheet while recording one line at a time. In the above embodiment, the case where the recording apparatus is an ink jet recording apparatus has been exemplified. However, the present invention is also applicable to recording apparatuses having different recording methods, such as a thermal transfer type, a thermal type, a laser beam type, and a wired it type. The same applies.

It is a perspective view which shows schematic structure of the conveyance mechanism using the conveyance roller pair by this invention. It is a longitudinal cross-sectional view which shows the structure of the arbitrary one driven roller in FIG. FIG. 2 is an explanatory diagram illustrating the coating layer peeling of the recording sheet by the driven roller when the recording sheet is nipped between the driving roller and the driven roller of FIG. FIG. 5 is a longitudinal sectional view showing a state when a cut sheet is fed as a recording sheet to a nip portion of a pair of conveying rollers disposed on the upstream side in the conveying direction of the recording head. It is a table | surface which shows the mixing | blending and the physical property in various prescriptions of the surface layer material of a driven roller, and a test result. 1 is a longitudinal sectional view of a recording apparatus suitable for applying the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Drive roller 20 Driven roller unit 21 Driven roller 21a Roller collar 21b Roller rubber 51 Carriage 52 Recording head 200 Paper feed part 300 Conveying mechanism 500 Recording part

Claims (7)

In a conveying roller pair consisting of a driving roller and a driven roller that conveys a recording sheet through the recording unit of the recording apparatus,
A pair of conveying rollers, characterized in that as a material of the surface layer of the driven roller, a urethane elastomer as a base material containing 10% to 20% of a fine particle resin material is used.   2. The pair of conveying rollers according to claim 1, wherein an acrylic resin particle material having a particle diameter of 10 to 20 [mu] m is used as the fine particle resin material.   The pair of conveying rollers according to claim 1, wherein a polyethylene resin particle material having a particle diameter of 10 to 20 µm is used as the fine particle resin material.   The conveyance according to any one of claims 1 to 3, wherein a surface friction coefficient of a surface layer of the driven roller is 0.2 or less, and a surface roughness (Rz) of the surface layer is 20 µm or less. Laura vs.   5. The pair of conveying rollers according to claim 1, wherein a rubber hardness (JIS-A hardness) of a surface layer of the driven roller is 70 degrees to 90 degrees. In a recording apparatus for recording an image on a recording sheet by a recording head based on image information,
A recording apparatus comprising the pair of conveyance rollers according to claim 1.   The recording apparatus according to claim 6, wherein the recording head is an ink jet recording head that records an image by discharging ink.

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