JP4616084B2 - Image recording device - Google Patents

Description

  The present invention relates to an image recording apparatus that reliably detects in advance advance of a recording medium that is actually harmful to conveyance from a recording medium conveyance mechanism and prevents excessive detection.

  2. Description of the Related Art Conventionally, an ink jet printer as an image recording apparatus ejects ink droplets by an ink jet method from a plurality of nozzles of a recording head, and records a high-quality image on a recording medium conveyed by a conveying mechanism at high speed.

  In the case of an ink jet printer including a platen belt as a transport mechanism, a platen belt is usually provided with a suction unit, and a recording medium is held on the platen belt by the suction unit and transported.

  In general, the usage environment of an inkjet printer is not limited to an office, and is exposed to various usage environments. When the recording medium is left in a high temperature and high humidity environment for a long time without packaging, the recording medium absorbs moisture, and the end of the cut sheet-shaped recording medium is warped in a half-curl shape.

  When the recording medium having the curled edge is passed through the ink jet printer, the curled portion at the leading edge of the recording medium is rubbed against the nozzle surface of the recording head, and the edge of the recording medium or the printing surface The problem of fouling occurs.

  Further, when the leading end portion of the curled recording medium comes into contact with the side surface of the recording head or the like, the recording medium is often jammed and the paper passing is often unstable. In addition, when a stiff recording medium such as cardboard is brought into contact with the recording head in a curled state, there is a problem that the recording head may be damaged.

In order to solve these problems, in order to suppress the floating of the recording medium, a configuration of an ink jet printer in which a recording medium pressing mechanism composed of a pressing arm member with a spur is disposed in the vicinity of the recording head has been proposed. According to this proposal, the lifting of the recording medium immediately before the recording operation by the recording head can be suppressed, and control for prohibiting the recording operation by detecting the lifting above a predetermined level is performed. (For example, refer to Patent Document 1.)
JP 2001-26154 A (paragraphs [0080] to [0085], FIG. 9)

  By the way, in the configuration of the conventional ink jet printer shown in Patent Document 1 described above, the recording medium lift immediately before the recording operation by the recording head is pressed by the pressing arm, and the lift above the predetermined level is detected to perform the recording operation. Control is prohibited.

  However, the recording medium is pressed against the conveying belt by the conductive roller on the most upstream side in the conveying direction, and the floating of the recording medium is temporarily suppressed here. This pressing is released as the recording medium is conveyed downstream from the conductive roller. Therefore, the floating state of the recording medium may be different between the pressing arm portion that detects the floating of the recording medium and the position immediately below the recording head on the downstream side.

  For this reason, the floating state of the recording medium that may cause damage to the recording head due to the tip of the curled recording medium coming into contact with the recording head cannot be detected correctly by the pressing arm, or the detection may be insufficient. In order to prevent this, a malfunction of the detection mechanism that is excessively detected occurs.

  The present invention relates to recording on a recording medium that is actually harmful to the conveyance, in which the recording medium slides on the printing surface of the recording head and the printing surface of the recording medium becomes dirty or the recording medium collides with the recording head and causes damage to the recording head. An object of the present invention is to provide an image recording apparatus that reliably detects in advance a lift from a medium transport mechanism and prevents excessive detection.

An image recording apparatus of the present invention is arranged on the upstream side in the first direction from the line head, the recording medium conveyed in the first direction by the conveying means, the image recording unit having a line head for recording an image on the recording medium. A first guide member to be detected, a detection unit that is disposed on the downstream side in the first direction from the first guide member, detects a lift of the recording medium that has passed through the first guide member, and a first one from the detection unit. A second guide member disposed on the downstream side in the direction and on the upstream side in the first direction of the line head, and the distance in the first direction between the first guide member and the detection unit is d1, and the detection unit And the distance between the second guide member and the line head in the first direction is d2, and the distance between the line head and the recording medium conveyance surface of the conveyance means is h2. H1 / d1 and h2 / Wherein the 2 and has a substantially equal relationship. The image recording apparatus of the present invention also includes a recording medium conveyed in the first direction by the conveying means, an image recording unit having a line head for recording an image on the recording medium, and an upstream side in the first direction from the line head. A first guide member disposed on the downstream side of the first guide member, a detection unit disposed on the downstream side in the first direction from the first guide member, and detecting the lifting of the recording medium that has passed through the first guide member; A second guide member disposed on the downstream side in the first direction and on the upstream side in the first direction of the line head, and the distance between the first guide member and the detection means in the first direction is d1. The distance between the detection means and the recording medium conveyance surface of the conveyance means is h1, the distance between the second guide member and the line head in the first direction is d2, and the distance between the line head and the recording medium conveyance surface of the conveyance means is When h2, (h2 / 2) characterized by having a relationship of × 0.7 ≦ h1 / d1 ≦ ( h2 / d2) × 1.1.

  According to the present invention, a recording medium having a serious damage in conveyance such that the recording medium slides on the printing surface of the recording head and the printing surface of the recording medium becomes dirty or the recording medium collides with the recording head and causes damage to the recording head. It is possible to provide an image recording apparatus that reliably detects in advance the lifting from the recording medium transport mechanism and prevents excessive detection.

  Embodiments of the present invention will be described below with reference to the drawings. In the following description, the first direction is, for example, the Y-axis direction along the conveyance direction of the paper 10, the conveyance means is composed of, for example, the platen unit 3, and the recording medium is, for example, the paper 10 The first guide member comprises, for example, a first paper guide 19 and the like, the detection means comprises, for example, a paper floating detection plate 21, a sensor 22 and the like, and the second guide member comprises For example, four second paper guides 18 and the like.

  FIG. 1 is a side view schematically showing a configuration of a main part of the image recording apparatus in the present embodiment. As shown in FIG. 1, the image recording apparatus 1 includes a paper feeding unit 2, a platen unit 3, an image recording unit 4, a recording medium floating detection unit 5 and a recording medium discharge unit 6 that constitute essential parts of the present invention. I have.

  The paper feed unit 2 includes a paper tray 7, a pickup roller 8, and a registration roller pair 9. The paper tray 7 can store at least one cut sheet-like paper 10 as a recording medium. In this example, a plurality of sheets 10 are stored in the sheet tray 7.

In FIG. 1, the direction along the conveyance direction of the paper 10 is shown as the Y axis, the direction perpendicular to the Y axis on the surface on which the image of the paper 10 is recorded during image recording is shown as the X axis, and the X axis And Y
The direction orthogonal to the axis is shown as the Z axis.

  The pickup roller 8 of the paper feeding unit 2 is a paper take-out mechanism that takes out the paper 10 from the paper tray 7 one by one. The pickup roller 8 is rotatably supported by a frame of a main unit (not shown) (image recording apparatus 1, the same applies hereinafter).

  The registration roller pair 9 of the paper feeding unit 2 is rotatably supported by the frame of the main body apparatus. The registration roller pair 9 is a conveyance direction adjustment unit that corrects skew of the sheet 10 taken out by the pickup roller 8, that is, aligns the position with the conveyance direction (Y-axis direction).

  The registration roller pair 9 is also a paper feeding unit that feeds the aligned paper 10 to the platen unit 3 in accordance with the timing of image formation on the paper 10 in the image recording unit 4.

  The platen unit 3 is a transport device that transports the paper 10 fed from the paper feed unit 2 during image recording. As shown in FIG. 1, the platen unit 3 includes a platen belt 11, a plurality of platen belt rollers 12, a driven roller 13, a platen frame 14, and a platen suction unit 15.

  The platen belt 11 of the platen unit 3 is an endless belt, and constitutes a belt conveyor that cooperates with a plurality of platen belt rollers 12 to convey the paper 10 along the Y axis. The sheet 10 is conveyed by the platen belt 11 between the platen sheet conveyance areas a and b.

  The platen belt 11 and the platen belt roller 12 are assembled with their conveying directions set so as to convey the paper 10 along the Y axis to the Y axis (+) side during image recording. Yes. Here, the Y axis (+) side is the downstream side in the paper transport direction, and the Y axis (−) side is the upstream side in the paper transport direction.

  The driven roller 13 of the platen unit 3 is disposed at a position facing the platen belt roller 12 in the Z-axis direction across the platen belt 11 at the upstream end of the platen belt 11 in the sheet conveyance direction, and prevents the sheet 10 from lifting up. ing. The platen frame 14 and the platen suction part 15 will be described later.

  The image recording unit 4 is disposed close to the upper part of the platen belt 11. The image recording unit 4 is an ink ejection device for ejecting ink onto the paper 10. The image recording unit 4 includes a plurality of recording heads 16 (16k, 16c, 16m, 16y) and a carriage 17 that supports these recording heads 16.

  The recording head 16 is composed of an aggregate of image recording heads for recording images. The recording head 16 is provided for each color. For example, in this example, the recording heads 16k, 16c, 16m, and 16y eject black, cyan, magenta, and yellow inks, respectively. These four recording heads 16 are arranged at equal intervals in the conveyance direction of the paper 10.

  Further, the recording head 16 constitutes a line head fixed to the main body apparatus, and is formed to have the same or larger dimension as the maximum width of the paper 10 used in the image recording apparatus 1. That is, when the image recording apparatus 1 is set to be capable of recording on a maximum of A3 size paper, the width of the recording head 16 is set to be equal to or larger than the width of the A3 size paper.

  Second paper guides 18 are disposed on the upstream side of the four recording heads 16 in the paper transport direction. The second paper guide 18 is a cylindrical roller, and the center of both ends of the roller shaft is rotatably supported by a frame (not shown) of the main body device. The dimension of the second paper guide 18 in the recording medium width direction is the same as or larger than the maximum width of the recording medium to be used.

  The total four second paper guides 18 arranged immediately before each of the four recording heads 16 suppress the floating of the paper 10, and each of the four second paper guides 18 is downstream in the paper transport direction. The recording head 16 is conveyed directly below the recording head 16 on the side.

The recording medium floating detection unit 5 includes a first paper guide 19, a paper floating detection plate 21, and a sensor 22.
Only one first paper guide 19 is disposed upstream of the four recording heads 16 in the paper conveyance direction. The first paper guide 19 is also a cylindrical roller, and the center of both ends of the roller shaft is rotatably supported by a frame (not shown) of the main unit. The dimension of the first paper guide 19 in the recording medium width direction is the same as or larger than the maximum width of the recording medium used.

  The sheet floating detection plate 21 of the recording medium floating detection unit 5 has a shape in which a vertical straight line portion is shifted up and down until a hatched portion having an inverted N cross section becomes horizontal. Then, a substantially central portion of the linear portion above is pivotally supported by the rotation shaft 23, and the vicinity of the upper end portion faces the sensor 22. The sensor 22 is a transmissive optical sensor.

  Further, the lower end portion of the linear portion below the sheet floating detection plate 21 is disposed close to the sheet conveying surface of the platen belt 11 of the platen unit 3 at a predetermined interval (Z direction). The configuration and functions in the vicinity of the recording medium floating detection unit 5 will be described in detail later.

  The recording medium discharge unit 6 is disposed downstream of the platen unit 3 and the image recording unit 4 in the sheet conveyance direction. The recording medium discharge unit 6 is a mechanism for discharging the paper 10 on which the image is recorded by the image recording unit 4 to the outside of the main body apparatus. As shown in FIG. 1, the recording medium discharge unit 6 includes a discharge unit conveying roller pair 24, a discharge unit discharge roller pair 25, and a discharge tray 26.

  The discharge unit conveyance roller pair 24 takes over the conveyance of the sheet 10 conveyed from the platen unit 3 and conveys the sheet 10 toward the discharge unit discharge roller pair 25. The discharge unit discharge roller pair 25 discharges the sheet 10 conveyed from the discharge unit conveyance roller pair 24 to the discharge tray 26.

  FIG. 2 is a top view schematically showing the platen portion 3. In FIG. 2, the platen belt 11 is shown by cutting away a substantially right half of the drawing in the Y-axis direction for convenience of explaining the configuration of the platen portion 3.

  As shown in FIG. 2, the plurality of platen belt rollers 12 are arranged so that the platen belt 11 is parallel to the X axis and the Y axis between the platen paper conveyance areas a and b where the platen belt 11 and the image recording unit 4 face each other. Further, the platen belt 11 is supported.

  A belt roller drive motor 27 that rotates the platen belt roller 12 is connected to at least one of the platen belt rollers 12. In the example shown in the figure, a belt roller drive motor 27 is connected to the rotating shaft 12-1 of the platen belt roller 12 at the downstream end of the platen belt 11 in the sheet conveying direction.

  The platen belt 11 is provided with a plurality of suction holes 28 formed throughout. A platen frame 14 shown in FIG. 1 for supporting the platen belt 11 in a planar manner is provided below the platen belt 11.

  The platen frame 14 rotatably supports the platen belt roller 12 and holds a platen suction portion 15 (see FIG. 1). The platen frame 14 has surfaces along the X-axis and Y-axis directions, and a plurality of grooves 29 extending in the Y-axis direction are formed over the entire region facing the platen belt 11.

  A suction hole 31 is provided in a substantially central portion of each groove 29. A platen suction portion 15 shown in FIG. 1 is fixedly disposed on the platen frame 14. The platen suction part 15 is provided with a platen chamber (not shown). The suction hole 31 communicates with the platen chamber.

  The platen chamber has a negative pressure generating source for making a negative pressure in its own chamber. This negative pressure generating source is a known negative pressure generating device such as a fan. The platen chamber sucks air from the suction holes 31 by the negative pressure of the negative pressure generation source, and sucks the paper 10 being conveyed through the suction holes 28 of the platen belt 11. That is, the platen suction unit 15 shown in FIG. 1 is a negative pressure generating device that generates a negative pressure for attracting the paper 10 to the platen belt 11.

  Next, an image recording operation of the image recording apparatus 1 having the above configuration will be briefly described. First, when the power is turned on, the material, number of sheets, print mode, and other designations of the paper 10 to be used are input from the operation panel (not shown) as a key input or as a signal from a host device (not shown) connected. The controller starts printing (recording of characters and images, and so on).

The pickup roller 8 takes out one uppermost sheet 10 stored in the sheet tray 7 every rotation and feeds the taken sheet 10 to the registration roller pair 9.
The registration roller pair 9 temporarily stops the rotation and temporarily stops the progress of the paper 10, corrects the skew of the paper 10 with respect to the main scanning direction (X direction), waits for the conveyance timing, and the image recording timing comes. Then, the conveyance of the sheet 10 toward the platen unit 3 is started.

  When the sheet 10 sent to the platen unit 3 reaches the upstream side of the platen unit 3 in the sheet conveyance direction, the sheet 10 passes while the sheet floating is suppressed by the driven roller 13 and the first sheet guide 19.

  The first paper guide determines whether or not the sheet 10 exceeds a predetermined height so that the sheet 10 after the sheet floating is not pressed contacts the plurality of recording heads 16 of the image recording unit 4. 19 is detected by a sheet floating detection plate 21 located downstream in the sheet conveying direction.

  The paper 10 detected not exceeding the predetermined height passes through the paper floating detection plate 21 and reaches the second paper guide 18 immediately before the first recording head 16k. Thereafter, while the sheet lift is sequentially suppressed by the four second paper guides 18, the recording heads 16 (16 k, 16 c, 16 m, 16 y) on the downstream side in the sheet transport direction pass through each, and predetermined characters and images are recorded. And conveyed to the recording medium discharge unit 6.

Subsequently, an arrangement distance and an arrangement height between the paper guide and other members, which are features of the present embodiment, will be described.
FIG. 3 is an enlarged view of the vicinity of the sheet floating detection plate 21 and the most upstream recording head 16k on the upstream side of the platen unit 3 in the sheet conveyance direction.

  The first paper guide 19 that presses the paper lift is in contact with the surface of the platen belt 11 that is the recording medium conveyance surface of the platen unit 3 by its own weight. The paper 10 conveyed on the platen belt 11 of the platen unit 3 passes through the first paper guide 19 while being pressed by the weight of the first paper guide 19.

  Thereafter, the conveyed paper 10 passes through the paper floating detection plate 21, but is adsorbed by the platen unit 3, and even if the paper floating is suppressed by the first paper guide 19, the paper floating of a predetermined level or more is maintained. In the case of a certain sheet 10, the leading edge of the sheet 10 abuts on the sheet floating detection plate 21, so that the recording medium floating detection unit 5 detects that there is a sheet floating above a predetermined level.

  At this time, the sheet floating of a predetermined value or more means that in this embodiment, the distance h1 between the sheet floating detection plate 21 and the platen belt 11 is 1.4 mm, and the distance h2 between the recording head 16 and the platen belt 11 is 1.4 mm. Is a sheet floating exceeding h1 or h2.

  The sheet floating detection plate 21 is connected to a fixed plate (not shown) and is formed of a sheet metal that is at least larger than the maximum sheet width that can be conveyed and extends in the sheet width direction. The connection between the sheet floating detection plate 21 and the fixed plate is rotatably supported by a rotation shaft 23 having a rotatable member such as a bearing.

  As a result, when the sheet 10 with the lift comes into contact with the lower end portion of the sheet lift detection plate 21, even when the contact occurs with a small force, the paper lift detection plate 21 uses the rotation shaft 23 as a fulcrum. It has a rotatable structure.

  Further, the sheet floating detection plate 21 rotated by the contact of the sheet 10 is detected by a sensor 22 supported by a fixed plate (not shown) at the end above the rotation shaft 23. Rotation is detected. Normally, the sensor 22 is set so that its output is turned OFF when the detection optical axis is shielded by the upper end portion of the sheet floating detection plate 21.

  When a sheet 10 having a float above a predetermined level comes into contact with the sheet floating detection plate 21, the lower end of the sheet floating detection plate 21 has a rotation shaft 23 as a fulcrum as shown by a two-dot chain line in FIG. Turn in the paper transport direction. As a result, the upper end portion of the sheet floating detection plate 21 rotates in the reverse direction of the sheet conveyance with the rotation shaft 23 as a fulcrum to release the shielding of the sensor 22.

  As a result, the output of the sensor 22 is turned on, and the rotation of the sheet floating detection plate 21, that is, the lifting of the sheet 10 above a predetermined level is detected by the recording medium floating detection unit 5. By this detection, the entire recording operation can be stopped before the sheet 10 on which the actual sheet lifting has occurred reaches the recording head 16.

  In the configuration shown in the upper part of FIG. 3, a case where the sheet 10 passes the sheet floating detection plate 21 will be described. When the paper 10 passes the paper floating detection plate 21, the paper 10 passes through the second paper guide 18 that presses the paper floating before reaching the recording head 16 (16k).

  The second paper guide 18 is in contact with the platen belt 11 of the platen unit 3 by its own weight, and the conveyed paper 10 passes while the paper floating is suppressed by the own weight of the second paper guide 18.

  As described above, since the sheet floating more than a predetermined value is detected in advance by the recording medium floating detection unit 5, even if there is a sheet floating, only the sheet 10 having a sheet floating less than the predetermined value has the sheet floating detection plate 21. Pass through and further pass through the second paper guide 18. Then, the sheet 10 is image-recorded without contacting the recording head 16 and is discharged to the recording medium discharge unit 6.

  At this time, the distance d1 between the first paper guide 19 and the paper floating detection plate 21 for detecting the paper floating is set to 20 mm, and the distance d2 between the second paper guide 18 and the recording head 16 is set to 20 mm. Therefore, in this embodiment, h1 / d1 = h2 / d2, h1 = h2, and d1 = d2.

  In the case where the above-described paper lift is less than a predetermined value and the paper lift is not detected, and the case where the paper lift is equal to or higher than the predetermined value and the paper lift is detected, the center of FIG. This will be further described with reference to the drawings shown in FIG.

  The center of FIG. 3 shows a state where the paper 10 does not contact the paper floating detection plate 21. The paper 10 conveyed on the platen belt 11 passes through the first paper guide 19 while being pressed by the first paper guide 19 in contact with the platen belt 11 by its own weight.

  Since the leading edge of the sheet 10 conveyed in the sheet conveying direction from the first sheet guide 19 is lifted only to a certain height, when the sheet floats lower than the interval set by the sheet floating detection plate 21 Then, it passes under the paper floating detection plate 21 like the paper 10a without any problem.

  Further, the relationship between the conveyance direction distance and the height interval among the paper floating detection plate 21, the recording head 16, and the platen belt 11 is h1 / d1 = h2 / d2, h1 = h2, and d1 = d2. The sheet 10 a for which the floating of a predetermined level or more is not detected by the sheet floating detection plate 21 does not come into contact with the recording head 16 as shown by the sheet 10 b or 10 c even immediately below the recording head 16.

  The lower part of FIG. 3 shows a state in which the paper 10 comes into contact with the paper floating detection plate 21. When the sheet 10 having a large sheet floating is sent out through the first sheet guide 19 abutting against the platen belt 11 by its own weight, the sheet 10 has a predetermined height from the platen belt 11 set by the sheet floating detection plate 21. If the sheet 10 has a sheet floating height larger than the interval, the lifted sheet tip comes into contact with the sheet floating detection plate 21.

  By this contact, the lower end portion of the paper floating detection plate 21 is pushed up by the paper 10a, and the paper floating detection plate 21 rotates greatly with the rotation shaft 23 as a fulcrum, and a sensor 22 (upper part of FIG. Shielding is canceled. As a result, a sheet lift of a predetermined value or more is detected.

  If the sheet 10a in which the floating of the sheet more than a predetermined value is detected is continuously conveyed and reaches the second sheet guide 18, the sheet 10a is in contact with the platen belt 11 by its own weight. 2 passes through the two paper guides 18 and is sent to the recording head 16 as the paper 10b.

  The sheet 10b that has been fed from the second sheet guide 18 and has a sheet floating state of a predetermined level or more is from the height interval h2 (see the upper diagram in FIG. 3) with the platen belt 11 set by the recording head 16. However, the sheet 10b contacts the recording head 16, and the recording head 16 is damaged by slidably contacting the ink discharge surface of the recording head 16 so that, for example, the leading end of the sheet 10b is rolled up like the sheet 10c. .

  As described above, as in the configuration shown in FIG. 3, the distances in the transport direction between the first paper guide 19 and the paper floating detection plate 21 and between the second paper guide 18 and the recording head 16 are defined as d1 and d2. The height intervals of the paper floating detection plate 21 and the platen belt 11 and the recording head 16 and the platen belt 11 are h1 and h2, and the relationship between them is h1 / d1 = h2 / d2 and h1 = By setting h2 and d1 = d2, it is possible to reliably detect the sheet when the sheet floats more than a predetermined level while reproducing the sheet 10 floating immediately below the recording head 16 in advance. The settings can be determined.

  Even if the sheet 10 has a lift, if the lift is a lift height that does not cause actual damage that damages the recording head 16, recording can be performed without contacting the recording head 16. Can be executed.

  It should be noted that the settings for reliably detecting the sheet when the sheet floats more than a predetermined value are the sheet transport direction distance d1 = 20 mm between the first sheet guide 19 and the sheet lift detection plate 21, and the sheet lift detection plate 21. Height interval hl = 1.4 mm with the platen belt 11, paper conveyance direction distance d2 = 20 mm between the second paper guide 18 and the recording head 16, and height interval h2 = 1 between the recording head 16 and the platen belt 11. .4mm, but in reality, there is a tolerance as a variation at the time of assembly.

  That is, in this example, the height interval h1 between the sheet floating detection plate 21 and the platen belt 11 is 1.4 ± 0.1 mm, and the sheet conveyance direction distance d1 = 20 between the first paper guide 19 and the sheet floating detection plate 21. ± 0.1 mm, the height interval h2 between the recording head 16 and the platen belt 11 = 1.4 ± 0.1 mm, and the paper conveyance direction distance d2 between the second paper guide 18 and the recording head 16 = 20 ± 0. 1 mm.

  In this case, for example, when hl and h2 each have a tolerance of ± 0.1 mm, the relationship of h1 / d1 = h2 / d2 varies depending on the tolerance, but from the viewpoint of protection of the recording head 16, the tolerance range. Thus, it is preferable that h1 / d1 is substantially equal to or slightly smaller than h2 / d2. If h1 / d1 is too small with respect to h2 / d2, the sheet floating is overdetected. For this reason, as a range of the h1 / d1 value, for example, (h2 / d2) × 0.7 ≦ h1 / d1 ≦ (h2 / d2) × 1.1 is preferable.

  In this example, d1 = d2, but a range of about d2 × 0.8 ≦ d1 ≦ d2 × 1.2 is preferable. In any case, the distance and height relationship between the first paper guide 19, the paper floating detection plate 21, and the platen belt 11, and the distance and height between the second paper guide 18, the recording head 16, and the platen belt 11. By making the relationship the same, as described above, the paper 10 passes through the first paper guide 19 and passes through the second paper guide 18 as well as the environmental conditions that cause the paper to rise up to the paper floating detection plate 21. Thus, the environmental conditions that cause the sheet to rise up to the recording head 16 are set to be the same.

  Thus, before the paper 10 reaches the recording head 16, the same paper floating state as when the paper 10 reaches the recording head 16 is observed between the first paper guide 19 and the paper floating detection plate 21. Can be reproduced. Thereby, before the paper 10 reaches the recording head 16, it is possible to reliably detect the paper floating that may cause actual damage.

  As a result, it is possible to eliminate the occurrence of problems such as dirt on the printing surface and damage to the recording head. Further, it is not necessary to perform excessive detection such as detecting even a sheet floating sheet that is not harmful.

  FIG. 4 is a diagram illustrating a modification of the first embodiment. In FIG. 4, the same components as those shown in FIG. 3 are denoted by the same reference numerals as those in FIG. As shown in FIG. 4, in this example, instead of the second paper guide 18 extending in the paper width direction, a paper guide in which a plurality of spur-shaped or ratchet gear-shaped gears are arranged in the paper width direction. 32 is arranged. By arranging the paper guide 32 having such a shape, the same operation and effect as described above can be obtained.

  Also, in this case, unlike the second paper guide 18 extending in the paper width direction, the shape is in contact with the paper 10 over the entire width direction of the paper, and is constant with respect to the width direction of the paper 10. Since the arrangement is such that the paper guides 32 are arranged in contact with each other at points, even if the paper guides 32 are once stained due to some inconvenience, there is a risk that the dirt will move to the next sheet to be printed. It is greatly reduced.

  FIG. 5 is an enlarged view of the vicinity of the sheet floating detection plate and the most upstream recording head on the upstream side in the sheet conveying direction of the platen unit in the second embodiment. Note that the image recording apparatus as the main body apparatus in this example has the same configuration as that of the image recording apparatus 1 in the first embodiment shown in FIGS. In FIG. 5, the same components as those shown in FIG. 3 are given the same reference numerals as those in FIG.

  As shown in FIG. 5, the features that are characteristic of the present embodiment are the first paper guide 19 that makes contact with the platen belt 11 of the platen section 3 by its own weight, and the paper 10 that has passed through the first paper guide 19. The sheet floating detection plate 21a is configured to detect lifting.

  In this example, as in the configuration shown in FIG. 5, the height interval h <b> 3 between the sheet floating detection plate 21 a and the platen belt 11 and the conveyance direction distance d <b> 3 between the first paper guide 19 and the sheet floating detection plate 21. Are increased in the same proportion with respect to the height interval h1 between the sheet floating detection plate 21 and the platen belt 11 and the conveyance direction distance d1 between the first paper guide 19 and the sheet floating detection plate 21 according to the first embodiment. .

  That is, the dimension proportional to the height interval h3 between the paper floating detection plate 21a and the platen belt 11 and the distance d3 between the first paper guide 19 and the paper floating detection plate 21a as described above is h2 / d2 (= h1 / d1) = h3 / d3 and d2 (= d1) <d3.

  Even in this case, the detection of the paper lift can provide the same operation and effect as in the first embodiment, and can detect harmful and harmless especially for the paper having a fixed lift.

  That is, in general, there is a change in the float of the paper depending on the type of the paper and the storage environment. For example, not only the rising curl at the leading edge of the paper, but also the position where the rear position is the largest from the floating of the leading edge of the paper, or the center of the paper is swelled away from the platen belt 11.

  In this example, even for a sheet having such a constant lifting wrinkle, the dimension of the sheet conveyance direction distance and the height interval between the members of the recording medium floating detection unit 5 is set to h2 / d2 = h3 / d3, In addition, by setting d2 <d3, it becomes possible to correctly detect harmful and harmless.

  When the paper lift is less than the specified value due to the increase in the transport amount due to the above-mentioned paper lift 癖 (the lift at the leading edge of the paper as the transport distance increases, the same applies below) and the paper lift is not detected. The case where the sheet lift is determined to be greater than or equal to the predetermined amount and the sheet lift is detected will be further described with reference to the diagram shown in the center of FIG. 5 and the diagram shown below FIG.

  The center of FIG. 5 shows a state where the paper 10 does not contact the paper floating detection plate 21a. The paper 10 conveyed on the platen belt 11 passes through the first paper guide 19 while being pressed by the first paper guide 19 in contact with the platen belt 11 by its own weight.

  In the case of the paper 10a in which the lift of the leading edge of the paper 10 fed from the first paper guide 19 in the paper conveyance direction is not proportional to the conveyance amount, the leading edge only rises to a certain height even if the conveyance amount increases. The lift is lower than the height interval h3 set in the paper floating detection plate 21a, and therefore passes under the paper floating detection plate 21a without any problem.

Thus, even immediately below the recording head 16, as shown by the sheets 10b and 10c, the recording head 16 is not contacted.
The lower part of FIG. 5 shows a state where the paper 10 comes into contact with the paper floating detection plate 21a. In the case of the paper 10 in which the lifted wrinkles at the leading end increase in proportion to the transport amount, the transport amount increases and the paper floats after being fed through the first paper guide 19 that is in contact with the platen belt 11 by its own weight. The amount becomes higher.

For this reason, the sheet 10a having a larger float than the height interval h3 set by the sheet floating detection plate 21a is conveyed, and the leading end thereof abuts on the sheet floating detection plate 21a.
By this contact, the lower end portion of the paper floating detection plate 21a is pushed up by the paper 10a, and the paper floating detection plate 21a rotates greatly with the rotation shaft 23 as a fulcrum, and the sensor 22 (not shown in FIG. 5) by the upper end portion. , See FIG. 3 above). As a result, a sheet lift of a predetermined value or more is detected.

  If the sheet 10a in which the floating of the sheet more than a predetermined value is detected is continuously conveyed and reaches the second sheet guide 18, the sheet 10a is in contact with the platen belt 11 by its own weight. 2 passes through the two paper guides 18 and is sent to the recording head 16 as the paper 10b.

  The paper 10b sent out from the second paper guide 18 is lifted in proportion to the transport amount in the same manner as after passing through the first paper guide 19. For this reason, the paper 10b comes into contact with the recording head 16, and the recording head 16 is damaged by slidingly contacting the ink ejection surface of the recording head 16 while being wound around the leading end portion like the paper 10c.

  Thus, as in the configuration shown in FIG. 5, the distances in the transport direction between the first paper guide 19 and the paper floating detection plate 21a, and the second paper guide 18 and the recording head 16 are d3 and d2. The height intervals of the sheet floating detection plate 21a and the platen belt 11 and the recording head 16 and the platen belt 11 are h3 and h2, and the relationship between them is h2 / d2 = h3 / d3 and d2 < By setting d3 in advance, it is possible to reliably detect the sheet when the sheet floating with the increase in the transport amount is a predetermined level or more while reproducing the sheet 10 floating immediately below the recording head 16 in advance. The settings for doing so can be determined.

  Contrary to the above, the recording is arranged such that h2 / d2 = h3 / d3 and d2> d3 are set so that the height interval and the conveyance direction distance are smaller and proportional to those of the first embodiment. In the case of the medium floating detection unit 5, the same operation and effect can be obtained. Further, in this case, since the arrangement distance between the first paper guide 19 and the paper floating detection plate is close, there is an effect of space saving, and it is possible to contribute to the downsizing of the entire apparatus.

  FIG. 6 is an enlarged view of the vicinity of the sheet floating detection plate and the most upstream recording head on the upstream side in the sheet conveying direction of the platen unit in the third embodiment. Note that the image recording apparatus as the main body apparatus in this example has the same configuration as that of the image recording apparatus 1 in the first embodiment shown in FIGS. In FIG. 6, the same components as those shown in FIG. 5 are given the same reference numerals as those in FIG.

  As shown in FIG. 6, the features that are characteristic in the present embodiment are the first paper guide 19a located on the upstream side of the platen belt 11 of the platen portion 3, and the lifting of the paper that has passed through the first paper guide 19a. The sheet floating detection plate 21 for detecting the above, the recording head 16, and the second paper guide 18a immediately before the recording head.

  The first paper guide 19a and the second paper guide 18a are supported by members (not shown), respectively, and have a predetermined same height or an equivalent height h4 from the belt platen 11 of the platen unit 3, respectively. The position is fixed.

  The paper 10 is conveyed through the gap between the first paper guide 19a and the platen belt 11 while being attracted to the platen belt 11 and pressed against the paper lift by the first paper guide 19a.

The sheet 10 conveyed while the sheet lift is suppressed is detected in contact with the sheet lift detection plate 21 only when it is higher than a predetermined height, and the recording operation is stopped.
Also in this example, since the arrangement setting conditions of the second paper guide 18a immediately before the recording head 16 and the first paper guide 19a on the upstream side of the platen belt 11 are the same conditions, as described above. An environmental condition in which the paper 10 is lifted up to the paper floating detection plate 21 after passing through the first paper guide 19a and a paper lift up to the recording head 16 through the second paper guide 18a. The resulting environmental conditions are the same. That is, in the case of this example, h4 is set to be the same or equivalent in addition to h1 / d1 = h2 / d2, h1 = h2, and d1 = d2.

  Thus, before the paper 10 reaches the recording head 16, the same paper floating state as that when the paper 10 reaches the recording head 16 is observed between the first paper guide 19 a and the paper floating detection plate 21. Can be reproduced. As a result, before the paper 10 reaches the recording head 16, it is possible to reliably detect the paper that may be harmful.

  In this example, the second paper guide 18a immediately before the recording head 16 and the first paper guide 19a upstream of the platen part are both located at a predetermined height away from the platen belt 11. In the case of a sheet that has been attracted to the platen portion without being lifted, the sheet does not come into contact with the first sheet guide 19a when passing through the first sheet guide 19a. Therefore, such paper can be transported without causing any damaging damage.

  Further, since there is no useless damage to the paper, there is no occurrence of turning or peeling at the front end of the paper. As a result, contact with the recording head 16 is removed, and contamination of the paper and damage to the recording head can be prevented.

  In each of the embodiments described above, the configuration of the recording medium floating detection unit uses a rotating sheet floating detection plate and a sensor that detects this rotation. A transmissive optical sensor can also be used. This will be described below as a fourth embodiment.

  FIG. 7 is an enlarged view of the vicinity of the recording medium floating detection unit on the upstream side in the sheet conveyance direction of the platen unit in the fourth embodiment, and the bottom is a perspective view showing the configuration of the main part. Note that the image recording apparatus as the main body apparatus in this example has the same configuration as that of the image recording apparatus 1 in the first embodiment shown in FIGS. In FIG. 7, the same components as those shown in FIG. 3 are given the same reference numerals as those in FIG.

  In FIG. 7, the optical sensor 33 is disposed at a position corresponding to the lower end of the paper floating detection plate 21 that detects the paper floating shown in FIG. 3. The optical sensor 33 includes a light emitting element 33a and a light receiving element 33b.

  The light emitting element 33a and the light receiving element 33b are located in the width direction of the paper 10, and are disposed at positions outside the width of the maximum size of paper that can be passed. The output of the light receiving element 33b is OFF while the irradiation light from the light emitting element 33a is incident, and is ON when the irradiation light is blocked.

  In this configuration, the paper 10 conveyed on the platen belt 11 passes through the first paper guide 19 while being pressed by the first paper guide 19 in contact with the platen belt 11 by its own weight.

  When the paper 10a sent out from the first paper guide 19 to the downstream side in the transport direction is lifted more than a predetermined amount, the light path of the irradiation light from the light emitting element 33a to the light receiving element 33b is blocked by the lift. .

  Also in this case, the distance d1 and height h1 between the first paper guide 19, the optical sensor 33, and the platen belt 11, and the distance d2 and height h2 between the second paper guide 18, the recording head 16, and the platen belt 11. Is the same as that in the first embodiment, the environmental condition in which the paper 10 is lifted before the paper 10 passes through the first paper guide 19 and reaches the paper floating detection plate 21, and the second paper guide 18. The environmental conditions in which the paper floats up to the recording head 16 after passing through are set to be the same.

  Thus, before the paper 10 reaches the recording head 16, the same paper floating state as when the paper 10 reaches the recording head 16 is reproduced between the first paper guide 19 and the optical sensor 33. I can do it. Thereby, before the paper 10 reaches the recording head 16, it is possible to reliably detect and eliminate paper floating that may cause actual damage.

  Further, in this example, since there is no member that detects the sheet floating on the sheet conveyance path, the sheet does not contact the member that detects the sheet floating. As a result, unnecessary damage such as turning or peeling is not applied to the leading edge of the paper. Therefore, there is no possibility that the paper will come into contact with the recording head 16, and it is possible to prevent the paper from being soiled or the recording head from being damaged.

1 is a side view schematically illustrating a configuration of a main part of an image recording apparatus in Embodiment 1. FIG. 2 is a top view schematically showing a platen portion of the image recording apparatus in Embodiment 1. FIG. FIG. 3 is an enlarged view of the vicinity of a sheet floating detection plate and a most upstream recording head on the upstream side in the sheet conveying direction of the platen unit of the image recording apparatus according to the first exemplary embodiment. FIG. 6 is a diagram illustrating a modified example of the first embodiment. FIG. 10 is an enlarged view of the vicinity of a sheet floating detection plate on the upstream side in the sheet conveyance direction of the platen unit and the uppermost recording head in the second embodiment. FIG. 10 is an enlarged view of the vicinity of a sheet floating detection plate on the upstream side in the sheet conveyance direction of the platen unit and the uppermost recording head in Embodiment 3. FIG. 10 is an enlarged view of the vicinity of a recording medium floating detection unit on the upstream side in the sheet conveyance direction of a platen unit in Embodiment 4.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image recording device 2 Paper feed part 3 Platen part 4 Image recording part 5 Recording medium floating detection part 6 Recording medium discharge part 7 Paper tray 8 Pickup roller 9 Registration roller pair 10 Paper (recording medium)
11 Platen Belt 12 Platen Belt Roller 12-1 Rotating Shaft 13 Driven Roller 14 Platen Frame 15 Platen Suction Part 16 (16k, 16c, 16m, 16y) Recording Head 17 Carriage 18, 18a Second Paper Guide 19, 19a First Paper guide 21, 21a Paper floating detection plate 22 Sensor 23 Rotating shaft 24 Discharge part transport roller pair 25 Discharge part discharge roller pair 26 Discharge tray 27 Belt roller drive motor 28 Suction hole 29 Groove 31 Suction hole 32 Paper guide 33 Optical sensor 33a Issuing element 33b Light receiving element

Claims (6)

A recording medium conveyed in the first direction by a conveying means;
An image recording unit having a line head for recording an image on the recording medium;
A first guide member disposed upstream of the line head in the first direction;
Detecting means arranged on the downstream side in the first direction from the first guide member, and detecting the lifting of the recording medium that has passed through the first guide member;
A second guide member disposed downstream of the detection means in the first direction and upstream of the line head in the first direction,
The distance between the first guide member and the detection unit in the first direction is d1, the distance between the detection unit and the recording medium conveyance surface of the conveyance unit is h1, and the second guide member and the line head. And the distance in the first direction is d2, and the distance between the line head and the recording medium conveying surface of the conveying means is h2,
An image recording apparatus, wherein h1 / d1 and h2 / d2 have a substantially equal relationship . A recording medium conveyed in the first direction by a conveying means;
An image recording unit having a line head for recording an image on the recording medium;
A first guide member disposed upstream of the line head in the first direction;
Detecting means disposed on the downstream side in the first direction from the first guide member, and detecting the lifting of the recording medium that has passed through the first guide member;
A second guide member disposed downstream of the detection means in the first direction and upstream of the line head in the first direction,
The distance between the first guide member and the detection unit in the first direction is d1, the distance between the detection unit and the recording medium conveyance surface of the conveyance unit is h1, and the second guide member and the line head. And the distance in the first direction is d2, and the distance between the line head and the recording medium conveyance surface of the conveyance means is h2,
(H2 / d2) × 0.7 ≦ h1 / d1 ≦ (h2 / d2) images recording apparatus you characterized as having a relationship × 1.1. Wherein the distance d2 between the distance d1, the image recording apparatus according to claim 1 or 2, characterized in that it has a relation of d2 × 0.8 ≦ d1 ≦ d2 × 1.2. The image recording unit has a plurality of line heads,
The first guide member and the detection means are disposed only upstream of the plurality of line heads in the first direction, and the second guide member is disposed corresponding to each of the plurality of line heads. The image recording apparatus according to claim 1, wherein the image recording apparatus is provided. The image recording apparatus according to claim 1 , wherein the first guide member and / or the second guide member is in contact with a recording medium conveyance surface of the conveyance unit. 3. The image recording apparatus according to claim 1 , wherein the first guide member and / or the second guide member has a predetermined distance from a recording medium conveyance surface of the conveyance unit.

Images