JP2012091392A - Liquid droplet discharging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To compensate for a hitting position gap of a first liquid to a recording medium due to conveyance delay of the recording medium caused when the recording medium comes in contact with a roller.SOLUTION: The liquid droplet discharging device 1 includes a first liquid discharging head 8a which discharges the first liquid, a second liquid discharging head 8b which is arranged on an upstream side from the first liquid discharging head 8a and discharges a second liquid, a rotary roller 34 (34a) between the first and second liquid discharging heads 8a and 8b, a first position sensor 53 (53a and 53b) which detects whether the recording medium M is located on a first predetermined position between the rotary roller 34 (34a) and the first liquid discharging head 8a, and a second position sensor 54 which detects whether the recording medium M is located on a second predetermined position of an upstream side from the second liquid discharging head 8b. A discharging timing of the second liquid is determined on the basis of a time point when the recording medium M reaches the second predetermined position. A discharging timing of the first liquid is determined on the basis of a time point when the recording medium M reaches the first predetermined position.

Description

  The present invention relates to a droplet discharge device that discharges a first liquid such as ink to form an image on a recording surface of a recording medium. In particular, the present invention is configured to discharge a second liquid such as a processing liquid for aggregating or precipitating the components of the first liquid onto the recording surface of the recording medium before discharging the first liquid. In addition, the present invention relates to a droplet discharge device configured to abut a roller on a recording surface of a recording sheet after discharging a second liquid and before discharging a first liquid.

  Conventionally, in order to maintain high printing quality or improve image quality regardless of the difference in properties of the recording medium, the first liquid before discharging the first liquid such as ink for forming an image on the recording medium. There is known a droplet discharge device configured to apply a second liquid for aggregating or precipitating the components to a recording medium position where the first liquid is discharged. For example, an ink jet recording apparatus disclosed in Patent Document 1 includes an ink composition attaching unit (ink jet recording head) that ejects an ink composition toward a recording medium, and a reaction liquid attaching unit (reaction) that ejects a reaction liquid toward the recording medium. An ink jet recording head as a liquid applying means), and the reaction liquid and the ink composition are landed on the recording medium so that the position of the reaction liquid adhering to the recording medium coincides with the printing position of the ink composition. It is configured. Further, the ink jet recording apparatus of Patent Document 1 includes two rollers that pressurize and heat the reaction liquid attached to the recording medium.

JP 2000-37942 A

  As described in Patent Document 1, when the second liquid (corresponding to the reaction liquid of Patent Document 1) attached to the recording medium is brought into contact with a roller, the recording medium is moved into the space between the rollers. The downstream end of the recording medium comes into contact with the circumferential surface of the roller, or the roller slides on the recording medium to cause a winding failure, resulting in a recording medium conveyance delay. However, the discharge timing of the first liquid (corresponding to the ink of Patent Document 1) does not take into account the above-described transport delay, so that the landing position of the first liquid on the recording medium is displaced, and the second liquid is discharged. It is difficult to properly land the first liquid on the landing position of the liquid, and the image formed on the recording medium is disturbed.

  Therefore, according to the present invention, in the droplet discharge device having a configuration in which the second liquid that has landed on the recording medium is brought into contact with the roller, the second delay is taken into account when the recording medium is transported between the rollers. An object of the present invention is to suppress the above-mentioned image disturbance by performing the discharge control of one liquid.

  A droplet discharge device according to the present invention includes a transport mechanism that transports a recording medium in a transport direction, and a first liquid discharge head that discharges a first liquid for forming an image toward a recording surface of the recording medium that is transported. And a second liquid that is disposed upstream of the first liquid discharge head in the transport direction and that aggregates or deposits the components of the first liquid toward the recording surface of the transported recording medium. A two-liquid discharge head, a rotating roller provided between the first liquid discharge head and the second liquid discharge head so that an outer peripheral surface is in contact with the recording surface of the recording medium to be conveyed; A liquid droplet ejection apparatus comprising: a liquid ejection head and a control unit that controls operations of the second liquid ejection head, wherein recording is performed at a first predetermined position between the rotating roller and the first liquid ejection head. Medium is located A first position sensor capable of detecting whether or not, and a second position sensor for detecting whether or not the recording medium is located at a second predetermined position upstream of the second liquid discharge head in the transport direction. And the controller is configured to eject the second liquid ejecting head from the second liquid ejecting head with reference to a time point when the second position sensor detects that the transported recording medium has reached the second predetermined position. The ejection timing of the two liquids is determined, and the first liquid ejection head ejects the liquid on the basis of the time point when the first position sensor detects that the transported recording medium has reached the first predetermined position. The discharge timing of the first liquid is determined.

  According to the above configuration, the recording medium passes through the second predetermined position in the process of being transported, receives the discharge of the second liquid from the second liquid discharge head, comes into contact with the outer peripheral surface of the rotating roller, and has the first predetermined position. Passing through the position, the first liquid is ejected from the first liquid ejection head. Since the discharge timing of the second liquid is determined with reference to the point in time when the recording medium reaches the immediately preceding second predetermined position, the second liquid can be landed at a desired position on the recording surface. Further, since the recording medium is bent due to contact with the rotating roller, even when the recording medium does not reach the first liquid head when the recording medium is scheduled, the recording medium passes through the rotating roller and is first. Since the discharge timing of the first liquid is determined based on the time point when the predetermined position is reached, the first liquid can be landed accurately at a desired position on the recording surface. Therefore, it is possible to accurately match the position where the second liquid lands and the position where the first liquid lands, thereby suppressing the disturbance of the image formed on the recording medium.

  As described above, according to the present invention, the first liquid can be landed accurately at a desired position on the recording surface, and the landing position of the first liquid and the landing position of the second liquid can be accurately matched. Therefore, the disturbance of the image formed on the recording medium can be suppressed.

1 is a schematic diagram illustrating an overall configuration of an inkjet printer according to a first embodiment of the present invention. In order to show the paper feeding mechanism and the conveyance path shown in FIG. 1 as extending on a plane, the IIa-IIa arrow view, the IIb-IIb arrow view, and the IIc-IIc arrow view of FIG. It is a figure formed by combining from below. IIa-IIa arrow view is a diagram composed of a combination of a plan view of the paper feed mechanism and a view showing the upstream portion of the transport path extending on the plane along the transport direction, IIb-IIb arrow view, The plan view of the straight line portion of the transport path and the IIc-IIc arrow view are views showing the downstream portion of the transport path extending on the plane along the transport direction. It is a figure which shows the periphery of the linear part of the conveyance path | route shown in FIG. 1 seeing in the width direction. It is a block diagram which shows the whole structure of the control part of the inkjet printer shown in FIG. It is a flowchart which shows the procedure of the main process of the inkjet printer performed by the control part shown in FIG. It is a flowchart which shows the procedure of the initial process shown in FIG. 6 is a flowchart illustrating a procedure of image forming processing illustrated in FIG. 5. FIG. 8 is a flowchart showing a part of the procedure of the conveyance / discharge process shown in FIG. 7 (generally, a procedure from the start of the conveyance / discharge process to the determination of the discharge timing of the processing liquid). FIG. 8 is a flowchart showing a part of a procedure of the transport / discharge process shown in FIG. 7 (generally, a procedure from determination of the discharge timing of the processing liquid to the end of the transport / discharge process). It is a figure which shows the periphery of the linear part of the conveyance path | route of the inkjet printer which concerns on 2nd Embodiment of this invention seeing in the width direction. It is a top view of the linear part of the conveyance path | route of the inkjet printer which concerns on 3rd Embodiment of this invention. 12 is a flowchart showing a procedure of image forming processing executed by the ink jet printer shown in FIG. 11. It is a top view of the linear part of the conveyance path | route of the inkjet printer which concerns on 4th Embodiment of this invention. 14 is a flowchart showing a part of a procedure of a conveyance / discharge process executed by the ink jet printer shown in FIG. 13 (generally, a procedure from determination of the discharge timing of the processing liquid to the end of the conveyance / discharge process).

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. Here, the liquid droplet ejection apparatus according to the present invention will be described by applying it to an ink jet printer (hereinafter simply referred to as “printer”). In the following, the same or corresponding elements are denoted by the same reference symbols throughout the drawings, and the detailed description thereof is omitted.

[First Embodiment]
FIG. 1 is a schematic diagram showing an overall configuration of a printer 1 according to the first embodiment of the present invention. As shown in FIG. 1, the printer 1 has a substantially rectangular parallelepiped housing 2. A paper discharge unit 3 for storing the paper M on which the image is formed on the recording surface is provided on the outer upper portion of the housing 2. An operation panel 4 operated by a user is provided on the outer surface of the housing 2.

  In the housing 2, a paper feed mechanism 5, a transport path 6, a transport mechanism 7, five heads 8, and a control unit 9 are provided. The paper feed mechanism 5 stores the paper M and sends the stored paper M to the transport path 6. The conveyance path 6 is formed in an S-shape whose left and right are reversed as a whole, and includes an upstream portion 6a extending upward from the sheet feeding mechanism 5, a linear portion 6b extending linearly from the end of the upstream portion 6a, and the end of the linear portion 6b. The downstream part 6c extends upward from the downstream part 6c, and the end of the downstream part 6c is connected to the paper discharge part 3 through a discharge port 2a formed in the upper part of the housing 2. The transport mechanism 7 transports the paper M sent out by the paper feed mechanism 5 to the paper discharge unit 3 along the transport path 6. The five heads 8 include four recording heads 8a that eject ink for image formation and one processing liquid head 8b that ejects processing liquid for improving image quality. The control unit 9 controls operations of the paper feed mechanism 5, the transport mechanism 7, and the five heads 8. As a result, the processing liquid and the ink are ejected at an appropriate ejection timing toward the recording surface of the paper M being transported along the transport path 6, and an image is formed on the recording surface.

  In the printer 1, a total of four types of inks are used: black ink, cyan ink, magenta ink, and yellow ink. The processing liquid is ejected toward the recording surface of the paper M prior to the ink. The material of the treatment liquid is appropriately selected according to the properties of the ink, such as a liquid containing a cationic compound, in particular, a cationic polymer, a cationic surfactant, a polyvalent metal salt such as a calcium salt or a magnesium salt. The When the ink lands on the recording surface of the paper M to which such a treatment liquid has been applied in advance, the polyvalent metal salt or the like acts on the pigment or dye that is the colorant of the ink, and the insoluble or poorly soluble metal composite or the like aggregates or Formed by precipitation. As a result, the penetrability of the landed ink into the paper M is lowered, and the ink is easily fixed on the recording surface of the paper M, so that the image quality is increased and the image quality is increased. In addition, a treatment liquid that agglomerates the pigment may be used for the pigment ink, and a treatment liquid that precipitates the dye may be used for the dye ink, and a treatment liquid that has both aggregating and precipitation functions may be used. May be.

  Hereinafter, the configuration of the printer 1 will be described in detail with reference to FIGS. FIG. 2 is a diagram obtained by combining the IIa-IIa arrow view, the IIb-IIb arrow view, and the IIc-IIc arrow view of FIG. 1 in this order from the bottom of the drawing. In FIG. 2, the intermediate portion between the upstream portion 6a and the downstream portion 6c is omitted as appropriate. FIG. 3 is a view showing the periphery of the straight portion 6b of the transport path 6 shown in FIG. 1 as viewed in the width direction. The “conveying direction” in the following description is the direction in which the sheet M is conveyed by the conveying mechanism 7 and coincides with the extending direction of the conveying path 6 and is horizontal around the straight line portion 6b.

(head)
As shown in FIG. 1, the five heads 8 are arranged at intervals in the transport direction. Among them, the processing liquid head 8b is disposed on the most upstream side in the transport direction in order to discharge the processing liquid prior to the ink as described above. The four recording heads 8a are configured to eject different types of ink, and are arranged from the upstream side in the transport direction in order of decreasing lightness of the ejected ink. That is, they are arranged in the order of black, cyan, magenta, and yellow from the upstream side in the transport direction.

  Each head 8 has the same configuration. The printer 1 is a so-called line printer, and each head 8 has a substantially rectangular parallelepiped shape that is long in the width direction (direction perpendicular to the transport direction and perpendicular to the paper surface of FIG. 1). Each head 8 has a head main body 41 through which liquid flows, and the lower surface of the head main body 41 forms an ejection surface 42 that faces the linear portion 6b of the transport path 6 with a predetermined interval. A plurality of discharge ports are arranged in the width direction on the discharge surface 42, and the liquid flowing through the head main body 41 is a recording surface of the sheet M that is transported horizontally along the straight portion 6b through each discharge port. It is discharged toward. The head body 41 includes a head actuator 61 (see FIG. 4) that applies discharge energy to the liquid in the selected plurality of discharge ports, and the liquid is selectively discharged from the plurality of discharge ports by the operation of the head actuator 61. It has become so. The operation of the head actuator 61 is controlled by the control unit 9. Specifically, the head actuator 61 includes a piezo actuator or a thermal heating element provided so as to correspond to each of a plurality of ejection openings.

  The printer 1 according to the present embodiment can form an image with a resolution of 600 dpi in the transport direction and the width direction. For this reason, the recording surface of the sheet M is defined with a plurality of unit regions (pixel regions) partitioned in a grid pattern with an interval of 1/600 inch in the width direction and the longitudinal direction. A number of ejection openings corresponding to the number of unit areas for one column in the width direction defined on the maximum width paper that can be used by the printer 1 are arranged at 1/600 inch intervals in the width direction. In order to realize the arrangement at this minute interval, the plurality of discharge ports may be arranged in a staggered manner. That is, some of the plurality of discharge ports may be arranged at different positions in the transport direction with respect to the other discharge ports. In the following description, “ejection timing” means the timing at which liquid is ejected from an ejection port at an arbitrary position in the transport direction. The “ink discharge position” and the “processing liquid discharge position” are the positions of the paper M on which the ink or processing liquid discharged from the discharge port is landed.

  In addition, four ink tanks 46 for storing different types of ink and one processing liquid tank 47 for storing processing liquid are detachably provided on the inner bottom of the housing 2. The liquid stored in the tanks 46 and 47 is appropriately replenished to the corresponding head 8 via a tube (not shown) when the liquid is discharged from the corresponding head 8.

(Paper feed mechanism)
As shown in FIG. 1, the paper feed mechanism 5 has a paper feed tray 11 and a paper feed roller 12. The paper feed tray 11 is detachably provided above the ink tank 46 and the processing liquid tank 47 in the housing 2 and is formed in a box shape having an opening at the top. A plurality of sheets M are stored in the sheet feed tray 11 in a state of being stacked one above the other.

  As shown in FIG. 2, in the paper feed tray 11, the vertical direction of the paper M (in the rectangular paper, one side is long) is directed to the longitudinal direction of the paper feed tray 11 (horizontal direction in FIG. 1). The lateral direction of the paper M is directed in the width direction orthogonal to the longitudinal direction of the paper feed tray 11. A pair of paper guides 13 and 14 are attached to the bottom of the paper feed tray 11 via a slider 15. The paper guides 13 and 14 protrude from the bottom into the paper feed tray 11, extend in the longitudinal direction of the paper feed tray 11, and are arranged in parallel at the same distance from the center line in the width direction of the paper feed tray 11. Yes. The paper guides 13 and 14 can be moved in the width direction of the paper feed tray 11 while the distance to the center line of the paper feed tray 11 is kept equal to each other by the slider 15. When the paper M is stored, the distance between the paper guides 13 and 14 is adjusted so that both sides in the width direction of the paper M are close to the inner surfaces of the paper guides 13 and 14. Thus, regardless of the size of the sheet M in the width direction, the center line CM in the width direction of the sheet M can be guided to coincide with the center line in the width direction of the sheet feed tray 11.

  When the pair of paper guides 13 and 14 are maximally separated from each other, the first type of paper M1 that is less than the distance and has a width equal to or larger than the first dimension is preferably aligned. When the pair of paper guides 13 and 14 come close to each other as much as possible, the second type of paper M2 having a width equal to or smaller than the second dimension and less than the distance at that time is suitably aligned. The first dimension is, for example, 200 mm. In this case, the first type paper M1 includes paper of 6P size, A4 size, Legal size, Letter size, and the like. The second dimension is, for example, 185 mm. In this case, the second type paper M2 includes papers such as Executive size and B5 size. As described above, the printer 1 can selectively convey one of a plurality of types of paper having different dimensions to form an image on the paper. Here, for simplification of description, it is assumed that the sheet M having the maximum length in the width direction among the sheets M usable in the printer 1 is included in the first type sheet M1, and the minimum length in the width direction. It is assumed that the sheet M having the thickness is included in the second type sheet M2. However, the paper having the minimum length in the width direction may be a paper having a smaller width (for example, KG size) than the above-mentioned examples, and the paper having the maximum length in the width direction is described above. It may be a paper having a width larger than that of the paper (for example, B4 size or A3 size).

  The paper feed roller 12 is provided so as to come into contact with the uppermost paper of the paper stored in the paper feed tray 11 from above, and is driven to rotate by a paper feed motor 62 (see FIG. 4). When the paper feed roller 12 is driven to rotate, the uppermost sheet is sent from the upper opening of the paper feed tray 11 to the upstream portion 6 a of the transport path 6. The operation of the paper feed motor 62 is controlled by the control unit 9 (see FIGS. 1 and 4).

  The center line in the width direction of the paper feed tray 11 is continuous with the center line R in the width direction of the transport path 6. According to the paper feed mechanism 5 configured as described above, the center line CM of the paper M is guided so as to coincide with the center line of the paper feed tray 11 regardless of the dimension in the width direction. The center line CM can be along the center line R in the width direction of the transport path 6 regardless of the dimension in the width direction. Hereinafter, the center line R in the width direction of the transport path 6 extending in the transport direction will be described as a “reference line R” that should coincide with the center line CM of the paper M.

  As for the paper feed tray 11, a plurality of paper feed trays 11 having the above-described configuration are provided, each of which stores a plurality of different sizes of paper, and a paper feed tray in which paper to be fed is stored under the control of the control unit 9. 11 may be selected and control may be performed so that a desired size of paper M is fed from the paper feed tray 11. Further, instead of the above-described configuration, a predetermined frame corresponding to the paper size is provided in the paper feed tray 11, and the paper M is stored so that the center line CM of the paper M coincides with the center line of the paper feed tray 11. A plurality of paper feed trays 11 corresponding to different paper sizes are provided, the paper feed tray 11 storing the paper to be fed is selected under the control of the control unit 9, and the desired paper feed tray 11 is selected. It is also possible to control so that the size of the paper M is fed.

(Transport route)
As shown in FIG. 1, the upstream portion 6 a of the transport path 6 is formed by a pair of transport guides 21 and a pair of transport guides 22 that continuously extend upward from the upper opening of the paper feed tray 11. The straight portion 6 b of the transport path 6 is formed by the upper surfaces of the platens 23 a to 23 d arranged above the paper feed tray 11. The platens 23a to 23d are arranged from the vicinity of the upper end of the conveyance guide 22 toward the back side of the housing 2, and the upper surfaces of the platens 23a to 23d are located in the same horizontal plane. The downstream portion 6b of the transport path 6 is formed by a pair of transport guides 24 and a pair of transport guides 25, and the upper end of the transport guide 22 is located in the vicinity of the discharge port 2a. A transport guide may be used instead of the platens 23b and 23d.

(Transport mechanism)
As shown in FIG. 1, the transport mechanism 7 includes feed roller pairs 31 and 32, a transport roller pair 33, an extension roller pair 34, transport roller pairs 35 to 37, and feed roller pairs 39 in order from the upstream side. ing.

  The feed roller pair 31 is interposed between the transport guides 21 and 22, and the feed roller pair 32 is disposed close to the transport guide 22 on the downstream side in the transport direction. The feed roller pair 38 is interposed between the transport guides 24 and 25, and the feed roller pair 39 is disposed close to the downstream side of the transport guide 25 in the transport direction. Each pair of feed rollers 31, 32, 38 and 39 is composed of two rollers arranged so as to sandwich the paper M conveyed along the conveyance path 6 from the recording surface side and the back surface side, one of which is driven. The other is a driven roller.

  The conveyance roller pair 33 is disposed close to the upstream side of the platen 23a in the conveyance direction, the extension roller pair 34 is interposed between the platens 23a and 23b, and the conveyance roller pair 35 is interposed between the platens 23b and 23c. The conveyance roller pair 36 is interposed between the platens 23c and 23d, and the conveyance roller pair 37 is disposed close to the downstream side of the platen 23d. On the other hand, the treatment liquid head 8b is disposed above the platen 23a, and the four recording heads 8a are disposed above the platen 23c. Accordingly, the conveyance roller pair 33 is located on the upstream side of the processing liquid head 8b. The pair of extension rollers 34 and the pair of transport rollers 35 are located between the processing liquid head 8b and the black recording head disposed on the most upstream side of the four recording heads 8a. The conveyance roller pair 36 and the conveyance roller pair 37 are located on the downstream side in the conveyance direction with respect to the yellow recording head arranged on the most downstream side among the four recording heads 8a.

  These roller pairs 33 to 37 are composed of upper rollers 33a to 37a disposed so as to contact the recording surface of the sheet M from above and lower rollers 33b to 37b disposed to contact the back surface of the sheet M from below. Thus, the rotation shafts of the upper rollers 33a to 37a and the rotation shafts of the lower rollers 33b to 37b extend parallel to the width direction and are arranged vertically. Therefore, the tangent lines of the outer peripheral surfaces of the upper roller and the lower roller extend horizontally in the same plane as the upper surfaces of the platens 23a to 23d at positions where they can contact the paper M.

  Regarding the conveyance roller pairs 33 and 35 to 37, the lower rollers 33b and 35b to 37b are driving rollers, and the upper rollers 33a and 35a to 37a are driven rollers. The transport roller pair 33 and the transport roller pair 36 are arranged so as to sandwich the five heads 8 in the transport direction, and each upper roller forms spur rollers 33a and 36a (also referred to as toothed rollers). . The spur rollers 33a and 36a are configured by a rotation shaft extending in the width direction and a plurality of toothed disks provided at intervals on the rotation shaft. The toothed disk is a thin plate having a plurality of teeth (or protrusions) formed on the peripheral surface, and contacts the recording surface of the paper P at the tips of the teeth. The spur rollers 33a and 36a are urged toward the corresponding lower rollers 33b and 36b. If the spur roller is employed, the paper M can be easily caught between the upper and lower rollers, and the paper M can be smoothly conveyed. In addition, since the contact area between the paper M and the spur roller is small, it is possible to avoid dirt and the like adhering to the roller from adhering to the paper.

  With respect to the extension roller pair 34, only the lower roller 34b may be a driving roller, the upper roller 34a may be a driven roller, and both the rollers 34a and 34b may be driving rollers. The upper roller 34a of the extension roller pair 34 has a long cylindrical roller provided on the rotation shaft thereof, and the surface of the roller is smoothly formed, and the printing range of the paper allowed by the printer 1 It has the same or larger width, and its surface contacts the entire width of the recording surface of the paper P. The upper roller 34a of the extension roller pair 34 is also biased toward the corresponding lower roller 34b.

  Each drive roller of the roller pair 31 to 39 is rotationally driven by a conveyance motor 63 (see FIG. 4), and each driven roller rotates as the drive rollers rotate. Each drive roller is rotationally driven at an appropriate angular speed corresponding to its own radius so as to transport the paper M along the transport path 6 at a constant transport speed V [m / s]. The operation of the transport motor 63 is also controlled by the control unit 9 (see FIGS. 1 and 4). The conveyance motor 63 may be provided individually for the drive roller, or may be provided in common for some of the drive rollers. Here, for simplification of explanation, it is assumed that each drive roller is driven by one transport motor 63.

  When each drive roller is rotationally driven along with the sheet feeding operation, the sheet M is transported along the transport guides 21 and 22 to the linear portion 6b by the feed roller pair 31 and 32. The sheet M conveyed to the straight line portion 6b passes between the spur roller 33a and the lower roller 33b of the conveyance roller pair 33 and is conveyed along the upper surface of the platen 23a. On the platen 23a, there is a “processing liquid discharge position” for receiving the processing liquid discharged from the processing liquid head 8b, and the droplets of the processing liquid land on the recording surface when passing through the processing liquid discharge position.

  Next, the sheet M abuts on the upper roller 34a and the lower roller 34b of the extension roller pair 34, and passes between the rollers 34a and 34b horizontally. The conveyance speed V of the sheet M is such that the processing liquid does not completely penetrate into the sheet M while the sheet M is conveyed from the processing liquid discharge position to the “roller contact position” where the sheet M contacts the extension roller pair 34. Set high. For this reason, the processing liquid which does not penetrate into the sheet M and remains on the recording surface is sandwiched between the upper roller 34a urged downward and the lower roller 34b receiving the urging pressure. As a result, the droplets of the processing liquid are stretched thinly on the recording surface to widen the application range of the processing liquid. Note that the surface of the roller forming the upper roller 34a has non-liquid absorbency in order to increase the adhesion efficiency of the processing liquid to the paper M. For example, a water-insoluble resin such as polyethylene or a metal such as iron or nickel Or it forms with alloys, such as the oxide and stainless steel.

  Next, the sheet M passing through the extension roller pair 34 is transported along the upper surface of the platen 23b, passes between the upper roller 35a and the lower roller 35b of the transport roller pair 35, and is transported along the upper surface of the platen 23c. The On the platen 23c, an ink discharge position (K) for receiving black ink discharge, an ink discharge position (C) for receiving cyan ink discharge, an ink discharge position (M) for receiving magenta ink discharge, and yellow ink discharge are provided. There is an ink discharge position (Y) to be received, and ink droplets land on the recording surface when sequentially passing through these ink discharge positions.

  Thereafter, the sheet M passes between the spur roller 36a and the lower roller 36b of the conveyance roller pair 36, is conveyed along the platen 23d, and is conveyed along the conveyance guides 24 and 25 by the feed roller pair 38 and 39 along the paper discharge unit 3. It is conveyed to. A guide plate 26 is provided between the conveyance roller pair 37 and the conveyance guide 23 to prevent the paper M from being wound around the upper roller 37a or the lower roller 37b of the conveyance roller pair 37.

(Around the extension roller pair)
As shown in FIG. 3, a guide plate 51 is provided between the extension roller pair 34 and the transport roller pair 35. The guide plate 51 is formed in a square shape as viewed from the side as a whole, and is arranged along the peripheral surface of the upper roller 34a on the downstream side in the conveying direction of the upper roller 34a. The lower end portion of the guide plate 51 is bent and is in close proximity to the peripheral surface of the upper roller 34a. By such a guide plate 51, the leading edge of the sheet M is satisfactorily guided so as to be engaged between the upper roller 35a and the lower roller 35b of the guide roller pair 35 after passing through the roller contact position. In other words, the recording surface of the paper M may adhere to the peripheral surface of the upper roller 34a via the processing liquid when passing through the roller contact position, whereby the paper M may wind around the upper roller 34a and leave the platen 23b. There is. Even in such a situation, the leading edge of the paper M can be brought back against the lower end of the guide plate 51 and returned downward. Thereby, the back surface of the paper M can be returned to the top surface of the platen 23b.

  An angle α formed by a line connecting the center of the upper roller 34a to the roller contact position and a line connecting the center of the upper roller 34a to the lower end of the guide plate 51 is an angle smaller than 90 degrees, preferably 10 degrees to An angle in the range between 45 degrees. If the angle α is such a value, the paper M can be quickly returned downward. Further, it is possible to avoid the sheet M trying to pass through the extension roller pair 34 appropriately in the horizontal direction from interfering with the guide plate 51. A distance X2 in the conveyance direction from the front end of the guide plate 51 to the rotation center of the conveyance roller pair 35 is equal to or longer than a distance X1 in the conveyance direction from the front end of the guide plate 51 to the rotation center of the extension roller pair 34. As a result, the sheet M returned downward by the guide plate 51 is guided so as to be more reliably engaged between the rollers 35 a and 35 b of the transport roller pair 35. In the present embodiment, an example is shown in which three guide plates 51 are arranged at intervals in the width direction (see FIG. 2), but even if a single long guide plate 51 is provided in the width direction. Good. Further, the lower end of the guide plate 51 may be brought into contact with the peripheral surface of the upper roller 34a. In this case, the guide plate 51 can have a function of scraping off the processing liquid adhering to the peripheral surface.

  The upper roller 34a of the extension roller pair 34 has non-liquid absorbability as described above. In order to shorten the tact time of image formation, it is preferable to increase the conveyance speed of the sheet M as much as possible. Therefore, the upper roller 34a is also driven to rotate at as high a speed as possible. For this reason, when the upper roller 34a rotates, the processing liquid adhering to the peripheral surface of the upper roller 34a may be scattered so as to be wound up downstream in the transport direction. Therefore, a duct 52 is provided above the straight portion 6b of the transport path 6 for sucking droplets of the processing liquid. The suction port of the duct 52 is disposed downstream of the upper roller 34a in the transport direction and above it. Thereby, it can suppress favorably that the inside of the housing | casing 2 is polluted with a process liquid.

  The printer 1 then detects a first position sensor 53 that detects whether or not the paper M is located at the first predetermined position, and a second position that detects whether or not the paper M is located at the second predetermined position. Sensor 54. The first position sensor 53 is disposed upstream of the black recording head 8a in the transport direction and downstream of the extension roller pair 34 in the transport direction. More specifically, the first position sensor 53 is downstream of the transport roller pair 35 in the transport direction. Arranged on the side. The first predetermined position is a position on the transport path 6 and is separated by a distance D1 upstream of the ink discharge position (K) where black ink is discharged and in the transport direction from the roller contact position. It is the position of the downstream side. The first predetermined position is a distance D2 from an ink discharge position (C) that receives cyan ink discharge, a distance D3 from an ink discharge position (M) that receives magenta ink discharge, and an ink discharge that receives yellow ink discharge. It is separated from the position (Y) by a distance D4. The second position sensor 54 is disposed upstream of the treatment liquid head 8 b in the transport direction, and more specifically, is disposed downstream of the transport roller pair 33 in the transport direction. The second predetermined position is a position on the transport path 6, which is separated from the processing liquid discharge position by a distance d on the upstream side in the transport direction, and in the transport direction from a position where the sheet M contacts the transport roller pair 33. This is the downstream position.

  The first position sensor 53 is configured by a transmissive photo interrupter, and includes a light projecting unit 55 disposed above the platen 23c, and a light receiving unit 56 disposed inside the platen 23c. The light projecting unit 55 can emit inspection light downward, and the light receiving unit 56 is provided directly below the light projecting unit 55 on the optical path of the inspection light so as to receive the inspection light. . The platen 23c is provided with a slit window 57 so that the light receiving portion 56 in the platen 23c can receive inspection light from outside the platen 23c. The slit window 57 may be a slit hole formed through the platen 23c, and may be configured by closing such a slit hole with a plate material made of a translucent material. The light projecting unit 55 and the light receiving unit 56 may be integrated, and the inspection light emitted downward may be reflected on the platen 23c or the paper M, and the reflected light may be received by the light receiving unit 56.

  In the above configuration, if the slit window 57 is not covered with the paper M, the light receiving unit 56 receives the inspection light from the light projecting unit 55 and enters a light receiving state. When the leading edge of the paper M reaches the slit window 57, the light receiving unit 56 switches from the light receiving state to the non-light receiving state where the inspection light cannot be received. While the paper M covers the slit window 57, the light receiving unit 56 maintains a non-light receiving state. When the tail end of the paper M being conveyed passes through the slit window 57, the light receiving unit 56 is switched from the non-light receiving state to the light receiving state.

  The light projecting unit 55 is supported on the downstream end surface of the duct 52 in the transport direction via the shielding member 50. The shielding member 50 is formed in a plate shape, and is fixed to the downstream end face of the duct 52. As a result, the guide member 51 is disposed between the shielding member 50 and the extension roller pair 34.

  The lower end portion of the shielding member 50 projects downward from the suction port of the duct 52. By providing such a shielding member 50, the processing liquid splashed from the upper roller 34 a of the extension roller pair 34 collides with a portion projecting below the duct 52 on the upstream end surface in the transport direction of the shielding member 50. Can be made. Thereby, it is possible to suppress the processing liquid from being scattered downstream of the duct 52 in the transport direction, and it is possible to suitably guide the collided processing liquid to the suction port of the duct 52.

  The light projecting unit 55 is fixed to the downstream end surface of the shielding member 50 in the transport direction, and is disposed adjacent to the downstream end surface. As described above, since the processing liquid is suppressed from being scattered on the downstream side in the transport direction with respect to the shielding member 50, the inspection light emitted from the light projecting unit 55 is favorably suppressed from being scattered by the processing liquid. Can do. Thereby, the detection accuracy of the inspection light in the light receiving unit 56 can be maintained. Further, the shielding member 50 has a function of protecting the first position sensor 53 from the processing liquid and a function of a stay for attaching the first position sensor 53. For this reason, the support structure of the 1st position sensor 53 can be simplified, and it can suppress favorably that the structure of the extension roller pair 34 periphery in the housing | casing 2 is complicated.

  As shown in FIG. 2, the first position sensors 53 (53a, 53b) form a pair. The pair of first position sensors 53a and 53b are arranged symmetrically in the width direction about the reference line R. Thus, each 1st position sensor 53a, 53b is arrange | positioned so that it may leave | separate the same distance from the reference line R, and is unevenly distributed with respect to the reference line R in the width direction. On the other hand, the sheet M is transported so that its center line CM coincides with the reference line R. Generally, the probability that an image is formed at the center in the width direction of the sheet M is formed at the edge. Higher than probability. That is, in the vicinity of the central portion in the width direction of the transport path 6, the amount of processing liquid and ink tends to be increased, and the processing is performed near the reference line R on the upstream side in the transport direction of the extension roller pair 34. The concentration of liquid droplets tends to be high. Since the pair of first position sensors 53a and 53b are arranged so as to avoid the location where the concentration of the treatment liquid splashes is high, the treatment liquid splashes pass below the lower end of the shielding member 50. Even in such a case, it is possible to suppress the first position sensor 53 from being contaminated by the splash as much as possible.

  Further, the pair of first position sensors 53a and 53b are configured to have a pair of edges in the width direction of the sheet M2 when the sheet M2 having the shortest dimension in the width direction among the sheets M usable in the printer 1 is conveyed. It is provided in the position which can detect whether a part is located in the 1st predetermined position. Specifically, the pair of first position sensors 53a and 53b is configured such that the sheet M2 having the minimum width conveyed along the straight line portion 6b with the center line CM coincident with the reference line R is positioned at the first predetermined position. The paper M2 is arranged so as to overlap with a pair of edges in the width direction of the paper M2 when viewed in the normal direction of the recording surface of the paper M2 (that is, the vertical direction). As a result, when the sheet M is conveyed with the center line CM aligned with the reference line R and the leading edge thereof reaches the first predetermined position, each of the first position sensors 53a, 53a, 53b switches from the light receiving state to the non-light receiving state.

  As shown in FIG. 3, the second position sensor 54 includes a switch 58 built in the platen 23 a and an operation piece 59 for operating the switch 58. The operation piece 59 is provided so as to be swingable around a support shaft extending in the width direction in the platen 23a. A slit 60 is formed through the platen 23a in the vicinity of the first predetermined position, and the operation piece 59 is in a protruding position that protrudes upward from the upper surface of the platen 23a through the slit 60 by a biasing member such as a torsion coil spring. Be energized. If the sheet M does not cover the slit 60, the operation piece 59 is located at the protruding position, and the switch 58 is in a non-operation state. When the sheet M is conveyed and passes through the guide roller pair 33, the leading edge of the sheet M pushes the operation piece 59 to the downstream side in the conveyance direction, and the operation piece 59 falls down and is stored in the platen 23a. At this time, the switch 58 is operated by the operation piece 59, and the switch 58 is switched from the non-operation state to the operation state. While the paper M covers the slit 60, the switch 58 maintains the operation state. When the tail end of the conveyed paper M passes through the slit 60, the operation piece 59 returns to the protruding position. At this time, the switch 58 is switched from the operation state to the non-operation state. Since the single second position sensor 54 is arranged on the reference line R (see FIG. 2), if the leading edge of the conveyed paper M reaches the second predetermined position, the width of the paper M is increased. Regardless of the dimensions, the switch 58 switches from the non-operating state to the operating state.

  The control unit 9 (see FIGS. 1 and 4) receives a signal indicating whether the light receiving unit 56 is in a light receiving state or a non-light receiving state from the first position sensor 53, and switches from the second position sensor 54 to the switch. A signal indicating whether 58 is in an operating state or a non-operating state is input. Hereinafter, the signal indicating that the light receiving unit 56 is in the light receiving state and the signal indicating that the switch 58 is in the non-operation state are “off”, and the signal indicating that the light receiving unit 56 is in the non-light receiving state and the switch 58 are The signal indicating the operation state will be described as “ON”.

(Control part)
Hereinafter, the configuration of the control unit 9 of the printer 1 will be described with reference to FIG. FIG. 4 is a block diagram showing an overall configuration of the control unit 9 shown in FIG. The control unit 9 shown in FIG. 4 includes a CPU (Central Processing Unit), a control program executed by the CPU, and an EEPROM (Electrically Erasable and Programmable Read Only Memory) that stores data used for these programs in a rewritable manner, RAM (Random Access Memory) that temporarily stores data when the program is executed. The control program is stored in various recording media such as a floppy (registered trademark) disk, a CD-ROM, and a memory card, and is installed in the EEPROM from these recording media. Then, when the control program is executed by the CPU, each functional unit constituting the control unit 9 shown in FIG. 4 is realized. The control program recorded on the recording medium may be directly executable by the control unit 9, or may be executable only after being installed in the EEPROM. Further, it may be encrypted or compressed.

  As shown in FIG. 4, the control unit 9 includes a recording head control unit 71, a treatment liquid head control unit 72, a paper feed / conveyance control unit 73, a display control unit 74, an image data storage unit 75, an ink ejection data creation unit 76, An ink discharge data storage unit 77, a processing liquid discharge data creation unit 78, a processing liquid discharge data storage unit 79, a position monitoring unit 80, and a paper width determination unit 81 are provided.

  The paper feed transport control unit 73 controls the paper feed motor 62 and the transport motor 63 so that the paper M is transported along the transport path 6 at a constant transport speed V. The display control unit 74 controls the display device 64 so that the display device 64 displays various information related to the printer 1 to the user. The display device 64 may be a monitor of a personal computer 65 (hereinafter simply referred to as “PC 65”) that is provided in an environment that can be visually recognized by the user and is connected to the printer 1 so as to be communicable. It may be a display provided.

  The position monitoring unit 80 monitors the inputs from the first position sensor 53 and the second position sensor 54, and whether these inputs are off, switched from off to on, on, and off from on. It is detected whether it has been switched to. That is, based on the input from the first position sensor 53, the position monitoring unit 80 indicates that the sheet M is not present at the first predetermined position, the leading edge of the sheet M has reached the first predetermined position, It is possible to detect that it is located at one predetermined position and that the tail end of the sheet M has passed the first predetermined position. Based on the input from the second position sensor 54, the fact that the paper M is not present at the first predetermined position, the fact that the leading edge of the paper M has reached the first predetermined position, the paper M is located at the first predetermined position. It is possible to detect the fact and the fact that the tail end of the paper M has passed the first predetermined position. The paper width determination unit 81 is provided by a tray width sensor 66 that detects a user input operation command in the PC 65, a user input operation command in the operation panel 4, and a spacing between the paper guides 13 and 14 provided in the paper feed tray 11. Based on the detection result, the size in the width direction of the sheet M to be conveyed is determined. In the case of a paper feed tray in which the paper size stored in the paper feed tray 11 is determined as one, the paper feed tray 11 in which the paper M having a size requested at the time of printing is stored from the plurality of paper feed trays 11. Is selected, and the dimension in the width direction of the paper M is determined from data relating to the paper size included in the print command, recording data, and the like.

  The image data storage unit 75 stores image data relating to an image recorded on the paper M transferred from the PC 65. Based on the image data stored in the image data storage unit 75, the ink ejection data creation unit 76 creates a total of four ink ejection data corresponding to the recording heads 8a. The ink discharge data storage unit 77 stores the created four ink discharge data. The processing liquid ejection data creation unit 78 creates processing liquid ejection data based on the image data stored in the image data storage unit 75 or the ink ejection data stored in the ink ejection data storage unit 77. The processing liquid discharge data storage unit 79 stores the generated processing liquid discharge data. In the ink ejection data and the treatment liquid ejection data, the amount of droplets (for example, zero, small droplet, medium droplet) ejected to each unit region (pixel region) partitioned by the corresponding head on the recording surface of the paper M is included. And any one of the four stages of large droplets). The ink discharge data and the treatment liquid discharge data may be created in a device that transfers image data such as the PC 65 to the control unit 9, and in that case, the ink discharge data and the treatment liquid discharge data together with the image data are included in the control unit. 9 is transferred. The image data may be transferred not from the PC 65 but from a removable storage terminal (USB memory, hard disk, etc.) connected to the printer.

  Based on the ink ejection data stored in the ink ejection data storage unit 77, the recording head control unit 71 ejects ink drops of the amount indicated by the ink ejection data to each unit area on the recording surface of the paper M. Thus, the head actuator 61 of the recording head 8a is controlled. The processing liquid head control unit 72 uses the processing liquid discharge data stored in the processing liquid discharge data storage unit 79 to treat each unit area on the recording surface of the sheet M with the amount of processing liquid indicated in the processing liquid discharge data. The head actuator 61 of the processing liquid head 8b is controlled so that the droplets are ejected.

  In addition, when the position monitoring unit 80 detects that the input from the first position sensor 53 has been switched from OFF to ON, that is, the recording head controller 71 detects that the leading edge of the sheet M being conveyed by the conveyance mechanism 7 is the first. 1 When it is detected that a predetermined position has been reached, the ejection timing for ejecting ink droplets from the recording head 8a to each unit area is determined based on the switching time (ie, the arrival time). The head actuator 61 is controlled so that ink droplets are ejected at the ejection timing.

  Taking the black recording head as an example, as described above, the distance from the first predetermined position to the ink ejection position (K) is D1. On the other hand, the conveyance speed of the paper M is V [m / s]. Here, the distance in the transport direction between the leading edge of the sheet M and an arbitrary unit area on which ink droplets should be landed is ΔD [m], and the point in time when the leading edge of the sheet M reaches the first predetermined position is t1. In this case, the ejection timing for ejecting the black ink toward the unit area is determined as t1 + (D1 + ΔD) / V. For the cyan recording head, D1 is replaced with D2, and the ejection timing is determined. For the magenta recording head, D1 is replaced with D3, and the ejection timing is determined. For the yellow recording head, D1 is determined. Is replaced with D4 to determine the discharge timing.

  When the position monitoring unit 80 detects that the input from the second position sensor 54 has been switched from OFF to ON, that is, the processing liquid head controller 72 detects the leading edge of the paper M being transported by the transport mechanism 7. When it is detected that the second predetermined position has been reached, the discharge timing for discharging the processing liquid droplets from the processing liquid head 8b to each unit region is determined on the basis of the switching time point (that is, the reaching time point), The head actuator 61 is controlled so that the processing droplets are discharged at the determined discharge timing. The distance from the second predetermined position to the treatment liquid ejection position is d [m], the distance in the transport direction between the leading edge of the paper M and any given unit area where ink droplets should land is Δd [m], and the paper If the transport speed of M is V [m / s] and the time point when the leading edge of the paper M reaches the first predetermined position is t2, the ejection timing for ejecting ink toward the unit area is t2 + (d + Δd) / V is determined.

  As described above, the discharge timing of the processing liquid is determined based on the time point when the leading edge of the sheet M reaches the second predetermined position. There is no conveyance roller pair between the second predetermined position and the processing liquid discharge position, and the sheet M is conveyed between these two positions along the upper surface of the platen 23a. For this reason, the paper M can be transported between two positions at an actual speed substantially equal to the transport speed V controlled by the paper feed transport controller 73. Therefore, the processing liquid can be landed at a desired position on the recording surface of the paper M by discharging the processing liquid droplets at the discharge timing based on the transport speed V of the control target.

  Further, the ink ejection timing is determined based on the time point when the leading edge of the paper M reaches the first predetermined position. There is no conveyance roller pair between the first predetermined position and the ink ejection position, and the sheet M is conveyed between these two positions along the upper surface of the platen 23c. Accordingly, ink can be landed on a desired position on the recording surface of the paper M in the same manner as the processing liquid. Thereby, the landing position of the ink can be accurately adjusted to the landing position of the processing liquid, and the ink can be satisfactorily acted on the processing liquid to form a high-quality image.

  In particular, when the paper M on which the processing liquid has landed enters between the rollers 34a and 34b of the extension roller pair 34, the leading edge of the paper M comes into contact with the peripheral surface of the rollers 34a and 34b, or the rollers 34a and 34b are placed on the paper. If the slippage causes a slippage failure, the conveyance of the paper M may be delayed, and the leading edge of the paper M may not reach the second predetermined position when scheduled based on the control target conveyance speed V. In the present embodiment, the discharge timing is determined based on the point in time when the leading edge of the sheet M that has passed through the extension roller pair 34 has reached the first predetermined position. Therefore, regardless of whether such a conveyance delay has occurred or not, Ink can be landed on the position.

(Main process)
Next, a procedure of processing executed by the control unit 9 of the printer 1 will be described with reference to FIGS. 5 is a flowchart showing a procedure of main processing executed by the control unit 9 shown in FIG. 4, FIG. 6 is a flowchart showing a procedure of initial processing shown in FIG. 5, and FIG. 7 is a flowchart of image forming processing shown in FIG. It is a flowchart which shows a procedure. The main process shown in FIG. 5 starts when the main power of the printer 1 is switched from off to on, and is repeated while the main power is on. When the main power supply of the printer 1 is turned on, first, initial processing (S1) is executed.

  As shown in FIG. 6, in the initial process (S1), it is first determined whether or not at least one of the inputs from the first position sensor 53 and the second position sensor 54 is on (S11). . If there is an ON input (S11: YES), information indicating that the sheet remains in the housing 2 is displayed on the display device 64 (S12). As a result, when the main power is turned off while the paper M remains in the housing 2 when the printer 1 is used last time and the main power is turned on as it is, the user can be notified of this. The user can be prompted to remove the paper. This display is continued until all the inputs from the first position sensor 53 and the second position sensor 54 are turned off. If all of the inputs are turned off (S11: NO), it is determined whether maintenance of the head 8 is necessary (S13). If unnecessary (S13: NO), the process returns to the main process. If necessary (S13: YES), the maintenance process (S4) is executed, and the process returns to the main process after the maintenance process ends.

  Returning to FIG. 5, when the initial process (S1) is completed, it is determined whether there is a print command (S2). If there is no print command (S2: NO), it is determined whether maintenance of the head 8 is necessary (S3), and if it is not necessary (S3: NO), the process returns to step S2. If necessary (S3: YES), the maintenance process (S4) is executed, and the process returns to step S2 after the maintenance process (S4) is completed. After the main power is turned on and the initial process (S1) is completed, this procedure is repeated to wait for a print command. If there is a print command (S2: YES), an image forming process (S5) for forming an image on the paper M stored in the paper feed tray 11 is started. Here, a description will be given assuming that a sufficient amount of paper M is stored in advance in the paper feed tray 11.

  As shown in FIG. 7, in the image forming process (S5), first, image data is read from the PC 65 or the like (S51), and the paper width is based on the input from the paper width sensor 66 or the input operation on the PC 65 or the operation panel 4. Is determined (S52), and ink discharge data and process liquid discharge data (hereinafter, these may be collectively referred to as “liquid discharge data”) are created. Then, a transport / discharge process (S100) for discharging the liquid while transporting the paper M is started.

(Transport / Discharge processing)
8 and 9 are flowcharts showing a part of the procedure of the transport / discharge process (S100) shown in FIG. FIG. 8 generally shows the procedure from the start of the transport / discharge process to the determination of the discharge timing of the processing liquid, and FIG. 9 generally shows the procedure from the determination of the discharge timing of the processing liquid to the end of the transport / discharge process. Show.

  As shown in FIG. 8, in the transport / discharge process (S100), first, the paper feed motor 62 and the transport motor 63 are driven, the paper M in the paper feed tray 11 is fed, and the transport of the paper M is started. (S101). Then, it is determined whether or not a predetermined time T1 has elapsed since this conveyance start time (S102). If the predetermined time T1 has not elapsed (S102: NO), it is determined whether or not the input from the second position sensor 54 has been switched from OFF to ON (S103). Since there is no sheet M in the transport path 6 at the start of transport, the input from the second position sensor 54 is off. If the input remains off (S103: NO), the process returns to step S102. The predetermined time T1 is set to a time slightly longer than the estimated time required to transport from the starting point of the transport path 6 (that is, the lower end of the transport guide 21) to the second predetermined position. The estimated time can be calculated based on the control target transport speed V controlled by the paper feed transport control unit 73 and the distance between these two positions.

  If the input from the second position sensor 54 remains off even after the predetermined time T1 has elapsed, the paper M has jammed undesirably in the upstream portion 6a of the transport path 6 or the transport roller pair 33, and the paper There is a high probability that the tip of M could not reach the second predetermined position. Therefore, when the predetermined time T1 has passed with the input from the second position sensor 54 turned off (S102: YES), information indicating that the conveyance is stopped and the paper M is jammed on the display device 64 is present. It is displayed (S104). The display may be added with information specifying that the jam occurrence location is in the vicinity of the upstream portion 6a or the conveyance roller pair 33. Thereby, it is possible to prompt the user to quickly perform the operation of removing the paper.

  Next, it is determined whether or not the user has removed the paper M, such as opening the housing 2 (S105), and the display is continued while the removal work is not being performed (S105: NO). The If the removal operation of the sheet M is performed (S105: YES), the conveyance of the sheet M is started again (S101). The presence / absence of the removal work is determined based on a sensor (not shown) for detecting that the housing 2 is opened, a sensor (not shown) for detecting that the housing 2 is closed, and the first position sensor 53. The determination can be made based on the input from the second position sensor 54.

  If the input from the second position sensor 54 is switched from OFF to ON before the predetermined time T1 elapses (S103: YES), as described above, the processing liquid is discharged from the processing liquid head 8b on the basis of this switching time. The timing to perform is determined (S106). When the discharge timing is determined, the processing liquid is discharged toward the recording surface from the processing liquid head 8b at the determined timing.

  As shown in FIG. 9, after it is determined that the input from the first position sensor 53 has been switched from OFF to ON, it is determined whether or not a predetermined time T2 has elapsed since the switching (S107). If the predetermined time T2 has not elapsed (S107: NO), it is determined whether one of the inputs from the pair of first position sensors 53a, 53b has been switched from OFF to ON (S108). Since there is no sheet M on the transport path 6 at the start of transport, the input from the first position sensors 53a and 53b is off. Thus, if both inputs remain off (S108: NO), the process returns to step S107. Here, the predetermined time T2 is set to a time slightly longer than the estimated time required for the paper M to be conveyed from the second predetermined position to the first predetermined position. The estimated time can also be calculated based on the conveyance speed V and the distance between these two positions.

  Here, the transport mechanism 7 according to the present embodiment has a configuration in which only the extension roller pair 34 or the transport roller pair 35 exists between the first predetermined position and the second predetermined position, and there is no roller pair having a spur roller. It has become. For this reason, if both the inputs from the first position sensors 53a and 53b remain off even after the predetermined time T2 has elapsed, the jamming of the paper M has occurred undesirably at these roller pairs 34 and 35. There is a high probability that the tip of M could not reach the first predetermined position. Therefore, when the predetermined time T2 has passed with both inputs from the first position sensors 53a and 53b being off (S107: YES), the conveyance is stopped and the processing liquid head 8b stops discharging the processing liquid. In addition, information indicating that the paper M is jammed is displayed on the display device 64 (S109). In particular, when the predetermined time T2 has elapsed while the input of the second position sensor 54 has been switched from on to off, it is highly likely that the paper pair M has jammed in the roller pairs 34 and 35 (paper M The first specified position has not been reached even though the paper is being transported), so the display identifies that the location of the jam is around the stretch roller pair 34 or the transport roller pair 35 Information may be added. Accordingly, it is possible to prompt the user to quickly perform the operation of removing the paper M.

  Next, it is determined whether or not the user has removed the paper M (S110), and the display is continued while the removal work is not being performed (S110: NO). If the removal operation of the sheet M is performed (S110: YES), the conveyance of the sheet M is started again (S101).

  If one of the inputs from the first position sensor 53 is switched from OFF to ON before the predetermined time T2 has elapsed (S108: YES), it is determined whether or not the predetermined time T3 has elapsed since this switching. (S111). The predetermined time T3 is set to a minute time. If the predetermined time T3 has not elapsed (S111: NO), it is determined whether or not both the inputs from the first position sensors 53a and 53b have been switched from OFF to ON (S112). If the other input remains off (S112: NO), the process returns to step S111.

  If one of the inputs is on but the other input is off even after the predetermined time T3 has elapsed, the upper surface of the platen 23c with the center line CM of the paper M deviating from the reference line R undesirably. The probability that it has been transported up to is high. If ink is ejected at such a time, the ejected ink may not land properly on the recording surface of the paper M, and in some cases, the ink may protrude from the paper M and land on the platen 23c. Therefore, when the predetermined time T3 has passed with the other input turned off (S111: YES), the conveyance is stopped, the processing liquid is stopped from being discharged from the processing liquid head 8b, and the sheet M is displayed on the display device 64. Is displayed on the conveyance path 6 (S113). At this time, since it is clear that the leading edge of the sheet M is located near the first predetermined position, information indicating that the sheet M is jammed around the transport roller pair 35 is added to the display. Also good. As a result, the user can quickly remove the paper M. Further, it is possible to prevent the components in the housing 2 including the platen 23c from being contaminated with liquid.

  Next, it is determined whether or not the user has removed the paper M (S114), and the display is continued while the removal work is not being performed (S114: NO). If the removal operation of the sheet M is performed (S114: YES), the conveyance of the sheet M is started again (S101).

  If both inputs from the first position sensors 53a and 53b are switched from OFF to ON before the predetermined time T3 elapses (S112: YES), this switching time or one input is switched from OFF to ON As described above, the timing for ejecting the corresponding ink from each recording head 8a is determined (S115). When the ejection timing is determined, ink is ejected from the recording heads 8a toward the recording surface at the determined timing.

  Then, it is determined whether there is still a page on which an image is to be formed (S116). If there is such a page (S116: YES), conveyance of the next sheet M to start printing is started. (S101). If there is no such page (S116: NO), after the paper M is transported to the paper discharge unit 3, the transport / discharge process and the image forming process are terminated, and the process returns to the main process.

  In this way, by monitoring the inputs from the first position sensor 53 and the second position sensor 54, when the sheet M remains on the transport path 6 when the main power source is turned on or when an image is formed. It is possible to determine whether or not the paper M is jammed and whether or not the paper M is deviated from the reference line R when an image is formed.

  In addition, in step S107 shown in FIG. 9, the time when the predetermined time T2 is counted may be changed to the time when the input from the second position sensor 54 is switched from on to off. That is, it may be determined whether or not the predetermined time T2 has elapsed from the time when the entire sheet M has passed the second predetermined position.

  Further, the procedure of the process shown in FIG. 9 may be changed so that the process is executed such that the predetermined time T3 becomes zero. In this case, the determination process of S111 is deleted. If YES in S108, the process proceeds to S112. If NO in S112, the process proceeds to S113.

  Further, in order to ensure that the input from the first position sensor 53 and the second position sensor 54 is OFF at the time when the paper M is fed and transported, in the transport / discharge process S100, the process proceeds to step S101. Prior to the initial processing S1, steps S11 and S12 may be executed to determine whether or not the sheet M remains in the housing 2.

[Second Embodiment]
FIG. 10 is a diagram illustrating the periphery of the straight line portion 6b of the conveyance path 6 of the printer 101 according to the second embodiment of the present invention when viewed in the width direction. This embodiment is different from the first embodiment in that the first position sensor is a contact switch type.

  As shown in FIG. 10, the first position sensor 153 according to the present embodiment is configured in the same manner as the second position sensor according to the first embodiment. That is, the first position sensor 153 includes a switch 155 built in the platen 23c and an operation piece 156 for operating the switch 155. The operation piece 156 is provided so as to be swingable around a support shaft extending in the width direction in the platen 23c. A slit 157 is formed through the platen 23c in the vicinity of the first predetermined position, and the operation piece 156 has a protruding position that protrudes upward from the upper surface of the platen 23c through the slit 157 by a biasing member such as a torsion coil spring. Be energized. When the sheet M covers the slit 157, the operation piece 156 falls down and the switch 155 enters the operation state. In the present embodiment, since the switch 155 is built in the platen 23c, it is possible to satisfactorily prevent the switch 155 from being damaged by the splash of the processing liquid. As a result, the shielding member according to the first embodiment can be omitted. However, a shielding member may be provided in order to achieve the effect of guiding the processing liquid to the duct.

[Third Embodiment]
FIG. 11 is a plan view of the straight portion 6b of the conveyance path 6 of the printer 201 according to the third embodiment of the present invention. This embodiment is different from the first and second embodiments in that a plurality of sensor sets each including a pair of first position sensors are provided. In the present embodiment, each first position sensor 53 is optical as in the first embodiment, but may be switched as in the second embodiment.

  As shown in FIG. 11, in this embodiment, two sets of sensors each including two pairs of first position sensors are provided. The first pair of first position sensors 53A (53a, 53b) is the same as the pair of first position sensors 53a, 53b according to the first embodiment. That is, when the paper M2 having the shortest dimension in the width direction among the papers M that can be used in the printer 1 is transported, whether or not the pair of edges in the width direction of the paper M2 is positioned at the first predetermined position. It is provided at a position where it can be detected. Specifically, the pair of first position sensors 53a and 53b is configured such that the sheet M2 having the minimum width conveyed along the straight line portion 6b with the center line CM coincident with the reference line R is positioned at the first predetermined position. The paper M2 is arranged so as to overlap with a pair of edges in the width direction of the paper M2 when viewed in the normal direction of the recording surface of the paper M2 (that is, the vertical direction).

  The second pair of first position sensors 53B (53c and 53d) are also arranged symmetrically with respect to the reference line R. Further, the second pair of first position sensors 53c and 53d are arranged in the width direction of the sheet M1 when the sheet M1 having the longest dimension in the width direction among the sheets M usable in the printer 1 is conveyed. Is provided at a position where it can be detected whether or not the pair of edges are positioned at the first predetermined position. Specifically, the pair of first position sensors 53c and 53d is configured such that the sheet M1 having the maximum width conveyed along the straight line portion 6b with the center line CM coincident with the reference line R is positioned at the first predetermined position. The paper M1 is arranged so as to overlap with a pair of edges in the width direction of the paper M1 when viewed in the normal direction of the recording surface of the paper M1 (that is, the vertical direction).

  As described above, the pair of first position sensors 53A and 53B in each group is provided corresponding to each of the plurality of sheets having different dimensions in the width direction.

  FIG. 12 is a flowchart showing the procedure of the image forming process S5A executed by the printer 1 shown in FIG. The image forming process S5A shown in FIG. 12 is replaced with the one shown in FIG. As shown in FIG. 12, in the image forming process S5A according to the present embodiment, first, similarly to the first embodiment, image data is read (S51), the sheet width is read (S52), and the liquid ejection data. Is created (S53). Next, a set of first position sensors 53 corresponding to the paper width is selected based on the read information on the paper width (S54). After this selection process is performed, a transport / discharge process is executed (S100). In the transport / discharge process (S100), the input from the pair of first position sensors selected in step S54 is monitored, and the processes of steps S108 and S112 (see FIG. 9) are executed.

  When the pair of first position sensors are arranged in accordance with the minimum width sheet, even if the center line of the sheet is deviated from the reference line when the maximum width sheet is conveyed, the first position sensor Both inputs may be on. As in this embodiment, by providing a pair of first position sensors corresponding to a plurality of types of sheets having different widthwise dimensions, it is possible to satisfactorily determine whether the center line of the sheet is deviated from the reference line. Can be detected.

[Fourth Embodiment]
FIG. 13 is a plan view of the straight portion 6b of the conveyance path 6 of the printer 301 according to the fourth embodiment of the present invention. The present embodiment is different from the first to third embodiments in that the first position sensor 53 is single. Although the first position sensor 53 according to the present embodiment is an optical type as in the first embodiment, it may be a switch type as in the second embodiment.

  As shown in FIG. 13, the first position sensor 53 according to the fourth embodiment is in a state where one is deleted from the pair of first position sensors according to the first embodiment and the other is left. In other words, the single first position sensor 53 is configured such that when the sheet M2 having the shortest dimension in the width direction among the sheets M usable in the printer 1 is conveyed, one edge in the width direction of the sheet M2 is conveyed. It is provided in the position which can detect whether a part is located in the 1st predetermined position. Specifically, when the sheet M2 having the minimum width conveyed along the straight line portion 6b with the center line CM coincident with the reference line R is positioned at the first predetermined position, the first position sensor 53 When viewed in the normal direction of the recording surface of M2 (that is, in the vertical direction), it is arranged so as to overlap with one edge portion in the width direction of the paper M2. As a result, it is possible to satisfactorily determine whether or not the leading edge of the paper has reached the first predetermined position regardless of the widthwise dimension of the conveyed paper, while suppressing the sensor from being contaminated by the splash of the processing liquid as much as possible. Can be detected.

  FIG. 14 is a flowchart showing a part of the procedure of the conveyance / ejection process executed by the printer 301 shown in FIG. The process shown in FIG. 14 is executed together with the process shown in FIG. 8, and is replaced with the process shown in FIG. As shown in FIG. 14, after the processing liquid discharge timing is determined based on the input from the second position sensor 54, a predetermined time T2 has elapsed since the second position sensor 54 was switched from OFF to ON. It is determined whether or not (S157). The predetermined time T2 is the same as the time T2 used in the determination process of step S107 according to the first embodiment. If the predetermined time T2 has not elapsed (S157: NO), it is determined whether or not the input from the single first position sensor 53 has been switched from OFF to ON (S158). If it remains off (S158: NO), the process returns to step S157.

  When the predetermined time T2 has passed with the input from the first position sensor 53 being OFF (S157: YES), the conveyance is stopped, the discharge of the processing liquid by the processing liquid head 8b is stopped, and the display device 64 has a pair of extension rollers. 34 or the fact that a jam of the paper M has occurred in the vicinity of the conveying roller pair 35 is displayed (S159). Next, it is determined whether or not the user has performed the paper removal operation (S160), and the display is continued while the removal operation is not performed (S160: NO). When the removal operation is performed, the display is stopped and the conveyance of the sheet M is started again (S101).

  If the input from the first position sensor 53 is switched from OFF to ON before the predetermined time T2 elapses (S158: YES), the ejection timing for ejecting ink from the recording head 8a on the basis of the switching time. Is determined (S161). Then, it is determined whether or not there is a next page on which an image is to be formed (S161). If there is such a page (S161: YES), conveyance of the next sheet is started (S101). If there is no such page (S161: NO), the conveyance / discharge process is terminated and the process returns to the main process.

  As described above, even when the first position sensor 53 is single, the ink ejection timing can be determined regardless of the time required for the sheet M to pass through the extension roller pair 34. Can be landed at a desired position on the recording surface.

[Other forms]
The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various design changes can be made as long as they are described in the claims. .

  For example, a single first position sensor 53 may be arranged so as to overlap the reference line R. The second position sensor may be optical. The second position sensor 54 may be disposed anywhere as long as it is downstream of the processing liquid head 8b. When the linear portion 6b is provided as in the above embodiment, the second predetermined position can be suitably brought close to the treatment liquid discharge position, and the accuracy of timing control is increased. In addition, the sensor is more freely arranged in the linear portion 6b formed by the upper surfaces of the platens 23a to 23d than in the upstream portion 6a formed by the conveyance guides 21 and 22. Note that the pair of first position sensors may be arranged so as to overlap the edge of the maximum width sheet.

  Moreover, the conveyance roller pair provided between the extension roller pair and the first position sensor can be omitted as appropriate. Conversely, a pair of conveying rollers may be provided in all or part of three spaces formed between two adjacent recording heads 8a. Further, the lower rollers of the conveying roller pairs 33, 35 to 37 and the extension roller pair 34 and the platens 23a to 23d may be omitted, and an endless conveying belt may be provided instead of the omitted lower rollers and platens. . In this case, the transport mechanism is provided with a roller for rotating the transport belt.

  The present invention is also applicable to a liquid ejecting apparatus that ejects liquid other than ink. Further, the present invention is not limited to a printer, and can be applied to a facsimile, a copier, and the like. The head controller does not drive the actuator unit of the processing liquid head or the actuator unit of each recording head, but discharges the processing liquid or ink from the head by driving the heating element of each recording head. It is good as well. Further, the action of the treatment liquid on the ink includes agglomeration or precipitation of components (pigments and dyes) in the ink due to a chemical reaction by mixing the ink and the treatment liquid.

  The present invention can accurately match the landing position of the first liquid for forming an image with the landing position of the second liquid that acts on the components of the first liquid to aggregate or deposit the first liquid, There is an effect that the disturbance of the image formed on the recording medium can be suppressed, and the invention can be widely applied to an apparatus for forming an image such as an ink jet printer.

M paper (recording medium)
CM Center line R Reference line 1 Inkjet printer (droplet ejection device)
7 Conveying mechanism 8a Recording head (first liquid ejection head)
8b Treatment liquid head (second liquid discharge head)
9. Control part 33, 35-37 Conveyance roller pair 33a, 36a Spur roller 34 Extension roller pair 34a Upper roller (rotating roller)
34b Lower roller (rotating roller)
50 Shielding member 51 Guide plate (guide member)
53 (53a, 53b, 53c, 53d), 153 First position sensor 54 Second position sensor 64 Display device

Claims (13)

A transport mechanism for transporting the recording medium in the transport direction;
A first liquid ejection head that ejects a first liquid for forming an image toward a recording surface of a recording medium that is conveyed;
A second liquid that is disposed upstream of the first liquid discharge head in the transport direction and discharges the second liquid that aggregates or deposits the components of the first liquid toward the recording surface of the transported recording medium. A discharge head;
A rotating roller provided between the first liquid discharge head and the second liquid discharge head, so that an outer peripheral surface is in contact with the recording surface of the recording medium to be conveyed;
A liquid droplet ejection apparatus comprising: a control unit that controls operations of the first liquid ejection head and the second liquid ejection head;
A first position sensor capable of detecting whether or not a recording medium is positioned at a first predetermined position between the rotating roller and the first liquid ejection head;
A second position sensor that detects whether or not the recording medium is positioned at a second predetermined position upstream of the second liquid discharge head in the transport direction;
The controller controls the second liquid discharged from the second liquid discharge head based on a time point when the second position sensor detects that the recording medium to be conveyed has reached the second predetermined position. The discharge timing is determined, and the first liquid discharge head discharges the first liquid discharge head based on the time point when the first position sensor detects that the recording medium to be conveyed has reached the first predetermined position. 1. A liquid droplet ejection apparatus, wherein a liquid ejection timing is determined. A shielding member provided between the position where the rotating roller and the recording medium come into contact with the first liquid discharge head, and the second liquid scattered by the rotation of the rotating roller colliding;
The droplet discharge device according to claim 1, wherein the first position sensor is disposed between the shielding member and the first liquid discharge head.   The droplet discharge device according to claim 2, wherein the first position sensor is disposed so as to be adjacent to an end face on a downstream side in the transport direction of the shielding member. A guide member provided between the shielding member and a position where the rotary roller and the recording medium contact in the transport direction;
4. The droplet according to claim 2, wherein the guide member has an end portion that is close to and opposed to a surface of the rotating roller, and guides a recording medium that rotates along the surface of the rotating roller in the transport direction. Discharge device.   The control unit performs the recording by the first position sensor during a predetermined period from the time when the second position sensor detects that the recording medium to be conveyed has reached or passed the second predetermined position. 5. The droplet discharge device according to claim 1, wherein when it is not detected that the medium has reached the first predetermined position, the first liquid discharge head and the second liquid discharge head are stopped. 6. . Provided with a display device visible to the user,
The control unit performs the recording by the first position sensor during a predetermined period from the time when the second position sensor detects that the recording medium to be conveyed has reached or passed the second predetermined position. The droplet discharge device according to claim 5, wherein when it is not detected that the medium has reached the first predetermined position, the display device displays that a jam of the recording medium has occurred. The transport mechanism is a mechanism for transporting the recording medium by a plurality of spur rollers,
The spur roller is disposed upstream of the second position sensor in the transport direction and downstream of the first position sensor in the transport direction;
The control unit detects that the second position sensor detects the passage of the recording medium at the second predetermined position, and that the recording medium has reached the first predetermined position while the predetermined period has elapsed. The droplet discharge device according to claim 6, wherein when the position is not detected by the one-position sensor, the display device displays that a jam of the recording medium has occurred in the rotating roller.   The control unit monitors an input from at least one of the first position sensor and the second position sensor when the power is switched from off to on, and based on the input, the recording medium has the first predetermined position and The droplet discharge device according to claim 6 or 7, wherein when it is determined that the recording medium is located at at least one of the second predetermined positions, the display device displays that the recording medium remains. The transport mechanism transports the recording medium such that a center line in a width direction of the recording medium is along a virtual reference line extending in the transport direction;
9. The droplet discharge device according to claim 1, wherein the first position sensor is unevenly distributed in a direction perpendicular to the transport direction with respect to the virtual reference line. The transport mechanism is configured to selectively transport a plurality of types of recording media having different dimensions.
Among the recording media that can be transported by the transport mechanism, when the recording medium having the shortest length in the width direction is transported by the transport mechanism, the edge of the recording medium in the width direction can be detected at the first position. The droplet discharge device according to claim 9, wherein a position sensor is arranged. The first position sensors form a pair, and the pair of first position sensors are arranged symmetrically in a direction perpendicular to the transport direction with the virtual reference line as the center,
The pair of first position sensors are arranged in the width direction of the recording medium when viewed in the normal direction of the recording surface of the recording medium passing through the first predetermined position with the center line coincident with the virtual reference line. The droplet discharge device according to claim 9, wherein the droplet discharge device is disposed so as to overlap each of the pair of edges. The transport mechanism is configured to selectively transport a plurality of types of recording media having different dimensions.
The liquid droplet ejection apparatus according to claim 11, wherein a plurality of sets of sensors including the pair of first position sensors are provided corresponding to types of recording media that can be transported by the transport mechanism.   The control unit is configured so that a predetermined period of time elapses from the time when the second position sensor detects that the recording medium to be conveyed has reached or passed the second predetermined position. The first liquid ejection head and the second liquid ejection head are stopped when it is not detected by both of the pair of first position sensors that the recording medium has reached the first predetermined position. Or the droplet discharge apparatus of 12.

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