Patent Description:
In methods in which ink is discharged to a sheet to thereby print an image, there are cases in which the sheet curls due to moisture included in the ink. Accordingly, techniques for heating the sheet to accelerate drying have been proposed. For example, a technique in which drying is accelerated by blowing hot air onto a sheet on which an image has been printed is disclosed in the specification of <CIT>. <CIT> discloses a heat application device which performs drying of a recording surface by applying heat to both the recording surface and a rear surface of a recording sheet. <CIT> further discloses a technique of determining an area drying time from the volume of droplets to be ejected.

The form of heating that is suitable to drying a sheet may differ depending on print conditions. For example, when the sheet conveyance path differs depending on one-side printing and double-side printing, if a sheet is heated in the same section on the conveyance path in both cases, the sheet may be heated unnecessarily or unsuitably. There are cases in which this results in an excess or deficiency in the drying of the sheet, or results in the internal temperature of the apparatus rising unnecessarily or in unnecessary power consumption.

The present invention provides a technique capable of controlling heating of a sheet in accordance with a print condition.

The present invention in its first aspect provides a printing apparatus as specified in claims <NUM> to <NUM>.

The present invention in its second aspect provides a control method as specified in claims <NUM> to <NUM>.

The invention is defined in the claims.

<FIG> is a front surface view of a printing system <NUM> according to an embodiment of the present invention. An arrow X in each figure including <FIG> indicates left and right directions, and an arrow Y indicates the depth direction, and these are orthogonal to each other. An arrow Z indicates a vertical direction.

The printing system <NUM> includes an apparatus main body <NUM> and a post-processing apparatus <NUM>. The apparatus main body <NUM> of the present embodiment is an apparatus that configures a multi-function device, and the apparatus main body <NUM> comprises a copy function, a scanner function, and a printer function. The apparatus main body <NUM> includes a reading apparatus <NUM>, a printing apparatus <NUM>, and a feeding apparatus <NUM>, and an operation unit <NUM> is provided on a front portion of the apparatus main body <NUM>. The operation unit <NUM> is a user input/output interface, and, for example, includes hard keys, a display unit, or a touch panel that receives user input and displays information, and includes an output unit such as a voice generator.

The reading apparatus <NUM> includes an ADF (automatic document feeder) and the reading apparatus <NUM> conveys stacked originals and reads original images. The feeding apparatus <NUM> is an apparatus for feeding a recording medium to the printing apparatus <NUM>. The recording medium, in the case of the present embodiment, is a sheet of paper or film or the like, and in particular is a cut sheet. There are cases where the recording medium is referred to as a sheet. The feeding apparatus <NUM> includes a plurality of a cassette 6a on which sheets are stacked, and a feeding mechanism (not shown) for feeding sheets from the cassette 6a to the printing apparatus <NUM> on a conveyance path RT.

The printing apparatus <NUM> prints an image on a sheet. The printing apparatus <NUM> includes a printing unit <NUM> for printing an image by discharging ink onto a sheet and drying acceleration units <NUM> and <NUM> for accelerating drying of sheets. Details of the printing apparatus <NUM> will be described later.

The post-processing apparatus <NUM> is attached disconnectably to a side of the apparatus main body <NUM> as an optional apparatus, and is a finisher (sheet processing apparatus) for performing sheet post-processing. The post-processing may be, for example, stacking processing in which sheets discharged from the printing apparatus <NUM> are stacked on a tray 3a, sorting processing in which a plurality of sheets discharged from the printing apparatus <NUM> are read in order and aligned in a bundle form, stapling process in which a bundled sheet bundle is bound by a stapler, binding processing, or punch press processing.

<FIG> is an explanatory view illustrating an internal structure of the printing apparatus <NUM>. The printing apparatus <NUM> includes, as frames for supporting internal mechanisms, a bottom wall portion 5a, a top wall portion 5b, a right wall portion 5c, a left wall portion 5d, and a back wall portion 5e. These walls define the internal space of the printing apparatus <NUM>. The internal space of the printing apparatus <NUM> is further separated into a bottom space SP1 and a top space SP2 by a partition wall <NUM>. The space SP1 and the space SP2 are not divided hermetically, and communicate with each other.

The bottom wall portion 5a has an opening 5f through which a sheet that is fed from the feeding apparatus <NUM> passes. The right wall portion 5c has an opening <NUM> through which a sheet that is discharged to the post-processing apparatus <NUM> passes. The left wall portion 5d and the right wall portion 5c may be supported so as to be able to open/close, in the form of a door, for maintenance.

The printing apparatus <NUM> includes a conveyance unit <NUM>, the printing unit <NUM>, the drying acceleration units <NUM> and <NUM>, a straightening unit <NUM>, and an exhaust unit <NUM>.

The conveyance unit <NUM> is a mechanism for conveying a sheet along a conveyance path RT. The conveyance path RT is a path along which sheets are conveyed whose upstream end is the opening 5f and whose downstream end is the opening <NUM> in the case of the present embodiment. The conveyance path RT includes main paths RT1 and RT2, a redirecting path RT3, and an inversion path RT4. The main paths RT1 and RT2 are paths that connect the opening 5f to the opening <NUM> through a midpoint M1, and the main path RT1 is from the opening 5f to the midpoint M1 and the main path RT2 is from the midpoint M1 to the opening <NUM>. The main paths RT1 and RT2 are paths for conveying a sheet leftward and then upward and then rightward, and the sheet passes, in order, the printing unit <NUM>, then the drying acceleration unit <NUM>, then the drying acceleration unit <NUM>, and then the straightening unit <NUM>. In the case of one-side printing, in which only one side of the sheet is printed to, the sheet is conveyed through the main paths RT1 and RT2.

The redirecting path RT3 and the inversion path RT4 are paths that are formed to branch from the main path RT1, and along which a sheet is conveyed after one-side printing in the case of double-side printing in which both sides of the sheet are printed to. The redirecting path RT3, from the midpoint M1, forms a path separate from the main path RT2. Also, the inversion path RT4 is a path from the midpoint M1 to a merging point M2 part way through the main path RT1, and, via the inversion path RT4, the front and back of a sheet are inverted and the sheet is returned once again to the main path RT1.

When the downstream side and the upstream side are referred to in the discussion below, the conveyance direction of the sheet in the conveyance path RT is the reference.

The conveyance unit <NUM> includes a driving mechanism that biases a conveying force in relation to a sheet, and a guide that guides the conveyance of the sheet along the conveyance path RT, and part of that is illustrated in <FIG>. The driving mechanism includes a plurality of a conveyance roller <NUM> which are driven by a driving source such as a motor. A driven roller or spur is arranged to face each of the conveyance rollers <NUM>. A sheet is conveyed so as to be sandwiched between the conveyance roller <NUM> and the driven roller or spur. The spur, in order to maintain the quality of a printed image, is arranged so as to contact the side of the printing surface in a region on the downstream side of the printing unit <NUM>. The guide includes guide members <NUM> to <NUM>. The guide member <NUM> is supported by the left wall portion 5d. Part of the conveyance path RT is formed between the guide member <NUM> and the guide member <NUM>, and part of the path RT1 is formed between the guide member <NUM> and the guide member <NUM>.

The conveyance unit <NUM> includes path switching units <NUM> and <NUM>. The path switching units <NUM> and <NUM> are units for switching the sheet guidance path, and operate by a driving source such as an electromagnetic solenoid, a motor, or the like. The path switching units <NUM> and <NUM> guide the sheet from the main path RT1 to the main path RT2 in the case of one-side printing and, in the case of double-side printing, guide the sheet from the main path RT1 to the redirecting path RT3, and then guide the redirected sheet to the inversion path RT4. <FIG> illustrates path switching states of the path switching units <NUM> and <NUM>. The path switching units <NUM> and <NUM> respectively includes pivotable flaps, and switch the path by positioning of the flaps. The positioning illustrated in solid lines is the positioning in the case of one-side printing, and the positioning illustrated in dashed lines is the positioning in a case of double-side printing. Sheet sensors for detecting the presence or absence of a sheet at respective locations on the conveyance path RT are arranged, and the position of the sheet on the conveyance path RT is identified by sheet sensor detection results.

Returning to <FIG>, the printing unit <NUM> includes a printhead <NUM>, and the printhead <NUM> is an inkjet head for forming images (ink images) by discharging ink onto a sheet. The ink that the printhead <NUM> discharges is contained in a plurality of an ink tank unit T. The ink tank unit T is arranged for each type of ink, the types of ink are, for example, of yellow, magenta, cyan, and black color types.

The printhead <NUM> is arranged for each type of ink. In the case of the present embodiment, each printhead <NUM> is a full-line head arranged to extend in a Y direction, and nozzles are arranged in a range covering a width of an image printing area of a sheet of a maximum size that can be used. A printhead includes a bottom surface that faces the sheet via a minute gap (of several mm, for example), and an ink discharge surface in which a nozzle is open is formed in this bottom surface.

A discharging element is arranged in each nozzle. The discharging element is, for example, an element that causes pressure to form within the nozzle to discharge ink within the nozzle, and a publicly known inkjet head technique can be applied thereto. The discharging element may be, for example, an element that discharges ink by forming air bubbles by causing film boiling to occur in the ink by an electrothermal transducer, an element that discharges ink by an electromechanical transducer, an element that discharges ink using static electricity, or the like. It is possible to perform high-density printing at highspeed by using a discharging element that uses an electrothermal transducer.

Note that the printing unit <NUM> may be a serial printing unit in which printing is performed by the reciprocal movement of a printhead arranged on a carriage in a sheet width direction. Also, the ink to be discharged may be of a single type such as when it is only black. It is possible to select a single ink printing mode and a multiple ink type printing mode as the printing mode of the printing unit <NUM>. The ink may mainly contain a coloring agent (a dye or a pigment) and a solvent component. A water-based material or an oil-based material may be used for the solvent component. As the dye, a water-soluble dye as typified by, for example, a direct dye, an acidic dye, a basic dye, a reactive dye, a food dye, or the like, is preferable, and the dye may be anything that provides an image that satisfies a fixing characteristic, colorability, vividness, stability, lightfastness, or other desired characteristics in combination with the above-described recording medium. A carbon black or the like is preferable for the pigment. A method for using a pigment and a dispersing agent together may be a method using self dispersion pigment or a method of microencapsulation. Also, for the ink, it is possible to add various additives, as necessary, such as a solvent component, a solubilizer, a viscosity modifier, a surfactant, a surface tension adjuster, a pH adjuster, a resistivity adjusting agent, and the like. Also, rather than arranging the printhead <NUM> for every type of ink, nozzles may be arranged for every type of ink on a single printhead.

A sheet, after an image has been printed thereon by the printing unit <NUM>, may expand due to the liquid in the ink and an undulation may form therein. Such a sheet may become the cause of a paper jam in the printing apparatus <NUM> or of a deterioration in stacking performance/alignment performance in the post-processing apparatus <NUM>. By accelerating sheet drying, it is possible to prevent the expansion of the sheet due to liquid in the ink. The printing apparatus <NUM> of the present embodiment comprises a plurality of drying acceleration units <NUM> and <NUM> that are similar in that they heat the sheet, but whose methods of drying the sheet differ. Note that a predetermined moisture is included in the liquid of the ink.

The drying acceleration unit <NUM> is a unit that is arranged on the downstream side of the printing unit <NUM> and that heats the sheet by blowing hot air onto the sheet in a predetermined heating section on the conveyance path RT, thereby accelerating drying of the sheet without contacting the sheet. This structure will be described with reference to <FIG>, <FIG>, and <FIG>.

The drying acceleration unit <NUM> includes a hollow body <NUM> that defines an internal space and a fan <NUM> and a heating element <NUM> arranged within the hollow body <NUM>. The hollow body <NUM> comprises an air intake port 41a on a right side. The wall 41b that forms the left side of the hollow body <NUM> is a guide wall portion that is also used as a sheet conveyance guide, and the wall 41b extends in a Y direction so as to cover the width of the maximum size sheet. A guide wall portion 41b has C-shaped cross-sectional shape (cross section on the X-Z plane), and has a wall surface that faces the guide members <NUM> to <NUM>. Between this wall and the guide members <NUM> to <NUM>, a part of the conveyance path RT is formed and the midpoint M1 is present. A large number of a hot air outlet N that communicates with the internal space of the hollow body <NUM> is formed in the guide wall portion 41b.

The fan <NUM> is an electrically driven fan for which a motor is made to be a driving source, and the fan <NUM> is, for example, a Sirocco fan. The fan <NUM> introduces air into the hollow body <NUM> from the intake port 41a. The air pressure within the hollow body <NUM> increases due to the introduced air, and the air within the hollow body <NUM> is blown out of the hollow body <NUM> from the outlet N. There may be one fan <NUM> or there may be a plurality of the fan <NUM> arranged adjacently in a Y direction.

The heating element <NUM> heats the air introduced into the hollow body <NUM> from the intake port 41a by the fan <NUM>. In the case of the present embodiment, the heating element <NUM> is a rod-like heating element such as an infrared light lamp heater or the like, and the heating element <NUM> extends in the Y direction. Also, a plurality of the heating element <NUM> are arranged in a Z direction. The plurality of the heating element <NUM> are arranged between the fan <NUM> and the intake port 41a, and the air introduced within the hollow body <NUM> from the intake port 41a is heated when passing through the heating element <NUM>. A temperature sensor <NUM> is provided in the drying acceleration unit <NUM>, and driving of the heating element <NUM> is controlled according to a result of detection by the temperature sensor <NUM>.

By such a configuration, the drying acceleration unit <NUM> blows hot air from the outlets N whose air flow is indicated by the arrows in <FIG>. By this, the sheet that passes through the conveyance path RT is heated to promote evaporation of the liquid included in the ink image on the sheet, and thereby drying of the sheet can be accelerated.

In the drying acceleration unit <NUM>, a shutter unit <NUM> that changes the outlets N that blow out hot air is arranged. It is possible to change the heating section on the conveyance path by changing the outlets N that blow out hot air.

<FIG> is an explanatory view for the heating section. In the example of the figure, a heating section R1 and a heating section R2 are exemplified. The heating section R2 is all sections in which hot air can be blown out from the drying acceleration unit <NUM>, and the heating section R1 is a part of the heating section R2. Accordingly, the heating section R2 is a section that is longer than the heating section R1. The heating section R2 includes a portion on the downstream side of the main path RT1 (from the starting point for blowing of hot air by the drying acceleration unit <NUM> until the midpoint M1) and a portion on the upstream side of the main path RT2 (the surrounding part of the midpoint M1) and the redirecting path RT3. The heating section R1 includes a portion on the downstream side of the main path RT1 (from the starting point for blowing hot air by the drying acceleration unit <NUM> until the midpoint M1) and the portion on the upstream side of the main path RT2 (the surrounding part of the midpoint M1).

Note that while in the present embodiment it is possible to change between two types of heating section, there may be three or more types of heating sections that it is possible to change between. The three or more types of heating section may have different lengths to each other, and a shorter heating section may be a portion of a larger heating section.

The shutter unit <NUM> includes a shutter <NUM> and a drive unit <NUM> for reciprocally moving the shutter <NUM> in a Y direction. <FIG> is a view that illustrates movement states of the shutter <NUM>, and shows a part of the wall 41b in a direction of an arrow D1 in <FIG>. The shutter <NUM> is arranged on the inner side of the wall 41b, and is a plate-like member having a form that follows the inner surface of the wall 41b. The shutter <NUM> has a size that overlaps only a part of the top side of the wall 41b, and its width (the width in the Y direction) reaches the entirety of the region in which the outlets N are formed on the wall 41b. In <FIG>, a pattern is added to the shutter <NUM> positioned in the background of the wall 41b so that the shutter <NUM> can be easily visually distinguished. The shutter <NUM> has a plurality of holes OP corresponding to the plurality of outlets N provided on the wall 41b. There is no pattern added for the holes OP.

The drive unit <NUM> is a driving mechanism such as a pull solenoid or an electrically-driven cylinder/ball screw mechanism/rack pinion mechanism for which a motor is a driving source, and the drive unit <NUM> causes the shutter <NUM> to slide in the Y direction. In <FIG>, a state STO indicates a state in which the shutter <NUM> is positioned at an open position, and a state STC indicates a state in which the shutter <NUM> is positioned at a closed position. In a case where the shutter <NUM> is position in an open position, the holes OP overlap the respective outlets N, and so the outlets N are in an open state in which hot air can be blown therethrough. The heating section is then R2. In the case where the shutter <NUM> is positioned in the closed position, the respective outlets N do not overlap the holes OP but rather overlap the body portion of the shutter <NUM>, and the outlets N are in a closed state in which the hot air substantially cannot be blown therethrough.

The heating section is then R1. In this fashion, by changing the outlets N through which the hot air is blown, the heating section can be switched between R1 and R2.

The drying acceleration unit <NUM> is arranged on the downstream side of the drying acceleration unit <NUM>, and is a heat fixing device for heating the sheet by contacting the sheet and thereby accelerating the drying. Its structure is described with reference to <FIG>.

The drying acceleration unit <NUM> includes a heating member <NUM> and a roller <NUM>, and these extend in a Y direction so as to cover the width of the sheet of the maximum size. The heating member <NUM> includes a support member <NUM> for supporting a heating element <NUM> which is a heat source. The heating element <NUM> is, for example, a ceramic heater, and extends in a Y direction. The temperature of the heating element <NUM> is detected by a temperature sensor <NUM> as typified by a thermistor, and driving of the heating element <NUM> is controlled based on detection results.

The support member <NUM> supports a film <NUM>. The film <NUM> is configured in a cylindrical shape and extends in a Y direction. The film <NUM> is supported by the support member <NUM> so as to be able to freely rotate around the support member <NUM>, and is interposed between the roller <NUM> and the heating element <NUM>. The film <NUM>, for example, is a single layered film or a multi-layered film whose thickness is <NUM> or more and <NUM> or less. In a case of a single layered film, the material may be PTFE, PFA, or FEP, for example. In the case of a multi-layered film, PTFE, PFA, FEP, or the like, for example, may be coated on a layer of polyimide, polyamide-imide, PEEK, PES, PPS, or the like, or a film of a layered structure to which a coating is applied may be used.

Note that the configuration of the heating member <NUM> is not limited to this structure, and, for example, configuration may be taken such that a structure comprising a heating element such as a halogen heater is comprised within a hollow metal core axis, and an elastic body such as silicone rubber is coated around the core axis.

The roller <NUM> is configured to coat the circumferential surface of the core metal 56a by the elastic body 56b which may be silicone rubber. The roller <NUM> is crimped to the heating member <NUM> with a predetermined pressing force, and a nipping portion is formed by the roller <NUM> and the heating member <NUM>. The roller <NUM> rotates with a motor as its driving source, and the film <NUM> rotates together with the roller <NUM>. By such a configuration, it is possible to heat the sheet while it is being conveyed in the nipping portion, and thereby promote drying of the sheet.

In the present embodiment, the sheet is dried in two stages by the drying acceleration units <NUM> and <NUM>, but configuration may be such that only one of the drying acceleration units is arranged.

The straightening unit <NUM> is a mechanism for straightening the curvature ("curl" here) of the sheet. In the case of the present embodiment, the straightening unit <NUM> includes a large-diameter drive roller <NUM> and a small-diameter driven roller <NUM>. The drive roller <NUM> is a roller in which the circumference of a core metal is coated by an elastic body such as silicone rubber. The driven roller <NUM> is a metal roller. The drive roller <NUM> and the driven roller <NUM> press against each other. When a sheet passes between the drive roller <NUM> and the driven roller <NUM>, pressure is applied to the sheet by these rollers, and it is possible to straighten a curl in the sheet. The straightening unit <NUM> can add a straightening force in a direction of projection, upward, for example, in relation to the sheet. In such a case, it is possible to straighten a sheet having a convex curl downward by the straightening unit <NUM> so that has a more flat shape.

The exhaust unit <NUM> is a unit for discharging air within the printing apparatus <NUM> to the outside of the apparatus. The printing apparatus <NUM> of the present embodiment comprise the drying acceleration units <NUM> and <NUM>, and these increase the temperature within the apparatus. Also, these act to cause moisture in the ink to evaporate. In a case where printing is performed consecutively in relation to a large number of sheets, the humidity level within the apparatus may rise. A high humidity level may cause curving of sheets. Between the drying acceleration unit <NUM> and the opening <NUM>, the sheet conveyance distance is comparably long, and moreover, the sheet is conveyed within the upper space SP2 in which water vapor tends to be retained. There are cases in which sheets are exposed to a high humidity level environment in the space SP2. The humidity level within the apparatus can be lowered by discharging air within the space SP2 to the outside of the apparatus by the exhaust unit <NUM>.

The exhaust unit <NUM> of the present embodiment is a structure that naturally discharges air within the space SP2 by the plurality of exhaust ducts <NUM> to <NUM>. However, configuration may be taken such that the exhaust unit <NUM> forcibly discharges air within the apparatus by a fan or the like. With reference to <FIG> and <FIG>, the structure of the exhaust unit <NUM> will be described. <FIG> is a plan view illustrating the vicinity of the exhaust unit <NUM>, and the top wall portion 5b is omitted from the illustration.

An exhaust duct <NUM> is a tubular member including an extension 71a that extends in a Y direction and an extension 7b that extends from the end on the far side in the Y direction of the extension 71a to the right side in the X direction. The extension 71a extends at a position in the vicinity of the sheet discharge position in the drying acceleration unit <NUM> and below the main path RT2. The extension 71a is an air intake portion in which a plurality of slits for air intake ports are formed on the upper left-side and bottom. From the upper left-side slit, air that was warmed by the drying acceleration unit <NUM>, for example, is introduced, and from the bottom slit, for example, it is possible for hot air blown out from the outlets N of the drying acceleration unit <NUM> to be introduced. The extension 71a is arranged to extend across the back wall portion 5e, and its end on the far side in the Y direction and the extension 7b are positioned outside (the far side in the Y direction) of the space SP2. Note that the extension 71a may be of a form that extends at a position on the top side of the main path RT2.

An exhaust duct <NUM> is a tubular member that includes an extension 72a that extends in the Y direction, a collection unit 72b that extends from the extension 72a to the right side, and an extension 72c that extends from the right end of the collection unit 72b to the far side of the Y direction. The extension 72a extends at a position in the vicinity of the sheet discharge position in the drying acceleration unit <NUM> and above the main path RT2. The bottom of the extension 72a opens to form an air intake port, and for example, air warmed by the drying acceleration unit <NUM> and water vapor in the space SP2 is introduced. The extension 72a crosses the top wall portion 5b and protrudes above the top wall portion 5b.

For the collection unit 72b, the extension 72a side in the plan view has a wide triangular shape, and its entirety is positioned above the top wall portion 5b. The collection unit 72b collects air introduced to the extension 72a in the center in the Y direction on the right end. The collected air flows to the extension 72c. The entirety of the extension 72c also is positioned above the top wall portion 5b, and partially warped and extends to the far side of the back wall portion 5e. In the far side of the back wall portion 5e, the extension 7b of the exhaust duct <NUM> is connected to the extension 72c of the exhaust duct <NUM>, and these internal spaces communicate. The extension 72c is connected to an exhaust duct <NUM>.

The exhaust duct <NUM> extends in the X direction and is an exhaust member open to the far side in the Y direction. The opening of the exhaust duct <NUM> faces a cover <NUM> that forms the exterior of the rear side of the apparatus main body <NUM>. A large number of slits (louver) 8a are formed in the cover <NUM>, and the air that has flowed into the exhaust duct <NUM> is discharged to the outside of the apparatus from the rear side of the apparatus main body <NUM> through the slits 8a.

A control system of the apparatus main body <NUM> will be described. <FIG> is a block diagram of a control unit <NUM> of the apparatus main body <NUM>. The control unit <NUM> comprises a processing unit <NUM>, a storage unit <NUM>, a read control unit <NUM>, an image processing unit <NUM>, a head controller <NUM>, an engine control unit <NUM>, and a drying control unit <NUM>. The processing unit <NUM> is a processor as typified by a CPU (central processing unit), and comprehensively controls operation of each unit of the apparatus main body <NUM>. The storage unit <NUM> is a storage device such as a ROM or a RAM, for example. In the storage unit <NUM>, programs for the processing unit <NUM> to execute and fixed data (for example, data related to the type of sheets stored in each cassette 6a) necessary for various operation of the apparatus main body <NUM> are stored. Also, the storage unit <NUM> stores various setting data in a work area for the processing unit <NUM> or a temporary storage region for various received data.

The read control unit <NUM> controls the reading apparatus <NUM>. The image processing unit <NUM> performs image processing for image data that the apparatus main body <NUM> handles. The inputted image data color space (for example, YCbCr) is converted into a standard RGB color space (for example, sRGB). The print data obtained by such image processing is stored in the storage unit <NUM>. The head controller <NUM> performs control for driving the printing unit <NUM> in accordance with print data based on control commands received from the processing unit <NUM>. The engine control unit <NUM> performs sheet conveyance control and the like. The drying control unit <NUM> performs control for driving the drying acceleration units <NUM> and <NUM>. Each of these control units includes a processor such as a CPU, a storage device such as a RAM or a ROM, and an interface for an external device.

An I/O <NUM> is an interface (I/F) for connecting the control unit <NUM> with a host apparatus <NUM> and the post-processing apparatus <NUM>, and is a local I/F or a network I/F. The host apparatus <NUM> is an apparatus that is an image data supply source for causing the printing apparatus <NUM> to perform a printing operation. The host apparatus <NUM> may be a general-purpose or dedicated computer, and may be a dedicated image device such as an image capturing device having an image reader unit, a digital camera, or a photo storage.

The redirecting path RT3 included in the heating section R2 is a path over which sheets are conveyed in the case of double-side printing, and a path over which sheets are not conveyed in the case of one-side printing. Assuming that the heating section of the drying acceleration unit <NUM> is uniformly made to be the heating section R2, in a case where one-side printing over which a sheet is not conveyed to the redirecting path RT3, hot air that does not contribute to the drying of the sheet is blown to the redirecting path RT3. This is a waste (a waste of power consumption) of the heat generated by the heating element <NUM>. Also, in the case of the present embodiment, since the redirecting path RT3 does not communicate with the space SP2, hot air blown to the redirecting path RT3 flows to the space SP2. The hot air that does not contribute (by which heat exchange with the moisture does not occur) to the drying of the sheet causes an unnecessary rise in the temperature of the space SP2. Cases are envisioned where, when the temperature of the space SP2 rises, another sheet that is conveyed via the drying acceleration unit <NUM> towards the straightening unit <NUM> will be heated, and the intended curvature of the another sheet will not be achieved by the straightening unit <NUM>.

Conversely, assuming that the heating section of the drying acceleration unit <NUM> is uniformly made to be the heating section R1, in the case of double-side printing in which a sheet is conveyed to the redirecting path RT3, it is envisioned that there will be cases where drying of the sheet will be insufficient.

Accordingly, in the present embodiment, the heating section is changed depending on one of the sheet print conditions, namely one-side printing or double-side printing. In other words, in the plurality of conveyance paths, the heating section is changed in accordance with the current sheet conveyance path. By this, it is possible to control heating of the sheet in accordance with the print condition, and it is possible to achieve drying of the sheet as intended. <FIG> is a flowchart that illustrates an example of control for changing the heating section. Processing of <FIG> is a process for controlling the drying acceleration unit <NUM> that is executed by the drying control unit <NUM>, for example.

In step S1, it is determined whether a print condition for an image on a sheet that is the current print target is one-side printing or double-side printing. In the case of one-side printing, the processing advances to step S2, and in the case of double-side printing, the processing advances to step S3. In step S2, the drive unit <NUM> is driven, and the shutter <NUM> is positioned at a closed position. The heating section R1 ends up being selected. In step S3, it is determined whether printing of an image on a front surface (hereinafter a first surface), on which an image is printed first among a front/back surfaces of the sheet that is the current target of printing, has completed, and it is the stage in which an image is to be printed on the back surface (hereinafter, second surface).

If it is the stage in which the image is to be printed to the second surface, the processing advances to step S2, and the shutter <NUM> is positioned in the closed position. The heating section R1 becomes selected. If it is not the stage in which the image is to be printed to the second surface, and rather it is the stage in which an image is to be printed to the first surface, the processing advances to step S4. In step S4, the drive unit <NUM> is driven and the shutter <NUM> is thereby positioned in the open position. The heating section R2 becomes selected. The above processing is repeated, and the heating section is changed according to whether it is one-side printing or double-side printing. In the case of the double-side printing, the heating section is also changed according to whether it is the stage is for printing the first surface or it is the stage for printing the second surface.

An example of a printing operation by the printing apparatus <NUM> according to control by the control unit <NUM> will be described with reference to <FIG>. First, with reference to <FIG> and <FIG>, operation in a case where an image is printed on one side of a sheet will be described. In a case of printing an image on one side of a sheet, the path switching units <NUM> and <NUM> are set at the positions for the case of the one-side printing (the positioning illustrated in solid lines in <FIG>). By the processing of <FIG>, the shutter <NUM> is positioned in the closed position and the heating section R1 is set. The heating element <NUM> of the drying acceleration unit <NUM> and the heating element <NUM> of the drying acceleration unit <NUM> may be kept at a temperature that is predetermined in advance.

The state ST1 of <FIG> indicates a state in which a sheet P fed from the feeding apparatus <NUM> is conveyed by the conveyance unit <NUM> on the main path RT1 to the printing unit <NUM>, and printing by the printing unit <NUM> is started. The printing unit <NUM> prints the image by discharging ink to the sheet P as illustrated by the arrow. The sheet P is conveyed towards the drying acceleration unit <NUM>. The drying acceleration unit <NUM> starts operating, and hot air is blown (state ST2 of <FIG>) to the sheet P in the heating section R1. Drying of the sheet P which is wet from the ink is accelerated by the hot air.

The sheet P is further conveyed toward the drying acceleration unit <NUM> on the main path RT2. The drying acceleration unit <NUM> starts operating, and the sheet P is conveyed by the roller <NUM> rotating as illustrated in the state ST3 of <FIG> and the sheet P is heated by the heating member <NUM>. The drying of the sheet P is further accelerated thereby.

The sheet P is further conveyed toward the straightening unit <NUM> on the main path RT2 as illustrated in the state ST4 of <FIG>. The straightening unit <NUM> starts operating, and an curl in the sheet P is straightened and the sheet P is discharged to the post-processing apparatus <NUM> from the opening <NUM>.

Next, with reference to <FIG> and <FIG>, operation in a case where an image is printed on both sides of a sheet will be described. The state ST11 of <FIG> indicates a state in which a sheet P fed from the feeding apparatus <NUM> is conveyed by the conveyance unit <NUM> on the main path RT1 to the printing unit <NUM>, and printing by the printing unit <NUM> is started. The printing unit <NUM> prints the image by discharging ink to a first surface of the sheet P as illustrated by the arrow. The path switching unit <NUM> is set to the position for the case of double-side printing (the positioning illustrated by dashed lines in <FIG>). By the processing of <FIG>, the shutter <NUM> is positioned in the open position and the heating section R2 is set.

The sheet P is conveyed towards the drying acceleration unit <NUM>. The drying acceleration unit <NUM> starts operating, and hot air is blown (state ST12 of <FIG>) to the sheet P in the heating section R2. Drying of the sheet P which is wet from the ink is accelerated by the hot air. By the guidance of the path switching unit <NUM>, the sheet P, rather than being conveyed to the drying acceleration unit <NUM>, is conveyed to the redirecting path RT3. Since the heating section R2 is set, hot air is blown onto the sheet P in the redirecting path RT3. When the trailing edge of the sheet P passes the position of the path switching unit <NUM>, the path switching unit <NUM> is set to the position for double-side printing. Then, the conveyance unit <NUM> conveys (redirecting conveyance) the sheet P on the redirecting path RT3 in the reverse direction.

By guidance of the path switching unit <NUM>, the sheet P is conveyed to the inversion path RT4 as indicated by the state ST13 of <FIG>. Also, the sheet P is returned to the main path RT1 as illustrated by the state ST14 of <FIG>. The path switching unit <NUM> is set to the position (the positioning illustrated by the solid lines in <FIG>) in the case of the one-side printing. The printing unit <NUM> prints the image by discharging ink to a second surface of the sheet P as illustrated by the arrow. The operation after that is the same as in the states ST2 to ST4 of the case of one-side printing.

Regarding the heating and drying in relation to the sheet P, the configuration of the present embodiment is summarized as follows. The drying acceleration unit <NUM> of the present embodiment is a configuration in which the heating member <NUM> (the heating element <NUM>) is arranged on one side of the conveyance path RT of the sheet P, and the heating member <NUM> contacts only one side of the sheet P and heats it. Accordingly, while heat reaches both sides of the sheet P and drying is accelerated, the drying is more accelerated on the one side that the heating member <NUM> contacts directly. In the case of one-side printing, the heating member <NUM> contacts the image printing surface of the sheet P.

In the case of double-side printing, the heating element <NUM> faces the second surface of the sheet P, and the heating member <NUM> contacts only the back surface, and there is no stage in which the heating member <NUM> contacts the first surface of the sheet P. Accordingly, in the case of double-side printing, if the other conditions are the same, drying of the sheet P by the drying acceleration unit <NUM> will be more accelerated for the second surface than the first surface.

Meanwhile, the drying acceleration unit <NUM> of the present embodiment is arranged on one side of the conveyance path RT of the sheet P, and is a configuration in which hot air is blown only on one side of the sheet P. Accordingly, while drying of both sides is accelerated, the drying on the one side that the hot air directly hits is more accelerated. In the case of one-side printing, the hot air is blown on the image printing surface of the sheet P in the heating section R1.

In the case of the double-side printing, in the stage in which an image is printed to the first surface of the sheet P, hot air is blown on the first surface in the heating section R2, and in the stage in which an image is printed on the second surface, hot air is blown on the second surface in the heating section R1.

Regarding the drying in both the drying acceleration units <NUM> and <NUM> in the case of double-side printing, in the drying by the drying acceleration unit <NUM>, drying of the first surface of the sheet P is accelerated more than the second surface by using the length of the heating section. In the drying by the drying acceleration unit <NUM>, the drying of the second surface of the sheet P is accelerated more than the first surface at the point of the contact surface. Accordingly, it is possible to reduce the difference in drying between the front/back surfaces.

In the first embodiment, the difference (conveyance path difference) between one-side printing and double-side printing is given as an example of the print condition upon which the heating section change is based, but the print condition is not limited thereto. For example, may change the heating section depending on the discharge amount of ink onto the sheet P. Specifically, in a case where the ink discharge amount is large and the drying capability should be increased, a longer heating section may be selected, and in the case where the ink discharge amount is smaller, a shorter heating section may be selected. In the example of <FIG>, in the case where it is determined that it is not the stage in which an image is printed to the second surface of the sheet in step S3, the processing does not advance to the step S4 immediately, and further determines whether the ink discharge amount corresponding to the first surface is a threshold or more. If the ink discharge amount is the threshold or more, the processing advances to step S4, and if it is less than the threshold, the processing advances to step S2.

In the first embodiment, the driving condition for the fan <NUM> and the heating element <NUM> of the hot air drying unit <NUM> is not changed even in a case where both the heating sections R1 and R2 have been set, but configuration may be taken to change it. If the driving condition is the same for these, the drying capability per unit area of sheet may be increased for when the heating section R1 is set. Accordingly, in the case where the heating section R1 is set, output of at least one of the fan <NUM> and the heating element <NUM> may be reduced. It is possible to achieve a reduction in power consumption thereby.

Configuration may be taken so as not to continuously heat the heating element <NUM> of the drying acceleration unit <NUM>, and to stop the heating in the time period in which heat-drying of the sheet P not performed by the drying acceleration unit <NUM>. <FIG> is a flowchart that illustrates an example in of control for driving the heating element <NUM>, and processing in <FIG> is executed by the drying control unit <NUM>, for example. To outline the details of the control, the heating element <NUM> starts heating the sheet when it reaches the midpoint M1, and when the sheet passes the drying acceleration unit <NUM>, the heating is stopped. However, in the case of double-side printing, even after the sheet reaches the midpoint M1 immediately after the image is printed to the first surface, the heating is not started; the heating is started when the sheet reaches the midpoint M1 after the image is printed to the second surface. Until the sheet reaches the drying acceleration unit <NUM>, there is a period in which the heating of the heating element <NUM> is stopped, and therefore it is possible to reduce the power consumption and to prevent a rise in the internal temperature of the apparatus.

In step S11, it is determined whether a print condition for an image on a sheet that is the current print target is one-side printing or double-side printing. In the case of one-side printing, the processing advances to step S12, and in the case of double-side printing, the processing advances to step S16. In step S12, it is determined whether sheet reached the midpoint M1. This determination is performed based on the result of detection by the sheet sensor described above. In the case where it is determined that the sheet reached the midpoint M1, the processing advances to step S13, and in a case where it is determined not to have been reached, or when it had already been reached, the processing advances to step S14.

In step S13, the heating element <NUM> is driven and the heating is thereby started. In step S14, it is determined whether a sheet has passed the drying acceleration unit <NUM>. This determination is performed based on the above-described sheet sensor detection results. In the case where the sheet is determined to have passed the drying acceleration unit <NUM>, the processing advances to step S15, and in the case where it is determined to not have passed yet, the processing ends. In step S15, driving of the heating element <NUM> driven in step S14 is stopped, and the heating is ended.

In step S16, printing of the image on the first surface of the sheet in the double-side printing ends and it is determined that whether the inversion of the sheet has ended (whether the sheet has passed the inversion path RT4). This determination is performed based on the result of detection by the sheet sensor described above. In the case where the inversion of the sheet has ended, the processing advances to step S12, and in the case where it has not ended, the processing ends. By this, in the case of double-side printing, an image is printed to the second surface of the sheet, and the heating of the heating element <NUM> is stopped until the midpoint M1 is reached.

In the first embodiment, the shutter unit <NUM> was used to change the heating section, but other methods maybe be used. <FIG> illustrates an example of another configuration of the drying acceleration unit <NUM>. In the drying acceleration unit <NUM> of the figure, a partition wall <NUM> which separates the internal space of the hollow body <NUM> vertically is provided. As configurations corresponding to the fan <NUM> and the heating element <NUM> of the first embodiment, fans 42A and 42B which are driven independently and heating elements 43A and 43B are provided. The fan 42A and the heating element 43A are arranged in the lower space in the internal space of the hollow body <NUM> separated by the partition wall <NUM>, and the fan 42B and the heating element 43B are arranged in the upper space separated by the partition wall <NUM>.

When the heating section R1 is set, the fan 42A and the heating element 43A are driving when drying the sheet, and the fan 42B and the heating element 43B are not driven. When the heating section R2 is set, the fan 42A and the heating element 43A are driven when drying the sheet, and the fan 42B and the heating element 43B are driven.

<FIG> illustrates an example of yet another configuration of the drying acceleration unit <NUM>. The drying acceleration unit <NUM> of the figure is a configuration that correspond to the heating element <NUM> of the first embodiment, and heating elements 43A and 43B which are driven independently are provided. The heating element 43A is arranged in the lower space of the internal space of the hollow body <NUM>, and the heating element 43B is arranged in the upper space. The partition wall <NUM> illustrated in <FIG> is not arranged, and the fan <NUM> is not separated into upper and lower spaces. By driving the fan <NUM>, the air flow generated in the internal space of the hollow body <NUM> becomes a crosscurrent, but it is possible to produce a temperature difference depending on what part in the space it is in accordance with whether the heating elements 43A and 43B are driven. If the configuration is such that the air flow generated in the internal space of the hollow body <NUM> by driving the fan <NUM> becomes closer to a laminar flow, it is possible to more clearly produce this temperature difference.

When the heating section R1 is set, the fan <NUM> and the heating element 43A are driven when drying the sheet, and the heating element 43B is not driven. The hot air is sent from each outlet N and is blown to the redirecting path RT3 as well, but since the heating element 43B is not driven, the temperature of the hot air sent to the redirecting path RT3 is comparably lower. Since the heating element 43B is not driven, it is possible to prevent unnecessary power consumption and a rise in the internal temperature of the apparatus.

When the heating section R2 is set, the fan <NUM> and the heating elements 43A and 43B are driven when drying the sheet. Since the heating element 43B is driven, hot air whose temperature does not differ from other sections is sent to the redirecting path RT3.

Claim 1:
A printing apparatus, comprising:
printing means (<NUM>) arranged to print an image by discharging ink on a printing medium from a nozzle arranged in a nozzle surface facing the printing medium;
conveyance means (<NUM>) arranged to convey a printing medium along a conveyance path (RT) arranged between a cassette (6a) and a tray (3a), a printing medium on which the ink has been discharged by the printing means (<NUM>) being stacked on the cassette (6a), and a printing medium on which the ink has been discharged by the printing means (<NUM>) being stacked on the tray (3a);
first heating means (<NUM>) arranged to heat the printing medium in a first section on the conveyance path (RT) between the printing means (<NUM>) and the tray (3a) by blowing hot air from a plurality of outlets (N); and
characterized by comprising
control means (<NUM>) arranged to control blowing hot air from the plurality of outlets (N) of the first heating means (<NUM>) based on a print condition so as to change a length of the first section.