Patent Description:
In a printing apparatus using a discharge head for discharging an ink from nozzles, cleaning for removing the ink adhering to the discharge head needs to be performed as appropriate. For example, in a cleaning method of <CIT>, an ink adhering to a discharge head is wiped out by bringing a sheet into contact with the discharge head by a wiping roller between a feeding roller and a take-up roller while conveying the sheet in a roll-to-roll manner from the feeding roller to the take-up roller.

To reliably wipe out the ink from the discharge head by such a cleaning method, it is suitable to take up the sheet fed from the feeding roller at a high speed by the take-up roller and sufficiently feed a new sheet to the discharge head. However, the discharge head might be damaged by sliding the sheet at a high speed with respect to the discharge head. Thus, a speed at which the sheet wipes a discharge head, in other words, a sheet conveying speed in a contact part of the sheet and the discharge head, has a proper value. Accordingly, it is considered to compute this conveying speed from a rotation speed of the take-up roller. However, to that end, a roll diameter of the sheet wound on the take-up roller is necessary.

A further prior art document is <CIT>, which discloses a methods and an apparatus for cleaning a nozzle plate of an inkjet print head are provided. A method according to this document includes positioning a cleaning medium proximate the inkjet print head, determining a pressure for an inflatable bladder to apply against the cleaning medium, contacting the cleaning medium with the bladder with the determined pressure, and moving the cleaning medium relative to the inkjet print head so as to clean the inkjet print head. The method also includes purging ink from the inkjet print head prior to the bladder contacting the cleaning medium and pre-jetting ink from the inkjet print head after moving the cleaning medium.

This invention was developed in view of the above problem and has the object to make it possible to obtain a roll diameter of a sheet on a take-up roller for taking up the sheet for wiping out an ink from the discharge head. This object is achieved by the subject matter of claims <NUM> and <NUM>. Further advantageous embodiments of the invention are the subject matter of the dependent claims.

A cleaning unit according to the invention, comprises: a feeding roller on which a sheet cleaning a discharge head which discharges an ink is wound in a rolled manner; a take-up roller on which the sheet fed from the feeding roller is wound in a rolled manner; a take-up motor rotating the take-up roller to take up the sheet fed from the feeding roller on the take-up roller; a wiping roller bringing the sheet being conveyed from the feeding roller to the take-up roller by the take-up motor into contact with the discharge head, a rotation detector detecting a feeding rotation speed, the feeding rotation speed being a rotation speed of the feeding roller; and a controller controlling drive of the take-up motor, wherein the controller includes a computer computing a roll diameter of the sheet taken up in a rolled manner on the take-up roller based on a ratio of a take-up rotation speed and the feeding rotation speed and to compute a rotation speed of the take-up roller necessary to convey the sheet at a target speed based on the roll diameter, the take-up rotation speed being a rotation speed of the take-up roller rotated by the take-up motor.

A roll diameter acquisition method according to the invention, comprises: taking up a sheet, which cleans a discharge head discharging an ink, fed from a feeding roller on which the sheet is wound in a rolled manner by a take-up roller; and computing a roll diameter of the sheet taken up in a rolled manner on the take-up roller based on a ratio of a take-up rotation speed and a feeding rotation speed and computing a rotation speed of the take-up roller necessary to convey the sheet at a target speed based on the roll diameter, the take-up rotation speed being a rotation speed of the take-up roller, the feeding rotation speed being a rotation speed of the feeding roller.

In the thus configured invention (cleaning unit and roll diameter acquisition method), the ratio of the take-up rotation speed, which is the rotation speed of the take-up roller, and the feeding rotation speed, which is the rotation speed of the feeding roller, is used. That is, as described in detail later, the inventor of this application obtained knowledge that the roll diameter of the sheet taken up on the take-up roller was given by a function using the ratio of the take-up rotation speed and the feeding rotation speed as a variable. Accordingly, this roll diameter is computed from the ratio of the take-up rotation speed and the feeding rotation speed. In this way, it is possible to obtain the roll diameter of the sheet on the take-up roller taking up the sheet for wiping out the ink from the discharge head.

As described above, according to the invention, it is possible to obtain a roll diameter of a sheet on a take-up roller for winding the sheet for wiping out an ink from the discharge head.

The above and further objects and novel features of the invention will more fully appear from the following detailed description when the same is read in connection with the accompanying drawing. It is to be expressly understood, however, that the drawing is for purpose of illustration only and is not intended as a definition of the limits of the invention.

<FIG> is a front view schematically showing an example of a printing system provided with a printing apparatus according to the invention. In <FIG> and subsequent figures, a horizontal direction X and a vertical direction Z are shown as appropriate. As shown in <FIG>, the printing system <NUM> includes a printing apparatus <NUM> and a drying apparatus <NUM> arrayed in the horizontal direction X. This printing system <NUM> conveys a printing medium M in the form of a long band in a roll-to-roll manner from a feeding roll <NUM> to a take-up roll <NUM>. Note that a material of the printing medium M is a film of OPP (oriented polypropylene), PET (polyethylene terephthalate) or the like. However, the material of the printing medium M is not limited to the film and may be paper or the like. Such a printing medium M is flexible. Further, out of both surfaces of the printing medium M, a surface on which an image is printed is referred to as a front surface M1 and a surface opposite to the front surface M1 is referred to as a back surface M2 as appropriate.

The printing apparatus <NUM> prints an image on the front surface M1 of the printing medium M by discharging water-based inks to the front surface M1 of the printing medium M being conveyed from the feeding roll <NUM> to the take-up roll <NUM> in an ink-jet method. A detailed configuration of such a printing apparatus <NUM> is described later. The printing medium M having the image printed in this way is conveyed in the horizontal direction X from the printing apparatus <NUM> to the drying apparatus <NUM>.

The drying apparatus <NUM> includes a drying furnace <NUM> and dries the printing medium M carried out from the printing apparatus <NUM> as the printing medium M is conveyed from the feeding roll <NUM> to the take-up roll <NUM>. Two upper-stage blower units 91u arrayed in the horizontal direction X, two middle-stage blower units <NUM> arrayed in the horizontal direction X below these upper-stage blower units 91u and two lower-stage blower units <NUM> arrayed in the horizontal direction X below these middle-stage blower units <NUM> are provided in the drying furnace <NUM>.

The printing medium M carried out through a carry-out port <NUM> of the printing apparatus <NUM> is folded toward the two middle-stage blower units <NUM> by one pair of rollers <NUM> after passing in the horizontal direction X through the two upper-stage blower units 91u. Subsequently, the printing medium M is folded toward the two lower-stage blower units <NUM> by one pair of air turn bars <NUM> after passing in the horizontal direction X through the two middle-stage blower units <NUM>. Further, the printing medium M is carried out to the outside of the drying apparatus <NUM> after passing in the horizontal direction X through the two lower-stage blower units <NUM>.

The upper-stage blower unit 91u includes two blower chambers <NUM> arranged to sandwich the printing medium M passing in the horizontal direction X in the vertical direction Z. Each blower chamber <NUM> includes a plurality of nozzles <NUM> arrayed in the horizontal direction X and injects hot air (gas of <NUM> or higher) from the nozzles <NUM> to the printing medium M. In this way, the printing medium M is dried by the hot air injected from the nozzles <NUM> of these blower chambers <NUM> while passing between the two blower chambers <NUM> provided on upper and lower sides. Further, each of the middle-stage blower units <NUM> and the lower-stage blower units <NUM> also includes two blower chambers <NUM> for sandwiching the printing medium M in the vertical direction Z, similarly to the upper-stage blower units 91u.

By the way, a specific configuration of the upper-stage blower unit 91u is not limited to the one in this example. For example, a plurality of rollers arrayed in the horizontal direction X may be provided instead of the lower blower chamber <NUM>, out of the upper and lower blower chambers <NUM> of the upper-stage blower unit 91u. In such a configuration, the hot air can be injected to the front surface M1 of the printing medium M from the upper blower chamber <NUM> while the back surface M2 of the printing medium M is supported from below by the plurality of rollers.

<FIG> is a front view schematically showing the printing apparatus equipped in the printing system of <FIG>. In <FIG>, one side X1 and another side X2 in the horizontal direction X are shown as appropriate. Here, the one side X1 is a side from the printing apparatus <NUM> toward the drying apparatus <NUM>, and the other side X2 is a side opposite to the one side X1. The printing apparatus <NUM> includes a housing <NUM>, a color printing unit <NUM> arranged in the housing <NUM>, a white printing unit <NUM> arranged above the color printing unit <NUM> in the housing <NUM>, and a conveyor <NUM> for conveying the printing medium M by a plurality of rollers arranged in the housing <NUM>.

The color printing unit <NUM> includes a plurality of (six) head units <NUM> arrayed in a moving direction (direction from the other side X2 toward the one side X1) of the printing medium M above the printing medium M being conveyed by the conveyor <NUM>. The plurality of head units <NUM> include nozzles facing the front surface M1 of the printing medium M passing therebelow from above, and discharge color inks having mutually different colors in the ink-jet method. Here, the color inks mean inks other than that having a white color and include inks of cyan, magenta, yellow, black and the like. In this way, the plurality of head units <NUM> of the color printing unit <NUM> print a color image on the front surface M1 of the printing medium M by discharging the color inks to the front surface M1 of the printing medium M passing therebelow from above.

Further, the white printing unit <NUM> includes a single head unit <NUM> arranged above the printing medium M being conveyed by the conveyor <NUM>. The head unit <NUM> includes nozzles facing the front surface M1 of the printing medium M passing therebelow from above, and discharges a white ink from the nozzles in the ink-jet method. In this way, the head unit <NUM> of the white printing unit <NUM> prints a white image on the front surface M1 of the printing medium M by discharging the white ink to the front surface M1 of the printing medium M passing therebelow from above.

A carry-in port <NUM> is open in a side wall on the other side X2 of the housing <NUM>, whereas a carry-out port <NUM> is open in a side wall on the one side X1 of the housing <NUM>. The conveyor <NUM> conveys the printing medium M from the carry-in port <NUM> to the carry-out port <NUM> by way of the color printing unit <NUM> and the white printing unit <NUM> described above.

This conveyor <NUM> includes a carry-in part <NUM> provided below the color printing unit <NUM>, an ascending conveyor <NUM> provided on the one side X1 of the color printing unit <NUM>, an upper conveyor <NUM> provided above the color printing unit <NUM> and a descending conveyor <NUM> provided on the other side X2 of the color printing unit <NUM>. The carry-in part <NUM> conveys the printing medium M carried in through the carry-in port <NUM> toward the one side X1 by rollers <NUM>, the ascending conveyor <NUM> conveys the printing medium M conveyed by the carry-in part <NUM> upward by rollers <NUM>, the upper conveyor <NUM> conveys the printing medium M conveyed by the ascending conveyor <NUM> toward the other side X2 by rollers <NUM>, and the descending conveyor <NUM> conveys the printing medium M conveyed by the upper conveyor <NUM> downward by rollers <NUM>.

Further, the conveyor <NUM> includes a color conveyor <NUM> for supporting the printing medium M facing the color printing unit <NUM> from below, and the printing medium M passed through the descending conveyor <NUM> enters the color conveyor <NUM>. This color conveyor <NUM> includes a plurality of rollers <NUM> arrayed from the other side X2 to the one side X1 and each roller <NUM> contacts the back surface M2 of the printing medium M from below. In this way, the front surface M1 of the printing medium M supported by the color conveyor <NUM> is facing up and each head unit <NUM> of the color printing unit <NUM> discharges the color ink to this front surface M1 while facing this front surface M1 from above.

Further, the conveyor <NUM> includes rollers <NUM>, <NUM> and <NUM> arranged between the color conveyor <NUM> and the descending conveyor <NUM> in the moving direction of the printing medium M. The roller <NUM> is a drive roller for driving the printing medium M. The rollers <NUM>, <NUM> are driven rollers which rotate, following the printing medium M.

Furthermore, the conveyor <NUM> includes an inverting conveyor <NUM> for vertically inverting the printing medium M conveyed to the one side X1 from the color conveyor <NUM> twice. This inverting conveyor <NUM> includes a plurality of the rollers <NUM> to <NUM> including the drive roller <NUM>, and these rollers <NUM> to <NUM> vertically invert the printing medium M twice while contacting the back surface M2 of the printing medium M. That is, the inverting conveyor <NUM> vertically inverts the front surface M1 and the back surface M2 of the printing medium M by conveying the printing medium M conveyed from the color conveyor <NUM> downward by the rollers <NUM>, <NUM> and further conveying the printing medium M with the moving direction of the printing medium M changed to the one toward the other side X2 by the roller <NUM>. Subsequently, the inverting conveyor <NUM> conveys the printing medium M from the one side X1 to the other side X2 by a plurality of the rollers <NUM> and then conveys the printing medium M upward by the rollers <NUM> to <NUM>. Further, the inverting conveyor <NUM> vertically inverts the front surface M1 and the back surface M2 of the printing medium M again and conveys the printing medium M from the other side X2 to the one side X1 by the roller <NUM> by changing the moving direction of the printing medium M toward the one side X1 by the roller <NUM>.

Further, the conveyor <NUM> includes a white conveyor <NUM> for supporting the printing medium M facing the white printing unit <NUM> from below, and the printing medium M vertically inverted twice by the inverting conveyor <NUM> enters the white conveyor <NUM>. This white conveyor <NUM> includes a roller <NUM> configured to contact the back surface M2 of the printing medium M from below. In this way, the front surface M1 of the printing medium M supported by the white conveyor <NUM> is facing up, and the head unit <NUM> of the white printing unit <NUM> discharges the white ink to this front surface M1 while facing this front surface M1 from above.

Furthermore, the conveyor <NUM> includes a carry-out part <NUM> provided above the upper conveyor <NUM>. The carry-out part <NUM> includes a plurality of rollers <NUM> arrayed from the other side X2 to the one side X1 in the horizontal direction X. This carry-out part <NUM> conveys the printing medium M conveyed by the white conveyor <NUM> to the drying apparatus <NUM> through the carry-out port <NUM> of the housing <NUM> by conveying the printing medium M to the one side X1 by the plurality of rollers <NUM>.

As described above, the color printing unit <NUM> and the white printing unit <NUM> of the printing apparatus <NUM> include the head units <NUM>, <NUM>. Next, these head units <NUM>, <NUM> are described. Note that each head unit <NUM>, <NUM> has a common basic configuration. Accordingly, one head unit <NUM> is described below and the other head units <NUM>, <NUM> are not described.

<FIG> is a diagram schematically showing the bottom surface of the head unit. In <FIG>, a horizontal direction Y orthogonal to the horizontal direction X is shown in addition to the horizontal direction X and the vertical direction Z. As shown in <FIG>, a plurality of discharge heads H for discharging the ink of the same color are arrayed in a row in the horizontal direction Y in the head unit <NUM>. Note that an array mode of the discharge heads H is not limited to an example of <FIG> and the plurality of discharge heads H may be arrayed in a staggered manner.

This discharge head H has a housing Ha and the bottom surface of the housing Ha is an ink discharging flat surface Hb facing the front surface M1 of the printing medium M. A plurality of nozzles Hc are arrayed in the horizontal direction Y and open in this ink discharging flat surface Hb. Note that, although the plurality of nozzles Hc are arrayed in a row in the example of <FIG>, an array mode of these nozzles Hc is not limited to this example and the nozzles Hc may be, for example, arrayed in a staggered manner in the horizontal direction Y. Each nozzle Hc provided in the ink discharging flat surface Hb in this way discharges the ink toward the front surface M1 of the printing medium M. Note that the ink can be discharged by various ink-jet techniques such as a piezo technique or thermal technique.

Further, the printing apparatus <NUM> includes a maintenance unit <NUM> (<FIG>) for performing maintenance for the respective discharge heads H. Next, the maintenance unit <NUM> is described using <FIG>. Note that the maintenance unit <NUM> is arranged for each of the plurality of head units <NUM>, <NUM> and the configuration and operation of the maintenance unit <NUM> provided in each head unit <NUM>, <NUM> are common. Thus, one maintenance unit <NUM> is described here.

<FIG> is a diagram schematically showing the configuration and operation of the maintenance unit. As shown in <FIG>, the printing apparatus <NUM> includes the maintenance unit <NUM> and a linear motion mechanism <NUM> for driving the maintenance unit <NUM> in the horizontal direction Y. This linear motion mechanism <NUM> includes, for example, a ball screw or a linear motor and moves the maintenance unit <NUM> between a facing position La and a retracted position Lb provided at an interval from the facing position La in the horizontal direction Y. The maintenance unit <NUM> located at the facing position La faces the plurality of discharge heads H, whereas the maintenance unit <NUM> located at the retracted position Lb does not face the plurality of discharge heads H. Further, to avoid interference with the maintenance unit <NUM>, the plurality of discharge heads H can be integrally raised and lowered. Particularly, the plurality of discharge heads H are located at any one of a printing height Hl, a cap height Hm higher than the printing height Hl and a retracted height Hh higher than the cap height Hm.

This maintenance unit <NUM> includes a cap <NUM> for covering the discharge heads H from below and a cleaning unit <NUM> to be described in detail later. This cleaning unit <NUM> performs cleaning to wipe out the ink adhering to the ink discharging flat surfaces Hb of the discharge heads H with a sheet S. A fabric in form of a long band is used as the sheet S. However, a material of the sheet S is not limited to the fabric and may be, for example, paper. Next, an execution procedure of cleaning using the sheet S is described through Steps S101 to S105 of <FIG>.

In a field of Step S101 of <FIG>, a state is shown in which a printing operation is performed to print an image on the printing medium M by discharging the ink from the nozzles Hc of the discharge heads H. In Step S101, the discharge heads H are located at the printing height Hl and the maintenance unit <NUM> is located at the retracted position Lb. When this printing operation is finished, the plurality of discharge heads H are raised from the printing height H1 to the retracted height Hh (Step S102). In this way, a space into which the maintenance unit <NUM> enters is formed below the respective discharge heads H.

In Step S103, the maintenance unit <NUM> starts to move from the retracted position Lb to the facing position La. This causes the cleaning unit <NUM> to move at a speed V6 in the horizontal direction Y while causing the sheet S to contact the ink discharging flat surfaces Hb of the discharge heads H. In this way, the ink adhering to the ink discharging flat surfaces Hb is wiped out with the sheet S (cleaning).

When the maintenance unit <NUM> reaches the facing position La (Step S104), the cap <NUM> of the maintenance unit <NUM> faces the plurality of discharge heads H from below. On the other hand, the cleaning unit <NUM> stops at a position projecting from the plurality of discharge heads H in the horizontal direction Y. Subsequently, the plurality of discharge heads H are lowered from the retracted height Hh to the cap height Hm (Step S105). In this way, each discharge head H is covered from below by the cap <NUM> (capping).

<FIG> is a partial side view schematically showing the configuration of the cleaning unit in a side view, and <FIG> is a partial section schematically showing the configuration of the cleaning unit in a plan view. In <FIG>, members hidden behind members in front are shown by broken lines. Note that the cleaning unit <NUM> is slightly inclined according to the posture of the head unit <NUM> or head unit <NUM> to be cleaned. However, since the inclination of the cleaning unit <NUM> is slight, inclination is not expressed in these figures.

The cleaning unit <NUM> includes a housing <NUM>. This housing <NUM> includes a separation wall <NUM> extending in the horizontal direction Y and orthogonal to the horizontal direction X. The separation wall <NUM> has a rectangular shape in a side view from the horizontal direction X. Further, the housing <NUM> includes a pair of a separation wall <NUM> and a separation wall <NUM> arrayed at an interval in the horizontal direction Y. Each of the separation walls <NUM>, <NUM> extends in the horizontal direction X toward the inside (upper side of <FIG>) of the housing <NUM> from the separation wall <NUM> and is orthogonal to the horizontal direction Y. In this way, the separation wall <NUM> has a central part 601a provided between the separation walls <NUM> and <NUM> in the horizontal direction Y and end parts 601b, 601c provided on both sides of the central part 601a. In the horizontal direction Y, the end part 601b projects toward a side opposite to the central part 601a from the separation wall <NUM>, and the end part 601c projects toward a side opposite to the central part 601a from the separation wall <NUM>.

In this way, a cleaning region Ac (inside region of the housing <NUM>) divided in three directions by the central part 601a of the separation wall <NUM> and the separation walls <NUM>, <NUM>, a front region Af on a side opposite to the cleaning region Ac with respect to the separation wall <NUM>, a side region Asl divided in two directions by the end part 601b of the separation wall <NUM> and the separation wall <NUM> and a side region Asr divided in two directions by the end part 601c of the separation wall <NUM> and the separation wall <NUM> are provided. That is, in a plan view, the cleaning region Ac and the front region Af are divided by the central part 601a of the separation wall <NUM>, the cleaning region Ac and the side region Asl are divided by the separation wall <NUM>, and the cleaning region Ac and the side region Asr are divided by the separation wall <NUM>.

Further, the cleaning unit <NUM> includes a feeding roller <NUM> and a take-up roller <NUM> which convey the sheet S in the cleaning region Ac. The feeding roller <NUM> and the take-up roller <NUM> are arranged at an interval in the horizontal direction Y between the separation walls <NUM> and <NUM>, the feeding roller <NUM> is arranged closer to the separation wall <NUM>, out of the separation walls <NUM>, <NUM>, and the take-up roller <NUM> is arranged closer to the separation wall <NUM>, out of the separation walls <NUM>, <NUM>. Particularly, the cleaning unit <NUM> continuously supplies the new sheet S to the ink discharging flat surfaces Hb of the discharge heads H by conveying the sheet S in a roll-to-roll manner from the feeding roller <NUM> to the take-up roller <NUM> during the execution of the above cleaning (Step S103).

The feeding roller <NUM> is arranged in parallel to the horizontal direction X and supported rotatably about a center of rotation parallel to the horizontal direction X by the separation wall <NUM>. The feeding roller <NUM> includes a cylindrical roller body <NUM> and a cylindrical rotary shaft <NUM> provided coaxially with the roller body <NUM>. A diameter of the rotary shaft <NUM> is shorter than that of the roller body <NUM>, and the rotary shaft <NUM> projects in the horizontal direction X from the roller body <NUM>. The roller body <NUM> is arranged in the cleaning region Ac, and the rotary shaft <NUM> penetrates through the central part 601a of the separation wall <NUM> from the cleaning region Ac to the front region Af via a through hole provided in the separation wall <NUM>. In contrast, a pair of bearings <NUM> are mounted on the central part 601a of the separation wall <NUM>. One <NUM> of the pair of bearings <NUM> rotatably supports the rotary shaft <NUM> in the through hole of the separation wall <NUM>, and the other bearing <NUM> is arranged in the front region Af and rotatably supports an end part of the rotary shaft <NUM> projecting into the front region Af from the separation wall <NUM>. In this way, the rotary shaft <NUM> is rotatably supported by the pair of bearings <NUM>.

The take-up roller <NUM> is arranged in parallel to the horizontal direction X and supported rotatably about a center of rotation parallel to the horizontal direction X by the separation wall <NUM>. The take-up roller <NUM> includes a cylindrical roller body <NUM> and a cylindrical rotary shaft <NUM> provided coaxially with the roller body <NUM>. A diameter of the rotary shaft <NUM> is shorter than that of the roller body <NUM>, and the rotary shaft <NUM> projects in the horizontal direction X from the roller body <NUM>. The roller body <NUM> is arranged in the cleaning region Ac, and the rotary shaft <NUM> penetrates through the central part 601a of the separation wall <NUM> from the cleaning region Ac to the front region Af via a through hole provided in the separation wall <NUM>. In contrast, a pair of bearings <NUM> are mounted on the central part 601a of the separation wall <NUM>. One <NUM> of the pair of bearings <NUM> rotatably supports the rotary shaft <NUM> in the through hole of the separation wall <NUM>, and the other bearing <NUM> is arranged in the front region Af and rotatably supports an end part of the rotary shaft <NUM> projecting into the front region Af from the separation wall <NUM>. In this way, the rotary shaft <NUM> is rotatably supported by the pair of bearings <NUM>.

One end of the sheet S is wound in a rolled manner on the roller body <NUM> of the feeding roller <NUM>, and the other end of the sheet S is wound in a rolled manner on the roller body <NUM> of the take-up roller <NUM>. That is, a feeding roll Ru constituted by the rolled sheet S is supported on the feeding roller <NUM>, and a take-up roll Rr constituted by the rolled sheet S is supported on the take-up roller <NUM>. These feeding roll Ru and the take-up roll Rr are arranged in the cleaning region Ac. The sheet S has a front surface for wiping out the ink and a back surface opposite to the front surface, the feeding roll Ru is so wound that the front surface of the sheet S is located outside, and the take-up roll Ru is so wound that the front surface of the sheet S is located inside.

Further, the cleaning unit <NUM> includes a wiping roller <NUM> and a winding roller <NUM> and a winding roller <NUM> arranged in the cleaning region Ac. The wiping roller <NUM> is arranged in parallel to the horizontal direction X between the feeding roller <NUM> and the take-up roller <NUM>, the winding roller <NUM> is arranged in parallel to the horizontal direction X between the feeding roller <NUM> and the wiping roller <NUM>, and the winding roller <NUM> is arranged in parallel to the horizontal direction X between the wiping roller <NUM> and the take-up roller <NUM>. The housing <NUM> includes a support plate <NUM> provided for these rollers <NUM>, <NUM> and <NUM>, and the separation wall <NUM> and the support plate <NUM> rotatably support the rollers <NUM>, <NUM> and <NUM> while sandwiching the rollers <NUM>, <NUM> and <NUM> in the horizontal direction X. That is, the roller <NUM>, <NUM>, <NUM> is rotatable about a center of rotation parallel to the horizontal direction X.

The winding roller <NUM> contacts the front surface of the sheet S fed from the feeding roll Ru of the feeding roller <NUM> from above, and the winding roller <NUM> contacts the front surface of the sheet S to be taken up on the take-up roll Rr of the take-up roller <NUM> from above. On the other hand, the wiping roller <NUM> is arranged above the winding roller <NUM> and the winding roller <NUM> and contacts the back surface of the sheet S conveyed from the winding roller <NUM> to the winding roller <NUM> from below. This wiping roller <NUM> partially projects upward from the separation wall <NUM>. Thus, the sheet S wound on the wiping roller <NUM> projects upward from the separation wall <NUM> and contacts the ink discharging flat surfaces Hb of the discharge heads H. That is, the wiping roller <NUM> functions to wipe out the ink by the front surface of the sheet S by bringing the front surface of the sheet S into contact with the ink discharging flat surfaces Hb of the discharge heads H.

Further, the cleaning unit <NUM> includes a discharge rod <NUM> arranged in the cleaning region Ac. The discharge rod <NUM> is so supported on the separation wall <NUM> and the support plate <NUM> to face the front surface of the sheet S conveyed from the winding roller <NUM> to the wiping roller <NUM> from above. This discharge rod <NUM> discharges a cleaning liquid to the front surface of the sheet S located below. In this way, the cleaning liquid is supplied to the front surface of the sheet S before reaching the wiping roller <NUM>. This cleaning liquid is, for example, constituted by components other than coloring components (pigments, dyes), out of ink components.

Further, the cleaning unit <NUM> includes a rotation detector <NUM> detecting a rotation speed of the feeding roller <NUM>. This rotation detector <NUM> is arranged in the front region Af and mounted on the end part 601b of the separation wall <NUM>. Specifically, the rotation detector <NUM> includes a rotary plate <NUM> (rotary blade) arranged in the front region Af and a rotary shaft <NUM> supporting the rotary plate <NUM>. The rotary shaft <NUM> is provided coaxially with the rotary plate <NUM> and has a cylindrical shape. The rotary shaft <NUM> penetrates through the separation wall <NUM> from the front region Af to the side region Asl via a through hole provided in the end part 601b of the separation wall <NUM>. In contrast, a pair of bearings <NUM> are provided on the end part 601b of the separation wall <NUM>. One <NUM> of the pair of bearings <NUM> rotatably supports the rotary shaft <NUM> in the through hole of the separation wall <NUM>, and the other bearing <NUM> is arranged in the front region Af and rotatably supports an end part of the rotary shaft <NUM> projecting into the front region Af from the separation wall <NUM>. In this way, the rotary shaft <NUM> and the rotary plate <NUM> mounted on the rotary shaft <NUM> are rotatably supported by the pair of bearings <NUM>.

Furthermore, the rotation detector <NUM> includes a photosensor <NUM> arranged in the front region Af and a mounting fitting <NUM> for mounting the photosensor <NUM> on the end part 601b of the separation wall <NUM>. The photosensor <NUM> includes a light emitter Pe and a light receiver Pd. A peripheral edge part of the rotary plate <NUM> is located between the light emitter Pe and the light receiver Pd, the light receiver Pd does not detect light if the light emitted from the light emitter Pe is blocked by the rotary plate <NUM>, and the light receiver Pd detects light if the light emitted from the light emitter Pe passes through the rotary plate <NUM>.

<FIG> is a diagram schematically showing the configuration of the rotary plate, and <FIG> is a partial enlarged view enlargedly showing a part of a range surrounded by a curved of <FIG>. As shown in <FIG>, a plurality of teeth T are arrayed at intervals in a circumferential direction on the peripheral edge part of the rotary plate <NUM>. If light emitted from the light emitter Pe of the photosensor <NUM> is blocked by the tooth T, the light receiver Pd does not detect the light and the photosensor <NUM> outputs an off-signal. On the other hand, if light emitted from the light emitter Pe of the photosensor <NUM> passes through a slit between the teeth T, the light receiver Pd detects the light and the photosensor <NUM> outputs an on-signal. Therefore, the rotation speed of the rotary plate <NUM> can be detected based on a time interval at which the photosensor <NUM> alternately outputs the on-signal and the off-signal.

Particularly, as shown in <FIG>, the plurality of teeth T are so provided that widths of the teeth T periodically change. That is, the teeth T of the width corresponding to an angle θ1 (= <NUM>°), the teeth T of the width corresponding to an angle <NUM> (= <NUM>°) larger than the angle θ1 and the teeth T of the width corresponding to an angle θ3 (= <NUM>°) larger than the angle θ2 are periodically arranged in this order. Accordingly, in <FIG>, the photosensor <NUM> detects the teeth T in the order of the angles θ1, θ2 and θ3 if the rotary plate <NUM> rotates clockwise, and the photosensor <NUM> detects the teeth T in the order of the angles θ3, θ2 and θ1 if the rotary plate <NUM> rotates counterclockwise. Therefore, the rotation direction of the rotary plate <NUM> can be detected based on changes of the time intervals at which the photosensor <NUM> outputs the off-signals.

Referring back to <FIG> and <FIG>, it is further described. As just described, the rotation detector <NUM> has a mechanism for detecting the rotation speed of the rotary plate <NUM> by the photosensor <NUM>. Further, in the rotation detector <NUM>, a one-way clutch or torque limiter is mounted on the rotary shaft <NUM>, and the rotary shaft <NUM> is configured to rotate if a torque of a predetermined value or more is applied.

Further, the cleaning unit <NUM> includes a rotation transmitter <NUM> arranged in the front region Af, and the rotation of the feeding roller <NUM> is transmitted to the rotation detector <NUM> by this rotation transmitter <NUM>. This rotation transmitter <NUM> includes a pulley <NUM> mounted on the rotary shaft <NUM> of the feeding roller <NUM>, a pulley <NUM> mounted on the rotary shaft <NUM> of the rotary plate <NUM>, an endless timing belt <NUM> mounted between the pulleys <NUM> and <NUM>, and a winding roller <NUM> configured to contact the timing belt <NUM> from above. Accordingly, the rotation of the feeding roller <NUM> is transmitted to the rotary plate <NUM> by the pulley <NUM>, the timing belt <NUM> and the pulley <NUM>. Thus, a rotation speed and a rotation direction of the feeding roller <NUM> can be detected based on outputs (on-signals and off-signals) of the photosensor <NUM>. Note that the pulleys <NUM>, <NUM> have the same diameter and the rotation speed of the feeding roller <NUM> and that of the rotary plate <NUM> of the rotation detector <NUM> are equal.

Furthermore, the cleaning unit <NUM> includes a take-up motor <NUM> rotating the take-up roller <NUM>. The take-up motor <NUM> includes a motor body <NUM> and a rotary shaft <NUM> projecting in the horizontal direction X from the motor body <NUM>. The motor body <NUM> is arranged in the side region Asr, whereas the rotary shaft <NUM> projects from the side region Asr to the front region Sf via a through hole provided in the end part 601c of the separation wall <NUM>. This rotary shaft <NUM> rotates about a center of rotation parallel to the horizontal direction X by a rotational drive force output by the motor body <NUM>.

Further, the cleaning unit <NUM> includes a rotation transmitter <NUM> arranged in the front region Af, and the rotation of the rotary shaft <NUM> of the motor body <NUM> is transmitted to the take-up roller <NUM> by this rotation transmitter <NUM>. This rotation transmitter <NUM> includes a pulley <NUM> mounted on the rotary shaft <NUM> of the take-up motor <NUM>, a pulley <NUM> mounted on the rotary shaft <NUM> of the take-up roller <NUM>, an endless timing belt <NUM> mounted between the pulleys <NUM> and <NUM>, and a winding roller <NUM> configured to contact the timing belt <NUM> from above. Accordingly, the rotation of the rotary shaft <NUM> of the take-up motor <NUM> is transmitted to the take-up roller <NUM> by the pulley <NUM>, the timing belt <NUM> and the pulley <NUM>. Thus, the take-up motor <NUM> can rotate the take-up roller <NUM> at a predetermined rotation speed. Note that the pulleys <NUM>, <NUM> have the same diameter, and the rotation speed of the rotary shaft <NUM> of the take-up motor <NUM> and that of the take-up roller <NUM> are equal.

In this cleaning unit <NUM>, the roller body <NUM> of the feeding roller <NUM> has a diameter Dsu, the feeding roll Ru has a diameter Dru, the roller body <NUM> of the take-up roller <NUM> has a diameter Dsr and the take-up roll Rr has a diameter Drr as shown in <FIG>. Further, the feeding roller <NUM> feeds the sheet S by rotating at a rotation speed Nu (rpm), and the take-up roller <NUM> takes up the sheet S by rotating at a rotation speed Nr (rpm). Note that, in this example, the diameters Dsu and Dsr are equal. However, these may be different.

<FIG> is a diagram showing an electrical configuration of the printing apparatus. As shown in <FIG>, the printing apparatus <NUM> includes a controller <NUM> and a storage <NUM>. The controller <NUM> is a processor such as a CPU (Central Processing Unit), and the storage <NUM> is a storage device such as an HDD (Hard Disk Drive) or SSD (Solid State Drive). The controller <NUM> controls each component of the printing apparatus <NUM>, and the storage <NUM> stores data (target speed Vt and constant parameters Cp) used in a sheet conveyance control in the cleaning unit <NUM> to be described later. The target speed Vt is set based on an empirically obtained result on a conveying speed of the sheet S optimal for cleaning and stored in the storage <NUM> in advance. Further, the printing apparatus <NUM> includes a UI (User Interface) <NUM>. This UI <NUM> can make notification to an operator by an indication on a display, an alarm sound or the like. As shown in <FIG>, the controller <NUM> includes a linear motion mechanism drive controller 391a, a take-up motor controller 391b, a feeding roller rotation direction discriminator 391c, a take-up rotation speed calculator 391d, a feeding rotation speed calculator 391e and a computer 391f as functional parts thereof. The linear motion mechanism drive controller 391a controls the linear motion mechanism <NUM> to move the maintenance unit <NUM> in the horizontal direction Y.

In cleaning of <FIG> described above, the linear motion mechanism drive controller 391a controls the linear motion mechanism <NUM> to drive the maintenance unit <NUM> in the horizontal direction Y. In this way, the cleaning unit <NUM> provided in the maintenance unit <NUM> moves at the speed V6 in the horizontal direction Y. At this time, the take-up motor controller 391b sends a motor command value Cm (pulse signal) to the take-up motor <NUM> and controls to rotate the rotary shaft <NUM> of the take-up motor <NUM> at a rotation speed indicated by the motor command value Cm. By this control, the sheet S is conveyed at the speed Vs in the horizontal direction Y. In this way, the sheet S sandwiched by the wiping roller <NUM> and the ink discharging flat surfaces Hb is conveyed at the speed Vs in the same direction as that at the speed V6 while being moved at the speed V6. Next, a conveyance control of the sheet S executed at the time of cleaning is described.

<FIG> is a flow chart showing an example of the sheet conveyance control. Each step of <FIG> is performed by the controller <NUM>. In Step S201, the feeding roller rotation direction discriminator 391c judges whether or not the rotation direction of the feeding roller <NUM> is proper based on a confirmation result on the rotation direction of the feeding roller <NUM> indicated by outputs of the photosensor <NUM>. If this rotation direction is not proper ("NO" in Step S201), the take-up motor controller 391b stops the take-up motor <NUM> and causes the UI <NUM> to make error notification indicating that the orientation of the sheet S mounted on the feeding roller <NUM> is improper (Step S202).

If the rotation direction of the feeding roller <NUM> is proper ("YES" in Step S201), the take-up rotation speed calculator 391d confirms the rotation speed Nr (rpm) of the take-up roller <NUM> based on the motor command value Cm output to the take-up motor <NUM> (Step S203). As described above, since the diameters of the pulleys <NUM>, <NUM> are equal, the rotation speed of the rotary shaft <NUM> of the take-up motor <NUM> indicated by the motor command value Cm is the rotation speed of the take-up roller <NUM>. However, the pulleys <NUM>, <NUM> may have different diameters. In this case, the take-up rotation speed calculator 391d may obtain the rotation speed of the take-up roller <NUM> based on the rotation speed indicated by the motor command value Cm according to a diameter difference between the pulleys <NUM> and <NUM>.

In Step S204, the feeding rotation speed calculator 391e confirms the rotation speed Nu (rpm) of the feeding roller <NUM> based on outputs of the photosensor <NUM>. As described above, since the diameters of the pulleys <NUM>, <NUM> are equal, the rotation speed of the rotary plate <NUM> indicated by the output of the photosensor <NUM> is the rotation speed of the feeding roller <NUM>. However, the pulleys <NUM>, <NUM> may have different diameters. In this case, the feeding rotation speed calculator 391e may obtain the rotation speed of the feeding roller <NUM> based on the output of the photosensor <NUM> according to a diameter difference between the pulleys <NUM> and <NUM>. Note that an execution order of Steps S203, S204 is not limited to that in this example and the execution order may be reversed or these steps may be simultaneously performed.

In Step S205, the computer 391f computes the diameter Drr of the take-up roll Rr based on a ratio of the rotation speed Nr of the take-up roller <NUM> and the rotation speed Nu of the feeding roller <NUM>. The computation of this diameter Drr is based on the following knowledge. That is, if a length of the sheet S from the feeding roll Ru to the take-up roll Rr is sufficiently shorter than an entire length Lt of the sheet S, the following equation:<MAT> holds. Here, a length Lu is a length of the sheet S wound on the feeding roller <NUM> (i.e. sheets S constituting the feeding roll Ru), and a length Lr is a length of the sheet S wound on the take-up roller <NUM> (i.e. sheet S constituting the take-up roll Rr). Further, the following equations are expressed using an area Au of a side surface of the feeding roll Ru constituted by the sheet S wound on the feeding roller <NUM>, an area Ar of a side surface of the take-up roll Rr constituted by the sheet S wound on the take-up roller <NUM>, and a thickness tw of the sheet S: <MAT> <MAT>.

If these equations are simultaneously solved, <MAT> is obtained. If the conveying speed of the sheet S is constant, the following equation holds: <MAT>.

As a result, <MAT> is obtained. Therefore, the diameter Drr of the take-up roller <NUM> is given by the following equation: <MAT>.

That is, a variable of the diameter Drr is only a ratio of the rotation speed Nr and the rotation speed Nu.

Note that other constants are obtained as constant parameters Cp in advance and saved in the storage <NUM>. That is, the following constants:.

are saved as the constant parameters Cp in the storage <NUM>.

In Step S206, the take-up motor controller 391b computes the rotation speed of the take-up roller <NUM> necessary to convey the sheet S at the target speed Vt based on the diameter Drr of the take-up roll Ru and computes the motor command value Cm based on this rotation speed. Then, the take-up motor controller 391b sends the motor command value Cm to the take-up motor <NUM>. The take-up motor <NUM> having received the motor command value Cm rotates the take-up roller <NUM> based on the motor command value Cm received from the controller <NUM>. In this way, the sheet S pulled out from the feeding roller <NUM> is taken up on the take-up roller <NUM> and the sheet S is conveyed at the target speed Vt.

In the embodiment described above, the ratio of the rotation speed Nr of the take-up roller <NUM> (take-up rotation speed) and the rotation speed Nu of the feeding roller <NUM> (feeding rotation speed) is used. That is, as described above, knowledge that the roll diameter Drr of the sheet S taken up on the take-up roller <NUM> is given by a function using the ratio of the rotation speeds Nr and Nu as a variable was obtained. Accordingly, the roll diameter Drr is computed from this ratio. In this way, it is possible to obtain the roll diameter Drr of the sheet S on the take-up roller <NUM> for taking up the sheet S for wiping out the ink from the discharge heads H.

Further, the take-up motor <NUM> rotates at the rotation speed indicated by the motor command value Cm received from the take-up motor controller 391b. In contrast, the take-up rotation speed calculator 391d calculates the rotation speed Nr of the take-up roller <NUM> based on the rotation speed indicated by the motor command value Cm. In such a configuration, since it is not necessary to separately provide a detector for detecting the rotation speed Nr of the take-up roller <NUM>, the cleaning unit <NUM> can be simplified and reduced in size.

Further, the separation wall <NUM> (first separation wall) is provided which divides the cleaning region Ac in which the feeding roller <NUM>, the wiping roller <NUM> and the take-up roller <NUM> are arranged and the front region Af (first region) in which the rotation detector <NUM> is arranged. In such a configuration, it can be suppressed by the separation wall <NUM> that the ink wiped out from the discharge heads H scatters to the rotation detector <NUM> and contaminates the rotation detector <NUM>. Particularly, if the ink adheres to the photosensor <NUM>, it becomes difficult to precisely obtain the rotation speed of the feeding roller <NUM>, but ink adhesion to the photosensor <NUM> can be suppressed by the separation wall <NUM>.

Further, the separation wall <NUM> (second separation wall) is provided which divides the cleaning region Ac and the side region Asr (second region) in which the take-up motor <NUM> is arranged. In such a configuration, the scattering of the ink wiped out from the discharge heads H to the motor body <NUM> can be suppressed by the separation wall <NUM>. Particularly, if the ink adheres to the take-up motor <NUM>, an electrical system of the take-up motor <NUM> may be deteriorated, but ink adhesion to the electrical system can be suppressed by the separation wall <NUM>.

Further, the rotation transmitter <NUM> (first rotation transmitter) is provided which transmits the rotation of the feeding roller <NUM> to the rotation detector <NUM>. By interposing the rotation transmitter <NUM> in this way, the rotation detector <NUM> can be separated from the feeding roller <NUM>. As a result, it can be suppressed that the ink wiped out from the discharge heads H scatters to the rotation detector <NUM> and contaminates the rotation detector <NUM>.

Further, as shown in <FIG> and <FIG>, the rotation detector <NUM> is arranged on a side opposite to the wiping roller <NUM> with respect to the feeding roller <NUM> in the horizontal direction Y. In such a configuration, the rotation detector <NUM> is arranged away from the wiping roller <NUM>. As a result, it can be suppressed that the ink wiped out from the discharge heads H scatters to the rotation detector <NUM> and contaminates the rotation detector <NUM>.

Further, the rotation transmitter <NUM> (second rotation transmitter) is provided which transmits the rotation of the take-up motor <NUM> to the take-up roller <NUM>. By interposing the rotation transmitter <NUM> in this way, the take-up motor <NUM> can be separated from the take-up roller <NUM>. As a result, it can be suppressed that the ink wiped out from the discharge heads H scatters to the take-up motor <NUM> and contaminates the take-up motor <NUM>.

Further, as shown in <FIG> and <FIG>, the take-up motor <NUM> is arranged on a side opposite to the wiping roller <NUM> with respect to the take-up roller <NUM> in the horizontal direction Y. In such a configuration, the take-up motor <NUM> is arranged away from the wiping roller <NUM>. As a result, it can be suppressed that the ink wiped out from the discharge heads H scatters to the take-up motor <NUM> and contaminates the take-up motor <NUM>.

Further, the rotation detector <NUM> detects the rotation direction of the feeding roller <NUM>. In such a configuration, it can be confirmed by the rotation direction of the feeding roller <NUM> that an operator erroneously set the orientation of the sheet S mounted on the feeding roller <NUM> to replenish the sheet S. As a result, erroneous mounting of the sheet S can be detected.

As described above, in this embodiment, the printing apparatus <NUM> corresponds to an example of a "printing apparatus" of the invention, the controller <NUM> corresponds to an example of a "controller" of the invention, the take-up motor controller 391b corresponds to an example of a "take-up motor controller" of the invention, the computer 391f corresponds to an example of a "computer" of the invention, the take-up rotation speed calculator 391d corresponds to an example of a "take-up rotation speed calculator" of the invention, the cleaning unit <NUM> corresponds to an example of a "cleaning unit" of the invention, the separation wall <NUM> corresponds to an example of a "first separation wall" of the invention, the separation wall <NUM> corresponds to an example of a "second separation wall" of the invention, the feeding roller <NUM> corresponds to an example of a "feeding roller" of the invention, the take-up roller <NUM> corresponds to an example of a "take-up roller" of the invention, the wiping roller <NUM> corresponds to an example of a "wiping roller" of the invention, the rotation detector <NUM> corresponds to an example of a "rotation detector" of the invention, the rotation transmitter <NUM> corresponds to an example of a "first rotation transmitter" of the invention, the take-up motor <NUM> corresponds to an example of a "take-up motor" of the invention, the rotation transmitter <NUM> corresponds to an example of a "second rotation transmitter" of the invention, the front region Af corresponds to an example of a "first region" of the invention, the cleaning region Ac corresponds to an example of a "region in which the feeding roller, the wiping roller and the take-up roller are arranged" of the invention, the side region Asr corresponds to an example of a "second region" of the invention, the motor command value Cm corresponds to an example of a "motor command value" of the invention, the diameter Drr corresponds to an example of a "roll diameter" of the invention, the discharge head H corresponds to an example of a "discharge head" of the invention, the rotation speed Nu corresponds to an example of a "feeding rotation speed" of the invention, the rotation speed Nr corresponds to an example of a "take-up rotation speed" of the invention, and the sheet S corresponds to an example of a "sheet" of the invention.

Note that the invention is not limited to the embodiment described above and various changes other than the aforementioned ones can be made without departing from the scope of the invention as defined by the appended claims.

For example, the controller <NUM> can compute the roll diameter Dru of the sheet S wound in a rolled manner on the feeding roller <NUM> based on the ratio of the take-up rotation speed Nr and the feeding rotation speed Nu. Here, a relationship of the ratio of the take-up rotation speed Nr and the feeding rotation speed Nu and the diameter Dru is obtained similarly to the relationship represented by the above knowledge. In such a configuration, the controller <NUM> can obtain a remaining amount of the sheet S wound on the feeding roller <NUM>. Such a remaining amount may be, for example, displayed on the display of the UI <NUM>.

Further, the operation of the maintenance unit <NUM> described above is merely an example and the cleaning timing and method of the maintenance unit <NUM> can be changed as appropriate. Accordingly, cleaning may be performed before the start of the printing operation or cleaning may be performed after the execution of purging to push out or suck out the ink from the nozzles Hc of the discharge heads H. Alternatively, the configuration of the cleaning unit <NUM> may be so changed that cleaning can be performed when the cleaning unit <NUM> moves from the facing position La to the retracted position Lb.

Further, a specific mechanism of the rotation transmitter <NUM> or <NUM> is not limited to a mechanism using pulleys and a timing blet and may be, for example, a mechanism for transmitting rotation by a gear train.

Further, the rotary plate <NUM> of the rotation detector <NUM> may be provided coaxially with the feeding roller <NUM> without providing the rotation transmitter <NUM>.

Further, the rotary shaft <NUM> of the take-up motor <NUM> may be provided coaxially with the take-up roller <NUM> without providing the rotation transmitter <NUM>. In this case, the take-up motor <NUM> may be arranged in the front region Af.

Further, the configuration of the rotary plate <NUM> of the rotation detector <NUM> may be changed as appropriate. For example, the plurality of teeth T may have the same width.

Further, cleaning may be performed by moving the discharge heads H in the horizontal direction Y and wiping out the ink on the ink discharging flat surfaces Hb of the discharge heads H with the sheet S. In short, the cleaning unit <NUM> may be relatively moved with respect to the discharge heads H.

The invention is applicable to techniques in general for cleaning a discharge head for discharging an ink with a sheet.

The cleaning unit may be configured so that the controller includes: a take-up motor controller sending a motor command value to the take-up motor and controlling the take-up motor so that the take-up motor rotates at a rotation speed indicated by the motor command value; and a take-up rotation speed calculator calculating the take-up rotation speed from the rotation speed indicated by the motor command value sent to the take-up motor by the take-up motor controller. In such a configuration, since it is not necessary to separately provide a detector detecting the rotation speed of the take-up roller, the cleaning unit can be simplified and reduced in size.

The cleaning unit may be configured so that the computer computes a roll diameter of the sheet wound in a rolled manner on the feeding roller based on the ratio of the take-up rotation speed and the feeding rotation speed. In such a configuration, the roll diameter of the sheet wound on the feeding roller, i.e. a remaining amount of the sheet, can be obtained.

The cleaning unit may further comprise a first separation wall dividing a region in which the feeding roller, the wiping roller and the take-up roller are arranged and a first region in which the rotation detector is arranged. In such a configuration, it can be suppressed by the first separation wall that the ink wiped out from the discharge head scatters to the rotation detector and contaminates the rotation detector.

The cleaning unit may further comprise a second separation wall dividing a region in which the feeding roller, the wiping roller and the take-up roller are arranged and a second region in which the take-up motor is arranged. In such a configuration, it can be suppressed by the second separation wall that the ink wiped out from the discharge head scatters to the take-up motor.

The cleaning unit may further comprise a first rotation transmitter transmitting rotation of the feeding roller to the rotation detector. By interposing the first rotation transmitter in this way, the rotation detector can be separated from the feeding roller. As a result, it can be suppressed that the ink wiped out from the discharge head scatters to the rotation detector and contaminates the rotation detector.

The cleaning unit may be configured so that the rotation detector is arranged on a side opposite to the wiping roller with respect to the feeding roller. In such a configuration, the rotation detector is arranged away from the wiping roller. As a result, it can be suppressed that the ink wiped out from the discharge head scatters to the rotation detector and contaminates the rotation detector.

The cleaning unit may further comprise a second rotation transmitter transmitting rotation of the take-up motor to the take-up roller. By interposing the second rotation transmitter in this way, the take-up motor can be separated from the take-up roller. As a result, it can be suppressed that the ink wiped out from the discharge head scatters to the take-up motor and contaminates the take-up motor.

The cleaning unit may be configured so that the take-up motor is arranged on a side opposite to the wiping roller with respect to the take-up roller. In such a configuration, the take-up motor is arranged away from the wiping roller. As a result, it can be suppressed that the ink wiped out from the discharge head scatters to the take-up motor and contaminates the take-up motor.

The cleaning unit may be configured so that the rotation detector detects a rotation direction of the feeding roller. In such a configuration, it can be confirmed by the rotation direction of the feeding roller that an operator erroneously set the orientation of the sheet mounted on the feeding roller to replenish the sheet. As a result, erroneous mounting of the sheet can be detected.

A printing apparatus according to the invention, comprises: a discharge head discharging an ink to a printing medium; and the above cleaning the discharge head. Therefore, it is possible to obtain the roll diameter of the sheet on the take-up roller taking up the sheet for wiping out the ink from the discharge head.

Claim 1:
A cleaning unit (<NUM>), comprising:
a feeding roller (<NUM>) on which a sheet (S) cleaning a discharge head which discharges an ink is wound in a rolled manner;
a take-up roller (<NUM>) on which the sheet (S) fed from the feeding roller (<NUM>) is wound in a rolled manner;
a take-up motor (<NUM>) configured to rotate the take-up roller (<NUM>) to take up the sheet (S) fed from the feeding roller (<NUM>) on the take-up roller (<NUM>);
a wiping roller (<NUM>) configured to bring the sheet (S) being conveyed from the feeding roller (<NUM>) to the take-up roller (<NUM>) by the take-up motor (<NUM>) into contact with the discharge head,
a rotation detector (<NUM>) configured to detect a feeding rotation speed, the feeding rotation speed being a rotation speed of the feeding roller (<NUM>); and
a controller (<NUM>) configured to control drive of the take-up motor (<NUM>),
characterized in that the controller (<NUM>) includes a computer (391f) configured to compute a roll diameter of the sheet (S) taken up in a rolled manner on the take-up roller (<NUM>) based on a ratio of a take-up rotation speed and the feeding rotation speed and to compute a rotation speed of the take-up roller (<NUM>) necessary to convey the sheet (S) at a target speed based on the roll diameter, the take-up rotation speed being a rotation speed of the take-up roller (<NUM>) rotated by the take-up motor (<NUM>).