Patent Description:
A head unit incorporated in an ink-jet recording apparatus includes a recording head having a plurality of nozzles for ejecting ink on a recording medium such as a sheet, and records an image on the recording medium. One example of such head units is disclosed in Patent Document <NUM> identified below.

Patent Document <NUM> discloses a known ink-jet recording apparatus that includes a head assembly (head unit) having three recording heads. The recording heads are coupled to a base member of the head assembly with a coupling member.

With the known technology, if, when a user is using the ink-jet recording apparatus, a fault or the like occurs that requires replacement of a recording head, it is difficult to replace the recording head alone and, inconveniently, the whole head assembly needs to be replaced. Thus, it is necessary to replace also another component unnecessarily, and there is thus concern for increased cost. Also, even if the recording head alone can be replaced, it is not possible for a user to align the new recording head with respect to the existing base member.

In view of the situation described above, an object of the present invention is to provide a head unit and an ink-jet recording apparatus that allows easy replacement of a recording head as well as cost reduction.

To achieve the above object, a head unit according to the present invention includes a recording head, a frame, and an angle adjusting portion. The recording head has a plurality of nozzles for ejecting ink on a recording medium. The frame has a side wall that extends in a width direction perpendicular to a conveying direction of the recording medium to be adjacent to the recording head. To the frame, the recording head is connected rotatably about a head rotary shaft arranged in an end part of the recording head in the width direction. The angle adjusting portion is arranged at an other end part side of the recording head, opposite from the head rotary shaft in the width direction, and rotates the recording head about the head rotary shaft. The angle adjusting portion includes a frame adjusting screw and a head adjusting screw. The frame adjusting screw is provided on the side wall, on its face opposite the recording head. The frame adjusting screw can reciprocate in directions toward and away from the recording head. The head adjusting screw is provided on the recording head, on its face opposite the side wall. The head adjusting screw can reciprocate in directions toward and away from the side wall. The frame adjusting screw and the head adjusting screw make contact with each other at their tip end parts in the direction in which they face each other.

With this construction, during the assembly of the head unit, after the head adjusting screw is adjusted in the recording head, the recording head is fitted to the frame, and the frame adjusting screw is adjusted in the frame. This allows easy replacement of the recording head alone. There is also no need to replace any other components unnecessarily, and this permits cost reduction. Furthermore, when the recording head is replaced, a new recording head is fitted to the frame that has the frame adjusting screw already adjusted; thus, a user can easily adjust alignment.

An embodiment of the present invention will be described below with reference to the accompanying drawings. The present invention is, however, defined by the claims.

<FIG> is a schematic sectional view of an ink-jet recording apparatus <NUM> according to an embodiment. <FIG> is a plan view of a recording portion <NUM> in the ink-jet recording apparatus <NUM> in <FIG>. The ink-jet recording apparatus <NUM> is, for example, a printer of an ink-jet recording type. The ink-jet recording apparatus <NUM> includes, as shown in <FIG>, an apparatus main body <NUM>, a sheet feeding portion <NUM>, a sheet conveying portion <NUM>, a recording portion <NUM>, a drying portion <NUM>, and a control portion <NUM>.

The sheet feeding portion <NUM> stores a plurality of sheets (of a recording medium) S and, during recording, feeds them out one after another separately. The sheet conveying portion <NUM> conveys a sheet S fed out from the sheet feeding portion <NUM> to the recording portion <NUM> and then to the drying portion <NUM>, and then discharges the sheet S after recording and drying to a sheet discharge portion <NUM>. When duplex recording is performed, the sheet conveying portion <NUM> switches, with a branch portion <NUM>, the conveying direction of the sheet S after recording on its first side and drying to a reversing conveying portion <NUM>, and conveys the sheet S having its conveying direction switched and its obverse and reverse sides reversed to the recording portion <NUM> and then to the drying portion <NUM> once again.

The sheet conveying portion <NUM> includes first and second belt conveying portions <NUM> and <NUM>. The first belt conveying portion <NUM> has a first conveying belt <NUM> formed so as to be endless. The second belt conveying portion <NUM> has a second conveying belt <NUM> formed so as to be endless. The first and second first belt conveying portions <NUM> and <NUM> convey a sheet S by holding it by suction on their upper outer faces (top faces). The first belt conveying portion <NUM> is arranged under the recording portion <NUM> and conveys the sheet S. The second belt conveying portion <NUM> is arranged downstream of the first belt conveying portion <NUM> in the sheet conveying direction in the drying portion <NUM> and conveys the sheet S.

The recording portion <NUM> faces the sheet S that is conveyed while being held by suction on the top face of the first conveying belt <NUM> and is arranged above the first conveying belt <NUM> across a predetermined gap from it. As shown in <FIG>, the recording portion <NUM> includes head units 51B, 51C, <NUM>, and 51Y corresponding to four colors, namely black, cyan, magenta, and yellow. The head units 51B, 51C, <NUM>, and 51Yare arranged side by side along the sheet conveying direction Dc such that their longitudinal direction is parallel to the sheet width direction Dw perpendicular to the sheet conveying direction Dc. The four head units 51B, 51C, <NUM>, and 51Y have basically similar structures. Thus, in the following description, the suffixes "B", "C", "M", and "Y" distinguishing different colors are often omitted, unless distinction is needed.

The head units <NUM> for the different colors each include line recording heads <NUM> of an ink-jet type. In each of the head units <NUM> for the different colors, a plurality of recording heads <NUM> (for example, three of them (52a, 52b, and 52c)) are arranged in a staggered formation along the sheet width direction Dw.

The recording head <NUM> has a plurality of ink ejecting nozzles <NUM> in a bottom part of it. The plurality of ink ejecting nozzles <NUM> are arrayed along the sheet width direction Dw so that ink can be ejected over the entire recording region of the sheet S. That is, the recording head <NUM> has a plurality of ink ejecting nozzles <NUM> for ejecting ink on the sheet S. The recording portion <NUM> ejects ink sequentially from the recording heads <NUM> in the head units 51B, 51C, <NUM>, and 51Y of four colors toward the sheet S conveyed by the first conveying belt <NUM> so as to record on it a full-color image or a monochrome image.

The drying portion <NUM> is arranged downstream of the recording portion <NUM> in the sheet conveying direction and includes the second belt conveying portion <NUM>. While the sheet S with an ink image recorded on it in the recording portion <NUM> is being conveyed while being held by suction on the second conveying belt <NUM> in the drying portion <NUM>, the ink is dried.

The control portion <NUM> includes a CPU, a storage portion, and other electronic circuits and components (none of which are illustrated). The CPU, based on control programs and data stored in the storage portion, controls the operation of different components provided in the ink-jet recording apparatus <NUM> to perform processing related to the functions of the ink-jet recording apparatus <NUM>. The sheet feeding portion <NUM>, the sheet conveying portion <NUM>, the recording portion <NUM>, and the drying portion <NUM> individually receive commands from the control portion <NUM> and coordinate to perform printing on the sheet S. The storage portion is composed of, for example, a combination of an unillustrated non-volatile storage device, such as a program ROM (read-only memory) and a data ROM, and an unillustrated volatile storage device, such as a RAM (random-access memory).

Next, the construction of the head unit <NUM> in the ink-jet recording apparatus <NUM> will be described with reference to <FIG> as well as <FIG>. <FIG> is a horizontal sectional view of the head unit <NUM> in the recording portion <NUM> in <FIG>.

The head unit <NUM> includes, in addition to the recording head <NUM>, a frame <NUM>, a head rotary shaft <NUM>, and an angle adjusting portion <NUM>.

The frame <NUM> holds three recording heads 52a, 52b, and 52c. The three recording heads 52a, 52b, and 52c are arranged in a staggered formation along the sheet width direction Dw. The frame <NUM> has a side wall <NUM>. The side wall <NUM> extends in the up-down direction and in the sheet width direction Dw to make contact with the recording heads 52a, 52b, and 52c. The side wall <NUM> is arranged between two recording heads 52a and 52c and one recording head 52b in the sheet conveying direction Dc. The side wall <NUM> faces the side faces of the recording heads <NUM> on the downstream or upstream side in the sheet conveying direction Dc.

The head rotary shaft <NUM> is one end part 52r of each recording head <NUM> in the longitudinal direction (sheet width direction Dw) and is arranged, for example, in an end part of the recording head <NUM> at the rear side of the recording portion <NUM>. The rotation axis of the head rotary shaft <NUM> extends in the up-down direction, which is the direction normal to the top face of the first conveying belt <NUM>.

The three recording heads <NUM> are each connected to the frame <NUM> so as to be rotatable about the head rotary shaft <NUM>. The recording head <NUM> is rotatable in a rotation direction Ra in which an other end part 52f side of it in the longitudinal direction (sheet width direction Dw) moves upstream in the sheet conveying direction Dc about the head rotary shaft <NUM>, or in a rotation direction Rb in which the other end part 52f moves downstream in the sheet conveying direction Dc about the head rotary shaft <NUM>.

The angle adjusting portion <NUM> is arranged at the other end part 52f side of the recording head <NUM>, opposite from the head rotary shaft <NUM>, for example, in an end part of the recording head <NUM> at the front side of the recording portion <NUM>. The angle adjusting portion <NUM> rotates the recording head <NUM> about the head rotary shaft <NUM> in the rotation direction Ra or Rb. In this way, the angle adjusting portion <NUM> can adjust the angle of the recording head <NUM> with respect to the frame <NUM> of the head unit <NUM>; thus, it is possible to position the recording head <NUM> properly with respect to the head unit <NUM>.

Next, the structure of the angle adjusting portion <NUM> will be described with reference to <FIG> as well as <FIG>. <FIG> is a part horizontal sectional view of and around the angle adjusting portion <NUM> in the head unit <NUM> in <FIG>. <FIG> is a perspective view of the side wall <NUM> of the head unit <NUM> in <FIG>. <FIG> is a perspective view of the recording head <NUM> in the head unit <NUM> in <FIG>. <FIG> is a part perspective view of and around the angle adjusting portion <NUM> in the recording head <NUM> in <FIG>.

The angle adjusting portion <NUM> includes a frame adjusting screw <NUM> and a head adjusting screw <NUM>.

The frame adjusting screw <NUM> is provided on the side wall <NUM>, on its face opposite the recording head <NUM>. The frame adjusting screw <NUM> is fitted perpendicularly to the side wall <NUM> so as to penetrate the side wall <NUM>, and extends in a direction intersecting with the rotation axis of the head rotary shaft <NUM> (i.e., in the sheet conveying direction Dc). The frame adjusting screw <NUM> is, for example, a setscrew having a hexagonal hole or a slot formed in an end part of it. The frame adjusting screw <NUM> can reciprocate in directions toward and away from the recording head <NUM>.

The head adjusting screw <NUM> is provided on the recording head <NUM>, on its face opposite the side wall <NUM>. The head adjusting screw <NUM> is fitted perpendicularly to a side plate <NUM> of the recording head <NUM> so as to penetrate the side plate <NUM>, and extends in a direction intersecting with the rotation axis of the head rotary shaft <NUM> (i.e., in the sheet conveying direction Dc). The head adjusting screw <NUM> is, for example, a setscrew having a hexagonal hole and a slot formed in an end part of it. The head adjusting screw <NUM> can reciprocate in directions toward and away from the side wall <NUM>.

The frame adjusting screw <NUM> and the head adjusting screw <NUM> are arranged at positions at which they face each other in a direction intersecting with the rotation axis of the head rotary shaft <NUM> (i.e., in the sheet conveying direction Dc). That is, the frame adjusting screw <NUM> and the head adjusting screw <NUM> are arranged at positions at which they face each other in the longitudinal direction (sheet width direction Dw) of the head unit <NUM> and in the up-down direction, and their extending directions (moving directions) are the same. The frame adjusting screw <NUM> and the head adjusting screw <NUM> make contact with each other at tip end parts of them in the direction in which they face each other.

With this construction, during the assembly of the head unit <NUM>, after the head adjusting screw <NUM> is adjusted in the recording head <NUM>, the recording head <NUM> is fitted to the frame <NUM>, and the frame adjusting screw <NUM> is adjusted in the frame <NUM>. This allows easy replacement of the recording head <NUM> alone. There is also no need to replace any other components unnecessarily, and this permits cost reduction. Furthermore, when the recording head <NUM> is replaced, a new recording head <NUM> is fitted to the frame <NUM> that has the frame adjusting screw 81already adjusted; thus, a user can easily adjust alignment.

The head unit <NUM> includes a plurality of (three in this embodiment) recording heads <NUM> that are arranged side by side in the sheet width direction Dw. With this construction, when, for example, one recording head <NUM> needs to be replaced, the other two recording heads <NUM> can continue to be used without necessity of replacement. Thus, it is possible to reduce the cost of the head unit <NUM>.

The three recording heads 52a, 52b, and 52c are, as described above, arranged in a staggered formation along the sheet width direction Dw (see <FIG>). Two recording heads 52a and 52c are arranged upstream of the side wall <NUM> in the sheet conveying direction Dc, and one recording head 52b is arranged downstream of the side wall <NUM> in the sheet conveying direction Dc. That is, a plurality of recording heads <NUM> are arranged both upstream and downstream of the side wall <NUM> in the sheet conveying direction Dc.

With the above construction, for example, it is possible to provide the angle adjusting portion <NUM> using the frame adjusting screw <NUM> and the head adjusting screw <NUM> to each of the three recording heads 52a, 52b, and 52c arranged in a staggered formation along the sheet width direction Dw. That is, even when the recording heads <NUM> are arranged side by side in the sheet conveying direction Dc, it is possible to replace the recording head <NUM> alone easily.

The ink-jet recording apparatus <NUM> includes the head unit <NUM> constructed as described above which records an image on the sheet S. With this construction, it is possible to provide an ink-jet recording apparatus <NUM> that has a low-cost construction and that allows easy replacement of a recording head <NUM>.

The description given above of an embodiment of the present invention is in no way meant to limit the scope of the present invention which is defined by the claims.

Claim 1:
A head unit (51B, 51C, <NUM>, 51Y) comprising:
a recording head (52a, 52b, 52c) including a plurality of nozzles (<NUM>) for ejecting ink on a recording medium;
a frame (<NUM>) which has a side wall (<NUM>) that extends in a width direction perpendicular to a conveying direction of the recording medium to be adjacent to the recording head and to which the recording head is connected rotatably about a head rotary shaft (<NUM>) arranged in an end part of the recording head in the width direction; and
an angle adjusting portion (<NUM>)
which is arranged at another end part side of the recording head, opposite from the head rotary shaft in the width direction, and
which rotates the recording head about the head rotary shaft, wherein
the angle adjusting portion includes:
a frame adjusting screw (<NUM>)
which is provided on the side wall, on a face thereof opposite the recording head and
which can reciprocate in directions moving toward and away from the recording head; and characterized in that the head unit further comprises
a head adjusting screw (<NUM>)
which is provided on the recording head, on a face thereof opposite the side wall and
which can reciprocate in directions moving toward and away from the side wall, and
the frame adjusting screw and the head adjusting screw make contact with each other at tip end parts thereof in a direction in which the frame adjusting screw and the head adjusting screw face each other.