Patent Description:
In an image forming apparatus, such as an inkjet printer, a technique is widely known that adjusts the positions of recording heads to form a good image (for example, <CIT>).

Specifically, the image forming apparatus includes the recording heads (printing modules) for a plurality of colors that are arranged so as to face a sheet conveyed by a conveyor. The recording heads for the plurality of colors discharge liquid droplets toward the conveyed sheet to form a desired color image on the sheet.

<CIT> discloses a technique in which an angle adjustment mechanism adjusts an angle of the recording heads to arrange the recording heads with respect to a drum with high accuracy. In a comparative recording-head position adjustment mechanism, the discharge direction of liquid droplets discharged from the recording head varies. Therefore, a good image is not formed stably.

To adjust the angle of the recording head, the angle adjustment mechanism can be used, to which the technique disclosed in <CIT> is applied. However, the angle adjustment mechanism disclosed in <CIT> has a complicated configuration.

<CIT>discloses the preamble of claim <NUM>.

To solve such a situation described above, the present disclosure has an object to provide a recording-head position adjustment mechanism, a recording-head module, and an image forming apparatus that can easily adjust the discharge direction of the liquid droplets from the recording head without the complicated configuration.

Embodiments of the present disclosure describe an improved recording-head position adjustment mechanism according to claim <NUM>.

As a result, according to the present disclosure, the recording-head position adjustment mechanism, the recording-head module, and the image forming apparatus can be provided that can easily adjust the discharge direction of the liquid droplets from the recording head without the complicated configuration.

In addition, identical or similar reference numerals designate identical or similar components throughout the several views.

It is to be noted that the suffixes Y, M, C, K, S1, and S2 attached to each reference numeral indicate only that components indicated thereby are used for forming yellow, magenta, cyan, black, and spot color images, respectively, and hereinafter may be omitted when color discrimination is not necessary.

Embodiments of the present disclosure are described in detail with reference to drawings. Identical reference numerals are assigned to identical components or equivalents and a description of those components is simplified or omitted as appropriate.

The configuration and operation of an image forming apparatus <NUM> according to the present embodiment is described below with reference to <FIG>. In <FIG>, the image forming apparatus <NUM> is illustrated as an inkjet printer. The image forming apparatus <NUM> includes a conveyance drum <NUM> as a conveyor to convey a sheet P, a sheet feeding tray <NUM> on which sheets P to be printed are stacked, and grippers <NUM> to grip the sheet P on the conveyance drum <NUM>. The image forming apparatus <NUM> further includes a separator <NUM> to separate the sheet P from the conveyance drum <NUM>, a conveyance belt <NUM> to convey the sheet P separated from the conveyance drum <NUM>, and a sheet ejection tray <NUM> onto which the printed sheet P is ejected and stacked.

The image forming apparatus <NUM> further includes recording heads (printing modules) 10Y, <NUM>, 10C, <NUM>, 10S1, and 10S2 serving as image forming units for printing, e.g., letters and images by an inkjet method, supporting members <NUM> to support (suspend) the recording heads 10Y, <NUM>, 10C, <NUM>, 10S1, and 10S2, and a base frame <NUM> to hold the supporting members <NUM>. The supporting member <NUM> includes a first support <NUM> and a second support <NUM>.

The image forming apparatus <NUM> according to the present embodiment forms a color image. As illustrated in <FIG>, the image forming apparatus <NUM> includes the recording head <NUM> for black, the recording heads 10Y, <NUM>, and 10C for three colors (yellow, magenta, and cyan), and the recording heads 10S1 and 10S2 for coating (two spot colors). The six recording heads 10Y, <NUM>, 10C, <NUM>, 10S1, and 10S2 are opposed to the conveyance drum <NUM> and arranged side by side along the rotation direction of the conveyance drum <NUM>. In other words, the plurality of recording heads 10Y, <NUM>, 10C, <NUM>, 10S1, and 10S2 and a plurality of recording-head position adjustment mechanisms <NUM> (see <FIG> and <FIG>) to be described later are radially arranged side by side along the direction (or a conveyance direction of the sheet P) intersecting a longitudinal direction of the recording heads 10Y, <NUM>, 10C, <NUM>, 10S1, and 10S2. The longitudinal direction is perpendicular to the surface of the paper on which <FIG> is drawn.

Since the six recording heads 10Y, <NUM>, 10C, <NUM>, 10S1, and 10S2 have substantially the same structure except that the colors (types) of inks used for printing are different, the suffixes Y, M, C, K, S1, and S2 attached to the reference numeral of the recording head <NUM> are omitted in <FIG> and <FIG>. For the sake of understanding the recording head <NUM>, the recording head <NUM> indicated by a solid line is not inclined in <FIG>, but in reality, as illustrated in <FIG> (or <FIG>), all of six recording heads 10Y, <NUM>, 10C, <NUM>, 10S1, and 10S2 are inclined in the image forming apparatus <NUM>. As illustrated in <FIG>, a main part of the recording head <NUM> includes a piezoelectric actuator, a thermal actuator, or the like, and further includes a nozzle 10a to discharge ink as liquid droplets, an ink tank 10b filled with ink, and a control board (controller).

The operation of the image forming apparatus <NUM> is briefly described with reference to <FIG>. First, when a print command is input together with image data from, e.g., a personal computer to the controller of the image forming apparatus <NUM>, the sheet P is fed from the sheet feeding tray <NUM> by a sheet feeding roller. The sheet P fed from the sheet feeding tray <NUM> is conveyed toward the conveyance drum <NUM> by a conveyance roller pair <NUM>. Meanwhile, in the recording heads 10Y, <NUM>, 10C, <NUM>, 10S1, and 10S2 for the respective colors, the input image data are converted into writing data of the respective colors.

The sheet P conveyed to the conveyance drum <NUM> is gripped by the gripper <NUM> and positioned on the conveyance drum <NUM>. The conveyance drum <NUM> conveys the sheet P while rotating counterclockwise. As the conveyance drum <NUM> rotates, the sheet P is conveyed in the direction indicated by arrow A1 in <FIG>. The recording heads 10Y, <NUM>, 10C, <NUM>, 10S1, and 10S2 sequentially discharge inks of the respective colors as liquid droplets onto the sheet P based on the writing data. Thus, a desired image is formed on the sheet P. The sheet P, on which the desired image has been formed, is separated from the conveyance drum <NUM> by the separator <NUM>. The sheet P separated from the conveyance drum <NUM> is conveyed by the conveyance belt <NUM> and ejected onto the sheet ejection tray <NUM>.

A description is given below of a recording-head position adjustment mechanism <NUM> to adjust the position of the recording head <NUM> that discharges ink (liquid droplets) in the image forming apparatus <NUM> having such a configuration with reference to <FIG> and <FIG>. The recording-head position adjustment mechanism <NUM> according to the present embodiment includes an inclination adjuster <NUM> and discharge angle adjusters <NUM> or <NUM>. The inclination adjuster <NUM> adjusts an inclination α (see <FIG>) of the recording head <NUM> in the longitudinal direction. The discharge angle adjusters <NUM> and <NUM> adjust a direction of liquid droplets discharged from the nozzle 10a of the recording head <NUM> (i.e., a discharge angle β, see <FIG>).

As illustrated in <FIG>, the image forming apparatus <NUM> includes the supporting member <NUM> (see <FIG>) including the first and second supports <NUM> and <NUM> to support the recording head <NUM>. The recording head <NUM> can be drawn out in a predetermined direction (i.e., +Y direction in <FIG>). That is, the replaceable recording head <NUM> is removably installed in the image forming apparatus <NUM> (recording-head position adjustment mechanism <NUM>) so that the recording head <NUM> can be drawn out from the image forming apparatus <NUM> in +Y direction or installed into the image forming apparatus <NUM> in -Y direction. When ink stored in the ink tank 10b is depleted, the recording head <NUM> is drawn out, and a new recording head <NUM> is installed for replacement.

Here, the recording-head position adjustment mechanism <NUM> includes the supporting member <NUM> including the first support <NUM> and the second support <NUM>. The first support <NUM> supports one end of the recording head <NUM> in the longitudinal direction (i.e., a first predetermined position). The second support <NUM> supports the other end of the recording head <NUM> in the longitudinal direction (i.e., a second predetermined position different from the first predetermined position). Hereinafter, the one end of the recording head <NUM> in the longitudinal direction is referred to as a "first end," and the other end of the recording head <NUM> in the longitudinal direction is referred to as a "second end. " The recording head <NUM> is removably installed in the longitudinal direction (i.e., an installation direction). The longitudinal direction, which is ±Y directions, is substantially perpendicular to the conveyance direction of the sheet P indicated by arrow D in <FIG>.

Specifically, the supporting member <NUM> includes a pair of the first supports <NUM> and a pair of the second supports <NUM> sandwiching the recording head <NUM> in the substantially horizontal direction. In the present embodiment, as illustrated in <FIG>, the supporting member <NUM> is divided into the pair of the first supports <NUM> to support the first end of the recording head <NUM> in the longitudinal direction and the pair of the second supports <NUM> to support the second end of the recording head <NUM> in the longitudinal direction. The first end is the back side of the recording head <NUM>, and the second end is the front side of the recording head <NUM> in the installation direction. That is, the first support <NUM> includes a first support portion at the first end and a second support portion at the first end in the longitudinal direction. The second support <NUM> includes a first support portion at the second end and a second support portion at the second end in the longitudinal direction. The first support portion at the first end of one first support <NUM> and the second support portion at the first end of the other first support <NUM> sandwiches the first end of the recording head <NUM>. The first support portion at the second end of one second support <NUM> and the second support portion at the second end of the other second support <NUM> sandwiches the second end of the recording head <NUM>. Thus, the supporting member <NUM> including the pair of the first supports <NUM> and the pair of the second supports <NUM> supports the recording head <NUM>.

As illustrated in <FIG>, the first support <NUM> includes a first upper grooved roller 21Aa and a first lower grooved roller 21Ab (hereinafter, collectively referred to as first grooved rollers 21Aa and 21Ab) serving as the first support portion at the first end, and two first columnar rollers 22A serving as the second support portion at the first end. The first grooved rollers 21Aa and 21Ab engage and support one edge of the recording head <NUM> in a transverse direction of the recording head <NUM> at the first end in the longitudinal direction. The first columnar rollers 22A support the other edge of the recording head <NUM> in the transverse direction at the first end in the longitudinal direction so that the recording head <NUM> is movable on the first columnar rollers 22A. Hereinafter, the one edge of the recording head <NUM> in the transverse direction is referred to as a "first edge", and the other edge of the recording head <NUM> in the transverse direction is referred to as a "second edge". The first support <NUM> is secured to the image forming apparatus <NUM> (side frame <NUM>), and the discharge angle adjuster <NUM>, which is described later, is installed in the first support <NUM>.

Similarly, the second support <NUM> includes a second upper grooved roller 21Ba and a second lower grooved roller 21Bb (hereinafter, collectively referred to as second grooved rollers 21Ba and 21Bb) serving as the first support portion at the second end, and two second columnar rollers 22B serving as the second support portion at the second end. The second grooved rollers 21Ba and 21Bb engage and support the first edge of the recording head <NUM> in the transverse direction at the second end in the longitudinal direction. The second columnar rollers 22B support the second edge of the recording head <NUM> in the transverse direction at the second end in the longitudinal direction so that the recording head <NUM> is movable on the second columnar rollers 22B. The inclination adjuster <NUM> and the discharge angle adjuster <NUM>, which are described later, are installed in the second support <NUM>.

Specifically, the recording head <NUM> includes two ridged rails 11a and 11b as a first slider at the first edge and a flat rail <NUM> as a second slider at the second edge in the transverse direction. The transverse direction is perpendicular to the longitudinal direction and substantially the same as the conveyance direction of the sheet P. The ridged rails 11a and 11b are disposed vertically apart. As illustrated in <FIG>, each of the ridged rails 11a and 11b has a guide surface with a V-shaped projection, and the flat rail <NUM> has a flat guide surface. The ridged rails 11a and 11b and the flat rail <NUM> extend in the installation direction in which the recording head <NUM> is removably installed (i.e., ±Y directions).

The first and second grooved rollers 21Aa, 21Ab, 21Ba, and 21Bb have a V-shaped groove on the outer circumferential surface and are rotatably supported by bodies of the first and second supports <NUM> and <NUM>. The first and second columnar rollers 22A and 22B have a flat outer circumferential surface and are rotatably supported by the bodies of the first and second supports <NUM> and <NUM>.

The two first grooved rollers 21Aa and 21Ab (first support portion at the first end) disposed vertically apart engage the two ridged rails 11a and 11b (first slider) disposed vertically apart on the recording head <NUM>, respectively. The two first columnar rollers 22A (second support portion at the first end) contact the flat rail <NUM> (second slider) of the recording head <NUM> so as to sandwich the flat rail <NUM> from above and below. Specifically, the first grooved rollers 21Aa and 21Ab are first rotators that slidably support the ridged rails 11a and 11b of recording head <NUM> in the longitudinal direction of the recording head <NUM>, respectively, while restricting the ridged rails 11a and 11b from moving in the transverse direction intersecting the longitudinal direction relative to the first grooved rollers 21Aa and 21Ab. The first columnar rollers 22A are second rotators that slidably support the flat rail <NUM> of the recording head <NUM> in the longitudinal direction of the recording head <NUM>. Further, the first columnar rollers 22A as the second rotators slidably support the flat rail <NUM> in the transverse direction of the recording head <NUM>.

Similarly, the two second grooved rollers 21Ba and 21Bb disposed vertically apart engage the two ridged rails 11a and 11b disposed vertically apart on the recording head <NUM>, respectively. The two second columnar rollers 22B contact the flat rail <NUM> of the recording head <NUM> so as to sandwich the flat rail <NUM> from above and below. Specifically, the second grooved rollers 21Ba and 21Bb are third rotators that slidably support the ridged rails 11a and 11b of the recording head <NUM> in the longitudinal direction of the recording head <NUM>, respectively, while restricting the ridged rails 11a and 11b from moving in the transverse direction intersecting the longitudinal direction relative to the second grooved rollers 21Ba and 21Bb. The second columnar rollers 22B are fourth rotators that slidably support the flat rail <NUM> of the recording head <NUM> in the longitudinal direction of the recording head <NUM>. Further, the second columnar rollers 22B as the fourth rotators slidably support the flat rail <NUM> in the transverse direction of the recording head <NUM>.

While the first and second grooved rollers 21Aa, 21Ab, 21Ba, and 21Bb and the first and second columnar rollers 22A and 22B rotate, the ridged rails 11a and 11b and the flat rail <NUM> move on the first and second grooved rollers 21Aa, 21Ab, 21Ba, and 21Bb and the first and second columnar rollers 22A and 22B. Thus, the recording head <NUM> is removably installed in ±Y directions.

The first and second grooved rollers 21Aa, 21Ab, 21Ba, and 21Bb described above are classified into an upper support (i.e., the first upper grooved roller 21Aa and the second upper grooved roller 21Ba) that supports the upper portion of the recording head <NUM> and a lower support (i.e., the first lower grooved roller 21Ab and the second lower grooved roller 21Bb) that supports the lower portion of the recording head <NUM>, which is described later in detail. Hereinafter, the first and second grooved rollers 21Aa, 21Ab, 21Ba, and 21Bb are simply referred to as the groove rollers 21Aa, 21Ab, 21Ba, and 21Bb, and the first and second columnar rollers 22A and 22B are simply referred to as the columnar rollers 22A and 22B. In the drawings, when two rollers completely overlap, the suffix (or a part of the suffix) of reference numerals may be omitted, for example, the columnar rollers 22A and the columnar rollers 22B overlap and are indicated by the reference numeral <NUM>, and the first upper grooved roller 21Aa and the second upper grooved roller 21Ba overlap and are indicated by the reference numeral 21a as illustrated in <FIG>, <FIG>, and the like.

With such a configuration, the recording head <NUM> is removably installed in the image forming apparatus <NUM> while being restricted from moving in ±X directions by the grooved rollers 21Aa, 21Ab, 21Ba, and 21Bb having the V-shaped groove. Accordingly, the recording head <NUM> can be smoothly installed in and removed from the image forming apparatus <NUM> without damages to the recording head <NUM> caused by interference with other components. That is, the grooved rollers 21Aa, 21Ab, 21Ba, and 21Bb function not only as positioning members for the recording head <NUM>, but also as guide members for facilitating the installation and removal operation of the recording head <NUM>.

In the present embodiment, the grooved rollers 21Aa, 21Ab, 21Ba, and 21Bb have the V-shaped groove, and the ridged rails 11a and 11b have the V-shaped projection. The V-shaped projection engages the V-shaped groove, thereby restricting the recording head <NUM> from moving in the ±X directions. However, the shape of the groove on the grooved rollers 21Aa, 21Ab, 21Ba, and 21Bb and the shape of the projection on the ridged rails 11a and 11b are not limited to the V-shape but may be any other suitable shape that can meet such a function, for example, a W-shape or a shape in which three or more V shapes are arranged.

As illustrated in <FIG> and <FIG>, in the present embodiment, the first support <NUM> includes other first columnar rollers 22A disposed on the opposite side of the portion where the first grooved rollers 21Aa and 21Ab are disposed in order to support another recording head <NUM> adjacent to the recording head <NUM>. Similarly, the second support <NUM> includes other second columnar rollers 22B disposed on the opposite side of the portion where the second grooved rollers 21Ba and 21Bb are disposed in order to support another recording head <NUM> adjacent to the recording head <NUM>. With such a configuration, the plurality of the recording heads 10Y, <NUM>, 10C, <NUM>, 10S1, and 10S2 can be compactly installed in the image forming apparatus <NUM> along the conveyance direction of the sheet P.

As illustrated in <FIG>, in the present embodiment, the first support <NUM> is secured to the side frame <NUM> coupled to the base frame <NUM> disposed on the ceiling of the image forming apparatus <NUM>. That is, the first support <NUM> is stationarily installed at the secured position in the image forming apparatus <NUM>. On the other hand, the second support <NUM> is slidable in the transverse direction (i.e., the direction perpendicular to the surface of the paper in which <FIG> is drawn and the direction indicated by arrow A2 in <FIG>) relative to a side frame <NUM> coupled to the base frame <NUM>. That is, the second support <NUM> is slidably supported in the image forming apparatus <NUM>.

In particular, in the present embodiment, the second support <NUM> includes other second columnar rollers 22B disposed on the opposite side of the portion where the second grooved rollers 21Ba and 21Bb are disposed such that the second columnar rollers 22B does not follow the movement (slide) of the second grooved rollers 21Ba and 21Bb, in order to support another recording head <NUM> adjacent to the recording head <NUM>.

Specifically, as illustrated in <FIG>, <FIG>, and <FIG>, the second grooved rollers 21Ba and 21Bb are directly attached to the main portion of the second support <NUM> that is slidable relative to the side frame <NUM>. On the other hand, the second columnar rollers 22B are not directly attached to the main portion of the second support <NUM>, but is secured to the side frame <NUM>. That is, the second support <NUM> has a two-body structure divided into a portion where the second grooved rollers 21Ba and 21Bb are disposed and a portion where the second columnar rollers 22B are disposed. With such a configuration, even when the main portion of the second support <NUM> to which the second grooved rollers 21Ba and 21Bb are attached slides during inclination adjustment of the recording head <NUM>, which is described later, the second columnar rollers 22B do not move in conjunction with the slide of the main portion.

If the second columnar rollers 22B moves in conjunction with the slide of the main portion, when the inclination adjuster <NUM> described later slides the recording head <NUM> (10Y) in the direction indicated by arrow A3 as illustrated in <FIG> to adjust the inclination α (see <FIG>) of the recording head <NUM> (10Y) in the longitudinal direction, the adjacent recording head <NUM> (10S1) may be swung in the direction indicated by arrow A4 in <FIG>, and the discharge direction (discharge angle β, see <FIG>) of liquid droplets may change. In such a case, as the inclination adjuster <NUM> slides the second grooved rollers 21Ba and 21Bb together with the recording head <NUM>, the second columnar roller 22B is also slid in conjunction with the slide of the main portion of the second support <NUM> including the second grooved rollers 21Ba and 21Bb. As a result, the adjacent recording head <NUM> may receive force from the second columnar rollers 22B and may be swung in the direction indicated by arrow A4 in <FIG>. On the other hand, in the present embodiment, the second columnar rollers 22B do not slides in conjunction with the slide of the second grooved rollers 21Ba and 21Bb, thereby preventing the adjacent recording head <NUM> from being unintentionally swung.

As illustrated in <FIG>, the image forming apparatus <NUM> (the recording-head position adjustment mechanism <NUM>) according to the present embodiment includes the inclination adjuster <NUM>. The inclination adjuster <NUM> moves the second support <NUM> in the direction intersecting the longitudinal direction (i.e., the conveyance direction of the sheet P and the transverse direction) relative to the first support <NUM> to adjust the inclination of the recording head <NUM>.

Specifically, the inclination adjuster <NUM> moves the second grooved rollers 21Ba and 21Bb in the transverse direction intersecting the longitudinal direction. Accordingly, the first edge in the transverse direction of the recording head <NUM> at the second end in the longitudinal direction is moved following the movement of the second grooved rollers 21Ba and 21Bb. As a result, the recording head <NUM> is swung around the first end in the longitudinal direction (i.e., the position of the first grooved rollers 21Aa and 21Ab), thereby adjusting the inclination of the recording head <NUM>.

More specifically, the inclination adjuster <NUM> is an adjustment knob, which is rotatable, having an eccentric shaft 50a. The outer circumferential surface of the inclination adjuster <NUM> is rotatably held by the side frame <NUM> (see <FIG>) in the direction indicated by arrow A5 in <FIG>. A circular hole is disposed on the side frame <NUM>. A part of the outer circumferential surface of the inclination adjuster <NUM> in the axial direction fits into the circular hole, and the eccentric shaft 50a is held by the second support <NUM>. A slot 20a is disposed on the second support <NUM> and long in the vertical direction. The outer circumferential surface of the eccentric shaft 50a of the inclination adjuster <NUM> fits into the slot 20a and slidably contacts the slot 20a.

With such a configuration, as the inclination adjuster <NUM> is manually rotated in the direction indicated by arrow A5 in <FIG>, the second support <NUM> slides in the direction perpendicular to the surface of the paper on which <FIG> is drawn (i.e., the transverse direction of the recording head <NUM>). Accordingly, the recording head <NUM> is pulled by the second grooved rollers 21Ba and 21Bb of the second support <NUM> and swung around the first end in the longitudinal direction of recording head <NUM> in the direction indicated by arrow A6 in <FIG>. As a result, the inclination α of the recording head <NUM> (i.e., squareness of recording head <NUM> with respect to the conveyance direction of the sheet P) is adjusted. At this time, on the second edge of the recording head <NUM> in the transverse direction, the flat rail <NUM> slidingly moves on the columnar rollers 22A and 22B. Therefore, the swing of the recording head <NUM> described above is not hindered. Further, for the same reason, when the recording head <NUM> is swung for adjustment of the inclination, the adjacent recording head <NUM> is not swung and the position (inclination) of the adjacent recording head <NUM> is not affected by the adjustment. The above-described accurate adjustment of the position (inclination) of the recording head <NUM> allows a good image to be formed on the sheet P without positional deviation.

When the inclination of the recording head <NUM> is adjusted as described above, the screwing of a securing member <NUM> illustrated in <FIG> is temporarily released. The securing member <NUM> is screwed into a female screw of the second support <NUM> via the side frame <NUM>, thereby securing the second support <NUM> to the side frame <NUM> of the image forming apparatus <NUM>. Therefore, after the inclination adjuster <NUM> slidingly moves the second support <NUM> to adjust the inclination of the recording head <NUM>, the securing member <NUM> is screwed, thereby securing the second support <NUM> at the adjusted position.

In the present embodiment, the recording-head position adjustment mechanism <NUM> does not include a large supporting member that matches the size of the recording head <NUM> in the longitudinal direction. In the comparative example, the recording-head position adjustment mechanism swings the large supporting member that matches the size of the recording head <NUM> in the longitudinal direction to adjust the position (inclination) of the recording head <NUM>. On the other hand, in the recording-head position adjustment mechanism <NUM> according to the present embodiment, the supporting member <NUM> is divided into the first support <NUM> and the second support <NUM> in the longitudinal direction. The inclination adjuster <NUM> slidingly moves only the second support <NUM> while the first support <NUM> remains static, thereby adjusting the position (inclination) of the recording head <NUM>. Therefore, the position (inclination) of the recording head <NUM> can be easily adjusted without increasing the size of the apparatus.

In the present embodiment, the first support <NUM> and the second support <NUM> are manufactured as separate parts, and the body of each of the first support <NUM> and the second support <NUM> is manufactured by aluminum die casting. In particular, since the body of the second support <NUM>, which is the housing portion excluding the second grooved rollers 21Ba and 21Bb, the second columnar rollers 22B, and the like) is made of aluminum, the weight of the second support <NUM> is reduced, thereby facilitating the manual operation of the inclination adjuster <NUM> to move the second support <NUM>.

Further, in the present embodiment, as described above with reference to <FIG>, the ridged rails 11a and 11b of recording head <NUM> engage the grooved rollers 21Aa, 21Ab, 21Ba, and 21Bb, and the flat rail <NUM> of recording head <NUM> is slidingly movable on the columnar rollers 22A and 22B. Therefore, the above-described operation of the inclination adjuster <NUM> to swing the recording head <NUM> is not hindered, and the recording head <NUM> is supported by the multiple rollers (i.e., the grooved rollers 21Aa, 21Ab, 21Ba, and 21Bb, and the columnar rollers 22A and 22B) in a well-balanced manner.

Further, the multiple rollers (i.e., the grooved rollers 21Aa, 21Ab, 21Ba, and 21Bb, and the columnar rollers 22A and 22B) are arranged at four balanced positions, i.e., the first edge in the transverse direction at the first end in the longitudinal direction, the second edge in the transverse direction at the first end in the longitudinal direction, the first edge in the transverse direction at the second end in the longitudinal direction, and the second edge in transverse direction at the second end in the longitudinal direction. This configuration can downsize the recording-head position adjustment mechanism <NUM> (image forming apparatus <NUM>).

Here, the engagement of the grooved rollers 21Aa, 21Ab, 21Ba, and 21Bb, and the ridged rails 11a and 11b is described with reference to <FIG>. The first upper grooved roller 21Aa and the ridged rail 11a are described as an example. The first upper grooved roller 21Aa has the V-shaped groove, that is, has a shape such that the tips on the small diameter side of two cones are combined. Accordingly, as illustrated in <FIG>, the first upper grooved roller 21Aa is in line contact with the V-shaped projection of the ridged rail 11a. Therefore, as illustrated in <FIG>, even when the recording head <NUM> is inclined with respect to the longitudinal direction and the ridged rail 11a is inclined relative to the first upper grooved roller 21Aa, the line contact thereof is hardly changed. Therefore, the ridged rail 11a does not float from the first upper grooved roller 21Aa. That is, regardless of the posture of the recording head <NUM> in the inclination direction, the recording head <NUM> is supported by the four rollers (i.e., the grooved rollers 21Aa, 21Ab, 21Ba, and 21Bb) without floating.

In the present embodiment, the second support <NUM> and the inclination adjuster <NUM> are disposed at positions corresponding to the front side in the installation direction of the recording head <NUM>. Specifically, a door is disposed on the front side of the image forming apparatus <NUM> in the installation direction. With the door opened, an operator pulls out the recording head <NUM> through the front side or inserts the recording head <NUM> toward the rear side of the image forming apparatus <NUM> in the installation direction. The inclination adjuster <NUM> is exposed to the operator when the door is opened. In the image forming apparatus <NUM>, the second support <NUM> is disposed on the front side in the installation direction of the recording head <NUM>, and the first support <NUM> is disposed on the rear side in the installation direction. With such a configuration, the operator can smoothly adjust the inclination of the recording head <NUM> by operating the inclination adjuster <NUM> with the door opened.

As a variation, <FIG> is a top view illustrating the arrangement of four array-type recording heads 10Y, <NUM>, 10C, and <NUM> in the conveyance direction of the sheet P indicated by arrow D. In the above-described embodiment, each of the six recording heads 10Y, <NUM>, 10C, <NUM>, 10S1, and 10S2 includes a single head longer than the width of the sheet P. In the variation, the array-type recording heads 10Y, <NUM>, 10C, and <NUM> illustrated in <FIG> are arranged in parallel. Unlike the above-describe embodiment, each of the array-type recording heads 10Y, <NUM>, 10C, and <NUM> includes a plurality of heads <NUM> (<NUM> heads in <FIG>).

The recording-head position adjustment mechanism <NUM> according to the above-described embodiment can be applied to the array-type recording heads 10Y, <NUM>, 10C, and <NUM>. Accordingly, the array-type recording heads 10Y, <NUM>, 10C, and <NUM> can be easily adjusted without increasing the size of the recording-head position adjustment mechanism <NUM> (image forming apparatus <NUM>). Specifically, in <FIG>, among the four array-type recording heads 10Y, <NUM>, 10C, and <NUM>, the inclination adjuster <NUM> swings the array-type recording head <NUM> for magenta counterclockwise to adjust the inclination thereof, and swings the array-type recording head <NUM> for black clockwise to adjust the inclination thereof.

Here, as described above, the recording-head position adjustment mechanism <NUM> according to the present embodiment includes the supporting member <NUM> (the first support <NUM> and the second support <NUM>) including an upper support (i.e., the first upper grooved roller 21Aa and the second upper grooved roller 21Ba) that supports the upper portion of the recording head <NUM> and a lower support (i.e., the first lower grooved roller 21Ab and the second lower grooved roller 21Bb) that supports the lower portion of the recording head <NUM>.

In addition to the inclination adjuster <NUM> described above, the recording-head position adjustment mechanism <NUM> according to the present embodiment includes the discharge angle adjusters <NUM> and <NUM> that adjust the direction of liquid droplets discharged from the nozzle 10a of the recording head <NUM> (i.e., the discharge angle β, see <FIG>). The discharge angle adjusters <NUM> and <NUM> move the recording head <NUM> in the direction intersecting the longitudinal direction (substantially the same direction as the conveyance direction of the sheet P and the transverse direction) to swing the lower portion of the recording head <NUM> around an upper portion W (see <FIG>) supported by the first and second upper grooved rollers 21Aa and 21Ba (upper support) as a fulcrum, thereby adjusting the direction (discharge angle β) of the liquid droplets discharged from the recording head <NUM>. In other words, when the discharge angle β is adjusted, the recording head <NUM> is swung around the longitudinal axis with the V-shaped groove of the first and second upper grooved rollers 21Aa and 21Ba (upper support) as a fulcrum by the discharge angle adjusters <NUM> and <NUM>.

The adjustment of the discharge angle β by the discharge angle adjusters <NUM> and <NUM> is also referred to as the adjustment of the discharge direction of the liquid droplets from the recording head <NUM> to the surface of the conveyance drum <NUM> (or the surface of the sheet P conveyed on the conveyance drum <NUM>). As described above with reference to <FIG>, the discharge angle adjusters <NUM> and <NUM> are provided so as to prevent the discharge angle β of the adjacent recording head <NUM> (10S1) from changing when the inclination adjuster <NUM> slides the recording head <NUM> (10Y) in the direction indicated by arrow A3 in <FIG> and adjusts the inclination α (see <FIG>) of the recording head <NUM> in the longitudinal direction.

Here, with reference to <FIG>, the discharge angle β of the recording head <NUM> is preferably <NUM> degrees, which is a target angle perpendicular to the surface of the conveyance drum <NUM> (or the surface of the sheet P). The discharge angle β is defined as an angle of the recording head <NUM> with respect to the target angle. When the discharge angle β is <NUM> degrees, liquid droplets are discharged straight (perpendicular) onto the sheet P, thereby forming a good image. On the other hand, as the discharge angle β increases, liquid droplets are discharged obliquely onto the sheet P, which may cause an image formed on the sheet P to deteriorate. Therefore, as the inclination adjuster <NUM> finishes adjusting the inclination α of each of the recording heads 10Y, <NUM>, 10C, <NUM>, 10S1, and 10S2 (i.e., after the securing member <NUM> secures the second support <NUM>), the discharge angle adjusters <NUM> and <NUM> adjust the discharge angle β of each of the recording heads 10Y, <NUM>, 10C, <NUM>, 10S1, and 10S2.

Specifically, with reference to <FIG>, in the present embodiment, the discharge angle adjusters <NUM> and <NUM> (in particular, adjustment rollers 56a and 57a described later) are disposed adjacent to the first and second lower grooved rollers 21Ab and 21Bb (lower supports), respectively. More specifically, the discharge angle adjusters <NUM> and <NUM> includes the adjustment rollers 56a and 57a to push the ridged rail 11b attached to the lower portion of the recording head <NUM>, respectively. As a result, the recording head <NUM> can be efficiently swung around the upper portion W (see <FIG>) supported by the first and second upper grooved rollers 21Aa and 21Ba (upper supports), and the discharge angle β can be efficiently adjusted.

In the present embodiment, in order to smoothly swing the recording head <NUM> around the upper portion W, preferably, the first and second lower grooved rollers 21Ab and 21Bb (lower supports) are disposed in the first and second supports <NUM> and <NUM>, respectively, so as to be movable in the left-right direction in <FIG>, or a play (backlash of about <NUM> to <NUM>) in the left-right direction in <FIG> is provided between the first and second lower grooved rollers 21Ab and 21Bb (lower supports) and the ridged rail 11b.

With reference to <FIG>, in the present embodiment, the discharge angle adjusters <NUM> and <NUM> are provided in the first support <NUM> and the second support <NUM>, respectively. The discharge angle adjuster <NUM> in the first support <NUM> and the discharge angle adjuster <NUM> in the second support <NUM> can adjust the discharge angle β independently of each other. With such a configuration, even if the recording head <NUM> has a long length in the longitudinal direction, the discharge angle β of the recording head <NUM> can be uniformly adjusted to the target angle over the longitudinal direction without a positional difference in the longitudinal direction and without torsion of the recording head <NUM>.

In the present embodiment, the discharge angle adjuster <NUM> (see <FIG>) in the first support <NUM> and the discharge angle adjuster <NUM> (see <FIG>) in the second support <NUM> have different configurations. The discharge angle adjuster <NUM> in the first support <NUM> includes an eccentric shaft 57b serving as an operation portion. The eccentric shaft 57b projects from a ceiling (or bottom) of the first support <NUM>. On the other hand, the discharge angle adjuster <NUM> in the second support <NUM> includes a return screw 56b and a pressing screw 56c serving as operation portions. The return screw 56b and the pressing screw 56c project from the front side of the second support <NUM> toward the front side in the installation direction of the recording head <NUM>.

With such a configuration, with the door opened, an operator operates the return screw 56b and the pressing screw 56c from the front side in the installation direction to cause the discharge angle adjuster <NUM> of the second support <NUM> to adjust the discharge angle β. Further, the operator puts his/her hand into the rear side in the installation direction toward the ceiling (or bottom) of the first support <NUM> and operates the eccentric shaft 57b to cause the discharge angle adjuster <NUM> of the first support <NUM> to adjust the discharge angle β. With such a configuration, the discharge angle β of the recording head <NUM> can be smoothly adjusted.

More specifically, the discharge angle adjuster <NUM> in the second support <NUM> is described in detail with reference to <FIG>. As illustrated in <FIG>, the discharge angle adjuster <NUM> includes the adjustment roller 56a as a pushing member, the return screw 56b as an operation portion, the pressing screw 56c as an operation portion, a wedge-shaped member 56d (biasing member), a restrictor 56f, and the like.

The adjustment roller 56a serving as a pushing member contacts the ridged rail 11b attached to the lower portion of the recording head <NUM>. The adjustment roller 56a includes a shaft 56a1. Both ends of the shaft 56a1 are loosely held by grooves 20x of the second support <NUM>. The grooves 20x position the adjustment roller 56a in the second support <NUM> in the up-down direction and the left-right direction in <FIG>. Both ends of the shaft 56a1 of the adjustment roller 56a contact an inclined surface of the wedge-shaped member 56d serving as a biasing member.

The return screw 56b serving as an operation portion is screwed into a female screw of the wedge-shaped member 56d to move the wedge-shaped member 56d in the direction indicated by arrow A7 in <FIG>. The pressing screw 56c serving as an operation portion is screwed into a female screw of the second support <NUM> and contacts the wedge-shaped member 56d to position the wedge-shaped member 56d in the left-right direction in <FIG>. The wedge-shaped member 56d is movable in a hollow portion of the second support <NUM> in the left-right direction in <FIG> to push the adjustment roller 56a upward in <FIG> (in the direction in which the ridged rail 11b is pushed). The restrictor 56f comes into contact with the shaft 56a1 of the adjustment roller 56a to prevent the adjustment roller 56a from moving upward in <FIG> without limitation and falling off from the second support <NUM>.

When the ridged rail 11b is pushed upward in <FIG>, the discharge angle adjuster <NUM> described above is operated as follows. First, the return screw 56b is rotated to loosen the screwing between the return screw 56b and the female screw of the wedge-shaped member 56d. Then, the pressing screw 56c is rotated to push the wedge-shaped member 56d to the right in <FIG>, and the wedge-shaped member 56d moves the adjustment roller 56a upward in <FIG>. As a result, the recording head <NUM> is swung around the upper portion W supported by the second upper grooved roller 21Ba (upper support) in the direction indicated by arrow A8 as illustrated in <FIG>. As the discharge angle β is adjusted to the target angle, the return screw 56b is rotated and tightened. Thus, force in the direction opposite to that of the pressing screw 56c acts on the wedge-shaped member 56d, thereby positioning (securing) the wedge-shaped member 56d (adjustment roller 56a) at the adjusted position.

On the other hand, when the ridged rail 11b is moved downward in <FIG>, the discharge angle adjuster <NUM> is operated as follows. First, the pressing screw 56c is rotated to release the contact between the pressing screw 56c and the wedge-shaped member 56d. Then, the return screw 56b is rotated and tightened to move the wedge-shaped member 56d to the left in <FIG>, and the adjustment roller 56a moves downward in <FIG> along the inclined surface of the wedge-shaped member 56d due to the weight of the recording head <NUM> acting on the adjustment roller 56a, which is described in detail later. As a result, the recording head <NUM> is swung around the upper portion W supported by the second upper grooved roller 21Ba (upper support) in the direction opposite to the direction indicated by arrow A8 in <FIG>. As the discharge angle β is adjusted to the target angle, the pressing screw 56c is rotated and tightened. Thus, force in the direction opposite to that of the return screw 56b acts on the wedge-shaped member 56d, thereby positioning (securing) the wedge-shaped member 56d (adjustment roller 56a) at the adjusted position.

Next, the discharge angle adjuster <NUM> in the first support <NUM> is described in detail with reference to <FIG>. As illustrated in <FIG>, the discharge angle adjuster <NUM> includes the adjustment roller 57a as a pushing member, the eccentric shaft 57b as an operation portion, a fixing plate 57c that secures the posture of the eccentric shaft 57b in the rotation direction, a fixing screw <NUM>, and the like.

The adjustment roller 57a serving as a pushing member contacts the ridged rail 11b attached to the lower portion of the recording head <NUM>. Both ends of the eccentric shaft 57b of the adjustment roller 57a are rotatably supported by the first support <NUM>. The eccentric shaft 57b as an operation portion extends in a hollow portion of the first support <NUM> in the up-down direction in <FIG>. The eccentric shaft 57b has a large-diameter portion, and the large-diameter portion contacts an inner surface of the hollow portion of the first support <NUM>, thereby positioning the adjustment roller 57a in the first support <NUM> in the vertical direction.

As the eccentric shaft 57b serving as an operation portion is rotated in the direction indicated by arrow A9 in <FIG>, the adjustment roller 57a is moved in the left-right direction in <FIG>. With reference to <FIG>, as the posture of the eccentric shaft 57b (adjustment roller 57a) in the rotation direction is determined, the fixing plate 57c is secured to the first support <NUM> by a screw <NUM> so as to fit onto a polygonal milling portion 57b1 formed at the tip of the eccentric shaft 57b. The polygonal milling portion 57b1 projects from the ceiling of the first support <NUM>. The screw <NUM> is screwed into a female screw of the first support <NUM> through a slotted hole 57c1 of the fixing plate 57c.

When the ridged rail 11b is pushed to the left in <FIG>, the discharge angle adjuster <NUM> described above is operated as follows. First, the eccentric shaft 57b is rotated to direct a long-radius portion of the adjustment roller 57a to the left in <FIG>. As a result, the ridged rail 11b is pushed by the adjustment roller 57a, and the recording head <NUM> is swung around the upper portion W supported by the first upper grooved roller 21Aa (upper support) in the direction indicated by arrow A8 in <FIG>. As the discharge angle β is adjusted to the target angle, the fixing plate 57c is fitted onto the milling portion 57b1 of the eccentric shaft 57b, and the fixing plate 57c is secured to the first support <NUM> by the screw <NUM>.

On the other hand, when the ridged rail 11b is moved to the right in <FIG>, the discharge angle adjuster <NUM> is operated as follows. First, the eccentric shaft 57b is rotated to direct the long-radius portion of the adjustment roller 57a to the right in <FIG>. As a result, the ridged rail 11b moves to the right in <FIG> following the adjustment roller 57a due to the weight of the recording head <NUM>, which is described in detail later, and the recording head <NUM> is swung around the upper portion W supported by the first upper grooved roller 21Aa (upper support) in the direction opposite to the direction indicated by arrow A8 in <FIG>. As the discharge angle β is adjusted to the target angle, the fixing plate 57c is fitted onto the milling portion 57b1 of the eccentric shaft 57b, and the fixing plate 57c is secured to the first support <NUM> by the screw <NUM>.

Here, in the present embodiment, as described above with reference to <FIG>, in order to apply the weight of the recording head <NUM> to the adjustment rollers 56a and 57a, the recording head <NUM> is not installed straight (perpendicular to a horizontal plane) but is installed at an angle as illustrated in <FIG>. Although only four recording heads 10Y, <NUM>, 10C, and 10S1 are illustrated in <FIG> for the sake of simplicity, the six recording heads 10Y, <NUM>, 10C, <NUM>, 10S1, and 10S2 are actually installed so as to be radially inclined as illustrated in <FIG>.

Specifically, with reference to <FIG>, the first support <NUM> is inclined such that the side on which the first grooved rollers 21Aa and 21Ab (the first support portion at the first end) are disposed faces upward and the side on which the first columnar roller 22A (the second support portion at the first end) is disposed faces downward. Similarly, with reference to <FIG>, the second support <NUM> is inclined such that the side on which the second grooved rollers 21Ba and 21Bb (the first support portion at the second end) are disposed faces upward and the side on which the second columnar roller 22B (the second support portion at the second end) is disposed faces downward.

Specifically, with reference to <FIG>, unlike the plurality of first and second supports <NUM> and <NUM>, first and second center supports 19X and 20X includes the columnar rollers 22A and 22B on both the left side and the right side in <FIG>. In the first and second supports <NUM> and <NUM> on the left side with respect to the first and second center supports 19X and 20X (downstream in the conveyance direction) in <FIG>, the columnar rollers 22A and 22B are attached to the left side of the body of the first and second supports <NUM> and <NUM> in <FIG>, and the grooved rollers 21Aa, 21Ab, 21Ba, and 21Bb are attached to the right side of the body in <FIG>. In the first and second supports <NUM> and <NUM> on the right side with respect to the first and second center supports 19X and 20X (upstream in the conveyance direction) in <FIG>, the columnar rollers 22A and 22B are attached to the right side of the body of the first and second supports <NUM> and <NUM> in <FIG>, and the grooved rollers 21Aa, 21Ab, 21Bb, and 21Bb are attached to the left side of the body in <FIG>.

Each of the multiple recording heads <NUM> includes the ridged rails 11a and 11b and the flat rail <NUM> in accordance with the arrangement of the grooved rollers 21Aa, 21Ab, 21Bb, and 21Bb and the columnar rollers 22A and 22B in the first and second supports <NUM> and <NUM>. With this configuration, the adjustment roller 57a of the first support <NUM> and the adjustment roller 56a of the second support <NUM> constantly receive force from the recording head <NUM> against the pushing force of the adjustment rollers 56a and 57a. The force acts downward in <FIG> and to the right in <FIG>. In other words, the discharge angle adjusters <NUM> and <NUM> include the adjustment rollers 56a and 57a as pushing members to push the recording head <NUM> against the force received from the weight of the recording head <NUM>, respectively. Thus, the discharge angle adjusters <NUM> and <NUM> described above have a relatively simple configuration.

In the image forming apparatus <NUM> according to the present embodiment, the plurality of recording-head position adjustment mechanisms <NUM> and the plurality of recording heads 10Y, <NUM>, 10C, <NUM>, 10S1, and 10S2 are radially arranged side by side along the curved surface (outer circumferential surface) of the conveyance drum <NUM>. Therefore, the image forming apparatus <NUM> can adopt such a configuration described above.

As described above, the recording-head position adjustment mechanism <NUM> (image forming apparatus <NUM>) according to the present embodiment adjusts the position of the recording head <NUM> that discharges liquid droplets. The recording-head position adjustment mechanism <NUM> includes the supporting member <NUM> (first support <NUM> and second support <NUM>) including the first and second upper grooved rollers 21Aa and 21Ba (upper supports) to support the upper portion of the recording head <NUM>, and the first and second lower grooved rollers 21Ab and 21Bb (lower supports) to support the lower portion of the recording head <NUM>. The recording-head position adjustment mechanism <NUM> further includes the discharge angle adjusters <NUM> and <NUM>. The discharge angle adjusters <NUM> and <NUM> swing the lower portion of the recording head <NUM> around the upper portion W supported by the first and second upper grooved rollers 21Aa and 21Ba as a fulcrum to adjust the direction (discharge angle β) of the liquid droplets discharged from the recording head <NUM>.

With this configuration, the discharge direction of the liquid droplets from the recording head <NUM> can be easily adjusted without complicated configuration. In the above-described embodiments, the image forming apparatus <NUM> includes the six recording heads 10Y, <NUM>, 10C, <NUM>, 10S1, and 10S2. However, the number of recording heads is not limited to six but may be any suitable number.

Further, in the above-described embodiments, the plurality of recording heads 10Y, <NUM>, 10C, <NUM>, 10S1 and 10S2 are arranged in a radial pattern (on a curved surface) along the outer circumferential surface of the conveyance drum <NUM>. However, when the sheet P is conveyed on a flat conveyance surface, a plurality of recording heads can be flatly arranged side by side along the flat conveyance surface.

In the present embodiment, the discharge angle adjuster <NUM> in the first support <NUM> and the discharge angle adjuster <NUM> in the second support <NUM> have different configurations. Alternatively, a discharge angle adjuster in the first support <NUM> and a discharge angle adjuster in the second support <NUM> may have the same configuration. The discharge angle adjusters <NUM> and <NUM> are not limited to the above-described embodiments, and various types of configurations can be used.

In such configurations, effects similar to those described above are also attained.

Further, in the above-described embodiments, the recording head <NUM> and the recording-head position adjustment mechanism <NUM> including the first and second supports <NUM> and <NUM>, the base frame <NUM>, the side frames <NUM> and <NUM> can be unitized and construct a recording-head module <NUM>. In that case, the recording-head module <NUM> is removably installed in the image forming apparatus <NUM> in a single construction.

Further, in that case, the image forming apparatus <NUM> may include the recording-head module <NUM> in which a plurality of recording-head position adjustment mechanisms <NUM> and the plurality of recording heads 10Y, <NUM>, 10C, <NUM>, 10S1 and 10S2 are unitized.

In the above-described embodiment, the first and second supports <NUM> and <NUM> includes the first and second lower grooved rollers 21Ab and 21Bb as the lower supports, and the recording head <NUM> includes the ridged rail 11b that is pushed by the discharge angle adjusters <NUM> and <NUM> as described above with reference to <FIG>. In order to smoothly swing the recording head <NUM> around the upper portion W (see <FIG>), the first and second lower grooved rollers 21Ab and 21Bb (lower supports) are disposed in the first and second supports <NUM> and <NUM>, respectively, so as to be movable in the left-right direction in <FIG>, or a play (backlash) in the left-right direction in <FIG> is provided between the first and second lower grooved rollers 21Ab and 21Bb (lower supports) and the ridged rail 11b.

Alternatively, in order to smoothly swing the recording head <NUM> around the upper portion W, as illustrated in <FIG>, the first and second supports <NUM> and <NUM> may include columnar rollers 21Ab' and 21Bb' as lower supports, respectively, and the recording head <NUM> may include a flat rail 11b'.

As described above, according to the present disclosure, the recording-head position adjustment mechanism, the recording-head module, and the image forming apparatus can be provided that can easily adjust the discharge direction of the liquid droplets from the recording head without the complicated configuration.

Claim 1:
A recording-head position adjustment mechanism (<NUM>) configured to adjust a position of a recording head (<NUM>) that discharges liquid droplets, the recording-head position adjustment mechanism (<NUM>) comprising:
a supporting member (<NUM>) including:
an upper support (21Aa; 21Ba) configured to support an upper portion of the recording head (<NUM>); and
a lower support (21Ab; 21Bb) configured to support a lower portion of the recording head (<NUM>); and
a discharge angle adjuster (<NUM>; <NUM>) configured to swing the lower portion around the upper portion as a fulcrum to adjust a discharge direction of the liquid droplets from the recording head (<NUM>);
characterized in that the upper support comprises grooved rollers; and
that the grooved rollers are further configured to guide the recording head in a predetermined direction during installation and removal.