JP5702627B2 - Inkjet printer - Google Patents

Description

  The present invention relates to an ink jet printer, and more particularly to an ink jet printer having a plurality of two-dimensionally arranged ink jet heads with respect to a head holder surface such that ink discharge ports protrude from the head holder surface.

  As an ink jet method, there is a full line type in which a recording medium such as printing paper is recorded only by sub-scanning in the transport direction. With this full line type, recording for one line is continuously performed on the recording medium. To do.

  By the way, in recent printing apparatuses, various requests such as elaboration of printed images, multi-functionality of the apparatus, and miniaturization are high, and it is necessary to install inkjet heads having a complicated configuration of high-density pixels close to each other. When droplets (mist) other than the main droplets ejected from the inkjet head are generated, the mist has a relatively small mass and speed, so that it does not reach the printing paper and floats directly to another head. Or may adhere to the head holder. This causes problems such as image deterioration of the recording medium, ink ejection failure, and in-machine contamination with ink. This adverse effect becomes more prominent as the distance between the ink discharge port of the inkjet head and the printing paper increases.

  As a countermeasure, in Patent Document 1, a head holder surface is arranged on the recording medium conveyance path so as to face the conveyance path, and a plurality of inkjet heads are arranged so that the ink discharge ports protrude from the head holder surface. It has been proposed.

JP 2010-83013 A

  However, even if the above measures are taken, the airflow at the downstream inkjet head changes compared to the airflow at the upstreammost inkjet head in the transport direction. For this reason, it is preferable to take further measures.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an ink jet printer in which an air flow between an ink jet head and a recording medium conveyance path is stabilized.

  In order to achieve the above object, a first feature of an ink jet printer according to the present invention includes a transport path for transporting a recording medium, a head holder having a head holder surface disposed so as to face the transport path, and the head. A plurality of ink-jet heads arranged in a two-dimensional manner with respect to the head holder surface so that an ink discharge port protrudes from the head-holder surface; An airflow stabilization unit that stabilizes an airflow flowing from the upstream side of the conveyance into the gap between the holder surface and the conveyance path is provided.

  A second feature of the ink jet printer according to the present invention is that a gap adjusting means for adjusting a gap between the transport path and the ink jet head is provided, and the airflow stabilizing unit is an opening on the transport upstream side of the gap. The present invention is configured to shield the portion and change the shielding area in accordance with the change of the gap.

  A third feature of the ink jet printer according to the present invention is that the airflow stabilization unit includes an airflow stabilization auxiliary unit that is movable relative to the main body of the airflow stabilization unit in an up-and-down direction. It exists in a body and it exists in being controlled so that the up-down direction position of the said airflow stabilization assistance part is changed according to the change of the said gap.

  A fourth feature of the ink jet printer according to the present invention is that an upstream and downstream position variable deformation detection sensor for detecting deformation of a recording medium is provided on the upstream side of the conveyance of the ink jet head, and the deformation detection sensor is provided on the ink jet head. A oscillating portion pivotally supported about an axis parallel to the main scanning direction is provided, and the deformation of the recording medium is detected by the oscillating portion of the oscillating portion. By providing the stabilization part, an allowable gap is formed between the airflow stabilization part and the transport path.

  A fifth feature of the ink jet printer according to the present invention is that the allowable gap is adjusted by controlling the vertical position of the swinging portion in accordance with the change of the gap.

  According to the first feature of the ink jet printer according to the present invention, by providing the air flow stabilizing unit on the upstream side of the conveyance of the inkjet head, the air flow flowing from the upstream side of the conveyance to the gap between the head holder surface and the conveyance path is stabilized. Therefore, the airflow in the gap between the inkjet head and the recording medium conveyance path can be stabilized.

  According to the second feature of the ink jet printer according to the present invention, the airflow stabilizing unit shields a part of the opening on the transport upstream side of the gap, and shields according to the change of the gap between the ink jet head and the transport path. Since the area is changed, the airflow in the gap between the inkjet head and the conveyance path can be adjusted in more detail and stabilized.

  According to the third feature of the ink jet printer according to the present invention, the airflow stabilization unit includes an airflow stabilization auxiliary unit that is movable relative to the main body of the airflow stabilization unit in an up-and-down direction. Since the vertical position of the airflow stabilization assisting part is controlled according to the change of the gap, the gap and the distance between the airflow stabilization assisting part and the conveyance path are individually set. Can be adjusted.

  According to the fourth feature of the ink jet printer according to the present invention, the airflow stabilizing portion is provided in the swinging portion of the deformation detection sensor, so that an allowable gap is formed between the airflow stabilizing portion and the conveyance path. Therefore, the recording medium passing therethrough can be limited to a recording medium having a height equal to or smaller than the permissible gap, and it is not necessary to provide two components, that is, a normal deformation detection sensor and an airflow stabilization unit. Therefore, the components of the printer unit can be reduced.

  According to the fifth feature of the ink jet printer according to the present invention, since the permissible gap is adjusted by controlling the vertical position of the oscillating portion according to the change of the gap, the recording to be conveyed even if the gap fluctuates. An allowable gap can be set according to the medium.

It is explanatory drawing which shows schematic structure of the line type inkjet printer which concerns on 1st Embodiment. In the first embodiment, (a) is a schematic partial side cross-sectional view of an ink jet printer, and (b) is an explanatory view viewed from the arrow PP of (a). In 1st Embodiment, it is explanatory drawing which shows the flow of the airflow in a head holder surface. In 1st Embodiment, it is a side view which shows the structure of a deformation | transformation detection sensor. It is a modification of a 1st embodiment, and is an explanatory view showing a flow of air current on a head holder surface. In the second embodiment, (a) is a schematic partial side sectional view of an ink jet printer, and (b) is an explanatory view as viewed from the arrow Q-Q in (a). It is a partial expansion perspective view of the inkjet printer which concerns on 3rd Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Throughout the drawings, the same or equivalent parts and components are denoted by the same or equivalent reference numerals, and the description thereof is omitted or simplified. Also, it should be noted that the drawings are schematic and different from the actual ones. Further, the embodiment described below exemplifies an apparatus for embodying the technical idea of the present invention, and the technical idea of the present invention is not limited to this.

[First Embodiment]
First, the first embodiment will be described. In the following description, an example will be described in which recording paper is used as a recording medium, plain paper is mainly used as a recording medium with a small thickness, and envelopes are mainly used as a recording medium with a large thickness.

  FIG. 1 is an explanatory diagram showing a schematic configuration of a line type ink jet printer according to the present embodiment. As shown in FIG. 1, a line type ink jet printer 1 (hereinafter simply referred to as an ink jet printer 1) according to the present embodiment includes a control unit 10, a paper feed unit 101, a printer unit 102, and the like inside and outside a housing 100. The display 103, the belt platen mechanism 104, the recording paper circulation conveyance path 105, and the paper discharge unit 106 are provided.

(Paper Feeder)
The sheet feeding unit 101 includes a side sheet feeding table 21 disposed on a side surface of the housing 100 and a plurality of sheet feeding tables 22 and 23 disposed in a lower left portion of the housing 100. The side paper feed tray 21 can stack recording paper S of an appropriate size (for example, envelope) while detecting the size of the recording paper S. On the other hand, the plurality of paper feed trays 22 and 23 are capable of stacking thin recording paper S (for example, plain paper) having a specific size such as A4 size or A3 size.

  The uppermost recording sheet S among the unprinted recording sheets S stacked on the side sheet feeding table 21 or the plurality of sheet feeding tables 22 and 23 is fed one by one by each sheet feeding roller 24. After that, the leading portion of the recording sheet S that has been fed along the sheet feeding and conveying path KR by the driving mechanism such as a roller is guided to a registration roller pair 81 provided in the recording sheet circulating and conveying path 105. The registration roller pair 81 adjusts the timing so that the leading positions of the recording sheets S are aligned.

(Printer part)
The printer unit 102 is installed on the downstream side of the paper feeding unit 101 and on the upstream side of the recording paper circulation conveyance path unit 105, and is fixed to the housing 100 at a substantially central portion in the housing 100. .

  In the printer unit 102, a plurality of line-type inkjet heads 31 (hereinafter simply referred to as heads 31) corresponding to a plurality of colors of ink are used for C (cyan) and K (black) from the upstream side toward the downstream side. , M (magenta) and Y (yellow). That is, from the upstream side toward the downstream side, the cyan head 31C, the black head 31K, the magenta head 31M, and the yellow head 31Y are arranged in this order. A plurality of such combinations are arranged in parallel to each other on the side (main scanning direction side) orthogonal to the transport direction.

  The heads 31 of the respective colors are attached to the head holder 32 and are arranged at equal intervals in the conveyance direction X of the recording paper S by the belt platen mechanism unit 104. Each head 31 has an ink ejection surface 31F (a surface on which a large number of ink ejection ports are formed) formed on the lower surface side, and ink of each color is ejected from each ink ejection surface 31F.

  In this embodiment, an example in which four heads 31 are installed corresponding to four color (CKMY) inks will be described. However, for example, when only characters are printed, only one color (K) may be used. As for the head 31, one corresponding to at least one color may be installed.

  The head holder 32 is provided with a head gap adjusting unit 33 that suspends and supports the belt platen mechanism 104 so as to be lifted and lowered. The head gap adjustment unit 33 includes a head gap adjustment mechanism 34 having a pulley 33P and a wire W, and a motor 35. Then, the pulley 35P is rotated by the motor 35 to wind and unwind the wire W, so that the belt platen mechanism 104 connected to the wire W and supported by being suspended is lifted and lowered. Therefore, the belt platen mechanism 104 is structurally separated from the housing 100.

  The head gap adjustment unit 33 is connected to the control unit 10 as a part of the printer unit 102 and is driven by the control of the control unit 10. The belt platen mechanism 104 is moved up and down by the head gap adjusting unit 33, for example, when the print mode is changed according to the type of the recording paper S. As an example, when a printing mode for printing on an envelope having a paper thickness larger than that of plain paper is selected, the control unit 10 lowers the belt platen mechanism unit 104, and the head 31 and the belt platen mechanism unit 104. In this case, a gap G (head gap), which is an interval between a belt conveyance path 41R (hereinafter, simply referred to as a conveyance path 41R) formed by a conveyance belt 41 described later, is increased than usual.

(Arrangement of inkjet head and airflow stabilization unit)
FIG. 2A is a schematic partial side sectional view of the ink jet printer 1, and FIG. 2B is a bottom view seen from the arrow PP in FIG. 2A.

  The printer unit 102 has a head holder surface 32F disposed on the transport path 41R so as to face the transport path 41R. A plurality of heads 31 of the printer unit 102 are two-dimensionally arranged with respect to the head holder surface 32F so that the ink discharge surface 31F protrudes from the head holder surface 32F. In the present embodiment, the head 31 is disposed along the transport direction X (that is, along the sub-scanning direction XR), and along the direction orthogonal to the transport direction X (that is, along the main scanning direction YR). Heads 31 are arranged.

  More specifically, as shown in FIG. 2B, the head 31 is formed with a plurality of head rows L1, L2, L3... In the main scanning direction YR, and each head row L1, L2, L3. A portion b1 that does not overlap each other is formed in the scanning direction YR. The plurality of head rows L1, L2, L3,... Are arranged in a staggered manner so that a portion b2 overlapping with other adjacent rows is generated in the transport direction X (sub-scanning direction XR).

  FIG. 3 is an explanatory diagram showing the flow of airflow on the head holder surface in the first embodiment. As shown in FIG. 3, each of the head rows L1, L2, L3... Is arranged at a predetermined interval in the transport direction X, and a main scanning flow path MR is formed between the rows. Adjacent heads are arranged at a predetermined interval to form a sub-scanning flow path SR between the heads. The main scanning channel MR and the sub-scanning channel SR communicate with each other to form a mesh-like mist discharge channel. As shown in FIG. 2A, when the protrusion length H of the head 31 from the head holder surface 32F is larger than the width L of the main scanning flow path, the mist discharge path is also spread in the height direction. It is preferable.

  As shown in FIGS. 2 and 3, in the present embodiment, a plurality of airflow stabilizing portions 50 are disposed on the upstream side of the head row L1 in the transport direction X so as to protrude from the head holder surface 32F. ing. The airflow stabilizing unit 50 stabilizes the airflow F flowing from the upstream side of the conveyance into the gap T between the head holder surface 32F and the conveyance path 41R (the space portion sandwiched between the head holder surface 32F and the conveyance path 41R). Is provided. The airflow stabilizing unit 50 is a member protruding from the head holder surface 32F of a member 49 (see, for example, FIG. 2A) that is different from the member that forms the head holder surface 32F. ) Or may be provided integrally with the head holder surface 32F.

  The size of the airflow stabilizing unit 50 is the same as that of the protruding portion 31P of the head 31 from the head holder surface 32F. And the arrangement position of the airflow stabilization part 50 is made into the position which forms the row | line | column which becomes object with the head row | line | column L2 arrange | positioned immediately downstream with respect to the most upstream head row | line | column L1. More specifically, the downstream side of the head row L3 with respect to the head row L2 is the upstream side of the head row L1, and the airflow stabilization unit 50 determines whether the head row L2 and the target side of the head row L1. Are arranged to form a row K. Therefore, the airflow stabilization unit 50 looks like a pseudo head in dimension.

(Deformation detection sensor)
FIG. 4 is a side view showing the configuration of the deformation detection sensor in the first embodiment. As shown in FIG. 4, the printer unit 102 has a leading edge ST of the recording sheet S when the gap G becomes a small set value between a step guide roller 47 described later and an SS roller 72 described later. A deformation detection sensor 51 that detects deformation is provided. Specifically, the deformation detection sensor 51 detects a swinging portion 51y having a crank-like side view that is pivotally supported around an axis orthogonal to the transport direction X, and swinging of the swinging portion 51y. And a swing sensor unit 51s.

  As shown in FIG. 4, when the recording paper S is not in contact with the swinging portion 51y, the lower end of the swinging portion 51y has an allowable gap B that defines the recording paper S that can pass between the conveyance path 41R. While being formed, it is separated from the SS roller 72 by a distance A in the transport direction X. Then, after the deformed recording sheet S passes the SS roller 72, the leading end ST is lifted and comes into contact with the swing part 51y, and when the swing part 51y is pushed forward and swings, the swing part 51y is moved. It leaves | separates from the rocking | swiveling sensor part 51s. As a result, it is detected that the deformation of the recording paper S exceeds the allowable value. When this detection is performed, a detection signal is transmitted to the control unit 10, and the control unit 10 stops the conveyance. The recording paper S may be discharged without stopping.

(Belt platen mechanism)
The belt platen mechanism unit 104 is disposed below the heads 31 so as to face the printer unit 102.

  In this belt platen mechanism unit 104, in order to convey an unprinted recording sheet S fed by the sheet feeding unit 101 or a recording sheet S on which one side conveyed by a circulating conveyance path JR described later is mounted. An endless belt-like transport belt (belt platen) 41 having a plurality of suction holes (not shown) is stretched between a drive pulley 72 and a driven pulley 73 that are driven to rotate by a motor 75. A conveyance path 41 </ b> R is formed by the conveyance belt 41. The transport path 41R constitutes a part of a later-described circulation transport path JR.

  The moving speed of the conveying belt 41 by the motor 75, that is, the conveying speed of the recording paper S by the conveying belt 41 can be detected by the control unit 10 by the output of the encoder 77. Between the driving pulley 72 and the driven pulley 73, a suction fan 74 for generating a negative pressure for sucking the recording paper S onto the conveying belt 41 is provided.

  The conveyor belt 41 has a plurality of suction holes (not shown) communicating with the above-described suction fan 74 arranged on the back side thereof. A suction force generated by the suction fan 74 is supplied to the suction hole. Therefore, a suction force toward the transport belt 41 due to the negative pressure of the suction hole blocked by the recording paper S acts on the recording paper S on the transport belt 41.

  In the belt platen mechanism 104, when the recording paper S is mounted on the belt-like transport belt 41, the recording paper S is sucked by air through the suction holes on the transport belt 41, and the recording paper S is transported by the transport belt 41. The recording paper S is transported in the transport direction X (sub-scanning direction XR) by the rotation of the transport belt 41 while being fixed on the top. The recording sheet S being transported is printed in full color by a plurality of heads 31 of the printer unit 102 disposed above the passage path.

  In the belt platen mechanism 104, an SS roller 72 that abuts the transport path 41R is disposed upstream of the stepped guide roller 47 described later. The SS roller 72 is a pressing roller that presses the central portion of the recording paper S that is transported through the transport path 41R. Specifically, it is a roller in which the central portion of the recording sheet S is mainly pressed at the central portion, and grooves having narrow diameters are formed at both ends. By the SS roller 72, the recording paper S is adsorbed to the transport belt 41 so that there is no gap.

  As shown in FIG. 2, a stepped guide roller 47 is provided in each main scanning flow path MR. The stepped guide roller 47 is formed as a single roller by connecting guide rollers having different diameters, and is formed by cutting a metal rod, for example. Specifically, the stepped guide roller 47 is formed by alternately connecting an upstream guide roller 47a having a large diameter and a downstream guide roller 47b having a diameter smaller than that of the upstream guide roller 47a on the same rotation shaft. The arrangement is arranged.

  The upstream guide roller 47a is provided on the upstream side of each head 31 in the transport direction X, is urged downward, is pressed against the upper surface of the transport path, and rotates. On the other hand, the downstream guide roller 47b is provided on the downstream side of each head 31 in the transport direction X, and is rotatably supported at a predetermined distance from the upper surface of the transport path.

  In correspondence with the staggered arrangement of the heads, the upstream guide roller 47a and the downstream guide roller 47b are also arranged in a staggered manner. Further, since the stepped guide roller 47 is arranged in the main scanning flow path MR, the upstream guide roller 47a and the downstream guide roller 47b are also arranged alternately in the main scanning flow path MR. Become. In the present embodiment, the stepped guide roller 47 is rotatably supported by bearings 48 disposed on both sides of the head holder surface 32F, and has an integrated structure with the head holder 32.

  As shown in FIG. 4, a stepped guide roller 47 may be further disposed between the deformation detection sensor 51 and the airflow stabilization unit 50. Accordingly, it is possible to effectively suppress the recording paper S that has passed through the allowable gap B from being lifted before passing through the airflow stabilization unit 50.

(Recording paper circulation transport path)
The recording paper circulation conveyance path unit 105 circulates the recording paper S through the printer unit 102 for one-sided printing or double-sided printing by the printer unit 102 with respect to the recording sheet S fed by the paper feeding unit 101. It has a conveyance path JR. Then, a paper feed transport path KR that transports the unprinted recording paper S from the side paper feed tray 21 side in this circulation transport path JR, and a paper discharge that transports the printed recording paper S to the paper discharge tray 91 side. The conveyance path HR is branched and installed.

  In addition, the above-described circulation conveyance path JR includes a normal conveyance path CR that conveys the printed recording paper S printed on one side (front surface) of the recording paper S by the printer unit 102 as it is, and a single side (front surface). ) Printed on the recording paper S is switched from the middle of the normal conveyance path CR by switching the conveyance direction by the first and second conveyance path switching levers 82 and 83 using an electromagnetic valve or the like. ) And a switchback transport path SR for printing.

  The recording sheet S that is desired to be printed on both sides can be circulated through the printer unit 102 by the circulation conveyance path JR.

  At this time, the normal conveyance path CR in the circulation conveyance path JR passes below the printer unit 102, and thereafter, above the printer unit 102 in order to secure time for drying the ink on the printed recording paper S. The printed recording sheet S to be discharged is conveyed from the normal conveyance path CR to the discharge table 91 of the discharge unit 106 via the discharge conveyance path HR. Yes.

  On the other hand, the switchback transport path SR in the circulation transport path JR is changed by changing the transport direction of the recording paper S by switching the front of the normal transport path CR toward the paper discharge unit 106 with the first transport path switching lever 82. The recording paper guide frame 92 formed on the back surface of the paper discharge tray 91 of the paper section 106 is directed to the recording paper guide frame 92, and the leading position of the recording paper S is reversed in the recording paper guide frame 92. The recording paper S is switched to change the conveyance direction of the recording paper S so that the recording paper S is directed again to the registration roller pair 81.

  Further, in the recording paper circulation conveyance path section 105, light reflection type (or light transmission type) first to fourth recording paper detection optical sensors 84 to 87 are installed. The first recording paper detection optical sensor 84 is installed downstream of the registration roller pair 81 in the paper feed conveyance path KR and functions as a paper feed sensor that detects the paper feed state of the recording paper S. The first recording paper detection optical sensor 84 is configured by a line sensor having a dimension equal to or larger than the maximum width in the main scanning direction of the recording paper S fed by the paper feeding unit 101. Therefore, the first recording sheet detection optical sensor 84 detects the size of the recording sheet S from the size in the main scanning direction of the recording sheet S fed by the sheet feeding unit 101 and the passage time of the recording sheet S. It also functions as a paper size sensor (contact image sensor: CIS).

  The second recording paper detection optical sensor 85 functions as a transport path pre-switch sensor that detects a state before the recording paper S reaches the paper discharge transport path HR or the switchback transport path SR. The detection optical sensor 86 is installed along the paper discharge conveyance path HR and functions as a paper discharge sensor for detecting the paper discharge state of the recording paper S toward the paper discharge tray 91, and further, a fourth recording paper detection optical sensor. Reference numeral 87 denotes a circulating recording sheet presence / absence detection sensor that is installed between the first conveying path switching lever 82 and the second conveying path switching lever 83 and detects the presence / absence state of the recording sheet S being circulated.

(Output section)
The paper discharge unit 106 includes a paper discharge table 91 that is installed obliquely with respect to the housing 100.

  The paper discharge tray 91 has a function of storing the printed recording paper S transported by the normal transport path CR and the paper discharge transport path HR provided in the recording paper circulation transport path section 105, and The recording paper guide frame 92 formed on the back surface has a function of switching back and reversing the leading position of the recording paper S to print the back surface of the recording paper S printed on one side (front surface).

(Function, effect)
Hereinafter, the operation and effect of the present embodiment will be described. Of the airflow flowing from the upstream side of the conveyance into the gap T between the head holder surface 32F and the conveyance path 41R, the zone AR above the lower surface of the airflow stabilization unit 50 (the side of the head holder surface 32F) (FIG. 2A). In FIG. 3, as shown in FIG. 3, the flow is blocked by the airflow stabilization unit 50 in the row K, and the airflow flows through the spaces on both sides of the airflow stabilization unit 50 as flow paths. The airflow F is blocked by the head 31 of the head row L1, and the airflow F flows as a flow path in the space on both sides of each head 31 of the head row L1.

  Therefore, compared with the conventional example in which the airflow flows into the gap T from the upstream side of the conveyance and the flow is blocked by the head 31 of the head row L1, the airflow F on the downstream side of the conveyance from the airflow stabilization unit 50 is much stabilized. Can do. And since the airflow stabilization part 50 is arranged so that it may become zigzag like each head 31, this effect becomes more remarkable. Moreover, in the present embodiment, the airflow stabilizing unit 50 and the protruding portion 31P (see FIG. 2A) of the head 31 have the same dimensions. Therefore, the air flow in each head row can be made equal with a simple configuration. Note that these are particularly significant improvements in the air flow F when reaching the head row L1, and the ink droplets from the head row L1 are similar to the central portion of the head holder surface 32F and the head row on the downstream side thereof. To fly stably.

  By stabilizing the airflow F in the gap T in this way, problems such as image smearing and in-machine contamination due to mist are greatly reduced, and the ink droplet landing position accuracy is greatly improved. In addition, this effect can be obtained when the gap G is small or when the gap G is large, but becomes remarkable when the gap G is large.

  In the present embodiment, as shown in FIG. 5, a second airflow stabilization unit 52 may be further arranged on the upstream side of the airflow stabilization unit 50 that forms the row K. The arrangement position of the second airflow stabilization unit 52 is a position that is the target of the head 31 of the head row L1 arranged immediately downstream of the most upstream row K, and is arranged in a staggered manner. Has been. By arranging the second airflow stabilization unit 52 in such a staggered arrangement in this way, the airflow F when reaching the head row L1 becomes much more stable. This configuration is particularly effective when the airflow F is difficult to stabilize for reasons such as high speed.

  In this embodiment, the airflow stabilization unit 50 is provided in the printer unit 102. However, the airflow stabilization unit 50 is provided in the belt platen mechanism unit 104, and the airflow stabilization unit 50 is linked to the change in the gap G. The vertical position of the stabilization unit 50 may be controlled by the control unit 10.

  In the present embodiment, the airflow stabilizing unit 50 is described as having the same size as the protruding portion 31P of the head 31, but the airflow stabilizing unit 50 is not the same size as the protruding portion 31P. Even if the thickness is smaller or larger than 31P, the effect of stabilizing the air flow F in the gap T can be obtained.

[Second Embodiment]
Next, a second embodiment will be described. FIG. 6A is a schematic partial side sectional view of the ink jet printer 1 according to the present embodiment, and FIG. 6B is a bottom view as viewed from the arrow Q-Q in FIG. is there.

  In the present embodiment, an airflow stabilization unit 60 is provided instead of the airflow stabilization unit 50 as compared to the first embodiment. The airflow stabilization unit 60 includes a main body 60M and an airflow stabilization auxiliary unit 60S attached to the main body 60M. The airflow stabilization assisting unit 60S shields a part of the opening TF in the gap T between the transport path 41R and the head holder surface 32F, and the vertical position of the main body 60M can be moved relative to the main body 60M. Is attached.

  The airflow stabilization assisting portion 60S extends in parallel with the head holder surface 32F (that is, extends in parallel with the conveyance path 41R), and the upward extension extending upward from the upstream edge of the parallel plate portion 60a. And has an L-shape in side view. In the present embodiment, the control unit 10 controls so that the vertical position of the airflow stabilization assisting unit 60S is set in conjunction with the change in the gap G. In addition, it is not necessary to make the fluctuation amount of the distance between the conveyance path 41R and the airflow stabilization auxiliary unit 60S coincide with the fluctuation amount of the gap G, and the airflow F in the gap T in the gap G after the change is further stabilized. Thus, the opening area of the opening TF is adjusted by adjusting the vertical position of the airflow stabilization assisting part 60S.

  Note that the attached member of the airflow stabilization auxiliary unit 60S is not necessarily the main body 60M of the airflow stabilization unit 50, and another member may be provided to attach the airflow stabilization auxiliary unit 60S to the member.

(Function, effect)
Hereinafter, the operation and effect of the present embodiment will be described. When the recording paper S (see FIG. 4) is a thin paper such as plain paper, the selection is input on the display 103. As a result, a command from the control unit 10 is transmitted to the head gap adjusting unit 33, the pulley 33P is rotated by the motor 35, the wire W is wound up, and the belt platen mechanism 104 is raised. Then, when the gap G reaches a predetermined set value (gap value for thin recording paper), the rotation of the motor 35 stops, and the belt platen mechanism unit 104 stops rising. This set value is a value preset in the control unit 10.

  Along with this rise, the airflow stabilization assistant 60S also rises, and when the airflow stabilization assistant 60S reaches the set position corresponding to the gap G, the rise of the airflow stabilization assistant 60S stops. When the airflow stabilization assisting unit 60S is located at this set position, the opening area of the opening TF is adjusted so that the airflow F in the gap T when the gap G is small is further stabilized. This setting position is also a position set in advance in the control unit 10.

  Even when the recording sheet S is a thick sheet such as an envelope, the selection is input on the display 103. As a result, a command from the control unit 10 is transmitted to the head gap adjustment unit 33, the pulley 33P is rotated by the motor 35, the wire W is unwound, and the belt platen mechanism 104 is lowered. Then, when the gap G reaches a predetermined set value (gap value for thick recording paper), the rotation of the motor 35 is stopped, so that the lowering of the belt platen mechanism unit 104 is stopped. This set value is also a value preset in the control unit 10.

  Along with this lowering, the airflow stabilization assisting unit 60S is also lowered, and when the airflow stabilization assisting unit 60S reaches the set position corresponding to the gap G, the lowering of the airflow stabilization assisting unit 60S stops. By positioning the airflow stabilization assisting unit 60S at this set position, the opening area of the opening TF is adjusted so that the airflow F in the gap T when the gap G is large is further stabilized. This setting position is also a position set in advance in the control unit 10.

  Thus, in the present embodiment, the adjustment of the vertical position of the airflow stabilization assisting unit 60S in order to adjust the opening area of the opening TF is performed in conjunction with the change of the gap G. Thereby, compared with 1st Embodiment, the airflow F in the clearance gap T can be adjusted and stabilized more in detail. When the gap G is expanded, the space around the head is expanded compared to when the gap G is contracted, so that the airflow around the head is increased.

  In addition, the airflow stabilization auxiliary portion 60S is attached to the main body 60M so that the vertical position between the airflow stabilization auxiliary portion 60S and the main body 60M can be relatively moved. Thereby, it is not necessary to separately provide a member for holding the airflow stabilization auxiliary portion 60S. Moreover, since the vertical position of the airflow stabilization assisting part 60S and the main body 60M can be relatively moved, the gap G and the opening area of the opening TF can be individually adjusted.

  In the present embodiment, it has been described that the gap G is changed in a configuration in which the printer unit 102 is provided with the head gap adjustment unit 33 that suspends and supports the belt platen mechanism unit 104 so that the belt platen mechanism unit 104 can be raised and lowered. The gap G may be changed.

  Further, in consideration of the mounting structure of the airflow stabilization assisting part 60S and the main body 60M, the parallel plate part 60a of the airflow stabilization assisting part 60S extends in the horizontal direction so as to extend downstream from the airflow stabilization part 50. You may have the part 60c.

  Moreover, even if the upper extension part 60b does not shield all the arranged regions, even if an opening is partially formed from the viewpoint of stabilizing the air flow downstream from the upper extension part 60b. Good.

[Third Embodiment]
Next, a third embodiment will be described. FIG. 7 is a partially enlarged perspective view showing the vicinity of the most upstream head 31 in the transport direction in the inkjet printer according to the present embodiment.

  In the present embodiment, a deformation detection sensor 61 as shown in FIG. 7 is provided in place of the deformation detection sensor 51 (see FIG. 4) without providing the airflow stabilization unit 50 as compared with the first embodiment. The deformation detection sensor 61 includes a swing part 61y instead of the swing part 51y, and a swing sensor part 61s similar to the swing sensor part 51s. The swinging portion 61y has a crank shape in a side view, and can swing around a swinging shaft 61e parallel to the main scanning direction YR of the head 31. The swinging portion 61y includes a horizontal plate portion 61a extending in the transport direction X from the swing sensor portion 61s and a downstream end of the horizontal plate portion 61a on the downstream side when the recording paper S is not in contact with the swinging portion 61y. A downwardly extending portion 61b extending downward from the portion.

  The downward extending portion 61b includes three airflow stabilizing portions 70 arranged in parallel with the head row L1. Therefore, the downward extending part 61b has a comb-like shape, and the downward extending part 61b apparently forms the airflow stabilizing part 50 of the first embodiment. The size of each airflow stabilizing unit 70 is the same as that of the protruding portion 31P from the head holder surface 32F of the head 31, and the airflow stabilizing unit 70 is disposed at the same position as the airflow stabilizing unit 50. . And the lower end of the downward extension part 61b forms the tolerance gap B which prescribes | regulates the recording paper S which can pass between the conveyance paths 41R.

  In this embodiment, the printer unit 102 is provided with a lifting / lowering unit 64 that lifts and lowers the deformation detection sensor 61 so that the deformation detection sensor 61 is lifted and lowered independently of the lifting and lowering of the belt platen mechanism unit 104. It has become. The operation of the lifting / lowering unit 64 is controlled by the control unit 10. That is, when the thin recording paper S (for example, plain paper) whose end portion is difficult to deform is used, the allowable gap B is reduced, and when the thick recording paper S (for example, envelope) whose end portion is easily deformed is used. The gap B is increased.

  According to the present embodiment, even if the airflow stabilization unit 50 is not provided, the airflow stabilization unit 70 acts to play the same role as the airflow stabilization unit 50 when the recording paper S is not touching the swinging unit 61y. Therefore, the same effect as the case where the airflow stabilization part 50 is arrange | positioned can be acquired. Therefore, the number of parts can be reduced as compared with the first embodiment.

  Further, since the elevation control of the deformation detection sensor 61 and the elevation control of the belt platen mechanism 104 can be performed independently, the change length of the gap G and the change length of the allowable gap B can be made different. Therefore, an appropriate permissible gap B is set in accordance with either a thin recording paper S (for example, plain paper) whose end is difficult to deform or a thick recording paper S (for example, envelope) whose end is easily deformed. be able to.

  The embodiments of the present invention have been described above with reference to the embodiments. However, these embodiments are merely examples, and various modifications can be made without departing from the scope of the invention.

DESCRIPTION OF SYMBOLS 1 Inkjet printer 10 Control unit 31 Head (inkjet head)
31F Ink ejection surface (ink ejection port)
31P Protruding portion 32 Head holder 32F Head holder surface 33 Head gap adjusting unit (head gap adjusting means)
41R Conveyance path 50 Airflow stabilization unit 60 Airflow stabilization unit 60M Main body 60S Airflow stabilization auxiliary unit 61 Deformation detection sensor 61y Oscillating unit 70 Airflow stabilization unit 102 Printer unit 104 Belt platen mechanism G Gap YR Main scanning direction T Gap F Airflow B Allowable gap S Recording paper (recording medium)
TF opening

Claims (6)

A conveyance path for conveying the recording medium;
A head holder that arranges a head holder surface so as to face the transport path;
A plurality of ink jet heads provided in the head holder, and two-dimensionally arranged with respect to the head holder surface such that an ink discharge port protrudes from the head holder surface;
An airflow stabilization unit that is provided on the upstream side of transport of the inkjet head, and stabilizes the airflow that flows from the upstream side of transport into the gap between the head holder surface and the transport path;
Equipped with a,
The size of the airflow stabilizing portion is the same as the protruding portion of the inkjet head from the head holder surface,
2. The ink jet printer according to claim 1, wherein the arrangement position of the airflow stabilization unit is a position where an ink jet head row arranged immediately downstream of the uppermost ink jet head row and a target row are formed . A second airflow stabilization unit having the same dimensions as the protruding portion of the inkjet head from the head holder surface is further arranged on the upstream side of the airflow stabilization unit.
  The arrangement position of the second airflow stabilizing unit is an inkjet head row arranged immediately downstream of the uppermost inkjet head row and a target position. Inkjet printer. Gap adjustment means for adjusting the gap between the transport path and the inkjet head is provided,
3. The air flow stabilization unit according to claim 1, wherein the airflow stabilization unit is configured to shield a part of the opening on the transport upstream side of the gap and to change a shielding area in accordance with the change of the gap. The inkjet printer as described. The airflow stabilization unit includes an airflow stabilization auxiliary unit that can move relative to the main body of the airflow stabilization unit in an up or down direction, and is provided integrally or separately from the main body.
The inkjet printer according to claim 3 , wherein the vertical position of the airflow stabilization assisting unit is controlled to be changed according to the change of the gap. On the upstream side of conveyance of the inkjet head, a deformation detection sensor with a variable vertical position that detects deformation of the recording medium is provided,
The deformation detection sensor has a swinging portion pivotally supported so as to be swingable about an axis parallel to the main scanning direction of the inkjet head, and detects deformation of the recording medium by the swinging of the swinging portion. And
The said airflow stabilization part is provided in the said rocking | swiveling part, The tolerance gap is formed between the said airflow stabilization part and the said conveyance path, The Claim 3 or 4 characterized by the above-mentioned. Inkjet printer. The inkjet printer according to claim 5 , wherein the allowable gap is adjusted by controlling a vertical position of the swinging portion according to the change of the gap.

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