JP4310673B2 - Printer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a printer including a print head whose print operation range extends in a main scanning direction, and a conveyance belt that is rotationally driven along a sub-scanning direction that intersects the main scanning direction. Here, the transport belt transports the printing paper adsorbed and supported on the peripheral surface of the transport belt in the sub-scanning direction within a transport surface separated from the print head.
[0002]
[Prior art]
An example of the above type of printer is an inkjet printer. In an inkjet printer, in order to make ink fly from the print head toward the print paper, it is not possible to use a configuration in which the print paper is pressed against the print head, and the print paper is transported in a transport surface that is separated from the print head. It is necessary to In order to correctly form a high-resolution image on the printing paper, the distance between the print head and the printing paper, in other words, the distance from the nozzle from which the ink droplets are ejected to the printing paper is about 0.5 mm, for example. It is necessary to keep it at a constant value.
[0003]
[Problems to be solved by the invention]
However, the conventional inkjet printer has a configuration in which an endless conveyance belt configured to adsorb printing paper is simply installed between a pair of pulleys. Accordingly, the conveyance posture becomes unstable due to bending or the like at an intermediate position between the pair of pulleys, and the interval between the print head and the printing paper falls within a predetermined range. Therefore, there is a possibility that a correct image is not formed.
[0004]
Therefore, in view of the above-mentioned drawbacks of the prior art printers exemplified above, the object of the present invention is to be able to form a more stable and correct image even when used under various unfavorable conditions. To provide a printer.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, a printer according to the present invention has the characteristic structure described in claims 1 to 8.
That is, the printer according to claim 1 of the present invention is
A belt support member for supporting a portion of the transport belt facing the print head toward the print head; and a constant distance between the belt support member and the print head to maintain a constant distance from the print head. An interval holding member protruding toward the belt support member, a support mechanism for supporting the belt support member so as to be displaceable in a direction intersecting the transport surface, and pressing and holding the belt support member on the interval holding member side And an urging means for the purpose .
[0006]
Due to such a characteristic configuration, in the printer according to claim 1 of the present invention, for example, a phenomenon such as bending of the conveyance belt occurs due to a decrease in the tension of the conveyance belt based on a change with time. However, since the portion of the conveying belt facing the print head is supported by the belt support member toward the print head, the distance between the print head and the printing paper can be easily maintained, so that a more correct image is formed. Even if the mounting position accuracy of the print head or the mounting position accuracy between the pulley and the conveyor belt is insufficient, the print head is always provided by the biasing means while being displaceable in the direction intersecting the transport surface. By the effect exerted by the cooperative action of the belt support member pressed toward the print head and the interval holding member provided in the print head in order to keep the interval between the pressed belt support member and the print head constant, Since the interval between the print head and the printing paper is easily kept constant, a more accurate image is formed.
[0009]
In addition, a first pulley that supports the conveyor belt on the upstream side of the print head on the rotation driving track of the conveyor belt and a second pulley that supports the conveyor belt on the downstream side of the print head are provided. And the belt support member is configured such that the portion of the conveying belt that faces the print head is more than the virtual conveying surface that is formed by the conveying belt portion that is laid between the first pulley and the second pulley. It can be set as the structure provided so that it may support in the position displaced to the print head side.
[0010]
If comprised in this way, since the said part facing the said print head of the said conveyance belt will be reliably pressed on the said belt support member by the tension | tensile_strength which acts from the surrounding surface of the said 1st pulley or the said 2nd pulley, There is less possibility that the conveyance belt is separated from the belt support member and displaced toward the print head, and as a result, the distance between the print head and the printing paper is more reliably maintained constant.
[0011]
Specifically, the belt support member is rotatably supported around a bearing member installed so as to be displaceable in a direction intersecting the transport surface, and an axis extending in parallel with the main scanning direction by the bearing member. And the biasing means may be configured by a spring capable of pressing the bearing member toward the spacing member.
According to this configuration, the pressure roller freely rolls on the surface of the conveyor belt based on the pressing force of the urging member. Therefore, the smooth movement of the conveyor belt driven by the driving roller is caused by contact friction or the like. There is little possibility of obstruction. In addition, vibrations due to friction between the two members are unlikely to occur between the spacing member and the pressure roller (as a belt support member) that are relatively displaced from each other, or between the pressure belt and the conveyance belt. The deterioration of the image due to the slight vibration of the image is prevented.
[0012]
More specifically, the spacing member can be formed of a roller member supported on the print head so as to be rotatable about an axis extending in parallel with the main scanning direction.
If comprised in this way, between the belt support member which moves relatively mutually based on the rotational drive of a conveyance belt, and a roller member (as a space | interval holding member), or the conveyance belt and roller member supported by the belt support member In the meantime, vibration based on the friction between the two members hardly occurs, so that deterioration of the image based on the fine vibration of the print head is prevented.
[0013]
Further, the roller member as the spacing member is a pair of roller members installed near both ends in the main scanning direction on the print head so that the conveyance belt is sandwiched between the roller support member and the belt support member. It can be set as the structure which becomes.
With this configuration, the roller member always presses and holds the conveyor belt against the belt support member while rolling on the conveyor belt regardless of the rotational movement of the conveyor belt. It is possible to prevent the printing paper adsorbed on the conveying belt from floating from the belt support member, and as a result, the distance between the printing paper and the print head is easily maintained. In addition, by disposing the roller members only in the vicinity of both ends in the main scanning direction, it is possible to arrange the spacing members so as not to hinder image formation by the print head. Further, since the roller member is disposed only near both ends in the main scanning direction, the roller member naturally becomes a member having a short dimension along its rotation axis, and therefore, the bearing member supporting the roller member and Thus, a roller member that rotates smoothly without causing fine vibration of the print head is realized.
[0014]
Means can be provided for applying to the pressure roller a potential having a polarity opposite to the charging polarity of the ink flying from the print head configured as an electrostatic ink jet print head toward the printing paper.
With this configuration, a configuration is realized in which the pressure roller charged to a polarity opposite to that of the ink positively attracts the ink away from the print head ejection section, thereby controlling the flying direction of the ink more accurately. As a result, a substantial improvement in resolution of the formed image can be expected.
[0015]
Various realization means for adsorbing the printing paper to the conveying belt are known. In particular, in order to adsorb the printing paper to the conveying belt by electrostatic force, the conveying belt is charged with a specific potential polarity. The charging device may be provided on the upstream side of the print head in the driving direction of the transport belt.
[0016]
Other features and advantages of the present invention will become apparent from the following description of embodiments using the drawings.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments according to the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram showing an ink jet printer as a first embodiment of a printer according to the present invention.
This ink jet printer has an endless belt-like electrostatic adsorption film 3 (conveying belt) stretched between a total of four pulleys 1a, 1b, 1c, and 1d of the first, second, third, and fourth. And three print heads 4 arranged outside the rotation orbit of the electrostatic adsorption film 3. The fourth pulley 1d is configured to drive the electrostatic attraction film 3 at a constant peripheral speed in the direction of the arrow by being driven to rotate by an electric motor (not shown). The electrostatic adsorption film 3 is made of a ferroelectric flexible material such as PVDF (polyvinylidene fluoride).
[0018]
A corona discharge device 5 is disposed in the vicinity of the first pulley 1a located immediately upstream of the print heads 4Y, 4C, 4M. Further, a counter electrode roller 2 whose peripheral surface is grounded is rotatably disposed at a position facing the first pulley 1a with the electrostatic adsorption film 3 interposed therebetween. The portion of the electrostatic adsorption film 3 that has passed through the first pulley 1 a is charged to a negative polarity by the action of the corona discharge device 5.
The printing paper S is fed to the vicinity of the boundary between the first pulley 1a and the counter electrode roller 2 from a paper feeding system (not shown) arranged on the right hand side of the drawing. The printing paper S approaching the boundary is adsorbed to the electrostatic adsorption film 3 based on the electrostatic induction effect of the electrostatic adsorption film 3 and the counter electrode roller 2 that are strongly charged with negative polarity. The printing paper S adsorbed on the electrostatic adsorption film 3 is conveyed to the position of each print head 4 by the electric motor and the fourth pulley 1d. In this embodiment, the print heads are arranged in the order of the print head 4Y that ejects yellow ink, the print head 4C that ejects cyan ink, and the print head 4M that ejects magenta ink along the paper conveyance surface. Thus, they are arranged in a state of being separated from each other in the transport direction of the printing paper S.
[0019]
A pressure roller 8 (an example of a belt support member) for supporting the electrostatic adsorption film 3 from the lower side at a portion facing each print head 4 is disposed inside the rotation path of the electrostatic adsorption film 3. Yes. The pressure roller 8 includes a roller main body 10 having a peripheral surface made of hard rubber, and a metal shaft member 12 extending further outward from both ends of the roller main body 10. The roller body 10 has a length in the main scanning direction that exceeds at least the width of the printing paper, and has a constant outer diameter over the entire length. The roller body 10 is supported by a pair of support mechanisms 20 and 20 provided at both ends in the main scanning direction so as to be displaceable only in a direction intersecting with the transport surface (herein, a vertical direction).
[0020]
As shown in FIGS. 1 and 2, the support mechanism 20 includes a bearing member 14 formed of a hard insulating material, a locking portion 16 that can lock the bearing member 14, and the bearing member 14 upward. The compression spring 18 is energized. The bearing member 14 includes a rectangular outer portion 14a in front view, and an inner portion 14b that protrudes integrally from the outer portion 14a and has a shorter length in the conveyance direction of the printing paper S than the outer portion 14a. A support hole 14H for supporting the shaft member 12 is formed through the outer portion 14a and the inner portion 14b. As shown in FIG. 3, the locking portion 16 includes a rectangular through-hole formed in the casing of the inkjet printer itself or a metal side plate integrally extending from the casing. The left and right dimensions are set such that the inner portion 14b of the bearing member 14 can be engaged, and the bearing member 14 thus engaged is movable only in the vertical direction. In other words, the left and right dimensions of the locking portion 16 are substantially the same as the left and right outer dimensions of the inner portion 14b so that the bearing member 14 is not displaced in the conveyance direction of the printing paper S. The lower end portion of the compression spring 18 is fixed to the bottom side of the locking portion 16, and functions to urge the bearing member 14 engaged with the locking portion 16 upward.
[0021]
As also shown in FIGS. 1 and 2, a pair of roller members 24, 24 (an example of a spacing member, FIG. 1 and FIG. 2) are viewed from both ends in the main scanning direction of the print head 4 fixed to the main body frame side. In FIG. 2, only the member on the near side is shown) projecting toward the pressure roller 8. The roller members 24 and 24 are supported by a pair of shaft members 22 and 22 fixed near the lower end of the print head 4 so as to be rotatable around an axis extending in parallel with the main scanning direction. The roller member 24 receives the upper end portion of the peripheral surface of the roller body 10 that is biased upward by the compression spring 18. Since the roller member 24 is configured to receive the roller body 10 via the electrostatic adsorption film 3 that is in close contact with the roller body 10, the electrostatic adsorption film 3 is formed on the circumferential surface of the roller member 24. Between the lower end of the roller body 10 and the upper end of the peripheral surface of the roller body 10. The roller member 24 keeps the distance between the pressure roller 8 and the print head 4, more precisely, the distance between the upper end of the peripheral surface of the roller body 10 and the discharge nozzle of the print head 4 by this receiving action. Fulfills the function. As a result, the distance between the portion of the printing paper S that is in close contact with the outer periphery of the electrostatic adsorption film 3 and the print head 4 is 0.5 mm ± 0.2 mm as an example of a distance suitable for the ink flight. Retained.
[0022]
A first contact is provided between the roller main body 10 provided on the print head 4Y and the electrostatic adsorption film 3, and a second contact is provided between the roller main body 10 provided on the print head 4C and the electrostatic adsorption film 3. A third contact is formed between the roller main body 10 provided in the print head 4M and the electrostatic adsorption film 3. The first, second, and third contacts are common tangents on the outer circumferences of the first pulley 1a and the second pulley 1b (that is, there is no roller body 10 and the electrostatic adsorption film 3 is the first and second contacts). When supported by only the third and fourth pulleys 1a, 1b, 1c, and 1d, the transport surface drawn by the electrostatic adsorption film 3 supported between the first pulley 1a and the second pulley 1b) It is slightly displaced toward the outside of the rotation orbit of the electrostatic adsorption film 3. In other words, each pressure roller 8 or roller body 10 has a portion of the electrostatic adsorption film 3 facing each print head 4 and the electrostatic adsorption film 3 installed between the first pulley 1a and the second pulley 1b. It is supported at a position displaced toward the print head 4 from the virtual transport surface to be formed.
[0023]
Here, the details of the ink ejection portions of the print heads 4Y, 4C, and 4M will be described using the most upstream print head 4Y. In addition, about the basic structure of the ink discharge part described here, the same implementation method is applicable also to each of the remaining print heads 4C and 4M.
A cavity capable of holding ink is formed in the print head 4Y. The ink is composed of positively charged yellow pigment particles and a liquid medium containing the pigment particles in a dispersed state. In addition, on the lower surface of the print head 4Y, the ink nozzles communicating with the cavity extend so as to extend in the main scanning direction (parallel to the transport surface and perpendicular to the transport direction of the print paper), and the supplied print paper It is arranged in an open state toward S.
In the discharge nozzle, a large number of operation electrodes are arranged along the main scanning direction (that is, the paper surface penetration direction in FIG. 1). Therefore, positively charged pigment particles contained in the ink are discharged from the ink nozzle by an electric repulsive force acting between a control device (not shown) and a positive pulse voltage applied to the operation electrode. Ink dots are formed on the printing paper S by flying toward the printing paper.
In order to facilitate separation of the printing paper 3 that has completed printing from the electrostatic adsorption film 3, the electrostatic adsorption film 3 is charged between the most downstream print head 4M and the second pulley 1b. A static eliminator 6 for removing static electricity is disposed.
[0024]
[Another embodiment]
<1> The roller member 24 as the spacing member may be configured to directly receive the roller body 10 without using the electrostatic adsorption film 3 that is in close contact with the roller body 10.
[0025]
<2> As in the first embodiment, each pressing roller 8 is installed between the first pulley 1a and the second pulley 1b at a portion of the electrostatic adsorption film 3 that faces the print head 4. In the embodiment in which the electrostatic chucking film 3 is supported at a position displaced toward the print head 4 from the virtual transport surface formed by the electrostatic attracting film 3, the roller member 24, that is, the spacing member is not necessarily required. That is, in this case, even if the interval holding member is omitted, the interval between the print head and the printing paper is kept constant.
[0026]
<3> In the first embodiment described above, each pressing roller 8 is placed between the first pulley 1a and the second pulley 1b on the portion of the electrostatic attracting film 3 facing each print head 4 between the first pulley 1a and the second pulley 1b. Although it supports in the position displaced to the print head 4 side rather than the virtual conveyance surface which the electroadsorption film 3 forms, on the other hand, each press roller 8 has the site | part facing each print head 4 of the electrostatic adsorption film 3. Further, it may be configured to support at a position coinciding with a virtual conveyance surface formed by the electrostatic adsorption film 3 installed between the first pulley 1a and the second pulley 1b.
[0027]
<4> Further, as in the first embodiment, the roller member 24, that is, the interval holding member is provided, and the electrostatic adsorption film 3 is sandwiched between the roller member 24 and the roller body 10. In the case of the configuration, conversely, each pressing roller 8 is electrostatically mounted between the first pulley 1a and the second pulley 1b on the portion of the electrostatic attracting film 3 facing each print head 4. Even in an embodiment in which the suction film 3 is supported at a position slightly displaced to the opposite side of the print head 4 from the virtual transport surface formed by the suction film 3, the distance between the print head and the printing paper is kept constant.
[0028]
<5> In the first embodiment described above, the print head 4 provided with the spacing member is fixed to the main body of the printer, and the roller main body 10 as the belt support member can be displaced in a direction intersecting the conveyance surface. Contrary to this, the roller main body 10 as a belt support member is fixed to the main body of the printer, and the print head 4 on which the interval holding member is fixedly installed is arranged in a direction crossing the conveyance surface. You may provide so that a displacement is possible.
[0029]
<6> Each of the print heads 4 </ b> Y, 4 </ b> Y, 4 </ b> Y as a means for applying a potential having a polarity opposite to the charged polarity of the ink flying from the print head 4 toward the printing paper S to the peripheral surface of the roller body 10 of the pressure roller 8. A new corona discharge device can be provided for every 4C and 4M. This realizes a configuration in which the pressure-bonding roller 8 charged to a polarity opposite to that of the ink actively sucks the ink away from the discharge portion of the print head 4, so that the flying direction of the ink can be controlled more accurately. And a substantial improvement in image resolution can be expected.
[Brief description of the drawings]
FIG. 1 is a side view showing an essential part of an ink jet recording apparatus according to the present invention. FIG. 2 is a partially broken front view showing a belt support member and a spacing member. FIG. 3 is a perspective view showing a belt support member. ]
3 Conveyor belt 4 Print head 5 Charging device 8 Pressure roller (belt support member)
14 Bearing member (belt support member)
18 Compression spring (spring, biasing means)
20 Support mechanism 24 Roller member (interval holding member)
S printing paper

Claims (7)

A print head having a print operation range extending in a main scanning direction; and a conveyance belt that is rotationally driven along a sub-scanning direction that intersects the main scanning direction. The conveyance belt is attracted to a peripheral surface of the conveyance belt. A printer that transports a supported printing paper in the sub-scanning direction within a transport surface spaced from the print head,
A belt support member for supporting a portion of the transport belt facing the print head toward the print head ;
An interval holding member projecting from the print head toward the belt support member in order to keep the interval between the belt support member and the print head constant;
A support mechanism for supporting the belt support member so as to be displaceable in a direction intersecting the transport surface;
And a biasing means for pressing and holding the belt support member toward the interval holding member .   A first pulley that supports the conveyor belt on the upstream side of the print head on a rotational drive track of the conveyor belt, and a second pulley that supports the conveyor belt on the downstream side of the print head; The belt support member is configured so that the portion of the conveyance belt facing the print head is more than the virtual conveyance surface formed by the conveyance belt portion constructed between the first pulley and the second pulley. The printer according to claim 1, wherein the printer is provided to be supported at a position displaced to the side. The belt support member includes a bearing member installed so as to be displaceable in a direction intersecting with the conveying surface, and a pressure roller rotatably supported by the bearing member around an axis extending in parallel with the main scanning direction. the a, the biasing means, a printer according to claim 1 comprising a possible spring pressed toward the bearing member to the spacing members. The spacing member has, on the print head, the printer according to claim 2 or 3 consisting rotatably supported roller member axis around which extends parallel to the main scanning direction. The roller member, the said conveyor belt between the belt support member so as to sandwiched, claim 4 comprising a pair of roller members disposed in the vicinity of both ends of the main scanning direction on the print head Printer. Means are provided for applying to the pressure roller a potential having a polarity opposite to the charging polarity of the ink flying from the print head configured as an electrostatic ink jet print head toward the printing paper. Item 6. The printer according to any one of Items 3 to 5 . A charging device for charging the transport belt with a specific potential polarity is provided on the upstream side of the print head with respect to the driving direction of the transport belt in order to attract the print paper to the transport belt by electrostatic force. The printer according to any one of claims 1 to 6 .

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