JP2004175490A - Image recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem on the paper jamming caused by winding up of the paper on a conveying belt in a state of being attracted, when the paper is conveyed by electrostatically attracting the conveying belt. <P>SOLUTION: The conveying belt 21 for conveying the paper 12 is hung over between a conveying roller 27 and a tension roller 28, and a separation claw 41 kept into contact with a conveying belt 21 surface for separating the paper 12 from the conveying belt 21 is mounted at a paper discharge part side of the conveying belt 21 in a state of being energized to a conveying belt 21 side. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
[Industrial applications]
The present invention relates to an image recording apparatus, and more particularly to an image recording apparatus that conveys a sheet using a conveyance belt.
[0002]
[Patent Document 1] Japanese Patent Application Laid-Open No. 7-53082
[Prior art]
2. Description of the Related Art For example, an ink jet recording apparatus is known as an image recording apparatus (or image recording apparatus) such as a printer, a facsimile, and a copying apparatus. The ink jet recording apparatus is a sheet to which ink droplets including OHP and the like can be attached from an ink recording head to a sheet (also referred to as a recording medium, a recording medium, a recording sheet, or the like). It prints high-definition images at high speed with low running cost, low noise, and prints color images using multi-color inks. It has advantages such as easy operation.
[0004]
As the ink jet head, a piezoelectric actuator such as a piezoelectric element, a thermal actuator utilizing a phase change due to film boiling of a liquid using an electrothermal transducer such as a heating resistor, a shape memory alloy actuator using a metal phase change due to a temperature change, 2. Description of the Related Art There is known an electrostatic actuator using an electrostatic force or the like as an energy generating unit for discharging ink.
[0005]
By the way, in the ink jet recording method, since an ink is attached to paper, when an image is formed, there is a phenomenon that the paper is stretched by moisture contained in the ink. This phenomenon is called cockling. This cockling causes the paper to undulate, and the positions of the nozzles of the head and the surface of the paper change from place to place. If the degree of cockling becomes worse, in the worst case, the paper may come into contact with the nozzle surface of the head and stain the nozzle surface of the head, or the paper itself may become dirty, deteriorating the image quality. The impact position of the ink droplet may be shifted due to the influence.
[0006]
Further, in the conventional ink jet recording apparatus, paper is fed by rollers, and two sets of rollers (one is a combination of a spur and a roller as described above) are arranged with a printing area interposed therebetween. However, in this configuration, the paper feeding accuracy can be guaranteed only when the paper is engaged with the two sets of rollers.
[0007]
However, in recent years, since an increase in the image printing area is desired, a state in which the paper feeding accuracy cannot be assured in order to secure the printing area, that is, one of the two roller pairs is used. There is also an ink jet recording apparatus in which printing is performed in a state where only the sheet is bitten. However, in the state where the sheet is bitten by only one roller pair, if the sheet floats, it cannot be dealt with, or the feeding accuracy cannot be guaranteed because the sheet conveyance force cannot be secured, so the image quality also deteriorates. Problem arises.
[0008]
Therefore,
As described in Patent Document 1, in order to maintain the flatness of the paper, an endless charging belt is provided, and the surface of the charging belt is charged to electrostatically attract the paper. An ink jet recording apparatus has been proposed in which a sheet is conveyed by rotating the sheet to prevent the sheet from floating from a charging belt, thereby maintaining high flatness.
[0009]
[Problems to be solved by the invention]
However, when the paper is transported in a state in which the paper is electrostatically attracted using a transport belt as in the above-described conventional inkjet recording apparatus, in order to stack the paper on the paper discharge unit, the paper is separated from the transport belt by curvature separation. Although separated, the paper with a weak stiffness or a paper with a weak stiffness due to a solid image or the like does not undergo curvature separation, remains adsorbed on the transport belt, and has a problem that a jam occurs.
[0010]
The present invention has been made in view of the above problems, and has as its object to provide an image recording apparatus capable of reliably separating paper from a transport belt.
[0011]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the image recording apparatus according to the present invention is provided with a separation mechanism that supports the transport belt by bridging between at least two rollers, and separates the paper from the transport belt on the discharge side of the transport belt. It is a thing.
[0012]
Here, the separation mechanism preferably has a separation claw, and the separation claw is preferably disposed so as to be able to approach and separate from the surface of the conveyor belt.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a configuration diagram illustrating the overall configuration of an ink jet recording apparatus as an image recording apparatus according to the present invention, FIG. 2 is a plan view illustrating main parts of the recording apparatus, and FIG. 3 is an enlarged explanatory view illustrating main parts of the recording apparatus. is there.
[0014]
In the ink jet recording apparatus, a carriage 3 is slidably held in a main scanning direction by a guide rod 1 and a stay 2 which are guide members which are laterally mounted on left and right side plates (not shown). The moving scan is performed in the direction indicated by the arrow.
[0015]
The carriage 3 is provided with a plurality of ink ejection orifices through a recording head 4 composed of four inkjet heads for ejecting ink droplets of yellow (Y), cyan (C), magenta (M), and black (Bk). They are arranged in a direction crossing the main scanning direction, and are mounted with the ink droplet ejection direction facing downward.
[0016]
The ink jet head constituting the recording head 4 includes a piezoelectric actuator such as a piezoelectric element, a thermal actuator using an electrothermal conversion element such as a heating resistor to utilize a phase change due to film boiling of a liquid, and a metal phase change due to a temperature change. An actuator having a shape memory alloy actuator to be used, an electrostatic actuator using electrostatic force, or the like as an energy generating means for discharging ink can be used.
[0017]
Further, the carriage 3 is mounted with sub-tanks 5 of each color for supplying inks of each color to the recording head 4. The sub-tank 5 is supplied with ink from a main tank (ink cartridge) via an ink supply tube (not shown).
[0018]
On the other hand, as a paper feed unit for feeding paper 12 loaded on a paper loading unit (pressure plate) 11 such as a paper feed cassette 10, a half-moon roller that separates and feeds the papers 12 one by one from the paper loading unit 11 ( A sheet feed roller 13 and a separation pad 14 made of a material having a large friction coefficient are provided facing the sheet feed roller 13. The separation pad 14 is urged toward the sheet feed roller 13.
[0019]
As a transport unit for transporting the paper 12 fed from the paper feed unit below the recording head 4, a transport belt 21 for electrostatically attracting and transporting the paper 12 and a feed belt 21 A counter roller 22 for transporting the paper 12 sent through the guide 15 between the transport belt 21 and the paper 12 transported substantially vertically upward is turned by approximately 90 ° to copy the paper 12 onto the transport belt 21. A transport guide 23 for adjusting the pressure and a pressing roller 25 urged toward the transport belt 21 by a pressing member 24 are provided. Further, a charging roller 26 serving as a charging unit for charging the surface of the transport belt 21 is provided. Note that a holding roller 30 is provided at the tip of the holding member 24.
[0020]
Here, the transport belt 21 is an endless belt, is stretched between the transport roller 27 and the tension roller 28, and is configured to orbit in the arrow A direction (belt transport direction). The transport belt 21 has a surface layer serving as a paper adsorption surface formed of a pure resin material having a thickness of about 40 μm, for example, of which resistance is not controlled, for example, an ETFE pure material, and resistance control is performed with carbon using the same material as the surface layer. And a back layer (medium resistance layer, earth layer).
[0021]
The thickness of the insulating layer (surface layer) of the transport belt 21 affects the dielectric constant. As the thickness increases, the dielectric constant decreases, and the amount of electric charge placed on the belt when charged becomes smaller. Therefore, the electrostatic attraction force can be improved by taking into account the range of the film thickness that varies in manufacturing, and by making the layer thickness as thin as possible within the range where the layer thickness does not become 0 even when the belt is scratched in an actual machine. .
[0022]
Further, the thickness of the back layer (medium resistance layer, earth layer) of the transport belt 21 does not directly affect the electrostatic action, but when the total thickness of the belt increases, the rigidity increases and the belt is stretched on an actual machine. In addition, it is difficult to secure the flatness of the belt, while it is not possible to make the belt too thin to secure the required strength.
[0023]
By providing a layer with resistance control on the entire back side of the conveyor belt 21 as a two-layer configuration, charges are previously formed on the surface layer, which is an insulating layer, and then, when the paper to be adsorbed on the belt comes into contact, the charges are further supplied. In addition, the electrostatic attraction force between the sheet and the transport belt 21 can be increased. In the case of a single insulating layer, the suction force is reduced by half compared to the case of two layers, and in the case of a single layer, the position at which the paper starts to contact the belt faces the ground roller located inside the belt. However, such a restriction is eliminated by providing two layers.
[0024]
The charging roller 26 is arranged so as to be in contact with the surface layer of the transport belt 21 and rotate following the rotation of the transport belt 21, and apply 2.5 N to both ends of the shaft as a pressing force. The transport roller 27 also serves as the above-described ground roller, and is arranged in contact with the middle resistance layer (back layer) of the transport belt 21 and is grounded.
[0025]
A guide member 31 is arranged on the back side of the transport belt 21 so as to correspond to the printing area of the recording head 4. Both ends of the guide member 31 in the main scanning direction are held between frame members 35 that hold the transport roller 22 and the tension roller 28 and the like.
[0026]
The guide member 31 has an upper surface protruding from the tangent line of the two rollers (the transport roller 27 and the tension roller 28) supporting the transport belt 21 to the recording head 4 side. As a result, the transport belt 21 is pushed up and guided by the upper surface of the guide member 31 in the printing area.
[0027]
As described above, the guide member 31 disposed on the back side of the transport belt 21 causes the belt chord portion corresponding to the printing area to be pushed up to the recording head 4 side and to move along the guide member 31. No wrinkles or dances occur at the string portion of the belt, high flatness can be maintained, and recording can be performed with high image quality.
[0028]
Furthermore, a plurality of grooves are formed in the main scanning direction, that is, in a direction orthogonal to the conveying direction, on the surface of the guide member 31 that comes into contact with the back surface of the conveying belt 21 to reduce the contact area with the conveying belt 21. Thus, the transport belt 21 can be smoothly moved along the surface of the guide member 31.
[0029]
Furthermore, guide rollers 33 and 34 that abut on the back surface side of the transport belt 21 are rotatably disposed on the upstream side and the downstream side in the transport direction of the guide member 31, respectively. It is preferable that the guide rollers 33 and 34 are arranged near both ends of the guide member 31 in the transport direction.
[0030]
As described above, since the guide rollers 33 and 34 that come into contact with the back surface of the transport belt 21 are rotatably disposed on the upstream side and the downstream side of the guide member 31 in the transport direction, respectively, the transport belt 21 and the ends of the guide member 31 The friction generated between the belt and the belt can be reduced, the driving load due to the conveyor belt 21 can be reduced, and the conveyor belt 21 can be prevented from being fluctuated by rubbing against the end of the guide member 31. It is possible to prevent wrinkles, dances, and the like from occurring in the portion, and record with high image quality while maintaining high flatness.
[0031]
Further, as shown in FIG. 3, a separation claw 41 serving as a separation mechanism for separating the paper 12 from the transport belt 21 is transported as a paper discharge unit for discharging the paper 12 recorded by the recording head 4. A paper discharge roller 42 and a paper discharge roller 43 are disposed downstream of the separation claw 41, and a paper discharge tray 44 for storing the paper 12 discharged further downstream of the separation claw 41. It has. Here, the separation claw 41 is swingably supported by a support shaft 41a, and is brought into contact with the surface of the transport belt 21 by applying tension to the transport belt 21 side by an elastic body 45 such as a spring.
[0032]
Further, a duplex paper supply unit 51 is detachably mounted on the apparatus main body. The double-sided paper feeding unit 51 takes in the paper 12 returned by the rotation of the transport belt 21 in the reverse direction, reverses the paper 12, and feeds the paper 12 again between the counter roller 22 and the transport belt 21.
[0033]
In the ink jet recording apparatus configured as described above, the paper 12 is separated and fed one by one from the paper feeding unit, and the paper 12 fed substantially vertically upward is guided by the guide 15, and the transport belt 21 and the counter roller 22 And the leading end thereof is guided by a carrying guide 23 and pressed against the carrying belt 21 by a leading end pressing roller 25 to change the carrying direction by approximately 90 °.
[0034]
At this time, a positive output and a negative output are alternately repeated from the high voltage power supply to the charging roller 26 by a control circuit (not shown), that is, an alternating voltage is applied, and a charging voltage pattern in which the transport belt 21 alternates, that is, In the sub-scanning direction, which is the circling direction, plus and minus are alternately charged in a belt shape with a predetermined width. When the paper 12 is fed onto the positively and negatively charged conveyor belt 21, the paper 12 is polarized in the paper 12 to a charge opposite to the charged pattern, so that a capacitor connected in parallel is formed. The paper 12 is attracted to the transport belt 21, and the paper 12 is transported in the sub-scanning direction by the orbital movement of the transport belt 21.
[0035]
Therefore, by driving the recording head 4 in accordance with the image signal while moving the carriage 3, ink droplets are ejected onto the stopped paper 12 to record one line, and after the paper 12 is conveyed by a predetermined amount, Record the next line. Upon receiving a recording end signal or a signal indicating that the rear end of the sheet 12 has reached the recording area, the recording operation is terminated, and the sheet 12 is discharged to the discharge tray 44.
[0036]
At this time, since the separation claw 41 faces the paper discharge unit side of the transport belt 21, the paper 12 is reliably separated from the transport belt 21 and discharged, and is caught and jammed while being attracted to the transport belt 21. Is prevented.
[0037]
Next, another embodiment of the present invention will be described with reference to FIG.
In this embodiment, the separation claw 41 is swingably supported by the support shaft 41a, and is disposed so as to be capable of coming and going with respect to the surface of the conveyor belt 21. The separation claw 41 is brought into contact with and separated from the surface of the conveyor belt 21. Plunger 61 is provided. The main controller 63 controls the driving of the plunger 61 via the driver 64 based on the detection signal of the leading edge detection sensor 62 that detects the leading edge of the sheet 12 provided on the carriage 3.
[0038]
With this configuration, the plunger 61 is driven only for the timing of recording on the paper 12 and discharging the paper (the required period for the leading edge of the paper 12 to reach the paper discharge unit), and the separation claw 41 is moved to the surface of the transport belt 21. The sheet 12 is separated from the surface of the conveyor belt 21 by contact, and after separation, the plunger 61 is not driven to separate the separation claw 41 from the surface of the conveyor belt 21.
[0039]
Thereby, the separation claw 41 can be brought into contact with the surface of the conveyor belt 21 only when necessary, and the durability of the conveyor belt 41 is improved.
[0040]
In the above embodiment, the separation claw is used as the separation mechanism. However, for example, an air separation mechanism by blowing air may be used. Also, the present invention has been described with an example in which the present invention is applied to a serial type (shuttle type) ink jet recording apparatus in which a carriage scans, but the present invention can be similarly applied to a line type ink jet recording apparatus having a line type head.
[0041]
Further, the image recording apparatus according to the present invention can be applied to a facsimile apparatus, a copying apparatus, a printer / fax / copier multifunction peripheral, etc. in addition to the ink jet printer. Furthermore, the present invention can be applied to an image recording apparatus that ejects a liquid other than ink, for example, a resist or a DNA sample in the medical field.
[0042]
【The invention's effect】
As described above, according to the image recording apparatus of the present invention, since the separation mechanism that separates the paper from the transport belt is provided on the discharge unit side of the transport belt that transports the paper, the paper is reliably separated. Paper can be discharged, and occurrence of jam can be prevented.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an image recording apparatus according to an embodiment of the present invention. FIG. 2 is a plan view of main parts of the recording apparatus. FIG. 3 is a main part explanatory view of the recording apparatus. Description of the main parts of another embodiment of the present invention
3 carriage, 4 recording head, 12 paper, 21 conveyance belt, 26 charging roller, 27 conveyance roller, 28 tension roller, 31 guide member, 33, 34 guide roller, 41 separation claw, 44 ... paper ejection tray.

Claims (3)

In an image recording apparatus that charges the surface of an endless conveyance belt to attract and convey a sheet, discharges droplets from a recording head, records an image on the sheet, and discharges the sheet, the conveyance belt has at least two An image recording apparatus, comprising: a separation mechanism that is supported between rollers and supported by a roller, and that separates the sheet from the transport belt on the discharge side of the transport belt. 2. The image recording apparatus according to claim 1, wherein said separation mechanism has a separation claw. The image recording apparatus according to claim 2, wherein the separation claw is disposed so as to be able to approach and separate from the surface of the transport belt.

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