JP3610249B2 - Image recording device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image recording apparatus for recording an image by causing a recording agent to fly, and more particularly to a recording medium adsorption mechanism for adsorbing a recording medium during recording.
[0002]
[Prior art]
In general, an ink jet recording apparatus performs recording by ejecting ink from a recording head to a recording medium. The recording head can be easily made compact, can record high-definition images at high speed, and has a running cost. Since it is inexpensive and non-impact, it has advantages such as low noise and easy recording of a color image using multicolor ink. In particular, a full line type apparatus using a line type recording head in which a large number of ejection openings are arranged in the width direction of the recording medium can further increase the recording speed.
[0003]
On the other hand, in a full-line apparatus, the distance from the most upstream recording head to the most downstream recording head is considerably long. For this reason, if the recording medium is lifted in the recording area, the recorded image may be disturbed or cause a jam or the like. Therefore, it is necessary to urge downward so that the recording medium does not float. In particular, when water-based ink is ejected onto plain paper, so-called cockling occurs due to the extension of the paper fibers, and the floating of the recording medium becomes large. Therefore, a sufficient downward bias is required.
[0004]
As a means for energizing the recording medium, for example, in Japanese Patent Application Laid-Open Nos. 07-1333035 and 09-254460, a conductive electrode is provided, and an electrostatic force is generated by applying an electric charge to the electrode to perform recording. A configuration for adsorbing a medium has been proposed. Japanese Patent Application Laid-Open No. 07-053081 proposes a structure in which suction is performed by charging the suction mechanism.
[0005]
[Problems to be solved by the invention]
FIG. 12 shows a case where ink is ejected by combining such a suction mechanism using electrostatic force and a recording head. As shown in the figure, the ink droplets 102 ejected from the recording head 100 are charged by the influence of the electric field between the recording head 100 and the surface of the recording medium P, and the ink droplets 102 ejected from the adjacent nozzles 101 repel each other. . For this reason, there is a problem that the recording quality is lowered without landing at a predetermined landing position. The same phenomenon occurs when the recording agent is powder instead of ink.
[0006]
SUMMARY OF THE INVENTION An object of the present invention is to provide an image recording apparatus that suppresses deterioration in print quality due to electrical repulsion of a recording agent that flies close to an adsorption mechanism using electrostatic force.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, an image recording apparatus according to the present invention includes a recording unit that causes a recording agent to fly to perform recording on a recording medium, and an adsorption force that is disposed facing the recording unit and that adsorbs the recording medium. Generating means, and the attracting force generating means attracts the recording medium by applying positive and negative high voltages with reference to the potential of the recording means.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
An image recording apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing the overall configuration of the image recording apparatus according to the present embodiment, FIG. 2 is an enlarged configuration diagram of a conveyance unit, FIG. 3 is a plan view of a conveyance belt, and FIG. FIG. 5 is a front view showing power feeding to the conveyor belt, FIG. 6 is a diagram explaining the circuit configuration of the attracting force generating means, FIG. 7 is a diagram explaining grounding of the recording means, and FIG. FIG. 9 is a diagram illustrating a conventional circuit configuration for comparison, FIG. 10 is a diagram illustrating the surface potential of a conventional recording medium for comparison, and FIG. 11 is a surface potential. FIG. 6 is a diagram for explaining the relationship between the ink displacement amount and the ink displacement amount.
[0009]
The recording apparatus 1 according to the present embodiment includes an automatic feeding apparatus, and includes a feeding unit 2, a transport unit 3, a recording unit 5, and a discharge unit 4. Hereinafter, each will be described in order with reference to the drawings.
[0010]
(Feeding department)
The feeding unit 2 is configured such that a pressure plate 7 on which a recording medium P that is a recording medium is stacked and a feeding roller 10 that feeds the recording medium P are attached to the base 6. The pressure plate 7 can rotate around a rotation shaft 7 b coupled to the base 6, and is urged to the feeding roller 10 by a pressure plate spring 8. A separation pad 7 a made of a material having a large friction coefficient such as an artificial leather that prevents double feeding of the recording medium P is provided at a portion of the pressure plate 7 that faces the feeding roller 10.
[0011]
Further, the base 6 covers a corner in one direction of the recording medium P, and an illustration for releasing the contact between the separation claw 9 for separating the recording medium P one by one, the pressure plate 7 and the feeding roller 10 is shown. A release cam is not provided.
[0012]
In the above configuration, in the standby state, the release cam pushes down the pressure plate 7 to a predetermined position to release the contact between the pressure plate 7 and the feeding roller 10. When the driving force of the conveying roller 18 is transmitted to the feeding roller 10 and the release cam by a gear or the like, the release cam is separated from the pressure plate 7 and the pressure plate 7 is raised, and the recording medium P contacts the feeding roller 10. . The recording medium P is picked up with the rotation of the feeding roller 10, separated one by one by the separation claw 9, and fed to the transport unit 3. The feeding roller 10 rotates until the recording medium P is fed into the transport unit 3, and again enters a standby state in which the contact between the recording medium P and the feeding roller 10 is released, and the driving force from the transport roller 18 is cut off. .
[0013]
A manual feed tray 11 is provided on the side of the recording apparatus 1. The recording medium P loaded on the manual feed tray 11 is fed by a manual feed roller 12 that rotates according to a recording command signal from a computer or the like, and is guided by a lower guide 13 and an upper guide 14 to be conveyed. 3 is fed.
[0014]
(Transport section)
The conveyance unit 3 includes a conveyance belt 16 that is a belt member that conveys the recording medium P while adsorbing it, and a sheet end sensor (not shown). The conveyor belt 16 is wound around a driving roller 17 that is a downstream conveyor roller, a conveyor roller 18 that is an upstream conveyor roller, and a pressure roller 19. A driving force is transmitted to the driving roller 17 from a driving motor 27 described later, whereby the conveying belt 16 is rotated.
[0015]
The driving roller 17 and the conveying roller 18 are rotatably attached to the platen 20, and the pressure roller 19 is rotatably attached to the other end of an arm 21 that is swingably attached to the platen 20. The arm 21 is pressed by the spring 22 to tension the conveyor belt 16. The platen 20 is positioned below the conveyor belt 16 and has a role of supporting the conveyor belt 16.
[0016]
A pinch roller 23 is provided at a position facing the conveyance roller 18 and is configured to abut against the conveyance belt 16 and follow it. The pinch roller 23 is pressed against the transport belt 16 by a spring (not shown), and sandwiches and transports the recording medium P to the recording unit. Further, the upper guide 14 to which the recording medium P is guided from the feeding unit 2 is provided with a sensor lever 15 that detects the leading end and the trailing end of the recording medium P and transmits it to the sheet end sensor. Seeking the position.
[0017]
Further, a recording head 40 of the recording unit 5 that forms an image based on image information is provided on the downstream side of the conveying roller 18 in the recording sheet conveying direction.
[0018]
(Recording part)
The recording unit 5 according to the present embodiment uses a full-line type ink jet recording head 40 in which a plurality of nozzles are arranged in the entire width in a direction orthogonal to the conveyance direction of the recording medium P. The recording heads 40 are arranged at predetermined intervals in the order of 40K (black), 40C (cyan), 40M (magenta), and 40Y (yellow) from the upstream side in the conveyance direction of the recording medium P, and are attached to the head holder 41. . The recording head 40 has an electric heat energy converter such as a heater, and can apply heat to the ink 52 that is liquid ink. The ink 52 is film-boiled by this heat, and bubbles are generated by the film boiling. The ink 52 is ejected from the nozzles of the recording head 40 by a pressure change caused by the growth or contraction of the recording medium, and an image is formed on the recording medium P.
[0019]
One end of the head holder 41 is rotatably fixed by a shaft 42, and a protrusion 41 a formed at the other end engages with a rail 43, whereby the nozzle surface of each recording head 40, the recording medium P, and the like. Distance (paper spacing) is defined.
[0020]
(Discharge part)
The discharge unit 4 includes a discharge roller 44 and a spur 45, and the recording medium P on which an image is formed by the recording unit is nipped and conveyed by the discharge roller 44 and the spur 45 and is discharged to a discharge tray 46.
[0021]
Next, the configuration and operation for attracting and transporting in the recording unit, and the configuration of the attracting force generating means will be described with reference to FIGS. First, the structure of suction conveyance will be described with reference to FIGS.
[0022]
The conveyance belt 16 is formed of a synthetic resin such as polyethylene or polycarbonate having a thickness of about 0.1 mm to 0.2 mm, and has an endless belt shape. The conveying belt 16 is provided with an attracting force generating means 31 to be described later, and is conveyed in a recording area below the recording head 40 by applying a voltage of about 0.5 KV to 10 KV to a power supply member 34 joined to the conveying belt 16. The belt 16 generates an attracting force.
[0023]
The conveyor belt 16 is supported by an appropriate tension by a driving roller 17, a conveying roller 18 and a pressure roller 19, and the driving roller 17 is connected to a driving motor 27. A sheet pressing member 25 is attached as a pressing means for pressing the recording medium P toward the conveyance belt, and is urged toward the conveyance belt 16 by an urging means (not shown).
[0024]
A pair of cleaning rollers 28 is provided so as to clamp the conveying belt 16. The cleaning roller pair 28 absorbs the ink 52 in order to remove dirt such as ink adhering to the conveying belt 16 and has a small pore diameter (preferably 10 μm to 30 μm) to prevent deterioration in durability. It is formed with. The conveyor belt 16 is cleaned by the cleaning roller pair 28 and then neutralized by a neutralizing brush 29 which is a neutralizing unit.
[0025]
Next, the attractive force generating means 31 will be described with reference to FIGS. As shown in FIG. 3, an attracting force generating means 31 including a pair of electrode plates 32 and 33 made of conductive metal is installed inside the conveyor belt 16. Each of the electrode plates 32 and 33 is configured in an independent comb-teeth shape, and as shown in the figure, facing each other in a direction perpendicular to the transport direction of the transport belt 16, the convex portions enter the respective concave portions. It is installed inside the conveyor belt 16.
[0026]
On both sides of the transport belt 16 in the moving direction, the electrode plates 32 and 33 have power feeding portions (portion exposed portions) 32a and 33a, respectively. These power feeding portions 32a and 33a are provided with a distance longer than the width of the electrode plates 32 and 33, and the power feeding brushes 36 and 37 of the power feeding member 34 are respectively provided with a predetermined pressure as shown in FIG. In contact. A positive voltage of a positive / negative power source 50 that is a high-voltage power source is applied to the power supply brush 36 connected to the power supply unit 32a of the electrode plate 32, and a negative voltage is applied to the power supply brush 37 connected to the power supply unit 33a of the electrode plate 33. Is applied.
[0027]
As shown in FIG. 5, the power supply brushes 36 and 37 of the power supply member 34 are supported by a support member 35, and a cover 38 and a sealing member 39 are provided so as to surround the entire circumference of the support member 35 and the power supply brushes 36 and 37. Being protected. The cover 38 is attached to the platen 20 on the outer side, and a sealing member 39 made of a low-hardness elastomer is provided on the entire inner periphery of the inner side end so as to contact the conveying belt 16 with a predetermined pressure. As described above, the power supply member 34 is configured and installed by the cover 38 and the sealing member 39 so as to have a predetermined space around it and to be isolated from the outside.
[0028]
Further, as shown in FIG. 4, the conveyor belt 16 protects the adsorption force generating means 31 composed of electrode plates 32 and 33 made of conductive metal so as to be sandwiched between the base layer 16a and the surface layer 16b. The base layer 16a and the surface layer 16b are made of a synthetic resin such as polyethylene or polycarbonate.
[0029]
When a voltage is applied to the electrode plates 32 and 33, the surface layer 16b and the recording medium P are polarized as shown in the figure, and the recording medium P is attracted to the attracting force generating means 31 by electrostatic force. That is, in the vicinity of the electrode plate 32 to which a positive voltage is applied, the surface of the surface layer 16b is negatively charged and the surface of the surface layer 16b is positively charged. Similarly, since the surface of the surface layer 16b is negatively charged in the vicinity of the electrode plate 33, an electric field is generated by these potential differences, and the recording medium P can be adsorbed by electrostatic force. At this time, the surface of the recording medium P is also charged according to the polarity of the electrode plates 32 and 33.
[0030]
As shown in FIG. 6, when the recording medium P is attracted to the attracting force generating means 31, the positive / negative power source 50 is grounded to the ground by the ground terminal, +1 kV is supplied to the electrode plate 32 via the power supply brush 36, 1 kV is supplied to the electrode plate 33 via the power supply brush 37.
[0031]
The recording head 40 is grounded by a ground terminal 48. The grounding means in the recording head 40 is shown using FIG. The ink joint portion 47 of the recording head 40 is made of stainless steel, and a ground terminal 48 provided there is grounded to the frame of the recording apparatus 1 main body by an electric wire 51. Since the ink 52 is water-based, the orifice portion 40b is also grounded to 0V. When the base 40 a of the recording head 40 is a metal, the base 40 a can be directly grounded to 0 V, and the orifice portion 40 b can be directly grounded without using the ink 52.
[0032]
The recording medium P is conveyed in the direction of arrow F along with the movement of the conveying means. The actual measured value of the surface potential of the recording medium P at this time is shown in FIG. Since the recording medium P moves in the direction of arrow F in FIG. 6, the surface potential of the recording medium P at a position facing the recording head 40 changes. The highest potential is shown at the middle point X32 of the electrode plate 32, and the value is about 0.3 kV. In addition, the middle point Xc of the electrode interval is substantially 0 kV, and the middle point X33 of the electrode plate 33 is about −0.3 kV. These voltage values vary depending on the size of the adsorption force generating means 31, the thickness, material, and humidity of the base layer 16a and the surface layer 16b.
[0033]
In order to clarify the characteristics of the above configuration, a comparison is made with the state of suction in a conventional image recording apparatus with reference to FIGS. Unlike the present embodiment shown in FIG. 6, in the conventional configuration shown in FIG. 9, 0 kV of the high-voltage power supply 103 is connected to the electrode plate 33, and +2 kV is connected to the electrode plate 32. A potential difference of 2 kV is applied between the electrode plates 32 and 33, and the generated attractive force is the same as that of the present embodiment described with reference to FIG.
[0034]
However, as shown in FIG. 10, at the surface potential of the recording medium P, the maximum potential is 1.3 kV at the midpoint X32 of the electrode plate 32, and is approximately 1 kV at the midpoint Xc between the electrodes. The midpoint X33 was about 0.7 kV. That is, the absolute value of the electric field between the recording head 40 and the surface of the recording medium P is 0.3 kV at the maximum in the present embodiment, but 1.3 kV at the maximum in the conventional example.
[0035]
Here, FIG. 11 shows the deviation amount of the landing position of the ink droplet 49 due to the electric field between the recording head 40 and the surface of the recording medium P. In this figure, the ejection timing is shifted at 600 dpi to avoid ejection from adjacent nozzles, and the deviation amount when ejecting adjacent ink droplets every 3 dots (127 μm intervals) and every 8 dots (340 μm intervals). ) Shows a graph of the deviation amount when discharged.
[0036]
As shown in the figure, for example, when ink is ejected every 3 dots, the maximum potential is 0.3 kV according to the present embodiment, which is about 4 μm, whereas the conventional example has the maximum potential. Is 1.3 kV, so that the deviation is about 40 μm. Further, it can be seen that even when ink is ejected every 8 dots, the deviation is about 1 μm according to the present invention, whereas the deviation is about 10 μm in the comparative example.
[0037]
As described above, according to the present invention, it is possible to greatly suppress the deviation amount of the landing positions of ink droplets while maintaining the same suction force, and to improve the recording quality. Further, since the effect becomes more remarkable as the interval between the ink droplets 49 is smaller, a higher effect can be obtained in a high-resolution image recording apparatus such as 1200 dpi, 2400 dpi.
[0038]
In the present embodiment, it has been described that ± 1 kV is applied by the positive / negative power source 50. However, in order to suppress the landing position deviation, a lower value, for example, about ± 0.5 kV is desirable. If the voltage is lower than this, the attracting force becomes weak, and problems such as floating of the recording medium P occur. Further, in order to increase the attractive force, a voltage of about ± 3 kV may be applied. However, as the voltage increases, the landing position deviation increases. However, even in this case, it is understood that the amount of deviation of the landing position is smaller than in the conventional example.
[0039]
[Other Embodiments]
In the above embodiment, the suction force generating means 31 is integrally formed inside the conveyor belt 16, but the present invention is not limited to this, and an electrode is provided on the surface below a normal belt member. Alternatively, a fixed electrode plate may be provided. In this case, only the belt member can be driven to rotate and the recording medium can be conveyed along with it. At this time, friction between the belt member and the suction means becomes a problem, but the structure of the belt member can be simplified.
[0040]
Further, instead of the belt member, a comb-like electrode may be provided on the surface of the drum member, and the recording medium may be adsorbed on the surface and conveyed. In this case, it is difficult to reduce the size of the entire apparatus, but stability in the conveyance speed and the conveyance direction can be easily obtained.
[0041]
In the present embodiment, the water-based ink is used as the liquid ink. However, this embodiment is also effective in preventing deterioration of landing accuracy due to polarization of the oil-based ink. Even when recording is performed by flying powder or the like instead of liquid ink, any recording agent that is polarized by an electric field can be applied. The recording agent may be a colored member or may be colored by some means. For example, a coloring material is applied onto a recording medium, and a liquid ink having a colorless developer is caused to fly to develop a predetermined portion, or a colorless adhesive ink is caused to fly onto a recording medium and a powder toner is adhered. The present invention can also be applied to the case of using what performs recording.
[0042]
【The invention's effect】
As described above, in the image recording apparatus according to the present invention, even when a high voltage is applied to the suction force generating means in order to generate a sufficient suction force, the landing position of the landing position is not disturbed even when a high voltage is applied to the suction force generation means. The amount of deviation can be made extremely small. In particular, even in the case of a full-line type ink jet recording head in which a plurality of recording elements are arranged over the entire width of the recording medium and the density is 600 dpi or higher, the deviation of the landing position can be suppressed. Further, the higher the density is 1200 dpi and 2400 dpi, the greater the effect of the present invention.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an overall configuration of an image recording apparatus according to an embodiment.
FIG. 2 is an enlarged configuration diagram of a transport unit.
FIG. 3 is a plan view of a conveyor belt.
4 is a cross-sectional view taken along the line aa of FIG. 3 for explaining the attractive force generating means. FIG.
FIG. 5 is a front view showing power feeding to a conveyor belt.
FIG. 6 is a diagram illustrating a circuit configuration of an attractive force generation unit.
FIG. 7 is a diagram illustrating grounding of a recording unit.
FIG. 8 is a diagram illustrating a surface potential of a recording medium.
FIG. 9 is a diagram illustrating a conventional circuit configuration.
FIG. 10 is a diagram for explaining a surface potential of a conventional recording medium.
FIG. 11 is a diagram illustrating a relationship between a surface potential and an ink shift amount.
FIG. 12 is a diagram for explaining an image recording apparatus having a conventional suction mechanism using electrostatic force and a recording head.
[Explanation of symbols]
P ... Recording medium 1 ... Recording device 2 ... Feeding unit 3 ... Conveying unit 4 ... Discharging unit 5 ... Recording unit 6 ... Base 7 ... Pressure plate 7a ... Separation pad 7b ... Rotating shaft 8 ... Pressure plate spring 9 ... Separation claw 10 ... Feeding Feed roller 11 ... Manual feed tray 12 ... Feed roller 13 ... Lower guide 14 ... Guide 15 ... Sensor lever 16 ... Conveying belt 16a ... Base layer 16b ... Surface layer 17 ... Driving roller 18 ... Conveying roller 19 ... Pressure roller 20 ... Platen 21 ... arm 22 ... spring 23 ... pinch roller 25 ... sheet pressing member 27 ... drive motor 28 ... cleaning roller pair 29 ... static elimination brush 31 ... adsorption force generating means 32 ... electrode plate 32a ... power feeding part 33 ... electrode plate 33a ... power feeding part 34 ... Power supply member 35 ... Support member 36 ... Power supply brush 37 ... Power supply brush 38 ... Cover 39 ... Sealing member 40 ... Recording head 40a ... 40b ... Orifice part 41 ... Head holder 41a ... Projection part 42 ... Shaft 43 ... Rail 44 ... Discharge roller 45 ... Spur 46 ... Discharge tray 47 ... Ink joint part 48 ... Ground terminal 49 ... Ink droplet 50 ... Positive / negative power source 51 ... Electric wire 52 ... Ink 100 ... Recording head 101 ... Nozzle 102 ... Ink droplet 103 ... High voltage power supply

Claims (11)

A recording means for recording on a recording medium by flying a recording agent;
An adsorbing force generating means arranged to face the recording means and adsorbing the recording medium;
The image recording apparatus according to claim 1, wherein the attracting force generating means attracts the recording medium by applying positive and negative high voltages with reference to the potential of the recording means. The image recording apparatus according to claim 1, wherein the recording agent is liquid ink. The image recording apparatus according to claim 1, wherein the attraction force generating unit includes a first electrode and a second electrode arranged to face the first electrode. The attraction force generating means has a high voltage power source grounded to the same potential as the recording means, the high voltage power source applies a positive or negative output voltage with respect to the ground to the first electrode, 4. The image recording apparatus according to claim 3, wherein an output voltage having a polarity opposite to that of the output voltage to the first electrode is applied to the second electrode. 5. The image recording apparatus according to claim 1, wherein the image recording apparatus includes a conveying unit that moves the adsorbed recording medium with respect to the recording unit. 6. 6. The image recording apparatus according to claim 5, wherein the conveying means is a belt member. 6. The image recording apparatus according to claim 5, wherein the conveying means is a drum member. The image recording apparatus according to claim 5, wherein the attraction force generation unit is provided integrally with the transport unit. 9. The image recording apparatus according to claim 8, wherein the attraction force generating means is disposed close to the lower part of the conveying means. The recording unit includes a full-line type recording head in which a plurality of recording elements are arranged at a predetermined angle or perpendicular to the moving direction of the transport unit over the entire width of the recording area of the recording medium. The image recording apparatus according to any one of 1 to 8. The recording head performs recording by discharging liquid ink using thermal energy, and the image recording apparatus includes an electrothermal transducer for generating thermal energy to be applied to the liquid ink. The image recording apparatus according to claim 1, wherein:

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