JP2000143025A - Image recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a lowering of printing quality caused by the electrical repulsion of a recording agent flying in proximity by applying positive and negative high voltage to an attracting force generating means on the basis of the potential of a recording means to attract a recording medium. SOLUTION: A conveyor belt 16 is provided with an attracting force generating means 31 composed of electrode plates 32, 33 formed of conductive metal. When voltage is applied to the electrode plates 32, 33, polarization is generated to a surface layer 16b and a recording medium P, and the electrode plate 32 side of the surface layer 16b is charged negative near the electrode plate 32 to which positive voltage is applied, while the surface of the surface layer 16b is charged positive. In the same way, the surface of the surface layer 16b is charged negative near the electrode plate 33, so that the electric field is generated by the potential difference to attract the recording medium P by electrostatic power. At this time, the surface of the recording medium P is also charged according to the polarity of the electrode plates 32, 33. With this constitution, even if high voltage is applied to the attracting force generating means to generate sufficient attracting force, flying of a recording agent in proximity is not disordered, and the discrepancy of an impact position can be made extremely small.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording apparatus for recording an image by flying a recording agent, and more particularly to a recording medium adsorbing mechanism for adsorbing a recording medium during recording.

[0002]

2. Description of the Related Art In general, an ink jet recording apparatus performs recording by ejecting ink from a recording head to a recording medium, so that the recording head can be easily made compact and high-definition images can be recorded at high speed. It has advantages such as low running cost, low noise due to the non-impact method, and easy recording of a color image using multicolor inks. Above all, a full-line type apparatus using a line type recording head in which a large number of ejection ports are arranged in the width direction of the recording medium can further increase the recording speed.

On the other hand, in a full-line type apparatus, the distance from the recording head at the most upstream position to the recording head at the most downstream position becomes considerably long. Therefore, if the recording medium rises in the recording area, the recorded image may be disturbed or cause a jam or the like. Therefore, it is necessary to urge the recording medium downward so as not to rise. In particular, when the water-based ink is ejected onto plain paper, the so-called cockling due to the extension of the paper fibers occurs and the floating of the recording medium becomes large, so that a sufficient downward urging is required.

As means for urging the recording medium, for example, JP-A-07-133,035 and JP-A-09-254 are known.
Japanese Patent Application Publication No. 460/460 and the like have proposed a configuration in which a conductive electrode is provided, a charge is applied to the electrode to generate an electrostatic force, and the recording medium is adsorbed. Japanese Patent Application Laid-Open No. 07-053081 proposes a configuration in which a suction mechanism is charged to perform suction.

[0005]

FIG. 12 shows a case in which ink is ejected by combining such a suction mechanism utilizing electrostatic force and a recording head. As shown in the figure, the ink droplets 102 ejected from the print head 100
The ink droplets 102 ejected from the nozzles 101 adjacent to each other are charged by the influence of the electric field between 0 and the surface of the recording medium P, and repel each other. For this reason, there is a problem that the recording quality is deteriorated because the ink does not land at a predetermined landing position. A similar phenomenon occurs when the recording agent is not ink but powder.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image recording apparatus which suppresses a decrease in print quality due to an electric repulsion of a recording material flying close in an adsorption mechanism using electrostatic force.

[0007]

In order to solve the above-mentioned problems, an image recording apparatus according to the present invention comprises a recording unit for flying a recording agent to perform recording on a recording medium, and a recording unit facing the recording unit. And a suction force generating means for sucking the recording medium, wherein the suction force generating means suctions the recording medium by applying a positive and a negative high voltage with reference to the potential of the recording means. Features.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of an image recording apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view illustrating the overall configuration of an image recording apparatus according to the present embodiment, FIG. 2 is an enlarged configuration diagram of a transport unit, FIG. 3 is a plan view of a transport belt,
FIG. 4 is a sectional view taken along line aa of FIG.
FIG. 5 is a front view showing power supply to the conveyor belt, FIG. 6 is a diagram illustrating a circuit configuration of the suction force generating unit, FIG. 7 is a diagram illustrating grounding of the recording unit, and FIG. 8 is a diagram illustrating a surface potential of the recording medium. FIG. 9 is a diagram for explaining 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 diagram illustrating the relationship between the surface potential and the amount of ink displacement.

The recording apparatus 1 according to the present embodiment has an automatic feeding apparatus, and includes a feeding section 2, a transport section 3, a recording section 5, and a discharge section 4. Each of them will be described below in order with reference to the drawings.

(Feeding Unit) The feeding unit 2 is configured such that a pressure plate 7 for loading a recording medium P, which is a recording medium, and a feeding roller 10 for feeding the recording medium P are attached to a base 6. The pressure plate 7 is rotatable about a rotation shaft 7 b connected to the base 6, and is urged by a pressure plate spring 8 to the feed roller 10. A separation pad 7a made of a material having a large coefficient of friction, such as artificial skin, for preventing double feeding of the recording medium P is provided at a portion of the pressure plate 7 facing the feeding roller 10.

Further, the base 6 covers a corner in one direction of the recording medium P, and releases 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. Release cam (not shown) is provided.

In the above configuration, in the standby state, the release cam pushes down the pressure plate 7 to a predetermined position, thereby releasing the contact between the pressure plate 7 and the feed roller 10. When the driving force of the transport roller 18 is transmitted to the feed roller 10 and the release cam by a gear or the like, the release cam separates from the pressure plate 7 and the pressure plate 7 rises, so that the recording medium P comes into contact with the feed roller 10. . The recording medium P is picked up by the rotation of the feed roller 10, separated by the separation claw 9 one by one, and fed to the transport unit 3. The feed roller 10 transports the recording medium P to the transport unit 3.
Until the recording medium P and the feed roller 10
In this state, the driving force from the transport roller 18 is cut off.

A manual feed tray 11 is provided on the side of the recording apparatus 1. The recording medium P stacked on the manual feed tray 11 is fed by a feed roller 12 for manual feed that rotates according to a recording command signal from a computer or the like.
It is guided by the lower guide 13 and the upper guide 14 and fed to the transport unit 3.

(Conveying Section) The conveying section 3 has a conveying belt 16 which is a belt member for conveying the recording medium P while adsorbing the recording medium P, and a sheet end sensor (not shown). The transport belt 16 is wound around a drive roller 17 as a downstream transport roller, a transport roller 18 as an upstream transport roller, and a pressure roller 19. Driving force is transmitted to the driving roller 17 from a driving motor 27 to be described later, whereby the transport belt 16 is rotated.

The drive roller 17 and the transport roller 18 are rotatably mounted on the platen 20, and the pressure roller 19 is rotatably mounted on the other end of an arm 21 whose one end is swingably mounted on the platen 20. Arm 21 is spring 22
The tension is applied to the transport belt 16 by being pressed. The platen 20 is located below the transport belt 16 and has a role of supporting the transport belt 16.

A pinch roller 23 is provided at a position facing the transport roller 18, and is configured to abut on and follow the transport belt 16. The pinch roller 23 is pressed against the transport belt 16 by a spring (not shown),
The recording medium P is nipped and conveyed to the recording unit. The upper guide 14 on which the recording medium P is guided from the feeding unit 2 has a recording medium P
A sensor lever 15 for detecting the leading end and the trailing end of the recording medium P and transmitting it to the sheet end sensor is provided, and the recording position of the recording medium P is obtained.

Further, a recording head 40 of the recording section 5 for forming an image based on image information is provided downstream of the transport roller 18 in the recording sheet transport direction.

(Recording Unit) The recording unit 5 according to the present embodiment employs a full-line type ink jet recording head 40 in which a plurality of nozzles are arranged in a full width in a direction perpendicular to the conveying direction of the recording medium P. The recording head 40 includes 40K (black), 40C (cyan),
40M (magenta) and 40Y (yellow) are arranged at predetermined intervals in this order and attached to the head holder 41. The recording head 40 has an electrothermal energy converter such as a heater, and is capable of applying heat to the ink 52, which is a liquid ink. The pressure change caused by the growth or contraction of
52 is ejected to form an image on the recording medium P.

One end of the head holder 41 is rotatably fixed by a shaft 42. A protruding portion 41a formed on the other end is engaged with a rail 43, whereby the nozzle surface of each recording head 40 and the recording surface are connected. The distance (paper interval) from the medium P is defined.

(Ejection Unit) The ejection unit 4 is spurs with the ejection roller 44
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 discharged to the discharge tray 46.

Next, the structure, operation, and structure of the suction force generating means for sucking and conveying in the recording section will be described with reference to FIGS. First, the configuration of the suction conveyance will be described with reference to FIGS.

The transport belt 16 is made 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 conveyor belt 16 is provided with a suction force generating means 31 described later,
By applying a voltage of about 0.5 KV to 10 KV to the power supply member 34 joined to the transport belt 16, an attractive force is generated on the transport belt 16 in the recording area below the recording head 40.

The transport belt 16 includes a driving roller 17 and a transport roller.
The driving roller 17 is connected to a driving motor 27 while being given a suitable tension by a pressure roller 19.
As a pressing means for pressing the recording medium P against the conveying belt, a sheet pressing member 25 is mounted around the rotation axis of the pinch roller 23 as a rotation center, and is urged toward the conveying belt 16 by urging means (not shown).

A pair of cleaning rollers 28 is provided so as to sandwich the transport belt 16. The cleaning roller pair 28 absorbs the ink 52 to remove dirt such as ink adhered to the conveyor belt 16 and has a small cell diameter (preferably 10 μm to 30 μm) sponge for preventing deterioration in durability. It is formed with. After the transport belt 16 is cleaned by the cleaning roller pair 28, the charge is removed by a charge removing brush 29 that is a charge removing unit.

Next, the suction force generating means 31 will be described with reference to FIGS. As shown in FIG. 3, the conveyor belt
A set of electrode plates made of conductive metal inside 16
Attraction force generating means 31 composed of 32 and 33 is provided. Each of the electrode plates 32 and 33 has an independent comb tooth shape, and each of the electrode plates 32 and 33 faces each other in a direction orthogonal to the transport direction of the transport belt 16 so that each convex portion enters each concave portion as shown in the figure. It is installed inside the conveyor belt 16.

On both sides in the moving direction of the transport belt 16, the electrode plates 32 and 33 have power supply portions (portions where the pattern is exposed) 32a and 33a, respectively. These power supply units 32a, 33
“a” is provided with a distance longer than the width of the electrode plates 32 and 33, and the power supply brushes 36 and 37 of the power supply member 34 are in contact with each other at a predetermined pressure as shown in FIG. A positive voltage of a positive / negative power supply 50, which is a high-voltage power supply, is applied to a power supply brush 36 connected to a power supply portion 32a of the electrode plate 32.
A negative voltage is applied to the power supply brush 37 connected to 33a.

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 is provided so as to surround the entire circumference of the support member 35 and the power supply brushes 36 and 37.
38 and a sealing member 39 are provided and protected. cover
Numeral 38 is attached to the platen 20 on the outside, and a sealing member 39 made of a low-hardness elastomer is provided around the entire inner side end to make contact with the conveyor belt 16 at a predetermined pressure. As described above, the power supply member 34 is configured and installed so as to have a predetermined space around and be isolated from the outside by the cover 38 and the sealing member 39.

As shown in FIG. 4, the conveyor belt 16 protects the attraction force generating means 31 composed of electrode plates 32 and 33 made of conductive metal by sandwiching it between the base layer 16a and the surface layer 16b. I have. The base layer 16a and the surface layer 16b are made of a synthetic resin such as polyethylene and polycarbonate.

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 the positive voltage is applied, the surface layer 16b side of the electrode plate 32 is negatively charged, and 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 attracted by electrostatic force. At this time, the surface of the recording medium P is also charged according to the polarities of the electrode plates 32 and 33.

When the recording medium P is attracted to the attracting force generating means 31 as shown in FIG. 6, the positive / negative power supply 50 is grounded to the ground by the ground terminal, and +1 kV is supplied to the electrode plate 32 via the power supply brush 36. Then, -1 kV is supplied to the electrode plate 33 via the power supply brush 37.

The recording head 40 is grounded by a ground terminal 48 to ground. Recording head 40 using FIG.
2 shows the grounding means. The ink joint 47 of the recording head 40 is formed of stainless steel, and a ground terminal 48 provided there is grounded to a frame of the main body of the recording apparatus 1 by an electric wire 51. Since the ink 52 is water-based, the orifice section 40
b is also grounded to 0V. The base 40 of the recording head 40
When a is a metal, the base 40a can be directly grounded to 0V, and the orifice portion 40b can be grounded directly without the ink 52.

The recording medium P is conveyed in the direction of arrow F with the movement of the conveying means. FIG. 8 shows actual measured values of the surface potential of the recording medium P at this time. The recording medium P is indicated by an arrow F in FIG.
Therefore, the surface potential of the recording medium P at a position facing the recording head 40 changes. Midpoint of electrode plate 32 X32
Indicates the highest potential, and its value is about 0.3 kV. In addition, it is almost 0 kV at the midpoint Xc of the electrode interval, and about 0 kV at the midpoint X33 of the electrode plate 33.
It shows -0.3 kV. These voltage values are determined by the suction force generating means.
The size varies depending on the dimensions of 31, the thickness of the base layer 16a and the surface layer 16b, the material, and the humidity.

To clarify the features of the above configuration, FIG.
FIG. 10 is used to compare with the state of suction in the conventional image recording apparatus. Unlike the embodiment shown in FIG. 6, FIG.
In the conventional configuration shown in FIG. 1, 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,
The generated attraction force is the same as in the embodiment described with reference to FIG.

However, as shown in FIG. 10, in the surface potential of the recording medium P, the highest potential is 1. at the midpoint X32 of the electrode plate 32.
3 kV, and approximately 1 kV at the midpoint Xc between the electrodes,
It showed about 0.7 kV at 33 midpoint X33. Ie recording head
The absolute value of the electric field between 40 and the surface of the recording medium P is up to 0.3 kV in the present embodiment, whereas it is up to 1.3 kV in the conventional example.

FIG. 11 shows the recording head 40 and the recording medium P.
The amount of displacement of the landing position of the ink droplet 49 due to the electric field with the surface is shown. In this figure, the ejection timing is shifted at 600 dpi to avoid ejection from adjacent nozzles, and every third dot (12
7 shows a graph of a shift amount when ejecting adjacent ink droplets at an interval of 7 μm (at intervals of 7 μm) and a shift amount at a time of discharging every 8 dots (interval of 340 μm).

As shown in the figure, for example, when ink is ejected every three dots, according to the present embodiment, the maximum potential is set to 0.
Since it is 3 kV, it can be settled with a shift of about 4 μm, whereas in the conventional example, the shift is about 40 μm because the maximum potential is 1.3 kV. In addition, even when ink is ejected every eight dots, according to the present invention, the deviation can be settled by about 1 μm, whereas in the comparative example, a deviation of about 10 μm occurs.

As described above, according to the present invention, while maintaining the same suction force, the amount of displacement of the landing position of the ink droplet can be greatly suppressed, and the recording quality can be improved. Further, since the effect becomes more remarkable as the interval between the ink droplets 49 becomes smaller, an even higher effect can be obtained in a high-resolution image recording apparatus such as 1200 dpi and 2400 dpi.

In the present embodiment, the application of ± 1 kV by the positive / negative power supply 50 has been described. 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 attraction force is weakened, and problems such as floating of the recording medium P occur. To increase the attraction force, a voltage of about ± 3 kV may be applied, but as the voltage increases, the landing position shift increases.
However, even in this case, it can be seen that the deviation amount of the landing position is smaller than in the conventional example.

[Other Embodiments] In the above-described embodiment, the suction force generating means 31 is formed integrally with the inside of the conveyor belt 16, but the present invention is not limited to this. An electrode plate provided with an electrode on the surface may be fixedly provided below. In this case, only the belt member can be driven to rotate, and the recording medium can be conveyed therewith. 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.

Instead of the belt member, a comb-shaped electrode may be provided on the surface of the drum member, and the recording medium may be adsorbed and conveyed on this surface. In this case, it is difficult to reduce the size of the apparatus in terms of the layout, but the stability of the transfer speed and the transfer direction can be easily obtained.

Although the present embodiment has been described using the aqueous ink as the liquid ink, it is also effective in preventing the landing accuracy from being deteriorated due to the polarization of the oil-based ink. In addition, even when recording is performed by flying powder or the like instead of liquid ink, a recording agent that is polarized by an electric field can be applied. Note that the recording agent may be a colored member or a colorant that is colored by some means. For example, a coloring substance is applied on a recording medium, and a predetermined portion is colored by flying a liquid ink having a colorless developer, or a colorless adhesive ink is flying on the recording medium, and a powder toner is attached. The present invention can be applied to a case where recording is performed.

[0042]

As described above, in the image recording apparatus according to the present invention, even if a high voltage is applied to the attraction force generating means in order to generate a sufficient attraction force, the flying of the adjacent recording material is disturbed. In addition, the displacement amount of the landing position can be extremely reduced. In particular, it is 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 displacement of the landing position can be suppressed even at a high density of 600 dpi or more. Further, the effect of the present invention increases as the density increases to 1200 dpi and 2400 dpi.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating 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 transport belt.

FIG. 4 is a sectional view taken along line aa of FIG. 3 for explaining an attraction force generating means.

FIG. 5 is a front view illustrating power supply to a transport belt.

FIG. 6 is a diagram illustrating a circuit configuration of an attraction force generating 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 illustrating the surface potential of a conventional recording medium.

FIG. 11 is a diagram illustrating the relationship between the surface potential and the amount of displacement of ink.

FIG. 12 is a diagram illustrating a conventional image recording apparatus having a recording mechanism and a suction mechanism using electrostatic force.

[Explanation of symbols]

 P ... recording medium 1 ... recording device 2 ... feeding section 3 ... transport section 4 ... discharge section 5 ... recording section 6 ... base 7 ... pressure plate 7a ... separation pad 7b ... rotary shaft 8 ... pressure plate spring 9 ... separation claw 10 ... supply Feed roller 11… Manual feed tray 12… Feed roller 13… Lower guide 14… Guide 15… Sensor lever 16… Transport belt 16a… Base layer 16b… Surface layer 17… Drive roller 18… Transport roller 19… Pressure roller 20… Platen 21 … Arm 22… Spring 23… Pinch roller 25… Sheet pressing member 27… Driving motor 28… Cleaning roller pair 29… Electrification elimination brush 31… Adsorption force generating means 32… Electrode plate 32a… Power supply unit 33… Electrode plate 33a… Power supply unit 34 ... Power supply member 35 ... Support member 36 ... Power supply brush 37 ... Power supply brush 38 ... Cover 39 ... Sealing member 40 ... Recording head 40a ... Base 40b ... Orifice part 41 ... Head holder 41a ... Projection part 42 ... 43… Rail 44… Discharge roller 45… Spur 46… Discharge tray 47… Ink joint 48… Ground terminal 49… Ink drop 50… Positive and negative power supply 51… Wire 52… Ink 100… Record head 101… Nozzle 102… Ink drop 103… High voltage power supply

Claims (11)

[Claims] 1. A recording means for recording on a recording medium by flying a recording material, and a suction force generating means arranged to face the recording means and adsorbing the recording medium, wherein the suction force generating means Wherein the recording medium is attracted by applying a positive and a negative high voltage based on the potential of the recording means. 2. The image recording apparatus according to claim 1, wherein the recording agent is a liquid ink. 3. The attraction force generating means according to claim 1, wherein the attraction force generating means has a first electrode and a second electrode arranged opposite to the first electrode. Image recording device. 4. The attraction force generating means has a high voltage power supply grounded to a ground having the same potential as the recording means, and the high voltage power supply outputs 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 has a transport unit that moves the attracted recording medium with respect to the recording unit. apparatus. 6. The image recording apparatus according to claim 5, wherein said conveying means is a belt member. 7. The image recording apparatus according to claim 5, wherein said conveying means is a drum member. 8. The image recording apparatus according to claim 5, wherein said attraction force generating means is provided integrally with said transport means. 9. The apparatus according to claim 8, wherein said attraction force generating means is disposed below and adjacent to said transport means.
The image recording apparatus as described in the above. 10. A recording apparatus according to claim 1, wherein said recording means has a full-line type recording head in which a plurality of recording elements are arranged perpendicularly or at a predetermined angle to a moving direction of said conveying means over the entire width of a recording area of said recording medium. The image recording apparatus according to claim 1, wherein the image recording apparatus includes: 11. The recording head performs recording by ejecting liquid ink using thermal energy, and the image recording apparatus includes an electrothermal converter for generating thermal energy applied to the liquid ink. The image recording apparatus according to any one of claims 1 to 10, further comprising: