JPH09239987A - Image recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the jetting direction of an electrically charged ink and its dropping spot on a recording medium from being disturbed by providing a static eliminating means for removing an electric charge off the print face of a recording medium between the transport means of the recording medium and a printing head. SOLUTION: A static eliminator 24 is arranged in such a manner that the static eliminator 24 comes into c tact with the print face of a recording medium, between a transport device 22 and a printing head 1. The width, i.e., the length in the X axial direction, of the static eliminator 24 is almost the same as the width of the recording medium 12. The device 24 is formed of an electroconductive member, and is grounded. Consequently, the recording medium 12 is transported by the transport device 22 and comes into contact with the static eliminator 24 before reaching the printing head 1. In this case, the device 24 is grounded, so that an electric charge on the recording medium 12 passes through the device 24 and a grounding wire and is removed, if the recording medium 12 is electrically charged. As a result, the recording medium 12 is electrically neutralized and the jetting of an electrically charged ink is not disturbed when the recording medium 12 is transported to the surface of the printing head 1.

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 such as a copying machine, a facsimile, a printer, etc., and more specifically, an ink gas is intermittently ejected and selectively adheres to or permeates a recording medium. The present invention relates to an image recording apparatus that forms an image by doing so.

[0002]

2. Description of the Related Art In Japanese Patent Application No. 7-49778, the applicant of the present invention intermittently discharges a gas obtained by vaporizing ink in accordance with an electric signal corresponding to image data to be recorded, and deposits it on a recording medium. Alternatively, a new image recording method and device for permeating and obtaining an image is proposed. The configuration of the image recording apparatus includes heating means for evaporating ink by heating, ejecting means for ejecting the vaporized ink onto a recording medium, and intermittent heating of the ink heated according to image data corresponding to an image. Discharge control means for controlling the vaporized ink so that the discharge means discharges the ink.
The discharge control means includes a charging electrode section for charging the ink and a back electrode section arranged on the back surface of the recording medium for guiding the ink charged by the charging electrode section onto the recording medium. And a control section for controlling the operation of the shutter section according to image data.
The heating unit, the charging electrode unit, and the shutter unit are integrated into a print head.

A more detailed description will be given below with reference to the drawings.
FIG. 10 is a schematic diagram showing the configuration of the above-described image recording device. A powder ink 3 is stored inside the print head 1. The print head 1 has an electric heater 13 for heating the ink 3 and a heating device 2 including a heat radiating plate (not shown). And a thin wire electrode of 50 to 80 μm as a charging electrode 4 for charging the heated ink 3 ″, and an ejection hole 14. The ejection hole 14 of the ink 3 ″ is provided as shown in FIG. A plurality of electric field shutters 8 are provided, and electric field shutters 8 are provided on both sides of the ejection hole. The plurality of ejection holes are formed over a length corresponding to the print width, and the interval between the ejection holes is 200 μm when the recording density is 150 dpi.

As shown in the perspective view of FIG. 12, the discharge hole 14 has a structure in which the discharge hole for the ink 3 "is a slit 14 ', and the electric field shutters 8 are provided on both sides of the long side of the slit 14'. The length L of the slit 14 'may be a length corresponding to the print width in the case of a line head, for example, A4.
The size is about 200 mm, the A5 size is about 140 mm, and the width W of the slit 14 'is set to a recording density of 15 mm.
0 dpi is set to 200 μm. When the discharge holes are slits, there is an advantage that clogging is less likely to occur as compared with the case where the discharge holes shown in FIG. 11 are formed.

At the time of printing, the ink 3 is heated and vaporized by the heating device 2. As a color material of the ink, when a colored ink is used, yellow is an anthryothothiazole-based, quinophthalone-based, pyrazolonazo-based, pyridoneazo-based, styryl-based, etc., and magenta is anthraquinone-based, dicyanoimidazole-based, thiadiazoleazo-based, trisia For non-vinyl type, for cyan, azo type,
Anthraquinone series, naphthoquinone series, indoaniline series, etc. can be used. The ink 3 is vaporized into a gas ink 3 ″. At this time, by applying a voltage of +2 to 5 kV to the charging electrode 4, a corona discharge is generated in the direction of the heating device 2 which is grounded, and the gas ink 3 ″. Is charged with positive ions. The charged gaseous ink 3 ″ is guided toward the recording medium 12 by applying a negative voltage of −0.5 to −2 kV to the back electrode 11 provided on the back side of the printing surface of the recording medium 12. To be done.

Here, the electric field shutter 8 is composed of a common electrode 8a and a control electrode 8b provided in a comb-teeth shape at intervals of 169 μm corresponding to the recording density. Common electrode 8
a is grounded, and the control electrode 8b has a control unit 9 corresponding to an electric signal of image data to be recorded.
An output signal of 50 V to 1 kV (High level: H) or 0 V (Low level: L) is normally applied.

Specifically, for example, when the voltage of the control electrode 8b is 500 V (H), the electric field shutter 8 is turned on and an electric field is generated from the control electrode 8b toward the common electrode 8b, so that the electric charge is positively charged. The resulting ink 3 ″ cannot pass through the electric field shutter 8. On the other hand, the control electrode 8
When the voltage of b is 0 V (L), an electric field is not generated between the control electrode 8b and the common electrode 8a, so that the ink 3 ″ can be attracted to the electric field by the back electrode and pass through the electric field shutter 8. In this case, the electric field shutter 8
Is functioning as OFF.

In this way, the ON / OF of the voltage of the control electrode is
The ejection of ink can be intermittently controlled by F. Further, by controlling the electric potential of the electrode corresponding to each pixel, the passage of the gaseous ink 3 ″ can be controlled on a pixel-by-pixel basis.

[0009]

However, in the above-mentioned image recording apparatus, since the ejection of the charged ink is controlled by electrical control, charged bodies other than the electric field shutter and the back electrode are provided in the vicinity of the ink ejection portion. If present, the regular electric field is disturbed, and there is a problem that the charged ink may not be controlled as desired. In particular, when the recording medium is charged, adverse effects such as displacement of ink landing points on the recording medium occur, which causes deterioration of image quality. The recording medium may be charged when it is conveyed by a conveying unit such as a roller.

In view of these problems, the present invention provides an image recording apparatus capable of realizing high-definition image recording without disturbing the flight direction of the charged ink and the landing point of the ink on the recording medium. The purpose is to do.

[0011]

In order to solve the above problems, an image recording apparatus of the present invention has a conveying means for conveying a recording medium and a print head, and the print head heats ink to vaporize it. Means for discharging the vaporized ink onto the recording medium, and discharge control means for controlling the vaporized ink to be intermittently discharged according to the image data corresponding to the image. Between the means and the print head, there is provided static elimination means for removing charges on the print surface of the recording medium.

Further, in the image recording apparatus, the surface of the static eliminating means is formed of a material having conductivity and good slidability.

Further, in the image recording apparatus, the static eliminator is provided so as to face the print surface side and the back surface side of the recording medium, or has a brush shape.

Further, the image recording apparatus of the present invention has a conveying means for conveying the recording medium and a print head, the print head heating means for heating and vaporizing the ink, and the vaporized ink on the recording medium. And an ejection control unit that controls the vaporized ink to be ejected intermittently according to image data corresponding to the image, and the transport unit is made of a conductive member and is grounded. It is characterized by being

[0015]

1 is a cross-sectional view of an image recording apparatus of the present invention as viewed from the side, and FIG. 2 is a perspective view showing the main part thereof. For the sake of explanation, the direction in which the plurality of ink ejection portions and the electric field shutter 8 in FIG. 1 are formed, that is, the direction perpendicular to the paper surface is the X axis, and the direction intersecting the X axis at right angles and transporting the recording medium is the Y axis. In addition, the vertical direction of the plane of the paper that intersects both axes at right angles is the Z axis.

A solid or liquid ink 3 is contained in the ink chamber of the head 1, and a heating device 2 for heating and sublimating the ink 3 is provided on the bottom surface of the head 1 which is the lower portion of the ink chamber. There is. The heating device 2 is controlled by the heating control device 16. When the ink 3 is heated by the heating device, the inside of the ink chamber gradually becomes filled with the gaseous ink 3 ″.

Inside the head 1, 50 as a charging electrode is provided.
A thin wire electrode of ˜80 μm is arranged in the X-axis direction, that is, in the direction perpendicular to the paper surface, and is connected to the power supply 19,
A voltage of +2 to 5 kV is supplied. The gasified ink is positively charged by this charging electrode.

As shown in FIG. 11, a plurality of discharge holes and a plurality of electrodes forming the electric field shutter 8 are formed in the X-axis direction on the upper portion of the head 1 at intervals according to the resolution. Alternatively, as shown in FIG. 12, one slit and a plurality of electrodes corresponding to the resolution are formed on both sides of the slit.

Further, the print head 1 with the recording medium 12 sandwiched therebetween.
A back electrode 11 is provided on the opposite side to extend in the direction perpendicular to the plane of the drawing, and a negative voltage of -0.5 to -2 kV is applied by a power supply 20.

Between the transport device 22 and the print head 1,
A static eliminator 24 is provided. As shown in FIG. 2, the static eliminator 24 contacts the print surface of the recording medium 12 so that
It is arranged so as to extend in the X-axis direction. The width of the static eliminator 24,
That is, the length in the X-axis direction is substantially the same as the width of the recording medium 12, but may be longer than the width of the recording medium 12. The static eliminator 24 is formed of a conductive member such as metal, conductive rubber, or conductive resin, and is grounded.

The recording medium 12 is conveyed by the conveying device 22 from left to right on the paper surface. The recording medium 12 that has passed through the transport device 22 contacts the static eliminator 24 before reaching the print head 1. Since the static eliminator 24 is grounded, even if the recording medium 12 is charged, the static eliminator 24
The charge on the recording medium 12 that is in contact with the charge removal device 2
4 and the ground wire, and will be removed. Therefore, when the recording medium 12 is conveyed onto the print head 1, the recording medium 12 is electrically neutral, so that the flying of the charged ink is not disturbed.

Next, the basic operation of the image recording apparatus of the present application will be described with reference to the timing chart of FIG.

When a print command is output from the operator or an external information device, the CPU of the image recording device is operated at time t.
Outputs the print operation signal at _A. This signal is "L
"Level" indicates that the image recording apparatus is in a standby state, "H level" indicates that it is in operation, "rising" gives the timing to start the printing operation, and "falling" ends the printing operation. Give timing.

At the time t _B , the heating controller 16 drives the heating device 2 by using the rising edge of the signal (point t _A ) as a trigger. At this time, a voltage of +2 to 5 kV is applied to the charging electrode 4. When the heating device 2 is driven, the solid or liquid ink 3 is heated, and when the ink sublimation temperature T _g or higher is reached, the ink 3 becomes gaseous.
The amount of gaseous ink 3 ″ increases over time and reaches a threshold value at time t _{C. The} threshold value is the amount of gaseous ink that is sufficient to be ejected, If it is more than this, printing is possible. The gaseous ink 3 ″ is positively charged by corona discharge by the charging electrode 4.

The heating device is constantly controlled to a certain temperature T which is _{equal to} or higher than the ink sublimation temperature T _g . Where ΔT is
This is a value determined in consideration of temperature stability of the heating control device, changes in ambient temperature, etc. If ΔT is used and T = T _g + ΔT, when the ink sublimation temperature T _g is 140 ° C., for example, ΔT
= 15 ° C., control is performed so that T = 155 ° C.

At time t _D when the printable state is set,
The transport means 22 starts transporting the recording medium 12. Then, the recording medium 12 comes into contact with the charge eliminating means 24, so that the charges existing on the recording medium with which the charge eliminating means is in contact are removed. Since the recording medium is conveyed in the Y-axis direction, the charge is sequentially removed from the upper portion of the recording medium.

Further, at the time t _E after the recording medium is conveyed and passed the print head 1, a print start / end signal is output from the CPU to the control section of the ejection control device 9. As a means for detecting the time t _E , a light detecting element 23 such as an interrupter is installed at a position downstream of the print head 1 in the carrying direction, and the leading edge of the recording medium 12 can be detected.

More specifically, as shown in FIG. 2, a transmissive photo interrupter 23 is arranged at a position downstream of the print head 1 in the carrying direction. As the photo interrupter, for example, GP1L55 manufactured by Sharp Corporation can be used. Of course, it is not limited to the transmissive type, and may be the reflective type.

As the detection circuit, for example, a configuration as shown in FIG. 4A can be considered. The cathode which is the second terminal and the emitter which is the fourth terminal of the photo interrupter PI are both grounded, the anode of the first terminal is connected through the resistor R1, and the collector of the third terminal which is the output terminal is connected through the resistor R2.
To the power supply V _CC via. Furthermore, the output of the photo interrupter PI is connected to an input terminal of a logic element, for example, 74HC14 having a logic inverting function, and its output is the final output.

In the case of this configuration, the output of the photo interrupter PI when there is no recording medium 12 is at "L" level, so the output of the logic inverting element 74HC14 is at "H" level. When the leading edge of the recording medium 12 passes the photo interrupter, the photo interrupter output is "H".
It changes to the level, and the output of the logic inverting element changes to the "L" level.

FIG. 4B shows changes in the output waveform of the photo interrupter, and FIG. 4C shows changes in the output waveform of the logic inverting element. Time t ₁ represents the time when the leading edge of the recording medium passes the photodetecting element 23, and time t ₂ represents the time when the trailing edge of the recording medium passes the photodetecting element 23. Further, times t ₃ and t ₄ respectively represent the change timing of the logic inverting element based on the output signal of the photodetecting element 23. Based on the recording medium detection signal thus obtained, the CPU outputs a print start / end signal. For example, the falling edge of the recording medium detection signal shown in FIG. 4C may be used as a trigger. A simple generation method is obtained by passing the recording medium detection signal shown in FIG. 4C through another logical inversion element.

The print start / end signal indicates that the print head 1 is in the non-printing state when it is at the "L" level, and is in the printing state when it is at the "H" level.
"Falling" gives the timing of printing end.

The control section uses the rising edge of the print start / end signal as a trigger to turn on / off the electric field shutter 8.
The OFF control is started (point t _{E in} FIG. 4). The electric field shutter 8 is connected to a power source (not shown) that supplies a voltage of 500V, and 500V is applied to each control electrode 8b according to image data. At time t _E when the electric field shutter starts 0N / OFF, a voltage of -1 kV is applied to the back electrode to start printing. During printing, the recording medium 12 is conveyed in the Y-axis direction at a constant speed by the conveying device 22.

When the printing is completed, the print start / end signal becomes L level at time t _F , and the falling of this signal is used as a trigger for the heating device 2, the charging electrode 4, and the back electrode 11.
Are all off. The transport device 22 remains in operation until time t _I in order to eject the recording medium 12 even after printing is completed. At time t _I , a series of printing operations ends.

The recording medium 12 is the static eliminator 24.
Since the surface of the static eliminator contacting the recording medium 12 is formed of a member having good conductivity and slidability, the load on the conveyor 22 may be reduced. For example, it may be formed of a conductive fluororesin or the like.

FIG. 5 and FIG. 6 are perspective views of an essential part of an image recording apparatus showing another embodiment of the present invention. In the present embodiment, the static eliminator 24 is arranged not only on the printing surface of the recording medium but also on the back surface of the recording medium. As a result, it is possible to eliminate the influence of charges from the back surface of the recording medium. At this time, as shown in FIG. 6, the two static eliminators 24a and 24b are removed.
Do not necessarily have the same shape, and if the area of the portion in contact with the recording medium is minimized while ensuring the static elimination effect, the increase in load on the transport device 22 can be minimized. In the width direction of the recording medium, the recording medium 12 and the static eliminator 24 do not have to be in complete contact with each other, and may have, for example, a brush shape as shown in FIG. 7 or a sawtooth shape as shown in FIG. By making it into a brush shape, the contact surface with the recording medium can be made flexible, the printing surface is not damaged, and it is not necessary to strictly consider the parallelism between the recording medium and the static eliminator.

Further, FIG. 6 is a perspective view of a main part showing still another embodiment of the image recording apparatus of the present invention. The roller 22, which is a conveying device, is formed of a conductive member such as conductive rubber or conductive resin, and is grounded. According to this configuration, since the charge can be removed while the recording medium is being conveyed, it is not necessary to dispose a new charge removing device.

[0038]

As described above, since the charge eliminating means for removing the electric charge charged on the recording medium before the recording medium is conveyed to the print head is provided, the flight direction of the charged ink and the recording are performed. High-definition image recording can be performed without disturbing the landing point on the medium. Further, by forming the conveying means with a conductive member and grounding it, it is possible to remove the charges on the recording medium while conveying the recording medium without newly disposing a charge eliminating device. Has the effect.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an embodiment of the present invention.

FIG. 2 is a perspective view of a main part of the image recording apparatus shown in FIG.

FIG. 3 is a diagram showing the timing of each operation in the image recording apparatus of the present invention.

FIG. 4 is a circuit configuration diagram for detecting a leading edge of a recording medium.

FIG. 5 is a perspective view of an essential part showing another embodiment of the present invention.

FIG. 6 is a perspective view of a main part showing another embodiment of the present invention.

FIG. 7 is a perspective view of an essential part showing another embodiment of the present invention.

FIG. 8 is a perspective view of an essential part showing another embodiment of the present invention.

FIG. 9 is a perspective view of an essential part showing another embodiment of the present invention.

FIG. 10 is an overall configuration diagram of an image recording apparatus.

FIG. 11 is a perspective view illustrating a configuration of an electric field shutter unit.

FIG. 12 is a perspective view illustrating another configuration of the electric field shutter unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 print head 2 heating device 8 electric field shutter part 11 back electrode 12 recording medium 16 heating control device 22 carrier device 23 photodetector 24 static eliminator

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kaoru Higuchi 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation

Claims (5)

[Claims] 1. A conveying means for conveying a recording medium, a heating means for heating and vaporizing ink, an ejecting means for ejecting the vaporized ink onto the recording medium, and vaporizing according to image data corresponding to an image. And a print head including a discharge control unit that controls so that the ink is discharged intermittently, the charge on the print surface of the recording medium is removed between the transport unit and the print head. An image recording device, characterized in that it is provided with a static eliminating means for 2. The image recording apparatus according to claim 1, wherein
The image recording device, wherein the surface of the charge removing unit is formed of a material having electrical conductivity and good slidability. 3. The image recording apparatus according to claim 1 or 2, wherein the charge eliminating unit is provided so as to face the print surface side and the back surface side of the recording medium. 4. The image recording apparatus according to claim 1,
The image recording device, wherein the charge removing unit is in the shape of a brush. 5. A conveying means for conveying a recording medium, a heating means for heating and vaporizing ink, an ejecting means for ejecting the vaporized ink onto the recording medium, and vaporizing according to image data corresponding to an image. An image recording apparatus having a print head including an ejection control unit that controls so that the ink is intermittently ejected, wherein the conveying unit is made of a conductive member and is grounded. apparatus.