JP2873879B2 - Ink jet recording device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus that performs recording by discharging ink from a recording unit onto a recording material.

[Conventional technology]

Recording devices such as printers, copiers, and facsimiles that are used in conjunction with a computer or word processor, or used alone, form images on a recording material such as paper or a plastic thin plate based on image information. Is configured.

The recording apparatus can be classified into an ink jet type, a wire dot type, a thermal type, a laser beam type and the like according to a recording method.

Among them, the ink-jet type (ink-jet recording apparatus) performs recording by discharging ink from a recording means onto a recording material, and can record a high-definition image at a high speed, and is a non-impact type. And has the advantage that it is easy to record a color image using multicolor inks.

In particular, in the case of an ink-jet recording apparatus using an ink-jet recording means (recording head) that utilizes heat as ink ejection energy, electric power formed on a substrate through a semiconductor manufacturing process such as etching, vapor deposition, or sputtering. By forming the heat converter, the electrode, the liquid path wall, the top plate, and the like, it is possible to easily manufacture a device having a high-density liquid path arrangement (discharge port arrangement).

The ink (recording liquid) generally includes water, a solvent,
It is composed of dyes, pigments and the like. In an ink jet recording apparatus, an image is formed by causing such an ink to fly toward an opposing recording material in accordance with an image signal. In this case, the recording material needs to be conveyed while maintaining a certain gap between the recording material and the recording means.

Therefore, as means for forming a recording material guide surface for regulating the position of the recording surface of the recording material with respect to the recording means, in addition to a configuration using a transport roller and a platen, an endless belt also serving as a transport means or Often uses drums.

[Technical problem to be solved by the invention]

However, in the conventional ink jet recording apparatus, the ink adheres to a part other than the recording material due to scattering of the ejected ink and poor guidance of the recording material, and the back surface of the recording material becomes dirty or rusted. There was something.

Also, in the case of a transport system in which the surface of a transport member (belt, drum, etc.) is made of an insulator so that electric charges are injected into the recording material, a conductive material is used to transport the recording material by electrostatic attraction. The ink adheres to the conveying member to lower its surface resistance, thereby reducing the adsorption force due to leakage of electric charge, etc., and the recording material floats from the guide surface and contacts the recording head, or In some cases, the sheet may hit a guide member or the like and cause a conveyance failure.

The present invention has been made in view of such technical problems, and an object of the present invention is to improve the cleaning ability of a recording material guide surface, and to improve the reliability of a recording apparatus and the quality of a recorded image. In addition, an object of the present invention is to provide an ink jet recording apparatus capable of preventing a decrease in suction force due to a decrease in insulating property of a recording material guide surface and preventing a conveyance failure.

[Means for solving the problem]

In order to achieve the above object, the present invention provides an ink jet recording apparatus which performs recording by discharging ink from a recording means to a recording material, wherein the recording medium is provided for regulating a position of a recording surface of the recording material with respect to the recording means. A recording material guide surface is provided, and an electrostatic suction transport member that electrostatically attracts the recording material to the guide surface and transports the recording material, and a liquid having an electrical resistance value higher than the electrical resistance value of the ink is used. And a cleaning member for cleaning the electrostatic suction conveyance member.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 2 is a longitudinal sectional view showing the overall configuration of the ink jet recording apparatus according to one embodiment of the present invention, and is a longitudinal sectional view showing the structure of the recording section and the transport means of the ink jet recording apparatus shown in FIG. .

In FIG. 2, a recording material 7 is stored in a stacked state in a sheet cassette 6 detachably mounted on the apparatus main body, and one recording material 7 is placed near an exit of the sheet cassette 6.
A pick-up roller 8 for feeding out one sheet at a time is provided, and a feed roller 9, a guide member 10, and a registration roller (feed roller) 11 are provided between the pick-up roller 8 and the electrostatic attraction belt (conveying belt) 4. Are arranged.

The registration roller 11 is for taking the timing of recording by the recording means 1. The recording material 7 is fed onto the endless belt-shaped transport belt 4 while being timed by the registration rollers 11, and the transport belt 4 causes recording means (recording heads) 1B, 1C, 1M, 1Y.
Is conveyed through a recording unit facing the printer.

1 and 2, recording heads 1B, 1C, 1M, and 1Y as recording means are positioned and mounted on a block 2. In the illustrated example, four print heads are used. In the case of full-color printing, these print heads are used.
1B, 1C, 1M, and 1Y are used for recording with, for example, black, cyan, magenta, and yellow inks.

In the following description, the recording means 1 or the recording head 1 will be simply referred to when the four recording means (recording heads) 1B, 1C, 1M, and 1Y are shown as a whole or any one of them.
Indicated by

In FIG. 2, a recovery unit 3 for recovering the ejection of the recording unit 2 is disposed obliquely above the block 2.

The block 2 and the recovery means 3 are movably supported at predetermined positions, and are at positions shown by solid lines during recording, but rotate the block 2 around the fulcrum 12 during non-recording including a recovery operation. Then, by moving the recovery means 3 to the position indicated by the two-dot chain line, the porous member or cap provided in the recovery means 3 The ink ejection section (ejection port face) is configured to be brought into contact with and capped (closed).

1 and 2, a sheet-shaped recording material 7 such as a sheet of paper or a thin plastic sheet is conveyed through a recording unit by an endless belt-shaped conveyance belt 4. The transport belt 4 is charged by a charging roller 17 disposed at a predetermined position on the traveling path, and is an electrostatic attracting member (which can electrostatically attract the recording material 7 such as a fed sheet or a thin plastic plate). Belt).

The portion of the electrostatic attraction belt 4 facing the recording means includes:
The transport path is regulated by the back platen 5, and a recording material guide surface 18 for regulating the position of the recording surface of the recording material 7 with respect to the ejection port surface of the recording means 1 is formed. The gap between the recording means 1 and the recording material 7 in the recording section is kept at a high accuracy, for example, 0.5 mm ± 0.1 mm, and a narrow interval.

At a position on the upstream side of the recording means 1 of the electrostatic attraction belt 4, a charge elimination mylar 19 for removing electric charges on the recording surface side of the recording material 7 is disposed. As a result, the suction force of the recording material 7 by the electrostatic suction belt 4 is increased, and the recording material 7 is moved to the electrostatic suction belt 4.
Can be transported in close contact.

That is, the recording material 7 is conveyed while being firmly adsorbed on the electrostatic attraction belt 4 and hardly lifted off the electrostatic attraction belt 4, as described above. It can be transported through a narrow gap.

In FIG. 2, a heater 13 and a fan 14 for promoting drying and fixing of the recorded image ink on the recording material 7 are provided on the downstream side of the endless belt-shaped conveyance belt 4.
Is provided at the outlet on the downstream side, and a discharge roller 15 for discharging the recording material 7 to the outside of the apparatus main body is provided. A tray 16 for sequentially stocking the recording materials 7 is provided.

The recording unit (recording head) 1 is an inkjet recording unit that discharges ink using thermal energy, and includes an electrothermal converter for generating thermal energy.

Further, the ink jet recording means 1 performs recording by discharging ink from discharge ports by utilizing a pressure change caused by growth and shrinkage of bubbles caused by film boiling caused by thermal energy applied by the electrothermal transducer. Things.

FIG. 3 is a partial perspective view schematically showing the configuration of the ink ejection section of the recording means 1. In FIG. 3, a plurality of electrothermal transducers 22 and a plurality of electrothermal transducers 22 are formed on a substrate 21 of the recording means 1 by a manufacturing process (thin film forming method or the like) similar to that of a semiconductor with a layer of a thin film 23 interposed therebetween. Wiring is formed. As shown, the electrothermal transducers 22 are arranged at positions corresponding to respective discharge ports and liquid paths described later.

On the substrate 21 (on the thin film 23 on the substrate 21), a liquid path forming member 24 having a plurality of liquid path walls 24A formed in parallel on a lower surface at predetermined intervals is joined. Further, a top plate 25 is joined to the upper surface of the liquid path forming member 24.

The liquid passage 26 is formed between the liquid passage walls 24A, and the liquid passage forming member 24 is positioned at such a position that the electrothermal transducers 22 are arranged at predetermined positions inside the liquid passages 26. Positioned and joined in relation. Each of the liquid path walls 24A has a predetermined length, and a rear end of each of the liquid paths 26 is formed between the liquid path forming member 24 and the substrate.
It communicates with a common liquid chamber 27 formed between the liquid chamber 21 and the thin film 23 (or the thin film 23).

On the other hand, the other end (front end) of each liquid path 26 is open at the discharge port surface (face surface) 28 of the recording head 1, and a discharge port 29 is formed by each opening.

In this way, by energizing (applying a pulse voltage) the electrothermal transducer 22 such as a heating resistor to generate heat, the ink in the liquid passage 26 is film-boiled. An ink jet type recording means (recording head) 1 for discharging droplets is configured.

The recording means 1 is mounted in such a manner that the direction of arrangement of the plurality of discharge ports 29 intersects the direction in which the recording material 7 is conveyed.

In the ink jet recording apparatus having the configuration shown in FIGS. 1 to 3, when the recording material 7 comes to face each recording means 1, ink is ejected according to an image signal to record an image.

In this case, if the gap between the recording means 1 and the recording material 7 is widened, a good image recording cannot be obtained due to a large ink landing point error. On the other hand, when the gap is small, the recording material 7
When the recording material floats from the belt 4, the recording material 7 comes into contact with the recording head 1, and an image defect or a conveyance defect occurs.

That is, the electrostatic attraction force between the electrostatic attraction belt 4 and the recording material 7 has a great effect on the reliability and image quality of the recording apparatus.

By the way, in the ink jet recording apparatus, when the ink flies, the main droplet adheres to the recording material 7 to form an image, but the sub-drop (satellite) generated at the time of flying (ejection) becomes a mist. Floating in the device.

When the floating ink is generated, problems such as contamination of the belt 4 and occurrence of conveyance failure on the recording material guide surface 18 facing the recording unit 1 occur.

Further, due to such a problem, an image is formed on the electrostatic attraction belt 4 or the floating ink is
When the ink adheres to and accumulates on the surface, the ink is composed of water, a solvent, a dye, and the like. Leakage and the like will occur.

Therefore, conventionally, the ink on the recording material guide surface 18 has been cleaned with a blade or an ink absorber. However, in the conventional method, only the blade or the ink absorber was used. However, the above-described problem remains.

Therefore, in this embodiment, as shown in FIGS. 1 and 2, a movable blade 31 for wiping and cleaning the surface of the conveyor belt (electrostatic attraction belt) 4 is provided at a predetermined position. In addition to the waste ink receiver 32, a felt 33 impregnated with a liquid having higher electric resistance than ink such as silicon oil is provided.

The felt 33 is provided on the recording material guide surface 18 of the transport belt 4.
It is for wiping off and cleaning, and in the illustrated example,
It is arranged downstream of the blade 31 in the belt traveling direction.

The blade 31 and the felt 33 are supported by their holders so as to be rotatable about a fulcrum 34. By rotating the blade 31 and the felt 33 upward based on a predetermined control sequence, the recording material guide of the transport belt 4 is guided. The cleaning operation is performed by pressing against the surface 18.

By using such a cleaning felt 33, it has become possible to absorb and remove ink that could not be removed by the blade 31.

At the same time, when the felt 33 is wiped off, the liquid having a large electric resistance adheres to the surface of the conveyor belt 4, so that the recording material guide surface 18 of the conveyor belt 4 can be kept insulative.

Further, since the felt 33 is used, if the felt 33 is impregnated with high-viscosity silicone oil and cleaned, the durability of the felt 33 can be improved.

On the other hand, if a low-viscosity oil is used, the curl (warping) phenomenon of the recording material 7 recorded with ink can be prevented.

In this manner, the ink attached to the recording material guide surface 18 is cleaned and removed by using a liquid having a different component composition from the liquid (ink) used for image formation, thereby improving the cleaning ability, and improving the reliability of the recording apparatus and the image quality. An ink jet recording apparatus capable of improving quality was obtained.

Further, since the electrostatic attraction conveyance member is cleaned by using a liquid having a higher electric resistance value than the ink, it is possible to prevent a decrease in the attraction force due to a decrease in insulating property of the recording material guide surface 18 and to prevent a conveyance failure of the recording material 7. An ink jet recording apparatus that can be prevented was obtained.

FIG. 4 is a longitudinal sectional view showing a configuration of a recording unit and a transport belt of an ink jet recording apparatus according to another embodiment of the present invention.

In FIG. 4, a controllable voltage applying means 35 is provided to the neutralization mylar 19 disposed upstream of the recording means 1 in the transport direction.
The charge elimination mylar 19 is configured to be capable of forcibly applying a voltage to the recording material 7 in accordance with the polarity and magnitude of the charge induced on the recording material 7. I have.

 The reason for providing the voltage applying means 35 will be described below.

In a transport system that performs electrostatic attraction, the discharge direction of ink may change due to an electric field formed by charges on the transport belt 4. For example, the recording material guide surface 18 of the transport belt 4
When a positive charge is injected into the recording medium 7, a negative charge is induced on the back surface (belt side) of the recording material 7, and a positive charge is induced on the recording surface. Therefore, in order to increase the adsorption power,
At 19, the charge on the recording surface is removed.

However, as in the embodiment shown in FIG. 1, there is a case where the charge of the recording material 7 is not completely removed simply by grounding the neutralization mylar 19.

When the ink is caused to fly on the recording material 7 where such charges remain, charges are also induced in the ink droplets. For example, when the main droplet becomes negative and the sub-drop becomes positive by this inducing manner, the sub-drop having small inertia is sucked to the ejection port surface 28 side, and finally, the ejection port 29 is filled with ink. Blockage may result in ejection failure or ejection failure.

Therefore, according to the configuration of the present embodiment, the static elimination mylar 19
If the control is performed such that a negative charge is forcibly applied according to the magnitude of the positive charge on the recording material 7,
The above residual charges can be canceled out, and the above-described non-ejection and ejection failure can be eliminated.

In this case, since the type and strength of the electric charge on the transport belt 4 fluctuate depending on the time and place, the voltage applied to the charge removing mylar 19 is controlled according to the fluctuation of the electric charge, so that the electric charge on the recording material 7 is controlled. Can be completely canceled.

Also in the present embodiment, since the felt 33 applies oil having a large electric resistance (low conductivity) to the conveyor belt 4, it is possible to suppress a charge fluctuation due to a partial ink stain on the conveyor belt 4. it can.

The embodiment shown in FIG. 4 is different from the embodiment shown in FIGS. 1 to 3 in the points described above, but has substantially the same structure in other parts, and accordingly, the corresponding parts are the same. Reference numerals are used, and their detailed description is omitted.

According to the embodiment shown in FIG. 4, the same effect as that of the above-described embodiment can be obtained. In addition, since the voltage is applied by the neutralization mylar 19 so as to forcibly cancel the charge of the conveyor belt 4, the recording material Thus, an ink jet recording apparatus capable of eliminating the decrease in the adsorbing force of No. 7 and improving the reliability and image quality of the recording apparatus was obtained.

In each of the above-described embodiments, the oil-impregnated felt 33 was used.
Although the case of sliding contact has been described, the present invention is not limited to this. For example, instead of felt, a porous member, cloth, paper, etc., as long as the material can be impregnated with a liquid, such as oil. Various materials can be used.

In addition, the shape and structure of the felt 33 can be embodied in various modes such as a roller shape or a rotatable support.

The present invention relates to a color inkjet recording apparatus having a plurality of recording means (recording heads) for recording in different colors, an inkjet recording apparatus for recording with one recording means, or a plurality of recording apparatuses having the same color but different densities. Such as an inkjet recording device for gradation recording using means,
The present invention can be applied similarly regardless of the number of recording means, and can achieve the same operation and effect.

Further, the present invention is applicable to a serial recording type ink jet recording apparatus in which a recording means (recording head) is mounted on a carriage moving along a recording material, or to the whole or a part of the widthwise recording area of the recording material. For example, a line-type inkjet recording apparatus using a line storage unit having a length that can be applied can be applied in the same manner regardless of the type of recording method, and can achieve the same effect.

Further, as a recording unit (recording head) in each of the above embodiments, a convertible cartridge type recording unit in which a recording head and an ink tank are integrated, or
The recording head and the ink tank are separated from each other, and for example, recording means having various structures such as a recording means connected via a coupler and a tube can be used.

Incidentally, the present invention, if the inkjet recording apparatus,
For example, the present invention can be applied to a device using a recording means (recording head) using an electromechanical transducer such as a piezo element. Among them, an excellent effect is obtained in a valve jet type ink jet recording device proposed by Canon Inc. To bring. According to such a method, it is possible to achieve higher density and higher definition of recording.

The representative configuration and principle are preferably performed using the basic principle disclosed in, for example, US Pat. Nos. 4,723,129 and 4,740,796.

This method can be applied to any of the so-called on-demand type and continuous type. In particular, in the case of the on-demand type, it corresponds to a sheet or a liquid path holding a liquid (ink). By applying at least one drive signal corresponding to the recording information and providing a rapid temperature rise exceeding nucleate boiling to the arranged electrothermal transducer, heat energy is generated in the electrothermal transducer, and recording is performed. This is effective because the film can be boiled on the heat-acting surface of the means (recording head) and, as a result, bubbles in the liquid (ink) can be formed in one-to-one correspondence with this drive signal.

By discharging the liquid (ink) through the discharge opening by the growth and contraction of the bubble, at least one droplet is formed.

When the drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of a liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable. As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,434,262 are suitable.

Further, if the conditions described in US Pat. No. 4,313,124 relating to the invention relating to the temperature rise rate of the heat acting surface are adopted, more excellent recording can be performed.

As a configuration of the recording head, in addition to the combination configuration (a linear liquid flow path or a right-angled liquid flow path) of a discharge port, a liquid path, and an electrothermal converter as disclosed in each of the above-mentioned specifications, a heat acting section A configuration using U.S. Pat. No. 4,558,333 and U.S. Pat. No. 4,459,600, which disclose a configuration in which the is bent, is also included in the present invention.

In addition, JP-A-59-123670 discloses a configuration in which a common slit is used as a discharge portion of an electrothermal converter for a plurality of electrothermal converters, and an aperture for absorbing pressure waves of thermal energy. The present invention is also effective as a configuration based on JP-A-59-138461 which discloses a configuration corresponding to a discharge unit.

That is, according to the present invention, the recording can be reliably and efficiently performed regardless of the form of the recording head.

Further, the present invention can be effectively applied to a full-line type recording head having a length corresponding to the maximum width of a recording medium on which a recording apparatus can record.

Such a recording head may have a configuration that satisfies the length by a combination of a plurality of recording heads, or a configuration as one integrally formed recording head.

In addition, even with the serial type printer as in the above example, the recording head fixed to the main unit or attached to the main unit enables electrical connection with the main unit and supply of ink from the main unit. The present invention is also effective when a replaceable chip type print head or a cartridge type print head having an ink tank provided integrally with the print head itself is used.

It is preferable to add recovery means for the print head, preliminary auxiliary means, and the like provided as a configuration of the printing apparatus in the present invention since the effects of the present invention can be further stabilized.

If these are specifically mentioned, for the recording head,
Capping means, cleaning means, pressurizing or suction means, preheating means using an electrothermal converter or another heating element or a combination thereof, and a predischarge mode in which discharge is performed separately from recording can also be performed. This is effective for performing stable recording.

In addition, as for the recording or the number of recording beds to be mounted, for example, only one recording bed is provided corresponding to a single color ink, and a plurality of recording beds corresponding to a plurality of inks having different recording colors and densities are provided. It may be provided.

That is, for example, as the recording mode of the recording device,
Not only the recording mode of only the mainstream color such as black, but also a combination of a plurality of recording heads or a plurality of recording heads, any of which may be used, but at least one of multiple colors of different colors or full color by mixing colors. The present invention is also very effective for a device provided with such a device.

In addition, in the embodiments of the present invention described above, the ink is described as a liquid, but an ink that solidifies at room temperature or below, and softens or liquefies at room temperature, or in an ink jet system, Generally, the temperature of the ink itself is controlled within a range of 30 ° C. or more and 70 ° C. or less to control the temperature so that the viscosity of the ink is in a stable ejection range. Anything should do.

In addition, positively prevent temperature rise due to thermal energy by using it as energy for changing the state of the ink from a solid state to a liquid state, or use an ink that solidifies in a standing state to prevent evaporation of the ink. In any case, the ink is liquefied by the application of the heat energy according to the recording signal, and the ink is liquefied, and the liquid ink is discharged. The present invention is also applicable to a case where ink having a property of being liquefied for the first time by heat energy is used.

In such a case, the ink is described in JP-A-54-56847 or JP-A-60-71260.
It may be configured such that it is opposed to the electrothermal converter in a state where it is held as a liquid or solid substance in the concave portion or through hole of the porous sheet.

In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

In addition, the form of the inkjet recording apparatus according to the present invention includes, in addition to those used as image output terminals of information processing equipment such as a computer, a copying apparatus combined with a reader or the like, and a facsimile apparatus having a transmission / reception function. What you take may be used.

〔The invention's effect〕

As is apparent from the above description, according to the present invention, in an ink jet recording apparatus that performs recording by discharging ink from a recording unit to a recording material, the position of the recording surface of the recording material with respect to the recording unit is regulated. A recording material guiding surface for conveying the recording material by electrostatically adsorbing the recording material on the guiding surface, and an electric resistance value higher than the electric resistance value of the ink. A cleaning member for cleaning the electrostatic suction conveyance member using a liquid, so that the cleaning ability of the recording material guide surface is improved, and the reliability of the recording apparatus and the quality of the recorded image are improved. In addition, since the electrostatic attraction conveyance member is cleaned using a liquid having a higher electric resistance value than the ink, the suction force is prevented from decreasing due to the lowering of the insulating property of the recording material guide surface, and the conveyance failure is prevented. Can do An ink jet recording apparatus is provided that can.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a recording unit and a conveying means of an ink jet recording apparatus according to an embodiment of the present invention, FIG. 2 is a longitudinal sectional view of an ink jet recording apparatus having the recording unit and the conveying means of FIG. FIG. 3 is a partially cutaway perspective view schematically showing the structure of an ink ejection section of the recording means in FIG. 1, and FIG. 4 is a recording section and transport means of an ink jet recording apparatus according to another embodiment of the present invention. FIG. In the following, reference numerals indicating major components in the drawings are listed. 1, 1B, 1C, 1M, 1Y ... recording means (recording head), 4 ...
... Conveying belt (electrostatic attraction belt), 7 ... Recording material, 11
... Registration roller, 17 Charging roller, 18 Guide surface of recording material (conveying belt surface), 19 ... Mylar, 22
…… Electrothermal converter, 26 …… Liquid channel, 28 …… Discharge port surface, 29…
... Discharge port, 31 ... Blade, 33 ... Felt, 35 ... Voltage applying means.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B41J 2 / 01,29 / 00

Claims (3)

(57) [Claims] 1. An ink jet recording apparatus for performing recording by discharging ink from a recording means to a recording material, comprising a recording material guiding surface for regulating a position of a recording surface of the recording material with respect to the recording means. An electrostatic suction transport member that electrostatically attracts the recording material to the guide surface and transports the recording material; and the electrostatic suction transport using a liquid having an electrical resistance higher than the electrical resistance of the ink. An ink jet recording apparatus, comprising: a cleaning member for cleaning a member. 2. The recording device according to claim 1, wherein the recording device is a recording device that discharges ink using thermal energy, and is an ink jet recording device that includes an electrothermal converter for generating thermal energy. The ink-jet recording apparatus according to claim 1. 3. The method according to claim 1, wherein the recording means discharges ink from a discharge port by utilizing a state change caused by growth of bubbles due to film boiling caused by thermal energy applied by the electrothermal transducer. The inkjet recording apparatus according to claim 2.