JP2001088307A - Ink jet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate manufacture of a recording head of an ink jet recorder. SOLUTION: This ink jet recorder comprises a recording head 101 having a plurality of ink ejection members provided on a grid electrode plate 105 and an opposing electrode 100 provided to tip sides of the ink ejection members. A folded projection provided to an edge of the grid electrode plate 105 standing toward the side of the ink ejection member and a plurality of cutouts for allowing ink ejected from each of the ink ejection members to pass therethrough toward the side of the opposing electrode 100 are formed on the grid electrode plate 105.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a head structure of an ink jet recording apparatus.

[0002]

2. Description of the Related Art Fine ink droplets are recorded on recording media (recording paper, etc.).
Ink jet printers that form dots by directly spraying them on the surface have advantages such as less noise and fewer parts compared to other printers. For this reason, the printer has attracted attention as a plain paper recording type printer.

As a recording method of such an ink jet printer, for example, (1) a recording method in which ink droplets are ejected from nozzles by the pressure of bubbles generated when ink is boiled by heat of a heating element; 2. Description of the Related Art A recording method in which ink droplets are ejected from nozzles by changing the volume of an ink chamber due to distortion of a piezoelectric element is known.
As a recording technique using the former recording method (1), a technique described in Japanese Patent Publication No. 56-9429 is known, and as a recording technique using the latter recording method (2), there is a technique described in The technique described in JP-A-53-12138 is known.

However, these recording methods (1) and (2)
Since the ink ejection amount per dot is constant and gradation expression by area modulation is difficult, it is not suitable for high-definition color printing.

[0005] Therefore, (3) an ink meniscus is formed in the ink discharge portion, and the ink meniscus is formed by static electricity from the ink meniscus.
A recording method of drawing ink or a colorant in ink has been proposed. According to the recording method (3), the ink ejection amount can be controlled by pulse width modulation of a pulse voltage that generates static electricity for drawing ink, so that a high-definition color inkjet printer can be realized.
For example, as a recording technique applying this recording method (3),
Japanese Patent Application Laid-Open No. 56-4467, Japanese Patent Application Laid-Open No.
The technique described in Japanese Patent Application Publication No. 02218 is known.

However, according to this recording method (3), during image recording, a high-speed cycle of about 5 kHz causes
On / off of the pulse voltage of about 500 V is repeated.
For this reason, it is necessary to mount an expensive high-voltage driving IC as a pulse voltage control circuit on an ink jet printer to which the recording method (3) is applied, particularly an ink jet printer using a multi-head. This is
This has led to an increase in the production cost of inkjet printers.

Therefore, Japanese Patent Application Laid-Open No. 9-234870 discloses
Japanese Patent Application Laid-Open No. H10-128979 discloses a technique for reducing the pulse voltage, specifically, as shown in FIG. 10, provided between the tips of a plurality of ejection electrodes and a counter electrode. A technique has been proposed in which a grid electrode plate is arranged in a gap of about 1 mm, and a constant voltage Vgrid is applied to the grid electrode plate. In the electrostatic multi-head having such a head structure, the electric field near the tip of each ejection electrode is determined by the potential gradient between the ejection electrode and the grid electrode plate. Since the interval provided between the tip of the discharge electrode and the grid electrode plate is at most about 50 to 100 μm,
An appropriate electric field can be generated in the vicinity of the tip of the discharge electrode only by superimposing the lower pulse voltage Vp on the bias voltage Vb. Thus, the pulse voltage Vp generated by the pulse generator is reduced.

In order to allow the ink ejected from the tip of each ejection electrode to pass to the counter electrode side, a grid hole is formed in the grid electrode plate in correspondence with the tip of each ejection electrode.

[0009]

However, the minimum pulse voltage value (hereinafter, referred to as a pulse voltage threshold value) required to discharge ink from each discharge electrode of the multi-head having the head structure shown in FIG. And variations in the dimensions of the grid holes in the grid electrode plate and in the distance between the tip of the discharge electrode and the grid electrode plate. If the pulse voltage threshold is unstable, the ejection stability of the ink may be reduced. Therefore, the multi-head having the head structure shown in FIG. 10 is required to have high processing accuracy, which causes a reduction in production efficiency and an increase in manufacturing cost of the ink jet printer.

Incidentally, a general electrostatic multi-head has a drawback that a recorded image on a recording medium is easily deteriorated. In the image recording on the recording medium, which has two sides of adjacent discharge electrodes of a discharge electrode M _i M _i-1, M _{i + 1} potential is different, in this case, the center of the discharge electrode M _i
This is because the trajectory of the ink ejected from the ink is bent by electric mutual interference (crosstalk) from the adjacent ejection electrodes Mi _-1 and Mi _{+ 1} on both sides thereof.

Therefore, it is a first object of the present invention to provide an ink jet recording apparatus which can be manufactured efficiently. It is a second object of the present invention to provide a low-voltage driven inkjet recording apparatus in which the stability of the pulse voltage threshold required for ink ejection is not easily affected by the dimensional accuracy of the recording head. The present invention aims at reducing the production cost of the ink jet recording apparatus by achieving these objects.

[0012]

In order to solve the above-mentioned problems, the present invention is directed to a recording head having a plurality of ink ejection members on a grid electrode plate and an opposing head disposed on the tip side of the plurality of ink ejection members. And an electrode, wherein the grid electrode plate has a folded crest in which an end of the grid electrode plate is raised toward the plurality of ink ejection members, and the ink ejected from each of the ink ejection members is directed to the counter electrode side. And a plurality of notches for allowing the ink to pass therethrough.

An ink jet recording apparatus further comprising an ink ejection member array and a counter electrode disposed on the tip side of each ink ejection member of the ink ejection member array, wherein the ink ejection member array and the counter electrode And a grid plate interposed between the ink discharge member array and the ink discharged from the ink discharge member to the counter electrode side, respectively. And a notch for letting through and a grid electrode are provided.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

First, the configuration of the ink jet recording apparatus according to the present embodiment will be described with reference to FIGS. However, here, a line-type inkjet recording apparatus for monochrome printing will be described as an example.

As shown in FIG. 1, a housing of the present ink jet recording apparatus has a grounded counter electrode 100 and a plurality of (the number of dots in one line) ink ejection members whose tips are directed toward the counter electrode 100. Head 101, recording head 1
01, a voltage generator for generating a pulse voltage or the like for ejecting ink, the counter electrode 100 and the recording head 10
1, a recording medium transport device (not shown) for feeding the recording medium A so as to pass through a gap of about 1 mm (hereinafter referred to as a recording position), and a controller for controlling the entire device
(Not shown) and the like. Details of these components are as follows.

The head substrate of the recording head 101 has a laminated structure as shown in FIG. 2, that is, a thickness of 50 μm to 1 μm, which is sequentially formed on the insulating substrate 202 by electroforming or the like.
Grid electrode plate 105 of about 00 μm, insulating substrate 202
Insulating film 203 dielectric constant epsilon _s than forming material is small has a three-layer structure laminated. Of these three layers 200, 105, 203, only one end of the grid electrode plate 105 is connected to the counter electrode 10 from the other two layers 202, 203.
It protrudes toward the zero side, and is folded up toward the insulating film 105 (toward the ink discharge member 200) at a fold at an appropriate distance (described later) from the tip of the ink discharge member.

On the head substrate, an ink ejection member 200 having a dielectric thin film 204 of polyimide or the like as a base is provided.
They are arranged at a predetermined pitch (usually about 250 μm) in a direction crossing the recording medium passing the recording position. Each of these ink discharge members 200 is formed of a dielectric thin film such as polyimide, and the reason will be described later.

In order to allow the ink flying from the front end of each ink discharge member 200 of such an ink discharge member row to pass to the counter electrode side, the protruding portion of the grid electrode plate 105 is provided with other layers 202 and 203 from the end surface thereof. The notch 105a is formed in the ink ejection member 200 in a one-to-one correspondence.

Further, partition walls 201 are formed on the head substrate to partition between adjacent ink ejection members in the ink ejection member row. Then, two recording electrodes 111 are embedded in each partition 201 so that each ink ejection member is sandwiched between two recording electrodes from both sides thereof. The embedding of the recording electrode 111 in the partition wall prevents the recording electrode 111 from contacting with the ink and prevents the ink from flying from the recording electrode 111 during application of the pulse voltage by the voltage generator. For. When a pulse voltage is applied to a pair of recording electrodes arranged on both sides of each of the ink ejection members, the ink is ejected from the tip of the ink ejection member to the counter electrode side. An electric field to be generated is formed. In order to concentrate such an electric field on the tip of the ink ejection member 200, the tip of each ink ejection member 200 is slightly (usually about 50 μm to 200 μm) from the end surface of the insulating film 203 or the like to the counter electrode side. It is projected. The insulating film 203 having a relative dielectric constant 率_s smaller than that of the material of the insulating substrate 202 is formed on the ink ejection member 200 and the insulating substrate 2.
The reason why the electric polarization is interposed between the ink ejecting member 200 and the insulating substrate 202 is to prevent the electric polarization of the insulating substrate 202 from hindering the concentration of the electric field near the tip of the ink ejection member 200. For example, when a glass substrate (ε _s : about 7 to 10) is used as the insulating substrate 202, an organic material such as polyimide (ε _s : about 3.4) may be used as a material for forming the insulating film 203. desirable.

A recording head having such a structure can be manufactured simply and accurately as described below by using a thin film process already established in a semiconductor manufacturing process or the like.

On the insulating substrate 202, the grid electrode plate 10
A thin metal film to become 5, is formed by sputtering or the like, and a photoresist is applied thereon. The coating film is exposed using a photomask having a predetermined shape to form a photoresist pattern on the metal thin film. The metal thin film is wet-etched using the photoresist pattern as a mask, and then the unnecessary photoresist pattern is removed. After the insulating film 105 is formed on a predetermined region on the metal thin film formed in a comb shape in this manner, the ink ejection member 200 with the dielectric thin film 204 as a base is formed on the insulating film 105. It is formed by the same photolithography and etching as the formation of a metal thin film. Also, by forming a dielectric film between each adjacent ink ejection member, forming two metal thin films on each of these dielectric films, and further forming a dielectric film thereon. A partition 201 in which two recording electrodes 111 are embedded is formed. Lastly, the portion corresponding to the comb-shaped teeth of the metal thin film is folded up toward the ink ejection member 200 by folding ridges at appropriate intervals from the tip of the ink ejection member 200.

If the recording head is manufactured using the thin film process as described above, the positioning accuracy between the tip of the ink discharge member and the notch of the grid electrode plate is determined by the mask alignment accuracy. At most several μm
To some extent. Therefore, it is not necessary to perform a complicated positioning process for obtaining the positioning accuracy between the leading end of the ink discharge member and the notch of the grid electrode plate, so that the manufacturing cost of the recording head can be suppressed. Further, if the print head is manufactured by using the thin film process, the throughput is improved. Therefore, it is expected that the manufacturing cost of the print head can be reduced.

The ink supply device is a low-viscosity petroleum-based solvent.
An ink tank 102 for storing an ink B in which charged colorant particles and a charge control agent are dispersed in (for example, isoparaffin having a viscosity of about 1 to 10 Pa · s), and between the ink tank 102 and the recording head 101. And two pumps 103a, 103b driven by the control of the controller.

The ink circulation system configured as described above has two systems for circulating ink between the recording head 101 and the ink tank 102 during recording of an image on a recording medium. Supply system for supplying ink B from the printer to the printhead 101, and the printhead 10
1 and an ink collection system for collecting the ink B from the ink tank 102. In the ink supply system, the ink B stored in the ink tank 102 is sucked up from the ink tank 102 into the pipe 104a by suction of the pump 103a, and is sent to the ink introduction path 110 of the recording head 101. The ink sent from the ink supply system to the ink introduction path 110 is supplied to the recording head 1.
01, is supplied to the base side of the partition 201, and then flows between the partitions by capillary action toward the tip of each ink ejection member, and further wraps around the back side of the head substrate to the ink recovery system. Be guided. Then, in the ink recovery system, the ink B remaining in the recording head 101 is removed by the suction of the pump 103B.
(Not shown) and is sucked into the pipe 104 b and collected in the ink tank 102.

Further, the voltage generating device operates the grid electrode plate 10 of the recording head 101 during the image recording on the recording medium.
5 is supplied to the grid power supply 10
9 Further, the voltage generator includes a bias power supply 10 for applying a bias voltage Vb (about 1.5 kV to 2.0 kV) to all the recording electrodes 111 of the recording head 101.
8. A pulse voltage Vp for causing ink droplets forming one dot of a recorded image to fly is superimposed on a bias voltage Vb, and this is applied to the recording electrodes 111 on both sides of the ink ejection member 200.
And a drive circuit 107 that supplies a recording signal pulse-width-modulated to each pulse generator 106 in accordance with image data from the outside (such as a personal computer).

Further, the recording medium conveying device includes a conveying path extending from the insertion port of the housing to the discharge port via the recording position, and a call roller for calling the recording medium A inserted from the insertion port one by one onto the conveyance path. , A plurality of feed rollers that rotate while contacting both sides of the transport path with a predetermined pressure, a plurality of motors that rotate each roller, and the like. When receiving an image signal from the outside (a personal computer or the like), the controller controls each motor of the recording medium transport device, takes in the recording media inserted from the insertion slot one by one into the housing, and intermittently intermittently outputs the recording media. After passing through the recording position by manual movement, it is sent to the outlet.

Here, the reason why the dielectric is used as the material for forming the ink ejection member as described above will be described.

The electric field distribution in the vicinity of the tip of the ink ejection member of the two-dimensional model of the recording head with the grid electrode plate is represented by the distance D between the tip of the ink ejection member (ink ejection point) and the counter electrode.
The simulation was performed under the following simulation conditions while changing the _grid .

Simulation conditions Material for forming ink discharge member: (1) Conductor, (2) Dielectric Voltage applied to grid electrode plate V _grid : 2.3 kV Notch width W _grid of grid electrode plate: 150 μm Width: 50 μm Sharp angle α of ink discharge member (see FIG. 6): 60 ° Radius of curvature R at the tip of ink discharge member (see FIG. 6): 10 μm Width of ink discharge member: 250 μm Interval between adjacent partition walls: 20 μm Width of partition wall : 20 μm Bias voltage Vb: 2.5 kV Based on the simulation results, the pulse voltage threshold was calculated for each of the dielectric ink ejection member (1) and the conductor ink ejection member (2). Specifically, the pulse voltage threshold value for a recording head having no grid electrode plate was determined by experiment, and the experimental value (V
(p: 300 kV, Vb: 2.5 kV), the electric field distribution near the tip of the ink ejection member of the two-dimensional model of the recording head is simulated in advance, and the electric field distribution similar to the simulation result is described above. The pulse voltage value generated near the tip of the ink ejection member of the two-dimensional model of the recording head with the grid electrode plate is referred to as the pulse voltage threshold _Vpth for the recording head with the grid electrode plate.

From FIG. 3 showing the result of the calculation, if the distance D _grid between the tip of the ink discharge member and the counter electrode is within a practical range, the case where the dielectric ink discharge member (1) is used is used. It can be seen that the pulse voltage threshold _Vpth is lower in the case of using the ink ejection member (2) made of a conductor. This means that forming the ink ejection member from a dielectric material is effective in suppressing the pulse voltage to be applied from the pulse generator to the recording electrode. Further, if the pulse voltage applied to each recording electrode is suppressed, crosstalk between adjacent recording electrodes is less likely to occur, which is useful for improving the quality of a recorded image.

Further, in both cases where the dielectric ink discharging member (1) is used and when the conductive ink discharging member (2) is used, the distance between the tip of the ink discharging member and the grid electrode plate is increased. D _grid slide into increasing pulse voltage threshold V _pth gradually according increases but, when attention is focused on the change rate of the pulse voltage threshold V _pth for spacing D _grid of the grid electrode plate, a dielectric made of the ink ejection member ( The pulse voltage threshold value V _pth for the change in the distance D _grid between the grid electrode plate and the grid electrode plate is larger in 1) than in the conductive ink ejection member 2.
It can also be seen that the sensitivity of is low. This means that by using a dielectric material as a material for forming the ink discharge member, a dimensional error in the interval between the ink discharge member and the grid electrode plate is less likely to adversely affect the stability of the pulse voltage threshold. In other words, it means that the requirement for the processing accuracy of the recording head is eased.

The electric field distribution near the tip of the ink discharge member of the two-dimensional model of the recording head with the grid electrode plate was simulated under the following simulation conditions while changing the notch width W _grid of the grid electrode plate. .

Simulation conditions Material for forming ink discharge member: (1) Conductor, (2) Dielectric Voltage applied to grid electrode plate V _grid : 2.3 kV Distance D _grid between tip of ink discharge member and grid electrode plate: D _grid : 50 μm Ink ejection member width: 50 μm Sharp angle α of the ink ejection member: 60 ° Radius of curvature R at the tip of the ink ejection member: 10 μm Ink ejection member width: 250 μm Distance between adjacent partition walls: 20 μm Partition wall width: 20 μm Bias voltage Vb: 2.5 kV Based on the simulation result, the pulse voltage threshold was calculated for each of the dielectric ink ejection member (1) and the conductor ink ejection member (2) by the same method as described above. According to FIG. 4 showing the result of the calculation, when the ink discharge member (1) made of a dielectric material is used, the ink discharge member (2) made of a conductor can be used within the range of a practical notch width. ), The pulse voltage threshold V
_{It turns out} that _pth becomes low. This means that forming the ink ejection member from a dielectric material is effective in suppressing the pulse voltage to be applied from the pulse generator to the recording electrode.

Further, the cutout width W _grid of the grid electrode plate is increased in both cases where the dielectric ink ejection member (1) is used and when the conductor ink ejection member (2) is used. The pulse voltage threshold value V _pth gradually increases in accordance with the following _formula. However, focusing on the rate of change of the pulse voltage threshold value V _{pth with} respect to the notch width W _grid of the grid electrode plate, the dielectric ink ejection member (1) is more _suitable. It can also be seen that the sensitivity of the pulse voltage threshold V _pth to the change in the notch width W _grid of the grid electrode plate is lower than that of the conductive ink ejection member (2). This means that if a dielectric material is used as the material for forming the ink ejection member, the dimensional error in the notch width of the grid electrode plate will not adversely affect the stability of the pulse voltage threshold. In other words, it means that the requirement for the processing accuracy of the recording head is eased.

Further, the electric field distribution in the vicinity of the tip of the ink ejection member of the two-dimensional model of the recording head with the grid electrode plate is obtained by calculating the positional deviation between the center line of the notch of the grid electrode plate and the center line of the ink ejection member. The simulation was performed under the following simulation conditions while changing the amount Δax (see FIG. 5A). Based on the simulation result, the ink flying from the ink ejection member of the recording head with the grid electrode plate was applied to the recording medium. The positional deviation amount δ (landing position deviation amount) of the formed dots was calculated by the following equation (1).

Δ = D _gap × tan θ (1) where D _gap is the distance between the tip of the ink ejection member and the counter electrode, and θ is the value when no crosstalk occurs between adjacent recording electrodes. Is the angle between the ideal electric field vector (ideal ink ejection direction) and the electric field vector E (actual ink ejection direction) when crosstalk occurs between adjacent recording electrodes (see FIG. 6). ).

Simulation conditions Material for forming ink discharge member: (1) conductor, (2) dielectric Voltage applied to grid electrode plate V _grid : 2.3 kV Notch width W _grid of grid electrode plate: 50 μm, 150 μm Ink discharge Distance between member tip and grid electrode plate D _grid : 50 μm Ink ejection member width: 50 μm Tip angle (sharp angle) of ink ejection member: 60 ° Radius of curvature of tip of ink ejection member: 10 μm Ink ejection member width: 250 μm The distance between adjacent barrier ribs: 20 μm The width of barrier ribs: 20 μm Bias voltage Vb: 2.5 kV According to FIG. 5B showing the simulation results,
When a dielectric is used as the material for forming the ink ejection member
In the case of (1) and the case where a conductor is used as a material for forming the ink ejection member, the amount of positional deviation between the notch of the grid electrode plate and the ink ejection member even if the notch width of the grid electrode plate is large. It can be seen that there is almost no difference between the landing position deviation amount δ and Δax. This means that even when a dielectric material is used as the material for forming the ink ejection member, the positioning error of the ink ejection member with respect to the notch of the grid electrode plate is recorded more than when a conductor is used as the material for forming the ink ejection member. This means that there is no adverse effect on the image quality of the image.

Therefore, in the present embodiment, based on the above consideration results, by adopting a dielectric material as a material for forming the ink ejection member, it is possible to reduce the power consumption of the printer, improve the quality of recorded images, and reduce the production cost. We are trying to control it.

Next, with reference to FIG. 7, a description will be given of an appropriate numerical range as a dimension of a space provided between the tip of the ink discharge member and the protruding portion of the grid electrode plate.

The distance D _grid between the tip (ink discharge point) of the ink discharge member and the grid electrode plate and the pulse voltage threshold V
7 (a) and 7 (b) are graphs _showing the relationship between _pth and the distance D _grid between the tip of the ink ejection member (ink ejection point) and the grid electrode plate and the landing position deviation amount δ. ). Note that these graphs are created based on simulation results performed under the same simulation conditions as those described above.

As can be seen from FIG. 7A, in the two-dimensional model of the recording head without the grid electrode plate, the pulse voltage threshold V _pth is always constant (about 300 V in this case), Regarding the two-dimensional model of the recording head with an electrode plate, regardless of the magnitude of the voltage applied to the grid electrode plate, the pulse voltage threshold V increases as the distance D _grid between the tip of the ink ejection member and the grid electrode plate increases.
_pth increases gradually. If the distance D _grid between the tip of the ink ejection member of the recording head with a grid electrode plate and the grid electrode plate is set with the main focus on the low voltage driving of the printer, the set dimension is larger than that of the recording head without the grid electrode plate. It is desirable that the pulse voltage threshold falls within a range where the pulse voltage threshold becomes small. For example, in FIG. 7A, a range of a practically applied voltage to the grid electrode plate (2.2 kV to 2.4 kV).
V), the setting range of the distance D _grid between the tip of the ink discharge member of the recording head with the grid electrode plate and the grid electrode plate is about 150 μm or less, and more practically about 50 μm to 150 μm. Become.

Then, the distance D _grid between the tip of the ink ejection member of the recording head with the grid electrode plate and the grid electrode plate.
Is an appropriate numerical value within such a numerical range, FIG.
As can be seen from (b), the landing position deviation amount δ can be suppressed to about the same or less than the landing position deviation amount of the recording head without the grid electrode plate, specifically, to about 5 μm to 50 μm. . However, the value of the landing position deviation is based on the two-dimensional model of the recording head, that is, the value calculated under the condition that the crosstalk is the strongest. Is considered to be further suppressed. Even in the case of high-resolution printing at 600 dpi, the dot interval of the recorded image is about 42 μm. Therefore, even if a landing position shift of less than 50 μm occurs, it is recognized that the image quality of the recorded image is disturbed. Few things.

In the above description, one metal plate is used as the grid electrode. However, this is not always necessary. For example, instead of the grid electrode plate shown in FIG. 2, an insulating substrate (e.g., alumina, zirconia, etc.) having a similar shape is provided as a grid plate, and a metal film serving as a grid electrode is formed on the insulating substrate. You may do so. Hereinafter, a specific description will be given.

As shown in FIG. 8, the thickness of the plate provided in place of the grid electrode plate 105 of FIG.
On the grid plate 800 of m, metal films 801 are formed as grid electrodes on both edges of the surface folded up on the ink ejection member 200, respectively. A bias voltage Vb is supplied to these grid electrodes 801 from the same bias power supply 108 as the recording electrodes 111. These grid electrodes 801 are connected to the ink ejection member 2.
It is connected to the same grid electrode pulse generator 802 as the grid electrode sandwiching 00. Each of the grid electrode pulse generators 802 has the same recording voltage as that applied to a pulse generator that generates a pulse voltage for causing ink to fly from the ink ejection member 200 between the two grid electrodes connected thereto. Is supplied from the drive circuit 107.

With such a configuration, as shown in FIG. 9A, the same bias voltage is supplied to the recording electrode 111 and the grid electrode 801 associated with one ink ejection member 200. At the timing, pulse voltages of opposite polarities are superimposed. That is, the same ink discharge member as long as a positive pulse voltage V _p1 for discharging ink is superimposed on the bias voltage applied to the recording electrode 111 associated with one ink discharge member 200. A negative pulse voltage −V _p2 (usually V _p1 = V _p2 ) is superimposed on the bias voltage applied to the grid electrode 801 associated with 200. According to such a pulse voltage application method, the predetermined potential difference (V _p1 + V _p2) is applied between the recording electrode 111 and the grid electrode 801 associated with the ink ejection member during ink ejection.
= Vp / 2), but there is no potential difference between the recording electrode 111 and the grid electrode 801 associated with the ink ejection member that does not eject ink. As a result, no electric field is formed in the vicinity of the tip of the ink ejection member that should not cause the ink to fly, so that unnecessary ink flying hardly occurs.

In order to shorten the response period T of the ink ejection member and obtain good gradation characteristics, as shown in FIG.
The pulse voltage application timing to the grid electrode 801 is delayed by a predetermined delay time td, or conversely, the pulse voltage application timing to the grid electrode 801 is delayed by a predetermined delay from the pulse voltage application timing to the recording electrode 111. It is desirable to delay by the time td. For example, if a pulse voltage is applied to the grid electrode 801 earlier, the colorant particles are sufficiently aggregated at the tip of the ink ejection member before the pulse voltage is applied to the recording electrode 111. . In this case, the magnitude of the pulse voltage applied to the grid electrode 801 may be determined in consideration of ink characteristics and the like. In the case where a pulse voltage is applied to the recording electrode earlier, similarly,
The size may be determined in consideration of the characteristics of the ink and the like.

The above description has been made with reference to an ink jet printer for monochrome printing as an example. However, when the present invention is applied to an ink jet printer for color printing,
(Y: yellow, M: magenta, C: cyan, K: black) A print head similar to the above may be mounted on the printer.

[0049]

According to the present invention, the manufacturing efficiency of an ink jet recording apparatus can be improved. Further, it is possible to realize a low-voltage driven inkjet recording apparatus in which the dimensional accuracy of the recording head does not adversely affect the stability of the pulse voltage threshold. With such an effect, a reduction in the production cost of the inkjet recording apparatus is realized.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an internal structure of an inkjet recording apparatus according to an embodiment of the present invention.

2A is a sectional view of a recording head according to an embodiment of the present invention, and FIG. 2B is a perspective view of a part C thereof.

FIG. 3 is a diagram showing the relationship between the distance between the tip of the ink ejection member and the grid electrode and the pulse voltage threshold for each material for forming the ink ejection member.

FIG. 4 is a diagram showing a relationship between a notch width of a grid electrode and a pulse voltage threshold for each forming material of an ink ejection member.

5A is a diagram illustrating a positional relationship between an ink discharge member and a notch of a grid electrode, and FIG. 5B is a diagram illustrating a landing position shift amount, an ink discharge amount, and a discharge amount for each forming material of the ink discharge member. FIG. 4 is a diagram illustrating a relationship between a displacement amount of a member and a grid electrode.

FIG. 6 is a diagram showing a two-dimensional model of the recording head according to one embodiment of the present invention.

FIG. 7A is a diagram illustrating a relationship between a pulse voltage threshold and a distance between the tip of an ink ejection member and a grid electrode for each voltage value applied to the grid electrode, and FIG. FIG. 4 is a diagram illustrating a relationship between a landing position deviation amount and a position deviation amount between an ink ejection member and a grid electrode for each voltage value applied to an electrode.

FIG. 8 is a schematic partial configuration diagram of a recording head according to an embodiment of the present invention.

FIG. 9 is a timing chart of a pulse voltage generated from a recording electrode pulse generator and a pulse voltage generated from a grid electrode pulse generator.

FIG. 10 is a diagram showing a schematic structure of a recording head of a conventional ink jet recording apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 100 ... Counter electrode 101 ... Recording head 102 ... Ink tank 103a, 103b ... Pump 104a, 104b ... Pipe 105 ... Grid electrode 105a ... Notch 106 ... Pulse generator group 107 ... Drive circuit 108 ... Bias power supply 109 ... Grid power supply 110 ... Ink Introducing path 111 ... Recording electrode 200 ... Ink ejection member 201 ... Partition wall 202 ... Insulating substrate 203 ... Insulating film 204 ... Dielectric thin film

Continued on the front page (72) Inventor Seiji Yonekura 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture F-term in Hitachi Research Laboratory, Hitachi, Ltd. F term (reference) 2C057 AF93 AP51 AP77 BD05 BD12

Claims (5)

[Claims] A recording head having a plurality of ink ejection members on a grid electrode plate; and a counter electrode disposed on a tip side of the plurality of ink ejection members. A fold that raises the end of the plate toward the plurality of ink ejection members, and a plurality of notches for allowing the ink ejected from each of the ink ejection members to pass to the counter electrode side are formed. An ink jet recording apparatus, comprising: 2. An ink jet recording apparatus comprising: an ink ejection member array; and a counter electrode disposed on a tip side of each ink ejection member of the ink ejection member array, wherein the ink ejection member array and the counter electrode are provided. And a grid plate interposed between the ink discharge member row and the ink discharged from the ink discharge member to the counter electrode side in association with each ink discharge member of the ink discharge member row. And a notch for letting through and a grid electrode are formed. 3. An ink jet recording apparatus according to claim 2, wherein said first pulse generation means is provided for each of said ink ejection members, and said first pulse generation means is provided for each grid electrode unit associated with each of said ink ejection members. A second pulse generation means, wherein each of the second pulse generation means, together with the generation of a pulse voltage from the first pulse generation means corresponding to the second pulse generation means, a pulse of the opposite polarity to the pulse voltage An ink jet recording apparatus for generating voltages. 4. The ink jet recording apparatus according to claim 3, wherein a pulse voltage generation timing of each of said second pulse generation means and a pulse voltage of said first pulse generation means associated with said second pulse generation means. An ink jet recording apparatus, wherein the occurrence timing is shifted by a predetermined delay time. 5. The ink jet recording apparatus according to claim 1, wherein each of the ink ejection members is a dielectric. .