JPH1016254A - Ink-jet recorder and printing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink-jet recorder finely changing a dot diameter of ink to be emitted to obtain an image having gradation. SOLUTION: A passage guiding ink from an ink tank, the ink chamber connected to the passage, the electrostriction element connected to the ink chamber so as to be capable of reducing the vol. of the ink chamber, a first pulse generator 10a applying voltage to the electrostriction element, the emitting passage connected to the ink chamber to guide ink to an orifice, a second pulse generator 10b applying voltage across the emitting passage and a recording medium and a control means controlling voltages applied by two kinds of the pulse generators are provided. By this constitution, since an ink amt. can be changed at every dots by independently applying voltage at every emitting passages, a highly detailed image can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus and a printing method for forming an image on a recording medium by discharging ink droplets.

[0002]

2. Description of the Related Art Along with a printing apparatus (electrophotographic recording apparatus) for obtaining an image by an electrophotographic method, an ink jet recording apparatus for obtaining an image by discharging minute ink droplets onto a recording medium is widely used. Compared to electrophotographic recording devices, ink jet recording devices have the advantage that they do not require a photoreceptor or do not have a transfer or fixing process, so they have fewer parts and can form images with an inexpensive device configuration. ing.

A recording method using an ink jet recording apparatus is as follows.
The ink is guided from the ink tank in the ink jet recording head to the ink chamber corresponding to each dot, and kinetic energy is given to the ink in the ink chamber, and the ink droplet is discharged from a discharge port (orifice) onto a recording medium such as paper or an OHP sheet. An image is obtained by discharging. There are the following two methods for giving kinetic energy to the ink for ejection. The first method is to provide a heating element near the orifice,
This is a method (bubble jet method) in which a pulse current is applied thereto and ink is ejected from an orifice by the pressure of bubbles generated when the ink boils instantaneously. In the second method, a part of a wall constituting the ink chamber is adhered to the electrostrictive element, and the electrostrictive element is deformed by applying a pulse voltage to the electrostrictive element, thereby instantaneously reducing the volume of the ink chamber. In this method, ink is ejected from the orifice.

Japanese Patent Application Laid-Open No. 7-502218 discloses an apparatus for ejecting aggregates of charged particulate matter such as ink from a recording head by electrostatic means. That is, the liquid containing the particulate matter is supplied to the ejecting position of the recording head, a potential is applied to the ejecting position, an electric field is formed at that position, an aggregate is formed at the ejecting position, and the aggregate is ejected by electrostatic means. It is ejected away from the position.

[0005]

In an electrophotographic recording apparatus, the gradation can be given by changing the diameter of each dot by controlling the amount of exposure to irradiate the photoreceptor. It is possible to obtain a perfect image. On the other hand, in the conventional ink jet recording apparatus,
This is one of the reasons that the image quality is lower than that of the electrophotographic recording apparatus because the amount of ink ejected at one time is almost constant and dot gradation cannot be provided. The reason why the amount of ink discharged at one time is constant is as follows.

First, in the case of the bubble jet method, 10
Bubbles are generated in the ink chamber for each dot by heating the heating element for about μs, and the ink drops are ejected toward the recording medium by a rise in the pressure in the ink chamber at that time. Accordingly, ink droplets having a particle diameter substantially equal to the orifice diameter of the ink jet recording head are ejected. It is structurally difficult to eject ink droplets having a diameter equal to or less than the orifice diameter.

In the case of the piezo method, by applying a pulse voltage of about 100 μs to the electrostrictive element, the electrostrictive element is deformed and the ink is ejected by a force that instantaneously reduces the volume of the ink chamber. If the volume change amount of the ink chamber is reduced to reduce the amount of ink to be ejected,
There are problems that the ink does not reach the recording medium at a distance of about 1 mm from the orifice and that the ejection amount is unstable because the viscosity of the ink has a large temperature difference dependence. Therefore, the volume of the ink chamber is instantaneously reduced, and ink droplets having the same size as the orifice diameter are ejected.

That is, in a conventional ink jet recording apparatus which cannot eject ink droplets having an arbitrary particle diameter smaller than the orifice diameter, the limit of expressible image quality is low.

In the apparatus described in Japanese Patent Application Laid-Open No. 7-502218, since the size of the print dot radius is controlled by changing the magnitude of the potential applied to the ejection position, the response speed of the ejection is low. In addition, it is considered that it is difficult to finely change the size of the print dot radius.

An object of the present invention is to provide an ink jet recording apparatus and a printing method capable of ejecting ink droplets having an arbitrary diameter equal to or less than the orifice diameter.

Another object of the present invention is to provide an ink jet recording apparatus capable of expressing a gradation for each dot and obtaining a high-definition image.

Another object of the present invention is to provide an ink jet recording apparatus capable of ejecting ink droplets having an arbitrary particle diameter at a high speed in an apparatus of a method of ejecting ink by electrostatic force. .

[0013]

SUMMARY OF THE INVENTION A feature of the present invention is to provide a recording head having an ink supply path communicating from an ink tank to an orifice, a recording medium holding member for holding a recording medium, and an ink based on image data. In an ink jet recording apparatus that prints an image on the recording medium by discharging the orifice from the orifice, a pressurizing supply unit that pressurizes ink in the ink supply path by a member controlled by an electric unit and supplies the ink to the orifice. An electrostatic unit that discharges the ink from the orifice toward the recording medium by electrostatic force, and an electric signal applied to the pressurizing supply unit and the electrostatic unit based on the image data in a synchronized manner. And a control unit for adjusting the print dot diameter.

Another feature of the present invention is that in the ink jet recording apparatus, the recording head has a plurality of the orifices arranged in an array, and the ink supply paths are arranged in parallel corresponding to the respective orifices. A plurality of individual ink chambers, wherein each of the individual ink chambers is provided with the pressurizing supply means, and the electrostatic means is provided corresponding to each of the orifices.

Another feature of the present invention is that, in the ink jet recording apparatus, the pressurizing and supplying means constitutes a part of an ink chamber of the ink supply path, and the volume of the ink chamber in response to application of a voltage. Including an electrostrictive element for reducing and a first pulse generator for applying a pulse voltage to the electrostrictive element,
The electrostatic means includes a conductive discharge passage provided with the orifice at one end, and a second pulse generator for applying a potential difference between the discharge passage and the recording medium holding member.

According to another feature of the present invention, in the ink jet recording apparatus, the pressurizing and supplying means is provided in the ink chamber of the ink supply path and heats the ink in the ink chamber in response to the electric signal. And a first pulse generator for applying a pulse voltage to the heater, wherein the electrostatic means includes a conductive discharge passage having one end provided with the orifice, and a conductive discharge passage formed between the discharge passage and the recording medium holding member. A second pulse generator for providing a potential difference therebetween is included.

Another feature of the present invention is that an ink jet recording apparatus having a recording head having an ink supply path communicating from an ink tank to an orifice, and a recording medium holding member for holding a recording medium, is provided based on image data. In a printing method for printing an image on the recording medium by ejecting ink from the orifice, the ink in the ink supply path is pressurized by a pressurizing supply unit having a member controlled by an electric unit. The ink is ejected from the orifice toward the recording medium by the electrostatic force generated by the electrostatic means, and is applied to the pressurizing supply means and the electrostatic means based on the image data. An object of the present invention is to control the electric signals in synchronization with each other to adjust the dot diameter of an image to be printed.

According to the present invention, a pressurizing supply unit and an electrostatic unit for controlling the supply of ink are provided, and based on image data, an electric signal to be applied to these two independent units is controlled in synchronization with each other to discharge ink. The dot diameter of the ink to be adjusted is adjusted.
That is, by controlling the pressurizing supply unit and the electrostatic unit in synchronization based on the image data, the dot diameter of the ink ejected from the orifice can be adjusted over a wide range. This makes it possible to eject ink droplets having an arbitrary diameter equal to or less than the orifice diameter onto the recording medium, thereby obtaining a high-gradation print image.

Further, a pressure supply unit and an electrostatic unit for controlling the supply of ink are provided independently for each of the plurality of orifices arranged in parallel, and charged ink droplets are ejected onto a recording medium by electrostatic force. Since an image is formed by the method, the amount of ink ejected for each dot can be changed by changing the applied voltage condition for each orifice. Therefore, since the gradation can be expressed for each dot, there is an effect that a higher definition image can be obtained than in the conventional inkjet recording apparatus.

In an ink jet recording apparatus of a type in which ink is ejected by an electrostatic force, the force acting on the ink before the ink is ejected from the orifice and the force at the time of the ink ejection are determined by the electrostatic force and the pressure applied by the electrostatic means. By adjusting the two forces of the pressure by the supply means, the pressure can be freely adjusted to an arbitrary value over a wide range, so that the ink droplet can be ejected at a high speed.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the method and principle of ejecting ink droplets having an arbitrary particle diameter on a recording medium according to the present invention will be described with reference to FIGS.

FIG. 1 is a sectional view of an ink jet recording apparatus used by the inventor for experiments. In FIG. 1, reference numeral 2 denotes an electrostrictive element, and reference numerals 1 and 3 denote electrodes of the electrostrictive element 2, and reference numeral 4 denotes a partition constituting a part of the ink chamber 6. Reference numeral 5 denotes a discharge passage connected to the ink chamber, and guides the ink to the orifice at the end thereof. 9 is an ink tank, 11 is a recording medium, and 12 is a recording medium holding member. The electrostrictive element 2 has a function as a pressurizing / supplying unit that pressurizes the ink in the ink chamber 6 and sends it to the discharge passage 5 by applying a pulse voltage VA to the electrodes 1 and 3. Further, a pulse voltage VB is applied between the ejection path 5 made of a conductive material and the recording medium holding member 12. The recording medium 11 is an insulating material having a higher electric resistance than the discharge passage and the recording medium holding member, for example, a recording paper. The conductive discharge passage 5 has a pulse voltage V
It has a function as electrostatic means for adjusting the amount of ink ejected from the orifice when B is applied.

In the apparatus shown in FIG. 1, after the ink flows from the ink tank 9 into the ink chamber 6 through the ink conduit 8, the ink tank 9 is held at an appropriate height H and the electrode 1
By applying a pulse voltage VA between the electrode 3 and the electrode 3, the electrostrictive element 2 constituting a part of the ink chamber is deformed to reduce the volume of the ink chamber, and as shown in FIG. (A) where the ink is slightly discharged from the orifice. The diameter of the orifice in this case is 100μ
m. After that, the discharge passage 5 and the recording medium holding member 12
When the pulse voltage VB is applied between the discharge passage 5 and the recording medium holding member 12, the ink in the discharge passage 5 is charged, and the ink is held on the recording medium holding member 12 by an electrostatic force generated by the electric field formed between the discharge passage 5 and the recording medium holding member 12. The ink is ejected onto the recording paper 11 thus cut. Note that the ink needs to be an electrically high-resistance substance. Further, the electrostatic force between the discharge passage 5 and the recording medium holding member 12 has a magnitude depending on the application time and the voltage value of the pulse voltage VB.

As described above, in the present invention, the principle of causing ink to be ejected from the ejection passage is based on an electrostatic force, that is, an electric field in which charged ink acts between the ejection passage and the recording medium holding member. It draws on the side and uses the power that is accelerated. FIG. 4 (a)
As shown in (2), when the ink slightly exits from the orifice at the end of the discharge passage 5, an electric field concentrates on the ink portion, charges are injected, and the ink is charged. In the case of the apparatus used in the experiment, the distance between the orifice at the end of the discharge passage 5 and the recording paper 11 was 1 mm.

FIG. 2 shows an example of the operation of the electrostatic means. A pulse voltage VB of 3 ms applied between the discharge passage 5 and the recording medium holding member 12 (the discharge passage side 5 has a high potential) is applied.
Shows the diameter of the ink that has adhered to the surface of the recording paper when. As the applied voltage increases, the ink ejection amount increases, and the diameter (dot diameter) of the ink adhering to the apparatus recording paper 11 increases.

FIG. 3 also shows an example of the operation of the electrostatic means.
It shows the diameter (dot diameter) of the ink attached to the surface of the recording paper 11 when a pulse voltage VB of 5 kV is applied and the length of the pulse is changed. As the pulse voltage application time increases, the ink ejection amount increases, and the diameter of the ink attached to the recording paper 11 increases.

As described above, the larger the voltage applied between the discharge passage 5 and the recording medium holding member 12 and the longer the voltage application time, the larger the amount of ink to be discharged by the electrostatic means. However, in order for ink to be ejected from the orifice, there are threshold values for all of the ink pressure, applied voltage, and applied time. The threshold is determined by electrostatic means
Determined as a function of the voltage of the pulse voltage VB applied to the orifice and the application time, a function of the gap between the orifice and the recording medium, and a function of the ink pressure controlled by the pulse voltage VA applied to the electrostrictive element 2 of the pressure supply means. Is what is done.

In a conventional 360 dpi ink jet recording apparatus, when ink is ejected from an orifice having a diameter of about 50 μm, the ink diameter on the recording paper becomes about 100 to 20.
It is about 0 μm. Therefore, in FIGS. 2 and 3, the ink pressure, the orifice, and the recording pressure are adjusted by adjusting the pulse voltage VA applied to the electrostrictive element 2 constituting a part of the ink chamber, in a range where the ink diameter on the recording paper is 200 μm or less. By controlling the condition of the pulse voltage VB applied to the medium holding member, changing the amount of ink ejected from the orifice, and changing the diameter of the ink droplet on the recording paper, a resolution of 360 dpi can be obtained. An ink jet recording apparatus that obtains a higher definition image than the ink jet recording apparatus can be provided.

Hereinafter, an embodiment for realizing an ink jet recording head based on the principle of the present invention will be described with reference to FIGS.

FIG. 5 is a longitudinal sectional view of a recording head according to an embodiment of the present invention, FIG. 6 is a sectional view taken along the line aa 'of FIG. 5, and FIG.
FIG. 2 is an external perspective view of a recording head. FIG. 8 shows a configuration of a control unit of the recording head.

In this embodiment, the recording head has a plurality of discharge passages 5 (5a-5n) arranged in an array.
The ink stored in one ink tank 9 is guided to a common ink chamber 7 by an ink conduit 8, and further, a plurality of individual ink chambers 6 (6 a-6) corresponding to the respective discharge passages 5.
n) are arranged in parallel. Each of the individual ink chambers 6 has an electrostrictive element 2 (201a, 201b,... 201).
m, 201n) are provided.
a, 201b,... 201m and 201n are respectively
It is connected to the first pulse generator 10a. Discharge passage 5
Is made of a conductive material, and each discharge passage 5 (5a-5n)
Is connected to the second pulse generator 10b. The recording medium holding member 12 is grounded or a bias voltage is applied.

In the ink jet recording apparatus of the present invention, the number of discharge ports of the recording head is increased to form an array because the voltage required for discharging is higher in the electrostatic ink jet recording apparatus than in the bubble ink jet recording apparatus. This is because the application time is slightly longer, so that the number of ejection ports is increased to increase the recording speed.

FIG. 7 is a perspective view of the ink jet recording head of FIG. 5 as viewed obliquely from the right side. Second pulse generator 1
Ob allows the pulse voltage VB to be applied independently for each of the discharge passages 5a-5n.

FIG. 8 shows the configuration of the control unit of the recording head. The voltage control unit 110 controls the gradation level data 112
Based on the voltage VA supplied from the power supplies 114 and 116 to the first pulse generator 10a and the second pulse generator 10b,
Control VB. The first pulse generator 10a and the second pulse generator 10b are controlled based on the output of the synchronization clock 118 so that the application timings of the voltages VA and VB are synchronized.

Next, the operation of the above embodiment will be described. In order to bring the recording head into a printing state, a voltage VA is applied to the electrostrictive element 2 by the first pulse generator 10a of the pressurizing and supplying means, and the volume of the individual ink chamber 6 is reduced by deforming the electrostrictive element. And pressurizes the ink to slightly protrude the ink from the orifice at the end of the discharge passage 5. That is, the state shown in FIG. on the other hand,
In synchronization with this, a voltage V corresponding to the amount of ink ejected from the orifice based on the gradation level data 112 is applied to the ejection path 5 by the second pulse generator 10b of the electrostatic means.
B is applied to eject ink on the recording medium 11.

FIG. 4 is an explanatory view of a state in which ink is discharged from the orifice at the end of the discharge passage 5. FIG. 4 (a)
Is a state in which the ink does not reach the threshold value for discharging from the orifice against the surface tension.When a pulse voltage is applied, first, an electric field is concentrated on this ink portion, charges are injected, and the ink is charged. I do. (B)-(d) of FIG.
Means that the electrostatic force acting on the charged ink exceeds the threshold value due to the electric field acting between the discharge passage and the recording medium holding member as the pulse voltage VB increases, and the ink is drawn to the recording medium holding member side. This shows a state of discharging from the orifice. In (b)-(d), the voltage VB applied to the discharge passage 5 is small, and therefore, the dot diameter of the ink attached to the surface of the recording paper 11 is small. On the other hand, (e)-(g) of FIG.
Indicates that when the voltage VB applied to the discharge passage 5 is large, the dot diameter also becomes large.

As described above, means for applying a voltage independently to each ejection path 5 is provided, and an image is formed by a method in which charged ink droplets are ejected onto a recording medium by electrostatic force. By changing the applied voltage condition for each dot, the amount of ink ejected for each dot can be changed. Therefore, since the gradation can be expressed for each dot, a high-definition image can be obtained.

Next, a specific example of a method for applying a voltage to the electrostatic means will be described with reference to FIG. In order to change the amount of ink to be ejected for each dot, it is necessary to change the condition of the voltage VB applied to the ejection passage 5, but the following three methods are conceivable for applying the voltage.

The first method is a method in which the applied voltage is changed while the application time of the voltage VB to the discharge passage 5 is kept constant by electrostatic means. Hereinafter, a method of applying a voltage between the discharge passage 5 and the recording medium holding member 12 will be described.

First, in an image printing state, a bias voltage is applied so that the potential of the recording medium holding member 12 becomes -V0. The form of application of the bias voltage includes a form in which a voltage is applied to the entire recording medium holding member 12 as shown in FIG. 5 and a form in which a voltage is applied to a part of the recording medium holding member 12 as shown in FIG. Either may be used. 10, the recording medium 11 is conveyed by the guide roll 14 along the recording medium holding member 12. There is an electrode 16 behind the position where the ink adheres to the recording medium 11,
An output from the bias power supply 15 is applied to the electrode. The magnitude of the bias voltage −V0 is a voltage immediately before the ejection of ink from the orifice starts when a voltage is applied to the ejection passage 5. When discharging from the orifice, a positive voltage having a magnitude corresponding to the amount of ink is applied to the discharge passage 5. The reason for reversing the polarity of the voltage applied to the recording medium holding member 12 and the discharge passage 5 is to reduce the voltage difference due to the presence or absence of printing between adjacent dots, thereby preventing discharge.

FIG. 10 shows a method of expressing four types of gradations using the above method. The gradation level 0 indicates the non-printing state, the gradation level 3 indicates the maximum dot diameter, and the printing is performed on the recording medium. The kinetic energy of the ink ejected in this case is obtained from both the pressure accompanying the reduction in the volume of the ink chamber by the pressurizing and supplying means and the electrostatic force corresponding to the voltage VB by the electrostatic means. In FIG. 10, the voltage VA applied to the electrostrictive element is a triangular wave, but is not specified in the present invention. In the above description, the ejection path 5 of the inkjet head has a higher potential than the recording medium holding member 12, but depending on the properties of the ink, a voltage of the opposite polarity is applied.

The second method is a method (t1-t3) in which the voltage VB applied to the discharge passage 5 is kept constant and the application time t is changed by electrostatic means. Even in this case, in the image printing state, the potential of the recording medium holding member 12 becomes −V
A bias voltage is applied so as to be zero. Here, V0
Is set in the same manner as in the first method.

FIG. 11 shows a method of expressing four types of gradations by using the above method. Even in the case of FIG. 11, the waveform of the voltage VA applied to the electrostrictive element is not particularly specified.

The third method is a method of changing the application time t of the voltage VA to the electrostrictive element while the voltage VB is applied to the discharge passage 5 by the electrostatic means. The principle of this method is to change the time during which ink can be ejected from the orifice at the end of the ejection passage 5 by changing the application time of the voltage VA applied to the electrostrictive element, thereby controlling the ejection amount. It is. This method will be described with reference to FIG.

In FIG. 12, when the gradation level is 0, the voltage VA is not applied to the electrostrictive element, so that the volume of the ink chamber does not change and no ink is ejected. As the gradation level increases, the time during which ink can be ejected increases, and printing is performed on a recording medium with a larger dot diameter.

Next, an example of a method of changing the voltage application time according to the gradation level used in the second method and the third method will be described with reference to FIGS.

FIG. 13 shows a method of expressing four gradation levels. FIG. 13A shows a pixel clock. The pixel clock indicates HI during half the one-pixel printing time and LOW during the other half. FIG. 13B shows a triangular wave generated in synchronization with the pixel clock. Using a comparator that compares this triangular wave with the magnitude of the voltage signal defined by the gradation level, when the voltage of the triangular wave is smaller than the voltage defined by the gradation level, the output of the comparator is Set to be HI. This output waveform is shown in FIG.
It is shown in (c). A method of controlling the voltage applied to the load (the discharge passage 5 or the electrostrictive element) by the signal of FIG. 13C will be described with reference to FIG.

FIG. 14 shows a configuration example of the electrostatic means of the recording head. An output of a voltage generator 122 for generating a voltage based on the gray level data 112;
The output of the comparator 24 controls the voltage VB applied from the power supply 116 to the discharge passage 5 based on the output of the comparator. For example, when printing is performed at the gradation level 2, the comparator 120 outputs the signal shown in FIG.
Is compared with V2 which is the voltage corresponding to the gradation level 2 and the output of the comparator is set to HI when the triangular wave voltage is lower than V2, and this signal is received. The output control unit 126 controls the output from the power supply 116 to be connected to the load 5. A control signal output from the comparator 120 in synchronization with the pixel clock is supplied to each discharge passage (5a-5n) through a shift register (not shown).
Each of the orifices controls the ejection of the ink.

FIG. 15 shows a longitudinal section of a recording head according to another embodiment of the present invention. In this embodiment, the discharge passage 5 (5a-5n), the individual ink chamber 6 (6a
-6n) and the structure of the electrostatic means are the same as in the embodiment of FIG. In this embodiment, the individual ink chambers 6 are provided with heaters 31 (31a, 31b,..., 31m, 31n), respectively, and each heater 31 is connected to the first pulse generator 10a. In this embodiment, in order to bring the recording head into a printing state, a voltage VA is applied to each heater 31 by the first pulse generator 10a of the pressurizing / supplying means to supply a pulse current, and the ink is heated so that the ink is instantaneously discharged. 4A, the ink in the individual ink chamber 6 is pressurized by bubbles generated when the liquid boiled, and the ink slightly protrudes from the orifice at the end of the discharge passage 5.
State. On the other hand, in synchronization with this, in the discharge passage 5,
The voltage VB corresponding to the amount of ink to be ejected from the orifice is applied by the second pulse generator 10b of the electrostatic means based on the gradation level data 112, and the ink is ejected onto the recording medium 11.

[0050]

According to the present invention, a pressurizing supply means and an electrostatic means for controlling ink supply are provided, and an electric signal applied to these two independent means is controlled synchronously based on image data. The dot diameter of the ejected ink is adjusted. That is, by controlling the pressurizing supply unit and the electrostatic unit in synchronization based on the image data, the dot diameter of the ink ejected from the orifice can be adjusted over a wide range. This makes it possible to eject ink droplets having an arbitrary diameter equal to or less than the orifice diameter onto the recording medium, thereby obtaining a high-gradation print image.

Further, a pressure supply means and an electrostatic means for controlling the supply of ink are provided independently for each of a plurality of orifices arranged in parallel, and charged ink droplets are ejected onto a recording medium by electrostatic force. Since an image is formed by the method, the amount of ink ejected for each dot can be changed by changing the applied voltage condition for each orifice. Therefore, since the gradation can be expressed for each dot, there is an effect that a higher definition image can be obtained than in the conventional inkjet recording apparatus.

In an ink jet recording apparatus of the type in which ink is ejected by electrostatic force, the force acting on the ink before the ink is ejected from the orifice and the force at the time of ink ejection are determined by the electrostatic force and the pressure applied by the electrostatic means. By adjusting the two forces of the pressure by the supply means, the pressure can be freely adjusted to an arbitrary value over a wide range, so that the ink droplet can be ejected at a high speed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an ink jet recording apparatus illustrating the principle of the present invention.

FIG. 2 is a diagram illustrating a relationship between a magnitude of a voltage applied to an ink ejection unit and a diameter of an ink droplet to be ejected.

FIG. 3 is a diagram illustrating a relationship between a time of a voltage applied to an ink ejection unit and a diameter of an ink droplet to be ejected.

FIG. 4 is a diagram illustrating a state of ink near an orifice in a state where ink is ejected.

FIG. 5 is a cross-sectional side view of an inkjet recording apparatus according to one embodiment of the present invention.

FIG. 6 is a sectional view taken along the line aa ′ of FIG. 5;

FIG. 7 is a perspective view of the ink jet recording apparatus of FIG.

FIG. 8 is a diagram illustrating a configuration of a control unit of the recording head in FIG. 5;

FIG. 9 shows a first example of applying a voltage to the recording head according to the present invention.
It is a figure showing the method of.

FIG. 10 is a diagram showing another configuration example of the recording head according to the present invention.

FIG. 11 is a diagram showing a second method for applying a voltage to the recording head according to the present invention.

FIG. 12 is a diagram showing a third method for applying a voltage to the recording head according to the present invention.

FIG. 13 is a diagram showing a method of changing a voltage application time as a method of applying a voltage to a recording head according to the present invention.

FIG. 14 is a diagram showing an example of a pulse generator for realizing the method of FIG.

FIG. 15 is a view showing a longitudinal section of a recording head according to another embodiment of the present invention.

[Explanation of symbols]

1, 3, electrode, 2 electrostrictive element, 4 partition, 5 discharge passage, 6 individual ink chamber, 7 common ink chamber, 8 ink conduit, 9 ink tank, 10a first pulse generator ,
10b second pulse generator 10, 11 recording medium, 12
... Recording medium holding member

Claims (10)

[Claims] A recording head having an ink supply path communicating from an ink tank to an orifice; and a recording medium holding member for holding a recording medium, wherein the recording medium is discharged by discharging ink from the orifice based on image data. An ink jet recording apparatus that prints an image on an orifice; a pressurizing / supplying unit that pressurizes ink in the ink supply path by a member controlled by an electric unit and supplies the ink to the orifice; An electrostatic unit that discharges the recording medium, and a control unit that controls an electric signal applied to the pressurizing supply unit and the electrostatic unit in synchronization with each other based on the image data, and adjusts a print dot diameter. An ink jet recording apparatus comprising: 2. An ink jet recording apparatus according to claim 1, wherein said recording head has a plurality of said orifices arranged in an array, and said ink supply paths are arranged in parallel corresponding to said respective orifices. Ink jet recording comprising a plurality of individual ink chambers, each of the individual ink chambers being provided with the pressure supply means, and the electrostatic means being provided corresponding to each of the orifices. apparatus. 3. An ink jet recording apparatus according to claim 1, wherein said pressurizing and supplying means constitutes a part of an ink chamber of said ink supply path, and the volume of said ink chamber in response to application of a voltage. And a first pulse generator for applying a pulse voltage to the electrostrictive element, wherein the electrostatic means comprises: a conductive discharge passage having one end provided with the orifice; and the discharge passage. And a second pulse generator for providing a potential difference between the recording medium holding member and the recording medium holding member. 4. The ink jet recording apparatus according to claim 1, wherein said pressurizing and supplying means is provided in an ink chamber of said ink supply path and heats the ink in said ink chamber in response to said electric signal. And a first pulse generator for applying a pulse voltage to the heater, wherein the electrostatic means includes a conductive discharge passage having one end provided with the orifice, and a conductive discharge passage formed between the discharge passage and the recording medium holding member. An ink jet recording apparatus comprising a second pulse generator for giving a potential difference between the two. 5. The ink-jet recording apparatus according to claim 3, wherein said second pulse generator comprises two power supplies, a power supply connected to said discharge passage and a power supply connected to said recording medium holding member. An ink jet recording apparatus, wherein the two power supplies have different polarities. 6. An ink jet recording apparatus according to claim 3, wherein the magnitude of the voltage applied to said electrostatic means is changed based on gradation data of a print image. 7. An ink jet recording apparatus according to claim 3, wherein the application time of the voltage applied to said electrostatic means is changed based on gradation data of a print image. 8. An ink jet recording apparatus according to claim 3, wherein the application time of the voltage applied to said pressure supply means is changed based on gradation data of a print image. . 9. An ink jet recording apparatus according to claim 3, wherein said pulse generator of said electrostatic means applies a voltage to said recording medium holding member only during printing. 10. An ink jet recording apparatus comprising a recording head having an ink supply path communicating from an ink tank to an orifice, and a recording medium holding member for holding a recording medium, ejecting ink from said orifice based on image data. In the printing method of printing an image on the recording medium, the ink in the ink supply path is pressurized and supplied to the orifice by pressurizing supply means having a member controlled by an electric means, By means of the electrostatic force generated by the means, the ink is ejected from the orifice toward the recording medium, and based on the image data, an electric signal applied to the pressurizing supply means and the electrostatic means is synchronized. Controlling and adjusting the dot diameter of an image to be printed by an ink jet recording apparatus. Method.