JPH06286138A - Ink jet recorder and ink jet recording method - Google Patents

Abstract

PURPOSE:To carry out multiple gradation recording stably in high image quality. CONSTITUTION:Two discharge openings 11A, 11B are provided to one ink passage 12 in a recording head. A discharging heater 13 is driven according to a size of a dot to be formed on recording paper. Then, when a small dot is formed, small ink drops 25A, 25B are individually discharged from the discharge openings 11A, 11B, and each dot is formed. Besides when a large dot is formed, ink drops 26A, 26B are discharged so that they may coalesce into a large ink drop 27, and the large dot is formed.

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 an ink jet recording method, and more particularly to an ink jet recording apparatus and an ink jet recording method capable of controlling an ink ejection amount.

[0002]

2. Description of the Related Art In recent years, OA devices such as personal computers and word processors have become widespread, and along with this, demands for printing out image information processed by these devices are also increasing. Various printing methods such as a wire dot method, a thermal transfer method, and an ink jet method are known as the print output method. In these recording methods, recording based on image data is performed on a recording sheet conveyed by a recording head of each method.

The requirements for these types of recording devices are mainly that the recording is performed at high speed, the resolution is high, the image quality is high, and the noise is low. In particular, with the recent increase in the speed of MPUs and the higher integration of semiconductor memories, the handling of image images has increased, and therefore the supply of high-quality intermediate-tone images is increasing.

As a method of expressing a halftone in an ink jet recording apparatus, a method of expressing the number of ink droplets ejected per predetermined pixel on a recording medium (binary pseudo-halftone expression), There is a method in which recording heads having different ejection amounts or a plurality of recording heads for ejecting ink having different densities are arranged, and the recording heads are selected and driven according to the halftone to express the halftone.

In the halftone expression method as described above, bubbles are often generated in the ink mainly by using thermal energy, and the ink is often ejected based on the generation of the bubbles. This is because this discharge method cannot control the discharge amount for one time with a large width.

[0006]

However, the above-mentioned halftone expression system has the following problems.

In the case of the pseudo halftone expression means using binary values, the resolution may be lowered because one pixel is expressed by a plurality of ink droplets.

Further, in the method of performing halftone expression by arranging recording heads having different ejection amounts or a plurality of recording heads ejecting inks having different densities, not only there is a cost obstacle but also a recording apparatus. Size reduction (space saving)
Will be hindered. In particular, in the case of a multi-value full-color recording device, a plurality of recording heads must be arranged for each color, which makes it difficult to realize miniaturization.

The present invention solves the above-mentioned conventional problems,
An ink jet recording apparatus capable of stably performing multi-gradation recording with high image quality by controlling the ejection amount in multiple stages without impairing resolution and without requiring a plurality of recording heads or the like. Another object of the present invention is to provide an inkjet recording method.

[0010]

Therefore, according to the present invention, in an ink jet recording apparatus for ejecting ink to a recording medium to perform recording, a plurality of ejection ports for ejecting the ink and the plurality of ejection ports are provided. An ink flow path communicating with
The recording head provided with the ink flow path and having a heater for generating thermal energy used for ejecting ink ejects the ink, and controls the electric energy applied to the heater to generate the heat. Emission control means for varying the energy and ejecting the ink ejected from the plurality of ejection ports individually or in combination by the change is provided.

Furthermore, in an ink jet recording method in which recording is performed by using a recording head having a plurality of ink ejection ports and ejecting ink from the recording head onto a recording medium,
The ink ejected from the plurality of ejection ports is ejected individually or in combination.

[0012]

With the above arrangement, the size of the dots formed on the recording medium can be changed by ejecting the inks ejected from the plurality of ejection ports individually or in combination.

[0013]

Embodiments of the present invention will now be described in detail with reference to the drawings.

(Embodiment 1) FIGS. 1A to 1C are longitudinal sectional views of a recording head according to an embodiment of the present invention, and FIGS. 2A and 2B show the recording head. FIG.

As is clear from these figures, the recording head of this example has two ejection ports 11A and 11B having substantially the same shape and area for one ink flow path 12. When a small dot is formed using this recording head, relatively small energy is applied to the ejection heater 13 so that two separate ink droplets 25A and 25B are generated from the two ejection ports 11A and 11B. Is ejected. In this case, since the energy applied to the heater 13 is relatively small, as shown in FIG.
The diameter of 25B is not so large, and the diameter of the dot formed by the ink droplet landing on the recording paper is also relatively small.

In the example shown in FIG. 3B, the two dots 21A and 21B overlap each other to form an elongated dot shape. However, depending on the driving method of the heater 13, the small dots do not overlap and are separated. Can be formed as dots.

Next, the case of forming a large dot indicated by reference numeral 23 in FIG. 3C will be described.

In this case, as shown in FIGS. 1B and 1C, the energy applied to the ejection heater 13 is increased to combine the ink droplets 26A and 26B ejected from the two ejection openings 11A and 11B. One big ink drop 2
7 is discharged. In this case, the combined ink droplets 27 are larger than those ejected without being combined. This is the same ink droplet as that ejected from the ejection port whose diameter is a circle (see FIG. 2B) which is the distance between the furthest edges of the two ejection ports 11A and 11B. To grow. In addition, the above-mentioned distance between edges is also referred to as an effective discharge port diameter below.

The fact that coalescence of ink droplets as described above is useful in multi-gradation recording will be described below.

One of the factors affecting the diameter of the ejected ink droplet is the ejection port diameter. For example, even if a small amount of ink is ejected in a recording head having a certain ejection diameter by reducing the energy input to the ejection heater, if the ejection diameter is larger than the ink droplet to be ejected, Stable discharge cannot be realized because the surface tension pulls itself back.

On the other hand, since a large ink droplet is ejected with the predetermined ejection diameter, the ink droplet does not become so large even if a large input energy is applied to the ejection heater.

As described above, the size of the ink droplet to be ejected is substantially constant when the ejection port diameter is fixed, and if an ink droplet of a size deviating from it is attempted to be ejected, the ejection becomes unstable.

On the other hand, according to this example, since the diameter of each ejection port can be reduced, it is possible to eject a relatively small ink droplet from each ejection port, and ejection from two ejection ports. The formed ink drops can be combined into one ink drop by the surface tension of the ink drops. At this time, since the combined ink droplets are not separated from these ejection ports, as shown by the broken line in FIG. 2B, the ink droplets behave as if the ejection port diameter had increased, and the ink of a size determined by the effective ejection port diameter. Can eject drops. As described above, according to this example, the sizes of the small ink droplets and the large ink droplets can be set in a relatively large range, which is effective for multi-gradation recording.

As described above, the driving conditions for the case where the ink droplets are combined and ejected and the case where the ink droplets are ejected individually without being combined will be described below with reference to examples thereof.

First, in the case of individually ejecting from the two ejection ports, smaller ink droplets can be formed when the ink droplets are ejected from the ejection ports earlier. Therefore, by increasing the heat flux generated from the discharge heater to increase the bubble bubbling speed, thereby increasing the discharge speed and cutting off the energy input early, small ink droplets are discharged from each discharge port. Can be made.

On the contrary, in the case of ejecting a large ink droplet, the ink droplet does not become large if it is ejected from the ejection port early, so that the heat flux from the ejection heater is reduced and each ink droplet is ejected from the ejection port. And ejected as larger ink droplets.

The control of the heat flux or the applied energy is performed by controlling the voltage and pulse width of the drive pulse applied to the discharge heater. For example, when ejecting a small ink droplet, the drive pulse indicated by the symbol B in FIG. 4B is applied to increase the heat flow velocity. As a result, foaming as indicated by reference numeral b in FIG. 9A, that is, foaming that rapidly expands and contracts is generated. On the other hand, in the case of ejecting a large ink droplet, the pulse indicated by the symbol A in FIG. 4B is applied to reduce the heat flow rate, and the bubbling indicated by the symbol a in FIG.

In this case, preferably 1
A small heater and a large heater may be provided in one ink flow path, and the large and small heaters may be selectively used to obtain various ejected ink amounts. In that case, a relatively small ejection amount can be ejected by driving the small heater, and a relatively large ejection amount can be ejected by driving the large heater. When driving a small heater, the heat flux can be increased by foaming with a high voltage and a short pulse width, and with a large heater, foaming with a low voltage and a long pulse width can reduce the heat flux.

(Embodiment 2) FIG. 5 is a schematic front view of a recording head according to a second embodiment of the present invention.

In the first embodiment described above, the two ejection openings for each ink flow path are arranged in a direction substantially perpendicular to the surface of the ejection heater, but in this embodiment, as shown in the drawing, , Are arranged parallel to the surface of the discharge heater.

In this recording head, the driving of the ejection heater and the formation of ink droplets can be performed in the same manner as in the first embodiment. However, when ink is ejected simultaneously from all ejection ports of the recording head, the distance (d) between the two ejection ports 11A and 11B corresponding to one ink flow channel 12 is the ejection port of the adjacent ink flow channel. Distance with (p)
It must be smaller. If not, there is a risk of coalescing with the ink droplets ejected from the ejection ports of the adjacent ink paths.

Further, if the head configuration is such that the above relationship, d <p, is not satisfied, it is so arranged that adjacent ink flow paths do not eject simultaneously.

(Embodiment 3) FIG. 6 is a schematic front view showing an ink flow path and an ejection port of a recording head according to a third embodiment of the present invention.

In the recording head of this example, four ejection ports of substantially the same shape and area are arranged concentrically with respect to one ink flow path.

Also in this example, in the same manner as in Example 1, when forming small ink droplets, four small ink droplets are ejected by applying relatively small energy to the ejection heater, and within one pixel. To form four small dots.

Further, in the case of forming a large dot, the total energy input to the ejection heater is increased to combine the ink droplets ejected from the four ejection ports and eject them as one large ink droplet.

In this case, as in the case of FIG. 2B, the effective ejection port diameter in the case of a large ink droplet is as shown by the broken line in FIG. In this case, as compared with the case where the two ejection ports of the first embodiment are arranged, the effective ejection port diameter becomes larger, and it becomes easier to eject a larger ink droplet.

(Embodiment 4) FIG. 7 is a schematic front view showing an ink flow path and an ejection port of a recording head according to a fourth embodiment of the present invention, and FIG. 8 shows an example of recording by this recording head. It is a schematic diagram.

In the recording head of this embodiment, 16 ejection ports having substantially the same shape and area are arranged for one ink flow path.

When this recording head is used, for example, the energy input to the discharge heater is set to three levels, and a small ink droplet is individually discharged from each discharge port with the minimum energy of the three levels, as shown in FIG. A group of small dots 31A to 31D shown is formed. When driven by medium energy,
Out of 16 outlets, 4 sets of outlets make 1
One medium ink droplet that has merged into one ink droplet is ejected,
The four dots 32A to 32D formed by the medium ink drops are
It can be formed in the pixel 20. Furthermore, if the discharge heater is driven with the maximum energy of the three stages,
The medium ink droplets are further combined to be ejected as a large ink droplet, and the large dot 33 can be formed. As a result, recording in four stages is possible.

FIG. 9 is a schematic perspective view showing a main part of an ink jet recording apparatus using the recording head of each of the above-mentioned embodiments and capable of performing the above-mentioned ejection drive.

In FIG. 9, the recording head 1 is provided with a plurality of ink ejection openings (not shown) on the surface facing the recording paper 7, corresponding to one ink flow path as described above. In addition, the above-described ejection heater that generates thermal energy used for ink ejection is formed on the substrate that constitutes the recording head 1 in correspondence with each ink flow path. The discharge heater generates heat by an electric pulse applied to the discharge heater according to the drive data, thereby causing film boiling of the ink, and the ink is discharged from the discharge port as bubbles are generated by the film boiling. It Each ink path is provided with a common liquid chamber that communicates with them in common, and the ink stored therein is supplied to the ink path according to the ejection operation in each ink path.

The carriage 2 carries the recording head 1,
Further, the pair of guide rails 3 extending parallel to the recording surface of the recording paper 7 are slidably engaged. As a result, the recording head 1 can move along the guide rail 3,
With this movement, recording is performed by ejecting ink toward the recording surface at a predetermined timing. After the above movement, the recording paper 7 is conveyed by a predetermined amount in the direction of the arrow in the figure, and the above movement is performed again to perform recording. By repeating such an operation, recording is sequentially performed on the recording paper 7.

The recording head 1 may be detachably attached to the carriage 2 or may be detachably provided integrally with the ink tank.

The recording paper 7 is conveyed by rotating a pair of conveying rollers 4 and 5 arranged above and below the recording surface. Also, recording paper 7
A platen 6 for maintaining the flatness of the recording surface is provided on the back side of the recording surface.

The above-mentioned movement of the carriage 2 is made possible by driving, for example, a belt (not shown) attached to the carriage 2 by the motor, and the rotation of the motor is also performed by the rotation of the conveying rollers 4 and 5. It becomes possible by being transmitted to.

FIG. 10 is a block diagram showing the control arrangement of the ink jet recording apparatus shown in FIG.

In FIG. 10, the CPU 100 executes control processing and data processing of the operation of each part of the apparatus. ROM
The processing procedure and the like are stored in 100A, and also. RA
M100B is used as a work area for executing the above processing.

Ink ejection in the recording head 1 is CP
U100 supplies the drive data and drive control signal of the electrothermal converter to the head driver 1A. That is, the pulse applied to the discharge heater is controlled. Further, the CPU 100 controls the temperature (ink temperature) of the recording head 1 as will be described later, so that the electrothermal converter is driven to the extent that ejection is not achieved. Supply.
Further, the CPU 100 controls the rotation of the carriage motor 28 for moving the carriage 2 and the paper feed (PF) motor 50 for rotating the conveying rollers 4, 5 via the motor driver 28A and B50A, respectively. To do.

(Others) The present invention is provided with a means (for example, an electrothermal converter or a laser beam) for generating heat energy as energy used for ejecting ink, particularly in the ink jet recording system. The present invention brings about excellent effects in a recording head and a recording apparatus of the type in which the state of ink is changed by the heat energy. This is because such a system can achieve high density recording and high definition recording.

Regarding the typical structure and principle thereof, see, for example, US Pat. No. 4,723,129 and US Pat. No. 4,740.
What is done using the basic principles disclosed in 796 is preferred. This method is a so-called on-demand type,
Although it can be applied to any of the continuous type, in particular, in the case of the on-demand type, it can be applied to the sheet holding the liquid (ink) or the electrothermal converter arranged corresponding to the liquid path. By applying at least one drive signal corresponding to the recording information and giving a rapid temperature rise exceeding nucleate boiling, heat energy is generated in the electrothermal converter, and film boiling is caused on the heat acting surface of the recording head. Liquid (ink) corresponding to this drive signal in a one-to-one correspondence
It is effective because bubbles can be formed inside. Due to the growth and contraction of the bubbles, the liquid (ink) is ejected through the ejection opening to form at least one droplet. It is more preferable to make this drive signal into a pulse shape because bubbles can be immediately and appropriately grown and contracted, so that liquid (ink) ejection with excellent responsiveness can be achieved. As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. If the conditions described in US Pat. No. 4,313,124 of the invention relating to the rate of temperature rise on the heat acting surface are adopted, further excellent recording can be performed.

As the constitution of the recording head, in addition to the combination constitution of the ejection port, the liquid passage, and the electrothermal converter (the linear liquid passage or the right-angled liquid passage) as disclosed in the above-mentioned respective specifications. US Pat. No. 4,558,333, US Pat. No. 4,558,333, which discloses a configuration in which a heat acting portion is arranged in a bending region.
The structure using the specification of No. 59600 is also included in the present invention. In addition, Japanese Unexamined Patent Publication No. 59-123670 discloses a configuration in which a common slit is used as a discharge portion of the electrothermal converter for a plurality of electrothermal converters, and an opening for absorbing a pressure wave of thermal energy is provided. The effect of the present invention is effective even if the configuration corresponding to the ejection portion is disclosed in JP-A-59-138461. That is, according to the present invention, recording can be surely and efficiently performed regardless of the form of the recording head.

Furthermore, 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 that can be recorded by the recording apparatus. 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 recording head integrally formed.

In addition, even in the case of the serial type as in the above example, the recording head fixed to the main body of the apparatus or the electrical connection to the main body of the apparatus or the ink from the main body of the apparatus by being attached to the main body of the apparatus. The present invention is also effective when a replaceable chip-type recording head that can be supplied or a cartridge-type recording head in which an ink tank is integrally provided in the recording head itself is used.

Further, as the constitution of the recording apparatus of the present invention, it is preferable to add the ejection recovery means of the recording head, the preliminary auxiliary means and the like because the effects of the present invention can be further stabilized. Specifically, heating is performed by using a capping unit, a cleaning unit, a pressure or suction unit for the recording head, an electrothermal converter or a heating element other than this, or a combination thereof. Examples thereof include a preliminary heating unit for performing the discharge and a preliminary discharge unit for performing discharge different from the recording.

Regarding the type and number of recording heads to be mounted, for example, only one is provided corresponding to a single color ink, or a plurality of inks having different recording colors and densities are supported. A plurality of pieces may be provided. That is, for example, the recording mode of the recording apparatus is not limited to the recording mode of only the mainstream color such as black, but it may be either the recording head is integrally formed or a plurality of combinations may be used. The present invention is also extremely effective for an apparatus provided with at least one of full-color recording modes by color mixing.

In addition, in the above-described embodiments of the present invention, the ink is described as a liquid, but an ink that solidifies at room temperature or lower and that softens or liquefies at room temperature may be used. Or, in the inkjet system, it is common to control the temperature of the ink itself within the range of 30 ° C. or higher and 70 ° C. or lower to control the temperature so that the viscosity of the ink is within the stable ejection range. Sometimes, a liquid ink may be used. In addition, the temperature rise due to thermal energy is positively prevented by using it as the energy of the state change from the solid state of the ink to the liquid state, or in order to prevent the evaporation of the ink, it is solidified and heated in the standing state. You may use the ink liquefied by. In any case, by applying heat energy such as ink that is liquefied by applying heat energy according to the recording signal and liquid ink is ejected or that begins to solidify when it reaches the recording medium. The present invention can be applied to the case where an ink having a property of being liquefied for the first time is used. In this case, the ink is
JP-A-54-56847 or JP-A-60-7
As described in Japanese Patent No. 1260, it may be configured to face the electrothermal converter in a state of being held as a liquid or a solid in the concave portion or the 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, as a form of the ink jet recording apparatus of the present invention, besides the one used as an image output terminal of an information processing apparatus such as a computer, a copying apparatus combined with a reader or the like, and a facsimile apparatus having a transmitting / receiving function. It may be a form or the like.

[0059]

As is apparent from the above description, according to the present invention, the size of the dots formed on the recording medium can be obtained by ejecting the inks ejected from a plurality of ejection ports individually or in combination. Can be changed.

As a result, the area occupied by dots in a pixel can be changed in multiple steps and in a large range, and multi-tone recording can be performed without lowering the resolution in the ink jet recording system.

[Brief description of drawings]

1 (A), (B) and (C) are the first of the present invention.
FIG. 3 is a schematic cross-sectional view showing a recording head according to an example.

2A and 2B are schematic front views showing the recording head of the first embodiment. FIG.

3A is a schematic view showing an array of ejection ports in the first embodiment, and FIGS. 3B and 3C are schematic diagrams showing two examples of dots printed by the array.

4A and 4B are respectively a diagram and a waveform diagram showing a volume change of bubbles for ejection and ejection heater driving pulses corresponding thereto in the first embodiment.

FIG. 5 is a schematic front view showing an ejection port array of a recording head according to a second embodiment of the invention.

FIG. 6 is a schematic front view showing an ejection port array of a recording head according to a third embodiment of the invention.

FIG. 7 is a schematic front view showing an ejection port array of a recording head according to a fourth embodiment of the invention.

FIGS. 8A, 8B and 8C are schematic diagrams showing dots printed by using the printing head of the fourth embodiment.

FIG. 9 is a schematic perspective view showing a main part of an inkjet recording apparatus that can use the recording head of each of the above-described embodiments.

FIG. 10 is a block diagram showing a control configuration of the inkjet recording apparatus.

[Explanation of symbols]

1 Recording Head 2 Carriage 3 Guide Rail 4, 5 Conveying Roller 6 Platen 7 Recording Paper 11A, 11B, 11C, 11D Ejection Port 12 Ink Flow Path 13 Ejection Heater 14 Bubble 20 Pixel 21A, 22B, 23, 31A, 31B, 31C, 31
D, 32A, 32B, 32C, 32D 33 dots 25A, 25B, 26A, 26B, 27 ink droplets 100 CPU 100A ROM 100B RAM

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical indication location B41M 5/00 A 8808-2H 9012-2C B41J 3/04 103 X (72) Inventor Hiroyuki Ishinaga 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (4)

[Claims] 1. An ink jet recording apparatus for ejecting ink to a recording medium for recording, comprising: a plurality of ejection ports for ejecting ink; an ink flow path communicating with the plurality of ejection ports; and an ink flow. The generated thermal energy is changed by controlling the electric energy applied to the heater by ejecting the ink by using a recording head having a heater for generating thermal energy used for ejecting the ink, which is provided in the path. An ink jet recording apparatus comprising: an ejection control unit configured to eject the ink ejected from the plurality of ejection ports individually or in combination by the change. 2. An ink jet recording method in which a recording head having a plurality of ink ejection ports is used and recording is performed by ejecting ink from the recording head to a recording medium, the ink ejected from the plurality of ejection ports is combined. An ink jet recording method, characterized in that the ink is ejected after being discharged. 3. An ink jet recording method for recording by using a recording head having a plurality of ink ejection ports and ejecting ink from the recording head to a recording medium. An ink jet recording method, characterized in that the ink is ejected on or after being combined. 4. The inkjet recording method according to claim 2, wherein the recording head uses the thermal energy to generate bubbles in the ink and ejects the ink based on the generation of the bubbles. .