JP2005305828A - Inkjet recording head and inkjet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To widen a variable range of an ink amount to be ejected from ejection ports and to record a halftone image with high gray scale and high quality, in an inkjet recording head. <P>SOLUTION: A first heater 12 and a second heater 13, which can be mutually independently driven, are formed in ink flow channels 11 communicating with one ejection port 15 of the inkjet recording head, and a flow separation wall 14 for separating the ink flow channel 11 into a first and a second ink flow channels 11a, 11b arranged in parallel is formed between the first and the second heaters 12, 13. The first heater 12 is applied with voltage to foam the ink 18, ejecting relatively a small amount of ink droplets. In this case, the first and the second heaters 12, 13 are simultaneously driven with the same voltage waveforms to eject relatively a large amount of ink droplets, with no interruptions between the ink flows in the first ink flow channel 11a and the second ink flow channel 11b. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ink jet recording head and an ink jet recording apparatus, and in particular, a plurality of electrothermal transducers are provided for one ink discharge port, and the variable range of the amount of ink discharged from the discharge port is wide, so that a halftone image can be displayed. The present invention relates to an ink jet recording technique suitable for being used in an ink jet recording apparatus, a color filter manufacturing apparatus, and the like that can be expressed with high gradation.

  In an ink jet recording apparatus widely used today, there are roughly the following two methods for expressing halftones. The first method is a method of expressing by the number of ink droplets per pixel on the recording medium (a pseudo halftone expression with two values), and the second method is one inkjet recording head. This is a method of expressing by changing the ink discharge amount in multiple stages.

Patent Document 1 discloses an example of an ink jet recording head using a first method expressed by the number of ink droplets per pixel.
On the other hand, Patent Documents 2 to 4 disclose examples of an ink jet head using a second method for expressing gradation by changing ink discharge amounts in multiple stages.
The ink-jet head disclosed in Patent Document 2 arranges a plurality of heaters in the ink discharge direction along one ink flow path, and independently controls the heaters to be driven, so that the ink discharge amount can be increased in multiple stages. To change.
The ink jet recording head disclosed in Patent Document 3 naturally mixes ink droplets ejected from adjacent ink ejection ports when a plurality of ink ejection ports are brought close to each other and droplets after ink ejection spread out from the ejection port diameter. In this way, the amount of ink that flies is changed.
The ink jet recording head disclosed in Patent Document 4 is provided with a plurality of heaters at one discharge port, forms a surrounding wall smaller than the discharge port surrounding each of the plurality of heaters, and is driven according to the amount of ink to be discharged. The number of inks to be ejected is controlled in multiple stages by controlling the number of heaters.
JP 2002-337345 A Japanese Patent Laid-Open No. 10-71718 JP-A-11-235833 Japanese Patent Laid-Open No. 2002-273833

  In the halftone expression method in the ink jet recording apparatus, in order to perform high gradation recording, the first method of ejecting ink droplets per unit pixel according to the gradation greatly increases the resolution because the recording pixels are large. I can't. Therefore, a second method for expressing gradation by changing the ink discharge amount in multiple stages is promising. However, as disclosed in Patent Document 2, in the case of an ink jet head in which two heaters are provided in an ink flow path in which an ejection opening opens and the amount of ink ejected is controlled by the number of heaters to be driven, ink ejection In order to improve the characteristics, the drive timing of the voltage applied to each heater is shifted, the timing of foaming between the two heaters is shifted, the mutual interference of bubbles is suppressed, and the ink ejection characteristics are improved. However, a drive circuit for shifting the drive timing is required, which complicates the circuit configuration and causes an increase in cost. In addition, the conventional method of improving the ink ejection characteristics by shifting the timing of foaming by two heaters and minimizing the influence of each other's foaming always has the effect of foam interference, which is an ideal ink. It is not a discharge characteristic.

  In addition, in the inkjet head disclosed in Patent Document 2, when a plurality of ink discharge ports are brought close to each other and the droplets after ink discharge spread out from the diameter of the discharge port, the droplets discharged from the adjacent ink discharge ports are natural to each other. This is an example of an inkjet head in which the amount of ink flying is changed so as to be mixed. In the case of this ink jet head, since the droplets are mixed when ejected from the ejection port, the ejection direction of the mixed ink droplets and the recording target are determined by the variation in the timing of the ejected ink droplets and the variation in the amount of the ejected ink droplets. There has been a problem that the shape when landing on the medium varies and the image quality of the recorded print is lowered.

Furthermore, the ink jet head disclosed in Patent Document 4 has a plurality of heaters at one discharge port, and forms a surrounding wall smaller than the discharge port that surrounds each of the plurality of heaters. The number of heaters to be driven is controlled according to the amount of ink to be ejected, and the amount of ink to be ejected is controlled in multiple stages. The position of the ink ejected from the ejection port varies depending on the number of heaters to be driven. In other words, the discharge position changes depending on the amount of ink droplets to be discharged, and as a result, the landing position on the recording medium changes depending on the appropriate amount of ink liquid, and if gradation is ensured, the image quality deteriorates. there were.
The present invention is to solve the problems of the conventional ink jet head and ink jet recording apparatus as described above.

  The invention according to claim 1 of the present invention comprises an ink flow path to which ink is supplied from a common liquid chamber, and an electrothermal converter provided in the ink flow path. In the ink jet recording head that foams and discharges ink from the discharge port, a plurality of the electrothermal transducers are provided for one ink discharge port, and the ink flow path extends from the common liquid chamber to the discharge port and the electric heat is supplied. It consists of the parallel ink flow path part in which the conversion body is formed, It is characterized by the above-mentioned.

  According to a second aspect of the present invention, in the ink jet recording head according to the first aspect, the center line of the ink flow path from the common liquid chamber to the discharge port coincides with the center of the ink discharge port. Features.

  According to a third aspect of the present invention, in the ink jet recording head according to the first or second aspect, the respective cross-sectional areas of the parallel ink flow path portions are different from each other.

  According to a fourth aspect of the present invention, in the ink jet recording head according to any one of the first to third aspects, the calorific values of the electrothermal transducers formed in the parallel ink flow path portions are different from each other. It is characterized by that.

  According to a fifth aspect of the present invention, in the ink jet recording head according to any one of the first to fourth aspects, the areas of the electrothermal transducers formed in the parallel ink flow path portions are different from each other. It is characterized by.

  A sixth aspect of the present invention is an ink jet recording apparatus equipped with the ink jet recording head according to any one of the first to fifth aspects.

  The ink jet recording head according to claim 1 has an ink flow path portion in which an electrothermal transducer is formed so as to form an ink flow parallel to the ink flow from the common liquid chamber to the ejection port. Since the bubbles foamed inside do not interfere with each other and the size of the bubbles can be controlled reliably, the ink discharge amount can be accurately controlled. Further, since the amount of ink to be ejected is controlled as in the conventional example, a driving circuit for shifting the timing for driving the electrothermal converter is not necessary, and the circuit configuration is simplified and the cost can be reduced. Further, since ink droplets are mixed before ink ejection and ejected from one ejection port, the ejection direction and the shape when landed on the recording medium are uniform, and there is no deterioration in the image quality of the recorded print.

  In the ink jet recording head according to the second aspect, the center line of the ink flow path that forms a parallel ink flow with the ink flow from the common liquid chamber to the discharge port coincides with the center of the ink discharge port. When the ink is foamed by the electrothermal transducer, the generated pressure wave is uniformly propagated toward the ejection port, and the controllability of the ejected ink droplet amount can be improved. In addition, since the landing position on the recording medium does not change depending on the appropriate amount of ink liquid, image quality does not deteriorate even when gradation is ensured.

  In the ink jet recording head according to claim 3, since the cross-sectional areas of the respective ink flow path portions in which a plurality of electrothermal transducers formed with respect to one ink discharge port are formed are different from each other, one electrothermal conversion is performed. The size of bubbles generated in the ink by the body can be accurately controlled, and the amount of ink droplets to be ejected can be accurately controlled.

  5. The ink jet recording head according to claim 4, wherein a plurality of electrothermal transducers formed with respect to one ink discharge port have different calorific values, so that the sizes of bubbles when the ink is foamed are different from each other, and the ejected ink It is possible to finely control the drop amount.

  In the ink jet recording head according to claim 5, the areas of the electrothermal converters formed for one ink discharge port are different from each other, and the amount of heat generated is controlled by the area of the electrothermal converters. It can be formed by a technique, and the controllability of the area, that is, the amount of heat generated by the electrothermal converter can be easily controlled.

  Since the ink jet recording apparatus according to claim 6 records an image on a recording medium using the ink jet recording head according to claims 1 to 5, a halftone image is printed and recorded with high gradation and high definition. Is possible.

  In the ink jet recording head of the present invention, a plurality of electrothermal conversion elements that can be driven independently from each other are provided in an ink flow path communicating with one ejection port, and a plurality of ink flow paths are provided between the electrothermal conversion elements. A partition wall is provided in the ink flow path portion, and the ink in the ink flow path portion is foamed by selectively driving the electrothermal conversion element, so that the amount of ink droplets discharged from the discharge port is wide. This is an inkjet recording head that can be varied. Specific examples are described below.

An ink jet recording head according to Embodiment 1 of the present invention will be described.
1A and 1B are diagrams showing an ink jet recording head of Example 1, FIG. 1A is a plan cross-sectional view, and FIG. 1B is a cross-sectional view taken along line AA ′ of FIG.
The ink jet recording head of Example 1 includes a first heater 12 and a second electric heat which are first electrothermal transducers that can be driven independently from each other in an ink flow path 11 communicating with one ejection port 15. A second heater 13 as a converter is formed, and between the first and second heaters 12 and 13, two ink flow path portions in parallel with the ink flow path 11, that is, the first ink flow path 11a. And a flow path partition wall 14 is provided to be separated into the second ink flow path 11b. At this time, the center line 17 of the flow path partition 14 between the first and second heaters 12 and 13 and the center of the ink discharge port 15 are arranged to coincide with each other. On the other hand, the discharge ports 15 are separated by the discharge port partition 16.

  Ink supplied from an ink tank (not shown) is temporarily held in the common liquid chamber 10, and further enters the first ink flow path 11 a and the second ink flow path 11 b by capillary force, and is discharged from the discharge port 15. A meniscus is formed and the ink flow path 11 is filled. That is, the ink flow path 11 including the first ink flow path 11a and the second ink flow path 11b that form an ink flow parallel to the ink flow from the common liquid chamber 10 to the ink discharge port 15 is formed. Yes.

  In the ink jet recording head shown in FIG. 1, the first heater 12 and the second heater 13 are driven, and thermal energy is applied to the ink in the ink flow path 11, thereby causing a sudden volume change (bubble foaming) in the ink. Ink is discharged from the discharge port 15 by the force generated at this time. A common electrode (not shown) is connected to the ink discharge port 15 side of the first and second heaters 12 and 13, and an individual electrode is connected to the common liquid chamber 10 side of the first and second heaters 12 and 13. (Not shown) are connected and can be driven independently.

The operation when the first heater 12 and the second heater 13 are driven independently to change the amount of ink to be ejected will be described.
2A and 2B are views showing a state in which the first heater is driven independently and a relatively small amount of ink droplets are ejected. FIG. 2A is a cross-sectional plan view, and FIG. It is AA 'sectional drawing of A).
FIGS. 3A and 3B are diagrams showing a state in which the first and second heaters are simultaneously driven to eject a relatively large amount of ink droplets. FIG. 3A is a plan sectional view, and FIG. It is AA 'sectional drawing of 3 (A).
The first and second heaters 12 and 13 have the same size and material, and the cross-sectional areas of the first and second ink flow paths 11a and 11b have the same size.

In such an ink jet recording head, in order to eject a relatively small amount of ink droplets in FIG. 2, a voltage is applied only to the first heater 12 to foam the ink 18, and the amount of the ejected ink droplets 19 is determined. As a result of measurement, a value of 3 pl was obtained.
On the other hand, the first heater 12 and the second heater 13 are simultaneously driven with the same voltage waveform without shifting the timing of the voltage waveform to be driven as in the conventional example, and the foam 18 of the first heater 12 is driven. As a result of measuring the amount of ejected ink droplets 21 including reproducibility, the value of 6 pl was obtained each time. In other words, twice the discharge amount is obtained as compared with the case where discharge is performed only by the first heater 12, and the discharge amount is stable as designed without shifting the timing of the voltage waveform to be driven as in the prior art. Was obtained.

FIG. 4 is a diagram showing an example of an ink jet recording head in which ejection openings are formed on the same surface as the substrate surface, and the ink ejection direction is a direction perpendicular to the substrate surface, and FIG. 4 (B) is a cross-sectional view taken along line AA ′ of FIG. 4 (A).
As shown in FIG. 4, the same ejection characteristics as those in FIGS. 2 and 3 were obtained also in the ink jet recording head that ejects ink from the ejection port 22 formed in the same direction as the substrate surface.

  On the other hand, for comparison, a conventional ink jet in which the ink flow from the common liquid chamber 10 to the ink discharge port 15 is not parallel, that is, the flow path partition 14 is not formed between the first heater 12 and the second heater 13. As a result of performing the same measurement in the configuration of the recording head, the amount of the ejected ink was 1.2 to 2 times due to interference when the ink was foamed, and variation was caused by the measurement.

FIGS. 5A and 5B are diagrams showing the ink jet recording head of Example 2, FIG. 5A is a plan sectional view, and FIG. 5B is a sectional view taken along line AA ′ of FIG.
The ink jet recording head of Example 2 is configured so that the amount of ink discharged can be varied in multiple stages as compared with the ink jet recording head of Example 1.
An ink flow path portion that forms a parallel ink flow with respect to the ink flow from the common liquid chamber 10 to the ink discharge port 15, that is, the ink flow path 11 including the first ink flow path 11a and the second ink flow path 11b. With regard to the flow path cross-sectional area of the ink flow path, the second ink flow path 11b is formed smaller than the first ink flow path 11a, and the first ink flow path 11a is formed in the first ink flow path 11a. A first heater 12 that is a first electrothermal transducer and a second heater 13 that is a second electrothermal transducer are formed in the second ink flow path 11b. These are heaters that can be driven independently of each other. Between the first and second heaters 12 and 13, a flow path partition wall 14 constituting the first and second ink flow paths 11a and 11b is provided. At this time, the center line 17 of the flow path partition 14 between the first and second heaters 12 and 13 and the center of the ink discharge port 15 are arranged to coincide with each other. On the other hand, separation between the bits of each discharge port 15 is performed by the discharge port partition 16.

  Ink supplied from an ink tank (not shown) is temporarily held in the common liquid chamber 10 and further enters the ink flow path 11 by capillary force and forms a meniscus at the discharge port 15 to fill the ink flow path 11. Hold the state. In this state, the first heater 12 and the second heater 13 are driven to give thermal energy to the ink, thereby causing a sudden volume change (bubble foaming) in the ink. Ink is discharged from. A common electrode (not shown) is connected to the ink discharge port 15 side of the first and second heaters 12 and 13, and an individual electrode is connected to the common liquid chamber 10 side of the first and second heaters 12 and 13. (Not shown) are connected and can be driven independently.

Operation when the first and second heaters 12 and 13 are independently driven using the ink jet recording head of the second embodiment and the amount of ink to be ejected is changed more finely than that of the ink jet recording head of the first embodiment. Will be described.
6A and 6B are diagrams showing a state in which the second heater 13 is driven independently to eject a small amount of ink droplets. FIG. 6A is a plan sectional view, and FIG. 6B is a diagram in FIG. It is AA 'sectional drawing.
FIGS. 7A and 7B are diagrams showing a state in which the first heater is driven independently to discharge an intermediate amount of ink droplets. FIG. 7A is a plan sectional view, and FIG. 7B is a diagram in FIG. It is AA 'sectional drawing.
FIGS. 8A and 8B are diagrams showing a state in which the first and second heaters are simultaneously driven to eject a large amount of ink droplets. FIG. 8A is a cross-sectional plan view, and FIG. It is AA 'sectional drawing of).
In the ink jet recording head of Example 2, the second ink channel 11b whose channel cross-sectional area is 1/2 of the first ink channel 11a is formed, and the first ink channel 11a has the first ink channel 11a. A first heater 12 that is an electrothermal converter and a second heater 13 that is a second electrothermal converter are formed in the second ink flow path 11b, and the first heater 12 and the second heater are formed. 13 equalized size and material.

As shown in FIG. 6, using the ink jet recording head of Example 2, a voltage was applied only to the second heater 13 to cause the ink to foam 32, and the amount of ejected ink droplets 33 was measured. 5 pl.
On the other hand, as shown in FIG. 7, when a voltage was applied only to the first heater 12, the ink was foamed 34, and the amount of ejected ink droplets 35 was measured, the result was 3 pl.
Further, as shown in FIG. 8, the first heater 12 and the second heater 13 are simultaneously driven with the same voltage waveform without shifting the timing of the voltage waveform to be driven as in the conventional example. As a result of measuring the amount of the ejected ink droplet 36 including reproducibility by ejecting the ink by the foam 32 by the first heater 12 and the foam 34 by the second heater 13, a value of 4.5 pl is obtained each time. Thus, a total discharge amount was obtained when the discharge was performed only by the first heater 12 and the discharge was performed only by the second heater 13. That is, it is possible to stably obtain the ejection amount as designed without shifting the timing of the voltage waveform to be driven as in the conventional example, and it is possible to increase the stage of the ink ejection amount.

9A and 9B are diagrams showing the ink jet recording head of Example 3. FIG. 9A is a cross-sectional plan view, and FIG. 9B is a cross-sectional view taken along line AA ′ of FIG.
The ink jet recording head of Example 3 is configured so that the amount of ink discharged can be varied in multiple stages as compared with the ink jet recording head of Example 1.
An ink flow path portion that forms a parallel ink flow with respect to the ink flow from the common liquid chamber 10 to the ink discharge port 15, that is, the ink flow path 11 including the first ink flow path 11a and the second ink flow path 11b. A first electrothermal converter having a different area that can be driven independently from each other in the first and second ink flow paths 11a and 11b communicating with one ejection port 15 is formed. One heater 12 and a second heater 41 as a second electrothermal converter are formed. Between the first and second heaters 12 and 41, there is provided a flow path partition wall 14 that forms a first ink flow path 11a and a second ink flow path 11b. At this time, the center line 17 of the flow path partition 14 between the first and second heaters 12 and 41 and the center of the ink discharge port 15 are arranged to coincide with each other. On the other hand, separation between the bits of each discharge port 15 is performed by the discharge port partition 16. Ink supplied from an ink tank (not shown) is temporarily held in the common liquid chamber 10, and further enters the first and second ink flow paths 11a and 11b by capillary force to form a meniscus at the discharge port 15. Thus, the state where the ink flow path 11 is filled is maintained.

  In this state, the first heater 12 and the second heater 41 are driven to give thermal energy to the ink, thereby causing a sudden volume change (bubble bubbling) in the ink. Ink is ejected from the outlet 15. A common electrode (not shown) is connected to the ink discharge port 15 side of the first and second heaters 12 and 41, and an individual electrode is connected to the common liquid chamber 10 side of the first and second heaters 12 and 41. (Not shown) are connected and can be driven independently.

About the operation | movement at the time of driving the 1st, 2nd heaters 12 and 41 independently using the inkjet recording head of Example 3, and changing the amount of the ink to eject more finely than the inkjet recording head of Example 1. explain.
FIGS. 10A and 10B are diagrams illustrating a state where the second heater is driven independently to eject a small amount of ink droplets. FIG. 10A is a cross-sectional plan view, and FIG. 10B is a diagram of FIG. It is AA 'sectional drawing.
FIGS. 11A and 11B are views showing a state in which the first heater is driven independently to discharge an intermediate amount of ink droplets. FIG. 11A is a cross-sectional plan view, and FIG. 11B is a view in FIG. It is AA 'sectional drawing.
12A and 12B are diagrams showing a state in which the first and second heaters are simultaneously driven to eject a large amount of ink droplets. FIG. 12A is a cross-sectional plan view, and FIG. It is AA 'sectional drawing of).

A second heater 41 having the same material and an area of 1 / 2.5 of the first heater 12 is formed in the second ink channel 11b, and the first and second ink channels 11a, 11a, As shown in FIG. 10, using the inkjet recording head of Example 3 in which the flow path cross-sectional area of 11b is equal, a voltage is applied only to the second heater 41, the ink is foamed 42, and the ejected ink droplet 43 As a result, the amount was 1.5 pl.
On the other hand, as shown in FIG. 11, the voltage was applied only to the first heater 12 and the amount of the ink droplet 45 in which the ink was foamed 44 was measured and found to be 3 pl.
Further, as shown in FIG. 12, the first heater 12 and the second heater 41 are simultaneously driven with the same voltage waveform without shifting the timing of the voltage waveform to be driven as in the conventional example. As a result of measuring the amount of the ejected ink droplet 46 including reproducibility by ejecting ink by the foam 44 by the first heater 12 and the foam 42 by the second heater 41, a value of 5 pl was obtained each time. That is, it is the total discharge amount when discharged only by the first heater 12 and when discharged only by the second heater 41, and is designed without shifting the timing of the voltage waveform to be driven as in the prior art. In addition to the stable ejection amount being obtained, it was possible to increase the level of ink ejection amount.

  On the other hand, for comparison, conventional ink jet recording in which the ink flow from the common liquid chamber 10 to the ink discharge port 15 is not parallel, that is, the flow path partition 14 is not formed between the first and second heaters 12 and 41. As a result of performing the same measurement in the configuration of the head, the amount of ink ejected due to interference when foaming was 1.2 to 2 times, and variation was caused by the measurement.

13A and 13B are diagrams showing the ink jet recording head of Example 4. FIG. 13A is a cross-sectional plan view, and FIG. 13B is a cross-sectional view taken along line AA ′ of FIG.
The ink jet recording head of Example 4 can expand the variable range of the amount of ink ejected compared to the ink jet recording head of Example 3.
An ink flow path portion that forms a parallel ink flow with respect to the ink flow from the common liquid chamber 10 to the ink discharge port 15, that is, the ink flow path 11 including the first ink flow path 11a and the second ink flow path 11b. In terms of the flow path cross-sectional area of the ink flow path, the second ink flow path 11b smaller than the first ink flow path 11a is formed, and the first ink flow path 11a is formed in the first ink flow path 11a. A first heater 12 that is a first electrothermal converter and a second heater 51 that is a second electrothermal converter are respectively formed in the second ink flow path 11b. These are heaters that can be driven independently of each other. At this time, the area of the first heater 12 was formed to be twice the area of the second heater 51.

  Between the first and second heaters 12 and 51, a flow path partition wall 14 constituting the first and second ink flow paths 11a and 11b is provided. At this time, the center line 17 of the flow path partition 14 and the center of the ink discharge port 15 are arranged to coincide. On the other hand, separation between the bits of each discharge port 15 is performed by the discharge port partition 16. Ink supplied from an ink tank (not shown) is temporarily held in the common liquid chamber 10, and further enters the first and second ink flow paths 11a and 11b by capillary force to form a meniscus at the discharge port 15. Thus, the state where the first and second ink flow paths 11a and 11b are filled is maintained. In this state, the first heater 12 and the second heater 51 are driven to give thermal energy to the ink, thereby causing a sudden volume change (bubble bubbling) in the ink. Ink is discharged from. A common electrode (not shown) is connected to the ink discharge port 15 side of the first and second heaters 12 and 51, and an individual electrode is connected to the common liquid chamber 10 side of the first and second heaters 12 and 51. (Not shown) are connected and can be driven independently.

The operation when the first and second heaters 12 and 51 are independently driven using the ink jet recording head of the fourth embodiment and the amount of ink to be ejected is larger than that of the ink jet recording head of the third embodiment will be described.
FIGS. 14A and 14B are views showing a state in which the second heater is driven independently to eject a small amount of ink droplets. FIG. 14A is a cross-sectional plan view, and FIG. 14B is a diagram of FIG. It is AA 'sectional drawing.
FIGS. 15A and 15B are diagrams showing a state in which the first heater is driven independently to eject an intermediate amount of ink droplets. FIG. 15A is a cross-sectional plan view, and FIG. 15B is a diagram in FIG. It is AA 'sectional drawing.
FIGS. 16A and 16B are diagrams showing a state in which the first and second heaters are simultaneously driven to eject a large amount of ink droplets. FIG. 16A is a plan cross-sectional view, and FIG. It is AA 'sectional drawing of).
A second ink channel 11b having a channel cross-sectional area of the ink channel that is 1/2 that of the first ink channel 11a is formed, and the first electrothermal transducer is formed in the first ink channel 11a. A second heater 51, which is a second electrothermal converter, is formed in each of the first heater 12 and the second ink flow path 11b, and the area of the first heater 12 is the area of the second heater 51. 2 times.

With such an ink jet recording head, as shown in FIG. 14, the voltage was applied only to the second heater 51, the ink was caused to foam 54, and the amount of ejected ink droplets 55 was measured. .
On the other hand, as shown in FIG. 15, when a voltage was applied only to the first heater 12 to cause the ink to foam 56 and the amount of the ink droplets 57 was measured, the result was 4 pl.
Further, as shown in FIG. 16, the first heater 12 and the second heater 51 are simultaneously driven with the same voltage waveform without shifting the timing of the voltage waveform to be driven as in the conventional example. As a result of measuring the amount of ink droplets 58 ejected by the foam 56 of the first heater 12 and the foam 54 of the second heater 51 including reproducibility, a value of 5 pl was obtained each time. A total discharge amount was obtained when the discharge was performed only by the first heater 12 and the discharge was performed only by the second heater 51. In other words, it is possible to control the ink discharge amount in a wider range than in the third embodiment, and the discharge amount as designed can be stably obtained without shifting the timing of the voltage waveform to be driven as in the prior art. It was possible to increase the range of ink discharge amount.

Next, an ink jet recording apparatus of Example 5 equipped with the ink jet recording head according to the present invention will be described.
FIG. 17 is a perspective view showing an ink jet recording apparatus of Example 5, and FIG. 18 is a side cutaway view showing a mechanism part of the ink jet recording apparatus.
The ink jet recording apparatus according to the fifth embodiment includes a carriage 73 that can move in the main scanning direction inside the recording apparatus main body 61, a recording head 74 that includes the ink jet recording head according to the first to fourth embodiments mounted on the carriage 73, and the recording head 74. A paper feed cassette (or a paper feed tray) that accommodates a printing mechanism 62 or the like composed of an ink cartridge 75 that supplies ink and can stack a large number of sheets 63 from the front side in the lower part of the apparatus main body 61. It is also possible to insert and unload 64. Also, the manual feed tray 65 for manually feeding the paper 63 can be opened and fed from the paper feed cassette 64 or the manual feed tray 65. The paper 63 to be taken in is recorded, and a required image is recorded by the printing mechanism 62, and then discharged onto a paper discharge tray 66 mounted on the rear side.

  The printing mechanism 62 holds the carriage 73 slidably in the main scanning direction (the direction perpendicular to the paper in FIG. 18) with a main guide rod 71 and a sub guide rod 72 which are guide members horizontally mounted on left and right side plates (not shown). The carriage 73 is formed of an ink jet recording head according to Embodiments 1 to 4 of the invention that ejects ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (Bk). The head 74 is mounted with a plurality of ink ejection openings (nozzles) arranged in a direction crossing the main scanning direction, and the ink droplet ejection direction is directed downward. In addition, each ink cartridge 75 for supplying ink of each color to the recording head 74 is replaceably mounted on the carriage 73. The ink cartridge 75 has an air port that communicates with the atmosphere above, a supply port that supplies ink to the recording head 74 below, and a porous body filled with ink inside. The ink supplied to the recording head 74 by the force is maintained at a slight negative pressure. In addition, although the heads of the respective colors are used here as the recording head 74, a single head having nozzles for ejecting ink droplets of the respective colors may be used.

  Here, the carriage 73 is slidably fitted on the main guide rod 71 on the rear side (downstream side in the paper conveyance direction), and is slidably mounted on the sub guide rod 72 on the front side (upstream side in the paper conveyance direction). doing. In order to move and scan the carriage 73 in the main scanning direction, a timing belt 80 is stretched between a driving pulley 78 and a driven pulley 79 that are rotationally driven by a main scanning motor 77, and the timing belt 80 is moved to the carriage 73. The carriage 73 is reciprocally driven by forward and reverse rotations of the main scanning motor 77.

  On the other hand, in order to convey the sheet 63 set in the sheet feed cassette 64 to the lower side of the recording head 74, the sheet feed roller 81 and the friction pad 82 for separating and feeding the sheet 63 from the sheet feed cassette 64 and the sheet 63 are guided. A guide member 83 for conveying, a conveyance roller 84 for conveying the fed sheet 63 in a reversed manner, a conveyance roller 85 pressed against the peripheral surface of the conveyance roller 84, and a feeding angle of the sheet 63 from the conveyance roller 84. A tip roller 86 is provided. The transport roller 84 is rotationally driven by a sub-scanning motor 87 through a gear train. A printing receiving member 89 is provided as a paper guide member that guides the paper 63 fed from the transport roller 84 on the lower side of the recording head 74 corresponding to the movement range of the carriage 73 in the main scanning direction. A conveyance roller 91 and a spur 92 that are rotationally driven to send out the paper 63 in the paper discharge direction are provided on the downstream side of the printing receiving member 89 in the paper conveyance direction, and the paper 63 is further delivered to the paper discharge tray 66. A roller 93 and a spur 94, and guide members 95 and 96 that form a paper discharge path are disposed.

  At the time of recording, the recording head 74 is driven according to the image signal while moving the carriage 73, thereby ejecting ink onto the stopped sheet 63 to record one line. Record the line. Upon receiving a recording end signal or a signal that the trailing edge of the sheet 63 has reached the recording area, the recording operation is terminated and the sheet 63 is discharged. Further, a recovery device 97 for recovering defective ejection of the recording head 74 is disposed at a position outside the recording area on the right end side in the movement direction of the carriage 73. The recovery device 97 includes a cap unit, a suction unit, and a cleaning unit. The carriage 73 is moved to the recovery device 97 side during printing standby, and the recording head 74 is capped by the capping unit, and the ejection port portion is kept in a wet state to prevent ejection failure due to ink drying. Further, by ejecting ink that is not related to recording during recording or the like, the ink viscosity of all the ejection ports is made constant and stable ejection performance is maintained.

  In the case where a discharge failure occurs, the discharge port (nozzle) of the recording head 74 is sealed with a capping unit, and bubbles and the like are sucked out from the discharge port with the suction unit through the tube. Etc. are removed by the cleaning means, and the ejection failure is recovered. Further, the sucked ink is discharged to a waste ink reservoir (not shown) installed at the lower part of the main body and absorbed and held by an ink absorber inside the waste ink reservoir.

  As described above, since the inkjet head embodying the present invention is mounted in this inkjet recording apparatus, there is no ink droplet ejection failure due to vibration plate drive failure, stable ink droplet ejection characteristics are obtained, and image quality is improved. improves.

  In the first to fifth embodiments, the present invention is applied to the ink jet recording head and the ink jet recording apparatus. However, the present invention can also be applied to a liquid ejection head that ejects a liquid other than ink, for example, a liquid resist for patterning or DNA. .

1 is a diagram illustrating an ink jet recording head of Example 1. FIG. It is a figure which shows a mode at the time of driving a 1st heater independently and discharging a relatively small amount of ink droplets. It is a figure which shows the mode at the time of driving a 1st, 2nd heater simultaneously, and discharging a comparatively large amount of ink droplets. FIG. 2 is a diagram illustrating an example of an ink jet recording head in which ejection ports are formed on the same surface as a substrate surface and the ink ejection direction is a direction perpendicular to the substrate surface. FIG. 6 is a diagram illustrating an ink jet recording head of Example 2. It is a figure which shows a mode at the time of driving a 2nd heater independently and discharging a small amount of ink droplets. It is a figure which shows a mode at the time of driving a 1st heater independently and discharging an intermediate amount of ink droplets. It is a figure which shows the mode at the time of driving a 1st, 2nd heater simultaneously, and discharging a large amount of ink droplets. 6 is a diagram illustrating an inkjet recording head of Example 3. FIG. It is a figure which shows a mode at the time of driving a 2nd heater independently and discharging a small amount of ink droplets. It is a figure which shows a mode at the time of driving a 1st heater independently and discharging an intermediate amount of ink droplets. It is a figure which shows the mode at the time of driving a 1st, 2nd heater simultaneously, and discharging a large amount of ink droplets. 6 is a diagram illustrating an inkjet recording head of Example 4. FIG. It is a figure which shows a mode at the time of driving a 2nd heater independently and discharging a small amount of ink droplets. It is a figure which shows a mode at the time of driving a 1st heater independently and discharging an intermediate amount of ink droplets. It is a figure which shows the mode at the time of driving a 1st, 2nd heater simultaneously, and discharging a large amount of ink droplets. 6 is a perspective view showing an ink jet recording apparatus of Example 5. FIG. FIG. 10 is a side cutaway view showing a mechanism part of the ink jet recording apparatus of Example 5.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Ink flow path, 11a ... 1st ink flow path, 11b ... 2nd ink flow path, 12 ... 1st heater, 13, 41, 51 ... 2nd heater, 14 ... Flow path partition, 15, 22 ... discharge port, 16 ... discharge port partition, 17 ... center line (of the flow channel partition), 18, 20, 32, 34, 42, 44, 54, 56 ... (ink) foaming, 19, 21, 33, 35, 43, 45, 46, 55, 57, 58 ... ink droplets, 61 ... recording device main body, 62 ... printing mechanism, 63 ... paper, 64 ... paper feed cassette, 65 ... manual feed tray, 66 ... paper discharge tray, 71: Main guide rod, 72: Sub guide rod, 73: Carriage, 74: Recording head 74, 75 ... Ink cartridge, 77 ... Main scanning motor, 78 ... Drive pulley, 79 ... Drive pulley, 80 ... Timing belt, 81 ... Feed roller, 82 ... free 83 ... guide member, 84 ... conveying roller, 85 ... conveying roller, 86 ... front end roller, 87 ... sub-scanning motor, 89 ... printing receiving member, 91 ... conveying roller, 92 ... spur, 93 ... discharge roller 94 ... Spurs, 95, 96 ... Guide members, 97 ... Recovery device.

Claims (6)

An ink jet comprising an ink flow path to which ink is supplied from a common liquid chamber and an electrothermal converter provided in the ink flow path, wherein the ink is foamed by the heat generated by the electrothermal converter and the ink is discharged from a discharge port. In the recording head,
A plurality of the electrothermal converters are provided for one ink discharge port, and the ink flow path extends from the common liquid chamber to the discharge port from a parallel ink flow path portion where the electrothermal converter is formed. An ink jet recording head. The ink jet recording head according to claim 1.
An ink jet recording head, wherein a center line of the ink flow path from the common liquid chamber to the discharge port coincides with a center of the ink discharge port. The inkjet recording head according to claim 1 or 2,
An ink jet recording head, wherein the parallel ink flow path portions have different cross-sectional areas. The inkjet recording head according to any one of claims 1 to 3,
An ink jet recording head according to claim 1, wherein each of the electrothermal transducers formed in the parallel ink flow path portions has different heat generation amounts. The inkjet recording head according to any one of claims 1 to 4,
An ink jet recording head according to claim 1, wherein areas of the electrothermal transducers included in the parallel ink flow path portions are different from each other.   An ink jet recording apparatus comprising the ink jet recording head according to claim 1.