JPH0948125A - Recording head, ink jet recording apparatus using the same and recording method of recording head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide two heaters to one ink passage, to make the emitting speeds of ink liquid droplets almost same when small and large heaters are driven individually or simultaneously and to increase a difference in emitting quantity. SOLUTION: Two heaters 104, 105 having different areas are provided in one of the ink passages 106 of the recording head of an ink jet recording apparatus and two emitting orifices 101, 102 having different orifice areas corresponding to the heaters are arranged. Two emitting orifices are separated by a threshold wall and a small projection part is arranged to the threshold wall on the side of the small emitting orifice 101. Two heaters are selectively heated corresponding to image data to be recorded and the size of ink droplets is changed by the difference of the size of generated air bubbles.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording head of an ink jet recording apparatus for ejecting ink droplets toward a recording medium for recording, and particularly to an ink jet for ejecting ink droplets of plural sizes to perform recording. The present invention relates to a recording head of a recording device, an inkjet recording device using the recording head, and a recording method of the recording head.

[0002]

2. Description of the Related Art A conventionally used recording head of an ink jet recording apparatus for recording by ejecting ink droplets of a plurality of sizes has generally employed a structure shown in FIG. FIG. 6 is an overall schematic configuration diagram of a recording head of a conventional ink jet recording apparatus.
02 is a large nozzle, 604 is a small heater,
Reference numeral 605 is a large heater, and 606 is an ink flow path. In this method, two heaters 604 and 605 are provided in the ink flow path 606, and each heater is driven to change the ejection amount. The heaters have different areas as shown in FIG. 6, and it is possible to realize three kinds of discharge amounts, that is, only the small heater 604, the large heater 605, or the large and small heaters 604 and 605 are driven simultaneously.

The reason why such a recording head has been used is as follows. Recently, in order to print a high-quality image, a method of performing multi-valued recording by changing the size of ink droplets, and a method of printing with various resolutions by one recording head have been developed. As one example, there is a method of changing the energy applied to the heater. However, in the conventional recording head, the bubbles generated by applying heat to the heater are substantially determined by the area of the heater, and the size of the droplet, that is, the discharge amount, is changed by changing the energization time to the heater to some extent. The change was small, and it was not effective as a method of multilevel recording. Therefore, a recording head having a structure as shown in FIG. 6 has come to be used.

[0004]

However, in the above-mentioned conventional technique, the ejection speed of the ink droplets varies depending on the ejection amount change, the deviation of the landing point occurs, the ejection speed is very slow, and the ejection stability is poor. However, there is a problem in that the printed image is significantly deteriorated due to the ink droplet dripping. FIG. 3 is a graph showing the relationship between the ejection amount of ejection droplets and the ejection speed in the inkjet recording apparatus obtained by our experiment.
That is, the "discharge speed-discharge amount relationship line (S ₀ 680)" indicated by reference numeral 309 in FIG. 3 is the large hole nozzle 6 shown in FIG.
No. 02 discharge port area S ₀ = 680 μm ² . A point indicated by a small symbol on the line 309 is a case where only the small heater 604 in FIG. 6 is driven, and a discharge rate of 20 ng and a discharge speed of 4 m / s.
Is shown. A point indicated by a large code on the line 309 is a case where only the large heater 605 in FIG. 6 is driven, and shows a discharge speed of 12 m / s at a discharge amount of 60 ng. The point indicated by the code large + small on the line 309 indicates the case of simultaneous driving of the large heater 605 and the small heater 604 in FIG. That is, in a certain one nozzle structure (one ejection port), when the two heaters are driven individually or simultaneously, the ejection amount and the ejection speed are in a proportional relationship.

It is said that the discharge speed is usually required to be 10 m / s or more in order not to deteriorate the image, and the small heater 6 shown in FIG.
The ejection speed in the case of driving only 04 is 4 m / s, which causes image deterioration due to ink droplet deviation. The deviation of the landing point can be corrected by changing the scanning speed of the recording head when performing three types of ejection, but when the ejection amount is small, the ejection speed also becomes small, and ejection stability is improved. And the image deteriorates.

[0006] indicated by reference numeral 310 in FIG. 3 "discharge speed - discharge amount relational lines (S ₀ 300)" is a recording head using the small hole nozzle in place of the large hole nozzle 602 of FIG. 6, the discharge port area S ₀ = 300 μm ² . Line 31
A point indicated by a small symbol on 0 indicates a case where only the small heater 604 in FIG. 6 is driven, and shows a discharge speed of 12 m / s at a discharge amount of 20 ng. That is, when the discharge port area S ₀ = 300 μm ² , the discharge speed when only the small heater 604 is driven is 10 m / s.
As mentioned above, when the large heater 605 and the small heater 604 are simultaneously driven, there is a problem that the discharge amount cannot be obtained when the discharge port area S ₀ = 680 μm ² .

An object of the present invention is to improve the ejection speed of ink droplets when a small heater and a large heater are driven individually or simultaneously in a recording head of an ink jet recording apparatus in which two heaters are provided in one ink flow path. An object of the present invention is to provide a recording head of an inkjet recording apparatus that can be substantially the same and can increase a difference in ejection amount, an inkjet recording apparatus using the recording head, and a recording method of the recording head.

[0008]

In a recording head of an ink jet recording apparatus of the present invention, a heater is disposed in an ink flow passage in a nozzle of the recording head, and the heater is heated to discharge the ink at the tip of the ink flow passage. In a recording head of an inkjet recording apparatus in which ink droplets are ejected from an outlet to perform recording, a heater having two different areas in an ink flow path and an ejection port having two different opening areas corresponding to the heater are arranged. It is set up.

Further, a plurality of ink flow paths may be arranged in parallel.

Further, two ejection ports may be arranged in parallel so as to be perpendicular to the longitudinal direction of the ink flow path and perpendicular to the arrangement direction of the plurality of ink flow paths. Two ejection ports may be arranged in parallel in a direction parallel to the arrangement direction of the ink flow paths.

Further, a threshold wall may be provided between the ink passage side openings of the ejection opening (small hole) having a small opening area and the ejection opening (large hole) having a large opening area so that the small hole is on the lower side. Placed in the small area heater (small heater)
The heater having a large area (large heater) may be arranged below the threshold wall and separated from the small heater and the threshold wall in the direction opposite to the discharge port. Small protrusions may be provided at corresponding positions between the small heater and the large heater.

Further, the opening angle of the ejection port may be set so that the two ink droplets ejected from the two ejection ports have substantially the same landing point on the recording medium.

An ink jet recording apparatus using the recording head of the present invention is an ink jet recording apparatus provided with recording means for ejecting ink according to a signal to perform recording.
The recording head described above is used.

The recording method of the recording head of the inkjet recording apparatus of the present invention is the recording method of the recording head of the above-mentioned inkjet recording apparatus, in which two heaters are selectively used in accordance with a signal of image information to be recorded. Heated
By ejecting liquid droplets having different sizes according to the generated bubbles from the ejection ports having the corresponding opening areas,
Droplets are landed on the recording medium at almost the same speed.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic sectional view of an inkjet nozzle according to a first embodiment of the present invention, and FIG. 2 is an overall schematic configuration diagram of a recording head of an inkjet recording apparatus according to the first embodiment. In the figure, 101 is a small hole nozzle, 102 is a large hole nozzle, 103 is a threshold wall, 104 is a small heater, 105 is a large heater, 106 is an ink flow path, 1
Reference numeral 07 is a small protrusion, and 108 is a protrusion (LC).

In FIG. 1 or 2, at the tip of the ink flow path 106 of each nozzle, the ejection ports of the two nozzles 101 and 102 are perpendicular to the longitudinal direction of the ink flow path, and a plurality of ink flow paths are formed. So that it is perpendicular to the alignment direction,
It is juxtaposed. The discharge port (small hole) of the nozzle 101 has a smaller opening area than the discharge port (large hole) of the nozzle 102. Further, there are two heaters 104 and 105, and the area of the heater is smaller in the heater 104 (small heater) than in the heater 105 (large heater). The threshold wall 103 is for separating the two discharge ports, and a small protrusion 107 for further strengthening the separation is hanging from the threshold wall 103. The threshold wall 103 and the small protrusion 107 prevent ink from being ejected from the large hole of the large hole nozzle 102 when the small heater 104 is driven, and from the small hole nozzle 101 when the large heater 105 is driven. It is provided. Further, the projection 108 at the rear of the flow path is for increasing the ink ejection efficiency due to the bubbles when the heater is driven, and is called LC.

FIG. 3 is a graph showing the relationship between the discharge amount and the discharge speed of the liquid droplets discharged from the nozzle with the discharge port area as a parameter, and FIG. 4 is the ink in the recording head of the first embodiment. FIG. 3 is a conceptual diagram showing the state of droplet generation and flight,
[a] to [c] show the large heater 40 when only the small heater 404 is driven.
Only the driving of No. 5 and the simultaneous driving of the small heater 404 and the large heater 405 are shown. In the figure, 401 is a small hole nozzle, 4
02 is a large hole nozzle, 404 is a small heater, 405 is a large heater, 411 is a small bubble, 412 is a small drop, 413 is a recording medium, 414 is a large bubble, and 415 is a large drop.

First, when only the small heater 404 is driven, as shown in FIG. 4A, the ink on the upper portion of the small heater 404 is rapidly heated and small bubbles 411 are generated. As a result, the small drop 412 of the displaced ink is discharged from the corresponding small hole of the small hole nozzle 401, and the recording medium 413.
Recorded above. The discharge amount at this time depends on the size of the bubble, that is, the heater area, and the discharge speed depends on the discharge port area. For example, if the discharge port area of the small hole nozzle 401 is 300μ
and m ^2, the area of the small heater 404 and equivalent to that of the conventional FIG. 6, "the discharge rate of 3 - discharge amount relational lines (S ₀ 30
0) ”310, as indicated by the small dots on the small heater 4
The discharge amount when driving only 04 is 20 ng and the discharge speed is 12
m / s.

Similarly, when only the large heater 405 is driven, as shown in FIG. 4B, the ink on the upper portion of the large heater 405 is rapidly heated and large bubbles 414 are generated. As a result, the large drop 415 of the displaced ink is ejected from the corresponding large hole of the large hole nozzle 402 and recorded on the recording medium 413. The discharge amount at this time also depends on the size of the bubble, that is, the heater area, and the discharge speed also depends on the discharge port area.
For example the discharge port area of the large hole nozzles 402 and 680 micrometer ^2, in Figure 3 the area of the large heater 405 equivalent to the conventional 6 "discharge speed - discharge amount relational lines (S ₀ 680)" 30
As indicated by the reference numeral 9 in FIG. 9, the discharge amount when driving only the large heater 405 is 60 ng, and the discharge speed is 12 m / s. At this time, by adjusting the angle of the ejection port, the landing point of the ink on the recording medium 413 is increased by a large drop 41.
5 and the small drop 412 can be set at substantially the same position. Further, since the ejection speeds are almost the same, it is not necessary to change the scanning speed of the recording head depending on the ejection amount.

When the small heater 404 and the large heater 405 are driven at the same time, the two heaters 404 and 405 are driven at the same time as shown in FIG.
1 and 414 are generated, and the small drop 412 is the small hole nozzle 4.
From the small hole 01, the large drop 415 is the large hole nozzle 402.
Are ejected from the respective large holes and recorded on the recording medium 413. The discharge amount at this time depends on the size of the bubble, that is, the heater area, and the discharge speed depends on the discharge port area. For example 300 [mu] m ² discharge port area of the small hole nozzle 401, the discharge port area of the large hole nozzles 402 and 680 micrometer ^2, a small heater 4
Assuming that the area of 04 and the area of the large heater 405 are the same as those of the conventional FIG. 6, the “discharge speed-discharge amount relational line (S ₀ 30
0) ”310, the discharge amount when the small heater is driven is 20 ng, and the discharge speed is 12 m / s, as indicated by the small symbol on 310, and the“ discharge speed-discharge amount relationship line (S ₀ 680) ”in FIG.
As indicated by the large code on 309, the ejection amount when the large heater is driven is 60 ng, and the ejection speed is 12 m / s. That is, the discharge amount when the small heater 404 and the large heater 405 are simultaneously driven is 80 ng, which is a discharge amount of 20 ng when the small heater is driven and a discharge amount of 60 ng when the large heater is driven. The discharge speeds are almost the same and are 12 m / s. At this time, the ink recording medium 41
The impact points for 3 are small drop 412 and large drop 4
As described above, the angles of the discharge ports are adjusted so that the positions of 15 are almost the same.

In this way, the discharge amount can be changed, and the discharge speeds are stable and substantially equal, so that multi-value recording or printing with various resolutions can be realized. For example, at 80 ng shown in the example, 360 dpi (dot per in
ch) and 720 dpi can be printed at 20 ng. Furthermore, it is possible to print at a printing rate of 400 dpi at 60 ng.

A second embodiment of the present invention is shown in FIG.
FIG. 5 is an overall schematic configuration diagram of a recording head of the inkjet recording apparatus according to the second embodiment, in which 501 is a small hole nozzle, 502 is a large hole nozzle, 503 is a threshold wall, and
Reference numeral 04 is a small heater, 505 is a large heater, and 506 is an ink flow path. In the first embodiment, two ejection ports, a small hole nozzle and a large hole nozzle, are arranged so as to be perpendicular to the longitudinal direction of the ink flow path and perpendicular to the arrangement direction of the plurality of ink flow paths. However, in the present embodiment, the small hole nozzles 5 are arranged in the direction parallel to the arrangement direction of the plurality of ink flow paths 506.
01 and the large hole nozzle 502 are arranged side by side, and the generation and flight states of ink droplets in the recording head are the same as in the first embodiment. In this case, the ink flow path 5
Since 06 becomes large in the nozzle arrangement direction, the nozzle pitch becomes large and it is disadvantageous for printing with high resolution, but the nozzle configuration is simpler than the first embodiment and is advantageous in manufacturing.

[0023]

As described above, the present invention is an ink jet recording head in which two heaters are provided in one ink flow path, and two discharge ports having different opening areas corresponding to the respective heaters are provided in the ink flow path. By providing the two heaters individually or simultaneously, the ejection speeds can be stabilized to be substantially the same, and the ejection amount difference can be increased, so that multi-value recording or printing with various resolutions can be performed. There is an effect that can be. Further, when the ejection speed is very slow, the ejection stability becomes poor and the printed image is remarkably deteriorated due to the deviation of the ink droplets, but the ejection speed of the present invention is 10
Since m / s or more is possible, there is an effect that image deterioration does not occur.

Further, according to the present invention, since the threshold wall is provided between the two discharge ports having different opening areas,
In order to separate the two discharge ports and to further strengthen the separation, a small protrusion is provided on the lower surface of the threshold wall, so that the ink liquid from the large hole when driving the small heater and from the small hole when driving the large heater respectively. The effect is that no drops are ejected.

Further, according to the present invention, since the opening angle of the ejection port is adjusted so that both the large drop and the small drop land at substantially the same position on the recording medium, the ejection speed is almost the same, so that the large drop is This has the effect that the landing points of small drops do not shift.

By arranging the two ejection openings so as to be perpendicular to the longitudinal direction of the ink flow path and perpendicular to the direction in which the plurality of ink flow paths are arranged, the two ejection openings can be arranged without increasing the nozzle pitch. There is an effect that a discharge port can be provided and high-resolution printing can be performed.

By arranging the two ejection ports in the direction parallel to the direction in which the plurality of ink flow paths are arranged, there is an effect that the nozzle pitch is increased but the nozzle structure is simplified.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of an inkjet nozzle according to a first embodiment of the present invention.

FIG. 2 is an overall schematic configuration diagram of a recording head of the inkjet recording apparatus according to the first embodiment.

FIG. 3 is a graph showing the relationship between the ejection amount and the ejection speed of droplets ejected from a nozzle with the ejection opening area as a parameter in the inkjet recording apparatus.

FIG. 4 is a conceptual diagram showing a state of generation and flight of ink droplets in the recording head of the first embodiment. [a] Shows the state when only the small heater is driven. [b] Shows the state when only the large heater is driven. [c] Shows the state when a small heater and a large heater are driven simultaneously.

FIG. 5 is an overall schematic configuration diagram of a recording head of an inkjet recording apparatus according to a second embodiment of the present invention.

FIG. 6 is an overall schematic configuration diagram of a recording head of a conventional inkjet recording apparatus.

[Explanation of symbols]

101, 401, 501 small hole nozzle 102, 402, 502, 602 large hole nozzle 103, 503 threshold wall 104, 404, 504, 604 small heater 105, 405, 505, 605 large heater 106, 506, 606 ink flow path 107 small Projection portion 108 Projection (LC) 309 Ejection speed-ejection amount relationship line (S ₀ 680) 310 Ejection speed-ejection amount relationship line (S ₀ 300) 411 Small bubble 412 Small drop 413 Recording medium 414 Large bubble 415 Large drop

Claims (10)

[Claims] 1. A recording is performed by disposing a heater in an ink flow path in a nozzle of a recording head and heating the heater to eject ink droplets from a discharge port at the tip of the ink flow path. In a recording head of an inkjet recording device, a heater having two different areas in the ink flow path,
A recording head of an ink jet recording apparatus, comprising: the heater and two ejection openings having different opening areas corresponding to each other. 2. The recording head of the ink jet recording apparatus according to claim 1, wherein a plurality of the ink flow paths are arranged in parallel. 3. The recording head of the ink jet recording apparatus according to claim 2, wherein the recording head is perpendicular to the longitudinal direction of the ink flow path and perpendicular to the direction in which the plurality of ink flow paths are arranged. ,
A recording head of an ink jet recording apparatus, wherein the two ejection ports are arranged side by side. 4. The recording head of the inkjet recording apparatus according to claim 2, wherein the recording head is parallel to a direction in which the plurality of ink flow paths are arranged.
A recording head of an ink jet recording apparatus, wherein the two ejection ports are arranged side by side. 5. The recording head of an ink jet recording apparatus according to claim 1, wherein the ink has a small hole having a small opening area and a large hole having a large opening area. A recording head of an ink jet recording apparatus, wherein a threshold wall is provided between the flow path side openings. 6. The recording head of the ink jet recording apparatus according to claim 3 or 5, wherein the small hole, which is a heater having a small area, is arranged below the threshold wall. And a large heater, which is a heater having a large area, is arranged apart from the small heater and the threshold wall in the direction opposite to the ejection port. 7. The recording head of the ink jet recording apparatus according to claim 6, wherein a protrusion is provided on the lower surface of the threshold wall at a position corresponding to between the small heater and the large heater. And a recording head of an inkjet recording device. 8. The recording head of the ink jet recording apparatus according to claim 4 or 7, wherein two ink droplets ejected from the two ejection ports are ejected so as to have substantially the same landing point on the recording medium. A recording head of an inkjet recording apparatus, wherein an opening angle of an outlet is set. 9. An ink jet recording apparatus comprising a recording means for recording by ejecting ink according to a signal, wherein the recording head according to any one of claims 1 to 8 is used. Characteristic inkjet recording device. 10. The recording method for a recording head of an ink jet recording apparatus according to claim 9, wherein the two heaters are selectively heated according to a signal of image information to be recorded, and bubbles generated are generated. A recording method for a recording head of an ink jet recording apparatus, characterized in that droplets having different sizes are ejected from ejection ports having corresponding opening areas so that the droplets land on the recording medium at substantially the same speed. .