JP2008149673A - Recording head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recording head of a high density and a long size, for which a foaming pressure of an ink, which can correspond to the full multiplication, and an air stream are used. <P>SOLUTION: In a recording apparatus which performs recording by discharging a liquid ink toward a recording medium, this recording head has a heater board, a plurality of ink discharging ports 5, and a plurality of air discharging ports 7. In this case, on the surface of the heater board, a plurality of heating elements are installed at least in one row. The plurality of ink discharging ports 5 are installed to be confronted with the heating elements on the heating board. The plurality of air discharging ports 7 are installed to be confronted with the ink discharging ports. Then, the equivalent diameter of the air discharging port is set to be 50 μm or lower. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a configuration of a recording head in an ink jet recording apparatus.

Proposals for increasing the ink droplet velocity and gradation by using air flow in ink jet recording in combination with, for example, a piezoelectric ink jet, Japanese Patent Laid-Open No. 52-82426, Japanese Patent Laid-Open No. 57-115354, and a thermal ink jet JP-A-5-201031 and JP-A-5-104716 in combination with electrostatic ink jet are well known.
JP-A-52-82426 JP 57-115354 A JP-A-5-201031 JP-A-5-104716

  However, these proposals could only deal with single nozzles or at most multi-nozzles. The high density (for example, 600 dpi or more) essential for future high speed inkjet printers and the full multi-head for the paper width (for example, 8 inches to 12 inches) have not been very compatible.

  Accordingly, an object of the present invention is to provide a novel recording head using an air flow that is compatible with a high-density and long full multi-head.

  In a recording apparatus that performs recording by discharging liquid ink toward a recording medium, a heater substrate having a plurality of heating elements provided on at least one row on the surface, and a plurality of heater substrates provided on the heater substrate so as to face the heating elements And a plurality of air discharge ports provided opposite to the ink discharge ports, and the equivalent diameter of the air discharge ports is 50 μm or less.

  According to the present invention, it is possible to provide a recording head that uses high-density and full-multi ink ink foaming pressure and air flow.

  1 is a plan view showing a head according to an embodiment of the present invention, FIG. 2 is an enlarged sectional view taken along the line AA, FIG. 3 is a sectional view taken along the line BB in FIG. 2, and FIG. It is.

  As shown in FIG. 1, 5 heads are arranged in a line at a pitch p = 42.3 μm (600 dpi), the effective length L of the head is about 600 mm (12 inches), and a total of 7200 5s are arranged. The width W of the head is about 20 mm. The configuration will be described in more detail with reference to FIG. 2. 1 is a head base made of plastic injection molding or ceramic, 2 is a silicon heater substrate, 3 is a heating element made on the surface of the heater substrate 2, 4- 1, 4-2 and 4-3 are bumps formed on the surface of 2, 5 is an ink discharge port, 6 is an ink discharge port member, 7 is an air discharge port, 8 is an air discharge port member, and 9 is a driving IC chip. Reference numeral 10 denotes an FPC (flexible printed circuit board). The head substrate 1 has a liquid chamber 11, an ink inlet 12, an air chamber 13, an air inlet 14, the heater substrate 2 has an ink inflow hole 15, an air inflow hole 16, and the ink discharge hole member 6 has an ink distribution channel 17. The air discharge hole member 8 is provided with an air distribution flow path 18. The ink inlet 12, liquid chamber 11, ink inlet 15, ink distribution channel 17, and ink outlet 5 are filled with ink 19, and the air inlet 14, air chamber 13, air inlet 16, air distribution flow An air flow 20 flows through the path 18 and the air discharge port 7.

  In the configuration of FIG. 2, a drive signal from a main body (not shown) is given to the bump 4-3 through the FPC 10, and a signal flows from the bump 4-2 to the drive IC chip 9. The output from the driving IC chip 9 is applied to the heating element 3 via the bump 4-1, and the heating element 3 generates heat to a predetermined temperature, whereby the ink 19 in the ink distribution flow path 17 boils and the pressure of the ink 19 is increased. The ink is ejected from the ink ejection port 5 and flies toward a recording medium (not shown) on the air flow 20 flowing out through the air ejection hole 7 to perform recording.

  The operation will be described in more detail with reference to FIG. FIG. 5A shows a non-ejection state. The ink 19 forms a meniscus on the surface of the ink ejection port 5, and the air flow 20 flows through the air ejection port 7 at a constant speed. In FIG. 5B, when a predetermined drive pulse is applied to the heating element 3 and the heating element 3 generates heat, the ink 19 boils and a bubble 21 is generated. With the pressure of 21, the ink 19 becomes an ink droplet 22 and starts to be ejected from the ink ejection port 5, and is accelerated while being pushed by the air flow 20. After being driven, the heating element 3 cools and 21 starts to contract, but 22 is accelerated by the inertia and the air flow 20 and is ejected from the ink ejection port 5. It should be noted here that in this embodiment, the space between the heating element 3 and the ink discharge port 5 is extremely narrow and the volume thereof is small, so that almost all the ink 19 facing the heating element 3 flies as 22. It is. As a result, the surface of the heating element 3 communicates with the atmosphere through the ink discharge holes 5.

  Next, the air discharge port of the present invention will be described. Examples of the head of the embodiment described in FIGS. 1 to 5 with the equivalent diameter of the air discharge port 7 (diameters when various shapes such as squares are considered as equivalent circles having the same area) are used, When the conventionally proposed air outlets were examined including the slits, the results shown in FIG. 7 were obtained. Therefore, the air discharge port equivalent diameter da suitable for a high density and long full multi is much smaller than previously proposed da ≦ 50 μm, more preferably da ≦ 30 μm, particularly when the ink droplet is 4 pl or less. It was found that ≦ 20 μm. Further, it was found that the distance (air layer thickness) ha between the ink ejection port 5 and the air ejection port 7 is also ha <20 μm, more desirably ha <15 μm, and when the ink droplet is 4 pl or less, ha <10 μm is desirable. Table 1 shows that the ink droplet velocity is low, indicating that the air flow hardly accelerates. The large amount of required air is a large multi-printer with 7000 nozzles that consumes too much air and is large and noisy. Indicates that a pump is required.

  FIG. 8 shows the relationship between the equivalent diameter da of the air discharge hole of the present invention and the equivalent diameter dh of the heating element. From this result, it can be seen that if the equivalent diameter da of the air discharge hole and the equivalent diameter dh of the heating element are 0.5 * dh ≦ da ≦ 2 * dh, the ink droplets are stably accelerated and have an airflow effect. Furthermore, if 0.8 * dh ≦ da ≦ 1.5 * dh, more stable ejection is possible. If the equivalent diameter da of the air discharge hole is too small, the ink droplets are pulverized and splashed as a splash when passing through the air discharge port. Drop acceleration is not performed. As described above, since most of the ink on the front surface of the heating element 3 is ejected from the ink ejection port 5, the amount of the ejected ink droplet 22 is determined regardless of the size of the ink ejection hole 5. It will be understood that there is a close optimal relationship between the equivalent diameter dh of the body and the equivalent diameter da of the air outlet.

FIG. 6 shows a method for manufacturing the recording head of the present invention.
Step (a)
A predetermined insulating film or the like is formed on the surface of the heater substrate 2, and the heating element 3, the bump 4-1, the bump 4-2, the bump 4-3, and the like are formed. A protective film is formed on the surface of the heating element 3 as necessary.
Step (b)
A positive photosensitive resin 31 is applied, exposed, and patterned as a mold material for a portion of the flow path such as the ink distribution flow path 17.
Step (c)
A negative photosensitive resin 32 to be the ink discharge hole member 6 is applied and exposed.
Step (d)
A positive photosensitive resin 33 is applied, exposed, and patterned as a mold material for a portion that constitutes a flow path such as the air distribution flow path 18.
Step (e)
A negative photosensitive resin 34 to be the air discharge hole member 8 is applied and exposed.
Step (f)
The negative photosensitive resin 32 and the negative photosensitive resin 34 are etched and patterned. At this time, an air discharge hole 7 is also formed.
Step (g)
An ink inflow hole 15 and an air inflow hole 16 are formed in the heater substrate 2 by anisotropic etching.
Step (h)
The positive photosensitive resin 33 and the positive photosensitive resin 31 are removed with an etching solution, and the ink distribution flow path 17 and the air distribution flow path 18 are formed.
Step (i)
The ink discharge hole 5 and the air flow path 35 of the negative photosensitive resin 32 are etched.
Step (j)
The driving IC chip 9 and the FPC 10 are electrically connected by the ACF. Further, the head body 1 made of alumina or noryl is bonded to complete the head body.

  As can be seen from the above embodiments, since an important part of the head is manufactured by the photo process in this embodiment, the equivalent diameter da of the air discharge holes, the equivalent diameter di of the ink discharge holes, the equivalent diameter dh of the heating element, and the air layer thickness ha. In addition, an ink discharge hole height hI can be made with extremely high accuracy, and a high-density long full multihead using an air flow can be provided.

  A line printer using a full multi has to form an image in one pass, and a method for obtaining high image quality in a multi pass like a serial printer cannot be used. Therefore, although there is a strict requirement for density unevenness and landing accuracy of each nozzle, sufficient quality can be obtained by using an air flow and a combination of a thermal head that discharges all ink on the front surface of the heating element.

It is a top view which shows the head of the Example of this invention. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG. It is CC sectional drawing of FIG. It is a schematic cross section which shows operation | movement of this invention. It is a schematic diagram showing a manufacturing process of the recording head of the present invention. It is a table | surface which shows the relationship between the equivalent diameter da of the air discharge port of this invention, and structures, such as a slit of an air discharge port. It is a table | surface which shows the relationship between the equivalent diameter da of the air discharge port of this invention, and the equivalent diameter dh of a heat generating body.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Head base | substrate 2 Heater board | substrate 3 Heat generating body 4-1, 4-2, 4-3 Bump 5 Ink ejection port 6 Ink ejection port member 7 Air ejection port 8 Air ejection port member 9 Drive IC chip 10 FPC
DESCRIPTION OF SYMBOLS 11 Liquid chamber 12 Ink inlet 13 Air chamber 14 Air inlet 15 Ink inlet hole 16 Air inlet hole 17 Ink distribution channel 18 Air distribution channel 19 Ink 20 Air stream 21 Bubble 22 Ink droplet

Claims (5)

  In a recording apparatus that performs recording by discharging liquid ink toward a recording medium, a heater substrate having a plurality of heating elements provided on at least one row on the surface, and a plurality of heater substrates provided on the heater substrate so as to face the heating elements And a plurality of air discharge ports provided opposite to the ink discharge ports, and an equivalent diameter of the air discharge ports is 50 μm or less.   The recording head according to claim 1, wherein an equivalent diameter of the air ejection port is 30 μm or less, and a distance between the ink ejection port and the air ejection port is 20 μm or less. In a recording apparatus that performs recording by discharging liquid ink toward a recording medium, a heater substrate having a plurality of heating elements provided on at least one row on the surface, and a plurality of heater substrates provided on the heater substrate so as to face the heating elements And a plurality of air discharge ports provided opposite to the ink discharge ports, and the equivalent diameter da of the air discharge port and the equivalent diameter dh of the heating element are
0.5 * dh ≦ da ≦ 2 * dh
A recording head characterized by satisfying   The recording head according to claim 1, wherein an interval between the ink ejection port and the air ejection port is 10 μm or less. The equivalent diameter da of the air discharge port and the equivalent diameter dh of the heating element are
0.8 * dh ≦ da ≦ 1.5 * dh
The recording head according to claim 1, wherein the recording head is a recording head.

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