JP2009137022A - Inkjet recording head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress temperature rise of a head because of speed-up of recording and densification for reducing density irregularities of an image caused by a temperature difference in a delivering opening array. <P>SOLUTION: The inkjet recording head makes a thermal resistance in a direction to separate from a recording element substrate to a supporting part at the supporting part between the recording element substrate 21 and a supporting plate 10 different between a central region in the delivering opening arrays 51 and 52 direction and an end region. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ink jet recording head that performs a recording operation by discharging ink.

  The ink jet recording apparatus ejects ink from an ejection port of an ink jet recording head and deposits the ink on a recording medium to perform image recording, and can record a high-definition image at high speed.

  In recent years, it has become possible to record color images at a lower cost and in a smaller space by increasing the length and the number of rows of ejection port arrays formed on one recording element substrate.

  Such an ink jet recording head is shown in FIG. In this recording head, a plurality of recording element substrates having a large number of ejection port arrays are arranged in a staggered pattern on a single support plate, and a plurality of these arrays are arranged to correspond to the entire width of the recording medium. This is a full line type ink jet recording head in which a discharge port array is formed.

  In the ink jet recording head of FIG. 5, six recording element substrates 21 to 26 each having two ejection port arrays 5 are bonded and fixed to the fixing surface 11 of the support plate 10 in a staggered arrangement. The heat generated in the recording element substrates 21 to 26 as the recording is performed is radiated to the outside via the support plate 10.

  The recording medium is conveyed in a direction orthogonal to the ejection port array 5 of the recording element substrates 21 to 26 while facing the fixed surface 11 by a conveying unit (not shown) from the left side to the right side in FIG. The When the recording medium passes directly below the recording head, first, ink droplets are ejected from the ejection port arrays of the odd-numbered recording element substrates 21, 23, 25 to form dots on the recording medium. Next, ink droplets are ejected from the ejection port arrays of the even-numbered recording element substrates 22, 24, and 26 so as to complement the gaps, thereby forming dots on the recording medium. By repeating the same operation, image recording is executed. The odd-numbered recording element substrates and the even-numbered recording element substrates overlap each other by a certain amount, and the image of the overlapped portion is subjected to a complementary process to maintain image quality.

  FIG. 6 is a view of the support plate 10 of FIG. 5 as seen from the surface opposite to the surface on which the recording element substrate is disposed. Ink is supplied from an ink tank (not shown) to the corresponding recording element substrates 21 to 26 through the ink supply paths 111, 121, 131, 141, 151, and 161, respectively. Two ejection port arrays are arranged on both sides of one ink supply port, and one ink supply path is provided on one printing element substrate.

  FIG. 7 is a schematic diagram illustrating the recording element substrate 21. FIG. 7A is a plan view of the side on which the discharge port array is arranged, FIG. 7B is a cross-sectional view taken along the line AA in FIG. 7A, and FIG. It is BB sectional drawing of (a).

  Two rows of ejection port arrays 51 and 52 are formed on the recording element substrate 21, and the ink supply port 41 is shared as a pair. Ink is supplied through an ink supply path 111 provided in the support plate 10. The ink supplied to the ejection port arrays 51 and 52 receives thermal energy generated by a pulse signal applied to the heaters 61 and 62 and is ejected from the ejection ports.

A recording medium (not shown) is conveyed from the ejection port array 52 side, and a recording image is formed by overlapping ink droplets in the order of the ejection port arrays 52 and 51 on the recording medium.
The same applies to the other recording element substrates 22 to 26.
JP 2003-305853 A

  In the case of an ink jet recording head having such a structure, heat is likely to be trapped in the central portion of the ejection port array, and there is a risk of preventing soaking in the recording element substrate.

  The heat generated by the heaters 61 and 62 is diffused avoiding the ink supply port 41 and transmitted to the support plate 10. Therefore, the heat generated by the heaters of the ejection port arrays 51 and 52 is transmitted to the support plate 10 from both ends of the long side of the recording element substrate.

  On the other hand, in addition to the heat generated by the heaters near the ends of the ejection port arrays 51 and 52 being transmitted from both ends on the long side of the recording element substrate to the support plate 10, it is also supported from the ends on the short side of the recording element substrate. It is transmitted to the board 10. Therefore, the temperature rise at the end of the discharge port array is suppressed as compared with the center, and a temperature difference occurs at that position in the discharge port array.

  In general, the higher the temperature of the recording element substrate, the greater the amount of ink discharged. Therefore, if there is a temperature difference between the positions of the discharge ports, there will also be a difference in the ink discharge amount. Therefore, when the temperature difference in the ejection port array as described above occurs, there is a problem that the density of the image is uneven and the image quality is adversely affected.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an ink jet recording head that improves the soaking characteristic of a recording element substrate and reduces the density unevenness of an image due to the temperature difference in the ejection port array.

  The present invention that achieves the above-described object provides an inkjet recording head comprising: a recording element substrate having an ejection port array for ejecting ink; and a support plate that supports the recording element substrate. The thermal conductivity of the fixing surface fixed to the support plate at the center in the arrangement direction of the discharge port array is made higher than the thermal conductivity at the end in the arrangement direction of the discharge port array.

  According to another aspect of the present invention, there is provided an ink jet recording head comprising: a recording element substrate having an ejection port array for ejecting ink; and a support plate for supporting the recording element substrate. Fixed to the fixed surface of the plate by bonding, and on the fixed surface, at least one side of the recording element substrate or the support plate, other than the central portion in the arrangement direction of the plurality of ejection port arrays, On the other hand, a groove is formed in a direction away from the recording element substrate, and the groove is filled with an adhesive when the recording element substrate is fixed to the fixing surface.

  According to the present invention, it is possible to provide an ink jet recording head that improves the soaking characteristic of the recording element substrate and reduces the density unevenness of the image due to the temperature difference in the ejection port array.

(First embodiment)
FIG. 1 is a diagram illustrating a recording element substrate 21 that is bonded and fixed to a support plate 10 of an ink jet recording head according to a first embodiment of the present invention. 1A is a plan view of the side on which the ejection port array is arranged, FIG. 1B is a cross-sectional view taken along the line AA in FIG. 1A, and FIG. It is BB sectional drawing of (a). The basic external application configuration of the ink jet recording head is the same as that shown in FIGS.

  In FIG. 1, ejection port arrays 51 and 52 are formed on the recording element substrate 21 on the surface opposite to the ink supply side. The ejection port arrays 51 and 52 form a pair and share the ink supply port 41, and ink is supplied through an ink supply path 111 provided in the support plate 10. The ink supplied to the ejection port arrays 51 and 52 is ejected from the ejection ports by thermal energy generated by a pulse signal applied to the heaters 61 and 62.

The portions 101 and 102 on both sides of the ink supply path 41 of the support plate 10 are made of a material having a higher thermal conductivity than the other portions of the support plate 10. For example, the support plate 10 is formed of alumina (Al ₂ O ₃ , thermal conductivity: 32 W / mK). The portions 101 and 102 on both sides of the ink supply path 41 of the support plate 10 are made of high thermal conductivity such as aluminum nitride (AlN, thermal conductivity: 170 W / mK) or silicon carbide (SiC, thermal conductivity: 220 W / mK). Made of a ceramic material.

On the other hand, in the fixed surface (adhesive surface) 11 of the recording element substrate 21 to the support plate 10, the thermal conductivity is higher at both ends in the arrangement direction of the ejection port array than in other parts including the central portion in the arrangement direction of the ejection port array. The high thermal resistance layers 81 to 84 are formed of a low material. The high thermal resistance layers 81 to 84 may be formed on at least one of the recording element substrate 21 side and the support plate 10 side on the surface (fixed surface) where the recording element substrate 21 and the support plate 10 are in contact. In this way, the thermal conductivity of the fixed surface 11 from the center in the arrangement direction to the end in the arrangement direction is at the end in the arrangement direction of the ejection port array on at least one side of the recording element substrate 21 or the support plate 10. Low materials are arranged. At the same time, the thermal conductivity at the center in the arrangement direction of the discharge port array is made higher than the thermal conductivity at the end in the arrangement direction of the discharge port array. As a method of forming the high thermal resistance layers 81 to 84, for example, a silicon oxide layer 81 (SiO ₂ , thermal conductivity: 3 W / _second ) is formed on the bonding surface of the recording element substrate 21 formed of silicon (Si, thermal conductivity: 148 W / mK). mK) is formed by surface modification treatment by implanting oxygen ions. In addition, it can also form by a vacuum evaporation process. The thermal conductivity of the high thermal resistance layer is changed in steps from 81 to 84, and the high thermal resistance layer 81 has the lowest thermal conductivity. The high thermal resistance layers 81 to 84 are also formed so as to surround both ends of the discharge port arrays 51 and 52.

  When recording is performed using the recording element substrate 21 of the present embodiment, the heat generated by the heaters 61 and 62 is transferred to the high thermal conductivity portions 101 and 102 of the support plate 10 through the bonding portion in the long side direction of the recording element substrate. . Thus, since the heat generated by the central heater diffuses through the same path, there is almost no temperature difference at the central portion in the direction of the discharge port array.

  On the other hand, at both ends of the ejection port array, thermal diffusion occurs in the recording element substrate long side direction as well as in the central part, and thermal diffusion also occurs in the recording element substrate short side direction. In the present embodiment, the thermal diffusion in the short side direction is suppressed by the high thermal resistance layer 81. Further, in the heat generated from the heater slightly inside the shortest portion of the ejection port array, the diffusion amount diffusing to the long side portion of the recording element substrate is gradually suppressed by the high thermal resistance layers 82 to 84.

  FIG. 2 is a graph showing the temperature distribution in the discharge port array direction. A line 91 indicates a conventional example, and a line 92 indicates a state after the present embodiment is implemented. As is clear when the two are compared, the temperature drop at both ends is improved.

  As described above, with the configuration shown in the present embodiment, the temperature of the ejection port arrays 51 and 52 can be made uniform including the end of the ejection port array, and the uneven density of the image on the recording element substrate can be eliminated. Thus, the image quality can be improved.

  Although a part of the support plate 10 is made of a high conductivity material, the same material may be used for all. Even in that case, it is possible to make the temperature distribution of the discharge port array uniform by adjusting the thermal conductivity of the high resistance layers 81 to 84. However, it must be noted that if the thermal conductivity of the support plate 10 is low, the exhaust heat efficiency of the entire recording element substrate is lowered, and the temperature of the recording element substrate is increased.

  It is also possible to increase the thermal resistance of the bonded portion by shortening the long side and the short side of the recording element substrate 21 to reduce the area of the bonded portion between the high thermal resistance layers 81 to 84 and the support plate 10. However, due to the relationship between the allowable limit of the positioning error of the recording element substrate 21 with respect to the support plate 10 and the adhesive strength limit, there is a risk in reducing the area of the adhesive portion. It is desirable to deal with by increasing the thickness.

(Second Embodiment)
FIG. 3 is a diagram for explaining the recording element substrate 21 that is bonded and fixed to the support plate 10 of the ink jet recording head according to the second embodiment of the present invention. 3A is a plan view of the side on which the discharge port array is arranged, FIG. 3B is a cross-sectional view taken along the line AA in FIG. 3A, and FIG. It is BB sectional drawing of (a). The basic external application configuration of the ink jet recording head is the same as that shown in FIGS.

  Further, in this embodiment, grooves 85 to 88 are provided on the bonding surface (fixed surface) of the recording element substrate 21 instead of the high thermal resistance layer, and in other configurations, a part of the support plate 10 is made of the same material as other portions. It is the same as that of 1st Embodiment except having comprised.

  The recording head of the present embodiment has a recording element with respect to the fixed surface at a portion other than the central portion in the arrangement direction of the plurality of ejection port arrays on at least one side of the recording element substrate 21 or the support plate 10 on the fixed surface 11. Grooves 85 to 88 are formed in a direction away from the substrate 21. When the recording element substrate 21 is fixed to the fixing surface 11, the grooves 85 to 88 are filled with an adhesive.

  In FIG. 3, grooves 85 to 88 are formed stepwise at both ends of the fixing surface 11 of the recording element substrate 21 with the support plate 10, one step below the other portions. The grooves 85 to 88 are formed by, for example, an etching process that is masked by photolithography.

  The adhesive flows into the grooves 85 to 88 when the recording element substrate 21 is bonded and fixed to the support plate 10. The edges of the grooves 85 to 88 are all flush with the bonding surface of the recording element substrate so that the adhesive flowing into the grooves 85 to 88 does not protrude into the ink supply path or around the recording element substrate. The cured adhesive has an extremely low thermal conductivity of, for example, 1.0 W / mK with respect to the recording element substrate 21 formed of silicon (Si, thermal conductivity: 148 W / mK) or the like. Therefore, the adhesive collected in the grooves 85 to 88 functions as a high heat resistance layer.

  When recording is performed on the recording element substrate 21 configured as described above, the heat generated by the heaters 61 and 62 is transmitted to the support plate 10 through the adhesive portion in the long side direction of the recording element substrate 21.

  On the other hand, at both ends of the ejection port array, thermal diffusion occurs in the short side direction of the recording element substrate 21 in addition to thermal diffusion in the long side direction of the recording element substrate 21 as in the central portion. . In the second embodiment, the thermal diffusion in the short side direction is mainly suppressed by the high thermal resistance layer 85. Further, in the heat generated from the heater slightly inside the shortest portion of the ejection port array, the amount of diffusion that diffuses to the long side portion of the recording element substrate is gradually suppressed by the high thermal resistance layers 86 to 88.

  As described above, with the configuration shown in the present embodiment, the temperature of the ejection port arrays 51 and 52 can be made uniform including the end of the ejection port array, and a recording element having a plurality of ejection port arrays. It is possible to eliminate image density unevenness on the substrate and improve image quality.

  In this embodiment, the grooves 85 to 88 are provided on the adhesive surface of the recording element substrate, but equivalent ones may be provided on the adhesive surface of the support plate 10. This groove may be provided at least on one of the bonding surface of the recording element substrate and the support plate. In this case, the groove can be formed by electric discharge machining or die molding in addition to cutting.

(Third embodiment)
In the present embodiment, as shown in FIG. 4, the heat pipes are located along both sides of the recording element substrates 21, 23, and 25 in the arrangement direction and both sides of the recording element substrates 22, 24, and 26 in the arrangement direction. As described above, the heat pipes 31, 32, 33 are arranged inside the support plate 10. In other words, the heat pipes are arranged on the support plates on the side of each row along the discharge port row arrangement direction of each printing element substrate.

  According to the present embodiment, since the heat pipes extend laterally along the arrangement direction of the discharge port arrays, the temperature difference between both ends of the discharge port arrays and the central portion of the discharge port arrays can be reduced.

  The effects of the first and second embodiments can be further increased by applying the heat pipe arrangement configuration of the present embodiment to the support plate of the ink jet recording head of the first and second embodiments described above. Can do.

FIG. 3 is a diagram illustrating a recording element substrate of the ink jet recording head according to the first embodiment of the present invention. 2 is a graph showing a temperature distribution in a discharge port array direction between the recording head of FIG. 1 and a conventional recording head. It is a figure explaining the recording element board | substrate of the inkjet recording head which concerns on the 2nd Embodiment of this invention. It is a figure explaining the recording element board | substrate of the inkjet recording head which concerns on the 3rd Embodiment of this invention. It is a perspective view explaining the inkjet recording head of a prior art example. It is the figure which looked at the support plate of FIG. 5 from the surface on the opposite side. FIG. 6 is a schematic diagram illustrating the recording element substrate in FIG. 5.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Support plate 21-26 Recording element board | substrate 31-33 Heat pipe 41 Ink supply port 51,52 Ejection port row | line | column 61,62 Heater 81-84 High thermal resistance layer 85-88 Groove | channel 111 Ink supply path

Claims (7)

In an inkjet recording head comprising: a recording element substrate having an ejection port array for ejecting ink; and a support plate for supporting the recording element substrate.
The thermal conductivity at the center in the arrangement direction of the ejection port array of the fixing surface for fixing the recording element substrate to the support plate is made higher than the thermal conductivity at the end in the arrangement direction of the ejection port array. Inkjet recording head.   The arrangement direction end from the arrangement direction center to the arrangement direction end of the ejection port array on at least one side of the recording element substrate or the support plate on the fixing surface for fixing the recording element substrate to the support plate. The ink jet recording head according to claim 1, wherein a material having a low thermal conductivity is disposed toward the portion.   3. The ink jet recording head according to claim 1, wherein the thermal conductivity is changed stepwise so that a temperature difference in the arrangement direction of the ejection port arrays is minimized.   2. The recording element substrate is arranged in a plurality of rows on the support plate, and heat pipes extend inside the support plate along the row direction on both sides of each row. 4. The ink jet recording head according to any one of items 1 to 3. In an inkjet recording head comprising: a recording element substrate having an ejection port array for ejecting ink; and a support plate for supporting the recording element substrate.
The recording element substrate is fixed to the fixing surface of the support plate by bonding, and at least one side of the fixing element on the recording element substrate or the support plate is other than the central portion in the arrangement direction of the plurality of ejection port arrays. A groove is formed in a part in a direction away from the recording element substrate with respect to the fixed surface, and the groove is filled with an adhesive when the recording element substrate is fixed to the fixed surface. Inkjet recording head.   6. The ink jet recording head according to claim 5, wherein the thermal conductivity is changed stepwise so that the temperature difference in the arrangement direction of the ejection port arrays is minimized.   7. The recording element substrate is arranged in a plurality of rows on the support plate, and heat pipes extend inside the support plate along the row direction on both sides of each row. 2. An ink jet recording head according to 1.

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