JP2005225147A - Liquid droplet jet head, ink cartridge, and inkjet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid droplet jet head capable of preventing thermal expansion occurring in the assembling of the liquid droplet jet head, and lowering of recording quality or breaking of the head caused by the thermal expansion of the head itself due to heat from a heating element generated during the recording by using the head. <P>SOLUTION: This liquid droplet jet head comprises a substrate 1 having an ink channel 9, a nozzle hole 8 and a pressure generating means 2 provided to a wall face forming the ink channel 9, and a base plate holding the substrate 1. A stress absorbing means for absorbing a stress generated on the substrate 1 or the base plate is formed on the head. The stress absorbing means comprises a quadrangular pyramid shaped recessed section and a recessed section 4 such as a groove having a triangular cross section. A plurality of stress absorbing means are provided along a through-groove 3 for supplying ink to the ink channel 9. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a droplet discharge head, an ink cartridge, and an ink jet recording apparatus, and more particularly, a droplet discharge head in which stress relaxation means for absorbing stress generated in a substrate or base plate on which the droplet discharge head is formed is formed. The present invention also relates to an ink cartridge and an ink jet recording apparatus equipped with this droplet discharge head.

  Inkjet recording, in which image recording is performed using ink droplets, has a feature that a printing mechanism is simple and a compact recording apparatus with low noise can be provided at low cost. In particular, as disclosed in Patent Document 1, a so-called side shooter type ink jet head that discharges liquid droplets in a direction perpendicular to a substrate on which pressure generating means is mounted can be configured with a plurality of nozzles in one chip. In recent years, chips have become larger and longer in order to further increase the printing speed.

  Although ink jet recording has the advantages as described above, there are also disadvantages due to an increase in size and density. The ink jet recording head disclosed in Patent Document 2 has a through hole formed in a substrate on which a pressure generating means is formed by mechanical or chemical etching, and the through hole communicates with a pressure generating element on the surface. The ink is supplied through the mouth. However, in such a configuration, the area of the through hole in the chip increases with the increase in size and density of the chip, the rigidity of the chip decreases, the difference in expansion coefficient due to handling during assembly or thermal stress, etc. May cause cracking or deformation of the chip. In the ink jet recording head disclosed in Patent Document 3, a configuration has been proposed in which a beam structure is formed in the through hole to increase the rigidity of the chip as a countermeasure.

In addition, in the inkjet head disclosed in Patent Document 4, it is proposed that the base plate is made of a high heat conductive material of ceramic fired material, and heat generated by the chip is released to the base plate side to suppress the temperature rise of the head chip. ing. In addition, in the inkjet recording head disclosed in Patent Document 5, the base plate is made of two materials, and the base plate that is close to the thermal expansion coefficient of the substrate is used as the base plate that is directly joined to the substrate on which the pressure generating element is formed. Has proposed a structure that uses a material having a larger thermal expansion coefficient to enhance the heat dissipation effect.
Japanese Patent Application Laid-Open No. 06-320730 JP 09-314841 A JP-A-10-138478 JP 2000-190500 A JP 2000-351215 A

  However, although the inkjet recording head disclosed in Patent Document 3 can increase the rigidity of the chip to some extent, it has the same problem when a higher density and a longer length are required for the chip. Become. In particular, an inkjet recording head capable of full-color recording and recording simultaneously across the entire width of the recording medium is fragile even with slight vibration, and the chip warps even with a slight difference in expansion coefficient from the base substrate. There is a problem that desired recording quality cannot be obtained. This point is more serious in the case of a so-called thermal ink jet head in which the pressure generating means is composed of an electrothermal conversion element. In a thermal ink jet head, heat is easily accumulated because the ink is discharged by using the pressure when the ink itself generates heat to boil the ink and the bubbles grow.

  For this reason, in the case of a line printer type inkjet head, the generated heat is enormous and the chip is warped by the heat generated by itself, and the recording quality suddenly deteriorates during recording, resulting in white stripes and color unevenness. Or cracks due to the difference in thermal expansion coefficient from the base substrate, leading to head damage depending on the location. Moreover, although the heat dissipation effect is enhanced in the ink jet head disclosed in Patent Document 4, if the density and length of the nozzle are increased, the heat dissipation cannot catch up, and the same problem occurs.

  In addition, in the ink jet recording head disclosed in Patent Document 5, there is no concern about cracks due to a difference in expansion by using a material having a coefficient of thermal expansion close to the base plate, but the head accumulates heat, leading to ejection down. There is.

  The present invention has been made in view of the above-described problems of the prior art, and the recording quality is increased by the thermal expansion during assembly or the thermal expansion of the head itself due to the heat from the heating element generated during recording. An object of the present invention is to provide a liquid droplet ejection head that does not drop or the head is not damaged.

  The present invention has been made to solve the above-described problems, and the invention according to claim 1 forms a liquid flow path, a nozzle port communicating with the liquid flow path, and the liquid flow path. In a droplet discharge head comprising a substrate having pressure generating means on a wall surface and a base plate that holds the substrate, stress relaxation means for reducing stress generated on the substrate or the base plate is formed.

  According to a second aspect of the present invention, in the liquid droplet ejection head according to the first aspect, the stress relaxation means is formed on a surface of the substrate facing the wall surface having the pressure generating means.

  According to a third aspect of the present invention, in the liquid droplet ejection head according to the first or second aspect, the stress relaxation means includes a recess formed by etching the substrate.

  According to a fourth aspect of the present invention, in the droplet discharge head according to the third aspect, the depth of the recess is 1/15 or more of the thickness of the substrate.

  According to a fifth aspect of the present invention, in the liquid droplet ejection head according to any one of the first to fourth aspects, the stress relaxation means is formed on the base plate.

  The invention according to claim 6 is the liquid droplet ejection head according to any one of claims 1 to 5, wherein the contact area between the substrate and the base plate is 2/3 or less of the area of the substrate. To do.

  According to a seventh aspect of the present invention, in the liquid droplet ejection head according to any one of the first to sixth aspects, the pressure generating means is an electrothermal conversion element.

  The invention according to claim 8 is an ink cartridge on which the droplet discharge head according to any one of claims 1 to 7 is mounted.

  The invention according to claim 9 is an ink jet recording apparatus on which the droplet discharge head according to any one of claims 1 to 7 or the ink cartridge according to claim 8 is mounted.

  The invention according to claim 1 is a liquid droplet comprising a liquid channel, a nozzle port communicating with the liquid channel, a substrate having pressure generating means on a wall surface forming the liquid channel, and a base plate that holds the substrate. In the discharge head, stress relaxation means for relaxing the stress generated in the substrate or the base plate is formed. Therefore, the stress generated by the heat difference of the head itself or the expansion due to the heat supply from the outside can be relaxed. Damage or deterioration of recording quality can be prevented.

  According to the second aspect of the present invention, since the stress relaxation means is formed on the substrate having the pressure generating means, the stress generating means can be created in the same process in the process when the stress generating means is formed on the substrate. It is unnecessary, can reduce man-hours, and can provide an inexpensive and highly reliable head.

  In the invention of claim 3, since the stress relaxation means is formed by a recess formed by etching the substrate on which the pressure generating means is formed, the dimensional accuracy is good and an accurate recess structure is formed even in a minute region. This makes it possible to form an effective stress relaxation structure.

  In the invention of claim 4, since the depth of the recess is 1/15 or more of the thickness of the substrate, a more effective stress relaxation structure can be formed.

  In the invention of claim 5, since the stress relaxation structure is also formed on the base plate, the stress relaxation can be sufficiently performed.

  According to the sixth aspect of the present invention, since the bonding area between the substrate and the base plate is 2/3 or less of the substrate, the stress can be relaxed, and the head can be prevented from being damaged and the recording quality can be prevented from being lowered.

  According to the seventh aspect of the present invention, since the pressure generating means is an electrothermal conversion element, the pressure generating means itself generates heat and easily expands. However, since the stress generating structure is provided, the effect of the stress relaxing structure is exhibited.

  The invention of claim 8 is a head cartridge comprising a liquid discharge head in which the stress relaxation means according to any one of claims 1 to 7 is formed, and a liquid container for storing liquid to be supplied to the liquid discharge head. Therefore, the recording quality is high with high reliability.

  The invention according to claim 9 is a recording apparatus comprising the ink jet head according to claims 1 to 7 or the ink cartridge according to claim 8, so that the head is not damaged due to a difference in thermal expansion, recording unevenness or the like is not produced. Recording is possible.

  The present invention has been made in view of the problems of conventional droplet discharge heads, and is based on thermal expansion during assembly of the droplet discharge heads, or heating elements generated during recording using the droplet discharge heads. An object of the present invention is to provide a liquid droplet ejection head in which the recording quality is not deteriorated due to thermal expansion of the head itself due to heat, or the head is not damaged. A droplet discharge head comprising a nozzle port communicating with the liquid flow path, a substrate having pressure generating means on a wall surface forming the liquid flow path, and a base plate holding the substrate. A stress relaxation means for relaxing the generated stress is formed.

  Hereinafter, the present invention will be described based on the ink jet head, ink cartridge, and ink jet recording apparatus of the embodiments shown in FIGS.

FIG. 1 is a perspective view showing an ink jet head of Example 1, FIG. 2 is a cross-sectional view taken along line AA of the ink jet head shown in FIG. 1, and FIG. 3 is a back view of the ink jet head shown in FIG.
The ink jet head of Example 1 includes a substrate 1 on which pressure generating means 2 is formed, a nozzle port 8 formed on a nozzle plate 7, and an ink flow path in which an ink flow path 9 for guiding ink to the pressure generating means 2 is formed. And the substrate 6. The ink jet head of Example 1 is an example in which an electrothermal conversion element is employed as the pressure generating means 2, but is not limited to this. A voltage is applied between electrodes facing each other through a minute gap, and the potential difference is determined. The same can be realized with an electrostatic ink jet head or the like in which one electrode is displaced and ink is ejected by its restoring force.

In the ink jet head of Example 1, the through groove 3 is formed in the substrate 1 as means for supplying ink into the ink flow path 9, and the ink is supplied through the through groove 3. The substrate 1 is made of silicon single crystal having a plane orientation <100>, and the through grooves 3 are formed by performing anisotropic etching using SiO ₂ as a thermal oxide film, SiN film formed by plasma CVD, or the like as a mask material. In general, KOH, NaOH, TMAH, or the like is used as an etchant. In this example, anisotropic etching was performed at a temperature of 80 ° C. using a TMAH 22 wt% solution using SiO ₂ as a mask. In the anisotropic wet etching, the etching rate is extremely slow at the Si crystal plane <111>. When a substrate having a plane orientation <100> is used, the anisotropic wet etching is performed in the depth direction as shown in FIGS. An etched shape having a taper angle is obtained. Since the shape is almost determined by the formation accuracy of the mask material from the etching characteristics as described above, it is easy to control the dimensions.

  A stress relaxation mechanism including a plurality of recesses 4 is formed on the back surface of the substrate 1. The recess 4 can be formed simultaneously with the formation of the through groove 3 by etching the substrate 1, for example, by a quadrangular pyramid-shaped depression. The plurality of recesses 4 are provided at equal pitches on both sides of the through-groove 3 along the longitudinal direction of the through-groove 3, and the opening end size and depth of the quadrangular pyramid-shaped recess, the position provided on the substrate 1, etc. It is calculated in advance or determined by experiment.

The substrate 1 having the pressure generating means 2 is bonded to the base plate 10 as a strength member by an adhesive or the like.
4A and 4B are diagrams showing the relationship between the substrate and the base plate. FIG. 4A shows a state where no stress (stress) is generated on the substrate, and FIG. 4B shows a state where stress is generated on the substrate. The state of the state is shown.
In the inkjet head as shown in FIG. 4A, as shown in FIG. 4B, due to the heat generation of the substrate 1 itself or the supply of heat from the outside, due to the difference in expansion coefficient between the base plate 10 and the substrate 1, The base plate 10 is compressed in the direction of the arrow relative to the substrate 1, and stress is generated on the contact surface with the substrate 1. However, a columnar structure 5 formed by a plurality of recesses 4 is formed on the back surface of the substrate 1, and the portion functions as a stress relaxation mechanism, absorbs stress due to the expansion difference well, warps the substrate 1, and cracks. Occurrence is prevented.

FIG. 5 is a diagram showing the relationship between the recesses formed in the substrate and the opening width of the mask.
The recess 4 for absorbing stress was formed in the same manner by etching when the through groove 3 for supplying ink was formed. The depth of the recess 4 is substantially determined by the opening width of the mask m used during etching. When the opening width of the mask m is W, the depth H obtained by etching is H = W / √2
It is represented by

  In the ink jet head of Example 1, the opening width was set so that the depth H of the recess 4 was ½ of the thickness of the substrate 1. If the depth H of the recess 4 is too shallow, it does not function as stress relaxation. Therefore, as a result of examining the depth H that functions as stress relaxation, it was found that the function as a stress relaxation mechanism begins to be obtained from 1 / 15th of the thickness of the substrate 1. As a more effective value, the depth H of the recess 4 is set to ½ of the substrate.

FIG. 6 is a perspective view showing the bonding relationship between the substrate and the base plate.
The substrate 1 is bonded to the base plate 10 with an adhesive or the like, and the bonding area is adjusted to be 1/5 of the area of the substrate 1. This is because the stress relaxation function decreases when the bonding area is ½ or more. As a means for reducing the bonding area, the same effect can be obtained by providing the convex portion 11 on the base plate 10 and bonding the substrate 1 only at the convex portion 11 as shown in FIG.

  In the ink jet head of Example 1, as an example of forming the recess 4, the example using anisotropic wet etching has been described. However, the present invention is not limited to this, and sand blasting, laser, dicing, other machining and dry etching are used. Etc. can be substituted.

FIG. 7 is a back view of another inkjet head having different recesses that can achieve the same effect.
In the ink jet head shown in FIG. 7A, the recess 4 is a groove having a triangular cross section, and is provided along the through groove 3, and the edge of the substrate 1 orthogonal to the through groove 3 has a triangular cross section. A recess 4 made of a groove is provided.
In addition, in the ink jet head shown in FIG. 7B, in addition to the concave portion 4 provided in the ink jet head shown in FIG. 3, the small concave portion 4 is continuously provided at the edge of the substrate 1 orthogonal to the through groove 3. It has been.

FIG. 8 is a perspective view illustrating the ink jet head according to the second embodiment.
The ink jet head of Example 2 is a so-called side shooter type, and includes a nozzle 20, an ink flow path 21 communicating with the nozzle 20, a pressure generating means 22 formed on a part of the wall surface of the ink flow path 21, A common liquid chamber 23 for supplying ink to the ink flow path 21 and an ink supply port 24 for supplying ink to the common liquid chamber 23 are formed. The ink supply port 24 is formed on a substrate different from the substrate 1 on which the pressure generating means 22 is formed.

FIG. 9 is a rear view of the inkjet head shown in FIG.
Since no ink supply port is formed in the substrate 1, it is not necessary to form the concave portion 25 of the stress relaxation mechanism at a position avoiding the ink supply port 24 unlike the ink jet head of the first embodiment. Therefore, the recesses 25 each having an isosceles triangle-shaped cross section are provided at equal intervals over the entire back surface of the substrate 1. In particular, since stress is likely to occur in the longitudinal direction of the substrate 1, it is easy to reduce the stress.

FIG. 10 is a back view of another inkjet head having different concave portions that can achieve the same effect.
In the ink jet head shown in FIG. 10A, the recesses 25 each having a groove having an unequal triangular shape in cross section are provided at equal intervals over the entire back surface of the substrate 1.
In addition, the ink jet head shown in FIG. 10B is provided with a concave portion 25 formed of a groove having an isosceles triangular cross section across the entire back surface of the substrate 1.

FIG. 11 is a partially exploded perspective view illustrating the ink jet head according to the third embodiment.
In the ink jet head of Example 3, the base plate 31 is bonded to the ink jet head configured as in Example 1 or 2. A plurality of grooves 32 are formed in the base plate 31 at equal intervals by cutting at an appropriate pitch. The base plate 31 is made of aluminum having good thermal conductivity. Aluminum has a thermal expansion coefficient that is significantly different from that of silicon. However, the stress relaxation function works by the plurality of grooves 32, and the stress of the head can be released well. The base plate 31 having the above-described configuration is not limited to this, and a metal such as alumina, aluminum nitride, amorphous carbon, copper, nickel, SUS, or the like can be substituted. Furthermore, by forming a pattern similar to the pattern of the recess 33 formed on the substrate 1 so as to correspond to the base plate 31, the stress relaxation means becomes more effective. At this time, the contact area between the substrate 1 and the base plate is ½ or less of the area of the substrate 1.

FIG. 12 is a perspective view illustrating the liquid discharge head cartridge according to the fourth embodiment.
The ink jet head 48 as described in the first to third embodiments and the liquid container that holds the liquid supplied to the ink jet head 48 are integrated to form the ink cartridge 47. Note that the ink cartridge 47 can be reused by refilling the liquid container with the liquid after the liquid is consumed.

FIG. 13 is a perspective view showing an ink jet recording apparatus according to a fifth embodiment of the present invention, and FIG. 14 is a cross-sectional view showing a mechanism part of the ink jet recording apparatus of FIG.
In the ink jet recording apparatus of the fifth embodiment, a carriage 63 that is movable in the main scanning direction inside the recording apparatus main body 51, a recording head 64 that is an ink jet head according to the present invention mounted on the carriage 63, and supplies ink to the recording head 64. A paper feed cassette (or a paper feed tray) in which a printing mechanism portion 52 composed of an ink cartridge 65 or the like is housed and a large number of sheets 53 can be stacked from the front side in the lower portion of the recording apparatus main body 51 may be used. ) 54 can be removably mounted, and the manual feed tray 55 for manually feeding the paper 53 can be opened, and the paper 53 fed from the paper feed cassette 54 or the manual feed tray 55 can be removed. After a required image is recorded by the printing mechanism unit 52, it is discharged to a discharge tray 56 mounted on the rear side.

  The printing mechanism 52 holds the carriage 63 slidably in the main scanning direction (in the direction perpendicular to the paper in FIG. 14) with a main guide rod 61 and a sub guide rod 62 which are guide members horizontally mounted on left and right side plates (not shown). The carriage 63 is provided with a plurality of ink discharge heads 64 including the ink jet head of the above-described embodiment that discharges ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (Bk). The outlets are arranged in a direction crossing the main scanning direction, and the ink droplet ejection direction is directed downward. In addition, each ink cartridge 65 for supplying ink of each color to the recording head 64 is replaceably mounted on the carriage 63. Here, the recording heads of the respective colors are used as the recording head 64, but a single head having nozzles for ejecting ink droplets of the respective colors may be used.

  In order to move and scan the carriage 63 in the main scanning direction, a timing belt 70 is stretched between a driving pulley 68 and a driven pulley 69 that are rotationally driven by a main scanning motor 67, and the timing belt 70 is fixed to the carriage 63. The carriage 63 is reciprocated by forward and reverse rotation of the main scanning motor 67.

  On the other hand, in order to convey the paper 53 set in the paper feed cassette 54 to the lower side of the recording head 64, the paper 53 is guided from the paper feed roller 71 and the friction pad 72 for separating and feeding the paper 53 from the paper feed cassette 54. A guide member 73 for conveying, a conveyance roller 74 for reversing and conveying the fed paper 53, a conveyance roller 75 pressed against the peripheral surface of the conveyance roller 74, and a feeding angle of the paper 53 from the conveyance roller 74 are defined. A tip roller 76 is provided. The transport roller 74 is rotationally driven by a sub-scanning motor 77 through a gear train.

  Corresponding to the range of movement of the carriage 63 in the main scanning direction, there is provided a printing receiving member 79 which is a sheet guide member for guiding the sheet 53 fed from the conveying roller 74 below the recording head 64. On the downstream side of the printing receiving member 79 in the paper conveyance direction, conveyance rollers 81 and 82 that are rotationally driven to send the paper 53 in the paper discharge direction are provided, and a paper discharge roller that further feeds the paper 53 to the paper discharge tray 56. 83 and a spur 84, and guide members 85 and 86 forming a paper discharge path are disposed.

  At the time of recording, the recording head 64 is driven according to the image signal while moving the carriage 63, thereby ejecting ink onto the stopped paper 53 to record one line. Record the line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 53 reaches the recording area, the recording operation is terminated and the paper 53 is discharged. In this case, the inkjet head according to the present invention constituting the recording head 64 does not cause head breakage due to a difference in thermal expansion, recording unevenness, or the like, and enables stable and high-quality recording.

1 is a perspective view showing an ink jet head of Example 1. FIG. FIG. 2 is a cross-sectional view of the inkjet head shown in FIG. 1 taken along line AA. It is a reverse view of the inkjet head shown in FIG. FIGS. 4A and 4B show a relationship between the substrate and the base plate. FIG. 4A shows a state where no stress is generated on the substrate, and FIG. 4B shows a state where stress is generated on the substrate. It is a figure which shows the relationship between the recessed part formed in a board | substrate, and the opening width of a mask material. It is a perspective view which shows the joining relationship of a board | substrate and a baseplate. It is a back view of the other inkjet head which has a different recessed part. 6 is a perspective view showing an ink jet head of Example 2. FIG. It is a reverse view of the inkjet head shown in FIG. It is a back view of the other inkjet head which has a different recessed part. FIG. 6 is a partially exploded perspective view showing an ink jet head of Example 3. FIG. 6 is a perspective view illustrating an ink cartridge of Example 4. 6 is a perspective view showing an ink jet recording apparatus of Example 5. FIG. It is sectional drawing which shows the mechanism part of the inkjet recording device of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Board | substrate, 2 ... Pressure generating means, 3 ... Through groove, 4 ... Recessed part, 5 ... Columnar structure, 6 ... Ink channel substrate, 7 ... Nozzle plate, 8 ... Nozzle port, 9 ... Ink channel, 10 DESCRIPTION OF SYMBOLS ... Base plate, 11 ... Convex part, 20 ... Nozzle, 21 ... Ink flow path, 22 ... Pressure generating means, 23 ... Common liquid chamber, 24 ... Ink supply port, 25 ... Concave part, 31 ... Base plate, 32 ... Groove, 33 ... Recessed portion 47: Ink cartridge 48: Inkjet head 51: Recording apparatus main body 52: Printing mechanism 53: Paper 54: Paper feed cassette 55 ... Bypass tray 56: Discharge tray 61: Main guide rod 62 ... Subordinate guide rod, 63 ... Carriage, 64 ... Recording head, 65 ... Ink cartridge, 67 ... Main scanning motor, 74 ... Conveyance roller, 75, 81, 82 ... Conveyance roller, 79 ... Print receiving portion .

Claims (9)

  In a liquid droplet ejection head comprising a liquid flow path, a nozzle port communicating with the liquid flow path, a substrate having pressure generating means on a wall surface forming the liquid flow path, and a base plate that holds the substrate, the substrate or A droplet discharge head, wherein stress relaxation means for relaxing stress generated in the base plate is formed.   2. The liquid droplet ejection head according to claim 1, wherein the stress relaxation means is formed on a surface of the substrate facing the wall surface having the pressure generating means.   3. The liquid droplet ejection head according to claim 1, wherein the stress relaxation means comprises a concave portion formed by etching the substrate.   4. The droplet discharge head according to claim 3, wherein the depth of the recess is 1/15 or more of the thickness of the substrate.   The droplet discharge head according to claim 1, wherein the stress relaxation means is formed on the base plate.   The droplet discharge head according to claim 1, wherein a contact area between the substrate and the base plate is 2/3 or less of an area of the substrate.   The droplet discharge head according to claim 1, wherein the pressure generating unit is an electrothermal conversion element.   An ink cartridge on which the droplet discharge head according to claim 1 is mounted.   An ink jet recording apparatus comprising the droplet discharge head according to claim 1 or the ink cartridge according to claim 8 mounted thereon.