JP2000190499A - Top shooter type thermal ink jet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a top shooter type thermal ink jet head which corrects a positional deviation of ink discharge dots because of interlace driving or the like. SOLUTION: When a distance between a nozzle discharge face 38a of a nozzle hole 38 of a printing head to a paper 41 is L1, a thickness of an orifice plate 34 is L2, and an angle (inclination angle of a wall face of the nozzle hole 38) of a perpendicular line H erected to a central part of a face of a heating resistor 28 and a line J connecting the center of a bottom part of the nozzle hole 38 and an actual hit point P1 is θ, θ=tan-1(G1/(L1+L2) is obtained. The θ is determined if a desired G1 is given. For example, in the case of printing by 5-phase interlace driving, five dots from a first printing dot to a fifth printing dot shift in printing position by every 8.46 μm and therefore, the angle θof the five nozzle holes is obtained from an equation of G1=8.46 μ×n (n=1-5). When five nozzle holes 38 of an inclination angle of this angle θ are formed, printing dots are aligned in a longitudinal array with no positional deviation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a top shooter type thermal ink jet head for correcting a displacement of ink ejection dots in interlace driving or the like.

[0002]

2. Description of the Related Art In recent years, ink jet printers have been widely used. Printers using this ink jet system include a thermal ink jet system in which ink droplets are ejected by the force of air bubbles and a piezo ink jet system in which ink droplets are ejected by deformation of a piezoresistive element (piezoelectric element).

[0003] In these methods, a process in which ink as a color material is formed into ink droplets and directly ejected toward recording paper requires a lower printing energy as compared with an electrophotographic system using a toner as a powdery printing material. It is easy to colorize by mixing ink, and it is possible to reduce the size of printing dots, so that high image quality is achieved, the amount of ink used for printing is not wasted, and cost performance is excellent. This is the printing method used.

[0004] The above thermal ink jet system has two configurations depending on the direction in which ink droplets are ejected.
That is, there is a configuration that discharges in a direction parallel to the heating surface of the heating resistor, and a configuration that discharges in a direction perpendicular to the heating surface of the heating resistor.

FIGS. 6 (a), 6 (b) and 6 (c) show a structure in which the ink is discharged in a direction parallel to the heating surface of the heating resistor.
(e) and (f) each schematically show a configuration in which the ink is discharged in a direction perpendicular to the heat generating surface of the heat generating resistor. Figure (a)
Alternatively, as shown in (d), a heating resistor 2 is formed on a silicon substrate 1, and an orifice plate 3 is laminated with a certain gap. An orifice 4 is formed on the side of the heating resistor 2 in FIG. 1A and opposed to the heating resistor 2 in FIG. The heating resistor 2 is connected to an electrode (not shown), and the ink 5 is always supplied to the ink flow path in which the heating resistor 2 is provided.

In order to eject ink droplets from the orifice 4, first, as shown in FIG. 1 (b) or (e), the heating resistor 2 is heated by energizing according to image information, and the heating resistor 2 is heated. Nuclear bubbles are generated on the surface 2, and the nuclear bubbles are united to form a film bubble 6. The film bubble 6 adiabatically expands and grows to push the surrounding ink, whereby the ink 5 ′ is discharged from the orifice 4. The extruded ink 5 'is pushed out of the ink droplet 7 as shown in FIG.
Is discharged from the orifice 4 toward the paper surface. Thereafter, the grown film bubbles shrink due to the heat taken by the surrounding ink, and finally the film bubbles disappear, and the heating of the next heating resistor is awaited. This series of steps is performed instantaneously.

A structure in which ink droplets are ejected in a direction perpendicular to the heat generating surface of the heat generating resistor is called a roof shooter type thermal ink jet head or a top shooter type thermal ink jet head, and consumes very little power. It is known that it is necessary. As a method of manufacturing a thermal ink jet head in this type, there is a method in which a plurality of heating resistors, individual driving circuits, and orifices are collectively formed monolithically using a silicon LSI forming technique and a thin film forming technique.

According to this method, for example, in the case of a print head having a resolution of 360 dpi (dots / inch), 128 heating resistors, drive circuits, and orifices are formed on a substrate having a width of about 10 mm. Is 720 dpi, 256 heating resistors, drive circuits and orifices are formed.

FIG. 7A is a diagram schematically showing an ink ejection surface of the above-described top shooter type thermal ink jet head (hereinafter, simply referred to as a print head), and FIG.
Is a sectional view taken along the line BB 'of FIG. A print head 10 shown in FIGS. 1A and 1B includes a semiconductor substrate 11, a heating section 12 formed of a heating resistor formed thereon, a partition 13 formed at a predetermined location, and a gap formed by the partition 13. Ink supply passages 14, an orifice plate 15 laminated thereon, and nozzles 16 formed in the orifice plate 15 for guiding the direction of ink ejection (nozzles 16 in FIG. Nozzle number N01).

Here, as shown in FIG. 1A, an example of a print head 10 having 60 nozzles 16 with nozzle numbers N01 to N60 is shown. The ink supply passage 14 communicates with an ink tank (not shown), and the heating resistor 12 is always supplied with ink as shown by an arrow C in FIG. As described above, due to the heat generated by the heating resistor 12, the ink droplet flows from the nozzle port 16-1 to the sheet 1.
The ink is ejected toward the print surface 7 and lands on the print point P. The print head 10 performs the above printing while moving in the main scanning direction indicated by the arrow A in the figure.

By the way, in the configuration of the print head 10 in which a plurality of nozzles 16 are juxtaposed at close intervals as described above, in order to eject ink from 60 nozzles 16 at the same time, 60 heating elements 12 are simultaneously connected. Driving means that there is a possibility that a semiconductor circuit (not shown) mounted on the semiconductor substrate 11 may not operate normally due to excessive heat generation.

Therefore, in order to avoid excessive temperature rise of the print head due to such heat generation, generally, all the heat-generating low antibodies constituting the nozzle array are not driven at the same time.
Divide all heating resistors into appropriate numbers (grouping)
Interlace driving is performed in which the first heating resistor of each group is heated first, and then the second heating resistor of each group is heated at a staggered time.

For example, in the case of the print head 10 shown in FIG. 7A, it is assumed that four heating resistors 16 can be driven simultaneously. In that case, the 60 nozzles 16 are divided into four groups. For example, the nozzle numbers N01 to N15
Group, nozzle numbers N16 to N30 are a second group,
The nozzle numbers N31 to N45 are a third group, and the nozzle numbers N46 to N60 are a fourth group.

As described above, the same application timing is given to each group. That is, the first nozzle in the first group (nozzle number N01), the first nozzle in the second group (nozzle number N16), the first nozzle in the third group (nozzle number 31), and the first nozzle in the fourth group (nozzle number N46) ) Are driven to generate heat at the same application timing.

Further, the nozzles are divided even in the same group. For example, in the case of five-phase interlace driving, the image is divided into five parts. Since the operation is the same for each group, the first
Describing the group, first, the nozzle number N01
After applying a drive voltage to the heating resistor 12 (hereinafter, only the nozzle number will be described), the nozzle number N0
6, and a drive voltage is sequentially applied to the nozzle number N11.

Next, the fifth nozzle number is N16.
Since this is the nozzle number of the adjacent second group, the operation returns to the nozzle number N02 and the drive voltage is applied again every five nozzles. When the nozzle number N12 is applied, the fifth nozzle number is the nozzle number N17 of the second group, so that the process returns to the nozzle number N03 and the drive voltage is applied again every five nozzles. While printing is being performed in this manner, the paper 17 is stopped.

[0017] Thus, it is known that there is an advantage that overheating of the print head is prevented and power consumption can be reduced as compared with the case where all the heating resistors are driven collectively. I have.

[0018]

However, during the above printing, the print head 10 moves in the main scanning direction indicated by the arrow A even when the paper is stopped. Therefore, the printing result of the ink droplets that have landed on the paper 17 has a positional deviation in accordance with the ejection order.

FIG. 8 is a diagram schematically showing a result of printing by the above-described five-phase interlace driving, and shows a result of printing by the length of the nozzle row of the print head 10 in the sub-scanning direction. However, FIG.
2 shows only the print portion. The printing portion by the nozzles 16 of the second, third, and fourth groups also has the same printing mode except that the dot numbers are different.

A print sequence R1 shown in FIG. 1 is a print sequence to be printed this time, and a print sequence R2 is a next print sequence in the main scanning direction. White point N01p is nozzle 1 of nozzle number N01
6, the white point N02p
Is a printing result (hereinafter, the same applies) printed by ink ejected from the nozzle number N02. As shown in the figure, the vertical arrangement of the printing dots is inclined every five dots. As described above, the printing result is affected by the printing control method of the interlace driving, and has a positional shift, so that a clear straight line in the sub-scanning direction cannot be formed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional circumstances,
An object of the present invention is to provide a top shooter type thermal inkjet head that corrects a displacement of ink ejection dots due to interlace driving.

[0022]

First, a top-shooter type thermal ink jet head according to the first aspect of the present invention is provided with a discharge nozzle at a position facing a plurality of heating resistors arranged in parallel in the sub-scanning direction. In a top shooter type thermal inkjet head that prints dots adjacent in the sub-scanning direction at predetermined time intervals, the center line of the ejection hole of the ejection nozzle and the normal line of the surface of the heating resistor facing the ejection nozzle The discharge nozzle is formed by changing the angle formed by the angle according to the timing of applying a voltage to the heating resistor.

The angle is formed with n kinds of changes in the n-phase interlace driving, for example.

A top shooter type thermal ink jet head according to a third aspect of the present invention includes a discharge nozzle at a position facing a plurality of heating resistors arranged in parallel in the sub-scanning direction, and is provided adjacent to the heating resistor in the sub-scanning direction. In a top shooter type thermal ink jet printer that prints dots to be printed at predetermined time intervals, the center line of the discharge hole of the discharge nozzle extends along the normal direction of the surface of the heating resistor facing the discharge nozzle. The distance between the center line and the center position of the heating resistor is changed according to the timing at which a voltage is applied to the heating resistor.

The distance is formed with n kinds of changes in the n-phase interlace driving, for example.

[0026]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 (a), (b), (c) and FIGS. 2 (a), (b), (c)
FIGS. 1A and 1B are diagrams showing a method of manufacturing a top shooter type thermal inkjet head (hereinafter simply referred to as a print head) in the first embodiment in the order of steps. FIG. 1A is a plan view of the print head, and FIG. () Is a diagram showing a state in which a number of substrates (chips) of the print head are formed on a silicon wafer.

FIG. 2 (a) shows an enlarged plan view of FIG. 1 (a) in the upper part, a cross-sectional view taken along the line CC 'of the upper part in the middle part, and a cross-sectional view taken along the line DD' of the upper part in the lower part. FIG. FIG.
(b) shows a step that follows the step shown in FIG. 2 (a).
The parts shown in the middle and lower parts correspond to the parts shown in the upper, middle and lower parts of FIG. Then, FIG. 2 (c)
Is a diagram showing the last step, and the parts shown in the upper, middle and lower parts correspond to the upper, middle and lower parts in FIG. 2 (a). 2 (a), 2 (b) and 2 (c), for convenience of illustration, 128 or 256 heating elements and orifices are represented by 5 heating elements and orifices. Is shown.

In this embodiment, the print head 20 shown in FIG. 1C is formed as a chip substrate 22 divided by scribe lines on one silicon wafer 21 as shown in FIG. 1D. Many (for example, 90 or more) are formed,
After completion through a manufacturing process to be described later as shown in FIG. 7C, the silicon wafer 20 is individually cut out.

Hereinafter, FIGS. 1 (a), (b), (c) and FIGS. 2 (a), (b),
The method of manufacturing the print head 20 will be described first with reference to FIG. First, as a first step, a drive circuit and its terminals are formed by an LSI forming process and a passivation film having a thickness of 1 to 2 μm is formed on each substrate 22 partitioned on a silicon wafer 21 of 4 inches or more, Thereafter, a contact hole is formed in the terminal and an unnecessary portion of the passivation film is removed.

Next, in step 2, a heating resistor film for forming a heating element made of Ta—Si—O is formed to a thickness of 4000 ° by using a thin film forming technique such as a sputtering technique. An electrode film for forming individual wiring electrodes is formed. This electrode film is made of W-Al (or W-
Au, a barrier metal film made of Ti, W-Si), etc.
It is preferable to form a multi-layer structure in which electrode films are laminated. Then, the electrode film (and the barrier metal film if a barrier metal film is formed) is formed by photolithography.
A wiring portion pattern is formed, and a square exposed portion of, for example, approximately 40 μm × 40 μm is formed on the heating resistor film. Thereby, a fine pattern of the heating element (heating section) is formed.

FIGS. 1 (a) and 2 (a) show a state immediately after the above steps 1 and 2 are completed. That is, a drive circuit 23 and its terminals 24 (see FIG. 1A) are formed on the substrate 22, and the common electrodes 25 (25a,
25b), a common electrode power supply terminal 26 (see FIG. 1A), individual wiring electrodes 27, and a number of heating resistors 28 are formed.

Subsequently, in step 3, a partition member made of an organic material such as photosensitive polyimide is formed to a height of about 20 μm by coating to form ink paths corresponding to the individual heating resistors 28, and this is patterned. 30 minutes to 60 minutes, optionally 2 hours, 300 ° C.
Curing (dry curing, baking) by applying heat at 400 ° C. is performed, and a barrier made of the photosensitive polyimide having a height of 10 μm after curing is formed on the substrate 22 and fixed.

Further, in step 4, a groove-like ink supply path is formed on the surface of the substrate 22 by wet etching or sandblasting, and an ink supply hole communicating with the ink supply path and opening on the lower surface is formed. I do.

FIGS. 1 (b) and 2 (b) show a state immediately after Steps 3 and 4 are completed. That is, the groove-shaped ink supply passage 29 and the cylindrical ink supply hole 3
1 are formed, a partition wall 32 (between the common electrode 25 (25a) portion located on the left side of the ink supply path 29, the portion on which the right individual wiring electrode 27 is provided, and each heating resistor 28). 32, 32-1 and 32-2) are formed.
If the portion 32-1 on the individual wiring electrode 27 is a comb body, the partition 32 extends between the heating resistors 28.
2-2 has a shape corresponding to the teeth of a comb.

As a result, the fine individual ink paths in which the heating resistors 28 are located at the roots between the teeth are formed by the number of the heating resistors 28 with the teeth of the comb as partition walls. By changing the length of the teeth of the comb, the conductance of the flowing ink changes, and the interference between the ink flowing in adjacent individual ink paths is also affected.

Thereafter, in step 5, an orifice plate of a film of polyimide having a thickness of 10 to 30 μm is coated on one side with a very thin thermoplastic polyimide as an adhesive, for example, to a thickness of 2 to 5 μm. The ink path formed by the partition walls 32 is attached to the uppermost layer of the laminated structure, thereby forming a fine individual ink path and a common ink path. Then, pressure is applied while heating at 200 to 300 ° C. to fix the orifice plate. Subsequently, a thickness of 0.5, such as Ni, Cu or Al, is formed on the orifice plate surface.
A metal film having a thickness of about 1 μm is formed.

Further, in step 6, the metal film on the orifice plate is patterned to form a mask for selectively etching the polyimide, and then the orifice plate is subjected to the above-mentioned etching by a helicone wave etching device or the like. A plurality of nozzle holes (orifices) are formed at a time by making holes of 40 μmφ to 20 μmφ according to the metal film mask.

FIGS. 1 (c) and 2 (c) show a state immediately after the completion of the steps 5 and 6. That is, on the uppermost layer of the substrate 22, a thermoplastic polyimide 3
An orifice plate 34 coated with the third electrode 3 is laminated so as to cover the entire area except for the drive circuit terminal 24 and the common electrode power supply terminal 26, thereby covering the ink path described above and forming the partition wall 32 with a thickness of 10 μm. Are formed, and a common ink path 36 having a height of 10 μm, which connects the individual ink path 35 and the above-described ink supply path 29, is formed.

A metal film 37 is formed on the upper surface of the orifice plate 34, and a nozzle hole (orifice) 38 for discharging ink is formed in a portion corresponding to the heating resistor 28 by dry etching. As described above, FIG. 1 having one nozzle row including a large number of nozzle holes 38 is provided.
A top shooter type thermal ink jet head 20 shown in FIG. 1C is completed on a silicon wafer 21 shown in FIG.

The mask metal film is made of Ni, C
By using u, Al, or the like, a selectivity of approximately 100 between the resin and the metal film can be obtained. Therefore, 20 to 40 μ
1 μm for dry etching of polyimide film
It is sufficient to form a mask with the following metal film.

As described above, it is possible to monolithically configure the print head 20 having a large number of nozzle holes 38 in a line by the above-described manufacturing method. The positional relationship can be accurately arranged by today's semiconductor manufacturing technology.

The processing up to this point is performed in the state of a wafer.
Finally, as a step 7, cutting is performed along the scribe line 39 using a dicing saw or the like, divided into individual units, die-bonded to a mounting board, connected to terminals, and printed in practical units. The head 20 is completed.

In the print head 20, when printing, each heating resistor 28 is selectively energized in accordance with print information.
Heat is instantaneously generated to cause a film boiling phenomenon, and ink droplets are ejected from the nozzle holes 38 corresponding to the heating resistors 28. In such a thermal inkjet head, ink droplets are ejected in a substantially spherical shape having a size corresponding to the diameter of the nozzle hole, and are printed on the paper with a size approximately twice as large.

In the meantime, the basic manufacturing method has been described in the manufacturing process of the print head 20 described above. The present embodiment is characterized in that, in addition to the basic manufacturing method described above, the formation of the nozzle holes 38 or Special measures have been taken in the positional relationship between the heating resistor 28 and the nozzle hole 38. And, with this ingenuity, the problem of misalignment of print dots in interlaced driving is solved. Hereinafter, this will be described.

First, the printing result shown in FIG. 8 by the conventional print head 10 shown in FIGS. 7A and 7B will be examined in more detail. The example shown in the figure is a 600 dpi printer, and the nozzles are arranged at an interval of 42.3 μm.
The rows R1 and R2 (see FIG. 8) as the printing result are also separated at an interval of 42.3 μm. Here, assuming that the time required to apply the energy required to discharge the ink droplets to the heat generating unit 12 is 2.5 μs and the rest time is 2.5 μs, the printing cycle of one dot is 5 μs. Since each of the above-described groups of nozzles 16 includes 15 nozzles, it takes 15 × 5 μs, that is, 75 μs, to discharge all the dots.
Time will be required.

Therefore, the repetitive driving cycle of the heating section 12 is set to 75 μs. That is, the time required for the print head 10 to move from the row R1 to the row R2 is 75 μs. Therefore, the moving speed of the print head 10 is 42.3 μm ÷ 7.
5 μs, that is, 0.564 m / s.

Since all the times in the repetitive driving cycle are used for the five-phase interlace control, the distance between the center points of the adjacent landing dots N01p and N02p in the main scanning direction is the same as that of the row R1 as the printing result. And 1 / between row R2
5, 42.3 μm ÷ 5, that is, 8.46 μm
m. Similarly, the landed dot N02p and its adjacent dot N03p, the dot N03p and the dot N04p, and the dot N04p and the dot N05p are 8.46 μm apart.

Based on these facts, in the present embodiment, first, the shape of the nozzle hole 38 is devised.

FIG. 3 shows a nozzle hole 38 formed in step 6 of manufacturing the print head 20 according to the present embodiment.
It is a figure which shows typically the shape of. It should be noted that FIG.
(a), (b), (c) and FIGS. 2 (a), (b), (c), and FIG. 1 (a), (b), (c), and FIG. 1 (a), (b), (c) and FIGS. 2 (a), 2 (c)
The same numbers as in (b) and (c) are given.

In the manufacture of the print head 20 according to the present embodiment, first, in the above-described step 6, as shown in FIG. 3, the shape of the nozzle hole 38 is the same as the conventional nozzle shown in FIG. It is formed at a certain angle from the direction perpendicular to the surface of the heating element 28, that is, the direction normal to the surface of the heating resistor 28, as shown in FIG.

When the heating resistor 28 is driven, the common ink path 36 and the individual ink path 35 are supplied as shown by the arrow E in FIG. Nozzle hole 3 guided by the wall
8 and land at the position P1 shifted in the main scanning direction indicated by the arrow F in the figure, not at the point P0 of the sheet 41 corresponding to the vertical line E set at the center of the surface of the heating resistor 28. I do.

At this time, the displacement G1 of the landing dot from the point P0 to the position P1 is determined by the distance L1 from the nozzle ejection surface 38a to the sheet 41 and the thickness of the orifice plate 34 by L1.
2. The angle (angle of inclination of the wall surface of the nozzle hole 38) formed by a vertical line H formed in the center of the surface of the heating resistor 28 and a line J connecting the actual impact point P2 from the center of the bottom of the nozzle hole 38 is defined as θ. It is given by the following equation.

G1 = (L1 + L2) × tan θ (1) From this equation, θ = tan ⁻¹ (G1 / (L1 + L2)) (2) is obtained, and a desired G1 is obtained. If given, θ is determined.

As described above, in the printing example of the conventional five-phase interlace driving of the print head 10, the printing positions of the five dots from the printing dot N05p to the printing dot N05p are each shifted by 8.46 μm. That is, based on the print dot N01p of the nozzle of the nozzle number N05, the print dot N01 of the nozzle of the nozzle number N01 is used.
p is 33.84 μm (8.46 μm × 4), and the print dot N03p of the nozzle of nozzle number N02 is 25.38 μm.
(8.46 μm × 3), the dot N03p is 16.92 μm (8.46 μm × 3) in the meaning of the nozzle of nozzle number N03.
2), print dot N04p of nozzle of nozzle number N04
Is shifted by 8.46 μm.

Therefore, in the present embodiment, each nozzle hole 38 is formed in advance with the following angle θ. Here, the distance L1 from the nozzle end 38a to the paper 41 is 1 mm, and the thickness L2 of the orifice plate 34 is 50 μm.
m, the nozzle holes 38 which are driven in an interlaced manner and further divided into five groups in each group and driven in order from the top are nozzle 1, nozzle 2,..., nozzle 5, nozzle 1: tan ^-1 ( 8.46 μm × 4 / (1 mm + 5
0 μm) = 1.846 ° Nozzle 2: tan ⁻¹ (8.46 μm × 3 / (1 mm + 5)
0 μm) = 1.385 ° Nozzle 3: tan ⁻¹ (8.46 μm × 2 / (1 mm + 5)
0 μm) = 0.923 ° Nozzle 4: tan ⁻¹ (8.46 μm × 1 / (1 mm + 5)
0 μm) = 0.462 ° Nozzle 5: tan ⁻¹ (8.46 μm × 0 / (1 mm + 5)
0 μm) = 0.0 °.

Since the nozzle 1 ejects ink first, the nozzle 1 is 33.84 μm in the main scanning direction in consideration of the fact that the print head 20 moves in the main scanning direction in advance.
The nozzle angle is 1.846 ° so that printing is performed at a position shifted by (8.46 μm × 4). The same applies to the following nozzles 2, 3 and 4.

FIG. 4 is a diagram showing the result of printing by the print head 20 configured as described above. As shown in the drawing, print dots 1p, 2p to 15p...
2, that is, the prints are printed in a line in a substantially straight line just before the next print row.

As described above, the print head 20 has the same nozzle angle every five nozzles sequentially. That is, the angles of the first nozzle and the sixth nozzle are the same.
Essentially, strictly speaking, only one nozzle in each group is synchronized with one nozzle in the other group.
Since there is a driving time difference of 5 μsec between the nozzle 1 and the nozzle 6 which are further divided and driven every five in the group, 2.
An impact position deviation of 82 μm has occurred (print head 2
0 speed × discharge time difference = 0.564 m × 5 μsec =
2.82 μm). However, this shift amount is 4 lines apart.
Since it is a slight difference with respect to 2.3 μm, it is a deviation amount that is hardly noticeable visually.

In this embodiment, nozzles 38 having five kinds of angles are formed to cope with the five-phase interlace. The method of forming the nozzle having this oblique angle is, for example, the orifice plate 34 (or the silicon wafer 2).
1) may be placed on a jig having five angles, and a desired nozzle may be formed at each angle.

Further, in the above example, in the n-phase interlace, n nozzles have n types of nozzle angles, but all nozzles may have nozzle angles corresponding to the discharge time difference. For example, if each group consists of 15 nozzles, and the 15 nozzles sequentially eject ink every 5 μs, the distance the print head 20 advances in 5 μs is 2.8.
3 μm (speed of the print head 20 × discharge time difference = 0.564 m / s × 5 μsec), the nozzle angle θ is inclined in the plus direction (main scanning direction) for all nozzles as shown in FIG. In the case where the ink is ejected, the number of nozzles in each group is k, and the order of ink ejection is n (n = n).
1, 2,..., N), assuming that the distance the print head advances at one dot drive interval is s (2.82 μm in this example), the inclination angle θn of the n-th nozzle is θn = tan ^{− 1} ((kn) × s / (L1 + L2)) (3) In this case, in this example, nozzles having 15 kinds of angles (the number of nozzles in one group) are formed. As described above, since the drive timing is the same between the groups, the nozzles at the same position between the groups have the same nozzle angle.

In this example, the nozzle angle θ is formed in the plus direction for all the nozzles. However, the present invention is not limited to this, and the nozzle angle θ may be formed in the minus direction, or the plus direction and the minus direction may be mixed. You may make it.
In the case of such coexistence, for example, when changing every five nozzles, the angle of the nozzle 3 is 0, the angles of the nozzles 1 and 2 are plus, and the nozzles 4 and 5 are minus.

The present invention is not limited to a thermal ink jet head, but can be applied to other systems having nozzles, for example, a piezoelectric ink jet head. Further, the present invention is also applicable to an inkjet head having a plurality of nozzle rows (for example, a full-color inkjet head having four rows arranged in parallel).

FIG. 5 is a diagram showing a basic configuration of a print head according to the second embodiment. In the case of this example, in step 6 of the above-described print head manufacturing process, the nozzle hole 38 is formed not perpendicularly to the surface of the heating resistor 28 but at an angle. Then, in the step 2 before that, the position of the heating resistor 28 is arranged so as to be even shorter than the center of the nozzle hole 38. Even if the print head is configured as described above, it is possible to correct the displacement of the print dots in the landing direction.

The arrangement of the heating resistors 28 is shifted by a distance M in the direction opposite to the direction of the landing position P2 where the print dots are to be shifted, as viewed from the center line K of the nozzle hole 38. . It has been found through experiments that the larger the displacement M of the heating resistor 28, the larger the displacement G2 of the landing print dot.

In this case, similarly to the case of the first embodiment described above, the displacement of the landing print dots is changed by changing the displacement of the arrangement position of the heating resistor 28 in accordance with the ink ejection timing. Try to correct the amount.

At this time, in order to shift the landing position by 8.46 μm from the nozzle 4 to the nozzle 1 with the nozzle 5 as a reference, the center line of the heat-generating resistor 28 and the center line of the nozzle hole 38 in FIG. 0.417
It shifts by μm. That is, nozzle 1: 0.417 μm × 4 = 1.67 μm, nozzle 2:
0.417 μm × 3 = 1.25 μm, nozzle 3: 0.4
17 μm × 2 = 0.834 μm, nozzle 4: 0.417
μm × 1 = 0.417 μm, nozzle 5: 0.417 μm
× 0 = 0.0 μm.

The above 0.417 μm is an example when the distance between the paper 41 and the nozzle surface 38a is 1 mm. The rationale is as follows. In the experiment by the inventor, from the center of the nozzle hole 38 under the conditions that the diameter of the nozzle hole 38 is 29 μm, the size of the heating part of the heating resistor 28 is 25 × 25 μm, the thickness of the orifice plate 34 is 31 μm, and the height of the partition wall 32 is 7 μm. When the heating portion of the heating resistor 28 was shifted by 10 μm, the ink droplet was ejected at an angle of 12 ° in a direction opposite to the shifted direction. The relationship between the displacement of the heating portion of the heating resistor 28 and the inclination of the ink droplet ejection direction was not affected by the applied thermal energy or the driving repetition cycle.

As described above, a discharge inclination of 12 ° is obtained when M = 10 μ. Therefore, in FIG. 5, in order to set the displacement G2 of the landing print dot to 8.64 μm, the nozzle discharge surface 38
When the distance between a and the paper 41 is 1 mm, a discharge inclination of 0.5 ° is necessary. Therefore, to obtain 0.5 ° as a discharge angle difference between adjacent nozzles, 10 μm × (0.5 / 12) That is, it is only necessary to sequentially increase (or decrease) the shift amount M by 0.417 μm.

[0070]

As described above in detail, according to the present invention, the nozzle hole is formed to have an angle so that the ejection angle is inclined in accordance with the difference in the ejection time of the ink, Since the arrangement position of the heating resistor is shifted,
In the interlaced drive or the like, there is no dot displacement in the print dot row, so that a high-quality image can be obtained.

[Brief description of the drawings]

FIGS. 1A, 1B, and 1C are views showing a method of manufacturing a top shooter type thermal inkjet head according to a first embodiment in the order of steps, and FIG. 1D is a view showing a chip substrate on a silicon wafer; It is a figure showing the state where many were formed.

2 (a) is an enlarged plan view of FIG. 1 (a); FIG. 2 (b) is an enlarged plan view of FIG. 1 (a); FIG. The upper, middle, and lower rows are views showing steps subsequent to (a), and the upper, middle, and lower rows in (c) are views showing the last step.

FIG. 3 is a diagram schematically showing a shape of a nozzle hole formed in a process 6 for manufacturing a print head according to the first embodiment.

FIG. 4 is a diagram illustrating a result of printing by a print head according to the first embodiment.

FIG. 5 is a diagram illustrating a basic configuration of a print head according to a second embodiment.

6 (a), 6 (b) and 6 (c) show a structure in which a discharge is performed in a direction parallel to the heat generating surface of the heat generating resistor, and FIGS. It is a figure which shows the thing of the structure which discharges in the direction perpendicular | vertical to a surface, respectively.

FIG. 7A is a view schematically showing an ink ejection surface of a conventional top shooter type thermal inkjet head (print head), and FIG. 7B is a sectional view taken along the line BB 'of FIG.

FIG. 8 is a diagram schematically showing a result of printing by a conventional print head by five-phase interlace driving.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Silicon substrate 2 Heating resistor 3 Orifice plate 4 Orifice 5 Ink 5 'Extruded ink 6 Film bubble 7 Ink droplet 10 Print head 11 Semiconductor substrate 12 Heating part 13 Partition wall 14 Ink supply passage 15 Orifice plate 16, N01-N60 nozzle 16-1 Nozzle port 17 Paper P Print point 20 Print head 21 Silicon wafer 22 Chip substrate 23 Drive circuit 24 Terminal 25 (25a, 25b) Common electrode 26 Common electrode power supply terminal 27 Individual wiring electrode 28 Heating resistor 29 Ink supply path 31 Ink feed hole 32 (32, 32-1, 32-2) Partition wall 33 Thermoplastic polyimide 34 Orifice plate 35 Individual ink path 36 Common ink path 37 Metal film 38 Nozzle hole (orifice) 39 Scribe line 41 Paper

Claims (4)

[Claims] 1. A top-shooter-type thermal printer comprising a discharge nozzle at a position facing a plurality of heating resistors arranged in parallel in the sub-scanning direction, and printing dots adjacent in the sub-scanning direction at predetermined time intervals. In the inkjet head, an angle formed between a center line of the ejection hole of the ejection nozzle and a normal to the surface of the heating resistor facing the ejection nozzle is changed according to a timing of applying a voltage to the heating resistor. ,
A top shooter type thermal inkjet head, wherein the ejection nozzle is formed. 2. The top shooter type thermal inkjet head according to claim 1, wherein said angle is formed with n kinds of changes in n-phase interlace driving. 3. A top-shooter type thermal printer having discharge nozzles at positions facing a plurality of heating resistors arranged in parallel in the sub-scanning direction, and printing dots adjacent in the sub-scanning direction at predetermined time intervals. In the ink jet printer, a center line of the discharge hole of the discharge nozzle is along a normal direction of a surface of the heating resistor facing the discharge nozzle, and the center line and a center position of the heating resistor. The distance is
A top-shooter type thermal inkjet head, which is formed by changing in accordance with the timing of applying a voltage to the heating resistor. 4. The top shooter type thermal inkjet head according to claim 3, wherein the distance is formed with n kinds of changes in n-phase interlace driving.