JPH08295022A - Ink jet recording head - Google Patents

Abstract

PURPOSE: To provide an ink jet recording head effectively suppressing the shift of the arrival positions of ink droplets and enhancing printing quality. CONSTITUTION: An ink jet recording head has a head main body 5 constituted by providing orifice parts 14, 16 having ink emitting orifices forming ink droplets, the ink passage forming member 2 supporting the orifice parts 14, 16 and integrated therewith and a thermal head substrate 4 equipped with heating elements 3 forming ink droplets. The ink emitting direction of the orifice parts 14, 16 is set to a state slightly inclined toward the downstream side in the moving direction of the head main body 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording head, and more particularly to an ink jet recording head which ejects ink to form ink droplets for recording.

[0002]

2. Description of the Related Art In an ink jet recording head, ink droplets to be ejected are ejected with a tailing at the time of ejection, in addition to main droplets forming dots. Therefore, the ink droplets are accompanied by satellites before they land on the recording material. Since the ink droplets are bent and ejected in the scanning direction of the carriage on the apparatus, the occurrence of satellites increases ink scattering and causes a significant deterioration in print quality.

Further, when bidirectional printing is performed, the ink droplets are bent and ejected in the scanning direction of the carriage as described above, which causes a deviation of the ruled lines when the vertical ruled lines are printed, and deteriorates the print quality. There was an inconvenience.

In order to solve these problems, the following methods have been conventionally used. ． Reduce the print gap between the recording head and recording paper. ． In the case of bidirectional printing, the ejection timing of ink droplets is slightly shifted according to the moving direction of the carriage. ． One-way printing is performed when the carriage is moved in the direction opposite to the direction in which the ink droplets are inclined by utilizing the fact that the ink ejection direction is inclined due to the difference in the wettability of the material around the orifice. ． An air nozzle that generates an air flow from the same direction as the moving direction of the carriage is provided near the ejection port of the ejected ink.

[0005]

However, when the print gap is narrowed, there is a disadvantage that various sheets having different thicknesses cannot be accommodated.

Further, when the ejection timing of ink droplets is delayed (shifted) in accordance with the moving direction of the carriage, generally, the ink droplet ejection speed cannot be said to be completely constant when ejecting from the same orifice. Further, in an ink jet recording head having a plurality of nozzles, the ejection speeds of the nozzles vary, and thus the misalignment of the ejection speeds may cause misalignment of the droplet deposition even if the ejection timing is shifted.

Further, when unidirectional printing is performed by limiting the ink ejection direction to the opposite direction to the inclined direction, the printing quality is improved but the printing speed is slowed down.

Furthermore, an air nozzle is provided near the discharge port,
The method of generating the airflow to control the direction of the ink droplet has a disadvantage that the airflow causes disturbance to the ink droplet and the ink scattering is increased.

[0009]

It is an object of the present invention to provide an ink jet recording head which improves the disadvantages of the conventional example, effectively suppresses the deviation of the ink droplet landing position, and thereby improves the printing quality. The purpose is to do.

[0010]

According to a first aspect of the present invention, an orifice portion having an ink discharge port for forming ink droplets, and an ink flow path formation supporting the orifice portion and being integrated with the orifice portion. In an ink jet recording head having a head body including a member and a thermal head substrate having a heating element for forming the ink droplets, an ink droplet ejection direction of an orifice portion is set to a downstream side of a moving direction of the head body. The configuration is set so that it is tilted slightly toward the side.

According to a second aspect of the present invention, an orifice portion having an ink discharge port for forming ink droplets, an ink flow path forming member that supports the orifice portion and is integrated with the orifice portion, and the ink droplets. In an ink jet recording head having a head main body comprising a thermal head substrate having a heating element for forming an orifice, a fixed orifice part and a movable orifice part provided outside the fixed orifice part. It consists of and. Then, the ink droplet ejection direction of the movable orifice portion is set to be slightly inclined toward the downstream side in the moving direction of the head body described above.

According to a third aspect of the present invention, an orifice portion having an ink discharge port for forming ink droplets, an ink flow path forming member that supports the orifice portion and is integrated with the orifice portion, and the ink droplets. In an ink jet recording head having a head main body comprising a thermal head substrate having a heating element for forming an orifice, a fixed orifice part and a movable orifice part provided outside the fixed orifice part. It consists of and. Then, the movable orifice portion has a first movable orifice and a second movable orifice in a state in which the movable orifice portion is slightly inclined in the opposite directions toward the downstream side in one of the reciprocating directions of the head body and the other direction. Consists of,
The method is adopted. This aims to achieve the above-mentioned object.

[0013]

[Operation] When the head main body is transported in one direction, the orifice portion slightly inclines in the direction opposite to the moving direction of the head main body, and ejects ink droplets. In this case, the amount of deviation of the landing positions of the main droplet 51 and the last satellite 52 when ejected at an angle of θ in the direction opposite to the carriage movement direction is smaller than that in the case of vertical ejection. Therefore, the main drop 51
Therefore, the amount of deviation of the landing position of the last satellite 52 surely decreases.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIG. First, in FIGS. 1A and 1B, reference numeral 1 indicates an orifice portion 1 having ink ejection ports 1A and 1B for ejecting ink droplets. The orifice portion 1 is provided at the tip of the ink flow path forming member 2. In addition, the ink flow path 2A of the ink flow path forming member 2 is equipped with the heating element 3 that instantly generates the bubble 3A for forming the above-described ink droplet.

The heating element 3 is mounted on the thermal head substrate 4 which forms one side of the ink flow path 2A together with the ink flow path forming member 2 described above. Then, with the ink flow path forming member 2 and the thermal head substrate 4,
A head body 5 is formed.

The head body 5 is mounted on a carriage and is moved in the direction of arrow A.

The orifice section 1 is a fixed orifice section 11
And a moving orifice portion 12 provided outside the fixed orifice portion 11.

Of these, the moving orifice portion 12 is set in a state of being slightly inclined in the opposite direction toward the downstream side in each of the one direction and the other direction in the reciprocating direction (A or B) of the head body 5. It is composed of a moving orifice member having a first moving orifice 14 and a second moving orifice 16.

Here, in FIG. 1A, the head main body 5
Shows the case of being transferred in the direction A in FIG. In this case, the moving orifice portion 12 is moved in the direction of arrow a, so that the first moving orifice 14 is communicated with the fixed orifice portion 11.

Further, in FIG. 1B, the head body 5 is
The case where it is transferred in the B direction in the figure is shown. in this case,
The moving orifice portion 12 is moved in the direction of the arrow b, so that the second moving orifice 16 is communicated with the fixed orifice portion 11.

In this case, the inclination angles of the first and second orifices 14 and 16 are optimized in advance depending on the gap between the recording paper 100 and the head body 5, the carriage movement speed, the ejection speed, and the like. Is selected and determined.

Next, based on FIGS. 2 to 3, the above-described paper 100 when ejected ink droplets are ejected by the first moving orifice 14 or the second moving orifice 16.
The state of landing of the ink droplet with respect to is compared with the case where the orifice is not inclined in the conventional example.

FIG. 2 shows a case where the ink droplets are ejected perpendicularly to the recording paper 100, and FIG. 3 shows that the ink droplets are inclined by θ with respect to the recording paper 100 in the direction opposite to the carriage movement direction A or B. The case where the ink is discharged while being inclined in the direction of is shown.

In this case, it is assumed that the ink jet recording head is incorporated in the carriage 13 and moves in the -y direction to print on the recording paper 100.

In FIG. 2, the recording paper 100 is generated when ink droplets are ejected perpendicularly to the recording paper 100.
The deviation of the landing positions of the upper main droplet 51 and the last satellite 12 is determined.

First, after the drive pulse is applied, the time T1 for the main droplet 51 to reach the recording paper 100 is X0, the distance between the head end surface and the recording paper 100, and X1 is the discharge distance of the main droplet 51 at an arbitrary time. , V1 is the discharge velocity component of the main droplet 51 in the direction of the main axis, T1 = (X0-X1) / V1 …………………………………… (1) The landing position y1 of the main droplet 51 is , Y1 = V3.T1 = V3 [(X0-X1) / V1] ......... (2)

Similarly, the last satellite 52 is the recording paper 1.
The time T2 to reach 00 is T2 = (X0-X2) / V2, where X2 is the discharge distance of the tail satellite 52 at any time and V2 is the discharge velocity component in the main axis direction. (3) The landing position y2 of the last satellite 52 is the carriage 1
When the moving speed of 3 is V3, y2 = V3.T2 = V3 [(X0-X2) / V2] .......... (4)

Therefore, the amount of deviation Δy of the landing position between the main droplet 51 and the last satellite 52 is Δy = y ₂ −y ₁ = V ₃ (X ₀ −X ₂ ) / V ₂ −V ₃ [( X ₀ -X ₁₎ / V _1] = V _{3 [(X 0 -X 2) / V} 2 - (X 0 -X 1) / V 1 ] ....................................... ( 5)

Next, in FIG. 3, ink droplets are recorded on the recording paper 10.
The main droplet 51 and the last satellite 5 when ejected with an inclination of θ with respect to 0 in the direction opposite to the moving direction of the carriage 13
The deviation of the landing position of the second recording paper 100 is obtained.

The velocity component of the moving direction of the carriage 13 is represented by "V ₃ -V ₃ '". Here, “V ₃ ′” represents a velocity component that is generated due to oblique discharge and is pulled in a direction perpendicular to the above-described V _1, and is represented as follows. V ₃ '= V ₁ · tan θ ………………………………………… (6) The landing position y ₁ of the main droplet 51 is y ₁ = (V ₃ −V ₁ tan θ) _{· (X 0 -X 1) /} V 1 ............... (7) dripping position y ₂ of the last satellite _{52, y 2 = (V 3 -V} 2 tanθ) · (X 0 -X 2) / V ₂ …………… (8)

Therefore, the deviation amount Δy ₁ of the landing position between the main droplet 51 and the last satellite 52 is Δy ₁ = y ₂ −y ₁ = [(V ₃ −V ₂ tan θ) · (X ₀ −X ₂ ) / V ₂ ]-[(V ₃ −V ₁ tan θ) ・ (X ₀ −X ₁ ) / V ₁ ] −y ₃ ………………………………………………………… …… (9)

Here, in FIG. 3, y ₃ in the equation (9) is not affected by the moving speed of the carriage generated at the time of oblique ejection, and the main droplet 5 already generated at the time of ejection.
1 is the difference between the landing positions of 1 and the last satellite 52 on the recording paper 100 (landing position deviation amount).

In actual ejection, the value is extremely small, but FIG. 3 is emphasized.

Further, when the ink droplets are ejected by inclining by θ in the same direction as the moving direction of the carriage 13, the velocity component in the moving direction of the carriage is represented by "V ₃ + V ₃ '",
“V ₃ '” is calculated from the equation (6) as “V ₃ ' = V ₁ · tan θ”.
Therefore, the landing position y ₁ of the main droplet 51 is y ₁ = (V ₃ + V ₁ tan θ) · (X ₀ −X ₁ ) / V ₁ (10) Last satellite 52 The landing position y _{2 of this} is y ₂ = (V ₃ + V ₂ tan θ) · (X ₀ −X ₂ ) / V ₂ ………… (11)

Therefore, the deviation amount Δy ₂ of the landing position between the main droplet 51 and the last satellite 52 is Δy ₂ = y ₂ −y ₁ = [(V ₃ + V ₂ tan θ) · (X ₀ −X ₂ ) / V ₂ ]-[(V ₃ + V ₁ tan θ) ・ (X ₀ −X ₁ ) / V ₁ ] -y ₃ ………………………………………………………… (12)

Here, equations (5), (9), and (12)
Therefore, the difference between the landing position deviation amounts of the main droplet 51 and the rearmost satellite 52 of the vertical and oblique ejection of ink droplets can be calculated as “Δy ₁ −Δ
If it is expressed by “y” and “Δy ₂ −Δy”, the amount of misalignment of the landing position is decreased or increased by the amount expressed by the following equation with respect to vertical ejection.

[0037] When the discharge inclined θ in the direction opposite to the carriage moving direction △ y ₁ - △ y = - _{[V 2 tanθ · (X 0 -X} 2) / V 2 -V 1 tanθ · (X 0 -X ₁ ) / V ₁ ] -y ₃ ……………………………………………………………… (13) From the result of equation (13), it is opposite to the carriage movement direction. The amount of deviation of the landing position between the main droplet 51 and the last satellite 52 when ejected at an angle of θ is larger than that in the case of vertical ejection.
It is found that the amount is small by the amount shown in the equation (13), and therefore the amount of deviation of the landing position between the main droplet 51 and the last satellite 52 decreases.

On the other hand, when the ejected inclined θ in the carriage movement in the same direction △ y ₂ - △ y = + _{[V 2 tanθ · (X 0 -X} 2) / V 2 -V 1 tanθ · (X 0 -X ₁ ) / V ₁ ] -y ₃ ……………………………………………………………… (14)

From the result of the equation (14), the amount of deviation of the landing position between the main droplet 51 and the last satellite 52 when ejected at an angle of θ in the same direction as the carriage movement direction is larger than that in the case of vertical ejection. It was found that the amount was large by the amount shown in (14), so that the main droplet 51 and the last satellite 52 were
The amount of misalignment of the landing position of is increased.

As described above, when the ink is ejected while being inclined in the direction opposite to the carriage movement direction, the landing position shift amount between the main droplet 51 and the tail satelliteite 52 is reduced, and the tail satellite 52 is placed in the main droplet 51. Since it is included, it is possible to improve the printing quality.

Therefore, in the above-described first embodiment, the first
The first moving orifice 14 and the second moving orifice 16 are set to be slightly inclined toward the opposite side (downstream side) with respect to the moving direction of the head body 5.
Alternatively, the second moving orifice 14 (or 16) is selectively set, and as a result, as described above, the landing position shift amount between the main droplet 51 and the tail satelliteite 52 is decreased, and the tail satellite 52 is mainly used. Since it is included in the droplet 51, it is possible to effectively improve the print quality,
In particular, in bidirectional printing, there is an advantage in that the landing positions of ink droplets in the forward direction and the backward direction are made constant to prevent vertical ruled line misalignment, thereby improving printing quality.

Here, in the embodiment shown in FIG.
When the operation is stopped, the opening portion of the fixed orifice 11 may be closed by the central portion R of the moving orifice member forming the moving orifice portion 12 described above.

Next, a second embodiment will be described with reference to FIGS. In the second embodiment shown in FIGS. 4A and 4B, the moving orifice 12 in FIG.
The second moving orifice 16 and the second moving orifice 16 are provided, whereas only the moving orifice 26 corresponding to the second moving orifice 16 is provided. And this FIG. 4 (A)
The second embodiment shown in (B) is configured so that the moving orifice 26 described above operates when the carriage 13 moves in the direction of arrow B. Other configurations are the same as those of the first embodiment.

FIG. 4A shows the operation state of the moving orifice 26, and FIG. 4B shows the operation state of the moving orifice 26.

Even in this case, when the carriage 13 moves in the direction of the arrow B, it is possible to obtain the same effect as the case of FIG. 1B described above.

Next, a third embodiment will be described with reference to FIG. In the third embodiment shown in FIG. 5, the fixed orifice 11 in each of the above-described embodiments is an orifice 31 having the same inclination as the moving orifice 26 in FIG. 4, and at the same time, the moving orifices 14 and 16 in each of the above-described embodiments.
The feature is that points 26 and 26 are excluded. The other structure is the same as that of the second embodiment described above.

Even in this way, the above-mentioned FIG.
In addition to having the same function and effect as the second embodiment shown in (B), there is an advantage that the structure is particularly simple and can be obtained at low cost.

[0048]

Since the present invention is constructed and functions as described above, according to the present invention, the ejection direction of ink droplets is set to be slightly inclined in the opposite direction to the moving direction of the carriage. It is possible to provide an ink jet recording head which is excellent in the past, in which it is possible to effectively prevent the ink scattering that occurs around the main droplets, and thereby to significantly improve the printing quality.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of an apparatus showing a first embodiment of the present invention, FIG. 1 (A) shows a state in which a carriage moves in one direction, and FIG. 1 (B) shows the carriage in the other direction. It is a figure which shows the state at the time of moving to the direction.

FIG. 2 is an explanatory diagram showing a state when ink droplets are ejected perpendicularly to a recording sheet.

FIG. 3 is an explanatory diagram showing a state when ink droplets are obliquely ejected onto a recording sheet.

FIG. 4 is a partial cross-sectional view of an apparatus showing a second embodiment, FIG.
FIG. 4A is a diagram showing a state when the carriage moves in one direction, and FIG. 4B is a diagram showing a state when the carriage moves in the other direction.

FIG. 5 is a partial sectional view of an apparatus showing a third embodiment.

[Explanation of symbols]

 1 Orifice Part 2 Flow Forming Member 2A Flow Path 3 Heating Resistor 3A Bubble 4 Thermal Head Substrate 5 Head Body 11,31 Fixed Orifice Part 12,22 Moving Orifice Part 13 Carriage 14 First Moving Orifice 16 Second Moving Orifice 26 Moving Orifice 51 Main Droplet of Ejected Ink 52 Last Satiterite 100 Recording Paper

Claims (3)

[Claims] 1. An orifice portion having an ink ejection port for forming an ink droplet, and an ink flow path forming member that supports the orifice portion and is integrated with the orifice portion.
In an ink jet recording head having a head main body including a thermal head substrate having a heating element for forming the ink droplets, an ink ejection direction of the orifice portion is set to a downstream side of a moving direction of the head main body. The inkjet recording head is characterized in that it is set in a slightly tilted state. 2. An orifice portion having an ink ejection port for forming an ink droplet, and an ink flow path forming member which supports the orifice portion and is integrated with the orifice portion.
An ink jet recording head having a head body including a thermal head substrate having a heating element for forming the ink droplets, wherein the orifice portion is provided on a fixed orifice portion and outside the fixed orifice portion. An ink jet recording head comprising a movable orifice portion and an ink discharge direction of the movable orifice portion set to be slightly inclined toward the downstream side in the moving direction of the head body. 3. An orifice portion having an ink discharge port for forming an ink droplet, and an ink flow path forming member which supports the orifice portion and is integrated with the orifice portion.
An ink jet recording head having a head body including a thermal head substrate having a heating element for forming the ink droplets, wherein the orifice section is provided on a fixed orifice section and outside the fixed orifice section. And a movable orifice portion, and the movable orifice portion is slightly movable in the opposite directions toward the downstream side in one of the reciprocating direction of the head body and the other movable orifice portion. An ink jet recording head comprising an orifice and a second movable orifice.