JP3062298B2 - Inkjet printer head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet printer head.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 6, a polyurethane foam (foamed body) 21 impregnated with ink is accommodated in a case 20 and the ink impregnated in the polyurethane foam 21 is stored in an ink reservoir 22.
When the ink was supplied to the ink, the solid particles contained in the ink and the air bubbles of the ink were removed by the filter 23, and the polyurethane foam 21 was impregnated every time the ink in the ink reservoir 22 was caused to fly from the nozzle of the thin-film resistance type printer head 24. There is an ink jet printer head that sucks ink by the negative pressure of the ink reservoir 22.

[0003]

FIG. 6 shows the structure of the polyurethane foam 21 because even if the amount of ink impregnated in the polyurethane foam 21 becomes small, the small amount of ink cannot be collected at one place. All the impregnated ink cannot be used up, which is uneconomical. It is also difficult to know the amount of ink impregnated in the polyurethane foam 21, that is, the remaining amount.

[0004]

According to a first aspect of the present invention, there is provided a first ink reservoir which communicates with the atmosphere and directly stores ink.
A reservoir second ink storing the ink has a nozzle at one end, an ink ejection means kicked set in the vicinity of the nozzle,
It has a supply port communicating between the first ink reservoir and the second ink reservoir , and is provided between the first ink reservoir and the upper part of the second ink reservoir , and at least the supply port is provided. A material whose inner surface has a contact angle with the ink exceeding 90 °
And a partition wall formed of a material.

In the following, the contact angle with the ink is 90
The property exceeding ° is called “ink repellency”.

According to a second aspect of the present invention, in the first aspect, the pressure equivalent amount due to the surface tension of the ink in the first ink reservoir at the supply port is P _S1 , and the ink in the first ink reservoir applied to the supply port is Let P _{1 be} the pressure, P _{S2 be the} pressure equivalent of the surface tension of the ink in the second ink reservoir at the nozzle, and P _{2 be} the ink pressure of the second ink reservoir applied to the nozzle, P ₁ + P ₂ <P _S1 <P ₁ + P ₂ + P
_The relationship was set as _S2 .

[0007]

According to the first aspect of the present invention, the inner surface of the supply port communicating the first ink reservoir and the second ink reservoir is in contact with the ink.
Since it is formed of a material having an angle exceeding 90 °, that is, an ink-repellent material, the weight of the ink in the first ink reservoir and the atmospheric pressure are usually determined by the surface tension of the ink at the supply port. To prevent ink from flowing out to the second ink reservoir. When the ink in the second ink reservoir is ejected by the ink ejection means, the internal pressure of the second ink reservoir is reduced, so that the ink in the first ink reservoir can be discharged from the supply port to the second ink reservoir. . Accordingly, the ink can be directly stored in the first ink reservoir, and therefore, the ink impregnated body such as a sponge can be omitted, and the ink can be used up without leaving the ink in the first ink reservoir. The remaining amount of ink in the first ink reservoir can be easily visually recognized.

The invention according to claim 2 is characterized in that P ₁ + P ₂ <P _S1 <P ₁
By the relationship + P ₂ + P _S2 , the pressure of the first ink reservoir, the pressure of the second ink reservoir, the amount of pressure corresponding to the surface tension of the ink at the supply port, and the amount of pressure corresponding to the surface tension of the ink at the nozzle. Can be adapted to the best conditions, so that in the normal time when printing is not performed, ink leakage from the first ink reservoir to the second ink reservoir is extremely effectively prevented by the supply port. After the ink is ejected from the nozzle, the ink in the first ink reservoir can be reliably supplied from the supply port to the second ink reservoir.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. 1 is a case. In this case 1, a first ink reservoir 2 and a second ink reservoir 3 are formed,
Between the first ink reservoir 2 and the second ink reservoir 3, a plate-shaped partition wall 4 formed of an ink- repellent member such as fluororesin is fixedly provided. 5 are formed. An opening 6 communicating with the atmosphere is formed on the upper surface of the first ink reservoir 2, and a nozzle plate 8 having a nozzle 7 is fixed to a lower end of the second ink reservoir 3. Further, on the side wall 9 of the second ink reservoir 3, a piezoelectric element 10 as an ink discharging means is provided. The piezoelectric element 10 is deformed together with the side wall 9 when a voltage is supplied through an electrode (not shown). And
The ink 11 is directly stored in the first ink reservoir 2, and the ink 11 is supplied from the supply port 5 to the second ink reservoir 3.

In such a configuration, the partition wall 4 having the supply port 5 for communicating the first ink reservoir 2 and the second ink reservoir 3 is formed of an ink- repellent member. The weight of the ink 11 in the first ink reservoir 2 and the atmospheric pressure can be supported by the surface tension of the ink 11 in the supply port 5 to prevent the ink 11 from flowing out to the second ink reservoir 3. A voltage is applied to the piezoelectric element 10 to deform the piezoelectric element 10 together with the side wall 9, reduce the volume of the second ink reservoir 2, and reduce the volume of the ink 1 in the second ink reservoir 3.
When 1 protrudes from the nozzle 7, the internal pressure of the second ink reservoir 3 decreases, so that the ink 11 in the first ink reservoir 2 can flow out of the supply port 5 into the second ink reservoir 3. Accordingly, the ink 11 can be directly stored in the first ink reservoir 2, and therefore, the ink impregnated body such as a sponge can be omitted and the ink 11 in the first ink reservoir 2 can be used up without being left. it can. Further, the remaining amount of the ink 11 in the first ink reservoir 2 can be easily recognized visually.

The supply port 5 is formed by plasma etching or chemical dry etching.
May be singular or plural. When the thickness of the partition wall 4 is such that the ink 11 in the first ink reservoir 2 cannot be supported, the sheet-like partition wall 4 has a high rigidity and an opening facing the supply port 5. A method of supporting with a plate material having the following is adopted.

As described above, the supply port 5 of the partition wall 4 is
Normally, the dropping of the ink 11 from the first ink reservoir 2 is prevented, and the dropping of the ink 11 to the second ink reservoir 3 is permitted according to the ejection amount of the ink 11 from the nozzle 7. The performance of the supply port 5 is mainly determined by the partition wall 4
Material (degree of ink repellency of supply port 5) and supply port 5
Depends on the diameter of

Here, P ₀ is the atmospheric pressure P _B is the air pressure in the second ink reservoir 3 θa is the advancing contact angle θr between the inner surface of the supply port 5 and the ink 11, and the reversal angle between the inner surface of the nozzle 7 and the ink 11 is When the contact angle P _S1 is equal to the pressure due to the surface tension of the ink 11 when the forward contact angle at the supply port 5 is θa (see FIG. 2), the contact angle P _S2 is changed when the receding contact angle at the nozzle 7 is θr. pressure equivalent amount of the surface tension (see FIG. 3) sigma reservoir first ink density g inks diameter ρ diameter d ₂ of the nozzle 7 of the supply port 5 the surface tension d ₁ gravitational acceleration h ₁ of the ink 11 Assuming that the height h2 of the ink 11 in the second ink reservoir ₂ is the height of the ink 11 in the second ink reservoir 3 and the height H from the nozzle 7 to the surface of the ink 11 in the first ink reservoir 2, no print signal is output. Sometimes, as shown in FIG. It is necessary to draw the meniscus of the ink 11 in the nozzle 7 inward.
For this purpose, the air pressure of the second ink reservoir 3 and the ink 11
Is set to a value smaller than the atmospheric pressure.
This relationship is represented by the following equation (1).

[0014]

(Equation 1)

[0015] As a result, the nozzle plate 8, ink
The property that the contact angle with is less than 90 ° ( hereinafter, this property,
Even in the case where the ink 11 is formed of a material having “ink affinity” , the state where the ink 11 is drawn from the nozzle 7 can be maintained, and the adhesion of the ink 11 to the recording paper can be prevented. Also, under normal circumstances, the ink 11 in the first ink reservoir 2 must not be dropped from the supply port 5 into the second ink reservoir 3. Here, the supply port 5 having ink repellency
In FIG. 2A, as shown in FIG. 2A, the ink 11 is projected downward because the pressure of the ink 11 acts downward, and the ink 11 is dropped until the advancing contact angle between the inner surface of the supply port 5 and the ink 11 becomes θa. Is prevented, but when θa is exceeded, FIG.
As shown in (b), the ink 11 in the first ink reservoir 2
Moves down. Therefore, in normal times, a condition according to the formula (2) is set in order to prevent the ink 11 from dropping from the supply port 5.

[0016]

(Equation 2)

Therefore, the following equation (3) is obtained from the equations (1) and (2).

[0018]

(Equation 3)

Next, when the ink 11 is ejected from the nozzle 7, the internal pressure is reduced.
The receding contact angle with 1 exceeds θr, and the meniscus of the ink 11 at the nozzle 7 is drawn inward as shown in FIG. At this time, if the air is sucked, the balance between the internal pressures of the first ink reservoir 2 and the second ink reservoir 3 changes, so the condition of the following equation (4) is set. P
_B ′ is the air pressure of the second ink reservoir 3 that has dropped at this time.

[0020]

(Equation 4)

In this state, in order to drop the ink 11 of the first ink reservoir 2 from the supply port 5 to the second ink reservoir 3, the following condition (5) is set.

[0022]

(Equation 5)

Then, Expression (6) is derived from Expressions (4) and (5).

[0024]

(Equation 6)

The equation (7) is obtained from the above equations (3) and (6).

[0026]

(Equation 7)

Here, assuming that the ink pressure of the first ink reservoir 2 applied to the supply port 5 is P ₁ and the ink pressure applied to the nozzle 7 is P ₂ , ρgh ₁ is replaced by P ₁ and ρgh ₂ is replaced by P ₁ Since it is replaced by ₂ , the following equation (8) is obtained.

[0028]

(Equation 8)

Therefore, by satisfying the condition (8), which is the condition described in claim 2, the supply of the ink 11 from the first ink reservoir 2 to the second ink reservoir 3 is performed accurately.

The accuracy of the holding action of the ink 11 and the dropping action of the ink 11 in the supply port 5 is determined by the pressure equivalent amount due to the surface tension of the ink 11 when the advancing contact angle is θa (90 to 180 ° ). The value of P _S1 is given by the following equation (9).

[0031]

(Equation 9)

As a result, the following equation (10) is obtained from the equations (7) and (9). However, the value of P _S2 is determined by equation (11).

[0033]

(Equation 10)

[0034]

[Equation 11]

Here, the actual value of the supply port 5 diameter d ₁ is obtained.

Where h ₁ = 26 mm, h ₂ = 3 mm, H
= 34 mm, g = 9.8 m / s ² , σ = 73 mN / m,
ρ = 1180 kg / m ³ , θa = 110 ° , θr = 20
° , d ₂ = 50 μm. Here, σ is the surface tension of water,
ρ is the density of water, θa is the advancing contact angle between the inner surface of the supply port 5 and water when the inner surface of the supply port 5 is made of a fluororesin, and θr is the contact angle of the nozzle 7 when the inner surface of the nozzle 7 is gold plating with good hydrophilicity. A receding contact angle between the inner surface and water was applied respectively.
This is because the characteristics of the ink 11 in question here are close to those of water. Thereby, the diameter d ₁ of the supply port 5 becomes 1
It is set to a value of 7 μm to 300 μm.

Next, modified examples of the partition wall are shown in FIGS. What is necessary for the partition wall is that at least the inner surface of the supply port 5 has ink repellency. Therefore, FIG.
As shown in (1), a member 12 such as glass having excellent ink affinity may be joined to one surface of the partition wall 4 formed of a material having excellent ink repellency on the first ink reservoir 2 side. In this case, when the ink 11 shook inside the first ink reservoir 2, the ink 11 in the ink affinity of the member 12 fits, mitigate the effect of vibration of the ink 11 is transferred to the vicinity of the supply port 5 Accordingly, it is possible to prevent the ink 11 from leaking from the supply port 5 in a normal state. The supply port 5 of the partition wall 4 and the opening 13 of the ink- philic member 12 can be formed by plasma etching or the like. Further, as shown in FIG. 5, the partition walls 4 parent Lee
When formed of a material having good ink repellency, the same object can be achieved by coating the lower surface and the inner surface of the supply port 5 with a film 14 having good ink repellency such as fluororesin.

[0038]

According to the first aspect of the present invention, there is provided a first ink reservoir which communicates with the atmosphere and directly accumulates ink, a second ink reservoir having a nozzle at one end for accumulating ink, and a vicinity of the nozzle. to a set vignetting ink ejection means, the first ink reservoir and the second ink reservoir between a supply port communicating with the first of these ink reservoir and the second ink reservoir
Before at least the inner surface of the supply port is provided between the upper
Since the partition wall is made of a material having a contact angle of more than 90 ° with the ink, the inner surface of the supply port connecting the first ink reservoir and the second ink reservoir is formed of an ink- repellent member. Therefore, normally, the surface tension of the ink at the supply port can support the weight and the atmospheric pressure of the ink in the first ink reservoir and prevent the outflow of the ink to the second ink reservoir, Also, when the ink in the second ink reservoir is ejected by the ink ejection means, the internal pressure of the second ink reservoir is reduced, so that the ink in the first ink reservoir flows out of the supply port to the second ink reservoir. This makes it possible to directly store the ink in the first ink reservoir, so that the ink impregnated body such as a sponge can be omitted and the ink in the first ink reservoir can be used up without being left. Bets can be, further it has the effect of such can be easily recognized visually the remaining amount of the first ink reservoir in the ink.

According to a second aspect of the present invention, in the first aspect, the pressure equivalent amount due to the surface tension of the ink in the first ink reservoir at the supply port is P _S1 , and the ink in the first ink reservoir applied to the supply port is Let P _{1 be} the pressure, P _{S2 be the} pressure equivalent of the surface tension of the ink in the second ink reservoir at the nozzle, and P _{2 be} the ink pressure of the second ink reservoir applied to the nozzle, P ₁ + P ₂ <P _S1 <P ₁ + P ₂ + P
_{Since the} relationship is set as _S2 , the pressure of the first ink reservoir, the pressure of the second ink reservoir, the pressure equivalent amount by the surface tension of the ink at the supply port, the pressure equivalent amount by the surface tension of the ink at the nozzle, Can be adapted to the best conditions, so that in the normal time when printing is not performed, ink leakage from the first ink reservoir to the second ink reservoir is extremely effectively prevented by the supply port. In addition, after the ink is ejected from the nozzle, there is an effect that the ink in the first ink reservoir can be reliably supplied from the supply port to the second ink reservoir.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional side view showing one embodiment of the present invention.

FIG. 2 is a partial longitudinal side view showing a state of ink at the supply port.

FIG. 3 is a partial longitudinal side view showing a state of ink in the nozzle.

FIG. 4 is a vertical sectional side view showing a modification of the partition wall.

FIG. 5 is a longitudinal sectional side view showing another modified example of the partition wall.

FIG. 6 is a longitudinal sectional side view showing a conventional example.

[Explanation of symbols]

 2 First ink reservoir 3 Second ink reservoir 4 Partition wall 5 Supply port 7 Nozzle 10 Ink ejection means

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B41J 2/045 B41J 2/055 B41J 2/175

Claims (2)

(57) [Claims] 1. A a reservoir first ink reserving directly the ink in communication with the atmosphere, the reservoir a second ink storing the ink has a nozzle at one end, ink ejection was kicked set in the vicinity of the nozzle Means, and a supply port communicating between the first ink reservoir and the second ink reservoir, provided between the first ink reservoir and the upper portion of the second ink reservoir , and at least the The inner surface of the supply port is the contact angle with the ink
An ink jet printer head comprising: a partition wall formed of a material having a diameter exceeding 90 ° . 2. The pressure equivalent amount of the ink in the first ink reservoir at the supply port due to the surface tension of the ink is P _S1 , the ink pressure of the first ink reservoir applied to the supply port is P ₁ , and the second pressure at the nozzle is fountain ink P _S2 pressure equivalent amount of the surface tension of the ink pressure reservoir said second ink applied to said nozzle as _{P 2, P 1 + P 2} <P S1 <P 1 + P 2 + P S2 the relationship 2. The ink-jet printer head according to claim 1, wherein the setting is made as follows.