JPS58187369A - Ink jet recording device - Google Patents

Abstract

PURPOSE:To make it possible to inject an ink by a simple constitution and operation, by providing an ink steady flow generating means and a pressure varying means in a fine pipe passage having an ink injection port provided to the intermediate part to emit and stop ink liquid droplets in accordance with the variation in pressure. CONSTITUTION:An ink is flowed to a second ink chamber 2 from a first ink chamber 1 by operating a pressure pump so as to generate an ink stream in a fine pipe 3. An electro-mechanical converter element such as a piezo-electric element is arranged to the downstream side of said fine pipe 3 while the volume of the downstream side part of the fine pipe 3 is abruptly reduced by the electric signal from a printing control circuit and, by the rising in pressure resulting therefrom, ink liquid droplets are emitted from an ink emitting port 4 provided to the intermediate part of said fine pipe 3. In addition, even if a heat generating resistor is arranged in place of the electro-mechanical converter element 12 and the ink is subjected to abrupt heat expansion by the abrupt heat generation due to an electric signal, similar action is obtained. Therefore, an on-demand type ink jet recording apparatus can be realized by a simple constitution and operation.

Description

[Detailed description of the invention] The present invention discharges liquid ink in response to electrical signals.

Regarding an inkjet recording device that is stopped, the present invention provides an inkjet recording device based on an unprecedented new principle.

FIG. 1 is a sectional view for explaining the basic principle of an ink jet recording apparatus according to the present invention. A first ink chamber 1 and a second ink chamber 2, which are provided with a relative pressure difference, are communicated with each other by a thin tube 3, and an ink discharge hole 4 is perforated in the middle portion of the thin tube 3. . Here, the first ink chamber 1 and the second ink chamber 2 are not necessarily necessary in principle, but are provided to simplify the explanation.

When the ink pressure in the first ink chamber 1 is set as 'ff: P1, the ink pressure in the second ink chamber 2 is P2, and Pl>P2, the ink in the first ink chamber 1 is When such a flow of ink occurs in the thin tube 3 that flows into the second ink chamber 2 through the ink, the flow rate of the ink inside the thin tube 3 and the above-mentioned pressure P1. The ink pressure P5 of the ink discharge port 4 increases by 1j depending on the values of P2 and the like. When this ink pressure P3 is a sufficiently large value compared to atmospheric pressure, the ink in the first ink chamber 1 flows into the second ink chamber 2 through the thin tube 3, and the ink is ejected. Exit 4
It blows out into the outside air. Conversely, when the ink pressure P5 is a sufficiently small value compared to atmospheric pressure, the ink in the first ink chamber 1 passes through the thin tube 3 to the second ink chamber 2.
At the same time, air flows into the ink discharge port 4 and flows into the second ink chamber 2. ,however,
If the ink pressure Ps k is set to a value almost equal to the atmospheric pressure, the ink in the first ink chamber 1 passes through the entire thin tube 3 and flows into the second ink chamber 1 while the ink is retained in the ink discharge [14]. Flows into the ink chamber.

In the present invention, in the configuration shown in FIG.
A state in which the ink flows only into the second ink chamber 2, a state in which the ink flows into the second ink chamber 2 and is ejected into the outside air through the ink discharge LL14, or a state in which the ink is ejected only into the outside air can be determined using electrical signals. ) The liquid ink is ejected and stopped from the ink ejection port 4 by switching the means.

Various methods can be considered for the means related to the above-mentioned electric signals, and the details will be described later. Here, in order to better understand the present invention, the ink pressure p1. p2. A detailed explanation will be given regarding the relationship of P5.

Since the first ink chamber 1 and the second ink chamber 2 are sufficiently wider than the Al tube 3, the ink flow velocity can be ignored, and the ink flow velocity in the thin tube 3 is assumed to be V. Since the pressure loss in the thin tube 3 is proportional to the flow velocity V of the ink inside the thin tube 3, P+ = P2 + Kl) --('
1") In general, the constant K in the formula 90 viscosity P per unit length of thin tube 3
I:, can be considered as a coefficient. Therefore, if the length of the thin tube 3 from the first ink chamber 1 to the ink discharge port 4 is kl, and the length of the thin tube 3 from the ink discharge port 4 to the second ink chamber 2 is 42, then P, -he, v =p3+' ρv2=P5+kj? z
v・＋・＋＋・.

is established from Bernoulli's equation. (However, ρ is E・′
It is the density of ri. ) +3) If you organize the 戊, you will get 11 points. Therefore, P, I P21 e, + 4+ k+ P so that the right side of equation 0 is 0
The value of P3 can be set to 0 depending on the value f selected.

(→1. Since there are many variable parameters in the formula,
There are relatively few restrictions on the conditions for satisfying P50. For example, the pressure P2 in the second ink chamber 2 can be lower than the pressure P1 in the first ink chamber 1. It can be set to a value of 0, and even if the value is of either sign, there are conditions that satisfy ■ and ■.

(2) As an example of a condition that satisfies the formula 0, P2=o.

Considering the case of 1,=12=,l, when Pl- is 212/ρ, P5-0 holds true. That is, l and ρ are fixed values depending on the physical properties of the ink and the shape of the thin tube 3, and the pressure P+ in the first ink chamber 1 is set to a value corresponding to the above fixed value. By this, P520 can be realized.

Also, for other examples, Pl = P+ r 1!1=
42-shi (in the case of 1, P5-0 holds true when Pl-2 is 212/ρ, and furthermore, p2=P,/2
, l, -122i, n, p3=o holds true when Pl-24 is 212/ρ, and similarly, the pressure P1 in the first ink chamber is set according to the physical properties of the ink and the shape of the thin tube 3. By setting this, the pressure at the ink ejection port 4 can be set to P50, and the ink meniscus generated at the ink ejection port 4 can be kept completely stable.
By appropriately setting the values of Pit Pl, k, and β, P5 can be made equal to 01, that is, the inlet [F force. This situation occurs because although there is a high-speed ink flow n in the thin tube 3 caused by the pressure difference between the first ink chamber 1 and the second ink chamber 2, the pressure near the ink discharge port 4 is large. The ink is at rest in the ink ejection port 4 at a pressure equal to the atmospheric pressure, and even though there is energy inside the thin tube 3, this energy causes the ink to be ejected tI! It can be said that it is in a state where it is not used for the ejection force of ink liquid from fO4.

The invention defines such a state as a steady state during non-recording,
During recording, the ink liquid is ejected from the ink ejection ports 4 and 9 by effectively utilizing the latent energy contained within the thin tube 3, and its basic principle is based on two factors. . One of them is the viscous resistance in the part of the thin tube 3 that leads from the ink discharge port 4 to the first ink chamber 1, and the large viscous resistance in the part of the thin tube 3 that leads from the ink discharge port 4 to the second ink chamber 2. The potential energy is converted into the ejection energy of the ink liquid by changing the size or the ratio.
Eli ink causes pressure fluctuations in the ink contained in one or both of the part of the thin tube leading to the ink chamber 1 and the part of the thin tube 3 leading from the ink discharge port 4 to the second ink chamber 2. The pressure of the ink near the ejection port 4 is increased to P5', and the flow of ink in the thin tube 3 is converted into the ejection force of the ink liquid from the ink ejection port 4.In other words, the present invention has a principle driving means. There are two methods: one that changes viscous resistance and one that causes pressure fluctuations.
Ink liquid is ejected by one or both of these means.

In order to provide a detailed explanation regarding the means for changing the viscous resistance mentioned above, in equations (1) and (2), ke = αko, k12 = βk.

Assuming a state where
/) Assume that f can be changed. For further simplicity, Pl
Considering the case of -0, Pl = 4 kO/ρ must be satisfied from the condition of α = t no 1 when p5-o, so (,4) l ■ formula P5 is a function of α and β. And here, if α is unchanged and β is changed by α-1, P5Uβ
For a change in the height of the curve of FIG.

On the other hand, if β does not change and β=1, and α changes, then fr
K is a function of P5ba as shown in Figure 2.
Ru. In this case, P5 has a 19 large value.
-3, the maximum value P, /sq is taken.

Therefore, in this case, rather than changing α, β′4−′
It can be seen that it is more efficient to compare the trees. That is, in this embodiment, the field for changing the viscous resistance is
By providing means for increasing the total viscous resistance of the thin tube 3 located on the downstream side of the wick flow, i') is increased;
艮<P3 can be increased.

As is clear from the explanation using the above specific numerical examples, the ink pressure PstK near the ink ejection port 4 can be changed by means of changing the viscous resistance in the thin tube 3, so that the ink pressure Ps'c can be suddenly increased. If the viscous resistance is changed to a positive value and a sound is generated, the flow of ink in the thin tube 3 is converted to the outflow force of the ink liquid from the ink ejection port 4, and the droplet is ejected or flies. can be done.

In addition, in the above-mentioned specific numerical example, it is better to provide the viscous resistance changing means in the part of the thin tube 3 located on the downstream side of the ink flow, because the viscous resistance changes in the part of the thin tube 3 located on the upstream side of the ink flow. This was more effective than providing a means, but this also holds true in other examples and is a common phenomenon.

Next, a detailed explanation will be given regarding means for causing pressure fluctuations within the thin tube 3.

The phenomenon that causes pressure fluctuations in the thin tube 3 can be approximately explained by the phenomenon that changes the ink pressure P1 in the first ink chamber 1 and the ink pressure P2' in the second ink chamber.

Again, for simplicity, let l be (!2=l/2, and P2
If Ps-0 holds true when -o, P, = 2g/ρ, then from formulas ■ and ■, and when V is eliminated, Pl(P, + P2)/2-ρ(P+ P2f/
2 to 212......■ and -1, 0, Here, P2 0''''C does not change, but Pl changes)] Then, the ■ formula is Ps=P, (k2e2−ρP+ )/2 to 212
＋＋＋＋＋0 and i4, drawn in a graph like Figure 3 a, ns P+ is steady state < P, = k2 (
12/ρ), the value of P5 is 9.
, P1=k2J? When 2/2ρ, the maximum value is 2e2/8
It becomes ρ.

By the way, Pl does not change and P, -"w2 (12/ρ), and if P2 is a variable ratio, then in equation (■), Ps -= P2 (3 to 2jl"-ρP2)/2 2
〆 ・・・・・・■ and 1) Draw a graph like the one in Figure 3. When P2 rises from the robust state (p2-o), P3 increases and P2 = -3 by 212/2ρ
When the maximum value 9 becomes 2 e2/4ρ, 0.
It is more efficient to change P2 than to change P2.
sk can be increased. In particular, the increase in Ps when P2 is changed is as follows:
The rise within 22 V becomes a much larger value.

In this way, in the thin tube 3, the ink pressure Psk near the ink ejection port 4 can be increased by means of causing pressure fluctuation, and the di-ink liquid can be ejected from the ink ejection port 4. In this case, generally speaking, if the means for generating this pressure fluctuation is located in the thin tube 30 portion on the downstream side of the ink flow, the efficiency of the means in the thin tube 3 portion on the upstream side of the ink flow is better. , a pressure difference is created between the first ink chamber 1 and the second ink chamber 2, and the ink Me is introduced into the thin tube 3.
1 is an example of a device for generating tl-. The ink stored in the ink reservoir 8 is pressurized by the pressure pump 7 and sent to the first ink chamber 1 via the filter 6.
The ink pressure in the first ink chamber 1 is kept at a constant value. An ink flow corresponding to the ink pressure in the first ink chamber 1 is generated in the thin tube 3 and flows into the second ink chamber 2. FIG. 4 shows an example where the ink pressure in the second ink chamber 2 is equal to 01, that is, the atmospheric pressure, and a part of the second ink chamber 2 or a part of the ink reservoir is connected to a passage ( (not shown), the ink pressure in the second ink chamber 2 can be set to zero.

In addition, when setting the pressure of the second ink chamber 2 to negative pressure, this can be done by providing a suction pump between the ink reservoir 8 and the second ink chamber 2. If the second pressure is set to a positive pressure, this can be done by providing a passage with a large viscous resistance between the ink reservoir 8 and the second ink chamber 2.

By the way, when the ink pressure in the first ink chamber 1 and the pressure in the second ink chamber 2 are in a steady state, the ink is discharged.
The pressure must always be kept constant so that the ink pressure in the vicinity is zero. However, there may be cases where it becomes difficult to maintain the ink pressure near the ink discharge port 4 due to changes in the performance of the pressure pump 7, changes in the ink supply system such as clogging of the filter 6, or changes in the physical properties of the ink due to temperature. A meeting can occur.

FIG. 6 shows an embodiment of a configuration that can eliminate such difficulties. That is, if the pressure sensor 9 is installed near the ink discharge port 4 on the inner wall of the thin tube 3, the η mouth pressure pump 7, for example, is controlled by the signal from the pressure sensor 9, and the pressure detected by the pressure sensor 9 is only in a steady state. 0 to maintain the ink meniscus generated at the ink ejection port 4 in a constant shape in a steady state.

Next, for example, in the configuration shown in FIG. 4, a process in which the pressure pump 7 starts and reaches a steady state, and a process in which the pressure pump 7 stops and changes from a steady state to a stopped state will be fully explained. The ink pressure P2 in the second ink chamber 2 is 0
Assuming that, when the ink pressure in the thin tube 3 near the ink discharge [ ] 4 becomes O, the ink pressure in the first ink chamber 1 must be M2/ρ, as is clear from the diagram in Figure 3. Must be n.

That is, in the configuration of FIG. 4, the first. The ink pressure in the second ink chambers 1 and 2 is p2:Ol
If p, = is not 21J2/P, then z. However, when the pressure pump 7 starts, the ink pressure))T'
+ gradually increases to 212/p, and when the pressurization stops, the ink pressure P+ u k2A! 2/
It gradually decreases from ρ and reaches 0. In such a situation, as is clear from FIG. Unnecessary ink is ejected from the ink ejection port 4. In order to reach a steady state through a process that eliminates such unnecessary ink ejection, the pressure p21 of the second ink chamber 2 must be reduced to, for example, negative pressure. Select the conditions that will cause the ink discharge port 4 to
The pressures P, , P2 of the first ink chamber 1 and the second ink chamber 2 must be selected so that the pressure changes such that the pressure in the vicinity becomes Ps'fr:O and then reaches a steady state. No. However, such a device has the drawbacks of a very complicated structure and delicate control of the ink pressure.

FIG. 6 shows an embodiment for eliminating such drawbacks. That is, on the front of the inkjet printer 1 head 11,
A cap member 10 that is movable relative to the inkjet head 11 is installed, and the time from the start of the pressure pump 7 to the steady state, the stop of the pressure pump, and the amount of ink in the thin tube 3 are fixed. The cap member 10 is in close contact with the front surface of the inkjet head 11 and closes the ink ejection port 4 during a time period including at least the time period 1 when the flow stops. The cap member 1o needs to be movable relative to the ink shared head 11 so that the inkjet head 11 can be disposed opposite the recording material in the steady state. The cap member 10 is in close contact with the front surface of the inkjet head 11 while the pressure P3 near the ink discharge port 4 becomes positive due to starting, stopping, and stopping of the pressure pump 7, so that the cap member 10 closes the front surface of the ink jet head 11 and closes the ink discharge port 4. , ink ejection port 4 due to ink drying
In order to avoid clogging of the inkjet head 11, it is also effective to keep the cap member 10 in close contact with the inkjet head 11 at all times when not in use. Furthermore, it is also an effective means to control the movement of the cap member 10 by means of a control unit 9 shown in FIG.

That is, for example, when the pressure pump is started, the sensor 9 detects that the pressure P3 in the vicinity of the ink discharge port 4 has become 0 (the steady state has been reached), and the cap material 1o'i is separated from the front surface of the inkjet head 11. If this is done, the timing of the movement of the cap member 10 will not be correct and the cap member 10 will not fall off, and troubles are less likely to occur.

Above, we have explained the principle for causing ink to flow in the thin tube 3 and for making the pressure near the ink discharge port 4 zero in a steady state, and for discharging and stopping the di-ink liquid from the ink discharge port 4. , the first ink chamber 1 and the second ink chamber
C) The ink chamber 2U is not necessary, and the essential structural conditions are to cause ink flow in the thin tube 3 having the ink discharge port 4, and to make the pressure near the ink discharge port 4 zero in a steady state. It is. Therefore, in the case of flJ, there is a structure in which the ink piping for supplying ink from the blade pressure pump 7 to the head is directly connected to the thin tube 3, or a structure in which the other side of the thin tube 3 is directly connected to the ink tube communicating with the ink tank 8. Of course, a structure in which means corresponding to the first ink chamber 1 and second ink chamber 2 are arranged outside the inkjet head 11 is also possible.

Next, specific means for changing the viscous resistance of ink flow within the thin tube 3 or causing pressure fluctuations in the ink within the thin tube 3 will be explained.

FIG. 7 shows a first embodiment of this means. An electromechanical transducer 12 such as a piezo element is connected to the ink ejection port 4.
is perforated and fixed to the member 13, and the thin tube 3 is caused by the displacement of the electromechanical transducer 12 caused by the electric signal.
The structure is such that the volume of one portion of the structure can be changed.

The electric machine-like conversion element 12 is provided in a portion of the thin tube 3 located on the downstream side of the ink flow, as described in FIG. 2 or 3. The conversion element 12 in the electric machine 4 suddenly reduces the entire volume of the downstream portion 11i110 of the thin tube 3 by an electric signal. At this time, the downstream 1i111f of the thin tube 3
l? - If a sudden pressure rise occurs, the pressure rise force as shown by the curve in Figure 3;
Occurs nearby. Furthermore, at the same time, the diameter of the downstream +1111 part of the thin tube 3 becomes smaller, so the viscous resistance increases in this part, and for example, the pressure rise in the curvilinear force (e as shown) in Figure 2 B increases near the ink discharge port 4. In other words, in the configuration shown in FIG. 7, a sudden rise in pressure and a rise in viscous resistance are simultaneously caused in the downstream portion 1u11 of the ink flow in the thin tube 3, and as a result, the pressure near the ink discharge port 4 fs5 is suddenly increased. raised to;
The ejection force of the ink flowing through the thin tube 3] and the ink H, K from the ink ejection port 4 is converted to V·2.

Figure 8 shows an inkjet printer based on the same principle as Figure 7! The electromechanical transducer 14 has a cylindrical shape and constitutes the entire portion of the thin tube 3 on the downstream side of the ink flow. By applying an electric signal to the electromechanical transducer f.14, it is possible to displace the ink so that ff of it rapidly contracts. can be discharged and stopped.

FIG. 9 shows another embodiment of the invention. Inside the thin tube 3, an ink flow occurs from the first ink chamber 1 to the second ink chamber 2, and in a steady state (no electric signal applied), ink near the ink discharge port 4 flows. The pressure is adjusted to a value close to pressure (0), which is equal to atmospheric pressure. A heating resistor 16 is provided on the inner wall of the thin tube 3 located on the downstream side of the ink flow. This heating resistor 16 is easily formed from a material mainly composed of silicon or tantalum.

When an electric signal is applied to the heating resistor 16 and a current flows,
The heating resistor 16 rapidly generates heat, increasing the temperature of the ink flowing inside the thin tube 3. The fl-ink that causes a rapid temperature rise increases its volume due to rapid thermal expansion.
A pressure wave is generated in the part of the thin tube 3 on the downstream side of the ink.

Furthermore, when the temperature of the ink exceeds a temperature close to the boiling point of the ink, bubbles 16 are generated which are made of ink vapor or air dissolved in the ink. The state in which the bubbles 16 are generated is shown in FIG. 10. The rapid growth of the bubbles 16 further causes a pressure wave of a magnitude l, while the interfacial force generated by the bubbles 16 inhibits the flow of ink within the thin tube 3. It acts as a resistance force and moves.

In this way, in the inkjet head using the heating resistor 16 as the driving force, the ink flow is caused by two factors: the pressure increase in the thin tube 3 due to thermal expansion and the generation of the bubbles 160, and the resistance force of the bubbles 16 themselves against ink flow. This is to increase the ink pressure near the ejection port 4 and convert the energy of the ink flow in the thin tube 3 into the ejection force of ink droplets from the ink ejection port 4, as explained in FIGS. 2 and 3. As is clear, the inkjet head is also a very efficient inkjet head.

FIG. 10 shows that due to the generation of air bubbles 16, the ink liquid ii+1
7 shows the state in which it is being ejected, and ink f night drop 17
The ejection is continued until the bubble 16 flows out through the thin tube 3 into the second ink chamber 2 or disappears within the thin tube 3, and then stops. Therefore, the response characteristics of the inkjet head shown in FIGS. 9 and 10 depend on the time required for the bubbles 16 to generate, disappear, or flow out, and this depends on the heat generation characteristics of the heating resistor 15 and the amount of ink flowing inside the thin tube 3. It is determined by the physical properties, the flow rate of the ink flow, etc.

In general, with inkjet heads that use the energy of bubble generation, the problem is how quickly all the generated bubbles can disappear, and the heat generated before the bubbles disappear encourages the generation of more and more bubbles, eventually making it impossible to eject ink liquid. becomes. However, in the configuration of the present invention, the generated bubbles do not need to be separated or completely extinguished, but only need to flow out through the thin tube 3 into the second ink chamber 2, and the physical properties of the ink are extremely limited.・It is clear that the ejection response can be significantly improved.

FIG. 11 shows still another embodiment of the present invention, which is characterized by utilizing the electrorheological effect of liquid.

The electrorheological effect is a phenomenon in which the viscosity of a liquid changes when a voltage or electric field is applied to the liquid, as seen in many protein solutions in which solid powders are dispersed. Regarding this n')spAp=26(1+1/Xη.i(!'D
/2rr)2'': The relational expression of J is known n.Here, a
id solid powder particle radius, η. and D are the viscosity and dielectric constant of the dispersion medium, X is the electrical conductivity of the dispersed phase,
ψ is the volume ratio of the dispersed phase to the total volume of the dispersed system, η3. is the specific activity rate 1. S represents the electrokinetic potential. It is clear from this relational expression that there is a positive correlation between 3, which corresponds to the voltage, and the specific activity ratio ηsp, and therefore the viscosity increases as the voltage increases.

The electrorheological fluid is generally composed of a suspension of micron-sized solid powder.

Moreover, it must also have suitability as an ink. For example, when carbon blank is used as a solid powder, it is known to exhibit a high electrorheological effect and is also extremely effective from the viewpoint of density on recording paper. In addition, electrorheological fluids include those in the form of non-imitation particles, such as metal sorb solutions, and this is not an invention.
It is effective for all electrorheological fluids.

In the example in Figure 11, it is an electrorheological fluid like the one above! 7 is flowing in the thin tube 3, and the ink discharge port 4
The pressure in the vicinity is almost atmospheric pressure, and the ink is stably maintained within the ink ejection port 4. A pair of electrodes 18 are provided on the inner wall of the thin tube 3 on the downstream side of the ink flow (the inner wall between the ink discharge port 4 and the second ink chamber 2).
A high voltage (several tens to hundreds of volts) is applied depending on the signal. When a high voltage is applied to the electrode 18, the electric field caused by this voltage instantly increases the viscosity coefficient of the ink on the downstream side of the ink flow in the thin tube 3, increasing the flow resistance on the downstream side of the ink flow. As explained in FIG. 2, ink liquid is ejected from four ink ejection ports and nine ink ejection ports. Then, when the electric field is removed, the original state is instantaneously restored and the ejection of ink liquid from the ink ejection ports 4 is stopped. In the case of the configuration shown in FIG. 11, when the volume expansion and contraction of the liquid when an electric field is applied can be ignored, the ink liquid is ejected and stopped only by the change in viscous resistance in the thin tube 3.

FIG. 12 shows an embodiment of a multi-nozzle inkjet head utilizing the principle of the invention.

Thin tube 3-1.3-2. 3-n are arranged at equal intervals, and each ink discharge port 4-1, 4-2, . ...4-n is not provided. One end of each of the thin tubes 3-n commonly communicates with the first ink chamber 1, and the other end commonly communicates with the second ink chamber 2. Pressurized ink is supplied to the first ink chamber 1 through an ink supply path 19, and a thin tube 3-1
．． 3-2. . . . 3-n is caused to flow, and the ink is recovered from the ink recovery path 2o of the second ink chamber 2. In a steady state where no electric signal is applied t'L, the ink pressure in the first ink chamber 1 and the second ink chamber 2, the flow rate of ink in the thin tube 3, etc. -2. . . . The ink pressure near 4-n is set to be approximately equal to atmospheric pressure. Thin tube 3-1.3-2. ...3-n
A heating resistor 15-1.1 is provided on the downstream side of the ink flow.
5-2,...16-n are installed, and the capillary tubes 3-1.3-21...3- are installed by electric signals.
Make the ink in n generate heat.

In the configuration shown in FIG. 12, ink droplets are ejected and stopped according to the same principle as explained in FIG. 9 or 10, but a plurality of heating resistors 15-1, 15-2
．． ...16-n each generates heat independently n1 ink ejection ports 4-1, 4-2.・・・・・・4-n Since the ink droplets are ejected from the ink ejection port 4-1.4-
2. ...4-High speed recording becomes possible in proportion to the number of n.

As described in detail above, the present invention generates an ink flow in a capillary passage having an ink ejection port in the intermediate portion, and is equipped with a part of the capillary passage to reduce the viscous resistance of the ink flow in the capillary passage. The pressure of the ink near the ink ejection opening in the V-tube passage is changed by a means for changing the pressure or a means for causing a pressure fluctuation in the ink in the capillary passage, and this change in pressure causes the ink to be ejected from the ink ejection opening and then stopped. Specific driving means include a method using mechanical vibration using an electromechanical transducer as shown in FIGS. 7 and 8;
Possible methods include a method that utilizes the temperature rise of the ink caused by a heating resistor as shown in FIGS. 9 and 10, or a method that utilizes the electrorheological effect as shown in FIG. 11. In addition,
Other methods include energizing the ink to raise its temperature, discharging the ink in the ink to heat it or foaming it, applying high frequency to the ink to boost or foam it, and irradiating the ink with a laser beam or electron beam to ink the ink. A method of heating or foaming can also be applied. 1. If an inkjet recording device having such a configuration is used, an on-demand inkjet recording device can be realized with an extremely simple configuration and operation.

[Brief explanation of the drawing]

FIG. 1 is a sectional view for explaining the principle of an inkjet recording apparatus according to the present invention, and FIGS. 2 and 3 a and b
is a pressure characteristic diagram for explaining the operation of the inkjet recording apparatus shown in FIG. 1, and FIG. 4 is a block diagram showing an ink supply system of the inkjet recording apparatus according to an embodiment of the present invention.
6(2) is a cross-sectional view showing an example of the configuration when the ink meniscus shape is kept constant in the inkjet recording device according to the present invention, and FIG. 7 to 9 are cross-sectional side views showing embodiments of the inkjet recording apparatus according to the present invention, and FIG. 10 is a sectional view for explaining the operation of the embodiment of FIG. 9. 11 is a sectional view showing still another embodiment of the inkjet recording apparatus according to the invention, and FIG. 12 is a partially sectional perspective view of the inkjet recording apparatus according to the invention having a multi-head configuration. 1... 10th ink chamber, 2... 2nd ink chamber, 3... Thin tube, 4... Ink discharge port, 6... ... Filter, 7 ... Pressure pump, 8 ... Ink reservoir, 9 ...
・Pressure sensor, 1o...Cap member, 11・
...Inkjet head, 12, 14...
...Electromechanical conversion element, 13... Member, 16.
...Heating resistor, 16...Bubble, 17.
...Ink droplet, 18... Electrode, 19.
. . . Ink supply path, 20 . . . Ink recovery path. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 ((1) Figure 3/4) Figure 4 Figure 7 Figure 5 Figure 6 Figure 8 Figure 9 Guan 10 Figure 11 Figure 12

Claims (1)

Scope of Claims: (1) A capillary passage having an ink discharge port in an intermediate portion, a means for generating a steady flow of ink within the capillary passage, and a total pressure of ink near the ink discharge port within the capillary passage. What is claimed is: 1. An inkjet recording apparatus, comprising: means for varying ink pressure, and ejecting and stopping ink droplets according to fluctuations in ink pressure. (2) The means for moving the ink pressure near the ink ejection opening is at least one of means for changing the viscous resistance of the ink flow disposed in a portion of the thin tube passage or means for causing pressure fluctuations of the ink. An inkjet recording apparatus according to claim 1, characterized in that: ((2) One end of the thin tube passage communicates with a first ink chamber having a high pressure M, and the other end communicates with a second ink chamber having a low pressure M. Claim 1) The inkjet recording device according to claim 2. (4) The inkjet recording device according to claim 2, wherein the means for changing viscous resistance or the means for generating pressure fluctuation is an electromechanical transducer. (6 ) The inkjet recording device according to claim 2, wherein the means for changing viscous resistance or the means for generating pressure fluctuation is a heating element. +6) The means for changing viscous resistance or the means for generating pressure fluctuation sound. 1. The ink jet recording apparatus according to claim 2, wherein the means for applying a high voltage is a high voltage applying electrode, and the means for applying a high voltage is an electrorheological fluid. ('7) The second aspect of the present invention is characterized in that the means for changing the viscous resistance or the means for generating pressure fluctuations is provided on the downstream side of the ink flow of the ink discharge 11 of the thin tube passage. Recording device described in section. (8) The ink jet recording apparatus according to claim 1, wherein a pressure sensor is provided near the ink ejection opening of the thin tube passage. (9) Claim 1 is characterized in that a cap member is provided that closes the ink discharge [1] at least during a period including the start and stop of ink flow in the thin tube passage.
The inkjet recording device described in Section 1.