JPS636356B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus that performs recording by ejecting liquid from an ejection port by the action of thermal energy. Non-impact recording methods, especially the so-called inkjet recording methods, produce almost no noise during recording.
Recently, research and development have been actively conducted on this method because it has various advantages such as being capable of high-speed recording and being able to perform recording on plain paper without the need for special fixing treatment. On the other hand, the equipment used for this recording method is
A colored liquid called ink is ejected,
A recording head is used that has an ejection port (ejection orifice) for ejecting liquid droplets and an inlet for liquid to flow into. And in the recording head,
There are various types depending on the method of discharging liquid from the discharge orifice. For example, the liquid may be supplied from an external liquid supply tank into the liquid chamber under pressure or through natural supply (such as supply using capillary action). There is a type that applies voltage between the liquid in the chamber and an electrode installed in front of the discharge orifice, and electrostatically discharges the liquid from the discharge orifice. . Although this type of recording head has a simple structure, the overall system configuration is complex, and the disadvantage is that a high degree of skill and precision are required for electrically controlling the generation of droplets and the direction of their flight. Another drawback is that it is difficult to create a multi-orifice recording head, which is essential for high-speed recording. Another type of recording head uses a mechanical vibration method to eject liquid and fly it as droplets. That is, this type of device changes the volume of the liquid chamber into which liquid is supplied in accordance with a signal by mechanical vibration of a piezo vibrating element.
This causes the liquid to be ejected as droplets. Its specific structure is USP3747120, IEEE
Transactions on Industry, Applications Vol.
It is disclosed in IA-13, No. 1, January/February 1977, etc. The entire system structure of such a recording head is extremely simple. However, since droplets are generated by the mechanical vibration of the piezo vibrating element, there are problems with responsiveness during high-speed recording, and there are problems with processing such as forming the liquid chamber and installing the piezo vibrating element. For reasons such as the difficulty of miniaturization, it is extremely difficult to create high-density multi-orifices, and it is difficult to achieve high-speed recording. As described above, many conventional recording heads have problems that need to be solved in terms of structure, processing, high-speed recording, high-density multi-orifice, and overall system configuration. have. The present invention has been made in view of the above points, and it is an object of the present invention to provide an apparatus that is excellent in ejection efficiency, ejection response, or ejection stability, and long-term continuous recording performance.
Another object of the present invention is to provide an apparatus capable of high-speed recording. Yet another object of the invention is to provide a high density multi-orifice type device which is easy to manufacture and extremely practical. The liquid jet recording device of the present invention includes an ejection opening for ejecting liquid in a predetermined direction to form flying droplets, and a liquid path communicating with the ejection opening and having a bending part, where the bending part A heat acting part is a part where thermal energy generated from a heating element acts on the liquid to cause a state change due to heat and form flying droplets of the liquid to be ejected from the ejection port based on the state change. an included angle Ψ formed by a vector on an axis parallel to the discharge direction of the liquid and a vector on a line perpendicular to the heat generating surface passing through a point where the vector or its extension intersects the heat generating surface of the heat generating element; is 45° or less, and is electrically connected to the heating element, and includes a signal supply means for supplying a drive signal to the heating element to drive the heating element to discharge liquid in a predetermined direction. characterized by things. In the recording device of the present invention configured in this way,
Thermal energy is effectively used to eject and fly liquid in the form of droplets, and ejection efficiency, ejection response, and long-term continuous recording performance are significantly improved. Furthermore, in the multi-orifice configuration, there is virtually no mutual influence between droplets discharged from each orifice, resulting in excellent discharge stability. Furthermore, since the recording apparatus of the present invention has an extremely simple structure and can be easily microfabricated, the recording head itself can be made much smaller than conventional ones. Furthermore, due to its simple structure and ease of processing, it is extremely easy to realize high-density multi-orifice formation, which is essential for high-speed recording, and it is extremely easy to take out the electrodes to drive the heating element. Furthermore, in the case of multi-orifice configuration, the array structure of the ejection orifices of the recording head can be arbitrarily designed as desired, and it is therefore extremely easy to make the recording head bar-shaped. It has remarkable features such as: The present invention will be specifically explained in detail below with reference to the drawings. FIG. 1 is a schematic explanatory diagram for explaining the recording principle in the recording apparatus of the present invention. A liquid 3 is supplied to the recording head 1 from an external supply tank (not shown) through means such as a supply pipe (not shown) or a filter (not shown). At this time, pressure P may be applied to the liquid by an appropriate pressurizing means such as a pump to such an extent that it cannot be discharged from the discharge orifice 2 by itself. As shown in this figure, a heating element 4, which is a means for generating thermal energy, is installed in a heat acting part 5, which is a part where the generated thermal energy acts on the liquid 3. The heat acting portion 5 is a portion where thermal energy generated by the heating element 4 is applied to the liquid 3, and the liquid in the heat acting portion 5 undergoes a state change (liquid volume expansion, generation of bubbles, etc.). As is clearer from FIG.
The direction in which the liquid flows out is bent (that is, the liquid path communicating with the discharge port is bent), and the heat generating surface S _G of the heating element 4 is oriented toward the discharge orifice. And because of these features, the intended purpose of the present invention is effectively achieved. To explain this point in further detail, the central _axis The axis Y _O is an axis obtained by rotating the line segment X O by an angle θ to the right, and is parallel to the direction in which the discharge orifice 2 flows from the heat application section 5 (as shown in Fig. 1, the axis Y _O When the discharge passage 7 is provided between the discharge passage 7 and the discharge orifice 2, the central axis of the portion of the discharge passage 7 near the heat acting part 5 may be used as the central axis). A heat acting section 5, a supply channel 6, and a discharge orifice 2 are arranged. A heating element 4 for supplying thermal energy to the liquid in the heat acting section 5
is arranged in the heat acting part 5 so that its heat generating surface faces toward the discharge orifice 2. In particular, the heat generating surface of the heat generating element 4 is made to substantially oppose the cross section AB of the heat acting part 5 on the side of the discharge orifice 2, and is aligned with the central axis of the discharge orifice 2 (which is the same as the axis _YO in the figure). It is desirable that the heating element 4 is disposed in the heat effecting section 5 so as to be substantially perpendicular to the direction of the heat generating section 5. The above-mentioned angle .theta. and the surface direction of the heating element can take various values other than the angles shown in the figure in designing the recording head. However, if θ is too close to 0° or 180°, the heating element, heat acting part, supply channel,
It is not only difficult to form the discharge orifice, etc., but also it becomes difficult to effectively achieve the intended purpose of the present invention, so it is usually preferable to set the angle to 30°≦θ≦150°, and the preferable range is 45°≦θ. ≦135゜, optimally approximately θ
It is desirable that the angle be 90°. Similarly, to describe the direction of the heating element using FIG. 1, there is a vector on the axis _YO , and a vector on a line perpendicular to the heating surface passing through the point where the axis _YO or its extension intersects the heating surface of the heating element 4. and the included angle Ψ formed when the reference point of both vectors is the intersection point is usually 45° or less, preferably 30° or less,
In particular, it is desirable that the angle be selected to be approximately 0°. When θ=90° and Ψ=0°,
It is also most preferred in that it is practically easy to form a heating element, a heat acting part, a supply channel, and a discharge orifice. In addition, as the heating element 4, for example, ZrB ₂ ,
Made of material such as HfB ₂ . Now, when a signal is applied to the heating element from the outside, the heating element instantaneously generates heat and applies thermal energy to the liquid in the heat effecting section 5. As a result, a state change (volume expansion or generation of bubbles) occurs in the liquid, and a predetermined amount of liquid is ejected from the ejection orifice 2 in a predetermined direction. As described above, in the present invention, a bent part is provided in the liquid flow path (liquid path) having a heat acting part therebetween, so that the thermal energy generated in the heat acting part can be effectively applied to the liquid. When the heat generating surface of the provided heat generating element is installed facing the discharge orifice, pressure changes are effectively transmitted in the discharge direction. Therefore, the effect (so-called back pressure effect) of pressure changes based on changes in the state of the liquid in the heat acting section being transmitted inward to the supply flow path is suppressed, and the discharge efficiency is improved. Furthermore, when multi-orifices are used, back pressure is not transmitted to adjacent heat-acting parts and they interfere with each other, and discharge stability is also improved. Furthermore, since thermal energy is efficiently used for discharging liquid, the driving energy of the heating element can be reduced, and favorable results can be obtained in terms of energy saving, improvement in the durability of the heating element, etc. . In addition to the above-mentioned advantages, if the device of the present invention is constructed of blocks such as a heating element substrate, a supply flow path plate, and a discharge flow path plate as described below, particularly favorable results can be obtained in terms of the structure. It will be done. For example, as shown in FIG. 2a, the heating element substrate 8 is provided with seven heating elements 11, seven selection electrodes 12 for supplying electricity to the heating elements 11, and a common electrode 13. In addition, seven narrow grooves 14 are provided in the supply channel plate 9 at positions corresponding to each of the seven heating elements 11.
Similarly, seven narrow grooves 15 are formed in the discharge flow path plate 10 so as to correspond to the narrow grooves 14. When these blocks are integrated, a device as shown in cross-section in FIG. 2b is formed. That is, a supply channel 20 is formed by the heating element substrate 8 and the supply channel plate 9, and a discharge channel 21 is formed by the end surface of the supply channel plate 9 and the discharge channel plate 10, respectively. Further, a heat acting part 22 shown by a broken line is formed between the supply channel 20 and the discharge channel 21, and the heating element 11 is arranged so as to effectively apply thermal energy to the liquid in the heat acting part 22. Placed. The supply flow path plate 9 is provided with a block 16 for forming a means for supplying liquid from the outside into the supply flow path 20, for example, a supply liquid chamber 23. A pipe 17 is attached for introducing into 23. Reference numerals 18 and 19 denote a discharge orifice plate (in the figure, seven discharge orifices are provided corresponding to the narrow grooves 15) and an air bleed pipe, which are provided as necessary. FIG. 3 is a schematic perspective view for explaining the apparatus of the present invention incorporating the recording head described in FIG. 2. In this figure, 24 is an electrode lead substrate (not shown in FIG. 2), and lead wires 25 and 2 for selection electrodes and common electrodes are provided on the substrate 24.
6 is provided. Further, a heat sink 27 is provided on the lower surface of the heat generating substrate 8. The lead wire 25 of the selection electrode and the lead wire 26 of the common electrode are electrically connected to a drive signal generating means P for supplying a drive signal such as a pulse voltage to each heat generating element in order to drive each of the seven heat generating elements 11. connected. A signal S of information to be recorded is input to the drive signal generating means P, and the signal S
is input to the drive signal generating means P, the means P
A drive signal is output from the drive signal, and the heating element selected based on the drive signal is driven to eject liquid from the ejection orifice, thereby executing recording. The end of the pipe 17 may be extended or may be connected to another introduction pipe CP, but the liquid L in the storage tank R in which the liquid L is stored
It is communicated with. Therefore, the amount of liquid discharged from each discharge orifice is supplied from the storage tank R to each heat acting section through the pipe 17. In the above example, the end face of the supply channel plate 9 is set at approximately 90 degrees with respect to the reference axis CD of the supply channel, and θ=
An example in which the angle is 90° and Ψ=0° has been described, but the same procedure can be used to create the ones shown in FIGS. 4a and 4b, in which θ and Ψ are variously changed. However, in FIG. 4a, 28 is a member for adjusting the installation angle Ψ of the heating element 11. Furthermore, in order to reduce the pressure loss (back pressure) into the supply flow path, if a convex part 29 is provided near the heat acting part 22 of the supply plate 9 as shown in FIG. 4C,
More favorable results can be obtained in terms of discharge efficiency. Alternatively, in the example of FIG. 2 described above, the supply channel 20
The case has been described in which the grooves 14 providing the flow path 21 are formed on the supply flow path plate 9 side, and the grooves 15 providing the discharge flow path 21 are formed on the discharge flow path plate 10 side.
The groove 14 may be formed in the heating element substrate 8, or the groove 14 may be formed in the heating element substrate 8.
5 may be formed on the end face on the supply channel plate 9 side. Furthermore, if possible, the supply channel plate 9 and the discharge channel plate 10 may be made of the same member, and the supply channel and the discharge channel may be formed thereon by techniques such as etching, electron beam processing, or laser processing. The device of the present invention has improved ejection efficiency or ejection response. Furthermore, the structure allows for easy installation of the heating element or electrodes. Generally, the liquid flow path of such a device has an extremely fine structure,
It is extremely difficult to install an element such as a heating element in a flow path for the purpose of improving discharge efficiency, discharge response, and the like. Furthermore, there are many restrictions on the removal of electrodes and electrode leads. However, the device of the present invention has many advantages, such as being able to easily create a fine structure with high density multi-orifices, and having a structure that allows easy installation of heating elements, electrodes, electrode leads, etc. . The invention will be explained in further detail in the following examples. EXAMPLE A recording head for the apparatus shown in FIG. 3 was prepared in the following manner. Width 60 μm on a glass plate with a micro cutter.
Forming many grooves with a depth of 60 μm and a pitch of 250 μm,
A supply channel plate 9 as shown in FIG. 2a was prepared.
Similarly, a large number of grooves each having a width of 70 μm, a depth of 80 μm, and a pitch of 250 μm were formed to form the discharge channel plate 10. The heating element substrate 8 basically includes a base layer 29 for heat retention and smoothness, a heating element 11, electrodes 12 and 13, and an insulating protective film 30. 0.6mm
_SiO2 was sputtered to a thickness of 3μ as a base layer on _{an Al2O3} substrate, and _ZrB2 was sputtered to a thickness of 800Å as an electrode.
After laminating Al to a thickness of 5000 Å, selective photoetching was performed to make the heating element 11 with a width of 65 μm and a length of 75 μm to a thickness of 250 μm.
It was formed with pitch. Subsequently, an insulating protective film was formed by sputtering SiO ₂ to a thickness of 1 μm, and then a heat sink 27 was installed on the back side of the substrate to complete the heating element substrate 8. A plan view of the heating element substrate 8 is shown in FIG. In this figure, 11, 11-1 to 11-7 are plural heating elements, 12, 12-1 to 12-7 are selective electrodes,
13 is a common electrode. (Here, an example is shown in which seven heating elements and selection electrodes are provided.) The selection electrode 12 and the common electrode 13 are formed to extend to one end of the heating element substrate 8, as shown in FIG. 3, and supply drive signals. It is electrically connected to the means P. Also, a molybdenum member with a thickness of 100 μm has a diameter of 60 μm.
The holes were machined with an electron beam with a pitch of 250 μm to form the discharge orifice plate 18 (discharge orifice plate 18
is not necessarily necessary if the discharge flow path has a desired shape and droplets are stably discharged. ).
Furthermore, a block 16 and a supply pipe 1 for introducing liquid supplied from an external supply tank into the supply channel.
7 and air bleed pipe 19 were created. The above-mentioned supply channel plate 9, discharge channel plate 10, heating element substrate 8, discharge orifice plate 18, and block 16 were integrated to form a recording head shown in FIG. Recording was carried out using the recording head described above and the following liquid containing water or toluene as a main component.
As shown in an enlarged cross-sectional view of the recording head in FIG. 6, the liquid supplied from the supply channel 20 undergoes a rapid state change at a heat acting portion 22 indicated by a broken line as it is affected by thermal energy. This state change causes a pressure change in the liquid in the discharge passage 21, and the liquid is discharged from the discharge orifice. Good ejection efficiency and ejection response, and clear images were obtained. 【table】

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram for explaining the principle of the apparatus of the invention, and FIGS. 2a and 2b are illustrations of preferred embodiments of the recording head which is the main part of the apparatus of the invention. , Figure 2a is a schematic assembly diagram, Figure 2b
3 is a schematic perspective view of the device of the present invention incorporating the recording head shown in FIGS. 2a and b, and FIGS. 4a and b ,c
5 is a partial sectional view showing another embodiment of the recording head, which is the main part, and FIG. 5 is a plan view of the heating element board.
FIG. 6 is an enlarged explanatory view showing a part of the recording head section of the apparatus of the present invention. 1... Recording head, 2... Discharge orifice, 3
...Liquid, 4,11...Heating element, 5,22...Heat action section, 6,20...Supply channel, 7,21...Discharge channel, 8...Heating element substrate, 9...Supply Channel plate, 10...Discharge channel plate.

Claims (1)

[Claims] 1. A device comprising an ejection port for ejecting a liquid in a predetermined direction to form flying droplets, and a liquid path communicating with the ejection port and having a bending portion, the bending portion preventing the liquid from flowing into the liquid. The heating element has a heat acting part which is a part where thermal energy generated from a heating element acts on the liquid to cause a state change due to heat and form flying droplets of the liquid to be ejected from the ejection port based on the state change. The included angle Ψ formed by a vector on an axis parallel to the discharge direction of the liquid and a vector on a line perpendicular to the heat generating surface passing through a point where the vector or its extension intersects the heat generating surface of the heat generating element is 45° or less, and is electrically connected to the heating element, and includes a signal supply means for supplying a drive signal to the heating element to drive the heating element to discharge liquid in a predetermined direction. A liquid jet recording device characterized by: 2 The heating surface of the heating element is directed toward the discharge port (the included angle Ψ is
0° direction).