JPS636358B2 - - 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, as it has great 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. The device used in this recording method is an ejection orifice that ejects a colored liquid called ink and causes it to fly as droplets.
A recording head is used which has an inlet for liquid to enter. There are various types of recording heads depending on the method of ejecting liquid from the ejection orifice. For example, the liquid may be supplied from an external liquid supply tank into the liquid chamber under pressure or through natural supply (supply using capillary action, etc.) (However, the above pressurization cannot be done by pressure alone. ), the liquid in the liquid chamber, and
There is a type in which a voltage is applied between an electrode installed in front of the discharge orifice, and liquid is electrostatically discharged from the discharge orifice. Although this type of recording head has a simple structure, it has the drawback that the overall system configuration is complex and requires a high degree of skill and precision in 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 IEE
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 problems with processing such as forming the liquid chamber and installing the piezo vibrating element. Due to the difficulty of miniaturization, it is extremely difficult to create high-density multi-orifices, and it is difficult to achieve high-speed recording. In this way, many of the conventional recording heads have essential but unsolved problems in terms of structure, processing, high-speed recording, high-density multi-orifice, and overall system configuration. There are some issues that need to be addressed. The present invention has been made in view of the above points, and its main object is to provide a recording device 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 a high-density multi-orifice type recording device that is easy to manufacture and practical. The liquid jet recording device of the present invention includes a plurality of ejection ports for ejecting liquid in a predetermined direction to form flying droplets, and a liquid path that communicates with each of the plurality of ejection ports and has a bent portion, The bending portion causes a state change in the liquid due to heat, and based on the state change, thermal energy generated from a heating element acts on the liquid to form the flying droplets of the liquid that are ejected from the ejection port. a plurality of heat action parts that are parts, a liquid path leading to the heat action parts is common to the plurality of heat action parts, a vector on an axis parallel to the discharge direction of the liquid, and a vector on an axis parallel to the discharge direction of the liquid; or an included angle Ψ formed by a vector on a line perpendicular to the heat generating surface passing through a point where the extension line intersects with the heat generating surface of the heat generating element is 45 degrees or less, and is electrically connected to the heat generating element and directed in a predetermined direction. The heating element is characterized by comprising a signal supply means for supplying a drive signal to selectively drive each of the heating elements to cause the heating element to eject the liquid. In this way, the supply channel for supplying liquid to a plurality of heat effecting parts is made common, and the direction in which the liquid flows from the flow path to the heat action part, and the direction from the heat action part to the discharge orifice. By setting the heating element in such a way that its heating surface faces the direction of the discharge orifice, the thermal energy can be used effectively to discharge the liquid, and the discharge efficiency, especially, can be improved. Ejection response and long-term continuous recording properties are significantly improved. In addition, the device of the present invention has an extremely simple structure and can be easily microfabricated, so the device itself can be made much smaller than conventional devices. High-density multi-orifice formation, which is indispensable for high-speed recording, can be realized extremely easily, and in addition, in multi-orifice formation, the array structure of the ejection orifices of the recording head can be arbitrarily configured as desired. It has remarkable features such as being able to be designed and therefore very easily made into a bar shape. The present invention will be explained below with reference to the drawings. FIG. 1 is an explanatory diagram for explaining the recording principle in the recording apparatus of the present invention. A liquid 3 is supplied into the recording head 1 through means such as a supply tank (not shown), a supply pipe (not shown), or a filter (not shown). Note that the 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 section 5, which is a portion where the generated thermal energy acts on the liquid 3. In the heat acting section 5, thermal energy generated by the heating element 4 is applied to the liquid 3, and the state of the liquid in the heat acting section 5 changes (liquid volume expansion, generation of bubbles, etc.).
This is the part that causes 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 more detail, the central axis XO of the portion of the supply liquid path 6 near the heat acting section
YO, which is an axis obtained by rotating the line segment XO to the right by an angle θ around point O, which is parallel to the direction in which the flow flows from the heat action part 5 toward the discharge orifice 2. (As shown in FIG.
is provided, the heat acting part 5, the supply flow path 6, and the discharge liquid are arranged so that the central axis of the part of the discharge liquid path 7 near the heat acting part 5 has an angle θ between them. Orifice 2 is arranged. In order to supply thermal energy to the liquid in the heat effecting part 5, the heating element 4 is arranged in the heat effecting 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 has a cross section AB on the discharge orifice 2 side of the heat acting part 5.
and the discharge orifice 2
The heating element 4 is attached to the heat acting part 5 so that it is approximately perpendicular to the central axis (in the figure, it is the same as the axis YO).
It is desirable that the 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 O° or 180°, not only will it be difficult to form the heating element heat acting part, supply channel, discharge orifice, etc., but it will also be difficult to effectively achieve the intended purpose of the present invention. Therefore, normally 30°≦θ
Preferably ≦150°, preferably 45°≦θ≦135°,
Optimally, it is desirable that θ be approximately 90°. Similarly, to describe the direction of the heating element using FIG. 1, there are two vectors: 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. The angle 4 formed when the reference point of both vectors is set to the intersection is usually 45° or less, preferably 30° or less,
In particular, it is desirable that the angle be selected to be approximately O°. When θ=90° and =0°, it is most preferable from the point of view that it is practically easy to form the heating element, the heat acting part, the supply channel, and the discharge orifice.
The heating element 4 is made of a material such as ZrB ₂ or HfB ₂ , for example. 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. In this way, 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 in the direction in 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, when the device of the present invention is structured as follows, consisting of blocks such as a heating element substrate, a supply flow path plate, and a discharge flow path plate, particularly favorable results can be obtained in terms of the structure. . 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. Further, grooves 14 are formed in the supply passage plate 9, and narrow grooves 15 are formed in the discharge passage plate 10 so as to correspond in position and number to the heating elements 11. When these blocks are integrated, a device as shown in cross-section in FIG. 2b is formed. That is, a common supply channel 2 for each heating element is provided by the heat generating element substrate 8 and the supply channel plate 9.
0, a discharge passage 21 is formed by the end face of the supply passage plate 9 and the discharge passage 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. be done. The supply channel plate 9 is provided with means for supplying liquid from the outside to the supply channel 20, for example, a block 16 for forming a supply liquid chamber 23, and the block 16 is provided with a means for supplying liquid from the outside to the supply channel 20. A pipe 17 is attached for introducing into the chamber 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 illustrating an apparatus of the present invention incorporating the recording head described in FIG. 2. In this figure, 24 is an electrode lead board (second
), and lead wires 25 and 26 for the selection electrode and the common electrode are provided on the substrate 24.
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. It is connected.
A signal S of information to be recorded is inputted to the drive signal generation means P, and a drive signal is outputted from the means P so that the signal S is inputted to the drive signal generation means P. The selected heating element is driven based on the drive signal, liquid is ejected from the ejection orifice, and recording is executed. The pipe 17 may have an extended end or may be connected to another inlet pipe.
Although it may be connected to the CP, it is communicated with the liquid L in the storage tank R in which the liquid L is stored. 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 supply channel reference axis 1, and θ=90°ψ=
Although the example in which the angle is 0° has been described, the ones shown in FIG. 4 a, b, c, and d, in which θ and ψ are variously changed, can also be created using the same procedure as in the above example. However, in FIG. 4a, 28 is a member for adjusting the installation angle φ of the heating element 11. Figures 4a and 4b are examples in which the heating element is provided above the reference plane of the supply channel; c and d are examples in which at least a part of the heating element is below the reference plane. Furthermore, in order to reduce the pressure loss (back pressure) in 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. 4e,
More favorable results can be obtained in terms of discharge efficiency. Alternatively, in the example of FIG. 2 described above, the supply channel 20
Although the case has been described in which the grooves 14 giving the same are formed on the supply channel plate 9 side, the grooves 14 may also be formed on the heat generating substrate 8. 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 supply channel of such a device has an extremely fine structure,
It is extremely difficult to install an element such as a heating element within or close to the flow path for the purpose of improving ejection efficiency, ejection 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 form a fine structure with a high density multi-orifice structure, 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 an apparatus as shown in FIG. 3 was prepared in the following manner. A concave portion (groove) 14 having a depth of 70 μm was formed in the glass plate by etching to obtain the supply channel plate 9 shown in FIG. 2a. Further, a large number of grooves 15 each having a width of 100 μm, a depth of 150 μm, and a pitch of 250 μm were formed on the glass plate using a micro cutter to form a discharge channel plate 10. On the other hand, the heating element substrate 8 basically includes a base layer 29 for the purpose of heat retention and smoothness, a heating element 11, electrodes 12 and 13, and an insulating protective film 30. SiO ₂ was sputtered to a thickness of 3 μm as a base layer on a 0.6 mm Al ₂ O ₃ substrate, ZrB ₂ was laminated to a thickness of 800 Å, and Al was laminated to a thickness of 5000 Å as an electrode, and then selective photoetching was performed to form a heat generating layer of 85 μm in width and 130 μm in length. body 11
It was formed with a pitch of 250 μm. Then add SiO ₂ to the thickness
After forming an insulating protective film by sputtering with a thickness of 1 μm, a heat sink 27 was installed on the back side of the substrate. A plan view of the heating element substrate 8 thus formed is shown in FIG. In this figure, 11 (11-1 to 11
-7) is a plurality of heating elements, 12 (12-1 to 12-
7) is a selection electrode, and 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:
As shown in FIG. 3, it is formed to extend to one end of the heating element substrate 8, and is connected to a connector (not shown). In addition, a molybdenum member with a thickness of 100 μm has a diameter
Discharge orifice plate 1 with 60μm holes and 250μm holes.
8 (the discharge orifice plate 18 is not necessarily necessary if the discharge flow path has a desired shape and diameter and droplets of an appropriate diameter are discharged). Furthermore, a block 16, a pipe 17, and an air bleed pipe for introducing liquid supplied from an external tank into the supply channel were created. The above-mentioned supply channel plate 9, discharge channel plate 10, heating element substrate 8, etc. were integrated. This recording head was used to record water and the following liquid containing toluene as its main component. The droplet ejection operation will be briefly explained with reference to FIG.
When pulsed signals are applied to the electrodes 13 and 12, the heating element 11 generates heat. and supply channel 20
The liquid supplied from the pump undergoes a sudden change in state (volume expansion or generation of bubbles) under the action of thermal energy at a heat acting portion 22 indicated by a broken line. This causes a pressure change in the liquid within the discharge flow path 21 and is discharged from the discharge orifice. When the heating element stops generating heat, the liquid returns to its original state (reduction in volume or disappearance of bubbles), and therefore droplets are ejected in accordance with the external information signal. Ejection efficiency, ejection response, and long-term continuous recording performance were good, and clear images were obtained. 【table】

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram for explaining the principle of the device of the present invention, and FIGS. 2a and 2b are diagrams showing preferred embodiments of the recording head which is the main part of the device of the present invention. Figure 2a is a schematic assembly diagram, Figure 2b is a sectional view taken along the breaking line X'Y', and Figure 3 is a
A schematic perspective view of the apparatus of the present invention incorporating the recording head shown in FIGS. 2a, b, and 4a, b, c, d,
e is a partial sectional view showing another embodiment of the recording head which is the main part, FIG. 5 is a plan view of the heating element substrate, and FIG. 6 is an enlarged view showing a part of the recording head part of the apparatus of the present invention. It is an explanatory diagram. 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)

[Scope of Claims] 1. A liquid crystal display device comprising: a plurality of ejection ports for ejecting liquid in a predetermined direction to form flying droplets; and a liquid path having a bent portion communicating with each of the plurality of ejection ports; The bending part is a part where thermal energy generated from a heating element acts on the liquid to cause a state change in the liquid due to heat and form the flying droplets of the liquid to be ejected from the ejection port based on the state change. , a liquid path leading to the heat acting part is common to the plurality of heat acting parts, and a vector on an axis parallel to the discharge direction of the liquid, and a vector or The included angle Ψ formed by a vector on a line perpendicular to the heating surface passing through the point where the extension line intersects with the heating surface of the heating element is 45 degrees or less, and it is electrically connected to the heating element and A liquid jet recording apparatus characterized by comprising: signal supply means for supplying a drive signal for selectively driving each of the heat generating elements to the heat generating elements to cause the liquid to be ejected. 2 The heating surface of the heating element is directed toward the discharge port (the included angle Ψ is
0° direction).