JP2780844B2 - Substrate for inkjet recording head, inkjet recording head having the substrate, and inkjet recording apparatus provided with the recording head - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a substrate for an ink jet recording head for performing recording by ejecting a liquid using thermal energy, an ink jet recording head having the substrate, and the ink jet recording. The present invention relates to an inkjet recording apparatus having a head.

[Related Art] An ink jet recording method in which a liquid is ejected (discharged) by using thermal energy to perform recording is capable of high resolution, high speed printing, high recording quality, low noise, and color image recording. This makes it easy to print on plain paper and the like, and it is easy to reduce the size of the recording head and the entire apparatus.

Above all, bubble jet recording utilizes a film boiling phenomenon caused by rapidly heating a heating element in contact with ink. Therefore, the properties of the surface of the heating element for a bubble jet printer have a great effect on the performance of the printer, and various contrivances have conventionally been made.
In JP-A-56-10471, the heating element surface is made rough (JIS roughness 0.05S to 2S) to form bubble nuclei on the irregularities on the surface, and by causing boiling at a lower temperature,
An arrangement capable of performing recording with low energy consumption is disclosed. JP-A-56-19771 discloses a method of setting an energy level for performing good recording using a heating element having a rough surface (JIS roughness 0.05S to 2S). Japanese Patent Application Laid-Open No. 62-201254 discloses a configuration in which gradation can be controlled by roughening the surface of a heating element and increasing the heating value of the heating element in a central portion from an end portion.

Further, the surface state of the heating resistor depends on the surface state of the substrate on which the heating element is formed, and thus the substrate has been devised. In JP-A-56-10470, the surface of the heating element is made uneven by making the surface of the substrate rough (JIS roughness 0.1S to 5S).
A configuration realizing the same effect as that of Japanese Patent No. 471 is disclosed.
On the other hand, from the viewpoint of the durability of the heating element, the covering property of the protective layer on the surface of the heating element is important. Therefore, a smooth substrate is preferable. JP-A-60-203452 and JP-A-60-206655
In ( ₁ ), the surface of the substrate on which the heating element is provided is made smooth (JIS center line average roughness _Ra 0.1 μm) to improve the coverage of the layer that protects the surface of the heating element formed thereon. There is disclosed a configuration for causing this to occur.

Regarding the properties of the general flow channel wall surface, which is not limited to the heating element surface, various ideas have been devised from a hydrodynamic viewpoint. Japanese Patent Application Laid-Open No. 55-128470 discloses a configuration in which a smoothing process is performed on the inner wall of a flow path to improve the affinity of the ink in the flow path for the wall and realize a smooth ink flow. . Japanese Patent Application Laid-Open No. Sho 58-11173 discloses a configuration in which the flow path is formed with a cured film of a photosensitive resin and the inner wall of the flow path has a fine rough surface, thereby facilitating production and increasing the speed of ink supply. It has been disclosed.

[Problems to be Solved by the Invention] However, in the above-described conventional example, there is a problem that a device for increasing the pressure at which the liquid boils is lacking. That is, JP-A-56-10471, JP-A-56
-19771, JP-A-62-201254, and JP-A-56-104
In No. 70, since the liquid boils at a low temperature, the vapor pressure at the time of foaming is small, and a sufficient droplet discharge speed may not be obtained. In Japanese Patent Application Laid-Open Nos. 60-203452 and 60-206655, the surface coating property is considered, but what should be done to increase the pressure at which the liquid boils? Does not give any suggestions. In JP-A-55-128470 and JP-A-58-11173, although the surface condition as a flow path wall is taken into consideration, the properties of the surface of the heating element as a heat transfer surface (heat action surface) are not considered. No consideration is given, so no suggestion is given as to how to increase the pressure at which the liquid boils. For this reason, the pressure at the time of bubbling becomes small, and a droplet discharge speed sufficient for performing high-quality recording may not be obtained in some cases.

The bubble internal pressure during foaming is substantially equal to the vapor pressure of the ink at the temperature at which the bubble was generated. Therefore, in order to increase the pressure at the time of foaming, it is necessary to suppress the generation of bubbles at a low temperature and to generate the bubbles only when the surface of the heating element becomes high in temperature.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a heating element for constructing a bubble jet printer head having a high pressure at the time of foaming and a high droplet discharge speed.

Means for Solving the Problems In order to achieve such an object, a substrate for an ink jet recording head according to the present invention includes a heating resistor layer and at least a pair of electrodes electrically connected to the heating resistor layer. And a heating element having a surface covering the heating resistor layer and the at least one pair of electrodes, the surface of which contacts the ink.
A protective layer made of -Si- (at least one of B and C), wherein the surface of the protective layer has a 60-degree specular gloss of 70% or more.

Here, the substrate for an inkjet recording head may further have another protective layer below the protective layer.

An ink jet recording head according to the present invention includes a heating element having a heating resistor layer and at least a pair of electrodes electrically connected to the heating resistor layer, and covering the heating resistor layer and the at least one pair of electrodes. A base having a protective layer whose surface is made of Ta-Si- (at least one of B and C) in contact with the ink and whose surface has a 60-degree specular gloss of 70% or more; And a liquid passage communicating with the discharge port.

Here, the heating element generates heat energy by applying at least one drive signal corresponding to recording information and giving a rapid temperature rise exceeding nucleate boiling, and a film is formed on the ink on the protective layer surface. Boiling can occur.

An inkjet recording apparatus according to the present invention includes a heating element having a heating resistor layer and at least a pair of electrodes electrically connected to the heating resistor layer, and covering the heating resistor layer and the at least one pair of electrodes. A base having a protective layer whose surface is made of Ta-Si- (at least one of B and C) in contact with the ink and whose surface has a 60-degree specular gloss of 70% or more; An ink jet recording head having a discharge port provided, a liquid path communicating with the discharge port, a drive circuit for generating an electric signal for driving the heating element, and a drive circuit provided at a position facing the discharge port. And a platen.

Here, the driving circuit generates heat energy in the heating element by applying at least one driving signal corresponding to recorded information and giving a rapid temperature rise exceeding nucleate boiling to the heating element, The ink may cause film boiling on the protective layer surface of the recording head.

[Operation] According to the present invention, since the surface of the heating element is smooth, generation of bubble nuclei at a low temperature is suppressed, and bubbles are generated when the temperature of the heating element surface becomes sufficiently high. Therefore, the pressure at the time of bubbling is high, and droplets can be discharged at a size speed, so that high-quality image recording can be performed. Further, the pressure at the time of bubbling is increased, and the action force for discharging the liquid is increased. Therefore, an effect that so-called clogging is hardly generated can be obtained.

Examples Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a schematic configuration example of a liquid jet recording apparatus (ink jet recording apparatus) equipped with a recording head to which the present invention is applied, and FIG. 2 shows a configuration example of the recording head.

First, in FIG. 1, reference numeral 1 denotes a head cartridge in which a recording head and an ink tank as an ink supply source are integrated. The head cartridge 1 is fixed on the carriage 3 by a holding member 2.
These can reciprocate along the shaft 4 in the longitudinal direction. The ink ejected from the recording head reaches the recording medium 6 whose recording surface is regulated by the platen 5 at a minute interval from the recording head, and forms an image on the recording medium 6.

The recording head is connected to a driving circuit via a cable 7 and a terminal (not shown) connected thereto, and an ejection signal corresponding to image data is supplied from an appropriate data supply source. One or more (two in the figure) head cartridges can be provided according to the ink color or the like to be used.

In FIG. 1, 8 is a carriage motor for scanning the carriage 3 along the shaft 4, and 9 is a wire for transmitting the driving force of the motor 8 to the carriage 3.
Reference numeral 10 denotes a feed motor that is coupled to the platen roller 5 to convey the recording medium 6. Reference numeral 11 denotes a reference temperature sensor provided at an appropriate portion of the apparatus main body.
The reference temperature sensor 11 is disposed at an appropriate position that is not affected by the temperature rise in the device, and monitors the ambient temperature.

FIG. 2 shows a configuration example of a recording head to which the present invention can be applied. Here, reference numeral 12 denotes a heater board (substrate), which is formed by forming an electrothermal transducer (discharge heating element) 13 according to the present invention and a wiring 14 made of Al or the like for supplying power thereto by a film forming technique. . Then, a top plate 16 provided with a partition wall for forming a liquid path (nozzle) 15 of the recording liquid is adhered to the heater board 12, thereby forming a liquid jet recording head. Note that this partition need not be provided on the top plate 16,
A partition may be provided on the heater board 12, and a top plate without the partition may be provided on the partition.

A recording liquid (ink) is supplied to a supply port 17 provided in the top plate 16.
The liquid is supplied to the common liquid chamber 18 and is guided into each nozzle 15 from here. When the heating element 13 generates heat by energization,
Foaming occurs in the ink filled in the nozzle 15 and the discharge port 19
More ink droplets are ejected.

FIG. 3 shows a sectional view of one embodiment of the heating resistor according to the present invention. In this embodiment, a 2.5 μm thick surface oxide SiO ₂ layer 22 is formed on the surface of a 525 μm thick Si substrate 21, and a 0.1 μm thick HfB ₂ resistance layer 23 is formed thereon by sputtering.
A 0.5 μm thick Al electrode 24 by EB evaporation, a 1.5 μm thick SiO ₂ insulating layer (also serving as a protective layer) 25 by sputtering, and a 0.5 μm thick
The Ta-Si-B protective layer 26 of μm is sequentially formed. The area of the heating part of the heating resistor is 30μm × 50μ
m.

When the composition ratio of the protective layer 26 was changed, the crystal grain size of Ta-Si-B changed, and the 60-degree specular gloss of the protective layer 26 changed.
The 60 degree specular gloss was measured according to JISZ8741. The relationship between the composition ratio and the 60-degree specular gloss was determined by trial and error because there was an uncertain factor such as the state of the film forming apparatus and a quantitative relational expression had not yet been obtained.

Using the heat-generating resistor of the present embodiment and discharging droplets using water-based ink as the ink, when the 60-degree specular gloss was 70% or more, a sufficient droplet discharge speed was obtained. When it was less than 70%, a sufficient droplet discharge speed could not be obtained. This indicates that there is a correlation between the surface glossiness and the droplet discharge characteristics.

Similar results were obtained when inks other than water-based inks were used.

FIG. 4 is a sectional view of another embodiment of the heating resistor according to the present invention. In this embodiment, a 2.5 μm thick surface oxidized SiO ₂ layer 22 is formed on the surface of a 525 μm thick Si substrate 21, and a 0.1 μm thick HfB ₂ resistance layer 2 is formed thereon by sputtering.
3, an Al electrode 24 having a thickness of 0.5 μm is formed by EB evaporation, an SiO ₂ insulating layer 25 having a thickness of 1.5 μm is sequentially formed by a sputtering method, and a 0.5 μm thick electrode is further formed by a sputtering method.
In this example, a m-type Ta-Si-C protective layer 27 is formed. The area of the heat generating portion of the heat generating resistor was 30 μm × 50 μm.

When the composition ratio of the protective layer 27 was changed, the crystal grain size of Ta-Si-C was changed, so that the 60-degree specular gloss of the protective layer 27 was changed. Even if the material of the protective layer is different,
When the 60-degree specular gloss was 70% or more, a sufficient droplet discharge speed was obtained as in the previous example, but when it was less than 70%, a sufficient droplet discharge speed was not obtained.

(Others) The present invention brings about an excellent effect particularly in a recording head and a recording apparatus of a bubble jet system among ink jet recording systems. This is because according to such a method, it is possible to achieve higher density and higher definition of recording.

As for the representative configuration and principle, it is preferable to use the basic principle disclosed in, for example, US Pat. Nos. 4,723,129 and 4,740,796. This method can be applied to both the so-called on-demand type and the continuous type. In particular, in the case of the on-demand type, it is arranged corresponding to a sheet or a liquid path holding a liquid (ink). Applying at least one drive signal corresponding to recording information and providing a rapid temperature rise exceeding each boiling point to the electrothermal transducer, thereby causing the electrothermal transducer to generate thermal energy, and This is effective because a film in the liquid (ink) corresponding to the driving signal can be formed one by one by causing film boiling on the heat acting surface. The liquid (ink) is ejected through the ejection opening by the growth and contraction of the bubble to form at least one droplet. When the drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of a liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable. U.S. Pat. No. 44
Those described in JP-A-63359 and JP-A-4345262 are suitable. Further, when the conditions described in US Pat. No. 4,313,124 relating to the temperature rise rate of the heat acting surface are adopted, more excellent recording can be performed.

As a configuration of the recording head, in addition to a combination configuration (a linear liquid flow path or a right-angled liquid flow path) of a discharge port, a liquid path, and an electrothermal converter as disclosed in the above-mentioned specifications, A configuration using U.S. Pat. No. 4,558,333 and U.S. Pat. No. 4,459,600, which disclose a configuration in which is disposed in a bending region, is also included in the present invention. In addition, Japanese Unexamined Patent Publication No. 59-123670 discloses a configuration in which a common slit is used as a discharge portion of an electrothermal converter for a plurality of electrothermal converters, and an opening for absorbing a pressure wave of thermal energy is provided. The effect of the present invention is effective even if the configuration is based on JP-A-59-138461, which discloses a configuration corresponding to a discharge unit. That is, according to the present invention, recording can be reliably and efficiently performed regardless of the form of the recording head.

Further, the present invention can be effectively applied to a full-line type recording head having a length corresponding to the maximum width of a recording medium on which a recording apparatus can record. Such a recording head may have a configuration that satisfies the length by a combination of a plurality of recording heads, or a configuration as one integrally formed recording head.

In addition, even with the serial type printer as in the above example, the recording head fixed to the main unit or attached to the main unit enables electrical connection with the main unit and supply of ink from the main unit. The present invention is also effective when a replaceable chip type print head or a cartridge type print head having an ink tank provided integrally with the print head itself is used.

Further, it is preferable to add recovery means for the print head, preliminary auxiliary means, and the like provided as a configuration of the printing apparatus in the present invention since the effects of the present invention can be further stabilized. To be more specific, capping means for the recording head, cleaning means, pressurizing or suction means, preheating means using an electric heat exchange couple or another heating element or a combination thereof, Performing a preliminary ejection mode in which ejection is performed separately from printing is also effective for performing stable printing.

Regarding the type or number of print heads to be mounted, for example, in addition to one provided for single color ink, a plurality of print heads are provided corresponding to a plurality of inks having different print colors and densities. May be used. That is, for example, as the recording mode of the recording apparatus, not only the mainstream color such as black is used in the recording mode, but the recording head may be configured integrally or by a combination of a plurality of recording heads. The present invention is also extremely effective for an apparatus provided with at least one of full colors by color mixture.

In addition, in the embodiments of the present invention described above, the ink is described as a liquid. However, an ink that solidifies at or below room temperature and softens or liquefies at room temperature, or the ink itself in an inkjet method. In general, the temperature is controlled within a range of 30 ° C. or more and 70 ° C. or less to control the temperature so that the viscosity of the ink is in a stable ejection range. I just need. In addition, the temperature rise due to thermal energy can be positively prevented by using it as energy for changing the state of the ink from a solid state to a liquid state, or ink that solidifies in a standing state to prevent evaporation of the ink can be used. In any case, the ink is liquefied by the application of the thermal energy according to the recording signal, and the ink is liquefied, and the liquid ink is discharged. The present invention is also applicable to a case where an ink that liquefies for the first time by energy is used. The ink in such a case is disclosed in
No. -56847 or JP-A-60-71260, while being held as a liquid or solid substance in a porous sheet recess or through hole, facing the electrothermal converter. It is good also as a form. In the present invention,
The most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

In addition, as the form of the ink jet recording apparatus of the present invention, in addition to those used as image output terminals of information processing equipment such as a computer, a form of a copying apparatus combined with a reader and the like, and a form of a facsimile apparatus having a transmission / reception function What you take may be used.

[Effects of the Invention] As described above, according to the present invention, the pressure at the time of bubbling is increased by increasing the JIS 60-degree specular glossiness of the heating resistor surface to 70% or more, and the droplet discharge speed is reduced. As a result, recording with high quality image quality can be performed. Furthermore, since the pressure at the time of foaming increases and the acting force for discharging the liquid increases, so-called clogging is less likely to occur.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of an ink jet recording apparatus equipped with a recording head to which the present invention is applied, FIG. 2 is a diagram showing a configuration example of a recording head to which the heating element of the present invention can be applied, and FIG. FIG. 4 is a sectional view of a heating resistor according to an embodiment of the present invention. FIG. 4 is a sectional view of a heating resistor according to another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1 ... Head cartridge, 2 ... Holding part, 3 ... Carriage, 4 ... Shaft, 5 ... Platen, 6 ... Recording medium, 7 ... Cable, 8 ... Carriage motor, 9 ... Wire, 10 ... feed motor, 11 ... reference temperature sensor, 12 ... heater board, 13 ... heating element, 14 ... wiring, 15 ... nozzle, 16 ... top plate, 17 ... supply port, 18 ... common liquid chamber, 19 ...... discharge port, 21 ...... Si substrate, 22 ...... surface oxide layer, 23 ...... HfB ₂ resistive layer, 24 ...... Al electrode, 25 ...... SiO ₂ insulating layer, 26 ...... Ta-Si -B protective layer, 27 ... Ta-Si-C protective layer.

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B41J 2/05

Claims (8)

(57) [Claims] A heating element having a heating resistor layer and at least a pair of electrodes electrically connected to the heating resistor layer; and a surface covering the heating resistor layer and the at least one pair of electrodes, the surface of which is ink. And a protective layer made of Ta-Si- (at least one of B and C) in contact with the protective layer, wherein the surface of the protective layer has a 60-degree specular gloss of 70% or more. Substrate. 2. The substrate for an ink jet recording head according to claim 1, further comprising another protective layer below said protective layer. 3. A heating element having a heating resistor layer and at least one pair of electrodes electrically connected to the heating resistor layer, and a surface covering the heating resistor layer and the at least one pair of electrodes, the surface of which is ink. Consisting of Ta-Si- (at least one of B and C) in contact with
An ink jet recording head, comprising: a base having a protective layer of 70% or more; a discharge port provided corresponding to the heating element; and a liquid passage communicating with the discharge port. 4. The ink jet recording head according to claim 3, further comprising another protective layer below said protective layer. 5. The heating element generates heat energy by applying at least one drive signal corresponding to recording information and giving a rapid temperature rise exceeding nucleate boiling, and the ink is generated on the surface of the protective layer. 5. The ink jet recording head according to claim 3, wherein film boiling occurs in the ink jet recording head. 6. A heating element having a heating resistor layer and at least a pair of electrodes electrically connected to the heating resistor layer, and a surface covering the heating resistor layer and the at least one pair of electrodes, the surface of which is ink. Consisting of Ta-Si- (at least one of B and C) in contact with
An ink jet recording head having a base having a protective layer of 70% or more, an ejection port provided corresponding to the heating element, and a liquid path communicating with the ejection port, and for driving the heating element And a platen provided at a position facing the discharge port. 7. The ink jet recording apparatus according to claim 6, further comprising another protective layer below said protective layer. 8. The heating circuit generates heat energy in the heating element by applying at least one driving signal corresponding to recorded information and giving a rapid temperature rise exceeding nucleate boiling to the heating element. The ink jet recording apparatus according to claim 6, wherein the ink causes film boiling on the protective layer surface of the recording head.