JPH02111552A - Substrate for liquid jet recording head and liquid jet recording head equipped with same substrate - Google Patents

Abstract

PURPOSE:To improve quality of an image to be obtained by improving reproducibility of boiling by a method wherein substance which has large thermal conductivity in a part including a position at which a bubble disappears is arranged under a heating resistor layer. CONSTITUTION:For a thermal resistor layer 3 formed for instance by a sputtering method, a layer 9 of which thermal conductivity is higher than that of a heat accumulation layer is arranged under a part including a position at which a bubble disappears. A differences DELTAT (=TH-TO) between a peak value TH of surface temperature of a thermal resistor 3 and a peak value TO of surface temperature corresponding to an area in which a layer 9 of high thermal conductivity is established according to the bubble disappearing position is preferably 20 deg.C or over up to and including 100 deg.C. Though heat generated in the thermal resistor layer 3 is transmitted down and up, the heat to be transmitted to the lower part is more by comparing that with the other part in a part in which the thermal resistor layer 3 is in contact with a SiC layer 9 of higher thermal conductivity than the heat accumulation layer 2. Consequently over the layer 9, the heat which is transmitted to liquid 8 via the upper layers, i.e., protective layers 5, 6 and 7 is decreased.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a liquid jet recording head and a substrate used for the recording head, and in particular to a liquid jet recording head that boils the liquid by applying thermal energy to the recording liquid. The present invention relates to a liquid jet recording head that performs recording by jetting (discharging) droplets, and a substrate that includes an electrothermal transducer that generates the thermal energy in response to energization.

[Prior Art] Performances required of this type of liquid jet recording head or electrothermal converter include high responsiveness during high-speed driving, and the ability to heat the liquid sufficiently to boil it. , may be highly durable. For this purpose, we have traditionally used materials,
Various improvements have been made in terms of construction.

For example, in Japanese Patent Publication No. 59-34506, the electrothermal converter has a three-layer structure consisting of a lower layer, a heating resistor layer, and an upper layer in order to improve response, capacitance, and heating performance. Discloses the conditions that must be met.

Furthermore, Japanese Patent Laid-Open No. 60-236758 discloses a structure in which the protective layer is made thinner on the heat generating portion in order to increase durability.

Generation of bubbles (main bubbles or primary bubbles) related to liquid discharge.
During repeated extinction, if there is a part with a temperature higher than the heating limit temperature other than the position where the main bubble disappears on the heat acting part, sushi-shaped secondary bubbles ( A phenomenon occurs in which secondary air bubbles remain. Since the cavitation of the secondary bubbles is much larger than that of the main bubbles, it may destroy the upper protective layer in that area, leading to destruction of the electrothermal converter and deteriorating its durability.

The invention disclosed in JP-A-62-103148 focuses on the fact that when the thickness of the upper layer and the lower layer of the electrothermal converter are uniform, the central part of the heat acting part becomes high temperature. By forming the central area of the heat acting part of at least one of the lower layer and the upper layer of the converter to be thinner than the other areas, the heat dissipation of that area is improved, and during driving (electrothermal converter When electricity is applied), the temperature of the heat acting part rises uniformly over the center and surrounding areas, and when the main bubble disappears after driving, the temperature of the center of the heat acting part falls below the heating limit temperature. .

In addition, in JP-A No. 59-95155, in order to prevent the above-mentioned cavitation damage, a conductive area is provided in the center of the electrothermal converter (resistor), and the area is closed so that the area does not become involved in foaming. Annular bubbles are formed in the surrounding area, and when defoaming, a plurality of small bubbles are randomly distributed on the heat acting part.

[Problems to be Solved by the Invention] However, in a recording head having an electrothermal converter in the ejection energy generating means, in addition to the above conditions, high reproducibility of boiling is required.

According to the inventor of the present application, when repeatedly boiling a liquid, the drive signal (heating pulse) previously given to the electrothermal converter
When the bubbles generated by this process disappear, microscopic residual substrates randomly adhere to the surface of the electrothermal converter at the point where the bubbles disappear, and when the initial bubbles are generated in the next pulse heating, they become foaming nuclei. It has been confirmed that boiling reproducibility is not guaranteed due to the This point has not been particularly considered in the past.

If the boiling phenomenon is not stabilized in this way, the shape and size of the generated bubbles will not be constant, resulting in variations in droplet diameter and ejection speed, resulting in problems such as a decline in image quality.

An object of the present invention is to provide a recording head with high boiling reproducibility and a substrate thereof.

Another object of the present invention is to provide a liquid jet recording head with high image quality without variations in droplet diameter or ejection speed.

[Means for Solving the Problems] To this end, in the substrate for a liquid jet recording head according to the present invention, the support, the heat storage layer disposed on the support, the heating resistor layer, and the heating resistor layer are provided with electricity. an electrothermal transducer having a pair of electrodes that are electrically connected to each other, and a heat generation part is formed on the heat storage layer between the pair of electrodes; a heat conductive layer made of a substance having higher thermal conductivity than the heat storage layer, which is disposed between the electrothermal converter and the heat storage layer in a position corresponding to a position where bubbles generated in the recording liquid disappear; ΔT-T□-T0 is 20℃ or more10
It is characterized by a temperature of 0°C or lower.

Further, a liquid jet recording head according to another embodiment of the present invention includes a support, a heat storage layer disposed on the support, a heating resistor layer, and a pair of electrodes electrically connected to the heating resistor layer. bubbles generated in the recording liquid on the recording liquid contact surface corresponding to the heat generating part and the electrothermal converter having a heat generating part formed on the heat storage layer between the pair of electrodes disappear. A thermally conductive layer is arranged between the electrothermal converter and the heat storage layer in correspondence with the position, and is made of a material having higher thermal conductivity than the heat storage layer, and ΔT=TH−To is 20°C or more. 100℃
The present invention is characterized by comprising the following base body and a member provided on the base body to form a liquid path for recording liquid.

In these, To is the peak temperature of the electrothermal converter in the driving state when there is no recording liquid at the position where the bubble disappears, and T)I is the peak value of the temperature when the recording liquid is at a position other than that position. It is the peak value of the temperature in the operating state of the electrothermal converter when it is not present.

[Function] According to the present invention, a substance having higher thermal conductivity than the lower layer is disposed between the portion of the layer of the electrothermal converter including the position where bubbles disappear and the support (lower layer). By doing so, the heat flux transmitted from the electrothermal converter to the upper liquid becomes smaller in that part.

Therefore, this part has a lower temperature than other parts, and even if there is microscopic residual gas attached to that part after the bubbles disappear,
This will not become a foaming nucleus during subsequent driving.

In addition, by appropriately selecting and configuring the temperature difference, high ejection performance can be maintained, and together with this effect, the reproducibility of boiling can be improved, and as a result, good recording quality can be obtained.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

FIGS. 1(^) and (B) show an example of a liquid jet recording head to which the present invention can be applied, in which a plurality of ejection portions including a plurality of liquid paths, electrothermal converters, and ejection ports (orifices) are integrated. FIG. 2 is a perspective view and a cross-sectional view taken along line X-X′ of the liquid jet recording head in an arranged form.

In these figures, a heating resistor 107 is placed on a substrate 103.
(107-1 to 107-6), and a common electrode 1068 and a selection electrode 105 are arranged as electrodes for energization, and the heating resistor 107 is limited by the partition walls 101a to 101g formed on the T-groove cover plate 102. Groove 101 (
101-1 to 101-6) to match the adhesive layer 10.
4 (104-1 to 104-7). A liquid (ink) is introduced into this, and when electricity is applied, the heating resistor 1
When 07 is heated, bubbles are generated in the liquid on the heating resistor 107 due to a sudden change in state, and droplets corresponding to the increase in volume are discharged from the orifice formed by the groove cover plate 102 and the substrate 103.

The heating resistor 107 according to this example has a layer made of a highly thermally conductive material below the bubble extinguishing position, as will be described later.

Here, the bubble disappearance position (bubble extinction position) will be considered.

The position at which the bubble disappears is determined by the shape of the liquid path in which the heating resistor is installed, the installation position, temperature, and other environmental conditions, and is determined by the inertial component 2 of the hydrodynamic impedance in the area around the bubble.
The inventor of the present application has confirmed that foam disappears near the position where the heating resistors are proportionally distributed in the inverse ratio of Z.

Here, regarding the basin of interest, the position taken in the flow direction is X, and the cross-sectional area at the position X of the basin is 573. Assuming that the length of the basin is °C and the density of the fluid (recording liquid) is ρ, the inertial component Z of the impedance of the basin is determined by:

For example, as shown in FIG. 1, if the heating resistor 107 has a configuration in which the supply direction and the discharge direction of the liquid are the same, the cross-sectional areas "+x" and "-" as shown in FIG. 5
- If constant, 1+-ρfl +/s, z2-9 fl 2/S
(2) C1:C2zZ2 near, -, 122:
x l (3). That is, bubbles disappear near the position determined by this relational expression.

Therefore, the heat flux transmitted to the upper liquid at a portion including that position may be made small.

The above is a general relationship, but if the height of the nozzle ceiling at position X is h(x), then C,
: C2=w2: It was sufficient that the bubbles disappeared at the position where w.

Next, we will consider how much of a temperature difference the region including the defoaming position has from other regions to maintain good discharge performance.

FIG. 3 shows the peak value TM of the surface temperature of the heating resistor and the peak value T of the surface temperature corresponding to the region where a layer with high thermal conductivity is provided corresponding to the defoaming position. For which difference 6 teeth (・TO), the average value V of the droplet ejection speed and the standard deviation of the speed Ov
is plotted. However, the temperature difference ΔT here is a value with no ink present in the liquid path.

As is clear from the figure, when the temperature difference ΔT is 20° C. or more, σV becomes almost constant and the discharging variation becomes stable, but when it exceeds 100° C., it was confirmed that the average speed V decreases. From this, in this case, the temperature difference ΔT is 20°C
It can be seen that the temperature is preferably 100°C or less.

More preferably, when the standard deviation of the liquid ejection speed can be ignored to some extent, that is, when the liquid ejection speed is mainly considered, ΔT is 20° C. or more and 60° C. or less, and the liquid ejection speed can be ignored to some extent. In other words, when the above standard deviation is mainly considered, ΔT is 25°C.
The temperature was above 100°C. Furthermore, most preferably,
ΔT was 25°C or more and 60°C or less.

Furthermore, in this example, the dimensions of the area including the defoaming position where the highly thermally conductive layer is provided are determined appropriately.

FIG. 4 shows the heat generating area area S of the region. and the total heat generating area Sll of the heat generating resistor. /Sll, ■ and Ov are plotted. As is clear from the figure, it was confirmed that when S, /S□ was set to 1/10 or more and 1/2 or less, the V and σν values became stable and the ejection performance became good.

More preferably, when the standard deviation of the liquid discharge rate can be ignored to some extent, that is, when the liquid discharge rate is mainly considered, So/SH is 1/10 or more or 1/10.
4 or less, and 5 (1
15N was 178 or more and 172 or less. Furthermore, most preferably, So/So is 1/8 or more and 1/4 or less.

(Example 1) Figures 5 (^) and (B) show a first example of the substrate according to the present invention, and are respectively a plan view along the liquid path direction and its A in Figure 1 (A). -A' line sectional view.

Here, l is a substrate having a thickness of 525 μm, for example, and can be formed of glass, Si, or the like. 2 is a surface oxidized 5i02 layer with a thickness of 25 μm, which is used as a heat storage layer. 3 is II f B formed by sputtering, for example, with a thickness of 0.1 μm, a width of the heat generating part of 30 μm, and a length of the heat generating part of 150 μm.
The heating resistor layer consists of 2, and is located under the part including the position where the bubble disappears (nearly the middle of the current path between the electrodes 4, if 11kjZ2 in equation (2)). A layer 9 with a high rate is arranged. Reference numeral 4 denotes an electrode such as A1 having a thickness of 0.5 μm formed by, for example, an EB evaporation method.

5 has a thickness of 1, sμ formed by sputtering, for example.
+11 is a layer of SiO, SiN, etc., 6 is a layer of Ta2O, etc. with a thickness of 0.1 μm formed by a sputtering method, and 7 is a layer of Ta, etc. with a thickness of 0.5 μm formed by a sputtering method. , these act as a protective layer. Further, 8 is a liquid to be boiled.

9 is a layer having high thermal conductivity disposed between the above portion of the heating resistor layer 3 and the storage layer 2, and in this example, SIC
layered. In this example, the temperature difference Δ between the thickness d of the layer 9 and the dry firing state (when electricity is applied without introducing ink)
The relationship with T was as follows.

Therefore, the thickness of the 516 layer 9 is 0.2 μm or more and 1.5 μm.
It is preferable that it is less than m, and in this example, dFo was set to 5 μm.

Further, the length of the layer 9 is 25 μm, and S is added here. =30x
25 (μm2), S, = 30x 150 (p m2)
and therefore S. Since /SH is 1/6, the condition explained for Figure 4 is also satisfied.

Note that the planar patterns of the heating resistor layer 3 and the electrodes 4 were formed by etching. Furthermore, as is clear from the figure, the corners at the connection between the electrode 4 and the heat generating resistor layer 3 are rounded to prevent deterioration in durability and local bubbling due to current concentration.

In such a configuration, when a voltage is applied between the electrodes 4,
A current flows through the heating resistor layer 3 and heat generation occurs.

The heat generated in the heat generating resistor layer 3 is transmitted to the lower part and the upper part, but in the part where the heat generating resistor layer 3 is in contact with the 516 layer 9, which has a higher thermal conductivity than the distribution layer (heat storage layer) 2, it is transmitted to the lower part and the upper part. More heat is transferred to the lower part than to the lower part, and as a result, less heat is transferred to the liquid 8 in the upper part of the layer 9 via the upper layers, the protective layers 5, 6 and 7.

When bubbles were actually generated using the substrate according to this example, as shown in FIG. It was observed that the heat transmitted to this part 3A was small;
Because the temperature is lower than that of the remaining part, even if residual gas adheres, random nucleate boiling does not occur from there and disturb bubble generation, and film boiling occurs from the remaining part with extremely high reproducibility. Ta. In this case, the shape and size of the bubbles were constant each time. When this substrate was used as a recording head as shown in FIG. 1 to perform recording, the droplet diameter and ejection speed were uniform, and a good image was obtained.

The high reproducibility of boiling in parts other than the upper part 3^ of the heating resistor layer 3 that is in contact with the layer 9 with high thermal conductivity is because there is no residual gas attached and the liquid 8 is rapidly heated. This is because the liquid 8 reaches near the superheating limit and bubbles are formed due to a spontaneous nucleation phenomenon based on the movement of molecules inside the liquid.

Comparative example FIG. 7 (conventional example) shows air bubbles using an electrothermal converter having the same configuration as the present example except that the layer 9 with high thermal conductivity was not provided under the heating resistor layer 3. The diagram shows a case where bubble generation occurs, and unlike the present example, random nucleate boiling occurs from the location where the bubble 10 disappears, and the reproducibility of bubble generation is reduced.

In other words, in the case of (a) in the figure, the location where nucleate boiling occurs is 1.
Although relatively good bubble generation was achieved in some places,
Such bubble generation does not always occur, and nucleate boiling may occur from multiple locations as shown in (b) or (C) in the figure, in which case thermal energy is transferred to the liquid by nucleate boiling heat transfer. The bubble volume will become smaller. In such an example, the shape and size of the bubbles are not constant, so when the recording head is configured and recorded,
It was observed that variations occurred in the droplet diameter and ejection speed, and the quality of the image deteriorated.

FIG. 8 shows a modification of this embodiment.

In this example, the layer 9 with high thermal conductivity has a circular shape with a diameter of 20 μm.

This example also has the advantage that not only the same effects as the example of FIG. 1 can be obtained, but also the heat transfer loss to the lower part can be suppressed.

Note that an elliptical, rectangular, etc. area may be used instead of the circular area. In any case, the upper part of the layer 9 with high thermal conductivity is the 9th layer.
As shown in the figure, if the part where the bubbles 10 disappear is included inside, the nucleate boiling suppressing effect will be increased (in the illustrated example, the layer 9 has an elliptical shape).

Moreover, as shown in FIG. 1θ, if the center part 9-1 of the layer 9 with high thermal conductivity is located below the inside of the circle or ellipse 11 with the largest area inscribed in the heating resistor, The effect of suppressing heat conduction increases.

(Example 2) FIG. 11 shows a second embodiment.

In this example, after forming a recess 12 with a depth of 0.5 μm on a Si substrate 1, a surface oxidation layer 2 is formed to a thickness of 0.5 μm to fill the recess appearing on the layer 2. μm
A SiC layer 9 was formed. Other than this, the configuration was the same as that of the embodiment shown in FIG.

In this example as well, the same effect as the example shown in the third figure was obtained, and since there was no step on the heat transfer surface, an excellent effect was also obtained in terms of durability.

In this embodiment as well, the layer 9 has a circular shape, as described with reference to FIGS.
Of course, the shape can be elliptical, rectangular, etc.

As described above, the layer 9 having a higher thermal conductivity than the substrate 1 may be formed in any manner as long as the position where the bubbles disappear is completely included.

In the above two embodiments and their modifications, the thickness between the heating resistor layer 3 and the heat storage layer 2, which is the lower layer, is 0.5 mm.
Although the SiC layer is 0.5 μm thick, the thickness is not necessarily 0.5 μm.
It doesn't have to be l. Further, any material may be used as long as it has a higher thermal conductivity than the lower layer, and depending on the material of the lower layer, for example, Si may be used.

Furthermore, in the above two embodiments and their variations,
Although the upper part of the heating resistor layer 9 has a layered structure consisting of 5i02°Ta205 and Ta, it may have another structure or a structure without an upper layer.

In addition, the material forming the lower layer (heat storage layer) is 5 inches.
It may be a material other than 2, for example, glass, alumina, etc. Then, the layer 9 may be formed of a material having higher thermal conductivity than this.

(Example 3) In the above example, a case was described in which the present invention was applied to a recording head in which the liquid path was linear. As shown, even if the discharge is perpendicular to the substrate 1', there is a layer of high thermal conductivity under the heating resistor layer 107' in the portion including the illustrated defoaming position 13'. By providing the layer, the same rubbing effect as described above can be obtained.

(Further Other Embodiments) In addition, recording heads having an electric heat exchanger having a shape capable of expressing gradations that have been developed in recent years, such as the one disclosed in Japanese Patent Publication No. 59-31943 proposed by the applicant. It can also be effectively applied to things. In other words, the electrothermal converter has a structure (heat generation amount adjustment structure) that generates a temperature distribution that can be controlled according to the level of the signal input manually in the heat generating part, and the bubbles are adjusted in multiple stages according to the signal level. The present invention can also be applied to a recording head having a similar configuration.

For example, in the electrothermal converter shown in FIGS. 13(A) to 13(C), if the defoaming position is at the position indicated by the reference numeral 13'', the electrothermal converter is A layer 9'' having high thermal conductivity may be provided below the body 107'' or the heating resistor layer 3''. Furthermore, if the bubble extinguishing position differs depending on the size of the generated bubbles, a plurality of such layers 9'' may be provided (see the portion indicated by the dashed line in FIG. 11(A)).

In addition, in order to adjust the air bubbles in multiple stages, we have developed a structure in which the layer thickness of the heating resistor layer is varied along the direction of the mold temperature (Japanese Patent Application Laid-Open No.
31943), and a structure in which the thickness of the heating resistor layer is gradually increased toward the center line (Japanese Patent Laid-Open No. 62-20
1255).

In addition, the present invention is of course applicable to any device that uses an electrothermal converter as a discharge energy generating means without being limited to the integrated type shown in FIG. Needless to say, the present invention can also be applied to a scanning type print head or a full multi-type print head in which ejection ports are selected over the entire width of the print medium.

[Effects of the Invention] As explained above, according to the present invention, boiling can be prevented by arranging a substance with high thermal conductivity at the bottom of the heat generating resistor layer in the portion including the position where bubbles disappear. The effects of improved reproducibility and improved image quality were obtained.

[Brief explanation of the drawing]

1A and 1B are respectively an exploded perspective view and a front view of a liquid jet recording head according to an embodiment of the present invention; FIG. 2 is an explanatory diagram for explaining the defoaming position; Figure 3 is an explanatory diagram for explaining the range of temperature difference that is optimal for discharge, Figure 4 is an explanatory diagram for explaining the area ratio, and Figures 5 (A) and (B) are respectively FIG. 6 is an explanatory diagram showing bubble behavior when the present invention is used, and FIG. 7 is a plan view showing bubble behavior in the conventional example. 8 to 10 are plan views showing modified examples of the first embodiment of the present invention, FIG. 11 is a sectional view of a substrate according to the second embodiment of the present invention, and FIG. 12 is a main An explanatory diagram showing a recording head according to a third embodiment of the invention. FIGS. 13A to 13C are plan views showing still another embodiment of the invention. 1.1'...Substrate, 2...Heat storage layer, 3.3', 3''...Heating resistor layer, 4...Electrode, 5...Protective layer (St(la), 6) ...Protective layer (razos), 7...Protective layer (Ta), 8...Liquid, 9.9', 9''...SiC layer, 1O...Bubble, 12...Recessed part, 13', 13''... position where bubble disappears. Fig. 2 (TH-To) = ΔT Fig. 3 01/10 1/2 So/SH Fig. 4 Easy request A Fig. 6 Fig. 7 Convex No. 11 Figure p Above mouth Figure 12 Figure 13

Claims (1)

[Scope of Claims] 1) A support, a heat storage layer disposed on the support, a heating resistor layer, and a pair of electrodes electrically connected to the heating resistor layer, the pair of electrodes being electrically connected to the heating resistor layer. an electrothermal converter in which a heat generating part is formed on the heat storage layer between the electrodes, and a position where bubbles generated in the recording liquid on the recording liquid contact surface corresponding to the heat generating part disappear. A thermally conductive layer is provided between the electrothermal converter and the heat storage layer in accordance with the included portion, and is made of a material having higher thermal conductivity than the heat storage layer, and ΔT=T_H−T_O is 20°C. More than 100℃
A substrate for a liquid jet recording head characterized by the following: T_O: Peak value of the temperature in the driving state of the electrothermal transducer when no recording liquid is present at the position. T_H: Peak value of temperature at a position other than the above position in the driving state of the electrothermal transducer when no recording liquid is present. 2) More preferably, the ΔT is 20° C. or more and 60° C. or less when mainly considering the ejection speed of the recording liquid, and 25° C. when mainly considering the standard deviation of the ejecting speed of the recording liquid. 2. The substrate for a liquid jet recording head according to claim 1, wherein the ΔT is greater than or equal to 25°C and less than or equal to 60°C, most preferably greater than or equal to 25°C and less than or equal to 60°C. 3) The length of the heat generating section along the liquid path of the recording liquid is proportionally distributed by the inverse ratio of the inertial component Z of the hydrodynamic impedance of the flow area on both sides of the heat generating section along the liquid path. 2. The substrate for a liquid jet recording head according to claim 1, wherein the position where the bubble disappears is set as the position where the bubble disappears. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [x: Position in the flow direction of the basin of interest, l
: Length of the basin of interest, S(x): Cross-sectional area of the liquid path at position x, ρ: Density of the recording liquid] 4) Height of the liquid path at position x taken in the flow direction of the recording liquid with respect to the basin When the length is h(x), the position where the length of the heat generating part is proportionally distributed by the inverse ratio of ▲ There are mathematical formulas, chemical formulas, tables, etc. on both sides is set as the position where the bubble disappears. 4. The substrate for a liquid jet recording head according to claim 3. 5) Area S_O on the heat generating part corresponding to the part
and the total area S_H on the heat generating part S_O/S_
H is preferably 1/10 or more and 1/2 or less, more preferably 1/1 when mainly considering the liquid ejection speed.
A claim characterized in that the ratio is 10 or more and 1/4 or less, and when the standard deviation of liquid ejection speed is mainly considered, 1/8 or more and 1/2 or less, most preferably 1/8 or more and 1/4 or less. 1. The substrate for a liquid jet recording head according to 1. 6) comprising a support, a heat storage layer disposed on the support, a heating resistor layer and a pair of electrodes electrically connected to the heating resistor layer, between the pair of electrodes; an electrothermal converter in which a heat generating portion is formed on the heat storage layer; and a portion corresponding to a portion including a position where bubbles generated in the recording liquid on a recording liquid contact surface corresponding to the heat generating portion disappear. a thermally conductive layer disposed between the electrothermal converter and the heat storage layer and made of a material having higher thermal conductivity than the heat storage layer, and ΔT=T_H−T_O is 20°C or more and 100°C.
A liquid jet recording head comprising: a base as described below; and a member provided on the base to form a liquid path for the recording liquid. T_O: Peak value of the temperature in the driving state of the electrothermal transducer when no recording liquid is present at the position. T_H: Peak value of temperature at a position other than the above position in the driving state of the electrothermal transducer when no recording liquid is present. 7) More preferably, the ΔT is 20° C. or more and 60° C. or less when mainly considering the ejection speed of the recording liquid, and 25° C. when mainly considering the standard deviation of the ejecting speed of the recording liquid. 7. The liquid jet recording head according to claim 6, wherein the ΔT is set to be at least 25 degrees Celsius and not more than 60 degrees Celsius, most preferably at least 25 degrees Celsius and not more than 60 degrees Celsius. 8) The length of the heat generating section along the liquid path of the recording liquid is proportionally distributed by the inverse ratio of the inertial component Z of the hydrodynamic impedance of the basin on both sides of the heat generating section along the liquid path. 7. The liquid jet recording head according to claim 6, wherein the position where the bubble disappears is determined as the position where the bubble disappears. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ 9) Position X of the basin in the flow direction of the recording liquid
Let h(x) be the height of the liquid path at 9. The liquid jet recording head according to claim 8, wherein the liquid jet recording head is at a position where the liquid jet recording head disappears. 10) Area S_O on the heat generating part corresponding to the part
and the total area S_H on the heat generating part S_O/S_
H is preferably 1/10 or more and 1/2 or less, more preferably 1/1 when mainly considering the liquid ejection speed.
A claim characterized in that the ratio is 10 or more and 1/4 or less, and when the standard deviation of liquid ejection speed is mainly considered, 1/8 or more and 1/2 or less, most preferably 1/8 or more and 1/4 or less. 6. The substrate for a liquid jet recording head according to 6.