MXPA96002527A - Inch jet registration head and it chip registration apparatus - Google Patents

Abstract

The present invention relates to an ink jet recording head comprising an ink flow path having a discharge opening for discharging an ink, a lower layer for accumulating heat, a resistance layer which is provided in the layer lower, a pair of electrical connection electrodes provided in the resistor layer for applying an electrical signal to the resistive layer, and an electrothermal transducer that is provided to correspond to the ink flow tratyectoria, employing the resistance layer between the electrical connection electrodes as a heat generating portion, wherein the heat generating portion has a high temperature section and a low temperature section when driven, and a limit at which the thickness of the protective layer varies in the low temperature section

Description

"INK JET REGISTRATION HEAD AND INK JET REGISTRATION APPARATUS" BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The present invention relates to an ink jet recording head and an ink jet recording apparatus employing the ink jet recording head.

BACKGROUND OF THE RELATED ART The ink jet recording system as disclosed, for example, in the Patent Application Japanese No. 54-51837, has characteristics different from other ink jet recording systems, since the driving force of the discharge of the liquid droplets is derived by application of thermal energy to the liquid. More specifically, in the ink jet recording method disclosed in the aforementioned gazette, a liquid is heated by application of thermal energy to form a bubble, and the liquid droplet is discharged, by the action of the force generated by the formation of the bubble, through a discharge opening in the tip portion of the registration head so that it is allowed to deposit towards a recording medium to record the information therein. The ink-jet recording head (hereinafter referred to simply as a "registration head") employed in the ink-jet recording system is provided with a discharge portion f of the ink. The portion of peel, by, " Generally, it comprises a discharge opening for discharging the liquid, a liquid path that communicates with the discharge opening, and a heat generation means that is provided in the liquid path to apply the thermal energy to the liquid. An example of the medium The heat generator is an electrothermal transducer comprising an inner layer for heat accumulation, a resistance layer having a heat generating portion, a pair of electrical installation electrodes for supplying electricity to the resistance layer, and a protective layer to protect the electrical installation electrodes against the ink. From the point of view of the design of the registration head, the one protective layer is preferably formed as thin as possible or more preferably not way, in order to effectively transfer the thermal energy to the ink. However, in conventional recording heads, the protective layer had to be formed coarse in and around the edge portion between the heat generating portion and the electrical installation electrodes to protect the electrode from electrical installation because the electrodes Electrical installation is formed thick to reduce the electrical resistance with a large height of the electrode pattern. On the other hand, the resistance layer is relatively thin compared to the electrical installation electrodes since the resistance layer has high electrical resistance. Accordingly, the protective layer can be made thin in the heat generating portion of the resistance layer region (the region of the resistance layer that lies between the pair of electrical installation electrodes and does not have an electrical installation electrode constituted therein). Japanese Patent Application Number 60-236758 proposes the formation of the protective layer to be thin in the heat generating portion. However, it does not specifically consider where the protective layer should get thinner.

Japanese Patent Application Number 63-191645 discloses electrical installation electrodes that are provided below the resist layer in a portion of the organic protective layer covering the heat generating portion to decrease the temperature rise of the portion of the organic protective layer, since the organic protective layer is less resistant to heat. Nevertheless, this arrangement is used taking into account the durability of the protective layer, but the relationship with the resistance layer is not taken into account. Japanese Patent Application Number 55-126462 discloses a layer constitution that does not have a protective layer. The strength layer in this layer constitution must have sufficient ink resistance, having excellent electrochemical properties at an elevated temperature, and being resistant against cavitation caused by the disappearance of the bubble. The material suitable for the strength layer having the aforementioned properties includes Al-Ta-Ir disclosed in Japanese Patent Application Number 01-46769 and Ta-Ir disclosed in the Japanese Patent Application. Number 02-55131. However, in the recording head having a thinner protective layer in the heat generating portion, the durability of the discharge varies depending on the thickness of the protective layer, and may be less than the discharge characteristics. The lower discharge characteristics are found to result from causes that are mentioned below by failure of analysis. The first cause is that a crack appears in the thin portion of the protective layer, and the ink penetrates through the crack formed to react with the resistance layer to a # high temperature to destroy it. The second The cause is that the thermal stress of the protective layer against the resist layer breaks the resistance layer in the thin portion of the protective layer. More specifically, the protective layer is formed relatively thicker in the electrode layer of electrical installation to cover the level difference of the electrode pattern and form as thin as possible in the portion * heat generator. Therefore, the thick region and thin region of the protective layer exist in the heat generating portion at and around the boundary of the the heat generating portion of the electrical installation electrode (see Figures 9A and 9B). When the heat generating portion of the resistance layer generates heat, the difference in heat expansion between the coarse region and the thin region of the protective layer imposes a Effort between these regions to cause cracking of the protective layer or damage to the lower resistance layer to finally destroy the resistance layer by high temperature reaction with the ink having penetrated through the crack of the protective layer. Otherwise, the resist layer below the limit of the coarse portion and the thin portion of the protective layer can be broken by the aforementioned effort of the protective layer. In particular, in the present invention an ink jet system is employed which discharges the ink by boiling pressure of the ink film, and the heat is generated abruptly in a very short period of time in the heat generating portion. the resistance layer to impose a greater heat stress on the upper protective layer. The effort is more intense in the portion where the thickness of the protection is changed. On the other hand, in a similar ink discharge test using a registration head in which the heat generating portion of the resistance layer is placed in direct contact with the ink (namely no protective layer in the heat generating portion). , see Figures 10A and 10B) the durability varies around the boundary between the protected and unprotected regions, similarly in the log head having a protective layer. As a result of the failure of the analysis, the first cause is the great difference of the effort in the protective layer 5 between the protected and unprotected regions of the resistance layer in the generation of heat to break the resistance layer, similarly to the second cause mentioned above. The second cause in 'W this case is the electrochemical reaction. In particular, when the strength layer becomes thinner to raise the strength of the blade for weaker current drive, in order to use an economical driving element, the potential difference in the resistance layer becomes larger, which accelerates the electrochemical reaction to cause the disintegration of the resistance layer in a short period of time. The disintegration of the resistance layer by the electrochemical reaction is considered to below for a layer constitution in which the heat generating portion is brought into direct contact with the ink. The disintegration of the resistance layer by the electrochemical reaction is considered as a result of the causes that will be presented below: (1) Attack by the alkali metal ions against the negative electrode portion: The resistance layer and the heat accumulation layer have the possibility of being attacked by electrochemical reaction especially in the end portion of the pattern of the resistance layer, and (2) The dissolution of the resistance layer in the positive electrode portion. # The electrochemical reaction is accelerated by the following factors: (i) Voltage: A higher driving voltage for the resistance layer increases the potential difference in the heat generating portion by accelerating the electrochemical reaction. 15 (ii) Temperature: A higher temperature naturally accelerates the reaction, since the electrochemical reaction is a kind of chemical reaction. This depends on the ratio of the driving voltage, the voltage of the formation of the bubble and the width of the impulse motor. (iii) Heating time: The progress of the electrochemical reaction depends on the heating time within a pulse, or the width of the drive pulse. (iv) Ink Class: The electrochemical reaction is affected naturally by the species of ion contained in the ink. (v) The material and the thickness of the resistance layer: The electrochemical reaction depends of course on the material of the resistance layer. The time that has passed before the disintegration depends on the thickness of the layer. The greater the thickness, the longer is the time that passes before the disintegration. The progress of the electrochemical reaction varies with the causes mentioned above. In particular in a weaker electric current drive with a less costly drive element to reduce the cost, a higher leaf strength is required for the resistance layer, which decreases the durability of the discharge. The lowest durability to highest blade strength is considered in the following manner. The higher blade strength increases the potential difference in the resistance layer to accelerate the electrochemical reaction. The lower thickness of the resistance layer results in insufficient anti-electrochemical reaction properties. These two causes can decrease the ejection durability.

In addition, the electrochemical reaction is accelerated by various factors such as higher drive voltage with a certain pattern design of the resistance layer; highest maximum temperature of the resistance layer due to the variation in the production of the recording heads at a uniformized driving voltage for cost reduction; and the use of different inks for different registration paper. Therefore, a layer of # material and a layer constitution that are more stable electrochemically. As described above, a measure is required to fill the thickness change of the protective layer in the heat generating portion, in order to improve the durability of the discharge, regardless of the presence or absence of the protective layer in the portion heat generator of the jjK- resistance layer.

SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet recording head which exhibits excellent discharge durability, irrespective of the kind of ink and which is producible at a lower cost without the disadvantages mentioned above. Another object of the present invention is to provide an ink jet recording apparatus employing the aforementioned ink jet recording head. In accordance with one aspect of the present invention, there is provided an ink jet recording head comprising an ink flow path having a discharging aperture for discharging an ink, a lower layer for accumulating heat, a layer for resistance that is provided in the lower layer, a pair of electrical connection electrodes that are provided in the resistance layer to apply an electrical signal to the resistance layer, and an electrothermal transducer, which is provided to match the flow path of ink, using the resistance layer between the electrical connection electrodes as the heat generating portion, wherein the heat generating portion has a high temperature section and a low temperature section when it is driven and a limit at which the temperature varies. Thickness of the protective layer is placed in the low temperature section. In an embodiment of the ink jet recording head, the high temperature section and the low temperature section are provided by making the width of the resistance layer forming the heat generating portion non-uniform. In another modality, from the registry head of ink jet, the high temperature section and the low temperature section are provided by making the thickness of the resistance layer forming the heat generating portion non-uniform. r-, p In yet another mode of. the head of The ink jet register, the high temperature section and the low temperature section are provided by making the thickness of the lower layer corresponding to the heat generating portion non-uniform. In an additional mode of the head of The ink jet register, the high temperature section and the low temperature section are provided by making the thermal conductivity of the lower layer corresponding to the heat generating portion non-uniform. In yet a further embodiment of the ink jet recording head 20, the limit at which the thickness of the protective layer varies is the boundary between the thin region and the thick region of the protective layer. In still a further embodiment of the ink jet recording head, the limit at which the The thickness of the protective layer is the limit between the region * that has the protective layer and the region that does not have the protective layer. In another aspect of the present invention, there is provided an ink jet recording apparatus having the aforesaid ink jet recording head and a means for supplying a recording medium. The present invention allows the reduction of the thickness of the protective layer, or the omission of the layer protective without deteriorating the durability of the recording head whereby the energy saving of the entire recording head can be achieved, and the temperature rise of the body of the recording head during printing can be reduced. In addition, the ink jet recording head of the present invention has discharge durability Pf high, and given the high print quality and high printing stability due to the sufficient bubble stability in the nozzle and the stability of descaraga elevated. Due to the high discharge stability, a less expensive drive unit is available at a lower driving current and at a uniform driving voltage, allowing the production of an ink jet recording head at a lower cost. In addition, the ink jet recording apparatus employing the ink head is applicable to a variety of printing paper due to the high durability of the recording head against the different kinds of inks.

BRIEF DESCRIPTION OF THE DRAWINGS Figures 1A and IB are sectional and plan views for explaining a heater board of a first embodiment of the ink jet recording head of the present invention, respectively; Figures 2A and 2B are sectional and plan views for explaining a heating board of a second embodiment of the ink jet recording head of the present invention, respectively; Figures 3A and 3B are sectional and plan views for explaining a heating board of a third embodiment of the ink jet recording head of the present invention, respectively; Figures 4A and 4B are sectional and plan views for explaining a heater board of a fourth embodiment of the ink jet recording head of the present invention, respectively; Figures 5A and 5B are sectional and plan views for explaining a heater board of a fifth embodiment of the ink jet recording head of the present invention, respectively; Figures 6A and 6B are sectional and plan views for explaining a heater board of the sixth embodiment of the ink jet recording head of the present invention, respectively. H.H? Figures 7A and 7B are sectional views and plant for explaining a heater board of the seventh embodiment of the ink jet recording head of the present invention, respectively; Figures 8A and 8B are sectional and plan views for explaining a one-octave heater board mode of the ink jet recording head of the present invention, respectively; 'wj Figures 9A and 9B are sectional and plan views for explaining a heater board of a conventional ink jet recording head, respectively; Figures 10A and 10B are sectional and plan views for explaining a heater board of a conventional ink jet recording head, respectively; and Figure 11 is a perspective view of an ink jet recording head of the present invention.

DESCRIPTION OF THE PREFERRED MODALITIES The present invention is described below in greater detail with reference to the drawings. Figures 1A and IB illustrate an example of a heater board of an ink jet recording head of a first embodiment of the present invention. Figure IB is a plan view of the heater board and Figure 1A is a sectional view taken along line 1A-1A in Figure IB. In Figure 1A, the heater board comprises a substrate 101, an inner layer 102 for heat accumulation, a resistance layer 103, a pair of layers 104 of the electrical connection electrode for supplying electricity to the resistance layer, a protective layer 105 for protecting the resistance layer and the electrical connection electrodes against the ink , a second protective layer 106 and a third protective layer 107. The number 108 indicates a heat generating portion of the resistance layer between the pair of electrical installation electrodes and the number 109 indicates a thin region of the protective layer 105. In Figure IB, the number 108 indicates the heat generating portion and the number 109 indicates the thin region of the protective layer. The second protective layer is provided to retard the cavitation caused during the disappearance of the bubble. The third protective layer (organic protective layer, or the like) is provided to further reduce the short-circuit and damage caused by penetration of the ink. These protective layers are optionally provided for the improvement of functionality. This is also the case for the second and third protective layers in Figures 2A, 2B, 3A, 3B, 4A and 4B. In the first embodiment it is characterized in that the width of the pattern of the resistance layer is partially changed to form a high temperature section and a low temperature section of the heat generating portion when it is driven, and that the limit at which the temperature varies. Thickness of the protective layer is placed in the low temperature section. In other words, the width of the pattern of the heat generating portion 108 of the resistance layer 103 becomes wider to reduce the density of electric current in and around the edge of the pattern between the heat generating portion 108 and the layers 104. of electrode for electrical installation. In this way, the temperature rise is retarded in and around the edge of the pattern to provide the low temperature section. By placing the limit at which the thickness of the protective layer varies in the low temperature section, the thermal stress produced in the protective layer 105 can be reduced in and around the edge of the aforementioned pattern. An excessively large pattern width in a part of the heat generating portion increases a rate of change in the width of the pattern to cause concentration of the electric current to the change portion, leading to the disintegration or damage of the heat generating portion. . The relation (B / A) of the change in the width of the preference pattern is within the scale of 1.2 to 2.8, more preferably from 1.2 to 2.5. The pattern width of the sheet resistance layer of the electrical connection electrode layer is not particularly limited but is preferably greater than the width of the pattern (A) of the heat generating portion, and may be the same as the width (B) of the pattern of the heat generating portion as shown in Figure IB. Further, in the first embodiment, as shown in Figures 1A and IB, a thin region 109 of the protective layer is formed in the region of the heat generating portion that becomes a high temperature section during the drive. This thin region 109 of the protective layer is formed in the aforementioned heat generating portion of the strength layer in such a way that the boundary between the thick and thin regions of the protective layer is placed in the area of the wide pattern width. aforementioned of the heat generating portion (low temperature section during the drive). Since the area of the wide pattern width in the vicinity of the edge of the pattern between the heat generating portion and the connecting electrode layer electrical causes less elevation of temperature during the drive, less thermal stress occurs at the boundary between the thin and thick regions of the protective layer in the area of the broad pattern of the heat generating portion, and the disintegration or damage of the layer protective of the resistance layer by thermal stress has less chance of occurring. The region 109 of the thin protective layer is formed in such a way that any other boundary between the thick and thin regions of the protective layer does not remain on or around the edge of the aforementioned pattern, is placed outside of the heat generating portion. This is also carried out in the prior art (Figure 9B and Figure 10B). In the first embodiment, in Figures 1A and IB, of limit at which the thickness of the protective layer varies that boundary between the thin region and the thick region of the protective layer (particularity of the fifth modality). The position of the limit is decided similarly in the same way as in the case where the limit at which the thickness of the protective layer varies is the boundary between a region 505 formed with a protective layer and a non-covered region 509 (the sixth mode) as shown in Figures 5A and 5B. In other words, on the heater board where the heat generation portion of the layer of resistance is not protected by a protective layer and is put in direct contact with the ink, the boundary between the region covered by the protective layer and the uncovered region of places in the broad pattern wide area of the portion heat generator so similar to the first modality previously mentioned. Figures 2A and 2B illustrate an example of a heater board of an ink jet recording head of a second embodiment of the present invention. Figure 2B is a plan view of the heater board, and Figure 2A is a sectional view taken along the line 2 -2A in Figure 2B. In Figure 2A, the heater board comprises a substrate 101, a lower layer 102 for heat accumulation, a resistor layer 203, a pair of electrically connected electrode layers 104 for supplying electricity to the resist layer, a protective layer 105 for protecting the resist layer and the electrical connection electrodes against the ink, a second protective layer 106 and a third protective layer 107. The number 208 indicates a heat generating portion of the resistance layer between the pair of electrical connection electrodes and the number 109 indicates a thin region of the protection layer 105. In Figure 2B, the number 208 indicates the heat generating portion and the number 109 indicates the thin region of the protective layer.

The second embodiment is characterized in that the thickness of the resistance layer is partially changed to form a high temperature section and a low temperature section of the heat generating portion when driven and that the limit at which the thickness varies of the protective layer is placed in the low temperature section. In other words, the resistance layer 203 of the heat generating portion becomes thicker at and around the edge of the pattern between the heat generating portion 208 and the layers 104 of the electrode electrical connection to reduce the density to the electric current in them. In this way, the temperature rise is retarded in and around the edge of the pattern to provide the low temperature section. Placing the limit at which the thickness of the protective layer varies In the low temperature section, the thermal stress produced in the protective layer 105 can be reduced in and around the edge of the aforementioned pattern. Excessively large thickness of the portion of the resist layer in the heat generating portion increases the rate of change in thickness to cause concentration of the electric current to the shifting portion, leading to the disintegration or damage of the generating portion of the hot. The regime (G / F) of the change in the thickness of preference is within the scale of 1.1 to 2.5, more preferably 1.2 to 2.0. The thickness of the resist layer under the layers of the electrical connection electrode is not particularly limited, but is preferably greater than the thickness (F) in the heat generating portion, and may be equal than the thickness (G) of the heat generating portion as shown in Figure 2A. In addition, in the second embodiment, as shown in Figures 2A and 2B, a thin region 109 of the protective layer is formed in the region of the generating portion. heat that develops when driven in a high temperature section. This thin region 109 of the protective layer is formed in the aforementioned heat generating portion of the strength layer in such a way that the boundary of the thick and thin regions of The protective layer is placed in the aforementioned thick zone of the heat generating portion (low temperature section during the drive) in the vicinity of the edge of the pattern between the heat generating portion and the electrical connection electrode layer. Since the thick zone of the resistance layer in the heat generating portion causes less elevation of temperature when it is driven, less thermal stress occurs at the boundary between the thin and thick regions of the protective layer in the thick zone of the portion 10. generating heat, and the disintegration or damage of the protective layer or the resistance layer by thermal stress is less likely to occur. In addition, the thin region 109 of the protective layer is formed in such a way that any other limit between the thick and thin regions of the protective layer that is not on or around the edge of the aforementioned pattern, is placed outside of the heat generating portion. This is also carried out in the previous techniques (Figure 9 and Figure 10B). 20 'In the second embodiment, in Figures 2A and 2B, the limit at which the thickness of the protective layer varies is the boundary between the thin region and the thick region of the protective layer (the particularity of the fifth mode). The limit position is decided similarly when The limit at which the thickness of the protective layer varies is the boundary between the region 505 covered with a protective layer and the uncovered region 509 (the sixth embodiment) as shown in Figures 6A and 6B. In other words, in the heater board where the heat generating portion of the resist layer is not protected by a protective layer and placed in direct contact with the ink, the boundary between the region covered by the protective layer and the region not covered is placed in the thick layer area of the resistance layer in the portion heat generator in a manner similar to the second embodiment mentioned above. Figures 3A and 3B illustrate an example of a heater board of an ink jet recording head of a third embodiment of the present invention. The Figure 3B is a plan view of the heater board and Figure 3A is a sectional view taken along the line 3A-3A in Figure 3B. In Figure 3A, the heater board comprises a substrate 101, a lower layer 302 for heat accumulation, a resistance layer 303, a pair of layers 104 of the electrical connection electrode for supplying electricity to the resistance layer, a protective layer 105 for protecting the resistance layer and the electrical connection electrodes against the ink, a second protective layer 106 and a third layer 107 protective. The number 308 indicates a heat generating portion of the resistance layer between the pair of electrical connection electrodes, and the number 109 indicates a thin region of the protective layer 105. In Figure 3B, the number 308 indicates the heat generating portion, and the number 109 indicates the thin region of the protective layer. The third embodiment is characterized in that the thickness of the lower layer is partially changed to form a high temperature section and a low temperature section of the heat generating portion, when is driven, and that the limit at which the thickness of the protective layer varies is placed in the low temperature section. In other words, the lower layer 302 becomes partially thinner below the heat generating portion in and around the edge of the pattern. between the heat generating portion 308 and the electrical connection electrode layer 104 compared to the other region below the heat generating portion. In this way, the temperature rise is retarded in and around the edge of the pattern to provide the section low temperature. By placing the limit at which the thickness of the protective layer varies in the region of low temperature, the thermal stress produced in the protective layer 105 can be reduced in and around the above-mentioned pattern edge.

The extreme thinness of the aforementioned lower layer part increases the rate of change in thickness to increase the temperature difference in that changing portion, leading to disintegration or damage of the heat generating portion. The rate (I / H) of the change in thickness of preference is within the range of 0.1 to 0.9, more preferably 0.2 to 0.8. The thickness of the lower layer below the layers of the electrical connection electrode is not particularly limited, but preferably is less than the thickness (H) of the lower layer in the heat generating portion, and may be the same as the thickness (I) of the lower layer in the heat generating portion as shown in the Figure 3A. Further, in the third embodiment, as shown in Figures 3A and 3B, a thin region 109 of the protective layer is formed in the region of the heat generating portion that becomes the high temperature region. when driving. This thin region 109 of the protective layer is formed above the lower layer mentioned above in such a way that the boundary of the thick and thin regions of the protective layer is placed in the aforementioned thin zone of the layer Lower portion in the heat generating portion (low temperature section during the drive) in the vicinity of the edge of the pattern between the heat generating portion and the electrical connection electrode layer. Since the resistance layer in the thin lower region exhibits less elevation of temperature when driven, less thermal stress occurs at the boundary between the thin and thick regions of the protective layer in this area of the layer, and the disintegration or damage of The protective layer or the resistance layer through thermal stress has fewer possibilities to occur. In addition, the thin region 109 of the protective layer is formed in such a way that any other boundary between the thick and thin regions of the protective layer that is not on or around the edge of the pattern mentioned above is placed outside of the heat generating portion. This is also carried out in the prior art (Figure 9B and Figure 10B). In the third embodiment, in Figures 3A and 3B, the limit at which the thickness of the protective layer varies is the boundary between the thin and thick regions of the protective layer (particularity of the fifth modality). The position of the limit is decided similarly when the limit to which the thickness of the protective layer is the boundary between a region 505 covered with a layer varies. protective and a 509 uncovered region (the sixth embodiment) as shown in Figures 7A and 7B. In other words, in the heater board in which the heat generating portion of the resist layer is not protected by a protective layer and placed in direct contact with the ink, the boundary between the region covered with the protective layer and the The uncovered region is placed in the thin layer region of the lower layer in the heat generating portion in a manner similar to the third embodiment mentioned above. Figures 4A and 4B illustrate an example of a heater board of an ink jet recording head of a fourth embodiment of the present invention. Figure 4B is a plan view of the heater board, and Figure 4A is a sectional view taken through the line 4A-_4A in Figure 4B. In Figure 4A, the heater board comprises a substrate 101, a lower layer 402a consisting of a material of low thermal conductivity, a lower layer 402b constituted of a material of high thermal conductivity, a layer 303 of resistance, a pair of layers 104 of the electrical connection electrode for supplying electricity to the resistance layer, a protective layer 105 for protecting the resistance layer and the electrical connection electrodes against the ink, a second protective layer 106, and a third layer 107 protective. The number 308 indicates a heat generating portion of the resistance layer between the pair of electrical connection electrodes and the number 109 indicates a thin region of the protective protective layer 105. In Figure 4B, the number 308 indicates the heat generating portion, and the number 109 indicates the thin region of the protective layer. The fourth embodiment is characterized in that the material of the lower layer is locally changed to constitute a high temperature section and a low temperature section of the heat generating portion, when it is driven, and that the limit at which the thickness of the Protective layer is placed in the low temperature section. In other words, the lower layer is locally made of a material having higher thermal conductivity than the region below the heat generating portion in and around the edge of the pattern between the heat generating portion 308 and the electrode layer 104 electrical connection than in another region of the lower layer. In this manner, the temperature rise is delayed at and around the edge of the pattern between the heat generating portion and the electrical connection electrode layer to provide the low temperature section. By placing the limit at which the thickness of the protective layer varies in the low temperature section, the thermal stress produced ^ P in the protective layer 105 can be reduced in and around the edge of the aforementioned pattern. The region 402b of the lower layer below the region of the heat generating portion at or around the edge of the pattern between the heat generating portion and the electrical connection electrodes, (namely, the region of low temperature during the drive) It is made of a higher thermal conductivity material than the region 402a of the lower layer below the generating portion of heat (namely, the high temperature region during the drive). For example, in the case where region 402a of the lower layer below the high temperature region is composed of SIO2, region 402b of the lower layer below the low temperature region is manufactures of SÍ3N4, AI2O3, or a similar material that has higher thermal conductivity than SÍO2. The material of the lower layer under the layers of the electrical connection electrode is not particularly limited but preferably it is a material having a thermal conductivity greater than the region 402a of the lower layer below the heat generating portion (the high temperature region during the drive), and may be a material equal to that of the region 402a below the heat generating portion. (the region of low temperature during the drive), as shown in Figure 4A. Further, in the fourth embodiment, as shown in Figures 4A and 4B, a thin region 109 of the protective layer is formed in the region of the heat generating portion that becomes a high temperature region during the drive. This thin region 109 of the protective layer is formed above the aforementioned heat generating portion of the lower layer in such a way that the boundary between the thick and thin regions of the protective layer is placed above the thermal conductivity zone. elevated from the lower layer in the heat generating portion (low temperature region during the drive) in the vicinity of the edge of the pattern between the heat generating portion and the electrical connection electrode layer. Since the layer of resistance in the lower region composed of a material of high thermal conductivity causes less elevation of temperature when boosting, less thermal stress is produced in the limit of thickness change of the protective layer in this zone, and the disintegration or damage of the protective layer or the resistance layer by thermal stress has less possibility to occur. In addition, the thin region 109 of the protective layer is formed in such a way that any other boundary between the thick and thin regions of the protective layer that is not on or around the edge of the aforementioned pattern is placed outside the generating portion of the protective layer. hot. This is also carried out in the prior art (Figure 9B and Figure 10B). In the fourth embodiment, in Figures 4A and 4B, the limit at which the thickness of the protective layer varies is the boundary between the thin and thick regions of the protective layer (the particularity of the fifth mode). The limit position is similarly decided when the limit at which the thickness of the protective layer varies is the boundary between a region 505 covered with the protective layer and an uncovered region 509 (the sixth embodiment) as shown in the Figures. 8A and 8B. In other words, in the heater board in which the heat generating portion of the resist layer is not protected by a protective layer and placed in direct contact with the ink, the boundary between the region covered with the protective layer and the The uncovered region is placed in the region of high thermal conductivity of the lower layer in the heat generating portion in a manner similar to the fourth previous embodiment. The ink jet recording head having the heater board of the present invention can be employed as a full line type recording head having multiple discharge openings through the full width of the recording region of a media of registration as shown in Figure 11. The registration head in Figure 11 comprises discharge openings 110, a heater board 111, a ceiling plate 112, and an ink supply opening 113. The present invention is especially effective for an ink jet recording head or an ink jet recording apparatus that performs the record allowing liquid droplets to fly using thermal energy. A typical constitution of the principle of this recording head and ink jet recording apparatus are disclosed for example in the Patents North American Numbers 4,723,129 and 4,740,796. The ink-jet recording systems based on this principle are applicable to any of the ink-jet registers of type on request and continuous type, especially effective for those of type upon request. In the on-demand type system, the recording is carried out in the following way: One or more driving signals are applied to an electrothermal transducer provided in a sheet or a liquid path that retains a liquid (ink) so that corresponds to the registration information to cause a sudden rise in the temperature of the liquid exceeding the nuclear boiling temperature to generate thermal energy in the electrothermal transducer, thereby causing the boiling of the film on the heat-activating surface of the the registration head to form bubbles in the liquid (ink) so that it corresponds one by one with the driving signal. The ink is discharged through the ink discharge opening * by growth and shrinkage of the bubbles and lets fly in the form of droplets of liquid. Pulsed impulse signals allow for the proper growth and shrinkage of the bubbles to achieve excellent ejection of ink. The appropriate impulse signals are described in U.S. Patent Nos. 4,463,359 and 4,345,262. The registration can be carried out more excellently using the conditions disclosed in US Pat. No. 3,313,124 with respect to the temperature rise regime of the heat drive surface. The ink jet recording head of the present invention can be constituted of a combination of a liquid droplet discharge opening, a liquid path, and a transducer Electro-thermal (liquid path construction '^ PE linear or rectangular liquid path construction) as described in the aforementioned patent specifications may be a construction in which a heat actuating surface is placed in a region of bending as disclosed in US Pat. Nos. 4,558,333 and 4,459,600. In addition, the present invention is also effective ? BB ^ in the constitution comprising a common slot for multiple electrothermal transducers as a discharge portion (disclosed in Japanese Patent Application Number 59-123670), and the constitution comprising an opening corresponding to the discharge portion for damping thermal energy pressure waves (That discloses in Japanese Patent Application Number 59-138461. The present invention is also effective for a full line type ink jet recording head having a length corresponding to the width of maximum record of the recording device. The full line type recording head can be either a combination of multiple registration heads or an integrated construction, as disclosed in the aforementioned patent specifications.

The ink jet recording head may be an interchangeable tip type recording head which can be electrically connected to the thin body of the ink jet recording apparatus or which can be fed with ink from the main body of the ink jet recording apparatus. same or may be a cartridge type registration head that is integrally provided with an ink tank. As the building unit of the ink-jet recording apparatus in the present invention, aThe recovery means for the recording head or a preliminary supplementary means are preferably used to achieve a more stable effect of the present invention.

Specifically, the means include a cover means for the registration head, a cleaning means, a means of pressing and suction, a preliminary heating means and a preliminary discharge means. The recording mode of the ink jet recording apparatus of the present invention may be a black color or otherwise mono-color mode, one mode multiple colors that employ different colors or a full color mode that employs mixed colors. The present invention is more effective for a film boiling system for the aforementioned inks.

The ink jet recording apparatus of the present invention includes an integrated or separate terminal for image performance of the information processing apparatus such as word and computer processors, and copying apparatus combined with a reading apparatus and facsimile apparatus that they have transmission and reception functions. The present invention is described in greater # detail referring to the examples without limiting the invention in any way.

Examples 1 to 7 An ink jet recording head having the constitution shown in Figures 1A and IB was prepared. On a silicon substrate such as the substrate 101, a SiO 2 layer of 2.0 micrometer thickness was formed as the lower layer 102 of heat accumulation by thermal oxidation. On the same, a layer of HfB2 of thickness of 0.1 micrometer was formed as the layer 103 of resistance by sputtering. This layer had a sheet resistance of 20 ohms / Pl. In addition, a Ti layer with a thickness of 0.005 25 micrometer and an Al layer with a thickness of 0.6 micrometer was formed as the layer 104 of the electrical connection electrode by means of vapor deposition. Then, a circuit pattern was formed for the heat generation portion 108 and the layer 104 of the electrical connection electrode by photolithography and chemical etching as shown in Figures 1A and IB. The dimensions of C, D and E in Figure IB were 100 micrometers, 120 micrometers, and 140 micrometers, respectively, and dimensions A and B are shown in FIG.

Table 1. A SiO2 layer 1.0 micrometer thick was formed thereon as the protective layer 105 by sputtering. Then the thin region 109 of 0.2 micrometer thickness of the protective layer was formed partially removing a 0.8 micron thick portion of the SiO2 layer by photolithographic modeling and dry chemical etching as shown in Figures 1A and IB. The thin region of the protective layer 105 had a J dimension of 40 micrometers, and a K-dimension of 130 micrometers. The boundaries of the thick region and thin region of the protective layer 105, near the edges of the pattern between the heat generation portion 108 and the electrical connection electrode layer 104, were placed over the wide pattern wide area (width B) of the heat generating portion.

Then, the second protective layer 106 was formed from Ta by sputtering and subsequent photolithography and dry chemical etching in a pattern as shown in Figure 1A. Finally, the third protective layer 2.0 of 2.0 micrometer thickness was formed by coating a photosensitive polyimide and subsequent modeling by photolithography.

The heater board prepared in what The above was used for the production of an ink jet recording head shown in Figure 11. The heater board 111, the nozzle walls were formed from a negative DF dry film by photolithography. On the same oligomer was attached to a glass ceiling plate 112 having an ink supply opening 113 for covering the walls of the nozzle. Finally, the resulting combination consisting of the heater board, the nozzle walls and the ceiling plate was cut in a configuration signaled simultaneously to form the discharge openings 110. In this manner the ink jet recording head of the present invention was produced.

Examples 8 to 13 An ink jet recording head having the constitution shown in Figures 2A and 2B was prepared. On the silicon substrate as the substrate 101, a SiO 2 layer of a thickness of 2.0 micrometers was formed as the lower layer 102 of heat accumulation by thermal oxidation. On the same, a layer of HfB2 was formed as the layer 203 of resistance by sputtering at a thickness G as shown in Table 2. In addition thereto, a layer of Ti was formed with a thickness of 0.005 micrometer and an Al layer of a thickness of 0.6 micrometer as the layer 104 of the electrical connection electrode by vapor deposition. Then, the circuit pattern for portion 208 of heat generation and layer 104 of the electrical connection electrode was formed by photolithography and chemical etching as shown in Figures 2A and 2B. A portion of the heat generation portion 208 was thinned to a desired thickness by photolithographic modeling and dry chemical etching as shown in Figure 2A. The thickness (F) of the thin zone is shown in Table 2. The dimension of the thin zone of the heat generating portion was 20 micrometers per 100 micrometers. This dimension of 100 micrometers corresponds to the dimension L in Figure 2A.

A layer of SIO2 of a thickness of 1.0 micrometer was formed on it as the protective layer 105 by sputtering. Then the thin region 0.2 micron thick of the protective layer was formed by partially removing the 0.8 micron thick portion of the SiO2 layer by photolithographic modeling and dry chemical etching as shown in Figures 2A and 2B. The thin region of the protective layer had a J dimension of 40 micrometers, and a dimension K of 130 micrometers in like manner as in Examples 1 to 7. The boundaries of the thick region and thin region of the protective layer 105 near the edge of the pattern between the heat generating portion 108 and the electrode layer 104 electrical connection was placed in the thick zone (thickness G) of the heat generating portion 208. Then, the second protective layer 106 of Ta was formed by sputtering, and subsequent photolithography and dry chemical etching in a pattern as shown in FIG.

Figure 2A. Finally, the third protective layer 2.0 of 2.0 micrometer thickness was formed by coating a photosensitive polyimide and subsequently molded by photolithography. The heater board prepared above was used for the production of an ink jet recording head shown in Figure 11. In heater board 111, the nozzle walls were formed of a negative DF dry film by photolithography. A glass ceiling plate 112 having an ink supply opening 113 for covering the walls of the nozzle was attached thereto. Finally, the resulting combination of the heater board, the nozzle walls and the ceiling plate was cut in a configuration indicated simultaneously to form the discharge openings 110. In this way, the ink jet recording head of the present invention was produced.

Examples 14 to 17 An ink jet recording head having the constitution shown in Figures 3A and 3B was prepared. On a substrate of silicon as the substrate, a layer of SiO2 was formed as the lower layer 302 of heat accumulation by thermal oxidation. This thermal oxidation was carried out in two steps. In the first step of thermal oxidation, the thermal oxidation was carried out to form a layer of SiO2 of thickness I. In the next step, a Si3N4 film was formed by CVD, a portion of the SiI3N4 film was removed from the area where the thickness of the lower layer of SÍO2 should be made larger (thickness H), leaving the film SÍ3N4 in the area for the thin bottom (thickness I). The area that has the removed SÍ3N4 film had a dimension of 30 micrometers per 100 micrometers. This dimension of 100 micrometers corresponds to the dimension M in Figure 3A. In the second step of thermal oxidation, on the removed area of SÍ3N4, the layer of 10 SÍO2 was also formed in a total thickness of H. After thermal oxidation, the SÍ3N4 film was removed by chemical etching. In this way, a lower layer 302 having a locally "different" thickness was formed on the substrate. The thicknesses H and I of the layer are shown in Table 3. On the same, the layer of HfB2 of a thickness of 0.1 micrometer was formed as layer 303 of resistance by sputtering. A layer of Ti of a thickness of 0.005 micrometer was formed on it, and a layer of Al of a thickness of 0.6 micrometer as the layer 104 of the electrical connection electrode by vapor deposition. Then the circuit pattern for the heat generation portion 308 and the electrical connection electrode layer 104 was formed by photolithography and etching chemical as shown in Figures 3A and 3B.

* A SiO2 layer of 1.0 micrometer thickness was formed thereon as the protective layer 105 by sputtering. Then the region 109 of thickness 0.2 micrometer of the protective layer was formed partially removing a portion of thickness of 0.8 micron layer of SiO 2 by photolithographic patterning and chemical dry etching as shown in Figures 3A and 3B. The thin region of the protective layer had a J dimension of 40 micrometers, and a dimension K of 130 micrometers in like manner as in Examples 1 to 7. The boundaries of the thick region and thin region of the protective layer 105 near the edges of the pattern between the heat generating portion 308 and the layer 104 of the electrical connection electrode placed on the thin zone (thickness I) of the lower layer 302. Then, the second protective layer 106 of Ta was formed by subsequent ionic bombardment and photolithography and dry chemical etching in a pattern as shown in Figure 3A. Finally, the third protective layer 2.0 of 2.0 micrometer thickness was formed by coating a photosensitive polyimide and subsequent molding by photolithography. The heater board prepared in what The above was used for the production of an ink jet recording head shown in Figure 11. In heater board 111, the nozzle walls were formed of a negative DF dry film by photolithography. A glass ceiling plate 112 having an ink su opening 113 for covering the walls of the nozzle was attached thereto. Finally, the resulting combination consisting of the heater board, the nozzle walls and the plate * of the ceiling was cut in a designated configuration 10 simultaneously to form the discharge openings 110. Therefore, the ink jet recording head of the present invention was produced in this manner.

Example 18 An ink jet recording head having the constitution shown in Figures 4A and 4B was prepared. Especially the face of the silicon substrate in the On the substrate, a layer of Si3N4 was formed in a thickness of 2.0 micrometers as the bottom layer. Then, the SÍ3N4 in the zone 402a of the lower layer where the thermal conductivity is going to be decreased was removed by photolithography and chemical etching in a zone dimension of 30 micrometers. per 100 micrometers. This dimension of 100 micrometers corresponds to dimension N in Figure 4A. On the area other than the recorded area, a photoresist pattern was formed. Then, a layer 402a of Si02 of 2.0 micrometer thickness was formed by sputtering. Then the photoresist material was removed. On the same, a layer of HfB2 of 0.1 micrometer was formed as layer 303 of resistance by sputtering. On the same, a layer of Ti of a thickness of 0.005 micrometer was formed, and an Al layer of thickness of 0.6 micrometer as the layer 104 of the electrical connection electrode by vapor deposition. Then, the circuit pattern for the heat generating portion 308 and the electrical connection electrode layer 104 was formed by photolithography and chemical etching as shown in FIG. shows in Figures 4A and 4B. A SiO2 layer of 1.0 micrometer thickness was formed thereon as the protective layer 105 by sputtering. Then the thin region 109 of »0.2 micrometer thickness of the protective layer was formed partially removing a 0.8 micron thick portion of the SiO2 layer by photolithographic modeling and dry chemical etching as shown in Figures 4A and 4B. The thin region of the protective layer had a J dimension of 40 micrometers, and a dimension K of 130 micrometers in a manner similar to the ß Examples 1 to l. The boundaries of the thick region and thin region of the protective layer near the edges of the pattern between the heat generating portion 308 and the electrical connection electrode layer 104 were placed in the portion of the resistance layer in the region 402b of the lower layer made of a material of high thermal conductivity. Then, the second protective layer 106 of Ta was formed by ion bombardment, and photolithography and etching Subsequent dry chemistry in a pattern as shown in Figure 4A. Finally, the third protective layer 2.0 of 2.0 micrometer thickness was formed by coating a photosensitive polyimide and subsequently by photolithographic molding. The heater board prepared above was used for the production of an ink jet recording head shown in Figure 11. On heater board 111, the nozzle walls were formed of a negative dry film by photolithography. A glass ceiling plate 112 having an ink supply opening 113 for covering the nozzle walls was attached thereto. Finally, the resulting combination consisting of the heater board, the nozzle walls and the plate The ceiling was cut in a configuration indicated simultaneously to form the discharge openings 110. In this manner the ink jet recording head of the present invention was produced.

Example 19 An ink jet recording head was produced in the same manner as in Example 18 with the exception that AI2O3 was used instead of S3N4.

Examples 20 to 26 An ink jet recording head having the constitution shown in Figures 5A and 5B was prepared. On the silicon substrate as the substrate 101, a SiO 2 layer of 2.0 micrometer thickness was formed as the lower heat accumulating layer 102 by thermal oxidation. A layer of Ta-Ir of a thickness of 0.1 micrometer was formed on the same as layer 103 of resistance by sputtering. This layer had a sheet resistance of 15 ohms / | _ |. In addition thereto, a Ti layer with a thickness of 0.005 micrometer and an Al layer of 0.6 micrometer thickness was formed as layer 104 of the electrical connection electrode by vapor deposition. Then, a circuit pattern was formed for the heat generating portion 108 and the layer 104 of the electrical connection electrode by photolithography and chemical etching as shown in Figures 5A and 5B. The dimensions of C, D and E in Figure 5B were 100 micrometers, 120 micrometers and 140 micrometers, respectively, and the dimensions A and B are as follows. shows in Table 5. A photosensitive polyimide layer with a thickness of 2.0 micrometer was formed on it as the protective layer 505 by application. Then a portion of the protective layer 505 was removed by modeling photolithographic to provide an unprotected 509 region. The unprotected region had a J dimension of 40 micrometers and a K dimension of 130 micrometers. The boundaries of the protected region through the protective layer 505 and the unprotected region near the edges between the heat generating portion 108 and the electrical connection electrode layer 104 were placed in the broad pattern width zone (width B) of the heat generating portion. The heater board prepared in what The above was used for the production of an ink jet recording head shown in Figure 11. On the board 111, heater, the walls of the nozzle were formed of a negative dry film by photolithography. A glass ceiling plate 112 having an ink supply opening 113 for covering the walls of the nozzle was attached thereto. Finally, the resulting combination consisting of the heater board, the nozzle walls and the ceiling plate was cut in a designated manner 10 simultaneously to form the discharge openings 110. In this manner the ink jet recording head of the present invention was produced.

Comparison Example 1 An ink jet recording head having a constitution shown in Figures 9A and 9B is # produced in the same manner as in Examples 1 to 7 with the exception that the heat generating portion was prepared in a configuration as shown in Figures 9A and 9B with dimension A of 20 microns.

Comparison Example 2 An ink jet recording head having a constitution shown in Figures 10A and 10B was produced in the same manner as in Examples 20 to 26 with the exception that the heat generating portion occurred in a configuration as shown in Figures 10A and 10B with dimension A of 20 micrometers.

Thermal Durability Effort Evaluation (CST method) The heater boards were evaluated from compliance with the CST method by measuring the time that passed before the disintegration (disconnection). The more time has passed before the disintegration, the greater the thermal durability effort. The ink jet heads were driven under the operating conditions that will be given below and the number of pulses applied before the decay (decay pulse number) was measured as the index of the time that passed before the decay; drive voltage: 1.2 times the voltage of 20 the bubble formation, motor drive width: 3.0 microseconds, drive frequency: 3.0 kHz. The results of the evaluation are represented by a relative value of the number of decay pulses to that of the head of the Reference Example which is taken as 1, as shown in Tables 1 to 5.

Evaluation by Discharge Durability Test The ink jet recording heads were filled with an ink, and the practical ink discharge test was carried out. The time that passed before the disintegration was measured. The driving conditions were as follows: drive frequency: 3 kHz, width of driving impulse: 3 microseconds, driving voltage: 1.2 times the bubble formation voltage, ink composition: 77 weight percent water, 12 weight percent diethylene glycol, 7 weight percent urea, 4 weight 100 percent by weight of a dye (Black 2 for Food C.l.). The results are shown in Table 6. The time that passed before the disintegration is represented by a value relative to that of the head of Reference Example 2 which is taken as 1. 20 Table 1 Dimension Dimension A number of A B Impulses of (um) (um) De; Bintegration (Relative Value) Example 10 1 20 30 6000 2 20 55 700 3 30 50 4000 4 20 50 5000 5 20 40 5000 6 20 22 500 7 20 25 2000 Comparison Example. 20 1 20 20 1 Table 2 Dimension Dimension Number of F G Impulses of (um) (um) Disintegration (Relative Value) Example 8 0.1 0.2 5000 9 0.05 0.07 9000 35 10 0.1 0.25 300 11 0.1 0.15 7000 12 0.1 0.11 400 13 0.1 0.12 4000 40 Example of comparison 1 0.1 0.1 1 * Table 3 Dimension Dimension Number of H I Impulses of (um) (um) Disintegration (Relative Value) Example 14 2.0 0.7 6000 15 2.0 0.2 500 16 1.0 0.5 4000 17 2.0 1.8 700 Comparison Example 20 1 2.0 2.0 Table 4 Material Number of Disintegration Impulses (Relative Value) Example 18 YES3N4 5000 19 A1203 3000 40 Comparison Example Si0 < 45 Example 5 Dimension Dimension Number of A B Impulses of (um) (um) Disintegration (Relative Value) Example 20 20 30 8000 21 20 55 900 22 30 50 5000 26 20 25 3000 Comparison Example 2 20 20 1 Table 6 Time Before Disintegration (Relative Value) Example 1 8000 8 6000 14 5000 40 18 5000 20 5000 Comparison Example 45 1 2 2 1

Claims (8)

1. An ink jet recording head comprising an ink flow path having a discharge opening for discharging an ink; a lower layer for heat accumulation, a resistance layer that is provided in the lower layer, a pair of electrical connection electrodes that is provided in the resistance layer to apply an electrical signal to the resistance layer, and an electrothermal transducer , which is provided corresponding to the ink flow path, using the resistance layer between the electrical connection electrodes as a heat generating portion, wherein the heat generating portion has a high temperature section and a low temperature section when it is driven, and a limit of which varies the thickness of the protective layer is placed in the low temperature section.

The ink jet recording head according to claim 1, wherein the high temperature section and the low temperature section are provided by making the width of the resistance layer forming the heat generating portion non-uniform.

3. The ink jet recording head according to claim 1, wherein the high temperature section and the low temperature section are provided by making the thickness of the resistance layer forming the heat generating portion non-uniform.

The ink jet recording head according to claim 1, wherein the high temperature section and the low temperature section are provided by making the thickness of the lower layer corresponding to the heat generating portion non-uniform.

An ink jet recording head according to claim 1, wherein the high temperature section and the low temperature section are provided by making the thermal conductivity of the lower layer corresponding to the generating portion of the lower layer non-uniform. hot.

6. The ink-jet recording head according to any of claims 1 to 5, wherein the limit at which the thickness of the protective layer varies is the boundary between the thin region and the thick region of the protective layer. .

7. The ink jet recording head according to any of claims 1 to 5, wherein the limit at which the thickness of the protective layer varies is the boundary between the region having the protective layer and the region. that does not have the protective layer.

8. An ink jet recording apparatus having the ink jet recording head of any of claims 1 to 5, and a means for supplying a recording medium. F