JP6344916B2 - Liquid discharge head - Google Patents

Description

  The present invention relates to a liquid discharge head that discharges liquid such as ink.

  As one of recording apparatuses for recording an image on a recording medium by discharging a liquid, for example, ink, there is a thermal ink jet recording apparatus equipped with a liquid discharge head. In a thermal type ink jet recording apparatus, a pulse voltage is applied to a heating resistor that is an energy generating element, and ink in an ink chamber adjacent to the heating resistor is instantaneously boiled to cause an expansion of bubbles, thereby causing a discharge from an ejection port. Ink is ejected and recorded on a recording medium. Accordingly, the driving energy required for ejecting a certain amount of ink varies depending on the temperature of the ink and the temperature of the liquid ejection head.

  When the operating environment temperature is low and the ink viscosity is higher than that at room temperature (20 ° C. to 25 ° C.) or when the ink viscosity is high at room temperature, in the liquid ejection head, separately from the energy generating elements for liquid ejection on the substrate The heater which is a heating element provided on the substrate is driven. It is known that the ink is indirectly heated by heating the substrate with a heater.

  However, heating the substrate raises not only the ink but also the temperature of the substrate itself and the entire liquid discharge head, so that, for example, an overheat protection circuit that prevents the liquid discharge head from becoming high temperature is easily activated. .

  In addition, since the heated substrate radiates more heat from the end portion side of the substrate, a temperature difference is generated between the end portion and the central portion of the substrate. For this reason, the ink is not heated uniformly, the ink viscosity varies, and the ejection characteristics such as the ink ejection speed and the ink ejection amount differ depending on the position of the ejection port on the substrate. As a result, the color density and color tone of the image recorded on the recording medium change, and image quality such as streaks and unevenness may be deteriorated.

  In order to solve such a problem, Patent Document 1 aims to make the temperature in the substrate uniform so as to surround the end portion of the substrate in addition to the heating element for heating the liquid. By arranging the heating element, the temperature of the substrate is made uniform.

JP 2009-833 A

  In the liquid discharge head disclosed in Patent Document 1, when the ink is used at a low ambient temperature and the viscosity of the ink is higher than that at room temperature or when high viscosity ink is used at room temperature, the substrate on which the ink flow path is formed is heated. Thus, the ink is heated, and the recording operation is performed after the desired ink viscosity is reached.

  However, in the case of the liquid discharge head disclosed in Patent Document 1, the ink is not heated by the heating element, but the substrate is heated and the ink is indirectly heated through the heated substrate. Therefore, the energy efficiency of the heating element is not necessarily good. In addition, it takes time to increase the temperature of the ink, and the recording speed is reduced.

  In general, a heating element for increasing the temperature of the ink is formed on the same substrate as the substrate on which the energy generating element for generating heat for discharging ink is formed. Therefore, driving the energy generating element raises the temperature of the substrate, and in order to maintain the ink in a desired temperature range, it is necessary to perform complicated control on the heating element.

  The present invention has been made in view of the above problems, and provides a liquid discharge head capable of directly adjusting the temperature of a liquid with a heating element without complicated control of the heating element. .

The liquid discharge head of the present invention includes a flow path forming member in which a discharge port for discharging liquid is formed, a substrate on which a liquid supply port for supplying liquid to the discharge port is formed, and energy for generating energy for discharging the liquid. A generating element. An opening for a liquid supply port is formed on one surface of the substrate, and an energy generating element is arranged so as to sandwich the opening. The flow path forming member is disposed on one surface of the substrate. The flow path forming member and the substrate form a liquid flow path that connects the liquid supply port to the discharge port through the opening. A heating element for heating the liquid is disposed inside the liquid channel and at a position away from the substrate. The heating element is arranged inside the liquid channel so that the liquid flows between the heating element and the channel forming member in the thickness direction of the substrate.

  In the present invention, the heating element for heating the liquid is not a substrate on which the energy generating element for generating energy for ejection is disposed, but is located at a position away from the substrate in the liquid flow path. The liquid can be heated.

  According to the present invention, the temperature of the liquid can be directly adjusted by the heating element without performing complicated control on the heating element.

1 is a schematic perspective view of a first embodiment of a liquid ejection head according to the present invention. It is the schematic of the AA cross section of FIG. FIG. 6 is a top view of a recording element substrate for explaining the arrangement positions of heating elements. It is the schematic explaining an example of the manufacturing process of a recording element board | substrate. It is a flowchart of the manufacturing process shown in FIG. It is the schematic explaining another example of the manufacturing process of a recording element board | substrate. It is a flowchart of the manufacturing process shown in FIG. It is the schematic explaining the manufacturing process following the manufacturing process shown in FIGS. It is a flowchart of the manufacturing process shown in FIG. FIG. 2 is a schematic view of a cross section corresponding to the AA cross section of FIG. 1 according to a second embodiment of the liquid ejection head according to the present invention.

  Hereinafter, the liquid discharge head of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 shows a schematic perspective view of a first embodiment of a liquid discharge head according to the present invention. A part of the flow path forming member 3 is omitted so that the internal structure can be seen. FIG. 2 shows a schematic diagram of the AA cross section of FIG. FIG. 3 is a top view of the recording element substrate for explaining the arrangement positions of the heating elements. In FIG. 3, the flow path forming member, the intermediate layer, the first protective film, and the second protective film are omitted.

  The liquid discharge head 20 according to the present invention includes a recording element substrate 21 including a substrate 2 and a flow path forming member 3 disposed on the substrate 2 with an intermediate layer 5 for improving adhesion therebetween.

  The substrate 2 is provided with a liquid supply port 7 through which a liquid, for example, ink is supplied. The energy generating elements 1 are formed in rows at predetermined intervals on the surface (surface) 2a facing the flow path forming member 3 which is one surface of the substrate 2 with the liquid supply port 7 interposed therebetween. Yes. Further, contact pads 13 for electrical connection with the outside are formed on the end of the surface 2a in the longitudinal direction of the substrate 2.

  Corresponding to each energy generating element 1, a discharge port 6 is formed in the flow path forming member 3 above each energy generating element 1, and the liquid supply port 7 is formed by the substrate 2 and the flow path forming member 3. A liquid flow path 8 connected to the discharge port 6 through the opening 7a of the liquid supply port 7 is formed.

  The flow path forming member 3 is made of, for example, an epoxy resin. Moreover, what is necessary is just to provide the intermediate | middle layer 5 as needed. In the present embodiment, a plurality of energy generating elements 1 are arranged on each side of the liquid supply port 7, but a plurality of energy generating elements 1 may be arranged.

  A heating element 11 such as a heater for heating the liquid is provided between the opening 7 a of the liquid supply port 7 and the flow path forming member 3 in the liquid flow path 8. In the heating element 11, both end portions in the direction along the longitudinal direction of the liquid supply port 7 are connected to the contact pad 13 via the wiring 12 arranged on the substrate 2, and the heating pad 11 is connected to the contact pad 13 via the wiring 12. Electric power is supplied to the heating element 11 and the heating element 11 generates heat. In this configuration, since the heating element 11 is sufficiently in contact with the liquid, the thermal efficiency for heating the liquid is excellent.

  In addition, by covering the surface of the heating element 11 with a protective film, chemical damage to the heating element 11 due to the liquid used, specifically, dissolution, rust, and corrosion can be suppressed. By forming the protective film 9 before and after the step of forming the heating element 11 on the substrate 2, the heating element 11 can be sandwiched between the protective films 9. In the description of the present embodiment, a configuration in which the entire heating element 11 is covered with the protective film 9 will be described. However, a configuration in which only a part of the heating element 11 is covered with the protective film 9, a configuration in which the protective film 9 is not provided, and the like. Is also possible.

  Next, a method for manufacturing the recording element substrate 21 of the liquid discharge head 20 of the present invention will be described. FIG. 4 is a schematic diagram for explaining an example of the manufacturing process of the recording element substrate 21 and shows a case where the heating element 11 and the energy generating element 1 are formed in the same process. FIG. 5 shows a flowchart of the manufacturing process shown in FIG.

  First, the sacrificial layer 16 is formed on the surface 2 a of the substrate 2. The position of the sacrificial layer 16 is matched with the position where the liquid supply port 7 is formed. Then, a first protective film 9a is formed on the sacrificial layer 16 (S1) (see FIG. 4A).

  Next, a plurality of energy generating elements 1 are arranged on the surface 2a of the substrate 2 so as to sandwich the position where the liquid supply port 7 is formed, and the heating element 11 is arranged on the first protective film 9a (S2). (See FIG. 4 (b)).

  Next, a second protective film 9b is formed so as to cover the surface 2a of the substrate 2 (S3) (see FIG. 4C).

  Next, an unnecessary region of the second protective film 9b is removed (S4) (see FIG. 4D). Note that the step of removing unnecessary regions of the second protective film 9b can be omitted.

  As described above, the heating element 11 surrounded by the protective film 9 composed of the first protective film 9a and the second protective film 9b is formed. In this method, since the energy generating element 1 and the heating element 11 can be formed in the same process, it is not necessary to newly add a process for forming the heating element 11.

  FIG. 6 is a schematic diagram for explaining another example of the manufacturing process of the recording element substrate 21 and shows a case where the heating element 11 and the energy generating element 1 are formed in different processes. FIG. 7 shows a flowchart of the manufacturing process shown in FIG.

  A sacrificial layer 16 is formed on the surface 2a of the substrate 2 at a position where the liquid supply port 7 is formed, and a plurality of energy generating elements 1 are arranged in a row so as to sandwich the sacrificial layer 16 on the surface 2a. Then, a first protective film 9a is formed so as to cover the surface 2a of the substrate 2 (S11) (see FIG. 6A).

  Next, the heating element 11 is disposed on the first protective film 9a so as to face the sacrificial layer 16 (S12) (see FIG. 6B).

  Next, a second protective film 9b is formed on the first protective film 9 so as to cover the heating element 11 (S13) (see FIG. 6C).

  Next, an unnecessary region of the second protective film 9b is removed (S14) (see FIG. 6D). Note that the step of removing unnecessary regions of the second protective film 9b can be omitted.

  As described above, the heating element 11 surrounded by the protective film 9 composed of the first protective film 9a and the second protective film 9b is formed.

  In the above-described two manufacturing methods described with reference to FIGS. 4 to 7, the energy generating element 1 is formed on the substrate 2, and the heating element 11 is a first protective film 9 a that forms part of the protective film 9. Formed on top. That is, since the energy generating element 1 and the heating element 11 are formed in different layers, it is possible to avoid interference between a wiring (not shown) connected to the energy generating element 1 and a wiring 12 connected to the heating element 11. . Therefore, it is not necessary to separately add a space for arranging the wiring 12 for supplying power to the heating element 11 on the substrate 2, and it is not necessary to increase the size of the substrate 2.

  FIG. 8 is a schematic diagram for explaining a manufacturing process subsequent to the manufacturing process illustrated in FIGS. FIG. 9 shows a flowchart of the manufacturing process shown in FIG.

  A film to be the intermediate layer 5 is formed on the protective film 9 and becomes the mask 15 when the liquid supply port 7 is formed on the other surface (back surface) 2b of the substrate 2 opposite to the front surface 2a. A resist or the like is applied and cured by baking. And in order to pattern the film used as the intermediate | middle layer 5 on the protective film 9, a resist is apply | coated by spin coating etc. on this film | membrane, and exposure and image development are performed, and an excess resist is removed. Next, after patterning the film by dry etching or the like using the resist remaining on the film as a mask, the remaining resist on the film is peeled off to form the intermediate layer 5. In the same process, a mask 15 is formed on the back surface 2b of the substrate 2 (S21) (see FIG. 8A).

  Next, a positive resist (hereinafter referred to as “mold material”) 17 which is a mold material for forming a part of the liquid flow path 8 is formed on the protective film 9 at a position not covered with the intermediate layer 5. (S22) (see FIG. 8B).

  Next, a negative photosensitive resin film 23 to be the flow path forming member 3 is formed by spin coating or the like so as to cover the surface 2a of the substrate 2, and an ejection port is formed by exposure and development with ultraviolet rays, deep UV light, or the like. 6 is formed (S23) (see FIG. 8C).

  Next, the protective material 18 is formed by spin coating or the like so as to cover the surface 2a of the substrate 2 and the side surface 2c of the substrate 2. Then, the substrate 2 is chemically etched, for example, anisotropically etched with a strong alkaline solution such as 4-methyl ammonium hydroxide (TMAH). Since the portion covered with the protective material 18 and the portion covered with the mask 15 are not etched, the portion not covered with the mask 15 on the back surface 2b of the substrate 2 is etched. Then, the liquid supply port 7 is formed by etching the sacrificial layer 16 and a part of the protective film 9 on the sacrificial layer 16 (S24) (see FIG. 8D). The sacrificial layer 16 is preferably made of an easily etched material such as aluminum. Therefore, the opening 7 a of the liquid supply port 7 is formed in the same size as the sacrificial layer 16.

  Next, the mask 15 and the protective material 18 are removed. Further, the mold material 17 is eluted from the discharge port 6 and the liquid supply port 7, whereby the liquid channel 8 is formed and the channel forming member 3 is also completed (S25) (see FIG. 8E).

  In the liquid discharge head 20 of the present invention, the heating element 11 for heating the liquid is located between the opening 7 a of the liquid supply port 7 and the flow path forming member 3, that is, inside the liquid flow path 8, with the protective film 9 interposed therebetween. The liquid can be heated. In the liquid flow path 8, since the liquid which goes to each discharge port 6 necessarily flows, it can heat a liquid directly. Further, since the heating element 11 is in direct contact with the liquid through the protective film 9 or directly, the temperature of the liquid can be easily adjusted as compared with the case of heating the liquid through the substrate 2 and the liquid can be efficiently supplied. Easy to heat. Therefore, energy for heating the liquid can be reduced.

  Furthermore, since the heating element 11 is separated from the substrate 2 and does not heat the liquid via the substrate 2, the temperature rise of the substrate 2 can be suppressed. The energy generating element 1 is located on the surface 2a of the substrate 2, and the heating element 11 is located on the protective film 9 (first protective film 9a). That is, since the energy generating element 1 and the heating element 11 are located in different layers, it is possible to suppress interference between the wiring connected from the contact pad 13 to the energy generating element 1 and the wiring 12 connected from the contact pad 13 to the heating element 11. can do. Furthermore, since it is not necessary to provide an additional region for arranging the heating element 11 on the substrate 2 and the number of special manufacturing processes does not increase, the provision of the heating element 11 increases the size of the substrate 2 and increases the manufacturing cost. Can be suppressed.

  In the present invention, the heating element 11 may be disposed at a position away from the substrate 2 in the liquid flow path 8 from the liquid supply port 7 through the opening 7 a to the discharge port 6. It is also possible to arrange the heating element 11 at a position not in contact with the substrate 2.

  The liquid discharge head 20 of the present invention can be used in, for example, a recording apparatus including a transport mechanism that supports and transports a recording medium.

[Second Embodiment]
Next, a second embodiment of the liquid ejection head according to the present invention will be described. FIG. 10 is a schematic diagram of a cross section corresponding to the AA cross section of FIG. 1, which is a second embodiment of the liquid discharge head according to the present invention. Note that a description of the same configuration as that of the above-described embodiment is omitted.

  In the present embodiment, a protrusion 10 that protrudes toward the liquid flow path 8 is provided in a portion of the flow path forming member 3 that faces the liquid supply port 7, more specifically, a portion that faces the heating element 11. ing. The heating element 11 is fixed to the protrusion 10 via the protective film 9 (directly when there is no protective film 9). Since the heating element 11 is fixed to the protrusion 10, the thermal efficiency of the heating element 11 is not greatly reduced. The thermal conductivities of liquid, for example, water, which is the main component of ink, and epoxy resin, which is an example of the material constituting the flow path forming member 3, are 0.6 W / mK and 0.3 W / mK, respectively. That is, the thermal conductivity of the epoxy resin is as small as about 1/2 of water. Therefore, even if one surface of the heating element 11 is fixed to the protrusion 10 of the flow path forming member 3, the heat of the heating element 11 does not escape from the protrusion 10 and is easily transferred to the liquid.

  In the present embodiment, since the heating element 11 is fixed to the protrusion 10 of the flow path forming member 3, the reliability of the heating element 11 against the pressure caused by the liquid flow during the recording operation or the head refreshing operation. Will improve.

DESCRIPTION OF SYMBOLS 1 Energy generating element 2 Substrate 3 Flow path forming member 6 Discharge port 7 Liquid supply port 8 Liquid flow path 9 Protective film 11 Heating element 20 Liquid discharge head 21 Recording element substrate

Claims (9)

A flow path forming member in which a discharge port for discharging a liquid is formed; a substrate on which a liquid supply port for supplying the liquid to the discharge port is formed; and a plurality of energy generating elements for generating energy for discharging the liquid. A liquid ejection head comprising:
An opening of the liquid supply port is formed on one surface of the substrate, and each energy generating element is disposed so as to sandwich the opening,
The flow path forming member is disposed on the one surface of the substrate,
The flow path forming member and the substrate form a liquid flow path connected to the discharge port from the liquid supply port through the opening,
A heating element for heating the liquid is disposed inside the liquid flow path and at a position away from the substrate ,
The liquid ejection head, wherein the heating element is disposed inside the liquid flow path so that the liquid flows between the heating element and the flow path forming member in the thickness direction of the substrate . 2. The liquid ejection head according to claim 1, wherein the heating element has an end portion in a longitudinal direction disposed inside a periphery of the opening. Having a protrusion protruding from the flow path forming member toward the liquid flow path;
It said heating element is secured to the protrusion, the liquid discharge head according to claim 1 or 2. 4. The liquid discharge head according to claim 1, wherein the heating element is located between the opening and the discharge port. 5. At least a portion is covered with the protective film, the liquid discharge head according to any one of claims 1 4 of the heating element. The heating element is a heater, a liquid discharge head according to any one of claims 1 to 5. The liquid discharge head according to any one of claims 1 to 6 ,
A transport mechanism for transporting the recording medium;
A recording apparatus. A flow path forming member having a discharge port for discharging a liquid, a substrate having a liquid supply port for supplying the liquid to the discharge port, and an energy generating element for generating energy for discharging the liquid. A method for manufacturing a liquid ejection head having:
A first protective film is formed on one surface of the substrate, and a heating element is disposed on the first protective film so as to face a position where the liquid supply port is formed. Arranging energy generating elements in a row so as to sandwich a position where the liquid supply port is formed in a region where the first protective film on the one surface is not formed;
Forming a second protective film so as to cover the one surface of the substrate;
Forming a mold and a film to be the flow path forming member in this order on the second protective film;
Forming the discharge port at a position of the film facing the energy generating element;
Removing the mold material after forming the liquid supply port in the substrate;
A method for manufacturing a liquid discharge head, comprising: A flow path forming member having a discharge port for discharging a liquid, a substrate having a liquid supply port for supplying the liquid to the discharge port, and an energy generating element for generating energy for discharging the liquid. A method for manufacturing a liquid ejection head having:
A first protective film is disposed on one surface of the substrate so as to cover the one surface of the substrate after the energy generating elements are arranged in a row so as to sandwich the position where the liquid supply port is formed. Forming, and
Disposing a heating element on the first protective film at a position facing the position where the liquid supply port is formed;
Forming a second protective film so as to cover the one surface of the substrate;
Forming a mold and a film to be the flow path forming member in this order on the second protective film;
Forming the discharge port at a position of the film facing the energy generating element;
Removing the mold material after forming the liquid supply port in the substrate;
A method for manufacturing a liquid discharge head, comprising: