KR102066324B1 - Liquid discharge apparatus and liquid discharge head - Google Patents

Abstract

The liquid ejecting apparatus includes a plurality of ejection openings configured to eject the liquid, and a plurality of pressure chambers having a recording element configured therein configured to generate energy used to eject the liquid, each of which communicates with the plurality of ejection openings through the ejection channel. A liquid discharge head having a recording element substrate comprising a pressure chamber, a liquid supply channel configured to supply liquid to the plurality of pressure chambers, and a liquid recovery channel configured to recover liquid from the plurality of pressure chambers; A tank configured to store the liquid. The plurality of pressure chambers are in communication with the liquid supply channel and the liquid recovery channel, so that the liquid flows through the plurality of pressure chambers, and the relative dielectric constant ε _r of the liquid stored in the tank satisfies the relationship of ε _r ≤ 65. .

Description

LIQUID DISCHARGE APPARATUS AND LIQUID DISCHARGE HEAD}

The present disclosure relates to a liquid discharge device and a liquid discharge head.

In the liquid discharge head for discharging liquid such as ink from the discharge port, the volatile components in the liquid discharged from the discharge port evaporate, the liquid thickens near the discharge port, causing a change in the discharge speed of the discharged droplets, and the drop landing accuracy is affected. There is a problem receiving.

As a measure to counteract the liquid thickening phenomenon, there is a known method of circulating the ink supplied to the liquid discharge head along the circulation path. Japanese Laid-Open Patent Publication No. 2002-355973 discloses a liquid discharge head which suppresses clogging of a discharge port due to evaporation of liquid from the discharge port by circulating the liquid in a channel formed between the member where the discharge port is formed and the substrate on which the heating resistance element is formed. It is starting.

When the rest period after the ejection operation is long, the increased viscosity of the liquid near the ejection opening becomes prominent, and solid components in the liquid may solidify near the ejection opening. Therefore, the solid component increases the fluid resistance when the liquid passes through the discharge port at the first liquid discharge after rest, which can lead to defect discharge. However, no consideration regarding such defect discharge is given to the liquid discharge head disclosed in Japanese Patent Laid-Open No. 2002-355973. Therefore, defect discharge that occurs during the first liquid ejection after rest can cause deterioration of image quality.

It has been found to be desirable to provide a liquid discharge head and a liquid discharge device capable of forming high resolution and high quality images.

The liquid ejecting apparatus includes a plurality of ejection openings configured to eject the liquid, and a plurality of pressure chambers having a recording element configured therein for generating energy used to eject the liquid, each of which communicates with the plurality of ejection openings through the ejection channel. A liquid discharge head having a recording element substrate including a pressure chamber, a liquid supply channel configured to supply liquid to the plurality of pressure chambers, and a liquid recovery channel configured to recover liquid from the plurality of pressure chambers; And a tank configured to recover the liquid supplied to the liquid discharge head. The plurality of pressure chambers are in communication with the liquid supply channel and the liquid recovery channel 19, so that the liquid flows through the plurality of pressure chambers. The relative dielectric constant ε _r of the liquid stored in the tank satisfies the relationship ε _r ≦ 65.

The liquid discharge head includes a discharge port configured to discharge liquid; A recording element configured to generate energy used to discharge the liquid; A pressure chamber having a recording element therein; A liquid supply channel configured to supply a liquid to the pressure chamber; And a liquid recovery channel configured to recover the liquid from the pressure chamber. The liquid dielectric constant (ε _r) is satisfied a relationship of ε _r ≤ 65 is circulated through a liquid supply channel, a pressure chamber and the liquid collection channels.

According to the liquid ejecting apparatus and the liquid ejecting head described above, the relative dielectric constant of the liquid can be lowered, whereby stagnation of solids near the periphery of the ejection opening can be suppressed even after the ejection operation is stopped for a certain amount of time. Therefore, even in the case of a liquid having a large amount of solid content, defect discharge can be suppressed at the time of initial liquid discharge after rest, whereby deterioration of image quality is suppressed.

Other features of the present invention will be apparent from the following description of exemplary embodiments with reference to the accompanying drawings.

1 is a perspective view illustrating an inkjet recording apparatus according to a first application example.
2 is a schematic diagram illustrating a first circulation path of the first application example.
3 is a schematic diagram illustrating a second circulation path of the first application example.
4A and 4B are perspective views of the liquid discharge head according to the first application example.
5 is an exploded perspective view of the liquid discharge head according to the first application example.
6A to 6F are plan views illustrating first to third channel members according to the first application example.
7 is an enlarged perspective view of a part of the channel member of the first application example.
8 is a cross-sectional view taken along the line VIII-VIII of FIG. 7.
9A and 9B are views illustrating a discharge module according to a first application example, in which Fig. 9A is a perspective view and Fig. 9B is an exploded view.
10A and 10C are plan views of the recording element substrate according to the first application example.
11 is a perspective view illustrating the cross-section XI-XI of FIG. 10A.
12 is a plan view illustrating a partially enlarged exemplary view of an adjacent portion of the recording element substrate according to the first application example.
13A and 13B are perspective views of the liquid discharge head according to the second application example.
14 is an exploded perspective view of the liquid discharge head according to the second application example.
15A to 15E are plan views of the first and second channel members constituting the channel member according to the second application example.
16 is an enlarged perspective view of a part of the channel member of the second application example.
FIG. 17 is a cross-sectional view taken along the line XVII-XVII of FIG. 16.
18A and 18B are views illustrating a discharge module according to a second application example, in which Fig. 18A is a perspective view and Fig. 18B is an exploded view.
19A and 19C are plan views of the recording element substrate according to the second application example.
20 is a perspective view illustrating the inkjet recording apparatus according to the second application example.
21A to 21C are diagrams illustrating a main part of the liquid discharge head according to the first embodiment, in which FIG. 21A is a plan view, FIG. 21B is a sectional view, and FIG. 21C is a perspective view.
22 is an enlarged sectional view of the vicinity of the discharge port of the liquid discharge head.
23 is a graph illustrating the relationship between head dimensions and flow modes.
24 is a graph illustrating the identified results of the relationship between flow mode and head dimensions.
25A to 25D are diagrams illustrating the circulating flow in the discharge port.
26A to 26C are diagrams illustrating the concentration of ink in the ejection openings.
27A to 27D are diagrams illustrating the concentration distribution of the solvent and the concentration distribution of the pigment in the discharge port.
Fig. 28 is a graph showing the discharge rate versus the number of droplets discharged after rest.
29A to 29C are graphs showing the discharge speed with respect to the number of droplets discharged after rest.
30 is a cross-sectional view of the liquid discharge head according to the second embodiment.
31A and 31B are plan views of the liquid discharge head according to the third embodiment.
32 is a perspective view of the ink jet recording apparatus according to the first application example.
33 is a diagram illustrating a third circulation path.
34A and 34B are diagrams illustrating a liquid discharge head according to the first application example.
35 is an exploded perspective view of the liquid discharge head according to the first application example.
36 is a schematic view of the channel member of the liquid discharge head according to the first application example.
37 is a diagram illustrating a recording apparatus according to the third application example.
38 is a diagram illustrating a fourth circulation path.
39A and 39B are views illustrating a liquid discharge head according to the third application example.
40A to 40C are diagrams illustrating a liquid discharge head according to the third application example.

Application Examples and Embodiments will be described with reference to the accompanying drawings. First to third application examples will be described first, and then embodiments will be described. However, it should be understood that the following description does not limit the scope of the present invention. As an example, a thermal system in which bubbles are generated by a heating element and liquid is ejected is suggested in this application, but the present disclosure may likewise be applied to a liquid discharge head or various other types of liquid discharge systems employing piezoelectric systems. have.

Although the application relates to an inkjet recording apparatus (or simply " recording apparatus ") in which a liquid such as ink circulates between the tank and the liquid ejecting head, other forms can be used as well. For example, instead of ink circulation, two tanks, one on the upstream side and the other on the downstream side, are provided, and the ink in the pressure chamber flows by running the ink from one tank to the other tank. Can be used. Further, although the application example relates to a so-called line head having a length corresponding to the width of the recording medium, the embodiment may also be a so-called serial liquid discharge head for recording while scanning on the recording medium. An example of a serial liquid discharge head is, but is not limited to, having one substrate for each of black ink recording and color ink recording. Short line heads, which are shorter than the width of the recording medium, are formed, and a plurality of recording element substrates are arranged such that the ejection openings overlap in the ejection opening row direction, and an arrangement in which they are scanned on the recording medium can be formed.

Application Example 1

Description of Inkjet Recording Device

Fig. 1 illustrates a schematic configuration of an apparatus for ejecting liquid, in particular, an inkjet recording apparatus 1000 (hereinafter simply referred to as a "recording apparatus") for ejecting ink to perform recording. The recording apparatus 1000 is a line recording apparatus, which is a line-type (page-wide) liquid discharge head disposed generally orthogonal to the conveying direction of the conveying unit 1 and the recording medium 2 which conveys the recording medium 2. (3), single-pass continuous recording is performed while conveying a plurality of recording media 2 continuously or intermittently. The recording medium 2 is not limited to the cut sheet, but may be a continuous roll sheet. The liquid discharge head 3 is capable of full color printing by cyan, magenta, yellow and black (abbreviated "CMYK") inks. The liquid discharge head 3 has a liquid supply unit serving as a supply path for supplying liquid to the liquid discharge head 3, a main tank and a buffer tank (see FIG. 2) connected by fluid connection. The liquid discharge head 3 is also electrically connected to the electric control unit, which transmits power and discharge control signals to the liquid discharge head 3. The liquid path and the electric signal path in the liquid discharge head 3 will be described later.

Description of the first circular path.

2 is a schematic diagram illustrating a first circulation path which is a first form of the circulation path applied to the recording apparatus of this application example. 2 is a diagram illustrating a first circulation pump (high pressure side) 1001, a first circulation pump (low pressure side) 1002, a buffer tank 1003, and the like, which are connected by fluid connection as a flow unit. Although FIG. 2 illustrates only the path through which one color ink of the CMYK ink flows flows for the sake of brevity, in practice, there are four color circulation paths provided to the recording apparatus main unit and the liquid discharge head 3. . The buffer tank 1003 serving as a sub tank connected to the main tank 1006 has an atmospheric communication opening (not shown), whereby the inside and the outside of the tank communicate with each other, and bubbles in the ink can be discharged to the outside. Can be. Buffer tank 1003 is also connected to make-up pump 1005. When ink is consumed in the liquid ejecting head 3 by ejecting (ejecting) ink from the ejection opening of the liquid ejecting head by ejecting the ink to perform recording, suction recovery, and the like, the replenishment pump 1005 is connected to the main tank 1006. Serves to send the same amount of ink to the buffer tank 1003 as consumed from.

The first circulation pumps 1001 and 1002 serve to extract liquid from the liquid connector 111 of the liquid discharge head 3 and to flow the liquid into the buffer tank 1003. It is preferable that the first circulation pumps 1001 and 1002 functioning as flow units for flowing liquid through the liquid discharge head 3 are volumetric pumps having a quantitative fluid transfer function. Specific examples may include tube pumps, gear pumps, diaphragm pumps, syringe pumps, and the like. An arrangement may be used in which constant flow is guaranteed by placing a common constant flow valve and a relief valve at the outlet of the pump. When the liquid discharge unit 300 is driven, the first circulation pump (high pressure side) 1001 and the first circulation pump (low pressure side) 1002 have a constant amount of ink in the common supply channel 211 and the common recovery channel. Flow through 212. The amount of flow is preferably set at a level or higher where the temperature difference between the recording element substrates 10 of the liquid discharge head 3 does not affect the recording image quality. On the other hand, when the flow rate is set excessively high, the influence of the pressure drop of the channel in the liquid discharge unit 300 causes an excessively large difference in the negative pressure between the recording element substrates 10, resulting in an unevenness of the image density. do. Therefore, the flow rate is preferably set in consideration of the temperature difference and the negative pressure difference between the recording element substrates 10.

The negative pressure control unit 230 is provided between the liquid discharge unit 300 and the path of the second circulation pump 1004. The negative pressure control unit 230 is a pressure downstream from the negative pressure control unit 230 (that is, on the liquid discharge unit 300 side) at a predetermined constant pressure even when the flow rate of the circulation system fluctuates due to the difference in duty at the time of recording. It functions to be maintained. Any mechanism may be used as the two pressure regulating mechanisms constituting the negative pressure control unit 230 if the pressure downstream from itself can be controlled to fluctuate within a certain range or less centered on the desired set pressure. As an example, a mechanism corresponding to a so-called "decompression regulator" can be used. In the case of using the pressure regulator, the upstream side of the negative pressure control unit 230 is preferably pressurized by the second circulation pump 1004 through the liquid supply unit 220 as illustrated in FIG. 2. This allows the influence of the head pressure on the liquid discharge head 3 of the buffer tank 1003 with respect to the liquid discharge head 3 to be suppressed so that a greater degree of freedom in the layout of the buffer tank 1003 of the recording apparatus 1000 is obtained. To provide. It is sufficient that the second circulation pump 1004 has a specific lift pressure or more within the range of the circulating flow pressure of the ink used when driving the liquid discharge head 3, and a turbo pump, a volumetric pump, or the like can be used. Specifically, a diaphragm pump or the like can be used. Alternatively, by way of example, a head tank arranged at a particular head head relative to the negative pressure control unit 230 may be used instead of the second circulation pump 1004.

As illustrated in FIG. 2, the negative pressure control unit 230 has two pressure regulating mechanisms, which are set to different control pressures from each other. Of the two negative pressure regulating mechanisms, the relative high pressure setting side (indicated by H in FIG. 2) and the relative low pressure setting side (indicated by L in FIG. 2) are respectively common through the liquid supply unit 220 and in the liquid discharge unit 300. It is connected to the supply channel 211 and the common recovery channel 212. The liquid discharge unit 300 is provided with an individual supply channel 213 and an individual recovery channel 214 communicating between the common supply channel 211, the common recovery channel 212, and the recording element substrate 10. Due to the individual supply channel 213 in communication with the common supply channel 211 and the common recovery channel 212, flow occurs and a portion of the liquid is internal from the common supply channel 211 in the recording element substrate 10. It flows through the channel and into the common recovery channel 212 (indicated by the arrow in FIG. 2). The reason is that the pressure regulating mechanism H is connected to the common supply channel 211 and the pressure regulating mechanism L is connected to the common recovery channel 212 so that a pressure difference occurs between the two common channels.

Thus, flow occurs in the liquid discharge unit 300, and a portion of the liquid passes through the recording element substrate 10 while the liquid flows through each of the common supply channel 211 and the common recovery channel 212. Therefore, heat generated in the recording element substrate 10 can be discharged from the recording element substrate 10 to the outside by flow through the common supply channel 211 and the common recovery channel 212. This configuration also allows ink flow to occur in the discharge chamber and the pressure chamber not used for recording while the recording is performed by the liquid ejecting head 3, so that the thickening of the ink in this portion can be suppressed. have. In addition, the thickened ink and foreign matter in the ink may be discharged to the common recovery channel 212. The liquid discharge head 3 according to the present application can record at high speed with high image quality.

Description of the Second Cyclic Path.

3 illustrates a second circulation path which is a different circulation path from the above-described first circulation path for the circulation path applied to the recording apparatus according to the present application. The main difference with respect to the above-mentioned first circulation path is that both pressure regulating mechanisms constituting the negative pressure control unit 230 have a constant range centering on the set pressure desired upstream from the negative pressure control unit 230. It is to have a mechanism for controlling to shake within. This mechanism is a mechanism part having an operation corresponding to a so-called "back pressure regulator". Another difference is that the second circulation pump 1004 acts as a negative pressure source for depressurizing the downstream side from the negative pressure control unit 230. Another difference is that the first circulation pump (high pressure side) 1001 and the first circulation pump (low pressure side) 1002 are disposed upstream of the liquid discharge head 3, and the negative pressure control unit 230 is the liquid discharge head. It is arrange | positioned downstream of (3).

The negative pressure control unit 230 of the second circulation path acts as follows. That is, the negative pressure control unit 230 controls the pressure fluctuation of its own upstream side (i.e., the liquid discharge unit 300 side) even when the flow rate fluctuates due to the difference in duty during recording by the liquid discharge head 3. It operates to keep within a certain range centered on the previously set pressure. The downstream side of the negative pressure control unit 230 is preferably pressurized by the second circulation pump 1004 via the liquid supply unit 220 as illustrated in FIG. 3. This allows the influence of the head of the buffer tank 1003 on the liquid discharge head 3 to be suppressed, thereby providing a wider selection range for the layout of the buffer tank 1003 in the recording apparatus 1000. Alternatively, by way of example, a head tank arranged at a particular head head relative to the negative pressure control unit 230 may be used instead of the second circulation pump 1004.

The negative pressure control unit 230 has two pressure regulating mechanisms, which are set to different control pressures from each other as illustrated in FIG. 3 in the same manner as in the first application. Of the two negative pressure regulating mechanisms, the relative high pressure setting side (indicated by H in FIG. 3) and the relative low pressure setting side (indicated by L in FIG. 3) are respectively common in the liquid discharge unit 300 via the liquid supply unit 220. It is connected to the supply channel 211 and the common recovery channel 212. The pressure in the common feed channel 211 is made relatively higher than the pressure in the common return channel 212 by the two negative pressure regulating mechanisms. Thus, flow occurs and ink flows from the common supply channel 211 to the common recovery channel 212 through the individual channels 213 and 214 and the inner channel of the recording element substrate 10 (in the arrow in FIG. 3). Displayed). Thus, the second circulation path yields the same ink flow state as that of the first circulation path in the liquid discharge unit 300, but has two advantages different from that of the first circulation path.

One advantage is that in the second circulation path, the negative pressure control unit 230 is disposed downstream of the liquid discharge head 3, so that the dust and foreign substances generated in the negative pressure control unit 230 enter the head. There is almost no. The second advantage is that the maximum value of the required flow rate supplied from the buffer tank 1003 to the liquid discharge head 3 can be smaller in the second circulation path than in the case of the first circulation path. The reason for this is as follows. The total flow rate in the common supply channel 211 and the common recovery channel 212 during circulation during the recording standby is denoted by A. The value of A is defined as the minimum flow rate required to keep the temperature difference of the liquid discharge unit 300 within the desired range when the temperature adjustment of the liquid discharge head 3 is performed during the recording standby. In addition, the discharge flow rate in the case where ink is discharged from all the discharge ports of the liquid discharge unit 300 (total discharge) is defined as F. Therefore, in the case of the first circulation path (FIG. 2), the set flow rates of the first circulation pump (high pressure side) 1001 and the first circulation pump (low pressure side) 1002 are A, and therefore, the liquid required for the entire discharge. The maximum value of the liquid supply amount to the discharge head 3 is A + F.

On the other hand, in the case of the second circulation path (FIG. 3), the liquid supply amount to the liquid discharge head 3 required for recording standby is the flow rate A. FIG. This means that the supply amount to the liquid discharge head 3 necessary for the entire discharge is the flow rate F. FIG. Therefore, in the case of the second circulation path, the total value of the set flow rates of the first circulation pump (high pressure side) 1001 and the first circulation pump (low pressure side 1002, that is, the maximum value of the required supply amount is A and F. Therefore, if the liquid discharge unit 300 having the same configuration is used, the maximum value A or F of the required supply amount of the second circulation path is the maximum value A + F of the required supply amount of the first circulation path. As a result, the degree of freedom in respect of the applicable circulation pump is higher in the case of the second circulation path, so that a low cost circulation pump having a simple structure can be used, for example, arranged in the main unit side path. The load on the cooler (not shown) can be reduced, thus the cost of the recording apparatus main unit can be reduced This advantage is more pronounced in the line head, where the value of A or F is relatively high, The longer the length is in the longitudinal direction Innovation is useful.

However, there is an advantage that the first circulation path is more advantageous than the second circulation path. That is, in the second circulation path, the flow rate flowing through the liquid discharge unit 300 during the recording standby is the maximum value, so that the lower the recording duty of the image, the greater the negative pressure is applied to the nozzle. Thus, the channel width (length in the direction orthogonal to the liquid flow direction) of the common supply channel 211 and the common recovery channel 212 is reduced to reduce the head width (the length of the liquid discharge head in the transverse direction). In this case, this may lead to more influence of satellite droplets. The reason is that a high negative pressure is applied to the nozzle in a low-duty image where the inequality is well seen. On the other hand, in the case of the first circulation path, high negative pressure is applied to the nozzle when forming the high duty image, so that any satellite generated is less visible, which is advantageous in that the influence on the image quality is small. Which of these two circulation paths is more preferable can be selected in view of the specifications of the liquid discharge head and the recording apparatus main unit (discharge flow rate F, minimum circulation flow rate A, and channel resistance in the head).

Description of the Third Circular Path

33 is a schematic diagram illustrating a third circulation path which is the first form of the circulation path applied to the recording apparatus. Description of the same functions and configurations as those of the first and second circulation paths described above will be omitted, and differences will be mainly described.

The liquid is supplied into the liquid discharge head 3 at two locations in the middle of the liquid discharge head 3 and at a total of three locations on one end side of the liquid discharge head 3. The liquid passes from the common supply channel 211 through the pressure chamber 23 and is then recovered by the common recovery channel 212, which is then external from the recovery opening at the other end of the liquid discharge head 3. Is recovered. The individual channels 213 and 214 communicate with the common supply channel 211 and the common recovery channel 212, and the pressure chamber 23 disposed in the recording element substrate 10 and the recording element substrate 10 is an individual supply channel. On the path of (213, 214). Thus, flow occurs and a portion of the ink pumped by the first circulation pump 1002 flows from the common supply channel 211 through the pressure chamber 23 in the recording element substrate 10 to the common recovery channel 212. (Indicated by arrows in FIG. 33). The reason for this is that a pressure difference is formed between the pressure regulating mechanism H connected to the common supply channel 211 and the pressure regulating mechanism L connected to the common recovery channel 212, and the first circulation pump 1002 merely uses a common recovery. Is connected only to channel 212.

Accordingly, the flow of liquid passing through the common recovery channel 212 and the flow flowing from the common supply channel 211 to the common recovery channel 212 through the pressure chamber 23 of the recording element substrate 10 are the liquid discharge units. It is formed in 300. Therefore, heat generated in the recording element substrate 10 can be discharged from the recording element substrate 10 to the outside by the flow from the common supply channel 211 to the common recovery channel 212 while suppressing an increase in pressure loss. . Further, according to the present circulation path, the number of pumps functioning as the liquid conveying unit can be reduced in comparison with the above-described first and second circulation paths.

Description of the configuration of the liquid discharge head

The configuration of the liquid discharge head 3 according to the first application example will be described. 4A and 4B are perspective views of the liquid discharge head 3 according to the present application. The liquid discharge head 3 is a line type liquid discharge head, and the 15 recording element substrates 10 each of which the recording element substrates 10 can discharge ink of four colors of C, M, Y, and K are straight. (Inline layout). As shown in FIG. 4A, the liquid discharge head 3 is an input terminal 91 electrically connected via a recording element substrate 10, a flexible printed circuit board 40, and an electrical wiring board 90. And a power supply terminal 92. The input terminal 91 and the power supply terminal 92 are electrically connected to the control unit of the recording apparatus 1000, and supply the discharge drive signal and the electric power necessary for discharge to the recording element substrate 10, respectively. Integrating the wiring into the electrical wiring board 90 by the electrical circuit allows the number of input terminals 91 and power supply terminals 92 to be reduced compared to the number of recording element substrates 10. This allows the number of electrical connection portions to be removed at the time of exchange of the liquid discharge head 3 or assembly of the liquid discharge head 3 to the recording apparatus 1000 can be reduced. The liquid connecting portions 111 provided at both ends of the liquid discharge head 3 are connected with the liquid supply system of the recording apparatus 1000, as shown in FIG. 4B. Therefore, the ink of four colors of CMYK is supplied to the liquid discharge head 3, and the ink having passed through the liquid discharge head 3 is recovered to the supply system of the recording apparatus 1000. In this way, the ink of each color can circulate over the path of the recording apparatus 1000 and the path of the liquid discharge head 3.

5 illustrates an exploded perspective view of the parts and units constituting the liquid discharge head 3. The liquid discharge unit 300, the liquid supply unit 220, and the electrical wiring board 90 are attached to the case 80. A liquid connecting portion 111 (FIG. 3) is provided to the liquid supply unit 220, and a filter 221 for each color in communication with each opening of the liquid connecting portion 111 for removing foreign matter in the supplied ink. 2 and 3 are provided inside the liquid supply unit 220. The two liquid supply units 220 are each provided with filters 221 for two colors. The liquid passing through the filter 221 is supplied to each negative pressure control unit 230 provided in the corresponding liquid supply unit 220. Each negative pressure control unit 230 is a unit consisting of a pressure regulating valve for its respective color and is supplied to the recording apparatus 1000 generated due to fluctuations in the flow rate of the liquid by an operation such as a valve and a spring member provided therein. The change in pressure drop in the system (the supply system upstream of the liquid discharge head 3) is significantly attenuated. Therefore, the negative pressure control unit 230 can stabilize the change of the negative pressure on the downstream side (liquid discharge unit 300 side) from them within a specific range. Each negative pressure control unit 230 for each color has two pressure regulating valves built in as described in FIG. 2. These two pressure regulating valves are set to different control pressures, respectively, on the high pressure side via the common supply channel 211 in the liquid discharge unit 300 and on the low pressure side via the common recovery channel 212. Communicate with the liquid supply unit 220.

The case 80 is configured to include a liquid discharge unit support member 81 and an electrical wiring board support member 82, support the liquid discharge unit 300 and the electrical wiring board 90, and the liquid discharge head 3. It is configured to secure the stiffness of). The electrical wiring board support member 82 is for supporting the electrical wiring board 90 and is fixed by screwing to the liquid discharge unit support member 81. The liquid discharge unit support member 81 functions to correct the distortion and deformation of the liquid discharge unit 300, and thus suppresses the inequality of the recording by ensuring the relative positional accuracy of the plurality of recording element substrates 10. Therefore, it is preferable that the liquid discharge unit support member 81 has sufficient rigidity. Examples of suitable materials include metal materials such as stainless steel and aluminum and ceramics such as alumina. The liquid discharge unit support member 81 has openings 83 and 84, into which the bonded rubber member 100 is inserted. The liquid supplied from the liquid supply unit 220 passes through the coupling rubber member 100 and is guided to the third channel member 70, which is a component constituting the liquid discharge unit 300.

The liquid discharge unit 300 is composed of a plurality of discharge modules 200 and a channel member 210, and the cover member 130 is attached to the surface of the liquid discharge unit 300 facing the recording medium. The cover member 130 is a member having a framed surface provided with an elongated opening 131. The sealing portion 110 (FIG. 9) composed of the recording element substrate 10 and the sealing material included in the discharge module 200 is exposed from the opening 131 as illustrated in FIG. The frame portion of the periphery of the opening 131 functions as a contact surface for the cap member that covers the liquid discharge head 3 during recording standby. Therefore, by closing the periphery of the opening 131 with an adhesive, a sealant, a filling member or the like to fill the gaps and uneven portions of the discharge port surface of the liquid discharge unit 300, a closed space is preferably formed when the lid is attached.

Next, the configuration of the channel member 210 included in the liquid discharge unit 300 will be described. The channel member 210 is an article formed by stacking the first channel member 50, the second channel member 60, and the third channel member 70. The channel member 210 is a channel member that distributes the liquid supplied from the liquid supply unit 220 to each of the discharge modules 200 and returns the liquid recycled from the discharge module 200 to the liquid supply unit 220. The channel member 210 is fixed to the liquid discharge unit support member 81 by screws to suppress distortion and deformation of the channel member 210.

6A-6F are diagrams illustrating the front and rear sides of the channel members constituting the first to third channel members. FIG. 6A illustrates the side of the first channel member 50 on which the discharge module 200 is mounted, and FIG. 6F illustrates the surface of the third channel member 70 coming into contact with the liquid discharge unit support member 81. do. The first channel member 50 and the second channel member 60 have channel member contact surfaces that engage with each other illustrated in FIGS. 6B and 6C, respectively, and the second channel member as illustrated in FIGS. 6D and 6E. The same applies to the 60 and the third channel member 70. The joining second channel member 60 and the third channel member 70 have common channel grooves 62 and 71 formed thereon, which are eight common extending in the longitudinal direction of the channel member when facing each other. Form a channel. This forms a set of common feed channel 211 and common return channel 212 for each color in channel member 210 (FIG. 7). The communication port 72 of the third channel member 70 communicates with a hole in the engagement rubber member 100 to communicate with the liquid supply unit 220 by fluid connection. A plurality of communication ports 61 are formed on the bottom face of the common channel groove 62 of the second channel member 60 to communicate with one end of the individual channel groove 52 of the first channel member 50. The communication port 51 is formed at the other end of the individual channel groove 52 of the first channel member 50 to communicate with the plurality of discharge modules 200 by fluid connection via the communication port 51. These individual channel grooves 52 allow the channel to be integrated in the middle of the channel member.

The first to third channel members are preferably formed of a material that is corrosion resistant to liquid and has a low linear expansion coefficient. Exemplary suitable materials include alumina, liquid crystal polymers (LCPs), and composite materials (resin materials), wherein the composites include inorganic fillers such as fine silica particles or fibers such as polyphenyl sulfide (PPS), polysulfone (PSF) or In addition to substrates such as modified polyphenylene ethers (PPE). The channel member 210 may be formed by stacking three channel members and adhering with an adhesive, or when selecting a composite resin material as the material, the three channel members may be joined by fusion.

Next, the connection relationship of the channels in the channel member 210 will be described with reference to FIG. FIG. 7 is a partially enlarged perspective view of a channel in the channel member 210 formed by joining the first to third channel members, as seen from the side of the first channel member 50 on which the discharge module 200 is mounted. The channel member 210 includes, for each color, a common supply channel 211 (211a, 211b, 211c, 211d) and a common recovery channel 212 (212a, 212b) extending in the longitudinal direction of the liquid discharge head 3. 212c, 212d). A plurality of individual supply channels 213 (213a, 213b, 213c, and 213d) formed by the individual channel grooves 52 are connected to the common supply channel 211 of each color via the communication port 61. A plurality of individual recovery channels 214 (214a, 214b, 214c, 214d) formed as individual channel grooves 52 are connected to the common recovery channel 212 of each color via a communication port 61. This channel configuration allows ink to be integrated in the recording element substrate 10 disposed in the middle of the channel member from the common supply channel 211 to the individual supply channel 213. In addition, ink may be recovered from the recording element substrate 10 to the common recovery channel 212 via the individual recovery channel 214.

8 is a cross-sectional view taken along the line VIII-VIII of FIG. 7 illustrating the individual recovery channels 214a and 214c communicating with the discharge module 200 via the communication port 51. Although FIG. 8 illustrates only the individual recovery channels 214a and 214c, the individual supply channel 213 and the discharge module 200 communicate as illustrated in FIG. 7 in another cross section. The channel for supplying ink from the first channel member 50 to the recording element 15 (FIG. 10B) provided in the recording element substrate 10 is supported by the recording element substrate 10 and the discharge module 200. It is formed in the member 30. In addition, a channel for recovering (recycling) some or all of the liquid supplied to the recording element 15 to the first channel member 50 is formed in the recording element substrate 10 and the support member 30. The common supply channel 211 of each color is connected to the negative pressure control unit 230 (high pressure side) of the corresponding color via the liquid supply unit 220, and the common recovery channel 212 is passed through the liquid supply unit 220. It is connected to the negative pressure control unit 230 (low pressure side). The negative pressure control unit 230 generates a pressure difference between the common supply channel 211 and the common recovery channel 212. Therefore, in the liquid discharge head 3 according to the present application in which the channels are connected as illustrated in FIGS. 7 and 8, the common supply channel 211 → individual supply channel 213 → recording element substrate 10 → individual number of times. Flow for each color occurs in the order of channel 214 to common recovery channel 212.

Description of the discharge module

9A illustrates a perspective view of one discharge module 200, and FIG. 9B shows an exploded view thereof. The method of manufacturing the discharge module 200 is as follows. First, the recording element substrate 10 and the flexible printed circuit board 40 are attached to the support member 30 on which the communication port 31 is formed in advance. Subsequently, the terminal 16 on the recording element substrate 10 is electrically connected to the terminal 41 on the flexible printed circuit board 40 by wire bonding, and then the wire bonded portion (electric connecting portion) is It is covered and sealed by a sealant to form the seal portion 110. The terminal 42 at the other end of the flexible printed circuit board 40 from the recording element substrate 10 is electrically connected to the connecting terminal 93 (FIG. 5) of the electrical wiring board 90. The supporting member 30 is a supporting member for supporting the recording element substrate 10, and is also a channel member communicating between the channel member 210 and the recording element substrate 10 by fluid connection. Thus, the support member 30 must have a high degree of flatness and can also be coupled to the recording element substrate 10 with high reliability. Examples of suitable materials include alumina and resin materials.

Description of the structure of the recording element substrate

The configuration of the recording element substrate 10 according to this application example will be described. FIG. 10A is a plan view of a side portion of the recording element substrate 10 in which the discharge port 13 is formed, FIG. 10B is an enlarged view of the portion indicated by XB in FIG. 10A, and FIG. 10C is a recording element substrate from that in FIG. 10A. It is a top view of the rear surface of (10). The recording element substrate 10 has an ejection opening forming member 12, and four ejection opening forming columns corresponding to the ink color are formed in this ejection opening forming member as shown in Fig. 10A. Hereinafter, it will be mentioned that the direction in which the discharge port rows in which the plurality of discharge ports 13 are arranged extends will be referred to as the "discharge outlet row" direction.

The recording element 15, which is a heating element for generating energy used to discharge the liquid, is disposed at a position corresponding to the discharge port 13 as illustrated in FIG. 10B. The pressure chamber 23 containing the recording element 15 is isolated by the partition wall 22. The recording element 15 is electrically connected to the terminal 16 of FIG. 10A by electrical wiring (not shown) provided on the recording element substrate 10. The recording element 15 boils liquid based on a pulse signal input from the control circuit of the recording apparatus 1000 via the electrical wiring board 90 (FIG. 5) and the flexible printed circuit board 40 (FIG. 9). To generate heat. The force of foaming due to such boiling discharges the liquid from the discharge port 13. The liquid supply channel 18 extends along one side of each outlet port row, and the liquid recovery channel 19 extends along the other side. The liquid supply channel 18 and the liquid recovery channel 19 are channels extending in the direction of the row of discharge ports provided on the recording element substrate 10, and the discharge port 13 and the discharge port 13b are provided via the supply port 17a and the recovery port 17b, respectively. Communicate.

The sheet-like cover 20 is laminated on the rear surface from the surface of the recording element substrate 10 on which the discharge port 13 is formed, and the cover 20 is supplied with the liquid described below, as illustrated in FIGS. 10C and 11. It has a plurality of openings 21 in communication with the channel 18 and the liquid recovery channel 19. In this application, three openings 21 are provided in the cover 20 for each liquid supply channel 18, and two openings 21 are provided for each liquid recovery channel 19. The opening 21 of the cover 20 communicates with the plurality of communication ports 51 illustrated in FIG. 6A, as illustrated in FIG. 10B. The cover 20 functions as a cover forming part of the side of the liquid supply channel 18 and the liquid recovery channel 19 formed in the substrate 11 of the recording element substrate 10 as shown in FIG. The cover 20 is preferably sufficiently corrosion resistant to liquid and should have a high degree of precision regarding the shape of the opening and the position of the opening 21 from the standpoint of preventing color mixing. Therefore, a photosensitive resin material or a silicon plate, on which the opening 21 is formed by a photolithography process, is preferably used as the material for the cover 20. Thus, the cover 20 is for changing the pitch of the channel by the opening 21. The cover 20 is preferably thin in view of the pressure drop and is preferably formed of a film material.

Next, the flow of the liquid in the recording element substrate 10 will be described. FIG. 11 is a perspective view illustrating a cross section of the cover 20 and the recording element substrate 10 taken along plane XI-XI of FIG. 10A. The recording element substrate 10 is formed by stacking the discharge port forming member 12 formed of the photosensitive resin and the substrate 11 formed of silicon (Si), and the cover 20 is coupled to the rear face of the substrate 11. The recording element 15 is formed on the other side of the substrate 11 (FIG. 10B), and the grooves constituting the liquid supply channel 18 and the liquid recovery channel 19 extending along the discharge port row are located on the rear side thereof. Is formed. The liquid supply channel 18 and the liquid recovery channel 19 formed by the substrate 11 and the cover 20 are connected to the common supply channel 211 and the common recovery channel 212 in the channel member 210, respectively. There is a differential pressure between the liquid supply channel 18 and the liquid recovery channel 19. When the liquid is discharged from the plurality of discharge ports 13 of the liquid discharge head 3 and recording is performed, the liquid flows as follows due to the differential pressure in the discharge port 13 which does not perform the discharge operation. That is, the ink in the liquid supply channel 18 provided in the substrate 11 flows to the liquid recovery channel 19 through the supply port 17a, the pressure chamber 23, and the recovery port 17b (arrow of FIG. 11). Flow indicated by C). This flow is such that thickened ink, bubbles, foreign matters, etc. due to evaporation from the discharge port 13 can be recovered from the discharge port 13 and the pressure chamber 23 to the liquid recovery channel 19 where recording is not performed. do. This allows the thickening of the ink in the pressure chamber 23 and the discharge port 13 to be suppressed. The liquid recovered into the liquid recovery channel 19 is supported by the opening 21 and support of the cover 20 in the order of the communication port 51 of the channel member 210, the individual recovery channel 214 and the common recovery channel 212. It is recovered via the liquid communication port 31 of the member 30 (see FIG. 9B), and ultimately, to the supply path of the recording apparatus 1000.

That is, the liquid supplied from the recording apparatus main unit to the liquid discharge head 3 is supplied and recovered by the flow in the order described below. First, the liquid flows into the liquid discharge head 3 from the liquid connecting portion 111 of the liquid supply unit 220. Thereafter, the liquid communicates with the coupling rubber member 100, the communication port 72 provided in the third channel member 70, and the common channel groove 71, the common channel groove 62 provided in the second channel member 60, and the communication. It is supplied to the port 61 and the individual channel groove 52 and the communication port 51 provided in the first channel member 50. Thereafter, the liquid is supplied to the pressure chamber 23 in the order of the liquid supply channel 18 and the supply port 17a provided on the substrate 11. The liquid supplied to the pressure chamber 23 but not discharged from the discharge port 13 is provided with the recovery port 17b and the liquid recovery channel 19 provided in the substrate 11, the opening 21 provided in the cover 20 and the support member. It flows in the order of the liquid communication port 31 provided in the 30. Thereafter, the liquid is provided with the communication port 51 and the individual channel grooves 52 provided in the first channel member 50, the communication port 61 provided with the second channel member 60 and the common channel groove 62, the third, and the like. It flows in the order of the common channel groove 71 and the communication port 72 provided in the channel member 70 and the coupling rubber member 100. The liquid further flows out of the liquid discharge head 3 from the liquid connecting portion 111 provided in the liquid supply unit. In the first circulation path illustrated in FIG. 2, the liquid flowing from the liquid connecting portion 111 passes through the negative pressure control unit 230 and is then supplied to the coupling rubber member 100. In the second circulation path illustrated in FIG. 3, the liquid recovered from the pressure chamber 23 passes through the coupling rubber member 100, and then through the negative pressure control unit 230, the liquid discharge head from the liquid connecting portion 111. It flows out of (3).

In addition, all liquids introduced from one end of the common supply channel 211 of the liquid discharge unit 300 are supplied to the pressure chamber 23 via the individual supply channel 213 as illustrated in FIGS. 2 and 3. It is not. There is liquid flowing through the liquid supply unit 220 from the other end of the common feed channel 211 without entering the individual feed channel 213 at all. Therefore, providing a channel through which the liquid flows without proceeding through the recording element substrate 10 can provide a circulating flow of liquid even when the recording element substrate 10 has a fine channel with a large flow resistance as in the case of the present application. Reverse flow of Therefore, the liquid discharge head according to the present application can suppress the thickening of the liquid in the vicinity of the discharge port and in the pressure chamber, thereby suppressing the ejection deviation and the liquid non-ejection from the normal direction, and consequently, the high image quality Recording can be performed.

Explanation of Positional Relationship Between Recording Element Substrates

12 is a plan view showing a partially enlarged view of adjacent portions of the recording element substrate 10 of two adjacent ejection modules. The recording element substrate 10 according to this application example is formed in a parallelogram as illustrated in Figs. 10A to 10C. The ejection opening rows 14a to 14d in which the ejection openings 13 are arranged on the recording element substrate 10 are arranged inclined with respect to the conveying direction of the recording medium by a specific angle as illustrated in FIG. At least one discharge port in the discharge port row of adjacent portions of the recording element substrate 10 thereby overlaps in the conveying direction of the recording medium. In Fig. 12, two ejection openings on the line D exist in an overlapping relationship with each other. Such a layout can make the black streaks and blank portions of the recorded image hard to be seen by the drive control of the overlapping discharge ports even when the position of the recording element substrate 10 is somewhat displaced from the predetermined position. The configuration illustrated in FIG. 12 can also be used when a plurality of recording element substrates 10 are disposed in a straight line (inline) instead of a staggered arrangement. Therefore, black streaks and blank portions at overlapping portions between the recording element substrates 10 can be processed while suppressing an increase in the length of the liquid discharge head 3 in the conveying direction of the recording medium. Although the shape of the main surface of the recording element substrate 10 according to this discharge port row is a parallelogram, this is not a limitation. The configuration of the present disclosure may be appropriately applied even when the shape is rectangular, trapezoidal or other shape.

Description of the variation of the liquid discharge head configuration

The above-described modification of the liquid discharge head configuration will be described with reference to FIGS. 32 and 34A to 36. The same configuration and function as the above-described example will be omitted in the description, and the difference will mainly be described. In this variant, a plurality of liquid connecting portions 111, which are the connecting portions between the liquid and the liquid discharge head 3 outside, are formed in the longitudinal direction of the liquid discharge head 3 as illustrated in FIGS. 32, 34A and 34B. It is arranged in an integrated manner on one end side. A plurality of negative pressure control units 230 are arranged in an integrated manner on the other end side of the liquid discharge head 3 (FIG. 35). The liquid supply unit 220 included in the liquid discharge head 3 is configured as a long thin unit corresponding to the length of the liquid discharge head 3, and the channel and filter 221 corresponding to the liquid of four colors to be supplied. Has The positions of the openings 83 to 86 provided in the liquid discharge unit support member 81 are also at different positions from the above-described liquid discharge head 3 as illustrated in FIG.

36 illustrates the stacked state of the channel members 50, 60, 70. The plurality of recording element substrates 10 are arranged in a straight line on the top surface of the first channel member 50 which is the highest layer of the plurality of channel members 50, 60, 70. As a channel in communication with the opening 21 (FIG. 19C) formed on the rear side of each recording element substrate 10, two separate supply channels 213 and one individual recovery channel 214 are provided for each liquid color. exist. Correspondingly, also with respect to the opening 21 formed on the cover 20 provided on the rear face of the recording element substrate 10, two supply openings 21 and one recovery opening 21 for each liquid color. ) Exists. The common supply channel 211 and the common recovery channel 212 extending in the longitudinal direction of the liquid discharge head 3 are alternately arranged as illustrated in FIG. 36.

Second application example

The configuration of the liquid discharge head 3 and the inkjet recording apparatus 1000 according to the second application example will be described. It is noted that parts different from the first application example are mainly described, and parts identical to the first application example are omitted from the description.

Description of Inkjet Recording Device

20 illustrates an inkjet recording apparatus according to the second application example. The recording apparatus 1000 according to the second application example differs from the first application example in that full color recording is performed on the recording medium by arranging four monochromatic liquid ejecting heads 3 respectively corresponding to one of the CMYK inks. Although the number of ejection outlet rows available per color in the first application was one column, the number of ejection outlet rows available per color in the second application is 20 (Fig. 19A). This allows extremely fast recording to be performed by assigning recording data to a plurality of discharge port rows. Reliability can be improved by the ejection openings of the corresponding positions in the conveying direction of the recording medium of other rows which perform ejection in a complementary manner even when there are ejection openings indicating the ink body ejection, and therefore, such an arrangement is suitable for industrial printing. Do. The supply system, the buffer tank 1003 and the main tank 1006 (FIG. 2) of the recording apparatus 1000 are connected to the liquid discharge head 3 by fluid connection in the same manner as in the first application example. Each liquid discharge head 3 is also electrically connected to an electrical control unit, which transmits power and discharge control signals to the liquid discharge head 3.

Description of the circular path.

The first and second circulation paths illustrated in Figs. 2 and 3 can be used as the liquid circulation path between the recording apparatus 1000 and the liquid discharge head 3 in the same manner as the first application.

Description of the structure of the liquid discharge head

The structure of the liquid discharge head 3 according to the second application example will be described. 13A and 13B are perspective views of the liquid discharge head 3 according to the present application. The liquid discharge head 3 has 16 recording element substrates 10 arranged in a straight line in the longitudinal direction of the liquid discharge head 3, and is an ink jet line recording head capable of recording with liquid of one color. The liquid discharge head 3 has a liquid connecting portion 111, an input terminal 91 and a power supply terminal 92 in the same manner as in the first application example. The liquid discharge head 3 according to this application example is different from the first application example in that the input terminal 91 and the power supply terminal 92 are disposed on both sides of the liquid discharge head 3 because the number of discharge port rows is larger. This is to reduce the voltage drop and the signal transmission delay occurring in the wiring portion provided on the recording element substrate 10.

FIG. 14 is an exploded perspective view of the liquid discharge head 3 illustrating each part or unit constituting the liquid discharge head 3 disassembled according to a function. The roles of the unit and the member and the order of the liquid flow through the liquid discharge head are basically the same as in the first application, but the functions in which the rigidity of the liquid discharge head is guaranteed are different from each other. The stiffness of the liquid discharge head is mainly guaranteed by the liquid discharge unit support member 81 in the first application example, but is guaranteed by the second channel member 60 included in the liquid discharge unit 300 in the second application example. In this application there is a liquid discharge unit support member 81 connected to both ends of the second channel member 60. This liquid discharge unit 300 is mechanically coupled to the carriage of the recording apparatus 1000, whereby the liquid discharge head 3 is located. The liquid supply unit 220 having the electrical wiring board 90 and the negative pressure control unit 230 is coupled to the liquid discharge unit support member 81. A filter (not shown) is embedded in the two liquid supply units 220. The two negative pressure control unit 230 is set to control the pressure by the high and low negative pressures relatively different from each other. When the high pressure side and low pressure side negative pressure control unit 230 is disposed at the end of the liquid discharge head 3 as illustrated in FIGS. 14A to 15, a common supply channel extending in the longitudinal direction of the liquid discharge head 3. Liquid flows on 211 and common recovery channel 212 are in opposite directions. This facilitates heat exchange between the common feed channel 211 and the common recovery channel 212 so that the temperature difference between the two common channels can be reduced. This is advantageous in that a temperature difference does not easily occur between a plurality of recording element substrates 10 arranged along a common channel, and therefore, unevenness of recording due to the temperature difference does not easily occur.

The channel member 210 of the liquid discharge unit 300 will be described in detail next. The channel member 210 is a first channel member 50 and a second channel member 60 stacked as illustrated in FIG. 14, and the liquid supplied from the liquid supply unit 220 to the discharge module 200. To distribute. The channel member 210 also functions as a channel member for returning the liquid recycled from the discharge module 200 to the liquid supply unit 220. The second channel member 60 of the channel member 210 is a channel member in which the common supply channel 211 and the common recovery channel 212 are formed, and is mainly responsible for the rigidity of the liquid discharge head 3. . Thus, the material of the second channel member 60 is sufficiently corrosion resistant to liquid and has high mechanical strength. Examples of materials suitably used include stainless steel, titanium (Ti), alumina and the like.

FIG. 15A illustrates the face of the first channel member 50 on the side on which the discharge module 200 is mounted, and FIG. 15B illustrates the back face from which it comes into contact with the second channel member 60. Unlike the case of the first application example, the first channel member 50 according to the second application example is an arrangement in which a plurality of members corresponding to the discharge module 200 are arranged adjacently. The use of such a divided structure allows a length corresponding to the length of the liquid discharge head to be realized, and thus can be used particularly suitably for a relatively long scale liquid discharge head corresponding to, for example, a B2 size and a larger sheet. . The communication port 51 of the first channel member 50 communicates with the discharge module 200 by fluid connection as illustrated in FIG. 15A, and the individual communication port 53 of the first channel member 50 is shown in FIG. Communication with the communication port 61 of the second channel member 60 is by fluid connection as illustrated in 15b. FIG. 15C illustrates a surface of the second channel member 60 in contact with the first channel member 50, FIG. 15D illustrates a cross section of an intermediate portion of the second channel member 60, taken in the thickness direction, 15E is a diagram illustrating the face of the second channel member 60 in contact with the liquid supply unit 220. The function of the channel and communication port of the second channel member 60 is the same as that of one color in the first application. One of the common channel grooves 71 of the second channel member 60 is the common supply channel 211 illustrated in FIG. 16, and the other is the common recovery channel 212. Both have a liquid supplied from one end side to the other end side along the longitudinal direction of the liquid discharge head 3. Unlike the case of the first application example, the longitudinal directions of the liquids for the common supply channel 211 and the common recovery channel 212 are opposite to each other.

16 is a perspective view illustrating a connection relationship relating to liquid between the recording element substrate 10 and the channel member 210. The common supply channel 211 and the common recovery channel 212 extending in the longitudinal direction of the liquid discharge head 3 are provided in the channel member 210 as illustrated in FIG. 16. The communication ports 61 of the second channel member 60 are each located with and connected to the respective communication ports 53 of the first channel member 50, thereby communicating the second channel member 60. A liquid supply path is formed from the port 72 to the communication port 51 of the first channel member 50 via the common supply channel 211. In the same way, a liquid supply path is also formed from the communication port 72 of the second channel member 60 via the common recovery channel 212 to the communication port 51 of the first channel member 50.

FIG. 17 is a diagram illustrating a cross section taken along XVII-XVII of FIG. 16. FIG. 17 shows how the common feed channel 211 is connected to the discharge module 200 via the communication port 61, the individual communication port 53 and the communication port 51. Although omitted from the illustration of FIG. 17, it can be clearly seen from FIG. 16 that the other cross section will show the individual recovery channel 214 connected to the discharge module 200 through a similar path. A channel is formed on the recording element substrate 10 and the discharge module 200 to communicate with the discharge port 13, and the discharge port 13 (pressure chamber 23) in which some or all of the supplied liquid does not perform the discharge operation. Is recycled in the same manner as in the first application. Through the liquid supply unit 220 in the same manner as in the first application example, the common supply channel 211 is connected to the negative pressure control unit 230 (high pressure side), and the common recovery channel 212 is the negative pressure control unit 230. ) (Low pressure side). Therefore, a flow occurs due to the differential pressure, and the flow flows from the common supply channel 211 to the common recovery channel 212 through the discharge port 13 (pressure chamber 23) of the recording element substrate 10.

Description of the discharge module

18A illustrates a perspective view of one discharge module 200, and FIG. 18B is an exploded view thereof. The difference with respect to the first application example is that the following points, that is, a plurality of terminals 16 are arranged on both sides (long side portions of the recording element substrate 10) in the direction of the plurality of discharge port rows of the recording element substrate 10. And two flexible printed circuit boards 40 are provided on one recording element substrate 10 and electrically connected thereto. The reason is that the number of rows of discharge ports provided on the recording element substrate 10 is 20 rows, which is a significant increase compared to the eight rows in the first application example. The purpose is to keep the maximum distance from the terminal 16 to the recording element 15 provided corresponding to the discharge port row short, thereby reducing the voltage drop and signal transmission delay occurring in the wiring portion provided to the recording element substrate 10. It is to let. The liquid communication port 31 of the support member 30 is provided in the recording element substrate 10 and is opened to cover all the discharge port rows. The difference is the same as in the first application example.

Description of the structure of the recording element substrate

FIG. 19A is a schematic diagram illustrating a surface of the recording element substrate 10 of the side where the discharge port 13 is disposed, and FIG. 19C is a schematic diagram illustrating the back surface of the one illustrated in FIG. 19A. FIG. 19B is a schematic diagram illustrating the surface of the recording element substrate 10 when the cover 20 provided on the rear surface side of the recording element substrate 10 is removed in FIG. 19C. The liquid supply channel 18 and the liquid recovery channel 19 are alternately provided on the rear face of the recording element substrate 10 along the discharge port row direction as illustrated in Fig. 19B. Although the number of ejection opening rows is much larger than that of the first application example, a remarkable difference from the first application example is that the terminals 16 are disposed on both side portions of the recording element substrate 10 along the ejection opening row direction as described above. Is the point. The basic configuration is the same as that of the first application, for example, a set of liquid supply channels 18 and liquid recovery channels 19 are provided in each discharge port row and communicate with the liquid communication port 31 of the support member 30. Opening 21 is provided in the cover 20, and so on.

Third application example

The configurations of the liquid discharge head 3 and the ink jet recording apparatus 1000 according to the third application example will be described. The liquid discharge head 3 according to the third application example is a page-wide head for recording on a B2 size recording medium sheet in a single scan. The third application example is similar to the second application example with respect to a number of points, so the differences with respect to the second application example are mainly described later, and the same parts as the second application example are omitted from the description.

Description of Inkjet Recording Device

37 is a schematic diagram of an ink jet recording apparatus according to the present application. The recording apparatus 1000 discharges liquid onto the intermediate transfer member (intermediate transfer drum 1007) to form an image without directly recording onto the recording medium from the liquid discharge head 3, and then forms an image on the recording medium ( 2) The image recording apparatus 1000 has four monochromatic liquid ejecting heads 3 corresponding to four ink types of CMYK disposed on an arcuate portion along the intermediate transfer drum 1007. Thus, full color recording is performed on the intermediate transfer member, and the recorded image is dried in an appropriate state on the intermediate transfer member, and then the recording medium conveyed by the sheet conveying roller 1009 by the transfer unit 1008 ( 2) The sheet conveying system of the second application example has a horizontal conveying path mainly intended to convey the cut sheet, while the present application takes a continuous sheet fed from a main roll (not shown). This kind of drum conveying system can easily convey the sheet with a specific tension applied, so there is less conveying jamming when performing high speed recording, thus improving the reliability of the apparatus, It is suitable for application to commercial printing, etc. The supply system of the recording apparatus 1000, the buffer tank 1003 and the main tank 1006 are connected to the liquid discharge head 3 by fluid connection in the same manner as in the first and second applications. Each liquid discharge head 3 is also electrically connected to an electrical control unit, which transmits power and discharge control signals to the liquid discharge head 3.

Description of the fourth circular path

Although the first and second circulation paths illustrated in FIGS. 2 and 3 between the tank and the liquid discharge head 3 of the recording apparatus 1000 can be applied as the liquid circulation path in the same manner as in the second application, FIG. 38 The circulation paths illustrated in are suitable. The main difference to the second circulation path of FIG. 3 is the addition of a bypass valve 1010 in communication with the channels of each of the first circulation pump 1001, 1002 and the second circulation pump 1004. The bypass valve 1010 functions to lower the pressure on the upstream side of the bypass valve 1010 due to the valve opening when the pressure exceeds the predetermined pressure (first function). In addition, the bypass valve 1010 functions to open and close the valve at a predetermined timing by a signal from the control board in the recording apparatus main unit (second function).

According to the first function, an excessively large or excessively small pressure can be prevented from being applied to the channel downstream of the first circulation pumps 1001 and 1002 and upstream of the second circulation pump 1004. For example, when the function of the first circulation pumps 1001 and 1002 is malfunctioning, excessive flow rate or pressure may be applied to the liquid discharge head 3. This can cause liquid to leak from the discharge port 13 of the liquid discharge head 3 or damage the engaging portion in the liquid discharge head 3. However, when a bypass valve is added to the first circulation pumps 1001 and 1002 as in this application, opening of the bypass valve 1010 opens the liquid path upstream of the circulation pump, so that excessive pressure Even if it occurs, the problem as described above can be suppressed.

Also, due to the second function, when the circulation operation is stopped, all the bypass valves 1010 are controlled signals from the main unit side after the first circulation pumps 1001 and 1002 and the second circulation pump 1004 stop. Open quickly on the basis of This allows the high negative pressure (eg several kPa to several tens kPa) of the downstream portion of the liquid discharge head 3 (between the negative pressure control unit 230 and the second circulation pump 1004) to be released in a short time. . In the case of using a volumetric pump such as a diaphragm pump as a circulation pump, a check valve is generally built into the pump. However, opening of the bypass valve 1010 likewise allows pressure relief on the downstream side of the liquid discharge head 3 from the downstream buffer tank 1003 to be performed. Although the pressure release on the downstream side of the liquid discharge head 3 can likewise be performed only from the upstream side, there is a pressure drop in the channel in the liquid discharge head 3 and the channel upstream of the liquid discharge head 3. do. Accordingly, there is a fear that the pressure is time-consuming, the pressure in the common channel in the liquid discharge head 3 temporarily drops too much, and the meniscus at the discharge port may be destroyed. Opening of the bypass valve 1010 on the upstream side of the liquid discharge head 3 promotes pressure discharge on the downstream side of the liquid discharge head 3, so that the risk of breaking meniscus at the discharge port is reduced.

Description of the structure of the liquid discharge head

The structure of the liquid discharge head 3 according to the third application example will be described. 39A is a perspective view of the liquid discharge head 3 according to the present application, and FIG. 39B is an exploded perspective view thereof. The liquid discharge head 3 has 36 recording element substrates 10 arranged in a straight line (inline) in the longitudinal direction of the liquid discharge head 3, and is a line type (page-wide) for recording using a single color liquid. A) inkjet recording head. The liquid discharge head 3 has a signal input terminal 91 and a power supply terminal 92 in the same manner as in the second application example, and also has a shielding plate 132 to protect the longitudinal side surface of the head. do.

39B is an exploded perspective view of the liquid discharge head 3 exemplifying each part or unit constituting the liquid discharge head 3 disassembled according to the function (the shield plate 132 is not shown). The roles of the units and members and the order of the liquid flow through the liquid discharge head 3 are basically the same as in the second application example. The third application example is different from the second application example mainly in terms of the shape of the first channel member 50, the position of the negative pressure control unit 230, and the point of the electrical wiring board 90 divided and arranged into a plurality. For example, in the case of the liquid ejecting head 3 having a length corresponding to the B2 size recording medium, since the amount of electric power used by the liquid ejecting head 3 is large, as in the case of this application example, 8 electrical wirings Substrate 90 is provided. Each of the four electrical wiring boards 90 is attached to both sides of the thin electrical wiring board support member 82 attached to the liquid discharge unit support member 81.

40A is a side view of the liquid discharge head 3 having the liquid discharge unit 300, the liquid supply unit 220, and the negative pressure control unit 230, FIG. 40B is a schematic diagram illustrating liquid flow, and FIG. 40C is a view. It is a perspective view which illustrates the cross section taken along the line XLC-XLC of 40a. Part of the configuration is simplified to facilitate understanding.

The liquid connecting portion 111 and the filter 221 are provided in the liquid supply unit 220, and the negative pressure control unit 230 is integrally formed under the liquid supply unit 220. This allows the distance in the height direction between the recording element substrate 10 and the negative pressure control unit 230 to be reduced as compared with the second application example. This configuration is advantageous in that the number of channel connecting portions in the liquid supply unit 220 is reduced, and the number of parts and the assembly process as well as the increased reliability regarding leakage of the recording liquid can be reduced.

Further, the head head difference between the negative pressure control unit 230 and the surface on which the discharge port is formed is relatively smaller, and therefore, the inclination angle of the liquid discharge head 3 with respect to each liquid discharge head 3 as illustrated in FIG. 37. Can be suitably applied to other recording apparatuses. This is because the reduced head difference allows the negative pressure difference applied to the discharge port of each recording element substrate 10 to be reduced even when each of the plurality of liquid discharge heads 3 is used at different inclination angles. Reducing the distance from the negative pressure control unit 230 to the recording element substrate 10 also reduces the pressure drop difference due to fluctuations in the flow of the liquid because the flow resistance is reduced, and more stable negative pressure control can be performed. It is preferable in that it exists.

40B is a schematic diagram illustrating the flow of the recording liquid in the liquid discharge head 3. The circuit is the same as the circulation path illustrated in FIG. 38, but FIG. 40B illustrates the liquid flow in each component in the actual liquid discharge head 3. The common supply channel 211 and the common recovery channel 212 are provided in the second channel member 60 which is thin, extending in the longitudinal direction of the liquid discharge head 3. The common feed channel 211 and the common recovery channel 212 are configured to allow liquids to flow in opposite directions, and a filter 221 is disposed upstream of these channels to trap foreign matter introduced from the connecting portion 111 or the like. do. This arrangement in which the liquid flows in opposite directions in the common supply channel 211 and the common recovery channel 212 is preferred in that the temperature gradient in the longitudinal direction in the liquid discharge head 3 is reduced. The flow directions of the common feed channel 211 and the common recovery channel 212 are shown to be the same direction in FIG. 38 to simplify the description.

The negative pressure control unit 230 is disposed downstream of each of the common supply channel 211 and the common recovery channel 212. Common feed channel 211 has a branch portion to a plurality of individual feed channels 213 along the path, and common return channel 212 has a branch portion to a plurality of individual recovery channels 214 along the path. Individual feed channels 213 and individual return channels 214 are formed in the plurality of first channel members 50. Each of the individual channels communicates with the opening 21 of the cover 20 provided on the back side of the recording element substrate 10 (see FIG. 19C).

The negative pressure control unit 230 denoted by H and L in FIG. 40B is a high pressure side H and a low pressure side L unit. Each negative pressure control unit 230 is a back pressure type pressure regulating mechanism set to control the upstream pressure of the negative pressure control unit 230 with relative high (H) and low (L) negative pressures. The common supply channel 211 is connected to the negative pressure control unit 230 (high pressure side), and the common recovery channel 212 is connected to the negative pressure control unit 230 (low pressure side). This creates a differential pressure between the common feed channel 211 and the common recovery channel 212. This differential pressure is common when the liquid passes from the common supply channel 211 to the individual supply channel 213, the discharge port 13 (pressure chamber 23 and the individual recovery channel 214) in the recording element substrate 10 in that order. Flow to return channel 212.

40C is a perspective view illustrating a cross section taken along line XLC-XLC in FIG. 40A. Each discharge module 200 of this application example is configured to include a first channel member 50, a recording element substrate 10, and a flexible printed circuit board 40. This application example does not have the supporting member 30 (FIG. 18) described in the second application example, and the recording element substrate 10 has a cover 20 which is directly coupled to the first channel member 50. As shown in FIG. The common supply channel 211 provided on the second channel member 60 is individually supplied from the communication port 61 provided on the upper surface thereof through the individual communication port 53 formed on the lower surface of the first channel member 50. The liquid is supplied to the channel 213. The liquid then passes through the pressure chamber 23 and is recovered to the common recovery channel 212 via the respective recovery channel 214, the individual communication port 53, and the communication port 61 in that order.

Unlike the arrangement illustrated in the second application example illustrated in FIGS. 15A and 15B, the individual communication ports 53 on the lower side of the first channel member 50 (the side facing the second channel member 60) may be removed. It is an opening of sufficient size with respect to the communication port 61 formed in the upper surface of the two-channel member 60. According to this configuration, even when there is a positional deviation when mounting the discharge module 200 to the second channel member 60, in a reliable manner between the first channel member 50 and the second channel member 60. Fluid communication is realized, so that the yield in manufacturing the head is improved and the cost is reduced.

First embodiment

Specific embodiments are described below. Although the case where the liquid discharge head according to the first application example illustrated in FIGS. 1 to 12 is used is described, the liquid discharge head according to another application example may also be used in the same manner.

Explanation of flow of liquid in discharge port

21A to 21C are schematic views for explaining in detail the vicinity of the discharge port of the recording element substrate. FIG. 21A is a plan view from the discharge direction in which the liquid is discharged, FIG. 21B is a sectional view taken along the line XXIB-XXIB in FIG. 21A, and FIG. 21C is a perspective view illustrating the cross section taken along the line XXIC-XXIC in FIG. 21A.

A circulating flow C through which liquid in the liquid supply channel 18 provided to the substrate 11 flows into the liquid recovery channel 19 through the supply port 17a, the pressure chamber 23 and the recovery port 17b is As described above, the discharge port 13 which does not perform the discharge operation is formed in the recording element substrate 10. The speed of the circulating flow C in the pressure chamber 23 is, for example, about 0.1 to 100 mm / s, and is a speed at which the performing of the ejection operation in the state in which the liquid flows hardly affects the drop landing accuracy or the like. A liquid meniscus, i.e., an outlet opening 24, which is an interface between the liquid and the atmosphere, is formed in the outlet opening 13. The discharge port 13 is an opening of the through-path 25 formed in the discharge port forming member 12, and is an opening that is open at the surface of the discharge port forming member 12 on the side from which the liquid is discharged, as illustrated in Fig. 21B. In the following description, the through path 25 will be referred to as the "discharge port part", the direction in which the liquid is discharged from the discharge port 13 (vertical direction in FIG. 21B) will be referred to as the "discharge direction", and the liquid is pressured. The direction of flow in the chamber 23 (horizontal direction in FIG. 21B) will be referred to simply as “flow direction”.

Now, the dimensions of the pressure chamber 23 and the discharge port portion 25 are defined as follows. The height of the pressure chamber 23 on the upstream side from the portion communicating with the discharge port 25 is defined as H, the length of the discharge port 25 in the discharge direction is defined as P, and the width in the flow direction is It is defined as W. Examples of these dimensions are 3 to 30 μm for H, 3 to 30 μm for P, and 6 to 30 μm for W. In addition, an example in which the discharged liquid is an ink will be described later, which has a nonvolatile solvent concentration of 30%, a color material concentration of 3%, and a viscosity of 0.002 to 0.003 Pa · s.

22 is an enlarged sectional view of the vicinity of the discharge port 13, and shows the state of the circulating flow C in the discharge port 13, the discharge port 25, and the pressure chamber 23 when the circulation flow C is in a normal state. . Specifically, the arrow indicates the pressure chamber 23 from the supply port 17a at a flow rate of 1.26 × 10 ⁻⁴ ml / min in the recording element substrate 10 having H of 14 μm, P of 5 μm, and W of 12.4 μm. Represents the flow of ink flowing into). It should be noted that the length of the arrow in FIG. 22 does not represent the velocity.

Although evaporation of the ink from the discharge port 13 causes a change in the color material concentration, the recording element substrate 10 of the above-described dimensions suppresses stagnation of such ink in the discharge port 13 and the discharge port portion 25. Is arranged to. That is, the portion of the circulating flow C in the pressure chamber 23 flows inside the discharge port 25, reaches the position of the meniscus formed in the discharge port 13 (near the meniscus interface), and then, The discharge port 25 returns to the pressure chamber 23. Therefore, not only the ink in the discharge port portion 25 already affected by the evaporation but also the ink near the discharge port interface 24 having a particularly high evaporation or influence does not wait inside the discharge port portion 25 to the pressure chamber 23. Will flow. Here, the characteristic of the circulating flow C is that at least the velocity component (hereinafter referred to as " positive " Velocity component ". The flow mode in which the circulating flow C has a positive velocity component at least near the middle portion of the outlet interface 24 as illustrated in FIG. 22 is referred to as “flow mode A”. The flow mode in which the circulating flow C has a negative velocity component (from right to left in FIG. 21B) as opposed to the positive velocity component near the middle portion of the outlet interface 24 to be described later is referred to as "flow mode B". do.

The inventor determines whether the circulating flow C of the liquid discharge head is the flow mode A (or the flow mode B) by the above-described dimensions (H, P, W) of the discharge port portion 25 and the pressure chamber 23. I found out. That is, in the liquid discharge head in which the circulating flow C is the flow mode A, the height H of the upstream pressure chamber 23, the length P of the discharge port 25 in the discharge direction, and the flow direction The length W satisfies the following relationship (see FIG. 21B).

H ^-0.34 × P ^-0.66 × W> 1.7 (1)

Therefore, the flow mode A as illustrated in FIG. 22 is realized in the liquid discharge head that satisfies the relationship of equation (1), and the flow mode B is realized in the liquid discharge head that does not satisfy the relationship of equation (1). do. The left side of equation (1) will be referred to as "determined value J".

23 is a graph for explaining the relationship between the flow mode and the dimensions of the liquid discharge head. The horizontal axis represents the ratio of P to H (P / H), and the vertical axis represents the ratio of W to P (W / P). The thick line T in FIG. 23 is a threshold line that satisfies the following relationship.

(2)

(2)

Flow mode A is realized in the liquid discharge head of the portion (shading area) in which the relationship of H, P and W exceeds the threshold line T in FIG. 23, and the flow mode B is realized below the threshold line T. In FIG. That is, the flow mode A is realized in the liquid discharge head that satisfies the following relationship.

(3)

(3)

Rearranging the equation (3) yields the equation (1), so that the flow mode A is realized in the liquid discharge head in which the relationship of H, P, and W satisfies the equation (1). On the other hand, the flow mode B is realized in the liquid discharge head in which the relationship of H, P and W satisfies the following relationship.

H ^-0.34 × P ^-0.66 × W ≤ 1.7 (4)

Now, the liquid ejection head having the flow mode B is advantageous in that the crack of the ejection opening forming member 12 can be suppressed, because the length P of the ejection opening 25 in the longitudinal direction, that is, This is because the thickness of the discharge port forming member 12 can be formed larger. The height H of the pressure chamber 23 can also be high, which is also advantageous because the pressure difference required to produce the circulating flow C can be smaller.

The above-described relationship equation and the flow in the discharge port portion 25 are described in detail with reference to Figs. 24 to 25D. 24 is a graph illustrating the results of checking the flow in the discharge port portion of the liquid discharge head of various shapes. The dots in FIG. 24 represent liquid discharge heads determined to have flow mode A, and the scissors table represent discharge heads determined to have flow mode B. FIG. 25A to 25D are diagrams illustrating an example of the circulating flow of the liquid discharge head indicated by the respective points A to D of FIG. 24.

The liquid discharge head indicated by point A in FIG. 24 has H of 3 m, P of 9 m and W of 12 m. The determined value J on the left side of Equation (1) is 1.93, which is larger than 1.7. In this case, the actual flow in the outlet port 25 is as illustrated in FIG. 25A, which is a flow mode A with a positive velocity component near the middle portion of the outlet interface 24. The liquid discharge head indicated by point B in FIG. 24 has H of 8 μm, P of 9 μm and W of 12 μm. Determination J is 1.39, which is less than 1.7. In this case, the actual flow in the outlet port 25 is as illustrated in FIG. 25B, which is the flow mode B with a negative velocity component near the middle portion of the outlet interface 24. The liquid discharge head corresponding to point C in FIG. 24 has 6 μm H, 6 μm P, and 12 μm W. FIG. Determination J is 2.0, which is greater than 1.7. In this case, the actual flow in the outlet port 25 is as illustrated in FIG. 25C, which is the flow mode A with a positive velocity component near the middle portion of the outlet interface 24. The liquid discharge head indicated by point D in FIG. 24 has 6 μm H, 6 μm P and 6 μm W. FIG. Determination J is 1.0, which is less than 1.7. In this case, the actual flow in the outlet port 25 is as illustrated in FIG. 25D, which is the flow mode B with a negative velocity component near the middle portion of the outlet interface 24.

Thus, the liquid discharge head representing the flow mode A and the liquid discharge head representing the flow mode B can be distinguished by the threshold line T in FIG. 23 as a boundary. That is, the liquid ejection head in which the determined value J in Equation (1) is larger than 1.7 realizes the flow mode A, and the circulating flow C has a positive component at least near the middle portion of the ejection opening interface 24. .

It should be noted that the conditions H, P and W are the main influences on whether the circulating flow C in the discharge port portion 25 is the flow mode A or the flow mode B. As an example, the influence of other conditions such as the flow velocity of the circulating flow C, the viscosity of the ink, and the width (length in the direction orthogonal to the flow direction) of the discharge port 13 is insignificant compared to the conditions of H, P, and W. Therefore, the flow rate of the circulating flow C and the viscosity of the ink can be appropriately set according to the requirements of the liquid discharge head (ink jet recording apparatus) and the use environment conditions. As an example, an ink having a flow rate of circulating flow C in the pressure chamber 23 of 0.1 to 100 mm / s and a viscosity of 0.01 Pa.s may be used. When the amount of evaporation of ink from the discharge port in the liquid discharge head having the flow mode A due to the change in the use environment or the like increases, the flow mode A can be maintained by appropriately increasing the circulating flow C. On the other hand, however, in the liquid discharge head whose dimensions are set to realize the flow mode B, the flow mode A cannot be realized by increasing the flow rate of the circulating flow C. Of the liquid discharge heads in which the flow mode A is realized, a liquid discharge head having H of 20 µm or less, P of 20 µm or less, and W of 30 µm or less is particularly preferable, whereby higher resolution image formation becomes possible. .

Second embodiment

30 is a diagram illustrating the flow of ink flowing through the liquid ejecting head according to the second embodiment. The liquid discharge head according to the present embodiment has a stepped portion at the communication portion between the discharge port portion 13b and the channel 26 as illustrated in FIG. 30. The part from the discharge port 13 to the part where the stepped part is formed is the discharge port part 13b, and the discharge port part 13b is, in this embodiment, via the channel (part of the channel) having a diameter larger than itself in the channel. Connected to 26. Therefore, P, W and H of this embodiment are defined as illustrated in FIG. Flow mode A can likewise be realized in a liquid discharge head having this shape by setting P, W and H so as to satisfy equation (3). Therefore, the multi-step configuration from the channel toward the discharge port can make the flow resistance from the recording element 15 toward the discharge port 13 relatively small.

Third embodiment

31A and 31B are diagrams particularly illustrating two examples of the shape of the discharge port of the liquid discharge head according to the third embodiment. 31A and 31B are plan views (schematic diagrams) of observing the discharge port 13 from the liquid discharge direction. The ejection opening 13 according to the present embodiment is shaped so that a projection 13d extending from the opposing positions toward the center of the ejection opening is formed. The protrusion 13d extends continuously from the outer surface of the discharge port 13 to the inner portion of the discharge port 13b. Flow mode A can likewise be realized in an arrangement with these protrusions by setting H, P and W to satisfy the above equation (2).

The discharge port in the example illustrated in FIG. 31A has a projection 13d projecting in the direction intersecting with the flow of liquid in the channel 26. The ejection opening in the example illustrated in Fig. 31B has a projection 13d that protrudes in the direction along the flow of ink. Forming such a projection in the ejection opening 13 allows the meniscus formed between the projections 13d to be more easily maintained than the meniscus of the other portion of the ejection opening, so that the droplet tail of the ink droplets extending from the ejection opening Can be cut at an earlier time. Therefore, generation of microdroplet mist generated with the main droplets can be suppressed.

Description of features common to the first to third embodiments

Explanation of influence of relative dielectric constant of degraded ink

As described above, the ink in the discharge port portion 25, in particular, the ink near the discharge port interface 24 has a positive velocity component reaching the vicinity of the discharge port interface 24 in the liquid discharge head 3 in the flow mode A. It can be moved to the pressure chamber 23 by the circulating flow (C). Therefore, stagnation of the ink in the discharge port portion 25 can be suppressed, and an increase in the color material concentration of the ink in the discharge port portion 25 with respect to evaporation from the discharge port 13 can be reduced. However, even when circulating flow C is present in the pressure chamber 23, circulating flow C cannot easily occur near the periphery of the discharge port 13 due to the influence of the viscosity, so that stagnation of ink is suppressed. Difficult to do

26A-26C show a liquid discharge head (J = 1.3, H = 14 μm, P = 11 μm, W = 16 μm) with flow mode B in FIG. 26A, and a liquid discharge head with flow mode A in FIG. 26B (FIGS. J = 2.3, H = 14 μm, P = 6 μm, W = 18 μm), and the liquid discharge head having flow mode A in FIG. 26C (J = 3.5, H = 5 μm, P = 5 μm, W = It is a figure which illustrates the ink density in the discharge port part 25 for 18 micrometers). 26A to 26C are orders in which the circulating flow C is likely to reach the discharge port interface 24. It can be seen from FIGS. 26B and 26C that even when the liquid discharge head has the flow mode A, stagnation of the concentrated ink occurs in the vicinity of the periphery of the discharge port 13 (the area surrounded by the dotted line as the "concentrated area"). Thus, when the ink has a large amount of solids (for example, 8 wt% or more), it is easier to be affected by the concentrated ink near the periphery of the discharge port 13, and defect discharge occurs more easily. Solids included in the ink include emulsions of pigments, resins, polymers and the like.

In order to offset the defect ejection that occurs when using ink having a large amount of solids, the present inventors have found that reducing the relative dielectric constant of the ink causes a phenomenon of receding of the pigment of the ink to It has been found that concentration can be inhibited. The retreat phenomenon of the pigment retreats (moves) to the pressure chamber 23 side (recording element side) in which, when the moisture of the ink is evaporated from the discharge port, the water having more hydrophilic pigment in the vicinity of the discharge port is contained. This is a phenomenon in which the pigment concentration near the discharge port interface decreases. This will be explained with reference to Figs. 27A to 29C.

27A and 27B show the pigment in the discharge port portion 25 in the state where the circulating flow C is generated, using the liquid discharge head having the flow mode A (J = 2.3) and the ink in which the amount of solids is 8% by weight or more. It is a figure which illustrates the result of numerical value calculation (simulation) of concentration distribution. FIG. 27A illustrates a case in which the retraction phenomenon of the pigment does not substantially occur, and FIG. 27B illustrates a state in which the retraction phenomenon of the pigment occurs. In the same way, Figs. 27C and 27D show the ejection openings in the state in which the circulating flow C is generated, using the liquid ejecting head having the flow mode A (J = 2.3) and the ink in which the amount of solids is 8% by weight or more. It is a figure which illustrates the result of numerical value calculation of the solvent concentration distribution in 25). FIG. 27C illustrates a case in which the pigment retreat phenomenon does not substantially occur, and FIG. 27D illustrates a state in which the pigment recession phenomenon occurs.

In the case where substantially no retreat of the pigment occurs, the concentration of the ink due to the evaporation of the ink from the ejection opening 13 is maintained even when the circulating flow C is generated as illustrated in Fig. 27A. It cannot be sufficiently suppressed in the vicinity of the periphery of, and concentration of the pigment occurs. As a result, the agglomeration properties of the pigment particles with each other increase, the ink is easily thickened, and in extreme cases, the ink is solidified so as to discharge defects at the first discharge after a pause of a discharge operation for a certain amount of time (e.g., a discharge speed Changes more easily). On the other hand, when the retraction phenomenon of the pigment occurs, the discharge port 13 due to the circulating flow C reaching near the discharge port 13 because the pigment is retracted toward the pressure chamber 23 side as illustrated in FIG. 27B. It is not easily congested near the periphery of the As a result, the ink is not easily thickened, and solidification is suppressed, so that defect ejection does not easily occur upon initial ejection after a pause.

As illustrated in Figs. 27C and 27D, the concentration of the solvent in the peripheral portion of the discharge port 13 occurs in the same manner regardless of whether the retreat phenomenon of the pigment occurs. However, the influence of the pigment-like solids on the thickening of the ink is generally greater, and therefore, the suppression of stagnation of the ink solid near the ejection opening 13 is particularly important in view of suppressing the ink thickening affecting the ejection. .

Fig. 28 shows each other in the liquid ejecting head having the flow mode A (J = 2.3), with the circulating flow C being formed, the ejection operation being stopped for 10 seconds, and then the ejection speed is plotted against the ejection count value. It is a graph when two types of inks having different relative permittivity (solvent composition) are used. Specifically, the vertical axis is a ratio in which the average value of the ejection speeds after the 20th ejection after rest is taken as 1. Results shown are 15% by weight of solids in the ink (including emulsions of pigments, resins, polymers, etc.), flow rate of circulating flow (C) of 10 mm / s (circulation speed), and head temperature of 55 ° C. It is obtained in. The following two types of solvent compositions were used for the inks. Details of the definition of the dielectric constant epsilon _r will be described later.

Composition A: 20 wt% glycerin (Gly), large dielectric constant (ε _r = 45)

Composition B: 20 wt% trimethylolpropane (TMP), small relative dielectric constant (ε _r = 30)

Composition B (black dots in FIG. 28) having a relatively low relative dielectric constant from FIG. 28 shows a discharge rate from the first discharge after rest (and then several discharges) compared to composition A (circle in FIG. 28) having a relatively high relative dielectric constant. It can be seen that the change in is relatively smaller. The reason is that the lowering of the dielectric constant makes the aforementioned phenomenon of retraction of the pigment more pronounced. Thus, after rest, a lower relative dielectric constant is desirable in order to reduce the change in the discharge rate from the initial discharge (and then several discharges thereafter).

29A to 29C are graphs showing the ejection rates of three types of inks each having different relative dielectric constants (solvent compositions). Specifically, they are formed with a circulating flow C, the ejection operation is stopped for 10 seconds, and then the ejection rate (the rate at which the average value of the ejection rate after the 20th ejection is taken as 1) is drawn with respect to the ejection count value. Is a graph when these inks are used in the liquid ejecting head having the flow mode A (J = 3.5). The results shown are 12% by weight of solids (pigments, polymers, etc.) in the ink, circulating flow (C) with flow rates of 10 mm / s and 30 mm / s (circulation speed) and head temperature of 55 ° C. Obtained. The solvent composition of the ink is as shown in the table. 29A shows the discharge rate of composition 1, FIG. 29B shows the discharge rate of composition 2, and FIG. 29C shows the discharge rate of composition C. FIG.

Standard Solvent (% by weight) Relative dielectric constant glycerin 2-pyrrolidinone Trimethylol
Propane sum Composition 1 15 5 0 20 45.4 Composition 2 10 5 5 20 40.7 Composition 3 0 5 10 15 33.8

29A-29C were obtained using the liquid discharge head of FIG. 26C with flow mode A (J = 3.5), and the liquid discharge head of FIG. 26B with circulating flow C having flow mode A (J = 2.3). It can be seen that it reaches the outlet interface 24 more easily than. However, in the case where the ink has a high solid concentration (12 wt%), as shown in FIG. 29A, even when the circulation flow rate is high (30 mm / s), at the time of initial discharge after rest in composition 1 having a relatively high relative dielectric constant, The change in the ejection speed is large. Composition 2, having a relative dielectric constant lower than composition 1, is preferred because the change in discharge rate is small as a whole when the circulation flow rate is high (30 mm / s) as illustrated in Fig. 29B. On the other hand, Composition 3, which has a much lower relative dielectric constant, is even more desirable because the change in discharge rate from initial discharge after rest is small even when the circulation flow rate is low (10 mm / s) as illustrated in Fig. 29C. Therefore, with respect to the dielectric constant epsilon _r , epsilon _r <= 40.7 is preferable and epsilon _r <33.8 is more preferable. 28 shows that ε _r ≤ 30.0 is more preferable. When the concentration of the ink solid is high, the viscosity tends to increase, and therefore, the differential pressure necessary to cause the ink flow needs to be increased in order to increase the flow velocity of the circulating flow C. However, this increase in the differential pressure increases the negative pressure applied to the discharge port 13, which has a negative effect on the discharge characteristics. The flow rate of the circulating flow C is preferably lower in this respect, but on the other hand, the slower the flow rate of the circulating flow C, the easier it is for the solids of the ink to stagnate in the discharge port portion 25, and the more the defect discharge is. Occurs easily. However, the change in the ejection speed of the initial ejection after rest is increased in the crystal mode J in the flow mode A, and also by lowering the relative dielectric constant of the ink so as to cause the retreat phenomenon of the pigment, in the case of lower circulation rate Even lower levels can be suppressed.

Explanation of influence of relative dielectric constant of degraded ink

The relative dielectric constant epsilon _r of the ink is defined by the following equation, and is used herein as an integer value rounded off a fractional part.

(5)

(5)

In the above formula (5), n represents the type of water-soluble organic solvent, ε _n represents the relative dielectric constant of the water-soluble organic solvent represented by n, and r _n is a water-soluble organic solvent represented by n with respect to the total ink mass. It is the physical characteristic value excluding water. In this case, the region concentrated by the circulating flow C can be considered to have a small amount of water due to evaporation, so that a water-soluble organic solvent excluding water is used as the physical property value of the liquid in the concentrated region.

The relative dielectric constant ε _n defined by the above equation (5) represents the relative dielectric constant of the entire "aqueous medium" composed of a water-soluble organic solvent in the ink, and is specifically a value calculated as follows. The values obtained by multiplying the relative dielectric constant (dimensionless number) inherent to the water-soluble organic solvent by the content in the ink of this component (content of the total mass of the ink in mass%) with respect to the component are added together, and the whole is water-soluble organic. The relative dielectric constant can be measured by a general permittivity meter, the water content in the ink can be found by Karl Fischer titration, etc., and the content of water-soluble organic solvent is determined by gas chromatography (GC / MS) or high performance liquid chromatography (LC / MS) or the like.

Inks used in the present disclosure may include various types of additives as needed. Examples of such additives include surfactants, pH adjusters, antifoams, rust inhibitors, preservatives, antioxidants, reduction inhibitors, evaporation promoters, chelating agents and the like. The content of these additives in the ink is very small and, therefore, does not necessarily have to be taken into account in the calculation of the dielectric constant.

Explanation of the relationship between the presence / absence of circulating flow in the pressure chamber and the lowering of the dielectric constant of the ink

Even in a configuration in which no circulating flow C is formed in the pressure chamber 23, a porous medium may be used as the ink solvent composition to reduce the dielectric constant. However, in the case of inks with more solids such as pigments, the relative dielectric constant of the ink is less likely to be lowered due to the following two damages in the configuration in which no circulating flow C is produced in the pressure chamber 23.

In a configuration in which no circulating flow C is produced, the pigment is concentrated when the ejection operation is stopped for a predetermined time, so that the optical density OD tends to be high with respect to the first landing dot after rest. However, when the relative dielectric constant of the ink is lowered, the phenomenon of retreat of the pigment occurs, so that the OD of the first landing dot after rest becomes lower instead. This is the first loss.

In addition, in a configuration in which no circulating flow C is generated, a good medium having a high relative dielectric constant such as glycerin having a good moisture-holding characteristic as one measure to solve the solidification due to ink evaporation from the discharge port 13 ), There is a method to suppress the solidification due to pigment concentration. In addition, there is a method in which pigment concentration is less likely to occur using an empty medium having a low relative dielectric constant in order to cause the pigment retreat, thereby suppressing solidification. However, excessively accelerating the occurrence of the pigment retreat phenomenon, i.e., excessively promoting the lowering of the dielectric constant, leads to solidification of the pigment that has been retracted in the pressure chamber 23. This makes it difficult to significantly reduce the dielectric constant. This is the second loss.

These two damages can be avoided by creating a circulating flow C in the pressure chamber 23, and to make the decision value J larger in the flow mode A can be added thereto. That is, in the state where the circulating flow C is generated, in particular, in the state in which ink flows through the discharge port 25 as the flow mode A, regardless of whether or not the retreat phenomenon of the pigment occurs, OD does not change easily. Therefore, ink having a lower relative dielectric constant can be used, and stagnation of the ink near the periphery of the ejection opening 13 can be suppressed. Irrespective of whether or not the receding phenomenon of the high-definition pigment in the discharge port portion 25 and the pressure chamber 23 occurs, an ink having a lower relative dielectric constant can be used. Therefore, the reduction in the dielectric constant of the ink is particularly effective in the configuration in which the circulating flow C is generated in the pressure chamber 23. The present disclosure may apply in particular to flow mode A, but may also apply to flow mode B when circulating flow C occurs.

Thus, according to the present disclosure, a liquid ejecting apparatus and a liquid ejecting head capable of forming high resolution and high quality images can be provided.

While the invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims (17)

Liquid discharge device,
A liquid discharge head having a recording element substrate,
The recording element substrate,
A discharge port configured to discharge the liquid,
A pressure chamber provided therein with a recording element configured to generate energy used to discharge the liquid;
A liquid supply channel configured to supply liquid to the pressure chamber, and
Liquid recovery channel configured to recover liquid from the pressure chamber
And comprising a liquid discharge head,
A flow unit configured to cause liquid to flow in the liquid supply channel, the pressure chamber and the liquid recovery channel in this order,
And a relative dielectric constant (ε _r ) of the liquid flowing through the pressure chamber by the flow unit satisfies a relationship of ε _r ≤ 40.7. The method of claim 1,
And a relative dielectric constant (ε _r ) of the liquid flowing through the pressure chamber satisfies a relationship of ε _r ≤ 33.8. The method of claim 2,
And a relative dielectric constant (ε _r ) of the liquid flowing through the pressure chamber satisfies a relationship of ε _r ≤ 30.0. The method according to any one of claims 1 to 3,
A discharge port portion is formed in communication between the pressure chamber and the discharge port,
The height H of the pressure chamber on the upstream side in the flow direction of the liquid with respect to the communication portion with the discharge port, the length P of the discharge port in the discharge direction of the liquid, and the flow direction of the liquid in the discharge port. Length W to satisfy the relationship of H ^-0.34 x P ^-0.66 x W> 1.7. The method of claim 4, wherein
The height (H) is 20 m or less, the length (P) is 20 m or less, and the length (W) is 30 m or less. The method according to any one of claims 1 to 3,
And a flow rate of the liquid flowing through the pressure chamber is 0.1 to 100 mm / s. The method according to any one of claims 1 to 3,
And the solid component of the liquid is at least 8% by weight. Liquid discharge head,
A discharge port configured to discharge the liquid,
A recording element configured to generate energy used to discharge the liquid,
A pressure chamber having the recording element therein;
A liquid supply channel configured to supply a liquid to the pressure chamber; And
A liquid recovery channel configured to recover liquid from the pressure chamber,
A liquid discharge head in which a liquid having a relative dielectric constant (ε _r ) satisfying a relationship of ε _r ≤ 40.7 circulates through the liquid supply channel, the pressure chamber, and the liquid recovery channel in this order. The method of claim 8,
And the relative dielectric constant ε _{r of the} liquid satisfies the relationship ε _r ≤ 33.8. The method according to claim 8 or 9,
A discharge port portion is formed in communication between the pressure chamber and the discharge port,
The height H of the pressure chamber upstream in the flow direction of the liquid with respect to the communication portion with the discharge port, the length P of the discharge port in the discharge direction of the liquid, and the flow direction of the liquid in the discharge port. Length W to satisfy the relationship of H ^-0.34 x P ^-0.66 x W> 1.7. The method of claim 10,
The height H is 20 m or less, the length P is 20 m or less, and the length W is 30 m or less. The method according to claim 8 or 9,
And a flow rate of the liquid flowing through the pressure chamber is 0.1 to 100 mm / s. The method according to claim 8 or 9,
Wherein the solid component of the liquid is at least 8% by weight. The method according to claim 8 or 9,
A plurality of recording element substrates having recording elements; And
A channel member for supporting the plurality of recording element substrates and for supplying liquid to the plurality of recording element substrates,
And the liquid discharge head is a page-wide liquid discharge head. The method of claim 14,
The channel member,
A common supply channel configured to supply liquid to the plurality of recording element substrates while extending in an array direction in which the plurality of recording element substrates are arranged;
And a common recovery channel configured to recover liquid from the plurality of recording element substrates while extending in the array direction. The method of claim 14,
And a plurality of recording element substrates arranged in a straight line. The method according to claim 8 or 9,
Liquid in the pressure chamber is circulated between the inside of the pressure chamber and the outside of the pressure chamber.

Images