JP7638697B2 - Liquid ejection device - Google Patents

Description

The present invention relates to a liquid ejection device.

Liquid ejection devices are provided with a pressure control mechanism such as a differential pressure valve to manage the pressure of the liquid supplied to the liquid ejection head. For example, the differential pressure valve described in Patent Document 1 uses a compression spring to manage the force required to open the valve (valve opening force).

JP 2010-223259 A

The differential pressure valve described in Patent Document 1 has the advantage that the force required to open the valve can be easily set arbitrarily by using a compression spring, and the configuration can be simplified. However, it is necessary to secure space to accommodate the compression spring inside the differential pressure valve, which increases the dimensions of the differential pressure valve itself, particularly its thickness. In recent years, liquid ejection devices have tended to increase in number of parts and size due to the increasing number of functions, the larger capacity of cartridges (liquid containers), and the use of multiple colors for high-definition recording. However, increasing the size of the liquid ejection device body is undesirable as it leads to increased product costs. Therefore, as mentioned above, it is desirable to prevent the liquid ejection device from becoming larger due to the compression spring of the differential pressure valve.

The object of the present invention is to provide a liquid ejection device that can prevent the device from becoming too large even if it has a valve.

The liquid ejection device of the present invention is a liquid ejection device including an element substrate that ejects liquid, a tank that stores the liquid, a valve that controls the supply of the liquid from the tank to the element substrate, and a flow path forming member that forms a part of a flow path located between the tank and the element substrate , wherein the valve is provided inside the flow path forming member, the valve includes a leaf spring that is integrally formed with a part of the flow path forming member, the flow path forming member is provided with a hole that forms a part of the valve, the flow path forming member includes a valve seat having a metal frame and an elastic member a part of which is fixed to the metal frame, and the valve opens and closes by a part of the elastic member being displaced together with the elastic deformation of the leaf spring to move between a position in contact with the hole and a position away from the hole .

The present invention provides a liquid ejection device that can prevent the device from becoming too large even though it has a valve.

1 is a block diagram illustrating a liquid ejection head of a liquid ejection device according to an embodiment of the present invention. 1 is an exploded perspective view of a liquid ejection head of a liquid ejection device according to an embodiment of the present invention. FIG. 3 is an exploded perspective view of a tank unit of the liquid ejection head shown in FIG. 2 . 4 is a cross-sectional view taken along line AA in FIG. 3. FIG. 3 is an exploded perspective view of a valve unit of the liquid ejection head shown in FIG. 2 . FIG. 6 is a plan view of an upper valve seat of the valve unit shown in FIG. 5 . FIG. 6 is a plan view of a lower valve seat of the valve unit shown in FIG. 5 . FIG. 6 is a perspective view of a metal plate of the valve unit shown in FIG. 5 . 7 is a cross-sectional view taken along line BB in FIG. 6, illustrating a closed state and an open state of the differential pressure valve of the valve unit illustrated in FIG. 5. FIG. 10 is an enlarged plan view of a leaf spring of the differential pressure valve shown in FIG. 8 is a cross-sectional view taken along lines C1-C1 and C2-C2 in FIG. 7. 8 is a cross-sectional view taken along line D-D in FIG. 7. FIG. 3 is an exploded perspective view of a gas flow unit of the liquid ejection head shown in FIG. 2 . FIG. 3 is an exploded perspective view of a liquid flow unit of the liquid ejection head shown in FIG. 2 . FIG. 3 is an exploded perspective view of a discharge module of the liquid discharge head shown in FIG. 2 .

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. However, the following description is not intended to limit the scope of the present invention.
[Description of Liquid Ejection Head]
1 is a block diagram showing the configuration of a liquid ejection head 1 of a liquid ejection device according to an embodiment of the present invention and the flow of liquid. Lines connecting each unit indicate the flow of liquid (flow path), and arrows indicate the direction in which the liquid flows. In FIG. 1, the normal flow of liquid is shown by solid lines, and the flow of liquid when a switching valve 220 is operated is shown by dashed lines.

The liquid ejection head 1 of this embodiment has a tank unit 100, a valve unit 200, a liquid flow unit 300, and an ejection module 400. The ejection module 400 includes an element substrate 401. The element substrate 401 includes an ejection port and an energy generating element (a heat generating resistor element or a piezoelectric element) for generating energy for ejecting liquid such as ink from the ejection port to the outside, not shown. The tank unit 100 includes a tank 101, which is a container for storing liquid. Between the tank 101 and the element substrate 401, the valves 210, 220 and the diaphragm pump 230 of the valve unit 200, and the liquid supply flow path 304 and the liquid return flow path 305 of the liquid flow unit 300 are interposed. Liquid is supplied from the tank 101 to the element substrate 101 via the differential pressure valve 210 and the liquid supply flow path 304 or the liquid return flow path 305. The liquid that is not discharged from the discharge port of the element substrate 401 to the outside returns to the tank 101 via the liquid return flow path 305 or the liquid supply flow path 304, the switching valve 220, and the diaphragm pump 230. A circulation path is formed that connects the tank 101 and the element substrate 401 in this way. In this embodiment, the tank unit 100, the valve unit 200, the liquid flow unit 300, and the discharge module 400 are stacked and integrated, but this configuration is not limited to this. As long as a circulation path is formed between the tank 101 and the element substrate 401, the arrangement of each unit is free, and for example, it is possible to arrange the units at separate positions without contacting each other.

[Explanation of the valve unit]
The valve unit 200 includes a diaphragm pump 230 , two switching valves 220 , and two differential pressure valves 210 .
(Diaphragm pump)
The diaphragm pump 230 supplies the liquid contained in the tank 101 to the element substrate 401 of the ejection module 400, and generates a flow of liquid that returns the liquid from the element substrate 401 to the tank 101. Such a flow of liquid (circulation flow) is generated when the diaphragm pump 230 operates to generate a pressure difference in the liquid. That is, the diaphragm pump 230 functions as a circulation pump. In this embodiment, three diaphragm pumps 230 are provided for one type (one color) of liquid. However, in FIG. 1, the three diaphragm pumps 230 are shown as a single schematic diagram. By driving the diaphragm pumps 230 with the phases shifted, the variation in the flow rate of the liquid is suppressed. The detailed structure of the diaphragm pump 230 will be described later.

(Switching valve)
The switching valve 220 includes a switching valve 221 that is normally open (normally open) and a switching valve 222 that is normally closed (normally closed). When the normally open switching valve 221 is open and the normally closed switching valve 222 is closed, a circulation path connecting the tank 101 and the element substrate 401 is formed. The circulation direction of the liquid in this state is referred to as the forward direction. When the normally open switching valve 221 is closed and the normally closed switching valve 222 is opened, another circulation path connecting the tank 101 and the element substrate 401 is formed. The circulation direction of the liquid in this state is opposite to the forward direction, and is referred to as the reverse direction.

The function of the switching valve 220 will be described. When the liquid ejection device is used for the first time, or when it is used after a long period of non-use, air bubbles may be present in the liquid flow path of the liquid ejection head 1. If liquid is ejected in this state, air bubbles may get into the ejection port of the element substrate 401, causing ejection failure. Therefore, the liquid ejection head 1 of this embodiment generates a reverse circulation flow of liquid at a specific timing, such as when the liquid ejection device is first used or after ejecting a predetermined amount or time of liquid, to move air bubbles away from the ejection port and its vicinity. In this way, the switching valve 220 is provided to switch between the forward circulation flow of liquid and the reverse circulation flow of liquid. The detailed structure of the switching valve 220 will be described later.

(Differential pressure valve)
In the liquid ejection head 1, if the pressure of the liquid supplied to the ejection module 400 is not properly managed, the liquid may leak from the ejection port (not shown) of the element substrate 401. Therefore, in order to properly manage the pressure of the liquid and prevent the liquid from leaking, a differential pressure valve 210 is provided between the tank 101 and the element substrate 401. The differential pressure valve 210 is structured to open when the difference between the pressure of the liquid on the tank unit 100 side and the pressure of the liquid on the liquid flow unit 300 side that supplies the liquid to the element substrate 401 becomes equal to or greater than a certain level. When the liquid is ejected from the element substrate 401 and consumed, the amount of liquid in the liquid flow unit 300 decreases and the pressure drops. When the pressure difference between the upstream and downstream of the differential pressure valve 210 reaches a certain value or more, the differential pressure valve 210 opens and the liquid is supplied. In this way, in this embodiment, the differential pressure valve 210 is used, and the liquid is not supplied to the element substrate 401 unless an appropriate pressure is reached.

Furthermore, as shown in FIG. 1, two types of differential pressure valves 210 are provided in this embodiment, namely, a weak pressure differential valve 211 and a strong pressure differential valve 212. These two differential pressure valves have different pressure differences that are the thresholds at which the valves open. Normally, liquid is supplied to the element substrate 401 through the weak pressure differential valve 211, which requires a small pressure difference to open the valve. However, for example, when printing a printed material that consumes a large amount of liquid, the pressure difference of the liquid becomes large, so not only the weak pressure differential valve 211 but also the strong pressure differential valve 212 is opened to supply liquid to the element substrate 401 from the two differential pressure valves 211, 212.

The differential pressure valve 210 of this embodiment is provided with a biasing member having an appropriate biasing force in order to appropriately set the pressure difference that serves as the threshold for opening and closing. This biasing member is made of a leaf spring formed integrally with the flow path forming member, which allows the differential pressure valve to have a small and simple structure. The specific structure of such a differential pressure valve 210 will be described later. Note that in this embodiment, the differential pressure valve 210 is provided inside the liquid ejection head 1, but the position of the differential pressure valve 210 can be changed as desired. For example, the differential pressure valve 210 may be disposed outside the liquid ejection head 1.

(Circulating flow of liquid)
The liquid is circulated in the liquid ejection head 1 by the above-described configuration. Normally, the liquid in the tank 2 flows to the element substrate 401 through the weak pressure differential valve 211 and the liquid supply flow path 304 by the operation of the diaphragm pump 230. Furthermore, the liquid returns to the tank 101 from the element substrate 401 through the liquid reflux flow path 305 and the normally open switching valve 221. In this way, a forward circulation flow of the liquid (shown by a solid line in FIG. 1) is generated. As described above, when bubbles are generated in the flow path, for example, in the liquid supply flow path 304 or in the flow path of the element substrate 401, the liquid circulation direction is changed to move the bubbles to a position away from the element substrate 401. That is, the normally open switching valve 221 is closed and the normally closed switching valve 222 is opened. As a result, the liquid in the tank 2 flows to the element substrate 401 through the strong pressure differential valve 212 and the liquid reflux flow path 305 by the operation of the diaphragm pump 230. The liquid further returns to the tank 101 from the element substrate 401 through the liquid supply flow path 304 and the normally closed switching valve 222. In this way, a circulating flow of liquid in the reverse direction (shown by the dashed line in FIG. 1 ) is generated. By reversing the inflow direction of the liquid into the element substrate 401, for example, air bubbles remaining in the element substrate 401 are discharged to the outside of the element substrate 401.

The above explanation concerns the configuration for the flow of one type (one color) of liquid, and in a liquid ejection head 1 that ejects multiple liquids of different types and colors, the above-mentioned configuration is provided for each type (color) of liquid.

[Example of Liquid Ejection Head]
A more detailed embodiment of the liquid ejection head 1 of the present invention will be specifically described. FIG. 2 is an exploded perspective view of the liquid ejection head 1 of this embodiment. The liquid ejection head 1 of this embodiment is an inkjet recording head capable of color recording, ejecting four color liquids (e.g., cyan, magenta, yellow, and black inks). This liquid ejection head 1 has a tank unit 100, a valve unit 200, a gas flow unit 500, a liquid flow unit 300, and an ejection module 400. The liquid ejection head 1 of this embodiment has a structure in which these units are stacked and integrated, but is not limited to such a structure. At least one of the units may be disposed at a separate position.

(Tank unit)
FIG. 3 shows an exploded perspective view of the tank unit 100 of this embodiment. FIG. 4 is a cross-sectional view of line A-A in FIG. 3. The tank unit 100 has a configuration in which a hollow tank block 103 is sandwiched between a tank cover 102 and a plate 104. The tank block 103 has a configuration in which a plurality of tanks (liquid storage portions) 101 (four in this embodiment) and a liquid supply portion 106 are integrated, and the plurality of tanks 101 and the liquid supply portion 106 are collectively blocked by the tank cover 102. The tank cover 102 is provided with an external supply port 105 that communicates with the liquid supply portion 106. A tube connected to a cartridge (not shown) is connected to the external supply port 105. The liquid supplied from the cartridge to the liquid supply portion 106 through the tube and the external supply port 105 is introduced into the tank 101 through a flow path provided between the tank block 103 and the plate 104.

An opening/closing valve 108 is provided inside the tank 101. The opening/closing valve 108 is welded to a flexible film 110 provided inside the tank 101, and is located opposite a liquid supply port 111 and a liquid discharge port 112 provided in the tank block 103. The opening/closing valve 108 is biased by a coil spring 109 in a direction away from the liquid supply port 111 and the liquid discharge port 112. The liquid supply port 111 is in communication with a differential pressure valve 210 in the valve unit 200. The liquid discharge port 112 is in communication with a diaphragm pump 230 in the valve unit 200.

The liquid ejection device body or a component mounted on the device body presses the opening/closing valve 108 from above, thereby closing the liquid supply port 111 and the liquid discharge port 112 as shown in FIG. 4. When the device is first used, the liquid supply port 111 and the liquid discharge port 112 are closed, and the tank 101 is suctioned through the communication port 113 (see FIG. 3) of the tank cover 102. When the tank 101 is suctioned, the flexible film 110 welded to the opening/closing valve 108 deforms, and the pressure in the space inside the flexible film 110 decreases. This pressure decrease causes liquid to flow into the liquid supply section 106 from the cartridge (not shown) through the external supply port 105, and is then led to the tank 101. After the liquid flows into the tank 101, the connection path with the cartridge is closed, completing the supply of liquid to the liquid ejection head 1. Thereafter, when the pressure on the opening and closing valve 108 is released, the coil spring 109 separates the opening and closing valve 108 from the liquid supply port 111 and the liquid discharge port 112, opening the liquid supply port 111 and the liquid discharge port 112 and allowing the liquid to circulate.

(Valve unit)
FIG. 5 is an exploded perspective view of the valve unit 200. The valve unit 200 is a laminate of a lower valve seat 202, a thin metal plate 203, and an upper valve seat 201, and includes the differential pressure valve 210, the switching valve 220, and the diaphragm pump 230 shown in FIG. 1. An enlarged plan view of the upper valve seat 201 is shown in FIG. 6, and an enlarged plan view of the lower valve seat 202 is shown in FIG. 7. A perspective view of the metal plate 203 from below is shown in FIG. 8. The upper valve seat 201 and the lower valve seat 202 of this embodiment are insert molded products of a thin metal frame 204 and an elastic member 205. The metal frame 204 of this embodiment is made of stainless steel (SUS304) having a thickness of 0.1 mm. The elastic members 205 formed on the front and back of the metal frame 204 are each made of EPDM (ethylene propylene diene rubber) having a thickness of 0.5 mm. An opening 206 is provided in the upper valve seat 201 and the lower valve seat 202, and a rib 207 is formed on the inner periphery of the opening 206. When the upper valve seat 201 and the lower valve seat 202 are sandwiched from the front and back by other members and compressed, the opening 206 is sealed by the rib 207 to become a flow path through which liquid passes. A joint 208 is formed in the upper valve seat 201, and this joint 208 functions as a check valve that constitutes a part of the diaphragm pump 230. In addition, the upper valve seat 201 and the lower valve seat 202 are formed with windmill-shaped leaf springs 213a, 213b, 214a, 214b, 215a, 215b, and 216 that constitute a part of the differential pressure valve 210 and the switching valve 220. The upper valve seat 201 and the lower valve seat 202 shown in Figures 6 and 7 are provided with flow paths for two types (two colors) of liquid. The flow paths for the liquids of each color are arranged point-symmetrically about the center of the upper valve sheet 201 and the lower valve sheet 202. Two pairs of the upper valve sheet 201 and the lower valve sheet 202 are provided to form flow paths for circulating the liquids of four colors.

The metal plate 203 shown in FIG. 8 is made of stainless steel (SUS304) with a thickness of 1.0 mm. Flow paths corresponding to the nodes 208 and the windmill-shaped leaf springs 213a, 213b, 214a, 214b, 215a, 215b, and 216 described above are formed in the metal plate 203 by etching. The upper valve sheet 201 and the lower valve sheet 202 are stacked so as to sandwich the metal plate 203, forming the differential pressure valve 210, the switching valve 220, and the diaphragm pump 230.

(Differential pressure valve)
The configuration of the differential pressure valve of this embodiment will be described in more detail. When the parts A1 to A4 of the upper valve seat 201 shown in FIG. 6 are laminated with the metal plate 203 and the lower valve seat 202, a differential pressure valve 210 is configured. The configuration of one differential pressure valve 211 of the differential pressure valve 210 is shown in FIG. 9, which is a cross-sectional view of line B-B in FIG. 6. FIG. 9(a) shows the differential pressure valve 211 in a closed state, and FIG. 9(b) shows the differential pressure valve 211 in an open state. Although FIG. 9 shows only one differential pressure valve 211, the other differential pressure valve 212 has substantially the same configuration. The one differential pressure valve 211 of this embodiment is a weak pressure differential pressure valve, and has a smaller valve opening force (force required to open the valve) than the other differential pressure valve 212, which is a strong pressure differential pressure valve.

In this embodiment, the valve unit 200 is sandwiched between the plate 104 of the tank unit 100 and the upper gas flow block 503 of the gas flow unit 500 described later. The upper valve seat 201 of the valve unit 200, which is one of the flow path forming members that form the liquid flow path, is integrally formed with the metal frame 204 with a leaf spring 213a for the differential pressure valve. Similarly, the lower valve seat 202, which is one of the flow path forming members, is integrally formed with the metal frame 204 with a leaf spring 213b for the differential pressure valve. A metal pin 217 is arranged to penetrate a hole 203a provided in a metal plate 203 located between the upper valve seat 201 and the lower valve seat 202. As an example of the metal pin 217, a pin made of stainless steel (SUS304) with a diameter of 1.0 mm and a length of 2.3 mm is used. Metal pin 217 is held by metal pin support 209 with one end abutting leaf spring 213a and the other end abutting leaf spring 213b. Thus, metal pin 217 is held from above and below by leaf spring 213a integrally provided with upper valve seat 201 and leaf spring 213b integrally provided with lower valve seat 202. Leaf spring 213a of upper valve seat 201 and leaf spring 213b of lower valve seat 202 face each other with metal pin 217 in between. In this way, differential pressure valve 211 is constructed.

In the state shown in FIG. 9(a), the metal pin support 209 supporting one end of the metal pin 217 blocks the hole 203a of the metal plate 203 from above. Therefore, the liquid located on the upper valve seat 201 side does not flow through the hole 203a of the metal plate 203 to the lower valve seat 202 side, and the differential pressure valve 211 is in a closed state.

9(a), the leaf spring 213a and metal pin 217 of the upper valve seat 201 and the leaf spring 213b of the lower valve seat 202 move upward, i.e., toward the tank unit 100, as a unit. Then, as shown in FIG. 9(b), the metal pin support 209 supporting one end of the metal pin 217 moves away from the hole 203a of the metal plate 203, and at least a part of the hole 203a is opened. As a result, the liquid located on the upper valve seat 201 side flows through the hole 203a of the metal plate 203 to the lower valve seat 202 side, and the differential pressure valve 211 is in an open state. In this way, the opening and closing operation of the differential pressure valve 211 shown in FIG. 9(a) and 9(b) is performed. The opening and closing of this differential pressure valve 211 is performed by the integral movement of the leaf spring 213a of the upper valve seat 201, the metal pin 217, and the leaf spring 213b of the lower valve seat 202. The integral movement of these members is caused by the pressure difference between the space on the upper valve seat 201 side and the space on the lower valve seat 202 side as viewed from the metal plate 203. This point will be explained in more detail.

The leaf springs 213a and 214a of the upper valve seat 201 shown in FIG. 6 are enlarged and shown in FIG. 10. The leaf spring 213a has a windmill-like planar shape, that is, it consists of three serpentine parts that extend from three points on the circumference of a circle to the center of the circle while serpentine in the same way, and join at the center of the circle. The leaf spring 213a constituting a part of the low pressure differential pressure valve 211 has a narrow serpentine part and low rigidity, whereas the leaf spring 214a constituting a part of the high pressure differential pressure valve 212 has a wide serpentine part and high rigidity. The lower valve seat 202 shown in FIG. 7 also has leaf springs 213b and 214b with serpentine parts of a similar shape. The leaf spring 213b constituting a part of the low pressure differential pressure valve 211 has a narrow serpentine part and low rigidity, whereas the leaf spring 214b constituting a part of the high pressure differential pressure valve 212 has a wide serpentine part and high rigidity. Furthermore, the leaf spring 213a of the upper valve seat 201 has a wider meandering portion and is more rigid than the leaf spring 213b of the opposing lower valve seat 202. Similarly, the leaf spring 214a of the upper valve seat 201 has a wider meandering portion and is more rigid than the leaf spring 214b of the opposing lower valve seat 202.

The gap between the serpentine portions of the leaf springs 213a, 214a of the upper valve seat 201 is part of the opening 206 and serves as a flow path for liquid. The leaf springs 213b, 214b of the lower valve seat 202 are formed on top of the elastic member 205, and when the leaf springs are elastically deformed, the elastic member 205 is also displaced accordingly. In addition, the gap between the serpentine portions of the leaf springs 213b, 214b of the lower valve seat 202 is blocked by the elastic member 205 and does not serve as a flow path for liquid.

The operating principle of the differential pressure valve 211 with this configuration is as follows. Since the rigidity of the leaf spring 213a of the upper valve seat 201 is higher than the rigidity of the leaf spring 213b of the lower valve seat 202, the leaf spring 213a of the upper valve seat 201 is usually in a nearly horizontal position. As a result, as shown in FIG. 9(a), the metal pin support portion 209 of the upper valve seat 201 abuts against and blocks the hole portion 203a of the metal plate 203, and the differential pressure valve 211 is in a closed state.

In this state, when liquid is discharged from the element substrate 401 and the amount of liquid decreases, the pressure in the liquid flow path of the discharge module 400, the liquid flow unit 300, and the gas flow unit 500 decreases. At this time, in the valve unit 200, the leaf spring 213b on the lower valve seat 202 side is elastically deformed in a convex shape toward the metal plate 23 side due to the negative pressure in the liquid flow path inside the lower valve seat 202. The metal pin 217 connected to the lower valve seat 202 and the upper valve seat 201 are also deformed in a convex shape toward the tank unit 100 side integrally with the lower valve seat 202. As a result, the metal pin support portion 209 of the upper valve seat 201 is displaced away from the hole portion 203a of the metal plate 203, the hole portion 203a is opened, and the liquid flows from the upper valve seat 201 side to the lower valve seat 202 side through the hole portion 203a. That is, the differential pressure valve 211 is in an open state as shown in FIG. 9(b). In this embodiment, the pressure drop in the liquid flow path of the discharge module 400, the liquid flow unit 300, and the gas flow unit 500 due to liquid discharge acts as a suction force that creates a negative pressure in the liquid flow path inside the lower valve seat 202. That is, the liquid flow path of the discharge module 400, the liquid flow unit 300, and the gas flow unit 500, whose pressure drops due to liquid discharge, acts as a suction mechanism. In this way, when the differential pressure valve 211 opens and liquid flows from the upper valve seat 201 side to the lower valve seat 202 side through the hole 203a, the reduced pressure on the lower valve seat 202 side returns to its original state. As a result, the force pushing up the leaf spring 213b of the lower valve seat 202 decreases, the leaf spring 213b descends to the gas flow unit 500 side, and the metal pin support portion 209 of the upper valve seat 201 closes the hole 203a of the metal plate 203 again. In this way, the differential pressure valve 211 closes.

As mentioned above, the force required to push the leaf spring 213b of the lower valve seat 202 toward the tank unit 100 so as to move the metal pin support portion 209 of the upper valve seat 201 away from the hole portion 203a of the metal plate 203 is called the valve opening force. In order for the differential pressure valve 211 to open, the force generated by the pressure difference between the flow path on the upper valve seat 201 side and the flow path on the lower valve seat 202 side must overcome the force of the leaf springs 213a and 213b. Therefore, the opening force of the differential pressure valve 211 is determined by the rigidity of the leaf springs 213a and 213b. The strong pressure differential pressure valve 212 has substantially the same configuration as the weak pressure differential pressure valve 211 shown in FIG. 9. However, the strong pressure differential pressure valve 212 has a higher rigidity of the leaf springs 214a and 214b and a larger opening force than the weak pressure differential pressure valve 211. Therefore, when the weak pressure differential valve 211 is closed as shown in FIG. 9A, the strong pressure differential valve 212, which does not open unless there is a pressure difference larger than that of the weak pressure differential valve 211, is also closed. Since the differential pressure valve 212 is closed, the flow of liquid from the tank unit 100 to the gas flow unit 500 via the valve unit 200 is blocked. From this state, when the pressure difference increases and the weak pressure differential valve 211 opens as shown in FIG. 9B, the strong pressure differential valve 212 remains closed, and liquid flows to the discharge module 400 side through only the weak pressure differential valve 211. When the pressure difference further increases and the strong pressure differential valve 212 opens together with the weak pressure differential valve 211, a large amount of liquid flows to the discharge module 400 side through both the differential pressure valves 211 and 212. In this way, the pressure of the liquid on the gas flow unit 500 side is maintained lower than the pressure on the tank unit 100 side, which is subjected to atmospheric pressure, so that the liquid is replenished after the liquid is discharged from the element substrate 401.

In this embodiment, the differential pressure valve 210 has leaf springs 213a, 213b, 214a, and 214b instead of compression springs, so that the differential pressure valve 210 can be made thinner. In the differential pressure valve 210 of this embodiment, the thickness of the upper valve seat 201 is 1.1 mm, the thickness of the lower valve seat 202 is 1.1 mm, and the thickness of the metal frame 204 is 1.0 mm, so that the total thickness of the differential pressure valve 210 is 3.2 mm. In addition, the leaf springs 213a, 213b, 214a, and 214b are integrally formed with the metal frame 204 of the valve unit 200, which is a flow path forming member that forms a liquid flow path, so that the number of parts that constitute the differential pressure valve 210 can be reduced. Furthermore, because the leaf spring is integrally formed with the metal frame 204, multiple differential pressure valves 210 can be assembled simultaneously simply by stacking the upper valve seat 201, the metal plate 203, and the lower valve seat 202 and inserting the metal pin 217 into the metal pin support portion 209. Moreover, multiple differential pressure valves 210 can be positioned with high positional accuracy.

(Switching valve)
The configuration of the switching valve of this embodiment will be described in more detail. When the portions B1 to B4 of the lower valve seat 202 shown in Fig. 7 are laminated with the metal plate 203 and the upper valve seat 201, the switching valve is configured. The normally open switching valve 221 in the normal state is shown typically in Fig. 11(a), which is a cross-sectional view taken along the line C1-C1 in Fig. 7, and the normally closed switching valve 222 in the normal state is shown typically in Fig. 11(b), which is a cross-sectional view taken along the line C2-C2 in Fig. 7.

The leaf springs 215a and 215b for the switching valve 221 are formed integrally with the metal frame 204 on the upper valve seat 201 and the lower valve seat 202 of the valve unit 200, which is a flow path forming member. The leaf springs 215a and 215b for the switching valve 221 have a windmill-like planar shape consisting of three serpentine parts similar to the leaf spring 213a. A metal pin 218 for the switching valve 221 is arranged so as to penetrate the hole 203a provided in the metal plate 203. The metal pin 218 for the switching valve 221 is longer than the metal pin 217 for the differential pressure valve 210. The metal pin 218 is held by the metal pin support part 209 with one end abutting against the leaf spring 215a and the other end abutting against the leaf spring 215b. The leaf spring 215a of the upper valve seat 201 and the leaf spring 215b of the lower valve seat 202 face each other across the metal pin 218. This is how the normally open switching valve 221 is constructed. Since the normally open switching valve 221 uses a long metal pin 218, the leaf spring 215a of the upper valve seat 201 is always pushed up by the metal pin 218. Therefore, the switching valve 221 is always open and liquid flows through the switching valve 221.

The lower surface of the leaf spring 215b of the lower valve seat 202 is formed with a recess that forms a flow path between the leaf spring 215b and the gas flow unit 500. By sucking from the flow path on the gas flow unit 500 side with a suction mechanism, for example, an air pump 219 mounted on the liquid discharge device main body (not shown), the leaf spring 215b and the metal pin 218 of the lower valve seat 202 move to the gas flow unit 500 side (lower side). As a result, the metal pin support part 209 of the upper valve seat 201 closes the hole part 203a of the metal plate 203, and the switching valve 221 closes. In this way, the opening and closing operation of the normally open switching valve 221 shown in FIG. 11(a) is performed.

The normally-closed switching valve 222 shown in FIG. 11(b) includes a leaf spring 216 for the switching valve 222 formed integrally with the metal frame 204 of the lower valve seat 202. The leaf spring 216 for the switching valve 222 also has a windmill-like planar shape consisting of three serpentine portions, similar to the leaf spring 213a. A part of the elastic member 205 of the lower valve seat 202 is located on the surface of the metal plate 203 near the center of the leaf spring 216. Under normal circumstances, the leaf spring 216 maintains a nearly horizontal position, and the elastic member 205 near the center of the leaf spring 216 contacts the metal plate 203 to block the hole 203a of the metal plate 203. In other words, the normally-closed switching valve 222 is closed.

As with the normally open switching valve 221, the underside of the leaf spring 216 for the normally closed switching valve 222 also has a recess that forms a flow path between the leaf spring 216 and the gas flow unit 500. The leaf spring 216 moves to the gas flow unit 500 side (lower side) by sucking air from the flow path on the gas flow unit 500 side with a suction mechanism, for example, an air pump 219 mounted on the liquid discharge device main body (not shown). As a result, the elastic member 205 located near the center of the leaf spring 216 moves away from the metal plate 203, opening the hole 203a of the metal plate 203. That is, the normally closed switching valve 222 opens. In this way, the opening and closing operation of the normally closed switching valve 222 shown in FIG. 11(b) is performed.

As described above, the flow paths formed between the lower surfaces of the leaf springs 215b, 216 and the gas flow unit 500 for operating the normally open switching valve 221 and the normally closed switching valve 222 each constitute a part of the same flow path. By sucking from the flow path on the gas flow unit 500 side with a suction mechanism, for example, an air pump 219 mounted on the liquid discharge device main body (not shown), the normally open switching valve 221 changes from an open state to a closed state. At the same time, the normally closed switching valve 222 changes from a closed state to an open state. Furthermore, the aforementioned low pressure differential valve 211 is also arranged on this same flow path, and by sucking with the air pump 219, the function of the low pressure differential valve 211 stops and the liquid flow switches to the one shown by the dashed line in FIG. 1.

(Diaphragm pump)
The configuration of the diaphragm pump 230 of this embodiment will be described. When the portion C of the lower valve sheet 202 shown in FIG. 7 is laminated with the metal plate 203 and the upper valve sheet 201, the diaphragm pump 230 is configured. This diaphragm pump 230 is shown in FIG. 12, which is a cross-sectional view of line D-D in FIG. 7. A diaphragm 231 constituting the diaphragm pump 230 is formed on the lower valve sheet 202. When sucked from the suction portion 501 of the gas flow unit 500 located below the lower valve sheet 202, the diaphragm 231 deforms and functions as a pump that pumps out liquid. Note that check valves are arranged before and after the diaphragm pump 230 in the flow path formed in the valve unit 200, so that the diaphragm pump 230 can pump the liquid without causing it to flow backward. In this embodiment, three diaphragms 231 are formed for one type (one color) of liquid. Therefore, the lower valve seat 202 shown in FIG. 7 is provided with six portions, including the portion C, which constitute the diaphragm pump 230 in the same manner as the portion C.

(Gas Flow Unit)
13, the gas flow unit 500 is mainly composed of an upper gas flow block 503 and a lower gas flow block 504 bonded together, and is disposed so as to abut against the rear surface of the lower valve seat 202. The surface of the gas flow unit 500 that abuts against the lower valve seat 202 is formed with a concave receiving portion that allows deformation of the diaphragm 231, the leaf springs 213b and 214b for the differential pressure valve, and the leaf springs 215b and 216 for the switching valve. Inside the gas flow unit 500, a flow path for gas suction is formed between the upper gas flow block 503 and the lower gas flow block 504. The gas flow unit 500 has a cone-shaped suction portion 501 located below the diaphragm 231 as described above. When the suction port 502 of the flow path is sucked by a suction mechanism, for example, an air pump 219 mounted on the liquid ejection device main body (not shown), a suction force is transmitted from the flow path and the suction unit 501 to the diaphragm 231, causing the diaphragm 231 to deform. As a result, the diaphragm pump 230 is operated as described above. In addition, the leaf springs 213b and 214b for the differential pressure valve and the leaf springs 215b and 216 for the switching valve are deformed together with the diaphragm 231 by suction from the suction port 502, and the differential pressure valve 210 and the switching valve 220 are opened and closed as described above. In this way, the operation of the diaphragm pump 230, the differential pressure valve 210, and the switching valve 220 can be controlled simultaneously by suctioning gas, particularly by operating one air pump 219, so that the operation efficiency is good and the configuration can be simplified.

(Liquid Flow Unit)
As shown in FIG. 14, which is an exploded perspective view, the liquid flow unit 300 mainly includes a liquid flow block 301, a support block 302, and a rubber sheet 303. The liquid flow block 301 is formed with a flow path having a length corresponding to the discharge module 400, that is, the liquid supply flow path 304 and the liquid return flow path 305 shown in FIG. 1. This liquid flow block 301 serves to supply the liquid that has passed through the differential pressure valve 210 of the valve unit 200 to the element substrate 401 of the discharge module 400. The rubber sheet 303 is disposed so as to contact the upper surface of the liquid flow block 301, and seals the flow paths so that there is no leakage of liquid. The rubber sheet 303 in this embodiment is made of a silicon material having a thickness of 0.5 mm. The lower part of the liquid flow block 301 is inserted into a recess in the support block 302. The support block 302 is made of a material having a higher rigidity and a smaller linear expansion than the liquid flow block 301, for example, an aluminum alloy such as A5052 or a stainless steel material. Each unit and the discharge module 400 are disposed with the support block 302 as a reference.

(Discharge module)
15 , which is an exploded perspective view, an element substrate 401 capable of ejecting a plurality of types of liquid, and an electric wiring member 402 for driving the element substrate 401 are arranged on a support plate 403 of the ejection module 400 of this embodiment. A seal member 404 is arranged so as to abut against the element substrate 401 on the liquid flow unit 300 side, and the seal member 404 is fixed to the support block 302.

In this embodiment, the differential pressure valve 210, which is a valve that controls the supply of liquid from the tank 101 to the element substrate 401, is provided inside the valve unit 200, which is a flow path forming member that forms part of the flow path located between the tank 101 and the element substrate 401. This differential pressure valve 210 includes leaf springs 213a, 213b, 214a, and 214b formed integrally with the metal frame 204, which is part of the valve unit 200, as biasing members. The leaf springs 213a, 213b, 214a, and 214b are elastically deformed by the suction force or pressure force applied to the valve unit 200. The valve unit 200 is provided with a hole 203a that constitutes part of the differential pressure valve 210. The differential pressure valve 210 opens and closes when a part of the elastic member 205 of the valve seats 201, 202 of the valve unit 200 is displaced with the elastic deformation of the leaf spring and moves between a position in contact with the hole 203a and a position away from the hole 203a. With this configuration, the differential pressure valve 210 can be made thinner than a configuration having a compression spring as a biasing member, for example, and the number of parts that make up the differential pressure valve 210 can be reduced. Furthermore, the differential pressure valve 210 can be easily constructed with good positional accuracy.

A switching valve 220 that determines the circulation direction of the liquid is also provided inside the valve unit 200, and it is preferable that the switching valve 220 also includes leaf springs 215a, 215b, and 216 formed integrally with the metal frame 204 that is part of the valve unit 200 as a biasing member.

In the liquid ejection device of the present invention, the element substrate 401 and the valve unit 200, which is a flow path forming member, are directly or indirectly laminated to form the liquid ejection head 1. Furthermore, a liquid flow unit 300 having a liquid supply flow path 304 and a liquid reflux flow path 305 may be provided between the valve unit 200 and the element substrate 401. In that case, the differential pressure valve 210 is connected to the liquid supply flow path 304 or the liquid reflux flow path 305. In addition, a gas flow unit 500 that generates a suction force or a pressure force for operating the differential pressure valve 210 may be provided between the valve unit 200 and the element substrate 401. The tank unit 100 including the tank 101 may be directly or indirectly laminated on the element substrate 401 and the valve unit 200 to form the liquid ejection head. However, this configuration is not limited to this, and it is also possible to omit any of the units or to arrange them outside the liquid ejection head, which is a laminate.

101 Tank 200 Valve unit (flow path forming member)
210, 211, 212 Differential pressure valve (valve)
213a, 213b, 214a, 214b Leaf spring 401 Element substrate

Claims (17)

A liquid ejection device including: an element substrate that ejects liquid; a tank that stores the liquid; a valve that controls supply of the liquid from the tank to the element substrate; and a flow path forming member that forms a part of a flow path located between the tank and the element substrate ,
the valve is provided inside the flow passage forming member, and the valve includes a leaf spring formed integrally with a part of the flow passage forming member,
the flow passage forming member is provided with a hole that constitutes a part of the valve,
the flow passage forming member includes a valve seat having a metal frame and an elastic member a portion of which is fixed to the metal frame,
The liquid ejection device according to claim 1, wherein the valve opens and closes when a portion of the elastic member is displaced with elastic deformation of the leaf spring and moves between a position in contact with the hole and a position away from the hole . A liquid ejection device including: an element substrate that ejects liquid; a tank that stores the liquid; a valve that controls supply of the liquid from the tank to the element substrate; and a flow path forming member that forms a part of a flow path located between the tank and the element substrate,
the valve is provided inside the flow passage forming member, and the valve includes a leaf spring formed integrally with a part of the flow passage forming member,
The valve is a differential pressure valve, and the valve opening force is determined by the leaf spring.
A liquid ejection device comprising at least two of the differential pressure valves, one of the differential pressure valves having a smaller valve opening force than the other of the differential pressure valves. A liquid ejection device including: an element substrate that ejects liquid; a tank that stores the liquid; a valve that controls supply of the liquid from the tank to the element substrate; and a flow path forming member that forms a part of a flow path located between the tank and the element substrate,
the valve is provided inside the flow passage forming member, and the valve includes a leaf spring formed integrally with a part of the flow passage forming member,
a circulation pump for generating a circulating flow of the liquid passing through the flow path forming member between the tank and the element substrate; 4. The liquid ejection device according to claim 1, wherein the valve is a differential pressure valve, and the valve opening force is determined by the leaf spring. The liquid ejection device according to claim 4, which has at least two of the differential pressure valves, one of which has a smaller opening force than the other of the differential pressure valves. The liquid ejection device according to claim 1 , further comprising a circulation pump that generates a circulating flow of the liquid passing through the flow path forming member between the tank and the element substrate. The liquid ejection device according to claim 3 , wherein the circulation pump is a diaphragm pump provided in the flow path forming member. A liquid ejection device as described in any one of claims 3, 6 and 7, further comprising a switching valve provided inside the flow path forming member for determining a circulation direction of the liquid, the switching valve including a leaf spring formed integrally with a portion of the flow path forming member. the flow passage forming member is provided with a hole that constitutes a part of the valve,
the flow passage forming member includes a valve seat having a metal frame and an elastic member a portion of which is fixed to the metal frame,
9. A liquid ejection device according to claim 2, wherein the valve opens and closes by a portion of the elastic member being displaced with the elastic deformation of the leaf spring and moving between a position in contact with the hole portion and a position away from the hole portion. a circulation pump that generates a circulating flow of the liquid passing through the flow path forming member between the tank and the element substrate,
a switching valve for determining a circulation direction of the liquid is further provided inside the flow path forming member, the switching valve including a leaf spring integrally formed with a part of the flow path forming member,
A liquid ejection device as described in claim 1 or 9, wherein the switching valve opens and closes by a portion of the elastic member being displaced together with the elastic deformation of the leaf spring and moving between a position in contact with another hole portion formed in the flow path forming member and a position away from the other hole portion. The liquid ejection device according to claim 10 , wherein the selector valves include a normally open selector valve and a normally closed selector valve. The liquid ejection device according to claim 1 , further comprising a suction mechanism that applies a suction force to the flow path forming member so as to elastically deform the leaf spring. The liquid ejection device according to claim 1 , wherein the element substrate and the flow path forming member are directly or indirectly laminated to form a liquid ejection head. The liquid ejection device according to claim 13, wherein the flow path forming member is a valve unit, a liquid flow unit having a liquid supply flow path and a liquid return flow path is provided between the valve unit and the element substrate, and the valve is connected to the liquid supply flow path or the liquid return flow path. 15. The liquid ejection device according to claim 13 , further comprising a gas flow unit that generates a suction force or a pressure force for operating the valve, the gas flow unit being disposed between the flow path forming member and the element substrate. 16. The liquid ejection device according to claim 13 , wherein a tank unit including the tank is directly or indirectly laminated on the element substrate and the flow path forming member to form a liquid ejection head. The liquid ejection device according to claim 1 , comprising a plurality of the element substrates.

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