JP7027709B2 - Device that discharges liquid - Google Patents

Description

The present invention relates to a device for discharging a liquid .

The liquid discharge head (hereinafter, also simply referred to as “head”) has a supply flow path to the individual liquid chamber communicating with the nozzle and a discharge flow path leading to the individual liquid chamber, and supplies the liquid leading to the supply flow path. There is a flow-through type head (circulation type head) provided with a port and a liquid discharge port leading to a discharge flow path.

Conventionally, the supply side tank and the discharge side tank (collection side tank) are used to pressurize the liquid from the supply port of the head, or pressurize the liquid from the recovery port of the head to generate bubbles from the nozzle. Is known to be discharged (Patent Document 1).

Japanese Unexamined Patent Publication No. 2015-058581

The circulation type head has a problem that if the liquid supply from the supply side cannot catch up with the liquid while the liquid is being discharged, the liquid flows back from the discharge side.

The present invention has been made in view of the above problems, and an object of the present invention is to reduce the backflow of liquid to the head.

前記排出側圧力Ｖｏｕｔは、次の（１３）式によって計算する、

構成とした。


In order to solve the above problems, the device for discharging the liquid according to claim 1 of the present invention is
In a liquid discharge head and a liquid discharge device having a circulation device,
The circulation device has a circulation path through which the liquid circulates through the liquid discharge head.
In the circulation path,
The supply side tank leading to the supply port of the liquid discharge head and
Including a discharge side tank leading to the discharge port of the liquid discharge head,
The pressure of the supply side tank is made higher than the pressure of the discharge side tank to circulate the liquid.
The difference between the pressure of the supply side tank and the pressure of the discharge side tank when the liquid is discharged from the liquid discharge head is set.
Make it larger than the difference between the pressure of the supply side tank and the pressure of the discharge side tank when the liquid is not discharged.
The liquid discharge head is
A plurality of nozzles for discharging the liquid and
Individual liquid chambers leading to the nozzles and
A common liquid chamber on the supply side that communicates with the individual liquid chamber via a supply flow path,
The individual liquid chamber is provided with a common liquid chamber on the discharge side which is connected to the individual liquid chamber via a discharge flow path.
When the liquid is discharged, the pressure of the common liquid chamber on the supply side is Vin, and the pressure of the common liquid chamber on the discharge side is Vout.
The fluid resistance of the supply flow path is Rin, and the maximum value of the discharge amount when the liquid is discharged from the nozzle is Qt.
When discharging the liquid,
Vin-Vout> Qt × Rin
Satisfy the relational expression of
A means for detecting the pressure of the liquid supplied to the liquid discharge head is arranged in the liquid path between the supply side tank and the liquid discharge head.
A means for detecting the pressure of the liquid discharged from the liquid discharge head is arranged in the liquid path between the liquid discharge head and the discharge side tank.
The supply side head pressure detected by the means for detecting the pressure of the supplied liquid is Vpin [kPa],
The discharge side head pressure detected by the means for detecting the pressure of the discharged liquid is Vpout [kPa],
The difference between the pressure detection position of the means for detecting the pressure of the supplied liquid and the height of the nozzle surface of the liquid discharge head is Hpin [m].
The difference between the pressure detection position of the means for detecting the pressure of the discharged liquid and the height of the nozzle surface of the liquid discharge head is Hpout [m].
When the pressure detection position is higher than the nozzle surface, it is defined as "+", and when the pressure detection position is lower than the nozzle surface, it is defined as "-".
The fluid resistance between the common liquid chamber on the supply side and the means for detecting the pressure of the supplied liquid is Rpin [Pa · s / m ³ ],
When the fluid resistance between the discharge-side common liquid chamber and the means for detecting the pressure of the discharged liquid is Rpout [Pa · s / m ³ ],
The supply side pressure Vin is calculated by the following equation (12).

The discharge side pressure Vout is calculated by the following equation (13).

It was configured.

According to the present invention, the backflow of liquid to the head can be reduced.

It is explanatory drawing of the liquid circulation apparatus which concerns on 1st Embodiment of this invention. It is explanatory drawing which provides the explanation of the relationship between Vin-Vout and the liquid flow rate in the liquid circulation apparatus. It is explanatory drawing of the liquid circulation apparatus which concerns on 2nd Embodiment of this invention. It is an external perspective explanatory view of an example of an individual liquid chamber circulation type head. Similarly, it is a cross-sectional explanatory view along the direction orthogonal to the nozzle arrangement direction. It is a schematic explanatory drawing of an example of the apparatus which discharges a liquid which concerns on this invention. It is a plane explanatory view of the head unit of this apparatus.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The first embodiment of the present invention will be described with reference to FIG. FIG. 1 is an explanatory diagram of a liquid circulation device including a liquid discharge head according to the same embodiment.

The head 100 supplies a liquid to the individual liquid chamber 106 via the nozzle 104 for discharging the liquid, the individual liquid chamber 106 communicating with the nozzle 104, the supply flow path 116 communicating with the individual liquid chamber 106, and each supply flow path 116. It has a supply-side common liquid chamber 120, a discharge flow path 156 leading to the individual liquid chamber 106, and a discharge-side common liquid chamber 150 in which liquid is discharged via each discharge flow path 156.

The liquid is supplied to the supply-side common liquid chamber 120 through the supply port 141, and the liquid is discharged from the discharge-side common liquid chamber 150 through the discharge port 142.

In the head 100, the liquid in the individual liquid chamber 106 is pressurized by a pressure generating means such as a piezoelectric actuator or a thermal actuator, so that the liquid is discharged from the nozzle 104. At this time, the liquid not discharged from the nozzle 104 is discharged from the discharge flow path 156 to the discharge side common liquid chamber 150, and is again supplied to the supply side common liquid chamber 120 via the circulation path outside the head.

Further, even when the liquid is not discharged, the liquid flows from the supply side common liquid chamber 120 to the discharge side common liquid chamber 150 via the supply flow path 116, the individual liquid chamber 106, and the discharge flow path 156, and circulates outside the head. It is supplied again to the common liquid chamber 120 on the supply side via the route.

The liquid circulation device 200 that circulates the liquid to the head 100 includes a main tank 201 that is a liquid storage means for storing the liquid 300 discharged from the head 100, a supply side tank 210, and a discharge side tank (collection side tank) 220. The first liquid feeding pump 202 and the second liquid feeding pump 203 are provided.

The supply-side tank 210 communicates with the discharge-side tank 220 via the liquid path 281 and communicates with the supply port 141 of the head 100 via the liquid path 282. The discharge side tank 220 communicates with the discharge port 142 of the head 100 via the liquid path 283, and communicates with the main tank 201 via the liquid path 284.

That is, the supply side tank 210 communicates with the discharge side tank 220 via the liquid path 281, so that the liquid circulates through the liquid path 282, the internal flow path of the head 100, the liquid path 283, the discharge side tank 220, and the liquid path 281. Circulation route 290 is configured.

Then, the liquid is sent from the discharge side tank 220 to the supply side tank 210 via the liquid path 281 by the first liquid feed pump 202. Further, liquid is sent from the main tank 201 to the discharge side tank 220 via the liquid path 284 by the second liquid feeding pump 203.

A compressor 211, which is a compression means, is connected to the supply-side tank 210 via a regulator 212. The compressor 211 is constantly driven while the apparatus is in operation, and the pressure of the supply-side tank 210 is controlled by the regulator 212.

The supply-side tank 210 has a supply-side float sensor 215 as a liquid remaining amount detecting means for detecting the remaining amount of liquid as a liquid level height, and a supply-side pressure sensor 216 as a means for detecting the pressure in the supply-side tank 210. It is equipped with.

A vacuum pump 221 which is a decompression means is connected to the discharge side tank 220 via a regulator 222. The vacuum pump 221 is constantly driven while the device is in operation, and the pressure of the discharge side tank 220 is controlled by the regulator 222.

The discharge side tank 220 has a discharge side float sensor 225 as a liquid remaining amount detecting means for detecting the remaining amount of liquid as a liquid level height, and a discharge side pressure sensor 226 as a means for detecting the pressure in the discharge side tank 220. It is equipped with.

The circulation control unit 250 inputs the detection signal of the supply-side float sensor 215 and drives the first liquid feed pump 202 to control the supply of the liquid 300 from the discharge-side tank 220 to the supply-side tank 210. The circulation control unit 250 inputs the detection signal of the discharge side float sensor 225, drives the second liquid feed pump 203, and controls to replenish and supply the liquid 300 from the main tank 201 to the discharge side tank 220.

The circulation control unit 250 inputs the detection signal of the supply side pressure sensor 216, controls the opening and closing of the regulator 212, and controls the pressure of the supply side tank 210. The circulation control unit 250 inputs the detection signal of the discharge side pressure sensor 226, controls the opening and closing of the regulator 222, and controls the pressure of the discharge side tank 220.

The circulation control unit 250 inputs a detection signal of the flow rate sensor 230 provided in the liquid path 283 on the discharge side.

The liquid circulation device 200 configured in this way causes a differential pressure between the pressure of the supply-side tank 210 and the pressure of the discharge-side tank 220, thereby causing the supply-side tank 210 to the supply port (supply port) 141 of the head 100. The liquid 300 is supplied, and the liquid 300 is discharged (recovered) from the discharge port (discharge port) 142 of the head 100 to the discharge side tank 220.

The liquid 300 supplied to the supply port 141 of the head 100 is supplied to each of the plurality of individual liquid chambers 106 via the common liquid chamber 120 on the supply side, and droplets of the liquid 300 are discharged from the nozzle 104 according to the image data. Will be done. The liquid 300 that has not been discharged from the nozzle 104 is discharged to the discharge-side common liquid chamber 150 through the discharge flow path 156, and is discharged from the discharge port 142 to the discharge-side tank 220.

Specifically, when the circulation control unit 250 detects that the liquid level in the discharge side tank 220 is lower than the predetermined height by the discharge side float sensor 225, the circulation control unit 250 discharges that the liquid level has reached the predetermined height. The second liquid feed pump 203 is driven to replenish and supply the liquid 300 from the main tank 201 to the discharge side tank 220 until the side float sensor 225 detects it.

When the supply side float sensor 215 detects that the liquid level in the supply side tank 210 is lower than the predetermined height, until the supply side float sensor 215 detects that the liquid level has reached the predetermined height. By driving the first liquid feed pump 202, the liquid 300 is supplied from the discharge side tank 220 to the supply side tank 210.

While the power of the apparatus is on, the compressor 211 and the vacuum pump 221 are always driven. Then, the supply side regulator 212 is opened and closed so that the pressure in the supply side tank 210 detected by the supply side pressure sensor 216 becomes a predetermined pressure. Further, the discharge side regulator 222 is opened and closed so that the pressure in the discharge side tank 220 detected by the discharge side pressure sensor 226 becomes a predetermined pressure.

As a result, a differential pressure is generated between the supply side tank 210 and the discharge side tank 220, the liquid 300 circulates from the supply side tank 210 to the discharge side tank 220, and the liquid 300 from the discharge side tank 220 to the supply side tank 210. Is supplied.

Next, the setting (adjustment) of the pressure of the supply side tank and the pressure of the discharge side tank will be described.

The pressure applied to the liquid in the common liquid chamber 120 on the supply side of the head 100 (supply side pressure) is Vin [kPa],
The pressure applied to the liquid in the discharge-side common liquid chamber 150 of the head 100 (discharge-side pressure) is defined as Vout [kPa].

The pressure of the supply side tank 210 (supply side tank pressure) detected by the supply side pressure sensor 216 of the supply side tank 210 is Vtin [kPa],
The pressure of the discharge side tank 220 (discharge side tank pressure) detected by the discharge side pressure sensor 226 of the discharge side tank 220 is defined as Vtout [kPa].

The difference between the liquid level in the supply-side tank 210 and the nozzle surface of the head 100 is Htin [m],
The difference between the liquid level in the discharge side tank 220 and the nozzle surface of the head 100 is Htout [m].
The case where the liquid level in the tank is higher than the nozzle surface is "+", and the case where the liquid level in the tank is lower than the nozzle surface is "-".

The fluid resistance (fluid resistance on the supply side) between the common liquid chamber 120 on the supply side and the individual liquid chamber 106 of the head 100 is Rin [Pa · s / m ³ ],
The fluid resistance (fluid resistance on the discharge side) between the common liquid chamber 150 on the discharge side and the individual liquid chamber 106 of the head 100 is defined as Rout [Pa · s / m ³ ].

The fluid resistance between the supply-side common liquid chamber 120 and the supply-side tank 210 of the head 100 is Rtin [Pa · s / m ³ ],
The fluid resistance between the discharge-side common liquid chamber 150 and the discharge-side tank 220 of the head 100 is defined as Rotout [Pa · s / m ³ ].

The pressure of the meniscus (meniscus pressure) formed in the nozzle 104 of the head 100 is defined as Vm, and the meniscus pressure Vm can be calculated by the following equations (1) to (3).

Further, the supply side pressure Vin can be calculated by the following equation (4).

Further, the discharge side pressure Vout can be calculated by the following equation (5).

Then, when the liquid is discharged from the nozzle 104, the pressure Vtin of the supply side tank 210 and the pressure Vtout of the discharge side tank 220 are adjusted so that the nozzle meniscus pressure Vm becomes 0 to -3 [kPa].

Next, the difference between the supply side pressure Vin and the discharge side pressure Vout will be described with reference to FIG. FIG. 2 is an explanatory diagram for explaining the relationship between Vin-Vout and the liquid flow rate.

The difference (Vin-Vout) between the supply side pressure Vin and the discharge side pressure Vout is changed, and the supply side flow path (individual liquid chamber and supply) when the liquid is discharged and when it is not discharged (non-discharged). The flow rate changes of the flow path) and the discharge flow path are as shown in FIG. 2, for example. The supply side fluid resistance Rin / discharge side fluid resistance Rout = 0.8.

Here, as described above, the supply side pressure is Vin [Pa], the discharge side pressure is Vout [Pa], the supply side fluid resistance is Rin [Pa · sec / m ³ ], and the discharge side fluid resistance is Rout [Pa ·. sec / m ³ ].

Further, the flow rate flowing through the supply flow path 116, the individual liquid chamber 106, and the discharge flow path 156 when the liquid is not discharged from the nozzle 104 is Qo [m ³ / sec], and the supply flow rate is when the liquid is discharged. The flow rate flowing through the 116 and the individual liquid chamber 106 is Qin [m ³ / sec], the flow rate flowing through the discharge flow path 156 when the liquid is being discharged is Qout [m ³ / sec], and the amount of liquid discharged from the nozzle 104. Is Qt [m ³ / sec].

At this time, Qo, Qin, and Qout can be obtained by the following equations (6) to (8).

Here, in order to prevent the liquid from flowing back in the discharge flow path 156, that is, to make (Qout> 0), the relational expression of the following equation (9) may be satisfied from the equation (8). Therefore, if Qo is set so that the relational expression of the equation (9) is satisfied at the maximum value of Qt, the backflow of the liquid in the discharge flow path 156 can be reduced or prevented.

Further, in order to prevent the liquid from flowing back in the discharge flow path 156, that is, to make (Qout> 0), the equation (6) is used so as to satisfy the relational expression of the following equation (10). May be good.

That is, when the supply side pressure is Vin, the discharge side pressure is Vout, the supply side fluid resistance is Rin, and the maximum value of the discharge amount when the liquid is discharged from the nozzle is Qt when the liquid is discharged. By satisfying the relational expression of the following equation (11), it is possible to reduce or prevent the backflow in the individual flow path on the discharge side.

Therefore, the difference (Vin-Vout) between the supply side pressure Vin and the discharge side pressure Vout when the liquid is being discharged is set within the range A of FIG. 2, and when the liquid is not being discharged (the liquid discharge operation is performed). The difference between the supply side pressure Vin and the discharge side pressure Vout (Vin-Vout) is set within the range B of FIG.

The time when the liquid is discharged is when the liquid discharge operation is performed, for example, when the liquid discharge operation is printing, the printing operation is performed. Further, when the liquid is not discharged, when the liquid discharge operation is not performed, for example, if the liquid discharge operation is printing, printing is waiting.

That is, the difference between the supply side pressure Vin and the discharge side pressure Vout when the liquid is discharged is larger than the difference (Vin-Vout) between the supply side pressure Vin and the discharge side pressure Vout when the liquid is not discharged. is doing.

Here, the pressure (supply side pressure) Vin of the supply side common liquid chamber 120 is the pressure given by the supply side tank 210, and the pressure (supply side pressure) Vout of the discharge side common liquid chamber 150 is the discharge side tank 220. Is the pressure given by.

Therefore, the difference between the pressure of the supply-side tank 210 and the pressure of the discharge-side tank 220 when the liquid is discharged from the liquid discharge head 100 is the pressure of the supply-side tank 210 and the pressure of the discharge-side tank 220 when the liquid is not discharged. It is larger than the difference with the pressure.

In this case, when the liquid is discharged from the liquid discharge head 100, at least one of the absolute value of the pressure of the supply side tank 210 and the absolute value of the pressure of the discharge side tank 220 is made larger than that when the liquid is not discharged. Therefore, the difference between the pressure of the supply side tank 210 and the pressure of the discharge side tank 220 when the liquid is discharged from the liquid discharge head 100 is the pressure of the supply side tank 210 and the discharge side tank 220 when the liquid is not discharged. It can be larger than the difference with the pressure of.

In this case, when all the liquid is circulated without being discharged, the flow rate should not be less than the flow rate (flow rate Qm in FIG. 2) at which the meniscus of the nozzle is dried and the pigment is settled in the individual liquid chamber. It is preferable to set (Vin-Vout) so that the flow rate is as small as possible.

As a result, while reducing backflow, the quality is good, and the drive time of the liquid feeding means for returning the liquid from the discharge side tank to the supply side tank can be shortened or the drive speed can be slowed down, which is consumed. Power can be reduced.

Further, when the liquid is discharged, the deterioration of quality due to the backflow can be reduced by setting (Vin-Vout) so that the liquid does not flow back into the individual liquid chamber on the discharge side at the time of discharge.

Next, the second embodiment of the present invention will be described with reference to FIG. FIG. 3 is an explanatory diagram of a liquid circulation device including a liquid discharge head according to the same embodiment.

In the configuration of the first embodiment, the present embodiment is a supply-side head pressure that is a means for detecting the pressure of the liquid supplied to the head 100 in the supply-side liquid path 281 from the supply-side tank 210 to the head 100. The sensor 231 is arranged. Further, a discharge side head pressure sensor 232, which is a means for detecting the pressure of the liquid discharged from the head 100, is arranged in the discharge side liquid path 282 from the head 100 to the discharge side tank 220.

here,
The pressure detected by the supply side head pressure sensor 231 (supply side head pressure) is Vpin [kPa],
The pressure detected by the discharge side head pressure sensor 232 (discharge side head pressure) is Vpout [kPa],
And.

The difference between the pressure detection position of the supply side head sensor 231 and the height of the nozzle surface of the head 100 is Hpin [m],
The difference between the pressure detection position of the discharge side head sensor 232 and the height of the nozzle surface of the head 100 is Hpout [m].
When the pressure detection position is higher than the nozzle surface, it is defined as "+", and when the pressure detection position is lower than the nozzle surface, it is defined as "-".

The fluid resistance between the supply-side common liquid chamber 120 of the head 100 and the supply-side head pressure sensor 231 is Rpin [Pa · s / m ³ ],
The fluid resistance between the discharge side common liquid chamber 150 and the discharge side head pressure sensor 232 is Rpout [Pa · s / m ³ ].

The other parameters are the same as those in the first embodiment.

Here, the meniscus pressure Vm is calculated by the above-mentioned equation (1).

The supply side pressure Vin is calculated by the following equation (12).

The discharge side pressure Vout is calculated by the following equation (13).

Then, when the liquid is discharged from the nozzle 104, the supply side head pressure Vpin and the discharge side head pressure Vpout are adjusted so that the nozzle meniscus pressure Vm becomes 0 to -3 [kPa].

In this way, the pressure of the liquid supplied to the head 100 and the pressure of the liquid discharged from the head 100 are detected at a location close to the common liquid chamber 120 on the supply side and the common liquid chamber 150 on the discharge side of the head 100. The change in fluid resistance between the supply-side common liquid chamber 120 and the discharge-side common liquid chamber 150 of 100 becomes small.

As a result, even if the liquid viscosity changes due to a change in the environmental temperature or a change in the characteristics of the liquid over time, the pressure change applied to the liquid in the common liquid chamber 120 on the supply side and the common liquid chamber 150 on the discharge side of the head 100 becomes small. The pressure of the meniscus formed on the nozzle 104 is stable.

Next, an example of the circulation type head will be described with reference to FIGS. 4 and 5. FIG. 4 is an external perspective explanatory view of the head, and FIG. 5 is a cross-sectional explanatory view taken along a direction orthogonal to the nozzle arrangement direction of the head.

In this head, a nozzle plate 1, a flow path plate 2, and a diaphragm member 3 as a wall surface member are laminated and joined. Further, it includes a piezoelectric actuator 11 that displaces the vibration region (vibration plate) 30 of the diaphragm member 3, a common liquid chamber member 20 that also serves as a frame member of the head, and a cover 29.

The nozzle plate 1 has a plurality of nozzles 4 for discharging a liquid.

The flow path plate 2 has an individual liquid chamber 6 communicating with the nozzle 4 via the nozzle communication passage 5, a supply side fluid resistance unit 7 communicating with the individual liquid chamber 6, and a supply side introduction unit 8 communicating with each supply side fluid resistance unit 7. Is forming. Here, the flow path plate 2 is configured by laminating plate-shaped members 2A to 2F. The supply-side fluid resistance section 7 and the supply-side introduction section 8 form a supply flow path. The supply-side introduction unit 8 may have a configuration common to two or more or all individual liquid chambers 6.

The diaphragm member 3 has a deformable vibration region 30 that forms the wall surface of the individual liquid chamber 6 of the flow path plate 2. Here, the diaphragm member 3 has a two-layer structure (not limited), and is formed by a first layer forming a thin wall portion from the flow path plate 2 side and a second layer forming a thick wall portion, and the first layer is formed. A deformable vibration region 30 is formed in a portion corresponding to the individual liquid chamber 6.

Then, on the side of the diaphragm member 3 opposite to the individual liquid chamber 6, a piezoelectric actuator 11 including an electromechanical conversion element as a driving means (actuator means, pressure generating means) for deforming the vibration region 30 of the diaphragm member 3 is provided. It is arranged.

The piezoelectric actuator 11 has, for example, a required number of columnar piezoelectric elements 12 formed by groove processing the piezoelectric member joined to the base member 13 by half-cut dicing at predetermined intervals. The piezoelectric element 12 is joined to the vibration region (vibration plate) 30 of the diaphragm member 3. Further, a flexible wiring member 15 is connected to the piezoelectric element 12.

The common liquid chamber member 20 forms a common liquid chamber 10 on the supply side and a common liquid chamber 50 on the discharge side. The supply-side common liquid chamber 10 is connected to a supply port 41 which is a supply port for supplying liquid from the outside, and the discharge-side common liquid chamber 50 is connected to a discharge port 42 which is a discharge port for discharging liquid to the outside.

The supply-side common liquid chamber 10 is connected to the supply-side introduction unit 8 via the filter member 9. The filter member 9 is formed by the first layer of the diaphragm member 3.

Further, the flow path plate 2 forms a discharge-side fluid resistance portion 57, a discharge-side individual flow path 56, and a discharge-side lead-out portion 58 that communicate with each individual liquid chamber 6 via the nozzle communication passage 5. The discharge side fluid resistance portion 57, the discharge side individual flow path 56, and the discharge side lead-out section 58 form a discharge flow path. The discharge side lead-out unit 58 may be configured to be common to two or more or all discharge side individual flow paths 56.

The discharge side lead-out unit 58 is connected to the discharge side common liquid chamber 50 via the filter member 59. The filter member 59 is formed by the first layer of the diaphragm member 3.

In the head configured in this way, for example, by lowering the voltage applied to the piezoelectric element 12 from the reference potential (intermediate potential), the piezoelectric element 12 contracts, the vibration region 30 of the vibrating plate member 3 is pulled, and the individual liquid chamber 6 is pulled. As the volume of the liquid expands, the liquid flows into the individual liquid chamber 6.

After that, the voltage applied to the piezoelectric element 12 is increased to extend the piezoelectric element 12 in the stacking direction, and the vibration region 30 of the vibrating plate member 3 is deformed in the direction toward the nozzle 4 to contract the volume of the individual liquid chamber 6. As a result, the liquid in the individual liquid chamber 6 is pressurized, and the liquid is discharged from the nozzle 4.

Further, the liquid that is not discharged from the nozzle 4 passes through the nozzle 4 and is discharged to the discharge side common liquid chamber 50 via the discharge side fluid resistance section 57, the discharge side individual flow path 56, the discharge side lead-out section 58, and the filter member 59. .. Then, it is supplied again from the discharge side common liquid chamber 50 to the supply side common liquid chamber 10 through an external circulation path. Further, even when the liquid is not discharged, the liquid flows from the supply-side common liquid chamber 10 to the discharge-side common liquid chamber 50, and is further supplied to the supply-side common liquid chamber 10 through an external circulation path.

The method of driving the head is not limited to the above example (pull-push), and pulling or pushing may be performed depending on the driving waveform.

Next, an example of the device for discharging the liquid according to the present invention will be described with reference to FIGS. 6 and 7. FIG. 6 is a schematic explanatory view of the device, and FIG. 7 is a plan view of the head unit of the device.

This device discharges liquid to the carry-in means 501 for carrying in the continuous medium 510, the guide-carrying means 503 for guiding and transporting the continuous medium 510 carried in from the carry-in means 501 to the printing means 505, and the continuous medium 510. The printing means 505 for printing to form an image, the drying means 507 for drying the continuous medium 510, the discharging means 509 for discharging the continuous medium 510, and the like are provided.

The continuous medium 510 is sent out from the original winding roller 511 of the carrying-in means 501, guided and conveyed by the rollers of the carrying-in means 501, the guiding and transporting means 503, the drying means 507, and the discharging means 509, and is guided and conveyed by the winding roller 591 of the discharging means 509. It is wound up at.

The continuous medium 510 is conveyed on the transfer guide member 559 in the printing means 505 facing the head unit 550 and the head unit 555, and an image is formed by the liquid discharged from the head unit 550 and discharged from the head unit 55. Post-treatment is performed with the treatment liquid to be treated.

Here, the head unit 550 is referred to, for example, as a full-line head array 551K, 551C, 551M, 551Y for four colors from the upstream side in the medium transport direction (hereinafter, when the colors are not distinguished, it is referred to as "head array 551". ) Is placed.

Each head array 551 is a liquid discharging means, and discharges the liquids of black K, cyan C, magenta M, and yellow Y to the continuous medium 510 to be conveyed, respectively. The types and numbers of colors are not limited to this.

The head array 551 is obtained by arranging a plurality of circulation type heads 1000 on a base member 552 in a staggered manner, but the head array 551 is not limited to this.

Next, when applying the liquid circulation device to this device, the first manifold is arranged between the supply side and the supply side tank 210 of the plurality of heads 1000 of each head array 551, and each head 1000 is arranged from the first manifold. Supply liquid to. Further, a second manifold is arranged between the discharge side of the head 1000 and the discharge side tank 220, and the liquid is discharged from each head 1000 to the second manifold.

In the present application, the liquid to be discharged may have a viscosity and surface tension that can be discharged from the head, and is not particularly limited, but the viscosity becomes 30 mPa · s or less at room temperature, under normal pressure, or by heating or cooling. It is preferable that it is a thing. More specifically, solvents such as water and organic solvents, colorants such as dyes and pigments, polymerizable compounds, resins, functionalizing materials such as surfactants, biocompatible materials such as DNA, amino acids and proteins, and calcium. , Solvents, suspensions, emulsions, etc. containing edible materials such as natural pigments, such as inks for inkjets, surface treatment liquids, components of electronic and light emitting elements, and formation of electronic circuit resist patterns. It can be used in applications such as liquids and material liquids for three-dimensional modeling.

Piezoelectric actuators (laminated piezoelectric elements and thin-film piezoelectric elements), thermal actuators that use electric heat conversion elements such as heat-generating resistors, and electrostatic actuators that consist of a vibrating plate and counter electrodes are used as energy sources for discharging liquid. Includes what to do.

The "liquid discharge unit" is a liquid discharge head integrated with functional parts and a mechanism, and includes a collection of parts related to liquid discharge. For example, the "liquid discharge unit" includes a head tank, a carriage, a supply mechanism, a maintenance / recovery mechanism, a main scanning movement mechanism in which at least one of the configurations is combined with a liquid discharge head, and the like.

Here, the term "integration" means, for example, a liquid discharge head and a functional component, a mechanism in which the mechanism is fixed to each other by fastening, bonding, engagement, etc., or one in which one is movably held with respect to the other. include. Further, the liquid discharge head, the functional component, and the mechanism may be configured to be detachable from each other.

For example, as a liquid discharge unit, there is a unit in which a liquid discharge head and a head tank are integrated. In some cases, the liquid discharge head and the head tank are integrated by being connected to each other by a tube or the like. Here, a unit including a filter can be added between the head tank of these liquid discharge units and the liquid discharge head.

Further, as a liquid discharge unit, there is a unit in which a liquid discharge head and a carriage are integrated.

Further, there is a liquid discharge unit in which the liquid discharge head and the scanning movement mechanism are integrated by holding the liquid discharge head movably by a guide member constituting a part of the scanning movement mechanism. In some cases, the liquid discharge head, the carriage, and the main scanning movement mechanism are integrated.

Further, as a liquid discharge unit, there is a carriage to which a liquid discharge head is attached, in which a cap member which is a part of the maintenance / recovery mechanism is fixed, and the liquid discharge head, the carriage, and the maintenance / recovery mechanism are integrated. ..

Further, as a liquid discharge unit, there is a liquid discharge unit in which a tube is connected to a head tank or a liquid discharge head to which a flow path component is attached, and the liquid discharge head and a supply mechanism are integrated. The liquid of the liquid storage source is supplied to the liquid discharge head through this tube.

The main scanning movement mechanism shall include a single guide member. Further, the supply mechanism includes a single tube and a single loading unit.

The "device for discharging a liquid" includes a device provided with a liquid discharge head or a liquid discharge unit and driving the liquid discharge head to discharge the liquid. The device for discharging a liquid includes not only a device capable of discharging a liquid to a device to which the liquid can adhere, but also a device for discharging the liquid into the air or into the liquid.

The "device for discharging the liquid" can also include means for feeding, transporting, and discharging paper to which the liquid can adhere, as well as a pretreatment device, a posttreatment device, and the like.

For example, as a "device that ejects a liquid", an image forming device that is a device that ejects ink to form an image on paper, and a three-dimensional object (three-dimensional object) are formed in layers in order to form a three-dimensional object. There is a three-dimensional modeling device (three-dimensional modeling device) that discharges the modeling liquid into the powder layer.

Further, the "device for discharging a liquid" is not limited to a device in which a significant image such as characters and figures is visualized by the discharged liquid. For example, those that form patterns that have no meaning in themselves and those that form a three-dimensional image are also included.

The above-mentioned "thing to which a liquid can adhere" means a material to which a liquid can adhere at least temporarily, such as a material to which the liquid adheres and adheres, and a material to which the liquid adheres and permeates. Specific examples include paper, recording paper, recording paper, film, recorded media such as cloth, electronic substrates, electronic components such as piezoelectric elements, powder layers (powder layers), organ models, and media such as inspection cells. Yes, and includes everything to which the liquid adheres, unless otherwise specified.

The material of the above-mentioned "material to which a liquid can adhere" may be paper, thread, fiber, cloth, leather, metal, plastic, glass, wood, ceramics or the like as long as the liquid can adhere even temporarily.

Further, the "device for discharging the liquid" includes, but is not limited to, a device in which the liquid discharge head and the device to which the liquid can adhere move relatively. Specific examples include a serial type device that moves the liquid discharge head, a line type device that does not move the liquid discharge head, and the like.

In addition, as a "device for ejecting a liquid", a treatment liquid coating device for ejecting a treatment liquid to the paper in order to apply the treatment liquid to the surface of the paper for the purpose of modifying the surface of the paper, etc. There is an injection granulator that granulates fine particles of the raw material by injecting a composition liquid in which the raw material is dispersed in the solution through a nozzle.

In addition, in the term of this application, image formation, recording, printing, printing, printing, modeling, etc. are all synonymous.

1 Nozzle plate 2 Flow plate 3 Vibration plate 4 Nozzle 5 Nozzle communication passage 6 Individual liquid chamber 7 Supply side fluid resistance part 8 Supply side introduction part 10 Supply side common liquid chamber 11 Piezoelectric actuator 20 Common liquid chamber member (frame member)
50 Discharge side common liquid chamber 56 Discharge side individual flow path 57 Discharge side fluid resistance part 58 Discharge side outlet part 100 Liquid discharge head 104 Nozzle 106 Individual liquid chamber 116 Supply side individual flow path 120 Supply side common liquid chamber 150 Discharge side common liquid Room 156 Discharge side individual flow path 200 Liquid circulation device 201 Main tank 202 1st liquid discharge pump 203 2nd liquid supply pump 210 Supply side tank 220 Discharge side tank 250 Circulation control unit 403 Carriage 404 Liquid discharge head 440 Liquid discharge unit 630 Liquid Circulation system 1000 Liquid discharge head

Claims (4)

In a liquid discharge head and a liquid discharge device having a circulation device,
The circulation device has a circulation path through which the liquid circulates through the liquid discharge head.
In the circulation path,
The supply side tank leading to the supply port of the liquid discharge head and
Including a discharge side tank leading to the discharge port of the liquid discharge head,
The pressure of the supply side tank is made higher than the pressure of the discharge side tank to circulate the liquid.
The difference between the pressure of the supply side tank and the pressure of the discharge side tank when the liquid is discharged from the liquid discharge head is set.
Make it larger than the difference between the pressure of the supply side tank and the pressure of the discharge side tank when the liquid is not discharged.
The liquid discharge head is
A plurality of nozzles for discharging the liquid and
Individual liquid chambers leading to the nozzles and
A common liquid chamber on the supply side that communicates with the individual liquid chamber via a supply flow path,
The individual liquid chamber is provided with a common liquid chamber on the discharge side which is connected to the individual liquid chamber via a discharge flow path.
When the liquid is discharged, the pressure of the common liquid chamber on the supply side is Vin, and the pressure of the common liquid chamber on the discharge side is Vout.
The fluid resistance of the supply flow path is Rin, and the maximum value of the discharge amount when the liquid is discharged from the nozzle is Qt.
When discharging the liquid,
Vin-Vout> Qt × Rin
Satisfy the relational expression of
A means for detecting the pressure of the liquid supplied to the liquid discharge head is arranged in the liquid path between the supply side tank and the liquid discharge head.
A means for detecting the pressure of the liquid discharged from the liquid discharge head is arranged in the liquid path between the liquid discharge head and the discharge side tank.
The supply side head pressure detected by the means for detecting the pressure of the supplied liquid is Vpin [kPa],
The discharge side head pressure detected by the means for detecting the pressure of the discharged liquid is Vpout [kPa],
The difference between the pressure detection position of the means for detecting the pressure of the supplied liquid and the height of the nozzle surface of the liquid discharge head is Hpin [m].
The difference between the pressure detection position of the means for detecting the pressure of the discharged liquid and the height of the nozzle surface of the liquid discharge head is Hpout [m].
When the pressure detection position is higher than the nozzle surface, it is defined as "+", and when the pressure detection position is lower than the nozzle surface, it is defined as "-".
The fluid resistance between the common liquid chamber on the supply side and the means for detecting the pressure of the supplied liquid is Rpin [Pa · s / m ³ ],
When the fluid resistance between the discharge-side common liquid chamber and the means for detecting the pressure of the discharged liquid is Rpout [Pa · s / m ³ ],
The supply side pressure Vin is calculated by the following equation (12).

The discharge side pressure Vout is calculated by the following equation (13).

A device that discharges a liquid. In a liquid discharge head and a liquid discharge device having a circulation device,
The circulation device has a circulation path through which the liquid circulates through the liquid discharge head.
In the circulation path,
The supply side tank leading to the supply port of the liquid discharge head and
Including a discharge side tank leading to the discharge port of the liquid discharge head,
The pressure of the supply side tank is made higher than the pressure of the discharge side tank to circulate the liquid.
The difference between the pressure of the supply side tank and the pressure of the discharge side tank when the liquid is discharged from the liquid discharge head is set.
Make it larger than the difference between the pressure of the supply side tank and the pressure of the discharge side tank when the liquid is not discharged.
The liquid discharge head is
A plurality of nozzles for discharging the liquid and
Individual liquid chambers leading to the nozzles and
A common liquid chamber on the supply side that communicates with the individual liquid chamber via a supply flow path,
The individual liquid chamber is provided with a common liquid chamber on the discharge side which is connected to the individual liquid chamber via a discharge flow path.
When the liquid is discharged, the pressure of the common liquid chamber on the supply side is Vin, and the pressure of the common liquid chamber on the discharge side is Vout.
The fluid resistance of the supply flow path is Rin, and the fluid resistance of the discharge flow path is Rout.
The flow rate flowing through the discharge flow path when the liquid is not discharged is Qo,
Let Qt be the maximum value of the discharge amount when the liquid is discharged from the nozzle.
When discharging the liquid,
Qo> Qt × Rin / (Rin + Round)
Satisfy the relational expression of
A means for detecting the pressure of the liquid supplied to the liquid discharge head is arranged in the liquid path between the supply side tank and the liquid discharge head.
A means for detecting the pressure of the liquid discharged from the liquid discharge head is arranged in the liquid path between the liquid discharge head and the discharge side tank.
The supply side head pressure detected by the means for detecting the pressure of the supplied liquid is Vpin [kPa],
The discharge side head pressure detected by the means for detecting the pressure of the discharged liquid is Vpout [kPa],
The difference between the pressure detection position of the means for detecting the pressure of the supplied liquid and the height of the nozzle surface of the liquid discharge head is Hpin [m].
The difference between the pressure detection position of the means for detecting the pressure of the discharged liquid and the height of the nozzle surface of the liquid discharge head is Hpout [m].
When the pressure detection position is higher than the nozzle surface, it is defined as "+", and when the pressure detection position is lower than the nozzle surface, it is defined as "-".
The fluid resistance between the common liquid chamber on the supply side and the means for detecting the pressure of the supplied liquid is Rpin [Pa · s / m ³ ],
When the fluid resistance between the discharge-side common liquid chamber and the means for detecting the pressure of the discharged liquid is Rpout [Pa · s / m ³ ],
The supply side pressure Vin is calculated by the following equation (12).

The discharge side pressure Vout is calculated by the following equation (13).

A device that discharges a liquid. The device for discharging a liquid according to claim 1 or 2, wherein when the liquid is circulated, the pressure of the supply-side tank is set to a positive pressure and the pressure of the discharge-side tank is set to a negative pressure. The pressure of the supply side tank and the pressure of the discharge side tank are controlled according to the detection result of the means for detecting the pressure of the supplied liquid and the detection result of the means for detecting the pressure of the discharge path. The device for discharging the liquid according to any one of claims 1 to 3, further comprising means for discharging the liquid.

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