Liquid ejecting apparatus

Abstract

The performance of a liquid ejecting apparatus that ejects a certain amount of liquid is improved. As a means, a liquid ejection device is used. The liquid ejection apparatus includes a pump that conveys a liquid, an ejection unit that ejects the liquid, a pressure sensor that monitors a pressure of the liquid, an ejection solenoid valve that controls ejection of the liquid in the ejection unit, a control unit that controls the pressure of the liquid to be constant, and a liquid flow path that connects the pump, the ejection unit, the pressure sensor, and the ejection solenoid valve to each other. In a state in which the pressure of the liquid is controlled to be constant by the control unit, the liquid discharge amount is controlled by the opening / closing time of the discharge solenoid valve.

Description

Technical Field

[0001] The present invention relates to a liquid ejection device, and particularly to a method for quantitatively ejecting a reagent in an automatic analysis device and an automatic staining device. Background Art

[0002] Conventionally, as one method of ejecting a certain amount of liquid (for example, a reagent), as described in Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2019-124529), a method of controlling the ejection amount by changing the internal volume of a syringe or the like by a certain volume amount is known. In addition, as another method of ejecting a certain amount of liquid, the following method is known: in a state where pressure is applied to the liquid by compressed air or the like, an electromagnetic valve in a flow path is opened and closed for a certain period of time, thereby controlling the ejection amount. As such a technique, Patent Document 2 (Japanese Unexamined Patent Application Publication No. 2009-195774) describes that when pumping a liquid, the opening degree of a constant flow valve is controlled to control the supply amount of the liquid.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2019-124529

[0006] Patent Document 2: Japanese Unexamined Patent Application Publication No. 2009-195774 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] However, in the method using a syringe, it is difficult to maintain the ejection pressure from the start to the end of ejection, continuous ejection, and control the ejection amount of each of a plurality of ejection portions.

[0009] In addition, in the case of controlling the ejection amount by opening and closing the electromagnetic valve for a certain period of time, bubbles are likely to be generated inside or around the ejected liquid, which may cause a decrease in the quality of the liquid itself. In addition, in order to store the ejected liquid, a liquid tank having a pressure-resistant sealed structure needs to be used, but the atmosphere must be opened inside the tank when replenishing the liquid, and the system is stopped during this period. In addition, as a structure in which the liquid is always in contact with compressed air inside the liquid tank, the risk of contamination is high. And when contamination (such as contamination) occurs in the flow path, internal cleaning is performed, but since the liquid tank has a sealed structure, the flow path cannot be cleaned quickly, and as a result, the system must be stopped for a long time.

[0010] The present invention has been conceived to solve such problems, and an object of the present invention is to improve the performance of a liquid ejection device.

[0011] Means for Solving the Problems

[0012] A summary of representative embodiments in the embodiments disclosed in the present application is briefly described as follows.

[0013] A liquid ejection device according to an embodiment includes: a pump that conveys a liquid; an ejection unit that ejects the liquid; a pressure sensor that monitors the pressure of the liquid; an ejection solenoid valve that controls the ejection of the liquid in the ejection unit; a control unit that controls the pressure of the liquid to be fixed; and a flow path of the liquid that connects the pump, the ejection unit, the pressure sensor, and the ejection solenoid valve to each other. In a state where the pressure of the liquid is controlled to be fixed by the control unit, the liquid ejection amount is controlled by the opening and closing time of the ejection solenoid valve.

[0014] Advantageous Effects of the Invention

[0015] According to the present invention, a liquid ejection device with improved processing efficiency can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram showing the liquid ejection device in Embodiment 1.

[0017] Figure 2 It is a flowchart showing the liquid pressure control in Embodiment 1.

[0018] Figure 3 It is a schematic diagram showing the liquid ejection device in Embodiment 2.

[0019] Figure 4 It is a flowchart showing the liquid pressure control in Embodiment 2.

[0020] Figure 5 It is a waveform diagram showing the pressure waveform of the liquid during pressure control.

[0021] Figure 6 It is a flowchart showing the liquid pressure control in Embodiment 3.

[0022] Figure 7 It is a schematic diagram showing the liquid ejection device in Embodiment 4.

[0023] Figure 8 It is a timing chart showing the ejection timing of each ejection solenoid valve in Embodiment 4.

[0024] Figure 9 It is a schematic diagram showing the liquid ejection device in Embodiment 5.

[0025] Figure 10 It is a flowchart showing the switching control of the liquid container using a liquid detection sensor in Embodiment 5.

[0026] Figure 11 This is a flowchart showing the switching control of a liquid container that uses the liquid remaining amount meter value instead of the liquid detection sensor in Embodiment 5.

[0027] Figure 12 This is a flowchart showing the switching control of a liquid container when using both a liquid detection sensor and the liquid remaining amount meter value in Embodiment 5.

[0028] Figure 13 This is a schematic diagram showing the suction state in a liquid ejection device that uses a syringe as a liquid ejection device of Comparative Example 1.

[0029] Figure 14 This is a schematic diagram showing the ejection state in a liquid ejection device that uses a syringe as a liquid ejection device of Comparative Example 1.

[0030] Figure 15 This is a schematic diagram showing a liquid ejection device that is a liquid ejection device of Comparative Example 2, uses compressed air as a pressure source, and ejects liquid by opening and closing a solenoid valve for a certain period of time. Detailed Embodiments

[0031] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, in all the drawings used to describe the embodiments, components having the same function are denoted by the same reference numerals, and their repeated description is omitted. In addition, in the embodiments, unless otherwise particularly required, the description of the same or similar parts is not repeated in principle.

[0032] <Room for Improvement>

[0033] Hereinafter, using Figures 13 to 15 , the details of the room for improvement will be described.

[0034] Figure 13 This is a schematic diagram showing the suction state in a liquid ejection device of Comparative Example 1 that uses a syringe (hereinafter referred to as the syringe method). This liquid ejection device is composed of a liquid container 101 containing liquid 108, a suction solenoid valve 102, an ejection solenoid valve 103, a syringe 104, a syringe drive mechanism 105, an ejection part 106, and a flow path 107. In the Figure 13 shown syringe suction operation, under the condition of opening the suction solenoid valve 102 and closing the ejection solenoid valve 103, the liquid 108 is sucked by driving the syringe 104 in the suction direction.

[0035] Figure 14 This is showing the ejection state in the liquid ejection device described using Figure 13 . In Figure 14In the syringe ejection operation shown, under the condition that the suction solenoid valve 102 is closed and the ejection solenoid valve 103 is opened, the liquid 108 is ejected by driving the syringe 104 in the ejection direction. The liquid ejection device of Comparative Example 1 repeatedly performs the suction operation described using Figure 13 the suction operation described and the Figure 14 ejection operation described, and continuously performs the suction and ejection of the liquid 108.

[0036] However, in a liquid ejection device using a syringe, the syringe 104 starts the ejection operation from a stopped state at the start of ejection and becomes a stopped state again at the end of ejection. Therefore, it is difficult to maintain the ejection pressure of the liquid 108 at a fixed value from the start to the end of ejection. Therefore, a liquid ejection device using a syringe is not suitable for intermittent ejection such as ejecting and stopping at high speed repeatedly within a certain time. In addition, the syringe 104 performs the suction and ejection of the liquid 108 by repeatedly driving between the suction position and the ejection position, and the internal volume of the syringe 104 is limited. Therefore, it is difficult to continuously eject the liquid 108 without sucking the liquid 108 for a long time. Also, when using the same type of liquid 108 and ejecting from multiple ejection parts 106 at separate timings, it is difficult to independently control the ejection amount of the liquid 108 in the multiple ejection parts 106 using one syringe 104 regardless of the ejection timing. In this case, by adding the same number of flow path components and drive components such as syringes as the number of ejection parts 106, the liquid 108 can be ejected from each ejection part 106 without being affected by other ejection parts 106. However, the cost of the control system becomes proportionally higher as the total number of ejection parts 106 increases.

[0037] Figure 15 FIG. is a schematic diagram showing a liquid ejection device as Comparative Example 2, which uses compressed air as a pressure source and ejects by opening and closing a solenoid valve for a certain period of time (hereinafter, referred to as the compressed air method). This liquid ejection device is composed of a pressure-resistant liquid container 203 containing the liquid 208, a compressed air supply source 201, a pressure regulating valve 202, an ejection solenoid valve 204, an ejection part 205, a compressed air pipe 206, a flow path (liquid pipe) 207, an ejection solenoid valve control circuit 209, and a control part 210. As Figure 15As shown, the pressure of the compressed air generated by a compressed air supply source 201 such as a compressor is adjusted by a pressure regulating valve 202 such as a regulator to correspond to the ejection pressure of the liquid 208. The pressure-resistant liquid container 203 needs to have pressure resistance against the pressure adjusted by the pressure regulating valve 202. Inside the pressure-resistant liquid container 203, the ejection amount of the liquid 208 adjusted to the ejection pressure by the pressure regulating valve 202 is controlled by performing time opening and closing of the ejection electromagnetic valve 204 managed by the control unit 210. The opening and closing of the ejection electromagnetic valve 204 is performed by an ejection electromagnetic valve control circuit 209.

[0038] However, in this compressed air method, a compressor, a regulator, etc. are required, so there is a problem of the overall system becoming large-sized. In addition, under the pressurized conditions inside the pressure-resistant liquid container 203, the gas dissolved in the liquid 208 cannot be dissolved in the liquid 208 due to the sharp pressure change (decompression) during ejection. As a result, bubbles are likely to be generated inside or around the ejected liquid 208. This leads to a reduction in the quality of the ejected liquid 208. Therefore, for example, in applications where there cannot be bubbles in the ejected liquid 208, this compressed air method is not suitable. In addition, in order to store the ejected liquid 208, a pressure-resistant liquid container 203 with a pressure-resistant closed structure needs to be used. However, the internal volume of the pressure-resistant liquid container 203 is limited. Therefore, when the remaining amount of the liquid 208 inside the pressure-resistant liquid container 203 is insufficient, it is necessary to open the pressure inside the pressurized pressure-resistant liquid container 203 to the atmosphere and then open the pressure-resistant liquid container 203 to additionally replenish the liquid 208. As a result, the system must be stopped during the period of replenishing the liquid 208. In addition, inside the pressure-resistant liquid container 203, the structure is such that the liquid 208 is always in contact with the compressed air, and the risk of contamination (such as contamination) is high. And when performing internal cleaning when the flow path becomes fouled and contaminated, since the pressure-resistant liquid container 203 has a closed structure, the flow path cleaning cannot be performed quickly, and as a result, the system must be stopped for a long time.

[0039] Thus, there is room for improvement in the syringe-type liquid ejection device and the compressed air-type liquid ejection device. Therefore, in each embodiment of the present application, an attempt is made to solve the above-mentioned room for improvement. Hereinafter, the technical idea in the embodiment in which this improvement is implemented will be described.

[0040] (Embodiment 1)

[0041] Hereinafter, use Figure 1 and Figure 2 to describe this embodiment. In addition, the liquid mentioned in the following embodiments is, for example, a test liquid medicine (reagent).

[0042] Figure 1This is a schematic diagram showing the liquid ejection device (hereinafter referred to as the pump method) of the present embodiment. The liquid ejection device includes the following components: a liquid container 301 containing a liquid 307, a pump 302, a pressure sensor 303, an ejection solenoid valve 304, an ejection unit 305, a flow path (liquid pipe) 306, a pump control circuit 308, a pressure sensor processing circuit 309, an ejection solenoid valve control circuit 310, and a control unit 311.

[0043] The liquid container 301 is connected to the pump 302 via the flow path 306. In addition, the pump 302 is connected to the pressure sensor 303 via the flow path 306. In addition, the pressure sensor 303 is connected to the ejection unit 305 via the flow path 306, and an ejection solenoid valve 304 is provided in the middle of the flow path 306 between the pressure sensor 303 and the ejection unit 305. The control unit 311 is connected to the pump control circuit 308, the pressure sensor processing circuit 309, and the ejection solenoid valve control circuit 310, respectively. The pump control circuit 308 is connected to the pump 302, the pressure sensor processing circuit 309 is connected to the pressure sensor 303, and the ejection solenoid valve control circuit 310 is connected to the ejection solenoid valve 304.

[0044] That is, the liquid ejection device of the present embodiment has: a pump 302 for conveying the liquid 307, an ejection unit for ejecting the liquid, an ejection unit 305 for ejecting the liquid 307, a pressure sensor 303 for monitoring the pressure of the liquid 307, and an ejection solenoid valve 304 for controlling the ejection of the liquid 307 in the ejection unit 305. In addition, the liquid ejection device of the present embodiment has a control unit 311 for controlling the pressure of the liquid 307 to be fixed, and a flow path 306 of the liquid 307 that connects the pump 302, the ejection unit 305, the pressure sensor 303, and the ejection solenoid valve 304 to each other. The pressure sensor 303 does not detect the flow rate change of the liquid 307 by pressure, but detects the pressure of the liquid 307 in the standby state.

[0045] In Figure 1 it, white arrows are used to indicate the flow direction of the liquid and the ejection of the liquid in the liquid ejection device, respectively. The same applies to the schematic diagrams of other liquid ejection devices used in the following descriptions.

[0046] Figure 2This is an example of the process for controlling the pressure of the liquid in the present embodiment. Here, first, the control unit 311 determines whether the current time is the control period of the pressure control (step S401). The control period of the pressure control refers to the timing of the pressure adjustment process that is regularly performed in the liquid ejection device of the present embodiment. Next, if the current time is not the control period in step S401, no processing is performed. If the current time is the control period in step S401, the set pressure value (SV) is obtained in sequence (step S402), the current pressure value (PV) measured by the pressure sensor 303 and processed by the pressure sensor processing circuit 309 is obtained (step S403), and the deviation (τ = SV - PV) is calculated (step S404). Next, it is determined whether the conditional expression |τ| > threshold for comparing the absolute value of the deviation |τ| calculated in step S404 with the threshold value holds (step S405). If |τ| > threshold does not hold, no processing is performed. If |τ| > threshold holds, pressure control is performed after step S406. Step S405 is a process executed for adjusting the sensitivity of the control system for pressure control, or for performing control within a preset control range, etc., and can be omitted as needed, and the conditional expression can be set to |τ| > 0.

[0047] Next, the sign of the deviation (τ) is determined by the conditional expression (τ > 0) (step S406). In step S406, when the deviation (τ) is positive, it is a state where the set pressure value (SV) > the current pressure value (PV). Therefore, pressurization is required. For this purpose, the pressurization control amount is calculated (step S407) and the pump control is performed (step S408). In step S408, the pump control circuit 308 controls the liquid feeding direction of the pump 302 so as to feed the liquid toward the ejection unit for pressurization. In step S406, when the deviation (τ) is negative, it is a state where the set pressure value (SV) < the current pressure value (PV). Therefore, depressurization is required. For this purpose, the depressurization control amount is calculated (step S409) and the pump control is performed (step S410). In step S410, the pump control circuit 308 controls the liquid feeding direction of the pump 302 so as to feed the liquid toward the liquid container for depressurization. In step S406, when the deviation (τ) is 0, it is a state where the set pressure value (SV) = the current pressure value (PV) holds. Therefore, the control amount in the subsequent depressurization control amount calculation (step S409) is 0. In this way, the pump 302 can switch the liquid feeding direction by external control.

[0048] Here, for the pressurization control amount calculation (step S407) and the depressurization control amount calculation (step S409), PI control, PID control, etc. are considered. The optimal control method varies depending on the response characteristics of the pump 302 used. Therefore, the control amount calculation method is not particularly limited herein. Additionally, regarding the pressurization control amount calculation (step S407) and the depressurization control amount calculation (step S409), the optimal control method varies depending on the type of actuator (motor) driving the pump 302. Thus, for example, it can be a moving position command or a rotational speed command, and the actuator control method is not particularly limited. Additionally, the liquid container 301 is different from the pressure-resistant liquid container 203 in Comparative Example 2 shown in Figure 15 and is used at atmospheric pressure without pressurizing the inside of the liquid container 301. Therefore, there is no particular limitation on the shape of the liquid container 301. However, considering the risk of contamination such as fouling, the shape of the liquid container 301 is such that the liquid 307 does not come into direct contact with air. In particular, it is most effective to use a flexible bag-shaped container for the liquid container 301 that can deform according to the remaining amount of the liquid 307. In Figure 3 , the state where there is gas above the liquid 307 inside the liquid container 301 is shown, but ideally, there is no such gas inside the liquid container 30. Additionally, even if such gas exists inside the liquid container 30, since the pressure of this gas is below atmospheric pressure, the possibility of generating fouling is extremely low compared to the case of pressurizing with gas as in Comparative Example 2.

[0049] The liquid ejection device of the present embodiment follows the above process. The control unit 311 always performs feedback control so that the pressure of the liquid 307 becomes the set pressure value (SV), and at the same time, the ejection solenoid valve control circuit 310 opens and closes the ejection solenoid valve 304 for a certain period of time to control the ejection amount of the liquid 307. In the present embodiment, the ejection amount is controlled only by the ejection solenoid valve 304 downstream (on the ejection unit 305 side) of the pump 302. In the liquid ejection device of the present embodiment, the process shown in Figure 2 is periodically repeated until the ejection operation ends. Additionally, the control unit that controls the opening and closing of the ejection solenoid valve 304 does not need to be the same as the control unit 311 that performs the pressure control.

[0050] <Effects of the Present Embodiment>

[0051] In the liquid ejection device of the pump type according to the present embodiment, a pump 302 having a structure in which the liquid 307 does not directly contact air is used. As a result, compared with the compressed air type, the amount of gas dissolved in the liquid 307 or the amount of gas (bubbles) generated due to the pressure change (decompression) when the dissolved gas is ejected can be reduced. Further, since the liquid 307 does not need to directly contact air as in the compressed air type, the present embodiment can be realized even if the entire flow path is a closed system flow path. The closed system flow path is a flow path structure in which the entire flow path does not contact air. In particular, there is no limitation on the flow path direction. As in the liquid ejection device of the present embodiment, it is a flow path direction from the liquid container 301 toward the ejection unit 305 and is a one-way flow path direction in which the ejected liquid 307 does not circulate. As a result, the pump type of the present embodiment has an advantage that the risk of contamination is extremely low compared with the compressed air type. Further, since the pump 302 is used as the pressure source of the liquid 307, compared with the compressed air type, a compressed air supply source 201, a pressure regulating valve 202, a pressure-resistant liquid container 203 having a pressure-resistant airtight structure, etc. are not required. As a result, there is an advantage that the control system can be miniaturized.

[0052] In the present embodiment, the pump 302 must be able to control the liquid feeding direction so as to perform pressure increase control and pressure decrease control respectively. In particular, the liquid feeding direction can be switched by controlling the forward and reverse driving of the motor for the pump 302, and the liquid contact members are only tubes, and there are very few liquid contact members. Therefore, from the viewpoints of maintainability and hygiene, it is desirable that the pump 302 uses a peristaltic pump (tube pump) having a structure in which the liquid does not directly contact air. Further, in the unlikely event that the flow path is fouled and contaminated, by replacing the liquid contact member (cartridge portion) including the peristaltic pump tube, it is not necessary to stop the system for a long time for cleaning the flow path, and a short-time recovery can be achieved. Further, as the pump 302 that can switch the liquid feeding direction by external control, in addition to the peristaltic pump, a rotary pump, a gear pump, and other pumps called two-way pumps can also be used. These pumps can be used as the pumps used in Embodiments 2 to 5 described below.

[0053] (Embodiment 2)

[0054] In the above-described Embodiment 1, as the pump 302 of the liquid ejection device, the liquid feeding direction can be switched. Instead, in the present embodiment, a case where a pump that cannot switch the liquid feeding direction and has only a liquid feeding function in one direction is used will be described.

[0055] Figure 3Schematic diagram showing the liquid ejection device in this embodiment. The liquid ejection device includes the following components: a liquid container 501 containing liquid 508, a pump 502, a pressure sensor 503, an ejection solenoid valve 504, a reflux solenoid valve 505, an ejection section 506, a flow path (liquid pipe) 507, a pump control circuit 509, a pressure sensor processing circuit 510, an ejection solenoid valve control circuit 511, a reflux solenoid valve control circuit 512, and a control section 513. The liquid container 501 is connected to the pump 502 via the flow path 507. In addition, the pump 502 is connected to the pressure sensor 503 via the flow path 507. In addition, the pressure sensor 503 is connected to the ejection section 506 via the flow path 507, and the ejection solenoid valve 504 is provided in the middle of the flow path 507 between the pressure sensor 503 and the ejection section 506.

[0056] Here, the flow path 507 between the liquid container 501 and the pump 502 and the flow path 507 between the pump 502 and the pressure sensor 503 are connected by another flow path 507. The reflux solenoid valve 505 is provided in this other flow path 507. That is, two types of flow paths are provided between the liquid container 501 and the pressure sensor 503 through two flow paths. The pump 502 is provided in one flow path, and the reflux solenoid valve 505 is provided in the other flow path. Both ends of these two types of flow paths form a looped flow path. That is, these two types of flow paths form a reflux flow path within the entire flow path.

[0057] The control section 513 is respectively connected to the pump control circuit 509, the pressure sensor processing circuit 510, the ejection solenoid valve control circuit 511, and the reflux solenoid valve control circuit 512. The pump control circuit 509 is connected to the pump 502, the pressure sensor processing circuit 510 is connected to the pressure sensor 503, the ejection solenoid valve control circuit 511 is connected to the ejection solenoid valve 504, and the reflux solenoid valve control circuit 512 is connected to the reflux solenoid valve 505.

[0058] Figure 4This is an example of the process for controlling the pressure of the liquid in the present embodiment. In the present embodiment, control is performed in a state where the reflux solenoid valve 505 is released at a specified opening. Here, first, the control unit 513 determines whether the current time is the control period of the pressure control (step S601). Next, if the current time is not the control period in step S601, no processing is performed. If the current time is the control period, the set pressure value (SV) is obtained in sequence (step S602), the current pressure value (PV) measured by the pressure sensor 503 and processed by the pressure sensor processing circuit 510 is obtained (step S603), and the deviation (τ = SV - PV) is calculated (step S604). Next, it is determined whether the conditional expression |τ| > threshold, which compares the absolute value of the deviation |τ| calculated in step S604 with the threshold value, holds (step S605). If |τ| > threshold does not hold, no processing is performed, but if |τ| > threshold holds, pressure control is performed after step S606. Step S606 is a process executed to adjust the sensitivity of the control system for pressure control, or to perform control corresponding to the control range, etc.

[0059] Next, the sign of the deviation (τ) is determined by the conditional expression (τ > 0) (step S606). In step S606, when the deviation (τ) is positive, it is a state where the set pressure value (SV) > the current pressure value (PV). Therefore, the pressurization control amount is calculated (step S607) and pump control is performed (step S608). In step S608, the pump control circuit 509 controls the liquid feeding direction of the pump 502 so as to feed the liquid toward the ejection unit for pressurization. In step S606, when the deviation (τ) is negative, it is a state where the set pressure value (SV) < the current pressure value (PV). Therefore, the decompression control amount is calculated (step S609) and pump control is performed (step S610). In step S606, when the deviation (τ) is 0, it is a state where the set pressure value (SV) = the current pressure value (PV) holds, that is, a state where the stable state based on the set pressure value (SV) holds. Therefore, the control amount in the subsequent decompression control amount calculation (step S609) is 0.

[0060] As described above, the pump 502 in this embodiment cannot switch the liquid feeding direction and only has a liquid feeding function in one direction. Therefore, in the depressurization control in step S610, while the reflux solenoid valve 505 is opened to a specified opening degree to cause the liquid 508 to reflux, the pressure of the pump is reduced to perform depressurization. In addition, in the control of pressurization or depressurization, in order to perform continuous pressure increase and decrease control, a proportional valve capable of continuously controlling the internal aperture ratio when the reflux solenoid valve 505 is opened through PWM (Pulse Width Modulation) control or the like in the reflux solenoid valve control circuit 512 can also be used to change the opening degree of the reflux solenoid valve 505 for control, or used in combination with the pressure control of the pump, but the means is not particularly limited in this embodiment. The aperture is the effective diameter of the flow path. In the pressurization control amount calculation (step S607) and the depressurization control amount calculation (step S609), PI (P: Proportion, I: Integration) control and PID (P: Proportion, I: Integration, D: Differentiation) control are considered for use. In this embodiment, the control amount calculation method is not particularly limited. The pressurization control amount calculation (step S607) can be either a movement position command or a rotation speed command of the actuator (motor) that drives the pump 502, and the control method is not particularly limited.

[0061] According to the above process, the control unit 513 of the liquid ejection device in this embodiment always performs feedback control so that the pressure of the liquid 508 becomes the set pressure value (SV), and at the same time, the ejection solenoid valve 504 is opened and closed for a certain period of time through the ejection solenoid valve control circuit 511, thereby controlling the ejection amount of the liquid 508. In the liquid ejection device of this embodiment, the process shown is periodically repeated Figure 4 until the ejection operation ends. In this embodiment, the liquid feeding amount to the reflux flow path is controlled by the pressure increase and decrease control of the pump 502, and thus, the pressure increase and decrease control within the flow path can be performed.

[0062] In addition, in this embodiment, even if a pump that does not switch the liquid feeding direction is used for the pump 502, highly responsive pressure control can be performed. In addition, as the pump 502, a peristaltic pump, a rotary pump, a gear pump, or other pumps called bi-directional pumps can also be used.

[0063] (Embodiment 3)

[0064] In the above-described Embodiment 1, the case of performing feedback control on the pressure control of the liquid ejection device was described. In the feedback control of the above-described Embodiment 1 (refer to Figure 2 ), the deviation (set pressure value - current pressure value) calculated in step S404 is used to calculate the pump control amount (steps S407, S409), and pump control is performed (steps S408, S410). Therefore, in Figure 1When interference occurs in the liquid ejection device shown, as the deviation caused by the interference effect (set pressure value - current pressure value) increases, the pump control amount also increases correspondingly. As a result, after the interference occurs, feedback control starts in the direction of eliminating the interference with a slight delay. Therefore, when attempting to improve the stability of the pressure control of the liquid ejection device, the influence caused by this interference cannot be ignored. To reduce the interference effect, it is necessary to detect the degree of interference by some means and calculate the control amount caused by the interference (interference correction value) as the pump control amount.

[0065] The main cause of the interference to the feedback control system of the liquid ejection device is nothing but the opening and closing operation of the ejection solenoid valve 304. Figure 5 It shows the control signal of the ejection solenoid valve and the pressure curve during pressure control. In Figure 5 , from the top, it successively shows the ejection solenoid valve control signal 701 when the ejection solenoid valve 304 is opened and closed, the pressure waveform 702 of the above-described Embodiment 1 without performing control based on interference, and the pressure waveform 703 of this embodiment performing control based on interference. As shown by the ejection solenoid valve control signal 701 and the pressure waveform 702, when the ejection solenoid valve 304 is opened, the pressure decreases sharply, and feedback control is performed after the deviation becomes a certain positive value. Therefore, as a result, the pressure decreases after the ejection solenoid valve 304 is opened. When the ejection solenoid valve 304 is closed, the pressure increases sharply. For the same reason, the pressure increases after the ejection solenoid valve 304 is closed. Hereinafter, as this embodiment, a case will be described in which, without adding a hardware component such as a sensor as an interference detection unit to the liquid ejection device, the opening and closing operation of the ejection solenoid valve 304 that causes interference is detected, and pressure control for calculating the interference correction value as the control amount is performed.

[0066] Figure 6This is an example of the process for controlling the pressure of the liquid in the present embodiment. First, the control unit 311 determines whether the current time is the control period for pressure control (step S801). Next, if the current time is not the control period in step S801, no processing is performed. If the current time is the control period, the set pressure value (SV) is obtained (step S802), the current pressure value (PV) measured by the pressure sensor 303 and processed by the pressure sensor processing circuit 309 is obtained (step S803), and the deviation (τ = SV - PV) is calculated (step S804). Next, it is determined whether the conditional expression |τ| > threshold for comparing the absolute value of the deviation |τ| calculated in step S804 with the threshold value holds (step S805). If |τ| > threshold does not hold, no processing is performed, but if |τ| > threshold holds, pressure control is performed after the next step S806. Step S805 is a process executed for adjusting the sensitivity of the control system for pressure control and performing control corresponding to the control range.

[0067] Next, the sign of the deviation (τ) is determined by the conditional expression (τ > 0) (step S806). In step S806, when the deviation (τ) is positive, it is a state where the set pressure value (SV) > the current pressure value (PV). Therefore, the pressurization control amount is calculated (step S807). Next, by communicating with the control unit 311 or another control unit that controls the ejection electromagnetic valve 304, information on whether the opening / closing operation of the ejection electromagnetic valve 304 has been predetermined within the next control period is obtained (step S808). In this way, the detection unit that obtains information on whether the opening / closing operation of the ejection electromagnetic valve 304 has been predetermined within the next control period can be said to be an interference detection unit.

[0068] In step S808, if the opening / closing operation of the ejection electromagnetic valve 304 has been predetermined within the next control period, an interference correction value for the opening / closing operation of the ejection electromagnetic valve 304 is calculated for the pressurization control amount calculated in step S407 (step S809). As shown in the ejection electromagnetic valve control signal 701 when the ejection electromagnetic valve 304 is opened / closed (refer to Figure 5) As shown, when the ejection solenoid valve 304 is open, an interference correction value that has the effect of increasing the pressurization control amount is calculated so that the current pressure value (PV) is not lower than the set pressure value (SV) (τ > 0), which is effective (step S809). Similarly, when the ejection solenoid valve 304 is closed, an interference correction value that has the effect of reducing the pressurization control amount is calculated so that the current pressure value (PV) does not exceed the set pressure value (SV) (τ < 0), which is effective (step S809). In contrast, in step S808, when the opening / closing operation of the ejection solenoid valve 304 is not predetermined in the next control cycle, similar to step S407, a pressurization control amount without interference correction is calculated (step S809). Then, pressurization control is performed according to the pressurization control amount calculated in step S809 (step S810).

[0069] Then, in step S806, when the deviation (τ) is negative, it is a state where the set pressure value (SV) < the current pressure value (PV), so a decompression control amount is calculated (step S811). In step S806, when the deviation (τ) is 0, it is a state where the set pressure value (SV) = the current pressure value (PV) holds, that is, a stable state based on the set pressure value (SV) holds, so the control amount is generally 0 in subsequent decompression control amount calculations (step S811).

[0070] Next, by communicating with the control unit 311 or other control units that control the ejection solenoid valve 304, information on whether the opening / closing operation of the ejection solenoid valve 304 is predetermined in the next control cycle is obtained (step S812). In step S812, when the opening / closing operation of the ejection solenoid valve 304 is predetermined in the next control cycle, an interference correction value for the opening / closing operation of the ejection solenoid valve 304 is calculated for the decompression control amount calculated in step S409 (step S813). As in the ejection solenoid valve control signal 701 when the ejection solenoid valve 304 is opened / closed (refer to Figure 5) As shown, when the ejection solenoid valve 304 is closed, an interference correction value that has the effect of increasing the decompression control amount is added to the calculation so that the current pressure value (PV) does not exceed the set pressure value (SV) (τ < 0), which is effective (step S813). Similarly, when the ejection solenoid valve 304 is open, an interference correction value that has the effect of reducing the decompression control amount is calculated so that the current pressure value (PV) is not lower than the set pressure value (SV) (τ > 0), which is effective (step S813). Here, in step S812, when the opening / closing operation of the ejection solenoid valve 304 is not predetermined in the next control cycle, the decompression control amount is calculated in the same manner as in step S409 (step S813). Then, decompression control is performed according to the decompression control amount calculated in step S813 (step S814).

[0071] When interference correction is performed according to the above process, the pressure waveform 703 with interference correction has the effect of reducing the pressure fluctuation caused by interference compared to the pressure waveform 702 without interference correction. The control that has the effect of monitoring interference and eliminating the influence of interference by such means is called predictive control or feedforward control. Here, in the constant pressure control using feedback control shown in the above-described Embodiment 1, if the deviation (τ) of the pressure value caused by the influence of interference does not reach a certain magnitude, it is difficult to exhibit the control effect of eliminating interference. In contrast, in the predictive control in this embodiment, by detecting interference, the influence of interference can be quickly reduced. Such predictive control performs control to reduce the influence of interference by monitoring the degree of interference by some means, and is generally open-loop control. Therefore, it is difficult to maintain a stable state only by predictive control. Therefore, preferably, in the constant pressure control in this embodiment, for the control amount calculated by the constant pressure control (feedback control) shown in the above-described Embodiment 1, the interference correction calculated by predictive control (feedforward control) is calculated as a correction value (control amount + interference correction value), and thus the control amount is finally determined to control the pump.

[0072] The main cause of interference to the control system of this liquid ejection device is the opening / closing operation of the ejection solenoid valve 304. Therefore, in this embodiment, in steps S808 and S812, interference prediction is performed by determining whether there is solenoid valve control in the next control cycle, and interference correction is calculated for the pump control amount for control. In this embodiment, the means of the interference detection method is not limited. Therefore, for example, as the interference detection unit, a pressure sensor 303 can also be used to detect interference, or interference can be detected by additionally adding a sensor outside the control system. Thus, by applying Figure 6 the control process shown, the influence of interference can also be reduced.

[0073] According to the above, in this embodiment, the control unit 311 always uses the interference detection unit to detect interference, so that the pressure of the liquid 307 becomes the set pressure value (SV), thereby performing predictive control, and at the same time uses the ejection solenoid valve control circuit 310 to open and close the ejection solenoid valve 304 for a certain period of time, thereby controlling the ejection amount of the liquid 307. In this embodiment, the same effect as in the above-mentioned embodiment 1 can be obtained, and by performing interference prediction as described above to control the ejection amount of the liquid 307, the influence of the interference can be reduced. In other words, this embodiment has an interference detection unit, and controls the pump control amount in the constant pressure control with the control amount that corrects the influence caused by the interference, thereby reducing the influence of the interference on the control system.

[0074] (Implementation 4)

[0075] exist Figure 13 as well as Figure 14 In the comparative example 1 shown, a liquid ejection device for ejecting liquid from the ejection part 205 is shown. When using a liquid ejection device, it is sometimes necessary to use the same type of liquid to eject from multiple ejection parts at a separate timing. In order not to affect the ejection amount, the ejection timing in each ejection part is set to be staggered, for example, by more than 10 ms. Here, regarding the syringe method of comparative example 1 and the compressed air method of comparative example 2, consider the case where the same type of liquid is ejected from multiple ejection parts at a separate timing. In the syringe method, when the same type of liquid is ejected from multiple ejection parts at a separate timing, regardless of the ejection timing, it is difficult to control the ejection amount from multiple ejection parts separately in one syringe. In this case, flow path components and driving components such as syringes are added according to the number of ejection parts, thereby enabling ejection in each ejection part without being affected by other ejection parts. However, there is a disadvantage that the cost of the control system becomes higher in proportion to the total number of ejection parts.

[0076] In addition, when the compressed air method is used, regardless of the ejection timing, the number of ejection solenoid valves is increased according to the number of ejection parts, thereby enabling ejection from multiple ejection parts at separate timings. However, as described as room for improvement, the compressed air method has a tendency to increase the size of the entire system, and also has disadvantages such as the risk of dirt and contamination in the ejected liquid. The following describes a case where the same type of liquid is ejected from multiple ejection parts at separate timings in a liquid ejection device using the pump method of this embodiment.

[0077] The liquid ejection device in this embodiment includes: a liquid container 901 containing a liquid 911, a pump 902, a pressure sensor 903, a first ejection solenoid valve 904, a second ejection solenoid valve 905, a third ejection solenoid valve 906, a first ejection unit 907, a second ejection unit 908, and a third ejection unit 909. The liquid ejection device in this embodiment further includes: a flow path (liquid pipe) 910, a pump control circuit 912, a pressure sensor processing circuit 913, an ejection solenoid valve control circuit 914, and a control unit 915.

[0078] The liquid container 901 is connected to the pump 902 via the flow path 910. In addition, the pump 902 is connected to the pressure sensor 903 via the flow path 910. In addition, the pressure sensor 903 is connected to the first ejection unit 907, the second ejection unit 908, and the third ejection unit 909 respectively via the flow path 910. The first ejection solenoid valve 904 is provided midway in the flow path 910 between the pressure sensor 903 and the first ejection unit 907. The second ejection solenoid valve 905 is provided midway in the flow path 910 between the pressure sensor 903 and the second ejection unit 908. The third ejection solenoid valve 906 is provided midway in the flow path 910 between the pressure sensor 903 and the third ejection unit 909. The control unit 915 is connected to the pump control circuit 912, the pressure sensor processing circuit 913, and the ejection solenoid valve control circuit 914 respectively. The pump control circuit 912 is connected to the pump 902, the pressure sensor processing circuit 913 is connected to the pressure sensor 903, and the ejection solenoid valve control circuit 914 is connected to the first ejection solenoid valve 904, the second ejection solenoid valve 905, and the third ejection solenoid valve 906 respectively.

[0079] The liquid pressure control process in this embodiment is the same as the process in the above Embodiment 1 (refer to Figure 2 ). The liquid ejection in this embodiment is performed by controlling the first ejection solenoid valve 904, the second ejection solenoid valve 905, and the third ejection solenoid valve 906 by the ejection solenoid valve control circuit 914 and the control unit 915. That is, the ejection from the first ejection unit 907 is controlled by the first ejection solenoid valve 904, the ejection of the second ejection unit 908 is controlled by the second ejection solenoid valve 905, and the ejection from the third ejection unit 909 is controlled by the third ejection solenoid valve 906.

[0080] Figure 8 Indicate the control signals of the first ejection solenoid valve 904, the second ejection solenoid valve 905, and the third ejection solenoid valve 906 in this embodiment. As Figure 8As shown, by controlling the opening and closing of each ejection solenoid valve at different opening and closing timings, liquid can be ejected from each ejection unit in different ejection patterns. Each ejection solenoid valve in the present embodiment is controlled by an ejection solenoid valve control circuit 914. The control of each ejection solenoid valve can be performed by the same control unit 915 or by separate control units 915, and the means is not limited. In the present embodiment, since there are a plurality of ejection units, the ejection flow rate becomes larger compared to the case where there is one ejection unit. As a result, the liquid supply amount of the pump 902 in the constant pressure control also becomes larger. Therefore, in the present embodiment, it is particularly important to use a pump 902 having a liquid supply amount commensurate with the number of ejection units.

[0081] In the present embodiment, as Figure 8 shown, by opening and closing the ejection solenoid valve at high speed, intermittent ejection of liquid can also be performed. In such intermittent ejection, an air layer (segmented air) enters the ejected liquid, and thus, less damage is caused to the object, and the object can be cleaned only by liquid ejection. Therefore, the liquid ejection device of the present embodiment can be applied as a cleaning mechanism. In addition, the liquid ejection of the present embodiment is of course not limited to intermittent ejection.

[0082] Based on the above, in the liquid ejection device of the present embodiment, the control unit 915 always performs feedback control so that the pressure of the liquid 911 becomes a set pressure value (SV), and at the same time, the ejection solenoid valve control circuit 914 opens and closes the first ejection unit 907, the second ejection unit 908, and the third ejection unit 909 respectively, thereby controlling the ejection amounts of the liquid 911 from the first ejection unit 907, the second ejection unit 908, and the third ejection unit 909. In the present embodiment, even when the same type of liquid is ejected from a plurality of ejection units at separate timings, the same effects as those in the above-described Embodiment 1 can be obtained.

[0083] (Embodiment 5)

[0084] In the above-described Embodiment 1, a liquid ejection device that supplies the liquid 307 from the Figure 1 shown liquid container 301 was described. In this liquid ejection device, when the liquid 307 disappears from the liquid container 301, the pump 302 cannot eject the liquid 307, and the system has to be stopped. In addition, when the ejection of the liquid 307 continues, during the period when the system is stopped, after the liquid 307 is replenished to the liquid container 301, a reset operation such as removing air bubbles in the flow path needs to be performed so that the liquid can be ejected again. Therefore, there are problems regarding the stability and reliability of the system.

[0085] In the present embodiment, a liquid ejection device having a plurality of liquid containers, a switching solenoid valve for switching the liquid containers, and a liquid detection sensor will be described.Figure 9 Indicates the liquid ejection device of the present embodiment. The liquid ejection device of the present embodiment includes: a liquid container 1101 containing liquid 1111, a liquid container 1102, a liquid detection sensor 1103 for detecting the presence or absence of liquid 1111, a liquid detection sensor 1104, a pump 1105, a pressure sensor 1106, a switching solenoid valve 1107, an ejection solenoid valve 1108, and an ejection unit 1109. In addition, the liquid ejection device of the present embodiment includes: a flow path (liquid pipe) 1110, a liquid detection sensor processing circuit 1112, a switching solenoid valve control circuit 1113, a pump control circuit 1114, a pressure sensor processing circuit 1115, an ejection solenoid valve control circuit 1116, and a control unit 1117. The liquid detection sensors 1103 and 1104 are monitoring units for detecting the presence or absence of liquid in the liquid containers 1101 and 1102, respectively.

[0086] The liquid container 1101 is connected to the switching solenoid valve 1107 via the flow path 1110 in which the liquid detection sensor 1103 is provided midway. The liquid container 1102 is connected to the switching solenoid valve 1107 via the flow path 1110 in which the liquid detection sensor 1104 is provided midway. The switching solenoid valve 1107 is connected to the pump 1105 via the flow path 1110. The pump 1105 is connected to the pressure sensor 1106 via the flow path 1110. The pressure sensor 1106 is connected to the ejection unit 1109 via the flow path 1110, and the ejection solenoid valve 1108 is provided midway in the flow path 1110 between the pressure sensor 1106 and the ejection unit 1109. The control unit 1117 is connected to the liquid detection sensor processing circuit 1112, the switching solenoid valve control circuit 1113, the pump control circuit 1114, the pressure sensor processing circuit 1115, and the ejection solenoid valve control circuit 1116, respectively. The liquid detection sensor processing circuit 1112 is connected to the liquid detection sensors 1103 and 1104, respectively. The switching solenoid valve control circuit 1113 is connected to the switching solenoid valve 1107. The pump control circuit 1114 is connected to the pump 1105. The pressure sensor processing circuit 1115 is connected to the pressure sensor 1106. The ejection solenoid valve control circuit 1116 is connected to the ejection solenoid valve 1108.

[0087] Figure 10This shows an example of the control flow in the fifth embodiment. Here, first, the control unit 1117 determines whether the current time is the control cycle of the pressure control (step S1201). Next, if the current time in step S1201 is not the control cycle, no processing is performed. If the current time in step S1201 is the control cycle, the used container data is acquired (step S1202). Next, the liquid detection sensor value in the type of used container acquired in step S1202 is acquired (step S1203). After that, the cumulative value (Val) of the liquid detection sensor value acquired in step S1203 is calculated (step S1204). In step S1203, the purpose of calculating the cumulative value of the liquid detection sensor value is to reduce the influence of noise caused by sensor vibration, etc., and it is necessary to optimize the number of operation data used when calculating the cumulative value according to the periodic characteristics of the noise component.

[0088] Next, it is determined whether the conditional expression Val > threshold for comparing the cumulative value (Val) calculated in step S1204 with the threshold value holds (step S1205). When the conditional expression Val > threshold holds, it is a state where there is no liquid in the liquid detection sensor unit. Therefore, after performing the container switching process (step S1206) and the rewritten process of the used container data after switching (step S1207), the pressure control described in the above-mentioned first embodiment is performed (refer to Figure 2 ). In contrast, when the conditional expression Val > threshold does not hold, the container switching process is not performed, and the pressure control described in the above-mentioned first embodiment is performed (refer to Figure 2 ). By switching the liquid container in this way, the liquid can be continuously ejected without stopping the system.

[0089] However, in this method, when a liquid break occurs at the position of the liquid detection sensor, when the condition that the cumulative value (Val) of the liquid detection sensor value exceeds the threshold is satisfied, the container replacement process is generated. Therefore, the liquid 1111 contained in the flow path from the liquid detection sensor to the switching solenoid valve 1107 becomes the dead volume and is discarded without being used for ejection, which becomes a problem. The dead volume depends on the flow path length from the liquid detection sensor to the switching solenoid valve 1107. Therefore, in a system with a longer flow path length, the amount of liquid discarded as the dead volume is larger.

[0090] Therefore, in Figure 11 it is shown in Figure 9Remove the liquid detection sensors 1103 and 1104 from the liquid ejection device shown, and the control process in the ejection system that calculates the liquid remaining amount count value based on the opening time of the solenoid valve to perform liquid switching. Here, first, the control unit 1117 determines whether the current time is the control cycle of the pressure control (step S1301). Next, if the current time is not the control cycle in step S1201, no processing is performed. If the current time is the control cycle in step S1201, the used container data is acquired (step S1302). Next, the liquid ejection amount (B) from the previous control cycle in the type of used container acquired through step S1302 is acquired (step S1303). Next, using the liquid ejection amount (B) from the previous control cycle acquired through step S1303 as differential data, an operation (A - B) for updating the liquid remaining amount count value (A) is performed (step S1304). That is, here, the liquid ejection device has: a liquid remaining amount monitoring unit that acquires the liquid ejection amount from the previous control cycle in the type of used container and calculates the liquid remaining amount count value. This liquid remaining amount monitoring unit monitors the liquid remaining amount based on the liquid remaining amount count value calculated according to the total opening time of the ejection solenoid valve.

[0091] Next, it is judged whether the conditional expression A < threshold for comparing the liquid remaining amount count value (A) calculated in step S1304 with the threshold value holds (step S1305). When the conditional expression A < threshold holds, it is a state where the liquid remaining amount count value (A) becomes smaller. Therefore, after performing the container switching process (step S1306) and the rewritten process of the used container data after switching (step S1307), the pressure control described in the above Embodiment 1 is performed (refer to Figure 2 ). In contrast, when the conditional expression A < threshold does not hold, it is a state where the liquid remaining amount count value (A) is not as small as to switch the container. Therefore, the container switching process is not performed, and the pressure control described in the above Embodiment 1 is performed (refer to Figure 2 ).

[0092] At this time, a liquid detection sensor is not required, so the system cost does not increase, and the liquid switching process can be performed. However, when setting the liquid container in the system, in order not to deviate between the liquid remaining amount count value and the actual liquid remaining amount, it must always be set in a state where the liquid amount is a fixed value. Therefore, the workload of the operator may increase. In addition, in the subtraction method using the liquid remaining amount count value, in order to avoid the actual liquid remaining amount being less than the theoretical remaining amount, it is necessary to set the liquid remaining amount count value with a margin. As a result, the differential after the margin from the theoretical value becomes dead volume and is discarded without being used for ejection, which becomes a problem.

[0093] Also, for example, in a state where the liquid remaining amount count value (A) satisfies A > the threshold value, that is, in a state where the liquid remaining amount count value (A) is not as small as to switch the container, if the liquid container becomes empty due to some reason, since there is no unit such as a liquid detection sensor to monitor the presence or absence of liquid, the system cannot monitor this abnormal state, and there is a problem of ejecting liquid containing air.

[0094] Therefore, to solve these problems, an example of the following control flow is shown in Figure 12 : In a liquid ejection device having a liquid detection sensor as shown in Figure 9 , by using the read value of the liquid detection sensor and the liquid remaining amount count value together, the dead volume that causes problems is reduced, and the liquid container can be switched even in abnormal states such as sudden liquid interruption. Here, first, the control unit 1117 determines whether the current time is the control cycle of pressure control (step S1401). Next, if the current time is not the control cycle in step S1401, no processing is performed. If the current time is the control cycle in step S1401, it is determined whether it is in the liquid remaining amount counting (step S1402). In step S1402, if it is not in the liquid remaining amount counting, in order to enter the monitoring of the liquid detection sensor, the used container data is acquired (step S1403). Next, the liquid detection sensor value in the type of used container acquired through step S1403 is acquired (step S1404). After that, the cumulative value (Val) of the liquid detection sensor value acquired through step S1404 is calculated (step S1405). In step S1405, the purpose of calculating the cumulative value of the liquid detection sensor value is to reduce the influence of sensor value fluctuations, and it is necessary to optimize the number of operation data used when calculating the cumulative value according to the periodic characteristics of the fluctuations, etc.

[0095] Next, it is determined whether the conditional expression Val > the threshold value for comparing the cumulative value (Val) calculated in step S1405 with the threshold value holds (step S1406). When the conditional expression Val > the threshold value holds, it is a state where there is no liquid in the liquid detection sensor unit. Therefore, from then on, the liquid remaining amount counting is started so that the liquid of the dead volume can be effectively used for ejection. Then, in sequence, for liquid remaining amount counting, the liquid remaining amount set value (R) is acquired (step S1407), the liquid remaining amount count value (A) is initialized (step S1408), the liquid remaining amount counting is started (step S1409), and then, the pressure control described in the above Embodiment 1 is performed (refer to Figure 2 ).

[0096] When the conditional expression Val > the threshold value does not hold in step S1406, the container switching process is not performed, and the pressure control described in the above Embodiment 1 is performed (refer toFigure 2 )。

[0097] In the case of liquid remaining amount counting in step S1402, the liquid ejection amount (B) from the previous control cycle is obtained (step S1411). Then, taking the liquid ejection amount (B) from the previous control cycle obtained in step S1411 as differential data, an operation for updating the liquid remaining amount count value (A) is performed (A - B) (step S1412). Next, it is judged whether the conditional expression A < R for comparing the liquid remaining amount count value (A) calculated in step S1412 with the liquid remaining amount set value (R) holds (step S1413). When the conditional expression A < R holds, it is a state where the liquid remaining amount count value (A) becomes smaller. Therefore, after successively performing the container switching process (step S1414), the rewritten process of the used container data after switching (step S1415), and the liquid remaining amount counting end process (step S1416), the pressure control described in the above Embodiment 1 is performed (refer to Figure 2 ). On the contrary, when the conditional expression A < R does not hold, the pressure control described in the above Embodiment 1 is performed (refer to Figure 2 ).

[0098] Based on the above, by using the Figure 12 shown process, when the liquid detection sensor detects liquid breakage during normal times, the liquid container is switched according to the liquid remaining amount count value. Therefore, a liquid ejection device capable of reducing the dead volume and having extremely little liquid waste during container switching can be realized. In addition, even when an abnormality such as liquid breakage in the liquid container occurs due to sudden liquid generation, the liquid container is switched according to the liquid remaining amount count value in the same manner as during normal times from that time point. Therefore, a liquid ejection device with a reduced dead volume and high reliability can be realized.

[0099] In the above Embodiment 1, the case where it is effective to use a deformable and flexible bag-shaped container as the liquid container is described. In such a bag-shaped container, it is very difficult to provide a liquid level sensor inside, so it is difficult to consider monitoring the liquid remaining amount in the liquid container by the liquid level sensor. Therefore, in the case where the liquid container uses a flexible bag-shaped container or the like, the present embodiment having a monitoring unit outside the liquid container has an advantageous effect.

[0100] Based on the above, in the present embodiment, the control unit 1117 always performs feedback control so that the pressure of the liquid 1111 becomes the set pressure value (SV), and at the same time monitors the remaining amounts of the liquid containers 1101 and 1102 and performs container switching, thereby continuously controlling the ejection amount without cutting off the liquid 1111.

[0101] As described above, the invention completed by the present inventors has been specifically described according to its embodiments. However, the present invention is not limited to the above embodiments, and various modifications can be made without departing from its spirit.

[0102] Industrial Applicability

[0103] The present invention can be widely applied to liquid ejection devices.

[0104] Reference Signs

[0105] 301 Liquid container

[0106] 302 Pump

[0107] 303 Pressure sensor

[0108] 304 Ejection solenoid valve

[0109] 305 Ejection part

[0110] 306 Flow path (liquid pipe)

[0111] 306 Flow path

[0112] 307 Liquid

[0113] 308 Pump control circuit

[0114] 309 Pressure sensor processing circuit

[0115] 310 Ejection solenoid valve control circuit

[0116] 311 Control unit.

Claims

1. A liquid ejection device, characterized in that: The liquid ejection device has: A pump that transports the liquid; An ejection part that ejects the liquid; A pressure sensor that monitors the pressure of the liquid; An ejection solenoid valve that controls the ejection of the liquid in the ejection part; A control part that controls the pressure of the liquid to be fixed; and A flow path of the liquid that connects the pump, the ejection part, the pressure sensor, and the ejection solenoid valve to each other, In a state where the pressure of the liquid is controlled to be fixed by the control part, the liquid ejection amount is controlled by the opening and closing time of the ejection solenoid valve.

2. The liquid ejection device according to claim 1, characterized in that: The flow path is a closed system flow path with a structure in which the liquid does not directly contact the air.

3. The liquid ejection device according to claim 1, characterized in that: The liquid ejection device further has: A plurality of the ejection parts; and The same number of ejection solenoid valves as the plurality of ejection parts, Independently control the liquid ejection amount of each of the plurality of ejection parts.

4. The liquid ejection device according to claim 1, characterized in that: The pump can switch the liquid feeding direction through external control.

5. The liquid ejection device according to claim 4, characterized in that: The pump is a peristaltic pump having a structure in which the liquid does not directly contact the air.

6. The liquid ejection device according to claim 1, characterized in that: The liquid ejection device further has: A reflux flow path provided in the flow path; and A reflux solenoid valve that controls the reflux flow path, Control the liquid feeding amount to the reflux flow path through the pump, thereby performing pressure increase and decrease control in the flow path.

7. The liquid ejection device according to claim 6, characterized in that: The reflux solenoid valve can continuously control the internal aperture diameter.

8. The liquid ejection device according to claim 1, characterized in that: The liquid ejection device has an interference detection part, and controls the pump control amount in the constant pressure control with a control amount that corrects the influence of interference, thereby reducing the influence of interference on the control system.

9. The liquid ejection device according to claim 8, characterized in that: The interference detection part determines whether there is an opening and closing control of the ejection solenoid valve in the next control cycle, and if there is an opening and closing control, controls the pump control amount in the constant pressure control with a control amount that corrects the influence of interference.

10. The liquid ejection device according to claim 1, characterized in that: The liquid ejection device further has: A plurality of liquid containers; A switching solenoid valve that switches the plurality of liquid containers; and A monitoring part for the remaining amount of liquid in each of the plurality of liquid containers, or a monitoring part for the presence or absence of the liquid in the flow path, By switching the switching solenoid valve from the liquid container determined to be out of liquid among the plurality of liquid containers to the liquid container filled with the liquid, the liquid can be continuously ejected without stopping the system.

11. The liquid ejection device according to claim 10, characterized in that: The monitoring unit for the presence or absence of the liquid is a liquid detection sensor.

12. The liquid ejecting device according to claim 10, characterized in that the monitoring unit for the remaining amount of the liquid monitors the remaining amount of the liquid by using a remaining liquid amount count value calculated based on the total opening time of the ejection solenoid valve.

13. The liquid ejecting device according to claim 10, characterized in that the monitoring unit uses a combination of a liquid detection sensor and a remaining liquid amount count value calculated based on the total opening time of the ejection solenoid valve.

Images