JPH04308762A - Ink supply method and apparatus - Google Patents

Abstract

PURPOSE:To remove trouble such that recording becomes impossible because of the mixing with air by expelling the air introduced into an ink supply route at the time of the replacement of an ink bottle. CONSTITUTION:By opening a solenoid valve 4 to retract a piston 6 in a suction process, ink is sucked in a cylinder 5 from an ink bottle 1 and, by closing the solenoid valve 4 in a pressure process to allow a piston 6 to advance, the ink in the cylinder 5 is pressurized to be supplied to a nozzle 8 through the ink tube 7 connected to the cylinder 5 to form an ink jet. In a venting process, the ink bottle 1 is replaced and the solenoid valve 4 is opened to pressurize the ink in the cylinder 5 and the ink is allowed to flow backward to the ink bottle 1 from the cylinder 5 through the solenoid valve 4 to discharge the air in the ink supply route to the atmosphere in the ink bottle 1.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink supply device used in a continuous jet inkjet recording device, and more particularly to an ink supply system that includes a replaceable ink bottle and a piston pump, and which supplies ink when the ink bottle is replaced. The present invention relates to an ink supply method and device for preventing air from entering a path.

0002

2. Description of the Related Art Conventional ink supply devices include, for example, those described by Kent Bladh, “The three-co.
lor ink jet plotter,a
new device for the p
resentation of geophysics
cal data”, Report 1/1982
, Dept. Electr. Meas. , Lund
Inst. Tech. , p. 70-83 are well known.

Conventionally, this type of ink supply device, as shown in FIG.
a piston pump consisting of a cylinder 43 that sucks ink from an ink bottle 41 via a check valve 42 and a piston 44 that reciprocates within the cylinder 43;
an ink tube 45 that guides ink ejected from 3;
A nozzle 46 that ejects the ink guided by the ink tube 45 as a jet, a pressure sensor 47 that measures the pressure of the ink within the cylinder 43, and a piston drive mechanism 48 that reciprocates the piston 44 within the cylinder 43.
It is composed of a pump control device 49 that controls a piston drive mechanism 48 based on commands from a central processing unit (not shown, hereinafter abbreviated as CPU) of the continuous jet inkjet recording device and the output of a pressure sensor 47. Ta.

In such a conventional ink supply device, when sucking ink, the pump control device 49 causes the piston drive mechanism 48 to move the piston 4 in response to a command from the CPU.
Move 4 back. Then, the pressure inside the cylinder 43 becomes negative, the check valve 42 opens, and ink is injected into the cylinder 43 from the ink bottle 41. Note that the liquid level in the ink bottle 43 is maintained at atmospheric pressure (see the above document p.
．． 71 2nd line from the bottom ~ p. 74 up to line 4).

When pressurizing ink (during recording), the pump control device 49 controls the piston drive mechanism 4 based on a command from the CPU.
8 to advance the piston 44. Then, the pressure inside the cylinder 43 becomes positive, the check valve 42 closes, and the pressurized ink passes through the ink tube 45 and enters the nozzle 46.
and is ejected from the orifice as a jet. The pump control device 49 detects the pressure of the ink in the cylinder 43 during pressurization based on the output from the pressure sensor 47, and controls the piston drive mechanism 48 so that the pressure is constant or the flow rate is constant.

When the ink bottle 41 becomes empty, the operator of the continuous jet ink jet recording apparatus visually confirms that the ink is empty and replaces it with a new ink bottle 41 to prevent air from entering the ink supply path. do.

[0007]

[Problems to be Solved by the Invention] In the conventional ink supply device described above, since the ink empty state of the ink bottle 41 is visually detected, it is necessary to constantly monitor when the ink empty state approaches. The problem was that it was extremely inconvenient.

[0008] Furthermore, if the empty ink in the ink bottle 41 is overlooked, air will get mixed into the ink supply path including the cylinder 43, but if air gets mixed into the cylinder 43, in the next recording process, There was a problem in that the pressure of the ink within the cylinder 43 did not rise in a short time during pressurization, making recording impossible.

In view of the above-mentioned points, an object of the present invention is to provide a process for expelling air mixed into the ink supply path after replacing an ink bottle, thereby eliminating the problem that recording becomes impossible due to the mixed air. An object of the present invention is to provide an ink supply method that does the following.

Another object of the present invention is to automatically detect ink empty using existing techniques that are extremely easy and reliable, so that there is no need to visually detect ink empty, and the system is highly reliable. An object of the present invention is to provide an inexpensive ink supply device.

[0011]

[Means for Solving the Problems] The ink supply method of the present invention is an ink supply method for an ink supply device in which an ink bottle and a cylinder of a piston pump are connected via a solenoid valve. The suction process sucks ink from the ink bottle into the cylinder of the piston pump by retracting the piston of the pump, and the ink in the cylinder is pressurized by closing the solenoid valve and moving the piston forward to remove the ink connected to the cylinder. The pressurization process involves supplying ink to the nozzle through a tube to form a jet, and after replacing the ink bottle, the solenoid valve is opened to pressurize the ink inside the cylinder and the ink is sent from inside the cylinder to the ink bottle via the solenoid valve. The method is characterized in that it includes an air venting step of causing the air mixed in the ink supply path to flow backward into the ink bottle and releasing it into the atmosphere inside the ink bottle.

Further, the ink supply device of the present invention includes a replaceable ink bottle and a piston pump whose operation is controlled by a pump control device, and guides ink pressurized by the piston pump to a nozzle to form a jet. The ink supply device to be formed includes an ink reservoir to which an ink bottle is attached, an ink detection sensor that detects the presence or absence of ink in the ink reservoir and notifies the pump control device, and an ink reservoir and a cylinder of a piston pump. It is characterized by having a solenoid valve inserted between the pump and the solenoid valve whose opening and closing are controlled by a pump control device.

[0013]

[Operation] In the ink supply method of the present invention, ink is sucked from the ink bottle into the cylinder of the piston pump by opening the solenoid valve in the suction process and retracting the piston of the piston pump, and in the pressurization process, the solenoid valve is opened and the piston of the piston pump is moved backward. By closing the cylinder and moving the piston forward, the ink inside the cylinder is pressurized and the ink is supplied to the nozzle through the ink tube connected to the cylinder to form a jet, and the solenoid valve is opened after replacing the ink bottle during the air venting process. The ink in the cylinder is pressurized, the ink is caused to flow back from the cylinder into the ink bottle via the electromagnetic valve, and the air mixed in the ink supply path is discharged into the atmosphere inside the ink bottle.

Further, in the ink supply device of the present invention, the ink reservoir temporarily stores ink from the ink bottle, and the ink detection sensor detects the presence or absence of ink stored in the ink reservoir and notifies the pump control device. A pump control device controls opening and closing of a solenoid valve inserted between the ink reservoir and the cylinder of the piston pump.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a block diagram showing the main parts of an ink supply device according to an embodiment of the present invention. The ink supply device of this embodiment includes a replaceable ink bottle 1, an ink reservoir 2 for temporarily storing ink in the ink bottle 1, an ink detection sensor 3 provided in the ink reservoir 2, and an ink reservoir 2. A piston pump consisting of a solenoid valve 4 that communicates with the cylinder 5 in an openable and closable manner, a cylinder 5 that sucks ink from the ink bottle 1 through the ink reservoir 2 and the solenoid valve 4, and a piston 6 that reciprocates within the cylinder 5; An ink tube 7 that guides ink ejected from the cylinder 5, a nozzle 8 that ejects the ink guided by the ink tube 7 as a jet, a pressure sensor 9 that measures the pressure of the ink inside the cylinder 5, and a piston 6 that connects the cylinder 5 to the cylinder 5. 5, and a pump control device 11 that controls the solenoid valve 4 and the piston drive mechanism 10 based on commands from the CPU, the output of the pressure sensor 9, and the output of the ink detection sensor 3. It consists of

The volume of the cylinder 5 corresponding to one stroke of the piston 6 (cylinder volume) is sufficient to eject ink for one print sheet.

FIG. 2 shows the ink bottle 1 and the ink reservoir 2.
FIG. 3 is an enlarged cross-sectional view showing a more detailed configuration of FIG. The ink bottle 1 itself is a well-known commercially available one; one end is fixed to a rubber stopper 13 fixed to the opening of the ink bottle 1 and is open to the atmosphere, and the other end is connected to the bottom of the ink bottle 1 (
A thin air pipe 1 opened opposite the upper part in Fig. 2
2 is provided inside. As shown in FIG. 2, when the ink bottle 1 is attached to the ink bottle receiver 22, the air pipe 12 allows the atmosphere inside the ink bottle 1 to communicate with the outside atmosphere, so that the ink inside the ink bottle 1 can be removed. Ensure that the liquid level is maintained at atmospheric pressure.

The ink bottle 1 is attached to the ink bottle receiver 22 with the opening facing down, and in the attached state, the ink introduction tube 21 of the ink bottle receiver 22 passes through the rubber stopper 13 and is inserted into the ink bottle 1. The inside of the ink bottle 1 and the ink reservoir 22 are airtightly communicated through the ink introduction pipe 21. The ink introduction tube 21 is made as thin as possible to prevent dust from entering the ink supply path when the ink bottle 1 is removed.

The ink reservoir 2 is formed into a cylindrical shape with a bottom, and an ink bottle receiver 22 is hermetically screwed onto the upper part of the ink reservoir 2 through an O-ring 23. A lower part of the ink reservoir 2 is connected to a solenoid valve 4.

The ink reservoir 2 is also provided with an ink detection sensor 3 consisting of ink detection electrodes 3a and 3b to detect when the ink is empty. The ink detection electrodes 3a and 3b are composed of a pair of conductors that are disposed through the side wall of the ink reservoir 2 so that one end is exposed inside the ink reservoir 2 and the other end is exposed outside the ink reservoir 2. , the ink detection electrodes 3a are arranged at the upper level and the ink detection electrodes 3b at the lower level. The ink detection sensor 3 is
When the ink bottle 1 is empty and the ink in the ink reservoir 2 drops from the liquid level B at the lower surface position of the upper ink detection electrode 3a to the liquid level A further below, the ink detection electrode 3a is made of conductive ink. The ink empty state is detected by detecting that the conduction between the ink and 3b is broken.

The volume from the bottom of the ink reservoir 2 to the liquid level B at the lower surface of the upper ink detection electrode 3a is larger than the cylinder volume of the piston pump (full stroke of the piston 6). Therefore, when empty ink is detected after the suction operation of the piston pump, the liquid level A is always between the bottom of the ink reservoir 2 and the liquid level B at the bottom of the upper ink detection electrode 3a, and No air can get in. By the way, if air gets into cylinder 5, the structure is not simple, so
Its removal is troublesome. Note that the suction operation of the piston pump (retreating operation of the piston 6) is performed in units of one stroke, and even if ink empty is detected in the middle of one stroke, the retracting operation of the piston 6 does not stop.

Since the ink used in the ink supply device of this embodiment is conductive, a voltage is applied between the ink detection electrodes 3a and 3b, and at that time, the current flowing between the ink detection electrodes 3a and 3b is Empty ink can be easily detected by measuring the presence or absence of ink. However, since conductive ink contains an electrolyte, its composition will decompose if a voltage is applied for a long time. Therefore, in the ink supply device of this embodiment, the ink detection electrode 3a and A pulse voltage is applied between 3b and ink empty is detected by the pulse current generated at that time.

By the way, the ink detection sensor 3 is not limited to a conduction type ink detection sensor. For example, the ink reservoir 2 is made of transparent resin such as acrylic resin,
By arranging the light-emitting element and the light-receiving element horizontally and facing each other, it is also possible to detect ink empty using an optical method of detecting the presence or absence of light shielding by the ink. In this case, no compositional separation of the ink occurs, so there is no problem even if ink empty is continuously detected. Alternatively, a pair of electrodes may be disposed inside or outside the ink reservoir 2 to face each other, and the change in capacitance depending on the presence or absence of ink may be measured to detect ink empty.

FIG. 3 is a flowchart showing the air venting process in the ink supply method according to one embodiment of the present invention. This air venting process includes an ink detection process S1,
Empty determination step S2 and operation number check step S3
, a specified number of times determination step S4, a solenoid valve opening step S5, a pressurized operation ink detection step S6, and an empty determination step S7
, a pressurizing operation step S8, an ink suction step S9, and a solenoid valve closing step S10.

Next, the operation of the ink supply method and apparatus of this embodiment constructed as described above will be explained.

During ink suction, the pump control device 11 opens the solenoid valve 4 and causes the piston drive mechanism 10 to retract the piston 6 in response to a command from the CPU. Then, the pressure inside the cylinder 5 becomes negative, and ink is injected into the cylinder 5 from the ink bottle 41 via the ink reservoir 2 and the solenoid valve 4. At this time, ink bottle 1
The liquid level inside is maintained at atmospheric pressure by an air pipe 12.

When pressurizing ink (during recording), the pump control device 11 closes the solenoid valve 4 and moves the piston 6 forward by the piston drive mechanism 10 in response to a command from the CPU. Then, the pressure inside the cylinder 5 becomes positive, and the pressurized ink is guided to the nozzle 8 through the ink tube 7, and is ejected from the orifice as a jet. The pump control device 11 detects the pressure of ink in the cylinder 5 during pressurization based on the output from the pressure sensor 9, and controls the piston drive mechanism 10 so that the pressure is constant or the flow rate is constant.

After recording by the continuous jet inkjet recording device is completed and the suction operation of the ink pump is completed for the next recording, the pump control device 11 controls the ink detection sensor 3 between the ink detection electrodes 3a and 3b. A pulse voltage is applied, and conductive ink is detected based on the presence or absence of a pulse current generated at that time to check whether the ink is empty. At this time, if ink empty is detected, the ink bottle 1 is empty and the ink level is always at the level A in the ink reservoir 2. When the pump control device 11 detects that the ink is empty, it notifies the CPU that the ink is empty, and the CPU displays the fact that the ink is empty on a display device (not shown) of the continuous jet inkjet recording apparatus.

The operator of the continuous jet ink jet recording apparatus replaces the ink bottle 1 with a new one when the ink empty message is displayed. At this time, even if the ink bottle 1 is replaced, the air in the ink reservoir 2 remains in the ink reservoir 2 without replacing the ink in the ink bottle 1 because the ink introduction tube 21 is thin. If the ink pump performs a suction operation for the next recording operation with air mixed in the ink reservoir 2, the amount of ink sucked will be sucked from the ink bottle 1, but the ink reservoir The position of the liquid level A in 2 does not change. That is, since the air in the ink reservoir 2 is not expelled, the ink empty state is not released.

Therefore, when the ink bottle 1 is replaced, a signal indicating that the ink bottle 1 has been replaced is sent to the CPU via a transmission means (not shown). For example, a continuous jet inkjet recording device is usually provided with a cover (not shown), and a safety switch is attached to detect the opening and closing of the cover. If the ink bottle 1 is replaced, the signal when the cover is changed from opening to closing can be used as a signal indicating that the ink bottle 1 has been replaced.

[0032] Upon receiving a signal indicating that the ink bottle 1 has been replaced, the CPU outputs an air purge command to the pump control device 11.

Upon receiving the air purge command, the pump control device 11 performs the air purge process shown in FIG. 3.

(1) The pump control device 11 first applies a pulse voltage between the ink detection electrodes 3a and 3b of the ink detection sensor 3 to detect the presence or absence of a pulse current flowing between the ink detection electrodes 3a and 3b. Ink is detected (step S1), and the ink empty state is confirmed (step S2).

(2) At this time, since the ink level is at level A, the pump control device 11 determines that the ink is empty, and checks whether the air purge operation has been performed more than a specified number of times (step S3 and S4). The predetermined number of times is set so that the process loop of steps S1 to S10 can be exited in the event that air purge fails or a failure occurs in the ink supply device. The prescribed number of times is
2 to 3 times is appropriate. If the ink empty state is not released even after reaching the specified number of times, the pump control device 11
Treat it as a failure and perform error processing.

(3) If the number of air purge operations has not reached the specified number, the pump control device 11 opens the solenoid valve 4 (step S5) and causes the piston drive mechanism 10 to move the piston 6 forward to remove the ink. Start pressurizing operation (process S
6). At this time, since the fluid resistance on the output side (nozzle 8) of the cylinder 5 is large, the pressurized ink flows back into the ink reservoir 2 through the electromagnetic valve 4, and the liquid level A is pushed up. Then, the air in the ink reservoir 2 and the ink introduction tube 21 of the ink bottle receiver 22 enters the ink bottle 1, becomes air bubbles, and is discharged into the atmosphere inside the ink bottle 1. In this pressurizing process, the pressurizing speed of the piston 6 (pressure inside the cylinder 5) is set to a value such that the pressurized ink flows back into the ink reservoir 2 but is not discharged from the nozzle 8. In addition, in this pressurizing step, the pump control device 11 continues to detect ink empty at regular intervals (step S7).

(4) When the liquid level A is pushed up to the liquid level B, the pump control device 11 detects the pulse current flowing between the ink detection electrodes 3a and 3b, and detects that the ink empty state has been released. . Pump control device 1
No. 1 continues pressurization for a certain period of time even after the ink empty state is released (step S8). This certain period of time is set to the time required for the liquid level B to move to the liquid level C, that is, the time required for the air in the ink reservoir 2 and the ink introduction tube 21 to be completely expelled into the ink bottle 1.

(5) When the pressurizing operation for a certain period of time is completed, the pump control device 11 sucks ink (step S9), closes the solenoid valve 4 (step S10), and shifts the control to step S1. return.

(6) Then, the pump control device 11 detects ink again (step S1), and if the ink empty state is not released, repeats the air purge operation a prescribed number of times. If the ink empty state is released, this means that the ink reservoir 2 and the ink introduction tube 21 are completely filled with ink, and the pump control device 11 ends the air venting process.

[0040]

As explained above, according to the ink supply method of the present invention, after replacing an ink bottle, the solenoid valve is opened to pressurize the ink inside the cylinder, and the ink is supplied from inside the cylinder via the solenoid valve. By providing an air venting process that allows the air that has entered the ink supply path to flow back into the bottle and releases it into the atmosphere inside the ink bottle, even if air enters the ink supply path when replacing the ink bottle, it is completely removed. This has the effect of making it possible to supply ink with high reliability, and eliminating the problem of inability to record due to air being mixed in.

Furthermore, even if air gets mixed in, it is automatically removed, making the ink bottle replacement operation extremely simple.

Furthermore, according to the ink supply device of the present invention, since the ink reservoir is provided with an ink detection sensor, there is no need to visually monitor the ink empty state, and the ink reservoir acts as a buffer to prevent the cylinder of the ink pump. This has the effect of preventing air from entering the ink bottle, and allowing almost all of the ink in the ink bottle to be used up.

Furthermore, since only existing techniques that are easy and reliable are used, a highly reliable and inexpensive ink supply device can be realized.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing main parts of an ink supply device according to an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of the ink bottle and ink reservoir in FIG. 1.

FIG. 3 is a flowchart showing an air venting process in an ink supply method according to an embodiment of the present invention.

FIG. 4 is a configuration diagram showing main parts of a conventional ink supply device.

[Explanation of symbols]

1 Ink bottle 2 Ink reservoir 3 Ink detection sensor 3a, 3b Ink detection electrode 4 Solenoid valve 5 Cylinder 6 Piston 7 Ink tube 8 Nozzle 9 Pressure sensor 10 Piston drive mechanism 11 Pump control device 12 Air pipe 13 Rubber stopper 21 Ink introduction tube 22 Ink bottle holder 23 O-ring S1 Ink detection process S2 Empty judgment process S3　Operation number check process S4 Prescribed number of times determination step S5 Solenoid valve opening process S6 Pressure operation ink detection process S7 Empty judgment process S8 Pressure operation process S9 Ink suction process S10 Solenoid valve closing process

Claims (5)

[Claims] 1. In an ink supply method for an ink supply device in which an ink bottle and a cylinder of a piston pump are connected via a solenoid valve, the piston is removed from the ink bottle by opening the solenoid valve and retracting the piston of the piston pump. A suction process involves sucking ink into the cylinder of the pump, and a solenoid valve is closed to move the piston forward to pressurize the ink inside the cylinder, supplying ink to the nozzle via an ink tube connected to the cylinder and jetting. After replacing the ink bottle, the solenoid valve is opened to pressurize the ink inside the cylinder, and the ink flows back from inside the cylinder to the ink bottle via the solenoid valve to remove air mixed into the ink supply path. An ink supply method comprising the step of releasing air into the atmosphere inside an ink bottle. 2. The method further comprises the steps of measuring the residual amount of air mixed in the ink supply path during the air venting step, and continuing the air venting operation until the remaining air is completely expelled. The ink supply method according to claim 1. 3. After the air venting step, the method further includes a step of confirming that air mixed in the ink supply path has been removed, and if the air has not been removed, the air venting step is repeated a predetermined number of times. The ink supply method according to claim 1. 4. An ink supply device comprising a replaceable ink bottle and a piston pump whose operation is controlled by a pump control device, and which guides ink pressurized by the piston pump to a nozzle to form a jet,
an ink reservoir to which an ink bottle is attached; an ink detection sensor that detects the presence or absence of ink in the ink reservoir and notifies the pump control device; and a pump control device inserted between the ink reservoir and the cylinder of the piston pump. An ink supply device comprising: a solenoid valve whose opening and closing are controlled by a solenoid valve. 5. The ink detection sensor is composed of a pair of ink detection electrodes, and when detecting ink empty, a pulse voltage is applied between the pair of ink detection electrodes, and conductivity is determined depending on the presence or absence of a pulse current generated at that time. 5. The ink supply device according to claim 4, wherein the ink supply device detects the presence or absence of ink.