JPS58191169A - Pressure ink jet recording apparatus - Google Patents

Abstract

PURPOSE:To enable the exclusion of air in an ink, by a method wherein a space for permitting the rising of air in the ink is formed between a solenoid opening and closing valve and an ink jet nozzle and a gas vent tank equipped with a heater is provided to heat the ink supplied to the nozzle. CONSTITUTION:A printing control unit supplies a current to a solenoid valve 40 to energize the same when a solenoid opening and closing valve 5b is subjected to the injection of an ink and, when the injection of the ink through the valve 5b is stopped, deenergizes the valve 40. The valve 40 is closed with a slight time lag after the valve 5b is opened and, during this time lag, the ink pressure of an accumulator 4 is added to the inner space 31 of a gas vent tank 30 while air and the ink in the upper part of the inner space 31 is forcedly discharged to a pipe 29. The tank 30 is constituted from the main body forming the inner space 31 and side plates 50a, 50b closing both side surfaces of the inner space 31 while plate heaters 51a, 51b are mounted to the surfaces contacted with the inner space 31 of each side plates and a thermistor 52 is mounted to the lower part of the side plate 50a.

Description

Detailed Description of the Invention Regarding the Kujienoto recording device, in particular, pressurized ink is supplied to an ejection head, pressure vibrations of a constant period and a constant wave height are applied to the ink ejected from the nozzles of the head, and the ejected ink is separated into ink particles. The present invention relates to a charged arsenic inkjet recording device that selectively applies an electric field to ejected ink to generate charged ink particles, and deflects the particles using a deflection electric field.

An example of a conventional recording apparatus of this type is shown in FIG.

In FIG. 1, ink in an ink tank 1 is sucked by a pump 3 through a filter 2 and is then pumped to an accumulator 4. In the accumulator 4, pressure vibrations caused by suction (and discharge) of the pump 3 are absorbed.
and is supplied to the ink jet head 8 through the filter 6. In the head 8, a constant frequency pressure vibration is applied to the ink by constant frequency excitation of an electrostrictive vibrator. As a result, the ink ejected from the nozzle of the ink ejecting head 8 separates into ink particles at a predetermined distance from the nozzle. A charging electrode 9 is disposed at this separation position, and when a charging voltage is applied to the electrode 9 at the time of separation, the ink particles are charged to a polarity opposite to the polarity of the charging voltage. The charged ink particles are deflected by the deflection electric field between the deflection electrodes 10, 102, and are deflected onto the recording paper 2.
6 and the uncharged ink particles head towards the gutter 11.

Ink in the gutter 11 is sucked by a pump 27 and returned to the ink tank 1. Filter 6 to gutter 1 surrounded by two-dot chain lines
1 is mounted on a scanning carriage. In addition, there is a charger on the carriage or near the platen side edge for detecting ink particles and detecting the charge of ink particles when searching for position and setting the deflection amount. Although detection electrodes are arranged, illustration is omitted.

During recording preparation and recording, the solenoid valve 5a is energized to communicate the accumulator 4 and the filter 6, and the ink tank 1
The ink flow path to is closed (off). When the pump 3 is stopped, the solenoid valve 5a is deenergized, the ink inflow from the accumulator 4 is closed (off), and the filter 6 is communicated with the ink tank 1. As a result, when the pump 3 is stopped, the ink outflow from the accumulator 4 is stopped, and the ink chamber of the head 8 is reduced to the pressure inside the ink tank 1 (
Since it communicates with the atmosphere, it becomes a trap (atmospheric pressure), and the ink jetting stops early, causing the ink to run low.

In this type of inkjet recording device, the head 8
If air is present in the ink supplied to the ink, the ink jetting will become erratic or stop, and the regular formation of ink particles in a constant amount and at regular intervals will not occur, and the recorded image will be disturbed. Therefore, conventionally, an air reservoir is connected to the ink flow path from the ink pressure source to the nozzle via an on-off valve, and the air stagnant at the top of the ink flow path is stored in the air reservoir. (For example, Tokuko Sho 5215
178 and Japanese Patent Publication No. 52-15333].

However, once the air reservoir is filled with air, air cannot be recovered from the ink. Replacing the air reservoir or discharging air from the air reservoir is time-consuming.
Sometimes we lose the opportunity. In addition, even after the pressure pump is stopped, ink continues to flow out from the nozzle for a long time, resulting in large ink stains (in the case of Japanese Patent Publication No. 15178/1983).
There are problems such as the large number of mechanical elements (in the case of Japanese Patent Publication No. 52-15333), including the use of three sets of on-off valves.

On the other hand, since the ink viscosity changes depending on the ink temperature, and the mass and charge amount of the ink particles change, the amount of deflection changes, so it is preferable to keep the ink temperature constant.
Ink tank and ink flow path (C heater is installed. It is preferable to place this heater as close to the head as possible.
.

A first I:D object of the present invention is to provide a pressurized inkjet recording device that can heat ink supplied to a nozzle and expel air from the ink, and can substantially omit maintenance of an air reservoir. The second object is to provide a pressurized inkjet recording device that requires fewer additional elements and that causes less ink to flow out from the nozzle after the pressure source is shut off.

In the present invention, in order to achieve F multiplicity, a first electromagnetic on-off valve is inserted between the ink pressure source and the ink injection nozzle, and the ink Φ is inserted between the electromagnetic on-off valve and the ink injection nozzle. A space is formed in which air rises, a gas vent tank equipped with a heater is inserted, an exhaust port is formed in the upper part of the space, and this exhaust port is opened and closed by a second electromagnetic on-off valve. , closes the first electromagnetic on-off valve when ink injection stops (
The ink is cut off) and the second electromagnetic on-off valve is opened.

According to this, only two sets of valve devices are required, and when the second electromagnetic on-off valve is opened, the air stagnant in the degassing tank is released to the outside, and by opening the second electromagnetic on-off valve, The ink pressure in the ink flow path from the first electromagnetic on-off valve to the nozzle quickly drops, and therefore the ink outflow from the nozzle quickly stops.

On the other hand, during ink jetting, the ink is heated to a predetermined temperature in the gas venting tank, and due to this heating, the air in the ink expands, causing the air to separate from the ink, migrate to the upper part of the internal space of the gas venting tank, and stay there. However, when the second electromagnetic on-off valve is closed, it is discharged to the outside of the tank. There is no need to separately install a heater in the ink flow path, the ink temperature is kept constant, and air removal from the ink is facilitated.

Fluctuations in ink temperature may cause air to separate from the ink or, conversely, to dissolve into the ink, causing air particles to adhere to and remain on the inner wall of the ink pipe, and depending on the material of the ink pipe. , when ink jetting is stopped, air may seep into the pipe little by little through the pipe wall.

Therefore, it is preferable that the ink flow path between the gas vent tank and the nozzle be as short as possible. Therefore, in a preferred embodiment of the present invention, the degassing tank and the second electromagnetic on-off valve are mounted on the carriage together with the ink jet head. Also, if you divide the ink supply pipe and insert a filter! It requires a lot of assembly work and also takes up filter space. Therefore, a filter is attached to the ink outlet inside the gas venting tank. Since it is preferable that the number of pipes between the carriage and the fixed part be small, the exhaust gas 1 from the gas venting tank on the carriage is communicated with an ink recovery path connected to a gutter that captures non-printing ink particles.

FIG. 2a shows the main parts of the mechanism of an embodiment of the present invention. In this case, the first electromagnetic on-off valve 5b is connected to the accumulator 4.
A degassing tank 30 is inserted between the on-off valve 5b and the filter 6.
K. A second electromagnetic on-off valve 40 is installed.

Figure 2b shows a longitudinal section of the degassing tank.

An exhaust port 32 is provided in the upper part of the inner space 31 of the degassing tank 30.
An ink inlet 33 and an ink outlet 1] 34 are formed at the bottom. An exhaust passage 35 communicates with the exhaust port 32, and this passage is connected to the ink recovery pipe 29 of the gutter 11 via a pipe 37. Ink inlet 3
3 is connected to the discharge port of the first electromagnetic on-off valve 5b through a pipe 38, and the ink outlet is connected to the filter 6 through a pipe 39. A filter 53 is attached to the inner space 31 side of the ink outlet 34. The ink drain tank 30 is the second
The electromagnetic on-off valve 40 and the ink jet head 8 are mounted on a carriage. The exhaust port 32 is closed by a valve body 46 that is constantly pushed upward by a compression coil spring 47. The valve body 46 is integral with a rod 45, and the lower end of the rod 45 fits into a center hole 36b at the tip of a cylindrical guide 36a erected at the bottom of the gas venting tank 30.

The upper end of the rod 45 passes through the O-ring and the tightening nand and protrudes to the outside, and one end of the magnetic arm 44 is connected to the tip. The other end of the arm 44 is pivotally attached to the tip of the magnetic yoke 43. The lower end of the magnetic core 41 is fixed to the magnetic yoke 43.
1 has an electric coil 42 wound around it. Magnetic core 4
Since the arm 44 faces the upper end of the core 41, when a current of a predetermined value or more is applied to the electric coil 42 (energizing the coil), the arm 44 is attracted to the upper end surface of the core 41 and comes into contact with it. At this time, the rod 45 is
is driven downward and the valve body 46 opens the exhaust port 32. If the ink and/or air in the interior space 31 is higher than atmospheric pressure, the ink and/or air above the interior space 31 will flow through the exhaust port 32 . The ink passes through the exhaust flow path 35 and the vibrator 37 to reach the recovery pipe 29, is sucked by the pump 27, and enters the ink tank 1. If there is ink inside the inner space 31 and air has accumulated near the valve element 46, and the pressure in the inner space is higher than atmospheric pressure, when the valve element 46 is driven downward, the air in the F section will first flow. However, the ink subsequently flows into the recovery pipe 29.

FIG. 2e shows an exploded perspective view of the degassing tank 30.

The degassing tank 30 is composed of a main body forming an inner space 31 and side plates 50a and 50b that close both sides of the inner space 31. 51a and 51b are respectively attached, and a thermistor 52 is attached to the lower part of the side plate 50a.

These side plates 50a and 50b are bonded to the side surfaces of the main body with adhesive and surround the inner space 31 together with the main body.

An electrical circuit shown in FIG. 2C is connected to the terminals A to N shown in FIG. 2A. Note that the terminals A-N are shown for convenience and that such intermediate terminals are not necessarily required. As shown in FIG. 2F, the heaters 51a, 51b and thermistor 52 are connected to a heater controller, and while the printer is powered on, the controller controls the heater energization to maintain the interior space 31 at a predetermined temperature. Printing control unit 25 shown in FIG. 2C
is the drive of the pumps 3 and 27 and the first and second electromagnetic on-off valves 5b and 40 (41-47).

Controls stop, open, and close, as well as excitation control of the electrostrictive vibrator of the hemlock 8, control of application of charging voltage to the charging electrode 9, and phase search and deflection, including turning on and off the deflection voltage. Performs volume setting and recording control.

FIG. 2d shows the control operation of the printing control unit 25. When the unit 25 is powered on, it initializes the input/output board and input/output registers, and then
Set the status shown in the table.

The first table unit 25 then waits for a preparation instruction to arrive from a printer control unit (not shown), and when it arrives, sets the preparation state. That is, the pump 3 is set to drive, the first electromagnetic on-off valve 5b is opened, the pump 27 is set to drive, and the electrostrictive vibrator of the head 8 is excited. As a result, ink is ejected from the head 8, collides with the gutter 11, is sucked by the pump 27 and returns to the ink tank, and the ink in the ink tank 1 is sucked by the pump 2 and sent under pressure to the accumulator 4. Ink circulation begins. After starting ink ejection, the unit 25 waits until the ink pressure in the accumulator 4 becomes stable, detects the ink pressure, and adjusts the ink pressure to a predetermined value. When the ink pressure is stabilized at a predetermined pressure, phase search and deflection amount setting are performed, and when these are completed, ready is notified to the printer ra'J a unit, and then recording control is performed in accordance with instructions from the printer control unit. After that, when a signal indicating the end of recording is given from the printer control unit, the unit 25 attempts to stop the pump 3, and the first
The second electromagnetic on-off valve 5b is closed, the second electromagnetic on-off valve 40 is opened, and the timer (program timer) is set to ΔT (stop 1). As a result, the pump 3 is stopped, the first electromagnetic on-off valve 5b is closed, and ink supply to the accumulator 4 and ink outflow from the accumulator 4 are stopped.
The valve body 46 of the second electromagnetic on-off valve 40 is lowered to open the exhaust port 32 of the degassing tank 30, and the accumulated air and ink in the upper space of the tank 30 are discharged from the exhaust port 32. The ink flows through the flow path 35 and the pipe 37 to the ink recovery pipe 29. This causes the pressure inside the tank 30 to drop rapidly.

When this JZE force reaches the pressure within the gutter 11, that is, atmospheric pressure, ink jetting from the head 8 stops and ink flow from the exhaust port 32 stops. After the ink jetting stops, the timer finishes counting the time, and the unit 25 closes the second electromagnetic on-off valve 40 and starts driving the pump 27 (stop L2).

Due to the control operation of the control unit 25 described above, the ink is separated from the ink and remains in the upper part of the inner space of the degassing tank 30 until the ink jetting is started and after the ink jetting is started and the ink jetting is stopped. The air is discharged to the ink recovery pipe 29 (atmospheric pressure) when ink jetting is stopped. Moreover, when the ink jetting is stopped, the second electromagnetic on-off valve 40
When the valve 5b is opened, the pressure in the ink flow path from the first electromagnetic on-off valve 5b to the nozzle of the head 8 rapidly decreases to atmospheric pressure, so ink outflow from the nozzle stops within a short time after the valve 5b is closed.

FIG. 3a shows another embodiment of the present invention in which a degassing tank 30 and a second electromagnetic on-off valve 4 o (
41 to 47) are shown. In addition to this, the coil spring 47 drives the valve body 46 in the direction to open the exhaust port 32, and when the coil 421 is biased and energized, the valve body 46 is driven to open the exhaust port 32.
6 is driven downward to close the exhaust port 32. In this embodiment, the printing restraint unit (25) energizes the coil 42 to close the exhaust port (closes the second electromagnetic on-off valve 40) when ink is ejected.

Fig. 3b shows the control operation of printing control unit (25),
Table 2 shows the control status.

Table 2 In this embodiment, when the printing control unit (25) opens the first electromagnetic on-off valve 5b (ink jetting), the printing control unit (25) closes the second electromagnetic on-off valve 40 (energized). When the first electromagnetic on-off valve 5b is closed (ink ejection is stopped), the second electromagnetic on-off valve 40 is opened (de-energized). In this case, while the second electromagnetic on-off valve 40 is open, the inner space of the gas venting tank 30 is communicated with the pipe 29, and air is released. In addition, the first
The second electromagnetic on-off valve 40 is closed after a short time delay after opening the electromagnetic on-off valve 5b, and during this time delay, the ink pressure in the accumulator 4 is applied to the inner space 31 of the degassing tank 30. The air and ink in the upper part of the inner space are forcibly discharged into the pipe 29.

Air and ink are similarly discharged from the L/C when ink ejection is stopped, and ink outflow from the nozzle is quickly stopped.

Next, in another embodiment of the present invention, the guide 3
6a is a partition wall. That is, the guide 36;1 is made into a wall extending over the side plates 50a and 50b. In this embodiment, the ink that enters the degassing tank from the ink inlet is purified by the wall, rises, climbs over the upper end of the wall above the inner space, and descends to the ink outlet. While the ink rises and passes over the upper body of the wall, the air floats up and stays in the valve body. In this embodiment, air separation from the ink is effectively achieved.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing the main mechanism of a conventional charge dissociation inkjet recording apparatus. Fig. 2a, j is a system diagram showing the main parts of the mechanism of an embodiment of the present invention, Fig. 2b is an enlarged cross-sectional view of the degassing tank 30 and the second electromagnetic on-off valve 40, and Fig. 2C is the configuration of the electrical control system. FIG. 2d is a flowchart showing the control operation of the control unit 25, FIG. 2e is an exploded perspective view of the degassing tank 30, and FIG. 2f is a diagram showing the connections between the heaters 51a, 51b and teamister 52, and the heater controller. It is a circuit diagram. FIG. 3a is an enlarged sectional view of a degassing tank and a second electromagnetic on-off valve used in another embodiment of the present invention, and FIG. 3b is a flowchart showing the control operation of the control unit. 1: Ink tank 2, 6: Filter 3. 27: Pump 4: Accumulator 5a: Magnetic switching valve
8: Ink jet head 9: IJ electrode
10. ．． 102: Deflection electrode 1] Nigator
26 = Recording paper 29: Ink collection pump 5b = First electromagnetic on-off valve 30: Gas venting tank 31: Inner space 32:
Exhaust port 33: Ink inlet 34: Ink outflow D 35: Exhaust flow path 36a guide
36b: Center hole 37 to 39: Pipe 40: Second electromagnetic on-off valve 41: Core 42: Electric coil 43: Yoke 44: Arm 45: Ronod 46: Valve body 47: Compression coil spring 50a, 50b: Side plates 51a, 51b :Surface heater 52:? -j star 53
: Filter procedure amendment (1 button 1. Display of case 1982 Patent Application No. 74822 2,
Title of the invention Pressurized ink jet recording device 3, relationship to the case of the person making the amendment Patent applicant address 1-3-6 Nakamagome, Ota-ku, Tokyo Name
(674) Ricoh Co., Ltd. Representative Takeshi Oue 4, Agent 104 Phone: 03-543-86945,
Detailed explanation of the invention column 2 of the specification subject to amendment, brief explanation of the drawing column, drawing 4: (Correct)
The content has been corrected. (2) Add Figure 4. 7. Catalog drawing of attached documents...-leaf

Claims (1)

[Scope of Claims] (1) In a pressurized ink jet recording device that ejects pressurized ink from a nozzle to perform visible recording with the jetted ink, an ink flow path between an ink pressure source and the nozzle is provided. The first one inserted. An ink flow path IC is inserted between the first electromagnetic on-off valve and the nozzle, the ink inlet communicates with the discharge port of the first electromagnetic on-off valve, and the ink outlet communicates with the nozzle C. a gas venting tank having an exhaust port at the top and an inner space or a hole in the wall of the inner space; a second electromagnetic on-off valve that opens and closes the exhaust port of the gas venting tank; and first and second electromagnetic valves. A pressurized ink jet recording device comprising: a control device that opens and closes an on-off valve at predetermined timing. (2) The second electromagnetic on-off valve includes a valve body, a spring means for biasing the valve body in the exhaust port closing direction, and a solenoid device for driving the valve body in the exhaust port opening direction when energized. A pressurized ink jet recording apparatus according to the range (1). (3) The pressurized ink jet recording device according to claim (2), wherein the control device opens the second electromagnetic on-off valve for a predetermined period of time when the first electromagnetic on-off valve is switched from open to closed. . (, 11 The second electromagnetic on-off valve has a valve body and an exhaust I
] The pressurized ink jet recording apparatus according to claim 1, comprising a spring means for biasing in the opening direction, and a solenoid device for driving the valve body in the exhaust port closing direction when energized. (5) The pressurized ink jet recording apparatus according to claim 4, wherein the control device closes the second electromagnetic on-off valve after switching the first electromagnetic on-off valve from closed to open. (6) Claims (1), (2), (3), and (4) in which the degassing tank and the second electromagnetic on-off valve are mounted on the carriage together with the ink jet head. Alternatively, the pressurized ink jet recording device according to item (5). (7) Mount the degassing tank and the second electromagnetic on-off valve together with the ink jet head on the carriage, and place the exhaust port of the degassing tank at τ on the carriage and connect it to the ink collection path of the gutter that captures non-printing ink particles. (The pressurized ink jet recording apparatus according to claim 1, (2), (3), (4), or (5), which is connected to C. (8) Claims (1), (2), (3), (4), or (5), wherein a filter is attached to the inner space side of the ink outlet. The pressurized ink jet recording device described in (9) The upper part of the inner space is narrow in the upper part and wider in the lower part, stands upright from the bottom between the ink inlet and the ink outlet, and the upper part of the inner space is Claims (1) and (2) in which a wall is formed that does not divide the lower part but divides the lower part.
The pressurized ink jet recording apparatus according to item (3), item (4), or item (5). 00) The ink flow path of the degassing tank is shaped such that the ink rises from the ink pressure source toward the exhaust port and descends from the exhaust gas toward the ink outlet. ), (2), (3), (4), or (5).