JPS6223759A - Ink jet recorder - Google Patents

Abstract

PURPOSE:To reduce the amount of power to be consumed as well as simplify a sequence control system by providing a check valve between a head element and a pump and a normally-open electromagnetic valve. CONSTITUTION:A normally-open electromagnetic valves A to C are used, and a check valve 64 is provided in a flow path 8 connecting a head element with the pump. The valve 64 has a structure allowing the passage of ink to the element 1 side. In a pressurizing mode, only the valve A is closed and the other valves B and C are opened. In the other modes, all the electromagnetic valves stay open. The number of operations of the electromagnetic valves can thus be greatly reduced, and sequence control, either in terms of hard ware or soft ware can be greatly simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inkjet recording apparatus, and more particularly to an inkjet recording apparatus with an improved ink supply system.

[Prior Art] As a conventional inkjet recording device, an ink supply path is formed from an ink supply tank, passes through a recording head, and returns to the ink supply tank, and an electromagnetic force and a pump are interposed in the middle of this supply path. A structure has been proposed in which the device can be set to various modes by controlling it.

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

FIG. 9 explains the entire ink supply path. In the figure, the symbol 1 is a bubble jet type head element, in which a plurality of head elements each having a large number of nozzles are arranged in the width direction of the recording paper. There is.

Each head element 1 has two channels 2.3, one channel 2 being connected to a distributor channel 4 and the other channel 3 being connected to another distributor channel 5. .

One distributor flow path 4 is connected to a first ink tank 7 via a flow path 6, and a solenoid valve A is interposed in the middle of the flow path 6.

Further, the other distributor flow path 5 is connected to the first ink tank 7 via a flow path 8. A solenoid valve C and a pump P are interposed in the middle of the flow path 8. The pump P is driven by a motor M capable of forward and reverse rotation, and can switch the direction of ink supply.

A liquid level sensor 9 is attached to the first ink tank 7 and constantly monitors the ink level.

Further, the first ink tank 7 can be released to the atmosphere via a pipe 1O and a solenoid valve B interposed therebetween, so that the pressure inside the tank can be kept constant.

On the other hand, a second ink tank 1 that is detachable in the middle of the flow path 8 and between the electromagnetic valve C and the pump P via a check valve 11
2 are connected.

Note that although the example shown in FIG. 9 is shown in a state corresponding to one color of ink, in the case of a multicolor printer, the above-mentioned flow path system is provided in multiple layers.

Based on the above-described configuration, each electromagnetic valve A to C and the pump are controlled according to their respective modes as shown in Table 1.

1) Print mode In this case, solenoid valves A and B are open, and solenoid valve C is closed. Further, in the case of the illustrated example, since it is an on-demand type inkjet printer, no pressure is applied to the ink during recording, so the pump P is not driven. The ink is then supplied to the head unit 1 via the solenoid valve A, the flow path 6, the distributor flow path 4, and the flow path 2.

Also, because ink leaked from the first ink tank,
When the inside of the tank becomes negative pressure, air is sucked through the solenoid valve B, and the inside of the tank is kept at a constant pressure.

2) Supply mode In this mode, only the solenoid valve C is closed, the others are open, the pump is rotated normally, and ink is supplied from the second tank 12 to the first tank 7. This mode is applied when the printer starts to be used and when the amount of ink in the first tank 7 decreases.

3) Pressure mode This mode is applied when the nozzle of the head element becomes dry or when the nozzle becomes clogged, applying pressure to the ink and pushing out the ink needle from the nozzle to recover from ink ejection failure. be done.

In this mode, only the solenoid valve A is closed, the others are open, the motor is reversed, and the ink from the first ink tank 7 is transferred to the flow path 8.
．． The ink is supplied to the head element 1 side via the electromagnetic valve C, the distributor channel 5, and the channel 3, and the ink is ejected.

4) Circulation mode This mode is a mode that circulates the ink to supply ink to each head etc. during the initial use of the device, or to remove air bubbles in the heads and flow paths, and is a mode that is used to remove air bubbles in the heads and flow paths. Applies to cases.

In this case, all solenoid valves are open, the motor is reversed, and ink is supplied from the tank via channels 8, 5.3 to the head element 1 and via channels 2.4.6 to the tank. Go back inside.

Air bubbles in the head element or flow path are the first
The ink is collected in the ink tank 7 and released into the atmosphere via the solenoid valve B.

5) Storage mode In this mode, the ink in the first ink tank 7 evaporates,
This mode prevents deterioration and ink leakage, and is used when the device is not in use for a long time or during transportation.

- In this case, all solenoid valves are closed and the motor is stopped, and due to changes in surrounding conditions (temperature, humidity, etc.), ink in the tank may leak from the head, or air or dust may enter the supply path. etc. will not be mixed in.

Table 1 The functions of the device can be exerted by appropriately switching between the various modes described above.

[Problems to be Solved by the Invention] However, when the above structure is employed, the following problems arise.

First of all, since the flow of ink is controlled by solenoid valves A-C and the pump, operations such as switching the solenoid valves, stopping the pump, and reversing the pump are frequent, and the hardware and software for sequence control become complex. There are problems in that the energizing time becomes longer, the power consumption increases, and the amount of heat generated increases.

In addition, since the flow of ink is controlled by opening and closing the solenoid valve, the pressure in the flow path fluctuates each time it opens and closes, causing ink to leak from the nozzle or absorb air, creating bubbles. There is a problem.

Furthermore, it is difficult to distinguish between a small overflow from the ink flow path system and a large overflow caused by a failure, etc., and it is impossible to set the system to a safe state at the same time as a large amount of O/C flow occurs, resulting in ink leakage. There was also the problem that accidents could occur.

[Means for Solving the Problems] In the present invention, the following measures were taken to solve the above-mentioned problems.

First, in order to simplify sequence control and prevent adverse effects on the head side, a check valve that allows ink to pass only in the head direction is installed in the ink flow path between the head element and the pump in series with the solenoid valve. In addition, the solenoid valve was of a normally open type.

In addition, an overflow sensor was provided that does not respond to a small amount of ink overflow, but responds immediately only to a large amount of ink overflow, as a countermeasure against overflow.

[Function] When the structure described above is adopted, due to the presence of the check valve, there is no need to operate the solenoid valve except during ink non-discharge recovery operation, and sequence control is significantly simplified and power consumption is reduced. It is possible to significantly reduce heat generation.

[Example] Hereinafter, the present invention will be described in detail based on the example shown in the drawings.

Figures 1 to 8 illustrate one embodiment of the present invention.
Components in the figure that are the same as those in FIG. 9 are designated by the same reference numerals, and their explanations will be omitted. In this embodiment, the solenoid valves A to C are of a normally open type.

FIGS. 2 and 3 explain the overall color printer to which the present invention is applied, and are exemplified as an on-demand type printer that employs a bubble jet method.

In the figure, the reference numeral 20 is an upper unit, which accommodates a head unit as described later.

The lower side of this upper unit 20 is a lower unit 21, which houses a power supply section.

A removable drain tank 2 is installed on the outside of the lower unit 21.
2 is attached so that it can be seen from the outside.

A paper feed unit 24 is attached to the front side of the upper unit 20 via a hinge 23 so as to be openable and closable.

A flap 25 is detachably attached to the upper part of the front side of the paper feed unit 24.

This flap 25 is a lid that covers the paper discharge port and is removed by the operator during actual printing.

An operation panel 26 is provided adjacent to this flap 25.

Moreover, what is indicated by the reference numeral 27 is a pocket, and this pocket 27 accommodates manuals and the like.

Furthermore, an opening 28 is formed in the lower part of the front side of the paper feed unit 24 for viewing the remaining amount of recording paper.

A stacker 29 formed by bending steel wire or the like is provided at the bottom of the paper feed unit 24.

In addition, a base unit) 30 is attached to the lower end of the lower unit 21.
is installed.

A paper feeding mechanism 31 is provided inside the paper feeding unit 24, and a storage space 32 for recording paper is provided below the feeding mechanism 31.

Further, the upper unit 20 serves as a housing for the heating unit, and a bubble jet assembly (hereinafter abbreviated as BJA) 33 is removably attached to the upper part.

Further, a cap 34 is attached to the front side of the BJA 33 so as to be movable up and down.

BJA33 has a structure as shown in FIG.

That is, the BJA 33 is assembled with a strong frame 34 as a reference, and is detachably attached to the upper space of the upper unit 20.

Four bubble jet units (hereinafter abbreviated as BJU) 35 to 38 are detachably attached to the frame 34 toward the front side thereof.

In this example, these BJUs 35 to 38 are arranged in order from top to bottom: black, cyan, magenta, and yellow.

Each BJU35 to 38 has a plurality of Herad elements 1.
Each head element l has a large number of nozzles, for example 128 (not shown).

The head elements 1 are arranged in a staggered manner in two stages, upper and lower, in each of the BJUs 35 to 38, but the nozzles are arranged so that they do not overlap in the upper and lower positions.

A second ink tank 12 filled with ink corresponding to each color is detachably attached to the lower stage of the BJUs 35 to 38.

Although not shown in FIG. 4, the second ink tank 12 is connected to the first ink tank 7 provided on the back side of the BJA 33.

This connection is automatically made by simply installing the second ink tank 12.

Fans 39 for sending cooling air are attached to both left and right ends of the frame 34 of the BJA 33.

The BJA 33 having such a structure is detachably installed in the upper frame 20 by grasping the left and right handles 34a of the frame 34, and when installed, it is attached to the upper frame 20 via the connector 4o provided at the rear end of the frame 34. automatically connected to the power side terminal on the side.

Note that the reference numeral 41 is a knob for locking and unlocking the connector 40.

On the other hand, what is indicated by the reference numeral 42 in FIG. 4 is a cap cover, which is attached to cover the BJUs 35 to 38.

This cap cover 42 is attached to BJA3
This is the case when attaching and detaching 3.

That is, the diameter of the nozzle formed in the head element 1 is extremely small, and there is a risk that the nozzle will become clogged just by touching it with a fingertip or the like.

It is always installed when handling BJA33.

Incidentally, the cap 34, which can be raised and lowered freely, is constructed as shown in FIGS. 5 and 6.

In other words, the cap 34 is assembled based on a strong frame 43, and is provided so as to be freely raised and lowered by a drive device (not shown), and is placed in a position covering the BJA 33 and completely away from the BJA 33 downward as shown in FIG. It is installed so that it can be raised and lowered freely.

The cap 34 accommodates ink absorbers 44 to 47 that cover the head elements 1 of the BJUs 35 to 38, respectively.

Each of the ink absorbers 44 to 47 has a support frame 5 fixed to an arm 49 rotatably supported on the frame 43 via a shaft 48.
A diaphragm plate 51 is arranged below the ink absorbers 44 to 47, and this diaphragm plate 51 is fixed to the tip of another arm 52.

The reference numeral 53 is a stopper with which the rear end of the arm 52 comes into contact.

Further, a lever 54 is arranged on the outer edge of the frame 43 so as to be vertically movable up and down.

One end of four arms 56 is rotatably supported on this lever 54 via a pin 55, and the other end of the arm 56 is connected to the shaft 48.

The lower end of the lever 54 is rotatably supported on the tip of a rotating arm 58 which is rotated by a motor 57 via a pin 59.

Therefore, when the motor 57 is rotated and the rotating arm 58 is rotated, the lever 54 is lowered and the shaft 4 is rotated via the arm 56.
8 is rotated.

As a result, as shown in FIG. 6, the support frame 50 descends via the arm 49, and the arm 52 hits the stopper 53 and cannot move, so the aperture plate 51 rises and the ink absorber 44
This will narrow down the results.

Then, when the lever 54 eventually rises, it returns to its original state.

6th rI! In J, each part is shown as an irregular sectional view explaining the operation of the absorber 44 over time from the top.

Note that due to the rotation of the arm 49, the ink absorber 44 performs an arcuate movement, so in the middle of the movement, the two
As shown in the row, the ink absorber is head element 1.
It comes into contact with the nozzle part of the ink, absorbs ink, and the absorbed ink is squeezed out.

On the other hand, each ink absorber 44 to 47 is housed in a long and narrow room partitioned by an inclined partition plate 60 as shown in FIG. A cover 61 is fixed.

The flat space formed by this cover 61 serves as a path for the squeezed ink to descend, collect in the lowest ink reservoir indicated by reference numeral 62 in FIG. In FIG. 5, the reference numeral 43a indicates the cover of the cap.

On the other hand, FIG. 1 schematically shows an ink flow path of a printer having the above-described structure.

In the example shown in FIG. 1, as is clear from comparison with FIG. 9, a check valve 64 is provided in the flow path 8 connecting the head element and the pump side. This check valve 64 has a structure that allows ink to pass toward the head element 1 side.

Furthermore, an overflow sensor 65 that also serves as a breather is attached to the end of the tube 10 on the side of the first ink tank 7 that is open to the atmosphere via the electromagnetic valve B.

This overflow sensor 65 has a structure as shown in FIG.

As shown in FIG. 8, this overflow sensor 65 has a container 66 of a predetermined shape, and this container 66 is filled with an ink absorber 67 having a predetermined capacity.

The other end of the tube 10 extending from the first ink tank 7 is connected to the space above the absorber 67.

A drop lid 68 is placed on the top surface of the ink absorber 67, but this may be omitted.

Further, a pair of electrodes 6 are arranged inward from the upper end of the container 66.
9.70 is provided protruding a predetermined distance.

In addition, an air hole 71 is formed at the upper end of the container 66, through which air is sucked when a predetermined pressure is reached.
A breather membrane 72 that is discharged is stretched.

This is for adjusting the pressure of the air chamber in the first ink tank 7 which is communicated via the tube 10.

An overflow sensor employing such a structure has the following functions.

That is, when there is no malfunction in the apparatus, ink may come out little by little from the tube 10 due to fluctuations in pressure within the flow path.

Such minute amounts of overflow ink fall onto the upper side of the dropper lid 68 and are absorbed by the absorber 67 through the gap between the dropper lid 68 and the container 66.

Therefore, there is no short circuit between the electrodes 69 and 70.

However, if some kind of failure occurs and a large amount of overflow ink is discharged from the tube 10, the ink will accumulate on the upper side of the drop M2S faster than the ink can be absorbed into the absorber 67 through the gap in the drop lid 68, and the ink will accumulate on the top of the drop M2S. 69.
Since 70 is short-circuited, an overflow condition can be immediately detected, and an overflow accident can be interrupted at an early stage by stopping or closing the pump or solenoid valve.

Next, the operation of this embodiment configured as above will be explained.

When stored for a long period of time, the BJA 33 is removed from the upper unit 20 of the apparatus before being transported and set at the user's side.

In the removed state, all solenoid valves A to C are mechanically closed, and the connector 40 is also separated, so the current to the motor is cut off and the pump is stopped.

On the other hand, when the BJA 33 is housed in the upper unit 20, the solenoid valves A-C are automatically and mechanically opened, and are in a state of configuring their respective flow path systems.

However, the pump remains stopped.

In this state, the device is in standby state.

The states of the solenoid valves and pumps in each of the above-mentioned states are shown in the upper column of Table 2.

Table 2 (C→Close, 0→Open) In addition, the states of the solenoid valves and pumps during the various operations described below are shown in the lower column of Table 2.

The operation in each mode will be described below with reference to Table 2.

1) Circulation mode As mentioned above, this mode is used to supply ink to each head element or to remove air bubbles in the head element or ink flow path when the device is in the stun/pull state. This mode is used when refreshing the ink inside them at the same time.

In this state, as shown in Table 2, all the solenoid valves are open, the cap 34 rises and covers the front surface of the BJA 33, and the ink absorbers 44 to 47 are pressed against the respective head elements 1. It is in a state.

In this state, the pump P rotates in reverse, and the ink sucked from the first ink tank 7 passes through the flow path 8 via the solenoid valve C9 and the check valve 64, and passes through the distributor flow path 5. The ink is supplied to the head element 1 side through the flow path 3, and is pushed out from the nozzle, as well as flowing through the flow path 2. Distributor flow path 4
through the solenoid> first ink tank 7 through the flow path 6 equipped with the valve A.
It circulates to.

Due to this ink circulation, ink is supplied to the head element side, and air bubbles in the head and ink flow path are collected in the first ink tank 7, and from the upper air chamber to the tube 10. The air is guided to the overflow sensor 65 side which also serves as a breather via the electromagnetic valve B, and is discharged to the outside from the air hole 71.

2) Print mode This mode is a mode in which ink necessary for recording is supplied from the first ink tank 7 to the head element L side. In this case, as shown in Table 2, all solenoid valves are open and the pump is turned off. It's stopped.

Since the inkjet printer in this example is an on-demand type, no pressure is applied to the ink during recording.
The pump is therefore not activated.

In this mode, as the ink is ejected from the head element 1, the head element side becomes negative pressure, so the ink passes through the flow path 6 and the solenoid valve A, and the ink flows through the distributor flow path 4. It is supplied to the head element 1 via the flow path 2, and recording is performed based on a recording command.

3) Supply mode This mode is a mode for supplying ink from the second ink tank 12 to the first ink tank 7, and is applied when the device starts to be used and when the amount of ink in the first ink tank 7 decreases. be done.

In this mode, all solenoid valves A-C are
is open and the pump is rotated forward.

Therefore, the ink from the second ink tank 12 is transferred to the check valve 11. Because the first ink is drained through pump P,
Even if pressure is applied to the ink by the pump concubine, no ink reflux occurs.

Note that the cap 34 also rises at this time, and the absorbers 44 to
47 is in a state of being pressed against the head element l.

4) Pressure mode This mode applies pressure to the ink when the ink in the nozzle is dry or the nozzle is clogged.
This is a so-called non-discharge recovery mode in which ink is pushed out from the nozzle to remove a non-discharge state of ink.

In this case, as shown in Table 2, only A of the solenoid valves is closed, the others are open, and the pump is reversed.

At this time, the ink in the first ink tank 7 is pumped
, through the flow path 8 via the solenoid valve C9 check valve 64, and the distributor flow path 5. It passes through the flow path 3 and is supplied to the head element l side.

At this time, since the electromagnetic valve A is closed, no ink circulation occurs and the ink is guided to the nozzle side of the head element, and the ink is ejected from the nozzle to remove the clogging.

Of course, the cap 34 also rises at this time, and the absorber 44
47 are in a state of being pressed against the head element 1.

By the way, in addition to being able to operate the printer according to various states or modes of the device as shown in Table 2 above, the printer shown in this embodiment also has the following functions.

That is, one of them is that if the liquid level does not rise in the above-mentioned supply mode, it means that the ink on the second ink tank 12 side has run out. can.

Furthermore, even if the second ink tank 12 runs out of ink, a certain amount of ink is reserved in the first ink tank 7, so there is no need to interrupt print output while replacing the second ink tank 12. Does not occur.

Further, due to the presence of the above-mentioned overflow sensor 65, even if a large amount of overflow occurs, necessary parts of the device can be immediately stopped to prevent a major accident from occurring.

[Effects] As is clear from the above description, according to the present invention, a check valve that allows ink to flow only toward the head side is provided in series with the solenoid valve in the middle of the flow path connecting the head element and the pump. At the same time, all solenoid valves are of the normally open type, so the number of solenoid valve operations is significantly reduced, sequence control can be significantly simplified in both hardware and software, the power consumption of the solenoid valves is drastically reduced, and heat generation is also prevented. be able to.

Furthermore, by providing the above-mentioned check valve, pressure fluctuations caused by the operation of the electromagnetic valve are reduced, and there is no influence on the head side, so that inconveniences such as ink leakage do not occur.

Furthermore, since the structure is equipped with an overflow sensor that can distinguish between a small amount of overflow and a large amount of overflow caused by an accident, it is possible to immediately detect an overflow caused by an accident and prevent a major accident due to an overflow.

[Brief explanation of drawings]

Figures 1 to 8 illustrate one embodiment of the present invention.
Figure 1 is an explanatory diagram of the ink flow path system, Figures 2 and 3 are an external perspective view of the printer and a perspective view of the paper feed unit in an open state, Figure 4 is a perspective view of the BJA, and Figure 5 is a perspective view of the printer. The figure is a perspective view of the cap, FIGS. 6 and 7 are a vertical cross-sectional side view and a side view of the cap, FIG. 8 is a vertical cross-sectional side view of an overflow sensor, and FIG. 9 is an explanatory diagram of a conventional ink flow path system. . l...Head element 2.3, 5, 6, 8. ... Channel 7 ... First ink tank 12 ... Second ink tank 20 ... Upper unit 21 ... Lower unit 24
...Paper feed unit 33...BJA34...Cap 35-38...BJU44-47.67.
...Ink absorber 64...Check valve 65...Overflow sensor 69.70...Electrode thickness ω Figure 1 Picture price 4171 ' r trout food 1 draw 5th picture Dan 5 O J father "One low, 70-zoi's busy farewell @ Showa 8th ko 1"<4...+"I'r'/jh@1°J6i111
Figure 7

Claims (1)

[Scope of Claims] 1) A head element that discharges ink and performs recording, a recording flow path that communicates between the head element and one end of the first ink tank, and the first ink tank and the head. a flow path on the pump side that communicates with the element side via the pump and constitutes an ink circulation path together with the recording ink flow path via the head element and the first ink tank; and the first ink tank. In an inkjet recording apparatus equipped with a second ink tank that supplies ink to the recording ink flow path and a tube that releases the first ink tank to the atmosphere, a normally open electric A normally open electric opening/closing means is provided in the middle of the ink flow path on the pump side and between the pump and the head element, and a check that allows ink to pass only from the pump side to the head element side. An inkjet recording device characterized by having valves interposed in series. 2) An absorber for absorbing a small amount of ink leakage is provided at the outer end of the tube that releases the first ink tank to the atmosphere, and a pair of electrodes are short-circuited through the ink in case of a large amount of ink leakage. 2. The inkjet recording apparatus according to claim 1, further comprising an overflow sensor serving as a breather.