JP2701553B2 - Ink supply device for inkjet recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink supply apparatus for an ink jet recording apparatus, and more particularly to adjustment of physical properties of an ink in an ink circulation system in a charge control type ink jet recording apparatus.

[0002]

2. Description of the Related Art An ink jet recording apparatus of a charge control system is configured to collect and reuse (circulate) ink ejected from nozzles that has not been used for recording. However, ink collected without being used for recording needs to be adjusted in viscosity (adjusted in physical properties) because the solvent of the ink evaporates while flying in the air and the viscosity increases. This viscosity adjustment is performed by supplying a solvent to the ink circulation system.

[0003] Such a conventional apparatus is disclosed in Japanese Patent Laid-Open No. 57-70667.
And JP-A-56-19765.

[0004]

However, in this type of conventional apparatus, the diffusion speed of the solvent supplied to the ink for viscosity adjustment is increased to prevent the viscosity of the ink from becoming uneven. Or, there is no consideration for preventing precipitation of the pigment when the ink uses a pigment for coloring, and even when the ink is provided with a viscosity measuring container, the viscosity measuring container is filled with the ink. It takes a long time, and there is a problem that viscosity measurement cannot be performed frequently. Therefore, conventionally, especially in the field of an industrial ink jet recording apparatus using a quick-drying ink based on a solvent system, it has been impossible to accurately and frequently adjust the physical properties of the ink to improve the print quality.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an ink jet recording apparatus capable of obtaining better print quality, and in particular, to provide an ink physical property adjusting means in an ink circulation system in a charge control type ink jet recording apparatus.

[0006]

According to the present invention, an overflow container having a smaller capacity than the ink holding container is provided at an upper portion of the ink holding container, and the ink in the ink holding container is circulated from the bottom to the overflow container. A circulation agitation flow path is provided, and a part of the ink sent from the circulation agitation flow path enters the ink holding container through a natural flow-down flow path for allowing the ink to flow naturally from the lower part of the overflow container. The ink is configured to overflow from the upper side of the overflow container and flow down into the ink holding container.

[0007]

The ink in the ink holding container is always supplied into the overflow container by the circulation stirring channel, and overflows from the upper portion of the overflow container. Therefore, since the ink level in the overflow container can be maintained at a certain height, the ink liquid in the overflow container is closed by closing the circulation stirring channel or by stopping the pumping means for pumping the circulation stirring channel. The surface becomes only natural flow,
A value corresponding to the viscosity of the ink can be obtained by measuring the flowing time by the liquid level detecting means.

In addition, since the ink in the ink holding container and the ink in the overflow container are stirred by circulating in the circulation stirring channel, the supplied solvent and the precipitated pigment are constantly stirred to make the physical properties of the ink uniform. can do. Therefore, the adjustment of the physical properties of the ink becomes accurate, and the printing quality is not reduced.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an ink circulation system of an ink jet recording apparatus according to the present invention.

In the ink holding container 1, a maximum level L1a of the amount (liquid level) of the ink held in the container is set.
The liquid level detector 3 is provided with three electrodes for detecting the reference level L1b and the lowest level L1c, and the ground electrode 2 of each electrode, that is, a total of four electrodes. The liquid level detector 3 detects whether or not there is ink up to the position (level) of the electrode by determining whether or not the ink forms an electric circuit between the electrodes. Limit level for prevention, reference level L1b
Is a reference level for keeping the amount of ink in the ink holding container 1 constant, or before the ink viscosity measurement, and the minimum level L1c is monitored so that a diaphragm 4 described later does not come out of the ink in the ink holding container 1 ( (To prevent the diaphragm 4 from drying).

An ink circulation stirring pipe 5 led out from the lowermost part of the ink holding container 1 is connected to an overflow container 9 with a filter 6, a pressure pump 7 and a solenoid valve 8 interposed in this order. The ink circulation stirring pipe 5 is connected to a conductive pipe 10 (specifically, a stainless steel pipe) at a connection portion with the overflow container 9.
Is led to the inside of the ink natural downflow pipe 11 derived from the lowermost part of the ink. Here, the tip of the conductive pipe 10 is set to be always in the ink. In the overflow container 9, there is a liquid level detector 13 having a low level sensor electrode 12 for detecting the low level L9 of the ink liquid level when measuring the ink viscosity. The ground electrode of the low level sensor electrode 12 is , The conductive pipe 10. That is, the ground electrode 2 and the ink holding container 1
Whether or not an ink is present up to the position (level) of the internal ink, the conductive pipe 10, the ink in the overflow container 9, and the low-level sensor electrode 12 is determined by forming an electric circuit.

The ink that has entered the overflow container 9 passes through a spontaneous ink flow-down pipe 11 that is led out from the lowermost portion of the overflow container 9, and is returned to the ink holding container 1 after its flow rate is adjusted by the throttle 4. Further, since the amount of ink passing through the throttle 4 is set smaller than the amount of ink supplied by the pressure pump 7, the ink overflows from the upper portion of the overflow container 9 and returns to the ink holding container 1. Here, an oblique cut portion 9a is provided above the overflow container 9 so that the ink in the overflow container 9 overflows only from there. The purpose of providing the cut portion 9a is to make the surface area of the overflowing ink flow that comes into contact with air as small as possible and to suppress the amount of ink solvent volatilized. Alternatively, a groove may be formed in the side surface of the overflow container 9 following the cut portion 9a of the overflow container 9, so that the overflowed ink may flow down only the groove.

After the ink supply pipe 14 branches off from the front of the filter 6 of the ink circulation stirring pipe 5, the solenoid valve 15
, A pressurizing pump 16, a filter 17, a pressure regulating valve 18, a pressure gauge 19, and a solenoid valve 20.
It is connected to the.

An ink supply pipe 23 led out of a supply ink holding container 22 for storing and holding supply ink is connected between the electromagnetic valve 15 and the pressure pump 16 via an electromagnetic valve 24. Connected to. A solvent supply pipe 26 led out of a solvent holding container 25 that holds and holds an ink solvent used for ink physical property adjustment includes a filter 27, a pressure pump 28, a solenoid valve 29, and a throttle 30 for flow rate adjustment.
Is connected to a collecting pipe 32 to be described later between a gutter 31 and a filter 33 to be described later. In some cases, the throttle 30 may not be needed due to the relationship between the flow rates of the pressurizing pump 28 and the recovery pump 34. Specifically, the flow rate of the collection pump 34 is set to be larger than the total flow rate of the ink ejected from the nozzle 21 and the solvent sent by the pressure pump 28, and the electromagnetic valve 2
Even when 9 is in the open state, if the ink captured by the gutter 31 can be sufficiently recovered, the diaphragm 30 is not required.

The ink ejected from the recording nozzle 21 that is not used for recording is captured by the gutter 31. The collection pipe 32 led out from the gutter 31 is connected to the ink holding container 1 with a filter 33 and a collection pump 34 interposed in this order.

Further, in order to operate the liquid level detector 3 in the ink holding container 1 stably, a partition is provided to prevent the ink liquid level in the ink holding container 1 from being disturbed by the ink returned from the collection pipe 32. A plate 35 is provided to divide the inside of the ink holding container 1 into the collection tube 32 and the liquid level detector 3.

The controller 36 controls the liquid level detector 3
And 13 from the recording nozzle 21
And solenoid valves 8, 15, 20, 24, 29 and pressurizing pump 7,
16, 28 and the recovery pump 34 are controlled.

Next, recording control and ink physical property adjustment control will be described with reference to FIGS.

FIG. 2 is a flowchart of a control process executed by the control device 36 for recording control. The recording control is performed by storing a predetermined amount of ink (reference level L1) in the ink holding container 1.
It starts with b) satisfied.

First, at step 210, pump control is executed, the pumps 7, 16, and 34 are put into operation, and the pump 2 is operated.
8 remain dormant. Here, the pressure pumps 7, 1
If pumps 6, 28 are of a type that shares a drive source, for example, a pump drive motor, and are provided with protection such as a safety valve that does not increase the pressure above a certain value, all pumps are kept in operation. You may.

Next, at step 220, the solenoid valves are controlled to open the solenoid valves 8, 15, 20 and keep the other solenoid valves 24, 29 closed. Step 21
0, 220 may be operated in the same step.

With the above processing, the supply of ink to the recording nozzle 21 is started. As a result, the ink in the ink holding container 1 is supplied to the electromagnetic valve 15, the pressure pump 16, and the filter 17.
, A pressure regulating valve 18, a pressure gauge 19, and an electromagnetic valve 20 in order to reach a recording nozzle 21, which is ejected from a nozzle hole of the recording nozzle 21, and a part of the ejected ink is used for image (character) recording. Ink not used for recording is gutter 3.
1 and the ink captured by the gutter 31 is collected by the collection pump 34 through the collection tube 32.
Return to

Next, at step 230, a timer for issuing a timing for adjusting the physical properties of the ink is started. In step 240, it is determined whether the timer value has reached the set timer value. If the timer value has not reached the set timer value, the flow proceeds to step 250 to start printing control.

In the print control of step 250, counting of ink particles (print dots) used for recording is started.
This count value is used to control the replenishment amount of new ink to be replenished during ink physical property adjustment control described later. After that, other control processing is executed in step 260.

When the timer value set in step 240 is reached, the process proceeds to step 270 to start control for adjusting the physical properties of the ink in the ink holding container 1.

FIG. 3 is a flowchart of a control process executed by the control device 36 for the ink physical property adjustment control.

In step 271, ink replenishment control for replenishing the amount of ink used for recording is executed. In this control, the electromagnetic valve 15 is closed and the electromagnetic valve 24 is opened to supply ink to the recording nozzle 21 from the supply ink holding container 22. The ink not used for recording is collected from the gutter 31 through the collection tube 32 and into the ink holding container 1. When the replenishment of the consumed ink amount is completed, step 2
At 72, the pump 28 is operated and the solenoid valve 29 is opened, and the solvent is replenished until the ink amount in the ink holding container 1 reaches the reference level L1a. If the driving source of the pump 28, for example, the pump driving motor is shared with the motors of the pumps 7 and 16, only the solenoid valve 29 is opened and the solvent is supplied until the ink amount in the ink holding container 1 reaches the reference level L1a. I do. Thus, the amount of ink in the ink holding container 1 becomes the reference level L1a.

Next, when the electromagnetic valve 8 is closed in step 273, the ink is supplied to the overflow container 9, so that the ink in the overflow container 9 starts to flow naturally. After the electromagnetic valve 8 is closed, the timer for viscosity measurement is started, and the amount of ink in the overflow container 9 is set to the low level L9.
Measure the time until. The pump 7 may be in an operating state as long as the pump 7 is provided with a protection such as a safety valve whose pressure does not increase above a certain value.

In step 274, the viscosity of the ink is estimated based on the natural flow time of the ink obtained from the timer, and it is compared whether the estimated ink viscosity is a specified value. If the viscosity is high, in step 275, the pump 28 is operated and the solenoid valve 29 is opened by an amount corresponding to the ink viscosity to supply the solvent. If the viscosity is low, proceed to step 276. In step 276, nothing is performed this time, and the control in step 271 is performed until the amount of ink in the ink holding container 1 reaches the reference level L1b under control after the control program has completed one cycle. Hereinafter, step 272 is omitted and step 27 is omitted.
Move to 3.

FIG. 4 is a block diagram of an ink circulation system of an ink jet recording apparatus according to another embodiment of the present invention.
Here, only portions different from the embodiment of FIG. 1 will be described.

In the embodiment shown in FIG. 1, the ink in the ink holding container 1 is supplied with a solenoid valve 15, a pressurizing pump 16 and a filter 17.
, The pressure regulating valve 18, the pressure gauge 19, and the electromagnetic valve 20 are sequentially interposed and are always supplied to the recording nozzle 21. In the embodiment of FIG. 4, the ink supply container 39 is provided between the ink holding container 1 and the electromagnetic valve 15. It has. In the ink circulation system of the embodiment shown in FIG. 4, only the ink whose physical properties have been adjusted in the ink holding container 1 operates so as to be sent into the ink supply container 39.
For example, in a normal operation, the solenoid valve 8 is opened and the solenoid valve 38 is opened.
Is in the closed state, and the ink in the ink supply container 39 is supplied to the nozzle 21. When the amount (level) of the ink in the ink supply container 39 reaches the minimum level L39a,
The lowest level is detected by the liquid level detector 40, and the control for adjusting the physical properties of the ink in the ink holding container 1 is started using this as a trigger. The ink physical property adjustment control is the same as the control content of FIG. 3 described above. When the adjustment of the physical properties of the ink is completed in the ink holding container 1, the electromagnetic valve 8 is closed and the electromagnetic valve 38 is opened, so that only the ink whose physical properties have been adjusted is sent to the ink supply container 39. This ink transfer is performed until the liquid level detector 3 in the ink holding container 1 detects the minimum level L1c. Therefore, only the ink whose physical properties have been adjusted is held in the ink supply container 39.
1 is supplied with only ink whose physical properties have been adjusted. Also,
According to this method, only the ink whose physical properties have been adjusted can be supplied to the nozzles 21 irrespective of the amount of ink in the ink circulation system. Can be supplied to the nozzle 21.

The liquid level detector 40 also has an electrode for detecting a limit limit level L39b for preventing overflow.

The ink circulation system of the embodiment shown in FIG. 4 is provided with a liquid level detector 41 for detecting that the amount of replenished ink remaining in the replenished ink holding container 22 is low. In this apparatus, when the liquid level detector 41 detects the minimum level L22 of the liquid level, an alarm is displayed and an alarm signal is output to the outside.

The ink circulation system of the embodiment shown in FIG. 4 is provided with a liquid level detector 42 for detecting that the amount of the solvent remaining in the solvent holding container 25 is low. Considering the use of a solvent having low conductivity, a float type level detector is used here. A nozzle washing pipe 43 is branched between a pressure pump 28 and a solenoid valve 29 from a solvent supply pipe 26 led out from the solvent holding container 25, and a solenoid valve 44 is provided.
Is connected to the check valve 45 via a. When the electromagnetic valve 44 is opened in the present ink circulation system, the solvent is supplied to the nozzle 21, so that the nozzle 21 can be cleaned. By automatically cleaning the nozzle 21 when the ink is stopped, the ink can be automatically stopped, and the handling property is improved.

The check valve 45 includes, in addition to the nozzle cleaning pipe 43, the ink supply pipe 14, the ink circulation pipe 46, and the nozzle 21.
And are connected. The check valve 45 has a function of preventing the ink in the ink supply pipe 14 from mixing with the solvent in the nozzle cleaning pipe 43 or the ink or solvent in the ink circulation pipe 46.

The ink circulation pipe 46 is connected to the ink holding container 1 via a solenoid valve 47. By opening the solenoid valve 47, the ink can be circulated without passing through the nozzle 21, so that the ink can be quickly filled up to the flow path immediately before the nozzle 21.

Further, from the ink supply pipe 14, the electromagnetic valve 2
The depressurizing pipe 48 is branched between 0 and the check valve 45, and is connected to the collecting pipe 32 between the gutter 31 and the filter 33 via an electromagnetic valve 49. The pressure release pipe 48 is a flow path for releasing the pressure of the ink in the ink supply pipe 14 when the pressure pump 16, the filter 17, the pressure regulating valve 18, the pressure gauge 19, and the solenoid valve 20 are maintained. Pressure pump 1
6, the pressure of the ink is quickly released by stopping the electromagnetic valve 49.

The above operations are all controlled by the controller 36.

[0040]

As described above, according to the present invention, since the inside of the overflow container for measuring the viscosity is always in the overflow state, it is always in the standby state for measuring the viscosity, and the overflow immediately after measuring the viscosity. Since it can be in a state, viscosity measurement can be performed with high frequency even when a quick-drying ink is used. In addition, by constantly circulating the ink in the ink holding container to the overflow container by the circulation stirring channel, the supplied solvent and the precipitated pigment can be stirred, and the physical properties of the ink can be made uniform.
Accordingly, the adjustment of the physical properties of the ink becomes accurate, and the effect that the print quality is not reduced is obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram of an ink circulation system according to an embodiment of the present invention.

FIG. 2 is a flowchart of processing of recording control and ink physical property adjustment control executed by a control device.

FIG. 3 is a flowchart of a process of controlling the control of physical properties of ink executed by the control device.

FIG. 4 is a block diagram of an ink circulation system showing another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Ink holding container, 3 ... Liquid level detector, 4 ... Restrictor, 5 ... Ink circulation stirring tube, 7 ... Pressurizing pump, 9 ... Overflow container, 10 ... Conductive pipe, 11 ... Natural ink downflow tube, 13 ... Liquid level detector, 16 ... Pressure pump, 21 ... Nozzle, 22 ... Refill ink holding container, 25 ...
Solvent holding container, 28 ... Pressure pump, 31 ... Gutter, 34
... Recovery pump, 36 control device, 39 ink supply container, 40 liquid level detector, 41 liquid level detector, 42 liquid level detector, 45 check valve.

Claims (7)

(57) [Claims] An ink holding container, a supply means for supplying the ink held in the ink holding container to a recording nozzle, and collecting and ejecting ink ejected from the recording nozzle that has not been used for recording. In an ink supply apparatus for an ink jet recording apparatus comprising: an ink recovery unit for returning the ink to the ink holding container; and an ink property adjusting unit for replenishing the recording holding container with new ink and / or an ink solvent. An overflow container having a smaller capacity than the ink holding container provided in a positional relationship in which the ink overflowing from above and flowing down into the ink holding container under natural flow, and the bottom of the ink in the ink holding container. A circulating agitating flow path for circulating the fluid into the overflow vessel, and an inlet flowing through the circulating agitating flow path. A natural flow path configured to flow ink at a flow rate smaller than the flow rate, a liquid level detecting means for detecting a liquid level in the ink holding container and the overflow container, and the liquid level detection A control device for controlling the circulation stirring channel based on a detection output of the means. 2. The ink jet printer according to claim 1, wherein the control device estimates the viscosity of the ink based on a liquid level detection output of the ink holding container and the overflow container, and controls the ink physical property adjusting means. An ink supply device for an inkjet recording device. 3. A liquid level detecting means according to claim 1, wherein said liquid level detecting means is provided in said ink holding container and overflow container.
An ink supply device for an ink jet recording apparatus, wherein each ink supply device comprises a pair of electrodes. 4. The ink jet printer according to claim 1, wherein the flow rate restricting means provided in the natural flow path below the overflow container comprises a restrictor, and the restrictor is located at a position such that the restrictor is always in the ink in the ink holding container. Installed in the overflow container and extends the circulation stirring channel for circulating the ink in the overflow container to the natural flow-down channel, and a portion of the circulation stirring channel in contact with the ink in the overflow container is electrically conductive. An ink supply device for an ink jet recording apparatus, comprising a pipe, wherein the conductive pipe is used as a ground electrode for detecting a liquid level in the overflow container. 5. A low-level detecting means according to claim 4, wherein a low-level detecting means is provided in said ink holding container, and a detecting position of said low-level detecting means is set at a position higher than a lower end of said conductive pipe and higher than said throttle. Then, when the ink in the ink holding container becomes the low level or becomes lower than the low level, the control device operates in conjunction with the ink physical property adjusting means so as not to become lower than the low level, or issues an alarm signal, or An ink supply device for an ink jet recording apparatus, which displays an alarm. 6. The overflow container according to claim 1, wherein an upper portion of the overflow container is obliquely cut, or a groove is provided in a part of an upper portion of the overflow container, and the overflowed ink passes through a limited portion of the overflow container. An ink supply device for an ink jet recording apparatus, wherein the ink supply device is configured to fall down. 7. An ink recovery container according to claim 1, wherein said ink recovery container includes an ink recovery flow path for returning the ink recovered by said ink recovery means into said ink storage container and said liquid level detection means. An ink supply device for an ink jet recording apparatus, comprising a partition plate for separating.