JPH1034899A - Ink jet textile printing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To save wastful time and ink required for removing bubbles in an ink supply tube. SOLUTION: Ink is sent out of a liquid chamber 100 by a propeller 301 driven by a motor 303 to be send to a recording hard 200 through a supply tube 102a and returned to a liquid chamber by a return tube 102b to be circulated to discharge bubbles in the tube. The drive voltage of the motor is controlled to set the number of rotations of a propeller 301 so as to obtain pressure not discharging sent ink from a nozzle 201. By providing a pressure sensor or a bubble detection sensor to the supply tube 102a or driving them in combination with a flow sensor, further effective removal of the bubbles becomes possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus, and more particularly to an ink jet textile printing apparatus.

[0002]

2. Description of the Related Art A conventional ink jet recording method is a method of forming an image by discharging a single color ink or a plurality of color inks corresponding to color recording onto a recording material (paper, cloth, OHP paper, etc.). It is. An ink jet recording apparatus employing this method includes a carriage on which a recording head and an ink tank serving as recording means are mounted, a conveying means for conveying a recording material, and a control means for controlling these. Ink droplets are ejected from a plurality of ejection ports while serial scanning is performed in the direction (main scanning direction) orthogonal to the recording material transport direction (full scanning direction).
On the other hand, during non-recording, the recording material is intermittently conveyed by an amount equal to the recording width, thereby sequentially recording on the recording material. In this recording method, recording is performed by directly discharging ink onto a recording material in accordance with a recording signal.
It is widely used as an easy and inexpensive recording method.

[0003] However, when an ink jet recording apparatus is used for industrial purposes such as printing and printing, the printing duty is extremely high, so that the ink consumption is very large. For this reason, an ink jet textile printing apparatus that employs a method in which a liquid chamber having a large capacity is provided outside the apparatus and a tube or a pipe is piped from the liquid chamber to the recording head, and the liquid is sent from the liquid chamber to the recording head has been disclosed. It became publicly known. According to this method, it is possible to supply ink to the liquid chamber without stopping the recording apparatus.

In this type of ink jet printing apparatus, the liquid is generally sent from the liquid chamber to the recording head by utilizing the capillary phenomenon of fine nozzles of the recording head. Therefore, if air bubbles are present in the tube, an inappropriate pressure is generated between the liquid chamber and the recording head, so that ink is not properly supplied to the nozzles, and a malfunction such as non-ejection may occur. In particular, when the length of the tube that sends liquid from the liquid chamber to the recording head in such a printing apparatus is several tens of meters, there may be many bubbles in the tube. Liquid was sent from the liquid chamber to the recording head to remove bubbles in the tube.

[0005]

In the above-described conventional ink jet printing apparatus, the liquid is sent to remove the bubbles in the ink supply path, so that the bubbles are discharged from the nozzles of the recording head and the ink is also discharged. . Therefore, there is a disadvantage that a large amount of ink not used for recording is consumed, and the printing cost increases.In addition, since the presence of bubbles in the tube cannot be confirmed, regardless of the presence or absence of the bubble, a transfer for removing the bubble is performed. There is a disadvantage that the liquid has to be periodically applied and printing time is extra.

SUMMARY OF THE INVENTION An object of the present invention is to provide an ink-jet printing apparatus which does not unnecessarily consume ink and removes bubbles in a tube only when necessary.

[0007]

SUMMARY OF THE INVENTION An ink jet textile printing apparatus according to the present invention comprises a recording means for forming an image by ejecting ink droplets on a recording material based on an input image, and a carriage for mounting the recording means. And an ink supply device for supplying ink to the recording device, and a transport device for transporting the recording material, wherein the ink supply device includes a device for varying the ink supply pressure. .

A means for measuring the supply pressure is provided in the supply path of the above-mentioned ink supply means, and a return path of the ink from which the ink supply means returns from the recording means is provided. The pressure of the ink supplied to the recording means through the supply path is adjusted by means for varying the ink supply pressure, and at a predetermined pressure set so that the ink is not discharged from the nozzles of the recording means, the ink returns to the return path. It circulates through. By circulating the ink from the supply path to the return path, bubbles contained in the path are removed and the ink is not wasted.

Means for detecting the presence or absence of air bubbles are provided in the ink supply path, the ink is circulated to remove the air bubbles only when air bubbles are detected, and a flow meter is provided in the ink return path. Discharge of ink in the path is performed reliably and without waste.

The means for varying the ink supply pressure is performed by changing the number of revolutions of the motor of the pump for feeding the liquid, and the means for changing the number of revolutions is to change the drive voltage of the motor.
Alternatively, it is performed by changing the drive pulse signal.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIG. 1 is a block diagram showing main components of a first embodiment of the present invention. In the figure, a liquid chamber 100 is a container for storing ink, and supplies ink to a recording head 200. The air hole 101 is an air hole for keeping the ink in the liquid chamber 100 at atmospheric pressure. The nozzle 201 is a nozzle provided on the recording head 200 for discharging ink. The supply tube 102a
The tube for supplying ink from the liquid chamber 100 to the recording head 200 and the return tube 102b are tubes for returning ink from the recording head 200 to the liquid chamber 100. The propeller 301 is a propeller that functions to supply ink from the liquid chamber 100 to the supply tube 102a. Propeller 301
Is connected to a motor 303 for rotating the shaft 302. In this embodiment, a small DC motor is used as the motor 303. The motor 303 is driven by a drive circuit 400 that drives the motor.

The configuration of the drive circuit 400 will be described with reference to a block diagram. The drive circuit 401 is a circuit for driving a motor, the drive signal circuit 402 is a circuit for supplying a drive signal to the drive circuit 401, and the voltage control circuit 403 is a circuit for controlling a drive voltage. Information from a CPU (not shown) is received by a CPU interface 404, and is used as a drive signal and a drive voltage of a motor as a drive signal circuit 402,
The voltage is sent to the voltage control circuit 403.

In the above-described configuration, first, information for determining the drive voltage is sent from the CPU. This information changes the rotation speed of the motor by changing the voltage applied to the motor 303. The voltage control circuit 403 sets a drive voltage based on this information. In this embodiment, a voltage of about 15 V is applied to a DC motor rated at 24 V. Next, when a motor drive signal is sent from the CPU, the motor 303 rotates while the drive signal is applied, and rotates the propeller 301 through the shaft 302. The rotation of the propeller 301 causes the liquid chamber 100 to rotate.
From the recording head 200 via the supply tube 102a
Is supplied to the printer. The supplied ink returns to the liquid chamber 100 via the return tube 102b.

By circulating the ink as described above, the bubbles existing in the ink supply tube 102a and the return tube 102b are discharged to the liquid chamber 100 together with the flow of the ink and are discharged from the air holes 101.

The rotation speed of the motor 303 is
The pressure of the ink to be sent out was set to be low so that the ink supplied to the nozzle No. 00 was not discharged from the nozzle 201, whereby the applied voltage was set.

(Second Embodiment) Next, a second embodiment of the present invention will be described based on FIG. 2 with respect to portions different from the configuration shown in FIG. A pressure sensor 501 is provided on the ink supply tube 102a. Pressure sensor 501
An A / D converter 410 is added to the drive circuit 400 in order to convert this signal into a motor drive signal. Generally, the signal of the pressure sensor is generated as an analog voltage.
In the present embodiment, the analog voltage is converted into a digital signal using the A / D converter 410, and this digital signal is converted into a CP signal.
Feedback to U.

In the above-described configuration, the motor drive signal is sent from the CPU. This signal allows the motor 30
The rotation of the propeller 3 and the rotation of the propeller 301 to send out the ink are the same as in the first embodiment. Next, CPU
Reads the signal of the pressure sensor 501 converted into a digital signal and detects the pressure. Initially 24V rated voltage
Is applied, a pressure higher than a predetermined pressure is detected. The CPU sends information for determining the drive voltage based on the pressure data. Based on this information, a drive voltage is set to reduce the rotational speed of the motor and reduce the pressure.

The CPU reads the pressure signal converted into a digital signal again. Here, if the pressure is higher than the predetermined pressure, a signal for further reducing the driving voltage is transmitted, and if the pressure is lower than the predetermined pressure, a signal for increasing the driving voltage is transmitted. The CPU repeats this operation.

In this way, ink can always be sent out at a predetermined appropriate pressure. In addition, the setting of the delivery pressure can be easily changed. For this reason, air bubbles adhering to the wall surface of the tube, which operates at a constant delivery pressure and is difficult to remove in the first embodiment, can be easily removed.

In the present embodiment, the initial voltage is set to the rated voltage of 24 V. However, a low voltage may be set in advance and the voltage may be increased so as to reach a predetermined pressure.

(Third Embodiment) Next, a third embodiment of the present invention will be described with reference to FIG. In FIG.
A sensor 601 for detecting the presence or absence of bubbles in the tube is provided on the return tube 102b. In the present embodiment, a photo interrupter was provided near the liquid chamber 100, and the return tube 102b was passed through the photo interrupter. Other configurations are the same as those of the first and second embodiments.

Here, while the ink is being sent, the CPU
Detects the signal of the photo interrupter 601. When the return tube 102b is full of ink, the light of the photointerrupter is blocked, and conversely, when air bubbles pass, the light of the photointerrupter is transmitted. Drive circuit 40
0, the photo interrupter 601
And sends it to the CPU. The CPU determines the presence or absence of bubbles in the tube based on this signal.

On the other hand, the amount of ink in the liquid chamber, the tube, and the recording head is calculated in advance, and the amount of ink delivered from the liquid chamber per unit time is measured and obtained. be able to. The CPU drives the motor 303 with this time as one cycle to detect the presence or absence of bubbles in the tube. If a signal indicating the presence of air bubbles is detected within one cycle, the motor is driven again for one cycle to send out ink and remove air bubbles. When no air bubbles are detected in the tube, unnecessary operations need not be performed.

(Fourth Embodiment) Next, a fourth embodiment of the present invention will be described with reference to FIG. In FIG.
A flow sensor 701 is provided on the return tube 102b and measures the flow rate of the ink flowing therein. The flow rate sensor 701 includes an impeller that rotates in accordance with the flow of a fluid. The impeller has magnetism, and the Hall element senses the magnetism and converts a change in the magnetism into a pulse number proportional to the flow rate. And send it out. This pulse is counted by the pulse count circuit 430 and sent to the CPU. Some sensors for measuring the flow rate send a signal to the outside by voltage or current, but the drive circuit 400 may use a detection method suitable for each.

The pulse generation circuit 440 is a circuit that changes a drive pulse signal according to information from the CPU. By combining the pulse signal and the drive signal, the drive circuit 401
To send to. The timing chart is shown in FIG. The motor 303 is driven at a rotation speed according to the frequency of the pulse signal. In addition, sensors 601 for detecting bubbles are provided at two locations on the tubes 102a and 102b. Other specifications are the same as those in the first, second, and third embodiments.

In the present embodiment, the CPU changes the pulse signal for driving the motor 303 while checking the pressure at which the ink is delivered, so that the ink is not leaked from the nozzle 201, and the pulse of the flow meter is changed. The flow rate is confirmed from the number, and during that time, the presence / absence of bubbles is checked by sensors 601 provided at two places, thereby transmitting the drive information of the motor.

According to the present embodiment, since the sensors for checking the air bubbles are provided at two locations, by sending out half of the total ink amount in the liquid chamber, the tube and the recording head, the air bubbles in the entire ink supply system can be reduced. Check is possible. Further, since the ink delivery amount is accurately measured by providing the flow meter, the bubble check can be performed more reliably and without waste. In this embodiment, two sensors are provided.
If two or more sensors are provided, measurement can be performed in a shorter time.

[0028]

As described above, the ink jet printing apparatus according to the present invention has a variable ink supply pressure, a return circuit provided to circulate the ink, and a bubble detection sensor and a flow meter. Therefore, there is an effect that bubbles from the liquid chamber to the ink tube and the head can be reliably and efficiently removed without consuming waste ink.

[Brief description of the drawings]

FIG. 1 is a block diagram showing main components of a first embodiment of the present invention.

FIG. 2 is a block diagram showing main components of a second embodiment of the present invention.

FIG. 3 is a block diagram showing main components of a third embodiment of the present invention.

FIG. 4 is a block diagram showing main components of a fourth embodiment of the present invention.

FIG. 5 is a timing chart showing driving of the motor in FIG. 4;

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 liquid chamber 101 air hole 102a supply tube 102b return tube 200 recording head 201 nozzle 301 propeller 302 shaft 303 motor 400 drive circuit 401 drive circuit 402 drive signal circuit 403 voltage control circuit 404 CPU interface 410 A / D converter 420 detection circuit 430 pulse Count circuit 501 Pressure sensor 601 Bubble sensor / photo interrupter 701 Flow rate sensor

Claims (7)

[Claims] 1. A recording means for forming an image by ejecting ink droplets onto a recording material based on an input image, a carriage for mounting the recording means, and supplying ink to the recording means. Ink supply means for
An ink-jet printing apparatus comprising: a conveying unit for conveying the recording material; wherein the ink supply unit includes a unit for varying an ink supply pressure. 2. The ink jet textile printing apparatus according to claim 1, further comprising means for measuring a supply pressure in an ink supply path of said ink supply means. 3. The ink jet textile printing apparatus according to claim 1, wherein the ink supply unit has a return path of the ink from the recording unit. 4. The ink supply path according to claim 1, further comprising means for detecting the presence or absence of air bubbles in the supply path.
The inkjet printing apparatus according to any one of claims 1 to 7. 5. The ink jet textile printing apparatus according to claim 1, wherein the means for varying the ink supply pressure includes means for changing a drive voltage of a motor to control a rotation speed. 6. The ink jet printing apparatus according to claim 1, wherein the means for varying the ink supply pressure includes means for changing a drive pulse signal of a motor to control the number of rotations. 7. The ink jet printing apparatus according to claim 2, further comprising means for measuring a flow rate of the ink in the ink supply path.