JPH0639167B2 - Inkjet device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The invention of the present application relates to a liquid jet recording apparatus such as an ink jet recording apparatus, and more particularly to a mechanism for preventing clogging of the apparatus, which prevents retreat of a meniscus due to a capping operation, and The present invention relates to a liquid jet recording apparatus that can reduce the discharge of recording liquid.

2. Description of the Related Art A liquid jet recording apparatus such as an ink jet recording apparatus has advantages such as direct recording, easy colorization, low noise, and the like, and has attracted attention as a new recording means.
However, heretofore, this type of recording apparatus has a drawback that the volatile substance in the recording liquid at the tip of the ejection head evaporates and the viscosity of the recording liquid increases, and the ejection of recording liquid droplets becomes unstable. As a countermeasure against this, it has been proposed to prevent the evaporation by capping the injection head.

By the way, if the cap is simply capped, air is pushed into the ejection head at the time of capping, the meniscus retracts, and droplet ejection becomes unstable. In order to solve this problem, it is necessary to suck the recording liquid and the air again to restore the meniscus. However, in this case, the recording liquid is wasted.

Therefore, the first invention of the present application eliminates the above-mentioned drawbacks of the conventional liquid jet recording apparatus, and in order to prevent the air from flowing into the jet head at the time of capping, the air is supplied by the pressure generating means. An object of the present invention is to provide a liquid ejecting recording apparatus capable of preventing receding of a meniscus and reducing discharge of recording liquid by performing capping while sucking.

The second invention achieves the object of the first invention, and
To provide a liquid jet recording apparatus which prevents a back flow of jet head air and a backward movement of a meniscus when a capping is released by setting a time difference between the capping release operation and the recovery operation of a pressure generating means. With the goal.

According to a first aspect of the present application, a cap that covers a discharge port of an ejection head, a capping unit that moves the cap, a pressure generating unit that sucks the inside of the cap, and a suction inside the cap are performed. An inkjet device comprising: a unit that operates the capping unit.

According to a second aspect of the invention, in addition to the above features, the inkjet device is provided with a unit that controls the pressure generating unit to return to an initial state after the cap is separated from the ejection head. .

In the present invention, capping means that the space including the ejection port of the inkjet head is hermetically sealed by using a cap, which will be clear from the contents described later.

In the above, the citation of the specific examples described below does not limit the scope of the invention of this application in any way, and the invention of this application can appropriately change its embodiment within the scope of the claims.

In this specification, recording means printing of characters and / or recording of images.

Hereinafter, the configuration and operation of a specific example of the liquid jet recording apparatus according to the first invention of this application and a specific example of the liquid jet recording apparatus according to the second invention of this application will be described in detail with reference to the drawings.

Configuration of Specific Example of Liquid Jet Recording Apparatus According to First Invention of this Application (FIGS. 1 to 3) FIG. 1 is an overall configuration of a specific example of the liquid jet recording apparatus according to the first invention of this application. In the figure, 1 is a liquid ejecting head unit, 2 is a recording liquid tank (hereinafter referred to as an ink tank), and 3 is a tube connecting the head unit 1 and the ink tank 2. Reference numeral 4 denotes a pump (pressure generating means capable of making the pressure outside the discharge port smaller than the pressure inside the discharge port), which is connected to the head unit 1 by a tube 5. Explaining the internal structure of the pump 4, 6 is a cylinder and 7 is a cylinder 6.
, 7a is a through hole provided in the piston 7, and 7b is a valve, and the flow path resistance of these is set sufficiently smaller than that of a tube 13 described later. Reference numeral 8 is a spring that biases the piston 7 upward, and 9 is a tube that is connected to a waste liquid tank (not shown).

Reference numeral 10 is a pulse motor capable of open control, and 11 is a capping device (cap for capping the ejection port of the inkjet head), which is biased by a spring 12 in the direction of the head unit 1.
a and a lever 1 fixed to a gear (means for performing capping after the operation of the pressure generating means) 14 described later.
The position is restricted by the contact with 4a. Therefore, the capping device 11 slides by the rotation of the lever 14a caused by the rotation of the pulse motor 10, and caps the tip of the head unit 1. 13 is a capping device 1
1 is a tube which is held by No. 1 and connects the pump 4 and the head unit 1.

14 is a gear that works with the pulse motor 10, 14a is a gear 1
4 is a lever that is fixedly mounted on and rotates integrally with the lever. 1
Reference numeral 5 denotes a slide lever, which has a rack portion 15a that engages with the gear 14 and elongated holes 15b and 15c, and responds to rotations of the pulse motor 10 and the gear 14 along pins 16a and 16b implanted in the fixed portion of the device. Slide. Slide lever 15
The lower part of 2 has two step shapes 15f and 1 due to chamfered parts 15d and 15e.
It is 5g.

FIG. 2 shows details of the capping device 11 and the head unit 1, and 11b is an end portion of the capping device 11, which is made of rubber, for example. Reference numeral 17 is an ejection head, 17a is an orifice portion including its orifice (hereinafter also referred to as “ejection port”), 18 is a sub tank for storing a recording liquid (hereinafter, also referred to as ink), and 19 is an ink in the sub tank 18. Shows. Head unit 1 as mentioned above
When the cap is capped by the capping device 11, the end
11b and the tip region of the injection head 17 come into contact with each other, and the orifice portion 17a is capped. In this case, simply capping causes the meniscus to retract due to the air around the orifice portion 17a, as described above. In addition, injection head 1
As is well known, 7 ejects ink droplets by contraction movement of an electromechanical conversion element such as a piezoelectric element or application of a heat pulse, whereby recording is performed.

FIG. 3 is a block diagram of the control system of the liquid jet recording apparatus shown in FIGS. 1 and 2, 101 is a control circuit, and 102 is a driver of the pulse motor 10. R, ST and E
ND indicates a recovery signal, a recording start signal and a recording end signal, of which the R signal is generated, for example, by a manual operation of the operator when the meniscus retracts due to vibrations caused by movement of the apparatus. .

Operation of Specific Example of Liquid Jet Recording Apparatus According to First Invention of this Application (FIGS. 1 to 4) Next, also referring to FIG. 4, the liquid jet recording apparatus according to the first invention of this application The operation of the specific example will be described.

(1) When the recording is completed and the END signal is input to the control circuit 101, the driver 102 rotates the pulse motor 10 in the normal direction by an amount corresponding to the pulse number N ₁ (steps 201 to 20 in FIG. 4).
2. In the following, the drawing number is omitted and only the step number is displayed. ) Pulse motor 10 and gear 1 that works together
When 4 rotates, the lever 14a rotates clockwise and the spring 1
2, the capping device 11 slides to the right in FIG. 1, and at the same time the slide lever 15 slides to the left, so that the chamfered portion 15d pushes the piston 7 and the piston 7 descends. As the piston 7 descends, the air around the capping device 11 flows into the upper chamber of the pump 4 via the tube 13. Then, the end portion 11b of the capping device 11 caps the tip of the injection head 17, and the first step portion 15f of the slide lever 15 and the upper end of the piston 7 come into contact with each other to stop the air suction.

Here, the slide lever 15 is held at the level shown in FIG. 1A. For that purpose, even if the drive current of the pulse motor 10 is cut off, it may be held by the torque without turning off the excitation, or by the piston. The position of the slide lever 15 may be held by the force of 7 being biased upward by the spring 8. On the other hand, the capping device 11 has a spring 12
It remains crimped to the head unit 1. According to the above capping operation, capping is performed while sucking air, so that the meniscus does not recede, and ink is hardly discharged by evaporation or suction of ink.
Therefore, there is no fear that the recording will become unstable at the next recording, and good recording can be performed.

(2) Next, when the recording start signal ST is input to the control circuit 101, the driver 102 reverses the pulse motor 10 by an amount corresponding to the pulse number N ₁ (steps 203 to 204). This causes the gear 14 to rotate in the opposite direction to that described above, and the gear 14 and the rack 14
The lever 15 moves due to the engagement with 15a and returns to the initial position. At the same time, the lever portion 14a of the gear 14 moves the capping device 11 against the spring 12 to the left in FIG. 1, and removes the cap of the head unit 1. In this case, since the flow path resistance of the through hole 7a and the valve 7b is smaller than that of the tube 13, the backflow of air in the tube 13 is prevented, and therefore the meniscus does not recede. In this state, recording is performed by known means. (Step 20
5) (3) On the other hand, the meniscus may retreat due to vibration caused by replacement of the ink tank 20 or movement of the apparatus, which makes ink ejection unstable. Therefore, the R signal is controlled manually by a control circuit 10
When the value is input to 1, the driver 102 causes the pulse motor 10 to rotate in the normal direction by an amount corresponding to the number of pulses N ₂ which is larger than the above-mentioned N ₁ . (Steps 206-207). As a result, the slide lever 15 slides and moves until the second step 15g comes into contact with the piston 7. In this case, the capping is completed at the first step 15f and the injection head 1 at the second step 15g.
Ink is sucked from the discharge port at the tip of 7, and the meniscus is forcibly restored. The piston 7 is at the level indicated by B in FIG.

Next, when the ST signal is input, the pulse motor 10 rotates by an amount corresponding to the number N ₂ of pulses, the capping is released in the same manner as described above, the piston 7 returns, and recording is performed in this state. (Steps 208-210) The pump 4 is 3
It is also possible to generate a pressure equal to or higher than the step and control the ink suction amount.

In the apparatus of FIGS. 1 to 3 embodying the invention of this application, it is the negative pressure generating operation of the pump 4 described in (1) that operates simultaneously with the capping operation of the capping apparatus 11. In the operation described in (3), the capping has already been completed, and the pump 4 does not operate at the same time as the capping operation. The description of the claims should be understood as above.

Specific Example of Liquid Ejection Recording Apparatus According to Second Invention of this Application (FIG. 5) In the apparatus of FIG. 4, during the capping releasing operation,
The backflow of the air in the tube 13 is prevented and the meniscus is prevented from retreating due to the difference in the flow path resistance between the tube 13 and the valve 7b, etc. In the specific example of the second invention shown in FIG. By providing a time lag between the capping releasing operation and the operation of returning the pressure generating device to the initial state, the pressure generating device is returned to the initial state after the cap is removed to prevent the retreat of the meniscus more reliably.

Members shown in FIG. 5 by the same reference numerals as those in FIG. 1 have basically the same configuration and function as those in FIG. The tube 3 is connected to an ink tank (not shown) as in the device shown in FIG. The main features of the device of FIG.
The point is that the following lever 24 and slide lever 25 are provided. That is, the lever 24 is rotatable about the shaft 24a in conjunction with the pulse motor 10 and is in contact with the protruding portion 11a of the capping device 11. On the other hand, the slide lever 25 has its engaging portion 25a engageable with the claw portion 24b of the lever 24, and is provided with elongated holes 25b and 25c so that the pins 16a and 16b planted in the fixing portion of the device can be provided. They are fitted together. The lower part of the slide lever 25 is provided with a chamfer 25d and a step 25e. A clearance l is provided between the claw portion 24b of the lever 24 and the engaging portion 25a of the slide lever 25.
(Means for setting a time difference so as to recover the pressure generating means after the capping is released). The operation will be described later.

In the structure shown in FIG. 5, the lever 24 rotates clockwise around the shaft 24a by the forward rotation of the pulse motor 10, and the capping device 11 slides to the right in the drawing by the spring 12 and, together with this, the slide lever 25. Slides to the left and is pushed by the chamfered portion 25d, the piston 7 descends, and the air around the capping device 11 flows into the upper chamber of the pump 4 through the tube 13. Then, the end of the capping device 11 caps the tip of the injection head in the head unit 1. At the same time, the stepped portion 25e of the slide lever 25 and the upper end of the piston 7 come into contact with each other, and air suction is stopped. The slide lever 25 holds its position in the same manner as the device of FIG.

Next, as in the apparatus shown in FIG. 1, when the pulse motor 10 is reversely rotated by the same amount as described above, for example, by inputting a recording start signal, the lever 24 rotates counterclockwise, and the capping apparatus 11 resists the spring 12. Then slide to the left and the capping is released. On the other hand, the slide lever 25 does not move until the cap is released by the clearance 1 between the claw portion 24b of the lever 24 and the engaging portion 25a of the slide lever 25. This is to prevent the air inside the tube 13 from flowing back and the meniscus retracting when the piston 7 moves in the capped state. When the lever 24 rotates by an amount corresponding to the clearance l, the slide lever 25 returns to the initial position and recording is performed by a known means. The device shown in FIG. 5 is also a specific example of the first invention of this application.

EFFECTS OF THE INVENTION As described in detail above, according to the first invention of this application, since the capping means is operated while suctioning the inside of the cap, air is sucked by the pressure generating device. While carrying out the capping, prevent air from flowing back to the injection head during capping.
It is possible to prevent the meniscus from retreating and reduce the discharge of the recording liquid.

According to the second aspect of the invention, the interlocking means further includes means for controlling the pressure generating means to return to the initial state after the cap is separated from the ejection head, so that air is ejected from the ejection head when the capping is released. It is possible to reliably prevent the meniscus from retreating back to the back.

[Brief description of drawings]

FIG. 1 is a schematic view of a specific example of a liquid jet recording apparatus according to the first invention of this application, FIG. 2 is a sectional view showing the details of the capping device and the liquid jet head in the apparatus of FIG. 1, and FIG. FIG. 4 is a block diagram of the control system of the apparatus of FIG. 1, FIG. 4 is a flow chart explaining the operation of the apparatus of FIG. 1, and FIG. 5 is a specific example of the liquid jet recording apparatus according to the second invention of this application. It is a schematic diagram. In the figure, 1 is a liquid jet head unit, 2 is an ink tank,
4 is a pump, 7 is a piston, 8 is a spring, 10 is a pulse motor, 11 is a capping device, 12 is a spring, 14 is a gear, 14a is a lever that rotates integrally with the gear 14, 15 is a slide lever, and 15a is its Rack part, 15f is its first step part, 15g is its second step part, 17 is an injection head, 17a is its orifice part, 24 is a lever, 24b is its claw part, 25 is a slide lever, and 25a is its engagement. Part, 101 is a control circuit, 10
2 is a driver for the pulse motor 10, R is a recovery signal, ST is a recording start signal, END is a recording end signal, and 1 is a clearance.

Claims (4)

[Claims] 1. A cap covering an ejection port of an ejection head, a capping means for moving the cap, a pressure generating means for sucking the inside of the cap, and a means for operating the capping means while sucking inside the cap. An inkjet device comprising: 2. The ink jet apparatus according to claim 1, wherein the pressure generating means has means for generating pressure stepwise to control the suction amount. 3. A cap for covering a discharge port of an ejection head, a capping means for moving the cap, a pressure generating means for sucking the inside of the cap, and a means for operating the capping means while sucking inside the cap. And a unit that controls the pressure generating unit to return to the initial state after the cap is separated from the ejection head. 4. The ink jet apparatus according to claim 3, wherein the pressure generating means has means for generating pressure stepwise to control the suction amount.