JPH0358306B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a so-called inkjet device, and more particularly, to an inkjet device having means for reliably supplying recording liquid and preventing clogging of an ejection head. .

BACKGROUND ART Inkjet recording devices are attracting attention as a new recording technology because they have advantages such as direct recording, easy colorization, and negligible noise. In particular, on-demand type inkjet recording devices are inexpensive and can be made compact, and are becoming central to the full-color printer technology that has been attracting attention recently.

However, conventionally, this type of recording device has a complicated ink supply system to the ink jet head, and the viscosity of the ink increases due to the evaporation of volatile substances in the ink at the tip of the head, which maintains the stability of ink ejection. The drawback was that it was difficult to do.

First, regarding the ink supply system, various means have been proposed in the past, but the representative ones are:
One is a configuration in which the ink tank and the head are connected by a highly flexible tube, and the other is a configuration in which the ink tank is disposed on a head carriage and the ink tank and the head are directly connected. However, in the former case, the tube drags as the head moves during recording, which causes problems with the durability of the tube itself, and also causes instability in carriage feeding due to load fluctuations caused by tube movement, i.e. (i) (ii) Instability of ink ejection due to incomplete ink supply due to variations in tube flow path resistance or air bubbles mixed into the tube; and (iii) Maintaining the relative position of the head and ink tank. Therefore, there are many design constraints, which makes it difficult to optimally design equipment. On the other hand, the latter method increases the load on the carriage motor by loading a sufficient amount of ink for recording into the head cartridge, which increases the size and cost of the entire device, and also causes problems such as ink leakage when changing the ink cartridge. This has the disadvantage of staining the user's hands and equipment. These drawbacks become even more noticeable in an apparatus configured to hold a plurality of types of ink having different ink densities in order to improve image quality.

Next, as means for preventing clogging, capping means and means for discharging ink from the leading end of the head to prevent drying of the leading end of the head have been proposed and have been effective.
However, the configuration in which these operations are performed manually has disadvantages such as poor operability and instability of ink ejection due to forgetting capping. As the amount of residual ink in the ink tank decreases accordingly, special means must be provided to detect the amount of remaining ink.Furthermore, these means must be provided separately from the ink supply system, resulting in an increase in the size of the equipment. However, there are disadvantages of high costs.

Purpose of the Invention The present invention provides an inkjet device which eliminates the above-mentioned drawbacks of conventional recording devices of this type, can reliably supply recording liquid with a simple configuration, and can prevent clogging of the ejection head. The purpose is to

In addition, this invention prevents the ink accumulated in the cap from dripping as it is and staining the inside and outside of the device, or the ink accumulated in the cap adhering to the ejection opening surface of the head during capping and disturbing the ink ejection direction. Another object of the present invention is to provide an inkjet device that does not cause problems such as ejection failure caused by ink accumulated in a cap or pressure disturbance that becomes a hindrance to suction recovery due to ink accumulated in a cap. .

More specifically, in the embodiment of the present invention, the pressure generated by the pressure generating means is changed depending on whether the recording liquid is supplied to the recording liquid storage chamber of the head unit or when only the meniscus return operation of the ejection head is performed. By controlling the supply amount of the recording liquid, it is possible to reliably supply the recording liquid with a simple configuration and prevent clogging of the ejection head.

Structure of the Invention The present invention provides a cap that can be in a sealed state in which an ejection port for ejecting ink is sealed from the atmosphere and an open state in which the ejection port is exposed to the atmosphere; and a cap for sucking ink from the ejection port through the cap. a pressure generating means for generating a pressure of; operating the pressure generating means when the cap is in the open state, stopping the operation to bring the cap into the sealed state, and then operating the pressure generating means; It is characterized by comprising a control means for restarting the operation.

In the above, the citation of the specific examples described later does not limit the scope of the present invention in any way, and the embodiments of the present invention can be modified as appropriate within the scope of the claims.

Note that in this specification, recording refers to printing of characters and/or recording of images, and the recording liquid is sometimes referred to as ink.

Hereinafter, with reference to the drawings, a specific example of the inkjet recording apparatus (liquid jet recording apparatus) according to the present invention will be described in detail, including the overall configuration, the configuration of the capping device and the liquid jet head unit, the configuration of the pump, the configuration of the control system, and the order of their operations. Explain in detail.

Overall Configuration of Liquid Jet Recording Apparatus (FIG. 1) In FIG. 1, numeral 1 indicates a platen that is interlocked with a paper feeding mechanism (not shown). 2 is a liquid ejecting head unit, the details of which will be described later. A carriage 3 is driven by a carriage motor 4 along a screw 5 and a guide 6 in the direction of the arrow. These control mechanisms are well known and are not related to the gist of the invention of this application, so detailed explanations will be omitted.

7 is a capping device, and 8 is a pump, the details of which will be described later in connection with FIGS. 2 and 3, respectively. 9 is a pulse motor for driving the pump, 10 is a worm gear, and 11 is an electromagnetic clutch. The worm gear 10 is interlocked with the motor 9 via the electromagnetic clutch 11 and drives the cam 15. 12 is a capping device driving motor;
13 is a worm gear, 14 is a capping device 7
a wheel fixed to the worm gear 1
3 is interlocked with the motor 12 and meshes with the wheel 14 to drive the capping device 7. 16 is a large capacity recording liquid tank (hereinafter referred to as an ink tank), 1
7 is a suction tube that connects the pump 8 and the capping device 7, 18 is a supply tube that connects the ink tank 16 and the capping device 7, and 19 is the tip (also 32) of the ejection head (32 in FIG. 2).
20 is a waste liquid tube that connects the pump 8 and the waste liquid tank 21, SW1 is a detection switch that detects the initial position of the carriage 3, and PA is a recording paper.

Structure of Capping Device and Liquid Ejecting Head Unit (FIG. 2) FIG.
3 is a sub-tank for storing a predetermined amount of ink necessary for recording a predetermined number of sheets; 32 is a known ejection head; 32a is a tip thereof; 33 is an ink supply port;
4 is a suction port that controls the pressure inside the sub tank 31 and discharges ink, and also serves as a level pointer 34a.
It functions to keep the initial amount of ink supplied to the sub tank 31 constant. 35 is sub tank 3
1 shows the ink stored in 1.

Reference numeral 36 denotes the main body of the capping device 7, which is fixed to the recording device main body (not shown). 37 is a cap made of a material such as rubber; 38 is a movable member to which the cap 37 is fixed; the movable member 38 is fitted with the main body 36 by a guide (not shown); is driven in the direction of the arrow. A spring 39 urges the movable member 38 toward the head unit 2. In addition, 1 in the figure
7, 18 and 19 indicate the suction tube, supply tube and recovery tube, respectively, as in FIG.

Configuration of Pump (FIG. 3) FIG. 3 is a sectional view showing details of the pump 8.
In the figure, 41 is a piston that fits into a cylinder 42, and O-rings 41a, 41b, 41c and 41d.
This is hermetically sealed and urged upward by a spring 43. 44 and 45 are first and second connecting holes, respectively, and these connecting holes have greater fluid resistance than the valve passage, and the piston 41
It is located at the bottom of the A valve 46 is made of an elastic member, and a portion thereof is fixed to the piston 41. 47 is a waste liquid discharge port.

Configuration of control system (Fig. 4) Fig. 4 shows a block diagram of the control system, 100 is a recording device control circuit, and in addition to the usual digital control section, a CNT counter 100a, an _n1 counter 10
0b, n ₂ counter 100c, W register 100
d, includes a timer 100e. CNT counter 10
The functions of timers 0a to 100e will be described later. Reference numeral 101 denotes a recording device driving circuit which transfers an end signal to the control circuit 100 in response to the end of recording;
On the other hand, a recording start signal is given from the control circuit 100. 102 is a signal output circuit that transfers a high level signal to the control circuit 100 when the initial position detection switch SW1 of the carriage 3 is activated, and 103 is a signal output circuit that transfers a high level signal to the control circuit 100 when the recovery switch _SW2 is activated. This is a signal output circuit that transfers signals to

Reference numerals 104, 109, 111 and 112 are drivers for the carriage motor 4, pump drive pulse motor 9, electromagnetic clutch 11 and capping device drive motor 12, respectively, and are controlled by a control circuit 100. 113 is a remaining ink warning indicator for the large capacity ink tank 16 (FIG. 1), and 114 is its driver. Reference numeral 115 is a potentiometer that detects the position of the piston 41 (Fig. 3), and 116 is a level detector. Depending on the output level of the potentiometer 115, the piston 41 is located at the bottom dead center, intermediate center, or top dead center. The control circuit 100 determines whether the position is at the bottom dead center, sets the signal S ₁ to high level when it is at the bottom dead center, sets the signal S ₂ at the middle point to a high level, and sets the signal S ₃ at the top dead center to a high level, and sends these signals to the control circuit 100.
Enter. 117 is the capping device 7 (first
It is a detector that detects the position of 1
Reference numeral 18 denotes a signal output circuit that outputs a high level signal when the recording start switch SW3 is pressed, and the output signal is transferred to the timer 100e and the like. Note that in place of the remaining ink amount warning display 113 in the above, a display device that displays the remaining amount itself may be provided. Operation of a specific example of the liquid jet recording apparatus according to the present invention (FIGS. 1 to 5) Next, the operation of the apparatus shown in FIGS. 1 to 4 will be explained with reference also to the flowchart of FIG. 5.

(1) Recording liquid supply and meniscus return operation When the recording of a preset predetermined number of sheets is completed, the CNT counter 100a outputs a signal indicating this and is reset itself (step 212 in FIG. 5B. (The drawing number is omitted and only the step number is displayed.) In response to this signal, the _n1 counter 100b counts up "1", and the carriage motor driver 104 drives the carriage motor 4 to return the carriage 3 to its initial position (steps 221-222). The return of the carriage 3 is confirmed by the initial position detection switch SW1, and the capping motor driver 112 drives the capping device drive motor 12 by the high level output of the signal output circuit 102, thereby causing the movable member 38 of the capping device 7 to move. The meshing between the worm gear 13 and the wheel 14 moves it to the tip of the head unit 2. As the movable member 38 moves, the suction tube 17 and the suction port 34, the supply tube 18 and the ink supply port 33, and the recovery tube 19 and the tip 32a of the liquid ejecting head are respectively engaged. In this state, the capping position detector 117 operates to confirm that the capping position is present, and the capping motor driver 112 is turned off. Even if the capping motor driver 112 is turned off, the cap 37
is pressed toward the tip of the head unit 22 by the spring 39, and the above-mentioned engagement is not released (steps 223-226).

Next, the pump motor driver 109 and the clutch driver 111 are operated to operate the pump driving pulse motor 9 and the electromagnetic clutch 1.
1 to rotate the gear 10 and therefore the cam 15 (step 227). As the cam 15 rotates, the piston 41 of the pump 8 begins to descend, and the upper chamber of the pump 8 becomes under negative pressure. This negative pressure becomes maximum when the piston 41 reaches the bottom dead center.

In this process, the pressure inside the sub-tank 31 becomes negative through the suction port 34, and ink is accordingly supplied from the ink tank 16 to the sub-tank 31 via the supply port 33 and the supply tube 18. Along with this, the tip 3 of the injection head
Ink is sucked from 2a through the recovery tube 19 to restore the meniscus of the head.

This suctioned air and ink restore the pressure in the upper chamber of the pump 8, and the sub tank 31
The internal pressure is also restored by supplying ink. Here, the level pointer 34a is set so that a predetermined pressure is restored when the ink level reaches the pointer. Even if excess ink remains in the sub-tank 31 depending on the recording state and exceeds the level pointer 34a, it is discharged as excess ink to the pump 8 via the discharge port 34 and the suction tube 17. For this reason, sub tank 3
A certain amount or more of the air inside 1 is reliably retained,
By setting the level pointer 34a at a position lower than the head tip 32a, pressurized printing will not occur, pressure fluctuations caused by the movement of the head unit 2 can be suppressed by the damper effect of air, and the meniscus of the head tip 32a can be suppressed. Since it has also recovered, good records can be made.

On the other hand, air and discharged ink from the head unit 2 are sent to the upper chamber of the pump 8 via the suction tube 17 and the second connecting hole 45. piston 4
1, the valve 46 is closed due to the pressure increase in the lower chamber, so the previously discharged ink, etc. that has accumulated in the lower chamber is discharged to the discharge port 47 and the waste liquid tube 20.
It is discharged to the waste liquid tank 21 through. When the piston 41 reaches the bottom dead center, the signal _S1 becomes high level, and upon confirming this, the pump motor driver 109 and the clutch driver 111 are turned off, and the motor 9 is stopped. and piston 41
is held in its position by the holding force of a worm gear (not shown). (Steps 228-229).

During this holding period, the above operation is completed and the pressure in the upper chamber is restored. After confirming that the predetermined time required for these has elapsed, the motor 9 is reversed,
Raise the piston 41 (step 230~
231). At this time, since the valve 46 opens, the air and waste ink in the upper chamber are sent to the lower chamber, but the connecting hole 44
There is no backflow to the head unit 2 because of the high fluid resistance of the fluids 45 and 45. The piston 41 is held by the spring 43 when it reaches the top dead center. Then the capping motor driver 112 operates again,
The capping device drive motor 12 is reversed,
By returning the movable member 38 to the initial position, the capping of the head unit 2 is released, the recording becomes possible, and the series of operations is completed (steps 232, 204 to 204).
208).

The liquid jet recording apparatus described above includes a large-capacity ink tank 16 and a small-capacity sub-tank 31 in the head unit 2, and ink is supplied from the ink tank 16 to the sub-tank 31 by a pump 8, which is a single pressure generating means. At the same time, meniscus recovery is performed by discharging ink from the tip 32a of the ejection head 32, so ink can be supplied accurately with a simple configuration, and since meniscus recovery is performed at the same time, stable recording can be achieved. Furthermore, since the ink supply and meniscus recovery are simultaneously performed using a single pressure generating means, it is possible to downsize the device and reduce manufacturing costs.

Furthermore, the above recording apparatus has an ink supply system (supply tube 18) in a single capping device 7.
and an ink suction system (recovery tube 19) for returning the meniscus, and are configured so that as the capping device 7 moves, these engage and separate from the ink supply port 33 and ejection head 32 in the head unit 2, respectively. Therefore, in combination with the above-mentioned configuration, it is possible to configure the fluid path for ink supply and meniscus return with a simple mechanism, and the above-mentioned operations can be performed reliably, resulting in high reliability. You can make improvements. Furthermore, since there is no extra load on the carriage motor 4 such as an ink supply tube during the recording operation, the inertia is reduced, the precision of carriage feeding is improved, and the motor can be made smaller. This greatly contributes to cost reduction. Furthermore, the degree of freedom in arranging the ink tank 16 is increased, and operability can be further improved.

Furthermore, since the above recording device is configured to automatically supply ink to the sub-tank 31 after recording a predetermined number of sheets, the ink tank is divided into a large-capacity main tank 16 and a small-capacity sub-tank 31. Ink can be supplied accurately even when the printer is in use, thereby making it possible to achieve the above-mentioned effects such as downsizing the device and improving operability.

(2) Operation of meniscus recovery only When the recovery switch SW2 is operated, the signal output circuit 103 outputs a high level signal to the _n2 counter 100c.
The _n2 counter 100c counts up "1". Subsequently, the pump motor driver 109 operates to drive the pump driving pulse motor 9, and move the piston 41 to
The piston 41 is moved from the position to the B position and stopped at the B position. Movement of the piston 41 is confirmed by the signal S2 becoming high level, and then the carriage motor driver 104 operates to drive the carriage motor 4 and return the carriage 3. The return of the carriage 3 is confirmed by the operation of the switch SW1, and the capping motor driver 112 is operated to rotate the capping device drive motor 12 in the forward direction, thereby engaging the capping device 7 with the head unit 2 (step
241-246). After confirming that the capping position has been reached (step 247), the operations starting from step 226 in Figure 5 are performed, but in this case, the piston 41 has already descended to position B in Figure 3. , unlike the case of ink supply described above,
Since the negative pressure in the upper chamber of the pump 8 is small, the ink supply to the sub-tank 31 is restricted to perform the meniscus recovery operation.

At this time, when the cap is in an open state in which the discharge port is exposed to the atmosphere, the pump, which is the pressure generating means, is operated, and the operation is stopped to shift the cap to a closed state in which the discharge port is sealed from the atmosphere. After that, suction recovery will be performed by restarting the pump operation. That is, the ink accumulated in the cap is discharged from the cap before suction recovery. That is, so-called empty suction is performed prior to suction recovery. Therefore, the ink that has accumulated in the cap may drip and stain the inside and outside of the device, or the ink that has accumulated in the cap may adhere to the ejection opening surface of the head during capping, resulting in ejection failure including disturbance of the ink ejection direction. Problems such as ink accumulated in the cap causing pressure disturbances that interfere with suction recovery do not occur.

The liquid jet recording device described above is configured to generate two levels of pressure by adjusting the position of the piston 41 in the pump 8, which is a pressure generating means, and thereby control the amount of ink supplied from the ink tank 16 to the sub tank 31. Therefore, by switching the generated pressure between the ink supply operation and the operation that only returns the meniscus, a considerable part of the mechanism for both operations can be shared, and both operations can be performed reliably. Accordingly, it is possible to avoid complication of mechanisms for ink supply and meniscus recovery and deterioration of operability in the recording apparatus.

(3) Automatic capping operation When recording of one sheet is completed, the timer 100e starts operating in response to an end signal from the recording device drive circuit 101. The timer 100e outputs a signal from the signal output circuit 118 by operating the recording start switch SW3.
It is reset by the signal output by Therefore, if recording of information to be recorded is started within the set time of the timer 100e, no capping operation is performed and normal recording is performed. On the other hand, if recording is not started within the set time, only the above-mentioned meniscus recovery operation is performed (steps 201 to 205). However, although the pump 8 returns after the meniscus returns (step 231), the capping device 7 does not evacuate and the recording start switch is turned off.
The evacuation is performed only by operating SW3 (steps 204 to 208). As a result, the tip 32a of the ejection head 32 is uncapped for the first time at the start of recording, thereby preventing it from drying out. This point also applies to the other operations described above.

(4) Ink remaining amount detection operation In the above-mentioned recording device, the supply amount w ₁ during one ink supply and the ink supply amount w ₂ during meniscus return operation are always constant, and the initial capacity in the ink tank 16 Since W is also constant, when n ₁ and n ₂ are the number of times of ink supply and meniscus return operation, respectively, and W' is the remaining amount of ink, W' = W - (n ₁ w ₁ + n ₂ w ₂ ) …(1) holds true. Therefore n ₁ counter 10
Equation (1) is calculated from the count values of the 0b and _n2 counters 100c, and the remaining amount of ink can be determined from the result.

Specifically, n ₁ for the previous count value W ₁
Every time the counter 100b or _n2 counter 100c counts up, the contents of the W register 100d are updated to W _{= W1-} ( _n1w1 + _n2w2 ), and compared with the reference value _V , W< If it is V, the remaining amount warning driver 114 is operated to display a warning on the remaining amount warning display 113. As described above, instead of the warning display 113, a display device that displays the remaining amount itself may be used.
If a warning is displayed, the ink tank 16 is replenished with ink and the W register 100d is reset (steps 251 to 255).

According to the above configuration, it is possible to easily know whether or not the ink tank 16 needs to be refilled, and not only can incomplete recording due to running out of ink be prevented, but also a special device is not required to detect the remaining amount of ink. This makes it easy to detect the amount of ink remaining even in devices that use a large amount of different types of ink, such as multi-color recording devices, making the device more compact and improving operability. be able to.

In the apparatus shown in FIGS. 1 to 4, a pump 8, which is a pressure generating means, generates two levels of pressure, and this generated pressure causes the ink tank 16 to flow into the sub tank 3.
Although the amount of ink supplied to the ink tank 1 is controlled, the generated pressure can be set in three or more levels, and a plurality of pressure generating means can be provided.

As described in detail above, according to the embodiment of the present invention, a first recording liquid storage chamber with a large capacity and a second recording liquid storage chamber with a small capacity are provided to generate at least two levels of pressure. Since the pressure generating means controls the amount of recording liquid supplied from the first recording liquid storage chamber to the second recording liquid storage chamber, the generated pressure can be increased by, for example, the recording liquid supply operation and the operation that only returns the meniscus. By switching, a considerable part of the mechanism for both operations can be shared, and both operations can be performed reliably. Therefore, compared to conventional devices, which required separate mechanisms for recording liquid supply and meniscus recovery, and which inevitably increased the size of the device and decreased reliability and operability, the structure is simpler and more reliable. It is possible to perform various operations necessary for liquid jet recording, improve reliability and operability, and reduce manufacturing costs.

Effects of the Invention As detailed above, in the present invention, when the cap is in the open state where the discharge port is opened to the atmosphere, the pump, which is the pressure generating means, is operated, and the operation is stopped to remove the discharge port from the atmosphere. Suction recovery is performed by moving the cap to an airtight state and then restarting the pump operation. That is, the ink accumulated in the cap is discharged from the cap before suction recovery. That is, so-called empty suction is performed prior to suction recovery. Therefore, the ink that has accumulated in the cap may drip and stain the inside and outside of the device, or the ink that has accumulated in the cap may adhere to the ejection opening surface of the head during capping, resulting in ejection failure including disturbance of the ink ejection direction. An excellent effect can be achieved in that problems such as ink accumulated in the kit do not cause pressure disturbances that interfere with suction recovery can be achieved.

[Brief explanation of drawings]

The drawings show a specific example of the liquid jet recording apparatus according to the present invention. FIG. 1 is a perspective view showing the overall structure of the liquid jet recording apparatus, and FIG. 2 shows details of the head unit and capping device in the apparatus shown in FIG. 1. 3 is a sectional view showing details of the pump, FIG. 4 is a block diagram of the control system, and FIGS. 5A and 5B illustrate the operation of the apparatus shown in FIGS. 1 to 4. One set of flowcharts to illustrate, Figure 6, Figures 5A and 5
It is a figure which shows the arrangement of figure B. In the figure, 2 is a liquid injection head unit, 3 is a carriage, 4 is a carriage motor, 7 is a capping device, 8 is a pump, 9 is a pulse motor for driving the pump, 10 is a worm gear, 12 is a motor for driving the capping device, 15 is a cam, 16 is a large capacity ink tank, 17 is a suction tube, 18 is a supply tube, 19 is a recovery tube, 31 is a sub tank,
32 is an ejection head, 32a is its tip, 33 is an ink supply port, 34 is a suction port, 37 is a cap, 3
8 is a movable member, 39 is a spring, 41 is a piston, 4
3 is a spring, 46 is a valve, 113 is a remaining amount warning indicator,
SW1 indicates a detection switch that detects the initial position of the carriage 3.

Claims (1)

[Scope of Claims] 1. A cap capable of being in a sealed state in which an ejection port for ejecting ink is sealed from the atmosphere and in an open state in which the ejection port is exposed to the atmosphere, and for sucking ink from the ejection port through the cap. a pressure generating means for generating a pressure of; operating the pressure generating means when the cap is in the open state, stopping the operation to bring the cap into the sealed state, and then operating the pressure generating means; An inkjet device comprising: a control means for restarting the operation.