JPH0348861B2 - - Google Patents

Description

[Detailed Description of the Invention] Technical field to which the invention pertains The invention of this application relates to a liquid jet recording device (inkjet recording device), and is directed to reliably preventing clogging of recording heads and thickening of recording liquid. The present invention relates to a liquid jet recording device (inkjet recording device) having a capping means capable of recording.

Prior Art A so-called inkjet recording device, which is a typical example of a recording device to which the invention of this application is applied, is
Direct recording is possible and colorization is easy.
It also has advantages such as negligible noise, and is attracting attention as a new recording technology. In particular, on-demand type inkjet recording devices
It is inexpensive and can be miniaturized, and is becoming a central player in full-color printer technology, which 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 evaporation of volatile substances in the ink at the tip of the head increases the viscosity of the ink, causing clogging and ink ejection. The disadvantage was that it was difficult to maintain the stability of Among these, as clogging prevention means, capping means and ink discharging means from the head tip to prevent drying of the head tip 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. Accordingly, the amount of residual ink in the ink tank decreases, making it necessary to provide special means to detect the amount of remaining ink.Furthermore, these means must be provided separately from the ink supply system, which increases the size of the equipment. However, there are disadvantages of high costs.

Furthermore, there is a drawback that during capping, the meniscus recedes due to insufficient outflow of air from the tip of the head, making ink ejection unstable.

Purpose of the Invention Therefore, the invention of this application is capable of reliably capping the recording head after a predetermined period of time has elapsed, and prevents the recording liquid from evaporating from the ejection opening at the tip of the recording head even if the recording head is left unused for a long time. The object of the present invention is to provide an inkjet recording device that can perform the following functions.

Another object of the invention of this application is to provide an inkjet device that can almost completely prevent malfunction of a timer for capping.

According to an embodiment of the present invention, the capping device is held at the capping position with the meniscus restored from its retreat during capping, thereby preventing clogging of the recording head and thickening of the recording liquid. equipment can be provided.

Structure of the Invention The inkjet device of the invention of this application includes a cap for covering an ejection port that ejects ink for recording, and a timekeeping operation that starts in response to a recording end signal and is reset when recording is resumed. The apparatus is characterized by comprising: a timer; and a control means for causing the capping to be performed when recording is not restarted within a set time of the timer.

This embodiment of the invention includes a capping device for the recording head; a device for restoring the meniscus of the recording head (also pump 8 in FIG. 3);
Means for maintaining the capping device in the capping state when the meniscus has returned (Similarly, after the meniscus has returned, the capping device 7 is engaged with the head unit 2 until a recording start signal is given, for example, from the signal output circuit 118 in FIG. 4). This is an inkjet device comprising: means for maintaining the state; and;

In the present invention, the recording end signal means a signal issued every time a predetermined amount of recording is performed. For example, if the recording medium is cut paper, it means the end of recording a predetermined number of sheets (one or more sheets) of cut paper, and if the recording medium is roll paper, it means the end of recording over a predetermined length. .

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

The invention of this application also applies to liquid jet recording devices that eject recording droplets from a jetting head by the movement of an electromechanical transducer (for example, a piezoelectric element) or the application of a heat pulse, as well as a liquid jet recording device that uses high viscosity, for example, oil-based recording liquid. It can also be applied to recording devices that use

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.

With reference to the drawings, a specific example in which the invention of this application is applied to a liquid jet recording device will be described below, including the overall configuration,
The configuration of the capping device and liquid injection head unit, the configuration of the pump, the configuration of the control system, and the order of their operations will be explained in detail.

Overall configuration of a specific example of a liquid jet recording apparatus to which the invention of this application is applied (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.
is a sub-tank that has at least the ink capacity necessary to record a predetermined amount of recording material, and here, the predetermined amount of recording material refers to the size and number of sheets for cut paper, and the width and width of roll paper. A recording medium whose recording amount is determined by its length. 32 is a known jetting head, 32a is its tip, 33 is an ink supply port, and 34 is a suction port, which controls the pressure inside the sub-tank 31 and discharges the ink, and has a level pointer 34a; It works to keep the amount of ink constant. 35 indicates ink stored in the sub tank 31.

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 the cylinder 42 and has 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 a higher fluid resistance than the valve passage and are arranged so as to be located below the piston 41. 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 other devices.

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 warning indicator for warning of the amount of ink remaining in the large-capacity ink tank 16 (FIG. 1), and may be an audible or visual indicator; 114 is the warning indicator 1;
13 drivers. 115 is the piston 41
a potentiometer that detects the position of (Fig. 3);
Reference numeral 116 is a level detector which determines whether the piston 41 is at the bottom dead center, intermediate center or top dead center based on the output level of the potentiometer 115, and outputs a signal _S1 when the piston 41 is at the dead center. The signal S ₂ and the signal S ₃ are set to high level at the middle point and at the top dead center, respectively, and these signals are input to the control circuit 100 . 117 is the capping device 7 (Fig. 1, 2
118 is 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.

Operation of a specific example of a liquid jet recording device to which the invention of this application is applied (FIGS. 1 to 5) Next, referring also to the flowchart in FIG. 5, FIGS.
The operation of the device shown in the figure will be explained.

(1) Recording liquid supply and meniscus return operation When recording on a preset amount of recording material, for example, a predetermined size and a predetermined number of cut sheets, the CNT counter 100a outputs a signal indicating this and also itself is reset (step 212 in FIG. 5B. In the following, the drawing numbers will be omitted and only the step numbers will be used). This signal causes n ₁ counter 1
00b counts up "1", and the carriage motor driver 104 drives the carriage motor 4 to return the carriage 3 to the initial position (steps 221-222). Initial position detection switch
The return of the carriage 3 is confirmed by 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 between the worm gear 13 and the wheel. 14, it moves to the tip of the head unit 2. By moving the movable member 38, the suction tube 17 and the suction port 34,
The supply tube 18 and the ink supply port 33, and
Recovery tube 19 and liquid injection head tip 32
a are engaged with each other. 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 when the capping motor driver 112 is turned off, the cap 37 is pressed toward the tip of the head unit 2 by the spring 39, and the above-mentioned engagement is not released (steps 223 to 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.

Next, when a recording start signal is given from the signal output circuit 118 by operating the recording start switch SW3, for example, the capping motor driver 112
is operated again, the capping device drive motor 12 is reversed, and the movable member 38 is returned to its initial position, thereby releasing the capping of the head unit 2, making it possible to record, and completing the series of operations (step 232,... ...,,..., steps 204-208). In other words, after the meniscus returns,
Even when the pump 8 returns, the capping device 7 is maintained in a capping state with respect to the head unit 2, thereby preventing clogging of the ejection head 32 and thickening of the ink, and ensuring good recording at all times.

Furthermore, the above recording apparatus is provided with 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 the pump 8, which is a single pressure generating means. In addition, since the ink is discharged from the tip 32a of the ejection head 32 to perform meniscus recovery, ink can be supplied accurately with a simple configuration.
In addition, since meniscus recovery is performed at the same time, stable recording can be performed.Furthermore, since ink supply and meniscus recovery are performed simultaneously using a single pressure generating means, it is possible to downsize the device and reduce manufacturing costs. I can do it.

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. Because there are
Coupled with the above configuration, it is possible to configure a fluid path for ink supply and meniscus return with a simple mechanism, and the various operations described above can be performed reliably, thereby improving reliability. I can do it.

(2) Operation that only returns the meniscus When an impact is applied to the recording device, the meniscus retreats and ink ejection becomes unstable.
To explain the operation of only recovering the meniscus to prevent this, the signal output circuit 103 outputs a high level signal by operating the recovery switch SW2.
Transfer to n ₂ counter 100c, n ₂ counter 10
0c counts up "1". Subsequently, the pump motor driver 109 operates to drive the pump driving pulse motor 9 and move the piston 41 from the position A to the position B in FIG. 3. 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 and engage the capping device 7 with the head unit 2 (steps 241 to 246). . After confirming that the capping device has been reached (step 247), the operations from step 226 onward in FIG.
has descended to position B in Figure 3, and unlike the case of ink supply described above, the negative pressure in the upper chamber of the pump 8 is small, so the ink supply to the sub-tank 31 is restricted and the meniscus return operation is performed. I will do it. In this case as well, even if the pump 8 returns after the meniscus returns, the capping device 7 is maintained in the capping state.

The liquid jet recording apparatus 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. It is possible to avoid complication of the mechanism for ink supply and meniscus recovery in the recording apparatus and avoid deterioration in operability.

(3) Capping operation When one sheet of recording is completed, the timer 100e starts operating in response to an end signal from the recording device drive circuit 101 (steps 210 to 212, . . . ).
, step 201). In this example, timer 10
Although the operation of timer 100e is set to start every time recording of one sheet of recording paper is completed, the timer 100e may be set to operate every time recording of an arbitrary number of sheets, or more generally, the above-mentioned predetermined amount of recording material is completed. . The timer 100e can be reset, for example, when a recording start signal is input from the signal output circuit 118, when recording actually starts, when the operation of the timer 100e is completed, or at any time thereafter. If recording of the information to be recorded is started within the set time of the timer 100e, the capping operation is not performed and normal recording is performed.On the other hand, if recording is not started within the above set time, the above-mentioned meniscus return is performed. Actions are performed (steps 201~
205,). However, similar to the operation described above, the pump returns after the meniscus returns (step
231), the capping device 7 is held at the capping position without retracting, and for example, the signal output circuit 1
It is only when the recording start signal is input from 18 that it is evacuated (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.

According to the above device, when recording is not restarted while the timer 100e is operating, the capping device 7 is operated after the operation of the timer 100e, so that capping of the head can be reliably performed after a predetermined period of time has elapsed, and the head can be capped even if it is left unused for a long time. Ink can be prevented from evaporating from the tip of the ejecting head, and good recording can always be performed.

(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 only meniscus return operation are always constant, and Since the initial capacity W is also constant, when n ₁ and n ₂ are the number of times of ink supply and only the number of meniscus return operations, respectively, and W' is the remaining amount of ink, W' = W - (n ₁ w ₁ + n ₂ w ₂ ) holds true. Therefore n ₁ counter 10
The counter values of the 0b and _n2 counters 100c are integrated with weighting factors based on the ink supply amounts _w1 and _w2 , 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).

The above specific example is applied to a liquid jet recording device in which recording droplets are ejected from the tip of a jetting head by the contraction movement of a piezoelectric vibrator or the application of a heat pulse.
For example, when the present invention is applied to a recording device that uses an oil-based recording liquid, a rotary pump, propeller pump, jet pump, or the like can be used as the pump.

Effects of the Invention As explained in detail above, according to the present invention,
A timer that operates for a certain period of time in response to the end of recording is provided, and means is provided to operate the capping device after the timer operates if recording is not restarted while this timer is operating, thereby ensuring that the recording head is turned off after the predetermined period of time has elapsed. can carry out capping,
It is possible to prevent the recording liquid from evaporating from the tip of the recording head even if it is left for a long time.

In the present invention, a recording end signal is given to the timer every time a predetermined amount of recording is performed, such as recording on a predetermined number of recording objects or recording on an area of a predetermined length on a recording object. In response to this recording end signal, the timer starts timing operation. If recording is not restarted within the time set by the timer, the ejection port is covered with a cap. The timer is reset by restarting recording. As described above, in the present invention, not only a normal recording signal but also a recording end signal is issued, and this end signal causes the timer to start timing, so that malfunctions of the timer can be almost completely prevented. This is because, while normal recording signals are emitted in extremely large numbers, the end of recording signal is emitted over a relatively long range every time a predetermined amount of recording is done, so it can be easily and reliably distinguished, and therefore the end signal is emitted in a relatively long range. This is because capping operations based on signals can also be performed reliably.

Furthermore, if we decide to perform capping immediately when the recording signal disappears, we will have to immediately cancel capping and move on to recording operation when the next recording signal comes in, and the capping operation will require more time. A problem arises in that time is wasted and, as a result, the overall operating time of the device becomes longer. However, according to the present invention, capping is not performed and the standby state is maintained until the recording end signal is given to the timer.
When the next recording signal comes in, the recording operation can be started immediately. Therefore, according to the present invention, it is possible to provide an inkjet device that can sufficiently cope with high-speed recording.

According to the invention, since a means is provided for holding the capping device at the capping position in a state in which the meniscus is restored, clogging of the recording head and thickening of the recording liquid due to evaporation can be prevented.

According to the invention of this application,
Not only can good recording be performed at all times, but it also reduces the burden on the operator and improves the reliability of the recording device.
It is possible to improve operability.

[Brief explanation of drawings]

The drawings show a concrete array of liquid jet recording apparatuses to which the invention of this application is applied. FIG. 1 is a perspective view showing the overall structure of the liquid jet recording apparatus, and FIG. 2 shows a capping device and a capping device in the apparatus shown in FIG. 3 is a sectional view showing details of the head unit, FIG. 4 is a block diagram of the control system, and FIGS. 5A and 5B are the devices shown in FIGS. 1 to 4. FIG. 6 is a diagram illustrating the arrangement of FIGS. 5A and 5B. 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, 100 is a recording device control circuit, 100e is a counter, 118 is a recording start signal output circuit, and SW1 is a detection switch for detecting the initial position of the carriage 3.

Claims (1)

[Scope of Claims] 1. A cap for capping an ejection port for ejecting ink to perform recording; a timer that starts a timing operation in response to a recording end signal and is reset when recording is restarted; and the timer. An inkjet device comprising: control means for causing the capping to be performed when recording is not restarted within a set time. 2. The ink jet device according to claim 1, wherein the recording end signal is a signal given to the timer every time a predetermined amount of recording is performed. 3. The inkjet device according to claim 2, wherein the predetermined amount of recording is performed on a predetermined number of recording media. 4. The inkjet device according to claim 2, wherein the predetermined amount of printing is performed on an area of a predetermined length on a recording medium. 5. The inkjet device according to claim 1, wherein the resumption of recording is the input of a recording start signal. 6. The inkjet device according to claim 1, wherein the restart of recording is the start of actual recording. 7. The inkjet device according to claim 1, wherein ink is ejected from the ejection port using thermal energy. 8. The inkjet device according to claim 1, wherein ink is ejected from the ejection port using motion of an electromechanical transducer.