JPH0358305B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an inkjet recording device that performs desired recording by ejecting ink, and more particularly to an inkjet recording device equipped with an ink supply means that contributes to supplying ink to a recording 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 miniaturized, 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) recording (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) To maintain the relative position of the head and ink tank. However, there are many design constraints, making it difficult to optimally design equipment. On the other hand, the latter method increases the load on the carriage motor due to loading enough 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. It has the disadvantage of staining the hands and equipment of the operator. 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.
Regarding ink discharge from the tip of the head, the residual ink in the ink tank decreases according to the amount of ink discharged, so it is necessary to provide a special means to detect the remaining amount of ink. Since these means must be provided separately, there is a drawback that the equipment becomes larger and the cost increases.

Purpose of the Invention The present invention has been proposed in order to improve the above-mentioned problems, and has a simple configuration, and simultaneously or selectively supplies ink to the recording head and restores the ejection state of the recording head. An object of the present invention is to provide an inkjet recording device equipped with an ink supply means that can perform the following steps.

As a result of intensive studies to achieve the above-mentioned object, the inventors of the present invention constructed an ink supply section and a suction section integrally, and each operation can be performed simultaneously or selectively by switching the pressure generated by the pressure generating means. We have come to the conclusion that the above objectives can be achieved by making the process more effective.

Structure of the invention The present invention was made based on the above-mentioned knowledge,
An inkjet recording apparatus comprising means for supplying ink from an ink storage chamber to an ink storage section in the movable recording head by engaging the movable recording head at a predetermined position within a movement range of the movable recording head. , the ink supply means includes an ink supply section that engages with an ink receiving section of the ink storage section in the movable recording head to supply ink, and an ink supply section that engages with a discharge section of the movable recording head to supply the ink. a suction unit that performs suction of the ink, and pressure generating means for causing the ink supply operation in the ink supply unit and the ink suction operation in the suction unit to be performed; and the ink supply operation and the ink suction unit. The apparatus is characterized by comprising a switching means for switching the pressure generated by the pressure generating means so that both the ink suction operation and the ink suction operation are performed at the same time or only the ink suction operation is performed.

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, a specific example of the liquid jet recording apparatus according to the present invention will be described in detail with reference to the drawings, 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.

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 a detailed explanation 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.
32 is a known ejection head; 32a is its tip; 33 is an ink supply port; and 34 is a suction port. It performs pressure control and ink discharge, and also has a level pointer 34a, which functions to keep the initial amount of ink supplied to the sub tank 31 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. Note that 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 outputs a high level signal to the control circuit 1 when the initial position detection switch SW1 of the carriage 3 is activated.
A signal output circuit 103 transfers a high level signal to the n ₂ counter 100c in the control circuit 100 when the recovery switch SW2 is activated.

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 an ink level warning indicator for the large capacity ink tank 16 (Fig. 1);
114 is its driver. 115 is a potentiometer for detecting the position of the piston 41 (FIG. 3), and 116 is a level detector.
determines whether it is at bottom dead center, intermediate point, or top dead center, and outputs signal S ₁ when it is at bottom dead center, signal S ₂ when it is at intermediate point, and signal S ₃ when it is at top dead center. These signals are set to high level and input to the control circuit 100. 117 is the capping device 7 (Fig. 1,
It is a detector that detects the position of 118
A signal output circuit 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 level warning display 113 in the above, a display device that displays the remaining level 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, 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 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 2 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. When the piston 41 reaches the top dead center, it is held by the spring 43. Next, the capping motor driver 112 operates again, the capping device driving motor 12 reverses, and the movable member 38 returns to its initial position, thereby releasing the capping of the head unit 2 and making it possible to record. is completed (steps 232, ..., ..., steps 204 to 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 meniscus recovery is performed at the same time, resulting in stable recording. Furthermore, since the ink supply and meniscus recovery are performed simultaneously by 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 meniscus recovery.
As the ink supply port 33 and the ejection head 32 in the head unit 2 are moved, these are engaged with and disengaged from the ink supply port 33 and the ejection head 32, respectively.In combination with the above-mentioned structure, ink supply and meniscus return can be performed with a simple mechanism. It is possible to configure a fluid path for the purpose, and the above-mentioned operations can be performed reliably, and reliability can be improved. Furthermore, during recording operation, there is no extra load on the carriage motor 4, such as an ink supply tube, so the inertia is reduced, the accuracy 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.

In the above device, the pump 8, which is a single pressure generating means, supplies the recording liquid and restores the meniscus, and this mode is desirable from the viewpoint of miniaturizing the device and reducing manufacturing costs. However, the present invention can also be implemented using a plurality of pressure generating means.

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 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 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 return operation.

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 injection head 32 becomes
Since the cap is released only when recording starts, it is prevented 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 possible to easily 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.

Effects of the Invention As is clear from the above description, the supply section that engages with the ink receiving section and the ink discharging section of the recording head to supply ink, and the suction section that sucks ink are integrally constructed. Therefore, the ink supply operation and suction operation to the recording head can be performed simultaneously or selectively, and a small and simple inkjet recording apparatus can be provided.

In addition, the inkjet recording device is simple and easy to operate because both the ink supply operation and the ink suction operation can be performed at the same time or only the suction operation can be performed by simply switching the pressure generated by the pressure generating means. can be provided.

[Brief explanation of drawings]

The drawings show a specific example of the liquid jet recording apparatus according to the present invention, and FIG. 1 is a perspective view showing the overall structure of the liquid jet recording apparatus, and FIG. 2 shows details of the capping device and head unit in the apparatus shown in FIG. 1. 3 is a sectional view showing details of the same 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. One set of flowcharts to be established, Figure 6 is similar to Figure 5A and Figure 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 the ink supply port, 34 is the suction port, 37 is the cap, 38 is the movable member, 39 is the spring, 41 is the piston, 43 is the spring, 46 is the valve, 113 is the remaining amount warning indicator, SW1 is the initial position of the carriage 3 The detection switch that detects is shown.

Claims (1)

[Scope of Claims] 1. Means for supplying ink from the ink storage chamber to the ink storage section in the movable recording head by engaging the movable recording head at a predetermined position within the movement range of the movable recording head. In the inkjet recording apparatus, the ink supply means includes an ink supply section that engages with an ink receiving section of the ink storage section in the movable recording head and supplies ink, and an ejection section of the movable recording head. a suction section that engages with the discharge section to suction the discharge section, and pressure generating means for causing the ink supply operation in the ink supply section and the ink suction operation placed in the suction section to be performed. , a switching means for switching the pressure generated by the pressure generating means so that both the ink supply operation and the ink suction operation are performed at the same time, or only the ink suction operation is performed. Device. 2. The pressure generating means is configured such that the pressure generated when only the ink suction operation is performed is smaller than the pressure generated when both the ink supply operation and the ink suction operation are performed simultaneously. An inkjet recording apparatus according to claim 1, characterized in that: