JPH03236964A - Ink jet recorder - Google Patents

Abstract

PURPOSE:To obtain an always satisfactory recording picture equality by removing burnt deposits on a heating resistor through discharging a clear ink in a clear ink tank from a recording head at the time of operation. CONSTITUTION:When a cleaning button is pushed down, a controller 11 moves a carriage to a cleaning position, switches valves 141, 142 mutually and causes a clear ink tank 16, a recording head 13 and a waste ink tank 18 to communicate with each other. A clear ink pump 15 is operated for a predetermined period to pour a clear ink into the recording head 13. Then, the recording head 13 is made to conduct a discharge operation for a predetermined period to foam the clear ink. Subsequently, the valve 141 is switched, a color ink tank 17, the recording head 13 and waste ink tank 18 are caused to communicate with each other, and a color ink pump 152 is operated for a predetermined period to pour a color ink into the recording head 13 and a residual clear ink into the waste ink tank 18. Then, the valve 142 is switched and the color ink tank 17 and the recording head 13 are caused to communicate with each other.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inkjet recording apparatus that performs recording by attaching ink droplets to a recording material such as paper.

[Prior Art] The inkjet recording method is a recording method in which ink (recording liquid) is ejected from an orifice provided in a recording head and recorded by adhering it to a recording material such as paper. is extremely low, and high-speed recording is possible.
Furthermore, various types of recording heads have been developed because they have many advantages, such as not requiring the use of specially constructed recording paper.

Among these, a type of print head that applies thermal energy to ink to eject it from an orifice has advantages such as good responsiveness to a print signal and easy multiplication of orifices at a high density.

FIG. 7(a) is a sectional view showing the configuration of a nozzle portion of a multi-nozzle recording head conventionally used in this type of inkjet recording apparatus, and FIG. 7(b) is a perspective view thereof.

A plurality of orifices 77 are provided to eject ink to form flying droplets, a flow path 76 is provided to supply ink to each orifice 77, and heat is provided to eject ink to form flying droplets. A heat generating resistor 79 which is an energy source and is provided in a part of the flow path, an electric current Fi 173 for passing current through the heat generating resistor 79, and an ink supplied to the flow path 76 provided upstream of the flow path 76. The liquid chamber 71 for storage and the substrate 7
2, and add ink-resistant heat as needed.
] A protective film 74 or the like is provided.

Ejection of ink droplets is performed by applying a voltage to the heating resistor 79 via the electrode 73 to generate heat, thereby causing bubbles to form in the ink.

[Problems to be Solved by the Invention] The ink shed recording device as described above ejects ink droplets by generating heat in the heating resistor, but at this time, slight impurities in the ink and the dye itself may be released onto the heating element. It burns and accumulates on surfaces that come into contact with ink. Therefore, there is a problem in that the efficiency of the heating element changes over time, and the diameter of the ejected droplets changes. On the other hand, the deposits caused by this burnt (hereinafter referred to as burnt) are peeled off by cavidation, so if the heating resistor is used for a long period of time,
In L, it is common for kogae to be scattered across the area due to deposition and exfoliation. This phenomenon is unique to each nozzle.
This occurs in a head that has been used for a long time.
The surface condition of the heating element differs from one nozzle to another, and the diameter of the ejected droplets also differs from one nozzle to another. As a result, even if a head initially performs uniform recording, after a certain period of use, the diameter of the ink droplets ejected from each nozzle, that is, the diameter of the dots, will differ, and this will appear as density unevenness on the image.

Particularly in color recording where high image quality is required, even a slight change in dot diameter is easily detected by the human eye as a deterioration in image quality, which poses a problem. Furthermore, in order to perform large-format recording, a serial scan type recording method is often used that repeatedly prints with a print width of several mm to several tens of mm, but in this case, the distribution of recording dot diameters periodically appears in the image. As a result, density unevenness becomes even more noticeable. As described above, the accumulation of burnt particles is a major obstacle to high-quality recording, but until now, no technology has been devised to prevent the buildup of burnt particles or to remove them uniformly. If the recording head deteriorated, the recording head had to be replaced. This was a big disadvantage for users in terms of running costs.

SUMMARY OF THE INVENTION An object of the present invention is to provide an ink sheet printing apparatus that solves the problems listed in item L, reduces the frequency of print head replacement, and can always obtain good print quality.

[Means for Solving the Problems] An inkjet recording device of the present invention includes a recording head that ejects recording ink when a voltage is applied to a built-in heating resistor, which does not contain dye. A control device that has a clear ink tank that stores clear ink and controls the recording operation of the inkjet recording device is activated when a predetermined instruction to perform a cleaning operation is input from the outside or when the power is turned on. Clear ink supplied from the clear ink tank is ejected from the recording head during a predetermined operation such as when the recording head is turned off or when the recording head is turned down.

[Function] When clear ink containing no dye is ejected, no moss is generated on the heating resistor, and only the peeling of the moss due to cavitation occurs, so that the moss on the heating resistor is removed.

[Example] FIG. 1 is a diagram showing the main part configuration of a first example of an inkjet recording apparatus of the present invention.

In the figure, 13 is a recording head, 17 is a color ink tank that stores color ink as a recording liquid, 16 is a clear ink tank that stores clear ink, and 151 and 152 are used to fill the recording head 13 with clear ink and color ink, respectively. 12 is a pump for receiving waste ink ejected from the recording head 13, and an ink receiver 18 is for receiving waste ink ejected from the recording head 13 and preventing the ink from evaporating from the nozzle when no recording is being performed. Waste ink tanks 14, . 14
2 are recording head 13 and clear ink tank 16 respectively.
, a valve for switching the ink flow path between the color ink tank 17 and the waste ink tank 18. The valve 141 connects either the clear ink tank 16 or the color ink tank 17 to the recording head 13, and the valve 142 is recording head 1
3 to either the color ink tank 17 or the waste ink tank 18. 19 indicates each pump 15, . 152 is a pump drive circuit, 20 is a pump I″1.4..14
．． ．． 11 is a pump drive [-[
0 path 19, each pump 15+, 1 via the valve opening/closing circuit 20
52, the driving state of the outer valves 14, . 14. This is a control device that controls the opening and closing states of , and also controls the printing operation of this embodiment via the control system shown in the figure below.

In this embodiment, the clear ink stored in the clear ink tank 16 does not contain dyes that cause moss, and by continuously ejecting the clear ink, the burns inside the recording head are removed.

FIG. 2 is a flowchart showing the operation when cleaning the recording head in this embodiment.

When the user, Nagisa, confirms the deterioration of the recorded image quality and determines that a recovery operation is necessary, presses a cleaning button (not shown), the control device 11 recognizes the pressing of the cleaning button and performs the cleaning shown in FIG. Get into action.

When performing a cleaning operation, the control device 11 first checks whether the carriage on which the recording head 13 is mounted is in the cleaning position (a position facing the ink receiver 12) (Step St), and if the carriage is in the cleaning position, it is removed. Valve 14. , 142 clear ink tank 16, recording head 13 and waste ink tank 1
8 so that they communicate with each other (step S2).

If the carriage is not in the cleaning position,
4r 14 each after moving the carriage to the cleaning position (step S8).

142. Outer valve 14. , 142, the clear ink pump 151 is driven [S1 path 19
(Step S3) to flow clear ink into the recording head 13. Next, the clear ink pump 15 is operated for a certain period of time (the time during which the colored ink stored in the recording head 13 is replaced with clear ink).
Check whether the process continues (Step S4), and then stop the clear ink pump 151 (Step SS).
. Next, an ejection signal is outputted to cause the recording head 13 to perform an ejection operation (step S6), and the clear ink is foamed. As the ejection signal at this time, it is normal to send a signal corresponding to solid printing, or a signal thinned out as necessary may be sent. Next, it is checked whether the ejection operation has continued for a certain period of time (a time period during which the burnt material in the recording head 13 is almost completely peeled off) (step S7), and then the ejection operation is stopped (step S9). Next, the valve 14 is switched so that the color ink tank 17, recording head 13, and waste ink tank 18 are in communication with each other (step 5IO).
, activates the color ink pump 152 (step 511).
) Color ink is poured into the recording head 13, and clear ink remaining in the recording head 13 is poured into the waste ink tank. Next, check whether the color ink pump 152 has been operating for a certain period of time (the time during which the clear ink in the recording head 13 is replaced with color ink) in step 5.
12), and then the pump 152 is stopped (step 513). Next, the color ink tank 17, the recording head 13
The valve 142 is switched so that the color ink is circulated between the color ink tank 17 and the recording head 13 (step 514), and the program returns to the main program in which the normal recording operation is performed.

In this example, as described above, by injecting dye-free clear ink into the recording head, foaming it on the heating element, and ejecting it, it was possible to remove the burnt particles uniformly.

FIG. 3(a) is a plan view showing the state in which burnt particles 32 are deposited on the heating resistor 31 due to the recording operation, and FIG. 3(b)
is a sectional view taken along the line A-A'.

When the clear ink is ejected, the cavitation causes the burnt 32 to partially peel off as shown in the plan view of FIG. 3(C), and eventually become almost uniform as shown in the plan view of FIG. 3(d). It was possible to achieve a good surface condition.

FIGS. 4(a) to 4(c) are diagrams showing the distribution of dot diameters of recording droplets ejected from each nozzle of the recording head 13. FIG.

Figure 4 (a) is a diagram showing the distribution of dot diameters in a state where no kogation is deposited, and Figure 4 (b) is a diagram showing the distribution of dot diameters in a state where no kogation is deposited. Figure 4 (C) shows the distribution of dot diameters when the burnt deposits as shown in Figure 3(d) are accumulated or are partially peeled off. FIG. 3 is a diagram showing the distribution of dot diameters in a completely cut out state.

By performing the cleaning operation in this way, the fourth
It was possible to obtain a substantially uniform distribution of the drum diameters as shown in Figure (C), and it became possible to record good images.

In order to obtain the surface condition as shown in Fig. 3(d), 10
Between 6 and 10 pulses were required.

The time required for the cleaning operation is set at a driving frequency of 2 kHz.
z, 8 to 80 minutes are required, and the driving frequency is 5
If it is kHz, it will take 3 to 30 minutes.

FIG. 5 is a block diagram showing the main structure of a second embodiment of the present invention.

The first embodiment shows an example of a printing apparatus that performs monochrome printing, but the wood embodiment shows an example of a printing apparatus that performs multicolor printing.

The four recording heads 531 to 534 respectively print yellow (Y), magenta (M), cyan (C), and black (B).
The valve 54.k) is for recording each color, and the part into which ink is injected is the valve 54.k). ,543°545.54. There are four color ink tanks 57 for storing Y, M, C, and Bk color ink for the switching operation. ~574 each,
Alternatively, it is communicated with either the clear ink tank 56. 2 The parts from which ink is discharged are valves 542, 544, 546.
548, the four color ink tanks 57
1 to 574 or the waste ink tank 58. The clear ink tank 56 and each of the four color ink tanks 571 to 574 carry the ink stored in each tank to each recording head 53. -534 pump 55. 555 are provided, respectively. Each of these pumps 55. ~55. drive and outer valve 54. 548 are controlled by the control device 51 via the pump drive circuit 59 and the valve opening/closing circuit 60.

The control operation by the control device 51 is similar to the flowchart shown in FIG. 2 for each recording head 53. When cleaning the ink filled in ~534, clear ink tank 5 is used.
The clear ink stored in the ink receptacle 6 is ejected by moving the carriage to a position facing the ink receiver 52, so a detailed explanation will be omitted.

In each of the embodiments described above, the cleaning operation is performed when the cleaning button is pressed, but the cleaning operation may be performed automatically when the power is turned on or off. In this case, since the cleaning operation will be performed frequently, a sufficient cleaning effect can be obtained with less than 106 pulses, and the time required for the cleaning operation will be several minutes.

FIGS. 6(a) and 6(b) are flowcharts showing the control operation of the control device in the third and fourth embodiments of the present invention, respectively, which perform the lean-linking operation as described in FIG.

The one shown in FIG. 6(a) performs the cleaning operation when the power is turned on, and the one shown in FIG. 6(b) performs the cleaning operation when the power is turned off. In either case, the configuration of the main parts is the same as that of the first or second embodiment shown in FIG. 2 or FIG. 5, respectively, so a description of the configuration will be omitted and only the operation will be described.

3 4 First, a description will be given of the device shown in FIG. 6(a) which performs a cleaning operation at the time of power-on.

When the user turns on the main switch when using the device (step 561), the control device checks whether the cleaning operation has been completed (step 562), and if the cleaning operation has not been completed, the control device returns to the state shown in FIG. Perform the cleaning operation shown in the flowchart (step S
63〉. Subsequently, after confirming that the cleaning operation has been completed, a predetermined device start-up program is executed (step 564).

Next, a case will be described in which the cleaning operation is performed when the power is turned off, as shown in FIG. 6(b).

When the user turns off the main switch when terminating the device (step 565), the control device checks to see if the cleaning operation has been completed (step 366), and if the cleaning operation has not been completed, the control device returns to the state shown in FIG. 5. A leaning operation is performed as shown in the flowchart (step 567). continue,
After confirming that the cleaning operation has been completed, a predetermined device shutdown program is executed (step 868).

[Effects of the Invention] Since the present invention is configured as described above, it has the following effects.

Since burnt spots on the heating resistor are removed, it is possible to always record good images. For this reason,
It becomes possible to reduce the frequency of replacing the recording head, which has the effect of reducing running costs for users.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the main part configuration of the first embodiment of the present invention, Fig. 2 is a flowchart showing the cleaning operation in the first embodiment, and Figs. 3(a) and (b) are respectively A plan view and a cross-sectional view showing the state in which the burnt material was deposited on the heating resistor, Figure 3 (C) is a plan view showing the state in which the burnt material has partially peeled off, and Figure 3(d) shows the state in which the burnt film has been peeled off almost uniformly. Figure 4(a) is a diagram showing the dot diameter distribution of recording droplets ejected from each nozzle of the recording head in a state where no burnt deposits are present, and Figure 4(b) is a plan view showing the state. Figures 3(a), 3(b), and 3(C) show the distribution of dot diameters in a state in which burnt deposits are deposited or in a state in which it is partially peeled off. FIG. 4(C) is a diagram showing the dot diameter distribution in a state where the burnt is almost completely removed as shown in FIG. 3(d), and FIG. 5 is a diagram showing the main part of the second embodiment of the present invention. A block diagram showing the configuration, FIGS. 6(a) and (b) are flowcharts showing the control operation of the control device in the third and fourth embodiments of the present invention, and FIGS. 7(a) and (b) respectively. 1A and 1B are a cross-sectional view and a perspective view, respectively, showing the configuration of a nozzle section of a multi-nozzle recording head. 11.51...Control device, 12.52...Ink receiver, 13.53. ~534... Recording head, 14 +, 1
42, 54 + ~ 548... valve, 15 +, 152
．． 55, ~555...Pump, 16.56...Clear ink tank, 7.571-574...Color ink tank, 8.58...Waste ink tank, 9.59...Pump drive circuit , 0.60... Valve opening/closing circuit, 1... Heat generating resistor, 32... Burnt, 1 to S1
4. S61-S68...step.

Claims (1)

[Claims] 1. In an inkjet recording device equipped with a recording head that ejects recording ink when a voltage is applied to a built-in heating resistor, a clear ink tank that stores clear ink that does not contain dye is provided. The control device that controls the recording operation of the inkjet recording device is configured to perform a cleaning operation when a predetermined instruction to perform a cleaning operation is input from the outside, or during a predetermined operation such as when turning on or turning off the power. An inkjet recording apparatus characterized in that clear ink supplied from the clear ink tank is ejected from the recording head.