JPH03292149A - Ink-jet recording device - Google Patents

Abstract

PURPOSE:To eliminate without fail alien substances that accumulate in an ink-jet recording head and cause malfunction to occur to ink-jetting by a method wherein an ink flow rate control means that changes the ink flow rate in accordance with hysteresis of forced inflow of the ink made by operation of an ink inflow means is provided to a device that makes the ink flow rate variable. CONSTITUTION:A CPU 31, a means to control ink flow rate, counts the number of operations of a pressure pump 14 (namely the number of forced inflow of the ink) and outputs driving condition-setting signals 32, in accordance with the countings, to a pump-driving electric power source 33 that drives the pressure pump 14. The driving condition-setting signals 32 act on heightening a pump-driving voltage 34 outputted from the pump-driving electric power source 33 in proportion to the increase of the countings by CPU 31. Therefore, pressurizing of the ink by operation of the pressure pump 14 can be controlled by heightening or lowering the pump-driving voltage 34, and the ink flow rate per unit hour can be varied. Thereby, in the case where the pressure loss becomes large with alien substances such as dust or the like accumulated and stuck to filters 23a and 23b, the pressure applied to the ink is increased so that the alien substances in an ink-jet recording head 12 can be discharged.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an image recording apparatus using an inkjet recording head.

[Prior Art] Inkjet recording has advantages such as easy colorization and direct recording with little noise, and is rapidly becoming popular.

FIG. 8 is a schematic cross-sectional view of a color copying machine using an inkjet recording head.

A document is placed on a document table 3° of a reading section 1', and is serially scanned and read by a reading carriage 19° equipped with a reading optical system 4' and a CCD 5'. The read signal is processed by an image processing section (not shown) and then sent to the recording section 2'.

In the recording section 2', the roll paper 6° is fed by the paper feed roller 7',
8' to the platen 10°.

On the platen 10', an inkjet recording head 12,
A recording carriage 11'' equipped with an ink tank 13, an ink cartridge 15', and a pressure pump 14'' performs serial scanning, and the inkjet recording head 12'' is driven in response to a signal from the reading section 1'' to record an image. .Inkjet recording head 12°, ink tank 13°, ink cartridge 15° and pressure pump 1
4° is equipped with four colors: cyan, magenta, yellow, and black, and performs full-color recording.
- When the recording for the digit is completed, the roll paper is sub-scanned by 6° by the sub-scanning roller 9°, and then the recording for the next digit is repeated.

When the copy rear end of the roll paper 6" reaches the position of the cutter 18", rotate the cutter 18 degrees and cut the roll paper 6".The cut and copied paper is placed in the paper guide 1.
The paper is ejected after passing through 6° and 17°.

FIG. 9 is a block diagram of the recording carriage 11' of the recording section 2°, and the same numbers as in FIG. 8 indicate the same components.

21' and 22' are ink tubes, one ink tube 21° connects the inkjet recording head 12' and the ink tank 13', and the other ink tube 22° connects the inkjet recording head 12 and the pressure pump 14'. There is. During printing, ink is supplied through the ink tube 21° by capillary action. In addition, if dust or bubbles enter the inkjet recording head 12', or if the ink in the head nozzle, which is the ink ejection opening of the inkjet recording head 12', dries and it becomes difficult to eject ink, pressurize the head. By driving the pump 14', ink is forced to flow through the ink tubes 22°, removing dirt, bubbles, and dry ink. are respectively equipped with filters 23° a and 23° b, which prevent dust from entering the inkjet recording head 12 from the ink supply side. If the nozzle opening of the recording head 12' is about 20 μm, providing a filter with a diameter of 10 μm or less can prevent intrusion of dust that can prevent ink ejection.

[Problems to be Solved by the Invention] However, in the above conventional technology, a filter is provided at the opening of the ink tube on the recording head side, and although it is highly effective in preventing the intrusion of dust, it has the following problems. There is a problem.

It is difficult to completely eliminate dust in ink cartridges and ink tanks, and it is also difficult to eliminate dust from entering when installing and removing ink cartridges. Also,
Dust may be generated from the moving parts when the pressure pump is operated. These dusts pass through the ink tubes and are captured by each filter little by little, but as the amount of dust increases, pressure loss increases and not enough ink can flow into the head.

As a result, even if the pressure pump is driven, a sufficient ink flow may not be generated within the head, and dust, bubbles, and dried ink within the head may not be removed.

Furthermore, in the case where each filter is provided on the recording head side as described above, if the amount of dust captured by each filter increases, the expensive inkjet recording head will have to be replaced as well. Further, even if each filter is provided on the ink tube side or independently, the filters themselves are not cheap, and if they have to be replaced frequently, the economic burden becomes a big problem.

Such clogging of the filter can occur even when printing is performed, but in the case of a device that uses a pressure pump to force ink to flow as described above, the clogging of the filter can occur even when printing is performed. However, the applicants have discovered that the filter through which pressurized ink passes is more likely to be clogged with dust. This is because: (1) Although the ink supply for printing is performed slowly, the ink flow caused by ink pressure is fast, so the ink flow caused by ink pressure is more likely to carry dirt in the ink tank.

■Some dust is generated in the moving parts of the pressure pump and clogs the filter.

This is thought to be due to two reasons.

The present invention has been made in view of the above-mentioned problems of the conventional technology, and even if foreign matter accumulates in the filter, it is possible to reliably remove the foreign matter that accumulates in the inkjet recording head and causes ink ejection. The purpose is to provide an inkjet recording device.

[Means for Solving the Problems] The present invention provides an inkjet recording apparatus having an ink inflow means for forcibly flowing ink into an inkjet recording head via a filter, in which the ink flow rate by the ink flow means is changed. It is characterized by having an ink flow rate variable means.

The ink flow rate variable means may include an ink flow rate control means that changes the ink flow rate according to the history of forced ink inflow by the ink inflow means. A system that counts the number of times the ink flows into the target ink flow and changes the ink flow rate by the ink flow means according to the number of times. There is a device that changes the ink flow rate by the ink inflow means.

In some cases, the ink flow rate variable means includes an ink flow rate control means for changing the ink flow rate by the ink inflow means according to the printing history of the inkjet recording apparatus. In this case, the ink flow rate control means An inkjet recording head that counts the number of sheets and changes the ink flow rate by the ink inflow means according to the number of sheets, A device that measures the time of recording and changes the ink flow rate by the ink inflow means according to that time. Some devices count the number of printing pulses supplied to the printer and change the ink flow rate by the ink inflow means according to the counted number.

Furthermore, the above-mentioned ink flow rate variable means may vary the ink flow rate per unit time by the ink inflow means;
There are cases where the ink inflow time by the ink inflow means is changed.

The inkjet recording head may be one with a plurality of ejection ports, a full-line type in which a plurality of ink ejection ports are provided over the entire width of the recording area of the recording paper, or a head that prints ink using thermal energy. It discharges heat, and may be equipped with an electrothermal converter that generates thermal energy.

[Function] The inkjet recording apparatus of the present invention uses a filter to catch foreign matter such as dust that flows into the inkjet recording head as ink is supplied to the inkjet recording head, and also to filter the inkjet recording head through the ink ejection openings of the inkjet recording head. Foreign matter, such as dried ink that adheres to the head nozzle and which causes ink failure to be ejected, is discharged by forcibly supplying ink to the inkjet recording head using an ink inlet means. The ink flow rate when ink flows,
It can be changed depending on the history of forced inflow of ink or the history of printing with an inkjet recording head. The amount of foreign matter such as dust that accumulates on the filter of an inkjet recording head and dried ink that adheres to the head nozzles is thought to increase with the amount of ink supplied to the inkjet recording head or with the progress of printing operations. According to the invention, it is possible to control the ink flow rate during forced ink inflow by taking into account the amount of these foreign substances.

[Example] Next, an example of the present invention will be described with reference to the drawings.

First, a first embodiment of the ink flow rate variable means in the inkjet recording apparatus of the present invention will be described with reference to FIG.

FIG. 1 shows an inkjet recording head 12 and ink on a recording carrier 11 disposed in a recording section 2 of a color copying machine using an inkjet recording head 12, similar to FIGS. 8 and 9 described above. FIG. 2 is a block diagram showing an ink flow rate variable means for changing the ink flow rate by a pressure pump 14 which is connected to a tank 13 and is an ink inflow means.

In FIG. 1, ink in an ink cartridge 15 is supplied to and stored in an ink tank 13, and during normal printing operation, the ink is transferred to an inkjet recording head 12 through an ink tube 21.
1 by capillary action. A filter 23a is attached to the opening of the ink tube 21 on the ink jet recording head 12 side to prevent foreign matter such as dust from entering the ink jet recording head 12. Further, the ink tank 13 is provided with a pressure pump 14 that forces ink to flow into the inkjet recording head 12, and the pressure pump 14 causes the ink in the ink tank 13 to flow into the ink tube. 22
Ink flows into the inkjet recording head 12 through the inkjet recording head 12. Similarly to the ink tube 21, this ink tube 22 is also connected to the inkjet recording head 1.
A filter 23b is provided at the opening on the second side.

The inkjet recording head 12 includes a plurality of head nozzles 3, which are ink ejection ports, over the entire width of the recording area of the recording paper.
7 are arranged in parallel, and as shown in FIG.
is provided. This electrothermal converter 38 applies ejection energy to the ink by receiving printing pulses from a printing control section (not shown).

The pressure pump 14 includes an ink flow control means C.
An ink flow rate variable means consisting of a PU 31 and a pump drive power source 33 is connected, and according to the history of forced ink flow into the ink jet recording head 12 by the pressure pump 14, the next forced ink flow is performed. When,
Controls the flow rate of ink to the inkjet recording head 12.

In this embodiment, the CPU 31, which is an ink flow rate control means, counts the number of times the pressure pump 14 is driven, that is, the number of forced ink inflows, and the pump drive that drives the pressure pump 14 according to the counted number. A drive condition setting signal 32 is output to the power supply 33. As shown in FIG. 3, this drive condition setting signal 32 is output by the pump drive power source 33 as the count number of the CPU 31 increases.
This is to increase the pump drive voltage 34 that increases the pump drive voltage 34.
The amount of pressure applied to the ink is controlled to change the ink flow rate per unit time.

Further, the CPU 31 outputs a pump drive command signal 3 to the pump drive power source 33 to instruct the drive of the pressure pump 14, that is, to instruct forced ink inflow, in accordance with an appropriate sequence such as when printing is started. When this pump drive command signal 35 is received, a pump drive voltage 34 corresponding to the drive condition setting signal 32 is outputted from the pump drive power source 33, and the pressurizing pump 14 is driven. Furthermore, CPU3
The count number of 1 is reset by a reset signal 36c applied from a print control section (not shown). This reset signal 36 is transmitted through the filter 23a, as in this embodiment.
23b is provided on the ink tube 21 or 22, when replacing the ink tube 22, and when a filter is provided on the ink jet recording head, the filter can be replaced independently when replacing the ink jet recording head. If possible, it is applied to cpυ31 when the filter is replaced.

Therefore, as is clear from FIG. 3, in this embodiment, when forcibly injecting ink immediately after replacing the filters 23a and 23b, the amount of ink pressurized by the pressurizing pump 14 is minimized to waste the ink. Reduces ink consumption, and
If the number of times the pump is driven increases and foreign matter such as dust accumulates in the filters 23a and 23b, resulting in a large pressure loss, increase the amount of pressurization to remove dust, bubbles, dried ink, etc. inside the inkjet recording head 12. This makes it possible to eject foreign matter.

Next, a second embodiment of the present invention will be described with reference to FIG.

In this embodiment, ink is forced to flow into the inkjet recording head by suction rather than by applying pressure to the ink.

In this embodiment, the inkjet recording head 12 is connected to an ink tank 13 through one ink tube 21, and ink is supplied through the ink tube 21. A filter 23 is attached to the ink tube 21 on the opening side of the inkjet recording head 12 in the same manner as described above.

Furthermore, this embodiment includes a suction pump 14a and a cap 41 that is connected to the suction pump 14a via an ink tube 43 and covers the ink ejection surface of the inkjet recording head 12. By driving the suction pump 14a while covering and sealing the ink ejection surface of the inkjet recording head 12, the inkjet recording head 12 is removed from the ink tank 13.
Force ink to flow into the ink. Note that due to this forced ink inflow, waste ink discharged from the inkjet recording head 12 is stored in the waste ink tank 42.

The suction pump 14a is driven by the CPU 31 as described above.
By setting the pump drive voltage according to the number of times the pump is driven, the increase in pressure loss caused by the filter 23 can be compensated for, and foreign matter in the inkjet recording head 12 can be removed. Remove.

Next, a third embodiment of the present invention will be described.

In the first and second embodiments described above, the pump drive voltage was changed to change the ink flow rate per unit time, but in this embodiment, the pump drive time is changed.

FIG. 5 shows the pump driving conditions in this embodiment. In this case, the pump driving time is controlled according to the number of counts. The pump driving time has the advantage that the controllable range is wider than that of the driving voltage.

Next, a fourth embodiment of the present invention will be described.

In the first to third embodiments described above, the driving conditions of the pump are controlled according to the number of times the pump is driven, but in this embodiment, the driving conditions of the pump are controlled by counting the pump driving time.

In this case, the CPU, which is the ink flow rate control means described above, counts the pump driving time and controls the pump driving conditions according to the counted value. More accurate control is possible than simply controlling according to the number of times.

Next, a fifth embodiment of the present invention will be described.

In the first to fourth embodiments described above, the ink flow rate was changed in accordance with the history of forced ink inflow by the ink inflow means, but in this embodiment, the ink flow rate was changed in accordance with the history of printing operations. let

In this case, the CPU, which is the ink flow control means described above, counts the number of copies that have been made, and
As shown in the figure, by increasing the pump driving voltage in accordance with the increase in the number of sheets counted, the ink flow rate per unit time during forced ink inflow is changed.

In addition, when the number of copies is counted as described above, the ink flow rate is controlled by controlling the drive time of the pump, that is, the time for forcibly injecting ink, as shown in Figure 7, according to the counted number. may be changed. In this case, there is an advantage that the controllable range is wider than when controlling the drive voltage of the pump.

Next, a sixth embodiment will be described.

In the fifth embodiment described above, the driving conditions of the pump were controlled according to the number of copies counted, but in this embodiment, the driving conditions of the pump are controlled by counting the printing time.

In this case, the printing time is counted by the CPU, which is the ink flow rate control means described above, and the driving conditions of the pump are controlled according to the counted value.

More accurate control is possible than simply controlling according to the number of copies.

Next, a seventh embodiment will be described.

In this embodiment, the driving conditions of the pump are controlled by counting the printing pulses applied to the inkjet recording head from a printing control section (not shown). count and
The driving conditions of the pump are controlled according to the value. More accurate control is possible than simply controlling according to the number of sheets or printing time.

In each of the above embodiments, a color copying machine using a full-line type inkjet recording head was explained as an example, but there are also printers with only a recording section, or printers in which the inkjet recording head moves back and forth across the recording area of the recording paper. It may also be possible to print while printing. Furthermore, instead of being a device that performs color printing, it may be a device that performs monochrome recording.

The present invention particularly applies to a bubble jet recording head proposed by Canon Co., Ltd. among inkjet recording systems.
This provides excellent effects in recording devices.

As for typical configurations and principles thereof, it is preferable to use the basic principles disclosed in, for example, US Pat. No. 4,723,129 and US Pat. No. 4,740,796. This method can be applied to both the so-called on-demand type and continuous type, but especially in the case of the on-demand type, it is necessary to arrange the liquid (ink) in accordance with the sheet and liquid path that hold it. By applying at least one drive signal that corresponds to recorded information and causes a rapid temperature rise exceeding nucleate boiling to the electrothermal transducer, the electrothermal transducer generates thermal energy, and the recording head This is effective because it causes film boiling on the heat acting surface of the liquid (ink), resulting in the formation of bubbles in the liquid (ink) in one-to-one correspondence with this drive signal. The growth and contraction of the bubble causes liquid (ink) to be ejected through the ejection opening to form at least one drop. When this drive signal is in the form of a pulse, bubbles grow and contract immediately and appropriately, so liquid (ink) can be ejected with particularly excellent responsiveness. Those described in Japanese Patent Nos. 4,463,359 and 4,345,262 are suitable. Incidentally, U.S. Patent No. 43 of the invention regarding the temperature increase rate of the heat acting surface
If the conditions described in the specification of No. 13124 are adopted, even more excellent recording can be performed.

The configuration of the recording head includes, in addition to the combined configuration of ejection ports, liquid paths, and electrothermal converters (straight liquid flow path or right-angled liquid flow path) as disclosed in the above-mentioned specifications, a heat acting section. US Pat. No. 4,558,333 and US Pat. No. 4,459,600 disclose a configuration in which the
The structure described in the specification may be used. In addition, Japanese Patent Application Laid-Open No. 1983 discloses a configuration in which a common slit is used as a discharge part of a plurality of electrothermal converters.
No. 23670 and Japanese Unexamined Patent Publication No. 1, 1982, which discloses a configuration in which a discharge portion is provided with an opening that absorbs pressure waves of thermal energy.
The present invention is also effective with a configuration based on Publication No. 38461.

Furthermore, as a full-line type recording head having a length corresponding to the width of the maximum recording medium that can be recorded by the recording apparatus, the length can be increased by combining multiple recording heads as disclosed in the above-mentioned specification. Either a configuration that satisfies the above requirements or a configuration as a single recording head formed integrally may be used, but the present invention can more effectively exhibit the above-mentioned effects.

In addition, a replaceable chip-type recording head that is attached to the device body enables electrical connection to the device body and ink supply from the device body, or a chip-type recording head that is installed integrally with the recording head itself. The present invention is also effective when a cartridge type recording head is used.

Further, it is preferable to add recovery means, preliminary auxiliary means, etc. for the recording head, which are provided as a configuration of the recording apparatus of the present invention, because the effects of the present invention can be further stabilized. Specifically, these include capping means, cleaning means, preheating means for the recording head using an electrothermal transducer or another heating element, or a combination thereof, and ejection other than recording. It is also effective to perform a preliminary ejection mode for performing stable recording.

In the embodiments of the present invention described above, the ink is described as a liquid, but it may be an ink that solidifies at room temperature or below, but softens or becomes a liquid at room temperature, or an ink that is generally used in inkjet. It may be one that becomes soft or liquid in the temperature range of 30° C. or higher and 70° C. or lower, which is the temperature range for temperature adjustment. That is, it is sufficient if the ink is in a liquid state when the recording signal is applied. In addition, the temperature rise caused by thermal energy can be actively prevented by using it as energy for changing the state of the ink from a solid state to a liquid state, or ink that solidifies when left unused is used to prevent ink evaporation. In any case, the ink may be liquefied by applying thermal energy in accordance with the recording signal and ejected as liquid ink, or the ink may already begin to solidify by the time it reaches the recording medium. The use of ink that is liquefied only by energy is also applicable to the present invention. In such a case, the ink may be ink as described in Japanese Patent Application Laid-Open No. 54-56847 or Japanese Patent Application Laid-Open No. 60-71260.
The porous sheet may be held as a liquid or solid in the recesses or through-holes of the porous sheet, and may face the electrothermal converter. In the present invention, the most effective method for each of the above-mentioned inks is to implement the above-mentioned film boiling method.

[Effects of the Invention] As explained above, the present invention has the following effects.

(1) The ink flow rate when forced ink flows into the inkjet recording head can be changed according to the history of the forced ink flow or the history of printing operations, so that the amount of ink captured by the filter It becomes possible to set the ink flow rate in consideration of the amount of foreign matter, and foreign matter within the inkjet recording head can be reliably removed. Furthermore, this increases the accuracy of image printing and improves the reliability of the recording device.

(2) The ink flow rate can be controlled taking into account the amount of foreign matter accumulated in the filter of the inkjet recording head, so if the amount of foreign matter is thought to be small, the ink flow rate can be restricted, making it economical. It is also advantageous.

(3) Since the ink flow rate control means can investigate the history of forced ink inflow or the history of printing operations, it is possible to set the ink flow rate when performing forced ink flow with higher precision. Become.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a first embodiment of an ink flow rate variable means in an inkjet recording apparatus of the present invention;
3 is a perspective view showing an example of an inkjet recording head, FIG. 3 is a diagram showing an example of pump drive conditions by the ink flow rate control means, FIG. 4 is a block diagram showing a second embodiment of the ink flow rate variable means, and FIG. 7 to 7 are diagrams showing examples of pump drive conditions by the ink flow rate control means, and FIGS. 8 and 9 are diagrams showing conventional examples, respectively. 12... Inkjet recording head, 13... Ink tank, 14... Pressure pump, 15... Ink cartridge, 21.22.43... Ink tube, 23... Filter, 31...・cpu. 32... Drive condition setting signal, 33... Pump drive power source, 34... Pump drive voltage, 35... Pump drive command signal, 36... Reset signal, 37... Head nozzle, 38. ...Electrothermal converter, 41...Cap, 42...Waste ink tank.

Claims (1)

[Scope of Claims] 1. An inkjet recording apparatus having an ink inflow means for forcing ink to flow into the inkjet recording head via a filter, comprising an ink flow rate variable means for changing the ink flow rate by the ink inflow means. An inkjet recording device comprising: 2. Claim 1, wherein the ink flow rate variable means has an ink flow rate control means that changes the ink flow rate according to a history of forced ink inflow by the ink inflow means.
The inkjet recording device described above. 3. The inkjet according to claim 2, wherein the ink flow rate control means counts the number of times the ink inflow means has performed forced inflow, and changes the ink flow rate by the ink inflow means according to the counted number of times. Recording device. 4. The ink flow control means according to claim 2, wherein the ink flow rate control means measures the time during which the ink flow is forcibly carried out by the ink flow means, and changes the ink flow rate by the ink flow means according to the time. Inkjet recording device. 5. The ink jet recording apparatus according to claim 1, wherein the ink flow rate variable means has an ink flow rate control means for changing the ink flow rate by the ink inflow means according to the printing history of the ink jet recording apparatus. 6. The inkjet recording apparatus according to claim 5, wherein the ink flow rate control means counts the number of recorded sheets of paper and changes the ink flow rate by the ink inflow means in accordance with the counted number of sheets. 7. The ink jet recording apparatus according to claim 5, wherein the ink flow rate control means measures the time during which recording is performed and changes the ink flow rate by the ink inflow means in accordance with the time. 8. The inkjet recording apparatus according to claim 5, wherein the ink flow rate control means counts the number of printing pulses supplied to the inkjet recording head, and changes the ink flow rate by the ink inflow means according to the counted number. . 9. The inkjet recording apparatus according to claim 1, 2, 3, 4, 5, 6, 7, or 8, wherein the ink flow rate variable means changes the ink flow rate per unit time by the ink inflow means. 10. Claim 1, wherein the ink flow rate variable means changes the ink inflow time by the ink inflow means.
, 2, 3, 4, 5, 6, 7 or 8. 11. Claims 1 and 2, wherein the inkjet recording head is equipped with a plurality of ink ejection ports.
The inkjet recording device according to 3, 4, 5, 6, 7, 8, 9 or 10. 12. The inkjet recording apparatus according to claim 11, wherein the inkjet recording head is a full-line type in which a plurality of ink ejection ports are provided over the entire width of the recording area of the recording paper. 13. Claims 1, 2, 3, 4, and 5, wherein the inkjet recording head discharges ink using thermal energy, and includes an electrothermal converter that generates thermal energy. , 6, 7, 8, 9, 10, 11 or 12.