JP2755771B2 - Ink jet recording device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ink jet recording apparatus.

[Conventional technology]

2. Description of the Related Art Conventionally, an ink jet recording method for performing recording by discharging ink on a recording sheet (for example, US Pat. No. 4,723,312)
No. 9 and U.S. Pat. No. 4,740,796) have good responsiveness to a recording electric signal and have a discharge port (orifice).
It has advantages such as high density multi-color printing, low noise during printing, and easy color image printing by using multi-color inks. In.

FIG. 5 is an internal configuration diagram showing one conventional color copier using an ink jet recording system, and FIG. 6 is a diagram showing an ink supply system of the recording head 75 of FIG.

This color copying machine includes a reading unit 60 and a recording unit 70.

The original on which the content to be copied is written is placed on the platen 61 of the reading unit 60.
The content of the original is read by serial scanning of the original by a carriage 64 mounted thereon and having an optical system 62 and an image sensor 63 composed of a charge transfer device (CCD). The output signal of the image sensor 63 is
After being processed by a signal processing unit (not shown), it is output to the recording unit 70.

In the recording unit 70, the roll paper 71 is divided into two sets of paper feed rollers 72 and 73.
To the platen 74. At this time, the recording head
A carriage 78 having an ink tank 75, an ink tank 76, and an ink cartridge 77
One line of 71 is scanned serially, and the recording head
By driving 75 in response to a signal from the signal processing unit, the content of the original is recorded on the roll paper 71 for one line. Here, the recording head 75, the ink tank 76, and the ink cartridge 77 are provided with four sets for cyan, magenta, yellow, and black, and perform full-color recording. When the recording for one line is completed, the roll paper 71 is sub-scanned in the upward direction in the figure by the pair of sub-scanning rollers 79, and the recording for the next one line is performed in the same manner.

When the recording of one page text is completed as described above, the cutter 80 is rotated, and the roll paper 71 is cut. The cut roll paper 71 is discharged outside through two paper guides 81 and 82.

Next, details of the ink supply system of the recording head 75 mounted on the carriage 78 of the recording unit 70 will be described with reference to FIG.

The ink used for recording is supplied from the ink cartridge 77 to the ink tank 76 as appropriate. An ink tube 80 is provided between the ink tank 76 and the recording head 75. A filter 81 is provided at a connection portion of the ink tube 80 with the recording head 75 to prevent dust from entering the recording head 75 together with ink.

In addition, when the recording head 75 is filled with dust or bubbles, or when the ink in the nozzles of the recording head 75 dries and the ejection of ink becomes difficult, the cap 8 serves as a recovery means.
2, a pump 83 and a waste ink tank 84 are provided. That is, when it becomes difficult to discharge the ink,
After the cap 82 contacts the recording head 75, the pump 83 is driven to suck the ink in the nozzles of the recording head 75, and the ink is guided to the waste ink tank 84. Is removed.

[Problems to be solved by the invention]

However, in the above conventional example, the filter 81 prevents dust from entering the recording head 75, and thus has the following disadvantages.

The dust existing in the ink cartridge 77 and the ink tank 76 and the dust entering when the ink cartridge 77 is attached and detached are included in the ink, carried through the ink tube 80, and captured little by little by the filter 81. When the dust caught by the filter 81 accumulates, the flow path resistance in the filter 81 increases, and it becomes impossible to sufficiently supply the recording head 75 with ink. As a result, for example, when printing an image with a high print duty,
The supply cannot keep up with the consumption of ink, and non-ejection of ink occurs.

In particular, when the ink is pressurized so that the ink is forced to flow in by the pump 83, the amount of dust caught by the filter 81 for the following reason is smaller than when ink is supplied during printing. The present inventor has found a great deal.

Although the supply of ink for printing is performed slowly, the flow rate of the ink at the time of pressurizing the ink is high, so that the dust in the ink tank 76 can be easily carried during the pressurization of the ink.

Here, even if the flow path resistance in the filter 81 increases due to the dust being caught by the filter 81, increasing the ink supply pressure is effective to make it easier to supply the ink to the recording head 75. It is a target. To increase the ink supply pressure, to reduce the absolute value of the negative pressure,
The head difference h between the recording head 75 and the ink surface in the ink tank 76 shown in FIG. 6 may be reduced. However, the head difference h
If the ink surface in the ink tank 76 vibrates even slightly even if the ink head 76
However, the head difference h cannot be reduced from when the flow path resistance of the filter 81 is small.

An object of the present invention is to provide an ink jet recording apparatus capable of stably supplying ink even when the flow path resistance of a filter is increased.

[Means for solving the problem]

The ink jet recording apparatus of the present invention has an ink tank for storing ink, ink supply means for supplying the ink to a recording head through a filter, and ink forcibly flowing into the recording head through the filter. An ink supply pressure that increases the ink supply pressure of the ink supply means in accordance with an increase in the cumulative drive time or the cumulative number of drive times of the ink inflow means from the time of replacement of the filter. It has control means.

Further, the ink supply pressure control means is configured to adjust the height of the ink tank so that the ink supply pressure of the ink supply means increases in accordance with an increase in the cumulative drive time or the cumulative number of drive times of the ink inflow means from the time of replacement of the filter. To reduce the head difference between the recording head and the ink surface in the ink tank.

Further, the ink supply pressure control means is operated such that the ink supply pressure increases in accordance with both the increase in the cumulative drive time or the number of cumulative drives of the ink inflow means and the increase in the print time of the recording head. I do.

The recording head may be a full-line type in which discharge ports are formed over the entire width of the recording area of the recording sheet.

Further, the recording head ejects ink using thermal energy, and may include an electrothermal converter for generating the thermal energy.

[Operation] The ink jet recording apparatus of the present invention includes an ink supply pressure control unit that controls the ink supply pressure of an ink supply unit that supplies ink to a recording head via a filter by changing the height of an ink tank. By operating according to the drive history (cumulative drive count or cumulative drive time since the filter was replaced) of the ink inflow means for forcing the ink to flow into the recording head via the filter, Even if the amount of dust caught by the filter increases with the driving, and the flow path resistance of the filter increases, the ink supply pressure to the recording head is controlled by the ink supply pressure control means so that the driving history of the ink inflow means is maintained. Therefore, non-ejection of ink in the recording head can be prevented.

Further, the ink supply pressure control means increases the ink supply pressure to the recording head in accordance with both the driving history of the ink inflow means and the printing history of the recording head, so that the ink supply pressure to the filter during printing is increased. Since a large amount of dust is caught, ink can be supplied more efficiently.

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

FIG. 1 is a diagram showing an ink supply system of a recording head 5 in a first embodiment of the ink jet recording apparatus of the present invention, and FIG. 2 is a perspective view showing details of a fixture 30 of the ink tank 6 shown in FIG. FIG. 3 is a graph showing the relationship between the number of times N the pump 13 is driven and the head difference H.

The ink jet recording apparatus of this embodiment is a color copying machine having the same configuration as that shown in FIG. 5, and is different from the color copying machine shown in FIG.
It differs from the one shown in the figure.

The ink supply system is provided between an ink cartridge 7 in which refilling ink is stored, an ink tank 6 to which ink is appropriately supplied from the ink cartridge 7, and a space between the ink tank 6 and the recording head 5. Ink tube 10 and the recording head 5 of the ink tube 10
And a waste ink tank 14 provided with a filter 1 provided at a connection portion between the filter 1 and a cap 12, a pump 13, and a waste ink tank 14 provided as recovery means when ink ejection becomes difficult. Same as the ones. But,
This ink supply system differs from the conventional ink supply system in the following points.

(1) As shown in FIG. 2, the mounting member 30 of the ink tank 6 has a flat mounting base 31 provided below and two mounting frames 32 ₁ and 32 ₂ provided above. and, the two attachment frame 32 _1, 32 _2, the sleeve 33 ₁ and the sleeve 33 ₂ each having a connecting structure and the mount 31. The two sleeves 33 ₁ and 33 ₂ are supported by rails 34 ₁ and 34 ₂ erected on the base 24 (see FIG. 1) via slide bearings so as to be slidable in the vertical direction. I have.

(2) The mounting table 31 of the mounting tool 30 is as shown in FIG.
The mounting base 31 is supported by a cam 23 rotated by a pulse motor 22 provided on a base 24, and the mounting base 31 is guided by the rail 27 to move in the vertical direction by rotating the cam 23. Can be As a result, the ink tank 6 and the ink cartridge 7 attached to the attachment 30 are moved up and down, and the water head value H changes.

(3) The pump 13 and the pulse motor 22 are controlled by a central processing unit (hereinafter, referred to as a CPU) 21.

Here, the CPU 21, the pulse motor 22, and the cam 23 operate as ink supply pressure control means for controlling the ink supply pressure of the ink supplied from the ink tank 6 to the recording head 5 by moving the ink tank 6 up and down. .

The pump 13 is connected to the recording head 5 via the filter 1.
It operates as ink inflow means for forcing ink to flow into the printer.

 Next, the operation of the CPU 21 will be described.

The CPU 21 instructs the start of driving of the pump 13 and counts the number of times N of driving the pump 13. However,
The count value is reset by a reset signal input from a reset signal generating means (not shown) when the filter 1 is replaced. The CPU 21 adjusts the height of the ink tank 6 by controlling the number of rotations and the rotation direction of the pulse motor 22 according to the count value and rotating the cam 23.

The height adjustment of the ink tank 6 is based on the assumption that, when the head difference between the recording head 5 and the ink surface in the ink tank 6 is Hmm, the head difference H and the count value (the number of times N the pump 13 is driven) are the same. Control is performed so as to satisfy the relationship shown in FIG.
That is, when the filter 1 has just been replaced and is new, the flow path resistance of the filter 1 is small. Therefore, the head pressure H is set to 100 mm, the negative pressure is increased, and ink does not flow from the nozzles of the recording head 5 due to vibration or the like. Keep out of necessity. Thereafter, as the count value increases, the ink tank 6 is pushed upward, and the head difference H is reduced to reduce the negative pressure. The ink supply to the recording head 5 can be sufficiently performed, and the non-ejection of the ink of the recording head 5 due to the insufficient supply of the ink is prevented.

The attachment 30 of the ink tank 6 in this embodiment is the second attachment.
Mounting base 31, mounting frames 32 ₁ and 32 ₂ and sleeves 33 ₁ and 33 ₂ shown in the figure
Instead of using the rail 34 _1, 34 is freely integrally slide ₂ along the vertical direction and four mounting frame to be fixed by supporting both sides of and below the ink tank 6, the The bottom surface of the ink tank 6 may be supported by the cam 23.

Next, a second embodiment of the ink jet recording apparatus of the present invention will be described.

FIG. 4 is a graph showing the relationship between the drive time t of the pump 13 and the water head difference H.

The difference between the ink jet recording apparatus of the present embodiment and the first embodiment described above is that the CPU 21 controls the water head difference H between the recording head 5 and the ink surface in the ink tank 6 according to the drive time t of the pump 13. Is a point. That is, when the filter 1 has just been replaced and is new, the flow path resistance of the filter 1 is small. Therefore, the distance H is set to 100 mm and the negative pressure is increased. From going out unnecessarily. Thereafter, the CPU 21 stores the drive time t of the pump 13 and stores the drive time t in accordance with the relationship shown in FIG.
The height of the ink tank 6 is adjusted by rotating the cam 23 by controlling the number and direction of rotation of the 22.

The drive time t of the pump 13 stored in the CPU 21 is reset by a reset signal generated by a reset signal generating means (not shown) every time the filter 1 is replaced.

In the case of the present embodiment, the ink supply pressure of the ink supplied to the recording head 5 is adjusted by the driving time t of the pump 13, so that more accurate control can be performed than in the first embodiment.

Next, a third embodiment of the ink jet recording apparatus of the present invention will be described.

The ink jet recording apparatus of the present embodiment has the same ink supply system as the ink supply system shown in FIG.
The difference from the first and second embodiments is that the CPU controls and operates the pulse motor in accordance with both the drive time of the pump and the print time of the recording head.

The control of the pulse motor is performed, for example, as follows.

Assuming that the driving time of the pump is T ₁ and the printing time of the recording head is T ₂ , according to a weighted time T ₃ calculated by T ₃ = T ₁ + 0.001 · T ₂ (1) The time
T ₃ so as to reduce the water head difference H of the ink surface of the recording head and the ink tank as large, the CPU will operate by controlling the pulse motor.

In general, when the dust is clogged in the filter, but more in the driving of the pump as described above is overwhelmingly larger than during printing, the printing time T ₂ of the said recording head with respect to driving time T ₁ = 1 sec of the pump Since the time is usually about several hundred seconds, the influence of the recording head during printing cannot be ignored.

Therefore, as in the present embodiment, the drive time of the pump T ₁ and the printing time T ₂ of the said recording head, better to control the water head difference H can be performed more efficiently supply the ink.

The printing time T _{2 of the} recording head shown in the equation (1)
It is more efficient to use the optimal value obtained by experiments or the like for the coefficient of.

In the embodiment described above, the ink supply pressure to the print head was adjusted by changing the head difference H between the print head and the ink surface in the ink tank. The ink supply pressure control pump may be provided in the middle of the supply path and controlled in the same manner.

In addition, the form of the ink jet recording apparatus is the fifth.
The present invention is not limited to the color copying machine as shown in the figure, and may be, for example, a printer having only a recording unit.

The present invention provides an excellent effect particularly in an ink jet recording apparatus using a bubble jet recording head among the ink jet recording methods.

Regarding the typical configuration and principle, it is preferable to use the basic principle disclosed in, for example, US Pat. Nos. 4,723,129 and 4,740,796.
This method can be applied to both the so-called on-demand type and the continuous type. In particular, in the case of the on-demand type, it is arranged corresponding to the sheet or the liquid path holding the liquid (ink). By applying at least one drive signal corresponding to the recording information and giving a rapid temperature rise exceeding nucleate boiling to the electrothermal transducer, heat energy is generated in the electrothermal transducer, and the recording head This is effective because it is possible to form a film in the liquid (ink) by one-to-one correspondence with the drive signal as a result of film boiling on the heat-acting surface. By discharging the liquid (ink) through the discharge opening by the growth and contraction of the bubble, at least one droplet is formed. When the drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable. U.S. Pat.
Those described in JP-A Nos. 359 and 4435262 are suitable. Further, when the conditions described in US Pat. No. 4,313,124 of the invention relating to the temperature rise rate of the heat acting surface are adopted, more excellent recording can be performed.

As a configuration of the recording head, in addition to a combination configuration (a linear liquid path or a right-angled liquid path) of a discharge port, a liquid path, and an electrothermal converter as disclosed in each of the above-mentioned specifications, a heat acting section is provided. A configuration using each of those described in U.S. Pat. No. 4,558,333 and U.S. Pat. No. 4,459,600, which disclose a configuration disposed in a bending region, may be used. In addition, Japanese Patent Application Laid-Open No. S59-5959 discloses a configuration in which a common slit is used as a discharge portion of an electrothermal converter for a plurality of electrothermal converters.
No. 123670/1984 and Japanese Patent Laid-Open No. 1384/1984 discloses a configuration in which an opening for absorbing a pressure wave of thermal energy is made to correspond to a discharge portion.
The present invention is also effective as a configuration based on JP-A-61-61.

Further, 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 inkjet recording apparatus, a combination of a plurality of recording heads as disclosed in the above specification, Either a configuration that satisfies the length or a configuration as a single recording head that is integrally formed may be used, but the present invention can more effectively exert the above-described effects.

In addition, a replaceable chip-type recording head that can be electrically connected to the apparatus main body and supplied with ink from the apparatus main body by being attached to the apparatus main body, or provided 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 for the printhead, preliminary auxiliary means, and the like provided as components of the ink jet printing apparatus of the present invention since the effects of the present invention can be further stabilized. Specifically, for the recording head, a capping unit, a cleaning unit, a pressurizing or suctioning unit, a preheating unit using an electrothermal transducer or another heating element or a combination thereof, and a recording unit Separately, a preliminary ejection mode for performing ejection is also effective for stable printing.

Further, as a recording mode of the inkjet recording apparatus, not only a recording mode of only a mainstream color such as black,
The recording head may be formed integrally or by a combination of a plurality of recording heads. However, the present invention is extremely effective for an apparatus having at least one of multiple colors of different colors or full color of mixed colors.

In the embodiments of the present invention described above, the ink is described as a liquid. However, ink that solidifies at room temperature or below and softens or becomes liquid at room temperature, or is generally used in ink-jet printing. It may be softened or liquid within a temperature range of 30 ° C. or more and 70 ° C. or less, which is the temperature range of the temperature adjustment. That is, the ink may be in a liquid state when the use recording signal is applied. In addition, the temperature rise due to thermal energy can be positively prevented by using it as energy for changing the state of the ink from a solid state to a liquid state, or the ink that solidifies in a standing state to prevent evaporation of the ink can be used. Or use
In any case, the property that the ink liquefies for the first time by thermal energy, such as the one in which the ink liquefies and is ejected as an ink liquid by application of the thermal energy according to the recording signal, and the one that already starts to solidify when reaching the recording medium Is also applicable to the present invention. In such a case, the ink is disclosed in JP-A-54-56847 or JP-A-54-56847.
As described in JP-A-60-71260, a configuration may be adopted in which the liquid sheet or the solid sheet is held as a liquid or solid substance in the concave portion or through hole of the porous sheet so as to face the electrothermal converter. In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

〔The invention's effect〕

The present invention is configured as described above, and has the following effects.

Ink supply pressure control means for controlling the ink supply pressure of the ink supply means for supplying ink to the recording head via the filter by changing the height of the ink tank, etc., and supplies the ink to the recording head via the filter. By operating the ink inflow means forcibly flowing according to the driving history (cumulative number of driving times or cumulative driving time from the time of replacement of the filter), the flow of the filter along with the increase of dust caught by the filter is increased. Even if the path resistance increases, there is an effect that non-ejection of ink in the recording head can be prevented.

Further, the ink supply pressure control unit increases the ink supply pressure to the recording head according to both the driving history of the ink inflow unit and the printing history of the recording head, so that more efficient ink supply is possible. There is an effect that can be supplied.

[Brief description of the drawings]

FIG. 1 is a diagram showing an ink supply system of a recording head 5 in a first embodiment of the ink jet recording apparatus of the present invention.
FIG. 3 is a perspective view showing details of the fixture 30 of the ink tank 6 shown in FIG. 1, FIG. 3 is a graph showing the relationship between the number of times N of the pump 13 and the head difference H, and FIG. FIG. 5 is a graph showing the relationship between the driving time t and the head difference H, FIG. 5 is an internal configuration diagram showing one of the conventional color copiers using the ink jet recording system, and FIG. FIG. 3 is a diagram illustrating an ink supply system. 1 ... Filter, 5 ... Recording head, 6 ... Ink tank, 7 ... Ink cartridge, 10 ... Ink tube, 12 ... Cap, 13 ... Pump, 14 ... Waste ink tank, 21 ... CPU , 22 ... pulse motor, 23 ... cam, 2
4 ... stand, 30 ... mounting fixture, 31 ... mounting base, 32 ₁ , 32 ₂ ... mounting frame, 33 ₁ , 33 ₂ ... sleeve, 34 ₁ , 34 ₂ ... rail, H ...
... head difference, N ... number of drives, t ... drive time.

Claims (5)

(57) [Claims] An ink tank for storing ink;
An ink jet recording apparatus comprising: an ink supply unit for supplying the ink to the recording head via a filter; and an ink inflow unit for forcibly flowing the ink into the recording head via the filter. An ink supply pressure control means for increasing an ink supply pressure of the ink supply means in accordance with an increase in the cumulative drive time or the cumulative number of times of drive of the ink inflow means. 2. The ink supply pressure control means according to claim 1, wherein the ink supply pressure of the ink supply means is increased in accordance with an increase in the cumulative drive time or the cumulative number of drive times of the ink inflow means from the time of replacement of the filter. 2. An ink jet recording apparatus according to claim 1, wherein the height of the ink head is changed to reduce the head difference between the recording head and the ink surface in the ink tank. And operating the ink supply pressure control means so as to increase the ink supply pressure in accordance with both an increase in the cumulative drive time or the cumulative number of drive times of the ink inflow means and an increase in the print time of the recording head. 3. The ink jet recording apparatus according to claim 1 or 2, wherein 4. The recording head according to claim 1, wherein the recording head is a full line type in which discharge ports are formed over the entire width of a recording area of the recording sheet. Ink jet recording device. 5. The recording head according to claim 1, wherein said recording head ejects ink by using thermal energy, and comprises an electrothermal converter for generating said thermal energy. Item 5. The ink jet recording apparatus according to any one of items 4.