JPH0781061A - Liquid jet recording method - Google Patents

Abstract

PURPOSE:To enhance the printing quality, in a liquid jet recording method opposing an ink jet recording head to a recording medium to perform recording, by successively driving respective adjacent heating resistors with phase difference of a specific value or greater. CONSTITUTION:The ink droplets 19 from the ink emitting orifices 17 provided to the emitting surface 16 of a recording head arrive at a recording medium to print dots on the recording medium 18. In a sequential driving system printing the (i+1)-th sub-scanning line after the printing of the i-th sub-scanning line, when the emitting phase difference between the adjacent ink droplets 19 is 10mum or generator, the generation probability of the mutual union of the ink droplets caused by the deflection of a flight direction becomes zero. When the emitting phase difference is shorter than 10mum, one line are divided into (n) odd-number row data and (n) even-number row data and non-emission data are inserted in the gaps between the respective data to form (2n) data rows and the data are inputted to the head at a twofold speed to drive the head. At the time, the number of sub-scanning lines becomes twice. In this case, the scanning time of one line becomes n/f sec(f; clock frequency) and the emitting phase difference between adjacent ink droplets becomes 1/2f+2n/2f n/f.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording apparatus of a type in which thermal energy is used to eject ink droplets toward a recording medium.

[0002]

2. Description of the Related Art An ink jet recording apparatus of a type in which a part of ink is rapidly vaporized by pulse heating and an ink droplet is ejected from an orifice by its expansive force is disclosed in JP-A-48-9622 and JP-A-54-54. No. 51837, for example.

The simplest method of pulse heating is to energize the heating resistor with a pulse, and the specific method is Nikkei Mechanical, December 28, 1992, p. 58,
And Hewlett-Packard-Journal, Aug. 1988. The common basic configuration of these conventional heating resistors is
The thin film resistor and the thin film conductor are coated with an antioxidation layer, and one or two cavitation resistant layers are coated on the antioxidation layer for the purpose of preventing cavitation destruction of the antioxidation layer.

As a radical simplification of this complicated multi-layer structure, as described in Japanese Patent Application No. 5-68257, a heating resistor which does not require the oxidation preventing layer and the cavitation resistant layer is used. There is a method of printing. In this case, since the thin-film resistor is in direct contact with the ink (either water-based or oil-based), the rapid vaporization of the ink by pulse heating and the resulting ink ejection characteristics are greatly improved, and the thermal efficiency is greatly improved. It was possible to improve (about 30 times) and the ejection frequency. The biggest reason why we have achieved such epoch-making performance is Cr-Si-Si, which has excellent pulse resistance, oxidation resistance, cavitation resistance, and electrolytic corrosion resistance.
This is because the heating resistor made up of only the O or Ta-Si-SiO alloy thin film resistor and the thin film conductor made of Ni or W is used, and no protective layer is required.

As described above, since it is possible to eject ink with much smaller input energy as compared with the prior art,
Even if this heating resistor is formed in the vicinity of the device area on the driving LSI chip, it will no longer heat the LSI device to cause a temperature rise, and realize a monolithic LSI head with a very simple structure. Is now possible. This is as described in Japanese Patent Application Nos. 4-347150 and 5-90123 previously filed by the present applicant. This new technology enables on-demand type inkjet printheads with many ink jet nozzles to be integrated and manufactured at high density, and the number of wires that control the drive can be greatly reduced. Could also be very simplified.

[0006]

As described above, it has become possible to realize a high-speed and high-definition ink jet printer by using the ink jet print head integrated on a large scale with high density. It was found that the printing quality would be slightly deteriorated if continued.
This is because, as already pointed out in Japanese Patent Laid-Open No. 55-109672, ink droplets in flight that are adjacent to each other coalesce due to blurring in the flight direction. In the above-mentioned publication, which employs a well-known matrix driving method as a driving method of the thermal recording head, a method of forming groups of adjacent heating resistors into several blocks is used, and one or two heating resistors are arranged. This is solved by using a group of bodies as a block.

On the other hand, the method of driving the ink jet print head made by the applicant of the present invention in Japanese Patent Application Laid-Open No. 4-347150 and Japanese Patent Application Laid-Open No. 5-90125 adopts a sequential continuous driving method. With this method, the latch circuit, which was indispensable for the matrix drive method, is not required, so that the drive circuit can be made smaller and the cost can be reduced. Moreover, the required number of signal lines required for the drive can be significantly reduced and the mounting cost Reductions have also been achieved. Further, the IC of the drive circuit and the heating resistor are integrated to achieve a drastic reduction in size and cost of the inkjet print head.

An object of the present invention is to provide a recording method aimed at further improving the printing quality of an ink jet printer adopting the above-mentioned sequential continuous drive system.

[0009]

The above object is to provide a plurality of recording liquid passages respectively communicating with a plurality of ejection ports arranged in close proximity to each other, and a recording liquid supply reservoir communicating with the recording liquid passages. An ink jet recording head including a heating resistor disposed in the vicinity of the ejection port in the recording liquid passage and corresponding to each ejection port, and a drive circuit for electrically sequentially driving the heating resistors is opposed to the recording medium. In the liquid jet recording method in which recording is performed while recording is performed, the adjacent heating resistors are set to 10 μS.
This is achieved by sequentially driving with the above phase difference. Alternatively, the phase difference between adjacent heating resistors is 10
When μS or less, each adjacent heating resistor has 10
This is achieved by reconfiguring the drive signals arranged in time series so as to sequentially drive the heating resistors so that they can be driven with a phase difference of μS or more.

[0010]

In the ink jet printer constructed as described above, since the driving of the heating resistors adjacent to each other has a phase difference of at least 10 μS, ink droplets in flight adjacent to each other having a flight speed of about 10 m / S. Will be separated back and forth by a distance of at least about 10 m / S × 10 μS = 100 μm. Therefore, in the case of a normal 40 to 50 μm sphere-sized ink droplet, the occurrence of coalescence due to blur in the flight direction can be greatly reduced.

Further, since the flying ink droplets often extend a little in the flying direction, the driving phase difference between the heating resistors adjacent to each other is further increased, that is, 30 to 50 μm.
If S is set, the probability that adjacent ink droplets in flight will coalesce can be zero, and the deterioration of print quality can be completely prevented.

[0012]

EXAMPLES Examples will be described below with reference to the drawings.

FIG. 1 is a sectional view showing an example of a thermal ink jet recording head to which the present invention is applied. For example, many ink ejection ports 8 are arranged in a direction perpendicular to the paper surface of FIG.
It is arranged at 0 μm pitch (360 dpi), and the total number can be manufactured, for example, from 64 serial scan type to 1512 × 2 = 3024 line head type.
As stated in No. 3.

The characteristic of this head is that the ink ejecting heater (heat generating resistor) 2 has a thickness of, for example, about 700 Å Cr-Si.
That is, the common wiring conductor 3 and the individual wiring conductors 4 which are made of a —SiO alloy thin film resistor and which conduct electricity thereto are made of, for example, a Ni thin film conductor having a thickness of 1 μm and are not covered with any protective layer. Therefore, the input energy required for ejecting ink is very small, about 1 μJ / drop,
Compared with a conventional heating resistor with a protective layer that has been put into practical use, it can be reduced to about 1/30, which is a significant reduction. Of course,
No matter what kind of water-based ink or oil-based ink is used, it has passed the life test of 1 billion pulses or more.
57 and Japanese Patent Application No. 5-90123.

Since the required applied energy is greatly reduced in this way, the heat generating resistor 2 should be disposed on the same silicon substrate 1 in the vicinity of the drive IC section 5 for driving these heat generating resistors. It has become possible to put a small-sized and large-scale thermal inkjet printhead into practical use.

Further, this head has the following major features. This drive IC has no latch circuit and adopts a new sequential continuous drive system instead of the block drive system known in thermal print heads and the like. The circuit configuration diagram is shown in FIG.

As a driving method of the thermal ink jet print head according to the prior art, the block driving method which is well known in the thermal print head is adopted. A latch circuit (not shown) is provided between the shift register 20 and the driver 21 shown in FIG. 2, and a timing generation circuit for controlling the latch circuit is additionally provided on the head drive circuit side. It has a configuration in which two to three wirings are transmitted to the side. That is, the sequential continuous drive system shown in FIG. 2 has a smaller circuit scale, a smaller number of wires to the head side, and a lower cost than the conventional one.

Now, with the sequential continuous drive system shown in FIG.
FIG. 3 schematically shows a state in which the thermal ink jet print head shown in FIG.

Ink droplets 19 are ejected from the ink ejection openings 17 (1 to 2n) arranged on the ejection surface 16 of the head,
When it reaches the recording medium 18, it is printed in dots. Although the head 16 and the recording medium 18 are moved relative to each other, in the present case, the case where the head side is fixed and the recording medium 18 is conveyed at a constant speed in the direction perpendicular to the paper surface of FIG. 3 will be considered.

In the case of the sequential continuous drive system shown in FIG. 2, when the recording data (Aij) is sequentially sent to the shift register,
When the jth signal Aij comes to the jth register, it is transferred to the driver side. When this signal is the ejection signal (1), the j-th driver applies a voltage having a preset pulse width to the ejection heater and causes it to generate pulse heat. When Aij is the non-ejection signal (0), no voltage is applied. In this way, when all the i-th sub-scanning lines are printed ((Aij), j = 1 to 2n), the i + 1-th sub-scanning line is printed ((Ai + 1, j), j = 1 to 2n). It will be started successively. This printing method is called a sequential continuous driving method.

As described above, this sequential continuous drive method is the simplest in terms of circuit, has the least number of wirings, and is the most advantageous in terms of cost. FIG. 3A shows how the ink droplets fly when all-black printing is performed by this driving method. In this embodiment, the size of the ink droplet is about 5 in diameter.
It has a spherical shape of 0 μm or a shape slightly extending in the flight direction. And the flight speed of ink drops is about 13m / S,
When the ejection phase difference between adjacent ink droplets is 8 to 10 μS or more, the distance between adjacent ink droplets is 100 to 130 μm or more, and the probability of coalescence of ink droplets due to blurring in the flight direction is almost zero.

However, when this phase difference is shorter than 8 to 10 μS, the number of cases in which the deterioration of the printing quality due to coalescence is recognized increases. In this case, the recording data (Ai
Only by converting the arrangement of j) and changing the recording data transfer clock according to this change, it is possible to completely prevent the deterioration of the printing quality due to the above-mentioned coalescence. One of the concrete examples is (b) of FIG.

Now, the recording data (Aij) is added to the head at a clock frequency fHz, and 2n heating resistors are added to 1 / f.
Consider scanning in seconds. In this case, the phase difference for driving the adjacent heating resistors is 1/2 nf. The driving method of FIG. 3 (b) uses this (Aij)

[0024]

[Equation 1]

Is performed and the clock frequency is set to 2 fHz. here,

[0026]

[Equation 2]

Where (A, 0) + (0, A) is (A,
It means that after inputting (0) to the head, the print data of (0, A) is subsequently input.

That is, 2n print data per line is divided into n odd-row data and n even-row data, and non-ejection data is inserted between each data to 2n
Two recording data strings are created one by one, and this is input to the head and driven at twice the speed. At this time, the number of sub-scanning lines is doubled. The conversion of the print data string is performed by the signal processing circuit (CP) installed in the printer.
It is easily possible by using some functions (such as U),
It does not cause a cost increase. Also, doubling the clock frequency does not pose any problem from the performance of the shift register mounted on the head side. With this new driving method, the scanning time for one line is 1/2 f second, and the ejection phase difference between adjacent ink drops is 1/2 f + 1 / 4n.
f≈1 / 2f.

Therefore, with a 64 nozzle / line serial scan type head, the clock frequency is severe.
When the frequency is set to kHz, the ejection phase difference between adjacent ink droplets in FIG. 3A is 1/64 × 10 ⁴ = 1.56 μS, which increases the possibility of coalescence of ink droplets. In contrast,
In the case of the method (b), 1/2 × 10 ⁴ = 50 μS, and the distance between ink droplets is also 13 m / S × 50 μS = 650 μS.
m, and the deterioration of print quality is completely prevented. This situation is due to the large line head (several hundreds to several thousands).
It is clear that the more nozzles / lines) the better. In addition to the method of discharging every other one as shown in (b), other methods such as every other two methods are possible, but the most important thing is to drive the next adjacent heating resistor by 10 μS. Phase difference above, more preferably 20μ
The driving signal is reconfigured so that it can be driven with a phase difference of S or more.

Although the technical basis of this method has been mainly described above, the 128 nozzle / line head shown in FIG. 1 was actually manufactured, and the applied pulse width was 1 μS, the applied power was 1 W, and the heating resistor was pulse-heated. Were sequentially driven by a continuous driving method, all-black printing was performed on the recording medium placed on the front surface of the head, and the recording medium was conveyed while the blank printing line was provided every other line to evaluate the printing quality. The evaluation method is as follows.
Printing was performed by changing the discharge phase difference between adjacent nozzles that are successively driven in succession within a range of approximately 16 μS to approximately 1.6 μS while changing the range of 5 kHz to 5 kHz. As a result, when the ejection phase difference is 7 to 8 μS or more, the print quality does not deteriorate, or even when the ejection phase difference deteriorates, it occurs after printing for a long time, whereas when the ejection phase difference is shorter than this, the print quality deteriorates. It was found that even after the cleaning of the head surface, it was recognized relatively early.

On the other hand, the ink ejection repetition frequency is set to 5 kHz.
When printing is performed by the above-mentioned method of discharging every other portion ((b) of FIG. 3) described above, deterioration of printing quality due to coalescence of ink droplets is not recognized even in continuous printing for a long time.
We were able to confirm its effectiveness. And, as is clear, even if the ink is ejected every two nozzles, the print quality is not deteriorated, and the same result is obtained in the case of a large-scale line head. After all, it has been found that by setting the ejection phase difference of the adjacent nozzles to 10 μS or more, it is possible to prevent the print quality from deteriorating, and this is the method in which the sequential continuous drive method works most effectively.

In this embodiment, the head of the type that ejects ink droplets in the direction perpendicular to the surface of the heating resistor as shown in FIG. 1 has been described. However, in the head of the type that ejects ink droplets in the direction parallel to the surface of the heating resistor. Even in the case, the same effect can be obtained.

[0033]

According to the present invention, in the thermal ink jet print head adopting the sequential continuous drive system, it is possible to completely prevent the deterioration of the print quality which is recognized when the ink discharge nozzles are arranged at a high density. Moreover, it is possible to suppress an increase in cost due to the adoption of this method.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a thermal inkjet printhead to which the present invention is applied.

FIG. 2 is a circuit configuration diagram illustrating a sequential continuous drive system of the present invention.

FIG. 3 is a schematic diagram illustrating a drive system of the present invention.

[Explanation of symbols]

1 is a silicon substrate, 2 is a discharge heater (heating resistor),
Reference numeral 3 is a common wiring conductor, 4 is an individual wiring conductor, 5 is a drive IC portion (device region), 6 is a driver power supply wiring conductor, 7 is a drive IC signal wiring conductor, etc., 8 is an ink ejection port, and 9 is an individual ink passage. 10 is a common ink passage in the mold resin, 1
1 is a common ink passage in the silicon substrate, 12 is a connecting hole, 1
3 is a common ink passage in the frame, 14 is an ink passage forming member, 15 is a frame, 16 is a head ejection surface, 17 is an ink ejection port number, 18 is a recording medium, 19 is a flying ink droplet, 20 is a shift register, 21 is a driver.

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[Procedure amendment]

[Submission date] April 14, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0023

[Correction method] Change

[Correction content]

Now, the recording data (Aij) is applied to the head at the clock frequency fHz, and the phase difference of 2n heating resistors is applied.
Consider scanning at 1 / f second . The driving method of FIG. 3 (b) uses this (Aij)

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0028

[Correction method] Change

[Correction content]

That is, 2n print data per line is divided into n odd-row data and n even-row data, and non-ejection data is inserted between each data to 2n
Two recording data strings are created one by one, and this is input to the head and driven at twice the speed. At this time, the number of sub-scanning lines is doubled. The conversion of the print data string is performed by the signal processing circuit (CP) installed in the printer.
It is easily possible by using some functions (such as U),
It does not cause a cost increase. Also, doubling the clock frequency does not pose any problem from the performance of the shift register mounted on the head side. The scanning time for one line in this new driving method is n / f seconds, and the ejection phase difference between adjacent ink droplets is 1 / 2f + 2n / 2.
f≈n / f .

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0029

[Correction method] Change

[Correction content]

Therefore, with a serial scan type head having 64 nozzles / line, the clock frequency is 64
When the frequency is 0 kHz, the ejection phase difference between adjacent ink droplets is 1/64 × 10 ⁴ = 1.56 μS in FIG. 3A, and the possibility of coalescence of ink droplets increases. In contrast,
In the case of the method (b), 1/2 × 10 ⁴ = 50 μS, and the distance between ink droplets is also 13 m / S × 50 μS = 650 μS.
m, and the deterioration of print quality is completely prevented. This situation is due to the large line head (several hundreds to several thousands).
It is clear that the more nozzles / lines) the better. In addition to the method of discharging every other one as shown in (b), other methods such as every other two methods are possible, but the most important thing is to drive the next adjacent heating resistor by 10 μS. Phase difference above, more preferably 20μ
The driving signal is reconfigured so that it can be driven with a phase difference of S or more.

Claims (2)

[Claims] 1. A plurality of recording liquid passages respectively communicating with a plurality of ejection outlets arranged in close proximity to each other, a recording liquid supply reservoir communicating with the recording liquid passages, and ejection outlets in the recording liquid passages. Liquid jet recording in which recording is performed while an ink jet recording head including a heating resistor disposed in the vicinity corresponding to each ejection port and a drive circuit for electrically sequentially driving the heating resistor is opposed to a recording medium. In the method, a liquid jet recording method is characterized in that adjacent heating resistors are sequentially driven with a phase difference of 10 μS or more. 2. A plurality of recording liquid passages respectively communicating with a plurality of ejection outlets arranged in close proximity to each other, a recording liquid supply reservoir communicating with the recording liquid passages, and an ejection outlet in the recording liquid passages. Liquid jet recording in which recording is performed while an ink jet recording head including a heating resistor disposed in the vicinity corresponding to each ejection port and a drive circuit for electrically sequentially driving the heating resistor is opposed to a recording medium. In the method, when the phase difference between adjacent heating resistors is 10 μS or less, the heating resistors are sequentially driven in time series so that the adjacent heating resistors can be driven with a phase difference of 10 μS or more. A liquid jet recording method comprising reconstructing arranged drive signals.