JPH09104111A - Ink jet recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the density irregularity caused by both of the irregularity of the emitting quantity between ink emitting orifices and the fluctuations of emitting quantity as a whole accompanying the temp. change of a head in an ink jet recording apparatus. SOLUTION: In the heat pulse consisting of the pre-pulse and main pulse for driving an emitting heater 100C, the pre-pulse is corrected on the pre-pulse width data obtained from a pre-pulse table 102 so as to correct the irregularity of emitting quality at every emitting orifice of a head and the fluctuations of emitting quantity as a whole of the head caused by the temp. change of the head is corrected on the basis of the correction data of the stop time between the pre-pulse and main pulse obtained from a stop time table 103.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus, and more particularly to correction of density unevenness caused by each ejection port of an ink jet head and correction of density unevenness due to temperature change of the ink jet head.

[0002]

2. Description of the Related Art Various ejection methods used in an ink jet recording apparatus are known. Among them, the method of ejecting ink along with expansion of bubbles generated by applying thermal energy to the ink is a high-resolution recording apparatus. It has the advantage that it can be made compact, and has been drawing attention in recent years.

The general structure of the recording head according to this system is as follows: a heating resistor that generates heat when an electric drive pulse is applied, a substrate on which electric wiring for supplying electric power to the heating resistor is formed by IC technology, and a heater. And a top plate on which a groove for a common liquid chamber for storing ink supplied to this flow path and the like are formed by etching or the like. The common liquid chamber, the flow path, and the discharge port are formed by connecting and fixing the top plate and the top plate to each other.

In order to stably form an image on a recording medium using such a recording head, it is desirable to keep the viscosity of the ink constant mainly from the viewpoint of the ink ejection amount. That is, when the temperature of the ink is low, the viscosity of the ink is high and it becomes difficult to eject the ink. On the other hand, when the temperature of the ink is high, the amount of ejected ink is large, but the evaporation is promoted. Therefore, when ejecting ink, it is desirable to set the optimum temperature for ejection.

The temperature is set by controlling the temperature of the head, so-called temperature control. One known method of controlling the head temperature is to use two pulses consisting of a pre-pulse and a main pulse for one ejection, and change the width of the pre-pulse or the pause time between the pre-pulse and the main pulse. , There is one that controls the temperature of the entire head. Another known method is to control the temperature of the entire head by turning on / off energy applied to sub-heaters other than the ejection heater.

[0006]

However, in the above-described conventional head temperature control, since the temperature adjustment is mainly performed collectively for all the ejection openings of the head and the ejection amount is corrected, ejection between ejection openings is performed. If the quantity varies, the correction may not be sufficiently performed.

The present invention has been made to solve the above problems, and corrects the variation in the ejection amount between the ejection ports and the variation in the ejection amount due to the temperature change of the head. An object of the present invention is to provide an ink jet recording apparatus capable of stabilizing the amount of ink ejected from each ejection port and obtaining a high-quality image.

[0008]

To this end, the present invention provides a plurality of ink ejection openings, and an energy generator that corresponds to the plurality of ink ejection openings and generates energy used for ejecting ink. In an inkjet recording apparatus that performs recording by ejecting ink onto a recording medium using an inkjet head provided, pauses a pre-pulse that does not lead to ink ejection and a main pulse that leads to ink ejection at one time ejection A drive unit that supplies energy to the energy generator through time to generate energy, a pre-pulse and a pause time that are supplied by the drive unit in correspondence with each of the plurality of ink ejection ports, A correction unit that corrects the discharge amount characteristic of the discharge port and the temperature of the inkjet head. And it said that there were pictures.

According to the above arrangement, the pre-pulse is corrected according to the ejection amount characteristic of each ejection port, and the rest time is corrected according to the temperature change of the entire head. It is possible to reduce the amount variation and the overall variation of the ejection amount.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is an exploded perspective view showing a main structure of a recording head that can be used in an ink jet recording apparatus according to an embodiment of the present invention.

In the figure, a recording head (hereinafter, also simply referred to as a head) has a main portion formed by joining a substrate 3 and a top plate 10. Discharge port 1 is 360 dp
There are 128 (only a part of which is shown in the figure) formed at a density of i. Each discharge port 1 is formed with an ink flow path 5, and each flow path 5 has a heating resistor 2 formed therein. Is provided. The heating resistor 2 is selectively driven by the head drive circuit to generate heat, and thereby ink droplets are ejected. The heating resistor 2 is arranged on a substrate 3 which is made of a relatively inexpensive and highly flat insulator or semiconductor such as glass or silicon, and has a SiO ₂ protective film as an upper layer so as not to come into direct contact with ink. Are formed. Electric power for causing the heating resistor 2 to generate heat is supplied to the heating resistor 2 from the head drive circuit through the lead wire and the wiring 4 formed on the substrate 3. Further, the substrate 3 is provided with a temperature sensor (not shown), which allows the overall temperature of the recording head to be detected.

FIG. 2 is a block diagram showing the structure of the drive circuit.

In the ROM 104, ejection amount data of each ejection port in the head is written. That is, RO
The M104 is provided on the substrate of the head 100, and the ejection amount data relating to each ejection port unique to the head is written therein, and when the head is attached, the content is read from the apparatus main body side as follows. FIG. 3 is a diagram showing the stored contents of the ROM 104 by the ejection amounts of the ejection ports # 1 to # 128, and shows the ejection amounts measured in advance before correction of the head 100. In the example shown in the figure, the average discharge amount is 79.7n.
g, standard deviation 5.9. Pre-pulse width 1.0μs, drive pause time 5μs, main pulse width 3μ
s, voltage 24V. As can be seen from this figure, for example, the ejection amounts of the 17th and 81st ejection ports are relatively small, and the pixels formed by this may have low density and uneven density.

Based on the information in the ROM 104,
The pre-pulse table 102 outputs pre-pulse width data so that the ejection amount of each ejection port becomes uniform. That is, the pre-pulse table 102 stores any one of the four types of pre-pulse width data described later so as to correct the ejection amount for each ejection port stored in the ROM 104 corresponding to each ejection port to a predetermined ejection amount. doing.

On the other hand, the pause time table 103 outputs the pause time between the pre-pulse and the main pulse based on the information from the temperature sensor attached to the head.
FIG. 4 is a diagram for explaining the contents of the pause time table 103. The figure shows the result of measuring the discharge amount (per discharge port) by changing the pre-pulse width T ₁ and the rest time T ₂ , the voltage is 24 V, the main pulse width T ₃ is 3 μm.
The case where it is fixed to s is shown.

As is apparent from this figure, the rest time T ₂
The higher the value, the higher the discharge amount, and
There is a linear relationship with the ejection amount in the range of 1 μs ≦ T ₂ ≦ 7 μs.

Therefore, the contents of the table 103 are such that as the temperature becomes higher within the range having the above linear relationship, the rest time T ₂
Should be shortened.

The heat pulse generation circuit 101 combines the pre-pulse width data T ₁ from the pre-pulse table 102 and the pause time from the pause time table 103 and sends four types of heat enable signals to the head 100. In the head 100, the ROM 1 is arranged so that the ejection amount of each ejection port becomes uniform
The optimum heat enable signal is selected for each ejection port by the selection signal SI based on the data of 04, and this signal is combined with the ejection data in the shift register and the latch 100B to apply a voltage pulse to the ejection heater 100C to perform ejection. To do.

FIGS. 5A to 5D show four types of heat enable signals generated by the heat pulse generation circuit 101, and the head temperature detected by the temperature sensor 100D is 25.
It shows the case of ° C.

As shown in the figure, the pre-pulse width T ₁ is
0.4, 0.8, 1.2, 1.6μ from table 102
4 types of sec are output, while the pause time table 1
From 03, the rest time T ₂ = 25 corresponding to a head temperature of 25 ° C.
By outputting 5 μsec, four types of pulse waveforms are generated.

The optimum heat enable signal is selected for each ejection port from the four types of heat enable signals obtained as described above, and ejection is performed for each ejection port of the ink jet recording head of this embodiment. Is shown in FIG. The corrected discharge amount of each discharge port becomes almost uniform, and the discharge amount averages 7
The standard deviation was 9.9 ng and the standard deviation was 2.1. As a result, it is possible to eliminate density unevenness even in actual recording.

On the other hand, FIG. 7 shows the ejection amount of each ejection port when the head temperature ΔT = 10 ° C. is increased under the same driving conditions in the same ink jet recording head as the one whose ejection amount was measured in FIG. .

Here, the average discharge amount is 85.2 ng and the standard deviation is 2.0. In this way, the ejection amount that is entirely shifted by the change in the head temperature is set to the desired ejection amount 8
In order to set the value to 0 ng, as described above, the pause time is calculated from the pause time table according to the head temperature (3 μm in the case of this embodiment).
The ejection amount is corrected by selecting s). As a result, the ejection amount of each ejection port is as shown in FIG. That is, the average discharge amount is 79.7 ng, and the standard deviation is 2.4.

As described above, the variation in the ejection amount of each ejection port of the ink jet recording head is corrected by changing the pre-pulse width, and the overall change in the ejection amount due to the head temperature is corrected by the pre-pulse and the main pulse. It is possible to obtain a uniform and stable discharge amount by performing correction by changing the pause time between the above.

The pre-pulse T shown in this embodiment is used.
The parameters of ₁ , the pause time T ₂ , and the main pulse T ₃ are not limited to the above values, and it goes without saying that appropriate parameters are used for each recording head.

(Other Embodiments) Another embodiment of the present invention will be described.

In the above-described embodiment, the optimum heat enable signal is selected for each ejection port to perform ejection amount correction, but in the present embodiment, eight ejection ports are sequentially arranged from the first ejection port. 1 block up to the 128th outlet
It is divided into 6 blocks, and the optimum heat enable signal is selected for each block to perform ejection amount correction for eliminating density unevenness, as in the above-described embodiment.

FIG. 9 is a diagram showing the ejection amount measurement result after performing the ejection amount correction for each block.

In the example shown in the figure, the average discharge amount is 78.8n.
and the standard deviation was 3.8. The ejection amount average value and standard deviation before correction of the ink jet recording head of the present embodiment are 79.7 ng as shown in the above embodiment,
Since it is 5.9, the variation after the correction according to the present embodiment is improved as compared with that before the correction. Further, in the actual recording, the density unevenness was reduced, and it was improved to the extent that it could hardly be visually recognized.

The setting of the pause time according to the temperature change of the head is the same as in the above-mentioned embodiment.

(Others) It should be noted that the present invention includes a means (for example, an electrothermal converter or a laser beam) for generating thermal energy as energy used for performing ink ejection, particularly in an ink jet recording system. An excellent effect is obtained in a recording head and a recording apparatus of a type in which the state of ink is changed by the thermal energy. This is because according to such a method, it is possible to achieve higher density and higher definition of recording.

The typical configuration and principle are described in, for example, US Pat. Nos. 4,723,129 and 4,740.
It is preferable to use the basic principle disclosed in the specification of Japanese Patent No. 796. This method is a so-called on-demand type,
Although it can be applied to any type of continuous type, in particular, in the case of the on-demand type, it can be applied to a sheet holding liquid (ink) or an electrothermal converter arranged corresponding to the liquid path. By applying at least one drive signal corresponding to the recorded information and giving a rapid temperature rise exceeding the nucleate boiling, heat energy is generated in the electrothermal transducer, and film boiling occurs on the heat acting surface of the recording head. Liquid (ink) corresponding to this drive signal on a one-to-one basis.
This is effective because air bubbles inside can be formed. The liquid (ink) is ejected through the ejection opening by the growth and contraction of the bubble to form at least one droplet. 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 a liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable. As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. If the conditions described in US Pat. No. 4,313,124 of the invention relating to the rate of temperature rise on the heat acting surface are adopted, more excellent recording can be performed.

As the configuration of the recording head, in addition to the combination configuration (a linear liquid flow path or a right-angle liquid flow path) of a discharge port, a liquid path, and an electrothermal converter as disclosed in the above-mentioned respective specifications, U.S. Pat. No. 4,558,333 and U.S. Pat. No. 44,558 which disclose a configuration in which a heat acting portion is arranged in a bending region.
A configuration using the specification of Japanese Patent No. 59600 is also included in the present invention. In addition, Japanese Unexamined Patent Publication No. 59-123670 discloses a configuration in which a common slit is used as a discharge portion of the electrothermal converter for a plurality of electrothermal converters, and an opening for absorbing a pressure wave of thermal energy is provided. The effect of the present invention is effective even if the configuration corresponding to the ejection portion is disclosed in JP-A-59-138461. That is, according to the present invention, recording can be surely and efficiently performed regardless of the form of the recording head.

Further, the present invention can be effectively applied to a full-line type recording head having a length corresponding to the maximum width of a recording medium on which a recording apparatus can record. Such a recording head may have a configuration that satisfies the length by a combination of a plurality of recording heads or a configuration as one recording head integrally formed.

In addition, even in the case of the serial type as described above, a recording head fixed to the apparatus main body or an electric connection with the apparatus main body or ink from the apparatus main body by being attached to the apparatus main body. The present invention is also effective when a replaceable chip-type recording head that can be supplied or a cartridge-type recording head in which an ink tank is provided integrally with the recording head itself is used.

It is preferable to add ejection recovery means for the recording head, preliminary auxiliary means, and the like as the constitution of the recording apparatus of the present invention since the effects of the present invention can be further stabilized. If these are specifically mentioned, the recording head is heated using capping means, cleaning means, pressurizing or suction means, an electrothermal transducer, another heating element or a combination thereof. Pre-heating means for performing the pre-heating and pre-discharging means for performing the discharging other than the recording can be used.

The type and number of recording heads to be mounted are not limited to those provided only for one color ink, and for a plurality of inks having different recording colors and densities. A plurality may be provided. That is, for example, the recording mode of the recording apparatus is not limited to the recording mode of only the mainstream color such as black, but it may be either the recording head is integrally formed or a plurality of combinations may be used. The present invention is also extremely effective for an apparatus provided with at least one of full-color recording modes by color mixing.

In addition, in the embodiment of the present invention described above, the ink is described as a liquid. However, an ink which solidifies at room temperature or lower and which softens or liquefies at room temperature may be used. In general, the ink jet method generally controls the temperature of the ink itself within a range of 30 ° C. or more and 70 ° C. or less to control the temperature so that the viscosity of the ink is in a stable ejection range. Sometimes, the ink may be in a liquid state. In addition, the temperature rise due to thermal energy is positively prevented by using it as the energy of the state change from the solid state of the ink to the liquid state, or in order to prevent the evaporation of the ink, it is solidified and heated in the standing state. You may use the ink liquefied by. In any case, by applying heat energy such as ink that is liquefied by applying heat energy according to the recording signal and liquid ink is ejected or that begins to solidify when it reaches the recording medium. The present invention can be applied to the case where an ink having a property of being liquefied for the first time is used. In this case, the ink is
JP-A-54-56847 or JP-A-60-7
As described in Japanese Patent Publication No. 1260, it is also possible to adopt a form in which the sheet is opposed to the electrothermal converter in a state where it is held as a liquid or solid substance in the concave portion or through hole of the porous sheet. In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

In addition, the form of the ink jet recording apparatus of the present invention is not only used as an image output terminal of an information processing apparatus such as a computer, but also for a copying apparatus combined with a reader or the like, and a facsimile apparatus having a transmission / reception function. It may take a form.

[0041]

As described above, according to the present invention,
Since the pre-pulse is corrected according to the ejection amount characteristic of each ejection port, and the rest time is corrected according to the temperature change of the entire head, the ejection amount variation between each ejection port and the overall ejection amount fluctuation Can be reduced.

As a result, stable ejection can be performed, and it is possible to always obtain a high-quality recorded image in which uneven density is eliminated.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a configuration of an inkjet recording head that can be used in an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration for driving a head of an inkjet recording apparatus according to an embodiment of the present invention.

FIG. 3 is a diagram showing an ink ejection amount before correction of an ink jet recording head used in an embodiment of the present invention for each ejection port.

FIG. 4 is a diagram illustrating a relationship between a pre-pulse width, a dwell time, and an ejection amount.

5A to 5D are schematic waveform diagrams of four types of heat enable signals generated in an embodiment of the present invention.

FIG. 6 is a diagram showing the ejection amount after pre-pulse correction for each ejection port in an embodiment of the present invention.

FIG. 7 is a diagram showing a change in ejection amount due to a rise in head temperature of an inkjet recording head used in an embodiment of the present invention.

FIG. 8 is a diagram showing a discharge amount after pulse rest time correction according to an embodiment of the present invention.

FIG. 9 is a diagram showing the ejection amount after prepulse correction for each ejection port block in another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Discharge port 2 Heating resistor 3 Substrate 4 Wiring 5 Ink flow path 6 Common liquid chamber 100 Head 100A Heat enable signal selection circuit 100B Shift register and latch circuit 100C Discharge heater (heating resistor) 100D Temperature sensor 101 Heat pulse generation circuit 102 Pre-pulse table 103 Rest time table 104 ROM

Claims (3)

[Claims] 1. A recording medium using an ink jet head having a plurality of ink ejection openings and an energy generator corresponding to the plurality of ink ejection openings to generate energy used for ejecting ink. In an ink jet recording apparatus for ejecting ink to perform recording, in one ejection, a pre-pulse that does not lead to ink ejection and a main pulse that leads to ink ejection are applied to the energy generator through a pause time. And a pre-pulse and a dwell time that are supplied by the driving means in correspondence with each of the plurality of ink ejection ports, the ejection amount characteristics of the ink ejection port, and the inkjet head. Ink jet characterized by comprising: Recording device. 2. The correction of the pre-pulse is to change the width of the pre-pulse.
3. The ink jet recording apparatus according to claim 1. 3. The ink jet recording apparatus according to claim 1, wherein the correction of the pre-pulse is performed for each block obtained by dividing the plurality of ink ejection ports into predetermined blocks.